Rcf. Jones et al., A 1,3-DIPOLAR CYCLOADDITION ROUTE TO 3-ACYL-4-HYDROXY-PYRIDIN-2-ONES AND 3-ACYL-4-HYDROXY-PYRAN-2-ONES, Synlett, (2), 1995, pp. 149-150
The 1,3-dipolar cycloaddition of nitrile oxides to enamines formed fro
m 5-benzyloxycarbonylamino-3-ketoesters affords 4-carboxyisoxazoles th
at are converted via isoxazolo[4,5-c] pyridin-4-ones into 3-acetyl-4-h
ydroxypyridin-2-ones.