Ethyl orthoformate → 4-(4-Cyano-2-methoxyphenyl)-5-ethoxy-2,7-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carbonitrile

Participants

Reaction Conditions

Reaction Steps

1920 mg (5.77 mmol) of 4-(4-cyano-2-methoxyphenyl)-2,7-dimethyl-5-oxo-1,4,5,6-tetrahydro-1,6-naphthyridine-3-carbonitrile are suspended in 40 ml (240 mmol) of anhydrous triethyl orthoformate. The reaction mixture is heated to 130° C. Then 10 drops of concentrated sulfuric acid are added each hour. After complete reaction has been detected (analytical HPLC; reaction time about 36 h), the reaction mixture is cooled to room temperature, and the volatile components are removed in a rotary evaporator. The crude product is purified by column chromatography (silica gel; mobile phase: cyclohexane/ethyl acetate 1:1). The product obtained in this way is crystallized from ethyl acetate. 451 mg (22% of theory) of the title compound are obtained as a white solid.

Provenance & Evidence