The reaction of thiocarbamoylcyanoacetates with hydroxylamine in ethanol under reflux conditions has provided a convenient method for the synthesis of 5-aminoisoxazoles.Isoxazoles play an important role in biochemistry, organic chemistry, and bioorganic chemistry. The biological activity of substituted isoxazoles [1] has made them a focus of medicinal chemistry over the years. Isoxazoles are potent, selective agonists of human cloned dopamine D4 receptors [2] and exhibit GABA A antagonistic [3], analgesic [3], anti-inflammatory [4], ulcerogenic [4], antifungal [5], antimicrobial [5], COX-2 inhibitory [6, 7], antinociceptive [8], and anticancer [9] activities. Many synthetic methods have been employed in the synthesis of isoxazoles [10], including the reactions of hydroxylamine with 1,3-dicarbonyl compounds [11], α,β-unsaturated carbonyl compounds [12], and α,β-unsaturated nitriles [13]. The reaction of oxime-derived dianion and ester [14] or amide [15, 16] also provides isoxazoles. [3+2] Cycloaddition reactions between alkynes and nitrile oxides have been also developed [17, 18]. However, these methods often require strong bases, strong mineral acids, and high temperatures, or provide poor regioselectivity. We have reported that the reaction of o-, m-, and p-substituted diethyl phenylthiocarbamoylmalonates with hydroxylamine under reflux conditions gave o-, m-, and p-substituted 3-phenylaminoisoxazol-5(2H)-ones [19-21]. CH NH S X CO 2 Et CO 2 Et O N H N H EtO 2 C O X C NH 2 OH EtOH X = H, 2-Me, 2-MeO, 3-Br, 4-Br, 3-Me, 4-Me, 4-CO 2 Et, 4-NO 2 __________________________________________________________________________________________