Asymmetric Guerbet Reaction to Access Chiral Alcohols
作者:Kun Wang、Lin Zhang、Weijun Tang、Huaming Sun、Dong Xue、Ming Lei、Jianliang Xiao、Chao Wang
DOI:10.1002/anie.202003104
日期:2020.7.6
example of an asymmetric Guerbet reaction has been developed. Using commercially available, classic Noyori RuII‐diamine‐diphosphine catalysts, well‐known in asymmetric hydrogenation, racemic secondary alcohols are shown to couple with primary alcohols in the presence of a base, affording new chiral alcohols with enantiomeric ratios of up to 99:1. Requiring no reducing agents, the protocol provides an easy
Transfer Hydrogenation of Aryl Ketones with Half‐Sandwich Ru
<sup>II</sup>
Complexes That Contain Chelating Diamines
作者:Hayati Türkmen、İbrahim Kani、Bekir Çetinkaya
DOI:10.1002/ejic.201200638
日期:2012.10
comparative study, half-sandwich complexes of RuII (1) with pyridine-based chelatingdiamine [NN = 2-aminomethylpiperidine (ampi), a; 2-aminomethylpyridine (ampy), b; 8-aminoquaniline (aquan), c; 4,4′-dimethyl-2,2′-bipyridine (dbipy), d; 2,2′-bipyridine (bipy), e] or amine amide (Ts-ampi, 2a) were synthesized by cleavage of [(η6-p-cymene)Ru(μ-Cl)Cl}2] dimer and the resulting complexes were screened for their
Highly efficient dynamic kinetic resolution of secondary aromatic alcohols at low temperature using a low-cost sulfonated sepiolite as racemization catalyst
作者:Jian-Ping Wu、Xiao Meng、Liang Wang、Gang Xu、Li-Rong Yang
DOI:10.1016/j.tetlet.2014.07.102
日期:2014.9
A highly efficient dynamic kineticresolution system for secondary aromatic alcohol using low-cost sulfonated sepiolite as a racemization catalyst has been developed. The system operates at 25 °C, achieves good eep (>99%) and substrate conversion ratio (>99%), is applicable to a variety of substrates and can be reused more than 10 times.
Highly efficient dynamic kinetic resolution of secondary aromatic alcohols using a low-cost solid super acid as a racemization catalyst
作者:Gang Xu、Liang Wang、Yongjun Chen、Yongmei Cheng、Jianping Wu、Lirong Yang
DOI:10.1016/j.tetlet.2013.07.016
日期:2013.9
A new, efficient dynamic kinetic resolution (DKR) of secondary aromatic alcoholsusing self-made solid super acid TiO2/SO42- as a racemization catalyst was developed. Low-cost and easily produced TiO2/SO42- showed excellent racemization activity. When coupled with the lipase, Novozym 435, good biocompatibility was observed, and optically pure aromatic acetate (>99%) was obtained with a high yield.
PREPARATION METHOD OF DEXMEDETOMIDINE INTERMEDIATE
申请人:TIANJIN WEIJIE PHARMACEUTICAL CO., LTD
公开号:US20160272594A1
公开(公告)日:2016-09-22
The present invention discloses a preparation method of 2,3-dimethyl phenyl-1-trityl-imidazole-4-ketone. In accordance with this method, imidazole-4-ethyl formate is used as a raw material; ethyl formate is used for amino protection, 1-trityl-1H-imidazole-4-formic acid is obtained after basic hydrolysis; 1-trityl-1H-imidazole-4-formic acid and N,O-dimethylhydroxylamine hydrochloride are subjected to condensation so as to obtain N-methoxyl-N-methyl-1-trityl-1H-imidazole-4-formamide; and N-methoxyl-N-methyl-1-trityl-1H-imidazole-4-formamide and a Grignard reagent prepared by the reaction of 2,3-dimethylbromobenzene with magnesium are subjected to a Grignard reaction, and then the target product 2,3-dimethyl phenyl-1-trityl-1H-imidazole-4-ketone is obtained. Compared with the reported preparation methods, the preparation method is more convenient to operate and is beneficial for industrial production.