Substituted hydrazones 5 and 6 were synthesized by the reaction of the corresponding furo[3,2-b]pyrrole-5-carboxyhydrazides 1 with 6-substituted 4-oxochromene-3-carbaldehydes 2 and methyl 2-formylfuro[3,2-b]pyrrole-5-carboxylates 3 under microwave irradiation as well as by the classical method. The beneficial effect of the microwave irradiation on these reactions was a shortening of the reaction time and an increase in the yields. The reactions of 1 with 4-[(4-oxochromen-3-yl)methylidene]-2-phenyloxazol-5(4H)-one (4) were also studied. Compounds 7 or 8 were obtained, depending on the reaction temperature.
The title compounds were prepareed by reaction of 1,2-dihydrofuro[2',3':4,5]pyrolo[1,2-d][1,2,4]-1-hydrazones by cyclization with triethyl orthoformiate or triethyl orthoacetate. All compounds were characterized by elemental analyses, UV and 1H NMR spectra.