Discrimination of Diastereotopic Sulfonyl Oxygens by Intramolecular Hydrogen Bonding: Stereoselective Hydrogenation of α-Sulfonyl Radicals.

Abstract Stereoselective intramolecular hydrogen bonding between the hydroxy group and a stereogenic sulfonyl oxygen led to high diastereoselectivity in the radical reaction of α-(1-hydroxyethyl)vinyl sulfone with alkyl iodides and tributyltin hydride in the presence of triethylborane as a radical initiator. Intramolecular hydrogen bonding was demonstrated to play an important role in controlling the diastereoselectivity.