Efficient Synthesis of an Allose-Containing Analogue of the Phytoalexin-Elicitor Glucohexaose and Its Dodecyl Glycoside

An allose-containing analogue 2 of thephytoalexin elicitor β-(1→3)-branched β-(1→6)-linkedglucohexatose and its dodecyl glycoside 3 hasbeen regio- and stereospecifically synthesized. As a typical exampleof the method, the synthesis of 2 was achieved viacoupling of the trisaccharide donor 2,3,4,6-tetra- O-benzoyl-β- D-glucopyranosyl-(1→3)-[2,3,4,6-tetra- O-benzoyl-β- D-glucopyranosyl-(1→6)]-1,2- O-isopropylidene-α- D-allopyranosyl trichloroacetimidate ( 9) with a trisaccharide acceptor. The donorwas prepared easily from 1,2:5,6-di- O-isopropylidene-α- D-allofuranose ( 5)and 2,3,4,6-tetra- O-benzoyl-α- D-glucopyranosyl trichloroacetimidate ( 4) in a regio- and stereoselective manner.