Pd(0) catalyzed three–five-component C-2-arylallylation of active methylene heterocycles: pyrazolones, oxazolones, isoxazolones and N,N′-dimethylbarbituric acid

A Pd(0) catalyzed three–five-component cascade involving an aryl iodide, allene and a heterocyclic pronucleophile is used to prepare 2-arylallyl derivatives (10–12 and 16–24) from 3-phenyl-5-isoxazolone (6) and 1-phenyl-3-methylpyrazolin-5-one (7) in moderate yield. Similar cascade allylation of masked amino acids 4-methyl-2-phenyl-4H-oxazol-5-one (8a), 4-benzyl-2-phenyl-4H-oxazol-5-one (8b) and 4-isopropyl-2-phenyl-4H-oxazol-5-one (8c) gave analogous products (25–37) in good yield. N,N-Dimethylbarbiturates (38–49) are similarly prepared from N,N-dimethylbarbituric acid (9) in excellent yield.