Tandem and two-directional asymmetric catalysis of the Mukaiyama aldol reaction

Article abstract of DOI:10.1016/S0040-4039(96)02376-3

Upon addition of an excess amount of an aldehyde 3, the Mukaiyama aldol reaction of a silyl enol ether 2 proceeds in tandem and two-directional fashion by the asymmetric catalysis of a binaphthol-derived chiral titanium complex (BINOL-Ti: 1) to give the silyl enol ether 4 in 77% isolated yield in more than 99% de and 99% de. The present asymmetric catalytic Mukaiyamn aldol reaction is characterized by amplification phenomena of the product chirality on going from the one-directional aldo intermediate 6 (98.5% ee, R) to the two-directional product 4 (99.6% ee, R,R). Further transformation of the pseudo C₂ symmetric product 4 (> 99% ee, > 99% de) in its' protected form as the silyl enol ether is established leading to a potentially potent analogue of HIVP inhibitor 9a.