A mixture of 4-(5-chlorothiazolo[5,4-b]pyridine-2-yl)-3-fluorobenzaldehyde (2.08 g, 7.11 mmol), methyl azetidine-3-carboxylate hydrochloride (1.62 g, 10.7 mmol), N-ethyl-N-isopropylpropan-2-amine (1.86 mL, 10.7 mmol) in dichloromethane (40.00 mL) and methanol (30.00 mL) was stirred for 5 min. Then acetic acid (1.64 mL, 28.4 mmol) was added and the mixture was allowed to stir for 90 min at 50° C. Sodium cyanoborohydride (0.223 g, 3.55 mmol) was added. After 15 min, the solvent removed, and the mixture concentrated onto silica gel. Purification by silica gel chromatography, 120 g column, 30-40% EtOAc/hex followed by 50-60% (3% TEA in EtOAc/hex) gave methyl 1-((4-(5-chlorothiazolo[5,4-b]pyridine-2-yl)-3-fluorophenyl)methyl)azetidine-3-carboxylate. MS (ESI) m/z: calculated: 391.1; Observed: 392.0 (M++1).
