Synthesis of furanose glycals from furanose 1,2-diols and their cyclic thiocarbonate esters

Furanosyl Oxocarbenium Ion Conformational Energy Landscape Maps as a Tool to Study the Glycosylation Stereoselectivity of 2‐Azidofuranoses, 2‐Fluorofuranoses and Methyl Furanosyl Uronates

“…We therefore took a different approach to generate the 2‐azidoxyloside (Scheme C). Thus, glycal 49 was functionalised by azidophenylselenation with TMSN 3 and N ‐(phenylseleno)phthalimide to give the desired 2‐azidoxyloside 50 with good diastereoselectivity ( xylo / lyxo 9:1) . Oxidative hydrolysis of the selenophenyl group by aqueous NIS then gave lactol 44 .…”

Chiral Synthesis of 4-[1-(2-Deoxy-β-l-ribofuranosyl)] Derivatives of 2-Substituted 5-Fluoroaniline: “Cytosine Replacement” Analogues of Deoxy-β-l-cytidine

“…For example, Garegg and Samuelsson have found that action of the iodine−triphenylphosphine−imidazole reagent on a vic - diol produced an unstable vic -diiodide that underwent an iodine-elimination reaction to afford the corresponding unsaturated sugar . The second reaction is related to the Corey and Hopkins dideoxygenation procedure, where the action of 1,3-dimethyl-2-phenyl-1,3,2-diazaphospholidine (DMPD) on a vic -diol thiocarbonate was shown to result in elimination to afford the olefin product, which has been used for the synthesis of enofuranosides and furanoid glycals . We adapted a method related to the Garegg and Samuelsson procedure 18 to prepare the ribofuranoid glycals 8a and 8b .…”

Diastereoselective Synthesis of C2′-Fluorinated Nucleoside Analogues Using an Acyclic Approach

“…To a solution of the known glycal − derived from l -xylose (1.75 g, 5.9 mmol, 1.0 equiv) in 10:1 DMF/H 2 O (30 mL, 0.18 M) was added Selectfluor (3.1 g, 8.8 mmol, 1.5 equiv). The reaction mixture was stirred at 25 °C for 16 h and concentrated.…”

“…The combined organic layers were dried over MgSO 4 , filtered, and concentrated in vacuo. Purification by flash chromatography (hexanes/EtOAc, 50:50) provided 39 (37 mg, 66%): R f = 0.39 (hexanes/EtOAc, 50:50); [α] 9,166.7,163.5,150.9,137.9 (d,J = 2.8 Hz),133.43,133.35,129.91,129.89,129.83,128.68,128.64,128.5,111.8,99.8 (d,J = 184.8 Hz) (+)-((2S,3R,4R,5R)-4-Fluoro-3-methyl-5-(5-methyl-2,4-dioxo-3,4dihydropyrimidin-1(2H)-yl)tetrahydrofuran-2,3-diyl)bis(methylene) Dibenzoate (40). To a solution of 39 (91 mg, 0.16 mmol, 1.0 equiv) in anhydrous THF (1.6 mL, 0.10 M) was added Me 2 S(SMe)BF 4 (61 mg, 0.31 mmol, 2.0 equiv).…”