Substrate Engineering in Lipase-Catalyzed Selective Polymerization of <scp>d</scp>-/<scp>l</scp>-Aspartates and Diols to Prepare Helical Chiral Polyester
作者:Yu Zhang、Bo Xia、Yanyan Li、Xianfu Lin、Qi Wu
DOI:10.1021/acs.biomac.0c01605
日期:2021.2.8
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
Calyxamides A and B, Cytotoxic Cyclic Peptides from the Marine Sponge <i>Discodermia calyx</i>
作者:Miki Kimura、Toshiyuki Wakimoto、Yoko Egami、Karen Co Tan、Yuji Ise、Ikuro Abe
DOI:10.1021/np2009187
日期:2012.2.24
thiazole moieties were isolated from the marinespongeDiscodermiacalyx collected near Shikine-jima Island, Japan. The structures of calyxamides A (1) and B (2), including the absolute configurations of all amino acids, were elucidated by spectroscopic analyses and degradation experiments. The structures are similar to keramamides F and G, previously isolated from Theonella sp. The analysis of the
Two separate and distinct syntheses of stereospecifically deuteriated samples of (2S)-proline
作者:Paul Barraclough、Petra Dieterich、Caroline A. Spray、Douglas W. Young
DOI:10.1039/b601097k
日期:——
were then converted into (2S,3S)-[3-(2)H1]- and (2S,3R)-[2,3-(2)H2]-proline, 1a and 1b respectively. The second synthesis provides (2S)-[3,3-(2)H2]-, (2S,3S)- and (2S,3R)-[3-(2)H1]-proline, 1d, 1a and 1c respectively, and has as its key step the highly stereoselective hydrolysis of the silylenol ethers 14 and 14a respectively in which deuteriation or protonation occurs from the re-face of the enol ether