BroP (bromo tris(dimethylamino) phosphonium hexafluorophosphate) is a particularly suitable reagent for coupling N-methylated aminoacids. It is stable and gives very high yields in short reaction times. Dipeptides are obtained without appreciable epimerization.
Antineoplastic Agents. 599. Total Synthesis of Dolastatin 16
作者:George R. Pettit、Thomas H. Smith、Pablo M. Arce、Erik J. Flahive、Collin R. Anderson、Jean-Charles Chapuis、Jun-Ping Xu、Thomas L. Groy、Paul E. Belcher、Christian B. Macdonald
DOI:10.1021/np500925y
日期:2015.3.27
23-step total synthesis of the cyclodepsipeptide dolastatin 16 (1) has been achieved. Synthesis of the dolaphenvaline and dolamethylleuine amino acid units using simplified methods improved the overall efficiency. The formation of the 25-membered macrocycle employing lactonization with 2-methyl-6-nitrobenzoic anhydride completed a key step in the synthesis. Regrettably, the synthetic dolastatin 16 (1), while
A novel thiazolium type peptide coupling reagent for hindered amino acids
作者:Peng Li、Jie Cheng Xu
DOI:10.1016/s0040-4039(99)01763-3
日期:1999.11
A highly efficient couplingreagent, 2-bromo-3-ethyl-4-methyl thiazolium tetrafluoroborate (BEMT), was designed, synthesized and successfully applied to the synthesis of oligopeptides containing N-alkyl or α-C-dialkyl aminoacids. Its efficiency was evaluated by HPLC and 1H NMR methods, and demonstrated by synthesis of a number of N-methyl-rich peptide segments with good yields and negligible racemization
设计,合成了高效偶联试剂2-溴-3-乙基-4-甲基噻唑四氟硼酸酯(BEMT),并将其成功地用于合成包含N-烷基或α- C-二烷基氨基酸的寡肽。通过HPLC和1 H NMR方法评价了其效率,并通过合成了许多具有良好产率和可忽略的外消旋作用的富含N-甲基的肽段。通过HPLC,1 H NMR和IR监测研究了偶联机理。有人提出不稳定的(酰氧基)噻唑盐和N-保护的氨基酸溴化物是主要的活性中间体,伴随着N的形成-乙基-4-甲基噻唑烷酮和少量的恶唑酮和N保护的氨基酸酸酐。
Convergent Synthesis of Dolastatin 15 by Solid Phase Coupling of an <i>N</i>-Methylamino Acid
Convergent synthesis of dolastatin 15 (1), a cytostatic depsipeptide isolated from the Indian Ocean sea hare, has been described. For construction of the backbone, a single-step condensation of peptide fragment 2 and pyrrolidone fragment 3 was successfully performed using 2-chloro-1,3-dimethyl-2-imidazolinium hexafluorophosphate (CIP) developed by us as an efficient coupling reagent. Coupling of an N-methylamino acid on solid support was first achieved using CTP for the efficient synthesis of peptide fragment 2. The effectiveness of CIP for the coupling of N-methylamino acids in solution and on solid support were clarified by the syntheses of model di- and tripeptides.
Depsipeptides
作者:Yu. A. Ovchinnikov、V. T. Ivanov、A. A. Kiryushkin