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Platinum Metals Rev., 1990, 34, (2), 72

Organopalladium Chemistry Project Sponsored by European Commission

In its latest round of funding under the Science Plan, the European Commission has agreed to support a programme of research in four university laboratories covering diverse aspects of the chemistry of palladium complexes applied to organic synthesis. At Strasbourg, the group led by Dr.Michel Pfeffer is engaged in studying the preparation of novel types of cyclic compound, including a range of nitrogen heterocycles of different ring size, through reactions which involve intramolecular C-H activation of functional aromatic compounds. These processes are combined with alkyne insertion to provide a battery of fused ring systems, as shown in Figure 1. Dr. Alain Dedieu is also at Strasbourg and works on the theoretical basis for organometallic catalytic reactions. Previous studies have been concerned with the classic catalytic reactions such as hydrogenation and hydroformylation, but within the framework of the present grant he will attempt to illuminate the course of relevant C-C bond forming reactions. Specific aspects of organopalladium catalysis, particularly cross-coupling and other related reactions which hold promise in asymmetric synthesis, will be the concern of Dr. John M. Brown at Oxford. The collaboration will involve regular meetings of the participants, as well as the exchange of research workers among the various laboratories.

Fig. 1

The fused nitrogen heterocyclic systems illustrated can be produced by organopalladium complex catalysis from C-H activation of aromatic compounds combined with alkyne insertion

The project is co-ordinated by Professor Gerard van Koten of Utrecht. His interests, like those of Pfeffer, are in cyclopalladated compounds but using the directed metallation procedures to provide functionalisation of aromatic compounds. This is of particular interest for oxidation chemistry and could lead to simple routes from arenes to the corresponding phenols.

Thus, all the participants have a common ground in organopalladium chemistry but plan to develop their research in diverse ways. A further basis for collaboration is provided by the sharing of equipment and expertise among the centres. The Utrecht group, for example, has long-standing experience in X-ray crystallographic characterisation of reactive organometallic compounds, see Figure 2. In catalytic cross-coupling reactions, the structure of the nucleophilic component may play a crucial part in determining the reaction selectivity. X-ray characterisation will underpin the work in the other laboratories. Similarly, the Oxford group has a lot of experience in applying NMR techniques to the mechanistic analysis of homogeneous catalysis.

Fig. 2

A typical X-ray cryBtallographic characterisation of an organopalladium complex formed by C-H activation and orthometallation

European Commission projects of this type serve a further useful purpose. They encourage a high level of exchange between the different laboratories both for the academic supervisors and for their students and associates. It is specified in the grant conditions that coworkers, supported by the project, must be members of one European Commission country but working in another. This stipulation serves a dual purpose. Not only will it help to bring about the broadening of the European research base in chemistry, but it will also lead to the training of students and postdoctorals who will be well-equipped to live and work in post-1992 Europe.

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