95061-46-4Relevant articles and documents
Reductive coupling between aromatic aldehydes and ketones or imines by copper catalysis
Takeda, Mitsutaka,Mitsui, Atsuhisa,Nagao, Kazunori,Ohmiya, Hirohisa
, p. 3664 - 3669 (2019/02/14)
The copper-catalyzed reductive coupling of two different carbonyl compounds has been achieved. The reaction of aromatic aldehydes and arylketones with a silylboronate in the presence of a catalytic amount of a CuCl-N-heterocyclic carbene (NHC) complex and a stoichiometric amount of alkoxide base yielded cross-coupled 1,2-diol derivatives. A reaction pathway is proposed that involves the catalytic formation of a nucleophilic α-silyloxybenzylcopper(I) species from the aromatic aldehyde and its subsequent coupling with the arylketone. This process was amenable to asymmetric catalysis. This copper catalyst system also enabled the reductive coupling between aromatic aldehydes and imines.
Homochiral Metal-Organic Frameworks with Tunable Nanoscale Channel Array and Their Enantioseparation Performance against Chiral Diols
Zhuo, Chao,Wen, Yuehong,Hu, Shengmin,Sheng, Tianlu,Fu, Ruibiao,Xue, Zhenzhen,Zhang, Hao,Li, Haoran,Yuan, Jigang,Chen, Xi,Wu, Xintao
supporting information, p. 6275 - 6280 (2017/06/13)
Enantioseparation is an integral process in the pharmaceutical industry, considering the ever-increasing demand for chiral medicine products. As a new material, porous metal-organic frameworks (MOFs) have shown their potential application in this field because their structures are easy to adjust and control. Though chiral recognition between racemic substrates and frameworks has made preliminary progress, discussions of their size-matching effects are rare. Herein with the help of channel-tunable homochiral MOFs (HMOFs), diols of different sizes have been separated in good enantiomeric excess (ee%). In addition, the ee% reaches 67.4% for the first time for diols as large as 1,1,2-triphenyl-1,2-ethanediol, which turns out to be the most effective value so far.
Novel biphenyl organocatalysts for iminium ion-catalyzed asymmetric epoxidation
Farah, Mohamed M.,Page, Philip C. Bulman,Buckley, Benjamin R.,Blacker, A. John,Elsegood, Mark R.J.
, p. 758 - 769 (2013/07/27)
Two novel chiral biphenyl iminium salts derived from L-acetonamine, containing electron-withdrawing 3,30-substituents on the biphenyl unit, have been prepared and tested as asymmetric catalysts for epoxidation of prochiral alkenes. The results are compared with those achieved using the corresponding unsubstituted system.
PROCESS FOR PREPARING (R)-(+)-LANSOPRAZOLE AND INTERMEDIATE USED THEREIN
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Page/Page column 9-10, (2010/07/02)
A process for the preparation of (R)-(+)-lansoprazole having a high optical purity and a novel intermediates used therein are provided. The inventive process provides (R)-(+)-lansoprazole having a high optical purity through optical resolution of racemic lansoprazole.
Comprehensive experimental and theoretical studies of configurationally labile epimeric diamine complexes of α-lithiated benzyl carbamates
Lange, Heiko,Huenerbein, Robert,Wibbeling, Birgit,Froehlich, Roland,Grimme, Stefan,Hoppe, Dieter
experimental part, p. 2905 - 2918 (2009/04/07)
Different primary benzyl-type carbamates were deprotonated by sec-butyllithium in the presence of a tert-leucinol-derived bis(oxazoline) ligand. The resulting configurationally labile epimeric complexes equilibrated and one diastereomer was strongly favor
PROCESS FOR THE PREPARATION OF ATORVASTATIN AND INTERMEDIATES
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Page/Page column 9, (2008/06/13)
A process is provided for preparing (R)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-5-hydroxy-3-oxo-1-heptanoic acid, R-substituted ester 9 comprising: (a) reacting the aldehyde 1 with the enolate form of (S)-2-hydroxy-1,2,2-triphenylethyl acetate substituent in a chelating co-solvent; (b) hydrolysis of (R,S)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-3-hydroxy-1-pentanoic acid, (S)-2-hydroxy-1,2,2-triphenylethyl ester (2a and 2b) using a base, preferably an alkali metal base, preferably in a solvent to form the carboxylic acid 7; (c) treating the acid 7 with a chiral base to form a salt and purifying the salt to obtain enantiomerically enriched (R)-7 chiral base salt; (d) alkylation of the (R)-7 chiral base salt or the free base derived from (R)-7, forming (R)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-5-hydroxy-3-oxo-1-heptanoic acid, R-substituted ester 9 and atorvastatin calcium 6, wherein R is a C1 to C6 alkyl, C6 to C9 aryl or C7 to C10 aralkyl.
A facile, catalytic, and environmentally benign method for selective deprotection of teri-butyldimethylsilyl ether mediated by phosphomolybdic acid supported on silica gel
Kishore Kumar,Baskaran, Sundarababu
, p. 4520 - 4523 (2007/10/03)
An environmentally benign PMA supported on SiO2 is found to be an efficient catalyst for the chemoselective deprotection of TBDMS ethers under very mild conditions. Various labile functional groups such as isopropylidene acetal, OTBDPS, OTHP, Oallyl, OBn, alkene, alkyne, OAc, OBz, N-Boc, N-Cbz, N-Fmoc, mesylate, and azide are found to be stable under the reaction conditions. This "truly catalytic" heterogeneous reaction does not require aqueous workup, and the supported catalyst and the solvent can be readily recovered and recycled.
Reaction of 2-hydroxy-1,2,2-triphenylethyl propionate with non-activated ketones and enones: Stereoselective aldol and Michael addition
Braun, Manfred,Mai, Brigitte,Ridder, Daniel
, p. 3155 - 3160 (2007/10/03)
The TiCl4-mediated Mukaiyama-type reaction of the silyl ketene acetal 2, derived from (R)-propionate 1, with the ketones 3a-d occurs in a stereoselective manner. The aldol product 4c is obtained from the enone 3c, whereas the homologous compound 3d undergoes a 1,4 addition and leads to the keto ester 5. The configurations of the deprotected aldol adduct 6 (obtained from 3c) and the Michael product 5 are determined by crystal structure analyses. The diastereomerically and enantiomerically pure esters 4a-c, 5, and 6, as well as the carboxylic acid 7 and the diol 8, containing two or three contiguous stereogenic carbon centers, are prepared. The enantiomerically pure compounds 7 and 8 result from the cleavage of the chiral auxiliary reagent 1,1,2-triphenyl-1,2-ethanediol, which can be recovered.
Efficient resolution of (±)-pantolactone by inclusion crystallization with the use of chiral 1,1,2-triphenylethane-1,2-diol
Vinogradov,Kurilov,Ferapontov,Heise
, p. 1483 - 1484 (2007/10/03)
Enantioselective formation of crystalline 1 : 1 host - guest complexes with (R)- or (S)-1,1,2-triphenylethane-1,2-diol as a host compound allows efficient preparative resolution of (±)-pantolactone. Optically active pantolactones (98% ee) were obtained in 65 - 67% yield.
Supramolecular crystalline construction based on a mandelic acid source. host design, inclusion formation and X-ray crystal structures of a methanol inclusion complex and free host structures in racemic and optically resolved forms
Weber, Edwin,Hager, Orm,Foces-Foces, Concepcion,Llamas-Saiz, Antonio L.
, p. 50 - 60 (2007/10/03)
A new host compound in optically resolved and racemic forms for selective crystalline inclusion formation derived from natural mandelic acid was synthesized. Inclusion properties of the two optical species are discussed, involving comparison with a lactic acid-based host analogue. Inclusion compounds with amines, ketones and heterocyclics and specifically with small unbranched alcohols were isolated. The crystal and molecular structures of the optically resolved and racemic forms of the free host at room temperature and the methanol inclusion complex of the resolved host at 255 K were determined by x-ray analysis. Two different binding schemes characterize the packing of these structures, in which one hydroxyl group is responsible for the formation of dimers and chains while in the free host the other hydroxyl group is involved in OH-phenyl interactions. A survey of the OH...phenyl interactions based on the Cambridge Structural Data Base (October 1994 version) reveals that π-electron bonding occurs in a wide range of crystal structures. The approximation of the hydrogen appears to take place in an asymmetric way. Several calculations for the ab initio prediction of the crystal structures were performed.
