C(sp2)−H Functionalization of 2H−indazoles at C3-position via palladium(II)−catalyzed isocyanide insertion strategy leading to diverse heterocycles

Shinde, V and Murugan, A and D S, Sharada (2016) C(sp2)−H Functionalization of 2H−indazoles at C3-position via palladium(II)−catalyzed isocyanide insertion strategy leading to diverse heterocycles. Journal of Organic Chemistry, 81 (7). pp. 2837-2848. ISSN 0022-3263

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Abstract

Herein, we have reported an efficient Pd-catalyzed C-H functionalization of 2H-indazole at C3-position via an isocyanide insertion strategy for the synthesis of unprecedented benzoxazinoindazoles, indazoloquinaoxalines and benzoxazinoindazolones for the first time. Our new method provides an operationally simple and versatile route for a selective synthesis of 2-(2H-indazol-2-yl)phenols. Furthermore, we developed a sequential one-pot strategy for the synthesis of benzoxazinoindazolone under metal-oxidant-free conditions. We also achieved the isocyanide insertion between C(sp2)−H and oxygen heteroatom for the first time. The key features of the present protocol are construction of 4 bonds in one-pot, synthesis of new skeletally diverse scaffolds, broad substrate scope, high yields and environmentally benign conditions.

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