A Palladium(0)‐Catalyzed C4 Site‐Selective C−H Difluoroalkylation of Isoquinolin‐1(2H)‐Ones

Herein, we report a Palladium(0)‐catalyzed C4 site‐selective C−H difluoroalkylation of isoquinolin‐1(2H)‐ones through a radical pathway. The present reaction enables the preparation of 2,2‐difluoro‐2‐(1‐oxo‐1,2‐dihydroisoquinolin‐4‐yl)acetates/acetamides through the direct cross‐coupling reaction of readily available isoquinolin‐1(2H)‐ones with 2‐bromo‐2,2‐difluoroacetates or 2‐bromo‐2,2‐difluoroacetamides. Therefore, this method provides an efficient and convenient approach to install a difluoroacetate or a difluoroacetamide moiety into bioactive molecules. Bioassay results showed that introduction of these difluorinated groups at C4 position was beneficial to improve their antiviral activity and compound 5 ab was found to exhibit similar antiviral activity with commercial Ningnanmycin.