公开了一种用于全合成去甲软骨素 B 的新合成策略,该策略具有高度收敛的方法和我们最近公开的用于合成环醚结构基序的反向方法。导致迄今为止公开的去甲软硬脂素 B 的最短途径,所报道的全合成是通过合成两个几乎同样复杂的片段来实现的,这些片段的偶联和短细化序列的特点是 C16 立体中心的基本差向异构化与简单的酸诱导的脱保护同时发生,一种基于合成路线先前研究的策略。这种在软软骨素家族天然产物中前所未有的策略可以在其他或多或少复杂的天然或设计的软软骨素类似物的合成中找到实际应用。
Asymmetric Ni(II)/Cr(II)-Mediated Coupling Reaction: Stoichiometric Process
作者:Zhao-Kui Wan、Hyeong-wook Choi、Fu-An Kang、Katsumasa Nakajima、Damtew Demeke、Yoshito Kishi
DOI:10.1021/ol0269805
日期:2002.12.1
[reaction: see text] Via an X-ray analysis, the sulfonamide bearing R(1) = i-Pr, R(2) = Me, and R(3) = Me is shown to be a tridentate ligand to a Cr(III) salt. This class of ligands, represented by R(1) = t-Bu, R(2) = 2-naphthyl, and R(3) = Me, is effective to achieve an asymmetricNi/Cr-mediated couplingreaction and, with the C14-C38 segment of halichondrins, its synthetic potential has been demonstrated
New Syntheses of E7389 C14−C35 and Halichondrin C14−C38 Building Blocks: Reductive Cyclization and Oxy-Michael Cyclization Approaches
作者:Cheng-Guo Dong、James A. Henderson、Yosuke Kaburagi、Takeo Sasaki、Dae-Shik Kim、Joseph T. Kim、Daisuke Urabe、Haibing Guo、Yoshito Kishi
DOI:10.1021/ja9058487
日期:2009.11.4
coupling partners. The C23-O bond is stereospecifically constructed via reductive cyclization of the oxonium ion, or oxy-Michael cyclization. Both syntheses have a high overall efficiency: E7389 C14-C35 and halichondrin C14-C38 building blocks have been synthesized from the corresponding C27-C35 and C27-C38 aldehydes, respectively, in high overall yields with an excellent stereoselectivity. Because of