The First Mineral-Catalyzed One-Pot [3+1+2] Coupling Protocol for Multifunctionalized Fused-Ring Pyrimidines

This is the first report on montmorillonite K-10 clay (nanoclay)-catalyzed, domino reactions of unprotected D-glucose/D-xylose with amidines/guanidine and an activated natural amino acid 2-phenyl-1,3-oxazol-5-one. The procedure results in an efficient annulation of the iminosugar moiety with functionalized pyrimidines in excellent yields (79-92%) with high trans-diastereoselectivity (>94%). The reaction is effected under solvent-free microwave irradiation conditions via amidine/guanidine-driven coupling and ring-transformation reactions in a one-pot procedure.