title: Computational and NMR Spectroscopic Evidence for Stereochemistry-Dependent Conformations of 2,2,6,6-Tetramethylpiperidinyl-Masked 1,2-Diols.
abstract: 2,2,6,6-Tetramethylpiperidinyl-masked 1,2-diols exhibited stereochemistry-dependent hydroxyl proton chemical shifts: ca. 7 ppm for the syn diastereomer and ca. 2 ppm for the anti diastereomer. A computational search for low energy geometries revealed that the syn isomer favors a six-membered ring hydrogen bond to nitrogen and the anti isomer favors a five-membered ring hydrogen bond to oxygen. The computed low energy conformations were found to have a large difference in hydroxyl proton shielding that was reflected in the experimental chemical shift difference. This chemical shift difference was observed in a broad range of solvents, and thus may be useful as a stereochemical probe. The stereochemistry-dependent conformation and chemical shift signature appeared to be due to a syn pentane interaction between the gem-dimethyl groups on the 2,2,6,6-tetramethylpiperidinyl moiety.
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Ellie L
authors.initials: EL
authors.lastname: Fought
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Shreyosree
authors.initials: S
authors.lastname: Chatterjee
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Theresa L
authors.initials: TL
authors.lastname: Windus
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Chen
mesh_terms: D003497:Cyclic N-Oxides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011789:Quantum Theory; D013237:Stereoisomerism
chemical_list: D003497:Cyclic N-Oxides; C003959:TEMPO