Hydrochloric Acid → 4-(4-amino-phenyl)-4',6'-dimethyl-3,4,5,6-tetrahydro-2H-[1,2']-bipyridinyl-4-ol

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Reaction Steps

n-Butyl lithium (1 mL, 1.6 M in hexane, 1.6 mmol) was added dropwise to a solution of 2-(4-bromo-phenyl)-1,1,1,3,3,3-hexamethyl-disilazane (0.7 g, 2.20 mmol) in dry diethyl ether (10 mL) and stirred at room temperature for 15 min then cooled in an ice bath. A solution of 4′,6′-dimethyl-2,3,5,6-tetrahydro-[1,2′]bipyridinyl-4-one (0.3 g, 1.47 mmol) in dry tetrahydrofuran (15 mL) was added and the resulting mixture heated at 50° C. for 2.5 h. The reaction mixture was brought to room temperature and stirred overnight, then cooled to 0° C. and quenched into ammonium chloride solution. The mixture was extracted with ethyl acetate and the organic phase was washed with water, brine, dried over anhydrous sodium sulfate, filtered and concentrated in vacuo to yield the crude compound, to which was added 2N HCl and the resulting mixture was stirred overnight at room temperature. The pH of the solution was adjusted to pH 10 with dilute sodium hydroxide then the mixture was extracted with chloroform. The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated to dryness to give a viscous red oil which was purified by washing with pentane (5×10 mL) to afford 4-(4-amino-phenyl)-4′,6′-dimethyl-3,4,5,6-tetrahydro-2H-[1,2′]-bipyridinyl-4-ol (0.25 g, 57%).

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