Lawesson's reagent → Ethyl 1-[(6-methyl-2,3'-bipyridin-5-yl)methyl]-4-thioxo-1,4-dihydropyrido[2,3-c]pyridazine-3-carboxylate

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Reaction Steps

Ethyl 1-[(6-methyl-2,3′-bipyridin-5-yl)methyl]-4-oxo-1,4-dihydropyrido[2,3-c]pyridazine-3-carboxylate (139 mg, 0.346 mmol) was suspended in dioxane (6 mL) and toluene (3 mL), placed into a preheated oil bath at 100° C. and treated with Lawesson's Reagent (84.0 mg, 0.208 mmol, 0.6 equiv) portionwise over 5 minutes. After stirring for 30 minutes, the mixture was cooled to ambient temperature and concentrated in vacuo. The residue was purified by silica gel gradient chromatography (100:0 to 0:100; hexanes:ethyl acetate containing 5% methanol), providing the titled compound as brownish-green foam.

Provenance & Evidence