通过哌啶催化的2-氨基苯并咪唑,芳香族醛和1,3-二酮在异丙醇水溶液中的三组分反应实现苯并咪唑并[2,1 - b ]喹唑啉-1(1 H)-的超声辅助合成。在我们确定了一锅反应中不寻常的反应中间体之后,首先怀疑了这种机制。前所未有的偶联反应,它涉及2-氨基苯并咪唑对原位生成的迈克尔加合物的亲核攻击,然后发生电环形成反应。与普遍接受的机理相反,2-氨基苯并咪唑与Knoevenagel加合物的直接反应不能释放目标化合物。
Rhodium-Catalyzed Regioselective Synthesis of Isocoumarins through Benzothiadiazine-Fused Frameworks
作者:Prashant B. Dalvi、Kuang-Ling Lin、Manohar V. Kulkarni、Chung-Ming Sun
DOI:10.1021/acs.orglett.6b01408
日期:2016.8.5
An unprecedented two-step, one-pot synthesis of benzimidazothiadiazine 5,5-dioxides is presented. Reaction condition based regioselectivity has been achieved where fused benzimidazo[1,2-b][1,2,4]thiadiazines are exclusively formed under thermal conditions, whereas benzimidazo[2,1-c][1,2,4]thiadiazines were created only under microwave irradiation. The salient features of this protocol include a regioselective
提出了前所未有的两步,一锅法合成苯并咪唑并二嗪5,5-二氧化物。当在热条件下仅形成稠合的苯并咪唑[1,2- b ] [1,2,4]噻二嗪时,已经达到了基于反应条件的区域选择性,而苯并咪唑[2,1- c ] [1,2,4]噻二嗪则在热条件下形成。仅在微波辐射下产生。该方案的显着特征包括2-氨基苯并咪唑与邻卤代磺酰氯的区域选择性磺酰化,随后形成NC键。这些稠合的区域异构体的酸形式已用于引入新型的含胍的异香豆素骨架。
One-Pot, Two-Step Synthesis of Imidazo[1,2-<i>a</i>]benzimidazoles via A Multicomponent [4 + 1] Cycloaddition Reaction
作者:Ya-Shan Hsiao、Bharat D. Narhe、Ying-Sheng Chang、Chung-Ming Sun
DOI:10.1021/co400075z
日期:2013.10.14
A one-pot, two-step synthesis of imidazo[1,2-a]benzimidazoles has been achieved by a three-component reaction of 2-aminobenzimidazoles with an aromatic aldehyde and an isocyanide. The reaction involving condensation of 2-aminobenzimidazole with an aldehyde is run under microwave activation to generate an imine intermediate under basic conditions which then undergoes [4 + 1] cycloaddition with an isocyanide.