Catalytic regioselective sulfonylation of α-chelatable alcohols:: Scope and mechanistic insight

This paper describes a convenient protocol for the regioselective sulfonylation of alpha-chelatable alcohols. Typically, the reaction of alpha-heterosubstituted alcohols with 1 equiv of p-TsCl and 1 equiv of Et3N in the presence of 2 mol % of Bu2SnO leads to rapid, regioselective, and exclusive monotosylation. The pKa of the amine was correlated to the reaction rate. A plausible mechanism for this reaction has been proposed on the basis of Sn-119 NMR studies.