Expedient Synthesis of Homochiral 1-Aryl-Substituted 4,5-Dihydro-1<i>H</i>-imidazoles and Their Modification to N-Heterocyclic Carbene Precursors
作者:Christopher M. Latham、William Lewis、Alexander J. Blake、Simon Woodward
DOI:10.1002/ejoc.201403560
日期:2015.3
6-Me3C6H2] cyclise to (S) 1-aryl-substituted 4,5-dihydro-1H-imidazolinium species with HC(OEt)3 in moderate-to-excellent yields on heating to 150–175 °C (nine examples, four isolated yields of 48 to >97 %). They are attained as their o-C6H4(SO3–)(CO2Et) salts. The latter are readily deprotonated to afford analytically pure (S) 1-aryl-substituted 4,5-dihydro-1H-imidazoles (imidazolines). The purification
酰胺胺 (S)-Ar1CONHCHRCH2NHAr2 [Ar1 = o-C6H4SO3H, R = Bn, iBu, iPr; Ar2 = 2,6-iPr2C6H4, 2,6-Et2C6H4, 2,4,6-Me3C6H2] 环化成 (S) 1-芳基取代的 4,5-二氢-1H-咪唑啉鎓物种,HC(OEt)3 在温和条件下加热到 150–175 °C 时的产率非常好(九个例子,四个分离产率从 48% 到 >97%)。它们以 o-C6H4(SO3–)(CO2Et) 盐的形式获得。后者很容易去质子化,得到分析纯的 (S) 1-芳基取代的 4,5-二氢-1H-咪唑(咪唑啉)。中间体磺酸盐的纯化并不总是必要的,分析纯的咪唑啉在碱化后通过简单的 kugelrohr 蒸馏(九个例子,45-95%)分离。咪唑啉烷基化提供了一个 (S)-N-烷基咪唑啉盐库(23 个实例,74-97%)。