Reaction Steps
To an ice-cold solution of 2 (10 g, 60.9 mmol) in dry tetrahydrofuran (350 mL) was added sodium hydride (60% dispersion in mineral oil, 14.8 g, 370 mmol) and the reaction mixture was stirred for 15 min under N2. To this reaction mixture was added solid tetrabutylammonium iodide (0.36 g, 0.96 mmol) followed by a dropwise addition of benzyl bromide (36.6 g, 214 mmol). The reaction mixture was stirred for 3 days at room temperature. After the addition of methanol (25 mL) the solution was evaporated under reduced pressure, and the crude product was purified by silica gel chromatography (cyclohexane/EtOAc, 9: 1) to afford pure methyl 2,3,5-tri-O-benzyl-L-xylofuranoside (3, 23 g, 87% yield). MS 435 (M+H)+, 433 (M−H)+, 403 (M−OCH3)+; 1H NMR (CDCl3)δ 7.38-7.25 (m, 30H, aromatic H=s), 4.94 (d, 1H, H−1α, J1,2=4.3 Hz), 4.87 (d, 1H, H−1β, J,1,2 =0.9 Hz), 4.64-4.45 (m, 12H, PhCH2's), 4.37 (m, 1H, H−4α), 4.27 (dt, 1H, H−4β, J4,5a=3.7 Hz, J4,5b=6.5 Hz, J3,4=6.2 Hz), 4.17 (t, 1H, H-3α, J3,4=6.9 Hz, J2,3=5.6 Hz), 4.07 (dd, 1H, H-3β, J3,4=6.2 Hz, J2,3=2.5 Hz), 4.00 (dd, 1H, H-2α, J2,3=5.6 Hz), 3.95 (t, 1H, H-2β, J2,3=2.5 Hz), 3.70 (dd, 1H, H-5aα, J4,5a=4.5 Hz, J5a,5b=10.4 Hz), 3.66 (dd, 1H, H-5aβ, J4,5a=3.7 Hz, J5a,5b=10.7 Hz), 3.54 (dd, 1H, H-5bα, J4,5b=7.5 Hz), 3.49 (dd, 1H, H-5bβ, J4,5b=6.5 Hz).
