Dong Shuzhi, Paquette Leo A
Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210, USA.
J Org Chem. 2005 Mar 4;70(5):1580-96. doi: 10.1021/jo048071u.
An enantioselective approach to 2'-deoxy-4'-thia spirocyclic nucleosides featuring an alpha- or beta-hydroxyl substituent at C-5' of the carbocyclic ring is detailed. The starting point is the mandelate acetal 8. The overall strategy involves the stereocontrolled dihydroxylation of this dihydrothiophene, subsequent generation of the keto acetonide 12 followed by its Meerwein-Ponndorf-Verley reduction and beta-elimination, protection of the resulting dihydroxy thiaglycal, electrophilic glycosidation according to the Haraguchi protocol, reductive removal of the phenylseleno group, and end-game global deprotection. Acquisition of the alpha- and beta-5'-isomers is equally facile. Various 1D and 2D NMR techniques are used for assigning configuration.
详细介绍了一种对碳环C-5'位具有α-或β-羟基取代基的2'-脱氧-4'-硫杂螺环核苷的对映选择性合成方法。起始原料是扁桃酸缩醛8。总体策略包括该二氢噻吩的立体控制二羟基化反应，随后生成酮缩丙酮12，接着进行麦尔外因-彭多夫-韦利还原反应和β-消除反应，对所得二羟基硫代糖进行保护，按照原口协议进行亲电糖苷化反应，还原除去苯硒基，以及最终的全局脱保护反应。获取α-和β-5'-异构体同样简便。使用各种一维和二维核磁共振技术来确定构型。
