A highly convergent synthesis of archazolid B, a potent and highly selective V-ATPase inhibitor, is described. A relay ring-closing metathesis reaction was used to form the 24-membered macrocyclic lactone, whereas the sensitive cis-triene moiety of the archazolids was assembled with a modified Stille coupling.
Highly Regio- and Stereoselective Synthesis of (Z)-Trisubstituted Alkenes via Propyne Bromoboration and Tandem Pd-Catalyzed Cross-Coupling
摘要:
Contrary to all previous reports, bromoboration of propyne with BBr3 proceeds in >= 98% syn-selectivity to produce (Z)-2-bromo-1-propenyldibromoborane (1). Although 1 is readily prone to stereoisomerization, it can be converted to the pinacolboronate (2) of >= 98% isomeric purity by treatment with pinacol, which may then be subjected to Negishi coupling to give trisubstituted (Z)-alkenylpinacolboronates (3) containing various R groups in 73-90% yields. Iodinolysis of 3 affords alkenyl iodides (4) in 80-90% yields. All alkenes isolated and identified are >= 98% Z
Synthesis of Diastereomerically and Enantiomerically Pure 2,3-Disubstituted Tetrahydrofurans Using a Sulfoxonium Ylide
作者:Jennifer M. Schomaker、Veera Reddy Pulgam、Babak Borhan
DOI:10.1021/ja0469075
日期:2004.10.1
via Sharpless asymmetric epoxidation chemistry, offer access to a wide variety of enantiomerically pure compounds. In this communication, we describe the use of a Payne rearrangement to control regioselectivity in the ring-opening of a series of 2,3-epoxy alcohols with dimethylsulfoxonium methylide to yield diastereomerically and/or enantiomerically pure disubstituted tetrahydrofuran rings. The factors
Highly Stereoselective Total Synthesis of Fully Hydroxy-Protected Mycolactones A and B and Their Stereoisomerization upon Deprotection
作者:Guangwei Wang、Ning Yin、Ei-ichi Negishi
DOI:10.1002/chem.201002627
日期:2011.4.4
Unprecedentedly efficient and highly (≥98 %) stereoselective syntheses of mycolactones A and Bsidechains relied heavily on Pd‐catalyzed alkenylation (Negishi version) and were completed in 11 longest linear steps from ethyl (S)‐3‐hydroxybutyrate in 12 % and 11 % overall yield, respectively, roughly corresponding to an average of 82 % yield per step. The synthesis of mycolactone core was realized by using Pd‐catalyzed
真菌内酯 A 和 B 侧链的前所未有的高效和高度(≥98 %)立体选择性合成严重依赖于 Pd 催化的烯基化(Negishi 版本),并在 11 个最长的线性步骤中完成,从12% 的( S )-3-羟基丁酸乙酯和分别为 11% 的总产率,大致对应于每步平均 82% 的产率。Mycolactone核心的合成是通过使用Pd催化的烯基烯丙基偶联和与三烷基烯基铝酸盐的环氧化物开环反应作为关键步骤来实现的。首次成功合成了异构纯度≥98%的完全羟基保护的支链菌内酯A和B。然而,在脱保护后获得了出乎意料的 4:3-5:4 不可分离的支链内酯 A 和 B 混合物。