Synthesis of 3‘-Deoxynucleosides with 2-Oxabicyclo[3.1.0]hexane Sugar Moieties: Addition of Difluorocarbene to a 3‘,4‘-Unsaturated Uridine Derivative and 1,2-Dihydrofurans Derived from <scp>d</scp>- and <scp>l</scp>-Xylose<sup>1</sup>
作者:Ireneusz Nowak、Morris J. Robins
DOI:10.1021/jo062614d
日期:2007.4.1
Syntheses of 3‘-deoxy analogues of adenosine, cytidine, and uridine with a 2,2-difluorocyclopropane ring fused at C3‘−C4‘ are described. Treatment of a 2‘,5‘-protected-3‘,4‘-unsaturated derivative of uridine with difluorocarbene [generated from (CF3)2Hg and NaI] gave a diastereomeric mixture of the 3‘,4‘-difluoromethylene compounds (α-l-arabino/β-d-ribo, ∼5:4). The limited stereoselectivity for addition
描述了腺苷,胞苷和尿苷的3'-脱氧类似物与在C3'-C4'稠合的2,2-二氟环丙烷环的合成。用二氟卡宾[由(CF 3)2 Hg和NaI生成]处理尿苷的2',5'-保护的3',4'-不饱和衍生物,得到3',4'-二氟亚甲基化合物的非对映异构体混合物( α- 1-阿拉伯糖/β- d-核糖,〜5:4)。在β面上添加的有限立体选择性是由于α面上C2'处的烯丙基4-甲氧基苄氧基和β面上C1'处的均烯丙基核碱基具有竞争性的位阻。通过4-(1,2,4-三唑-1-基)中间体将受保护的尿嘧啶衍生物转化为它们的胞嘧啶对应物。衍生自1,2-二氢呋喃的处理带有二氟卡宾的d-和l-木糖导致在β面上立体定向加成(与α面上的1,2- O-异亚丙基相反)。在β面上带有稠合的二氟环丙烷环的活化对映体糖衍生物的糖基化作用可得到受保护的腺嘌呤核苷,而与α稠合的衍生物进行糖基化尝试可得到多种产物。除去碱基和糖保护基团得到新的二氟亚甲基桥连的核苷类似物。