Deoxygenation/dimerization of sugar derivatives with BF3·Et2O–Et3SiH: synthesis of a β-isonucleoside

Exploitation of in Situ Generated Sugar-Based Olefin Keto-Nitrones: Synthesis of Carbocycles, Heterocycles, and Nucleoside Derivatives

“…In a comparable fashion for the synthesis of a hexahydrofuro-[3,4-b]furan ring (via Path C), the 1-deoxy sugar derivative 31 41 upon oxidation of the hydroxyl group by DMP, followed by nitrone generation using BnNHOH and its in situ cyclization, smoothly afforded the isoxazolidine-fused bisfuran derivative 32 in 62% yield (Scheme 7). The product was characterized by NMR spectral analyses, and its stereochemistry at the ring juncture was determined by single-crystal X-ray analysis of one of its derived products 42.…”

“…[α] D 25 − 7 (c 0. ((3S,3aS,6R,6aR)-3a-Acetamidohexahydrofuro[3,4-b]furan-3,6-diyl)bis(methylene)diacetate (41). Isoxazolidine ring cleavage, followed by debenzylation and acetylation, was carried out, following the procedure as described in 40, using 32 (500 mg, 1.36 mmol) in MeOH (20 mL), Pd/C (10%, 80 mg), pyridine (20 mL), Ac 2 O (0.81 mL), and DMAP (pinch).…”

Allyloxy and Propargyloxy Group Migration: Role of Remote Group Participation in the Synthesis of 5-C-Nucleosides and Other Sugar Derivatives

“…Surprisingly, we observed the formation of dioxabicyclo[2.2.1]heptane derivatives through participation of the C(5)ÀOÀBn group and loss of Bn. Thus the D-glucose-based tetrahydrofuran derivative 1, 26 after triflate formation, reacted with 6-chloropurine in DMF to afford the bicyclic compound 2 (Scheme 1). Indeed, the reaction carried out in DMF alone at 110À120 °C, without the addition of 6-chloropurine, furnished the same product in very good yield.…”