120-45-6Relevant academic research and scientific papers
Chromatography-Free Esterification Reactions Using a Bifunctional Polymer
Ma, Shuang,Toy, Patrick H.
, p. 1207 - 1210 (2016)
A linear polystyrene functionalized with both nucleophilic DMAP groups and sterically hindered tertiary amine groups was synthesized and used homogeneously in a range of esterification reactions between alcohols and various carboxylic acid derivatives. The polymer was highly effective in such reactions where the DMAP groups served as catalytic groups. The ester products of these reactions could be isolated in high purity and yield without the need for chromatographic purification, and the polymer could be recovered and reused numerous times with no apparent decrease in utility.
Two Approaches for CAL-B-Catalyzed Enantioselective Deacylation of a Set of α-Phenyl Ethyl Esters: Organic Solvent with Sodium Carbonate and Micro-aqueous Medium
Razi, Samra,Zeror, Saoussen,Merabet-Khelassi, Mounia,Kolodziej, Emilie,Toffano, Martial,Aribi-Zouioueche, Louisa
, p. 2603 - 2611 (2021/01/15)
Herein, we report an efficient enantioselective cleavage of the acyl- moiety of a set of α- phenyl ethyl esters with different chain-lengths catalyzed by lipase B from Candida antarctica (CAL-B) by comparing two reactional approaches: anhydrous media with sodium carbonates and micro-aqueous medium. The deacylation is performed in organic solvent, in the presence of Na2CO3 in the first case, and by addition of a drop of phosphate buffer solution pH 7 in the second. The results show the high efficiency of the deacylation in the presence of the sodium carbonate for the enzymatic resolution of all the esters and that in term of reactivity (31% ≤ conv ≤ 50%) and selectivity (E > 200). While, during the hydrolysis in micro-aqueous media, the conversion is strongly affected by the length of the acyl-chain side, the conversion decreases from conv = 50% with the 1-phenylethyl acetate 1a to conv = 19% with 1-phenyethyl dodecanoate 6a, and this, even if the selectivity remains high (E > 89). In both conditions, the lipase CAL-B shows a high enantioselectivities in favor of (R)-1-phenyl ethanol enantiomer (conv > 45%, E > 200) but the reactivity is modulated by the form and the size of the acyl-chain side. Graphic Abstract: [Figure not available: see fulltext.].
18O-Labeled chiral compounds enable the facile determination of enantioselectivity by mass spectroscopy
Mandai, Kyoko,Tsuchihashi, Yuta,Ashikari, Yosuke,Yoshida, Jun-ichi,Nagaki, Aiichiro
, (2019/12/24)
The synthesis of 18O-labeled enantioenriched compounds and their facile evaluation system to determine enantiomeric excess (ee) using mass spectroscopy was described. Equimolar mixture of 18O-labeled and non-labeled pseudo-enantiomers were used as a substrate for enzyme-catalyzed kinetic resolution. Ees determined by mass spectroscopy showed good agreement with those by HPLC. Our method would be a promising tool for fast evaluation of ee and contribute to development of enantioselective transformations.
Efficient O-Acylation of Alcohols and Phenol Using Cp2TiCl as a Reaction Promoter
Durán-Pe?a, María Jesús,Botubol-Ares, José Manuel,Hanson, James R.,Hernández-Galán, Rosario,Collado, Isidro G.
supporting information, p. 3584 - 3591 (2016/07/28)
A method has been developed for the conversion of primary, secondary, and tertiary alcohols, and phenol, into the corresponding esters at room temperature. The method uses a titanium(III) species generated from a substoichiometric amount of titanocene dichloride together with manganese(0) as a reductant, as well as methylene diiodide. It involves a transesterification from an ethyl ester, or a reaction with an acyl chloride. A radical mechanism is proposed for these transformations.
An extremely efficient and green method for the acylation of secondary alcohols, phenols and naphthols with a deep eutectic solvent as the catalyst
Nguyen, Hai Truong,Tran, Phuong Hoang
, p. 98365 - 98368 (2016/10/31)
The typical deep eutectic solvent [CholineCl][ZnCl2]3, easily prepared from choline chloride and zinc chloride, is green and useful for the acylation of secondary alcohols, phenols, and naphthols with acid anhydrides. Its efficiency allows the acylation of sterically hindered secondary alcohols and acid anhydrides to proceed in high yield under mild condition. The catalyst is cheap, easy to handle, conveniently synthesized in a single step, and recyclable for several times without significant loss of catalytic activity.
Bi-aryl rotation in phenyl-dihydroimidazoquinoline catalysts for kinetic resolution of arylalkyl carbinols
Wang, Zheng,Ye, Jinjin,Wu, Rui,Liu, Yang-Zi,Fossey, John S.,Cheng, Jiagao,Deng, Wei-Ping
, p. 1909 - 1913 (2014/06/24)
Chiral nucleophilic catalysts, 6-aryl-phenyl-dihydroimidazoquinolines (PIQs), were designed, synthesised and applied to the kinetic resolution of arylalkyl carbinols with very high selectivity (S) factors (up to 530). Density functional theory calculations indicate that multiple noncovalent interactions play a key role in chiral recognition between 6-aryl-PIQ catalysts and chiral secondary alcohol substrates. The Royal Society of Chemistry 2014.
Dynamic double kinetic resolution of amines and alcohols under the cocatalysis of Raney nickel/Candida antarctica lipase B: From concept to application
Xia, Bo,Cheng, Guilin,Lin, Xianfu,Wu, Qi
supporting information, p. 2917 - 2923 (2014/05/20)
Herein, we have established a dynamic double kinetic resolution (DDKR) strategy under the co-catalysis of Raney nickel and Candida antarctica lipase B (CAL-B) for the one-pot simultaneous resolution of primary amines and secondary alcohols (or esters). The DDKR strategy was successfully applied to the resolution of a series of racemic amines and secondary alcohols (or esters) as well as mexiletine, an important antiarrhythmic agent. The catalysts could be recycled and reused several times with the same high activity. Scale-up experiments were also successful. As a more atom-economical and efficient process than traditional simple kinetic resolutions, the DDKR strategy can be widely used to prepare optically pure amines and alcohols.
Kinetic resolution of secondary alcohols by chiral dmap derivatives prepared by the Ugi multicomponent reaction
Mandai, Hiroki,Irie, Shunsuke,Akehi, Masaru,Yuri, Kazunobu,Yoden, Masaaki,Mitsudo, Koichi,Suga, Seiji
, p. 329 - 340 (2013/03/28)
The kinetic resolution of secondary alcohols was examined by new chiral DMAP derivatives, which can readily be prepared by the Ugi multicomponent reaction in a one-pot operation. The initial screening of DMAP derivatives indicated that the catalyst bearing L-valine with an S configuration at the a-position of amide showed the best stereoselectivity factor. After the reaction conditions were optimized with (S,S)-4a in the kinetic resolution of secondary alcohols, various acyclic and cyclic secondary alcohols could be resolved with an s -factor of up to 12.
Kinetic studies on sec-alcohol racemization with dicarbonylchloro(pentabenzylcyclopentadienyl)- and dicarbonylchloro(pentaphenylcyclopentadienyl)ruthenium catalysts
Mavrynsky, Denys,Murzin, Dmitry Yu.,Leino, Reko
, p. 2436 - 2445 (2013/08/23)
Pentasubstituted cyclopentadienyl complexes of ruthenium R5CpRu(CO)2Cl (R=Ph, benzyl) form, upon activation with tBuOK, highly active catalysts for racemization of chiral sec-alcohols. In combination with suitable resolving enzymes, such catalyst systems can efficiently be utilized for dynamic kinetic resolution reactions providing chiral alcohols, after hydrolysis of the corresponding acetates, in high yields and high enantiomeric purities. Here, three such ruthenium complexes were first characterized by NMR spectroscopy and cyclic voltammetry analysis (CVA) for elucidating their electronic characteristics in detail. Then, accurate kinetic studies were performed providing for the first time the calculated racemization rate constants for such catalyst systems. Furthermore, the dependence of the racemization rate on the electronic structure of the catalyst was investigated from the Hammett constants, substitution patterns of the substrate, and by isotopic labeling studies. The results obtained support the earlier suggested racemization reaction mechanism and indicated that the electron-rich catalyst Bn5CpRu(CO)2Cl (Bn=benzyl) racemizes electron-rich substrates more efficiently and in most cases faster than its pentaphenyl substituted analogue, formerly often considered as the leading catalyst candidate for dynamic kinetic resolution applications. The electron-deficient catalyst Ph5CpRu(CO)2Cl, in turn, is more efficient for electron-poor substrates.
Nonenzymatic dynamic kinetic resolution of secondary alcohols via enantioselective acylation: Synthetic and mechanistic studies
Lee, Sarah Yunmi,Murphy, Jaclyn M.,Ukai, Atsushi,Fu, Gregory C.
, p. 15149 - 15153 (2012/10/30)
Because of the ubiquity of the secondary carbinol subunit, the development of new methods for its enantioselective synthesis remains an important ongoing challenge. In this report, we describe the first nonenzymatic method for the dynamic kinetic resolution (DKR) of secondary alcohols (specifically, aryl alkyl carbinols) through enantioselective acylation, and we substantially expand the scope of this approach, vis-a-vis enzymatic reactions. Simply combining an effective process for the kinetic resolution of alcohols with an active catalyst for the racemization of alcohols did not lead to DKR, due to the incompatibility of the ruthenium-based racemization catalyst with the acylating agent (Ac2O) used in the kinetic resolution. A mechanistic investigation revealed that the ruthenium catalyst is deactivated through the formation of a stable ruthenium-acetate complex; this deleterious pathway was circumvented through the appropriate choice of acylating agent (an acyl carbonate). Mechanistic studies of this new process point to reversible N-acylation of the nucleophilic catalyst, acyl transfer from the catalyst to the alcohol as the rate-determining step, and carbonate anion serving as the Bronsted base in that acyl-transfer step.
