3-chloro-5,6,7,8-tetrahydropyrido[4,3-c]pyridazine synthesis

Yield:-

Reaction Conditions:

with trichlorophosphate in methanol;

Steps:

8.f EXAMPLE 8:

f. 3-Chloro-5,6,7,8-tetrahydropyrido[4,3-c]pyridazine Produced in a manner analogous to that described in Example 4 (e), from 30.3 g of 5,6,7,8-tetrahydro-3(2H)pyrido[4,3-c]pyridazinone and 250 cc of phosphorus oxychloride. The crude unstable base is converted into the maleate for working up. This is effected by boiling 24.8 g of the base in 150 cc of methanol with 17.5 g of maleic acid. Upon cooling the solution, the crude maleate is obtained, which is recrystallized from methanol with the addition of a small amount of coal. 3-Chloro-5,6,7,8-tetrahydropyrido [4,3-c]pyridazine maleate has a M.P. of 162°-164° (decomp.).

References:

US3954754,1976,A