2-Benzimidazolthiones and their congeners are significant motifs among heterocyclic compounds, and they have been broadly used as key building blocks in organic synthesis and in the pharmaceutical chemistry. In the rubber industry, these compounds are promising ligands for metallic complexes used as important accelerators in rubber vulcanization. In medicinal chemistry, these heterocyclic compounds have versatile bioactivities against tumors, ulcers, inflammatory conditions and infectious microbes. Consequently, developing novel and efficient methods of preparing these heterocyclic derivatives are of increasing interest. Common methods of synthesizing these materials have centered on the reactions of carbon disulfide with o-phenylenediamines, o-aminothiophenols and o-aminophenols. 2-Benzoxazolthione derivatives also can be prepared from the reaction of o-haloanilines or o-aminothiophenols with disulfides. These approaches often suffer from high temperatures, long reaction times, toxic solvents and metal catalysts. As part of own ongoing interest in heterocyclic synthesis, we now report a simple method for synthesizing 2-benzimidazolthiones, 2-benzothiazolthiones and 2-benzoxazolthiones via the reactions of CS2 with appropriate precursors with a recyclable ionic liquid [DBUH][OAc] as catalyst and solvent, as shown in Scheme 1. The IL exhibited high catalytic ability under mild conditions with high yields, and it could be recycled at least six times and still keep good catalytic ability. Initially, a number of bases (DBU, Et3N, NaOH, KOH, K2CO3, K3PO4 and Cs2CO3) were investigated for the synthesis of 2-benzimidazolthione at room temperature for 30minutes, and the results are summarized in Table 1. Some bases (NaOH, KOH, Cs2CO3, K3PO4, K2CO3, and Et3N, Table 1, entries 3-8) had no catalytic ability in this reaction. It was found that DBU can catalyze the reaction with only 20% yield of the product 2-benzimidazolthione (Table 1, entry 2). Fortunately, the reaction went

中文翻译：

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在温和条件下高效合成 2-苯并咪唑硫酮及其同系物

2-苯并咪唑硫酮及其同系物是杂环化合物中的重要基序，它们已被广泛用作有机合成和药物化学中的关键构建单元。在橡胶工业中，这些化合物是金属配合物的有前途的配体，用作橡胶硫化中的重要促进剂。在药物化学中，这些杂环化合物对肿瘤、溃疡、炎症和感染性微生物具有多种生物活性。因此，开发制备这些杂环衍生物的新颖且有效的方法越来越受到关注。合成这些材料的常用方法集中在二硫化碳与邻苯二胺、邻氨基苯硫酚和邻氨基苯酚的反应上。2-苯并恶唑硫酮衍生物也可通过邻卤苯胺或邻氨基苯硫酚与二硫化物的反应制备。这些方法通常受到高温、长反应时间、有毒溶剂和金属催化剂的影响。作为自己对杂环合成持续兴趣的一部分，我们现在报告了一种通过 CS2 与适当前体和可回收离子液体 [DBUH] [OAc] 作为催化剂的反应来合成 2-苯并咪唑硫酮、2-苯并噻唑硫酮和 2-苯并恶唑硫酮的简单方法和溶剂，如Scheme 1所示。IL在温和条件下表现出高催化能力，产率高，并且至少可以循环使用6次，仍然保持良好的催化能力。最初，许多碱（DBU、Et3N、NaOH、KOH、K2CO3、K3PO4 和 Cs2CO3) 用于在室温下合成 2-苯并咪唑硫酮 30 分钟，结果总结在表 1 中。一些碱（NaOH、KOH、Cs2CO3、K3PO4、K2CO3 和 Et3N，表 1，条目 3- 8) 在该反应中没有催化能力。发现 DBU 可以催化反应，产物 2-苯并咪唑硫酮的产率仅为 20%（表 1，条目 2）。幸运的是，反应进行了