TEMPO-Mediated Direct C(sp)-H Alkoxylation/Aryloxylation of 1,4-Quinones.

A convenient and efficient transition-metal-free method has been developed for the C(sp)-H alkoxylation/aryloxylation of 1,4-quinones by direct cross-dehydrogenative coupling with readily available alcohols and phenols in the presence of TEMPO under simple and mild conditions. The method allowed the installation of a wide range of alkoxy/aryloxy groups, exhibited high functional group tolerance, showed a broad substrate scope, afforded good to excellent yields of products in a simple one-pot operation, and could be performed on a gram scale. Mechanistic investigation indicated the involvement of the radical pathway.

Ruthenium(II)-Catalyzed C-H/C-H (4+2) Annulation of 2-Aryl-N-heterocycles with Vinylene Carbonate.

A ruthenium(II)-catalyzed direct C-H/C-H (4+2) annulation of 2-aryl-N-heterocycles such as 2-aryl-4H-pyrido[1,2-a]pyrimidin-4-ones, 2-arylimidazo[1,2-a]pyridines, 2-aryl-2H-indazoles and 2-arylquinolin-4(1H)-ones with vinylene carbonate has been described. This one-pot cascade strategy provided the diversely substituted fused-polyheterocycles such as 7H-benzo[h]pyrido[2,1-b]quinazolin-7-ones, naphtho[1',2':4,5]imidazo[1,2-a]pyridines, indazolo[2,3-a]quinolines and benzo[c]acridin-7(12H)-ones in moderate to excellent yields. The developed protocol exhibited a broad substrate scope with good functional group tolerance and acid/base-free conditions.