Trifluoroacetic acid → 2-Amino-3-(7,7-dimethyl-1,4,6,7-tetrahydro-pyrazolo[4,3-c]pyridin-5-yl)-propionic acid methyl ester

関与物質

反応手順

To a solution of 2-(di-tert-butoxycarbonylamino)-3-(7,7-dimethyl-1,4,6,7-tetrahydro-pyrazolo[4,3-c]pyridin-5-yl)-propionic acid methyl ester (0.49 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 loaded onto a column of strong cation exchange resin. After flushing with methanol, the product was removed from the column by eluting with 2M ammonia in methanol to afford the product as its free base (250 mg, 94%). 1H-NMR (CDCl3, 500 MHz) δ 1.27 (s, 3H), 1.28 (s, 3H), 2.41 (d, J=11.3, 1H), 2.50 (d, J=11.3, 1H), 2.69 (dd, J=12.5, 7.9, 1H), 2.82 (dd, J=12.5, 5.2, 1H), 3.45 (d, J=12.8, 1H), 3.52 (d, J=12.8, 1H), 3.67 (m, 1H), 3.69 (s, 3H), 7.19 (s, 1H). Mass spec.: 253.16 (MH)+.

情報源と証拠