ABSTRACT

Experimental .......................................................................................................... 184 General Methods ............................................................................................... 184 1,3,4,6-Tetra-O-acetyl-α-d-glucopyranose (2) ................................................. 184

Method A, from d-glucose (1) ...................................................................... 184 Method B, from 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide (3) ... 185

Acknowledgments .................................................................................................. 185 References .............................................................................................................. 187

Regioselective, partial protection is an important transformation in carbohydrate chemistry as it simplies preparation of differentially substituted synthetic intermediates. One such procedure is the synthesis of tetraacetyl glucose 2. The method for obtaining 2 was originally presented by Helferich and Zirner1 and involved a multistep reaction that eventually led to a mixture of hemiacetal (1-OH derivative) and 2, from which the latter could be isolated in pure form by crystallization in a modest yield of 27%. Chromatographic purication of the material in the mother liquor is impractical due to the propensity of 2 to rapidly isomerize into its more stable hemiacetal counterpart. Since 2 is an important building block, the original protocol is still in frequent use.