Potassium Phosphate, Tribasic → Tert-Butyl 4-{4-Chloro-2-[(1R)-1-Hydroxyethyl]Phenyl}-3,6-Dihydropyridine-1(2H)-Carboxylate

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A vigorously stirred mixture of tert-butyl 4-(4,4,5,5-tetramethyl-1,2,3-dioxaborolan-2-yl)-3,6-dihydropyridine-1(2H)-carboxylate (1-4) (34.0 g, 0.110 mol), (1R)-1-(2-bromo-5-chlorophenyl)ethanol (3-4) (25.8 g, 0.110 mmol), potassium phosphate tribasic (70.0 g, 0.330 mol) and tetrakis(triphenylphosphine)palladium(0) (2.54 g, 2.20 mmol) in N,N-dimethylformamide (440 mL) was degassed via three vacuum/nitrogen ingress cycles and then heated at 100° C. for approximately 18 h. After cooling to room temperature, the reaction mixture was poured into ice/water (˜1:1) and extracted three times with ethyl acetate. The combined organic extracts were washed with brine, dried (MgSO4) and concentrated in vacuo. Purification of the crude residue by flash chromatography on silica gel (25% ethyl acetate/hexanes as eluent) afforded 3-5 (27.7 g) as a pale yellow foam.

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