1,4-DICHLOROPYRIDO[4,3-D]PYRIDAZINE

Pyrido[3, 4-d]pyridazine-1 , 4-diol (1 .83g, 1 1 .2mmol) and phosphorus oxychloride (8.4ml_, 89.7mmol) were added to a round bottomed flask. To this was added DIPEA (2.0ml_, 1 1 .2mmol) slowly. The suspension was then heated for 1 hour at 1 00°C. The reaction turned into a brown solution. The phosphorus oxychloride was then removed by rotary evaporator. The resulting brown residue was dissolved in DCM and added dropwise to a mixture of ice and saturated NaHCCb solution (aq). Saturated NaHCCb solution (aq) was added until the aqueous layer was neutral. The organic and aqueous layers were separated and the aqueous layer was further extracted with DCM (500ml_). The organic layers were combined and dried (MgSCH) and then concentrated in vacuo to afford 1 , 4- dichloropyrido[3, 4-d]pyridazine (1 .74g, 8.7mmol, 78percent). 1 H NMR (400MHz, CDC ) δ/ppm : 9.78 (d, J 0.9Hz, 1 H), 9.27 (d, J 5.7Hz, 1 H), 8.09 (dd, J 5.7Hz, 0.9Hz, 1 H). MS Method 2: RT: 1 .1 6min, ESPyrido[3, 4-d]pyridazine-1 , 4-diol (1 .83g, 11 .2mmol) and phosphorus oxychloride (8.4mL, 89.7mmol) were added to a round bottomed flask. To this was added DIPEA (2.OmL, 11 .2mmol) slowly. The suspension was then heated for 1 hour at 100°C. The reaction turned into a brown solution. Thephosphorus oxychloride was then removed by rotary evaporator. The resulting brown residue was dissolved in DCM and added dropwise to a mixture of ice and saturated NaHCO3 solution (aq). Saturated NaHCO3 solution (aq) was added until the aqueous layer was neutral. The organic and aqueous layers were separated and the aqueous layer was further extracted with DCM (500mL). The organic layers were combined and dried (Mg504) and then concentrated in vacuo to afford 1, 4- dichloropyrido[3, 4-d]pyridazine (1 .74g, 8.7mmol, 77.6percent).1H NMR (400MHz, ODd3) s/ppm: 9.78 (d, J0.9Hz, 1H), 9.27 (d, J5.7Hz, 1H), 8.09 (dd, J5.7Hz, 0.9Hz, 1H).MS Method 2: RT: 1 .1 6mm, ES÷ m/z 200.0/202.0 [M÷H].A mixture of pyrido[3, 4-d]pyridazine-l, 4-diol 2 (24.2 g, 148 mmol) and POCl

Molecular Weight:200.02
XLogP3:1.9
Hydrogen Bond Acceptor Count:3
Exact Mass:198.9704025
Monoisotopic Mass:198.9704025
Topological Polar Surface Area:38.7
Heavy Atom Count:12
Complexity:167
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes