We have prepared the pyrrolopyridazines 7a-f starting from the diazo compounds 4. The synthesis involves a tandem condensation-aza-Wittig reaction or a combination of Wittig and aza-Wittig reactions as key steps. Reaction of pyridazine 7d with diazomethane results in C-methylation to yield 7g. Sodium borohydride reduces 7d to either the dihydropyridazine 12 or the hydroxylactam 13b depending of the