An approach to synthesis of trichodiene

Vita.The purpose of this study was to develop a novel synthetic method to synthesize trichodiene (1). This study has utilized 2-methyl- Δ¹- cyclopentenecarboxylic acid (23) as the starting material for the preparation of dienone 51, which was subsequently cyclized to form tricyclic ketone 58. Tricyclic ketone 58 was the key intermediate in this synthetic approach to trichodiene (1). Acid 23 was readily prepared from its corresponding methyl ester 34, which was synthesized from methyl 2-oxy-cyclopentanecarboxylate (30). Acid 23 was converted to acid chloride 55 by treatment with oxalyl chloride in benzene. Reaction of acid chloride 55 with methylcyclohexene in the presence of stannic chloride as catalyst gave chloro ketone 56, which was dehydrohalogenated to give dienone 51. [See PDF for diagram] Cylization of dienone 51 in trifluoroacetic acid gave tricyclic ketone 58, which was the key intermediate in this synthetic study. Methods to cleave the central ring of tricyclic ketone 58 to form the basic ring skeleton of tri-chodiene (1) were investigated. [See PDF for diagram