Hydrolysis of barbituric acid derivatives. Part 6. Hydrolysis of spirocyclopropane- and spiro-2′-methylcyclopropane-1′,5-barbituric acids

Abstract

The title barbiturates are hydrolysed by pyrimidine ring degradation or by cyclopropane ring opening. The cyclopropane ring decreases the hydrolytic reactivity of the pyrimidine moiety in relation to other spirobarbiturates, owing to conjugation between the cyclopropane ring and the C-4 or C-6 carbonyl group. The kinetics and the products of the alcoholysis of these barbiturates have been investigated. The influence of the cyclopropane moiety on the pK_a1 values and ¹³C n.m.r. spectra has also been discussed.