Visible light-mediated metal-free alkyl Suzuki-Miyaura coupling of alkyl halides and alkenylboronic acids/esters: a green method for the synthesis of allyl difluoride derivatives

The Suzuki-Miyaura reaction has greatly facilitated the construction of C-C bonds and is well appreciated in medicinal chemistry, yet transition metal residues in this process are an unavoidable challenge. Herein, we report the first visible-light-driven photocatalyst-free coupling reaction of alkenylboronic acids/esters with α-bromodifluoroacylarenes, providing streamlining access to a series of Suzuki coupling products. The reactions proceed under metal-free conditions with a wide substrate scope. Mechanistic experiments and DFT calculation studies revealed that halogen bonding interactions, mainly generated in situ between α-bromodifluoroacylarenes and tertiary amines, could promote the C_sp³-Br bond homolytic cleavage from difluorobromoaryl ketones.