I2-Mediated 2H-indazole synthesis via halogen-bond-assisted benzyl C-H functionalization

Xiangli Yi; Lei Jiao; Chanjuan Xi

doi:10.1039/c6ob01827k

I₂-Mediated 2H-indazole synthesis via halogen-bond-assisted benzyl C-H functionalization

Org Biomol Chem. 2016 Oct 18;14(41):9912-9918. doi: 10.1039/c6ob01827k.

Authors

Xiangli Yi¹, Lei Jiao², Chanjuan Xi³

Affiliations

¹ Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China. cjxi@tsinghua.edu.cn.
² Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China.
³ Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China. cjxi@tsinghua.edu.cn and State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China.

PMID: 27714284
DOI: 10.1039/c6ob01827k

Abstract

I₂-Mediated benzyl C-H functionalization has been developed for the synthesis of 2H-indazoles, which features high efficiency, simple conditions and no need for metals. Mechanistic experiments and DFT calculations have revealed halogen bond assistance and a radical chain process for this reaction. The azo group and the bound iodine cooperate in the hydrogen abstraction step, which circumvents the thermodynamic disfavor of direct hydrogen abstraction by a simple iodine radical.