Grindstone chemistry: A "green" approach for the synthesis and derivatization of heterocycles

The famous quote by ancient great philosopher Aristotle, "No Coopora nisi Fluida" means "No reaction occurs in the absence of solvent." Chemistry till the last century was developed based on this philosophy. In the current century, with the growing environmental concerns and global warming, it has become imperative to minimize the usage of hazardous chemicals and solvents. Over a few decades, the application of mechanical energy for reactions, called "mechanochemistry," has emerged as a solvent-less and alternative technique for chemical transformations. The simple and ancient tool for "mechanochemistry," a pair of mortar and pestle, also called "grindstone chemistry," is revitalized in recent years for a myriad of reactions from simple two-component condensation reactions to multicomponent reactions even to the synthesis of materials. Many of these reactions by grinding in a mortar-pestle led to the construction of various heterocycles. The method has benevolent characteristics such as clean and safe reaction profile, high atom economy, time-efficiency and over a period of time, it proved as a viable alternative to traditional solution-phase reactions. While the main focus of this review article is to cover the literature available on the use of mortar-pestle for the construction and derivatization of heterocycles, a brief overview of "grindstone chemistry" is included to give readers an out-and-out idea on its potential as a sustainable technology for the future.(c) 2022 Elsevier Ltd. All rights reserved.