The Game of Electrons: Organocatalytic Higher-Order Cycloadditions Involving Fulvene- and Tropone-Derived Systems.

The great progress that took place in the field of higher-order cycloadditions involving fulvene- and tropone-derived systems in the last few years is astonishing. By application of organocatalytic activation modes, new higher-order reactivities have been identified and described in the literature. These approaches take advantage of the high reliability of organocatalysis, at the same time expanding its potential and paving new directions for its further evolution. In this Minireview, the progress in the field of organocatalytic higher-order cycloadditions involving fulvene- and tropone-derived systems is summarized and insights into mechanistic aspects of the developed reactivities are provided. Furthermore, the discussion on the nomenclatural issues related to cycloaddition reactions has been conducted and solutions to clarify the picture proposed.