Glycosyl thiols are widely used in stereoselective S-glycoside synthesis. Their epimerization from 1,2-trans to 1,2-cis thiols (e.g., equatorial to axial epimerization in thioglucopyranose) was attained using TiCl4, while SnCl4 promoted their axial-to-equatorial epimerization. The method included application for stereoselective β-d-manno- and β-l-rhamnopyranosyl thiol formation. Complex formation explains the equatorial preference when using SnCl4, whereas TiCl4 can shift the equilibrium toward the 1,2-cis thiol via 1,3-oxathiolane formation.
CITATION STYLE
Doyle, L. M., O’Sullivan, S., Di Salvo, C., McKinney, M., McArdle, P., & Murphy, P. V. (2017). Stereoselective Epimerizations of Glycosyl Thiols. Organic Letters, 19(21), 5802–5805. https://doi.org/10.1021/acs.orglett.7b02760
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