Calcium-Catalyzed Bis-hydrothiolation of Unactivated Alkynes Providing Dithioacetals
摘要:
Bis-hydrothiolation of alkynes providing anti-Markovnikov dithioacetals is reported. Lewis-acidic Ca(OSO2C4F9)(2) (Ca(ONf)(2)) was synthesized for the first time and was shown to be an excellent catalyst for the transformation. The reaction is highly selective and has a wide substrate scope. It was revealed that vinyl sulfides were intermediates for this transformation and that Ca(ONf)(2) efficiently catalyzed the unprecedented reactions of unactivated vinyl sulfides with thiols to afford the dithioacetals in good to high yields.
Phosphorus pentoxide supported on silica gel (P2O5/SiO2) efficiently acts as a highly active and reusable catalyst for cyclic and non-cyclic S,S-acetalization of a variety of carbonyl compounds under mild, solvent-free and ambient conditions. This method offers significant advantages such as high conversion, clean work-up, short reaction times and simplicity in operation.[GRAPHICS].