Felix A M, Zhao Z, Lambros T, Ahmad M, Liu W, Daniewski A, Michalewsky J, Heimer E P
Roche Research Center, Hoffmann-La Roche Inc., Nutley, New Jersey, USA.
J Pept Res. 1998 Aug;52(2):155-64. doi: 10.1111/j.1399-3011.1998.tb01370.x.
A novel analog of vasoactive intestinal peptide (VIP) has been reported which exhibits high potency and enhanced duration of in vivo biological activity. This VIP analog, cyclo-(Lys21-Asp25)Ac[Glu8 Lys12 Nle17 Ala19, Asp25 Leu26,Lys27,28,Gly29,30,Thr31]-VIP, which also has a lactam bridge, has been reported to have relaxant effects that are significantly more potent than other beta-agonists such as salbutamol and salmeterol. Because it has potential use for the treatment of bronchial asthma in humans, various convergent syntheses were evaluated to enable the economic preparation of large quantities of this medium-sized hentriacontapeptide. From these studies we developed a combined solid-phase/solution synthesis which uses four protected fragments (each prepared by solid-phase synthesis with highly acid-labile resins) possessing Nalpha-9-fluorenylmethyloxycarbonyl and side-chain tert-butyl protection. Only equivalent amounts of each fragment were required to achieve near-quantitative coupling reactions using N-[(1H-benzotriazol-1-yl)(dimethylamino)methylene]-N-methylmeth anaminium hexafluorophosphate N-oxide/N-hydroxybenzotriazole. All reagents and side products were removed at each stage by simple extraction procedures. Final deprotection was carried out with 90% trifluoroacetic acid. Under these conditions only low levels of epimerization were observed (<2%). These diastereoisomers and other trace impurities were removed from the product in a single purification by preparative high-performance liquid chromatography. The procedure has been scaled up (10-g scale) and the final product obtained in an overall (nonoptimized) yield of 24%. This procedure for the repetitive coupling of fragments, without isolation of intermediates, may be generally applicable for the economic synthesis of other medium-sized and longer peptides.
据报道，一种新型的血管活性肠肽（VIP）类似物具有高效能和延长的体内生物活性持续时间。这种VIP类似物，环-（Lys21-Asp25）Ac[Glu8 Lys12 Nle17 Ala19，Asp25 Leu26，Lys27,28，Gly29,30，Thr31]-VIP，也有一个内酰胺桥，据报道其舒张作用比其他β-激动剂如沙丁胺醇和沙美特罗显著更强。由于它在治疗人类支气管哮喘方面有潜在用途，因此对各种汇聚合成方法进行了评估，以实现大量制备这种中等大小的三十一肽的经济化。通过这些研究，我们开发了一种固相/溶液组合合成方法，该方法使用四个具有Nα-9-芴甲氧羰基和侧链叔丁基保护的受保护片段（每个片段均通过使用高酸不稳定树脂的固相合成制备）。使用N-[(1H-苯并三唑-1-基)(二甲基氨基)亚甲基]-N-甲基甲铵六氟磷酸N-氧化物/N-羟基苯并三唑时，仅需要等量的每个片段就能实现近乎定量的偶联反应。在每个阶段，所有试剂和副产物都通过简单的萃取程序去除。最终脱保护使用90%的三氟乙酸进行。在这些条件下，仅观察到低水平的差向异构化（<2%）。通过制备型高效液相色谱在一次纯化中从产物中去除这些非对映异构体和其他痕量杂质。该方法已扩大规模（10克规模），最终产物的总收率（未优化）为24%。这种不分离中间体而重复偶联片段的方法可能普遍适用于其他中等大小和更长肽的经济合成。
