Imidoylketene–azetin-2-one–oxoketenimine rearrangement

Abstract
N-Adamantylimidoylketene 2 produced from pyrroledione 1 is in thermal equilibrium with azetin-2-one 4; 2 also thermally rearranges to oxoketenimine 3; azetin-2-one 4 is photolytically converted into imidoylketene 2, and thermally cleaved to adamantyl isocyanate 5 and 1-phenylpropyne 6.