Recent development on the [5+2] cycloadditions and their application in natural product synthesis.

The [5+2] cycloaddition is one kind of fascinating and powerful reaction to access seven-membered ring systems existing in complex natural products and pharmaceuticals. In this review, recent developments on the [5+2] cycloadditions and their application in the synthesis of complex natural products are discussed. A focus is given to the way in which the [5+2] cycloadditions have influenced the logical process of the synthesis. This article is organized by reaction types, aiming to provide a clear clue to the latest research trends.