Synthetic routes to higher-carbon sugars. 1-C-Formylation of a 2-deoxyaldose via the anion of its diethyl dithioacetal

Diphenylmethylation of carbohydrate hydroxyl groups may be effected by the thermal reaction with diazo(diphenyl)methane in the absence of catalysts. Migration of the labile ester groups of methyl 2,3,4-tri-O-acetyl-α-d-glucopyranoside and 3-O-benzoyl-1,2-O-isopropylidene-α-d-glucofuranose does not occur during diphenylmethylation by this procedure. The diphenylmethyl group may be readily removed by catalytic hydrogenolysis, and is sufficiently acid-stable to enable the selective hydrolysis of acetal groups. Its use as an O-4 protecting-group and as a non-participating O-2 protecting-group in α-glycoside synthesis has been demonstrated in syntheses of methyl 2,3,6-tri-O-methyl-α-d-glucopyranoside and kojibiose octa-acetate, respectively.