SmI(2)-H(2)O reduces cyclic 1,3-diesters to 3-hydroxyacids with no over-reduction. Furthermore, the reagent system is selective for cyclic 1,3-diesters over acyclic 1,3-diesters and esters. Experimental and computational studies suggest that the origin of the selectivity lies in the initial electron transfer to the ester carbonyl and the anomeric stabilization of the resulting radical-anion intermediate. Radicals formed by one-electron reduction of the ester carbonyl group have been exploited in intramolecular additions to alkenes.

SmI(2)/H(2)O reduces cyclic 1,3-diesters to 3-hydroxyacids with no over reduction. Furthermore, the reagent system is selective for cyclic 1,3-diesters over acyclic 1,3-diesters, and esters. Radicals formed by one-electron reduction of the ester carbonyl group have been exploited in intramolecular additions to alkenes. The ketal unit and the reaction temperature have a marked impact on the diastereoselectivity of the cyclizations. Cyclization cascades are possible when two alkenes are present in the starting cyclic diester and lead to the formation of two rings and four stereocenters with excellent stereocontrol.

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