Benzofuro[2,3-d]pyridazines IV. Etude de la chloro-4 benzofuropyridazine

1] Benzofuro2,3-d] pyridazone was synthesized by three methods namely8: catalytic dehalogenation of the 4-chlorobenzofuro 2,3-d] pyridazone; removal of the hydrazono group of 4-hydrazinobenzofuro 2,3-d] pyridazine and desulphurization of benzofuro 2,3-d] pyridazine and desulphurization of benzofuro 2,3-d] pyridazine-4(3H) thione. The 4-substituted derivatives were obtained by nucleophilic attack of the 4-chlorobenzofuro2,3-d] pyridazine. Tetrazolo1,5-b]- and s-triazolo-1,2-b] benzofuro 2,3-d] pyridazones. The structural assignment of the benzofuro2,3-d]pyridazones was made by the Noe effect.