RhH(PPh(3))(4) and 1,1'-bis(diphenylphosphino)ferrocene catalyze the regio- and stereoselective additions of diaryl disulfides and diaryldiselenides 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
When diphenyldiselenide is heated at 150–180 °C in the presence of acetylenes, an acetylene insertion reaction into the Se–Se bond of the diselenide takes place to provide vic-bis(phenylseleno)alkenes in moderate to high yields.
Novel transition-metal-catalyzed reactions of disulfides and diselenides with acetylenes are described. In the of tetrakis(triphenylphosphine)palladium(0), [Pd(PPh3)4], the (1) of diaryl disulfides and diselenides to terminal acetylenes 1 takes place stereoselectively to give high yields of (Z)-1,2-bis(arylthio)-1-alkenes 2 and (Z)-1,2-bis(arylseleno)-1-alkenes 3, respectively. A mechanistic proposal includes the following: (1) oxidative addition of (ArY)2 [Y = S, Se] to low-valent palladium species, (2) stereoselective cis-thiopalladation or cis-selenopalladation to acetylenes to form a cis-vinylpalladium intermediate, and (3) reductive elimination of the product with retention of the stereochemistry. When the reaction of diaryl disulfides and diselenides with terminal acetylenes is performed under the pressure of carbon monoxide, the carbonylative addition occurs to afford (Z)-1,3-bis(arylthio)-2-alken-1-ones 4 and (Z)-1,3-bis(arylseleno)-2-alken-1-ones 5, respectively. Carbon monoxide is regioselectively incorporated on the side of the terminal carbon of the acetylenes.
Highly Selective Three-Component Coupling of Ethyl Propiolate, Alkenes, and Diphenyl Diselenide under Visible-Light Irradiation
Just the right strength of carbon-radical trapping by diphenyldiselenide facilitates its selectivethree-componentcoupling with an electron-poor alkyne and an electron-rich alkene [Eq. (1)]. In contrast, (PhS)2 is too weak and (PhTe)2 too strong a radical trap, and polymerization of the unsaturated compounds and addition of (PhTe)2 to the alkyne occur, respectively.
The oxidation of 1,2-bis(phenylseleno)-1-alkenes and the reactivity of thus formed selenoxides have been investigated. When (Z)-1,2-bis(phenylseleno)-1-octene was oxidized with two equivalents of MCPBA, a novel selenoxide anti-elimination has been found to take place at or below room temperature.