Catalytic Asymmetric Cationic Geranyl Cyclizations
Na Luo1, Mathias Turberg1, Nobuya Tsuji2
1Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr45470, Germany.
Researchers developed a new catalytic method for asymmetric cyclization of geranyl compounds using confined chiral Brønsted acids. This breakthrough enables efficient synthesis of complex terpenes and natural product scaffolds.
Area of Science:
- Organic Chemistry
- Catalysis
- Natural Product Synthesis
Background:
- Cyclogeranyl motifs are crucial building blocks in natural products and terpene synthesis.
- Asymmetric formation of these motifs from acyclic dienes presents a significant synthetic challenge.
Purpose of the Study:
- To develop a general catalytic asymmetric cyclization method for geranyl derivatives.
- To achieve high efficiency, regioselectivity, and enantioselectivity in terpene synthesis.
Main Methods:
- Utilized confined chiral imidodiphosphorimidate (IDPi) Brønsted acids as catalysts.
- Employed fluorinated alcohol additives to facilitate the reaction under mild conditions.
Main Results:
- Demonstrated high efficiency and excellent regio- and enantioselectivity for diverse geranyl substrates.
- Enabled access to fragrance scaffolds, retinal precursors, complex polycyclic terpenes, and selective squalene cyclization.
- Mechanistic studies revealed a cooperative catalyst-additive hydrogen-bonding network and an enzyme-like transition state.
Conclusions:
- The developed method offers a general solution for asymmetric geranyl cyclizations.
- Expands the application of confined Brønsted acid catalysis in biomimetic terpene synthesis.
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