An Unequivocal Synthesis of Mono-N-Substituted Barbiturate Derivatives

Abstract

It is known that those reactions of barbiturates which depend on the accessability of hydrogen produce mono-N-substituted barbiturate derivatives. This is the case in the Mannich reaction, where lactim formation of the mono-aminomethyl derivative renders the other hydrogen inaccessible to a second condensation reaction^1,2. On the other hand those reactions of barbiturates which depend on enol (lactim) or enolate ion formation usually produce a mixture of unsubstituted, monosubstituted and disubstituted derivatives of barbiturates^3,4. The ratio of products largely depends on the degree of enolization of the appropriate barbiturate.