Facile synthesis of acridines via Pd(0)-diphosphine complex-catalyzed tandem coupling/cyclization protocol.

A facile and efficient approach for the synthesis of a variety of acridines via the tandem coupling/cyclization of substituted 2-bromobenzaldehydes and anilines is described. The reaction can be accomplished with ease in the presence of a catalytic amount of Pd2(dba)3 and diphosphine ligand dppf, providing a broad range of substituted acridines in good to excellent yields (up to 99%). The Lewis acid, AlCl3, is required to promote the cyclization for less electron-rich anilines.