Nucleophilic [3+3] addition of dimedone N-alkylimines to pyrrolo[1,2-a]quinoxaline-1,2,4-triones

1-Alkylamino-5,5-dimethyl-1-cyclohexen-3-ones react with pyrrolo[1,2-a]quinoxaline-1,2,4-triones to form substituted 3,10,13-triazapentacyclo[10.7.1.0(1,10).0(4,9).0(14,19)]icosa-4,6,8,14(19)-tetraene-2,11,18-triones.