The reaction between N-substituted enamines and phenylglyoxal or glyox
al yielded Delta(2)-pyrrolin-5-ones in moderate to good yields. An unc
ommon pyrrolo [2,1-b]thiazole derivative was formed as a minor product
when a N-(2-mercaptoethyl)enamine was used as the starting reagent. A
n explanation for the regiochemistry of the reaction is proposed.