A flexible and unified strategy for syntheses of cladospolides A, B, C, and iso-cladospolide B
作者:Debjani Si、Narayana M. Sekar、Krishna P. Kaliappan
DOI:10.1039/c1ob05787a
日期:——
efficient and flexible strategy for the syntheses of cladospolides A–C and iso-cladospolide B is reported here. This strategy involves Julia–Kocienski olefination and Yamaguchi macrolactonization as key steps, starting from either D-ribose or suitable tartaric acid esters. Although our initial efforts towards cladospolide A involving a ring closing metathetic approach were not successful, changing the mode
(+)-Cladospolide C was synthesized in eight steps with 5% total yield, using methyl acrylate, (3R, 4R)-1,5-hexadiene-3,4-diol, and (6R)-6-hepten-2-ol as the starting materials. Two cross-metathesis reactions and Yamaguchi esterification were applied to assemble the three units into (+)-Cladospolide C. Unsuccessful routes using ring-closing metathesis are also discussed.
(+)Cladospolide C 通过八步反应合成,总收率为 5%,采用甲基丙烯酸酯、(3R,4R)-1,5-己二烯-3,4-二醇和 (6R)-6-庚烯-2-醇作为起始原料。通过两次交叉-转移反应和山口酯化反应,将这三个单元组装形成 (+)-Cladospolide C。此外,还讨论了使用环闭转移反应但未能成功的合成路线。
An efficient total synthesis of (+)-Cladospolide C
作者:Ch. Raji Reddy、N. Narsimha Rao
DOI:10.1016/j.tetlet.2009.03.036
日期:2009.5
The asymmetric synthesis of (+)-Cladospolide C has been achieved in 11 steps with 26% overall yield. Key steps in the sequence involve KAPA-promoted alkyne Zipper reaction, TPP-promoted enyne ester (ynoate) to diene ester (dienoate) isomerization, Sharpless asymmetric dihydroxylation and Yamaguchi macrolactonization.
De Novo Asymmetric Synthesis of Cladospolide B−D: Structural Reassignment of Cladospolide D via the Synthesis of its Enantiomer
作者:Yalan Xing、George A. O’Doherty
DOI:10.1021/ol9000119
日期:2009.3.5
The enantioselectivesynthesis of cladospolide B, C, and (ent)-cladospolide D has been achieved in 11−15 steps from 1-nonyne. The route relies upon an alkyne zipper reaction to relay an ynone and dienoate functional groups across a nine carbon fragment, which enables a highly enantioselective Noyori ynone reduction and a diastereo- and regioselective Sharpless dihydroxylation of a dienoate. In addition
general strategy for the stereoselective totalsyntheses of cladospolides A, B, and C and iso-cladospolide B has been accomplished. The key steps provide easy access to the target molecules and include an alkyne-zipper reaction, a Sharpless asymmetric epoxidation/dihydroxylation, and a Yamaguchi macrolactonization. The feasibility of the alkyne-mediatedapproach to construct the required carbon framework
已经完成了对枝条 A、B 和 C 以及异枝条 B 进行立体选择性全合成的一般策略。关键步骤提供了对目标分子的轻松访问,包括炔-拉链反应、Sharpless 不对称环氧化/二羟基化和 Yamaguchi 大环内酯化。成功证明了炔烃介导方法构建所需碳框架以及创建二醇官能团和烯烃几何结构的可行性。