decarboxylative amidation of α-ketoacids by using inexpensive tert-butyl hydroperoxide (TBHP), which is characterized by high yields, a broad substrate scope, mild reaction conditions, and a unique chemoselectivity. These features enable the synthesis of peptides from amino acid derived α-ketoacids under preservation of the stereochemical information.
results in a significant advance in convergent peptide synthesis is described. Despite the observation of epimerization with low bulk substrates in preliminary studies, a systematic examination and understanding of the reaction mechanism enabled the development of a modified epimerization-free reaction whereby peptidefragmentcouplingsusingpeptide α-ketoacids were successfully achieved. Fullsize
1-Ethyl 2-Halopyridinium Salts, Highly Efficient Coupling Reagents for Hindered Peptide Synthesis both in Solution and the Solid-Phase
作者:Peng Li、Jie-Cheng Xu
DOI:10.1016/s0040-4020(00)00657-8
日期:2000.10
proved to be very effective for the synthesis of hindered peptides containing N-methylated or Cα,Cα-dialkylated amino acid residues. HPLC monitoring of model reactions indicated that these pyridinium salts demonstrated higher reactivities, lower racemization than the commonly used halogenated uronium and phosphonium salts. The efficiency of these pyridinium type coupling reagents was further proved by the
1-乙基-2-卤代吡啶鎓盐,BEP,FEP,BEPH和FEPH,合成并证明是含有受阻的肽的合成是非常有效的Ñ甲基化的或Ç α,Ç α-二烷基化的氨基酸残基。HPLC对模型反应的监测表明,与通常使用的卤化铀盐和phospho盐相比,这些吡啶鎓盐具有更高的反应活性和更低的消旋性。通过合成一系列受阻的寡肽和活性酯,具有良好的收率和方便的后处理,进一步证明了这些吡啶鎓类偶联剂的效率。使用这些吡啶鎓盐还成功合成了环孢菌素A(CsA)的8-11四肽片段和Dolastatin 15的五肽部分。这些吡啶鎓类偶联剂对SPPS的效率还通过CsA的极受阻碍的8-11肽段和CsO的线性十一肽的固相合成证明。1 H NMR,IR和HPLC。提出主要的反应性中间体是N-保护的氨基酸或肽的相应的酰卤和酰氧基吡啶鎓盐。