Imidazolylidenes, imidazolinylidenes and imidazolidines

Abstract Starting from glyoxal, 1,3-diarylimidazolinium chlorides 3 were obtained in a three-step sequence via the diimines (1) and ethylene diamine dihydrochlorides (2). Reduction of 1,3-diarylimidazolinium chlorides (3) with lithium alumnium hydride furnished the 1,3-diarylimidazolidines (4) while their deprotonation with potassium hydride in thf gave access to stable carbenes (1,3-diarylimidazolin-2-ylidenes, 5). Similarly substituted imidazol-2-ylidenes are described for comparison.