Ethylenediamine diacetate- and 2-aminopyridine-catalyzed metal-free synthesis of pyran-annulated heterocyclic systems via a domino Knoevenagel–Michael cyclocondensation reaction: an environmentally responsible approach

This study created safe and easy methods to make 2-amino-4H-chromene scaffolds and pyrano[2,3-d]pyrimidine scaffolds that are safe for the environment. The process uses a special chemical reaction called a domino Knoevenagel-Michael cyclocondensation reaction. Ethylenediamine diacetate (EDDA) is a cost-effective and inexpensive catalyst for the preparation of 2-amino-4H-chromene scaffolds and pyrano[2,3-d]pyrimidine scaffolds. The reaction happens at room temperature under solvent-free conditions. This process uses ideas from green chemistry. This study also presents a convenient method to create 2-amino-4H-chromene scaffolds. The strategy uses 2-aminopyridine, which is a cheap and recoverable catalyst, to help accelerate a reaction while refluxing in ethanol. The current method has many great benefits that support eco-friendly and sustainable chemistry. The 2-aminopyridine was stable enough to be reused four times in a row without losing its performance. The reactions finish faster and produce good-to-high results. These eco-friendly methods use safe chemicals. There is no need to use column chromatography to separate the mixture. These ways are cheap and simple to do. They put all the steps together in one pot, which makes them easier to use and better for the environment, which helps them fulfill industry demands.