H2O2/DMSO-Promoted Regioselective Synthesis of 3,3′-Bisimidazopyridinylmethanes via Intermolecular Oxidative C(sp2)–H Bond Activation of Imidazoheterocycles

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• 作者：Om P. S. Patel ; Devireddy Anand ; Rahul K. Maurya ; Prem P. Yadav
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：September 2, 2016
• 年：2016
• 卷：81
• 期：17
• 页码：7626-7634
• 全文大小：661K
• 年卷期：0
• ISSN：1520-6904

文摘

In the past decade, metal-free approaches for C–C bond formation have attracted a great deal of attention due to their ease of use and low cost. This report represents a novel and metal-free synthesis of 3,3′-bisimidazopyridinylmethanes via intermolecular oxidative C(sp<sup>2sup>)–H bond functionalization of imidazo[1,2-a]pyridines with dimethyl sulfoxide as the carbon synthon (CH<sub>2sub>) using H<sub>2sub>O<sub>2sub> as a mild oxidant under air. A library of 3,3′-bis(2-arylimidazo[1,2-a]pyridin-3-yl)methanes has been achieved in good to excellent yields. The present methodology has been successfully applied to imidazo[2,1-b]thiazoles and imidazo[2,1-b]benzothiazoles. Furthermore, the current approach was also extended for the synthesis of unsymmetrical 3,3′-bisimidazopyridinylmethanes under optimized reaction conditions. A mechanistic pathway is proposed on the basis of experiments with radical scavengers and DMSO-d<sub>6sub> and ESI-MS observations.