The general procedure for the synthesis of 3,4,6-tri-octa-acetyl-ALPHA-D-glucopyranose 1,2-(methyl orthoacetate) from (2S,3R,4S,5S,6S)-2-hydroxy-6-(methoxycarbonyl)tetrahydro-2H-pyran-3,4,5-triethyl triacetate and trichloroacetonitrile was performed as follows: 2,3,4-triacetyl-α,β-pyran methyl gluconate (12.0 g, 36 mmol) and trichloroacetonitrile (18 mL, 180 mmol) were dissolved in anhydrous CH2Cl2 and stirred for 30 min. Subsequently, DBU (1.5 mL, 10 mmol) was slowly added dropwise, and the reaction mixture was gradually warmed up to room temperature and continuously stirred overnight. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure and the resulting residue was purified by fast column chromatography (eluent ratio 40:59:1 EtOAc-hexane-Et3N). The fraction containing the target product was collected and concentrated under reduced pressure to give a slurry, which was ground with ether. Further recrystallization with EtOAc-hexane (50:50) mixed solvent resulted in 8.5 g (65% yield) of off-white solid product. The melting point of the compound was 108-109 °C and literature reported values of 109-110 °C. Infrared spectroscopy (KBr) showed characteristic absorption peaks: v 3320 (N-H stretching vibration), 2958 (C-H stretching vibration), 1755 (C=O stretching vibration) cm-1. 1H NMR (CDCl3) data were as follows: δ 8.73 (s, 1H, NH), 6.64 (d, 1H, J=3.6 Hz, H-1), 5.63 (t, 1H, J =10Hz, H-3), 5.27 (t, 1H, J=10Hz, H-4), 5.16 (dd, 1H, J=3.6Hz, 10Hz, H-2), 4.49 (d, 1H, J=10Hz, H-5), 3.75 (s, 3H, CO2Me), 2.05 (s, 3H, OAc), 2.04 (s, 3H, OAc) , 2.02 (s, 3H, OAc). 13C NMR (CDCl3) data are as follows: δ 169.78 (CO), 169.72 (CO), 169.47 (CO), 167.14 (CO), 160.58 (CN), 92.64 (CH), 70.49 (CH), 69.47 (CH), 69.10 (CH). 68.96 (CH), 53.04 (CO2Me), 21.04,20.66,20.48,20.39 (3 × OAc and 1 × CCl3).
