Oxidation glucofuranurono-6,3-lactones

Because direct glycosidation of 4 with phenols is not possible, indirect methods must be used for the preparation of aryl D-glucofuranosidurono-6,3-lactones (29). In addition, aryl 2,5-di-O-acetyl-D-glucofuranosidurono-6,3-lactones (30), obtained35-37 from the reaction of 1,2,5-tri-0-acetyl-D-glucofuranurono-6,3-lactones with phenols, can only be deacetylated by such multi-step procedures as (1) ammonolysis of 30 to afford aryl D-glucofuranosiduronamides (31), followed by amide hydrolysis and lactonization, 35,37 or (2) reduction of 30 with lithium aluminum hydride, and subsequent oxidation of the intermediate aryl D-glucofuranosides38 (32) (see Scheme 1). 

Two methods by which D-glucofuranurono-6,3-lactone (63) has been synthesized are shown in Scheme 9. The oxidation of starch to oxidized starch (64) has been described by a number of workers. Heyns and Graife338 were able to obtain 50-55% yields of 64 by oxidation with nitric acid plus nitrogen tetraoxide. From 64, D-glucofuran-... 

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