Microwave-assisted one step high-throughput synthesis of benzimidazoles

Synthesis of substituted 2-(β-d-glucopyranosyl)-benzimidazoles and their evaluation as inhibitors of glycogen phosphorylase

“…C-(b-D-Glucopyranosyl)formic acid 5, prepared from cyanide 2 via amide 3 43 by the literature protocol 44 (Table 1), was reacted with 1,2-diaminobenzenes (a, f, h) in the presence of triphenylphosphite in pyridine under microwave irradiation (conditions were adapted from a published procedure applied for non-sugar based com-120 pounds 45 ). Although the conversions were complete at 140°C in 20 min, the desired products could be isolated only in moderate yields (8a: 45%, 8f: 53%, 8h: 43%).…”

Wells–Dawson Heteropolyacid: An Efficient Recyclable Catalyst for the Synthesis of Benzimidazoles Under Microwave Condition

“…Various oxidative reagents, such as nitrobenzene, benzoquinone, sodium metabisulfite, mercuric oxide, lead tetraacetate, iodine, copper (II) acetate, indium perfluorooctane sulfonates, ytterbium perfluorooctane sulfonates, and even air, have been employed for this purpose [26]. Moreover, a variety of benzimidazoles could also be produced via coupling of 1, 2-diaminobenzenes with carboxylic acid derivatives such as nitriles, imidates, orthoesters, anhydrides or lactones [27]. Several other catalysts, namely iodine [28], hydrogen peroxide [29], zirconyl (IV) chloride [30], boron trifluoride diethyl etherate [31], ytterbium perfluorooctane sulfonates [32,33], zeolite [34], and Lproline [35] have been effectively used for the synthesis of benzimidazole derivatives.…”

Benzoimidazole Derivatives Containing Indole Unit: Activated Carbon/Air Promoted Synthesis and Spectral Properties

“…鉴于此, 本文选用 3-吲哚甲醛为原料, 合成了具有拓展 π 结构的含吲哚基苯 并咪唑衍生物, 并测试其紫外-可见吸收光谱和荧光发 射光谱, 期待筛选和进一步合成有更佳性能的光敏材 料. 苯并咪唑衍生物可经多种途径合成, 其中主要有两 种: 第一种是以邻苯二胺与羧酸或其衍生物为原料, 在 盐酸 [18] 、多聚磷酸 [19] , 或微波辐射 [20,21] 等作用下合成, MnO 2 [24] 等, 催化剂有 Co(OH) 2 [25] 、苯磺酸 [26] 、Cu(II)配 合物 [27] 等. 然而, 这种方法也有一些不足之处, 如后处 理复杂、需化学计量甚至过量的氧化剂, 有些氧化剂或 催化剂本身毒性较大, 许多反应还产生毒性大或污染环 境的副产物等.…”