Synthesis of 2-deoxy-C-glycosides via Lewis acid-mediated rearrangement of 2,3-anhydro-1-thiopyranosides?

Organic Chemistry Frontiers Pub Date: 2014-07-09 DOI: 10.1039/C4QO00113C

Abstract

An approach to the regio- and stereo-selective construction of 2-deoxy-C-glycosides via Lewis acid-mediated rearrangement of 2,3-anhydro-1-thiopyranosides is disclosed. Treatment of 2,3-anhydro-1-thiopyranosides with phenols in the presence of TMSOTf, the migration–O-glycosylation and Fries-like O to C rearrangement took place in succession, providing aryl 2-thio-2-deoxy-C-glycosides with the single thermodynamically favourable configuration (1C4 or 4C1) in good to excellent yields. The coupling reaction of 2,3-anhydro-1-thiopyranosides with trimethylsilylated or tributylstanylated nucleophiles in the presence of TMSOTf or Sc(OTf)3, via the migration–C-glycosylation process, afforded 2-thio-2-deoxy-C-glycosides in a stereospecific manner in moderate to good yields and with the C-1 and C-2 substituents opposite. The 2-thio-functionality was further removed to produce the corresponding 2-deoxy-C-glycosides. This method may provide a convenient route for the preparation of 2-deoxy-C-glycosides.

Graphical abstract: Synthesis of 2-deoxy-C-glycosides via Lewis acid-mediated rearrangement of 2,3-anhydro-1-thiopyranosides
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