Stereoselective synthesis of (1-alkoxyalkyl) alpha- and beta-D-glucopyranosiduronates (acetal-glucopyranosiduronates): a new approach to specific cytostatics for the treatment of cancer.

The reaction of methyl 2,3,4,6-tetra-O-acetyl-1-O-trimethylsilyl-beta- and -alpha-D-glucopyranuronate severally with the dimethyl or diethyl acetals of formaldehyde, bromoacetaldehyde, propionaldehyde, 3-benzyloxypropionaldehyde, 5-carboxypentanal, and 2-bromohexanal in the presence of catalytic amounts of trimethylsilyl trifluoromethanesulfonate at -78 degrees gave the corresponding (1-alkoxyalkyl) alpha- and beta-glycosides (acetal-glucopyranosiduronates) with retention of configuration at C-1 in yields of 41-91%. Instead of the dialkyl acetals, the corresponding aldehydes and alkyl trimethylsilyl ether can be used. Deacetylation gave the corresponding methyl (acetal-beta- and -alpha-D-glucopyranosid)uronates in good yield. De-esterification of methyl [(1R)-1-methoxybutyl beta-D-glucopyranosid]uronate with esterase gave the acetal-beta-D-glucopyranosiduronic acid which was an excellent substrate for beta-D-glucuronidase.