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13C n.m.r. spectra of 2-substituted pyrimidines

✍ Scribed by Christopher J. Turner; Gordon W. H. Cheeseman

Publisher: John Wiley and Sons
Year: 1976
Tongue: English
Weight: 394 KB
Volume: 8
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1270080707

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✦ Synopsis

Abstract

^13^C n.m.r. chemical shifts and carbon‐proton coupling constants of 2‐substituted pyrimidines are reported. The carbon chemical shifts are correlated with π‐electron densities. Substituents which cause deshielding at the directly bound carbon (e.g. NH~2~, OCH~3~ and F) exert a more powerful effect in the benzene series than in the pyridine or pyrimidine series. The carbon‐proton coupling constants do not correlate with the electronegativity of the substituents. Carbon‐proton coupling constants and proton‐proton coupling constants over the same number of bonds do not obey the Karabatsos relationship. The changes in the carbon‐proton coupling constants in 2(1H)‐pyrimidinone and 2(1H)‐pyrimidinethione which accompany anion and cation formation are reported.

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