Synthesis of imidazo[1,2-a]pyridine-chromones via Groebke-Blackburn-Bienayme reaction

The search for new environmentally friendly synthetic processes that reduce the use and generation of hazardous substances is the main interest of green chemistry. Currently, the main challenges for synthetic chemistry are the design, development, and implementation of more efficient methods. One strategy to achieve this is the use of highly efficient synthesis tools such as Isocyanide-Based Multicomponent Reactions (IMCRs).

IMCRs have recently attracted the interest of various researchers in organic synthesis due to their efficiency in forming several bonds in one reaction step. Reducing the number of steps is crucial for minimizing waste generated during the purification processes of synthesis intermediates, which significantly contributes to the development of environmentally friendly strategies. The synthesis of Imidazo[1,2-α]pyridines (IMPs), via IMCR presents several advantages over multistep and/or conventional syntheses.The Groebke-Blackburn-Bienaymé reaction (GBB) is useful for synthesizing imidazole analogs and is the method of choice for synthesizing IMPs. Multiple properties of IMPs have been reported; however, these reports often describe the synthesis of IMPs using a large number of reagents, high temperatures, long reaction times, and overall low yields. The GBB synthesis of IMPs using cheap and environmentally friendly catalysts, such as ammonium chloride, has been little reported. In the present work, we describe the synthesis of analogues of IMPs functionalizated with the chromone into the imidazole ring, which is widely documented in the design of materials with fluorescent properties.