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Transition metal–catalyzed cross-coupling reactions are some of the most widely used methods in chemical synthesis. However, despite notable advantages of iron (Fe) as a potentially cheaper, more abundant, and less toxic transition metal catalyst, its practical application in multicomponent cross-couplings remains largely unsuccessful. We demonstrate 1,2-bis(dicyclohexylphosphino)ethane Fe–catalyzed coupling of α-boryl radicals (generated from selective radical addition to vinyl boronates) with Grignard reagents. Then, we extended the scope of these radical cascades by developing a general and broadly applicable Fe-catalyzed multicomponent annulation–cross-coupling protocol that engages a wide range of π-systems and permits the practical synthesis of cyclic fluorous compounds. Mechanistic studies are consistent with a bisarylated Fe(II) species being responsible for alkyl radical generation to initiate catalysis, while carbon-carbon bond formation proceeds between a monoarylated Fe(II) center and a transient alkyl radical.
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This content will become publicly available on November 24, 2026
Terpenoid Synthesis via Convergent Radical Annulation
Abstract The development of a convergent radical annulation strategy for the synthesis of complex terpenoids from sclareolide is disclosed. This approach employs a 1,3‐diradical synthon to enable rapid C‐ring annulation through inter‐ and intramolecular radical couplings, exemplified in the concise syntheses of serratene and cyclodammarane scaffolds from a common intermediate. Key features include a rapid alternating polarity (rAP) Kolbe electrolysis for onoceradiene assembly, a Co‐electrocatalytic metal‐catalyzed hydrogen atom transfer (MHAT) 7‐endo‐trig cycloisomerization─the first of its kind─to form the serratene core, and a tandem Fe‐mediated reductive olefin coupling/enolate alkylation cascade─also unprecedented─to forge the [4.3.1] propellane motif of cyclodammaranes with complete diastereocontrol over three contiguous quaternary centers. These routes, completed in 5–9 steps, maximize skeletal bond‐forming efficiency, feature unique radical cascades, and highlight the advantages of radical‐based disconnections in terpenoid synthesis.
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- Award ID(s):
- 2002158
- PAR ID:
- 10657587
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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