Efficient iron catalyzed ligand-free access to acridines and acridinium ions†
Acridines and acridinium ions are one of the important classes of compounds in terms of their usefulness in pharmaceuticals, materials, dyes and photo-catalysis. Here we present an unconventional FeCl3-alcohol catalysed one-pot method for their synthesis directly from aldehydes, 1,3-cyclohexanedione and amines. This method efficiently merged high atom-economy and diversity of multicomponent reaction with novel iron catalyzed dehydrogenation, using aerobic oxygen as the terminal oxidant, in alcoholic solvent to produce water as the only by-product. Easy scaling up of the method has been successfully demonstrated.