Synthesis and reactions of α‐ketoaldehyde adducts of some heterocyclic ureas

Abstract

Pyruvaldehyde reacts with heterocyclic ureas 4a‐d giving dihydroxyimidazolidin‐2‐ones 5a‐d. Phenyl glyoxal reacts with 4a giving an analogous adduct 5e. These 1,2‐diols are smoothly dehydrated to hydantoins 9a‐e which on mild reduction provide monohydroxyimidazolidin‐2‐ones 10a‐e. Cis and trans isomers of 10d have been isolated and observed to epimerise under suitable conditions. An unusual halogenation converts 5a to the bromomethyl derivative 14b which is a convenient starting material for the synthesis of 4‐substituted imidazolin‐2‐ones such as 15, 16, 17, 18 and 19. Copyright © 1986 Journal of Heterocyclic Chemistry