Isopropylamine → 2,6-Dihydro-2-methyl-6-(1-naphthalenylmethyl)-4-(2-propyl)amino-1H-pyrrolo[3,4-d]pyridazin-1-one

Isopropylamine (1 ml) was added to a solution of 4-chloro-2,6-dihydro-2-methyl-6-(1-naphthalenylmethyl)-1H-pyrrolo[3,4-d]pyridazine-1-one (0.095 g) in ethanol (4 ml) and the mixture was heated in a sealed tube at 200° C. for 3 days then at 250° C. for 24 hours. The mixture was evaporated and the residue was purified by column chromatography, eluting with ethyl acetate followed by recrystallisation from ethyl acetate/isohexane to give the title compound (0.013 g).