Ruthenium-catalyzed stereoselective anti-Markovnikov-addition of thioamides to alkynes.

A catalyst system generated in situ from bis(2-methallyl)-cycloocta-1,5-diene-ruthenium(II) and a phosphine was found to efficiently catalyze the addition of thioamides to terminal alkynes with exclusive formation of the anti-Markovnikov thioenamide products. The stereoselectivity of the addition is usually high and controlled by the choice of the phosphine ligand, whereas the (E)-isomers are predominantly formed in the presence of tri(n-octyl)phosphine, the use of bis(dicyclohexylphosphino)methane preferentially leads to the formation of the (Z)-configured thioenamides.

(R(p))-1-{(R)-(Dimethyl-amino)[2-(diphenyl-phosphan-yl)phen-yl]methyl}-2-(diphenyl-phosphan-yl)ferrocene chloro-form solvate.

The absolute configuration of the title mol-ecule, [Fe(C(5)H(5))(C(38)H(34)NP(2))]·CHCl(3), is R,R(p). The mol-ecular structure is similar to the structure of the solvent-free compound [Fukuzawa, Yamamoto & Kikuchi (2007 ▶). J. Org. Chem. 72, 1514-1517], but some torsion angles about the P-C(phen-yl) bonds differ by up to 25°. The P atoms and the N atom have a distorted trigonal-pyramidal geometry. The chloro-form solvate group donates a C-H⋯π bond to the central benzene ring and is also involved in six inter-molecular C-H⋯Cl contacts with H⋯Cl distances between 2.96 and 3.13 Å.