Addition of Difluorocarbene to 4‘,5‘-Unsaturated Nucleosides: Synthesis and Deoxygenation Reactions of Difluorospirocyclopropane Nucleosides<sup>1</sup>
作者:Ireneusz Nowak、Morris J. Robins
DOI:10.1021/jo061606u
日期:2006.11.1
Synthetic routes to 4‘-(2,2-difluorospirocyclopropane) analogues of adenosine, cytidine, and uridine are described. Treatment of 2‘,3‘-O-isopropylidene-4‘,5‘-unsaturated compounds derived from adenosine and uridine with difluorocarbene (generated from PhHgCF3 and NaI) gave diastereomeric mixtures of the 2,2-difluorospirocyclopropane adducts. Stereoselectivity resulting from hindrance by the isopropylidene
描述了合成腺苷,胞苷和尿苷的4'-(2,2-二氟螺环丙烷)类似物的途径。2'治疗,3'- ö异亚丙基-4' ,5'-不饱和选自腺苷衍生和尿苷二氟卡宾与化合物(从PhHgCF产生3和NaI),得到2,2- difluorospirocyclopropane加合物的非对映体混合物。由异丙叉基的阻碍引起的立体选择性有利于在β面上添加。除去碱基和糖保护基团得到新的二氟螺环丙烷丙烷核苷类似物。通过4-(1,2,4-三唑-1-基)中间体将受保护的尿苷类似物转化为其胞苷对应物。苯乙烯基自由基介导的3'- O脱氧-TBS-2'-硫代氨基甲酸酯衍生物产生直接氢转移的2'-脱氧产物。相反,对2' - O -TBS-3'-硫代氨基甲酸酯异构体的相同处理导致在生成C3'基团时打开邻位二氟环丙烷环,然后进行均烯丙基氢转移,得到4'-(1,1-二氟乙基)-3',4'-不饱和核苷衍生物。讨论了结构方面和生物学影响因素。