[Br:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][N:3]=1.[Li+].CC([N-]C(C)C)C.[O:17]1[CH2:20][C:19](=[O:21])[CH2:18]1.CC(=O)OCC>C1COCC1>[Br:1][C:2]1[C:7]([C:19]2([OH:21])[CH2:20][O:17][CH2:18]2)=[C:6]([Cl:8])[CH:5]=[CH:4][N:3]=1
To a solution of 2-bromo-4-chloropyridine (14 g, 70 mmol) in dry THF (200 mL) was added LDA (42.0 mL, 84.0 mmol, 2.0 M) dropwise at −70° C. After stirring for 0.5 h at this temperature, a solution of oxetan-3-one (6.6 g, 90 mmol) in dry THF (40 mL) was added slowly and the reaction mixture was stirred at 0° C. for an additional 1 h. Saturated aqueous NH4CI (50 mL) and EA (200 mL) were added. The mixture was partitioned between water and ethyl acetate. The aqueous layer was extracted with ethyl acetate. The combined organic layer was washed with water and brine. After drying over anhydrous magnesium sulfate, the solvent was evaporated and the crude material was purified by SGC eluting with DCM) to afford 148a as a yellow solid (8.8 g, 45%). MS: [M+H]+ 266.0.
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