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The proton magnetic resonance of heterocyclic diketones
Author(s) -
Galasso V.,
Pellizer G.,
Lisini A.,
Bigotto A.
Publication year - 1975
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270071206
Subject(s) - phthalic anhydride , chemical shift , chemistry , phthalimide , coupling constant , heteroatom , proton , proton nmr , perturbation theory (quantum mechanics) , spectral line , proton magnetic resonance , computational chemistry , ring (chemistry) , nuclear magnetic resonance , stereochemistry , organic chemistry , physics , quantum mechanics , catalysis
A full analysis of the 60 MHz 1 H NMR spectra of heterocyclic analogues of 1,3‐indandione [ N ‐(2‐bromoethyl)‐phthalimide, phthalic anhydride and thiophthalic anhydride] and of 1,2‐indandione ( N ‐methylisatin, coumarandione and 2,3‐dihydrothionapthene‐2,3‐dione) has been carried out. The protons of the symmetric compounds resonate at lower fields than those of the asymmetric ones and the proton ortho to the CO function is more deshielded than the proton ortho to the heteroatom. Coupled Hartree‐Fock perturbation theory has been applied to estimate the ring current contributions to the proton chemical shifts and to the magnetic susceptibilities. MO calculations based on the finite perturbation theory at the CNINDO levels provide information on the relative importance of σ and π pathways for the various coupling constants.