Convenient synthesis of N-alkoxymethylbarbituric acids and N-alkoxymethylhydantoins

A simple one-step method for the N-alkoxymethylation of barbituric acids and hydantoins is presented. The compounds are N-methoxymethylated or N-ethoxymethylated using phosphorus pentoxide and dimethoxymethane or diethoxymethane, respectively, in a chlorinated solvent. 1-Methoxymethyl-3-ethyl-5-phenylhydantoin showed significant anticonvulsant activity in the subcutaneous pentylenetetrazol test, while 1,3-bis(methoxymethyl)-5-ethyl-5-(p-tolyl) barbituric acid was inactive.