An electrophile-mediated cyclization on the 1,6-anhydro-D-glucopyranose framework

Article abstract of DOI:10.1016/0008-6215(93)80026-B

Iodocyclization of O-tributylstannyl-D-glucal with iodine in acetonitrile gave 1,6-anhydro-2-deoxy-2-iodo-β-D-glucopyranose (1) in high yield.The 3,4-di-O-acetyl derivative of 1 could be converted into the corresponding 2-deoxy compound and into the 2-C-allyl-2-deoxy branched sugar (5) by treatment with tributylstannane and allyltributylstannane, respectively.Controlled alkaline hydrolysis of 5 gave the 4-monoacetyl derivative.Complete hydrolysis of 5 gave the 3,4-diol, which underwent a 5-exo cyclization by treatment with N-bromosuccinimide. 1H NMR spectroscopy and X-ray analysis showed that the cyclized product has the B_3,0 conformation in its pyranose ring, which is trans-fused to the newly formed tetrahydrofuran ring.