464-49-3Relevant articles and documents
Molybdenum(0)-Catalyzed Reductive Dehalogenation of α-Halo Ketones with Phenylsilane
Perez, Daniel,Greenspoon, Noam,Keinan, Ehud
, p. 5570 - 5574 (1987)
Reductive dehalogenation of α-halo ketones and esters is effectively achieved by using a novel reducing system comprised of phenylsilane and catalytic amounts of molybdenum hexacarbonyl and triphenylphosphine.Reactions are carried out at 60-80 deg C in variety of solvents, including THF, benzene, toluene, and diglyme.With respect to α-halo carbonyl reduction, this combination of Mo(0) and phenylsilane is superior to our previously described palladium (0)/diphenylsilane system and produces higher yields and cleaner products.
Zwitterion-induced organic-metal hybrid catalysis in aerobic oxidation
Hu, Rong-Bin,Lam, Ying-Pong,Ng, Wing-Hin,Wong, Chun-Yuen,Yeung, Ying-Yeung
, p. 3498 - 3506 (2021/04/07)
In many metal catalyses, the traditional strategy of removing chloride ions is to add silver salts via anion exchange to obtain highly active catalysts. Herein, we reported an alternative strategy of removing chloride anions from ruthenium trichloride using an organic [P+-N-] zwitterionic compound via multiple hydrogen bond interactions. The resultant organic-metal hybrid catalytic system has successfully been applied to the aerobic oxidation of alcohols, tetrahydroquinolines, and indolines under mild conditions. The performance of zwitterion is far superior to that of many other common Lewis bases or Br?nsted bases. Mechanistic studies revealed that the zwitterion triggers the dissociation of chloride from ruthenium trichloride via nonclassical hydrogen bond interaction. Preliminary studies show that the zwitterion is applicable to catalytic transfer semi-hydrogenation.
Borneol dehydrogenase from Pseudomonas sp. TCU-HL1 possesses novel quinuclidinone reductase activities
Chen, Hao-Ping,Ho, Tsung-Jung,Hung, Chien-Chi,Khine, Aye Aye,Lu, Pei-Chieh,Simaremare, Sailent Rizki Sari,Tung, Chi-Hua,Wu, Jia-Ru,Yiin, Lin-Ming
, (2021/08/30)
Borneol dehydrogenase (BDH) catalyses the last step of the camphor biosynthetic pathway in plants and the first reaction in the borneol degradation pathway in soil microorganisms. Native or engineered BDH can be used to produce optically pure borneol and camphor. The recently reported apo-form crystal structure of BDH (PDB ID: 6M5N) from Pseudomonas sp. TCU-HL1 superimposes well with that of 3-quinuclidinone reductase (QR) (PDB ID: 3AK4) from Agrobacterium tumefaciens. QR catalyses the conversion of 3-quinuclidinone into (R)-3-(?)-quinuclidinol, an important chiral synthone for several drugs. However, the kinetic parameter, kcat, of QR was not determined in the previous reports even though both BDH and QR have various potential industrial applications. Here, we aimed to further characterise their structural and functional relationship. Recombinant QR with the native sequence was cloned, expressed in E. coli, and purified. We found that 3-quinuclidinone can be used as an alternative substrate for BDH. Only (R)-3-(?)-quinuclidinol was detected in this BDH-catalysed reaction. The results of 3 D molecular docking simulation show that 3-quinuclidinone and (+)-/(-)- borneol were docked to two different parts of the QR active site. In contrast, all three compounds are docked uniformly to the alpha-1 helix of BDH. There results explain why BDH can turnover 3-quinuclidinone, while QR can not act on (+)-/(-)-borneol.
carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
D?ring, Manuel,Sieber, Volker,Simon, Robert C.,Tafertshofer, Georg,Zachos, Ioannis
supporting information, p. 14701 - 14706 (2021/05/13)
Here we report a new robust nicotinamide dinucleotide phosphate cofactor analog (carba-NADP+) and its acceptance by many enzymes in the class of oxidoreductases. Replacing one ribose oxygen with a methylene group of the natural NADP+ was found to enhance stability dramatically. Decomposition experiments at moderate and high temperatures with the cofactors showed a drastic increase in half-life time at elevated temperatures since it significantly disfavors hydrolysis of the pyridinium-N?glycoside bond. Overall, more than 27 different oxidoreductases were successfully tested, and a thorough analytical characterization and comparison is given. The cofactor carba-NADP+ opens up the field of redox-biocatalysis under harsh conditions.