Ketene. Part 21. Reactions of heterocumulenes with nitrones

Abstract

Degradative and mass spectrometric evidence confirms the formation of the isoxazolidinones (2) from the reaction of cyano-t-butylketene with the N-alkyl nitrones (1), whilst the reaction with the N-phenyl nitrone (1d) gives the expected oxazolidinone (3b). Cyano-t-butylketene reacts with diphenyl nitrone to give the indolones (10a) and (10b). The reaction of phenyl isocyanate with diphenyl nitrone, and the N-alkyl nitrones (1a) and (1d) gives the normal 1,3-dipolar cycloadducts without rearrangement.

Ethoxycarbonyl-t-butylketene reacts with the N-phenyl nitrone (1d) to give an oxazolidinone, but reaction with the N-alkyl nitrones (1) gives only fiuorenone azine. This ketene reacts with diphenyl nitrone to give the anil (15) and the dihydroindole (16).