Facile One-Pot Synthesis of Substituted Hydantoins from Carbamates

A novel and simple approach for the preparation of 3-substituted, 5-substituted, or 3,5-disubstituted hydantoins is reported. It involves the reaction of -amino methyl ester hydrochlorides with carbamates to yield the corresponding ureido derivatives, which subsequently cyclize under basic conditions to produce substituted hydantoins in good yields. By applying this method, the bioactive anticonvulsant drug ethotoin was synthesized in good yield. The process avoids conventional multistep protocols and does not use the hazardous, irritant, toxic, or moisture-sensitive reagents, such as isocyanates or chloroformates, that are commonly used for the synthesis of these important compounds.