67436-17-3Relevant articles and documents
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 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
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.
