Divergent and Regioselective Synthesis of 1,2,4- and 1,2,5-Trisubstituted Imidazoles
作者:Bruno Delest、Prosper Nshimyumukiza、Olivier Fasbender、Bernard Tinant、Jacqueline Marchand-Brynaert、Francis Darro、Raphaël Robiette
DOI:10.1021/jo801256b
日期:2008.9.1
reaction with methyl triflate, selective formation of the corresponding 1,2,5-trisubsituted 1H-imidazole is observed. NMR studies have revealed that this regioselectivity can be accounted for by in situ rapid isomerization of 10 into its 1,2,4-isomer (13) followed by regiospecific N-alkylation of the latter. Conversely, when key intermediate 10 is slowly added to Meerwein's salt, isomerization can be constrained
已经开发了从容易获得的(两步)通用中间体中发散和区域选择性合成1,2,4-和1,2,5-三取代的咪唑的方法。该方法基于1-(N,N-二甲基氨磺酰基)-5-碘-2-苯基硫基-1H-咪唑的区域控制性N-烷基化(10)。当该中间体与三氟甲磺酸甲酯反应时,观察到选择性形成了相应的1,2,5-三取代的1H-咪唑。NMR研究表明,这种区域选择性可以通过将10原位快速异构化为其1,2,4-异构体(13),然后对其进行区域特异性N-烷基化来解决。相反,当将关键中间体10缓慢添加到Meerwein盐中时,异构化会受到限制,区域10的区域特异性N-烷基化会导致1,2,4-三取代的1H-咪唑具有高选择性。