A 500 mL three necked flask equipped with a magnetic stir bar and thermocouple and the pyridine solution of [(2S)-7-nitro-2,3-dihydro-1,4-benzodioxin-2-yl]methanol (˜66.4 mmol) from Example 1H is immersed in an ice/brine bath to achieve an internal temperature of 0-1° C. p-toluenesulfonyl chloride (14.55 g, 76.3 mmol) is dissolved in pyridine (17 mL) and the resulting solution is added over 20 min. The mixture is stirred while allowing the bath to expire, and then for 18 h. Water (180 mL) is added at a continuous rate over 30 min. The suspension is stirred for 1 h, and then collected by vacuum filtration onto a medium porosity fritted funnel. The filter cake is washed with water (160 mL) and suction dried under nitrogen to give [(2R)-7-nitro-2,3-dihydro-1,4-benzodioxin-2-yl]methyl 4-methylbenzenesulfonate (19.68 g, 81% two steps) as a brown solid; 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).
