1,3,5-Triazine → (+/-)-1,2,5,10-Tetrahydro-9-isopropoxy-1-oxo-10-(2-trifluoromethylphenyl)-pyrido[4,3-b][1,6]naphthyridine

Participants

Reaction Steps

A solution of 11.3 g (27 mMole) ethyl (±)-1,4-dihydro-5-isopropoxy-2-methyl-4-(2-trifluoro methylphenyl)-1,6-naphthyridine-3-carboxylate in 200 ml dimethylformamide is added dropwise, under an atmosphere of nitrogen, to a suspension of 1.0 g (33 mMole) sodium hydride (80% in oil) in 20 ml dry dimethylformamide. After cessation of the gas evolution, the reaction mixture is stirred for 10 minutes at ambient temperature and subsequently 2.5 g (31 mMole) s-triazine in 20 ml dimethylformamide are added dropwise thereto. The reaction mixture is stirred for 16 hours at 105° C. and, after cooling, evaporated in a vacuum. The residue is chromatographed on silica gel with dichloromethane/methanol (95:5 v/v) and the fraction with an Rf of 0.6 is isolated and recrystallized from ethyl acetate/ethanol (9:1 v/v). There is obtained (±)-1,2,5,10-tetrahydro-9-isopropoxy-1-oxo-10-(2-trifluoromethylphenyl)-pyrido[4,3-b][1,6]naphthyridine in the form of colorless crystals; mp 315° C.

Provenance & Evidence