One-pot metal-free access to uracil-benzofuran bis-heterocycles: synthesis and DFT insights.

The one-pot synthesis of uracil-benzofuran bis-heterocycles is reported via the base-catalyzed reaction of ortho-hydroxyphenyl propargylamines with 6-amino-1,3-dimethyluracil in good to excellent yields. This efficient protocol proceeds under mild conditions without the need for transition-metal catalysts or an inert atmosphere, offering a sustainable and practical synthetic route. The reaction mechanism involves a sequence of 1,4-conjugate addition, alkyne-allene isomerization, and 5-exo-dig cyclization processes. Furthermore, to validate the experimental results and provide deeper insight into the chemical behavior, the electronic structures and the relative energies of the products were investigated using Density Functional Theory (DFT) at the B3LYP/6-311++G** level. The calculated results showed excellent agreement with the experimental observations.