title: Assignment of the relative configuration of spiro[4.5]decanes by 13C, 15N and 17O NMR.
abstract: The relative configuration of 11 1,4-diazaspiro[4.5]decanes (1a-1j and 1m), 15 1,4-oxazaspiro[4.5]decanes (2a-2o) and 10 1,4-dioxaspiro[4.5]decanes (3a-3n) substituted at the 2-, 6-, 7- or 8-position by a methyl group or using the tert-butyl group as a model for the ananchomeric structure is reported. The relative stereochemistry was analyzed by 1H, 13C, 15N and 17O NMR and all isomers present were characterized spectroscopically. Compounds with a methyl group in the six-membered ring show a chair conformation preference with the methyl group in the equatorial position. Compounds with one or two nitrogens exhibit a tautomeric equilibrium between the imine-diazolidine forms, as demonstrated by IR and 13C NMR.
authors.affiliation: Departamento de Química, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal, 14-740, 07000 México DF, Mexico.
authors.forename: Jorge Antonio
authors.initials: JA
authors.lastname: Guerrero-Alvarez
authors.forename: Antonio
authors.initials: A
authors.lastname: Moncayo-Bautista
authors.forename: Armando
authors.initials: A
authors.lastname: Ariza-Castolo
mesh_terms: D000473:Alkanes / Q000032:analysis* / Q000737:chemistry*; D002247:Carbon Isotopes; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008968:Molecular Conformation; D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes; D013141:Spiro Compounds / Q000032:analysis* / Q000737:chemistry*
chemical_list: D000473:Alkanes; D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes; D013141:Spiro Compounds; C012867:decane