New approach to the preparation of bicyclo octane derivatives via the enantioselective cascade reaction catalyzed by chiral diamine-Ni(OAc) 2 complex

Abstract

A highly efficient catalyst system assembled from enantiomerically pure diaminocyclohexane and Ni(OAc) 2 is, for the first time, used to catalyze the cascade Michael-Henry reaction of various diones and substituted nitroalkenes. A series of polyfunctionalized bicyclo[3.2.1]octane derivatives containing four stereogenic centers are prepared with excellent enantioselectivities (up to >99% ee) and diastereoselectivities (up to 50:1 dr) with high yields. In addition, via this chiral diamine-Ni(OAc) 2 catalyst system, the base-induced epimerization leading to the decrease of stereoselectivity can be prevented. © 2012 The Royal Society of Chemistry.