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Iodocyclisation of 6-O-protected-D-galactal, followed by radical reduction, gives [2.2.1] bicyclic acetals which are regioselectively opened by various nucleophiles (alcohols, allyltrimethylsilane, triphenylphosphine) to give furanosyl compounds.

Addition of the allylsilane Me3SiCH2C:CH2CH2CO2Me to d -gluco and d -galactopyranosyl derivatives gives in good yields α-C-glycopyranosides which are easily converted into glycosylated β-keto esters, butenolide and dihydropyrone.

Cp 2 Zr(ClO 4 ) 2 was used as a promoter for nucleophilic addition of 2-(trimethylsilyloxy) furan (TMSOF) to 2,3,4,6-tetra- O -benzyl- d -glucopyranosyl fluoride to give a 2:1:1 mixture of adducts in 80% yield. NMR data and postulated transition states are consistent with a 3:1 ratio of regioisomers at C-5 and C-3 of TMSOF and a 2:1 ratio of threo and erythro α-adducts at C-5.