Asymmetric synthesis of enantiopure fluorinated cyclopropyl carbohydrate analogues

• Novel fluorinated cyclopropanes have been synthesized by cycloaddition.
• The observed π-facial selectivity is determined by the configuration at C-5.
• The exo-selectivity was complete in all the cases.

A simple and convenient method for the synthesis of cyclopropanes substituted with carbohydrate analogues is described. The addition of trifluoromethyl diazo compounds to 5-(R)-hydroxypyridazin-3-one derivative of d-(+)-galactose proceeded in almost quantitative yields and high syn-selectivity. The observed π-facial selectivity is determined by the configuration at C-5. The exo-selectivity was complete in all the cases. Steric interactions and electronic factors seem to be the main ones responsible for the observed exo selectivity and π-facial selectivity of reactions with trifluoromethyl diazo compounds.

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