SYNTHESIS OF 4 DIASTEREOMERIC OCTOFURANOSES FROM D-GLUCOFURANURONO-6,3-LACTONE VIA GRIGNARD REACTIONS

Reduction of 5-O-tert-butyldimethylsilyl-1,2-O-isopropylidene-alpha-D-gluco- (2) and -beta-L-idofuranurono-6,3-lactone (3) with diisobutylaluminum hydride (DIBAL-H) to the respective hemiacetal at C-6, followed by reaction with vinylmagnesium bromide in either ether or tetrahydrofuran, gives the corresponding diastereomeric pairs of 7,8-dideoxyoct-7-eno-1,4-furanoses. The configurations of the products at C-6 were determined after oxidative cleavage of the terminal double bond and reduction of the aldehyde by conversion of the resulting heptoses into the known corresponding per-O-acetylated heptitols.