par Zimmermann, Daniel ;Ottinger, Robert ;Reisse, Jacques ;Christol, Henri;Brugidou, J.
Référence Organic Magnetic Resonance, 6, 6, page (346-354)
Publication Publié, 1974
Article révisé par les pairs
Résumé : A large series of cyclohexane and cyclopentane spiro compounds has been studied by carbon‐13 NMR. Increments have been derived in terms of α, β, γ spiro substituent effects, one ring being considered as the substituent of the other. As usual α and β effects are paramagnetic and γ effects are diamagnetic. They are compared with the corresponding effects associated with the introduction of a gem dimethyl group into a cyclohexane or cyclopentane ring. The size of the two rings involved in the spirane structure has a marked influence especially on the chemical shift of the spirane carbon atom. Comparison between monospiro and dispiro derivatives gives information about the so‐called 1,5 or δ effect which is paramagnetic. From an analytical point of view, carbon‐13 NMR appears to be a powerful method of detecting the spirane structure, apparently including the relative size of the rings. Copyright © 1974 Heyden & Son Ltd.