Trifluoroacetic acid → 6-Ethyl-4-hydroxy-2H-pyran-2-one
Reaction equation
FC(F)(F)C(O)=O.C([O:12][C:13](=[O:22])[CH2:14][C:15](=[O:21])[CH2:16][C:17](=O)[CH2:18][CH3:19])(C)(C)C>FC(F)(F)C(OC(=O)C(F)(F)F)=O>[CH2:18]([C:17]1[O:16][C:15](=[O:21])[CH:14]=[C:13]([OH:12])[CH:22]=1)[CH3:19]Participants
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
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+].
Workup
- temperaturecooled in an ice bath for 40 minutes
- additionslowly added to the stirred mixture over 2 hours
- customThe TFA/TFAA solution was removed by rotary evaporation
- customResidual TFA could be removed azeotropically with toluene
- customThe residue was then purified by silica gel chromatography
- washeluting with a gradient of 10-50% ethyl acetate in dichloromethane
- customThe appropriate fractions were collected
- concentrationconcentrated by rotary evaporation
Sources & evidence
- ORD record
- ord-dc8a88671eb74484a897a8258902650d
- Source dataset
- uspto-grants-2011_02
- Patent number
- US07879846B2
Reaction notes
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