Reaction Steps
o-Nitrophenyl β-D-galactopyranoside 27 (903 mg, 3.0 mmol) was added to a mixture of trimethyl phosphate (7.5 mL, 64.8 mmol), water (0.05 mL, 3.0 mmol) and phosphorous oxychloride (0.84 mL, 9.0 mmol) at 0° C. The reaction mixture was stirred and after 2 h a change was observed from a white, cloudy suspension to a clear, yellow solution. After 3 h, t.1.c. (ethyl acetate:methanol, 4:1) indicated the formation of one product (Rf 0.2) and the absence of any starting material (Rf 0.3) Crushed ice (20 mL) was added and the reaction mixture neutralised with ammonia (5 mL of a 33% aqueous solution). The white crystalline solid thus formed was separated from the clear yellow solution by filtration, the filtrate concentrated in vacuo and co-evaporated with water (6×10 mL) to afford a white, crystalline solid. The residue was purified by flash column chromatography as follows; charcoal (10 g) and celite (10 g) were mixed together with hydrochloric acid (10 mL of a 1 M aqueous solution) and packed into a column. The white solid was dissolved in water (5 mL) and loaded onto the column. The column was eluted with water. Aliquots (1 mL) of each fraction were removed and tested for the presence of chloride ions by observing turbidity on addition of silver nitrate (1 mL of a 1 M aqueous solution). After elution with 1.75 L of water the presence of chloride ions were no longer detected. Further elution (water:pyridine, 2:1) yielded o-nitrophenyl β-D-galactopyranoside 6-phosphate 17 (701 mg, 62%) as a pale, yellow crystalline solid; m.p. 181.0-183.1° C. (ethanol/ether) [Lit. 180° C. (ethanol/ether)];27 [α]D25-31.1 (c, 0.2 in H2O) [Lit. [α]D20-40 (c, 2 in H2O)];27 νmax (KBr) 3400 br, OH) 1527, 1355 (sh, C—NO2), 1250 (sh, P═O)cm−1, δH (400 MHz, D2O) 1.17-1.29 (2H, m, 2 x CHNH3), 1.52-1.57 (2H, d, J=12.6 Hz, 2 x CHCHCHCNH3), 1.68-1.73 (4H, m, 4 x CHCHCNH3), 1.87 (4H, br, 4 x CHCNH3), 3.04 (2H, br, 2 x NH), 3.65-3.70 (2H, m, H-6, H-6′), 3.74-3.86 (3H, m, H-3, H-4, H-5), 3.91-3.92 (1H, m, H-1), 7.13-7.18 (1H, m, CHCHCNO2), 7.33-7.42 (1H, m, CHCHCHCHCNO2), 7.56-7.61 (H, m, CHCHCHCNO2), 7.83-7.86 (1H, m, CHCNO2).
