Access to New 2-Oxofuro[2,3-<i>b</i>]pyrroles and 2-Methylenepyrroles through the Reaction of 1,2-Diaza-1,3-butadienes and γ-Ketoesters

New and interesting 2-oxofuro[2,3-<i>b</i>]pyrroles and 19-methyl-15-oxa-20-azatricyclo[12.3.3.0<sup>1,14</sup>]icos-18-en-18-carboxylates have been obtained in good yields by the one-pot reaction, in basic medium, of 1,2-diaza-1,3-butadienes with diethyl or dimethyl acetylsuccinate or methyl 2-(1,3-dioxo-2-cyclotetradecyl)acetate, respectively, under mild conditions. Treatment of the same starting materials with diethyl 2-acetylglutarate, in acidic medium, afforded unknown 2-methylenepyrrole derivatives in high yields. Novel 4-(3-oxopropyl)-2,5-dimethyl-1<i>H</i>-pyrrole-3-carboxylates also have been achieved by reacting 1,2-diaza-1,3-butadienes with ethyl or methyl 4-acetyl-5-oxo-hexanoate.