反应详情

A mixture of 4.2 g of (1R,trans) 2,2-dimethyl-3-[(E) (dihydro-2-oxo-3-(2H)-furanylidene)-methyl]-cyclopropane-1-carboxylic acid, 3.5 g of methyl N,N'-diisopropyl-carbamimidate and about 20 ml of ethyl acetate was refluxed for 2 hours and was cooled and evaporated to dryness. The residue was chromatographed over silica gel and was eluted with a 6-4 cyclohexane-ethyl acetate mixture to obtain 2.5 g of methyl (1R,trans) 2,2-dimethyl-3-[(E) (dihydro-2-oxo-3-(2H)-furanylidene)-methyl]-cyclopropane-1-carboxylate with a specific rotation of [α]D20 =+65°±2.5° (c=0.6% in ethanol).

1. temperaturewas refluxed for 2 hours
2. temperaturewas cooled
3. customevaporated to dryness
4. customThe residue was chromatographed over silica gel
5. washwas eluted with a 6-4 cyclohexane-ethyl acetate mixture