Detailed 1H and 13C NMR structural assignment and relative stereochemistry determination for three closely related sesquiterpene lactones.
A complete analysis of (1)H and (13)C NMR spectra of the trypanocidal sesquiterpene lactone eremantholide C and two of its analogues is described. These structurally similar sesquiterpene lactones were submitted to (1)H NMR, (13)C {(1)H} NMR, gCOSY, gHSQC, gHMBC, J-resolved and DPFGSE-NOE NMR techniques. The detailed analysis of those results, correlated to some computational calculations (molecular mechanics), led to the total and unequivocal assignment of all (1)H and (13)C NMR data. The determination of all (1)H/(1)H coupling constants and all signal multiplicities, together with the elimination of previous ambiguities were also achieved.
Heleno
Vladimir Constantino Gomes
VC
Departamento de Química, Centro de Ciências Exatas e de Tecnologia, Universidade Federal de São Carlos, Via Washington Luiz, km 235, 13565-905, São Carlos, SP, Brazil. heleno.vcg@unifran.br
de Oliveira
Kleber Thiago
KT
Lopes
João Luis Callegari
JL
Lopes
Norberto Peporine
NP
Ferreira
Antonio Gilberto
AG
D002247:Carbon Isotopes / Q000032:analysis / Q000737:chemistry; D007783:Lactones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011522:Protons; D012717:Sesquiterpenes / Q000737:chemistry*; D013237:Stereoisomerism
D002247:Carbon Isotopes; D007783:Lactones; D011522:Protons; D012717:Sesquiterpenes