Efficient Synthesis of Diaryl Ketones by Nickel-Catalyzed Negishi Cross-Coupling of Amides by Carbon-Nitrogen Bond Cleavage at Room Temperature Accelerated by a Solvent Effect.

Abstract

The first Negishi cross-coupling of amides for the synthesis of versatile diaryl ketones by selective C-N bond activation under exceedingly mild conditions is reported. The cross-coupling was accomplished with bench-stable, inexpensive precatalyst [Ni(PPh3 )2 Cl2 ] that shows high functional-group tolerance and enables the synthesis of highly functionalized diaryl ketone motifs. The coupling occurred with excellent chemoselectivity favoring the ketone (cf. biaryl) products. Notably, this process represents the mildest conditions for amide N-C bond activation accomplished to date (room temperature, <10 min). Considering the versatile role of polyfunctional biaryl ketone linchpins in modern organic synthesis, availability, and excellent functional-group tolerance of organozinc reagents, this strategy provides a new platform for amide N-C bond/organozinc cross-coupling under mild conditions.