Diisophorone and related compounds. Part 23. A rearrangement of the tricyclo[7.3.1.02,7] tridecane to the bicyclo[4.2.1]nonane-7-spiro-2′-(tetrahydrofuran) ring system

Abstract

3,4-Dioxo-2,7-epoxydiisophoran-1-ol, a compound of the tricyclo[7.3.1.0^2,7]tridecane ring system, is converted by hydrogen peroxide in acidic media into a keto acid of the bicyclo[4.2.1]nonane-7-spiro-2′-(tetrahydrofuran) ring system by skeletal changes involving a Baeyer–Villiger oxidation, a recyclisation, and a pinacol rearrangement. Other members of this bridged ring structure are accessible from the keto acid by appropriate transformations. Their chemical and spectral properties including the results of two-dimensional carbon-13 NMR measurements, are in accord with the structural assignment to the new ring system.