RESUMO
A new family of chiral ferrocenyl P,S-ligands has been developed and successfully applied in a highly endo-selective catalytic asymmetric cycloaddition of azomethine ylides with various enones, including cyclic and acyclic α-enones. For cyclic α-enones, a [Cu(CH(3)CN)(4)]ClO(4)/(R(c),S(Fc))-2f complex catalyzed the cycloaddition to give the sole endo-cycloadducts in perfect enantioselectivities (normally 99% ee), while an AgOAc/(R(c),S(Fc))-2f catalytic system exhibited good endo/exo selectivities (endo/exo = 91/9 to 96/4) and high enantiocontrol (up to 98% ee) for acyclic α-enones.
Assuntos
Compostos Azo/química , Fósforo/química , Enxofre/química , Tiossemicarbazonas/química , Catálise , Ciclização , Ligantes , Estrutura Molecular , EstereoisomerismoRESUMO
An enantioselective synthesis of chiral alkylphosphonates bearing a beta-stereogenic center, based on the Rh-catalyzed asymmetric hydrogenation of corresponding beta-substituted beta,gamma-unsaturated phosphonates with a ferrocene-based monophosphoramidite ligand under the mild hydrogenation conditions, was developed, in which an ee value of up to 98% was obtained.
Assuntos
Amidas/química , Organofosfonatos/química , Ácidos Fosfóricos/química , Ródio/química , Catálise , Compostos Ferrosos/química , Hidrogenação , Ligantes , Metalocenos , EstereoisomerismoRESUMO
A new class of chiral ferrocenyl diphosphine ligands with an imidazole ring, (R(c),S(Fc))-ImiFerroPhos, has been prepared from acylferrocenes through a five-step transformation and successfully applied in the Rh-catalyzed asymmetric hydrogenation of various 3-aryl-substituted 2-phosphonomethylpropenoates, in which a series of chiral 3-phosphono-2-arylmethylpropanoic acid derivatives were achieved in ee values of up to 98%.
Assuntos
Imidazóis/química , Organofosfonatos/síntese química , Ródio/química , Catálise , Cristalografia por Raios X , Hidrogenação , Ligantes , Organofosfonatos/química , EstereoisomerismoRESUMO
An enantioselective synthesis of optically active 1-aryl or 1-alkyl substituted ethylphosphonates, based on the first Rh-catalyzed asymmetric hydrogenation of corresponding alpha,beta-unsaturated precursors with a P-stereogenic BoPhoz-type ligand under the mild condition, was developed, in which a wide range of 1-aryl or 1-alkyl substituted ethylphosphonates were achieved in up to 98% ee.
Assuntos
Organofosfonatos/síntese química , Compostos Organofosforados/síntese química , Catálise , Hidrogenação , Ligantes , Ródio , EstereoisomerismoRESUMO
A series of chiral beta-aryl-substituted gamma-amino butyric acid derivatives were synthesized in good enantioselectivities via the Cu-catalyzed asymmetric conjugate reduction of gamma-phthalimido-alpha,beta-unsaturated carboxylic acid esters using Cu(OAc)2 x H2O as a catalyst precursor, (S)-BINAP as a ligand, PMHS as a hydride source, and t-BuOH as an additive. The methodology has been applied successfully to the enantioselective synthesis of a chiral pharmaceutical, (R)-baclofen.
Assuntos
Aminoácidos/síntese química , Ácidos Carboxílicos/química , Cobre/química , Ésteres/química , Iminoácidos/química , Ftalimidas/química , Aminoácidos/química , Catálise , Ligantes , Estrutura Molecular , Oxirredução , EstereoisomerismoRESUMO
A new class of unsymmetrical hybrid phosphine--aminophosphine ligands has been prepared from commercially available, inexpensive (S)-1-phenylethylamine through a concise synthetic procedure. These ligands are not very sensitive to air and moisture, and displayed good enantioselectivities in the Rh-catalyzed asymmetric hydrogenation of various dimethyl alpha-benzoyloxyethenephosphonates bearing beta-aryl, beta-alkyl, and beta-alkoxy substituents and N-benzyloxycarbonyl alpha-enamido phosphonates, in which up to 97% ee was obtained. A side-by-side comparison study disclosed that these new phosphine--aminophosphine ligands showed better enantioselectivity than BoPhoz ligands.
RESUMO
A series of BoPhoz-type ligands were successfully applied in the rhodium-catalyzed asymmetric hydrogenation of a number of beta-substituted or unsubstituted alpha-(phthalimidomethyl)acrylates, affording good to excellent enantioselectivities. The results suggested that the presence of an N-H proton in the BoPhoz backbone could significantly improve the enantioselectivity, and ligand (Sc,Rp)-1d, bearing two CF3-groups in the 3,5-position of the phenyl ring of aminophosphino moiety, showed the highest enantioselectivity.
Assuntos
Aminoácidos/síntese química , Organofosfonatos/química , Ródio/química , Aminoácidos/química , Ligantes , Espectroscopia de Ressonância Magnética , Espectrometria de Massas por Ionização por Electrospray , EstereoisomerismoRESUMO
A series of chiral beta-aryl-gamma-amino acid ester derivatives were synthesized in high enantioselectivities (93-97% ee) via the Rh-catalyzed asymmetric hydrogenation of gamma-phthalimido-alpha,beta-unsaturated carboxylic acid esters using highly modular chiral BoPhoz-type phosphine-aminophosphine ligands. The method has been applied successfully to the synthesis of several chiral pharmaceuticals including (R)-baclofen and (R)-rolipram with high enantioselectivities.
Assuntos
Aminoácidos/síntese química , Ésteres/química , Ródio/química , Aminoácidos/química , Baclofeno/síntese química , Baclofeno/química , Catálise , Hidrogenação , Ligantes , Estrutura Molecular , Rolipram/síntese química , Rolipram/química , EstereoisomerismoRESUMO
A new family of air- and moisture-stable phosphine-phosphoramidite ligands (PEAPhos) has been prepared from commercially available and inexpensive (S)-alpha-phenylethylamine through a two- or three-step transformation and successfully applied in the rhodium-catalyzed enantioselective hydrogenations of a variety of substrates, in which up to 99.9% ee was obtained for all of these kinds of substrates.
RESUMO
The title compound, [Dy2(C8H7O2)6(C12H8N2)2], forms binuclear complexes, viz. di-mu-4-methylbenzoato-kappa4O:O'-bis[bis(4-methylbenzoato-kappa2O,O')(1,10-phenanthroline-kappa2N,N')dysprosium(III)] tetra-mu-4-methylbenzoato-kappa8O:O'-bis[(4-methylbenzoato-kappa2O,O')(1,10-phenanthroline-kappa2N,N')dysprosium(III)]. There are two independent binuclear complexes in the asymmetric unit, both of which are centrosymmetric. In one, the Dy(III) ions are linked by two bridging 4-methylbenzoate groups, while in the other, the Dy(III) ions are linked by four bridging 4-methylbenzoate groups. The remaining 4-methylbenzoate groups and 1,10-phenanthroline units coordinate to just one metal ion in bidentate modes.
RESUMO
The aim of this research is to prepare high quality polyclonal antibodies against Ecp, a recently identified leucine-zipper protein. The full length cDNA of ecp was amplified by PCR, cloned into pGEX-4T-1(His)6 and transformed into E. coli DH 5alpha. After induction with IPTG, the GST-Ecp fusion protein from the lysate was bound to glutathione-Sepharose 4B and digested with thrombin. The released Ecp protein was further purified through Ni-NTA affinity chromatography to homogeneity. A rabbit was immunized with the purified Ecp, and the antibody generated against Ecp was purified by affinity chromatography. The results of the Western blot showed that Ecp is present in various development stages of Drosophila melanogaster, from larvae to adult.