Diastereospecific synthesis of 2′- or 3′-c-branched nucleosides through intramolecular free-radical capture by silicon-tethered acetylene
作者:Zhen Xi、Jianhui Rong、Jyoti Chattopadhyaya
DOI:10.1016/s0040-4020(01)90435-1
日期:1994.4
tethered acetylene function in a ribonucleoside 2a, 2b, 2c, 8a, 8b or 8c gave only the [3.3.0]-cis-fused Z-vinylsiloxane 3a, 3b, 3c, 9a, 9b or 9c (&>90%) in a diastereospecific manner. The temporary silicon connection from the Z-vinylsiloxane was removed by the oxidation to give the 2′- or 3′-C-branched α-keto-,β-D-ribonucleoside (∼85%), which was diastereospecifically reduced to give 1,3-syn diol (&>90%
通过硅系乙炔官能团在核糖核苷2a,2b,2c,8a,8b或8c中进行的分子内自由基捕获仅提供了[3.3.0]-顺式稠合的Z-乙烯基硅氧烷3a,3b,3c,9a,9b或9c(&> 90%)以非对映形式。Z-乙烯基硅氧烷的临时硅连接通过氧化除去,得到2'-或3'-C支链的α-酮-,β-D-核糖核苷(〜85%),其经非对映特异性还原得到1 ,3-同二醇(> 90%,&> 97%ee)[2'-或3'-C-支链-α-取代的R或S-羟甲基-β-D-核糖核苷5a,5b,5c,11a,11b或11c ]。这些是使用硅系链的方法通过5-trig-exo自由基环化,高度非对映特异性合成2'-或3'-C分支的核糖核苷的第一个例子。