Allenes. Part XXIV. Preparation of α-allenic alcohols from the mono-O-tetrahydropyran-2-yl derivatives of butyne-1,4-diols

α-Allenic alcohols are obtained in high yield by the ready reductive elimination of the tetrahydropyranyloxy-group from the mono-O-tetrahydropyran-2-yl derivatives of butyne-1,4-diols with lithium aluminium hydride. Attempted reduction of the mono-O-tetrahydropyranyl derivative of an enynediol gave an isomeric mixture of an allenic and an acetylenic alcohol. O-Tetrahydropyranyl groups on secondary or tertiary alcohol functions have been shown to migrate to primary systems.