Acetonyltriphenylphosphonium bromide → methyl (1R,trans) 2,2-dimethyl-3-[(E)-3-oxo-1-butenyl]-cyclopropane-1-carboxylate

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Reaction Steps

A mixture of 5 g of methyl (1R,trans) 2,2-dimethyl-3-formyl-cyclopropane-1-carboxylate, 11.3 g of 2-oxopropyl-triphenylphosphonium bromide and 50 ml of dichloroethane was refluxed for 2 hours and the temperature was allowed to return to room temperature. The mixture was evaporated to dryness under reduced pressure and the 19 g of oil residue were empasted with ether and filtered. The filtrate was evaporated to dryness and the 5 g of oil residue were chromatographed over silica gel. Elution with a 7-3 cyclohexane-ethyl acetate mixture yielded 4.46 g of methyl (1R,trans) 2,2-dimethyl-3-[(E)-3-oxo-1-butenyl]-cyclopropane-1-carboxylate with a specific rotation of [α]D20 =+108°±2.5° (c=0.6% in benzene).

Provenance & Evidence