Total Synthesis of the Didemnins; IV.<sup>1</sup>Synthesis of the Peptolide Ring and Construction of the Side Chain
作者:Ulrich Schmidt、Matthias Kroner、Helmut Griesser
DOI:10.1055/s-1991-26448
日期:——
A total synthesis of didemnins A, B, and C (1-3) which enables these highly cytotoxic cyclopeptides to be prepared in decigram amounts is described. The ß-keto acid unit (hydroxyisovaleryl)propionic acid derivative (Hip, 6) was prepared by acylation of dibenzyl methylmalonate and subsequent cleavage of the benzyl groups by the action of boron trichloride. The free ß-keto acid 6 was activated by the DCC method and allowed to react with the leucine ester 7 to furnish the amide 8. Activation, deprotection, and ring closure of the linear peptide 19 by means of the pentafluorophenyl ester method in a two-phase system gave rise to the didemnin ring skeleton in 75% yield within a few minutes. The respective side chains were then attached to the didemnin ring easily and in high yields by activation of Z-(R)-N-methylleucine as its 3-cyano-2-pyridylthiol ester followed by reaction with Z-lactylproline chloride and Z-lactic acid chloride.
描述了双德米宁 A、B 和 C (1-3) 的全合成,该合成能够以十克的量制备这些高细胞毒性环肽。 β-酮酸单元(羟基异戊酰)丙酸衍生物(Hip,6)是通过甲基丙二酸二苄酯的酰化以及随后通过三氯化硼的作用裂解苄基来制备的。通过 DCC 方法激活游离的 β-酮酸 6,并使其与亮氨酸酯 7 反应以提供酰胺 8。通过五氟苯酯方法在两个步骤中对线性肽 19 进行激活、脱保护和闭环。 -相系统在几分钟内以75%的产率产生了二德明宁环骨架。然后,通过将 Z-(R)-N-甲基亮氨酸活化为其 3-氰基-2-吡啶硫醇酯,然后与 Z-乳酰脯氨酸氯化物和 Z-乳酸反应,将各自的侧链轻松且高产率地连接到二聚宁环上酰氯。