反应详情

A 5 L three necked flask equipped with a mechanical stirrer and thermocouple is changed with [(2S)-7-nitro-2,3-dihydro-1,4-benzodioxin-2-yl]methanol (210.4 g, 0.996 mol) and anhydrous pyridine (600 mL). The flask is immersed in an ice/brine bath to achieve an internal temperature of 0-1° C. To this is added a solution of p-toluenesulfonyl chloride (220.0 g, 1.15 mol) is dissolved in pyridine (200 mL) over 30 min. The bath is allowed to expire, and the mixture is stirred for 18 h at room temperature. Water (1600 mL) is added at a constant rate over 45 min. The resulting suspension is stirred for 1 h, and then the precipitate is collected by vacuum filtration onto a medium porosity fritted funnel. The filter cake is washed with water (1600 mL) and suction dried under nitrogen to give [(2R)-7-nitro-2,3-dihydro-1,4-benzodioxin-2-yl]methyl 4-methylbenzenesulfonate (356.8 g, 98%) as a tan powder; m.p. 138° C. LCMS (Standard Method): 2.78 min, 388 (M+Na)+. 1H NMR (300 MHz, DMSO-d6) δ7.79-7.72 (m, 3H), 7.49-7.42 (m, 3H), 7.06 (d, J=8.8 Hz, 1H), 4.59-4.55 (m, 1H), 4.41 (dd, J=2.6, 11.6 Hz, 2H), 4.22 (dd, J=6.3, 11.5 Hz, 1H), 4.12 (dd, J=6.8, 11.7 Hz, 1H), 2.38 (s, 3H).

1. customThe flask is immersed in an ice/brine bath
2. customan internal temperature of 0-1° C
3. stirringThe resulting suspension is stirred for 1 h
4. filtrationthe precipitate is collected by vacuum filtration onto a medium porosity fritted funnel
5. washThe filter cake is washed with water (1600 mL) and suction
6. customdried under nitrogen