Water → 5,6-Difluoro-2-methyl-1,2,3,4-tetrahydro-quinoline-8-carboxylic acid methyl ester

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Reaction Steps

A solution of 8.0 g (33.7 mmol) of 5,6-difluoro-2-methylquinoline-8-carboxylic acid methyl ester (Example 33) in 100 mL of glacial acetic acid is treated with 2.15 g of platinum on carbon (0.8 g of active catalyst+62.8% water) and then shaken in a hydrogen atmosphere at temperatures of 24° C. to 29° C. and pressures of 23.9 to 46.6 psi for 3 hours. The catalyst is removed by filtration and the solvent is removed in vacuo at 50° C. The residue is triturated with water (50 mL) and extracted with dichloromethane (2×200 mL). The combined organic layers are stirred with 5% sodium bicarbonate solution, washed with water, dried (MgSO4), filtered and evaporated in vacuo. The residue is chromatographed over flash grade silica gel (230–400 mesh) eluting with dichloromethane to give 5.6 g of the title compound as a light yellow oil. 1H NMR (400 MHz, CDCl3): 7.66 (bs, 1H), 7.49 (m, 1H), 3.82 (s, 3H), 3.46 (m, 1H), 2.88 (m, 1H), 2.67 (m, 1H), 1.97 (m, 1H), 1.27 (d, 3H).

Provenance & Evidence