The first synthesis of arylquinazolinones has been disclosed via the consecutive oxidative cyclization/ring-opening of anilines and methyl ketones. This transformation is characterized by the splitting of the methyl ketone as acyl and C1 sources through C(CO)-C(sp3) bond cleavage, using DMSO as a C1 source via C-S bond cleavage, which expands the use of methyl ketones as valuable building blocks and enriches the library of preparation quinazolinones. Moreover, preliminary mechanistic studies indicate that this multicomponent reaction underwent a consecutive cyclization/ring-opening sequence.