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.

(S)-1-Diphenyl-phosphanyl-2-{(S)-[2-(diphenyl-phosphan-yl)phen-yl]hydroxy-meth-yl}ferrocene.

The absolute configuration of the title compound, [Fe(C(5)H(5))(C(36)H(29)OP(2))], is S(p) at the ferrocene group and S at the asymmetric C atom. Both P atoms have a trigonal-pyramidal conformation. There is a short intra-molecular C-H⋯P contact with an H⋯P distance of 2.56 Å. The hydr-oxy group is involved in an intra-molecular O-H⋯π(phen-yl) inter-action. The crystal packing shows five very weak inter-molecular C-H⋯π contacts, with H⋯Cg distances between 3.26 and 3.39 Š(Cg is the centroid of a phenyl or cyclo-penta-dienyl ring).

(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.

Ru-catalyzed stereoselective addition of imides to alkynes.

A catalyst system formed in situ from bis(2-methylallyl)cycloocta-1,5-dieneruthenium(II) ((cod)Ru[met]2), a phosphine, and scandium(III) trifluoromethanesulfonate (Sc(OTf)3) was found to efficiently catalyze the anti-Markovnikov addition of imides to terminal alkynes, allowing mild and atom-economic synthesis of enimides. Depending on the phosphine employed, both the (E)- and the (Z)-isomer can be accessed stereoselectively.

Asymmetric rhodium-catalyzed hydrogenation meets gold-catalyzed cyclization: Enantioselective synthesis of 8-hydroxytetrahydroisoquinolines.

Different furyl-substituted (Z)-dehydroamino acid derivatives were hydrogenated with the rhodium/Mandyphos(OMe)-system to give enantiomeric excesses between 80 and 98 %. The absolute configuration of the newly formed stereogenic center was determined by anomalous diffraction to be R. These chiral furyl alanines were transferred into 8-hydroxytetrahydroisoquinolines by employing gold-catalyzed arene synthesis as the key step. During the latter reaction sequence, also including either a propargylation or a reduction, a protection of the hydroxy group, and a subsequent propargylation, no racemization of the stereogenic center was observed. With very electron-rich furans, instead of the 8-hydroxytetrahydroquinolines as products, furans anellated to seven-membered rings with exocyclic C-C double bonds are formed under the same reaction conditions.