REACTION OF AMINOCARBENE COMPLEXES OF CHROMIUM WITH ALKYNES .4. NEW TRANSFORMATIONS OF THE NITROGEN YLIDE COMPLEXES DERIVED THEREFROM

Attempts to remove the Cr(CO)(3) group from a series of N-ylide comple xes obtained from aminocarbene complexes of chromium and diphenylacety lene failed. With dioxygen under UV irradiation, insertion of an oxyge n atom into the N-C(O) bond gave aminolactones 8 instead. With sulfur a series of aminofuran complexes 9 were obtained. Olefins such as cycl opentadiene and cyclooctene did not cycloadd to these ylide complexes. Whereas no reaction was observed with cyclooctene, with cyclopentadie ne an overall protonation-demethyl-ation-demetallation reaction of N-d imethyl ylide complexes 4a and 4b to the pyrrolinones 10a and 10b took place. The same protonation-dealkylation reaction was observed with ( ArPS2)(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 reactio n on the N-ylides 4f and 4g derived from piperidine which gave the lac tone thiols 11f and 11g. The structure of the aminofuran complex 9b wa s unambiguously established by X-ray crystallography. The relationship between the structures of the N-ylide complexes and the reaction prod ucts is discussed.