Behavior of 5-amino-3-methylisoxazole in multicomponent heterocyclizations with carbonyl compounds under thermal heating and non-classical conditions

Abstract

Three-component heterocyclizations of 5-amino-3-methylisoxazole, cyclohexanedione derivatives, and aromatic aldehydes, including salicylic aldehydes, are studied under conventional thermal heating, microwave irradiation and ultrasonication. A dependence of the direction of the reaction on the structure of the aldehyde and the reaction conditions was found, which allowed selective synthesis of 6,7,8,9-tetrahydroisoxazolo[5,4-b]quinolin-5(4H)-ones and 2,3,4,9-tetrahydro-1H-xanthen-1-ones. Key stages of the reaction mechanisms are discussed. © ARKAT-USA, Inc.