1-O-Methyl-3,5-bis-O-[(2,4-dichlorophenyl)methyl]-alpha-D-erthro-pentofuranoside-2-ulose → 3,5-Bis-o-(2,4-dichlorobenzyl)-2-c-vinyl-1-o-methyl-alpha-d-ribofuranose

Participants

Reaction Conditions

Reaction Steps

Cerium chloride heptahydrate (50 g, 134.2 mmol) was finely crushed in a pre-heated mortar and transferred to a round-bottom flask equipped with a mechanical stirrer. The flask was heated under high vacuum overnight at 160° C. The vacuum was released under argon and the flask was cooled to room temperature. Anhydrous THF (300 mL) was cannulated into the flask. The resulting suspension was stirred at room temperature for 4 h and then cooled to −78° C. Vinylmagnesium bromide (1M in THF, 120 mL, 120 mmol) was added and stirring continued at −78° C. for 2 h. To this suspension was added a solution of 3,5-bis-O-(2,4-dichlorophenylmethyl)-1-O-methyl-α-D-erythro-pentofuranose-2-ulose (14 g, 30 mmol) [from Example 2, Step B] in anhydrous THF (100 mL), dropwise with constant stirring. The reaction was stirred at −78° C. for 4 h. The reaction was quenched with saturated ammonium chloride solution and allowed to come to room temperature. The mixture was filtered through a celite pad and the residue washed with Et2O (2×500 mL). The organic layer was separated and the aqueous layer extracted with Et2O (2×200 mL). The combined organic layers were dried over anhydrous Na2SO4 and concentrated to a viscous yellow oil. The oil was purified by flash chromatography (SiO2, 10% EtOAc in hexanes). The title compound (6.7 g, 13.2 mmol) was obtained as a pale yellow oil.

Provenance & Evidence