Bicyclo[2.2.2]octane-2-spirocyclohexanes, Part 4. Birch Reduction of Spirodiisophor-6-ones

Abstract

Birch reduction of spirodiisophorones by sodium in liquid ammonia - t-butanol reduces their normally inert 6-keto-group, producing the corresponding secondary alcohols, the 6-hydroxygroup of which assumes the endo- or exo-configuration. 3´-Oximinospirodiisophor-6-one is converted predominantly into the 6-endo-hydroxy-compound , from which the 3´,6-endo-ketol is obtainable by the action of sodium bisulphite. 3´-eq(and ax)-Hydroxyspirodiisophor-6-one each yield a pair of stereoisomeric 3´,6-diols, distinguished by their spectral characteristics and derivatives. Spirodiisophora-3´,6-dione yields a mixture of the same four diols, three of which are isolable in low yield. The structure of selected compounds is correlated with their assigned 13C NMR spectra.