The unusual influence of hetaryl groups on the direct conversion of some secondary alcohols into thiols with Lawesson’s reagent: elucidation of the reaction mechanism

A series of hetaryl-substituted methanols were used for direct conversion into the corresponding thiols by treatment with Lawesson’s reagent in boiling toluene. Unexpectedly, the respective sulfides were formed exclusively. In the case of chiral alcohols, the sulfides were obtained as 1:1-mixtures of meso- and dl-diastereoisomers. In contrast to hetaryl-substituted alcohols, the analogous protocol applied for benzhydryl alcohol led to a mixture of the expected secondary thiol and a bis(diphenylmethyl) trithiophosphonate. Finally, the analogous reactions with ferrocenyl(phenyl)methanol and diferrocenylmethanol, respectively, led to the corresponding thiols in good yield