Sequential construction of complex pyrrole-pyrrole or pyrrole-pyrazole systems from 1,2-diaza-1,3-butadienes

The treatment of cyanoacetic acid hydrazide or ethyl 3-hydrazino-3-oxopropi onate with methyl 2-chloroacetoacetate leads to the corresponding hydrazone derivatives. In the presence of sodium carbonate, these compounds react at room temperature with acetoacetanilide or 2,4-pentanedione to give the rel evant 1-aminopyrrole rings. In the presence of sodium methoxide, the activa ted methylene group present on the I-amino side chain of these heterocycles attacks at room temperature 1,2-diaza-1,3-butadienes affording the respect ive hydrazonic 1,4-adducts. Under basic conditions, these adducts surprisin gly cyclise at room temperature in different way providing pyrrole-pyrrole or pyrrole-pyrazole systems depending on the starting cyano or ethylcarboxy late group, respectively.