Alkene Dioxygenation with Malonoyl Peroxides: Synthesis of γ-Lactones, Isobenzofuranones, and Tetrahydrofurans

Treatment of homoallylic alcohols or carboxylic acids with malonoyl peroxide 1 provides a stereoselective method for the preparation of tetrahydrofurans, gamma-lactones, and isobenzofuranones in 44-82% yield and up to 27:1 trans selectivity. Application of this simple and effective heterocyclization in the synthesis of the antidepressant citalopram is also described.