Steglich’s Base Catalyzed Three-Component Synthesis of Isoxazol-5-Ones
Zeinab Faramarzi, Hamzeh Kiyani
Abstract
4-(Dimethylamino)pyridine (DMAP) has been used as an efficient Brønsted organo-base catalyst for the one-pot, three-component cyclization of various aldehydes, β-keto esters, and hydroxylamine hydrochloride. In this organocatalyzed reaction, 3,4-disubstituted isoxazole-5(4H)-ones were efficiently formed in high yields and relatively shorter reaction times. Using 8 mol% of DMAP, a mixture of water–ethanol solvent system, and 80 °C gave the best results. The three-component heterocyclization using arylaldehydes containing electron releasing groups is well performed and heterocyclic products were obtained in good to high isolated yields. Aldehydes with electron withdrawing groups did not lead to the formation of products. This method has many advantages such as broad substituent scope, mild and eco‐friendly conditions, step and atom economy, commercially available, and inexpensive organo-basic catalyst.