General procedure for the synthesis of spirocyclic 3-hydroxy- and 3-oxotetrahydrofurans containing carboand heterocyclic fragments

Abstract

Reactions of cyclopentanone, cyclohexanone, N-substituted pyrrolidin-3-one and piperidin-4-one, and tetrahydropyran-4-one with allyl bromide in the presence of zinc and ammonium chloride gave the corresponding geminal hydroxy allyl derivatives. Treatment of the latter with sodium periodate in the presence of sodium metabisulfite resulted in their oxidative cyclization with formation of oxa spirocyclic alcohols containing carbo- and heterocyclic fragments. Swern oxidation of the spiro alcohols afforded the corresponding ketones which were characterized as 2,4-dinitrophenylhydrazones.