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Updated: May 15, 2026

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
A simple metal-promoted three-step access to n/5/m angular carbocyclic systems
José Barluenga1, Ana Álvarez-Fernández, Tatiana Suárez-Rodríguez
1Departamento de Química Orgánica e Inorgánica, Universidad de Oviedo, Julian Clavería 8, 33071 Oviedo, Spain. barluenga@uniovi.es
A new three-step synthesis provides access to angular tricyclic skeletons using readily available starting materials. This method utilizes cyclopentannulation and metal-promoted fragmentation, followed by cyclization strategies.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
- Catalysis
Background:
- Tricyclic skeletons are important structural motifs in natural products and pharmaceuticals.
- Efficient synthetic routes to complex molecular architectures are highly sought after.
Purpose of the Study:
- To develop a simple and efficient three-step method for synthesizing n/5/m angular tricyclic skeletons.
- To explore novel cyclization pathways for constructing these complex structures.
Main Methods:
- Cyclopentannulation of propargylmalonates with enynyl Fischer carbenes.
- Metal-promoted Cope-type fragmentation of the propargyl unit.
- Tin enolate-mediated 5-exo annulation or gold-catalyzed 6-endo cyclization.
Main Results:
- Successful synthesis of angular tricyclic skeletons in three steps.
- Demonstration of two distinct cyclization pathways (5-exo and 6-endo).
- Formation of 4-allenyl-carbonyl intermediates enabling further transformations.
Conclusions:
- The developed method offers a straightforward access to valuable tricyclic frameworks.
- The study highlights the versatility of the intermediates for diverse cyclization reactions.
- This approach provides a new tool for constructing complex organic molecules.
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