Diastereoselective oxidation of β-hydroxysulfides with TBHP: a comparative study of titanocenes and Ti(Oi-Pr)4 as catalysts

Titanocene dichlorides and Ti(Oi-Pr)4 have been used as catalysts for the oxidation with t-butyl hydroperoxide of racemic β-hydroxysulfides having a stereogenic carbon centre in α- or β- position with respect to the sulfur atom. β-Hydroxysulfides were oxidized in high yields to the corresponding sulfoxides, titanocenes being more chemo- and generally more diastereoselective than Ti(Oi-Pr)4. A divergent stereochemical outcome has been observed when using titanocenes or Ti(Oi-Pr)4 in the oxidation of protected β-hydroxy sulfides.