A concise synthesis of benzimidazoles via the microwave-assisted one-pot batch reaction of amino acids up to a 10-g scale

Abstract

An efficient method for the synthesis of aminomethyl benzimidazoles is developed by using a one-pot batch reaction between amino acids and o-phenylenediamines. This reaction proceeds smoothly in an unmodified household microwave oven, even though scale-up is to 10 g. A desirable method for the quick synthesis of benzimidazoles, which are used as a kind of important intermediates in drug synthesis, is provided by the scale-up utilization of amino acid resource.

Characterization of some amino acid derivatives of benzoyl isothiocyanate: Crystal structures and theoretical prediction of their reactivity

“…The cyclization to form a benzimidazole using the alanine has been reported to be accessed by solvent free melting [30] and also in the presence of a mixture of orthophosphic acid and polyphosporic acid via microwave irradiation [31]. Hence, the compounds were not reproduced here.…”

Synthesis and characterization of a novel drug-loaded polymer, poly(lactic acid-co-aminomethyl benzimidazole)

“…anticancer, antifungal, antiviral, anti-inflammatory, etc. [5][6][7][8][9][10][11][12][13]. Among them, many drug molecules have a basic skeleton of aminomethyl benzimidazole (AMB) (Figure 1).…”

“…[28][29][30][31][32][33][34][35][36][37] However, there is no report about the drug delivery of benzimidazole drugs loaded by PLA materials. Herein, on the basis of our previous studies on lactic acid (LA) direct melt polymerization [35,38,39] and benzimidazole compounds, [3][4][5][6] using AMB [10] as a model of benzimidazole-type drugs, poly(lactic acid-coaminomethyl benzimidazole) (PLAAMB) as a potential biodegradable drug-loaded polymer is designed, and synthesized (Scheme 1). After the discussions on the optimal synthetic conditions, the structures and basic properties of PLAAMBs with different molar feed ratios are systematically investigated by Fourier transform infrared (FT-IR), 1 H NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and X-ray diffraction (XRD).…”

“…AMB was self-made from o-phenylenediamine and glycine according to the literature. [5] All other chemicals, including p-toluenesulfonic acid (TSA), stannous chloride (SnCl 2 ), stannous oxide (SnO), zinc chloride (ZnCl 2 ), and zinc oxide (ZnO) were commercially available as analytical grades from Guangzhou Chemical Reagent Factory (Guangzhou, China). All these materials were used without further purification.…”

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.…”