Application of Soft Pulse 1D NMR: Sweroside from a Potential Native American Anti-TB Drug

Soft pulse 1D H NMR was shown to be a powerful method in the structure determination of sweroside (1), a major secoiridoid isolated from Nyssa ogèche. Selective excitation of the two proton spin systems due to the sugar and the aglycone moiety allows separation of overlapping signals and provides rapid access to information concerning both coupling behaviour and glycosidic linkage. The results of selective TOCSY and selective ROESY experiments were compared with analogous 2D NMR methods, while inverse detected C, H-correlations (HMQC, HMBC) definitively confirmed the assignments of all proton and carbon resonances.