Diversified Aminohydantoins from Ureas and Thioureas Tethered to Amides

Abstract

Abstract Intramolecular cyclization of thioureas or ureas tethered to amides afforded 2‐iminohydantoins and 2‐amino‐1 H ‐imidazol‐4(5 H )‐ones in very high yields (87–100 %) regardless of the substituent (alkyls or aryls). This reaction proceeds through carbodiimides and iminium ions as intermediates. Among the reagents used to generate the carbodiimides, CBr 4 /Ph 3 P, CCl 4 /Ph 3 P, O , O′ ‐bis(2′‐pyridyl)thiocarbonate, and HgO were investigated.