ABSTRACT An efficient Pd2(dba)3-catalyzed amination of C5-bromo-imidazo[2,1-b][1,3,4]thiadiazole using conventional heating is reported. The C5-bromoimidazo[2,1-b][1,3,4]thiadiazole was synthesized using a multistep approach which started by cyclization of thiosemicarbazide with a carboxylic acid to give 2-amino[1,3,4]thiadiazoles which were further treated with 2-haloketones to give imidazo[2,1-b][1,3,4]thiadiazoles. Then, the bromination of imidazothiadiazole was done using N-bromosuccinimide to give the C5-bromo-imidazo[2,1-b][1,3,4]thiadiazole. Afterward, various C-N bond-forming approaches were attempted such as SNAr, Cu(I), Cu(II), Pd(OAc)2, Pd2(dba)3 catalyst with different ligand, additive, base, solvent and temperature conditions. Out of various approaches used, only Buchwald Hartwig amination, performed with conventional heating, gave N-arylamine-5-imidazothiadiazoles. Then, 10 different anilines with different electron-withdrawing and donating groups at different positions were employed to examine the scope and limitations of the method. Salient features of this method include conventional heating in a Schlenk tube as the reaction condition, the absence of the use of toxic isocyanides, the wide nature of substituent tolerance with anilines, and moderately good product yields. GRAPHICAL ABSTRACT

中文翻译：

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在 Schlenk 管中常规加热下 Pd2(dba)3 催化 C5-溴-咪唑并[2,1-b][1,3,4] 噻二唑与取代苯胺的胺化

摘要报道了使用常规加热有效 Pd2(dba)3 催化的 C5-溴-咪唑并 [2,1-b][1,3,4] 噻二唑胺化。C5-溴咪唑并[2,1-b][1,3,4]噻二唑是使用多步方法合成的，该方法开始于氨基硫脲与羧酸的环化，得到2-氨基[1,3,4]噻二唑。进一步用 2-卤代酮处理得到咪唑并[2,1-b][1,3,4]噻二唑。然后，使用 N-溴代琥珀酰亚胺进行咪唑并噻二唑的溴化，得到 C5-溴-咪唑并 [2,1-b][1,3,4] 噻二唑。随后，尝试了各种 CN 键形成方法，例如 SNAr、Cu(I)、Cu(II)、Pd(OAc)2、Pd2(dba)3 催化剂，具有不同的配体、添加剂、碱、溶剂和温度条件。在使用的各种方法中，只有 Buchwald Hartwig 胺化，使用传统加热进行，得到 N-芳胺-5-咪唑并噻二唑。然后，采用10种在不同位置具有不同吸电子和给电子基团的不同苯胺来检查该方法的范围和局限性。该方法的显着特点包括在 Schlenk 管中作为反应条件的常规加热、不使用有毒异氰化物、苯胺的取代基耐受性的广泛性质以及中等良好的产品收率。图形概要 苯胺的取代基耐受性广泛，产品收率中等。图形概要 苯胺的取代基耐受性广泛，产品收率中等。图形概要