Hydrochloric Acid → Methyl 2-(5-bromopyridin-2-yl)acetate

Concentrated hydrochloric acid (10 mL) was added to a solution of 5-(5-bromo-1H-2-pyridinylidene)-2,2-dimethyl-[1,3]dioxane-4,6-dione (Example 44-(1); 4.53 g, 15.09 mmol) in dioxane (20 mL), and the mixture was stirred at 100° C. for one hour. After cooling, the reaction mixture was concentrated. The residue was dissolved in methanol (20 mL) and toluene (20 mL). Trimethylsilyldiazomethane (2 M solution in diethyl ether, 25 mL) was added, and the mixture was stirred at room temperature for 30 minutes. Acetic acid was added to the reaction mixture to terminate the reaction. Then, the mixture was concentrated under reduced pressure. The resulting residue was purified by silica gel chromatography (hexane:ethyl acetate=100:0 to 30:70, 40 minutes) to give the target compound as a colorless oil (2.50 g, 72%).