Synthesis of 2.3-unsaturated polysaccharides from amylose and xylan

Abstract

Amylose ( 1) was tritylated at O-6, the ether p-toluenesulfonylated at O-2 and O-3, and the product ( 3) treated with sodium iodide and zinc dust in N,N-dimethyl-formamide, to give 2,3-dideoxy-6- O-trityl-α- D- erythro-hex-2-enopyranoglycan ( 4). This 2,3-unsaturated polysaccharide could be converted into a 2,3-dibromo derivative ( 5), and hydrogenated with concomitant detritylation to the saturated analogue ( 6), and, on treatment with aqueous acetic acid, it gave 2-( D- glycero-1,2-dihydroxyethyl)-furan ( 8). The 2,3-bis( p-toluenesulfonate) ( 10) of β- D-xylan ( 9) was similarly converted into the 2,3-unsaturated polysaccharide, 2,3-dideoxy-β- D- glycero-pent-2-enopyranoglycan ( 11), which, with aqueous acetic acid, gave 2-(hydroxymethyl)furan ( 12a).