Synthesis of Pyrido[2,3-d]pyrimidine Carbodithioates Using Deep Eutectic Solvent as Recyclable Media and Three-Component Reaction

A facile, three-component one-pot synthesis of a combinatorial library of pyrido[2,3- d]pyrimidines by condensation of easily accessible β-oxodithioesters with 1,3-dimethyl-6-amino uracil and aldehydes under deep eutectic solvent medium is achieved. The yields of the desired products are good to excellent, irrespective of the steric and electronic nature of the substituents. The advantages of operational simplicity, economic viability, generality, and atom economy, together with its ecologically benign nature, make this protocol a very efficient alternative to literature methods. These compounds contain reactive functionalities for further ring annulation reactions and thus can be utilized as building blocks for complex natural products.