Enantioselective Sulfonylation of Polyols

Significance

The authors report a π-methyl histidine based tetrameric peptide catalyzed desymmetrization of polyols through enantioselective mono-sulfonylation. Two methods using different bases (NaHCO₃ or 2,6-lutidine) were employed for the sulfonylation; in the presence of 5 mol% of tetra­peptide 1, various triols and diols can be selectively mono-sulfonated in good yield with high enantioselectivity. The structure of arene-sulfonyl chlorides affects the stereochemical outcome dramatically, in which para-nitrobenzenesulfonyl chloride (p-NsCl) gave an enantiomeric ratio of 97:3, but ortho-nitro- or para-methoxybenzenesulfonyl chloride only afforded er = 66:34 and 77.5:22.5, respectively. The chirality of the proline residue determines the absolute sense of asymmetric induction.