New facile enantio- and diastereo-selective syntheses of (−)-triptonide and (−)-triptolide
作者:Hongrui Zhang、Haifeng Li、Jijun Xue、Rui Chen、Ying Li、Yu Tang、Chunxin Li
DOI:10.1039/c3ob42183j
日期:——
A novelformal asymmetric synthesis of (−)-triptonide and (−)-triptolide, featuring a new alternative access to their known key intermediate 4, has been achieved through two synthetic routes in 9 steps with 13.6% total yield and 10 steps with 18.5% overall yield, respectively. This synthesis is scalable and hence has high potential for application to further synthetic elaboration and biologic investigation
reaction were elongated to β-oxo esters that were first reduced to β-hydroxy esters and then transformed into protected β-hydroxy aldehydes. Wittig–Horner–Emmons reaction with the anion of tetraisopropylmethylenebisphosphonate gave, after deprotection, the desired 4-hydroxy-6-purinyl- or -6-pyrimidinyl-1-hexenylphosphonic acids. A dimer, potential precursor of acyclic polynucleotides (APN), homomorphous with
已从 DNA 核碱基和丙烯酸叔丁酯开始制备了以天然脱氧核糖核苷酸为模型的无环卡巴核苷膦酸酯。从迈克尔型反应获得的产物被延长为 β-氧代酯,该酯首先被还原为 β-羟基酯,然后转化为受保护的 β-羟基醛。Wittig-Horner-Emmons 与亚甲基双膦酸四异丙酯的阴离子反应,去保护后得到所需的 4-羟基-6-嘌呤基-或-6-嘧啶基-1-己烯基膦酸。还制备了一种二聚体,一种与 DNA 同形的无环多核苷酸 (APN) 的潜在前体。
Stereoselective Synthesis of the ABC Ring System of Norzoanthamine
作者:Subhash Ghosh、Fatima Rivas、Derek Fischer、Miguel A. González、Emmanuel A. Theodorakis
DOI:10.1021/ol036492c
日期:2004.3.1
[reaction: see text] An efficient synthesis of enone 4, representing the ABCring motif of norzoanthamine, is presented. The crucial C22 quaternary center was introduced via a stereoselective methylation of enone 8. The trans-anti-trans relative configuration of the ABC framework of 4 was installed via a sequence of reactions that included a hydroboration and a modified Robinson annulation.
The synthesis of angular methyl substituted bicyclic enones via a unique regioselective enamine annulation reaction
作者:W.M.B. Könst、J.G. Witteveen、H. Boelens
DOI:10.1016/0040-4020(76)85022-3
日期:1976.1
Enamines of 2,4,4-trimethylcyclopentanone 5 and of 2,5,5-trimethylcyclohexanone 14 react with methyl vinyl ketone to afford the bicyclic enones 9 and 15 in yields up to 70%. The formation of these products bearing an angular Me group is the result of an anomalous enamine Robinson annulation reaction, due to an alkylation of the enamine in the first step at its most substituted α-position. The effect