Carbohydrate triflates: reaction with nitrite, leading directly to epi-hydroxy compounds

Development of a competitive binding assay for the Burkholderia cenocepacia lectin BC2L-A and structure activity relationship of natural and synthetic inhibitors

“…Finally, Lattrel-Dax conditions using nitrite ions as nucleophile reagent was tested on the triflate due to previous success in epimerisation of carbohydrate triflates. 42 Also under these conditions access to 28 remained unsuccessful. In contrast, a direct fluorination of the free hydroxy group in 27 using the reagent Deoxo-Fluor yielded the fluorinated compound 29…”

Synthesis of 7‐Deoxypancratistatin from Carbohydrates by the Use of Olefin Metathesis

“…To invert the configuration at the 3-position, two methods were tested. The free alcohol was converted into the corresponding triflate by treatment with triflic anhydride and reacted with either sodium nitrite [43] or sodium trifluoroacetate. [44] Both reactions gave a clean displacement of the triflate while leaving the primary iodide unaffected.…”

Stereocontrolled Total Syntheses of Shark Cartilage Chondroitin Sulfate D-Related Tetra- and Hexasaccharide Methyl Glycosides

“…KBr, NaHCO 3 , Ca(ClO) 2 , CH 2 Cl 2 , 0°C; then MeI, DMF, 50°C (74%); c, chloroacetic anhydride, pyridine/ CH 2 Cl 2 , 0°C (84%); d, CAN, toluene/MeCN/water; then CCl 3 CN, DBU, CH 2 Cl 2 , 0°C (70%) Preparation of the galactosaminyl acceptor 11 was then achieved (Scheme 2) by a route similar to those described for the synthesis of the CS-D disaccharide repeating unit. [17] Inversion of the configuration at C-4 in the known alcohol 8 [25] was achieved by treatment with triflic anhydride and pyridine in dichloromethane at low temperature, followed by nucleophilic displacement of the intermediate 4-triflate with sodium nitrite [26] in DMF to afford the crystalline -galacto derivative 9 in 60% overall yield. 1 H NMR spectra of 9 showed a signal with small coupling constants for 4-H (J 3,4 ϭ 3.1, J 4,5 ϭ 0.8 Hz), in full accord with the expected -galacto structure.…”