通过与1-溴戊-3-烯的格氏反应,使用2-(2,2-二甲基-1,3-二恶烷-4-基)乙醛(3)制备链烯醇A和B(方案1)。特此光学纯(4' - [R )- 3,得到Streptenol A.反应的对映体与锂化的1-戊炔打开访问streptenol C和D为获得streptenol C和d的二烯酮结构,钯催化的炔酮异构化诱导。1,3-丙酮化物保护的1,3,5-三醇系统在酸介导的裂解中的动力学差异导致了天然产物的立体选择性。所以只有(3 S *,5 R *)链烯醇B的丙酮化物在温和的水解条件下反应,并在缩醛化后首先提供具有相对相对立体化学的3,5-保护的链烯醇B,最后是(3 S *,5 R *)-链烯醇B.
Design, synthesis and biological evaluation of bridged epothilone D analogues
作者:Qiao-Hong Chen、Thota Ganesh、Peggy Brodie、Carla Slebodnick、Yi Jiang、Abhijit Banerjee、Susan Bane、James P. Snyder、David G. I. Kingston
DOI:10.1039/b814823f
日期:——
Six epothilone D analogues with a bridge between the C4-methyl and the C12-methyl carbons were prepared in an attempt to constrain epothilone D to its proposed tubulin-binding conformation. Ring-closing metathesis (RCM) was employed as the key step to build the C4–C26 bridge. In antiproliferative assays in the human ovarian cancer (A2780) and prostate cancer (PC3) cell lines, and also in tubulin assembly assay, all these compounds proved to be less active than epothilone D.
The enantioselective synthesis of simplified southern-half fragments of soraphen A
作者:Bernard Loubinoux、Jean-Luc Sinnes、Anthony C. O'Sullivan、Tammo Winkler
DOI:10.1016/0040-4020(95)00098-s
日期:1995.3
comprises a southern-half subunit of the fungicidal macrolide soraphen A 1. It was prepared by a Meinwald reaction of the enolate of S-7 with the lactone S-8. Its enantiomer and diastereomers were synthesized in a similar manner. The lactone S-8 and its enantiomer R-8 were prepared by three different routes, including the enantioselective catalytic reduction of the β-keto ester 17. These lactones are
Construction of protected hydroxylated pyrrolidines using nitrogen-centered radical cyclizations
作者:Huimin Zhai、Maria Zlotorzynska、Glenn Sammis
DOI:10.1039/b914757h
日期:——
Nitrogen-centered radical cyclizations onto silyl enol ethers were utilized for the syntheses of protected polyhydroxylated pyrrolidines 2-hydroxymethyl-3-hydroxypyrrolidine and 1,4-dideoxy-1,4-imino-L-ribitol.
[EN] NON-MYELOSUPPRESSIVE COMPOUNDS, PHARMACEUTICAL COMPOSITIONS THEREOF, AND METHODS OF TREATMENT<br/>[FR] COMPOSÉS NON MYÉLOSUPPRESSEURS, LEURS COMPOSITIONS PHARMACEUTIQUES, ET PROCÉDÉS DE TRAITEMENT
The cyclization of nitrogen-centered radicals onto silyl enol ethers is an efficient method for the synthesis of polyhydroxylated alkaloids as the 2-hydroxymethylpyrrolidine core can be readily accessed from a linear precursor. During our studies on the synthesis of polyhydroxylated alkaloid CYB-3, we found that the diastereoselectivity of the cyclization was dependent on a complex combination of sterics