Dimethyl Sulfide → trans-6-pentafluoroethyl-2,2-bisfluoromethyl-3,4-dihydro-4-(3-oxo-cyclopent-1-enyloxy)-2H-1-benzopyran-3-ol

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Reaction Conditions

Reaction Steps

In 40 ml of tetrahydrofuran was dissolved 0.36 g of cyclopentan-1,3-dione and 0.13 g of sodium hydride (60%) was added thereto under nitrogen stream with cooling at -20° C. After the mixture was stirred at room temperature for 15 minutes, 0.72 g of a complex of copper (I) bromide and dimethyl sulfide was added. To the reaction mixture was added 0.92 g of 3,4-epoxy-6-pentafluoroethyl-2,2-bisfluoromethyl-3,4-dihydro-2H-1-benzopyran dissolved in 10 ml of tetrahydrofuran. The mixture was stirred for 6 days. To the mixture were added water and a small amount of concentrated sulfuric acid. The mixture was extracted with methylene chloride and the organic layer was washed with water and dried. The solvent was distilled off and the resultant residue was purified using silica gel column chromatography (developing solution, MeOH:CH2Cl2 =1:99) and another silica gel column chromatography (developing solution, AcOEt:hexane=1:1) to obtain 0.04 g of trans-6-pentafluoroethyl-2,2-bisfluoromethyl-3,4-dihydro-4-(3-oxo-cyclopent-1-enyloxy)-2H-1-benzopyran-3-ol represented by the following formula having a melting point of 165-167° C.

Provenance & Evidence