Chlorido(η-cyclo-octa-1,5-diene)(N,N'-diethyl-thio-urea-κS)rhodium(I).

In the title rhodium(I) complex, [RhCl(C(8)H(12))(C(5)H(12)N(2)S)], N,N'-diethyl-thio-urea acts as a monodenate S-donor ligand. The rhodium(I) coordination sphere is completed by the Cl atom and the COD [= 1,5-cyclo-octa-diene] ligand inter-acting through the π-electrons of the double bonds. If the midpoints of these two bonds are taken into account, the Rh atom exhibits a distorted square-planar coordination.

Origin of enantioselectivity in palladium-catalyzed asymmetric allylic alkylation reactions using chiral N,N-ligands with different rigidity and flexibility.

The chiral bidentate-N,N ligands, (S(a))-1, (S(a))-2, (S,S)-3 and (S,S)-4, were synthesized. They were shown to contain rigid 2-pyridinyl or 8-quinolinyl building blocks and the C(2)-symmetric chiral frameworks trans-2,5-dimethylpyrrolidinyl or (S)-(+)-2,2'-(2-azapropane-1,3-diyl)-1,1'-binaphthalene. In the (S(a))-2, and (S,S)-4 ligands pair, the 8-quinolinyl skeleton is directly bonded to the C(2)-symmetric chiral frameworks (S)-(+)-2,2'-(2-azapropane-1,3-diyl)-1,1'-binaphthalene or trans-2,5-dimethylpyrrolidinyl.

Effect of chelating vs. bridging coordination of chiral short-bite P-X-P (X=C, N, O) ligands in enantioselective palladium-catalysed allylic substitution reactions.

The chiral short-bite ligands (Ra,Ra)-bis(dinaphthylphosphonito)methane, (Ra,Ra)-1, (Ra,Ra)-bis-dinaphthylpyrophosphite, (Ra,Ra)-2, (Sc)-bis(diphenylphosphino)-sec-butylamine, (Sc)-3, (Ra,Ra)-bis(dinaphthylphosphonito)phenylamine, (Ra,Ra)-4a, (Ra,Ra,Sc)-bis(dinaphthylphosphonito)-sec-butylamine, (Ra,Ra,Sc)-4b, and (Ra,Sc)-(dinaphthylphosphonito)(diphenylphosphino)-sec-butylamine, (Ra,Sc)-5, have been synthesised. The cationic palladium-allyl mononuclear chelate, [Pd(eta3-PhCHCHCHPh)(mu-L-Lshort-bite)]PF6 [L-Lshort-bite=(Sc)-3, (Ra,Ra)-4a, (Ra,Ra,Sc)-4b and (Ra,Sc)-5 for complexes, and, respectively] and binuclear bridged [Pd(eta3-PhCHCHCHPh)(mu-Ra,Ra-2)]2(PF6)2, 12, have been isolated. The short-bite chiral ligands synthesised have been tested in the palladium-allyl catalysed substitution reaction of 1,3-diphenylallyl acetate with dimethyl malonate.

Highly enantioselective nickel-catalyzed hydrovinylation with chiral phosphoramidite ligands.

Readily available chiral phosphoramidites are a promising class of ligands for nickel-catalyzed asymmetric hydrovinylation of vinyl arenes. Cooperative effects are operative when ligands with more than one element of chirality are used. Choosing the proper stereochemistry in each part of the modular ligand system leads to high chemoselectivities and excellent enantioselectivities up to 94%.