Substituent-controlled domino-Henry-hetero Diels–Alder reaction: synthesis of polycyclic nitronates

Syntheses of hitherto unreported 5-aryl-3,3-dimethylchromeno[2,3-b]furo[3,4-d]pyridine-1,11-diones and 6-aryl-4,4-dimethyl-12-oxochromeno[2,3:2′,3′]pyridino[4′,5′-d][1,2]oxazine-2-N-oxide have been accomplished by a metal-free domino-Henry-hetero Diels–Alder reaction.