[2 + 2]-Cycloaddition-derived cyclobutane natural products: structural diversity, sources, bioactivities, and biomimetic syntheses

Covering: up to the end of 2021[2 + 2]-Type cyclobutane natural products are biosynthetically derived from intermolecular [2 + 2] cycloaddition or intramolecular [2 + 2] cycloaddition reactions. Due to their distinctive cyclobutane architectures, diverse biological effects, interesting formation processes, and synthetic challenges, these compounds have attracted considerable attention from scientists. In this article, the progress in research published through the end of 2021 on [2 + 2]-cycloaddition-derived cyclobutane natural products, including their structural diversity, sources, bioactivities and biomimetic syntheses, was reviewed; in addition, structural revisions were included. Emphasis was placed on the structural diversity of these interesting molecules and their biomimetic syntheses, which will provide inspiration for the total synthesis or biomimetic synthesis of more [2 + 2]-type cyclobutane natural products and further phytochemistry investigations.