Pingsong Wu - Academia.edu (original) (raw)

Papers by Pingsong Wu

Research paper thumbnail of Glycine-and Sarcosine-Based Models of Vanadate-Dependent Haloperoxidases in Sulfoxygenation Reactions

Reaction of R-styreneoxide with glycine-tert-butylester yielded amino alcohols of the general for... more Reaction of R-styreneoxide with glycine-tert-butylester yielded amino alcohols of the general formula NR 1 R 2 R 3 , where R 1 ) CH 2 COOtBu and R 2 ) R 3 ) 2-phenyl-2-hydroxyethyl (H 2 L A ); R 2 ) 2-phenyl-2-hydroxyethyl and R 3 ) 1-phenyl-2-hydroxyethyl (H 2 L B ); R 2 ) H and R 3 ) 2-phenyl-2-hydroxyethyl (HL C ); and R 2 ) H and R 3 ) 1-phenyl-2-hydroxyethyl (HL D ). The corresponding reaction with sarcosine-tert-butylester and subsequent hydrolysis provided the zwitterion + NH(CH 3 ){CH 2 CHPh(OH)}(CH 2 CO 2 -), HL E / (asterisk refers to unprotected carboxylate).

Research paper thumbnail of Glycine and Sarcosine-Based Models of Vanadate-Dependent Haloperoxidases in Sulfoxygenation Reactions

Inorganic Chemistry, 2007

Reaction of R-styreneoxide with glycine-tert-butylester yielded amino alcohols of the general for... more Reaction of R-styreneoxide with glycine-tert-butylester yielded amino alcohols of the general formula NR1R2R3, where R1 = CH2COOtBu and R2 = R3 = 2-phenyl-2-hydroxyethyl (H2LA); R2 = 2-phenyl-2-hydroxyethyl and R3 = 1-phenyl-2-hydroxyethyl (H2LB); R2 = H and R3 = 2-phenyl-2-hydroxyethyl (HLC); and R2 = H and R3 = 1-phenyl-2-hydroxyethyl (HLD). The corresponding reaction with sarcosine-tert-butylester and subsequent hydrolysis provided the zwitterion +NH(CH3){CH2CHPh(OH)}(CH2CO2-), HLE* (asterisk refers to unprotected carboxylate). Reaction of these ligands with VO(OiPr)3 in CH2Cl2 gave the oxovanadium(V) complexes [VOL(OiPr)2] and [VOL2(OiPr)] (for LC and LD) or, when reacted in the presence of MeOH, [VOL'(OMe)], where L' represents the methyl ester of LA, LB, and LE. The crystal and molecular structures of R-HLC, S-HLD, R,S-HLE* x H2O, and lambda-[VO(R,S-LB')OMe] have been determined. The complex [VOLB'(OMe)] contains vanadium in a distorted trigonal-bipyramidal array (tau = 0.72), the oxo group in the equatorial plane, and methoxide and N in the apical positions, and thus, it structurally models the active center of vanadate-dependent haloperoxidases. The structure and the bonding parameters, including a particularly long d(V-N) of 2.562 A, are backed up by DFT calculations. The isolated oxovanadium(V) complexes and the in situ systems L + VO(OiPr)3 catalyze the oxidation, by cumylhydroperoxide HO2R', of prochiral sulfides (MeSPh, MeSp-Tol, PhSBn) to chiral sulfoxides plus some sulfone. The best results with respect to enantioselectivity (enantiomeric excess (ee) = 38%) were obtained with the system VO(OiPr)3/LA, and the best selectivity with respect to sulfoxide (100%) was obtained with [VOLA(OiPr)]. The reaction with the hexacoordinated [VO(OMe)(HOMe)LD*] was very slow. Oxidation of PhSBn is faster than that of MeSPh and MeSpTol. Turn-over numbers are up to 60 mol of sulfoxide mol-1 of catalyst h-1 (-20 degrees C). The unspectacular ee apparently is a consequence of flexibility of the active catalyst in solution, as shown by the 51V NMR of the catalysts [VOL(OR)] and the oxo-peroxo intermediates [VOL(O2R')]. As shown by DFT calculations, the peroxo ligand coordinates in the tilted end-on fashion in the axial or equatorial position (energy difference = 17.6 kJ/mol).

Research paper thumbnail of Sulfoxygenation Catalysed by Oxidovanadium Complexes

European Journal of Inorganic Chemistry, 2008

Model complexes of vanadate-dependent peroxidases, viz. oxidovanadium(V) complexes of the general... more Model complexes of vanadate-dependent peroxidases, viz. oxidovanadium(V) complexes of the general composition [VO(Hn–xL)], have been prepared and characterised. HnL is an n-basic di- or trichiral aminodiethanol [HOCH(Ph)CH2]2NR, with R = N-methylimidazolyl (H2LA), tris(hydroxymethyl)methyl (H5LB, 2 isomers), 2,3-dihydroxypropyl (H4LC, 2 isomers) and 2-hydroxy-3-trityloxypropyl (H3LD). These ligands form the complexes [VO(OH)(LA)], [VO(H2LB)], trigonal-bipyramidal [VO(HLC)]tbp and octahedral Λ-[VO(HLC)]oct. The ligands R,R,S-H4LC and R,R,R-H3LD, and the complexes Λ-[VO(R,R,S-HLC)]oct and [VO(R,R,S-HLC)]tbp have been characterised by X-ray structure analysis. The complexes [VO(H2LB)] and [VO(HLC)] were immobilised on Merrifield and Barlos resin by anchoring through a free alcoholic group in the ligand side-chain R. {[VO(H2O)LE]}, an oxidovanadium(IV) complex tethered to Merrifield resin, was prepared by treating [VO(acac)2] with {HLE}, the immobilised Schiff base ligand obtained by condensation of salicylaldehyde with resin-anchored lysine. The complexes and in situ systems ([VO(OiPr)3] + ligand) as well as the immobilised complexes were investigated for their catalytic activity in the oxygenation, by cumyl hydroperoxide, of thioanisol to its sulfoxide. All of the systems were active, with a selectivity (sulfoxide vs. sulfone) of 95–98 %. Satisfactory turnover rates and a chiral induction up to 37 % ee were observed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Research paper thumbnail of Modelling the Sulfoxygenation Activity of Vanadate-Dependent Peroxidases

Chemistry & Biodiversity, 2008

Vanadate-dependent peroxidases contain, in their active center, vanadate covalently attached to h... more Vanadate-dependent peroxidases contain, in their active center, vanadate covalently attached to histidine in an overall trigonal-bipyramidal array. We describe here the synthesis and characterization of optically active amino alcohols and their vanadium(V) complexes, and we show that the structural models of the active center thus obtained are also functional models for the sulfide-peroxidase activity of the enzyme in heterogeneous catalysis. The heterogeneous systems were obtained by immobilizing the complexes on silica gel and mesoporous silicas, and by aggregation. The following ligands, ligand precursors, and V compounds have been structurally characterized: (R)-(2-phenylethanol)-(R)-1-phenylethylamine (HLA), (R,R)-bis[2-phenyl(ethylmethylether)]ammonium chloride ([LD]+Cl−), the carbasilatranes (R,R)-methoxy{N,N′,N″-2,2′,3-[bis(1-phenylethanolato)propyl]amino}silane ((R,R)-Si(OMe)LE), (R,R)-methoxy-{N,N′,N″-1,2′,3-[(1-phenylethanolato)-(2-phenylethanolato)propyl]amino}silane ((R,R)-Si(OMe)LE′), and [VO(LF)(OSiMe2tBu)], where H2LF=ethylbis(2-hydroxy-2-phenylethyl)amine.

[Research paper thumbnail of Sulfoxygenation Catalysed by Oxidovanadium Complexes Cem Çelik, [a] Jérome Dallery, [a](https://attachments.academia-assets.com/32937959/thumbnails/1.jpg)

Keywords: Oxidovanadium complexes / Ethanolamines / Sulfoxygenation / Models of peroxidases / Van... more Keywords: Oxidovanadium complexes / Ethanolamines / Sulfoxygenation / Models of peroxidases / Vanadate-dependent peroxidase Model complexes of vanadate-dependent peroxidases, viz. oxidovanadium(V) complexes of the general composition [VO(H n-x L)], have been prepared and characterised. H n L is an n-basic di-or trichiral aminodiethanol [HOCH(Ph)-CH 2 ] 2 NR, with R = N-methylimidazolyl (H 2 L A ), tris(hydroxymethyl)methyl (H 5 L B , 2 isomers), 2,3-dihydroxypropyl (H 4 L C , 2 isomers) and 2-hydroxy-3-trityloxypropyl (H 3 L D ). These ligands form the complexes [VO(OH)(L A )], [VO(H 2 L B )], trigonal-bipyramidal [VO(HL C )] tbp and octahedral Λ-[VO-(HL C )] oct . The ligands R,R,S-H 4 L C and R,R,R-H 3 L D , and the complexes Λ-[VO(R,R,S-HL C )] oct and [VO(R,R,S-HL C )] tbp have been characterised by X-ray structure analysis. The complexes [VO(H 2 L B )] and [VO(HL C )] were immobilised on Merrifield and Barlos resin by anchoring through a free al-

Research paper thumbnail of Glycine-and Sarcosine-Based Models of Vanadate-Dependent Haloperoxidases in Sulfoxygenation Reactions

Reaction of R-styreneoxide with glycine-tert-butylester yielded amino alcohols of the general for... more Reaction of R-styreneoxide with glycine-tert-butylester yielded amino alcohols of the general formula NR 1 R 2 R 3 , where R 1 ) CH 2 COOtBu and R 2 ) R 3 ) 2-phenyl-2-hydroxyethyl (H 2 L A ); R 2 ) 2-phenyl-2-hydroxyethyl and R 3 ) 1-phenyl-2-hydroxyethyl (H 2 L B ); R 2 ) H and R 3 ) 2-phenyl-2-hydroxyethyl (HL C ); and R 2 ) H and R 3 ) 1-phenyl-2-hydroxyethyl (HL D ). The corresponding reaction with sarcosine-tert-butylester and subsequent hydrolysis provided the zwitterion + NH(CH 3 ){CH 2 CHPh(OH)}(CH 2 CO 2 -), HL E / (asterisk refers to unprotected carboxylate).

Research paper thumbnail of Glycine and Sarcosine-Based Models of Vanadate-Dependent Haloperoxidases in Sulfoxygenation Reactions

Inorganic Chemistry, 2007

Reaction of R-styreneoxide with glycine-tert-butylester yielded amino alcohols of the general for... more Reaction of R-styreneoxide with glycine-tert-butylester yielded amino alcohols of the general formula NR1R2R3, where R1 = CH2COOtBu and R2 = R3 = 2-phenyl-2-hydroxyethyl (H2LA); R2 = 2-phenyl-2-hydroxyethyl and R3 = 1-phenyl-2-hydroxyethyl (H2LB); R2 = H and R3 = 2-phenyl-2-hydroxyethyl (HLC); and R2 = H and R3 = 1-phenyl-2-hydroxyethyl (HLD). The corresponding reaction with sarcosine-tert-butylester and subsequent hydrolysis provided the zwitterion +NH(CH3){CH2CHPh(OH)}(CH2CO2-), HLE* (asterisk refers to unprotected carboxylate). Reaction of these ligands with VO(OiPr)3 in CH2Cl2 gave the oxovanadium(V) complexes [VOL(OiPr)2] and [VOL2(OiPr)] (for LC and LD) or, when reacted in the presence of MeOH, [VOL'(OMe)], where L' represents the methyl ester of LA, LB, and LE. The crystal and molecular structures of R-HLC, S-HLD, R,S-HLE* x H2O, and lambda-[VO(R,S-LB')OMe] have been determined. The complex [VOLB'(OMe)] contains vanadium in a distorted trigonal-bipyramidal array (tau = 0.72), the oxo group in the equatorial plane, and methoxide and N in the apical positions, and thus, it structurally models the active center of vanadate-dependent haloperoxidases. The structure and the bonding parameters, including a particularly long d(V-N) of 2.562 A, are backed up by DFT calculations. The isolated oxovanadium(V) complexes and the in situ systems L + VO(OiPr)3 catalyze the oxidation, by cumylhydroperoxide HO2R', of prochiral sulfides (MeSPh, MeSp-Tol, PhSBn) to chiral sulfoxides plus some sulfone. The best results with respect to enantioselectivity (enantiomeric excess (ee) = 38%) were obtained with the system VO(OiPr)3/LA, and the best selectivity with respect to sulfoxide (100%) was obtained with [VOLA(OiPr)]. The reaction with the hexacoordinated [VO(OMe)(HOMe)LD*] was very slow. Oxidation of PhSBn is faster than that of MeSPh and MeSpTol. Turn-over numbers are up to 60 mol of sulfoxide mol-1 of catalyst h-1 (-20 degrees C). The unspectacular ee apparently is a consequence of flexibility of the active catalyst in solution, as shown by the 51V NMR of the catalysts [VOL(OR)] and the oxo-peroxo intermediates [VOL(O2R')]. As shown by DFT calculations, the peroxo ligand coordinates in the tilted end-on fashion in the axial or equatorial position (energy difference = 17.6 kJ/mol).

Research paper thumbnail of Sulfoxygenation Catalysed by Oxidovanadium Complexes

European Journal of Inorganic Chemistry, 2008

Model complexes of vanadate-dependent peroxidases, viz. oxidovanadium(V) complexes of the general... more Model complexes of vanadate-dependent peroxidases, viz. oxidovanadium(V) complexes of the general composition [VO(Hn–xL)], have been prepared and characterised. HnL is an n-basic di- or trichiral aminodiethanol [HOCH(Ph)CH2]2NR, with R = N-methylimidazolyl (H2LA), tris(hydroxymethyl)methyl (H5LB, 2 isomers), 2,3-dihydroxypropyl (H4LC, 2 isomers) and 2-hydroxy-3-trityloxypropyl (H3LD). These ligands form the complexes [VO(OH)(LA)], [VO(H2LB)], trigonal-bipyramidal [VO(HLC)]tbp and octahedral Λ-[VO(HLC)]oct. The ligands R,R,S-H4LC and R,R,R-H3LD, and the complexes Λ-[VO(R,R,S-HLC)]oct and [VO(R,R,S-HLC)]tbp have been characterised by X-ray structure analysis. The complexes [VO(H2LB)] and [VO(HLC)] were immobilised on Merrifield and Barlos resin by anchoring through a free alcoholic group in the ligand side-chain R. {[VO(H2O)LE]}, an oxidovanadium(IV) complex tethered to Merrifield resin, was prepared by treating [VO(acac)2] with {HLE}, the immobilised Schiff base ligand obtained by condensation of salicylaldehyde with resin-anchored lysine. The complexes and in situ systems ([VO(OiPr)3] + ligand) as well as the immobilised complexes were investigated for their catalytic activity in the oxygenation, by cumyl hydroperoxide, of thioanisol to its sulfoxide. All of the systems were active, with a selectivity (sulfoxide vs. sulfone) of 95–98 %. Satisfactory turnover rates and a chiral induction up to 37 % ee were observed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Research paper thumbnail of Modelling the Sulfoxygenation Activity of Vanadate-Dependent Peroxidases

Chemistry & Biodiversity, 2008

Vanadate-dependent peroxidases contain, in their active center, vanadate covalently attached to h... more Vanadate-dependent peroxidases contain, in their active center, vanadate covalently attached to histidine in an overall trigonal-bipyramidal array. We describe here the synthesis and characterization of optically active amino alcohols and their vanadium(V) complexes, and we show that the structural models of the active center thus obtained are also functional models for the sulfide-peroxidase activity of the enzyme in heterogeneous catalysis. The heterogeneous systems were obtained by immobilizing the complexes on silica gel and mesoporous silicas, and by aggregation. The following ligands, ligand precursors, and V compounds have been structurally characterized: (R)-(2-phenylethanol)-(R)-1-phenylethylamine (HLA), (R,R)-bis[2-phenyl(ethylmethylether)]ammonium chloride ([LD]+Cl−), the carbasilatranes (R,R)-methoxy{N,N′,N″-2,2′,3-[bis(1-phenylethanolato)propyl]amino}silane ((R,R)-Si(OMe)LE), (R,R)-methoxy-{N,N′,N″-1,2′,3-[(1-phenylethanolato)-(2-phenylethanolato)propyl]amino}silane ((R,R)-Si(OMe)LE′), and [VO(LF)(OSiMe2tBu)], where H2LF=ethylbis(2-hydroxy-2-phenylethyl)amine.

[Research paper thumbnail of Sulfoxygenation Catalysed by Oxidovanadium Complexes Cem Çelik, [a] Jérome Dallery, [a](https://attachments.academia-assets.com/32937959/thumbnails/1.jpg)

Keywords: Oxidovanadium complexes / Ethanolamines / Sulfoxygenation / Models of peroxidases / Van... more Keywords: Oxidovanadium complexes / Ethanolamines / Sulfoxygenation / Models of peroxidases / Vanadate-dependent peroxidase Model complexes of vanadate-dependent peroxidases, viz. oxidovanadium(V) complexes of the general composition [VO(H n-x L)], have been prepared and characterised. H n L is an n-basic di-or trichiral aminodiethanol [HOCH(Ph)-CH 2 ] 2 NR, with R = N-methylimidazolyl (H 2 L A ), tris(hydroxymethyl)methyl (H 5 L B , 2 isomers), 2,3-dihydroxypropyl (H 4 L C , 2 isomers) and 2-hydroxy-3-trityloxypropyl (H 3 L D ). These ligands form the complexes [VO(OH)(L A )], [VO(H 2 L B )], trigonal-bipyramidal [VO(HL C )] tbp and octahedral Λ-[VO-(HL C )] oct . The ligands R,R,S-H 4 L C and R,R,R-H 3 L D , and the complexes Λ-[VO(R,R,S-HL C )] oct and [VO(R,R,S-HL C )] tbp have been characterised by X-ray structure analysis. The complexes [VO(H 2 L B )] and [VO(HL C )] were immobilised on Merrifield and Barlos resin by anchoring through a free al-