Sugar Intermediates Used in the Synthesis of Glycosiduronic Acids

Sugar Intermediates Used in the Synthesis of Glycosiduronic Acids 

Kovac and colleagues20 prepared the bromide 1 in high yield by treating methyl tetra-O-acetyl-a- or -/3-D-glucopyranuronate (3) with di-bromomethyl methyl ether in the presence of zinc chloride the same type of reaction,21 but using boron trifluoride etherate as the catalyst,22 led20 to selective conversion of the 1,2-trans isomer of 3 into the fi an-omer of 1. 

Methyl (2,3,4-tri-O-acetyl-a-D-glucopyranosyl iodide)uronate, prepared by the method used for the corresponding D-glucoside derivatives, proved25 to be inadequate for the synthesis of D-gluco- 

Acetylation of D-glucopyranuronamide (obtainable either by treatment 9 of l,2-0-isopropylidene-o -D-glucofuranurono-6,3-lactone with concentrated aqueous ammonia, followed by dilute acid, or by reac-tionSD of the unprotected lactone with methanol-aqueous ammonia), followed by treatment of the peracetate with hydrogen bromide-ace- 

Methyl-,4C D-glucuronate was prepared44 from the D-glucofuran-uronic acid derivative 22 (obtained by benzylidenation of D-glu-curonic acid in the presence of zinc chloride) by treating its sodium salt with methyl-14C iodide, followed by hydrogenolysis of the ester 23 in the presence of palladium-on-carbon the infrared (i.r.) spectrum of the product was identical to that of authentic 2. 

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II. Sugar Intermediates Used in the Synthesis of Glycosiduronic Acids. .. 59... 

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