Diastereocontrol in Radical Addition to β-Benzyloxy Hydrazones: Revised Approach to Tubuvaline and Synthesis of <i>O</i>-Benzyltubulysin V Benzyl Ester
作者:Manshu Li、Koushik Banerjee、Gregory K. Friestad
DOI:10.1021/acs.joc.1c01798
日期:2021.11.5
N-acylhydrazones has generated unusual amino acids tubuphenylalanine (Tup) and tubuvaline (Tuv) that are structural components of the tubulysin family of picomolar antimitotic agents and previously led to a tubulysin tetrapeptide analog with a C-terminal alcohol. To improve efficiency in this synthetic route to tubulysins, and to address difficulties in oxidation of the C-terminal alcohol, here we present two alternative
手性N-酰基腙的自由基加成生成了不寻常的氨基酸 tubuphenalanine (Tup) 和 tubuvaline (Tuv),它们是皮摩尔抗有丝分裂剂微管蛋白抑制剂家族的结构成分,之前产生了具有 C 末端醇的微管蛋白抑制剂四肽类似物。为了提高微管蛋白抑制剂合成路线的效率,并解决 C 末端醇氧化的困难,我们在此提出了两种 Tuv 的替代路线,(a) 提高步骤经济性,(b) 为 Mn 介导的自由基提供改进的条件(c) 揭示了在自由基加成到 β-苄氧基腙中的双非对映控制的例子,对通过自由基加成合成不对称胺具有更广泛的影响。有效的偶联序列提供 11- O-苄基微管蛋白 V 苄酯。