作者:Brendan M. Crowley、Yoshiki Mori、Casey C. McComas、Datong Tang、Dale L. Boger
DOI:10.1021/ja039795a
日期:2004.4.1
The first total synthesis of the ristocetin aglycon is described employing a modular and highly convergent strategy. An effective 12-step (12% overall) synthesis of the ABCD ring system 3 from its amino acid subunits sequentially features an intramolecular aromatic nucleophilic substitution reaction for formation of the diaryl ether and closure of the 16-membered CD ring system (65%), a respectively
采用模块化和高度收敛的策略描述了瑞斯托菌素苷元的首次全合成。ABCD 环系统 3 从其氨基酸亚基的有效 12 步(总体 12%)合成依次具有分子内芳香亲核取代反应,用于形成二芳基醚和 16 元 CD 环系统的闭合(65%) ,分别为非对映选择性 (3:1, 86%) Suzuki 偶联,用于安装可进一步热调节阻转异构体立体化学的 AB 联芳基键,以及用于闭合 12 元 AB 环系统的有效大环内酰胺化 (51%) .
Efficient synthesis of deuterium- and tritium-labeledd-erythro-sphingosine
作者:Shengrong Li、Jihai Pang、William K. Wilson、George J. Schroepfer
Deuterium- and tritium-labeled d-erythro-sphingosine (1b and 1c) were prepared by an efficient approach based on a known stereoselective total synthesis. Tritium was introduced at C−1 by [3H]NaBH4 reduction in the final synthetic step to give 1c of high radiochemical purity. 1,1,3-Trideuterio-d-erythro-sphingosine (1b) was prepared similarly and showed >99·5% enantiomeric purity and a high level of
A general, efficient and stereospecific route to sphingosine, sphinganines, phytosphingosines and their analogs
作者:Ye Cai、Chang-Chun Ling、David R. Bundle
DOI:10.1039/b516333a
日期:——
Sphingosine, sphinganines and phytosphingosines and their analogs were synthesized by an aldol condensation between an iminoglycinate bearing a (+)-(1R,2R,5R)-2-hydroxy-3-pinanone group as chiral auxiliary and an appropriate aldehyde. All condensations proceeded with excellent enantioselectivity to generate the (2S,3R)-D-erythro structures in good yields.
The Hydroxypinanone as Chiral Auxiliary in Michael Additions: an Inversion of Diastereoselectivity at Low Concentration of Enolate, a Substrate-Directed Approach
Inversion of diastereoselectivity (from 90-98% S to 90-95% R) was observed for Michael additions as a function of the starting chiral enolate concentration. It is also shown that catalytic amount of a phosphazene base (t-Oct-P2) allowed rapid reaction (1h), total conversion and high (90%) R-diastereoselectivity.
观察到迈克尔加成反应的非对映选择性(从 90-98% S 到 90-95% R)与起始手性烯酸盐浓度的函数关系。研究还表明,催化量的膦烯基(t-Oct-P2)可实现快速反应(1 小时)、完全转化和高(90%)R-非对映选择性。
An Efficient Synthesis of Sulfobacin A (Flavocristamide B), Sulfobacin B, and Flavocristamide A
作者:Takayuki Shioiri、Naoko Irako
DOI:10.1016/s0040-4020(00)00768-7
日期:2000.11
Sulfobacin A (flavocristamide B, 1), sulfobacin B (2), and flavocristamide A (3), biologically active sulfonolipids, have been efficiently synthesized utilizing the asymmetric aldol reaction of the Schiff base 8 derived from glycine eater and (+)-2-hydroxy-3-pinanone (HyPN). (C) 2000 Elsevier Science Ltd. All rights reserved.