Synthesis and NMR study of 5-furylmethylenehydantoins and 5-thienylmethylenehydantoins

Two series of 5‐furylmethylenehydantoins and 5‐thienylmethylenehydantoins were prepared and their 1H and 13C NMR spectra studied in comparison with those of compounds in the analogous 5‐aryl‐ and 5‐pyridyl‐ series. Differences in the effects of the aromatic, six‐ or five‐membered heteroaromatic rings are discussed. Spectral analysis enables Z/E configurations to be assigned with confidence and conformational preferences to be qualitatively deduced. Some interesting solvent effects were also observed.