The first example of transition-metal-catalyzed hydroselenation of acetylenes

Unusual Influence of the Structures of Transition Metal Complexes on Catalytic C–S and C–Se Bond Formation Under Homogeneous and Heterogeneous Conditions

“…In the same manner, Pd-(OAc) 2 catalyzed regioselective PhSeH addition to alkynes, which took place in benzene solution at 80°C. [51] The catalytic reaction resulted in 62-73 % yields of the α isomer 13, depending on the nature of the substituent R, except in the case of activated phenylacetylene, which gave significant amounts of anti-Markovnikov species (33 % of 13 and 64 % of 4 + 5). Scheme 12. Much better results in the synthesis of Markovnikov product were achieved by using Pd(OAc) 2 catalyst in pyridine to perform the hydroselenation reaction.…”

“…[50,51] ArSH addition to terminal alkynes was carried out with 55-87 % product yields and Ͼ11:1 selectivities with regard to Markovnikov/antiMarkovnikov products (THF, 67°C, 12-16 h). Depending on reaction temperature, up to 14 % of 14 was obtained due to an isomerization side-reaction.…”

Chemicals from Alkynes with Palladium Catalysts

“…98 The use of Pd(OAc) 2 (2 mol%) showed to catalyze the hydroselenation of terminal alkynes with benzeneselenol in benzene as solvent at 80 ºC, leading to branched vinyl selenides. 99 However, small amounts of byproducts from double hydroselenation and isomerization are formed under these conditions, the selectivity to the final terminal alkene being achieved totally by using pyridine as solvent as exemplified in Scheme 38 with the preparation of 104 from 5-methylhex-1-yne.…”

Catalytic Markovnikov and anti‐Markovnikov Functionalization of Alkenes and Alkynes: Recent Developments and Trends

“…Thus, in the presence of Pd(OAc) 2 , thiophenol adds to alkynes giving the corresponding vinylic sulfides with Markovnikov selectivity in moderate to good yields (29-87 %). [209] The possible active catalyst here is a polymeric palladium sulfide species [{Pd(SPh)} n ] which undergoes regioselective thiopalladation of alkynes to the corresponding vinylic palladium intermediate followed by protonation forming the Markovnikov type vinylic sulfide B. When [PdCl 2 (PhCN) 2 ] is used as the catalyst, a novel Markovnikov addition and sequential double-bond isomerization occur, forming the corresponding internal vinylic sulfides of the type C (Scheme 69).…”