High-yielding syntheses of 4(5)-substituted imidazoles via organolithium intermediates. the utility of sulphonamide n-protection and silicon-containing blocking groups
作者:Andrew J. Carpenter、Derek J. Chadwick
DOI:10.1016/s0040-4020(01)90617-9
日期:1986.1
-Protection of imidazole as its ,-dimethyl-sulphonamido derivative, and blocking of the 2-position with the triethylsilyl group permits regioselective 5-metallation with sec-butyl-lithium. The resulting organolithium intermediates react with a range of electrophiles and the products are easily deprotected to give the 4(5)-substituted NH-free imidazoles in good to excellent yields. Isolation of the
咪唑作为其,-二甲基-磺酰胺基衍生物的保护,以及用三乙基甲硅烷基封端2-位,可以与仲丁基锂进行区域选择性的5-金属化。所得的有机锂中间体与一定范围的亲电子试剂反应,产物易于脱保护,从而以良好或优异的产率得到4(5)-取代的不含NH的咪唑。硅封闭的中间体的分离是不必要的,并且实际上不利于最终收率,这使得该过程明显节省了时间。