Highly ortho‐Selective Chlorination of Anilines Using a Secondary Ammonium Salt Organocatalyst

An organocatalytic, highly facile, efficient, and regioselective ortho‐chlorination of anilines is described. A secondary ammonium chloride salt has been employed as the catalyst and the reaction can be conducted at room temperature without protection from air and moisture. In addition, the reaction is readily scalable and the catalyst can be recycled and reused. This catalytic protocol has been applied to the efficient synthesis of a highly potent c‐Met kinase inhibitor. Mechanistic studies revealed that unique structural features of the secondary ammonium chloride salt are important for both the catalysis and regioselectivity of the electrophilic ortho‐chlorination.