β‐lithiations of carboxamides. Synthesis of β‐substituted‐α,β‐unsaturated amides

N ‐Methyl‐2‐methyl‐3‐(benzotriazol‐l‐yl)propanamide, on treatment with butyllithium forms a dianion which on treatment with alkyl and benzyl halides, aldehydes and ketones affords monosubstituted products; with ethyl p ‐toluate, a lactam is formed. The alkylated derivatives eliminate benzotriazole in the presence of base to afford trisubstituted α,β‐unsaturated amides.