Radical Cyclization of O‐Pentafluorobenzoyloximes Having a (Cyclohexadiene)Fe(CO)₃ Moiety.

Abstract

Radical Cyclization of O-Pentafluorobenzoyloximes Having a (Cyclohexadiene)Fe(CO) 3Moiety. -Reaction of arylmethyl ketoxime-tricarbonyliron complexes (I) with perfluorobenzoyl chloride provides access to the corresponding benzoyloximes which smoothly cyclize in the presence of atmospheric oxygen to give trans--fused dihydroindole-tricarbonyliron complexes. Isolation of these dihydroindole derivatives with acidic silica Wako gel B-5F provides the corresponding cis-isomers (II) due to complete isomerization. The geometry of the oxime double bond has no significance in the outcome of the cyclization reaction. Oxidative removal of the Fe(CO)3 group proceeds best after N-acyl protection [cf. (III) vs. (VII)]. -(TANAKA, K.; YUKIMURA, N.; NARASAKA*, K.; Bull. Chem. Soc. Jpn. 77 (2004) 3, 575-584; Dep. Chem., Grad. Sch. Sci., Univ. Tokyo, Bunkyo, Tokyo 113, Japan; Eng.) -Mischke 28-131