Influence of Various Promoters on the Diastereoselectivity of Samarium(II) Iodide Mediated Reductive Carbocyclizations of ω-Iodo-α,β-unsaturated Esters Prepared from 2-Deoxy-d-ribose

ω-Iodo-α,β-unsaturated esters were reduced with SmI2 or Bu3SnH under different conditions to give carbocyclic compounds in good yield. The stereoselectivity of the SmI2 cyclizations varies with the choice of promoter, the reaction temperature, the identity of the hydroxyl protecting groups and the geometry of the double bond.