Stereoselective transition metal-catalysed higher-order carbocyclisation reactions.

Transition metal-catalysed higher-order carbocyclisation reactions represent an important class of reactions due to their ability to construct complex polycyclic systems in a highly selective and atom-economical fashion. A key and striking feature with these transformations is the dichotomy in reactivity that a substrate displays with different transition metal complexes, which is akin to the manner enzymes direct terpene biosynthesis. This tutorial review details the historical development of higher-order carbocyclisation reactions, specifically the variants of [m+2+2] that involve carbon-based pi-systems, where m = 2, 3 and 4, in the context of critical developments with various transition metal complexes.