1,2,4-Triazolo[4,3-b]pyridazine-6-carboxylic acid, 2,3-dihydro-3-thioxo-, methyl ester synthesis

Yield:1393352-88-9 91%

Reaction Conditions:

in N,N-dimethyl-formamide at 70; for 7 h;

Steps:

To a solution of methyl 4-hydrazinylbenzoate (3 g, 17.84 mmol) in DMF (20 ml) was added 1 , T-Thiocarbonyldiimidazole (3.18 g, 17.84 mmol). The reaction mixture was stirred for 7 hr at 70 °C, concentrated under high pressure pump until half of the DMF solvent was evaporated, and then diluted with CH₂CI₂ (20 ml). The resulting mixture was purified via biotage on silica gel flash chromatography column gradient with 0-50% MeOH/CH₂CI₂ to give Methyl 3-mercapto-[1 ,2,4]triazolo[4,3-b]pyridazine-6-carboxylate (3.41 g, 16.24 mmol, 91 % yield) as a yellow powder. LCMS (method B): [MH]⁺ = 21 1 , t_R = 1.42 min.

References:

WO2012/107500,2012,A1 Location in patent:Page/Page column 62; 63