Total Synthesis and Biological Activities of Polyhydroxy Flavonols: A Review

Flavonols are an important class of flavonoids widely distributed across various plant species. They have garnered significant attention from synthetic chemists due to their extensive biological activities and medicinal value. This review provides a systematic overview of five classical synthetic methods, including the Auwers reaction, the Allan–Robinson reaction, the Baker–Venkataraman rearrangement, the Algar–Flynn–Oyamada (AFO) reaction, and DMDO-mediated oxidation. Each methodology is comprehensively discussed in terms of its advantages, limitations, and potential optimization strategies. Additionally, the biological activities, including antioxidant, anticancer, anti-inflammatory, and antiviral properties, are summarized and discussed in the context of structure–activity relationships (SARs).