2,4,6-Trimethylpyridine → 2-octadecyl-7-(2,3,4,6-tetra-O-acetyl beta-D-galactopyranosyloxy)-3H-phenoxazin-3-one

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Reaction Steps

A mixture of 7-hydroxy-2-octadecyl-3H-phenoxazine-3-one ("octadecylresorufin) (220 mg, 0.47 mmole), powdered, activated 4Å molecular sieves (0.5 g), sym-collidine (125 μL, 0.95 mmole), and silver carbonate (155 mg, 0.56 mmole) in dry dichloromethane (20 mL) is allowed to stir at room temperature, under an atmosphere of dry nitrogen gas, in the dark for 1 hour. To this mixture is added 1-bromo-2,3,4,6-tetra-O-acetyl-α-D-galactopyranoside (389 mg, 0.95 mmole), slowly with stirring, and the resulting heterogenous solution allowed to stir as above for 72 hours. After this time the reaction mixture is filtered through a pad of diatomaceous earth. The precipitate is washed with chloroform (5×10 mL) and the combined organic filtrates are extracted with 1M aqueous HCl (1×75 mL), saturated aqueous sodium bicarbonate solution (1×75 mL), 1M sodium thiosulfate (1×75 mL), and water (1×75 mL). The organic layer is dried over anhydrous sodium sulfate, filtered, evaporated under reduced pressure, and dried in vacuo to an orange-brown powder (440 mg). An analytical sample of the title compound can be isolated by preparative t.l.c. (20×20 cm SiO2 plate; eluent=9:1 chloroform:ethylacetate) with the bright-orange product eluting at the highest Rf (0.44), (50 mg from 200 mg applied).

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