Carbon–carbon (C–C) and carbon–heteroatom (C–X) bond formation remain the cornerstones of organic synthesis. However, accessing unexplored chemical space requires reaction modes that transcend established catalytic paradigms. In this context, π -systems offer a versatile platform for bond construction, particularly through cycloaddition and electrocyclization processes that can rapidly build molecular complexity.1,2 

Here, we present a dual approach to unlocking unconventional π-reactivity by leveraging distinct activation modes. First, high-reactivity alkali-metal catalysts generate transient anionic intermediates, such as heptatrienyl species; these undergo efficient ring closure to yield challenging architectures, including 7- membered carbocycles derived from biobased monoterpenes.3 In parallel, low-valent cobalt complexes can enable selective cycloaddition and C–C/C–X bond-forming reactions with olefins and small molecules. In these systems, precise control over oxidation state and electronic structure grants access to reactivity patterns unattainable with traditional catalysts. 

By merging the potent reactivity of alkali metals with the controlled coordination chemistry of low-valent transition metals, this work establishes new pathways for π-system functionalization. Our mechanistic insights provide a foundation for expanding the scope of cycloaddition chemistry and streamlining the synthesis of more complex molecular architectures with organometallic species. 

(1) Cycloaddition Reactions in Organic Synthesis; John Wiley & Sons, Ltd, 2001; pp i–xii. https://doi.org/10.1002/3527600256. 

(2) S. Komijani, A. Orellana, The Electrocyclization of Heptatrienyl Anions. Synthesis 2023, s-0040-1720086. https://doi.org/10.1055/s-0040-1720086. 

(3) M. Le Roch, K. Piech, A. Crochet, A. Tortajada, Alkali-Metal Base Catalyzed Electrocyclization of Isoprene Derivatives. ChemRxiv 2026 https://doi.org/10.26434/chemrxiv.15000385/v2.