A study of the Mannich reaction in the isoxazole series

Abstract

3 : 5-Dimethyl-4-nitro isoxazole and 3-aryl-2-isoxazolin-5-ones were found to undergo the Mannich reaction readily at room temperature, affording in most cases unstable products. While the 5-methyl group was the active site with the former, the latter underwent reaction exclusively at the 4-position. The structures of the products were confirmed by spectral data. The Mannich bases from the isoxazolones were found to exist in three tautomeric modifications, contrary to earlier observations. Most of the products exhibited a high degree of antibacterial activity.