Unified Synthesis of C19−C26 Subunits of Amphidinolides B1, B2, and B3 by Exploiting Unexpected Stereochemical Differences in Crimmins' and Evans' Aldol Reactions
摘要:
The efficient synthesis of the C-19-C-26 subunit of amphidinolide B-1 and B-2 has been completed using a boron-mediated aldol reaction. The synthesis of the C-19-C-26 subunit of amphidinolide B-3 has also been accomplished through an unexpected anti aldol reaction using a titanium-mediated process. In addition, the first reported examples of a stereochemical discrepancy between the Evans' boron-mediated oxazolidinone and the Crimmins' titanium-mediated oxazolidinethione aldol reactions are disclosed. A working hypothesis is put forth to explain the results.
Unified Synthesis of C19−C26 Subunits of Amphidinolides B1, B2, and B3 by Exploiting Unexpected Stereochemical Differences in Crimmins' and Evans' Aldol Reactions
摘要:
The efficient synthesis of the C-19-C-26 subunit of amphidinolide B-1 and B-2 has been completed using a boron-mediated aldol reaction. The synthesis of the C-19-C-26 subunit of amphidinolide B-3 has also been accomplished through an unexpected anti aldol reaction using a titanium-mediated process. In addition, the first reported examples of a stereochemical discrepancy between the Evans' boron-mediated oxazolidinone and the Crimmins' titanium-mediated oxazolidinethione aldol reactions are disclosed. A working hypothesis is put forth to explain the results.
unselective “chemist” when it comes to making the highly cytotoxic amphidinolide macrolides of the B/G/H series. To date, 16 different such compounds have been isolated, all of which could now be approached by a highly convergent and largely catalysis‐based route (see figure). This notion is exemplified by the total synthesis of five prototype members of this family.
在生产具有高细胞毒性的B / G / H系列安非他命类大环内酯类药物时,自然界是一个非选择性的“化学家”。迄今为止,已分离出16种不同的此类化合物,现在可以通过高度聚合且主要基于催化作用的途径来接近所有这些化合物(见图)。该族的五个原型成员的总合成就是这一概念的例证。