Novel catalyst-free one-pot five-component synthesis of a series of new pyrazolo-pyrido-pyrimidine-diones in water under ultrasonication-Supporting information

A novel catalyst-free route was utilized for the first time to achieve a synthesis of fourteen new 3-methyl-1,4,8,9-tetrahydro-5H-pyrazolo[4,3:5,6]pyrido[2,3-d]pyrimidine-5,7(6H)-diones via a one-pot five-component reaction of substituted aromatic/hetero aromatic aldehydes, barbituric acid, ethyl acetoacetate, hydrazine hydrate and ammonium acetate in water under ultrasonication. The reaction conversion took place between 15 and 18 min, with the yield ranging from 85% to 98%; and it was found that five compounds gave 90%. The methodology is expeditious and furnishes varied advantages like shorter reaction time, energy efficiency, eco-sustainability and works under mild condition.