Reaction Steps
A mixture of 3-O-allyl-2,4,6-tri-O-benzoyl-α-D-mannopyranosyl trichloroacetimidate (742 mg, 1.01 mmol) and the alcohol (25) (908 mg, 0.84 mmol) in 1,2-DCE (10 mL), was stirred in the presence of mol. sieves (1.0 g of 3 Å powder) under an atmosphere of argon (30 min). The mixture was cooled (0° C.) with continued stirring (10 min) prior to the addition of TMSOTf (181 μL, 1.01 mmol). After some time (10 min), Et3N (100 μL) was introduced and the mixture was filtered. The solvent was evaporated and the residue subjected to FC (10-50% EtOAc/hexane) to yield the hexabenzoate (26) as, a colourless oil (1.26 g, 90%). 1H NMR (CDCl3) δ 3.51-3.56, 3.66-4.06, 4.23-4.27, 4.30-42, 4.47-4.72, 4.78-4.86 (6 m, 26 H; H-2I,-3I,-4I,-5I,-6aI,-6bI,-3II,-5II,-6aI,-6bII,-3III,-5III,-6aIII,-6bIII, OCH2, ═CH2, CH2Ph), 5.04 (d, 1 H, J1,2 1.7 Hz; H-1I), 5.15 (dd, 1 H, J1,2 1.8, J2,3 2.7 Hz; H-2II), 5.26 (d, 1 H; H-1II), 5.28 (d, 1 H, J1,2 1.7 Hz; H-1III), 5.33-5.43 (m, 1 H; ═CH), 5.77-5.82 (m, 2 H; H-4II,-2III), 5.92 (dd, 1 H, J3,4 9.5, J4,5 9.8 Hz; H-4III), 7.00-7.61, 7.80-8.19 (2 m, 50 H; Ar).
