Reductant-Free NiF2/Picolinic Acid-Catalyzed Coupling-Cyclization of 2-Iodobenzamides with Malonates
Gunniga Tanomsiri1, Jun Takaoka2, Jumreang Tummatorn1,3
1Program on Chemical Sciences Center of Excellence on Environmental Health and Toxicology (EHT), OPS, MHESI, Chulabhorn Graduate Institute, 54 Kamphaeng Phet 6, Laksi, Bangkok 10210, Thailand.
None:
A ligand-enabled NiF2/picolinic acid catalyst system enabled an efficient and chemoselective coupling-cyclization of ortho-halo benzamides, including ortho-iodo- and ortho-bromobenzamides, with malonates or 1,3-diketoesters to furnish homophthalimides under operationally simple conditions. The reaction proceeded with high selectivity for the activation of benzamide-proximal aryl halide (C-I or C-Br) while tolerating additional aryl C-Br functionality at other positions, which remained intact throughout the transformation. Broad functional-group tolerance was observed across both benzamide and nucleophile classes, delivering the desired products in consistently high yields. Control experiments were consistent with the involvement of a redox-assisted nickel catalytic cycle. This cost-effective strategy provided a general and practical approach for constructing homophthalimide frameworks from readily accessible substrates.
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