Annulations of 2-aminonaphthoquinone with aldehydes and acetals

Article abstract of DOI:10.1016/0040-4020(95)00294-I

One-pot annulations between 2-amino-1,4-naphthoquinone (1) and aldehydes or acetals give either 6,13-dihydro-6-azapentacene-5,7,12,14-tetraones (4) or 1H-2,4-dihydronaphthol[2,3-d]1,3-oxazine-5,10-diones (5). These reactions constitute new examples of Hantzsch synthesis of 1,4-dihydropyridines and 6-endo-trig ring closures, respectively.