Ni-Catalyzed Reductive Cross-Coupling of Amides with Aryl Iodide Electrophiles via C–N Bond Activation

Abstract

A Ni-catalyzed reductive cross-coupling reaction between two electrophiles, amides and aryl iodides, has been developed. This work is the first example using amide as an electrophile to couple with another electrophile, instead of using highly basic and pyrophoric nucleophiles. Furthermore, the Ni catalyst chemoselectively inserting the C-N bond of amide triggered the reductive cross-coupling reaction, which solves the problem that the Ni catalyst preferentially inserts the more reactive C-I bond to form a self-coupling product.

Exploring Mechanisms in Ni Terpyridine Catalyzed C–C Cross-Coupling Reactions—A Review

“…At the same time, this species is supposed to react with alkyl halides through single electron transfer (SET) under the formation of an alkyl radical and a halide, thus recovering the Ni(I) species. Very similar to the report by Han [62], and our findings [44], the next step comprises a radical oxidative addition of an alkyl radical [49] stemming from the second substrate to the Ni(II) complex. The resulting Ni(III) species undergoes reductive elimination to yield the C-C coupling product and a Ni(I) species, which is then reduced by the photosystem to recover the active Ni(0) species [66].…”

“…Recently, Han et al reported on Ni-catalyzed reductive cross-coupling reactions between two electrophiles, amides and aryl iodides [62]. The nickel-tpy catalysts system turned out to be superior to catalysts containing the bidentate ligands 2,2′-bipyridine, 2,2′-biquinoline, 1,10-phenanthroline, and its 5,6-dione.…”

“…As a proof for the radical oxidative addition reaction, the addition of TEMPO (TEMPO = 2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) inhibited the reaction and yielded the acyl-TEMPO adduct. Furthermore, [Ni(COD) 2 ] was also successfully used as the catalyst precursor, underpinning the role of the metallic zinc [62].…”

“…Furthermore, [Ni(COD)2] was also successfully used as the catalyst precursor, underpinning the role of the metallic zinc [62].…”

“…The resulting Ni(III) species Scheme 11. Proposed reaction mechanisms for the reductive cross-coupling reaction of amides and aryl iodides, adapted with permission from [62]. Copyright (2017) American Chemical Society.…”