Highly Selective Primary Alkoxycarboxylation and Esterification of Unprotected Pyranose Derivatives Mediated by Scandium(III) Triflate Catalysis

A highly selective method for the alkoxycarboxylation and acylation of primary alcohols of pyranose derivatives is described. The reaction is high yielding and proceeds under mild conditions with 0.15–1 mol‐% Sc(OTf)3 used in combination with anhydrides or pyrocarbonates at 40–50 °C. Selectivities observed for alkoxycarboxylation of unprotected pyranose derivatives are > 95 %, and this constitutes a significant advantage over existing methods. Mechanistic implications, including the role of steric demand and metal–heteroatom coordination are also discussed. A novel Sc‐catalyzed alkoxycarboxylation and esterification reaction of unprotectedpyranose substrates is described. This method gives nearly complete selectivity compared with existing methods and avoids known problems with polycarboxylation/acylation. A preliminary mechanistic model is proposed.