2-(TRIMETHYLSILYL)ETHYL (ME3SICH2CH2) GLYCOSIDES .10. SYNTHESIS OF 3'-DEOXYFLUOROLACTOSE AND 4'-DEOXYFLUOROLACTOSE AND ITS ME3SICH2CH2 AND CERAMIDE DERIVATIVES

(2-Trimethylsilyl)ethyl (Me3SiCH2CH2) 3'- and 4'-deoxyfluorolactosides (1 and 3) were synthesized by glycosylation of Me3SiCH2CH2 2,3,6-tri-O-benzyl-beta-D-glucopyranoside with 2,4,6-tri-O-acetyl-3-de-oxy-3-fluoro-beta-D-galactopyranosyl bromide and 2,3,6-tri-O-benzyl-4-deoxy-4-fluoro-beta-D-galactopyranosyl bromide. Anomeric deblocking of the fully acetyled Me3SiCH2CH2 glycosides (12 and 13) gave the corresponding hemiacetals 14 and 15. Removal of the acetyl groups gave 3'- and 4'-deoxyfluorolactose (2 and 4). The deoxyfluorolactosylceramides 5 and 6 were synthesized via boron trifluoride etherate- or silver triflate-activation of the trichloroacetimidates prepared from 14 and 15. Silver triflate-mediated glycosylations showed lower reaction rates, and fewer byproducts were formed.