The synthesis and transformations of 2H-naphtho-[1,2-b]pyran-2-one derivatives. Naphtho[2′,1′:5,6]-pyrano[3,4-d][1,3]oxazines and naphtho[1′,2′:5,6]pyrano[3,4-d]-pyrimidines, derivatives of two new heterocyclic systems

1,4-Naphthoquinone (1) was transformed with alkyl 2-aminofumarates 2 into 2H-naphtho[1,2-b]pyran-2-ones 3 and 4, which served as intermediates in the synthesis of 7, 8 and 13, which are derivatives of two new heterocyclic systems: naphtho[2′,1′:5,6]pyrano[3,4-d][1,3]oxazine and naphtho[1′,2′:5,6]pyrano[3,4-d]pyrimidine.