反应详情

Three g (6.2 mMol) benzyl (±)-1,4-dihydro-5-isopropoxy-2-methyl-4-(2-trifluoromethylphenyl)-1,6-naphthyridine-3-carboxylate are hydrogenated at normal pressure and at ambient temperature with the use of 1.5 g 10% palladium on active charcoal in 100 ml ethanol. The take up of hydrogen is finished after 30 minutes. The catalyst is filtered off, the solvent is distilled off in a vacuum and the colorless, crystalline residue is recrystallized from diisopropyl ether/ethyl acetate. There is obtained (±)-1,4-dihydro-5-isopropoxy-2-methyl-4-(2-trifluoromethylphenyl)-1,6-naphthyridine-3-carboxylic acid in the form of colorless crystals with a melting point of 164°-166° C. (decomp.).

1. filtrationThe catalyst is filtered off
2. distillationthe solvent is distilled off in a vacuum
3. customthe colorless, crystalline residue is recrystallized from diisopropyl ether/ethyl acetate