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.