Heterocyclic studies. Part II. Ethyl pteridine-4-carboxylate and some methyl derivatives

Abstract

Ethyl pteridine-4-carboxylate is the first monosubstituted pteridine with a strongly electron-withdrawing group to be prepared. Two molecules of water or ethanol are readily added across the 5,6- and 7,8-bonds to yield a stable isolable dihydrate or diethanolate. Ethyl 6- and 7-methylpteridine-4-carboxylates react similarly with two molecules of water, but ethyl 6,7-dimethylpteridine-4-carboxylate is only slightly hydrated at equilibrium. Freshly prepared aqueous acidic solutions of all the compounds contain only 5,6,7,8-dihydrated cations. In the case of the 6,7-dimethyl derivative the solute gradually changes to a mixture of 3,4-hydrated and 5,6,7,8-dihydrated cations.