title: Synthesis of new unsymmetrical 4,5-dihydroxy-2-imidazolidinones. Dynamic NMR spectroscopic study of the prototropic tautomerism in 1-(2-benzimidazolyl)-3-phenyl-4,5-dihydroxy-2-imidazolidinone.
abstract: The acid-catalyzed cyclocondensation in refluxing acetonitrile of aqueous glyoxal with N-heteroaryl-N'-phenylureas 4a-f (heteroaryl = 2-thiazolyl, 2-pyrimidinyl,2-pyrazinyl, 2-pyridinyl, 3-pyridinyl and 2-benzimidazolyl) led to the formation of the corresponding 1-heteroaryl-3-phenyl-4,5-dihydroxy-2-imidazolidinones 5a-f. All the products were characterized by elemental and spectroscopic analyses. The free-energy barrier (Delta G not equal) for prototropic tautomerism in 1-(2-benzimidazolyl)-3-phenyl-4,5-dihydroxy-2-imidazolidinone (5f) was determined by dynamic NMR studies to be 81 +/- 2 KJ mol(-1).
authors.affiliation: School of Chemistry, University College of Science, University of Tehran, Tehran, Iran. ghandi@khayam.ut.ac.ir
authors.forename: Mehdi
authors.initials: M
authors.lastname: Ghandi
authors.forename: Abolfazl
authors.initials: A
authors.lastname: Olyaei
authors.forename: Farshid
authors.initials: F
authors.lastname: Salimi
mesh_terms: D006037:Glyoxal / Q000737:chemistry; D048289:Imidazolidines / Q000138:chemical synthesis* / Q000737:chemistry*; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D010671:Phenylurea Compounds / Q000737:chemistry
chemical_list: D048289:Imidazolidines; D010671:Phenylurea Compounds; C004916:ethylene urea; D006037:Glyoxal