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CP/MAS spectroscopy in the determination of the tautomeric forms of gossypol, its Schiff bases and hydrazones in the solid state
Author(s) -
Przybylski Piotr,
Schilf Wojciech,
Kamienski Bohdan,
Brzezinski Bogumil,
Bartl Franz
Publication year - 2008
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2210
Subject(s) - tautomer , chemistry , gossypol , imine , aldehyde , heteronuclear single quantum coherence spectroscopy , schiff base , enamine , solid state , spectroscopy , stereochemistry , nuclear magnetic resonance spectroscopy , organic chemistry , catalysis , biochemistry , physics , quantum mechanics
New Schiff bases and new hydrazones were synthesized and studied by 13 C and 15 N CP/MAS spectroscopy and by 1 H 1 H COSY, 1 H 13 C HMBC, 1 H 13 C HSQC, 1 H 15 N HMQC and 1 H 15 N HSQC correlations. The CP/MAS investigation of gossypol has demonstrated that in the solid state it exists exclusively in the aldehyde‐aldehyde tautomeric form. In contrast, CP/MAS studies of hydrazones and Schiff bases reveal that these compounds occur in the solid state in the N ‐imine– N ‐imine and enamine–enamine tautomeric forms, respectively. It is shown that the 13 C resonances of C‐6, C‐7 and C‐11 carbon atoms are suitable for distinguishing between the tautomeric forms of aza‐derivatives of gossypol in the solid state. Furthermore, we have proved that the 15 N CP/MAS spectra can be used to identify these tautomeric forms. Copyright © 2008 John Wiley & Sons, Ltd.