I 2 -DMSO-Mediated Transannulation of Benzo[ d ]isoxazol-3-amine: Direct Access to 2,4,5-Substituted Pyrimidine Derivatives.

An I 2 -DMSO-mediated multicomponent [3+1+2] cascade annulation reaction using aryl methyl ketones, enaminones, and benzo[ d ]isoxazol-3-amine as substrates has been developed. This metal-free reaction involved the transannulation of benzo[ d ]isoxazol-3-amines with the formation of two C-N bonds and a C-C bond in one pot. Notably, a pyrimidine ring with a 1,4-dicarbonyl scaffold could efficiently transform into a pyrimido[4,5- d ]pyridazine skeleton. The phenolic hydroxyl group of the target product could undergo further modification with pharmaceuticals, demonstrating the utility of this method.