Adaptation of an NMR signal suppression pulse sequence for the selective removal of benzylic methylene signals of benzyl ether-protected carbohydrates

Application of the DPFGSE-TOCSY pulse sequence permits the selective removal of benzylic signals from the 1H NMR spectra of benzyl ether-protected glycosides. Anomeric proton signals, which have a similar chemical shift, can be readily re-introduced with the aid of a TOCSY sequence. This approach is useful in cases where intense spectral overlap does not permit the straightforward identification of anomeric signals, and hence definition of anomeric configuration or determination of anomeric ratios. The representative application of this pulse sequence to analysis of iodine-promoted thioglycoside activation is reported.