title: Unambiguous structural characterization of hydantoin reaction products using 2D HMBC NMR spectroscopy.
abstract: Data from two-dimensional (2D) NMR experiments were used to identify the reaction products resulting from the opening of pyroglutamates with isocyanates or thioisocyanates. The reaction has the potential to produce compounds that would have very similar one-dimensional proton ((1)H) or carbon-13 ((13)C) NMR spectra. Careful analysis of (1)H--(1)H COSY, (1)H--(1)H NOESY, and HMBC data, including chemical shifts and coupling constants, were used to distinguish correctly between carbamoyl-2-pyrrolidinone, hydantoin, and perhydro-1,3-diazepine-2,4-dione type structures that could result from this reaction. This work describes their preparation and subsequent identification using 2D NMR spectroscopy, and includes complete (13)C assignments of the reaction products. The 2D NMR techniques and analysis described here can be applied successfully to other synthetic reactions with the potential to produce isomeric products.
authors.affiliation: Schering Plough Research Institute, Department of Analytical Spectroscopy, 2015 Galloping Hill Road, Bldg. K15 LL-0450, Kenilworth, NJ 07033, USA. mary.senior@spcorp.com
authors.forename: Mary M
authors.initials: MM
authors.lastname: Senior
authors.forename: Tze-Ming
authors.initials: TM
authors.lastname: Chan
authors.forename: Guoqing
authors.initials: G
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Andrew
authors.initials: A
authors.lastname: Stamford
mesh_terms: D002247:Carbon Isotopes; D006827:Hydantoins / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards; D015394:Molecular Structure; D011522:Protons; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013237:Stereoisomerism
chemical_list: D002247:Carbon Isotopes; D006827:Hydantoins; D011522:Protons