Reaction Steps
A solution of 8.76 g of (3S,3aS,6R,6aR)-hexahydro-furo[3,2-b]furan-3,6-diol in 80 ml of pyridine is stirred for 16 hours with 13.7 g of toluenesulfonylchloride, solvent is distilled off and the distillation residue is dissolved in EtAc and extracted with 1N HCl, saturated aqueous NaHCO3-solution and H2O. The organic layer obtained is dried, solvent is evaporated and the evaporation residue is subjected to chromatography. Toluene-4-sulfonic acid (3S,3aS,6R,6aR)-6-hydroxy-hexahydro-furo[3,2-b]furan-3-yl ester (a) and toluene-4-sulfonic acid (3R,3aS,6S,6aR)-6-hydroxy-hexahydro-furo[3,2-b]furan-3-yl ester (b) are obtained. 1HNMR(DMSO-d6) of form (a): 7.8 (d,2H,Ar—H,J=8.2 Hz), 7.5 (d,2H,Ar—H,J=8.6 Hz), 4.95 (d,1H,6-OH), 4.8 (m, 1H, H-3), 4.42 (dd,1H,H-6a,J=4.6 and 4.8 Hz), 4.38 (d,1H,H-3a,J=4.6), 4.08 (m,1H,H-6), 3.8 (m,2H,2×H-2), 3.7, 3.25 (2×dd, 2H, 2×H-5), 2.4 (s, 3H, Ar—CH3). 1HNMR(DMSO-d6) of form (b): 7.8 (d,2H,Ar—H,J=8.6 Hz), 7.5 (d,2H,Ar—H,J=8.6 Hz), 5.15 (d, 6-OH, J=3.5), 4.9 (m, 1H, H-3), 4.45 (dd,1H,H-3a,J=4.3 and 4.8 Hz), 4.2 (d,1H,H6a,J=4.3), 4.0 (m,1H,H-6), 3.7 (m,3H,H-2 and 2×H-5), 3.5 (dd,1H,H-2,J=9.5 and 6.3 Hz), 2.4 (s, 3H, Ar—CH3).
