100760-07-4Relevant academic research and scientific papers
Cobalt-catalyzed asymmetric hydrogenation of ketones: A remarkable additive effect on enantioselectivity
Du, Tian,Wang, Biwen,Wang, Chao,Xiao, Jianliang,Tang, Weijun
supporting information, p. 1241 - 1244 (2020/10/02)
A chiral cobalt pincer complex, when combined with an achiral electron-rich mono-phosphine ligand, catalyzes efficient asymmetric hydrogenation of a wide range of aryl ketones, affording chiral alcohols with high yields and moderate to excellent enantioselectivities (29 examples, up to 93% ee). Notably, the achiral mono-phosphine ligand shows a remarkable effect on the enantioselectivity of the reaction.
Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of Ketones
Liu, Xiaoqin,Wang, Qiaotian,Han, Caifang,Feng, Xiangqing,Du, Haifeng
, p. 663 - 666 (2019/05/21)
A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst. A wide range of optically active secondary alcohols were furnished in 80%—99% yields with 81%—97% ee's under mild reaction conditions.
Plant-mediated asymmetric reduction of 1-(3,4-dimethylphenyl)ethanone
Pavokovi?, Dubravko,Bu?a, Renata,Andra?ec, Fran,Roje, Marin,Bubalo, Marina Cvjetko,Redovnikovi?, Ivana Radoj?i?
, p. 730 - 733 (2017/05/29)
Bioreduction mediated by plants is a highly selective and environmentally friendly approach to synthesise optically active alcohols. Herein the bioreduction of 1-(3,4)-dimethylphenyl)ethanone to the corresponding chiral alcohol 1-(3,4-dimethylphenyl)ethanol has been evaluated using nine different vegetables roots as biocatalysts. The chiral alcohol was prepared in yields ranging from 44.1% to 88.2%, and with enantiomeric excess up to 97.2% for the (S)-enantiomer. Sugar beet was the most promising among the tested vegetables roots. Therefore, sugar beet cell cultures (normal and transformed) were obtained and tested for the reduction as well, yielding the corresponding alcohol in the range from 62.1% to 88.2% yield and with enantiomeric excesses of >99%. Based on these results reported, there are no profound differences in the reductive capacity of undifferentiated cells and organs of the same plant species (sugar beet). Due to overall advantages of using cell cultures, we have highlighted this approach as a promising method for preparation of enantiomerically pure 1-(3,4-dimethylphenyl)ethanol.
Chiral Oxazolidine-Fused N-Heterocyclic Carbene Complexes of Rhodium and Iridium and Their Utility in the Asymmetric Transfer Hydrogenation of Ketones
Ramasamy, Balasubramaniyam,Kumar Gangwar, Manoj,Ghosh, Prasenjit
, p. 3253 - 3268 (2017/07/22)
The catalytic potential of new N-heterocyclic carbene ligands, derived from a chiral fused bicyclic ring scaffold with restricted rotation along the C–N bond bearing the chiral auxiliary, has been explored in the transition-metal-mediated asymmetric transfer hydrogenation reactions of ketones. In particular, the chiral oxazolidine-fused N-heterocyclic carbene precursors (3S)-3-R-6-methyl-7-phenyl-2,3-dihydroimidazo[5,1-b]oxazol-6-ium iodide [R = sec-butyl (1f), i-butyl (2f), isopropyl (3f)] were synthesized from commercially available optically pure amino acids in a multistep sequence that avoids tedious chiral resolution. The reactions of the chiral imidazolium iodide salts 1f–3f with Ag2O yielded the corresponding silver complexes 1g–3g, which were treated with [(COD)MCl]2 (M = Rh, Ir; COD = 1,5-cyclooctadiene) to afford the rhodium(I) and iridium(I) complexes (1h–3h and 1i–3i, respectively). The rhodium(I) and iridium(I) complexes conveniently catalyze the asymmetric transfer hydrogenation of acetophenones for a wide variety of substrates ranging from electron-rich ones such as 4-methylacetophenone, 3,4-dimethylacetophenone, 4-tert-butylacetophenone, and 4-(methylthio)acetophenone to electron-deficient ones such as 4-bromoacetophenone, 4-chloroacetophenone, 4-fluoroacetophenone, 4-nitroacetophenone, and 3-fluoroacetophenone in moderate-to-good yields (ca. 18–95 %) but with low enantioselectivities (ca. 4–41 % ee).
Escherichia coli BioH: A highly enantioselective and organic solvent tolerant esterase for kinetic resolution of sec-alcohols
Wang, Bo,Tang, Xiaoling,Liu, Ji,Yu, Hongwei
supporting information; experimental part, p. 6360 - 6364 (2011/01/04)
Escherichia coli BioH, which is obligatory for biotin synthesis, was found to be an organic solvent tolerant esterase with high enantioselectivity for the kinetic resolution of sec-alcohols using free enzyme powder. With this esterase, a variety of racemic sec-alcohols were efficiently resolved with ee values of up to 99%.
Preparation of chiral 1-phenylethanols and bromides
Stein, Allan R.,Dawe, Robert D.,Sweet, James R.
, p. 3442 - 3448 (2007/10/02)
A fast, convenient procedure for preparing and resolving moderate to large quantities of chiral secondary alcohols is described.The general procedure involves a one-pot conversion of the ketone (various acetophenones) to the half-ester of a diacid (succinic, phthalic...) and resolution with (+)- and (-)-1-phenylethylamines.Overall yields of the enantiomeric alcohols, the variously substituted 1-phenylethanols, are generally 65-85percent with optical purities of approximately 90percent.Properties and optical rotations of a number of chiral 1-phenylethanols and of the bromides made from them are tabulated.A discussion of optical purity determinations using nmr methods is included and absolute configurations are reported.
