Stereoselective acylation of the E,E-vinylketene silyl N,O-acetal possessing a chiral auxiliary has been achieved by using acid anhydrides and SnCl4. Acid anhydrides having alkyl chains gave the adducts in excellent stereoselectivity. The formal synthesis of khafrefungin has been accomplished by the methodology.
Total Synthesis of Biselyngbyolide B and Its C21–C22 <i>Z</i>-Isomer
作者:Lena Kämmler、Martin E. Maier
DOI:10.1021/acs.joc.8b00298
日期:2018.4.20
implementing an intramolecular Stillecoupling for macrolactonization, the 21Z-isomer of biselyngbyolide B (47) was obtained. For preparation of a C14–C23 fragment with the 21E-configuration, a cross-coupling of vinylstannane 48 with 4-bromocrotonate (49) set the configuration of the two double bonds. Biselyngbyolide B (2) was then accessed by an intramolecular Heckcoupling. In preliminary biological
Total Synthesis and Structure Revision of the Marine Metabolite Palmerolide A
作者:Xin Jiang、Bo Liu、Sylvain Lebreton、Jef K. De Brabander
DOI:10.1021/ja0715142
日期:2007.5.1
We describe a highly convergent and flexible synthesis of the novel antarctic marinemetabolite palmerolide Aan effort leading to a reformulation of palmerolide A as ent-24, the enantiomer of the C19,C20-bis-epimer of the original proposed structure 1. Our total synthesis features a highly stereoselective vinylogous Mukaiyama aldol reaction to introduce the C19,C20-stereodiad, an efficient Suzuki cross-coupling
我们描述了一种高度收敛和灵活的南极海洋代谢物palmerolide Aan 努力导致palmererolide A 重新配制为ent-24,原始提议结构的C19,C20-双差向异构体的对映异构体1。我们的全合成具有高度立体选择性的乙烯基 Mukaiyama 羟醛反应以引入 C19,C20-立体二联体,有效的 Suzuki 交叉偶联以安装内环二烯单元,以及分子内 Horner-Wadsworth-Emmons 烯化以关闭大环。从片段 2、3 (ent-3) 和 13(分别以 5 到 8 个步骤制备,总产率为 38-70%)开始,所提出的结构 1 和帕梅罗内酯 A (24) 的对映异构体的合成在额外的 14 步(最长线性序列 22 步)。
The MIDA touch: A concise and highly convergent protecting‐group‐free totalsynthesis of (−)‐myxalamide A involves a stereoselective vinylogous Mukaiyama aldol reaction of a vinylketene silyl N,O‐acetal, together with a one‐pot Stille/Suzuki–Miyaura cross‐coupling reaction using Burke's N‐methyliminodiacetic acid (MIDA) boronate to connect left‐ and right‐hand fragments of the molecule (see scheme)
Actinopyrone A (1) has been synthesized by using our developed remote stereoinduction, Kocienski olefination, Horner-Wadsworth-Emmons olefination, and reductive de-conjugation of the vinylpyrone. A concise method of O-methylation to obtain the gamma-pyrone has also been established. (c) 2006 Elsevier Ltd. All rights reserved.