Asymmetric Aldol Additions with Titanium Enolates of Acyloxazolidinethiones: Dependence of Selectivity on Amine Base and Lewis Acid Stoichiometry

摘要

Thus, aldol reactions of the titanium enolates of acyl oxa- zolidinethiones can be executed with extremely high selectivities at 0 deg C with readily available and easily handled reagents, and only 1 equiv of aldehyde is required. Additionally, either enan- tiomeric syn aldol product (after removal of the auxiliary) may be obtained from the same acyloxazolidinethione by simply changing the reaction conditions. A variety of aldehyde struc- tural types, including unsaturated aldehydes are tolerated.