Trifluoroacetic acid → 6-Ethyl-4-hydroxy-2H-pyran-2-one

Participants

Reaction Steps

A solution of 25% (v/v) trifluoroacetic acid (TFA) in trifluoroacetic anhydride (TFAA, 1117 mL) was placed in a 2 liter round bottom flask and cooled in an ice bath for 40 minutes. Crude compound U was loaded into an addition funnel and slowly added to the stirred mixture over 2 hours. The reaction was allowed to warm up to room temperature overnight. The TFA/TFAA solution was removed by rotary evaporation. Residual TFA could be removed azeotropically with toluene. The residue was then purified by silica gel chromatography eluting with a gradient of 10-50% ethyl acetate in dichloromethane. The appropriate fractions were collected and concentrated by rotary evaporation to yield compound V (63.15 g, 45%) as a yellow solid. 1H NMR CDCl3 δ: 11.08 (bs, 1H), 6.00 (s, 1H), 5.59 (s, 1H), 2.52 (q, 2H, J=8.0 Hz), 1.22 (t, 3H, J=8.0 Hz). ESMS m/z: 141.0 [M+H+].

Provenance & Evidence