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Cross-Aromaticity in annulated benzene and analogs Advisor: Jun Zhu Reporter: Yulei.Hao - PowerPoint PPT Presentation
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Cross-Aromaticity in annulated benzene and
analogs
Advisor: Jun Zhu
Reporter:
Yulei.Hao
Date: 2014.3.14
23/4/21 1
Results and Discussion
Futher Work
Background
Computational Methods
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BackgroundBackground
α
β
Mills–Nixon effect : Geometric changes of the benzene ring due to annulation by small, strained rings. in terms of the stability of the Kekulé resonance structures, it favor the resonance structure with the double bonds exo to the strained annulated ring.
exoendo
108 1=13
2=1
α=360。
-2βMills, W.H.; Nixon, I.G. J.Chem.Soc. 1930, 2510
23/4/21 3
BackgroundBackground
Coupling of diazo-compounds and Bromination
O2N1.3781.373
1.371
1.367 1.378
1.3911.501
Fuller, F. J.; Valente, J. E. J.Chem.Cryst. 1996, 26, 815.
Mills, W.H.; Nixon, I.G. J.Chem.Soc. 1930, 2510
4
5
6
7
HO
4
5
6
7
HO
N NClN N
OH
N NClH3C
Br2 OHR
R
Br
HO
R
N NH3C
4
5
6
7
HO
N NH3C 4
5 6
7
HO
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BackgroundBackground
“The field of the cycloproparene chemistry can be aptly regarded as something of a Cinderella area since the simple beginnings have led to a wealth of fascinating and fruitful chemistry far beyond expectation in 1960s.” ----Brian Halton Chem. Rev. 2003, 103, 1327-1369
1.334
1.382
1.390 1.360
[1] Vogel, E.; Grimme, W.; Korte, S. Tetrahedron Lett. 1965, 6, 3625.
COOCH3
COOCH3
TM.1
The synthesis some of cycloproparens:The synthesis some of cycloproparens:
TM.1
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1.3331.381
1.393
1.3931.518
1.566+
CH2OCH3
Si(CH3)3
CpCo(CO)2
n-octane
CH2OCH3
Si(CH3)3
1. Br2
2. BuLiTM.2
[2]
[3]
[4]
1.375
1.355
1.440
1.448
1.4201.374
1.415
Cl
Cl
KO-t-Bu
dry THFCl Cl TM.3
Ph
Ph1.355
1.3731.382
1.388BuLi Me3SiCl H
SiMe3
BuLi
SiMe3
Ph2COTM.4
TM.2
TM.3
TM.4
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Computational MethodsComputational Methods
G03 program
OPT : B3LYP/6-311++G*
NICS: B3LYP/6-311++G*
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Results and DiscussionResults and Discussion
Figure 1. Monomers of annulated rings in calculation.
Figure 2. Combination of non-π aromatic monomers.
monomer
G=0.86
1 2
3 4
Compounds NICS(0) NICS(1)zz
cyclopropane -42.73 -24.16
3 -47.57 -21.40(-23.53)a
4 -41.96 -18.26(-26.20)
cyclopropene -28.49 -16.17
1 -36.96 1.8
2 -40.57 -27.97(-7.52)
cyclobutane 3.11 5.54
4 -6.74 0.59(3.43)
Table 2. Comparing NICS values(ppm) of 1, 2, 3 and 4 with their monomers. a Numbers in the brackets are NICS(1)zz opposite the dihedral.
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Results and DiscussionResults and Discussion
(1.498)1.503 1.348(1.334)
(1.367)1.3771.401(1.390)
1.350
1.3951.384
1.3571.361
1.3801.431
5 6 7 8
1.583
1.5231.394
1.386
(1.348)1.356
1.406(1.393)
1.350(1.333)
1.402(1.393)
1.401
1.408
1.400
1.364(1.364)
(1.412)1.415
1.384
9 10 11 12
13 14 15
1.394 1.381
1.5821.581
1.581
1.505(1.498)
1.505(1.504)
1.503(1.512)
Figure 3. Selected bond distances(Å) for 5-15.
1.3281.368(1.375)
1.399 1.356(1.354)
1.337
1.329
1.363(1.360)
1.368
1.329
16 17
18
19
20
21
22
1.406 1.397
1.398
1.359(1.352)
1.401
Figure 4. Selected bond distances(Å) for 16-22.
1.291
1.511
(1.391)1.394
1.431
1.420 1.374
1.415
1.339
1.519
1.573
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Results and DiscussionResults and Discussion
Compounds aΔR ΔR
5 0.034 16 0.073
6 0.040 17 0.012
7 -0.051
8 -0.027 18 0.069
19 0.069
9 0.016 20 -0.004
10 -0.006 21 0.029
11 -0.020 22 0.072
12 -0.024
13 0.039
14 0.036
15 -0.041
Table 3. ΔR(Å) for compounds 5-22. R defined as the endo distance minus the exo distance. The bond between the two rings is used as the exo bond, and the maximum of the difference is used for the asymmetric compounds.
We can conclude that the bond length in benzene and naphthalene of these compounds change slightly after fused by small strained rings, impling the retained π aromaticity.
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compounds 3- /4-membered rings 6-membered rings
NICS(0) NICS(1)zz NICS(0) NICS(1)zz
monomers
-28.49 -16.17 -8.02 -29.255 -21.10 -14.48 -7.98 -27.556 -20.91 -6.69 -7.56 -25.857 -18.29 -14.18 -7.79 -26.598 -15.99 -14.72 -11.19 -29.20
monomers
1.43 0.14 -8.41 -29.059 -3.52 3.04 -8.40 -27.7710 2.85 2.80 -8.90 -26.2011 3.30 3.12 -8.65 -26.3912 3.40 3.45 -9.37 -25.23
13 -20.99/ 4.46 -14.20/ 3.11 -8.26 -26.2014 -21.56/ 2.55 -14.34/ 2.11 -8.49 -26.2115 -20.96/4.91 -13.83/ 3.53 -8.89 -25.02
16 -22.29 -13.14 -8.95/ -7.95 -26.88/ -27.8717 -19.85 -13.55 -8.10/ -8.40 -26.60/ -29.0018 -19.51 -12.80 -9.33/ -6.72 -29.56/ -26.5319 -22.12 -13.01 -8.02 -27.5420 -20.65 -13.54 -7.89 -26.4021 -20.19/ -22.49 -13.56/ -25.26 -7.39/ -8.80 -25.26/ -28.6622 -21.93 -12.99 -8.24 -27.81
Table 4. NICS(0) and NICS(1)zz of computed compounds
1.503
1.348
1.377 1.4011.350
1.395
5 6
1.3841.3571.361
1.3801.431
7 8
1.291
1.511 1.394 1.431
1.420 1.374
1.415
1.339
1.519
1.573
1.583
1.5231.394
1.3861.400
9 10
1.394
1.582
1.401
1.408
1.384
11 12
1.3811.581
1.581
1.356
1.406
1.350
1.402
1.364
1.415
13 14 15
1.3281.368
1.399 1.356
1.337
1.329
1.363
1.368
1.329
16 17
18
19
20
21
22
1.406 1.397
1.398
1.359
1.401
The aromaticity of both are The aromaticity of both are not destroyed.not destroyed.
23/4/21 11
Results and DiscussionResults and Discussion
Table 3. Smooth line of NICS(0) vs exo bond distance of compounds 5-22.
NICS(0) -28.49
1.291
1.511
We can conclude that the π-aromaticity in benzene and naphthalene weaken the σ-aromaticity in cyclopropene, and strengthen the σ-antiaromaticity in cyclobutene.
NICS(0) 1.43
1.339
23/4/21 12
G=5.47
13 (Cs)14 (C2v)
G=1.89
6 (D2h) 7 (C2v)
10 (D2h) 11 (C2v)
G=2.57
17 (C2v) 16 (Cs)
G=1.01
18 (C2v)19 (C2v)
20 (D2h) 21 (Cs) 22 (C2h)
G=0.17 G=0.76
G=0.83
G=3.02
Figure 5. The Gibbs Free Energy(in kcal.mol-1) of some compounds to their isomers.
We can conclude that those compounds with higher symmetry are more stable.
Results and DiscussionResults and Discussion
23/4/21 13
Futher WorkFuther Work
……
23/4/21 14
Thank you for listening!
23/4/21 15