CaRLa Winter School 2008 Final Programcarla-hd.de/wp-content/uploads/2018/02/CaRLa-Winter-School-2008-… · Department of Chemistry and Applied Biosciences, Swiss Federal Institute

CaRLa Winter School 2008 Heidelberg

23.02.2008 – 29.02.2008

Final Program

1

Welcome to the first CaRLa Winter School

Welcome to the picturesque town of Heidelberg, welcome to CaRLa, the joint Catalysis Research Laboratory of BASF and the University of Heidelberg and welcome to our first CaRLa Winter School on Homogeneous Catalysis! With our Winter School, we aim to foster intense scientific exchange between established and young researchers in the field of homogeneous catalysis. The conference takes place from February 23, 2008 – February 29, 2008 at the German-American-Institute downtown Heidelberg, within walking distance to the old town. We have chosen “Rational design of homogeneous catalysts?” as the scientific motto of the conference and we hope to initiate discussion and exchange about this topic throughout the conference. Our scientific program consists of 1 Keynote Lecture, 10 lectures, 10 problem set sessions and poster presentations. The days are organized as a morning and afternoon session. Each session is divided into two parts; the first part consists of a scientific lecture while the second part has a more educational focus. Between the two sessions of the day, we have scheduled a prolonged lunch break for individual use. In the evening, we have planned very short poster presentations of selected poster contributions, after which a light dinner is served in parallel with the poster sessions. All presentations are scheduled to leave enough room for discussion and we encourage every participant to use this time to make our Winter School an exciting event for science. The conference is fully sponsored by BASF and we are happy to announce, that we will have the opportunity for making an excursion to BASF on Wednesday afternoon. We hope that all participants will have a pleasant and scientifically stimulating stay in Heidelberg during our Winter School. If we can assist you in any way to make your stay in Heidelberg more pleasant, please do not hesitate to contact us.

Christoph Jäkel Peter Hofmann

2

Program of the CaRLa Winter School - Overview

All Sessions will take place at the German-American-Institute in Heidelberg

3

Saturday, 23th February until 16:00 Arrival 16:30 Welcome Address 17:00 Key Note Lecture

“Raw Material Change and Dream Reactions Rainer Diercks in the Chemical Industry”

18:30 Snacks and “Get-together”

4

Sunday, 24th February 9:00 Lecture

“Enantioselective Catalysis and Organofluorine Antonio Togni

Chemistry”

10:30 Coffee Break

11:00 Training Session

“Isotope Effects as Mechanistic Tools in Antonio Togni

Catalytic Reactions”

12:00 Lunch Break

14:30 Lecture

“Iridium - Newcomer with Potential in Organic Günther Helmchen

Synthesis and Catalysis”

16:00 Coffee Break


“Metal-Catalyzed Asymmetric Allylic Günther Helmchen

Substitutions in Natural Products Synthesis”

17:30 Poster Presentation

18:00 Poster Session including light dinner All

5

Monday, 25th February 9:00 Lecture

“Discovery and Surprises with Small Molecules” Erick Carreira

10:30 Coffee Break


“Surprises and Discovery with Natural Products” Erick Carreira

12:00 Lunch Break

14:30 Lecture

“New Hydrogenation Catalysts and New Charles P. Casey

Mechanisms for Hydrogenation”

16:00 Coffee Break


“Model studies of elementary steps” Charles P. Casey



6

Tuesday, 26th February 9:00 Lecture

“New Stoichiometric and Catalytic Transform- T. Don Tilley

ations involving Transition Metal-Silicon Systems”

10:30 Coffee Break


“Issues in Electron-Counting and Mechanisms for T. Don Tilley

Bond Activations in Organo-metallic Systems”

12:00 Lunch Break

14:30 Lecture

“Molecular-defined Catalysts for the Synthesis Matthias Beller

of Fine and Bulk Chemicals”

16:00 Coffee Break


“Catalytic Synthesis of Agrochemicals and Matthias Beller

Pharmaceuticals”



7

Wednesday, 27th February 9:00 Lecture

“Industrial Homogeneous Catalysis-Part 1” Rocco Paciello

10:30 Coffee Break


“Industrial Homogeneous Catalysis-Part 2” Rocco Paciello

12:00 Lunch Break

13:15 Transfer to Ludwigshafen All

14:00 Excursion of BASF’s Main Site in Ludwigshafen All

19:00 Winter School Dinner in “Kulturbrauerei” All

8

Thursday, 28th February 9:00 Lecture

“New Invention of Highly Selective Organo- Tobin J. Marks

f-Element Centered Catalytic Transformations.

Thermodynamics, Mechanism, and Selectivity”

10:30 Coffee Break


“Metal-Ligand Bonding Energetics and the Tobin J. Marks

Invention of New Homogeneous Catalytic Reactions”

12:00 Lunch Break

14:30 Lecture

“Cross-dehydrogenative Couplings and Related Frank Glorius

Transformations: Direct Formation of C-C- Bonds”

16:00 Coffee Break


Cross-dehydrogenative Couplings and Related Frank Glorius

Transformations: Direct Formation of C-C- Bonds”



9

Friday, 29th February 9:00 Lecture

“Preparative Methods for Alkane C-H Bond Peter R. Schreiner

Functionalizations”

10:30 Coffee Break


“C-H Bond Functionalization as Key Step in Peter R. Schreiner

Total Synthesis”

12:00 Closing Remarks

12:15 Departure

10

Lecture Abstracts

11

Raw Material Change and Dream Reactions of the Chemical Industry Rainer Diercks

Chemicals Research and Engineering

BASF SE, D-67056 Ludwigshafen, Germany

e-mail: [email protected]

At each time availability and price structure of the fossil raw materials coal, petroleum and natural gas have significantly influenced the technological basis and consequently the buildup and development of industrial chemistry. In the energy industry a consistent raw material change from coal to oil and gas has been carried out since the middle of the 20th Century. The reason for this change lies in the price advantages, simpler logistics as well as the versatile usefulness of oil and gas. Parallel to the change in the energy industry the raw material basis of the chemical industry has been changed over from coal to oil and gas. Olefins, which are produced mainly by steam cracking of naphtha, and aromatic hydrocarbons, are still the crucial raw materials for the majority of the value added chains of the chemical industry. Price volatility, regional distribution and the finite reserves of crude oil are the main drivers for the development of conversion technologies to utilize alternative raw materials, e.g. natural gas, coal and renewables as feedstocks for the chemical industry.

12

Enantioselective Catalysis and Organofluorine Chemistry Antonio Togni

Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology,

ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland


Ti(TADDOLato) complexes of type 1 are able to catalyze enantioselective electrophilic atom-transfer reactions with 1,3-dicarbonyl compounds involving fluorine,1 chlorine, oxygen, and sulfur. These reactions share common mechanistic and stereochemical features.2

R

R Cl

Ti

Cl

OO

NCMeMeCN

OO

Np

Np

Np

Np

1 Np = 1-naphthyl)

IO CF3

2

A possible extension of the underlying concept concerns trifluoromethylation reactions with new reagents of type 2. These hypervalent trifluoromethyliodine species smoothly react with 1,3-dicarbonyl compounds, α-nitro esters (Cu(I) catalysis) but also with aromatic heterocycles, as well as with functionalized thiols and secondary phosphines, formally delivering CF3

+.3 1 Hintermann, L.; Togni, A. Angew. Chem. Int. Ed. 2000, 39, 4359. 2 Perseghini, M.; Massaccesi, M.; Liu, Y.; Togni, A. Tetrahedron 2006, 62, 7180. 3 Kieltsch, I.; Eisenberger, P.; Togni, A. Angew. Chem. Int. Ed. 2007, 46, 754.

13

Iridium-Catalyzed Allylic Substitutions - Method Development and Applications

Günter Helmchen

Organisch-Chemisches Institut der Universität Heidelberg


Ir-complexes have been developed recently as catalysts for allylic substitu-tions of monosubstituted allyl derivatives. 1

b

[Ir(COD)Cl]2 / L*Additive, THF

Nu

R R Nu+

l

R OCO2Me*Nu

96-99 %eeb/l up to > 99:1

R = Ph, (E)-CH=CHPh, CH2CH2Ph, CH2OTBDPS

Nu = RR'NH, CH(COOR)2, OR

Phosphoramidites, introduced by Alexakis and Feringa, are effective ligands for these reactions. Particularly good results with respect to enantio- and re-gioselectivity were achieved by base-promoted C-H activation of their Ir-complexes. A cyclometallated complex with R = Ph was characterized by Hartwig et al.2

O

OP N

(S,S,aS) L

N

Ar

O

O PL

Ir

H3C

Ar

activated catalyst

R

R

1G. Helmchen, A. Dahnz, P. Dübon, M. Schelwies, R. Weihofen, Chem. Comm. 2007, 675. 2A. Leitner, S. Shekhar, M. J. Pouy, J. F. Hartwig, J. Am. Chem. Soc. 2005, 127, 15506.

14

Discovery and Surprises with Small Molecules

Prof. Dr. Erick M. Carreira Laboratorium für Organische Chemie, ETH-Zurich HCI H 335, CH-8093 Zurich,

Switzerland


The talk will focus on a number of different investigations that are on-going in the area of catalytic asymmetric synthesis. The design, synthesis, and study of novel chiral ligands for metals offer new opportunities in the development of reaction processes leading to useful building blocks for chemical synthesis. We have become interested in addressing the question of whether chiral dienes could be employed as ligands for enantioselective reaction processes involving late transition-metals. Consequently, we have been investigating chiral dienes as ligands in reactions involving organometallic intermediates. We intend to discuss and present [2.2.2]-bicyclooctadienes as a new family of ligands. These are notable because of their convenient preparation in optically active form from (R)- or (S)- carvone. We demonstrate the potential utility of these ligands in several different processes. In the final part of the discussion we will present new readily available atropisomeric P,N-ligands (PINAP) which bear structural similarity and reactivity parallels to QUINAP. They have the added advantage, however, that, unlike QUINAP, they are conveniently prepared and resolved as well as easily amenable to structural and electronic modifications. We describe their syntheses and applications in reactions involving Rh-, Ag-, and Cu-catalysts, demonstrating their utility. For the Cu-catalyzed coupling of acetylenes and imines they are found to be superior to QUINAP, affording products with the highest enantioselectivity reported to date.

15

New Hydrogenation Catalysts and New Mechanisms for Hydrogenation Charles P. Casey, Steven W. Singer, Jeffrey B. Johnson, Sharon E. Beetner, Neil A. Strotman, Thomas E. Vos, Galina A. Bikzhanova, Hairong Guan, and Timothy B. Clark

Department of Chemistry, University of Wisconsin-Madison, Madison WI 53706 USA


New catalysts for the hydrogenation of polar functional groups have recently been discovered that deliver a hydride from the metal center and a proton from the acidic center to an aldehyde or ketone. The mechanism of hydrogenation by Shvo’s diruthenium bridging hydride catalyst will be discussed.1 Unlike other hydrogenation catalysts, hydrogen transfer occurs without prior coordination of the substrate to the metal. The rates of all the individual steps in the catalysis have been independently measured at various temperatures and provided an accurate model of the complex overall kinetics of catalysis.2 These studies demonstrate that the majority of the metal complex is tied up an inactive bridging hydride. Our efforts to find more active monometallic hydrides have led to the successful development on a new iron catalyst.3 1 Casey, C. P.; Singer, S. W.; Powell, D. R.; Hayashi, R. K.; Kavana, M. J. Am. Chem. Soc., 2001, 123, 1090-1100. Casey, C. P.; Johnson, J. B.; Singer, S. W.; Cui, Q. J. Am. Chem. Soc. 2005, 127, 3100-3109. Casey, C. P.; Clark, T. B.; Guzei, I. A. J. Am. Chem. Soc. 2007, 129, 11821-11827. 2 Casey, C. P.; Beetner, S. E.; Johnson, J. B. J. Am. Chem. Soc. 2008, 130, ASAP. 3 Casey, C. P. and Guan, H. J. Am. Chem. Soc. 2007, 129, 5816-5817.

16

New Stoichiometric and Catalytic Transformations involving Transition Metal-Silicon Systems

Paul Hayes, Paul Glaser, Elisa Calimano, Preeyanuch Sangtrirutnugul, Jonas Peters, Jay Feldman, Gregory Mitchell and T. Don Tilley*a

aDepartment of Chemistry, University of California, Berkeley,

Berkeley, California 94720-1460 USA


Transition metal compounds are widely employed as reagents and catalysts for chemical conversions. The great utility of metal complexes in this regard derives from their ability to activate small molecule substrates toward a variety of different transformations. These activations are associated with a small number of fundamental steps, such as binding, oxidative addition and insertion. Along these lines, new platinum complexes have been prepared, featuring chelating ligands containing silicon and nitrogen atom donors. These ligands are designed to stabilize platinum in higher oxidation states, and this appears to be an important factor in a new hydrosilation mechanism that has been identified. A lesser-known fundamental process involves the migration of a substituent from a donor atom to the metal. This type of 1,2-shift, which can (for example) take a complex of the general form LnM-Si(R)Xm to a more reactive Ln(R)M=SiXm structure, represents a potentially important step in substrate activation and catalysis. Such migrations may be coupled with oxidative addition to provide the direct conversion of a free silane to a silyene complex. This chemistry may also be incorporated into the design of new hydrosilation catalysts.

17

Molecular-defined Catalysts for the Synthesis of Fine and Bulk Chemicals

Matthias Beller*a

aAlbert-Einstein-Strasse 29a, 18059 Rostock


More than 80% of all products of the chemical industry are made via catalysis. In this regard catalysis is a key factor for achieving a sustainable production of chemicals today and in the future. In the talk it will be shown that molecular-defined palladium, copper, and iron catalysts enable chemists to perform their organic syntheses more selectively and with improved economics. Examples which demonstrate the superiority of catalytic processes compared to more traditional stoichiometric reactions will include hydrogenations1 and oxidation reactions2 as well as modern CC-coupling reactions.3In the talk the development and optimization of practical catalysts will be demonstrated and their industrial application shown.

1. S. Enthaler, G. Erre, M. K. Tse, K. Junge, M. Beller, Tetrahedron Lett. 2006, 47, 8095-

8099.

2. M. K. Tse, C. Döbler, S. Bhor, M. Klawonn, W. Mägerlein, H. Hugl, M. Beller, Angew.

Chem. 2004, 116, 5367-5372; Angew. Chem. Int. Ed. 2004, 43, 5255-5260; b) G.

Anilkumar, B. Bitterlich, F. Gadissa Gelalcha, M. K. Tse, M. Beller, Chem. Commun.

2007, 289-291.

3. a) S. Klaus, H. Neumann, A. Zapf, D. Strübing, S. Hübner, J. Almena, T. Riermeier, P.

Groß, M. Sarich, W.-R. Krahnert, K. Rossen, M. Beller, Angew. Chem. Int. Ed. 2006, 45,

154-156; b) I. Iovel, K. Mertins, J. Kischel, A. Zapf, M. Beller, Angew. Chem. Int. Ed.

2005, 44, 3913-3916;.

18

Industrial Homogeneous Catalysis: Part 1 Dr. Rocco Paciello

Basic Chemicals Research

BASF SE 67056 Ludwigshafen, Germany


Homogeneous catalysis at BASF will be discussed using the hydroformylation of olefins as a typical example. Hydroformylation, at ca. 9 mio tons of production annually, is one of the largest homogeneously catalyzed processes in the chemical industry. At 1.9 mio tons/year production, it is a core technology area of BASF. Lower olefins such as ethylene, propylene and butenes are typically hydroformylated under low pressure conditions using ligand modified rhodium catalysts. The hydroformylation of propylene alone accounts for approximately three fourths of the world wide production volumes. Due to their economic significance, low pressure catalysts have been intensively investigated in the last decades and have accordingly reached a high degree of development. BASF efforts to design new ligands and understand the mechanism of the reaction will be discussed.

19

Invention of Highly Selective Organo-f-Element Centered Catalytic Transformations. Thermodynamics, Mechanism, and Selectivity

Tobin J. Marks*

Department of Chemistry, Northwestern University [email protected]

The lanthanides and actinides offer many intriguing and instructive characteristics for stoichiometric and catalytic transformations, including large and incrementally tunable ionic radii, high electrophilicity, high kinetic lability, predictable and constrained formal oxidation states, polar metal-ligand bonding, built-in paramagnetic probes, relatively high abundance, and relatively low toxicity. This lecture describes recent exploratory synthetic, mechanistic, and thermochemical research aimed at inventing new, unusual, and useful transformations mediated by complexes of these elements, and comparing 4f vs. 5f pathways. This includes the addition of element-hydrogen bonds to unsaturated hydrocarbons (“hydrofunctionalization”) to effect C-N, C-O, C-P, C-Si, and C-B bond forming processes. The goals are to rationally design, catalyze, and understand highly selective processes involving single additions, cascades of multiple bond fusions, and bond fusions coupled to polymerization processes.1,2

1 Amin, S.B.; Marks, T.J. Versatile Routes to In Situ Polyolefin Functionalization with Heteroatoms. Catalytic Chain Transfer, Angew. Chem. Int. Ed., in press (review). 2 Hong, S.; Marks, T.J. Organolanthanide-Catalyzed Hydroamination, Acc. Chem.

Res., 2004, 37, 673-686 (review).

20

Cross-dehydrogenative Couplings and Related Transformations: Direct Formation of C-C-Bonds

Frank Glorius*

Organisch-Chemisches Institut der Westfälische Wilhelms-Universität Münster,

Corrensstraße 40, 48149 Münster, Germany


Cross-coupling reactions have revolutionized the field of organic synthesis. However, in recent years, the area of CH-activation has received increasing attention.1 Breakthroughs in the field allow a more efficient use of limited natural resources and present versatile additions to the synthetic armory. Since each prefunctionalization has to be paid for, an approach enabling the direct transformation of a C-H bond seems to be more attractive than the traditional cross-coupling approach. Within the field of CH activations, the direct oxidative cross-coupling of two C-H bonds into a C-C bond is especially challenging.

R1 H H R2 R1 R2+

catalystoxidizing agent

R1 X M R2 R1 R2+catalyst

Traditional cross-coupling approach:

Direct oxidative cross-coupling:

This lecture will focus on newest developments in this field, including the discussion of reaction mechanisms and a critical evaluation of the synthetic value.

1 a) Stuart, D. R.; Fagnou, K. Science 2007, 316, 1172-1175. b) Alberico, D. ; Scott, M. E.;

Lautens, M. Chem. Rev. 2007, 107, 174-238. c) Dick, A. R.; Sanford, M. S. Tetrahedron

2006, 62, 2439-2463. d) Zhang, Y.; Li, C.-J. Eur. J. Org. Chem. 2007, 4654-4657 and

references cited therein.

21

Preparative Methods for Alkane C-H Bond Functionalizations Schreiner, Peter R.

Justus-Liebig-University, Institute of Organic Chemistry, Heinrich-Buff-Ring 58, 35392

Giessen, Germany


As the main constituent of natural gas, alkanes are Nature's most plentiful organic base chemicals. Chemists have long coveted the use of alkanes as feedstock for clean-burning fuels, plastics, solvents, new materials, and pharmaceuticals, and the selective functionalization of aliphatic hydro-carbons is considered a “holy grail” in chemistry.[1] With increasing energy consumption and the growing demand for bulk chemicals, solving this problem is essential and provides an exquisite scientific challenge.

The lecture will focus on mechanistic as well as practical aspects of alkane and alkyl group functionalization chemistry reviewing its fundamental challenges. This will mainly concentrate on single-electron transfer (SET) chemistry[2] and metal-free selective radical methods.[3] The use of transition metals for C–H insertions into hydrocarbon bonds, will be covered in part. Since there is still limited insight into the mechanisms of alkane activation reactions, the lecture will also emphasize the very fruitful combination of experiment and theory in elucidating these. [1] a) B. A. Arndtsen, R. G. Bergman, Science 1995, 270, 1970-1973; b) S. E. Bromberg, W. Yang, M. C. Asplund, T. Lian, B. K. McNamara, K. T. Kotz, J. S. Yeston, M. Wilkens, H. Frei, R. G. Bergman, C. B. Harris, Science 1997, 178, 260-263; c) A. A. Fokin, P. R. Schreiner, Chem. Rev. 2002, 102, 1551-1593. [2] a) A. A. Fokin, T. E. Shubina, P. A. Gunchenko, S. D. Isaev, A. G. Yurchenko, P. R. Schreiner, J. Am. Chem. Soc. 2002, 124, 10718-10727; b) A. A. Fokin, P. R. Schreiner, P. A. Gunchenko, S. A. Peleshanko, T. E. Shubina, S. D. Isaev, P. V. Tarasenko, N. I. Kulik, H. M. Schiebel, A. G. Yurchenko, J. Am. Chem. Soc. 2000, 122, 7317-7326. [3] a) A. A. Fokin, P. R. Schreiner, Adv. Synth. Cat. 2003, 345, 1035-1052; b) P. R. Schreiner, O. Lauenstein, E. D. Butova, P. A. Gunchenko, I. V. Kolomitsin, A. Wittkopp, G. Feder, A. A. Fokin, Chem. Eur. J. 2001, 7, 4996–5003.

22

Training Session Abstracts

23

Isotope Effects as Mechanistic Tools in Catalytic Reactions Antonio Togni

Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology,

ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland


The study of kinetic isotope effects is an important instrument for the elucidation of reaction mechanisms. This session will illustrate some typical examples of deuterium primary, secondary and inverse secondary effects in a variety of catalytic reactions,1 such as C-H activation, olefin polymerization and epoxidation, nucleophilic additions to olefins etc. 1 Literature references will be provided during the session.

24

Applications of Allylic Substitutions in the Synthesis of Biologically Active Compounds

Günter Helmchen

Organisch-Chemisches Institut der Universität Heidelberg


Palladium- and Iridium-catalyzed allylic substitutions have been often app-lied in organic synthesis. Examples as well as problems will be presented.

25

Surprises and Discoveries with Natural Products

Prof. Dr. Erick M. Carreira Laboratorium für Organische Chemie, ETH-Zurich HCI H 335, CH-8093 Zurich,

Switzerland


Natural products chemistry can offer immense opportunities for the study of biological processes, discovery of novel therapeutics, as well as for the development of novel strategies and methods for chemical synthesis. We have been involved in the study of several biologically active natural compounds with the aim of identifying novel chemical transformations and tactics as well as ultimately providing tools for studies in bioorganic chemistry. We will present a lecture that highlights these investigations. New derivatives of Amphotericin B (AmB) were synthesized through a double reductive alkylation of the mycosamine. These derivatives of AmB displayed superior antifungal activity against Saccharomyces cerevisiae wild type strain and especially in the case of an AmB-resistant Candida albicans strain. Moreover, these compounds display significantly reduced hemotoxicity compared to AmB. Furthermore, the same mycosamine modification can lead to improved properties with other well known polyene macrolide antibiotics; this would suggest that the specific modification can be employed to provide insight into biological processes in yeast.

26

Issues in Electron-Counting and Mechanisms for Bond Activations in Organometallic Systems

T. Don Tilley*a

aDepartment of Chemistry, University of California, Berkeley,

Berkeley, California 94720-1460 USA


The first topic will include electron bookkeeping rules for transition-metal organometallic compounds, and how they may be used to interpret structure, bonding and reactivity in cases involving metal-metal bonds and bridging ligands. This topic will address cases that are particularly complicated and perhaps controversial. A second topic will address mechanistic issues in reactions involving sigma bond metathesis. Simple reactivity and catalysis will be included. If time allows, the mechanisms of late metal-mediated activations of N-H and C-H bonds, and the possible role of proton transfers in this chemistry, will be addressed.

27

Catalytic Synthesis of Agrochemicals and Pharmaceuticals Matthias Beller*

Leibniz-Institut für Katalyse, Albert-Einstein-Strasse 29a, 18059 Rostock


Several examples of the retrosynthesis of biologically active compounds will be discussed. Details will be given on the mechanism and catalyst design.

28

Industrial Homogeneous Catalysis: Part 2 Dr. Rocco Paciello

Basic Chemicals Research

BASF SE 67056 Ludwigshafen, Germany


Homogeneous catalysis at BASF will be discussed using the

hydroformylation of olefins as a typical example. The higher alcohols and aldehydes produced in this manner are intermediates for large-scale applications, such as plasticizers, detergents and fuel additives, as well as being useful in the synthesis of fine chemicals such as vitamins or flavors and fragrances. Most of these products are still made using high pressure technologies. The advantages and disadvantages of different technologies presently in use or being developed will be discussed. The interplay between catalyst properties and process technology will be emphasized.

29

Metal-Ligand Bonding Energetics and the Invention of New Homogeneous Catalytic Reactions

Tobin J. Marks* Department of Chemistry, Northwestern University

[email protected]

As we develop new, ever more selective catalytic transformations and strive increasingly to invent new ones, it is only natural that we inquire more about the strengths of metal-ligand bonds being made and broken in the complexes we are studying.1-3 This tutorial focuses on: 1. Definitions of metal-ligand bonding energetics 2. How metal-ligand bond energies are measured experimentally 3. Examples in which this information helps us to understand the pathways of catalytic reactions or the challenges such processes encounter. 4. Examples in which this information is used to predict new catalytic transformations. 1 Review articles: (a) Armentrout, P.B. Gas-Phase Organometallic Chemistry Topics in Organometallic Chemisty 1999, 4, 2-45. (b) Hoff, C.D. "Thermodynamics of Ligand Binding and Exchange in Organometallic Reactions" Prog. Inorg. Chem. 1992, 40, 503-561. (c) Martinho Simões, J.A., ed. "Energetics of Organometallic Species" Kluwer: Dordrecht, 1992. (d) Martinho Simões, J.A.; Beauchamp, J.L. Transition Metal-Hydrogen and Metal-Carbon Bond Strengths: The Keys to Catalysis Chem. Rev. 1990, 90, 624-688. (e) Marks, T.J., ed. "Bonding Energetics in Organometallic Compounds" ACS Sympos. Series 1990, 428. 2 Research articles: (a) Stahl, N.G.; Salata, M.R.; Marks, T.J. B(C6F5)3-vs. Al(C6F5)3-Derived Metallocenium Ion Pairs. Structural, Thermochemical, and Structural Dynamic Divergences, J. Am. Chem. Soc. 2005, 127, 10898-10909. (b) Beswick, C.L.; Marks, T.J. Metal-Alkyl Group Effects on the Thermodynamic Stability and Stereochemical Mobility of B(C6F5)3-Derived Zr and Hf Metallocenium Ion-Pairs, J. Amer. Chem. Soc., 2000, 122, 10358-10370. (c) Deck, P.A.; Beswick, C.L.; Marks, T.J. Highly Electrophilic Olefin Polymerization Catalysts. Quantitative Reaction Coordinates for Fluoroarylborane/ Alumoxane Methide Abstraction and Ion Pair Reorganization in Group 4 Metallocene and "Constrained Geometry" Catalysts, J. Am. Chem. Soc., 1998, 120, 1772. (d) Luo, L.; Li, L.; Marks, T.J. Energetics of Metal-Ligand Multiple Bonds. Thermochemistry of Tantalum(V) Alkylidene Formation, J. Am. Chem. Soc. 1997, 119, 8574. (e) Luo, L.; Lanza, G.; Fragalà, I.L.; Stern, C.L.; Marks, T.J. Energetics of Metal-Ligand Multiple Bonds. A Combined Solution Thermochemical and ab Initio Quantum Chemical Study of M=O Bonding in Group 6 Metallocene Oxo Complexes, J. Am. Chem. Soc., 1998, 120, 3111-3122.

30

CH Activations and Related Transformations: Insightful Case Studies Frank Glorius*

Organisch-Chemisches Institut der Westfälische Wilhelms-Universität Münster,

Corrensstraße 40, 48149 Münster, Germany e-mail: [email protected]

Cross-coupling reactions have revolutionized the field of organic synthesis. However, in recent years, the area of CH-activation has received increasing attention.2 Breakthroughs in the field allow a more efficient use of limited natural resources and present versatile additions to the synthetic armory. Since each prefunctionalization has to be paid for, an approach enabling the direct transformation of a C-H bond seems to be more attractive than the traditional cross-coupling approach.

R1 H Y R2 R1 R2+

catalyst(oxidizing agent)

R1 X M R2 R1 R2+catalyst

Traditional cross-coupling approach:

CH activation:

In this interactive training session we will analyze a number of (hopefully) insightful case studies. The prediction of reaction conditions and the design of mechanistic experiments are planned be two important features of this session.

2 a) Godula, K.; Sames, D. Science 2006, 312, 67-72. b) Stuart, D. R.; Fagnou, K. Science

2007, 316, 1172-1175. c) Alberico, D. ; Scott, M. E.; Lautens, M. Chem. Rev. 2007, 107,

174-238. d) Dick, A. R.; Sanford, M. S. Tetrahedron 2006, 62, 2439-2463. e) Zhang, Y.; Li,

C.-J. Eur. J. Org. Chem. 2007, 4654-4657 and references cited therein.

31

C-H Bond Functionalization as Key Step in Total Synthesis Schreiner, Peter R.

Justus-Liebig-University, Institute of Organic Chemistry, Heinrich-Buff-Ring 58, 35392

Giessen, Germany


Usually, an alkane functionalization step is at the very beginning of a total synthesis, and we are in the comfortable situation to order most of the functionalized materials. But what if they aren’t available or if they are simply too expensive? What if in the middle of the synthesis there is a step that require the transformation of an alkyl C–H bond into a functional group? This kind of challenge will be exercised with several hands-on examples, building on the materials presented in the preceding lecture.

32

Poster Abstracts

33

The Mechanism of Racemization of Secondary Alcohols Catalyzed by a Cyclopentadienyl Ruthenium Complex

Åberg Jenny B., Martín-Matute Belén, Edin Michaela, and Bäckvall Jan-E.*

Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University,

SE-106 91, Sweden.


η

5-Ph5Ru(CO)2Cl (1) has been used successfully in the dynamic kinetic resolution of sec-alcohols to produce enantiomerically pure acetates.1 We have studied the mechanism of the racemization catalyzed by 1.2 Our results rule out an outer-sphere mechanism in which the sec-alcohol would not be coordinated to the Ru atom. We propose that the racemization takes place through Ru-alkoxide intermediates.

R R'

O

Ph

Ru

OCOC O

R'R

H

PhPh Ph

Ph

f ast

slow

+

HRu

Ph

PhPh

Ph

OC

Ph

OCRu

OCOC O

R'R

H

RuPh

PhPh

Ph

OC

Ph

OC OAlk

ηηηη3-cyclopentadienyl

Ph

PhPh

Ph

Ph

f ast

Racemization

OH

R R'H

f astX

AlkOH

Alkoxide Exchange

slow

Convincing experiments supporting a racemization mechanism inside the metal coordination sphere will be presented.

1 Martín-Matute, B.; Edin, M.; Bogár, K.; Kaynak, F. B.; Bäckvall, J.-E. J. Am. Chem. Soc.

2005, 127, 8817-8825. 2 Martín-Matute, B.; Åberg, J. B.; Edin, M.; Bäckvall, J.-E. Chem. Eur. J. 2007, 13, 6063-

6072.

Poster 1

34

Dihydroisocoumarines by Gold Catalysis

Benjamin Bechem, A. Stephen K. Hashmi

Organisch Chemisches Institut,

Ruprecht-Karls-University Heidelberg


While in general the gold-catalyzed phenol synthesis is an excellent tool for the synthesis of many different heterocycles, the cycloisomerization of substrates including a propiolic ester failed with the normal catalysts. Now with a specific type of gold-complex this task could be accomplished.

The synthesis of Ajudazol can now be tried with this method. The eastern part was already synthesized by Taylor et al. The western part is well suited for our methodology.

Hashmi, A. S. K.; Frost, T. M., Bats, J. W. J. Am. Chem. Soc. 2000, 122, 11553. Hashmi, A. S. K.; Frost, T. M., Bats, J. W. Organic Letters 2001, 3, 23, 3769. Hashmi, A. S. K.; Wölfle, M; Ata, F.; Hamzic, M; Salathè, R. Adv. Synth. Catal. 2006, 348, 2501-2508.

Krebs, O.; Taylor, R. J. K. Organic Letters 2005, 7, 6, 1063-1066.

Poster 2

35

Nanostructured Iridium Oxide Colloids

F. Berkermann, P. Wedemann, M. T. Reetz Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1,

45470 Mülheim a. d.Ruhr


Nanostructured metal oxides have a great potential in catalysis and are used in many applications such as hydrogenation, fuel cell technology, oxygen and chlorine evolution. Many different preparative methods have been described. Our group has previously developed an easy route to synthesize size-selective, water-soluble colloidal PtO2 by simple hydrolysis/ condensation of the metal salt in the presence of a betaine-stabilizer. It was shown, that the resulting colloid is an excelent hydrogenation catalyst.

[1]

Later, this new “metal oxide concept” could be generalized for the synthesis of other nanostructured metal and multimetal oxides, which can be reduced and immobilized.[2] Aqueous colloidal solutions, containing 1-2 nm sized particles were obtained. All of the present preparation methods have one thing in common. They need a stabilizer to prevent agglomerization. Our group discovered that aqueous IrOx-colloids, synthesized by hydrolysis of an iridium salt in the absence of a stabilizer, are stable for month.[3] Actual TEM-studies show, that the particles have an average diameter of ~1nm. These colloids can be deposited on titanium substrates by heat-treatment at 300-600°C without any Cl2-evolution. Ti-supported IrOx electrodes are highly active as electro-catalysts in waste-water treatment, oxygen and chlorine evolution and are usually prepared by thermal decomposition of the metal chloride at high temperatures.[4] The actual work focuses on the development of the best conditions for the synthesis of “stabilizer-free”-colloids and their deposition on substrates. Furthermore its characterization via TEM, SEM, XPS and electrochemical methods and their application as electrocatalysts are discussed. [1] M. T. Reetz, M. G. Koch, J. Am. Chem. Soc. 1999, 121, 7933-7934. [2] M. T. Reetz, M. Lopez, W. Grünert, W. Vogel, F. Mahlendorf, J. Phys. Chem. B 2003, 107, 7414-7419. [3] M. T. Reetz, H. Schulenburg, WO 2005/095671, October 13, 2005.

[4] A. de Oliveira-Sousa et al., Electrochimica Acta 2000,45, 4467-4473.

Poster 3

36

Enantioselective functionalization of aldehydes using secondary amines

Bertelsen, Søren & Jørgensen, Karl Anker*

[*] Danish National Research Foundation: Center for Catalysis, Department of Chemistry, Aarhus Universitet, Langelandsgade 140, DK-8000 Aarhus C, Denmark.e-mail: [email protected]

Carbonyl compounds are ubiquitously present in nature and therefore constitute important building blocks for organic chemists in life science. The ability to functionalize carbonyl compounds is well known and reactions such as the aldol or the Michael addition are of great importance in chemistry.

The asymmetric versions of carbonyl functionalizations are particularly well-suited for organo-catalysis, which presents a benign and “user-friendly” approach to enantioselective catalysis.

Herein, we will present studies of the α1- and β2-functionalization of aldehydes (Figure 1). Furthermore, a novel catalytic concept leading to formal allylic adducts is presented (γ-functionalization).3

O

R

O

R

Elec

O

R

NucO

R

Elec

*

*

*

α-functionalisation

β-functionalisation

γ-functionalisationchiral catalyst

NH

Rn

Fig. 1 Organocatalytic functionalization of aldehydes. (Elec = electrophile, Nuc = nucleophile)

Mechanistic considerations will be presented to support the experimental results. The usefulness of the obtained products is further demonstrated by the application of β-functionalized adducts in several different one-pot reactions. These highly stereoselective one-pot processes give access to a diverse range of highly substituted carbo- and heterocycles such as cyclohexanones or 1,4-dihydropyridines with up to six new stereocenters.4

1 Bertelsen, S., Halland, N.; Bachmann, S.; Marigo, M.; Braunton, A.; Jørgensen, K. A. Chem. Commun., 2005, 4821. 2 Bertelsen, S.; Dinér, P.; Johansen, R. L.; Jørgensen, K. A. J. Am. Chem. Soc., 2007, 129, 1536. 3 Bertelsen, S.; Marigo, M.; Brandes, S.; Dinér, P.; Jørgensen, K. A. J. Am. Chem. Soc., 2006, 128, 12973. 4 a) Marigo, M.; Bertelsen, S.; Landa, A.; Jørgensen, K. A. J. Am. Chem. Soc., 2006, 128, 5475. b) Cabrera, S.; Aléman, J.; Bolze, P.; Bertelsen, S.; Jørgensen, K. A. Angew. Chem. Int. Ed., 2008, 47, 121. c) Franke, P. T.; Johansen, R. L.; Bertelsen, S.; Jørgensen, K. A. Chem. Asian J., 2008, 3, 216. d) Bertelsen, S.; Johansen, R. L.; Jørgensen, K. A. Unpublished results.

Poster 4

37

Phosphino-Substituted N-Heterocyclic Carbene Ligands (NHCP) and their Transition Metal Complexes Oleg Bondarev,a Peter Hofmann *a,b

aCatalysis Research Laboratory CaRLa, Im Neuenheimer Feld 584,

D-69120 Heidelberg, Germany. bOrganisch-Chemisches Institut, University of Heidelberg, Im Neuenheimer Feld 270,

D-69120, Heidelberg, Germany.


The development of new classes of chiral ligands, which provide high activity and enantioselectivity in a wide range of asymmetric catalytic reactions remains a challenge of high importance. The minimum criteria for novel ligand families include the following: broad reaction and substrate scope; broad variability of both steric and electronic ligand parameters; direct and simple ligand synthesis from inexpensive or readily available starting material in a few steps. Chiral enantiopure NHCP ligands completely satisfy these criteria. They combine the advantages of bulky posphines and strong �-donor NHC ligands in one molecule. In general, the most important advantages of NHCP ligands include their pronounced �-donor abilities, unique steric and electronic properties, simple and robust chelate structures of transition metal complexes as well as their facile synthetic accessibility at low cost. Our phosphinomethyl-substituted carbene ligands can be isolated in pure form. Their cationic palladium and nickel complexes can be used as oligomerization catalysts. Their rhodium complexes were found to promote catalytic hydrogenation with up to 99% ee.

Poster 5

38

Study of Transmetalation Process in the Suzuki-Miyaura Coupling. Leïla Boubekeur-Lecaque, Anny Jutand, Christian Amatore*

Ecole Normale Supérieure, Département de Chimie, 24 rue Lhomond, 75005 Paris, France


Palladium catalyzed reaction of organoboron reagents with halogenated compounds (Suzuki-Miyaura Coupling) proves to be a very powerful approach to build C-C bonds.

R X R'(HO)2B[M]

+

X= Cl, Br, I, OTf

R, R'= Aryle, alkyle, alcynyle, alcènyle

M= Pd, Ni...

R R'

A generally accepted catalytic cycle involving oxidative addition/transmetalation/reductive elimination sequences is depicted bellow. Due to the weak nucleophilicity of the organic group linked to boron atom, the transmetalation to palladium intermediate requires the presence of a base to proceed. The role of the base has been theoretically investigated by means of DFT calculations by Maseras et al.1 The two proposed paths for transmetalation (palladium hydroxo complex or borate adduct) seem reasonable. Our study is intended to investigate experimentally by means of electrochemical and spectroscopic techniques, the kinetic aspects of the transmetalation step. This fruitful approach allowed Jutand and Amatore to study several metal catalyzed reactions bringing to light unexpected intermediates such as anionic palladium (0).2 1 Braga, AAC; Morgon, NH; Ujaque, G, et al., J. Organomat.Chem. 2006, 691, 4459-4466. 2 Amatore, C.; Jutand, A. Accounts Chem. Res. 2000, 33, 314-321.

X= Cl, Br, I, OTf

Pd(0)

PdIIR XPdIIR R'

R XR R'

R' MX M

Addition oxydanteElimination

réductrice

Transmétallation

M=B(OH)2

Poster 6

39

Application of Ultrahigh-field 59Co Solid-State NMR in the First Spectroscopic Investigations of the [Co(C8H13)(C4H6)] 1,2 -

Polybutadiene Catalyst Patrick Crewdson,a David L. Bryce,*b Frank Rominger,c Peter Hofmann *b,c

aCatalysis Research Laboratory, Im Neuenheimer Feld 584, 69120, Heidelberg, Germany. bDepartment of Chemistry and CCRI, University of Ottawa, 10 Marie Curie Private,

Ottawa, ON, K1N 6N5, Canada. cOrganisch-Chemisches Institut, University of Heidelberg, Im Neuenheimer Feld 270,

69120, Heidelberg, Germany.

e-mail: [email protected] e-mail: [email protected]

The syndiotactic 1,2-polybutadiene catalyst [Co(�

3:�2-C8H13)(�4-C4H6)] was

isolated and structurally characterized via X-ray crystallography and solution NMR studies. Furthermore, the utility of ultrahigh-field 59Co solid-state NMR spectroscopy was demonstrated for this class of compounds.

Poster 7

40

Rhenium Catalysed Vinylations with Alkynes Pierre Croizata, Christoph Jäkel*a,b

a Catalysis Research Laboratory, Im Neuenheimer Feld 584, 69120, Heidelberg, Germany b BASF SE, GCB/C – M313, 67056 Ludwigshafen, Germany


The synthesis of vinylesters is of great interest since they are useful building blocks in a large variety of chemical reactions. A straightforward way to obtain these compounds is the transition metal catalyzed vinylation of carboxylic acids with alkynes.1 We show in this work that different rhenium complexes can perform such reactions. In addition, these complexes present high selectivities towards the anti-Markovnikov products.

R OH

Ocat. Re

CH R' O

O

R

R'

O

O

R

R'+

So far, we were not able to obtain simple enolethers from the rhenium catalyzed addition of alcohols on alkynes. For that reason, we investigated a hypothetical mechanism of this addition with the complex [(triphos)Re(CO)2(OTf)] (1).2

1 1 Hua, R.; Tian, X. J. Org. Chem. 2004, 69, 5782-5784, Goossen, L. J.; Paetzold, J.; Koley,

D. Chem Commun. 2003, 706-707 and cited references. 2 Bianchini, C.; Marchi, A.; Marvelli, L.; Peruzzini, M.; Romerosa, A.; Rossi, R.; Vacca, A.

Organometallics 1995, 14, 3203-3215.

Poster 8

41

Iridium–NHC (N-Heterocyclic carbenes) Complexes: Tools and Reactive Species

Olivier Diebolt, Steven P. Nolan Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, 43007

Tarragona, Spain

[email protected]

Complexes of iridium bearing NHC (NHC = N-heterocyclic carbene) ligands were synthesized and fully characterized.

N NR R

general formula of the NHCs

The series [(NHC)Ir(cod)Cl] were obtained by simple cleavage of [Ir(cod)Cl]2. The [(NHC)Ir(COD)Cl] complexes were reacted with excess carbon monoxide, leading to [(NHC)Ir(CO)2Cl]1. The infrared carbonyl stretching frequencies of these were recorded to quantify the electronic parameter of NHC ligands. X-ray diffraction study results allow for determination of NHC steric parameters within this series. These data allow for comparison with other ligand families.

MCl

ClM

2 NHC NHC

ClM2

4 CO NHC

ClM

CO

CO- 2 cod

from (M(COD)Cl)2 to M(Cl)(NHC)(CO)2 (M=Ir, Rh)

2

More recently, we correlated the infrared stretching frequency of the carbonyls of the [(NHC)Ir(CO)2Cl] and of Ni(NHC)(CO)3

2,3,4. Surprisingly, the highly bulky ItBu gave an usual three-coordinated Ni(NHC)(CO)2. The reaction of ItBu with (M(COE)Cl)2 (M=Ir, Rh) leads to unusual systems that are capable of intramolecular C-H bond activation. A simple halide abstraction leads to a 14-electron species bearing an all carbon environment5.

(M(COE)2Cl)2

2 ItBuM

Cl

ClM

N

N

tBu

tBu

N

N

tBu

tBu

-2 COE

-2 COEM

N

NtBu

tBu

H Cl

H2CN

N

CH3

CH3

tBu

MN

N

tBu H2CN

N

CH3

CH3

tBu

- H2

CH2

H3CCH3

Cl

Reaction cascade of ItBu with (M(COE)2Cl)2 1 Burk, M. J.; Crabtree, R. H. Inorg. Chem. 1986, 25, 931-932 2 Kelly III, R. A.; Clavier H.; Nolan S. P. Organometallics 2008, 27, 202–210. 3 Dorta, R.; Scott, N. M.; Nolan, S. P. J. Am. Chem, Soc. 2005, 127, 3516-3526. 4 Tolman, C. A. Chem. Rev. 1977, 77, 313-373. 5 Scott, N. M.; Dorta, R.; Nolan, S. P. J. Am. Chem, Soc. 2005, 127, 2485-2495.

Poster 9

42

Palladium-Catalysed Allylic Alkylation Reactions: A Kinetic Study

Evans, Louise A; Owen-Smith, G J J; Orpen, A G; Fey, N; Harvey, J N; Lloyd-Jones, G C* School of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, UK

*[email protected], www.chm.bris.ac.uk/org/LoydJones

Scheme 1. Allylic alkylation of sodium dimethyl-methyl malonate, catalysed by a Palladium complex. Where L= mono-/ bidentate arylphosphine ligand.

Transition metal-catalysed allylic alkylation, namely with Palladium (See Scheme 1), is a highly versatile, well known reaction, and is known to be a useful and powerful method of carbon-carbon bond formation1,2. The investigations presented herein employ a series of mono- and bidentate (ligated by ferrocene), para-substituted arylphosphine ligands, in combination with Palladium, to gain further insight into the reaction mechanism and kinetics associated with allylic alkylation and to rationalise any trends in observed catalytic activity. It is well established, from inspection of both the equation and catalytic cycle, that attack of the nucleophile on the Palladium-bound η

3-allyl species is the Turnover-Limiting Step (TLS). Consequently, it was anticipated that, where the ligand is electron-withdrawing, allylic alkylation would proceed more efficiently than when electron-donating, due to extent of substrate activation. However, studies into the catalytic rate of the reaction above (See Scheme 1) identified that this was not the case- allylic alkylation proved more operative when the phosphine ligands were electron-donating. Direct investigation into the TLS followed, by competing two complexes (one 13C-labelled) in the stoichiometric allylic alkylation reaction. This reaffirmed the previous hypothesis and led to a revision in the catalytic cycle (See Scheme 2), in which a pre-TLS equilibrium involving catalyst active state interconversion is established. We propose that during catalytic turnover, the majority of the electron-poor catalyst is in its ‘Resting State’, favouring the pre-oxidative addition η

1-coordinated substrate- the opposite being true of the electron-rich species. If the difference in equilibrium population of the two species is large enough, the catalytic reaction will proceed more effectively with an electron-rich catalyst, validating our observations.

Scheme 2. Revised catalytic cycle for Palladium-catalysed allylic alkylation.

1. J. Tsuji, Tetrahedron, 1986, 42, 4361-4401. 2. B. M. Trost, M. L. Crawley, Chem. Rev., 2003, 103, 2921-2943. 3. Jacobsen, E.; Pfaltz, A.; Yamamoto, H.; Comprehensive Asymmetric Catalysis II, Springer, 1999.

Poster 10

43

2-Substituted Pyrrolidines via Ir-Catalyzed Allylic Amination and Domino-Hydroformylation/Reductive Amination

Andreas Farwick, Pierre Dübon, Günter Helmchen*

Organisch-Chemisches Institut der Ruprecht-Karls-Universität Heidelberg,

Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany


The strategy of combining an allylic substitution with a ring closing metathesis (RCM) has been used often to build up 5-membered carbo-1 and heterocycles.2 We present the first examples of the combination of an Ir-catalyzed allylic substitution with a Rh-catalyzed domino-hydroformyl-ation/reductive amination to build up chiral 2-substituted pyrrolidines in a shorter manner. These compounds are of interest because of their biological activitiy and potential as organocatalysts. The new method allows build-up of 2-substituted pyrrolidines in only two steps from easily accessible allylic carbonates. No racemization, which is a major problem for the route combining allylic substitution, RCM and reduction, occurred during the synthesis.

R1 OCO2Me R1

NR2R3

R1

NHR2

R1

NR2

NHR2R3

Ir-cat. allylicamination

If necessary deprotection

Domino-hydro-formylation/reduc-tive amination

R1 = Ph, 3-Py, n-Pr, (CH2)2OTrR2 = Bn, PMB, Me, BocR3 = H, Boc, CHO

1 (a) A. Alexakis, K. Croset, Org. Lett. 2002, 4, 4147-4149; (b) B.M. Trost, C. Jiang, Org. Lett. 2003, 5, 1563-1565; (c) S. Streiff, C. Welter, M. Schelwies, G. Lipowsky, N. Miller, G. Helmchen, Chem. Commun. 2005, 2957-2959. 2 (a) P.A. Evans, J.E. Robinson, Org. Lett. 1999, 1, 1929-1931; (b) P.A. Evans, D.K. Leahy, W.J. Andrews, D. Uraguchi, Angew. Chem. Int. Ed. 2004, 43, 4788-4791; (c) C. Welter, R.M. Moreno, S. Streiff, G. Helmchen, Org. Biomol. Chem. 2005, 3, 3266-3268; (d) V. Böhrsch, S. Blechert, Chem. Commun. 2006, 1968-1970.

Poster 11

44

Dinitrogen Activation and Functionalization by Transition Metal Complexes

Ferreira, M.J., Fryzuk, M.D.*

Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver,

British Columbia, Canada V6T 1Z1


Because N2 is extremely inert, its use as a feedstock to generate higher-value nitrogen containing materials, such as organic amines or N-heterocycles is still considered to be an unsolved problem in inorganic chemistry. Obvious exceptions to this are the Haber-Bosch process, which requires high pressures and temperatures of N2/H2 mixtures over a metal catalyst to produce ammonia, and the nitrogenase enzyme that also generates NH3 through a process not yet fully understood.

Considerable effort has been undertaken in the past few years by several groups to solve this long-standing problem. In particular, the work developed in the Fryzuk group has demonstrated that early transition metal complexes in high oxidation states supported by multidentate ligands containing nitrogen and phosphorus donors can promote the activation of N2 under a variety of conditions. Subsequent functionalization has resulted in the formation of new N-H, N-Si, N-B, N-Al and N-C bonds. This presentation will provide a summary of recent efforts to solve this difficult problem.

Poster 12

45

Screening of Chiral Organocatalysts by ESI-MS Fleischer Ivana, Pfaltz Andreas*

Department of Chemistry, University of Basel, St. Johanns-Ring 19,

CH-4056 Basel, Switzerland


Electrospray ionisation mass spectrometry (ESI-MS) has become a powerful tool for screening and studying mechanisms of many reactions. In our group, ESI-MS was applied to monitor positively charged intermediates in a palladium-catalyzed allylic substitution.1 Using quasienantiomeric mass-labelled substrates, a rapid screening protocol for chiral catalysts was developed. Here we report a successful application of this method in the organocatalytic Michael addition of malonates to unsaturated aldehydes.2 Based on the principle of microscopic reversibility, it is possible to determine the enantioselectivity of organocatalytic Michael addition by screening the intermediates of the retro-Michael addition. Several catalysts with excellent selectivity have been identified and applied in the preparative reaction. This procedure was extended to multi-catalyst screening. Up to 6 catalysts have been synthesised in one pot and the crude mixture was subjected to the mass spectrometric screening. The intermediates of every catalyst could be easily assigned and the enantioselectivity determined. This methodology represents an elegant approach to catalyst libraries. It allows to find a selective catalyst without time-consuming separation and analysis. 1 C. Markert, A. Pfaltz, Angew. Chem. Int. Ed. 2004, 43, 2497-2500. 2 S. Brandau, A. Landa, J. Franzèn, M. Marigo, K.A. Jørgensen, Angew. Chem. Int. Ed.

2006, 45, 4305-4309.

Poster 13

46

Catalytic Homogeneous Dehydrogenation of Limonene Horrillo-Martínez Patricia,a Jäkel Christoph*a,b

a Catalysis Research Laboratory, Im Neuenheimer Feld 584, 69120, Heidelberg, Germany

b BASF SE, GCB/C – M313, 67056 Ludwigshafen, Germany


Limonene is a terpene obtained from orange or lemon waste, and has a broad field of use already, most notably for its pleasant lemon odour. Dehydrogenation to the corresponding 1-methyl-4-(prop-1-en-2-yl)benzene (p-methyl-α-methylstyrene or DMS) holds great promises as a replacement of styrene for new polymer syntheses. Dehydrogenation reactions are commonly performed by using heterogeneous, transition metal containing catalysts at elevated temperature.1

In this poster we present a procedure based on homogeneous dissolved Pd-salts in the presence of Cu(II) salts as oxidants.2 This transformation shows good selectivities for DMS, avoiding greatly the formation of p-cymene as byproduct. Preliminary mechanistic studies give first insights in course for this transformation.

1 (a) Weyrich, P. A.; Hölderich, W. F. Applied Catalysis A: General 1997, 158, 145-162. (b)

Brau, R. J.; Zgolicz, P. D.; Gutierrez, C.; Taher, H. A. Journal of Molecular Catalysis A:

Chemical 1999, 148, 203-214. (c) Kageyama, Y.; Masuyama, T.; Yokoyama, T. Jpn. Kokai

Tokkyo Koho, JP 54163530, 1979. (d) Wideman, L. G., U.S. Pat. Appl. Publ. US 4375572,

1983.

2 (a) Trost, B. M.; Metzner, P. J. J. Am. Chem. Soc. 1980, 102, 3572-3577. (b) Jira, R. In

Applied Homogeneous Catalysis with Organometallic Compounds, Vol. 1; Cornils, B.,

Herrmann, W. A., Eds.; Wiley-VCH: Weinheim, Germany, 2002; p 386-405.

Poster 14

47

Gold Catalysis Applied to the Total Synthesis of Orientalols Jiménez-Núñez Eloísa,a Echavarren Antonio M.*a

aInstitute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, 43007

Tarragona, Spain.


Gold-catalyzed cycloisomerizations of 1,6-enynes have been extensively studied in our group.1 In these reactions, the delocalized electrophilic character of intermediate cyclopropyl-gold carbeneFehler! Textmarke nicht

definiert. ,2 makes it a versatile species for further cascade reactions. We developed a tandem polycyclization of carbonyl-functionalized 1,6-enynes.3 Here we present the application of that methodology to the total synthesis of natural products. Three guaiane sesquiterpenoids4,5 have been synthesized in a sequence that involves a gold-catalyzed polycyclization as the key step.

1 Nieto-Oberhuber, C.; López, S.; Jiménez-Núñez, E.; Echavarren, A. M. Chem. Eur. J.

2006, 12, 5916-5923. 2 Fürstner, A.; Davies, P. W. Angew. Chem. Int. Ed. 2007, 46, 3410-3449. 3 Jiménez-Núñez, E.; Claverie, C. K.; Nieto-Oberhuber, C.; Echavarren, A. M. Angew.

Chem. Int. Ed. 2006, 45, 5452-5455. 4 Peng, G.-P.; Tian, G.; Huang, X.-F.; Lou, F.-C. Phytochemistry 2003, 63, 877-881. 5 Huang, S.-X.; Yang, J.; Xiao, W. –L.; Zhu, Y.-L.; Li, R.-T.; Li, L.-M.; Pu, J.-X.; Li, X.;

Li, S.-H.; Sun, H.-D. Helvetica Chim. Acta 2006, 89, 1169-1175.

Poster 15

48

Organometallic Low Molecular Mass Gelators T. Klawonna), T. Tua), I. Winklera), A. Gansäuera), K. H. Dötza), W.

Assenmacherb), H. Peterlikc), H. Börnerd), M. C. Feiterse), R. J. M. Noltee)

a) Kekulé-Institut für Org. Chemie und Biochemie, b) Institut für Anorg. Chemie

Universität Bonn, c) University of Vienna, d) MPI Potsdam-Golm, e) Radboud University

Nijmegen, NL


The assembly of low molecular mass compounds to nanostructures and gels has aroused increasing interest due to their physical properties and potential applications.1 The incorporation of a covalent metal to carbon bond2,3,4 into the gelator allows for metal-assisted or -catalyzed reactions in the gel state4 We designed and developed sugar aminocarbene2, titanocene3 and palladium4 complex gelators and models for their aggregation. Furthermore, first applications to catalysis will be presented.2-4

1 For recent reviews, see: a) Tetrahedron 2007, 63; b) Top. Curr. Chem. 2005, 256. 2 a) G. Bühler, M. C. Feiters, R. J. M. Nolte, K. H. Dötz, Angew. Chem. Int. Ed. 2003, 42,

2494; b) T. Klawonn, M. C. Feiters, R. J. M. Nolte, K. H. Dötz, unpublished results. 3 T. Klawonn, A. Gansäuer, I. Winkler, T. Lauterbach, D. Franke, R. J. M. Nolte,

M. C. Feiters, H. Börner, J. Hentschel, K. H. Dötz, Chem. Commun. 2007, 1894. 4 T. Tu, W. Assenmacher, H. Peterlik, R. Weissbarth, M. Nieger, K. H. Dötz, Angew.

Chem. Int. Ed. 2007, 46, 6368.

HOH2C NH

OH

OH OH

OH

C8H17

Cr(CO)5

TiCl

Cl

O

Cholesterol

NNPd

N

N NIC16H33 C16H33

ONC COOEt+

NC CO2Et

O O

i-Pr2NEt, DCM, r.t.

I

Gel in DMSO

Poster 16

49

Transformation and valorization of natural products by ene-yne metathesis

Virginie Le Ravaleca, Christian Bruneau*a

aSciences chimiques de Rennes, Catalyse et Organométalliques UMR 6226 CNRS-

Université de Rennes 1 Campus Beaulieu, Bâtiment 10C –CS 7420

35042 Rennes Cedex

e. mail : [email protected]

The production of raw materials from renewable resources is a topic of current interest as petroleum chemical substitutes, energy savings and for its contribution to sustainable development. Within this trend the use of renewable unsaturated vegetable oils is attractive.1 The selective cleavage by cross metathesis of unsaturated fatty esters, arising from transesterification of vegetable oils, catalyzed by ruthenium-alkylidene complexes, constitutes a potentially useful transformation. Among metathesis transformations, the ene-yne cross metathesis,2 not much studied yet, allows the formation of a conjugated diene that can be further transformed into added value chemicals.

R1 R3R2+Catalyseur

R2 R3

R1

+R2 R3

R1

Diels Alder reactions will be considered in order to transform these new dienes into precursors of functionalized aromatic compounds.

1 a) Biermann, U.; Friedt, W.; Lang, S. ; Luhs, W.; Machmüller, G. ; Metzger, J.O.; Rüsh

gen. Klaas, M.; Schäfer, H.J.; Schneider, M.P. Angew. Chem. Int. Ed. 2000, 39, 2206. b) Hill, K. Pure Appl. Chem. 2000, 7, 1255. c) Corma, A.; Iborra, S.; Velty, A. Chem. Rev. 2007, 6, 2503. 1 Diver, S.T.; Giessert, A.J. Chem. Rev. 2004, 104, 1317.

Poster 17

50

N-N Bond Scission in Zirconium Hydrazide Promoted by Isocyanides and Chalcogen Atom Transfer Agents: Masked Metallonitrenes {M�N}

Heike Herrmann, Julio Lloret, Hubert Wadepohl, and Lutz H. Gade* Anorganisch-Chemisches Institut der Universität Heidelberg

Im Neuenheimer Feld 270, 69120 Heidelberg (Germany)


Interest in transition-metal hydrazides has been primarily due as intermediate species in the stoichiometric and catalytic reduction of dinitrogen to ammonia and hydrazinations of alkynes.1 Therefore, [Zr(N2

TBSNpy)(NNPh2)(Py)] (1) hydrazidozirconium complex is presented as an attractive compound for a potential N-N bond cleavage study.

NZrNN

N

NPh2

R

R

N

NZrNN

N

R

R

NPh2

EN Zr

NN

N

R

R

NPh2

NZrNN

N

R

R

NPh2

C NtBuE = S, SeCNtBu

-Py-Py

12 3: E = S4: E = Se

R = tBuMe2

Reaction of 1 with isocyanides and chalcogen atom transfer agents leads to the formation of compound [Zr(N2

TBSNpy)(NPh2)(NCNtBu)] (2) and [{Zr(N 2

TBSNpy)(NPh2)}2(�-N2E)] (E=S: 3, Se: 4) in high yields where the N-N bond has been cleaved. Preliminary DFT studies suggest that the naked metallonitrene {M�N} is not available while a change in hapticity at the hydrazo motif from η1 to η2 is thermally reliable.2 With the aim to clarify some open questions, we begin with the analysis of the bonding and bending on hydrazidozirconium complex 1. 1 (a) Schrock, R.R. Acc.Chem.Res. 2005, 38, 955. (b) Johnson, J.S.; Bergmann, R.G.. J.Am.Chem.Soc. 2001, 123, 2923. 2 Herrmann, H.; Lloret, J.; Wadepohl, H.; Gade, L.H. Angew.Chem.Int.Ed. 2007, 46, 8426.

Poster 18

51

The Synthesis of Organoboron Compounds by C-H Activation of Alkanes and Arenes

Jaclyn M. Murphya, John F. Hartwig*b

aYale University, Department of Chemistry bUniversity of Illinois, Urbana-Champaign, Department of Chemistry


Alkanes, although one of the most abundant chemical feedstocks, are relatively unreactive. A process that could directly and selectively convert alkanes into terminally functionalized compounds would be of great synthetic value. A series of ruthenium complexes has been found that

selectively borylates alkanes terminally, yielding α-alkylboronic esters in excellent yields.1 It has been shown that these complexes will also borylate the least sterically hindered terminal methyl group both in branched alkanes and in substrates that contain heteroatoms, including ethers, fluoroalkanes, and amines.

Arene functionalization through C-H activation is more developed compared to the alkane borylation chemistry. Development of a mild, efficient, and regioselective iridium-catalyzed arene borylation system has allowed access to 3,5-disubstituted arylboronic esters in excellent yields starting from the corresponding arene. Methodologies to convert arenes to either arylboronic acids, potassium aryl trifluoroborates, aryl bromides, or aryl chlorides using a one-pot synthesis have been developed and the scope of these transformations has been investigated.2,3 1. Murphy, J.M.; Lawrence, J.D.; Kawamura, K.; Incarvito, C.; Hartwig, J.F. J.

Am. Chem. Soc. 2006, 128, 13684-13685.

2. Murphy, J.M.; Tzschucke, C.C.; Hartwig, J.F. Org. Lett. 2007, 9, 757-760.

3. Murphy, J.M.; Liao, X.; Hartwig, J.F. J. Am. Chem. Soc. 2007, 129, 15434-

15435.

Poster 19

Synthesis and characterization of ηηηη3-allyl-nickel(II) complexes containing sulphur ligands: Evaluation as catalysts for 1,3-butadiene

polymerization

Padavattan Govindaswamya, Bélen Diaza, Christoph Jäkela, b*

aCatalysis Research Laboratory, Im Neuenheimer Feld 584, 69120 Heidelberg, Germany. bBASF SE, GCB/C-M313, 67056 Ludwigshafen, Germany.


The reaction of dimeric allyl-nickel(II) chloro complexes [(η3-C3H5)Ni(µ-Cl)]2 with sulphur donor ligands (L = L1-L4) gives the corresponding mononuclear complexes [(η3-C3H5)Ni(L)2]

+ (L1 = diphenylsulphide (1), L2 = 4,4’-thiodiphenol (2), L3 = 4,4’-thio-bis(6-tert-butyl-O-cresol) (3), L4 = 3-tert-butyl-2-hydroxy-5-methylphenyl sulfide (4).

Complex 3

The catalytic potential of these complexes for 1,3-butadiene polymerization reactions has been studied.

Poster 20

Poly(p-phenylene vinylene) Nanoparticles by Acyclic Diene Metathesis (ADMET) Polycondensation in Aqueous Emulsion

Johannes Pecher, Stefan Mecking*

Chair of Chemical Materials Science, Department of Chemistry, University of Konstanz,

Germany


Conjugated polymers, such as poly(p-phenylene vinylene) (PPV) and its derivatives are key components for the development of, e.g., flexible and low-cost displays and organic light emitting diodes (OLEDs).1 Aqueous dispersions of conjugated polymer nanoparticles may contribute to resolve the notorious issue of processing this class of polymers. Step-growth metathesis polymerization of alkoxy substituted and alkyl substituted divinylbenzenes in aqueous emulsion to afford PPV nanoparticles has been studied.2 Despite the sensitivity of the catalytically active ruthenium methylidene towards water,3 both catalyst precursors, [(PCy3)(�-C-C3H4N2Mes2)Cl2Ru=CHPh] (“Grubbs second generation”) and [(�-C-C3H4N2Mes2){k

2-=CH-o-(iPrO)C6H4}RuCl2] (“Hoveyda-Grubbs second generation”), are capable of performing ADMET in aqueous media. Specific aspects of the polymerization mechanism relative to the step-growth nature of this reaction will be discussed. Bright colored dispersions of fluorescent nanoparticles ranging from 100 to 300 nm were obtained. Lateral structures were obtained by simple ink-jet printing of the particle dispersion. 1 Müllen, K.; Scherf, U. Organic light emitting devices; Wiley-VCH: Weinheim, 2006. 2 Pecher, J.; Mecking, S. Macromolecules 2007, 40, 7733-7735. 3 Schwendeman, J. E.; Church, A. C.; Wagener, K. B. Adv. Synth. Catal. 2002, 344, 597-

613.

Poster 21

54

NOVEL CHELATING DIPHOSPHOROUS LIGANDS FOR RHODIUM-CATALYSED LOW PRESSURE

HYDROFORMYLATION Tobias Rosendahla,b, Sebastian Brauna, Rolf Tompers#a, Peter Deglmann#a,

Frank Romingera, Peter Hofmann*a,b

aOrganisch-Chemisches Institut der Universität Heidelberg bCatalysis Research Laboratory (CaRLa), Heidelberg

e-mail: [email protected] Rhodium-catalysed olefin hydroformylation represents one of the largest volume industrial processes employing homogeneous catalysis. We have developed a highly modular synthesis of new phosphine-, phosphonite- and phosphite chelate ligands (TTP and congeners), starting from easily accessible 1,8-disubstituted anthraquinones[1]. The rhodium-catalysed low pressure hydroformylation of 1-octene reveals that the new lead structure provides highly active (TOF > 10000) and highly selective (aldehyde and n-selectivity > 99%) catalysts. Until now, no consistent understanding of how activity and selectivity in hydroformylation are controlled by steric and/or electronic effects of the ligands has emerged. Therefore three analogs of one of our ligands, electronically modified by appropriate substitution, have been synthesised and their performance in low-pressure hydroformylation has been tested. In order to investigate the validity of the Wilkinson mechanism[2] for our systems, dicarbonyl hydride resting states have been identified, isolated and characterized by X-ray diffraction. A model compound for elusive alkyl monocarbonyl intermediates has been synthesised and its reactivity towards CO and H2 has been studied by in situ IR- and NMR. The reversibility of the CO insertion step has been studied by deuteroformylation experiments. [1] W. Ahlers, M. Röper, P. Hofmann, D.C.M. Warth, R. Paciello, WO 2001058589 A1 200110816, BASF. [2] D. Evans, J. A. Osborn, G. Wilkinson, J. Chem. Soc. A, 1968, 3133-3142. # New address: BASF SE, D-67056 Ludwigshafen, Germany

Poster 22

55

Highly efficient ruthenium-catalyzed ringclosing metathesis for the formation of tetrasubstituted olefins

Daniel Rost, Siegfried Blechert*

*Technische Universität Berlin, Institut für Chemie

Strasse des 17. Juni 135, 10623 Berlin, Germany


Ruthenium-catalyzed olefin metathesis reactions have emerged as an attractive and powerful tool for the formation of new carbon-carbon double bonds.1 Among the different types of the metathesis reactions, ringclosing metathesis (RCM) allows the elaboration of functionalized cyclic olefins which are very common synthetic intermediates in organic synthesis. In particular, RCM to form tetrasubstituted olefins is one of the most challenging transformation.

[Ru] Xn

Xn

Figure 1. Ring closing metathesis (RCM) to form tetrasubstituted olefins.

Our interest has been focused in the development of new efficient and easily prepared ruthenium-based catalysts, as this metathesis reaction typically required high catalyst loadings and any conversion to electron-deficient tetrasubstituted olefins has not been satisfactory achieved.2 Herein we present a new ruthenium complex with increased efficiency for the construction of different ring sizes and report the significantly influence of the reaction conditions. 1 (a) Nicolaou, K. C.; Bulger, P. G.; Sarlah, D. Angew. Chem. 2005, 117, 4564-4601; Angew. Chem. Int. Ed.. 2005, 44, 4490-4527. (b) Astruc, D. New J. Chem. 2005, 29, 42. 2 (a) Stewart, I. C.; Ung, T.; Pletnev, A. A.; Berlin, J. M.; Grubbs, R. H.; Schrodi, Y. Org. Lett. 2007, 9, 1589-1592. (b) Ritter, T.; Heijl, A.; Wenzel, A. G.; Funk, T. W.; Grubbs, R. H. Organometallics 2006, 25, 5740-5745.

Poster 23

56

Exploiting the chemistry of Rh-monohydrides: Extending the Scope of Asymmetric Hydrogenations

Caroline Scheuermann,a Christoph Jäkel*a,b

aCatalysis Research Laboratory, Im Neuenheimer Feld 584, 69120, Heidelberg, Germany bBASF SE, GCB/C – M313, 67056 Ludwigshafen, Germany


R

R1

O

R

R1

O1 mol % cat

Homogeneous asymmetric hydrogenation accounts for over half of the man made chiral compounds that are not produced by enzymatic or physical resolution.1,2 We present results for the highly selective hydrogenation of α,β-unsaturated carbonyl compounds using a monohydride catalyst, Rh(CO)2H(R,R)-Chiraphos, with up to 90 % e.e. and 100 % conversion. 1. Thayer, A. M., Chem. Eng. News, 2005, 61, 6169. 2. The Handbook of Homogenoeus Hydrogenation. Eds de Vries, C. J., Elsevier, 2007, Wiley, Weinheim.

H2

Poster 24

57

Pincer Dicarbene Complexes of Platinum(II) Daniel Serraa, Christoph Jäkel *a,b

aCatalysis Research Laboratory, Im Neuenheimer Feld 584, 69120, Heidelberg, Germany bBASF SE, GCB/C – M313, 67056 Ludwigshafen, Germany


NN N

N N

R R

Pt

Y

Y

A series of new pincer 2,6-pyridyl dicarbene complexes of type [(CNC)PtY]+, where carbene is 3-alkylimidazol-2-ylidene (1: alkyl = methyl, 2: alkyl = n-butyl) or 3-arylimidazole-2-ylidene (3: aryl = mesityl), Y = Cl or Br, have been prepared by transmetallation with platinum, from the corresponding silver complexes generated in situ. The crystal structure of complex 1 shows that the ligands are acting as chelates exhibiting a twisted C2 symmetry as observed for the isostructural Pd complexes reported.1 When the bromide or chloride complexes are treated with two equivalents of silver triflate, dicationic pincer platinum complexes can be generated and isolated as their acetonitrile adducts. 1 a) Nielsen, D. J.; Cavell, K.J.; Skelton, B.W.; White, A. H. Inorg. Chim. Acta, 2002, 327,

116-125. b) Miecznikowsky, J. R.; Gründemann, S.; Albrecht, M.; Mégret, C.; Clot, E.;

Faller, J. W.; Eisenstein, O.; Crabtree, R. H. J. Chem. Soc., Dalton Trans. 2003, 831-838. c)

Danopoulos, A. A.; Tulloch, A. A. D.; Winston, S; Eastham, G.; Hursthouse, M. B. J.

Chem. Soc., Dalton Trans. 2003, 1009-1015.

Poster 25

58

Oxidative Transition Metal Catalysed Diamination Reactions Streuff Jana, Muñiz Kilian*a

aInstitut de Chimie, Université Louis Pasteur, 4 rue Blaise Pascal, 67000 Strasbourg, France


We recently reported the first catalysed diamination of unfunctionalised alkenes followed by a detailed mechanistic study.1 This intramolecular approach works catalytic in palladium(II) and cyclises N-tosylated ureas in excellent yields using iodosobenzene diacetate or copper bromide2 as oxidants. The palladium acetate/iodosobenzene diacetate pairing also allows construction of bisindolines and related heterocycles within a catalytic diamination reaction.3 A complimentary method for a diamination with sulfamides was developed leading to products, which allow for facile selective deprotection.4 The reaction asks for a nickel(II) salt as catalyst and represents one of the rare examples of oxidation catalysis with nickel.

NH

XNHR

Pd(OAc)2 (5 mol%)PhI(OAc)2 (2.0 eq.)

baseCH2Cl2, r.t.

N NTos

O

X= C(O), R= Tos

NiCl2 (10 mol%)PhI(OAc)2 (2.0 eq.)

baseDMF, 40°C

X= SO2, R= Cbz

N NCbz

O2S NH NH2

ureas sulfamides free diamines 1 a) Streuff, J.; Hövelmann, C. H.; Nieger, M.; Muñiz, K. J. Am. Chem. Soc. 2005, 127,

14586; b) Muñiz, K.; Hövelmann, C. H.; Streuff, J. J. Am. Chem. Soc. 2008, 130, 763. 2 Muñiz, K.; Hövelmann, C. H.; Campos-Gómez, E.; Barluenga, J.; González, J. M.; Streuff,

J.; Nieger, M. Chem. Asian J. 2008, in press. 3 Muñiz, K.; J. Am. Chem. Soc. 2007, 129, 14542. 4 Muñiz, K.; Streuff, J.; Hövelmann, C. H.; Núñez, A. Angew. Chem. 2007, 119, 7255.

Poster 26

59

Side-Arm Approach to Catalysts in Asymmetrical Catalysis and Olefin Polymerization

Xiu-Li Sun, Yong Tang

The State Key Laboratory of Organomettalic Chemistry, Shanghai Institute of Organic

Chemistry, 354 Fenglin Lu, Shanghai 200032, China


We were interested in developing catalysts that are readily acessible, stable, and efficient. By sidearm approach, the salicylaldiminato titanium complexes [O-NX]TiCl 3 (X=N, O, P, S, Se) and pseudo C3-symmetric trisoxazoline (TOX) were synthesized. Strong side-arm effects were observed. It was found that [O-NX]TiCl 3 (X= P, S, Se) and the in-situ formed metal complexes from TOX were excellent catalyst in asymmetric catalysis and olefin polymerization, respectively.1

O

NSA

R

R

TiCl3

O

N N

OSA

Asymmetric catalysis

olefin polymerization

N

R3R1

O R2

Chem. Commun. 2003, 2554.J. Org. Chem. 2006, 71, 3576.

Org. Lett. 2004, 10, 1667.Angew. Chem. Int. Ed., 2007, 46, 3918.

NH

CH(COOR')2

J. Am. Chem. Soc. 2002, 124, 9030.Chem. Commun. 2003, 2554.J. Org. Chem. 2004, 69, 1309.

n

PE

LLD

PE

m n∗

1-olefin = C6-C18

CO

C m

aterials

m

n

functional PE

m n∗

R

Rp

R = OH, CO2Me, CO2H

On+5

OBr

m

OMeO

PE-b-PMMA

Organometallics 2004, 23, 1684. Organometallics 2006, 25, 3259.Macro. Rapid Commun. 2007, 28, 1511.and unpublished results

NOMe

R3

R1

R2O2C CO2R2cycloaddition

n

(n = 0,1)

R'CO2R

Ph

Chem. Commun. 2007, 1960.

Kin

u ga s

a re

a ctio

n O

S

R

CO2R'CO2R'

Ste

ven

Rea

rran

gem

ent

F-C reaction

unpublished results

1 We are grateful for the financial support from the National Natural Sciences Foundation of China.

Poster 27

60

O

OY Y Y Y

R4

X X R1

R4

R6

R2

R3R5

R7

X = PR2, OPR2, P(OR)2, OP(OR)2R1 ... R8 = substituents

Y = Cl, OBn = bridging group

R8R5,6,7 R1,2,3 R5,6,7 R1,2,3

Nickel-Catalyzed Hydrocyanation and Pentene Nitrile Isomerization Michael E. Taucherta, Peter Hofmann*a

aOrganisch-Chemisches Institut, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany


We recently developed a new class of modular, easily accessible phosphorus based chelating ligands. These ligands can be prepared in three to six steps with broad structural diversity.[1]

The most prominent industrial application of homogeneous hydrocyanation is the so-called adiponitrile process, in which butadiene is converted into adiponitrile - an important building block for nylon production - in a three step process.[2]

Our new ligand systems, using in particular bisphosphine and bisphosphonite derivatives, was successfully applied in the isomerization of 2M3BN into t3PN, and in the hydrocyanation of styrene. [1] W. Ahlers, M. Röper, P. Hofmann, D. C. M. Warth, R. Paciello, WO 01/58589 A1 (16.08.2001, BASF); W. Ahlers, R. Paciello, D. Vogt, P. Hofmann, WO 02/083695 A1 (24.10.2002, BASF). [2] B. Cornils, W. A. Herrmann, (Eds.) Applied Homogeneous Catalysis with Organometallic Compounds, VCH, Weinheim, 1996.

2M3BNCN

HCN, [Ni] HCN, [Ni](LA)

[Ni]CN

t3PNCN

NC

Poster 28

61

A Novel Synthetic Approach towards Chiral QUINAP via Diastereomeric Sulfoxide Intermediates

Thaler Tobiasa, Geittner Floriana Knochel Paul*a

a Department Chemie und Biochemie, Ludwig-Maximilians-Universität München,

Butenandtstr. 5-13, Haus F, 81377 München, Germany.


Since its discovery by J. M. Brown et al.1 QUINAP has become one of the most outstanding chiral P,N-ligands for enantioselective catalysis. However, the current preparation of chiral QUINAP and its derivatives is costly and difficult, as it is based on chiral resolution via diastereomeric cyclopalladated complexes formed with stoichiometric amounts of PdCl2 and (R)-(+)-dimethyl[1-(1-naphthyl)ethyl]amine.2 This approach avoids the use of stoichiometric Pd salts for chiral resolution, which herein is achieved by the preparation and simple chromatographic separation of chiral sulfoxide intermediates. Subsequent sulfoxide-lithium exchange, quenching with Ph2PCl and sulfur followed by desulfurisation with Raney-Ni provides (R)- and (S)-QUINAP with 54-56% overall yield.3 1 Alcock, N. W.; Brown, J. M.; Hulmes, D. I. Tetrahedron: Asymmetry 1993, 4, 743 2 Lim, C. W.; Tissot, O.; Mattison, A.; Hooper, M. W.; Brown, J. M.; Cowley, A. R.;

Hulmes, D. I.; Blacker, A. J. Org. Proc. Res. & Dev. 2003, 7, 379. 3 Thaler, T.; Geittner, F.; Knochel P., Synlett 2007, 17, 2655.

Poster 29

62

Binuclear Gold(I) Complexes Containing Bulky Electron-Rich Phosphine Ligands: Synthesis, Structural Feature and Catalytic

Reactions

Zhirong Zhao-Kargera and A. Stephen K. Hashmi*a,b

a Catalysis Research Laboratory, Im Neuenheimer Feld 584, 69120 Heidelberg, Germany

b Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer

Feld 270, 69120 Heidelberg, Germany


The use of gold in homogeneous catalysis is expanding rapidly and has emerged as important synthetic method.1 Mononuclear (phosphane)gold(I) halides are often utilized as active catalysts in many cases. The application of binuclear gold(I) complexes as catalysts has not been broadly exploited although the influence of the structure on properties of dimeric gold(I) complexes and its implications in photochemistry, crystal engineering or medicine studies have been highlighted by many groups.2 It might be interesting to study whether the very pronounced “aurophilicity” of the coordination chemistry of binuclear gold compounds can be translated into the creative design of catalysts and open up new perspectives of gold catalysis. The presented work reported synthesis, structure and some initial catalytic investigations of new binuclear gold(I) complexes with bulky electron-rich diphosphine ligands as bis(di-tertbutylphosphino)methane and bis(di-tertbutylphenylphosphino)methane.

1. For a most recent review: Hashmi, A. S. K., Chem. Rev. 2007, 107, 3180 – 3211.

2. a) Pyykko, P., Chem. Rev. 1997, 97, 597 and references therein; b) Lagunas, M. C.,

Fierro, C. M., Pintado-Alba, A. H. de la Riva , Betanzos-Lara, S., Gold Bulletin

2007, 40, 135 – 141.

Poster 30

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