Nickel(II) Chloride‐Catalyzed Regioselective Hydrothiolation of Alkynes

Abstract

Regioselective Markovnikov-type addition of PhSH to alkynes (HC C-R) has been performed using easily available nickel complexes. The non-catalytic side reaction leading to anti-Markovnikov products was suppressed by addition of g-terpinene to the catalytic system. The other side reaction leading to the bis(phenylthio)alkene was avoided by excluding phosphine and phosphite ligands from the catalytic system. It was found that catalytic amounts of Et 3 N significantly increased the yield and selectivity of the catalytic reaction. Under optimized conditions high product yields of 60 -85% were obtained for various alkynes [R ¼ n-C 5 H 11 , CH 2 NMe 2 , CH 2 OMe, CH 2 SPh, C 6 H 11 (OH), (CH 2 ) 3 CN]. The X-ray structure of one of the synthesized products is reported.

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

“…[55] The formation of complexes 8 was confirmed by 31 P NMR spectroscopy. [53,56] The process was accompanied by H 2 evolution, which was detected by 1 H NMR for both E = S [56] and E = Se. [53] Alkyne insertion into the Pd-E bond of dinuclear complex 8, followed by protonolysis of the Pd-C bond, gives Markovnikov-type alkene 13 (Scheme 13).…”

“…An attempt to involve arylthiols was unsuccessful; in the case of S-H bond addition the Pt-catalyzed reaction resulted in a complicated mixture of compounds with a rather low yield of 13. [56] Rhodium complexes catalyzed selective hydrothiolation reactions, but afforded the anti-Markovnikov β isomers (Scheme 11; RЈ = H for terminal alkynes). The Wilkinson complex Rh(PPh 3 ) 3 Cl was found to be an excellent catalyst for reactions of alkynes (19) with arylthiols, resulting in products 20 with good to high yields 62-97 %.…”

“…[63] Carrying out catalytic PhSH and PhSeH addition to N,N-dimethylpropargylamine and crystallization of the products as oxalic acid salts gave crystals of 13 (E = S, Se; R = CH 2 NMe 2 ) of sufficient quality for X-ray analysis. The molecular structures of both products E = S [56] and E = Se [53] were established.…”

Thiol-yne click polymerization

“…Besides the radical and amine-mediated reactions, the transition-metal complexes could catalyze the thiol-yne reaction and have been proven to be efficient catalysts for the preparation of regio-and stereo-regular vinyl sulfides. Several transition metal-based catalysts such as Rh, Ir, Ni, Pd, Pt, Au, and Zr have been developed [44][45][46]. Generally, the transition-metal-catalyzed thiol-yne reaction proceeds via a Migratory-Insertion mechanism [44].…”

The Mechanism for Transition-Metal-Catalyzed Hydrochalcogenation of Unsaturated Organic Molecules

“…The hydrothiolation and hydroselenation of alkynes catalyzed by NiCl 2 [27] or Ni(acac) 2 [28][29][30] under heterogeneous conditions and by CpNi(NHC)Cl [31] have been reported. The hydrothiolation of 1-heptyne with PhSH (2 equiv) was catalyzed by Ni (acac) (2 mol%) at 40 C under solvent-free conditions to produce 9, 10, and 11 in 81%, 4%, and 4% yields, respectively (7).…”