Synthesis of Homophthalates from Allenic Diesters: Conversion into Viocristin and Analogues, and Application to 6-Methylpretetramid.

Abstract

Oxy-substituted homophthalic anhydrides have been synthesized by cycloaddition of di- and tri-oxy butadienes to the allenic diester (1). By base-catalysed cycloaddition to appropriate benzoquinones they have afforded new syntheses of viocristin (19), isoviocristin (20) and analogous 1,4-anthraquinones. Related chemistry has led to the naphthalene (34) and the anhydride (35), intermediates in published syntheses of semivioxanthin and 6- methylpretetramid respectively.