67436-17-3Relevant academic research and scientific papers
Substrate Engineering in Lipase-Catalyzed Selective Polymerization of d -/ l -Aspartates and Diols to Prepare Helical Chiral Polyester
Zhang, Yu,Xia, Bo,Li, Yanyan,Lin, Xianfu,Wu, Qi
, p. 918 - 926 (2021/02/01)
The synthesis of optically pure polymers is one of the most challenging tasks in polymer chemistry. Herein, Novozym 435 (Lipase B from Candida antarctica, immobilized on Lewatit VP OC 1600)-catalyzed polycondensation between d-/l-aspartic acid (Asp) diester and diols for the preparation of helical chiral polyesters was reported. Compared with d-Asp diesters, the fast-reacting l-Asp diesters easily reacted with diols to provide a series of chiral polyesters containing N-substitutional l-Asp repeating units. Besides amino acid configuration, N-substituent side chains and the chain length of diols were also investigated and optimized. It was found that bulky acyl N-substitutional groups like N-Boc and N-Cbz were more favorable for this polymerization than small ones probably due to competitively binding of these small acyl groups into the active site of Novozym 435. The highest molecular weight can reach up to 39.5 × 103 g/mol (Mw, D = 1.64). Moreover, the slow-reacting d-Asp diesters were also successfully polymerized by modifying the substrate structure to create a "nonchiral"condensation environment artificially. These enantiocomplementary chiral polyesters are thermally stable and have specific helical structures, which was confirmed by circular dichroism (CD) spectra, scanning electron microscope (SEM), and molecular calculation.
A kind of optical active pharmaceutical process for the preparation of intermediates
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, (2016/10/17)
The invention relates to a preparation method of an optical active compound, represented by formula I, or a hydrochloride of the optical active compound by taking a compound with optical activity as a starting material. Raw materials of the preparation method are cheap and easily available; no splitting is needed; the whole technological operation is simple and convenient; cost is low; pollution on environment is less; and the preparation method is suitable for industrialized production. In the formula I, n is 1 or 2 or 3.
A practical, catalytic and selective deprotection of a Boc group in N,Na?2-diprotected amines using iron(III)-catalysis
L?3pez-Soria, Juan M.,P??rez, Sixto J.,Hern??ndez, J. Nicol??s,Ram??rez, Miguel A.,Mart??n, V??ctor S.,Padr?3n, Juan I.
, p. 6647 - 6651 (2015/03/03)
A selective, catalytic and practical method for removing a Boc group from several N,Na?2-diprotected amino acids and amine derivatives using iron(III) salts as sustainable catalysts is described. The process is clean, not needing a purification step. A th
Asymmetric total synthesis of (-)-quinocarcin
Wu, Yan-Chao,Liron, Melanie,Zhu, Jieping
, p. 7148 - 7152 (2008/12/20)
(-)-Quinocarcin (1) has been synthesized in a longest linear sequence of 22 steps from 3-hydroxybenzaldehyde in 16% overall yield. The Pictet-Spengler reaction of L-tert-butyl-2-bromo-5-hydroxy phenylalanate (17), synthesized according to Corey-Lygo's enantioselective alkylation process, with benzoxyacetaldehyde (12) under mild acidic conditions afforded 1,3-cis tetrahydroisoquinoline 20 as an only isolable stereomer in 91% yield. The diazabicycle[3,2,1]-octane ring system of 28 was constructed by a silver tetrafluoroborate-promoted intramolecular Mannich reaction using amino thioether as a latent N-acyliminium species and tethered silyl enol ether as a nucleophile. Using amino thioether instead of aminal as a precursor of N-acyliminium was of high importance to the success of this otherwise disfavored 5-endo-Trig cyclization. A Hf(OTf)4-catalyzed (0.1 equiv) transformation of aminal to amino thioether was uncovered in the course of this study, allowing the conversion of tricyclic aminal 24 to amino thioether 25 to be realized in high yield. From the bridged tetracyclic compound 28, a sequence of oxidation of aldehyde to acid, global deprotection under hydrogenolysis conditions, and one-pot partial reduction of lactam to aminal/oxazolidine formation completed the total synthesis of the pentacyclic (-)-quinocarcine.
A practical method for selective cleavage of a tert-butoxycarbamoyl N-protective group from N,N-diprotected α-amino acid derivatives using montmorillonite K-10
Hernandez, J. Nicolas,Crisostomo, Fernando R. Pinacho,Martin, Tomas,Martin, Victor S.
, p. 5050 - 5058 (2008/03/18)
A new, practical, and mild procedure for the selective cleavage of a tert-butoxycarbonyl group (Boc) in N-Boc-N-acyl-diprotected amines is described. When applied to α-amino acids, complete integrity of the stereochemistry was observed. The use of N,N-di-Boc-α-amino-δ- and γ-hydroxy esters provided both δ- and γ-lactones in very good yields. The method is based on the use of Montmorillonite K-10 either in CH 2Cl2 at room temperature or in toluene at 65°C and is compatible with the presence of a large range of functional and other protecting groups in the substrates. In most cases virtually pure samples are obtained after filtration and removal of solvents. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Regioselective opening of N-Cbz glutamic and aspartic anhydrides with carbon nucleophiles
Deguest, Geoffrey,Bischoff, Laurent,Fruit, Corinne,Marsais, Francis
, p. 2120 - 2125 (2007/10/03)
Depending on the experimental conditions, aspartic and glutamic anhydrides can be opened regioselectively with Grignard reagents, thus giving access to different isomers of chiral amino-ketoesters.
A new diastereoselective synthetic approach to the enantiopure peptidomimetic scaffold 2-oxo-1-azabicyclo[4.4.0]decane
Truchot, Cyrille,Wang, Qian,Sasaki, N. Andre
, p. 1765 - 1776 (2007/10/03)
A general method for the synthesis of unsubstituted and C-7-substituted azabicyclo[4.4.0]decane dipeptides (23, 30a, and 30b) that can serve as dipeptide mimetics has been developed. The key step of this new method involves the coupling reaction of the ox
Asymmetric synthesis of N-protected amino acids by the addition of organolithium carboxyl synthons to ROPHy/SOPHy-derived aldoximes and ketoximes.
Cooper, Tracey S,Laurent, Pierre,Moody, Christopher J,Takle, Andrew K
, p. 265 - 276 (2007/10/03)
A new asymmetric synthesis of alpha-amino acids is described in which the key step is the highly diastereoselective addition of organolithium carboxyl synthons (2-furyllithium, phenyllithium, vinyllithium) to (R)- and (S)-O-(1-phenylbutyl) oximes to give hydroxylamines, with vinyllithium being the most satisfactory nucleophilic reagent. Subsequent reductive cleavage of the N-O bond in hydroxylamines, followed by N-protection, and oxidative cleavage of the carboxyl precursor gave a range of N-protected amino acids and esters. The method was exemplified by the synthesis of a range of derivatives of non-proteinogenic amino acids such as 4-bromophenylalanine, tert-leucine, norvaline, cyclohexyl- and aryl-glycines, 2-amino-8-oxodecanoic acid (Aoda) and alpha-methylvaline.
First Practical Protection of α-Amino Acids as N, N-Benzyloxycarbamoyl Derivatives
Hernandez, J. Nicolas,Martin, Victor S.
, p. 3590 - 3592 (2007/10/03)
The consecutive treatment of N-Cbz amino protected compounds with LiHMDS and CbzCl provides a practical method for the preparation of N,N-benzyloxycarbamoyl (N,N-di-Cbz) derivatives in good yield. When α-amino acids are used the protection occurs without racemization. The method is compatible with a wide range of other functional and protecting groups. The procedure is also valid for the synthesis of mixed N,N-carbamoyl derivatives.
Synthesis of orthogonally protected enantiopure 2,9-diaminodecanedioic acid: A model for a new general method for the synthesis of orthogonally protected α,α′-diaminodicarboxylic acids
Truchot, Cyrille,Sasaki, N. Andre
, p. 393 - 406 (2007/10/03)
A new method for the synthesis of orthogonally protected enantiopure α,α′-diaminodicarboxylic acids is described. A key step involves the Julia olefination of an aldehyde and a sulfone, both of which are derived from an optically pure dicarboxylic amino a
