J. BeMiller, H. Muenchow
Jun 1, 1973
Citations
0
Influential Citations
7
Citations
Journal
Carbohydrate Research
Abstract
Abstract The dealkylation of benzylated carbohydrates by free-radical bromination and hydrolysis has been further examined. Free-radical bromination of methyl 2,3,4,6-tetra- O -benzyl-α- D -glucopyranoside ( 1 ) methyl 2,3-di- O -benzyl-α- D -glucopyranoside ( 2 ) 6- O -benzyl-3,5- O -benzylidene-1,2- O -isopropylidene-α- D -glucofuranose ( 4 ) and 6- O -benzyl- D -glucose ( 3 ) appears to be quantitative. Spectroscopic evidence of a CBr bond indicates that an α-bromobenzyl ether is the product. Alkaline hydrolysis yielded methyl α- D -glucopyranoside from 1 and 2 and D -glucose from 3 and 4 . A benzyl group present as an aglycon could be removed in the same way. Reaction of benzyl α- D -glucopyranoside tetraacetate ( 6 ) with bromine and chlorine under free-radical conditions and examination of the products by t.l.c. and i.r. spectrophotometry indicated that the first product was an α-halobenzyl glycoside and that the aglycon could be displaced by Br - or Cl - to form the tetra- O -acetyl- D -glucopyranosyl halide, undoubtedly with anomerization. Treatment of the mixture of products with moist ether and silver carbonate yielded only 2,3,4,6-tetra- O -acetyl- D -glucopyranose.