Synthesis of the First Benzoxazinobenzoxazine and its Tandem Retro-Diels-Alder - Diels-Alder Rearrangement to a Novel Benzoxazinobenzoxazine

Article abstract of DOI:10.1016/0040-4039(94)85380-0

Thermolysis of 3-methyl-4H-1,2-benzoxazine gave the tetracyclic 12a-methyl-7H,12aH,13H-<1,3>benzoxazino<3,2-b><1,2>benzoxazine, which further rearranged to the isomeric 5a-methyl-5aH,11H,13H-<1,3>benzoxazino<2,3-b><1,3>benzoxazine.Thermolysis of the benzoxazinobenzoxazines gave 2-methyl-4H-1,3-benzoxazine, and o-quinone methide which was trapped by ethyl vinyl ether to give 2-ethoxy-dihydrobenzopyran.