Rcf. Jones et al., A CYCLOADDITION APPROACH TO 3-ACYLTETRAMIC AND 3-ACYLTETRONIC ACIDS, Journal of the Chemical Society. Perkin transactions. I, (18), 1994, pp. 2513-2515
1,3-Dipolar cycloaddition of nitrile oxides to enamines formed from pr
otected-gamma-amino- or gamma-hydroxy-beta-keto esters affords isoxazo
lecarboxylic esters that can be converted into 3-acyltetramic acids vi
a dihydropyrroloisoxazol-4-ones, or into 3-acyltetronic acids.