Metal-Bearing and Trifluoromethyl-Substituted Pyrimidines: Generation and Functionalization
作者:Manfred Schlosser、Olivier Lefebvre、Levente Ondi
DOI:10.1002/ejoc.200500848
日期:2006.3
yl)pyrimidine are deprotonated with lithium diisopropylamide before being allowed to react with dry ice. In contrast, consecutive treatment of 2-bromo-4-(trifluoromethyl)pyrimidine and 2-chloro-5-iodo-4-(trifluoromethyl)pyrimidine with butyllithium affords the expected carboxylic acids in only poor yields and not even trace amts. of acid were detected when 4-bromo-6-(trifluoromethyl)pyrimidine served
当金属两侧有两个吸电子取代基(如三氟甲基和氯或溴)时,5-嘧啶基锂物种相当稳定。因此,在用异丙基氯化镁完成卤素/金属置换后,由 4,5-二溴-6-(三氟甲基)嘧啶和 5-溴-4-氯-6-(三氟甲基)嘧啶以高产率生产相应的 5-羧酸或丁基锂,然后羧化。当 4-氯-、2,4-二氯-和 2,4-二溴-6-(三氟甲基)嘧啶在与干冰反应之前用二异丙基氨基锂去质子化时,同样获得令人满意或优异的 5-羧酸产率. 相比之下,用丁基锂连续处理 2-bromo-4-(trifluoromethyl)pyrimidine 和 2-chloro-5-iodo-4-(trifluoromethyl)pyrimidine 得到了预期的羧酸,收率很低,甚至没有痕量的 amts。当 4-溴-6-(三氟甲基)嘧啶作为底物时,检测到酸。从两个相互竞争的机制途径中的任何一个中出现的双嘧啶的形成是一种永久性的有害副反应。[在 SciFinder