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DOI: 10.1055/s-0028-1084976
Conformational analysis of Hyptolide by DFT molecular modeling calculations and theoretical versus experimental NMR coupling constants analysis
Hyptolide belongs to a relevant group of cytotoxic compounds which occur in several members of the Lamiaceae family [1]. The conformational analysis of this highly flexible polyacylated-6-heptenyl-5,6-dihydro-2H-pyran-2-one was ascertained by a molecular modeling protocol which includes extensive systematic conformational searching [2], geometry optimization by DFT B3LYP/DGDZVP calculations, and comparison between the theoretical (DFT-GIAO) and experimental 1H-1H NMR couplings [3]. For the 28 more stable conformations, the root mean square difference between the observed and calculated couplings was smaller than 1Hz assuring the accuracy of the models.
Acknowledgements: Financial support from Conacyt is acknowledged (grant 45759-Q). Geometry optimizations and coupling constant calculations were performed in the Kan-Balam cluster at DGSCA, UNAM.
References: 1. Achmad, S. A. et al. (1987) Acta Chem. Scand. 41B: 599–609.
2. Pereda-Miranda, R. et al. (2001) Tetrahedron 57: 47–53.
3. Wolinski, K. et al. (1990)J. Am. Chem. Soc. 112: 8251–8260.