Greening of Monocyclic N- and O‑Azole Synthesis through Sonochemistry

Sonochemistry is a fascinating branch of chemistry that applies sound waves in the ultrasonic frequency range to facilitate chemical processes. Although this technique is powerful, it remains underutilized in synthetic chemistry. By leveraging mechanisms of acoustic cavitation, sonochemistry initiates and enhances reactions, offering advantages such as cost-effectiveness, environmental sustainability, and improved reaction efficiency. Significantly, product yields in ring-closing reactions can be enhanced through sonochemistry. In certain cases, sonochemistry may also lead to altered product distributions. In this narrative review, we delve into the realm of N- and O-azoles, noting that the existing literature on sonochemistry as a synthetic method constitutes only about a tenth of all reports in this area. However, it is noteworthy that nearly all studies indicate improved outcomes when employing sonochemistry relative to traditional methods. As a green and sustainable synthetic approach, sonochemistry plays a crucial role in the synthesis of important heterocycles, many of which have significant pharmaceutical applications. This review covers synthetic reports including reaction conditions, solvents, catalysts, and reagents, spanning the past three decades, with an emphasis on contributions from 2020 through early 2025.