Analysis of quinine as an asymmetric catalyst in the Michael reaction

CHED 795

Kelsey L. Hanson and William Dasher. Department of Chemistry, University of Puget Sound, 1500 North Warner, Tacoma, WA 98416
The enantioselective synthesis of Michael reaction products with various adducts using the cinchona alkaloid quinine and hydride reagent Red-Al as a catalyst are reported. The quinine/Red-Al complex was prepared in a 10% load in situ with the enone and adduct added in stoichiometric amounts to give yields of up to 99.1% of the ketone product. The ketone enantiomers did not efficiently separate on a chiral GC column; however, conversion to a diastereomeric ketal via a microscale reaction using (2R,3R)-butane-diol resulted in near baseline separation of the two diastereomers on a non-polar capillary column. Modest enantiomeric excesses, up to 27%, were achieved using the underivatized quinine/Red-Al complex. Synthesis and results using new derivatized complexes are ongoing.