Highly stereoselective synthesis of C-vinyl pyranosides via a Pd0-mediated cycloetherification of 1-acetoxy-2,3-dideoxy-oct-2-enitols

• C-Vinyl α-gluco, α-galacto, and β-mannopyranosides are selectively prepared.
• Pd0-mediated cyclization affords C-vinyl glycosides by substrate control.
• Double diastereoselection using DACH ligands amplifies the cyclization selectivity.
• The C-vinyl pyranosides have a free C-2 OH for further elaboration.

Oct-2-enitols undergo a Pd0-mediated cyclization to produce C-vinyl α-gluco- and α-galactopyranosides, and C-vinyl β-mannopyranoside in good yield and with high stereoselectivity. While substrate control demonstrates a clear stereochemical preference during cyclization, the α- and β-epimeric ratios are enhanced by double diastereoselection using the (S,S) or (R,R)-DACH ligands.

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