DOI: 10.1002/adsc.70694 ISSN: 1615-4150

Organocatalyzed Asymmetric Allylic Alkylation: A Key Step in the Synthesis of Spirolactone Cycloheptannulated Heteroarenes

Bastien Gitton, Rémi Pereira, Aurélien Blanc, Fabienne Grellepois, Emmanuel Riguet

A concise three‐step strategy provides enantioenriched, densely functionalized cycloheptannulated heteroarenes bearing a spirolactone motif adjacent to a tertiary stereocenter. The sequence begins with racemic α‐heteroaromatic γ‐butyrolactones, which undergo a microwave‐assisted Aromatic Cope rearrangement to afford key α‐(allyl)heteroaryl lactone intermediates. A subsequent organocatalytic Allylic Alkylation, leveraging a readily accessible Lewis base, enables the efficient synthesis of chiral lactones with excellent stereoselectivity ( dr up to >99:1, er up to 99 :1) and good to very good yields (up to 94%). The final ring‐closing metathesis step seamlessly constructs the target polycyclic frameworks, demonstrating broad structural versatility.

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