Synthesis of Benzo[c]phenanthridine Alkaloids, Chelerythrine and Nitidine, Using a Novel Palladium-Phosphine Combination System - Pd(OAc)2, DPPP, and Bu3P -
Total synthesis of chelerythrine (1) and nitidine (4) was accomplished via the aryl-aryl cyclization reaction using a novel Pd reagent prepared from Pd(OAc)(2), DPPP, and Bu3P. The present method was very versatile for coupling reaction not only between aromatic triflate and arene but also between aromatic halide and arene.