Polyphosphate ester-catalysed cyclodehydration of monoesters of N-substituted 3-(indol-3′-yl)-5-methylcyclohex-4-ene-1,2-dicarboxylic acids; stereoselective synthesis of methyl 9-methyl-6-oxo-5-tosyl-5,6,6aβ,7β,8,10aβ-hexahydroindeno[2,1-b]indole-7α-carboxylate. X-Ray molecular structure of methyl 5-methoxy-9-methyl-6-oxo-5,6,6aβ,7β,8,10aβ-hexahydroindeno[2,1-b]indole-7-carboxylate

Abstract

The effect of the N-substituents on the polyphosphate ester-(PPE)-catalysed cyclodehydration of a monoester of N-substituted 5-methyl-3-(indol-3′-yl)cyclohex-4-ene-1,2-dicarboxylic acids (41) is presented. Stereoselective synthesis of methyl 9-methyl-6-oxo-5-tosyl-5,6,6aβ,7β,8,10aβ-hexahydroindeno[2,1-b]indole-7α-carboxylate (2), the key synthetic intermediate for C(7)-functionalized antifertility agent yuehchukene (YCK)(1) analogues, is described.