University of Groningen

Synthesis of novel photochromic pyrans via palladium-mediated reactionsBöttcher, Christoph; Zeyat, Gehad; Ahmed, Saleh A.; Irran, Elisabeth; Cordes, Thorben;Elsner, Cord; Zinth, Wolfgang; Rueck-Braun, KarolaPublished in:Beilstein Journal of Organic Chemistry

DOI:10.3762/bjoc.5.25

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Publication date:2009

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Citation for published version (APA):Böttcher, C., Zeyat, G., Ahmed, S. A., Irran, E., Cordes, T., Elsner, C., Zinth, W., & Rueck-Braun, K. (2009).Synthesis of novel photochromic pyrans via palladium-mediated reactions. Beilstein Journal of OrganicChemistry, 5(25), 1-7. https://doi.org/10.3762/bjoc.5.25

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S 1

Supporting Information

Synthesis of Novel Photochromic Pyrans via Palladium-Mediated Reactions

Experimental Part

C. Böttcher1, G. Zeyat1, S. A. Ahmed1,3, E. Irran1, T. Cordes2, C. Elsner2, W. Zinth2 and Karola

Rueck-Braun*,1

1Technische Universität Berlin, Institut für Chemie,

Straße des 17. Juni 135, D-10623 Berlin, Germany

2Lehrstuhl für BioMolekulare Optik, Department für Physik,

Ludwig-Maximilians-Universität München,

Oettigenstraße 67, 80538 München, Germany

2Permanent address: Chemistry Department, Faculty of Science, Assiut University,

71516 Assiut, Egypt

karola.rueck-braun@tu-berlin.de

S 2

Table of contents

Part I Synthesis and characterization

General notes S 5 – S 6

Four-step Synthesis of Compound 8b – Experimental Procedures for the

Preparation of the Precursors

4-(Allyloxy)benzonitrile1 S 7

4-(Allyloxy)benzylamine1 S 8

(9H-Fluoren-9-yl)methyl [4-(allyloxy)benzyl]carbamate S 9 – S 10

(9H-Fluoren-9-yl)methyl (4-hydroxybenzyl)carbamate (8b)1 S 10 – S 11

1,1-Bis(4-fluorophenyl)prop-2-yn-1-ol (9)1 S 11 – S 12

Experimental Procedures for the Preparation of Functionalized Benzo- and Naphthopyrans

3,3-Bis(4-fluorophenyl)-8-(methoxycarbonyl)-3H-naphtho[2,1-b]pyran (10) S 12 – S 13

2-Bromo-3,3-bis(4-fluorophenyl)-8-(methoxycarbonyl)-2,3-dihydro-

1H-naphtho[2,1-b]pyran-1-ol (11) S 13 – S 14

2-Bromo-3,3-bis(4-fluorophenyl)-8-(methoxycarbonyl)-

3H-naphtho[2,1-b]pyran (1) S 15 – S 16

2,2-Bis(4-fluorophenyl)-6-[(methoxycarbonyl)methyl]-2H-1-benzopyran (12a) S 16 – S 17

2,2-Bis(4-fluorophenyl)-6-({[(9H-fluoren-9-yl)methoxycarbonyl]amino}methyl)-

2H-1-benzopyran (12b) S 17 – S 18

3-Bromo-2,2-bis(4-fluorophenyl)-6-[(methoxycarbonyl)methyl]-

3,4-dihydro-2H-1-benzopyran-4-ol (13a) S 18 – S 19

3-Bromo-6-({[(9H-fluoren-9-yl)methoxycarbonyl]amino}methyl)-

1 Known compound.

S 3

2,2-bis(4-fluorophenyl)-3,4-dihydro-2H-1-benzopyran-4-ol (13b) S 20 – S 21

3-Bromo-2,2-bis(4-fluorophenyl)-6-[(methoxycarbonyl)methyl]-

2H-1-benzopyran (2a) S 21 – S 22

3-Bromo-2,2-bis(4-fluorophenyl)-6-({[(9H-fluoren-9-yl)methoxycarbonyl]-

amino}methyl)-2H-1-benzopyran (2b) S 22 – S 23

2-Cyano-3,3-bis(4-fluorophenyl)-8-(methoxycarbonyl)-3H-naphtho[2,1-b]pyran (3) S 24 – S 25

3-Cyano-2,2-bis(4-fluorophenyl)-6-[(methoxycarbonyl)methyl]-

2H-1-benzopyran (5a) S 26 – S 27

3-Cyano-2,2-bis(4-fluorophenyl)-6-({[(9H-fluoren-9-yl)methoxycarbonyl]amino}-

methyl-2H-1-benzopyran (5b) S 27 – S 29

2-[Bis(4-fluorophenyl)methyl]-7-(methoxycarbonyl)naphtho[2,1-b]furan (14) S 29 – S 30

3,3-Bis(4-fluorophenyl)-8-(methoxycarbonyl)-2-[(trimethylsilyl)ethinyl]-

3H-naphtho[2,1-b]pyran (4) S 31 – S 32

2,2-Bis(4-fluorophenyl)-6-({N-[(9H-fluoren-9-yl)methoxy]carbamoyl}methyl)-

2H-1-benzopyran-3-carboxylic acid (6) S 33 – S 34

Spectroscopic data

UV-vis spectra S 35 – S 40

1H NMR and 13C NMR spectra S 41 – S 63

ORTEP plots of compounds 1, 3 and 5a2 S 64 – S 66

2 The corresponding cif-files have been deposited at the Cambridge Crystallographic Data Centre

(CCDC), 12, Union Road, Cambridge CB2 1EZ, UK, and copies can be obtained on request, free

S 4

References S 67

Part II Time-resolved photophysical spectroscopy

Materials and Methods S 68 – S 69

References S 69

of charge, by quoting the publication citation and the deposition numbers 688509 (1), 688510 (3)

and 688508 (5a). These data can also be obtained free of charge via

www.ccdc.cam.ac.uk/data_request/cif, by emailing data_request@ccdc.cam.ac.uk, or by

contacting fax: +44 1223 336033.

S 5

Part I Synthesis and characterization

General notes: All starting materials and reagents were purchased in the highest available purity

and were used without further purification. All reactions were conducted in flame-dried

glassware under an atmosphere of dry nitrogen. Solvents were dried prior to use according to

standard procedures [1]. Kugelrohr distillations were performed on a Büchi KGR-51 Kugelrohr

oven. Thin layer chromatography (silica, Merck 60 F254 plates) was visualized by UV light or

potassium permanganate stain. Preparative flash-chromatography was performed on ICN

Biomedicals GmbH silica gel 60 (32 – 63 µm, 60 Å). Melting points were recorded on a melting

point apparatus using open capillary tubes and remain uncorrected. Infrared spectra were

recorded as ATR (attenuated total reflectance) on a Nicolet FT-IR 750 spectrometer and are

reported as wavenumbers in cm−1. NMR spectra were recorded on Bruker AC 200, AM 400 or

DRX 500 spectrometers. The frequencies used for 1H NMR and 13C NMR spectra are mentioned

for the particular substances. Chemical shifts are given as dimensionless δ values and coupling

constants in Hz. Solvents are mentioned for the particular substances; their residual signals were

used as internal standard. The number of protons was determined by integrating the

corresponding signals. The samples for mass spectra and high-resolution MS

(Finnigan MAT 95 SQ or Varian MAT 711 spectrometer) were ionized by EI at 70 eV, the

temperatures used to evaporate the samples are given for the particular substance. Elemental

analysis (Anal.) were recorded on an Analytik Jena Elementar Vario EL. UV-vis spectra were

recorded on a Shimadzu UV-Visible Spectrophotometer UV-1601 at a concentration of

2.5 × 10−5 M in HPLC grade acetonitrile or spectroscopic grade dichloromethane at rt. Analytical

reversed phase (RP) high-performance liquid chromatography was performed on the following

experimental setup: a Bio-Tek System 525 as pump, an Autosampler 525 Kontron Instrument as

autosampler, a Bio-Tek Diodenarraydetektor as detector and a Phenomenex Luna® as column

S 6

(5 µm, C18, 250 mm × 4.6 mm). The acquisition parameters are stated at the particular substance.

HPLC-based ratios of conversion and purity were determined at 210 nm. The acquisition

parameters are stated at the particular substance. X-ray diffraction data were collected on an

Oxford Diffraction Xcalibur S diffractometer. The diffractometer was equipped with a Sapphire

CCD detector and an enhanced monochromated MoKα source on a four-circle κ platform. The

diffraction frames were integrated by using the CrysAlisRed program, the set of data were

corrected for empirical absorption with SCALE3 ABSPACK.3 The structure was solved by direct

methods and refined using the program SHELX97.4 Compound nomenclature: According to

IUPAC recommendations 1998 (FR-2.2.7) [2] the compounds named on the basis of

1-benzopyran and naphtho[2,1-b]pyran would have to be named as the corresponding chromene

and benzo[f]chromene derivatives, respectively.

3 SCALE3 ABSPACK and CrysAlisRed (version 1.171.29.10), Oxford Diffraction Ltd,

Abingdon, Oxford, England, 2006.

4 G. M. Sheldrick, SHELX97, Program package for the solution and refinement of crystal

structures, Release 97-2, University of Göttingen, Germany, 1997.

S 7

Four-step Synthesis of Compound 8b – Experimental Procedures for the Preparation of the

Precursors

4-(Allyloxy)benzonitrile [3]

4-Hydroxybenzonitrile (23.8 g, 0.20 mol, 1.00 equiv) and K2CO3 (30.4 g, 0.22 mol,

1.10 equiv) were suspended in 20 mL acetone and magnetically stirred at rt for

20 min until a gummy slurry was obtained. Then allylbromide (17.3 mL, 0.22 mol,

1.10 equiv) was added in a single portion. The magnetically stirred slurry was gently heated to

reflux for 16 h under an ambient atmosphere until TLC monitoring indicated complete

consumption of the 4-hydroxybenzonitrile. The slurry was cooled to rt and diluted with 500 mL

of diethyl ether and 200 mL of H2O. After separation of the organic layer the water phase was

extracted with diethyl ether (5 × 200 mL). The combined organic phases were successively

washed with water (150 mL) and brine (2 × 150 mL) and were subsequently dried (MgSO4).

Evaporation of the solvent afforded 4-(allyloxy)benzonitrile in 92% yield (29.3 g, 0.19 mol) as a

colorless solid. mp: 42 – 43 °C (lit. 43 – 44 °C [4]). Rf = 0.63 (pentane/diethyl ether, 1/2).

1H NMR (200 MHz, CDCl3): δ = 7.64 – 7.50 (m, 2 H), 6.99 – 6.89 (m, 2 H), 6.12 – 5.93 (m,

1 H), 5.47 – 5.29 (m, 2 H), 4.60 – 4.56 (m, 2 H). 13C NMR (50 MHz, CDCl3): δ = 162.0 (Cq),

134.1 (CH), 132.2 (CH), 119.4 (Cq), 118.7 (CH2), 115.6 (CH), 104.3 (Cq), 69.2 (CH2). IR: (ν) =

3083 (w), 3025 (w), 2985 (w), 2925 (w), 2873 (w), 2224 (s), 1605 (s), 1508 (s), 1257 (s), 1173

(s), 995 (m), 834 (m). MS (rt): m/z (%) = 160 (10) [M+H]+, 159 (100) [M]+, 119 (25), 102 (10),

90 (12). HRMS calcd for C10H9NO, m/z: 159.0684; found: 159.0681. Anal. calcd for C10H9NO

C 75.45%, H 5.70%, N 8.80%; found: C 75.43%, H 5.70%, N 8.79%.

S 8

4-(Allyloxy)benzylamine [5]

LiAlH4 (14.4 g, 0.38 mol, 4.00 equiv) was suspended at 0 – 5 °C in 350 mL of

diethyl ether. Then 4-(allyloxy)benzonitrile (29.3 g, 0.19 mol, 1.00 equiv),

dissolved in 150 mL diethyl ether, was added dropwise within 90 min by means

of a double tip needle. The suspension was gently warmed to rt and after 30 min

TLC monitoring indicated the complete consumption of the nitrile. Unreacted LiAlH4 was

carefully neutralized by adding 60 mL of 2-propanol. The reaction mixture was poured into 2.5 L

of water and the layers were separated. The aqueous layer was subsequently extracted with

dichloromethane (6 × 500 mL). The combined organic layers were dried (MgSO4) and

concentrated in vacuo, affording the pure amine in 83% yield (25.7 g, 0.16 mol) as a colorless

liquid. Rf = 0.36 (acetone + 1 vol% NEt3).

1H NMR (200 MHz, CDCl3): δ = 7.21 – 7.14 (m, 2 H),

6.88 – 6.81 (m, 2 H), 6.11 – 5.92 (m, 1 H), 5.43 – 5.21 (m, 2 H), 4.50 – 4.45 (m, 2 H), 3.75 (s,

2 H), 1.34 (s, 2 H). 13C NMR (50 MHz, CDCl3): δ = 157.6 (Cq), 135.7 (Cq), 133.4 (CH), 128.3

(CH), 117.6 (CH2), 114.8 (CH), 68.9 (CH2), 45.9 (CH2). IR: (ν) = 3332 (br, w), 3079 (w), 3063

(w), 3030 (w), 2991 (w), 2911 (m), 2862 (m), 2625 (w), 1662 (s), 1611 (s), 1510 (s), 1369 (s),

1241 (s), 1109 (w), 1024 (m), 925 (m), 825 (m). MS (rt): m/z (%) = 164 (10) [M+H]+, 163 (100)

[M]+, 162 (95), 145 (28), 122 (92), 106 (38), 94 (44). HRMS calcd for C10H13NO, m/z: 163.0997;

found: 163.0991. Anal. calcd for C10H13NO C 73.59%, H 8.03%, N 8.58%; found: C 73.42%,

H 7.88%, N 8.40%.

S 9

(9H-Fluoren-9-yl)methyl [4-(allyloxy)benzyl]carbamate [6]

4-(Allyloxy)benzylamine (20.0 g, 0.12 mol, 1.00 equiv) was

dissolved in 300 mL of THF/water (1/1). Then NaHCO3 (13.4 g,

0.16 mol, 1.30 equiv) was added in a single portion. The

resulting solution was stirred at rt for 10 min and N-[(9H-fluoren-

9-yl)methoxycarbonyloxy]succinimide (41.3 g, 0.12 mol,

1.00 equiv) was added portionwise within 1 h. The reaction mixture was stirred at rt until TLC

monitoring indicated complete consumption of the starting material (13 h). The reaction mixture

was diluted with 600 mL of water and extracted with diethyl ether (3 × 200 mL). The combined

organic phases were washed with water (2 × 75 mL), then dried (MgSO4) and concentrated in

vacuo. The carbamate was obtained in quantitative yield (46.2 g, 0.12 mol) as colorless solid.

mp: 108 – 109 °C. Rf = 0.32 (pentane/diethyl ether, 1/1). 1H NMR (200 MHz, CDCl3):

5

δ = 7.79 – 7.75 (m, 2 H), 7.62 – 7.58 (m, 2 H), 7.45 – 7.31 (m, 4 H), 7.21 – 7.17 (m,

2 H), 6.90 – 6.86 (m, 2 H), 6.16 – 5.97 (m, 1 H), 5.47 – 5.26 (m, 2 H), 5.03 (br s, 1 H),

4.56 – 4.51 (m, 2 H), 4.46 (d, J = 6.8 Hz, 2 H), 4.33 – 4.30 (m, 2 H), 4.23 (t, J = 6.9 Hz, 1 H).

13C NMR (50 MHz, CDCl3):6 δ = 158.2 (Cq), 156.5 (Cq), 144.1 (Cq), 141.5 (Cq), 133.3 (CH),

130.8 (Cq), 129.0 (CH), 127.8 (CH), 127.2 (CH), 125.2 (CH), 120.1 (CH), 117.9 (CH2), 115.0

(CH), 69.0 (CH2), 66.7 (CH2), 47.4 (CH), 44.7 (CH2). IR: (ν) = 3329 (br, m), 3064 (w), 3039 (w),

3017 (w), 2939 (w), 2923 (w), 2884 (w), 2862 (w), 1689 (s), 1539 (m), 1255 (m), 987 (m).

MS (180 °C): m/z (%) = 385 (<1) [M]+, 207 (4), 179 (21), 178 (100), 147 (4). HRMS calcd for

5 The broad signals at δ = 7.14 – 7.02 and 5.03 ppm were assigned to the carbamate-N-H.

6 Due to the symmetry of the carbamate, its 13C NMR-spectrum contains eight signals less (i.e. a

total of C17) than there are carbon atoms from elemental analysis (C25H23NO3).

S 10

C25H23NO3, m/z: 385.1678; found: 385.1680. Anal. calcd for C25H23NO3 C 77.90%, H 6.01%,

N 3.63%; found: C 77.90%, H 5.96%, N 3.61%.

(9H-Fluoren-9-yl)methyl (4-hydroxybenzyl)carbamate (8b) [7,8]

[4-(Allyloxy)benzyl]carbamate (5.70 g, 15.0 mmol, 1.00 equiv) and

Pd(PPh3)4 (347 mg, 0.3 mmol, 2 mol%) were dissolved at rt in 150 mL

of degassed dichloromethane under an atmosphere of argon. Then

degassed acetic acid (6.90 mL, 0.12 mol, 8.00 equiv) and degassed

water (2.20 mL, 0.12 mol, 8.00 equiv) were added in a single portion.

Afterwards Bu3Sn-H (11.9 mL, 45.0 mmol, 3.00 equiv) was added dropwise within 30 min. After

additional 15 min, TLC monitoring indicated complete consumption of the starting material. The

reaction mixture was concentrated to 25% of its volume in vacuo, and then pentane was added

until the product started to precipitate. The precipitation was completed at –25 °C for 12 h. The

isolated precipitate was recrystallized from toluene/cyclohexane (3/2) affording the

hydroxycarbamate 8b in quantitative yield (5.18 g, 15.0 mmol) as a colorless solid. mp:

144 – 146 °C (lit. 128 – 130 °C [6]). Rf = 0.35 (pentane/diethyl ether, 5/9). 1H NMR (200 MHz,

CDCl3):7 δ = 7.78 – 7.74 (m, 2 H), 7.60 – 7.57 (m, 2 H), 7.43 – 7.30 (m, 5 H), 7.14 – 7.10 (m,

2 H), 6.80 – 6.76 (m, 2 H), 5.02 (br s, 1 H), 4.45 (d, J = 6.7 Hz, 2 H), 4.31 – 4.28 (m, 2 H), 4.22

(t, J = 6.8 Hz, 1 H). 13C NMR (50 MHz, acetone-d6):8 δ = 157.4 (Cq), 157.3 (Cq), 145.2 (Cq),

142.2 (Cq), 131.6 (Cq), 129.7 (CH), 128.5 (CH), 128.0 (CH), 126.2 (CH), 120.8 (CH), 116.0

(CH), 66.9 (CH2), 48.2 (CH), 44.8 (CH2). IR: (ν) = 3329 (br, m), 3066 (w), 3041 (w), 3020 (w), 7 The broad signals at δ = 7.07 – 6.91 and 5.02 ppm were assigned to the carbamate-N-H.

8 Due to the symmetry of carbamate 8b, its 13C NMR-spectrum contains eight signals less (i.e. a

total of C14) than there are carbon atoms from elemental analysis (C22H19NO3).

OH

NH

O

O

S 11

2950 (w), 2892 (w), 1695 (s), 1516 (s), 1450 (m), 1247 (br, s), 1044 (w), 987 (w), 832 (w). MS

(170 °C): m/z (%) = 345 (<1) [M]+, 180 (6), 179 (86), 178 (100), 165 (44), 107 (84). HRMS calcd

for C22H19NO3, m/z: 345.1365; found: 345.1366. Anal. calcd for C22H19NO3 C 76.50%, H 5.54%, N

4.06%; found: C 76.47%, H 5.53%, N 3.96%.

1,1-Bis(4-fluorophenyl)prop-2-yn-1-ol (9)

4,4’-Difluorobenzophenone (21.8 g, 0.10 mol, 1.00 equiv) was dissolved

at rt in 200 mL of THF. Then 400 mL of a 0.5 M ethynylmagnesium

chloride solution (0.20 mmol, 2.00 equiv) were added dropwise within

12 h. After complete addition, the reaction mixture was magnetically stirred for further 12 h at rt

until TLC monitoring indicated a complete consumption of the starting material. The solution

was diluted with 750 mL of diethyl ether and carefully hydrolysed with 200 mL of a saturated

NH4Cl solution. The separated aqueous layer was extracted with diethyl ether (3 × 350 mL). The

combined organic layers where washed with brine (2 × 150 mL), dried (MgSO4) and

concentrated in vacuo. The crude alcohol 9 was purified by two consecutive Kugelrohr

distillations (120 – 150 °C, 0.1 mbar) affording a colorless oil (17.3 g, 70.83 mmol, 71%).

Rf = 0.46 (pentane/diethyl ether, 2/1). 1H NMR (200 MHz, CDCl3): δ = 7.59 – 7.51 (m, 4 H),

7.08 – 6.96 (m, 4 H), 2.91 (s, 1 H), 2.82 (s, 1 H). 13C NMR (50 MHz, CDCl3): δ = 162.5 (d,

J(F-C) = 247 Hz, Cq), 140.2 (d, J(F-C) = 3 Hz, Cq), 128.0 (d, J(F-C) = 8 Hz, CH), 115.3 (d,

J(F-C) = 22 Hz, CH), 86.0 (Cq), 76.1 (CH), 73.5 (Cq). IR: (ν) = 3563 (br, m), 3412 (br, m), 3300

(s), 3117 (w), 3075 (w), 3048 (w), 2978 (w), 2933 (w), 2885 (w), 2119 (w), 2034 (w), 1899 (w),

1702 (m), 1603 (s), 1506 (s), 1411 (m), 1329 (m), 1224 (s), 1158 (s), 993 (s), 905 (m), 835 (s).

MS (rt): m/z (%) = 245 (14) [M+H]+, 244 (100) [M]+, 243 (42) [M–H]+, 227 (23), 215 (20), 201

S 12

(28), 149 (86), 123 (39), 95 (32). HRMS calcd for C15H10F2O, m/z: 244.0700; found: 244.0691.

Anal. calcd for C15H10F2O C 73.76%, H 4.13%; found: C 73.75%, H 4.15%.

Experimental Procedures for the Preparation of Functionalized Benzo- and Naphthopyrans

3,3-Bis(4-fluorophenyl)-8-(methoxycarbonyl)-3H-

naphtho[2,1-b]pyran (10)

Methyl 6-hydroxy-2-naphthoate (7; 2.65 g, 13.10 mmol,

1.00 equiv) and pyridinium tosylate (166 mg, 0.66 mmol,

5 mol%) were heated to reflux in 440 mL DCE (0.03 M in

naphthoate 7). Then trimethyl orthoformate (2.84 mL, 26.20 mmol, 2.00 equiv) was added in a

single portion. To this mixture the propargyl alcohol 9 (4.5 g, 18 mmol, 1.4 equiv) was added

dropwise via syringe. The mixture was heated to reflux for 20 h until TLC monitoring indicated

complete consumption of the starting material. The brown solution was cooled to rt and diluted

with 160 mL of dichloromethane. The organic layer was washed with water (50 mL) and with

brine (2 × 50 mL), concentrated in vacuo and the crude product was lyophilized. The crude

product was crystallized from ethanol (about 1 mL per 20 mg) to give naphthopyran 10 as

colorless micro crystals in 77% yield (4.3 g, 10.04 mmol). mp: 174 – 176 °C (decomposition). Rf

= 0.59 (pentane/diethyl ether, 1/1). tR = 28.6 min (flow rate: 1 mL/min, rt; eluent:

acetonitrile/water, gradient: within 25 min form 1/1 to 9/1, then pure acetonitrile). UV-vis (2.5 ×

10−5 M, acetonitrile) λmax (A): 334 nm (ε = 5104 dm3 × M−1 × cm−1), λmax (B): 261 nm (ε = 64224 dm3

× M−1 × cm−1). 1H NMR (400 MHz, CDCl3): δ = 8.48 (s, 1 H), 8.06 (d, J = 8.9 Hz, 1 H), 7.98 (d, J

= 8.8 Hz, 1 H), 7.77 (d, J = 8.9 Hz, 1 H), 7.44 – 7.41 (m, 4 H), 7.32 (d, J = 10.0 Hz, 1 H), 7.21 (d,

J = 8.8 Hz, 1 H), 7.08 – 6.96 (m, 4 H), 6.20 (d, J = 10.0 Hz, 1 H), 3.96 (s, 3 H). 13C NMR (101

S 13

MHz, CDCl3):9 δ = 167.3 (Cq), 162.4 (d, J(F-C) = 247 Hz, Cq), 152.3 (Cq), 140.3 (d, J(F-C) = 3

Hz, Cq), 132.2 (Cq), 131.8 (CH), 131.7 (CH), 128.9 (d, J(F-C) = 8 Hz, CH), 128.6 (Cq), 127.7

(CH), 126.4 (CH), 125.6 (Cq), 121.7 (CH), 119.7 (CH), 119.2 (CH), 115.3 (d, J(F-C) = 21 Hz,

CH), 114.0 (Cq), 82.3 (Cq), 52.3 (CH3). IR: (ν) = 3071 (w), 2975 (w), 2951 (w), 2845 (w), 1899

(w), 1716 (s), 1630 (m), 1622 (m), 1601 (m), 1506 (s), 1468 (s), 1435 (m), 1381 (m), 1281 (s),

1227 (s), 1210 (s), 1178 (s), 1158 (s), 1105 (s), 1084 (s), 1008 (s), 953 (m), 836 (s). MS (140 °C):

m/z (%) = 428 (50) [M]+, 397 (4), 369 (12), 333 (90), 273 (12), 244 (12), 227 (8), 201 (14), 121

(100). HRMS calcd for C27H18F2O3, m/z: 428.1224; found: 428.1229. Anal. calcd for C27H18F2O3: C

75.69%, H 4.23%; found: C 75.58%, H 4.24%.

2-Bromo-3,3-bis(4-fluorophenyl)-8-(methoxycarbonyl)-2,3-dihydro-

1H-naphtho[2,1-b]pyran-1-ol (11)

Naphthopyran 10 (4.28 g, 10.0 mmol, 1.00 equiv) was

dissolved in 60 mL DMSO (0.2 M) and magnetically stirred

at rt. Water (0.4 mL, 24.0 mmol, 2.30 equiv) was added to

the solution in a single portion followed by the portionwise

addition of NBS (4.48 g, 19.8 mmol, 1.98 equiv) over a period of 30 min. The reaction mixture

was stirred for further 60 min until only traces of starting material remained detectable by TLC

monitoring. Then the reaction mixture was poured into 350 mL of water. The aqueous phase was

extracted with ethyl acetate (5 × 50 mL). The combined organic layers were washed with 25 mL

of water and 50 mL of brine, respectively, dried (MgSO4) and concentrated in vacuo. The

remainder was purified by flash-chromatography (silica, hexane/diethyl ether, 5/1 to 3/1) 9 Due to the symmetry of naphthopyran 10, its 13C NMR-spectrum contains eight signals less

(i.e. a total of C19) than there are carbon atoms from elemental analysis (C27

H18F2O3).

S 14

affording bromohydrin 11 (4.5 g, 8.6 mmol, 86%) as an amorphous wax. Rf = 0.26

(pentane/diethyl ether, 1/1). 1H NMR (400 MHz, CDCl3): δ = 8.56 (d, J = 1.5 Hz, 1 H), 8.10 (dd,

J = 8.8 Hz, J = 1.7 Hz, 1 H), 8.06 (d, J = 8.9 Hz, 1 H), 8.00 (d, J = 9.2 Hz, 1 H), 7.74 – 7.69 (m, 2

H), 7.51 (d, J = 9.3 Hz, 1 H), 7.49 – 7.46 (m, 2H), 7.11 – 7.06 (m, 2 H), 6.96 – 6.91 (m, 2 H),

5.62 – 5.59 (m, 2 H), 3.97 (s, 3 H), 1.45 – 1.42(m, 1 H). 13C NMR (101 MHz, CDCl3):10 δ =

167.2 (Cq), 162.1 (d, J(F-C) = 249 Hz, Cq), 162.1 (d, J(F-C) = 249 Hz, Cq), 151.4 (Cq), 139.7

(m, Cq), 135.9 (d, J(F-C) = 3 Hz, Cq), 135.6 (Cq), 133.1 (CH), 131.5 (CH), 129.1 (Cq), 128.6 (d,

J(F-C) = 9 Hz, CH), 127.1 (CH), 126.6 (d, J(F-C) = 6 Hz, CH), 126.2 (Cq), 123.5 (CH), 119.6

(CH), 116.0 (d, J(F-C) = 21 Hz, CH), 115.6 (d, J(F-C) = 22 Hz, CH), 113.5 (CH), 82.1 (CH),

68.4 (CH), 55.0 (CH), 52.4 (CH3). IR: (ν) = 3572 (w), 3472 (br, w), 3072 (w), 2975 (w), 2952

(w), 2846 (w), 1716 (s), 1624 (s), 1603 (m), 1507 (s), 1472 (s), 1405 (m), 1286 (s), 1237 (s),

1210 (s), 1081 (s), 999 (s), 836 (s). MS (190 °C): m/z (%) = 526 (<1) [M{81Br}]+, 524 (<1)

[M{79Br}]+, 447 (4), 427 (8), 294 (18), 230 (36), 121 (100). HRMS calcd for C27H19BrF2O4, m/z:

524.0435; found: 524.0436. Anal. calcd for C27H19BrF2O4: C 61.73%, H 3.65%; found: C

61.54%, H 3.77%.

10 The signal at 139.7 ppm, corresponding to C-4 (see figure above), is not resolved and thus

doesn’t show the coupling constant of 4J(F-C) = 3 Hz, which is found in most of the similar

compounds (e.g. naphthopyran 10 at 140.3 ppm). Moreover, due to the symmetry of bromohydrin

11, its 13C NMR-spectrum contains four signals less (i.e. a total of C23) than there are carbon

atoms from elemental analysis (C27H19BrF2O4).

S 15

2-Bromo-3,3-bis(4-fluorophenyl)-8-(methoxycarbonyl)-3H-

naphtho[2,1-b]pyran (1)

Bromohydrin 11 was dissolved in 30 mL of toluene (5.5 g,

10.5 mmol, 1.0 equiv; 0.4 M). 4-Toluenesulfonic acid

monohydrate (303 mg, 1.6 mmol, 15 mol%) was added in a

single portion and the resulting suspension was heated to reflux for 60 min until only traces of the

starting material remained detectable by TLC monitoring. The reaction mixture was diluted with

60 mL of ethyl acetate, washed with water (4 × 10 mL), dried (MgSO4) and concentrated in

vacuo. The remainder was once triturated with cold pentane and four times crystallized from

ethanol/ethyl acetate (5/1; about 1 mL per 6 mg) to give naphthopyran 1 as pale pink crystals (2.9

g, 5.7 mmol, 54%). mp: 211 – 213 °C. Rf = 0.32 (pentane/diethyl ether, 4/1). tR = 19.9 min (flow

rate: 1 mL/min, rt; eluent: acetonitrile/water, gradient: within 20 min from 7/3 to pure

acetonitrile). UV-vis (2.5 × 10−5 M, acetonitrile) λmax (A): 335 nm (ε = 6036 dm3 × M−1 × cm−1), λmax

(B): 265 nm (ε = 59840 dm3 × M−1 × cm−1). 1H NMR (400 MHz, CDCl3): δ = 8.47 (s, 1 H), 8.07

(d, J = 8.8 Hz, 1 H), 7.92 (d, J = 8.9 Hz, 1 H), 7.79 (s, 1 H), 7.76 (d, J = 8.8 Hz, 1 H), 7.49 – 7.46

(m, 4 H), 7.17 (d, J = 8.8 Hz, 1 H), 7.06 – 7.01 (m, 4 H), 3.96 (s, 3 H). 13C NMR (101 MHz,

CDCl3):11 δ = 167.1 (Cq), 162.8 (d, J(F-C) = 248 Hz, Cq), 151.4 (Cq), 137.7 (d, J(F-C) = 4 Hz,

Cq), 132.0 (CH), 131.7 (CH), 131.2 (Cq), 130.5 (d, J(F-C) = 8 Hz, CH), 128.8 (CH), 126.7 (CH),

126.0 (Cq), 125.0 (Cq), 121.7 (CH), 120.9 (Cq), 119.0 (CH), 115.6 (Cq), 115.0 (d, J(F-C) = 22

Hz, CH), 86.6 (Cq), 52.3 (CH3). IR: (ν) = 3074 (w), 2975 (w), 2951 (w), 2844 (w), 1718 (s), 1627

(m), 1601 (m), 1586 (w), 1506 (s), 1468 (s), 1436 (w), 1384 (w), 1272 (s), 1230 (s), 1201 (s),

1160 (m), 1086 (m), 1010 (s), 961 (w), 875 (w), 837 (s). MS (170 °C): m/z (%) = 508 (<1) 11 Due to the symmetry of naphthopyran 1, its 13C NMR-spectrum contains eight signals less (i.e.

a total of C19) than there are carbon atoms from elemental analysis (C27

H17BrF2O3).

S 16

[M{81Br}]+, 506 (<1) [M{79Br}]+, 427 (100), 367 (3), 338 (3), 198 (12). HRMS calcd for

C27H17BrF2O3, m/z: 506.0329; found: 506.0325. Anal. calcd for C27H17BrF2O3: C 63.92%, H

3.38%; found: C 63.94%, H 3.46%.

2,2-Bis(4-fluorophenyl)-6-[(methoxycarbonyl)methyl]-2H-1-benzopyran (12a)

Methyl 2-(4-hydroxyphenyl)acetate (8a; 1.5 g, 9.00 mmol,

1.00 equiv) and pyridinium tosylate (113 mg, 0.45 mmol,

5 mol%) were heated to reflux in 30 mL of DCE (0.5 M in

acetate 8a). Then trimethyl orthoformate was added in a single portion (1.97 mL, 19.00 mmol,

2.12 equiv). To this mixture the propargyl alcohol 9 (2.2 g, 9.00 mmol, 1.00 equiv) was added

dropwise via a syringe. The brown solution was heated to reflux for 5 h, cooled to rt and diluted

with 100 mL of dichloromethane. The organic layer was washed with water (2 × 25 mL) and with

brine (20 mL), dried (MgSO4) and concentrated in vacuo. Purification by flash-chromatography

(silica, pentane/diethyl ether, 3/1) gave benzopyran 12a in 23% yield

(812 mg, 2.10 mmol) as a colorless solid. mp: 26 – 28 °C. Rf = 0.67 (pentane/ethyl acetate, 1/1).

tR = 12.1 min (flow rate: 1 mL/min, rt; eluent: acetonitrile/water, gradient: within 20 min from 7/3

to pure acetonitrile). UV-vis (2.5 × 10−5 M, acetonitrile) λmax (A): 316 nm (ε = 3480 dm3 × M−1 ×

cm−1), λmax (B): 273 nm (ε = 8076 dm3 × M−1 × cm−1). 1H NMR (400 MHz, CDCl3): δ = 7.36 – 7.34

(m, 4 H), 7.05 – 6.94 (m, 6 H), 6.85 – 6.83 (m, 1 H), 6.60 (d, J = 9.8 Hz, 1 H), 6.07 (d, J = 9.8

Hz, 1 H), 3.68 (s, 3 H), 3.50 (s, 2 H). 13C NMR (101 MHz, CDCl3):12

δ = 172.3 (Cq), 162.3 (d, J(F-C) = 247 Hz, Cq), 151.4 (Cq), 140.6 (d, J(F-C) = 3 Hz, Cq), 130.7

12 Due to the symmetry of benzopyran 12a, its 13C NMR-spectrum contains eight signals less (i.e.

a total of C16) than there are carbon atoms from elemental analysis (C24H18F2O3).

S 17

(CH), 128.9 (d, J(F-C) = 8 Hz, CH), 128.8 (CH), 127.6 (CH), 127.0 (Cq), 123.7 (CH), 121.1

(Cq), 116.7 (CH), 115.2 (d, J(F-C) = 21 Hz, CH), 82.0 (Cq), 52.2 (CH3), 40.4 (CH2). IR: (ν) =

3068 (w), 3043 (w), 3000 (w), 2952 (w), 2844 (w), 1736 (s), 1636 (w), 1601 (m), 1506 (s), 1435

(m), 1227 (s), 1158 (s), 991 (m), 835 (s). MS (120 °C): m/z (%) = 392 (70) [M]+, 333 (14), 297

(100), 244 (52). HRMS calcd for C24H18F2O3, m/z: 392.1224; found: 392.1223. Anal. calcd for

C24H18F2O3 C 73.46%, H 4.62%; found: C 73.22%, H 4.62%.

2,2-Bis(4-fluorophenyl)-6-({[(9H-fluoren-9-yl)methoxycarbonyl]amino}methyl)-

2H-1-benzopyran (12b) [9]

(Hydroxybenzyl)carbamate 8b (4.80 g, 14.00 mmol,

1.00 equiv) and pyridinium tosylate (176 mg, 0.70 mmol,

5 mol%) were heated to reflux in 70 mL DCE (0.2 M in

carbamate 8b). Then trimethyl orthoformate was added in a

single portion (3.10 mL, 28.00 mmol, 2.00 equiv). To this

mixture the propargyl alcohol 9 (3.80 g, 15.40 mmol,

1.10 equiv) was added dropwise via syringe. The brown solution was heated to reflux for 5 h,

cooled to rt and diluted with 200 mL of dichloromethane. The organic layer was washed with

water (2 × 25 mL) and with brine (50 mL), dried (MgSO4) and concentrated in vacuo. The crude

product was purified by flash-chromatography (silica, pentane/diethyl ether, 10/1).

Benzopyran 12b was isolated in 25% yield (2.0 g, 3.5 mmol) as a colorless solid. mp: 95 – 97 °C.

Rf = 0.37 (pentane/dichloromethane, 2/1). UV-vis (1.0 × 10−4 M; dichloromethane, spectroscopic

grade): λmax (A): 312 nm (ε = 1869 dm3 × M−1 × cm−1), λmax (B): 301 nm (ε = 5594 dm3 × M

−1 ×

S 18

cm−1), λmax (C): 292 nm (ε = 4538 dm3 × M−1 × cm−1). 1H NMR (500 MHz, CDCl3):

13 δ = 7.78 –

7.76 (m, 2 H), 7.59 – 7.58 (m, 2 H), 7.42 – 7.36 (m, 5 H), 7.32 – 7.29 (m, 2 H), 7.03 – 7.00 (m, 5

H), 6.95 (s, 1 H), 6.86 – 6.85 (m, 1 H), 6.60 (d, J = 9.8 Hz, 2 H), 6.10 (d, J = 9.8 Hz, 1 H), 5.01

(br s, 1 H), 4.45 (d, J = 6.8 Hz, 2 H), 4.26 – 4.25 (m, 2 H), 4.22 (t, J = 7.0 Hz, 1 H). 13C NMR

(126 MHz, CDCl3):14 δ = 162.3 (d, J(F-C) = 248 Hz, Cq), 156.5 (Cq), 151.7 (Cq), 144.0 (Cq),

141.5 (Cq), 140.5 (d, J(F-C) = 3 Hz, Cq), 131.6 (Cq), 129.2 (CH), 129.0 (CH), 128.9 (d, J(F-C) =

8 Hz, CH), 127.8 (CH), 127.2 (CH), 126.2 (CH), 125.1 (CH), 123.7 (CH), 121.2 (Cq), 120.1

(CH), 116.8 (CH), 115.2 (d, J(F-C) = 22 Hz, CH), 82.0 (Cq), 66.8 (CH2), 47.4 (CH), 44.7 (CH2).

IR: (ν) = 3328 (br, w), 3066 (w), 3042 (w), 2971 (w), 2943 (w), 2889 (w), 1703 (s), 1601 (m),

1507 (s), 1407 (w), 1325 (w), 1227 (s), 1127 (m), 835 (m). MS (240 °C): m/z (%) = 571 (8) [M]+,

476 (12), 393 (32), 336 (30), 178 (100), 159 (20). HRMS calcd for C37H27F2NO3, m/z: 571.1959;

found: 571.1955. Anal. calcd for C37H27F2NO3 C 77.74%, H 4.76%, N 2.45%; found: C 77.43%,

H 4.73%, N 2.40%.

3-Bromo-2,2-bis(4-fluorophenyl)-6-[(methoxycarbonyl)methyl]-3,4-dihydro-

2H-1-benzopyran-4-ol (13a)

Benzopyran 12a (804 mg, 2.05 mmol, 1.00 equiv) was

dissolved in 35 mL of DMSO (0.06 M) and magnetically

stirred at rt. Water (74 µ l, 4.10 mmol, 2.00 equiv) was added

to the solution in a single portion followed by the

13 The broad signals at δ = 4.17, 5.01, 7.25 and 7.50 were assigned to the carbamate-N-H.

14 Due to the symmetry of benzopyran 12b, its 13C NMR-spectrum contains fourteen signals less

(i.e. a total of C23) than there are carbon atoms from elemental analysis (C37H27F2NO3).

S 19

portionwise addition of NBS (927 mg, 4.10 mmol, 2.00 equiv) over a period of 30 min. The

reaction mixture was stirred for further 60 min until only traces of the starting material remained

detectable by TLC monitoring. Then, the reaction mixture was poured into 150 mL of water. The

aqueous phase was extracted with ethyl acetate (3 × 75 mL). The combined organic layers were

washed with 25 mL water of and 25 mL of brine, respectively, dried (MgSO4) and concentrated

in vacuo. The crude product was purified by flash-chromatography (silica, pentane/ethyl acetate,

5/2) affording bromohydrin 13a as a colorless solid (763 mg, 1.56 mmol, 76%). mp: 65 – 68 °C.

Rf = 0.53 (pentane/ethyl acetate, 1/1). 1H NMR (400 MHz, CDCl3): δ = 7.74 – 7.70 (m, 2 H),

7.39 – 7.34 (m, 2 H), 7.28 – 7.27 (m, 1 H), 7.25 – 7.23 (m, 1 H), 7.09 – 6.94 (m, 5 H), 5.18 – 5.17

(m, 1 H), 5.10 – 5.06 (m, 1 H), 3.69 (s, 3 H), 3.55 (s, 2 H), 2.02 – 2.00 (m, 1 H). 13C NMR

(101 MHz, CDCl3):15 δ = 172.2 (Cq), 162.4 (d, J(F-C) = 248 Hz, Cq), 162.2 (d, J(F-C) = 248 Hz,

Cq), 151.1 (Cq), 137.7 (d, J(F-C) = 3 Hz, Cq), 137.4 (d, J(F-C) = 3 Hz, Cq), 131.5 (CH), 130.3

(CH), 129.1 (d, J(F-C) = 8 Hz, CH), 128.6 (d, J(F-C) = 8 Hz, CH), 127.9 (Cq), 122.4 (Cq), 117.8

(CH), 115.6 (d, J(F-C) = 21 Hz, CH), 115.5 (d, J(F-C) = 21 Hz, CH), 83.1 (Cq), 70.2 (CH), 58.8

(CH), 52.2 (CH3), 40.3 (CH2). IR: (ν) = 3409 (br, w), 3069 (w), 2952 (w), 2929 (w), 2854 (w),

1735 (m), 1602 (m), 1507 (s), 1498 (s), 1437 (m), 1231 (s), 1162 (s), 1015 (m), 839 (m). MS

(180 °C): m/z (%) = 490 (4) [M{81Br}]+, 488 (4) [M{79Br}]+, 473 (16), 471 (16), 391 (80), 331

(10), 296 (100), 215 (42), 194 (26). HRMS calcd for C24H19BrF2O4, m/z: 488.0435; found:

488.0434. Anal. calcd for C24H19BrF2O4: C 58.91%, H 3.91%; found: C 58.56%, H 3.98%.

15 Due to the symmetry of bromohydrin 13a, its 13C NMR-spectrum contains four signals less

(i.e. a total of C20) than there are carbon atoms from elemental analysis (C24H19BrF2O4).

S 20

3-Bromo-6-({[(9H-fluoren-9-yl)methoxycarbonyl]amino}methyl)-2,2-bis(4-fluorophenyl)-

3,4-dihydro-2H-1-benzopyran-4-ol (13b) [10]

Benzopyran 12b (2.00 g, 3.50 mmol, 1.00 equiv) was

dissolved in 35 mL of DMSO (0.1 M) and magnetically

stirred at rt. Water (126 µL, 7.00 mmol, 2.00 equiv) was

added to the solution in a single portion followed by the

portionwise addition of NBS (1.3 g, 7.00 mmol,

2.00 equiv) over a period of 30 min. The reaction mixture

was stirred for further 60 min until only traces of starting material remained detectable by TLC

monitoring. Then the reaction mixture was poured into 150 mL of water. The aqueous phase was

extracted with ethyl acetate (3 × 75 mL). The combined organic layers were washed with 25 mL

of water and 25 mL of brine, respectively, dried (MgSO4) and concentrated in vacuo. Purification

was effected by flash-chromatography (silica, pentane/ethyl acetate, 2/1) affording bromohydrin

13b in 90% yield (2.10 g, 3.14 mmol) as a colorless solid. mp: 107 – 109 °C. Rf = 0.72 (ethyl

acetate). 1H NMR (200 MHz, CDCl3): δ = 7.78 – 7.69 (m, 4 H), 7.60 – 7.56 (m, 2 H), 7.44 – 7.19

(m, 7 H), 7.10 – 6.93 (m, 5 H), 5.19 – 5.16 (m, 1 H), 5.10 – 5.02 (m, 2 H), 4.45 (d, J = 6.8 Hz,

2 H), 4.31 – 4.28 (m, 2 H), 4.22 (t, J = 6.7 Hz, 1 H), 2.06 – 2.02 (m, 1 H).

13C NMR (50 MHz, CDCl3):16 δ = 162.3 (d, J(F-C) = 247 Hz, Cq), 162.2 (d, J(F-C) = 248 Hz,

Cq), 156.5 (Cq), 151.4 (Cq), 144.0 (Cq), 141.4 (Cq), 137.6 (d, J(F-C) = 3 Hz, Cq), 137.4 (d,

J(F-C) = 3 Hz, Cq), 132.3 (Cq), 129.9 (CH), 129.1 (d, J(F-C) = 8 Hz, CH), 128.6 (d, J(F-C) =

8 Hz, CH), 127.8 (CH), 127.2 (CH), 125.1 (CH), 122.6 (Cq), 122.5 (CH), 120.1 (CH), 117.9

(CH), 115.5 (d, J(F-C) = 22 Hz, CH), 115.4 (d, J(F-C) = 22 Hz, CH), 83.2 (Cq), 70.1 (CH), 66.8

16 Due to the symmetry of bromohydrin 13b, its 13C NMR-spectrum contains ten signals less (i.e.

a total of C27) than there are carbon atoms from elemental analysis (C37H28BrF2NO4).

S 21

(CH2), 58.8 (CH), 47.3 (CH), 44.5 (CH2). IR: (ν) = 3413 (br, w), 3345 (br, w), 3066 (w), 3051

(w), 3018 (w), 2972 (w), 2948 (w), 2891 (w), 1702 (s), 1602 (m), 1508 (s), 1451 (m), 1410 (w),

1361 (w), 1228 (s), 1122 (m), 1015 (m), 839 (m). MS (210 °C): m/z (%) = 651 (<1) [M{81Br}–

H2O]+, 649 (<1) [M{79Br}–H2O]+, 570 (17), 476 (5), 393 (15), 392 (21), 348 (12), 178 (100), 165

(18). HRMS calcd for C37H26BrF2NO3 [M–H2O]+, m/z: 649.1064; found: 649.1066. Anal. calcd for

C37H28BrF2NO4: C 66.47%, H 4.22%, N 2.10%; found: C 66.07%, H 4.40%, N 2.23%.

3-Bromo-2,2-bis(4-fluorophenyl)-6-[(methoxycarbonyl)methyl]-2H-1-benzopyran (2a)

Bromohydrin 13a was dissolved in 15 mL of toluene (489

mg, 1.00 mmol, 1.00 equiv; 0.07 M). 4-Toluenesulfonic acid

(28.5 mg, 0.15 mmol) was added in a single portion and the

resulting suspension was heated to reflux for 1.5 h until only

traces of the starting material remained detectable by TLC monitoring. The reaction mixture was

diluted with 40 mL of ethyl acetate, washed with water (3 × 10 mL), dried (MgSO4) and

concentrated in vacuo. The remainder was purified by flash-chromatography (silica,

pentane/diethyl ether, 3/1) affording benzopyran 2a as a colorless solid (424 mg, 0.90 mmol,

90%). mp: 107 – 109 °C. Rf = 0.58 (pentane/ethyl acetate, 2/1). tR = 14.7 min (flow rate:

1 mL/min, rt; eluent: acetonitrile/water, gradient: within 20 min from 7/3 to pure acetonitrile).

UV-vis (2.5 × 10−5 M, acetonitrile) λmax (A): 312 nm (ε = 2580 dm3 × M−1 × cm−1), λmax (B): 265 nm

(ε = 6220 dm3 × M−1 × cm−1). 1H NMR (400 MHz, CDCl3): δ = 7.45 – 7.39 (m, 4 H), 7.12 (s, 1 H),

7.06 – 6.99 (m, 5 H), 6.93 – 6.92 (m, 1 H), 6.82 – 6.80 (m, 1 H), 3.68 (s, 3 H), 3.50 (s, 2 H).

S 22

13C NMR (101 MHz, CDCl3):17 δ = 172.1 (Cq), 162.7 (d, J(F-C) = 248 Hz, Cq), 150.5 (Cq), 137.8

(d, J(F-C) = 3 Hz, Cq), 130.9 (CH), 130.6 (d, J(F-C) = 8 Hz, CH), 128.9 (CH), 127.8 (Cq), 126.7

(CH), 122.5 (Cq), 122.1 (Cq), 117.1 (CH), 114.9 (d, J(F-C) = 22 Hz, CH), 86.3 (Cq), 52.2 (CH3),

40.3 (CH2). IR: (ν) = 3068 (w), 3050 (w), 3000 (w), 2951 (w), 2843 (w), 1737 (s), 1601 (m),

1507 (s), 1490 (s), 1436 (w), 1408 (w), 1340 (w), 1230 (s), 1159 (s), 1015 (m), 991 (m), 954 (w),

836 (s). MS (160 °C): m/z (%) = 472 (4) [M{81Br}]+, 470 (4) [M{79Br}]+, 392 (37), 391 (100), 332

(12). HRMS calcd for C24H17BrF2O3, m/z: 470.0329; found: 470.0322. Anal. calcd for

C24H17BrF2O3: C 61.16%, H 3.64%; found: C 60.98%, H 3.65%.

3-Bromo-2,2-bis(4-fluorophenyl)-6-({[(9H-fluoren-9-yl)methoxycarbonyl]amino}methyl)-2H-1-

benzopyran (2b) [10]

Bromohydrin 13b was dissolved in 15 mL of toluene

(1.7 g, 2.50 mmol, 1.00 equiv; 0.2 M). 4-Toluenesulfonic

acid monohydrate (48 mg, 0.25 mmol, 10 mol%) was

added in a single portion and the resulting suspension was

heated to reflux for 60 min until only traces of the starting

material remained detectable by TLC monitoring. The

reaction mixture was diluted with 40 mL of ethyl acetate, washed with water (3 × 10 mL), dried

(MgSO4) and concentrated in vacuo. The crude product was purified by flash-chromatography

(silica, pentane/diethyl ether, 1/1) affording compound 2b in 92% yield (1.5 g, 2.30 mmol) as a

colorless solid. mp: 96 – 98 °C. Rf = 0.37 (pentane/ethyl acetate, 2/1). tR = 19.9 min (flow rate:

1 mL/min, rt; eluent: acetonitrile/water, gradient: within 20 min from 7/3 to pure acetonitrile).

17 Due to the symmetry of benzopyran 2a, its 13C NMR-spectrum contains eight signals less (i.e.

a total of C16) than there are carbon atoms from elemental analysis (C24

H17BrF2O3).

S 23

UV-vis (2.5 × 10−5 M, acetonitrile) λmax (A): 316 nm (ε = 3364 dm3 × M−1 × cm−1), λmax (B): 300 nm

(ε = 7608 dm3 × M−1 × cm−1), λmax (C): 265 nm (ε = 24204 dm3 × M−1 × cm−1). 1H NMR (200 MHz,

CDCl3):18 δ = 7.78 – 7.74 (m, 2 H), 7.59 – 7.55 (m, 2 H), 7.45 – 7.29 (m, 8 H), 7.11 – 6.97 (m, 6

H), 6.90 – 6.78 (m, 2 H), 4.97 (br s, 1 H), 4.47 – 4.44 (m, 2 H), 4.25 – 4.17 (m, 3 H).

13C NMR (50 MHz, CDCl3):19 δ = 162.7 (d, J(F-C) = 248 Hz, Cq), 156.5 (Cq), 150.7 (Cq), 144.0

(Cq), 141.5 (Cq), 137.8 (d, J(F-C) = 3 Hz, Cq), 132.4 (Cq), 130.6 (d, J(F-C) = 8 Hz, CH), 129.4

(CH), 128.9 (CH), 127.8 (CH), 127.2 (CH), 125.2 (CH), 125.1 (CH), 122.6 (Cq), 122.3 (Cq),

120.1 (CH), 117.2 (CH), 115.0 (d, J(F-C) = 21 Hz, CH), 86.3 (Cq), 66.8 (CH2), 47.4 (CH), 44.5

(CH2). IR: (ν) = 3419 (br, w), 3330 (br, w), 3066 (w), 3043 (w), 2971 (w), 2944 (w), 2892 (w),

1703 (s), 1601 (m), 1507 (s), 1489 (s), 1450 (m), 1361 (m), 1300 (m), 1229 (s), 1159 (s), 1130

(m), 1043 (m), 990 (s), 899 (w), 836 (s). MS (210 °C): m/z (%) = 649 (<1) [M]+, 570 (20), 503

(5), 429 (12), 392 (20), 374 (28), 348 (36), 281 (18), 221 (34), 178 (100), 165 (36), 147 (32), 120

(12). HRMS calcd for C37H26BrF2NO3, m/z: 649.1064; found: 649.1070. Anal. calcd for

C37H26BrF2NO3: C 68.32%, H 4.03%, N 2.15%; found: C 67.92%, H 4.24%, N 2.20%.

18 The broad signals at δ = 4.17 and 4.97 were assigned to the carbamate-N-H.

19 Due to the symmetry of benzopyran 2b, its 13C NMR-spectrum contains fourteen signals less

(i.e. a total of C23) than there are carbon atoms from elemental analysis (C37H26BrF2NO3).

S 24

2-Cyano-3,3-bis(4-fluorophenyl)-8-(methoxycarbonyl)-3H-

naphtho[2,1-b]pyran (3)

A Schlenk flask was charged with zinc powder (14 mg,

0.21 mmol, 0.4 equiv), iodine (23 mg, 9.1 × 10−2 mmol,

0.2 equiv) and 1 mL of NMP. The suspension was

magnetically stirred at rt until decoloration. CAUTION!20

After a iodine-starch test indicated the absence of iodine, zinc cyanide (65 mg, 0.55 mmol,

1.12 equiv) was added followed by naphthopyran 1 (248 mg, 0.49 mmol, 1.00 equiv),

[t-Bu3PH]BF4 (12 mg, 0.04 mmol, 8 mol%) and Pd(dba)2 (12 mg, 0.02 mmol, 4 mol%). The

suspension was degassed and stirred for 41 h at 45 °C until RP-HPLC monitoring indicated a

complete consumption of the starting material. Then, 10 mL of ethyl acetate and 5 mL of brine

were added. The layers were separated and the aqueous layer was extracted with ethyl acetate (5

× 5 mL). The combined organic phases were once washed with water (5 mL), dried (MgSO4) and

concentrated in vacuo. The oily remainder was purified by flash-chromatography (silica,

pentane/diethyl ether, 3/1) affording the nitrile 3 as a yellow solid (185 mg, 0.41 mmol, 83%

yield). mp: 209 – 210 °C. Rf = 0.73 (pentane/diethyl ether, 1/2). tR = 14.4 min (flow rate:

1 mL/min, rt; eluent: acetonitrile/water, gradient: isocratic for 20 min at 17/3 then within 10 min

to pure acetonitrile). UV-vis (2.5 × 10−5 M, acetonitrile) λmax (A): 370 nm (ε = 7480 dm3 × M−1 ×

cm−1), λmax (B): 341 nm (ε = 6724 dm3 × M−1 × cm−1), (C): 326 nm (ε = 6872 dm3 × M−1 × cm−1), λmax

(D): 262 nm (ε = 38820 dm3 × M−1 × cm−1). 1H NMR (400 MHz, CDCl3): δ = 8.50 (d, J = 1.7 Hz, 1

H), 8.15 (dd, J = 8.8 Hz, J = 1.8 Hz, 1 H), 8.08 (s, 1 H), 7.96 (d, J = 9.1 Hz, 1 H), 7.92 (d, J = 8.9 20 CAUTION! Cyanide and gaseous HCN are highly toxic and need special precautions. For

additional information see: international chemical safety cards (ICSCs) at www.ilo.org or

www.hvbg.de/e/bia/gestis/.

S 25

Hz, 1 H), 7.47 – 7.43 (m, 4 H), 7.23 (d, J = 8.9 Hz, 1 H), 7.09 – 7.03 (m, 4 H), 3.97 (s, 3 H). 13C

NMR (101 MHz, CDCl3):21 δ = 166.8 (Cq), 163.1 (d, J(F-C) = 249 Hz, Cq), 153.9 (Cq), 136.9 (d,

J(F-C) = 3 Hz, Cq), 135.6 (CH), 134.7 (CH), 132.1 (Cq), 131.9 (CH), 129.8 (d, J(F-C) = 9 Hz,

CH), 128.8 (Cq), 128.0 (CH), 126.9 (Cq), 121.5 (CH), 119.0 (CH), 117.5 (Cq), 115.6 (d, J(F-C)

= 22 Hz, CH), 113.2 (Cq), 109.6 (Cq), 83.0 (Cq), 52.5 (CH3). IR: (ν) = 3072 (w), 2953 (w), 2926

(w), 2852 (w), 2210 (m), 1720 (s), 1626 (s), 1601 (m), 1508 (s), 1466 (m), 1281 (s), 1229 (s),

1204 (s), 1160 (s), 1088 (m), 1013 (m), 838 (s). MS (200 °C): m/z (%) = 455 (11) [M+2H]+, 454

(52) [M+H]+, 453 (97) [M]+, 421 (78), 392 (12), 358 (100), 333 (10), 201 (16). HRMS calcd for

C28H17F2NO3, m/z: 453.1177; found: 453.1178. Anal. calcd for C28H17F2NO3: C 74.17%, H 3.78%,

N 3.09%; found: C 74.06%, H 4.00%, N 3.01%.

21 Due to the symmetry of naphthopyran 3, its 13C NMR-spectrum contains eight signals less (i.e.

a total of C20) than there are carbon atoms from elemental analysis (C28

H17F2NO3).

S 26

3-Cyano-2,2-bis(4-fluorophenyl)-6-

[(methoxycarbonyl)methyl]-2H-1-benzopyran (5a)

A Schlenk flask was charged with zinc powder (29 mg,

0.44 mmol, 0.4 equiv), iodine (56 mg, 0.22 mmol, 0.2 equiv)

and 2.1 mL of NMP. The suspension was magnetically

stirred at rt until decoloration. CAUTION!22

After a iodine-starch test indicated the absence of

iodine, zinc cyanide (130 mg, 1.06 mmol, 1.05 equiv) was added followed by benzopyran 2a

(500 mg, 1.06 mmol, 1.0 equiv), [t-Bu3PH]BF4 (26 mg, 0.09 mmol, 8 mol%) and Pd(dba)2 (25

mg, 0.04 mmol, 4 mol%). The suspension was degassed and stirred for 19 h at 45 °C until RP-

HPLC monitoring indicated a complete consumption of the starting material. Then, 15 mL of

ethyl acetate and 10 mL of brine were added. The layers were separated and the aqueous layer

was extracted with ethyl acetate (6 × 5 mL). The combined organic phases were once washed

with water (10 mL), dried (MgSO4) and concentrated in vacuo. The crude oil was purified by

flash-chromatography (silica, pentane/diethyl ether, 1/1) to afford nitrile 5a as a colorless solid

(418 mg, 1.00 mmol, 94% yield). mp: 143 – 145 °C. Rf = 0.43 (pentane/diethyl ether, 1/1). tR =

11.2 min (flow rate: 1 mL/min, rt; eluent: acetonitrile/water, gradient: isocratic for 20 min at 17/3

then within 10 min to pure acetonitrile). UV-vis (2.5 × 10−5 M, acetonitrile) λmax (A): 343 nm (ε =

4356 dm3 × M−1 × cm−1), λmax (B): 288 nm (ε = 14328 dm3 × M

−1 × cm−1). 1H NMR (400 MHz,

CDCl3): δ = 7.42 – 7.38 (m, 5 H), 7.22 – 7.19 (m, 1 H), 7.07 – 7.03 (m, 5 H), 6.92 – 6.90 (m, 1

22 CAUTION! Cyanide and gaseous HCN are highly toxic and need special precautions. For

additional information see: international chemical safety cards (ICSCs) at www.ilo.org or

www.hvbg.de/e/bia/gestis/.

S 27

H), 3.69 (s, 3 H), 3.52 (s, 2 H). 13C NMR (101 MHz, CDCl3):23 δ = 171.7 (Cq), 163.0 (d, J(F-C) =

249 Hz, Cq), 151.9 (CH), 138.7 (Cq), 137.1 (d, J(F-C) = 3 Hz, Cq), 134.4 (Cq), 129.8 (d, J(F-C)

= 8 Hz, CH), 129.0 (CH), 128.4 (CH), 119.5 (Cq), 117.7 (CH), 117.3 (Cq), 115.5 (d, J(F-C) = 22

Hz, CH), 111.6 (Cq), 82.7 (Cq), 52.3 (CH3), 40.1 (CH2). IR: (ν) = 3070 (w), 3051 (w), 3000 (w),

2953 (w), 2927 (w), 2212 (m), 1737 (s), 1623 (m), 1600 (m), 1507 (s), 1487 (m), 1436 (m), 1231

(s), 1161 (s), 997 (m), 837 (s). MS (160 °C): m/z (%) = 417 (60) [M]+, 357 (100), 322 (83).

HRMS calcd for C25H17F2NO3, m/z: 417.1177; found: 417.1181. Anal. calcd for C25H17F2NO3: C

71.94%, H 4.11%, N 3.36%; found: C 71.78%, H 4.33%, N 3.40%.

3-Cyano-2,2-bis(4-fluorophenyl)-6-({[(9H-fluoren-9-yl)methoxycarbonyl]amino}methyl)-

2H-1-benzopyran (5b)

A Schlenk flask was charged with zinc powder (21 mg,

0.32 mmol, 0.4 equiv), iodine (41 mg, 0.16 mmol,

0.2 equiv) and 1.5 mL of NMP. The suspension obtained

was magnetically stirred at rt until decoloration.

CAUTION!24

After a iodine-starch test indicated the

absence of iodine, zinc cyanide (94 mg, 0.8 mmol, 1.0

equiv) was added followed by benzopyran 2b (0.5 g, 0.8 mmol, 1.0 equiv), [t-Bu3PH]BF4 (19 mg,

0.07 mmol, 8 mol%) and 18.0 mg Pd(dba)2 (0.031 mmol, 3.9 mol%). The suspension was

23 Due to the symmetry of benzopyran 5a, the 13C NMR-spectrum contains eight signals less (i.e.

a total of C17) than there are carbon atoms from elemental analysis (C25H17F2N1O3).

24 CAUTION! Cyanide and gaseous HCN are highly toxic and need special precautions. For

additional information see: international chemical safety cards (ICSCs) at www.ilo.org or

www.hvbg.de/e/bia/gestis/.

S 28

degassed and stirred for 24 h at 45 °C. After this period, RP-HPLC monitoring indicated

incomplete conversion of the starting material and the reaction mixture was stirred for further

49 h at 65 °C. After this additional period, RP-HPLC monitoring indicated a constant incomplete

consumption of the starting material, and 15 mL of ethyl acetate and 10 mL of brine were added.

The layers were separated and the aqueous layer was extracted with ethyl acetate (6 × 5 mL). The

combined organic phases were once washed with water (10 mL), dried (MgSO4) and

concentrated in vacuo. The oily remainder was purified by flash-chromatography (silica,

pentane/diethyl ether, 2/1 to 1/3) to give nitrile 5b as a colorless, amorphous wax (320 mg,

0.54 mmol, 67% yield). Rf = 0.20 (pentane/diethyl ether, 1/2). tR = 7.7 min (flow rate: 1 mL/min,

rt; eluent: acetonitrile/water, gradient: isocratic for 20 min at 17/3 then within 10 min to pure

acetonitrile). UV-vis (2.5 × 10−5 M, acetonitrile) λmax (A): 345 nm (ε = 3920 dm3 × M−1 × cm−1), λmax

(B): 300 nm (ε = 15604 dm3 × M−1 × cm−1), λmax (C): 289 nm (ε =17464 dm3 × M−1 × cm−1), λmax (D):

266 nm (ε = 22096 dm3 × M−1 × cm−1). 1H NMR (400 MHz, CDCl3):25,26 δ = 7.78 – 7.76 (m, 2 H),

7.58 – 7.56 (m, 2 H), 7.42 – 7.36 (m, 7 H), 7.32 – 7.28 (m, 2 H), 7.18 – 7.16 (m, 1 H), 7.09 – 7.03

(m, 5 H), 6.92 – 6.90 (m, 1 H), 5.03(br s, 1 H), 4.47 (d, J = 6.6 Hz, 2 H),

4.26 – 4.24 (m, 2 H), 4.20 (t, J = 6.6 Hz, 1 H). 13C NMR (101 MHz, CDCl3):27 δ = 163.0 (d, J(F-

C) = 249 Hz, Cq), 156.5 (Cq), 152.2 (Cq), 143.9 (Cq), 141.5 (Cq), 138.8 (CH), 137.0 (d, J(F-C) =

3 Hz, Cq), 133.1 (Cq), 132.7 (CH), 129.8 (d, J(F-C) = 9 Hz, CH), 127.9 (CH), 127.4 (CH), 127.2

(CH), 125.1 (CH), 120.2 (Cq), 119.6 (CH), 117.8 (CH), 117.3 (Cq), 115.6 (d, J(F-C) = 22 Hz,

25 The broad signal at δ = 5.03 was assigned to the carbamate-N-H.

26 Impurities and residual solvents can be removed by RP-HPLC.

27 Due to the symmetry of benzopyran 5b, its 13C NMR-spectrum contains fourteen signals less

(i.e. a total of C24) than there are carbon atoms from elemental analysis (C38H26F2N2O3).

S 29

CH), 111.8 (Cq), 82.7 (Cq), 66.8 (CH2), 47.4 (CH), 44.3 (CH2). IR: (ν) = 3485 (br, w), 3415 (br,

w), 3339 (br, w), 3066 (w), 2972 (w), 2930 (w), 2893 (w), 2211 (m), 1704 (s), 1622 (m), 1606

(m), 1508 (s), 1363 (m), 1230 (s), 1160 (s), 997 (m), 838 (s). MS (270 °C): m/z (%) = 597 (<1)

[M+H]+, 374 (68), 357 (77), 279 (78), 178 (100). HRMS calcd for C38H27F2N2O3 (M+H)+, m/z:

597.1990; found: 597.1997. Anal. calcd for C38H26F2N2O3: C 76.50%, H 4.39%, N 4.70%; found:

C 76.17%, H 4.53%, N 4.62%.

2-[Bis(4-fluorophenyl)methyl]-7-(methoxycarbonyl)naphtho[2,1-b]furan (14) [11]

A pressure tube (Ace Glass Inc.) was charged under an atmosphere

of argon with Na2CO3 (14.8 mg, 0.14 mmol, 1.00 equiv),

K4[Fe(CN)6] (16.0 mg, 0.04 mmol, 0.29 equiv), Pd(OAc)2

(1.1 mg, 5.0 × 10−3 mmol, 4 mol%) and 1,1'-bis(diphenyl-

phosphino)ferrocene (8.1 mg, 1.5 × 10−2 mmol, 10 mol%). The

vessel was purged with argon for 5 min. Then, naphthopyran 1 (70.8 mg, 0.14 mmol, 1.00 equiv)

and 3 mL of degassed NMP were added. CAUTION!28

The resulting suspension was

magnetically stirred for 44 h at 120 °C. After TLC monitoring indicated a complete consumption

of the naphthopyran 1, the reaction mixture was diluted with 5 mL of ethyl acetate and 5 mL of

brine. After separation of the organic layer, the aqueous layer was extracted with ethyl acetate

28 CAUTION! Experiments in pressure tubes at high temperatures are potentially hazardous and

must only be carried out by using appropriate equipment and safety precautions. A blast shield

should be in place and vessels designed to withhold elevated pressures must be used. After

completion of an experiment, the vessel must be allowed to cool before opening to the

atmosphere.

S 30

(5 × 5 mL). The combined organic layers were once washed with 5 mL of water, dried (MgSO4)

and concentrated in vacuo. The crude product was purified by flash-chromatography (silica,

pentane/diethyl ether, 6/1) affording furan 14 as a brown oil (39 mg, 9.1 × 10−2 mmol, 65%). Rf =

0.79 (pentane/diethyl ether, 1/4). tR = 10.2 min (flow rate: 1 mL/min, rt; eluent acetonitrile/water,

gradient: isocratic for 20 min at 17/3 then within 10 min to pure acetonitrile). 1H NMR

(400 MHz, CDCl3): 29 δ = 8.69 (d, J = 1.5 Hz, 1 H), 8.13 (dd, J = 1.6 Hz, J = 8.6 Hz, 1 H), 8.05

(d, J = 8.6 Hz, 1 H), 7.80 (d, J = 8.9 Hz, 1 H), 7.65 (d, J = 8.9 Hz, 1 H), 7.23 – 7.19 (m, 4 H),

7.07 – 7.03 (m, 4 H), 6.75 (s, 1 H), 5.66 (s, 1 H), 3.99 (s, 3 H). 13C NMR (101 MHz, CDCl3):30 δ

= 167.5 (Cq), 162.1 (d, J(F-C) = 246 Hz, Cq), 159.5 (Cq), 153.9 (Cq), 136.7 (d, J(F-C) = 3 Hz,

Cq), 131.9 (CH), 130.5 (d, J(F-C) = 8 Hz, CH), 130.1 (Cq), 129.5 (Cq), 126.33 (CH), 126.29

(Cq), 126.0 (CH), 123.8 (CH), 123.5 (Cq), 115.8 (d, J(F-C) = 22 Hz, CH), 113.4 (CH), 105.0

(CH), 52.4 (CH3), 50.0 (CH). IR: (ν) = 3070 (w), 3041 (w), 2951 (w), 2929 (w), 2853 (w), 1717

(s), 1628 (w), 1603 (w), 1507 (s), 1401 (w), 1296 (m), 1261 (s), 1225 (s), 1196 (m), 1158 (m),

992 (w), 800 (m). MS (200 °C): m/z (%) = 428 (66) [M]+, 369 (12), 333 (100), 305 (36), 273

(36), 244 (13), 227 (36). HRMS calcd for C27H18F2O3, m/z: 428.1224; found: 428.1228.

29 Impurities and residual solvents can be removed by RP-HPLC.

30 Due to the symmetry of napthofuran 14, its 13C NMR-spectrum contains eight signals less (i.e.

a total of C19) than there are carbon atoms from elemental analysis (C27H18F2O3).

S 31

3,3-Bis(4-fluorophenyl)-8-(methoxycarbonyl)-2-[(trimethylsilyl)ethinyl]-

3H-naphtho[2,1-b]pyran (4)

A Schlenk flask was charged with naphthopyran 1 (70 mg,

1.4 × 10−1 mmol, 1.0 equiv), Pd(PPh3)4 (16 mg, 1.4 ×

10−2 mmol, 10 mol%) and CuI (4 mg, 2.1 × 10−2 mmol,

15 mol%). Then, THF (1 mL, 0.1 M in pyran 1) and iPr2NH

(39 µL, 2.8 × 10−1 mmol, 2.0 equiv) were added. The yellow suspension was degassed and

(trimethylsilyl)acetylene (39 µL, 4.0 × 10−1 mmol, 2.8 equiv) was added. The mixture was

magnetically stirred for 22 h at rt and the RP-HPLC monitoring indicated incomplete conversion.

After additional stirring for 23 h at rt, RP-HPLC monitoring indicated a constant incomplete

conversion and the solution was diluted with 5 mL of diethyl ether and 5 mL of brine. The layers

were separated and the aqueous layer was extracted with diethyl ether (5 × 5 mL). The combined

organic layers were washed with 5 mL of water, dried (MgSO4) and concentrated in vacuo. The

remainder was purified by flash-chromatography (silica, pentane/diethyl ether, 10/1) to give 39

mg (7.4 × 10−2 mmol, 53% yield) of naphthopyran 4 as a brown solid. mp: 86 – 88 °C. Rf = 0.59

(pentane/diethyl ether, 3/1). tR = 14.0 min (flow rate: 1 mL/min, rt; eluent: acetonitrile/water,

gradient: within 10 min from 17/3 to pure acetonitrile). UV-vis (acetonitrile, 2.5 × 10−5 M) λmax

(A): 369 nm (ε = 14488 dm3 × M−1 × cm−1), λmax (B): 272 nm (ε = 46144 dm3 × M

−1 × cm−1).

1H NMR (400 MHz, CDCl3): δ = 8.46 (d, J = 1.4 Hz, 1 H), 8.06 (dd, J = 8.8 Hz, J = 1.8 Hz, 1 H),

7.97 (d, J = 8.9 Hz, 1 H), 7.77 (d, J = 8.8 Hz, 1 H), 7.68 (s, 1 H), 7.48 – 7.45 (m, 4 H), 7.20 (d, J

= 8.8 Hz, 1 H), 7.02 – 6.97 (m, 4 H), 3.96 (s, 3 H), 0.04 (s, 9 H). 13C NMR (101 MHz, CDCl3):31 δ

31 Due to the symmetry of naphthopyran 4, its 13C NMR-spectrum contains ten signals less (i.e. a

total of C22) than there are carbon atoms from elemental analysis (C32H26F2O3Si).

S 32

= 167.2 (Cq), 162.6 (d, J(F-C) = 247 Hz, Cq), 152.5 (Cq), 138.5 (d, J(F-C) = 34 Hz, Cq), 132.5

(CH), 131.9 (Cq), 131.8 (CH), 130.2 (d, J(F-C) = 8 Hz, CH), 128.8 (Cq), 126.80 (CH), 126.75

(CH), 126.0 (Cq), 121.8 (CH), 120.8 (CH), 119.1 (CH), 115.0 (Cq), 114.8 (d, J(F-C) = 22 Hz,

CH), 104.0 (Cq), 102.2 (Cq), 84.8 (Cq), 52.3 (CH3), –0.3 (CH3). IR: (ν) = 3072 (w), 2956 (m),

2899 (w), 2850 (w), 2138 (m) [C≡C], 1721 (s) [C=O], 1625 (m), 1603 (m), 1508 (s), 1467 (m),

1397 (w), 1280 (s), 1227 (s), 1202 (s), 1160 (s), 1087 (m), 857 (s). MS (RT °C): m/z (%) = 524

(100) [M]+, 509 (65), 451 (56), 432 (35), 430 (13), 429 (38), 392 (26). HRMS calcd for

C32H26F2O3Si, m/z: 524.1619; found: 524.1622.

S 33

2,2-Bis(4-fluorophenyl)-6-({[(9H-fluoren-9-yl)methoxycarbonyl]amino}methyl)-

2H-1-benzopyran-3-carboxylic acid (6)

Benzopyran 2b (1.5 g, 2.30 mmol, 1.0 equiv), PdCl2(PPh3)2

(160 mg, 0.23 mmol, 10.0 mol%) and molecular sieve (115

mg, 4 Å, activated powder, 50 mg/0.1 mmol benzopyran)32

were mechanically suspended in 20 mL of degassed THF

(0.1 M in benzopyran 2b) in a 100-mL-steele-autoclave

(Parr Instrument). The yellow suspension was stirred at rt

for 30 min and degassed water (420 µL, 23.0 mmol, 10.0 equiv) was added in a single portion.

CAUTION!33 The suspension was mechanically stirred at 100 °C under a CO pressure of 50 atm

for 72 h, and then concentrated in vacuo to give a black resin which was purified by flash-

chromatography (silica, pentane/acetone, 7/4). Benzopyran 6 was isolated as an amorphous pale

yellow wax (200 mg, 0.32 mmol, 14%). Rf = 0.30 (acetone/pentane, 2/3). Analytical RP-HPLC:

tR = 22.2 min (flow rate: 1 mL/min, rt; eluent: acetonitrile/water, gradient: within 25 min from

3/7 to 6/4). UV-vis (2.5 × 10−5 M, acetonitrile) λmax (A): 339 nm (ε = 3256 dm3 × M−1 × cm−1),

λmax (B): 300 nm (ε = 10540 dm3 × M−1 × cm−1), λmax (C): 265 nm (ε = 18584 dm3 × M−1 × cm−1).

1H NMR (400 MHz, CDCl3):34,35 δ = 7.77 – 7.75 (m, 3 H), 7.56 (d, J = 7.1 Hz, 2 H), 7.39 (t, J =

7.5 Hz, 2 H), 7.35 – 7.33 (m, 4 H), 7.31 – 7.27 (m, 2 H), 7.12 (d, J = 8.3 Hz, 1 H), 7.04 (s, 1 H),

32 The powder was dried prior to use (~750 °C, <1 mbar).

33 CAUTION! CO is highly toxic and needs special precautions. For additional information see:

international chemical safety cards (ICSCs) at www.ilo.org or www.hvbg.de/e/bia/gestis/.

34 The broad signal at δ = 5.03 was assigned to the carbamate-N-H.

35 Impurities and residual solvents can be removed by RP-HPLC.

S 34

6.97 – 6.92 (m, 4 H), 6.82 (d, J = 8.8 Hz, 1 H), 5.88 (br s, 1 H), 5.03 (br s, 1 H), 4.45

(d, J = 6.7 Hz, 2 H), 4.23 – 4.18 (m, 3 H). 13C NMR (100.6 MHz, CDCl3): δ = 169.1 (Cq), 162.3

(d, J(F-C) = 247 Hz, Cq), 156.6 (Cq), 152.9 (Cq), 143.9 (Cq), 141.5 (Cq), 138.3 (d, J(F-C) =

3 Hz, Cq), 136.6 (CH), 132.44 (CH), 132.38 (Cq), 130.5 (d, J(F-C) = 8 Hz, CH), 128.4 (Cq),

128.0 (CH), 127.9 (CH), 127.2 (CH), 125.1 (CH), 120.5 (Cq), 120.2 (CH), 117.4 (CH), 114.7 (d,

J(F-C) = 22 Hz, CH), 84.6 (Cq), 66.8 (CH2), 47.4 (CH), 44.4 (CH2). IR: (ν) = 3335 (br, w), 3065

(w), 2957 (w), 2925 (w), 2854 (w), 1700 (s), 1601 (w), 1507 (s), 1378 (m), 1229 (s), 1159 (m),

992 (m), 840 (m). MS (240 °C): m/z (%) = 571 (<1) [M–CO2]+, 476 (3), 437 (3), 393 (9), 355

(12), 284 (65), 231 (12), 178 (62), 165 (12), 128 (100). HRMS: calcd for C38H27F2NO5:

615.1857; found: 615.1867.

S 35

Spectroscopic data

UV-vis spectra (2.5 × 10−5 M, acetonitrile):

275 300 325 350 375 400 425 450 475 500

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

275 300 325 350 375 400 425 450 475 500

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

S 36

275 300 325 350 375 400 425 450 475 500

0,0

0,1

0,2

0,3

0,4

0,5

0,6

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

300 325 350 375 400 425 450 475 500

0,0

0,2

0,4

0,6

0,8

1,0

1,2

dichloromethane, 1.0×10-4 M

abso

rptio

n

Wavelength (nm)

S 37

275 300 325 350 375 400 425 450 475 500

0,0

0,1

0,2

0,3

0,4

0,5

0,6

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

275 300 325 350 375 400 425 450 475 500

0,0

0,2

0,4

0,6

0,8

1,0

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

S 38

275 300 325 350 375 400 425 450 475 500

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

275 300 325 350 375 400 425 450 475 500

0,0

0,1

0,2

0,3

0,4

0,5

0,6

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

S 39

275 300 325 350 375 400 425 450 475 500

0,0

0,2

0,4

0,6

0,8

1,0

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

275 300 325 350 375 400 425 450 475 500

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

S 40

275 300 325 350 375 400 425 450 475 500

0,0

0,1

0,2

0,3

0,4

0,5

0,6

acetonitrile, 2.5×10-5 M

abso

rptio

n

wavelength (nm)

S 41

NMR spectra

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

4.5

630

4.5

703

4.5

775

4.5

894

4.5

967

4.6

040

5.2

923

5.2

982

5.3

048

5.3

115

5.3

440

5.3

508

5.3

579

5.3

671

5.3

751

5.3

824

5.4

462

5.4

537

5.4

612

5.4

686

5.9

335

5.9

592

5.9

854

6.0

119

6.0

193

6.0

383

6.0

459

6.0

720

6.0

977

6.1

242

6.9

190

6.9

322

6.9

421

6.9

663

6.9

767

6.9

901

7.5

385

7.5

517

7.5

617

7.5

858

7.5

959

7.6

097

2.1

3

2.0

4

0.9

6

2.0

6

2.0

0

69.1

5

104.2

6

115.5

9

118.6

81

19.3

6

132.2

21

34.1

3

161.9

9

160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

S 42

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

1.3

38

5

3.7

46

74.4

54

44.4

61

84.4

69

64.4

80

84.4

88

04.4

95

25.2

12

15.2

19

25.2

26

35.2

56

95.2

63

85.2

70

95.2

78

05.3

17

55.3

24

85.3

33

65.3

41

55.4

03

05.4

11

95.4

19

75.4

27

05.9

22

45.9

49

05.9

74

26.0

00

46.0

08

06.0

27

46.0

34

66.0

61

36.0

86

56.1

12

86.8

08

26.8

23

06.8

33

06.8

55

86.8

66

36.8

80

87.1

40

47.1

54

77.1

65

87.1

97

77.2

12

4

2.0

1

2.0

1

2.0

4

1.9

2

0.8

6

1.9

9

1.9

7

45.9

1

68.8

8

114

.81

117

.63

128

.29

133

.41

135

.72

157

.55

155 150 145 140 135 130 125 120 115 110 105 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 ppm

S 43

9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

4.1

95

44

.23

04

4.2

64

74

.30

46

4.3

33

84

.44

01

4.4

74

34

.51

43

4.5

21

64

.52

87

4.5

40

94

.54

82

4.5

55

35

.02

84

5.2

63

65

.27

06

5.2

77

75

.28

46

5.3

23

35

.32

99

5.3

35

75

.36

55

5.3

72

95

.38

03

5.4

51

25

.45

87

5.4

67

35

.47

49

5.9

68

25

.99

47

6.0

20

26

.04

64

6.0

53

66

.07

31

6.0

80

56

.10

71

6.1

32

56

.15

89

6.8

60

46

.90

31

7.1

72

37

.21

46

7.3

09

77

.34

23

7.3

46

77

.37

60

7.4

08

37

.41

24

7.4

44

27

.44

93

7.5

79

77

.61

67

7.7

52

17

.79

01

1.2

61

.84

2.0

22

.12

0.7

6

1.9

0

0.8

7

1.9

5

1.7

6

4.1

9

1.8

3

2.0

0

44

.69

47

.41

66

.74

68

.96

11

5.0

3

11

7.8

6

12

0.1

1

12

5.1

512

7.1

612

7.7

912

9.0

213

0.7

913

3.3

3

14

1.4

6

14

4.0

6

15

6.4

815

8.1

7

160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

S 44

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

4.1

86

3

4.2

19

84

.25

41

4.2

79

14

.30

82

4.4

37

54

.47

12

5.0

18

3

6.7

62

76

.80

46

7.1

01

57

.14

25

7.2

95

97

.33

14

7.3

63

07

.39

85

7.4

33

77

.56

60

7.6

02

17

.74

00

7.7

76

5

1.3

0

1.8

3

2.0

8

0.4

9

2.0

0

1.9

9

4.9

4

1.9

9

2.0

4

4

4.8

2

48.1

7

66.8

6

116.0

1

120.8

31

26.1

51

27.9

41

28.5

21

29.6

61

31.5

8

142.1

71

45.2

3

157.3

21

57.4

3

230 220 210 200 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

S 45

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

2.8

18

32.9

06

2

6.9

61

56.9

78

06.9

88

17.0

05

27.0

12

07.0

21

47.0

31

27.0

36

17.0

54

07.0

64

77.0

80

57.5

05

17.5

20

27.5

31

67.5

46

87.5

55

37.5

64

97.5

80

87.5

90

8

0.9

10

.98

4.0

7

4.0

0

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

73

.51

76

.10

86

.04

11

5.1

011

5.5

3

12

7.8

812

8.0

5

14

0.1

914

0.2

6

16

0.0

3

16

4.9

4

S 46

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

3.9

61

7

6.1

86

26.2

11

1

6.9

93

16.9

98

47.0

14

77.0

36

57.2

01

07.2

23

17.3

04

67.3

29

67.4

06

77.4

12

17.4

20

07.4

28

77.4

42

07.7

63

27.7

85

47.9

65

87.9

87

98.0

46

18.0

68

38.4

75

6

3.0

1

1.0

0

4.0

1

1.0

41

.03

3.9

9

1.0

1

1.0

10

.99

1.0

0

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

52

.30

82

.32

11

4.0

211

5.1

711

5.3

911

9.1

611

9.6

612

1.6

612

5.5

612

6.4

312

7.7

112

8.6

012

8.9

012

8.9

813

1.7

313

1.8

013

2.2

214

0.3

114

0.3

4

15

2.3

0

16

1.1

4

16

3.6

0

16

7.3

0

S 47

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1.4

21

71.4

48

5

3.9

69

8

5.5

94

55.6

00

55.6

20

96.9

10

06.9

15

16.9

22

66.9

32

16.9

47

76.9

53

06.9

61

17.0

61

67.0

66

77.0

83

67.0

99

67.1

05

07.1

13

07.4

59

67.4

64

17.4

72

27.4

77

07.4

82

07.4

89

87.4

95

67.5

18

87.6

87

17.6

95

37.7

00

37.7

08

17.7

13

17.7

17

77.7

25

37.7

30

57.7

38

77.9

84

88.0

07

38.0

49

08.0

71

38.0

88

28.0

92

48.1

10

38.1

14

58.5

54

28.5

57

9

0.9

21.0

6

3.1

3

2.0

5

2.0

8

2.1

0

1.7

41.4

0

2.0

8

1.0

31.0

31.0

3

1.0

0

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

52

.39

54

.99

68

.39

82

.15

11

3.4

511

5.4

811

5.7

011

5.9

011

6.1

111

9.6

012

3.5

012

6.2

012

6.9

112

6.9

712

7.0

912

8.5

912

8.6

812

9.1

213

1.5

213

3.1

113

5.5

513

5.7

113

5.7

613

9.6

7

15

1.3

8

16

0.8

216

0.8

716

3.3

016

3.3

416

7.1

5

S 48

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

3.9

58

9

7.0

07

27.0

28

87.0

50

47.1

58

07.1

80

17.4

59

47.4

72

67.4

81

47.4

89

77.4

94

67.7

49

37.7

71

47.7

91

97.9

08

27.9

30

48.0

62

38.0

84

48.4

66

8

3.0

1

4.0

9

1.0

2

4.0

6

2.0

7

1.0

3

1.0

1

1.0

0

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

52

.33

86

.56

11

4.9

111

5.1

211

5.5

611

8.9

512

0.8

612

1.6

512

4.9

612

5.9

912

6.7

312

8.7

613

0.4

913

0.5

713

1.2

413

1.7

413

1.9

613

7.7

113

7.7

4

15

1.4

4

16

1.5

4

16

4.0

1

16

7.1

3

S 49

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

3.5

00

9

3.6

76

9

6.0

59

46

.08

39

6.5

85

86

.61

04

6.8

31

86

.85

24

6.9

44

16

.94

94

6.9

71

96

.97

96

6.9

84

96

.99

66

7.0

01

37

.00

60

7.0

17

97

.02

33

7.0

31

37

.04

70

7.0

52

47

.33

79

7.3

45

47

.35

09

7.3

58

8

2.0

3

3.0

7

1.0

0

1.0

1

1.0

1

6.2

3

4.1

1

40

.42

52

.19

82

.01

11

5.0

911

5.3

011

6.7

212

1.0

712

3.6

912

7.0

112

7.5

712

8.7

712

8.8

912

8.9

713

0.6

7

14

0.6

014

0.6

3

15

1.4

1

16

1.0

5

16

3.5

0

17

2.3

1

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

S 50

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

4.2

08

44.2

21

94.2

36

34.2

45

64.2

56

74.4

46

04.4

59

5

5.0

07

4

6.0

85

66.1

05

16.5

91

06.6

10

56.8

48

26.8

64

56.9

50

36.9

97

27.0

14

57.0

31

77.2

89

27.3

03

57.3

18

07.3

63

27.3

73

97.3

80

47.3

90

97.4

02

87.4

17

77.5

80

07.5

94

47.7

61

17.7

75

9

1.0

11.7

4

2.0

9

0.8

2

1.0

0

1.0

2

1.1

90.9

74.9

0

1.8

15.4

4

1.7

8

2.0

3

44

.67

47

.41

66

.79

82

.03

11

5.1

31

15

.30

11

6.8

01

20

.12

12

1.2

11

23

.69

12

5.1

31

26

.20

12

7.1

71

27

.82

12

8.8

81

28

.95

12

9.0

01

29

.22

13

1.5

91

40

.50

14

0.5

31

41

.46

14

4.0

4

15

1.7

2

15

6.4

9

16

1.3

01

63

.27

160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

S 51

9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

1.9

96

32.0

15

2

3.5

52

6

3.6

86

3

5.0

62

15.0

77

45.0

95

75.1

66

25.1

81

06.9

44

16.9

52

16.9

57

56.9

65

06.9

69

46.9

74

16.9

78

16.9

82

56.9

90

06.9

95

47.0

02

77.0

08

07.0

15

77.0

19

97.0

24

77.0

28

87.0

33

27.0

40

77.0

46

27.0

54

27.0

70

17.0

91

17.2

26

17.2

31

57.2

47

27.2

52

77.2

77

17.2

82

47.3

38

47.3

46

47.3

51

77.3

59

37.3

64

27.3

68

97.3

76

57.3

81

87.3

89

87.7

04

87.7

12

97.7

18

27.7

25

87.7

30

87.7

35

5

0.9

5

2.0

0

2.9

8

0.9

90.9

8

4.9

8

0.9

81.0

21.9

8

1.9

8

40

.32

52

.23

58

.80

70

.15

83

.12

11

5.3

511

5.4

411

5.5

611

5.6

511

7.8

012

2.3

512

7.9

012

8.5

512

8.6

312

9.1

112

9.1

913

0.3

213

1.4

913

7.3

713

7.4

013

7.7

313

7.7

6

15

1.0

8

16

0.9

716

1.1

216

3.4

416

3.6

0

17

2.1

5

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

S 52

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

2.0

21

72.0

57

9

4.1

78

34.2

11

84.2

45

14.2

76

14.3

05

64.4

29

74.4

63

9

5.0

15

85.0

37

85.0

68

15.1

02

65.1

55

95.1

85

3

6.9

25

76.9

69

16.9

80

77.0

12

47.0

24

87.0

57

17.0

67

57.0

97

27.1

94

07.2

97

97.3

19

07.3

30

47.3

44

57.3

63

77.3

89

97.4

00

97.4

37

37.5

61

17.5

97

47.6

94

07.7

03

37.7

20

07.7

40

77.7

64

47.7

81

1

0.9

1

2.8

8

2.0

0

1.7

6

0.9

5

4.8

3

8.4

6

1.8

6

3.8

6

160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

44

.50

47

.33

58

.79

66

.78

70

.07

83

.23

11

5.2

211

5.2

511

5.6

511

5.6

811

7.8

912

0.1

212

2.5

012

2.5

512

5.0

912

7.1

712

7.8

312

8.5

312

8.6

812

9.0

212

9.1

812

9.8

613

2.3

113

7.3

313

7.3

913

7.5

413

7.6

014

1.4

314

3.9

715

1.3

8

15

6.5

1

15

9.7

115

9.8

4

16

4.6

316

4.7

8

S 53

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

3.4

96

6

3.6

75

6

6.8

03

36.8

23

96.9

23

06.9

28

26.9

87

66.9

95

47.0

00

67.0

17

27.0

33

67.0

38

87.0

46

87.0

51

47.0

56

87.1

18

67.3

94

17.4

01

97.4

07

37.4

15

17.4

19

27.4

24

27.4

32

17.4

37

47.4

45

2

2.0

0

2.9

4

0.9

90.9

94.9

30.9

7

3.9

0

40

.32

52

.21

86

.25

11

4.8

411

5.0

511

7.1

312

2.0

712

2.5

312

6.7

312

7.8

112

8.9

113

0.5

613

0.6

413

0.9

413

7.8

413

7.8

7

15

0.4

6

16

1.4

7

16

3.9

4

17

2.0

9

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

S 54

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

4.1

70

54

.204

74

.223

24

.236

14

.250

54

.435

54

.469

0

4.9

72

8

6.7

84

26

.825

16

.900

66

.973

76

.983

97

.016

97

.049

77

.060

07

.107

87

.292

37

.328

47

.376

87

.387

87

.403

37

.420

87

.437

77

.447

37

.553

87

.589

97

.742

47

.779

0

2.8

0

2.0

5

0.7

7

2.1

4

5.8

6

8.0

2

1.9

9

2.1

6

44.5

2

47.3

9

66.7

6

86.2

8

114

.77

115

.19

117

.21

120

.14

122

.27

122

.63

125

.09

125

.20

127

.17

127

.84

128

.89

129

.35

130

.51

130

.67

132

.42

137

.75

137

.81

141

.47

143

.99

150

.74

156

.49

160

.26

165

.19

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

S 55

9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

3.9

71

9

7.0

34

77.0

42

57.0

47

87.0

55

57.0

59

57.0

64

37.0

68

57.0

72

77.0

80

37.0

85

87.0

93

57.2

22

07.2

44

27.4

25

37.4

33

37.4

38

57.4

46

17.4

50

67.4

55

57.4

63

27.4

68

57.4

76

57.9

12

07.9

34

37.9

47

77.9

70

48.0

77

98.1

40

28.1

44

68.1

62

38.1

66

78.4

98

88.5

03

0

3.0

6

4.2

2

1.2

0

4.1

6

2.0

81.0

41.0

4

1.0

0

253035404550556065707580859095100105110115120125130135140145150155160165170 ppm

52

.48

83

.04

10

9.5

911

3.1

711

5.5

211

5.7

311

7.5

311

8.9

812

1.4

612

6.8

512

7.9

812

8.8

212

9.7

712

9.8

513

1.9

013

2.1

213

4.6

513

5.6

013

6.8

713

6.9

1

15

3.8

5

16

1.8

3

16

4.3

1

16

6.8

0

S 56

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

3.5

20

6

3.6

85

1

6.9

02

46.9

23

37.0

31

47.0

36

67.0

48

37.0

53

37.0

61

37.0

74

77.1

91

87.1

97

27.2

12

67.2

18

17.3

78

57.3

81

27.3

83

57.3

89

07.3

96

67.4

00

47.4

06

17.4

13

87.4

19

1

2.0

0

2.9

9

0.9

9

5.0

2

1.0

7

5.0

3

40.0

7

52.2

8

82.6

5

111

.62

115

.41

115

.63

117

.32

117

.69

119

.51

128

.40

129

.04

129

.76

129

.84

134

.38

137

.10

137

.13

138

.74

151

.92

161

.71

164

.19

171

.73

180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

S 57

Discusson of impurties see footnote.36

9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

0.9

063

1.2

592

1.2

882

1.2

954

1.3

232

1.4

363

1.5

651

2.2

773

4.1

865

4.2

029

4.2

197

4.2

428

4.2

578

4.4

600

4.4

766

5.0

254

6.8

960

6.9

169

7.0

285

7.0

362

7.0

414

7.0

493

7.0

533

7.0

580

7.0

621

7.0

661

7.0

740

7.0

795

7.0

872

7.1

614

7.1

822

7.2

793

7.2

975

7.3

162

7.3

628

7.3

716

7.3

796

7.3

849

7.3

924

7.3

973

7.4

019

7.4

092

7.4

147

7.4

230

7.5

609

7.5

792

7.7

585

7.7

772

0.1

7

0.2

70

.14

0.0

80

.30

0.3

0

0.0

4

1.1

91

.55

2.0

0

0.8

5

1.0

4

4.9

80

.99

1.8

67

.14

1.7

5

1.9

0

36 The impurities below 2.5 ppm didn’t give any detectable 1H-1H-correlation (see page S 58 for

COSY spectra) and no detectable 1H-13C-correlation to the 13C-NMR-signals of compound 5b

(see page S 59 – S 60 for the corresponding HMBC and HMQC spectra).

S 58

44

.25

47

.40

66

.80

82

.67

11

1.7

61

15

.45

11

5.6

61

17

.29

11

7.8

11

19

.58

12

0.1

71

25

.05

12

7.1

71

27

.39

12

7.8

71

29

.76

12

9.8

51

32

.69

13

3.1

11

37

.00

13

7.0

31

38

.78

14

1.5

01

43

.92

15

2.1

6

15

6.5

4

16

1.7

2

16

4.2

0

160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

COSY:

ppm

1.52.02.53.03.54.04.55.05.56.06.57.07.5 ppm

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

S 59

HMQC:

ppm

1.01.52.02.53.03.54.04.55.05.56.06.57.07.58.0 ppm

160

140

120

100

80

60

40

20

S 60

HMBC:

ppm

1.01.52.02.53.03.54.04.55.05.56.06.57.07.58.0 ppm

160

140

120

100

80

60

40

20

S 61

9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

3.9

87

3

5.6

63

1

6.7

53

47.0

28

17.0

33

37.0

44

87.0

49

87.0

54

27.0

66

07.0

71

47.1

90

37.1

95

57.2

03

67.2

11

97.2

20

27.2

25

27.6

35

37.6

57

57.7

87

27.8

09

68.0

39

38.0

60

88.1

21

88.1

25

98.1

43

38.1

47

48.6

91

48.6

95

0

0.3

4

1.2

1

0.3

2

2.0

5

0.1

2

0.0

9

0.0

7

0.0

6

3.1

0

0.9

9

0.9

7

4.0

3

4.0

2

1.0

0

0.6

0

1.0

10.9

8

1.0

0

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

50

.02

52

.37

10

4.9

9

11

3.3

511

5.6

911

5.9

012

3.5

412

3.7

712

6.0

212

6.2

912

6.3

312

9.5

413

0.1

113

0.4

413

0.5

213

1.9

313

6.6

813

6.7

1

15

3.9

3

15

9.5

316

0.8

916

3.3

3

16

7.4

7

S 62

9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

0.0

36

9

3.9

54

5

6.9

73

26.9

78

66.9

90

26.9

95

16.9

99

87.0

11

57.0

16

87.1

92

07.2

14

17.4

48

97.4

54

37.4

62

27.4

67

17.4

71

27.4

79

17.4

84

57.6

75

77.7

54

57.7

76

67.9

59

87.9

82

18.0

45

98.0

50

38.0

68

08.0

72

48.4

55

28.4

59

3

8.9

0

0.5

5

0.1

8

3.0

0

4.0

8

1.0

3

4.0

3

1.0

21

.02

1.0

21

.00

1.0

0

7.87.98.08.1 ppm 7.17.27.37.47.5 ppm

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

-0.3

0

52

.33

84

.75

10

2.1

810

4.0

3

11

4.6

511

4.8

611

5.0

311

9.1

012

0.8

312

1.8

212

6.0

012

6.7

512

6.8

012

8.7

713

0.1

513

0.2

313

1.7

913

1.9

213

2.4

913

8.4

913

8.5

2

15

2.4

8

16

1.4

1

16

3.8

7

16

7.1

7

S 63

8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm

0.8

873

1.2

500

1.2

674

2.1

726

2.6

299

4.0

417

4.1

750

4.1

918

4.2

175

4.2

332

4.4

459

4.4

638

5.0

315

5.8

812

6.8

127

6.8

329

6.9

241

6.9

449

6.9

650

7.0

445

7.1

128

7.1

318

7.1

940

7.2

707

7.2

891

7.3

121

7.3

255

7.3

339

7.3

474

7.3

759

7.3

938

7.4

128

7.5

511

7.5

702

7.7

470

7.7

661

0.7

6

1.6

61

.51

0.5

8

0.3

6

0.4

5

0.9

01

.61

2.0

0

0.7

2

0.2

1

1.0

40

.27

4.2

70

.78

0.8

20

.49

1.4

04

.28

2.1

01

.62

3.0

3

210 200 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm

14.2

7

22.8

42

9.3

42

9.5

22

9.8

53

1.8

63

2.0

7

44.3

5

47.3

9

53.8

5

66.8

2

69.8

2

84.6

2

114

.58

114

.80

117

.35

120

.15

120

.53

125

.08

127

.18

127

.86

128

.03

128

.38

130

.46

130

.55

132

.38

132

.44

136

.60

138

.24

138

.27

141

.48

143

.93

152

.87

156

.63

161

.26

163

.72

169

.12

211

.10

S 64

ORTEP plots:

Figure S 2. ORTEP plot of compound 1.

S 65

Figure S 3. ORTEP plot of compound 3.

S 66

Figure S 1. ORTEP plot of compound 5a.

S 67

References:

[1] Perrin, D. D.; Armarego, W. L. F. Purification of Laboratorial Chemicals; Wiley-VCH:

Weinheim, 1998.

[2] Moss, G. P. Pure Appl. Chem. 1998, 70, 143–216. doi:10.1351/pac199870010143

[3] Claisen, L.; Eisleb, O. Justus Liebigs Ann. Chem. 1913, 401, 21–119.

[4] Partridge, M. W. J. Chem. Soc. 1949, 3043–3046.

[5] Leuck, M.; Kunz, H. Carbohydr. Res. 1998, 312, 33–44. doi:10.1016/S0008-

6215(98)00223-7

[6] Penke, B.; Rivier, J. J. Org. Chem. 1987, 52, 1197–1200. doi:10.1021/jo00383a004

[7] Guibe, F.; Saint M'Leux, Y. Tetrahedron Lett. 1981, 22, 3591–3594. doi:10.1016/S0040-

4039(01)81967-5

[8] Roush, W. R.; Hartz, R. A.; Gustin, D. J. J. Am. Chem. Soc. 1999, 121, 1990–1991.

doi:10.1021/ja984229e

[9] Zhao, W.; Carreira, E. M. Org. Lett. 2003, 5, 4153–4154. doi:10.1021/ol035599x

[10] Gabbutt, C. D.; Hepworth, J. D.; Heron, B. M.; Rahman, M. M. J. Chem. Soc., Perkin

Trans. 1 1994, 1733–1737. doi:10.1039/P19940001733

[11] Schareina, T.; Zapf, A.; Beller, M. Chem. Commun. 2004, 1388–1389.

doi:10.1039/b400562g

S 68

Part II Time-resolved photophysical spectroscopy

Material and Methods

Time-Resolved-Spectroscopy

The chromene was dissolved in acetonitrile (as received from Merck, purity 99%) at a

concentration in the millimolar range giving rise to an absorption of 0.4 OD at ~345 nm (optical

path of 0.5 mm in a fused silica flow-cell). This stock solution was directly used for the time-

resolved fs-experiments and diluted (1/10) for laser-flash-spectroscopy.

Femtosecond pump-probe spectroscopy in the visible and near ultraviolet spectral range

was used to investigate the reaction dynamics of the photoinduced ring-opening of chromenes.

The apparatus is described in more detail in ref. [1]. Briefly, a homebuilt Ti:Sa based laser-

amplifier-system generated ultrashort pulses with a duration of ~100 fs at a repetition rate of

~1 kHz. The excitation pulses at 340 nm with an energy between 250 to 500 nJ where generated

via a non-collinear optical parametric amplifier (NOPA) [2] in combination with frequency

doubling in a 100 µm BBO-crystal (type I). A white light continuum from CaF2 served as probe

pulse (380 to 650 nm) [3] to record the absorption changes induced by the pump-pulse. The

transient spectra at various delay times between pump and probe pulse were recorded using a

multi-channel detection setup [4]. The instrumental response time (FWHM of the cross-

correlation trace) was determined to be ~250 fs. The spot diameter of the pump-light was

adjusted to ~120 µm providing homogeneous excitation density for the probe-pulse (diameter

~60 µm). The polarization of pump and probe pulses at the sample location were set magic angle

(54.7°).

A homebuilt laser-flash spectrometer was used for the investigation of the transient

absorbance changes in a time-range from nanoseconds to microseconds. The sample was excited

with a pulsed Nd:YAG laser (3rd harmonic, 355 nm, pulse duration ~7 ns) at a repetition rate of

S 69

40 Hz. The transient absorbance changes of the sample were investigated at ~460 nm using a

high-power laser-LED (Luxeon, High Power LED, 1 W, Osram GmbH, 457 nm, ~20 nm spectral

width) and a photodiode (Thorlabs DET10A/M) coupled to an oscilloscope (Tektronix TCS

320D). A temporal resolution of the setup of ~ 8 ns could be achieved. Further details are found

in refs. [5,6].

References

[1] Cordes, T.; Weinrich, D.; Kempa, S.; Riesselmann, K.; Herre, S.; Hoppmann, C.; Rück-

Braun, K.; Zinth, W. Chem. Phys. Lett. 2006, 428, 167–173.

doi:10.1016/j.cplett.2006.07.043

[2] Riedle, E.; Beutter, M.; Lochbrunner, S.; Piel, J.; Schenkl, S.; Spörlein, S.; Zinth, W.

Appl. Phys. B 2000, 71, 457–465. doi:10.1007/s003400000351

[3] Huber, R.; Satzger, H.; Zinth, W.; Wachtveitl, J. Opt. Commun. 2001, 194, 443–448.

doi:10.1016/S0030-4018(01)01324-4

[4] Seel, M.; Wildermuth, E.; Zinth, W. Meas. Sci. Technol. 1997, 8, 449–452.

doi:10.1088/0957-0233/8/4/014

[5] Schmidhammer, U.; Roth, S.; Riedle, E.; Tishkov, A. A.; Mayr, H. Rev. Sci. Instrum.

2005, 76, 093111. doi:10.1063/1.2047828

[6] Elsner, C. Ultrakurzzeitspektroskopie zum Schaltverhalten substituierter Diarylethene.

Ph.D. Thesis, LMU München, Germany, 2008.

O

MeO2C

10