Efficient Cu-catalyzed intramolecular Heck-borylation of unactivated alkenes to boronated indolines

Abstract

Efficient Cu-catalyzed intramolecular Heck-borylation of alkenes was developed. Racemic and chiral boronated indolines were achieved by borarylation of alkenes with B2pin2 via simultaneous construction of C-C and C-B bonds by Cu/phosphine ligand system. With CuOAc and DPPE ligand, a series of 3-substituted borylated indoline derivatives were concisely synthesized in good to excellent yields in short time under mild conditions. Asymmetric synthesis was investigated by ligand screening, and the chiral 3-substituted borylated indoline was obtained in 80% yield and 80:20 er with (R,R)-MeDuphos. Application of 3-substituted borylated indolines has been demonstrated by a gram scale synthesis and further functionalization.