Synthesis of 1,9-Diazaphenoxazine Carboxamide Derivatives via Buchwald-Hartwig Amidation Protocol
作者:O.L. Edoka、U.C. Okoro、D.I. Ugwu
DOI:10.14233/ajchem.2015.18902
日期:——
Tandem amidation catalyzed synthesis of linear diazaphenoxazine carboxamide derivatives (18a-e) is reported. This was achieved by the reaction of 2-amino-3-hydroxypyridine (11) and 2,3,5-trichloropyridine (12) in aqueous basic medium to afford 3-chloro-1,9-diazaphenoxazine (13) as white solid crystals. Compound 13 was then subjected to Buchwald-Hartwig amidation coupling reaction with various carboxamides (17a-e) in the presence of 1,4-bis(2-hydroxyl-3,5-di-tert-butyl benzyl)piperazine (16) as ligand, Pd(OAc)2 as palladium source catalyst, K2CO3 as base and 50:50 DMF and toluene as solvent at 110 ºC for 2 h to afford the linear diazaphenoxazine carboxamide derivatives (18a-e) in good to excellent yield. The water mediated pre-activation of the catalyst was monitored visually using colour change from yellow to black. The compounds were characterized using UV-visible, FTIR, 1H NMR, 13C NMR spectroscopy and elemental analysis.
报道了一种通过串联酰胺化催化合成线性二氮苯并噁嗪羧酰胺衍生物(18a-e)的方法。该反应是通过在水性的碱性介质中将2-氨基-3-羟基吡啶(11)与2,3,5-三氯吡啶(12)反应,得到白色固体晶体3-氯-1,9-二氮苯并噁嗪(13)。然后,将化合物13与各种羧酰胺(17a-e)在含有1,4-二(2-羟基-3,5-二叔丁基苄基)哌嗪(16)作为配体,Pd(OAc)2作为钯源催化剂,K2CO3作为碱,在110 ºC下,使用50:50 DMF和甲苯作为溶剂反应2小时,获得了线性二氮苯并噁嗪羧酰胺衍生物(18a-e),产率良好至优异。催化剂的水介导预活化通过颜色从黄色变为黑色进行可视监测。使用UV-可见、FTIR、1H NMR、13C NMR光谱和元素分析对化合物进行了表征。