Scandium cation-exchanged montmorillonite catalyzed direct C-glycosylation of a 1,3-diketone, dimedone, with unprotected sugars in aqueous solution

The condensation of dimedone with unprotected sugars in aqueous solution in the presence of a catalytic amount of Sc3+-montmorillonite (Sc3+-mont) gave 9-hydroxyalkyl-3,3,6,6,-tetramethyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones in good yields, while the use of Sc(OTf)3 instead of Sc3+-mont gave the hydroxyalkyl-6,7-dihydrobenzofuran-4(5H)-one derivatives in good yields. Furthermore, Sc3+-mont could be recycled without inactivation.

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