Ethyl orthoformate → 2-Cyanoethyl 4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,8-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carboxylate

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Reaction Conditions

Reaction Steps

2.22 g (5.44 mmol) of the compound from Example 28A are suspended in 100 ml of triethyl orthoformate and heated to 130° C. Then, over a total period of 8 hours, 10 drops of concentrated sulfuric acid are added each hour to the reaction mixture. It is then stirred at the same temperature overnight. After cooling, excess orthoester is removed in a rotary evaporator, and the crude product is purified by column chromatography (silica gel; mobile phase: initially dichloromethane then isohexane/ethyl acetate 1:1). The product fractions are combined, the solvent is removed, and the residue is crystallized from ethyl acetate/diethyl ether. The precipitate is filtered off and dried under high vacuum. 1.80 g (77% of theory) of the title compound are obtained.

Provenance & Evidence