Stereoselective access to 2-deoxy-2-trifluoromethyl sugar mimetics by trifluoromethyl-directed 1,2-trans glycosylation

Fluorinated carbohydrate mimetics are valuable molecular fragments in contemporary Glycoscience. Available synthetic protocols are mainly restricted to the preparation of 'standard' monofluorinated derivatives, whereas their more complex C(sp(3))-CF3 congeners remain virtually underdeveloped. A protocol for accessing a series of previously uncharted 2-deoxy-2-trifluoromethyl-d-hexopyranosides from d-glycals is disclosed. The stereoselectivity of the glycosylation step, which is mainly governed by a combination of electronic and more dominant steric factors, revealed a pronounced substrate control rendering 1,2-trans glycosides as a result of the configuration of the CF3 moiety at C-2. The synthetic utility of this approach was demonstrated in the preparation of 2-CF3-glycoconjugates of natural origin, including disaccharides, cholesterol analogs, amino acids, and sphingosine/phytosphingosine derivatives.