1N HCl (5 mL) was added dropwised into the solution of (1R,2R,3S,4R,5R,6S)-4-(4-chloro-3-(4-ethylbenzyl)phenyl)-6-(hydroxymethyl)cyclohexane-1,2,3,5-tetraol (5, R=Et, 1 g, 2.46 mmol) in MeOH (80 mL) and acetone (20 mL), and stirred overnight, then the mixture was evaporated to dryness. The residue was purified by preparative HPLC to give the target compound (864 mg, white solid, yield of 75.3%). 1H-NMR (400 MHz, CD3COCD3): δ 7.26-7.29 (2H, m), 7.10-7.16 (5H, m), 3.74-4.21 (6H, m), 3.46-3.51 (1H, m), 3.35-3.37 (1H, m), 2.56-2.66 (3H, m), 1.72-1.75 (1H, m), 1.28 (3H, s), 1.18 (3H, t, J=7.6 Hz), 1.13 (3H, s); MS (ESI+): 447 [M+H]+, 488 [M+H+CH3CN]+, 910 [2M+NH4]+, 491 [M+HCOO]−, 937 [2M+HCOO]−.
