Friedel-Crafts hydroxymethylation of 3-methoxybenzoic acid (I) using aqueous formaldehyde and HCl gave rise to 6-methoxyisobenzofuran-1-one (II). After radical bromination of (II) with N-bromosuccinimide in the presence of benzoyl peroxide, the resulting 3-bromo derivative (III) was condensed with triphenyl phosphine to afford the phosphonium salt (IV). Wittig condensation of 3,5-dichloropyridine-4-carbaldehyde (V) with the phosphonium bromide (IV) provided the 3-(pyridylmethylene)isobenzofuranone (VI). Reaction of the enol lactone function of (VI) with hydrazine produced the phthalazinone derivative (VII), which was further converted to the 4-chlorophthalazine (VIII) upon treatment with POCl3. The 4-chloro group of (VIII) was finally displaced with the sodium salt of 1,2,4-triazole (IX) to give the title compound.

Friedel-Crafts hydroxymethylation of 3-methoxybenzoic acid (I) using aqueous formaldehyde and HCl gave rise to 6-methoxyisobenzofuran-1-one (II). After radical bromination of (II) with N-bromosuccinimide in the presence of benzoyl peroxide, the resulting 3-bromo derivative (III) was condensed with triphenyl phosphine to afford the phosphonium salt (IV). Wittig condensation of 3,5-dichloropyridine-4-carbaldehyde (V) with the phosphonium bromide (IV) provided the 3-(pyridylmethylene)isobenzofuranone (VI). Reaction of the enol lactone function of (VI) with hydrazine produced the phthalazinone derivative (VII), which was further converted to the 4-chlorophthalazine (VIII) upon treatment with POCl3. The 4-chloro group of (VIII) was finally displaced with the sodium salt of 1,2,4-triazole (IX) to give the title compound.