4-O-benzoyl-3,5-di-O-benzyl-2-deoxy-L-threo-pentose dibenzyl dithioacetal → 3,5-di-O-benzyl-2-deoxy-L-threo-pentose dibenzyl dithioacetal

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-O-benzoyl-3,5-di-O-benzyl-2-deoxy-L-threo-pentose dibenzyl dithioacetal (88.8 g, 137 mmol) in dichloromethane (500 ml) was added a solution of sodium methoxide (11.1 g, 206 mmol) in methanol (205 ml) dropwise, with stirring, at 0° C. The reaction mixture was then allowed to warm to room temperature over a period of 3 hours. At the end of this time TLC (hexane-ethyl acetate [4:1]) revealed complete conversion to a slower moving component (Rf 0.31). The mixture was then poured into a 5% solution of NaH2PO4 and extracted with dichloromethane. The dichloromethane extracts were then washed with a 5% solution of sodium hydrogen carbonate and water, dried (magnesium sulphate) and evaporated. The crude title product was applied to a silica gel column eluted with hexane-ethyl acetate (4:1). Combination of the appropriate fractions gave the title product as a clear colourless syrup.

Provenance & Evidence