Synthesis and reactions of an (α-d-glucopyranosyl)phenylacetylene

Silver tetrafluoroborate promoted addition of (phenylethynyl)tributylstannane to 6-O-acetyl-2,3,4-tri-O-benzyl-α-d-glucopyranosyl chloride stereoselectively gave a crystalline (α-d-glucopyranosyl)phenylacetylene (4) in 73% yield. Compound 4 was epimerized to the β isomer through its hexacarbonyldicobalt complex, and was also converted into a C-α-glycosyl aldehyde (8) by sequential zinc reduction and ozonolysis. The sensitive aldehyde 8 was conveniently isolated and manipulated through its 1,3-diphenylimidazolidine derivative.