Fickle Reactivity of Allenes in Transition‐Metal‐Catalyzed C−H Functionalizations

Transition‐metal‐catalyzed C−H functionalizations with allenes lead to unique selectivity challenges due to the presence of two adjacent carbon–carbon double bonds, which enables a series of atom‐ and step‐economical alkenylation, allenylation, allylation, dienylation, and annulation reactions of different substrates. This Focus Review highlights the recent remarkable advancements made in transition‐metal‐catalyzed C−H functionalization with allenes. The magic of allenes: This Focus Review highlights the variable reactivity of allenes for alkenylation, allenylation, allylation and annulation reactions by transition‐metal‐catalyzed C−H activation.