作者:Yu. M. Yutilov、Kh. Ya. Lopatinskaya、N. N. Smolyar、S. V. Gres’ko
DOI:10.1007/s11178-005-0186-y
日期:2005.3
Halogenation of 2-unsubstituted and 2-methylimidazo[4,5-b]pyridines and their N-methyl derivatives with bromine and chlorine in acetic acid takes different pathways, depending on the acetic acid concentration. The bromination in 50% aqueous acetic acid gives only 6-bromoimidazo[4,5-b]pyridines; bromination and chlorination of 2-unsubstituted imidazo[4,5-b]pyridines in glacial acetic acid leads to 5,6-dibromo(dichloro)imidazo[4,5-b]pyridin-2-ones, and bromination of 2-methylimidazo[4,5-b]pyridines in glacial acetic acid involves both the pyridine ring and the 2-methyl group to afford the corresponding 6-bromo-2-tribromomethylimidazo[4,5-b]pyridines.
在乙酸中用溴和氯对 2-未取代的和 2-甲基咪唑并[4,5-b]吡啶及其 N-甲基衍生物进行卤化,根据乙酸浓度的不同,卤化途径也不同。在 50% 的乙酸水溶液中进行溴化反应只能得到 6-溴咪唑并[4,5-b]吡啶;在冰醋酸中对 2-未取代的咪唑并[4,5-b]吡啶进行溴化和氯化反应,可生成 5,6-二溴(二氯)咪唑并[4,5-b]吡啶-2-酮;在冰醋酸中对 2-甲基咪唑并[4,5-b]吡啶进行溴化反应,可生成 2-甲基咪唑并[4,5-b]吡啶-2-酮、2-甲基咪唑并[4,5-b]吡啶在冰乙酸中的溴化反应涉及吡啶环和 2-甲基,从而得到相应的 6-溴-2-三溴甲基咪唑并[4,5-b]吡啶。