Cyclopentanecarboxylic acid, 2-oxo-, methyl ester → methyl 2-(((trifluoromethyl)sulfonyl)oxy)cyclopent-1-enecarboxylate

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Reaction Steps

Trifluoromethanesulfonic anhydride (1.5 mL, 8.9 mmol) was slowly added to a solution of methyl 2-oxocyclopentanecarboxylate (1.0 mL, 8.1 mmol) and N,N-diisopropylethylamine (2.2 mL, 13.0 mmol) in methylene chloride (30 mL) under a nitrogen atmosphere at room temperature. The reaction was stirred for 72 h, and then partitioned between methylene chloride and water. The organic layer was washed with 1 N HCl, aqueous NaHCO3, and brine; dried over magnesium sulfate; and concentrated to give an oil. The product was purified by FCC on silica gel eluting ethyl ether:hexane (5:95) to give 2-trifluoromethanesulfonyloxy-cyclopent-1-enecarboxylic acid methyl ester (1.62 g, 73%) as a yellow oil.

Provenance & Evidence