TCFH–NMI: Direct Access to <i>N</i>-Acyl Imidazoliums for Challenging Amide Bond Formations
作者:Gregory L. Beutner、Ian S. Young、Merrill L. Davies、Matthew R. Hickey、Hyunsoo Park、Jason M. Stevens、Qingmei Ye
DOI:10.1021/acs.orglett.8b01591
日期:2018.7.20
Challenging couplings of hindered carboxylic acids with non-nucleophilic amines to form amide bonds can be accomplished in high yields, and in many cases, with complete retention of the adjacent stereogenic centers using the combination of N,N,N′,N′-tetramethylchloroformamidinium hexafluorophosphate (TCFH) and N-methylimidazole (NMI). This method allows for in situ generation of highly reactive acyl imidazolium
具有挑战性的受阻羧酸与非亲核胺形成酰胺键的偶联可以高收率完成,而且在许多情况下,使用N,N,N ',N'-四甲基氯甲ami的组合完全保留相邻的立体异构中心六氟磷酸盐(TCFH)和N-甲基咪唑(NMI)。该方法允许原位产生高反应性的酰基咪唑鎓离子,其已被证明是反应的中间体。该试剂具有类似于酰基氯的高反应活性,并且易于使用现代铀试剂。