Copper-Catalyzed Domino [1,3]/[1,2] Rearrangement for the Efficient Synthesis of Multisubstituted ortho-Anisidines.

Multisubstituted ortho-anisidines were efficiently synthesized via cationic N-heterocyclic carbene-Cu-catalyzed domino rearrangement of N-methoxyanilines that possess an electron-donating functional group, such as an alkyl or an aryl group, at the ortho position. The reaction proceeded first through a [1,3]-rearrangement of the methoxy group to the ortho position bound to the electron-donating substituent, followed by a semipinacol type [1,2]-rearrangement of the electron-donating group from the ortho to the meta position. Mechanistic studies suggest that both rearrangement reactions are promoted by a cationic Cu catalyst.