Structurally modified antitumour agents. Part 1. Synthesis of cyclopropapyrrolo[1,2-a]indoles related to mitosenes by intramolecular cycloaddition

Abstract

N-Alkylation of indole-2-carbaldehydes with allyl halides followed by reaction with toluene-p-sulphonylhydrazide gives tosylhydrazones (14). Decomposition of the sodium salts of the tosylhydrazones (14) at ca. 140 °C results in an lntramolecular 1,3-dipolar cycloaddition to give, after loss of nitrogen, the cyclopropapyrroloindoles (15). At lower temperatures the intermediate cycloadduct pyrazoline can be isolated. The cyclopropapyrroloindoles react as simple indoles and readily undergo Vilsmeier formylation.