a) Synthesis of ethyl 5-bromonicotinate: Concentrated H2SO4 (9.0 mL) was slowly added dropwise to an ethanol (30.0 mL) suspension of 5-bromonicotinic acid (3.00 g, 14.9 mmol) under stirring, with the dropwise addition time controlled over 5 minutes until a clarified solution was formed. Subsequently, the reaction mixture was heated to reflux for 22 hours. Upon completion of the reaction, it was cooled to room temperature and the reaction was quenched with water (30 mL) and then extracted with dichloromethane (75 mL). The organic layer was washed sequentially with 10% Na2CO3 solution (20 mL) and water (20 mL), dried over anhydrous MgSO4, and concentrated by filtration through a sintered glass funnel to give 2.8 g of ethyl 5-bromonicotinate as a white solid in 82% yield. The structure of the product was confirmed by 1H NMR (CDCl3): δ 9.13 (d, J = 1.7 Hz, 1H), 8.84 (d, J = 2.2 Hz, 1H), 8.42 (m, J = 2.2, 1.7 Hz, 2H), 4.40 (q, J = 7.1 Hz, 2H), 1.43 (t, J = 7.1 Hz, 3H).
