Reactions with 4‐Hydroxy‐2‐methylbutananilides: Unexpected Formation of a Cyclopropanecarboxamide

The successive treatment of the N,N-disubstituted 4-hydroxy-2-methylbutanamide 2a with lithium diisopropylamide (LDA) and diphenyl phosphorochloridate (DPPCl) led to the 1-methylcyclopropanecarboxamide 10 in good yield. This base-catalyzed cyclization offers a new approach to cyclopropanecarboxamides. Under similar conditions, the N-monosubstituted 4-hydroxy-2-methylbutanamide 2b gave the 3-methylpyrrolidin-2-one 11. The structure of the cyclopropanecarboxamide 10 was established by X-ray crystallography.