Neighboring-Group Participation. The Preparation of Derivatives of D-Ribose and L-Lyxose from L-Arabinose¹

An alternative synthesis of anomeric methyl 2-deoxy-4-thio-D-erythro-pentofuranosides

“…Methyl 2-O-Benzoyl-3-O-p-toluenesulf onyl-4-0-(2-methoxyisopropyl)-d-L-arabinopyranoside (3). Compound 1 (41 g) was dissolved in a mixture of alcohol-free chloroform (100 ml) and anhydrous benzene (100 ml) with stirring.…”

“…The reaction mixture was neutralized by the addition of triethylamine (1 ml) and concentrated to a syrup. On addition of absolute ethanol, 3 crystallized readily, mp 118-119 °C. The yield was quantitative: [a]23D +198.3°( c 2.9, CHCI3); NMR (CDCI3) 1.41 (s, 6 H, 2 CCH3), 2.29 (s, 3 H, tosyl CH3), 3.30 and 3.33 (two s, 6 H, 2 OCHg), 3.77 (m, 2 , H-5), 4.35 (m, 1 , H-4), 4.88-5.63 (m, 3 H, H-l, H-2, and H-3), 6.98-7.88 (m, 9 H, aromatic).…”

“…A portion (2 g) of this mixture was separated by chromatography on a dry silica gel column, eluted with a benzene-ethyl acetate-triethylamine (10:1:1) mixture to give syrupy products 6 (1.8 g) and 7 (0.15 g). For 6: NMR (acetone-de) 1.35 (s, 6 H, 2 CCH3), 3.21 and 3.35 (two s, 6 H, 2 OCH3), 4.48 (d of d, 1 H, J\-2,2• -2.7 and 7. 4 Hz, H-l).…”

“…The readily available starting material, methyl 2-O-benzoyl-3-O-p-toluenesulfonyl-d-L-arabinopyranoside (1), was prepared from methyl 2-0-benzoyl-/3-L-arabinopyranoside by a slight modification of the procedure of Reist et al 3 It has been reported that compound 1 when treated with 2 mol of sodium methoxide in methanol at room temperature for 18 h gives an 80% yield of semicrystalline methyl 2,3-anhydrod-L-lyxopyranoside3 (2). In addition, Buchanan and Fletcher4 showed that treatment of the 4-0-acetyl derivative of 1 with 3 mol of sodium methoxide in methanol at room temperature for 6 h gave a 1:5.6 mixture of methyl 3,4-anhydro-/J-L-arabinopyranoside and 2 in 61% yield; formation of the second epoxide derivative is thought to be due to migration of the epoxide.…”

A heterogeneous Pd–Bi/C catalyst in the synthesis of l-lyxose and l-ribose from naturally occurring d-sugars

“…1) has interesting biochemical properties. Reist et al 4 synthesized the L-lyxose derivative, methyl b-L-lyxopyranose, by inversion of the 3-hydroxyl group of an Larabinose derivative. However, the yield for this method was low (<13%).…”