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Nonlinear effects and related phenomena
We predicted (ref. 212) the possibility that going from an enantiopure catalyst to an enantioimpure catalyst could be associated to an increase of enantioselectivity. We are looking for such systems.
Nonlinear effects are now widely used in asymmetric catalysis as a mechanistic tool. We published in 1998 a large review article covering the first ten years of investigation on NLE (ref. 23 in " Reviews and Books "). In 2009 we published the progresses on NLE in the 1998-2009 period (ref. 278).
Asymmetric C-C bond formation under PTC conditions
This topic is a joint work with the groups of Prof. Y. Belokon (Moscow) and Prof. A. Saghyan (Erevan).
The main reactions studied are the C-alkylation of the Schiff bases of some a-aminoacids in toluene in presence of KOH and an asymmetric phase-transfer catalyst. It will be extended to the synthesis of various unnatural a –aminoacids..
Tandem enantioselective reactions and nonlinear effects
The achiral substrates with two prochiral centers can be transformed into a chiral product by full transformation of the substrate in presence of achiral catalyst. Sometimes the product can be prepared with a high diastereoselectivity and a high enantiomeric excess (see our previous papers in that area : refs 198, 211, 263). We will study some bifonctionnal susbtrates with enantioimpure catalysts known to give rise to nonlinear effects on monofonctional substrates.
Regioselectivity control on chiral substrate
The possibility to use at will a given enantiomer of a chiral catalyst to achieve a regioselective reaction has been discussed in a review article (ref. 279). We are engaged on the regioselective monofunctionalization of diols in steroid or sugar families. Other types of transformations (epoxide opening, CH carbene insertion etc) are also under investigation.
