Novel polyoxazole-based cyclopeptides from Streptomyces sp. Total synthesis of the cyclopeptide YM-216391 and synthetic studies towards telomestatin
作者:Jon Deeley、Anna Bertram、Gerald Pattenden
DOI:10.1039/b802477d
日期:——
hepta-oxazole 30en route to telomestatin 1. Likewise, neither the hexa-oxazole 47 or application of an intramolecular Hantzsch oxazole ring-forming reaction from 44b allowed access to the advanced polyoxazole-macrolactam intermediates 48 and 30a, respectively, towards telomestatin. Combination of the tris-oxazole based methylamine 70 with the dipeptide carboxylic acid 71 derived from D-valine and L-isoleucine
描述了对端粒他汀(1)和YM-216391(2)中连续连接的tris-恶唑单元10、11和12的收敛,互补,合成方法。该途径涉及恶唑4-羧酸,即16a,16c,16d和恶唑2-取代的甲胺,即16b,16e,17之间的偶联反应,导致酰胺18和21,然后环脱水成相应的双恶唑恶唑啉,例如19,以及使用公认的方案进行后者的氧化。接下来,将三恶唑11和12逐步转化为六恶唑双内酰胺33。虽然双大内酰胺33(cf. 28)可以转化为相应的恶唑啉-六恶唑34和烯酰胺35,这些中间体都无法修饰成七恶唑30到端粒他汀1的途径。同样,六恶唑47或44b分子内汉茨法恶唑成环反应的应用均不能使高级聚恶唑-大环内酰胺中间体48和30a进入端粒他汀。将基于三恶唑的甲胺70与衍生自D-缬氨酸和L-异亮氨酸的二肽羧酸71结合,生成相应的酰胺,该酰胺在两个简单的步骤中转化为-氨基酸78。78的内酰胺化使用HATU,接着产生环