反应详情

To a solution of (triphenylphosphoranylidene)-acetic acid ethyl ester (15 g) in anhydrous tetrahydrofuran (100 ml) was added isothiocyanato-cyclopropane (4.4 g) and the mixture was refluxed under a nitrogen atmosphere for 20 hr. After allowing to cool to ambient temperature the reaction mixture was cooled to −78° C. and then a solution of 3-bromo-2-oxo-butanoic acid methyl ester (8.7 g) in anhydrous tetrahydrofuran (10 ml) was added. The resulting mixture was allowed to warm to ambient temperature and then refluxed for 20 hr., then ambient temperature for 2 days. The reaction was poured into water and extracted with diethyl ether. The collected organic extract was dried over magnesium sulfate, filtered and evaporated under reduced pressure. The residue was purified by column chromatography over silica, eluting with i-hexane/ethyl acetate (95:5) then triturated with i-hexane/diethyl ether (8:2) to give the sub-title compound as a solid (7.5 g).

1. temperaturethe mixture was refluxed under a nitrogen atmosphere for 20 hr
2. temperaturewas cooled to −78° C.
3. temperatureto warm to ambient temperature
4. temperaturerefluxed for 20 hr
5. extractionextracted with diethyl ether
6. extractionThe collected organic extract
7. dry with materialwas dried over magnesium sulfate
8. filtrationfiltered
9. customevaporated under reduced pressure
10. customThe residue was purified by column chromatography over silica
11. washeluting with i-hexane/ethyl acetate (95:5)
12. customthen triturated with i-hexane/diethyl ether (8:2)