19132-06-0Relevant articles and documents
Mechanisms of formation of stereoisomers of 2,3-butanediol during microbial fermentation of sugars.
TAYLOR,JUNI
, p. 1389 - 1390 (1958)
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Effect of Methyl Substitution on Conformation and Molecular Arrangement of BEDT-TTF Derivatives in the Crystalline Environment
Matsumiya, Shigeki,Izuoka, Akira,Sugawara, Tadashi,Taruishi, Tomohiro,Kawada, Yuzo
, p. 513 - 522 (1993)
Two methylated bis(ethylenedithio)tetrathiafulvalene (ET) derivatives, Me2ET and Me4ET were stereoselectively synthesized to examine the effect of methylation on conformations of dihydrodithiin rings and molecular arrangements in the crystalline state.Since the donating ability of Me2ET and Me4ET are similar to that of ET, the methylated ET derivatives are considered to be appropriate to investigate the "lattice pressure" effect on ET radical salts by changing the volume of donor molecules.The upper limit of an activation energy for the ring inversion of the dimethylated dihydrodithiin in solution was estimated to be 32 kJ mol-1 by 13C NMR spectroscopy.The X-ray structure analyses revealed that orientations of methyl groups are fixed to axial in Me2ET and to equatorial in Me4ET, accompanied by the change of molecular stacking.The "volume of a methyl group" was evaluated by comparing the molecular volumes of Me2ET and Me4ET with that of ET, and the effective volume for the axial methyl group turns out to be 15percent larger than that of the equatorial.The solid state 13C NMR (CP/MAS) spectra of ET and its derivatives showed that the chemical shifts of resonance lines reflect the conformations of dihydrodithiin rings in crystals.
An improved synthesis of chiral diols via the asymmetric catalytic hydrogenation of prochiral diones
Fan, Qing-Hua,Yeung, Chi-Hung,Chan, Albert S. C.
, p. 4041 - 4045 (1997)
The rates of the asymmetric hydrogenation of prochiral diketones catalyzed by Ru(BINAP) catalysts were substantially accelerated in the presence of small amounts of a strong acid.
Highly efficient and recyclable chiral Pt nanoparticle catalyst for enantioselective hydrogenation of activated ketones
Xue, Xiuru,Chen, Pu,Xu, Peng,Wang, Yanhua
, p. 55 - 58 (2018/03/22)
Thermoregulated phase-separable chiral Pt nanoparticle catalyst exhibited excellent ee (>99%) in the enantioselective hydrogenation of activated ketones for preparing chiral α-hydroxy acetals and chiral 1,2-diols. More importantly, the chiral catalyst could be easily separated by phase separation and directly reused in the next cycle without any loss in catalytic activity and enantioselectivity, even in the gram-scale reaction. The leaching of Pt was under the detection limit of the instrument.
Biocatalytic production of alpha-hydroxy ketones and vicinal diols by yeast and human aldo-keto reductases
Calam, Eduard,Porté, Sergio,Fernández, M. Rosario,Farrés, Jaume,Parés, Xavier,Biosca, Josep A.
, p. 195 - 203 (2013/05/08)
The α-hydroxy ketones are used as building blocks for compounds of pharmaceutical interest (such as antidepressants, HIV-protease inhibitors and antitumorals). They can be obtained by the action of enzymes or whole cells on selected substrates, such as diketones. We have studied the enantiospecificities of several fungal (AKR3C1, AKR5F and AKR5G) and human (AKR1B1 and AKR1B10) aldo-keto reductases in the production of α-hydroxy ketones and diols from vicinal diketones. The reactions have been carried out with pure enzymes and with an NADPH-regenerating system consisting of glucose-6-phosphate and glucose-6-phosphate dehydrogenase. To ascertain the regio and stereoselectivity of the reduction reactions catalyzed by the AKRs, we have separated and characterized the reaction products by means of a gas chromatograph equipped with a chiral column and coupled to a mass spectrometer as a detector. According to the regioselectivity and stereoselectivity, the AKRs studied can be divided in two groups: one of them showed preference for the reduction of the proximal keto group, resulting in the S-enantiomer of the corresponding α-hydroxy ketones. The other group favored the reduction of the distal keto group and yielded the corresponding R-enantiomer. Three of the AKRs used (AKR1B1, AKR1B10 and AKR3C1) could produce 2,3-butanediol from acetoin. We have explored the structure/function relationships in the reactivity between several yeast and human AKRs and various diketones and acetoin. In addition, we have demonstrated the utility of these AKRs in the synthesis of selected α-hydroxy ketones and diols.