Stereoselective Synthesis of Substituted Tetrahydropyrans and Isochromans by Cyclization of Phenylseleno Alcohols

A selenium-mediated strategy for the stereoselective synthesis of substituted tetrahydropyrans and isochromans has been developed starting from δ-phenylseleno ketones. After enantioselective reduction, the chiral nonracemic phenylseleno alcohols were oxidized to the corresponding selenones, which underwent an effcient 6-exo-tet ring-closure reaction.