Highly stereoselective radical cyclization of haloacetals controlled by the acetal center

A systematic investigation of radical haloacetal cyclizations (Ueno-Stork reaction) where the acetal center is the unique stereogenic element is reported. This highly diastereoselective reaction can be used for the preparation of polysubstituted tetrahydrofurans and gamma-lactones. We report herein the full experimental details of reactions where up to three new chiral centers are created. To demonstrate the potential of this approach, short syntheses of (+)eldanolide and of tricyclic acetals related to biologically active lignans have been achieved.