Synthesis of 3-(Glycosyloxymethyl)isocoumarins and (S)-3-(Glycosyloxy­methyl)-3,4-dihydroisocoumarins by Coupling of Propargyl Glycosides with 2-Iodobenzoic Acid Mediated by Palladium Complex and Zinc Chloride

ABSTRACT Palladium-catalyzed coupling of propargyl glycosides with O-iodobenzoic acid leads to the selective syntheses of hitherto unknown, novel isocoumarin glycosides in 43-55% yields. We have observed that reduction of the keto acids to the corresponding alcohols was highly stereospecific due to the neighboring glycosyl substitution and leads to the formation of (S)-3-(glycosyloxymethyl)-3,4-dihydroisocoumarins in 21-37% overall yield.