To a mixture of 3-formylisoxazole (19.4 mg, 0.2 mmol) and Compound B of Example 25 (39.9 mg, 0.1 mmol) in DCM (0.5 mL) at rt was added TFA (45 mg, 0.4 mmol), followed by triethylsilane (35 mg, 0.3 mmol). The resulting mixture was stirred at rt for 1 hour, neutrallized with NaHCO3 solution and extracted with DCM (2×5 mL). The combined extract was dried over Na2SO4 and concentrated. The residue was purified by flash column chromatography (SiO2; ethyl acetate: methanol ammonia/100:10:0.1) to afford the title compound, 45 mg (87%). MS: m/e (M+H)+=480.
