Hydrochloric Acid → (2E)-2-[(3-bromo-4-pyridyl)methylene]-6,7-dimethoxy-tetralin-1-one

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Reaction Steps

To a solution of (i-Pr)2NH (0.3 mL, 2.2 mmol) at 0° C. in dry THF (15 mL) was added n-BuLi (1.22 M solution in hexane, 2.7 mL, 2.2 mmol), the mixture was stirred for 15 min at this temperature, after which the 6,7-dimethoxy-1-tetralone (0.412 g, 2 mmol) in dry THF (7 mL) was slowly added at −78° C. After 30 min at this temperature, 3-bromo-4-pyridinecarboxaldehyde (0.446 g, 2.4 mmol) in dry THF (7 mL) was slowly added and the solution was stirred for 30 min at −78° C. before allowed to reach room temperature and being stirred for a night. Then, the mixture was hydrolyzed by HCl 1N and extracted by AcOEt to eliminate the possible excess of tetralone. The aqueous layer was neutralized by NaHCO3 and the compound was extracted by CH2Cl2 three times. The combined organic layers were dried over MgSO4 and concentrated to dryness. The residue was purified by column chromatography on SiO2 (gradient of EtOAc in petroleum ether) to afford the expected product 84 (Yield 598.7 mg, 80%).

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