Origins of diastereoselectivity in the alkylation of N-substituted lactams and amides derived from optically active aminoalcohols.

The origins of diastereoselectivity in the alkylation of lactams la and Ib and amides 6a and 6b are discussed. A rigid intermediate in which the pyramidalized amide nitrogen chelated the alkoxide lithium cation is invoked. Further experiments conducted with different substrates' are in agreement with the proposed model, Furthermore this model can explain the differences observed previously between ephedrine and pseudoephedrine amide alkylation. Copyright (C) 1996 Elsevier Science Ltd