112979-62-1Relevant academic research and scientific papers
Free-radical polymerization of (r)-(-)-1-(1-naphthyl)ethyl(2-methacryloyloxyethyl)urea and chiral recognition ability
Lee, Yong-Kyung,Nakashima, Yuji,Onimura, Kenjiro,Tsutsumi, Hiromori,Oishi, Tsutomu
, p. 4735 - 4742 (2003)
(R)-(-)-1-(1-Naphthyl)ethyl(2-methacryloyloxyethyl)urea (NEMOU) was synthesized from 2-methacryloyIoxyethyl isocyanate (MOI) and (R)-(+)-1-(1-naphthyl)ethylamine. Radical homopolymerizations of NEMOU were performed in several solvents to obtain the corresponding chiral polymers that have hydrogen bonds based on urea moieties. Specific optical rotations of poly(NEMOU) changed by the measurement temperature, which may be attributed in part to change of conformation. From the results of radical copolymerizations of NEMOU with styrene (ST, M2) or methyl methacrylate (MMA, M2), monomer reactivity ratios (r1, r2) and Alfrey-Price Q-e were determined: r1 = 0.48, r2 = 0.20, Q1 = 1.41, e1 = 0.74 for the NEMOU-ST system; r1 = 0.55, r2 = 0.16, Q1 = 9.02, e1 = 1.96 for the NEMOU-MMA system. The chiroptical property of the copolymers was strongly influenced by comonomer units. To examine the chiral recognition ability of poly(NEMOU), chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC) were prepared from silica gel and poly(NEMOU). The CSPs resolved some racemates such as 1,2,3,4-tetrahydro-1-naphthol and N-benzyl-1-(1-methyl-2-methoxy-carbony)ethylamine in n-hexane/2-propanol as mobile phase by HPLC. The chiral recognition ability of poly(NEMOU) may be ascribed not only to the interaction between the low molecular weight chiral selector and the racemates but also to the secondary and/or higher-ordered structure of the polymer.
One-pot lipase-catalyzed enantioselective synthesis of (r)-(?)-n-benzyl-3-(benzylamino)butanamide: The effect of solvent polarity on enantioselectivity
Ortega-Rojas, Marina A.,Rivera-Ramírez, José Domingo,ávila-Ortiz, C. Gabriela,Juaristi, Eusebio,González-Mu oz, Fernando,Castillo, Edmundo,Escalante, Jaime
, (2018/01/12)
The use of the solvent engineering has been applied for controlling the resolution of lipase-catalyzed synthesis of β-aminoacids via Michael addition reactions. The strategy consisted of the thermodynamic control of products at equilibrium using the lipase CalB as a catalyst. The enzymatic chemo- and enantioselective synthesis of (R)-(?)-N-benzyl-3-(benzylamino)butanamide is reported, showing the influence of the solvent on the chemoselectivity of the aza-Michael addition and the subsequent kinetic resolution of the Michael adduct; both processes are catalyzed by CalB and both are influenced by the nature of the solvent medium. This approach allowed us to propose a novel one-pot strategy for the enzymatic synthesis of enantiomerically enriched β-aminoesters and β-aminoacids.
Mechanochemical enzymatic resolution of N-benzylated-β3-amino esters
Pérez-Venegas, Mario,Reyes-Rangel, Gloria,Neri, Adrián,Escalante, Jaime,Juaristi, Eusebio
, p. 1728 - 1734 (2017/09/27)
The use of mechanochemistry to carry out enantioselective reactions has been explored in the last ten years with excellent results. Several chiral organocatalysts and even enzymes have proved to be resistant to milling conditions, which allows for rather efficient enantioselective transformations under ball-milling conditions. The present article reports the first example of a liquid-assisted grinding (LAG) mechanochemical enzymatic resolution of racemic β3-amino esters employing Candida antarctica lipase B (CALB) to afford highly valuable enantioenriched N-benzylated-β3-amino acids in good yields. Furthermore the present protocol is readily scalable.
Nitrile biotransformations for the synthesis of highly enantioenriched β-hydroxy and β-amino acid and amide derivatives: A general and simple but powerful and efficient benzyl protection strategy to increase enantioselectivity of the amidase
Ma, Da-You,Wang, De-Xian,Pan, Jie,Huang, Zhi-Tang,Wang, Mei-Xiang
, p. 4087 - 4091 (2008/09/20)
(Chemical Equation Presented) Biotransformations of a number of racemic β-hydroxy and β-amino nitrile derivatives were studied using Rhodococcus erythropolis AJ270, the nitrile hydratase and amidase-containing microbial whole cell catalyst, under very mild conditions. The overall enantioselectivity of nitrile biotransformations was governed predominantly by the amidase whose enantioselectivity was switched on remarkably by an O- and a N-benzyl protection group of the substrates. While biotransformations of β-hydroxy and β-amino alkanenitriles gave low yields of amide and acid products of very low enantiomeric purity, introduction of a simple benzyl protection group on the β-hydroxy and β-amino of nitrile substrates led to the formation of highly enantioenriched β-benzyloxy and β-benzylamino amides and acids in almost quantitative yield. The easy protection and deprotection operations, high chemical yield, and excellent enantioselectivity render the nitrile biotransformation a useful protocol in the synthesis of enantiopure β-hydroxy and β-amino acids.
Process for producing either optically active n-substituted beta-amino acid and optically active n-substituted beta-amino acid ester or optically active n-substituted 2-homopipecolic acid and optically active n-substituted 2-homopipecolic acid ester
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, (2008/06/13)
The present invention discloses a process which comprises selectively hydrolyzing one enantiomer of racemic mixtures of an N-substituted β-amino acid alkyl ester or N-substituted 2-homopipecolic acid ester represented by the formula (I): wherein Ar, Rsup
Amine-salt-controlled, catalytic asymmetric conjugate addition of various amines and asymmetric protonation
Hamashima, Yoshitaka,Somei, Hidenori,Shimura, Yuta,Tamura, Toshihiro,Sodeoka, Mikiko
, p. 1861 - 1864 (2007/10/03)
Matrix presented. The combined use of chiral Pd complex 2 and amine salt enabled completely regulated release of free nucleophilic amine. Under these conditions, an efficient catalytic asymmetric conjugate addition of various amines was achieved to afford
A practical stereoselective synthesis of (2S, 4S)-4-tert-butoxycarbonylamino-2-methylpyrrolidine
Qun, Li,Chu, Daniel T. W.,Raye, Kathleen,Claiborne, Akiyo,Seif, Louis,Macri, Bryan,Plattner, Jacob J.
, p. 8391 - 8394 (2007/10/02)
Two practical syntheses of (2S, 4S)-4-tert-butoxycarbonylamino-2-methylpyrrolidine, an important intermediate for quinolone antibacterial agents, have been developed through the combination of diastereo and enantioselective reactions starting from ethyl crotonate and L-alanine, respectively.
