J. Guerrero-Alvarez, Antonio Moncayo-Bautista, A. Ariza-Castolo
Jun 1, 2004
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Journal
Magnetic Resonance in Chemistry
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. Copyright © 2004 John Wiley & Sons, Ltd.