Recursive anionic γ'-spiro-annulation of cyclic vinylogous esters with 2-vinylbenzoates

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• Cyclic vinylogous esters (CVEs) are versatile building blocks.
• Developing selective methods for complex scaffold synthesis is crucial.

Purpose of the Study:

• To report a novel γ'-selective anionic cascade spiroannulation reaction.
• To utilize CVEs as γ',γ'-dianionic equivalents and 2-vinylbenzoates as 1,5-dielectrophiles.

Main Methods:

• Reaction of CVEs with 2-vinylbenzoates.
• Catalysis by KOtBu and Cu(I) salt in DMF.
• Thermal conditions.

Main Results:

• Achieved high γ'-selectivity in the spiroannulation.
• Demonstrated CVEs acting as γ',γ'-dianionic equivalents.
• Successfully constructed densely functionalized spirocarbocyclic scaffolds.

Conclusions:

• The developed method offers a new route to complex spirocycles.
• The reaction mechanism involves recursive anionic activation via deprotonation.
• This transformation enables rapid synthesis of structurally intricate molecules.