p-Toluenesulfonic acid → 1-(6-Methyl-pyrid-3-yl)-3,4-dihydro-4,4-dimethyl-7-bromo-naphthalene

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Reaction Steps

To a cold (-78° C.) solution of 6-methyl-3-bromopyridine (890 mg, 5.2 mmol) in THF (15 mL) was added n-BuLi in hexane (1.6M solution, 3.5 mL, 5.6 mmol) and stirred for 1 hour. This mixture was added to a flask containing 3,4-dihydro-4,4-dimethyl-7-bromo-1(2H)-naphthalenone (Compound A, 1.35 g, 5.4 mmol), in THF (5 mL) at -78° C. The reaction mixture was gradually warmed to ambient temperature and stirred for 16 hours. Thereafter it was diluted with ethyl acetate (100 mL), washed with water (10 mL), brine (10 mL) and dried with MgSO4. Solvent was removed by distillation, the crude material was dissolved in toluene (25 mL) and pTSA (530 mg, 2.8 mmol) was added. The mixture was heated at 90° C. for 36 hours. Thereafter it was diluted with ethyl acetate (100 mL), washed with 10% NaHCO3 (2×10 mL), brine (10 mL), dried with MgSO4 and the solvent was removed by evaporation. The title compound was obtained by recrystallization from ethyl acetate and hexane mixture (1:9).

Provenance & Evidence