GIAO DFT 13C/15N chemical shifts in regioisomeric structure determination of fused pyrazoles.
The combined use of two-dimensional NMR correlation experiments and gauge including atomic orbital density functional theory in (13)C NMR chemical shift (CS) calculations allowed reliable and simple structural determination of regioisomeric heterocyclic systems that originate from the reactions of acylquinolinones with substituted hydrazines. Moreover, the results of differential analysis between the calculated (15)N NMR CSs for hypothetical structures and the experimental data of the title azaheterocyclic systems were even more advantageous with respect to (13)C because there was no need for correlational analysis: structures of the regioisomeric compounds could be determined just by direct comparison.
Chimichi
Stefano
S
Department of Chemistry, University of Firenze, Firenze, Italy. stefano.chimichi@unifi.it
Boccalini
Marco
M
Matteucci
Alessandra
A
Kharlamov
Sergey V
SV
Latypov
Shamil K
SK
Sinyashin
Oleg G
OG
D002247:Carbon Isotopes; D003198:Computer Simulation; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D015394:Molecular Structure; D009587:Nitrogen Isotopes; D011720:Pyrazoles / Q000737:chemistry*; D012015:Reference Standards; D013237:Stereoisomerism
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D011720:Pyrazoles