HIGHLY DIASTEREOSELECTIVE COUPLING REACTIONS BETWEEN CHIRAL BENZALDEHYDE TRICARBONYLCHROMIUM COMPLEXES AND ACTIVATED DOUBLE-BONDS

The amine catalyzed coupling reaction of acrylic derivatives with benzaldehydes (Baylis-Hillman reaction) is more efficient when the arene is complexed to the electrophilic Cr(CO)3 group. Reactions with planar chiral o-substituted benzaldehyde complexes are highly diastereoselective. 3-Hydroxy-2-methylenealkanoic acid derivatives can be obtained efficiently and with very high enantiomeric excess from readily accessible enantiomerically pure complexes. The configuration of the benzylic stereogenic center relative to the planar chirality of the arene complex was determined in one case by an X-ray structural analysis. The reaction has been extended to an o-anisaldehydeimine complex.