Synthesis of the C7-C23 Fragment Related to Iriomoteolide-1a via B-Alkyl Suzuki-Miyaura Cross-Coupling and Indium-Mediated Aldehyde Allylation
作者:Wei-Min Dai、Yuanxin Liu、Jian Wang、Huoming Li、Jinlong Wu、Gaofeng Feng
DOI:10.1055/s-0030-1258507
日期:2010.9
Synthesis of the C7-C23 fragment and its 18R,19S-diastereomer of iriomoteolide-1a has been accomplished from the C7-C12 allyl bromide, the C13-C16 vinyl iodide, and the C17-C23 alkyl iodide fragments. These fragments were assembled first by the B-alkyl Suzuki-Miyaura cross-coupling to give the C13-C23 intermediate. The latter, after being transformed into the C13 aldehyde, was coupled to the C7-C12 allyl bromide in the presence of indium powder in THF-H2O (1:1) at 70 ËC to the fully functionalized C7-C23 fragment with orthogonal protecting groups at C19 (PMB ether), and C9, C14, and C22 (TBS, TES, and TBS ethers, respectively). Formation of the characteristic six-membered C9/C13-hemiacetal ring has been demonstrated after global desilylation using pyridine-buffered HF.
由 C7-C12 烯丙基溴、C13-C16 乙烯基碘和 C17-C23 烷基碘片段合成了虹彩内酯-1a 的 C7-C23 片段及其 18R、19S 非对映异构体。这些片段首先通过 B-烷基 Suzukii-Miyaura 交叉偶联组装,得到 C13-C23 中间体。后者转化为 C13 醛后,在铟粉存在下,于 70 ℃ 在 THF-H2O (1:1) 中与 C7-C12 溴化烯丙基偶联,得到完全官能化的 C7-C23 片段,其 C19(PMB 醚)和 C9、C14 和 C22(分别为 TBS、TES 和 TBS 醚)处带有正交保护基团。使用吡啶缓冲氢氟醚进行全局脱硅后,证明形成了特征性的六元 C9/C13 半缩醛环。