反应详情

61 mg of (±)-6-fluoro-8-amino-2,3-dihydrospiro[4H-1-benzopyran-4,5'-thiazolidine]-2',4'-dione were heated to 50° C. for 90 minutes in a mixture of 1.2 ml of glacial acetic acid and 1.2 ml of acetic acid anhydride and the resulting mixture was subsequently concentrated to dryness in vacuo. After boiling up briefly with active carbon in methanolic solution, the residue was crystallized from methanol and yielded (±)-6-fluoro-8-acetamido-2,3-dihydrospiro[4H-1-benzopyran-4,5'-thiazolidine]-2',4'-dione in the form of a light brownish material of melting point 278°-280° C.

1. concentrationthe resulting mixture was subsequently concentrated to dryness in vacuo
2. customthe residue was crystallized from methanol