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Variable-Temperature 1H-NMR Studies on Two C-Glycosylflavones
Department of Chemistry, The University of the West Indies, St. Augustine, Trinidad and Tobago, West Indies
Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
* Authors to whom correspondence should be addressed.
Received: 5 April 2012; in revised form: 26 May 2012 / Accepted: 18 June 2012 / Published: 2 July 2012
Abstract: Two known C-glycosylflavones, swertisin and embinoidin, were isolated from the leaves of Anthurium aripoense, and characterized by room temperature 1D and 2D NMR experiments. At this temperature, the 1H- and 13C-NMR spectra of these C-glycosylflavones revealed doubling of signals, which suggested the presence of two rotamers in solution. Variable-temperature (VT) 1H-NMR studies supported this hypothesis. The T-ROESY data, in addition to the theoretical (MM2) calculations utilizing the Chem3D Pro software, confirmed the hypothesis that the two rotamers interchange via rotation about the C-glycosidic bond.
Keywords: variable-temperature 1H-NMR; C-glycosylflavones; rotamers; swertisin; embinoidin; Anthurium aripoense
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Frank, J.H.; Powder-George, Y.L.; Ramsewak, R.S.; Reynolds, W.F. Variable-Temperature 1H-NMR Studies on Two C-Glycosylflavones. Molecules 2012, 17, 7914-7926.
Frank JH, Powder-George YL, Ramsewak RS, Reynolds WF. Variable-Temperature 1H-NMR Studies on Two C-Glycosylflavones. Molecules. 2012; 17(7):7914-7926.
Frank, Julia H.; Powder-George, Yomica L.; Ramsewak, Russel S.; Reynolds, William F. 2012. "Variable-Temperature 1H-NMR Studies on Two C-Glycosylflavones." Molecules 17, no. 7: 7914-7926.