Facile, capable, atom-economical one-pot multicomponent strategy for the direct regioselective synthesis of novel isoxazolo[5,4-d]pyrimidines

Facile and efficient NaOH-promoted one-pot regioselective synthesis of 5,7-dimethyl-3-(arylamino)isoxazolo[5,4-d]pyrimidine-4,6(5H,7H)-diones and 5,7-dimethyl-3-(arylamino)-6-thioxo-6,7-dihydroisoxazolo[5,4-d]pyrimidin-4(5H)-ones as pharmaceutically interesting compounds has been developed based on a three-component reaction between aryl isothiocyanates, N,N-dimethylbarbituric acid or N,N-dimethyl-2-thiobarbituric acid, and hydroxylamine hydrochloride in N,N-dimethylformamide (DMF) at room temperature. This new protocol has advantages such as simple operation, regioselectivity, metal-free operation, high atom economy, moderate to high yield, easy work-up procedure, and applicability on the gram scale.