TRANSITION-METAL-CATALYZED REACTIONS OF CHALCOGEN COMPOUNDS

Novel transition metal-catalyzed reactions of organic chalcogen compounds with acetylenes are described. In the presence of transition metal-catalysts such as Pd(PPh3)4, the addition of diaryl disulfides and diselenides to terminal acetylenes takes place stereoselectively to give high yields of (Z)-1,2-bis(arylthio)-1-alkenes and (Z)-1,2-bis(arylseleno)-1-alkenes, respectively. Similarly, many transition metal-complexes catalyze the addition of thiols(and selenols) to acetylenes, providing vinylic sulfides(and selenides) regioselectively. These reactions may involve vinylic metals as the intermediate. Thus, when the reaction of diaryl disulfides and diselenides with terminal acetylenes is performed under the pressure of carbon monoxide, the carbonylative addition occurs and carbon monoxide is regioselectively incorporated on the side of the terminal carbon of the acetylenes. The obtained carbonylation products, i.e., alpha, beta-unsaturated thiolesters and selenolesters, can be reduced chemoselectively to corresponding alpha, beta-unsaturated aldehydes by treatment with n-Bu3SnH in the presence of Pd(PPh3)4. We believe that this study will open up a new field of transition metal chemistry in combination with sulfur and selenium chemistry.