Regioselective double dehydrative cyclization route to construct polyheterocyclic skeletons consisting of 2,3-dihydroquinazolin-4(1<i>H</i>)-ones and 1,2-dihydropyrrolo[1,2-<i>a</i>]pyrazines

The Sc(OTf)₃-catalyzed reaction of 2-aminobenzamide with <i>N</i>-substituted pyrrole-2-carboxaldehyde proceeded well to give a tetracyclic skeleton consisting of dihydroquinazolin-4-one and 1,2-dihydropyrrolo[1,2-<i>a</i>]pyrazine <i>via</i> regioselective double cyclodehydrations where two heterocyclic rings (quinazolinone and pyrazine) were sequentially constructed through the formation of three C-N bonds.