A mixture of 2-chlorophenylboronic acid (5.0 g), 3-bromopyridine (4.8 g) and tetrakis(triphenylphosphine)palladium(0) (1.0 g) in toluene (47 ml), aqueous 2 M sodium carbonate solution (35 ml) and ethanol (2.4 ml) was heated under reflux for 5.5 h. The reaction mixture was cooled, and the toluene layer was separated. The aqueous layer was extracted with ethyl acetate and the combined organic extracts were dried (MgSO4), filtered, and the filtrate evaporated under reduced pressure to give crude 3-(2-chlorophenyl)pyridine (7.9 g). To a solution of the 3-(2-chlorophenyl)pyridine (7.9 g) in dichloromethane (50 ml) was added iodomethane (3.8 ml) and the mixture was stirred for 15 h. The solvent was evaporated under reduced pressure and the obtained residue was crystallized from ethyl acetate to give a pale-yellow crystal. To a solution of the obtained crystals in methanol (60 ml) was added sodium borohydride (1.7 g) under ice-cooling, and the mixture was stirred at room temperature for 3 h. The mixture was quenched with a saturated aqueous sodium chloride solution. The mixture was extracted with ethyl acetate. The extract was washed with a saturated aqueous sodium chloride solution, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure to give a crude 5-(2-chlorophenyl)-1,2,3,6-tetrahydro-1-methylpyridine (5.9 g).
