Rapid and efficient microwave-assisted copper(0)-catalyzed ullmann coupling reaction:: General access to anilinoanthraquinone derivatives

The synthesis of anilinoanthraquinones 3a-z was achieved by a new, Cu(0)-catalyzed, microwave-assisted Ullmann coupling reaction of bromaminic acid (1) with aniline derivatives 2a-z in phosphate buffer. Good to excellent isolated yields were obtained within only 2-20 min at 80-120 degrees C and 40-100 W. The new procedure provides the first general access to anilinoanthraquinones, furnishing a number of previously inaccessible compounds. It is superior to classical methods in all aspects, including yields, reaction time, and versatility.