Acid-catalysed intramolecular C-alkylation in β,γ-unsaturated diazomethyl ketones. Part 4. Synthesis of functionalised hydrophenanthrene and benzocyclodecenone derivatives via novel fragmentation reactions, and X-ray structural analyses of two angularly substituted hydrophenanthrene derivatives

Abstract

Some transformations of the octahydro-4a-hydroxy-4,l0a-ethanophenanthren-12-ones (4a–c), derived via acid-catalysed alkylation-rearrangement reactions, are described. Hydrogenolysis of the hydroxycyclopentanones (4a–c) with lithium–ammonia proceeds with retention of configuration to give the respective bridged ketones (6a–c) exclusively; these have been converted into the corresponding octahydrophenanthrene-4,10a-cis-dicarboxylic acids (10a–c). Formylation–oxidation of compounds (4a) and (4c) led to the hydroxy γ-lactonic acid (12a) and the dihydroxy dicarboxylic acid (16c) respectively. The structure of compourid (12a) has been established by X-ray crystallography. The α-keto γ-lactonic esters (15a) and (15c), obtained from compounds (12a) and (16c), respectivelv on oxidative fragmentation led to the respective benzocyclodecenone derivatives (19a) and (19c). The p-methoxy ketone (4b) underwent a novel fragmentation reaction with ethyl formate and sodium hydride giving the hydroxymethylene ester (21), the structure of which has been establishea by X-ray crystallography.