Alkyl 3-bromo-3-nitroacrylates – convenient building blocks for the construction of benzo-fused six-membered N,N-, N,O- and five-membered O,O-heterocycles

The reactions of alkyl 3-bromo-3-nitroacrylates with N,N-, N,O-, and О,О-o-phenylene bisnucleophiles resulted in the formation of benzo-fused heterocycles: reactions with о-phenylenediamines and о-aminophenols gave six-membered N,N- and N,O-heterocycles – (Z)-3-nitromethylidene-3,4-dihydroquinoxalin-2(1Н)-ones and (Z)-3-nitromethylidene-3,4-dihydro-2Н-1,4-benzoxazin-2-ones, while the use of pyrocatechols led to the formation of a five-membered O,O-heterocyclic system, providing alkyl 2-(nitromethyl)-1,3-benzodioxole-2-carboxylates. The nitroenamine moiety of the obtained six-membered heterocycles was shown to undergo tautomeric transformations.