Acetic Anhydride → Acetoacetic Acid

Reaction equation

[C:1]([O:4][C:5](=[O:7])[CH3:6])(=[O:3])[CH3:2].C[C@H]1[C@@H](C(C)C)OC(=O)C2N(CCC=2)C(=O)C2=COC(=N2)CC(=O)C[C@H](O)C=C(C)C=CCN[C:12](=[O:13])[CH:11]=C1>N1C=CC=CC=1>[CH3:2][C:1]([O-:4])=[O:3].[CH3:11][C:12]([CH2:6][C:5]([OH:4])=[O:7])=[O:13]

Participants

Procedure

Acetic anhydride (45 ml) was added to a stirring solution of Virginiamycin M1 (6.5 g) in anhydrous pyridine (45 ml) at room temperature. After 30 minutes, ice-cold methanol (85 ml) was added in portions. Stirring was continued for 20 more minutes followed by flash evaporation to dryness at room temperature. The residue was partitioned between dichloromethane (3×300 ml) and saturated NaCl (aq, 300 ml). The organic layers were pooled, dried over anhydrous Na2SO4, flash evaporated to dryness (dry weight=8.1 g) and purified over E. Merck silica gel 60 column in hexane/acetone mixtures to give 1.0 g of the monoacetate and 1.58 g of the diacetate.