Synthetic Studies on Gambieric Acids, Potent Antifungal Polycyclic Ether Natural Products: Reassignment of the Absolute Configuration of the Nonacyclic Polyether Core by NMR Analysis of Model Compounds
A/B-ring model compounds led to a stereochemical reassignment of the absolute configuration of the polycyclic ether core of GAs. This structure revision was further supported by a synthesis of the A/BC-ring model compound of gambieric acid B and a comparison of its 1H and 13C NMR data with those of the natural product.
基于(i)C1-C6烷基硼酸酯和C7-C17乙烯基碘的Suzuki-Miyaura偶联和( ii)非对映选择性的卤代醚化反应,是构建A环四氢呋喃的关键步骤。对合成的A / B环模型化合物的1 H和13 C NMR化学位移的检查导致GAs多环醚核的绝对构型的立体化学重新分配。冈比亚酸B的A / BC环模型化合物的合成以及其1 H和13 C NMR数据与天然产物的比较,进一步支持了该结构修订。