Rhodium-catalyzed regio- and stereoselective 1-seleno-2-thiolation of 1-alkynes

Rhodium complex RhH(PPh3)(4) and 1,1'-bis(diphenylphosphino)ferrocene catalyze the regio- and stereoselective additions of diaryl disulfides and diaryl diselenides to 1-alkynes giving (Z)-1-arylseleno-2-arylthio-1-alkenes. The catalyst promotes the addition reaction of dibutyl disulfide and dibutyl diselenide to 1-octyne with a similar selectivity giving (Z)-1-butylseleno-2-butylthio-1-octene but with a lower catalytic activity. The same product is obtained with a higher yield, when excess dibutyl disulfide is used against dibutyl diselenide in the presence of RhH(PPh3)(4) and 1,4-diphenylphosphinobutane.