Asymmetric Transfer Hydrogenation of Arylketones Catalyzed by Enantiopure Ruthenium(II)/Pybox Complexes Containing Achiral Phosphonite and Phosphinite Ligands.

A family of complexes of the formula -[RuCl(L)(R-pybox)] (R-pybox = (,)-Pr-pybox, (,)-Ph-pybox, L = monodentate phosphonite, PPh(OR), and phosphinite, L = PPh(OR), ligands) were screened in the catalytic asymmetric transfer hydrogenation of acetophenone, observing a strong influence of the nature of both the R-pybox substituents and the L ligand in the process. The best results were obtained with complex -[RuCl{PPh(OEt)}{(,)-Ph-pybox}] (), which provided high conversion and enantioselectivity (up to 96% enantiomeric excess, ) for the reduction of a variety of aromatic ketones, affording the ()-benzylalcohols.

Synthesis of Silver(I) and Gold(I) Complexes Containing Enantiopure Pybox Ligands. First Assays on the Silver(I)-Catalyzed Asymmetric Addition of Alkynes to Imines.

Dinuclear complexes [Ag2(CF3SO3){(S,S)-(i)Pr-pybox}2][CF3SO3] (1), [Ag2(R-pybox)2][X]2 [R-pybox = 2,6-bis[4-(S)-isopropyloxazolin-2-yl]pyridine (S,S)-(i)Pr-pybox and X = PF6 (2) and BF4 (3); R-pybox = 2,6-bis[(3aS,8aR)-8,8a-dihydro-3aH-indeno[1,2-d]oxazol-2-yl]pyridine (3aS,3a'S,8aR,8a'R)-indane-pybox and X = CF3SO3 (4)], [Ag2{(S,S)-(i)Pr-pybox}{(3aS,3a'S,8aR,8a'R)-indane-pybox}][CF3SO3]2 (5), and [Ag2(R-pybox)3][X]2 [R-pybox = (3aS,3a'S,8aR,8a'R)-indane-pybox and X = CF3SO3 (10), SF6 (11), and PF6 (12)] as well as mononuclear complexes [Ag(R-pybox)2][X] [R-pybox = (S,S)-(i)Pr-pybox and X = SbF6 (6), PF6 (7), and BF4 (8); R-pybox = (3aS,3a'S,8aR,8a'R)-indane-pybox) and X = BF4 (9)] have been prepared by the reaction of the corresponding silver salts and pybox ligands using the appropriate molar ratio conditions. The first gold(I)/pybox complex [Au6Cl4{(S,S)-(i)Pr-pybox}4][AuCl2]2 (13) has been synthesized by the reaction of [AuCl{S(CH3)2}] and (S,S)-(i)Pr-pybox (1:1 molar ratio) in acetonitrile. The structures of the dinuclear (1, 4, 5, 10, and 11) and mononuclear (6 and 9) silver complexes and the hexanuclear gold complex 13 have been determined by single-crystal X-ray diffraction analysis.

Antitumor activity of new enantiopure pybox-ruthenium complexes.

New ruthenium complexes containing enantiopure 2,6-bis[4'(R)-phenyloxazolin-2'-il-pyridine] ((R,R)-Ph-pybox), 2,6-bis[4'(S)-isopropyloxazolin-2'-il-pyridine] ((S,S)-(i)Pr-pybox) or 2,6-bis[4'(R)-isopropyloxazolin-2'-il-pyridine] ((R,R)-(i)Pr-pybox) and water soluble 1,3,5-triaza-7-phosphaadamantane (PTA) or N-substituted PTA phosphanes have been synthesized in high yields and fully characterized. The interactions of these compounds with plasmidic DNA and their cytotoxic activity against the human cervical cancer HeLa cell line are reported, pointing out for the first time the different behaviour of ruthenium enantiomers affecting the cell cycle in HeLa tumor cells.

Asymmetric transfer hydrogenation of ketones catalyzed by enantiopure osmium(II) pybox complexes.

The complexes trans-[OsCl2(L){(S,S)-(i)Pr-pybox}] ((S,S)-(i)Pr-pybox = 2,6-bis[4'-(S)-isopropyloxazolin-2'-yl]pyridine, L = P(OMe)3 (1a), P(OEt)3 (2a), P(O(i)Pr)3 (3a), P(OPh)3 (4a), and cis-[OsCl2(L){(S,S)-(i)Pr-pybox}] (L = PPh3 (5a), P(i)Pr3 (6a), and PCy3 (7a)) have been synthesized from the complex trans-[OsCl2(η(2)-C2H4){(S,S)-(i)Pr-pybox}] via substitution of ethylene by phosphites and phosphines, respectively, under toluene reflux conditions. On the other hand, the synthesis of the complexes trans-[OsCl2(L){(R,R)-Ph-pybox}] (L = P(OMe)3 (1b) and cis-[OsCl2(L){(R,R)-Ph-pybox}] (L = PPh3 (5b), P(i)Pr3 (6b), and PCy3 (7b)) has been achieved from the complex trans-[OsCl2(η(2)-C2H4){(R,R)-Ph-pybox}] ((R,R)-Ph-pybox = 2,6-bis[4'-(R)-phenyloxazolin-2'-yl]pyridine under microwave irradiation. Complexes 1a-6a, 1b, 5b, and 6b have been assayed as catalysts for the asymmetric transfer hydrogenation (ATH) of ketones.

1,3-Dipolar cycloadditions of ruthenium(II) azido complexes with alkynes and nitriles.

The diazido complex [Na][Ru(N3)2{κ(3)(N,N,N)-Tpms}(PPh3)] (1) (Tpms = tris(pyrazolyl)methanesulfonate) has been synthesized, and its reactivity toward dipolarophiles has been investigated. Thus, the reaction of 1 with alkynes leads to complexes with one or two triazolate ligands depending on the alkyne and the reaction conditions. Complex 1 also reacts with nitriles.

Antitumor activity of new hydridotris(pyrazolyl)borate ruthenium(II) complexes containing the phosphanes PTA and 1-CH3-PTA.

The synthesis and full characterization of new half-sandwich ruthenium(II) complexes containing κ(3)(N,N,N)-hydridotris(pyrazolyl)borate (κ(3)(N,N,N)-Tp) and the water-soluble phosphanes 1,3,5-triaza-7-phosphatricyclo[3.3.1.

Synthesis of copper(I) complexes containing enantiopure pybox ligands. First assays on enantioselective synthesis of propargylamines catalyzed by isolated copper(I) complexes.

Dinuclear [Cu(2)(R-pybox)(2)][X](2) [X = PF(6), R-pybox = 2,6-bis[4'-(S)-isopropyloxazolin-2'-yl]pyridine (S,S)-(i)Pr-pybox (1), 2,6-bis[4'-(R)-phenyloxazolin-2'-yl]pyridine) (R,R)-Ph-pybox (2), 2,6-bis[4'-(S)-isopropyl-5',5'-difeniloxazolin-2'-yl]pyridine (S,S)-(i)Pr-pybox-diPh (3); X = OTf, (R,R)-Ph-pybox (4)] and mononuclear complexes [Cu(R-pybox)(2)][PF(6)] [R-pybox = (S,S)-(i)Pr-pybox (5), (R,R)-Ph-pybox (6)] have been diastereoselectively prepared by reaction of [Cu(MeCN)(4)][PF(6)] or CuOTf.0.5C(6)H(6) and the corresponding pybox ligand.

Facile modification of 1,3,5-triaza-7-phosphatricyclo[3.3.1.1(3,7)]decane phosphanes coordinated to ruthenium(II).

Hydridotris(pyrazolyl)borate (Tp) ruthenium (II) complexes containing new phosphane ligands are described. The new complexes were obtained by electrophilic attack to a coordinated 1,3,5-triaza-7-phosphatricyclo[3.3.

Tetra-, di-, and mononuclear copper(I) complexes containing (S,S)-iPr-pybox and (R,R)-Ph-pybox ligands.

Tetranuclear [Cu4I4{(S,S)-iPr-pybox}2] (1) and dinuclear [Cu2Cl-{(S,S)-iPr-pybox}2][CuCl2] (2) copper(I) complexes have been synthesized by reaction of iPr-pybox with CuI and CuCl, respectively. Furthermore, dinuclear [Cu2(R-pybox)2][PF6]2 [R-pybox = (R,R)-Ph-pybox (3), (S,S)-iPr-pybox (4)] and mononuclear complexes [Cu(R-pybox)2][PF6] [R-pybox = (R,R)-Ph-pybox (5), (S,S)-iPr-pybox (6)] have been prepared by reaction of [Cu(MeCN)4][PF6] and the corresponding pybox. The structures of complexes 1-3 have been determined by X-ray diffraction analyses.

New chiral ruthenium(II) catalysts containing 2,6-bis(4'-(R)-phenyloxazolin-2'-yl)pyridine (Ph-pybox) ligands for highly enantioselective transfer hydrogenation of ketones.

Treatment of complex trans-[RuCl(2)(eta(2)-C(2)H(4))[kappa(3)-N,N,N-(R,R)-Ph-pybox]] [(R,R)-Ph-pybox = 2,6-bis[4'-(R)-phenyloxazolin-2'-yl]pyridine] with phosphines or phosphites in dichloromethane at 50 degrees C leads to the formation of novel ruthenium(II)-pybox complexes trans-[RuCl(2)(L)[kappa(3)-N,N,N-(R,R)-Ph-pybox]] [L = PPh(3) (1 a), PPh(2)Me (2 a), PPh(2)(C(3)H(5)) (3 a), PPh(2)(C(4)H(7)) (4 a), PMe(3) (5 a), PiPr(3) (6 a), P(OMe)(3) (7 a) and P(OPh)(3) (8 a)]. Likewise, reaction of trans-[RuCl(2)(eta(2)-C(2)H(4))[kappa(3)-N,N,N-(R,R)-Ph-pybox]] with PPh(3) or PiPr(3) in refluxing methanol leads to the complexes cis-[RuCl(2)(L)(kappa(3)-N,N,N-(R,R)-Ph-pybox] [L = PPh(3) (1 b), PiPr(3) (6 b)]. No trans-cis isomerisation of complexes 1 a-8 a has been observed.

Unexpected coupling between an eta5-indenyl ligand and alkenyl-vinylidene fragments: synthesis of unprecedented (eta6-indene)ruthenium(II) metallacycles.

Vinylidene complexes [Ru[=C=C(H)CR1R2CH2C(Me)=CH2](eta5-C9H7)(PPh3)2][BF4] undergo an intramolecular coupling between the alkenyl-vinylidene fragment and the eta5-indenyl ligand to afford indene-metallacyclic compounds (6a,b) in which the resulting functionalised indene group is eta6-coordinated to the metal.

Rhodium(I) and Rhodium(III) complexes containing the chiral ligand 2,6-bis[4'(S)-isopropyloxazolin-2'-yl]pyridine (pybox): an unprecedented monohapto coordination of pybox.

The complex [Rh(kappa(3)-N,N,N-pybox)(CO)][PF(6)] (1) has been prepared by reaction of the precursor [Rh(mu-Cl)(eta(2)-C(2)H(4))(2)](2), 2,6-bis[4'(S)-isopropyloxazolin-2'-yl]pyridine (pybox), CO, and NaPF(6). Complex 1 reacts with monodentate phosphines to give the complexes [Rh(kappa(1)-N-pybox)(CO)(PR(3))(2)][PF(6)] (R(3) = MePh(2) (2), Me(2)Ph (3), (C(3)H(5))Ph(2) (4)), which show a previously unseen monodentate coordination of pybox. Complex 1 undergoes oxidative addition reactions with iodine and CH(3)I leading to the complexes [RhI(R)(kappa(3)-N,N,N-pybox)(CO)][PF(6)] (R = I (5); R = CH(3) (6)).

Stereochemically Controlled Synthesis of Ruthenium(II) Complexes Containing Bis(oxazolin-2'-yl)pyridine Ligands. X-ray Crystal Structures of trans-[RuCl(2)(PPh(3)){kappa(3)-N,N,N-(S,S)-(i)Pr-pybox}] and [RuCl(=C=C=CPh(2))(PPh(3)){kappa(3)-N,N,N-(S,S)-(i)Pr-pybox}][PF(6)] ((S,S)-(i)Pr-pybox= 2,6-Bis[4'-(S)-isopropyloxazolin-2'-yl]pyridine).

The treatment of achiral and chiral bis(oxazolin-2'-yl)pyridine (pybox) complexes trans-[RuCl(2)(eta(2)-H(2)C=CH(2))(k(3)-N,N,N-pybox)] [pybox= 2,6-bis(dihydrooxazolin-2'-yl)pyridine] (1a) and [RuCl(2)(eta(2)-H(2)C=CH(2))(k(3)-N,N,N-(SS)-(i)Pr-pybox}] [(SS)-(i)Pr-pybox= 2,6-bis[4'-(S)-isopropyloxazolin-2'-yl]pyridine] (1b) with an excess of triphenylphosphine in dichloromethane at 50 degrees C leads to the formation of the first ruthenium(II) derivatives containing both bis(oxazolin-2'-yl)pyridine and phosphine ligands trans-[RuCl(2)(PPh(3))(kappa(3)-N,N,N-pybox)] (2a) and trans-[RuCl(2)(PPh(3)){kappa(3)-N,N,N-(SS)-(i)Pr-pybox}] (2b). Chiral complex 2b slowly isomerizes in acetone at 50 degrees C to generate cis-[RuCl(2)(PPh(3)){kappa(3)-N,N,N-(SS)-(i)Pr-pybox}] (3). Complex 3 can be also obtained from the reaction of 1b with PPh(3) in MeOH.