688-09-5Relevant 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.
Calyxamides A and B, cytotoxic cyclic peptides from the marine sponge Discodermia calyx
Kimura, Miki,Wakimoto, Toshiyuki,Egami, Yoko,Tan, Karen Co,Ise, Yuji,Abe, Ikuro
experimental part, p. 290 - 294 (2012/05/05)
Cyclic peptides containing 5-hydroxytryptophan and thiazole moieties were isolated from the marine sponge Discodermia calyx 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 16S rDNA sequences obtained from the metagenomic DNA of D. calyx revealed the presence of Candidatus Entotheonella sp., an unculturable δ-proteobacterium inhabiting the Theonella genus and implicated in the biosynthesis of bioactive peptides.
Two separate and distinct syntheses of stereospecifically deuteriated samples of (2S)-proline
Barraclough, Paul,Dieterich, Petra,Spray, Caroline A.,Young, Douglas W.
, p. 1483 - 1491 (2008/02/03)
Two distinct syntheses of samples of the amino acid l-proline which are stereospecifically deuteriated on the β-carbon atom are reported. In the first of these, the labelled diazoketones 6, prepared by a chemico-enzymatic synthesis, have been photolysed in alkaline conditions to give the corresponding labelled methyl pyroglutamates 10 via hydrolysis and intramolecular trapping of the resultant ketene intermediates 9. These were then converted into (2S,3S)-[3-2H1]- and (2S,3R)-[2,3-2H 2]-proline, 1a and 1b respectively. The second synthesis provides (2S)-[3,3-2H2]-, (2S,3S)- and (2S,3R)-[3- 2H1]-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. The Royal Society of Chemistry 2006.
Synthesis of L-Serine Stereospecifically Labelled at C-3 with Deuterium
Gani, David,Young, Douglas W.
, p. 2393 - 2398 (2007/10/02)
(2S,3R)-1>- and (2S,3S)-2>-Serines have been synthesised from the corresponding labelled aspartic acids.The synthesis involves a Baeyer-Villiger oxidation in which a migrating primary chiral centre rearranges with retention of stereochemistry.
