Molybdate sulfuric acid (MSA): an efficient solid acid catalyst for the synthesis of diversely functionalized fused imidazo[1,2-a]pyrimidines under solvent-free conditions

A one-pot multi-component, green, and highly efficient protocol has been developed for the synthesis of imidazo[1,2-a] pyrimidines annulated heterocyclic scaffolds (4a-4ab) using molybdate sulfuric acid (MSA) as an eco-friendly and reusable catalyst in good to excellent yields under solvent-free conditions that efficiently produced three new bonds (two C-N and one C-C) in a single operation. Other remarkable features of this environmentally benign protocol are a short reaction time, a wide range of functional group tolerance, use of an inexpensive heterogeneous catalyst, and high yield of products via a simple experimental and work-up procedure. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields. [GRAPHICS] .