73323-68-9Relevant articles and documents
Highly Regio- and Enantioselective Hydroformylation of Vinyl Esters Using Bidentate Phosphine,P-Chiral Phosphorodiamidite Ligands
Schmitz, Christian,Holthusen, Katharina,Leitner, Walter,Franciò, Giancarlo
, p. 1584 - 1589 (2016/03/15)
Hybrid bidentate phosphine-phosphorodiamidite ligands based on a chiral Betti base backbone and diphenylphosphinoaniline derivatives have been prepared (BettiPhos). The ligands possess a stereogenic P atom at the phosphorodiamidite moiety, whose configuration can be largely controlled by the synthetic route and the choice of base and solvent. The new ligands were applied in the rhodium-catalyzed asymmetric hydroformylation (AHF) of vinyl esters and vinyl amides. Very high enantioselectivities of up to 97% ee accompanied by excellent regioselectivities (up to b/l > 1000) were obtained using the BettiPhos ligand (SC,SC,RP,SC)-4b bearing an additional chiral group at the aniline nitrogen. The catalyst resting state [RhH(CO)2{(SC,SC,RP,SC)-4b}] was investigated by high pressure-NMR studies, revealing an equatorial-apical coordination of the bidentate ligand where the two phosphorus donors rapidly exchange their positions through an intermediate with the ligand bound via the phosphine group only.
A lysine conserved in the monoamine oxidase family is involved in oxidation of the reduced flavin in mouse polyamine oxidase
Henderson Pozzi, Michelle,Fitzpatrick, Paul F.
experimental part, p. 83 - 88 (2011/10/09)
Lysine 315 of mouse polyamine amine oxidase corresponds to a lysine residue that is conserved in the flavoprotein amine oxidases of the monoamine oxidase structural family. In several structures, this lysine residue forms a hydrogen bond to a water molecule that is hydrogen-bonded to the flavin N(5). Mutation of Lys315 in polyamine oxidase to methionine was previously shown to have no effect on the kinetics of the reductive half-reaction of the enzyme (M. Henderson Pozzi, V. Gawandi, P.F. Fitzpatrick, Biochemistry 48 (2009) 1508-1516). In contrast, the mutation does affect steps in the oxidative half-reaction. The kcat value is unaffected by the mutation; this kinetic parameter likely reflects product release. At pH 10, the kcat/Km value for oxygen is 25-fold lower in the mutant enzyme. The kcat/KO2 value is pH-dependent for the wild-type enzyme, decreasing below a pKa of 7.0, while this kinetic parameter for the mutant enzyme is pH-independent. This is consistent with the neutral form of Lys315 being required for more rapid flavin oxidation. The solvent isotope effect on the kcat/KO2 value increases from 1.4 in the wild-type enzyme to 1.9 in the mutant protein, and the solvent inventory changes from linear to bowed. The effects of the mutation can be explained by the lysine orienting the bridging water so that it can accept the proton from the flavin N(5) during flavin oxidation. In the mutant enzyme the lysine amine would be replaced by a water chain.
Synthese von Acylpolyaminen: Acetylspermidine und C12:0-Acarnidin
Boukouvalas, John,Golding, Bernard T.,McCabe, Richard W.,Slaich, Pritpal K.
, p. 646 - 647 (2007/10/02)
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