To a solution of 4-(3-undecyl-1,2,4-oxadiazol-5-yl)benzaldehyde (32.8 mg, 0.1 mmol) in anhydrous THF (0.6 mL) was added the 2-(2-fluorophenyl)ethylamine (11.8 mg, 0.1 mmol) and Ti(iPrO)4 (0.035 mL, 0.12 mmol). The mixture was stirred for 3 h at 60° C. then sodium triacetoxyborohydride (53 mg, 0.25 mmol) was added and the reaction mixture was stirred overnight at rt. THF (0.75 mL) was added followed by the PS-DEAM resin (Argonaut, 148 mg, 1.68 mmol/g), and the reaction mixture was stirred at rt overnight. The reaction mixture was filtered and the filtrates were eluted through a SCX column (Isolute, 1 g) with DCM (6 mL), then NH3 (2M in MeOH, 4 mL). The desired fractions (TLC monitoring) were concentrated under vacuum to give the title product.
