Fused chromeno-pyrano-pyrimidinediones: Multi-component green synthesis and electrochemical properties

An efficient solvent-free green multi-component reaction strategy for the synthesis of diversified fused chromeno-pyrano-pyrimidinediones (4) by the reaction of 4-hydroxy-1-benzopyran-2-one (1), benzaldehydes (2) and thiobarbituric acid (3) in the presence of thiamine hydrochloride at room temperature in a single step operation has been developed. Simple to perform, neat reaction conditions, water workup, short reaction times, high product yields, scalability, catalyst reusability, products free from column purification and excellent greenness of the process are the noteworthy features of this multi-component reaction approach. Hence, the established methodology meets the concept of "benign by design". Further, electrochemical properties of the synthesized compounds (4) have been studied by cyclic voltammetry. The HOMO/LUMO values of titled compounds (4) are obtained in the ranges of -5.72 to -5.37 eV/-2.57 to -2.21 eV that are comparable with the reported hole transporting materials.