Reaction of aminocarbene complexes of chromium with alkynes IV. New transformations of the nitrogen ylide complexes derived therefrom

Abstract

Attempts to remove the Cr(CO) 3 group from a series of N-ylide complexes obtained from aminocarbene complexes of chromium and diphenylacetylene failed. With dioxygen under UV irradiation, insertion of an oxygen atom into the NC(O) bond gave aminolactones 8 instead. With sulfur a series of aminofuran complexes 9 were obtained. Olefins such as cyclopentadiene and cyclooctene did not cycloadd to these ylide complexes. Whereas no reaction was observed with cylooctene, with cyclopentadiene an overall protonation-demethylation-demetallation reaction of N-dimethyl ylide complexes 4a and 4b to the pyrrolinones 10a and 10b took place. The same protonation-dealkylation reaction was observed with (ArPS 2) 2. Thus 4a, 4b and 4d led to 10a, 10b and 10d. The fate of the leaving alkyl group was established by carrying out a similar reaction on the N-ylides 4f and 4g derived from piperidine which gave the lactone thiols 11f and 11g. The structure of the aminofuran complex 9b was unambiguously established by X-ray crystallography. The relationship between the structures of the N-ylide complexes and the reaction products is discussed.