An efficient direct activation method transferring diastereopure platinum complex of BIPHEP to highly efficient Lewis acid catalyst for enantio selective carbonyl-ene reaction

An efficient direct activation method was developed to transfer diastereopure lambda-[(BIPHEP)Pt(S-BINOL)] to highly active and selective enantiopure Lewis acid lambda-[(BIPHEP)Pt](SbF6)(2) by silver hexafluoroantimonate(AgSbF6) for the enantioselective carbonyl-ene reactions. Both enantioselective glyoxylate-ene reactions between ethyl glyoxylate and alkenes, and enantioselective carbonyl-ene reactions between phenylglyoxal and alkenes were studied demonstrating good catalytic activity and enantioselectivity. Particularly, for the enantioselective carbonyl-ene reaction between phenylglyoxal and 2,3-dimethyl-1-butene, the Lewis acid catalyst lambda-[(BIPHEP)Pt](SbF6)2 generated with this direct activation method by silver hexafluoroantimonate(AgSbF6) could give excellent ee values high up to 94%. (c) 2005 Elsevier B.V. All rights reserved.