An approach to stereoselective preparation of 3-C-glycosylated D- and L-glucals.

ABSTRACT

An approach to stereoselective synthesis of alpha- or beta-3-C-glycosylated L- or D-1,2-glucals starting from the corresponding alpha- or beta-glycopyranosylethanals is described. The key step of the approach is the stereoselective cycloaddition of chiral vinyl ethers derived from both enantiomers of mandelic acid. The preparation of 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4,6-tetra-O-benzyl-beta-D-glucopyranosyl)methyl]-L-arabino-hex-1-enitol, 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4,6-tetra-O-benzyl-beta-D-glucopyranosyl)methyl]-D-arabino-hex-1-enitol, and 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl)methyl]-D-arabino-hex-1-enitol serves as an example of this approach.