Ethyl orthoformate → 2-Cyanoethyl 4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,7-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

1.52 g (3.76 mmol) of the compound from Example 25A are suspended in 40 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: cyclohexane/ethyl acetate 1:1). The product fractions are combined, the solvent is removed, and the residue is taken up in a little methanol. The crystallizing product is filtered off. Drying under high vacuum results in 1.09 g (67% of theory) of the title compound.

Provenance & Evidence