A new tetracyclic sesquiterpene hydrocarbon from trans-farnesic acid; X-ray crystal structure of 8-bromomethyl-1,4-dimethyl-9-methylenetetracyclo[5.2.1.1.0]undecane

Abstract

Sesquifilifolone (1), a cyclisation product of farnesic acid, has been reduced to the corresponding epimeric alcohols. These epimers (2) and (3) cyclise with rearrangement when treated with 50% sulphuric acid to give a new sesquiterpene hydrocarbon C₁₅H₂₂, the structure of which has been determined by analysis of its spectroscopic properties, its reactivity, and by X-ray analysis of the rearranged monobromo-derivative 8-bromomethyl-1,4-dimethyl-9-methylenetetracyclo[5.2.1.1.0]undecane (8).