title: NMR-based conformational analysis of perezone and analogues.
abstract: Complete assignment of the (1)H NMR chemical shift and coupling constant values of perezone (1), O-methylperezone (2) and 6-hydroxyperezone (3) was carried out by total-line-shape-fitting calculations using the PERCH iterative spectra analysis software (PERCH Solutions Ltd., Kuopio, Finland). The resulting simulated spectra for the three compounds showed strong similarity to their corresponding experimental spectra. Particularly, all vicinal, allylic and homoallylic coupling constant values for the side chain of the three compounds were very similar, thus revealing that the conformation of these three molecules in solution is indeed almost identical. This fact is in agreement with extended side chain conformations over folded chain conformations because 1, 2 and 3 undergo completely different intramolecular cycloaddition reactions. In addition, results of double pulsed field gradient spin echo NOESY 1D experiments performed on perezone (1) were unable to provide evidence for folded conformers.
authors: Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala, Col. Santo Tomás, México, D.F., 11340, Mexico.
authors: L Gerardo
authors: LG
authors: Zepeda
authors: Eleuterio
authors: E
authors: Burgueño-Tapia
authors: Nury
authors: N
authors: Pérez-Hernández
authors: Gabriel
authors: G
authors: Cuevas
authors: Pedro
authors: P
authors: Joseph-Nathan
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D012015:Reference Standards; D012717:Sesquiterpenes / Q000032:analysis*; D012984:Software
chemical_list: D012717:Sesquiterpenes; C053752:perezone