Preparation Of Bicyclo Octane Derivatives Catalyzed By Chiral Diamine-Ni（OAc）₂ Complex

During the past few years, the cascade reaction has represented a flourishing area in the organic chemistry. Significant progress has been made from the fields involving Organocatalyzed asymmetric cascade reactions using chiral secondary amines to the area of Metal-catalyzed asymmetric tandem reactions. Because the cascade reactions allow two or more reactions to occur in a single operation under the same reaction conditions, avoid changing the reaction conditions, isolating the intermediates as well as costly protecting-group manipulations. Also, the diaminocyclohexanes, which belong to vivinal diamines bearing a versatile stereochemical control element, typically combine a flexible and economically feasible synthetic route, strongly binding to the metal centre, together with excellent enantioselectivities for a variety of mechanistically diverse reactions. Therefore, with the significant improvement of synthetic efficiency and the reduction of waste and hazardous byproducts as well as the flexibility of catalysts, exploration and development of Metal-catalyzed asymmetric cascade reactions capable of promoting each single step is one of the major topics in current research. For the first time, we are able to report a simple catalyst system assembled from enantiomerically pure diaminocyclohexane and Ni(0Ac)2 (benzylated diaminocyclohexanes-Ni(OAc)2 complexes)efficiently catalyzed the cascade Michael-Henry reaction of variously 1,2-diones with substituted nitroalkenes. Via this catalyzed system, series of different configuration polyfunctionalized bicycle octane derivatives containing four stereogenic centers are obtained. In addition, the base-induced epimerization leading to the decrease of stereoselectivity can be prevented.