Asymmetric Aza-Michael Reactions Catalyzed by Cinchona Alkaloids

The organocatalyzed asym. aza-Michael addn. of hydrazones to cyclic enones has been achieved in good yield and stereoselection using cheap and com. available cinchona alkaloids as catalysts. A systematic study of the influence of the structure of the enone on the stereoselectivity was carried out, leading to optically active products with up to 77% ee. The products can be recrystd. to give nearly enantiopure products, and furthermore it was shown that the products could be reduced to the corresponding 1,3-benzylidenehydrazino alc. derivs. with high diastereoselectivity.