SYNTHESIS OF 3-CYANO-Δ2- AND -Δ3-DIHYDRO-PYRAN AND -THIOPYRAN DERIVATIVES

Article abstract of DOI:10.1016/S0008-6215(00)90095-8

Treatment of trans, trans-3,5-diacyloxy-r-4-tert-butoxycarbonyl-4-cyano-tetrahydropyran (1a-b) and -tetrahydrothiopyran (1c-d), 5-(2,4-di-O-acyl-3-tert-butoxycarbonyl-3-cyano-3-deoxy-β-D-xylo-pentopyranosyl)-3-ethoxycarbonyl-2-methylfuran (2a-b) and -3-acetyl-2-methylfuran (2c-d), and methyl 2,4,6-tri-O-acetyl-3-tert-butoxycarbonyl-3-cyano-3-deoxy-α-D-gluco-hexapyranoside (3) with toluene-p-sulfonic acid in acetic anhydride gave the corresponding branched unsaturated compounds, 5-acetyl-4-cyano-5,6-dihydro-2H-pyran (4a-b) and -thiopyran (4c-d), 5-(4-O-acyl-3-cyano-2,3-dideoxy-β-D-glycero-pent-2-enopyranosyl)-furans (5a-d) (minor), 5-(2-O-acyl-3-cyano-3,4-dideoxy-β-D-glycero-pent-3-enopyranosyl)furans (6a-d) (major), and methyl 2,6-di-O-acetyl-3-cyano-3,4-dideoxy-α-D-erythro-hex-3-enopyranoside (7).