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.