Synthesis and reactions of tert-butyldiphenylsilyl ethers of sucrose

The reaction of sucrose with 1.1 mol. equiv. of tert-butyldiphenylsilyl (t-BDPS) chloride in pyridine in the presence of 4-dimethylaminopyridine gave the crystalline 6′-t-BDPS ether 1 in 49% yield, without recourse to column chromatography. Compound 1 was transformed into the 4,6,1′-trichloride by using sulphuryl chloride. When the silylation reaction of sucrose was performed with 3 mol. equiv. of the reagent, chromatography gave the crystalline 6,6′-di-t-BDPS ether and the 6,1′,6′-tri-t-BDPS ether 9 in yields of 78 and 18.7%, respectively. Compound 9 was obtained as the major product on treatment of sucrose with 4.6 mol. equiv. of the silylating reagent. Removal of the silyl protecting-group in 6,6′-di-O-tert-butyl-diphenylsilylsucrose hexabenzoate, using tetrabutylammonium fluoride, proceeded smoothly, but with 4→6 migration of the benzoate.