Trifluoroacetic acid → 3-(4-Acetoxymethyl-7-chloro-1H-indazol-5-yl)-2-(R)-benzyloxycarbonylamino-propionic acid methyl ester

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Reaction Steps

Trifluoroacetic acid (70 μL, 0.91 mmol) was added to a solution of 3-(2-acetoxymethyl-4-amino-5-chloro-3-methyl-phenyl)-2-(R)-benzyloxycarbonylamino-propionic acid methyl ester (345 mg, 0.77 mmol) in 5% acetic acid in chloroform (5.2 mL). Isoamyl nitrite (120 μL, 0.89 mmol) was added to the mixture drop-wise. Reaction mixture was stirred at room temperature for 40 minutes. Potassium acetate (300 mg, 3.1 mmol) was added to the mixture. Reaction mixture was stirred at room temperature for 45 minutes. Mixture was diluted with dichloromethane (10 mL) then washed successively with water (2×10 mL), and saturated aqueous sodium bicarbonate (2×10 mL). Organic was dried (magnesium sulfate), filtered and concentrated in vacuo. Crude product was obtained as an orange solid in 83% yield. Material was carried forward without further purification. 1H NMR (300 MHz, CDCl3): δ=8.20 (s, 1H); 7.29 (m, 5H); 7.21 (s, 1H); 5.53 (d, J=7.7, 1H); 5.40 (s, 2H); 5.04 (s, 2H); 4.67 (m, 1H); 3.74 (s, 3H); 3.34 (m, 1H); 3.21 (m, 1H); 2.02 (s, 3H). MS m/e (M+H)+=460.1.

Provenance & Evidence