Synthesis of new 5-substituted hydantoins from 2-alkoxy-1-cyano-1-trimethylsiloxypropenes

Synthetic procedures for preparing previously unknown 5-(1′-alkoxyethylidene)hydantoins from 2-alkoxy-1-cyano-1-trimethylsiloxy-1-(or -2-)propenes by one-pot successive reactions with ethanol and (NH4)2CO3 are developed. Some intermediates, reaction mechanism, and parameters determining the optimal yields are considered. Acid hydrolysis of ethylidenehydantoins occurs at the vinyloxy group and gives 5-acetylhydantoin in 64% yield.