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15 N‐NMR‐Studien der Tautomerie in N ‐monosubstituierten Amidinen und in N , N ′‐Diphenylguanidin
Author(s) -
Clement Bernd,
Kämpchen Thomas
Publication year - 1986
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19861190331
Subject(s) - tautomer , chemistry , chemical shift , medicinal chemistry , nuclear magnetic resonance spectroscopy , stereochemistry , alkyl , carbon 13 nmr , organic chemistry
15 N NMR Studies of the Tautomeric Equilibrium of N ‐Monosubstituted Amidines and of N , N ′‐Diphenylguanidine 15 N NMR data are reported for tautomeric N ‐monosubstituted amidines 1a and b and for N , N ′‐diphenylguanidine ( 6 ). In order to elucidate the position of the tautomeric equilibrium, the nitrogen resonances of the salts of 1a, b and 6 were also determined. For comparison, chemical shifts δ 15 N were measured of non‐tautomeric amidines 2 – 5 . The preferred tautomers for N ‐phenylbenzamidine ( 1a ) and for 6 have the CN double bond conjugated with the phenyl group. Replacement of an NH proton with an alkyl group, as in 1b , has little effect on the tautomeric equilibrium of amidines.