Higher‐Order Cycloaddition Reactions for the Construction of Polycyclic Aromatic and Polycyclic Heteroaromatic Compounds.

Cycloadditions are an important class of reactions in materials science for the construction of polycyclic aromatic and polycyclic heteroaromatic compounds. Recently, cycloadditions have been expanded beyond the "classical" group of cycloadditions involving six π‐electrons, and it is now possible to control cycloadditions for an extended number of π‐electrons by applying organocatalysis. This novel field of cycloadditions–termed higher‐order cycloadditions–allows new synthetic methodologies to construct polycyclic carbo‐ and heteroaromatic compounds in two or three dimensions. This concept presents higher‐order cycloadditions as a method for accessing two‐ and three‐dimensional azulenes and cyclazines, as well as three dimensional indenes, as polycyclic aromatic and polycyclic heteroaromatic compounds. [ABSTRACT FROM AUTHOR]