Synthesis of polycyclic compounds. Part VIII. Friedel–Crafts acylation with anhydrides of tricarboxylic acids. Synthesis of 16,17-dihydro-17-methyl-15H-cyclopenta[a]phenanthrene

Abstract

The acylation of naphthalene, 1- and 2-methylnaphthalenes, and 1,2,3,4-tetrahydronaphthalenes with propane-1,2,3-tricarboxylic acid 1,2-anhydride and its 2-methyl derivative is described. 1,2,3,4-Tetrahydro-oxophenanthreneacetic acids have been prepared in good yields by this method. The structures of the intermediates were established by independent syntheses. The keto-acid formed by acylation of naphthalene with 3-methylbutane-1,2,4-tricarboxylic acid 1,2-anhydride has been utilised for a new and improved route to 16,17-dihydro-17-methyl-15H-cyclopenta[a]phenanthrene (Diels hydrocarbon). The keto-acid from naphthalene and 2-methylpropane-1,2,3-tricarboxylic acid 1,2-anhydride was converted into racemic oestra-1,3,5(10),6,8-pentaen-17-one [trans-(±)-3-deoxyequilenin] by known methods.