Supplementary Material Available: IR spectra of the carbonyl regions for 4,5, and 5/6, tables of thermal parameters, and a full listing of bond distances and angles ( 5 pages); tables of observed and calculated structure factors ( 5 pages). Ordering information is given on any current masthead page.Abstract: Photolysis of chromium-carbene complexes in the presence of nucleophiles gives ketene-derived products. This observation, in conjunction with the stereoselectivity observed in the photolytic reactions of chromium-carbene complexes with imines to produce &lactam, suggests the intermediacy of photolytically generated, metal-coordinated ketenes. Photolysis of chromium-carbene complexes containing a chiral, optically active amino alcohol group produced lactones in high yield and high diastereoselectivity. These lactones are convertible to optically active amino acids.A new synthetic approach to 6-lactams involving the photolytic reaction of heteroatom-stabilized ('Fischer") c h r o m i u m e r b e n e complexes with imines was recently developed in these laboratories (eq 1).l4 The process is quite general and tolerates wide vari-(1) McGuire, M. A.; Hegedus, L. S. J. Am. Chem. Sac. 1982,104,5538. ( 2 ) Hegedw, L. S.; McGuire, M. A.; Schultze, L. M.; Yijun, C.; Anderson, 0. P. J. Am. Chem. Sac. 1984, 106,2680. 0002-7863/88/1510-2122$01.50/0 ims . MI. m. H. xw. MLJ ations in the structure of both the carbene and the imine. The reactions proceed in high yield under very mild conditions

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