Radical Cyclization of α-Bromo Aluminum Acetals

Abstract

The radical cyclization of α-halo­acetals onto double bonds (Ueno-Stork reaction) can be a useful method for the synthesis of cyclic acetals (see Review below). The synthesis of the acetal starting materials can be challenging and incompatible with acid-sensitive functional groups. The authors utilize α-bromoesters directly in this transformation by forming aluminum acetals in situ through reduction of esters with DIBAL-H, which then undergo radical cyclization.