Ring‐opening and a novel ring expansion in the reactions of 1‐Alkyl‐2‐carbomethoxyazetidine with hydrazine

The mechanism of the reactions of 1‐ t ‐butyl‐2‐carbomethoxyazelidine and 1‐benzyl‐2‐carbomethoxyazetidine with hydrazine hydrate was investigated. Treatment of 1‐alkyl‐2‐earbomethoxyazetidine with hydrazine hydrate in cold ethanol yielded 1‐alkylazetidine‐2‐carhohydrazide. Depending on the sterie bulkiness of the alkyl group of the amino functionality, reactions of 1‐alkylazetidine‐2‐carbohydrazides in methanol gave the appropriate aminoester or the appropriate pyrrolidone, or a mixture of both. The intermediacy of the diimide in these transformations was confirmed by the concurrent reduction of azobenzene to hydrazobenzene.