反应详情

To a solution of 2-(di-tert-butoxycarbonylamino)-3-(1,4,6,7-tetrahydro-pyrazolo[4,3-c]pyridin-5-yl)-propionic acid methyl ester (0.55 g, 1 equiv.) in methylene chloride (5 mL, 0° C.) was added trifluoroacetic acid (1.5 mL). The ice bath was removed and stirring continued for 2 h. The solution was concentrated, redissolved in methanol, and passed onto a column of strong cation exchange resin. After flushing with methanol, the product was removed from the column by eluting with 2 M ammonia in methanol to afford the product as its free base (275 mg, 95%). 1H-NMR (CDCl3, 500 MHz) δ 2.71 (dd, J=12.8, 8.6, 1H), 2.74-2.91 (m, 6H), 3.48 (s, 2H), 3.54 (d, J=13.4, 1H), 3.62 (d, J=13.4, 1H), 3.69 (dd, J=8.2, 4.9, 1H), 3.73 (s, 3H), 7.27 (s, 1H). Mass spec.: 225.16 (MH)+.

1. customThe ice bath was removed
2. concentrationThe solution was concentrated
3. dissolutionredissolved in methanol
4. customAfter flushing with methanol
5. customthe product was removed from the column
6. washby eluting with 2 M ammonia in methanol