HPLC separation of 2-aryloxycarboxylic acid enantiomers on chiral stationary phases
作者:A. A. Tumashov、S. A. Vakarov、L. Sh. Sadretdinova、E. N. Chulakov、G. L. Levit、V. P. Krasnov、V. N. Charushin
DOI:10.1007/s11172-021-3165-8
日期:2021.5
reversed-phase HPLC on popular chiralstationaryphases. The best separation parameters were achieved on the chiralphases with the polysaccharide base Chiralcel OD-H and Chiralpack AD under the normal-phase HPLC conditions. The (S)- and (R)-enantiomers of 2-(1-naphthyloxy)- and 2-(2-iodophenoxy)propionic acids with enantiomeric excess ee >99% were isolated using preparative chiralHPLC.
[EN] A PROCESS FOR THE SYNTHESIS OF LOFEXIDINE<br/>[FR] PROCÉDÉ DE SYNTHÈSE DE LOFEXIDINE
申请人:PROCOS SPA
公开号:WO2020254580A1
公开(公告)日:2020-12-24
Disclosed is a process for the synthesis of lofexidine of formula (I) and the hydrochloride salt thereof (II), from ethyl 2-(2,6-dichlorophenoxy)propionate (III) and ethylenediamine in the presence of tetravalent titanium alkoxides, preferably titanium isopropoxide, in an apolar solvent such as toluene. A further object of the present invention is a process for the preparation of the intermediate ethyl 2-(2,6-dichlorophenoxy)propionate (III) from 2,6-dichlorophenol and ethyl 2-chloropropionate in the presence of a polar aprotic solvent and an alkali or alkaline earth carbonate salt, preferably potassium carbonate. Both processes are more cost-effective and more easily industrially scalable than the known procedures, thus enabling the active ingredient to be obtained with high yields at a limited cost.
A New Method for Production of Chiral 2-Aryloxypropanoic Acids Using Effective Kinetic Resolution of Racemic 2-Aryloxycarboxylic Acids
作者:Isamu Shiina、Atsushi Tengeiji、Kenya Nakata、Keisuke Ono
DOI:10.3987/com-12-s(n)79
日期:——
We report a novel method for the preparation of 2-aryloxypropanoic acids by kinetic resolution of racemic 2-aryloxypropanoic acids using enantioselective esterification. The usage of pivalic anhydride (Piv(2)O) as an activating agent, bis(alpha-naphthyl)methanol ((alpha-Np)(2)CHOH) as an achiral alcohol, and (+)-benzotetramisole ((+)-BTM) as a chiral acyl-transfer catalyst enables the effective separation of various racemic 2-aryloxypropanoic acids to afford optically active carboxylic acids and the corresponding esters with high enantioselectivities. Furthermore, theoretical calculations of the transition states required to form the chiral esters successfully proved the enantiomer recognition mechanism of the asymmetric esterification.
Fawcett et al., Annals of Applied Biology, 1955, vol. 43, p. 342,343, 344
作者:Fawcett et al.
DOI:——
日期:——
Osborne et al., Journal of Experimental Botany, 1955, vol. 6, p. 392,393, 394