Pyridazine → Ethyl 4-[6-chloro-2-phenylimidazo[1,2-b]pyridazin-3-yl]-4H-pyridazine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

26.2 ml (30.3 mmol) of ethyl chloroformate are added, dropwise in 30 minutes, to a solution of 25.2 g (109 mmol) of 6-chloro-2-phenylimidazo[1,2-b]pyridazine and 39.8 ml (548 mmol) of pyridazine in 550 ml of dichloromethane at 8° C. The medium is stirred at 10° C. for a further hour and then left to stir for an additional hour. The medium is cooled to 8° C. and 14.9 ml (273 mmol) of pyridazine and 13.1 ml (137 mmol) of ethyl chloroformate are then added in fifteen minutes. The reaction is allowed to return to ambient temperature with stirring for a further hour. The solvent is evaporated off under reduced pressure and the residue is taken up with 1 l of ethyl acetate. The organic phase is washed with a saturated solution of sodium hydrogen carbonate and then with water. The organic phase is dried over sodium sulfate and the solvent is evaporated off under reduced pressure. The product is chromatographed on a neutral alumina column, elution being carried out with a mixture of chloroform and cyclohexane (6/4), to give 35 g of an orangey solid, which is crystallized from 250 ml of diethyl ether, to give 30.1 g of a beige solid.

Provenance & Evidence