Synthesis and Solvolysis of Tricyclo[4.3.2.0^2,5]undeca-3,8,10-trien-7-ol. An Unusual [CH]₁₁⁺ Rearrangement

Synthesis of the title compound (11) has been achieved by two routes, the cycloaddition of cyclobutadiene to tropone and addition of tetrachlorocyclopropene to an appropriate bicyclo[4.2.0]diene (6) and subsequent transformations. Acetolysis of esters of 11 afforded a rearranged allylic acetate (15) and dihydroindenylenol acetate (20). Deuterium-labeling studies indicate that 20 derives from 15 via a bicyclo[2.1.0]pentane (25) and subsequent thermal fission. Activation parameters for this process (ΔH^‡ = 31.2 kcal/m ΔS^‡ = -6.2 eu) are in accord with the proposed mechanism.