Recent Developments in [8 + 2] Types Cycloadditions

Higher-order cycloadditions present significant potential as a convenient approach for creating higher-order ring systems, having immense potential in organic and natural product chemistry. The (8 + 2) cycloaddition reaction is a versatile tool in organic chemistry, enabling the efficient synthesis of complex cyclic structures with applications in material science and pharmaceuticals. This review summarizes developments in (8 + 2) cycloaddition since 2008, highlighting the use of tropones, tropothiones, heptafulvenes, and aza-heptafulvenes with olefins and benzyne as 2π-components. It emphasizes the need for exploring new 8π-components with hetero-dienophile-based 2π-components to form diverse higher-order heterocycles and further investigates intramolecular versions of the (8 + 2) cycloaddition. This article aims to review the recent progress made in the field of (8 + 2) cycloaddition reactions in the realm of organic synthesis since 2008.