Synthesis of 4‐Oxo‐3a,4,5,6‐tetrahydroimidazo[1,5‐b]isoxazole‐3‐carboxylic Acid Esters

Abstract

3‐Imidazoline 3‐oxides react regioselectively with 3‐phenylpropanoic acid alkyl esters to give the corresponding 2‐phenyl‐3a,4,5,6‐tetrahydroimidazo[1,5‐b]isoxazole‐3‐carboxylic acid alkyl esters. This adducts convert to imidazole and the corresponding alkyl 3‐oxo‐3‐phenylpropanoic acid esters when treated with alkoxides or heated under vacuum. Attempts to oxidise the carbon–carbon double bond using KMnO₄–FeSO₄ led to the formation of heretofore unknown 4‐oxo‐3a,4,5,6‐tetrahydroimidazo[1,5‐b]isoxazoles.

Keywords:

• Imidazole
• Heterocycles
• Adducts
• Nitrones

Acknowledgment

The financial support of Uludag University Research Fund is gratefully acknowledged (Projects 2001‐2 and 2000‐35).

Notes

^aA series of tetrahydroimidazo compounds were tested for their anticancer activity and found to be quite active at 10⁻⁵ molar concentrations.

^bThe spectra of alkyl 3‐oxo‐3‐phenylpropanoates were compared with the IR spectra of those obtained by Jons oxidation of the 3‐hydroxy‐3‐phenylpropanoates. The latter were prepared from the Reformatsky reaction of alkyl bromoacetates and benzaldehyde.