NEW N-N BOND-CLEAVAGE OF FUSED CHLOROPYRIDAZINES WITH YNAMINES

1-Chlorophthalazine (1) reacts with a 2-fold molar excess of ynamines 2a, b to give penta-substituted pyridine derivatives 3a,b by nitrogen- nitrogen bond cleavage of the pyridazine ring with release of hydrogen chloride. Similarly, other fused pyridazines having a chloro substitu ent a to nitrogen in the pyridazine ring, i.e., pyrido[3,4-d]-(10a), p yrido[2,3-d]-(10b), thiazolo[4,5-d]-(10c,d), furo[2,3-d]-(10e) and pyr rolo[2,3-d]-(10f,g) pyridazine derivatives, gave the corresponding pen ta-substituted pyridines 11a-11k.