[Synthesis of potential metabolites of a barbiturate containing two branched side chains]

The two branched side chains of 5-(3-methylbutyl)-5-(2-methylpropyl)-barbituric acid present a tertiary carbon atom, which can be oxidized in vivo by hepatic enzymes. Potential metabolites of this compound are synthesised: the gamma-hydroxy metabolite can be oxidized directly by CrO3 while the beta-hydroxy metabolite can only be prepared by hydration of a double bond. This beta-hydroxybarbiturate then undergoes an alcoholysis leading to an allophanyl-gamma-lactone, which is hydrolysed into a carboxylic lactone, which can give a lactone by decarboxylation. On the other hand, a beta-gamma-dihydroxymetabolite is synthesised by double hydration of two double bonds using two different methods. A spirobilactone can also be synthesised from this dihydroxy compound.