New drug approvals for 2021: Synthesis and clinical applications.

50 New drugs including 36 chemical entities and 14 biologics were approved by the U.S. Food and Drug Administration during 2021. Among the marketed drugs, 31 new small molecule agents (29 small molecule drugs and 2 diagnostic agents) with privileged structures and novel clinical applications represent as promising leads for the development of new drugs with the similar indications and improved therapeutic efficacy. This review is mainly focused on the clinical applications and synthetic methods of 29 small molecule drugs newly approved by the FDA in 2021. We believed that insight into the synthetic approaches of drug molecules would provide creative and practical inspirations for the development of more efficient and practical synthetic technologies to meet with new drug discovery.