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Paper | Regular issue | Vol 32, No. 10, 1991, pp.2005-2014
Published online, 1st January, 1970
DOI: 10.3987/COM-91-5852
DDQ Oxidation of Ring-A Methoxylated 11b-Methoxycarbonyl-2,3,5,6,11,11b-hexahydro-3-oxo-1H-indolizino[8,7-b]indoles

Krishnaswamy Narayanan and James M. Cook*

*Department of Chemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, U.S.A.

Abstract

A study of the oxidation of ring-A methoxylated 11b-methoxycarbonyl-2,3,5,6,11,11b-hexahydro-3-oxo-1H-indolizino[8,7-b]indoles (8a - 8e) with DDQ in aqueous tetrahydrofuran was carried out. Treatment of 8a - 8c under these conditions effected regiospecific oxidation at C-6 in yields ranging from 40-73% to provide the corresponding ring-A methoxylated 3,6-dioxo-1H-indolizino[8,7-b]indoles (12a -12c), respectively. The oxidation of the 7,8,9-trimethoxy analog (8d) also gave the 6-oxo derivative (12d), albeit in low yield. In contrast, the reaction of 8,10-dimethoxyindolizino[8,7-b]indole (8e) with DDQ (aq. THF) generated the quinone (12e), the structure of which is reminescent of the mitomycins. A proposed pathway for the origin of quinone (12e) is presented.