Under cooperative catalysis of iridium and a Brønsted acid, different C4-substituted azlactones react with vinyl benzoxazinones via a formal [4+2] cycloaddition or substitution reaction in a chemo- and stereoselective mode. Furthermore, the catalytic asymmetric version of the formal [4+2] cycloaddition established cooperative catalysis of iridium and a chiral thiourea-tertiary amine.