Synthesis
Synthesis of Compound VIII: Compound VII (2.2 mmol) was dissolved in ethyl acetate (54 mL) and triethylamine (Et3N) was added. Hydrogen trifluoride (3HF, 2.08 mL, 0.013 mmol) was added slowly under stirring. The reaction mixture was heated to 60°C with continuous stirring for 3 hours, followed by warming to 70°C with continued stirring for 1.5 hours. Upon completion of the reaction, the reaction was quenched by the addition of ice brine (10 mL) and extracted with dichloromethane. The organic phases were combined and washed sequentially with brine, water and saturated sodium bicarbonate solution and dried over anhydrous sodium sulfate for 4 hours. The solvent was removed by concentration under reduced pressure to give a dark yellow syrupy crude product. Purification by silica gel column chromatography (5 cm × 5 cm, eluted with dichloromethane) gave a light yellow syrupy product in 86.8% yield. Finally, the crude product was recrystallized in 95% ethanol to give the white crystalline compound VIII in 66.4% yield.1H NMR (CDCl3) δ ppm: 7.31-8.10 (m, 15H, OBz), 6.71 (d, J = 9.0 Hz, 1H, H-1), 5.68 (dd, J = 19.44 Hz, 1H, H-3). 5.32 (d, J = 48.2 Hz, 1H, H-2), 4.65-4.77 (m, 3H, H-4, H-5). Melting point: 80-82°C.
References
[1] Patent: EP2177527, 2010, A1. Location in patent: Page/Page column 11-12
[2] Journal of Labelled Compounds and Radiopharmaceuticals, 1999, vol. 42, # SUPPL. 1, p. S638-S640
[3] Tetrahedron Letters, 1996, vol. 37, # 1, p. 17 - 20
