Dependence of 1H NMR chemical shifts of geminal protons of glycosyloxy methylene (H2-26) on the orientation of the 27-methyl group of furostane-type steroidal saponins.
An approach based on the difference (Delta(ab) = delta(a) - delta(b)) between the 1H NMR chemical shifts (delta(a), delta(b)) of the geminal protons of glycosyloxy methylene (H2-26) (Delta(ab) = <0.48 for 25R; Delta(ab) = >0.57 for 25S) is proposed for ascertaining 25R/25S orientation of the 27-methyl group of furostane-type steroidal saponins. These studies suggested the 25R-orientation of the 27-Me group for the furostanol glycosides isolated by Wu et al. from Tribulus terrestris.
Agrawal
Pawan K
PK
Central Institute of Medicinal and Aromatic Plants, Lucknow-226015, India. pkagrawal11@hotmail.com
D006838:Hydrocarbons; D006859:Hydrogen; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011522:Protons; D012503:Saponins / Q000737:chemistry* / Q000302:isolation & purification; D013256:Steroids / Q000737:chemistry* / Q000302:isolation & purification; D032444:Tribulus / Q000737:chemistry*
D006838:Hydrocarbons; D011522:Protons; D012503:Saponins; D013256:Steroids; C030011:carbene; D006859:Hydrogen; D008697:Methane