Selective Reductions of 3-Substituted Hydantoins to 4-Hydroxy-2-imidazolidinones and Vicinal Diamines

Article abstract of DOI:10.1021/jo00161a021

N³-Substituted hydantoins (1) have been shown to undergo LiAlH4 reduction (THF, room temperature, 2 days) to give 4-hydroxy-2-imidazolidinones (3) in good yields.Reduction of 3,5-disubstituted hydantoins in which an aliphatic substituent was present at nitrogen 3 led to the preferential formation of the cis adduct 3.Conversely, disubstituted hydantoins possessing an aryl moiety at nitrogen 3 gave the trans derivative 3 as the major product.Treatment of the N³-substituted hydantoins (1) under more vigorous conditions (THF, reflux, 3 days) led to selective ring opening of 1 to yield N-methylethylenediamines (7).The scope of both of these reductive processes has been explored, and explanations are offered to account for the observed results.Full spectral (infrared, 1H and 13C NMR, and mass spectra) data on all three classes of compounds (1, 3, and 7) have been collected.Together this information provides a consistent data set which is useful in structure elucidation.Moreover, various NMR aids have been discerned for the isomeric cis- and trans-4-hydroxy-2-imidazolidinones (3) which permitted stereochemical assignments for these compounds.