4-Toluenesulfonyl chloride → (3R,3aS,6R,6aR)-6-Hydroxyhexahydrofuro[3,2-b]furan-3-yl 4-methylbenzenesulfonate

Participants

Reaction Conditions

Reaction Steps

Isomannide (40) (10 g, 68.49 mmol) and p-toluenesulphonyl chloride (6.53 g, 34.25 mmol) were dissolved in a mixture of carbon tetrachloride (50 mL), dichloromethane (5 mL) and water (40 mL). The flask was cooled to 0° C. and a solution of potassium hydroxide (1.92 g, 34.25 mmol) in water (5 mL) added dropwise over 30 minutes with stirring. The resulting biphasic mixture was stirred at 0° C. for 7 hours. Then off-white precipitate was collected by filtration in vacuo then partitioned between dichloromethane (30 mL) and water (10 mL). The organic phase was washed with brine (2×10 mL) then dried (Na2SO4), filtered and reduced in vacuo to leave a colourless solid. Recrystallisation from carbon tetrachloride gave monotosylate (50) as colourless granules (3.92 g, 38%). TLC (Rf=0.11, EtOAc:heptane 1:1); analytical HPLC main peak, Rf=10.692 min; HPLC-MS 318.2, 323.1 [M+Na]+, 623.2 [2M+Na]+; [α]D18+72.2° (c=5.4, CHCl3); δH (500 MHz, CDCl3) 2.44 (3H, s, CH3), 3.54 (1H, dd, J=9.31 and 7.23 Hz, OCH2CHOH), 3.78 (1H, dd, J=9.18 and 7.59 Hz, OCH2CHOTs), 3.95 (1H, dd, J=9.36 and 6.45 Hz, OCH2CHOH), 4.01 (1H, dd, J=9.33 and 6.64 Hz, OCH2CHOTs), 4.26 (1H, m, CHOH), 4.42 and 4.48 (each 1H, brt, J=5.03 and 5.00 Hz respectively, CHCHCHOH and CHCHCHOTs), 4.90 (1H, dd, J=12.15 and 6.84 Hz, CHOTs), 7.37 (2H, d, J=8.13 Hz, aromatic CH3CCH), 7.82 (2H, d, J=8.20 Hz, aromatic OSO2CCH); δC (125 MHz, CDCl3) 21.69 (CH3), 70.03 (CH2CHOTs), 72.29 (CHOTs), 74.02 (CH2CHOH), 80.00 (CH2CHOH), 81.36 (CHCHOTs), 81.76 (CHCHOH), 128.00 and 129.89 (aromatic CH), 133.04 (CHOSO2C quaternary), 145.26 (CH3C quaternary).

Provenance & Evidence