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ABSTRACT Since its introduction by Kagan more than 40 years ago, samarium(ii) iodide (SmI2; Kagan’s reagent) has found copious applications in organic synthesis. Its inherent strong reducing

ability, together with external additives, enable tunable reactivity and endow SmI2 with powerful reactivity and impressive chemoselectivity. As a result, SmI2 has been broadly applied in a

wide range of useful transformations, especially those involving C–C bond formation, in which both radical and ionic pathways could be selectively accessible. In the total synthesis of

natural products, the versatility of SmI2 renders it more appealing than other single-electron reductants, particularly when used in key steps at the late stages of synthetic routes.

Moreover, its ability to reach previously unattainable C–C bond disconnections accelerates the development of new synthetic strategies. In this Review, we highlight selected examples of

SmI2-mediated C–C bond formation in the total synthesis of natural products reported from 2014 to 2021. Access through your institution Buy or subscribe This is a preview of subscription

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DIRECTED C–H FUNCTIONALIZATION WITH NUCLEOPHILES Article 27 October 2022 CASCADE ASYMMETRIC DEAROMATIVE CYCLIZATION REACTIONS VIA TRANSITION-METAL-CATALYSIS Article 14 March 2022

TRANSITION-METAL FREE C–N BOND FORMATION FROM ALKYL IODIDES AND DIAZONIUM SALTS VIA HALOGEN-ATOM TRANSFER Article Open access 27 December 2022 REFERENCES * Namy, J. L., Girard, P. &

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ACKNOWLEDGEMENTS Financial support of this research from the Chinese Academy of Sciences (supported by the Strategic Priority Research Program, grant XDB20020200 and QYZDJ-SSW-SLH029) and

the National Natural Science Foundation of China (grants 21132008, 21831009 and 21991110) is acknowledged. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * State Key Laboratory of Bioorganic

and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of the Chinese Academy of Sciences, Chinese Academy of

Sciences, Shanghai, China Yang Gao & Dawei Ma Authors * Yang Gao View author publications You can also search for this author inPubMed Google Scholar * Dawei Ma View author publications

You can also search for this author inPubMed Google Scholar CONTRIBUTIONS Y.G. and D.M. contributed to discussions and wrote the manuscript. CORRESPONDING AUTHOR Correspondence to Dawei Ma.

ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. PEER REVIEW PEER REVIEW INFORMATION _Nature Synthesis_ thanks Scott Snyder and the other, anonymous,

reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Alison Stoddart, in collaboration with the _Nature Synthesis_ team. ADDITIONAL INFORMATION

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THIS ARTICLE CITE THIS ARTICLE Gao, Y., Ma, D. Samarium iodide-mediated C–C bond formation in the total synthesis of natural products. _Nat. Synth_ 1, 275–288 (2022).

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