Enantioselective Michael addition reactions of malononitrile catalyzed by chiral Lewis acid and achiral amine catalysts

Reactions of malononitrile with 3-(2-alkenoyl)-2-oxazolidinones or 1-(2-alkenoyl)-4-bromo-3,5-dimethylpyrazoles can be doubly activated by the use of catalytic amounts (10 mol% each) of both, (R,R)-DBFOX/Ph-Ni(ClO4)(2)(.)3H(2)O and amines, to give the Michael adducts in high chemical yields with satisfactory enantioselectivities. (C) 2003 Elsevier Science Ltd. All rights reserved.