Mild Deprotection of Dithioacetals by TMSCl/NaI Association in CH3CN

We showed for the first time, the fundamental role of CH3CN associated to TMSCl/NaI combination to deprotect S,S-ethylene- and S,S-propylene-ketals into ketones. Indeed, if the TMSCl/NaI association leads to the reduction of dithioketals in CH2Cl2, we have demonstrated that this association can be used to deprotect a large variety of various dithioketals into ketones in CH3CN. Otherwise, under mild experimental conditions, O,O-acetals as well as O,S-oxathianes were cleanly deprotected with high yields. It is also possible to easily regenerate the carbonyl function of various hydrazones and imines using this novel protocol. We believe that this metal-free process is a good alternative to other known methodologies used to deprotect dithioketals into ketones.