An extensive survey by the use of high performance liquid chromatography on racemization during the coupling of benzyloxycarbonyl-L-phenylalanyl-L-valine with L-proline tert-butyl ester.
An extensive survey by the use of high performance liquid chromatography on racemization during the coupling of benzyloxycarbonyl-L-phenylalanyl-L-valine with L-proline tert-butyl ester.
作者:SHOJI TAKUMA、YASUMASA HAMADA、TAKAYUKI SHIOIRI
DOI:10.1248/cpb.30.3147
日期:——
The extent of racemization and the coupling efficiency during the coupling of benzyloxycarbonyl-L-phenylalanyl-L-valine with L-proline tert-butyl ester were conveniently and rapidly determined by the use of high performance liquid chromatography with high accuracy. An extensive examination of various known coupling methods revealed that the coupling methods using diphenyl phosphorazidate (DPPA) and, especially, diethyl phosphorocyanidate (DEPC) afforded the best results. Reported results using DPPA and DEPC as peptide coupling reagents are also summarized (Table I).
Convenient primary amidation of N-protected phenylglycine and dipeptides without racemization or epimerization
作者:Takuya Noguchi、Seunghee Jung、Nobuyuki Imai
DOI:10.1016/j.tetlet.2013.11.042
日期:2014.1
Primary amidation of N-protected phenylglycine and dipeptide proceeded easily to afford the corresponding amides in 57–95% yields with 99% ee and 81–99% de, respectively. The procedure is very easy to avoid racemization and epimerization of the products in the reactions by keeping exactly the reaction temperature at −15 °C when the activation of carboxylic acids, followed by the reaction of the mixed
2-Propanephosphonic acid anhydride (T3P)-mediated segment coupling and head-to-tail cyclization of sterically hindered peptides
作者:Jana Klose、Michael Bienert、Christoph Mollenkopf、Detlef Wehle、Chong-wu Zhang、Louis A. Carpino、Peter Henklein
DOI:10.1039/a905021c
日期:——
In the course of comparing the effectiveness of an HOAt-derived coupling reagent (HAPyU) and a phosphonic acid-based condensation agent (T3P) by cyclization of model sequences, we found that T3P was a superior reagent with regard to conversion of the linear peptide into the stereochemically intact cyclic monomer when sterically hindered amino acids are found at the cyclization site.
A novel kinetically-controlled peptide synthesis—Dramatic increase of chemical yield with retention of chiral integrity
作者:Wen-Chung Shieh、John A. Carlson、Michael E. Shore
DOI:10.1016/s0040-4039(99)01493-8
日期:1999.10
Peptide synthesis employing the highly selective reaction of isobutyl chloroformate at the carboxyl group of the N-protected amino acid, almost to the exclusion of the amino group of the C-protected amino acid, is described. This one-stage, kinetically-controlled strategy remarkably affords peptides with excellent optical purity in high chemical yields. (C) 1999 Elsevier Science Ltd. All rights reserved.
Epimerization-Free C-Term Activation of Peptide Fragments by Ball Milling
Peptides were produced in high yields and, if any, very low epimerization, by mechanochemical coupling of peptide fragments containing highly epimerization-prone and/or highly hindered amino acids at C-term. Ball milling was clearly identified as the key element enabling one to obtain such results.
通过在 C 端含有高度差向异构化和/或高度受阻氨基酸的肽片段的机械化学偶联,以高产率和(如果有的话)非常低的差向异构化产生肽。球磨被清楚地确定为获得这种结果的关键因素。