5-Endo Ring Closures of Allylic Hydroperoxides: Useful Routes to 1,2- Dioxolanes Involving Strongly Stereoselective Free Radical and Polar Reactions.

Abstract Intramolecular cyclisation of simple allylic hydroperoxides to give substituted 1,2—dioxolanes using electrophilic reagents has been investigated. Closure using mercury(II) acetate and electrophilic halogen reagents (NBS, Br 2 Bu t OC1) occurs by Markovnikov—directed and conformationally strict stereospecificity. Subsequent free— radical reaction of the mercurated dioxolanes involved specific reaction involving reaction from the sterically unprotected face of the intermediate dioxolanyl radical.