摘要：Graduate School of Chemical andBiological Sciences, Scripps Research, La Jolla, California 92037, United State

转自：康龙化成

Alkene Hydrobenzylationby a Single Catalyst That Mediates Iterative Outer-Sphere Steps

Lingran Kong, Xu-cheng Gan, Vincent A. van der PuylLovett, and Ryan A. Shenvi*

Department of Chemistry, ScrippsResearch, La Jolla, California 92037, United States;

Graduate School of Chemical andBiological Sciences, Scripps Research, La Jolla, California 92037, United State

—J.Am. Chem. Soc. 2024, 146, 4, 2351-2357.

Recommended by Shi Li_MOC

KEYWORDS:cross-coupling (反应类型),alkene hydrobenzylation(反应类型), Iron catalysis (反应类型),metal hydride hydrogen atom transfer(MHAT) (反应类型), C(sp3)-C(sp3) (成键类型), benzyl bromide (原料),alkene (原料), alkane (产物), Fe(T4CPP)Cl (催化剂)

ABSTRACT: Cross-couplingcatalysts typically react and unite functionally distinct partners viasequential inner-sphere elementary steps: coordination, migratory insertion,reductive elimination, etc. Here, R. A. Shenvi reported a single catalyst thatcross-couples styrenes and benzyl bromides viaiterative outer-sphere steps: metal–ligand-carbon interactions. Each partnerforms a stabilized radical intermediate, yet heterocoupled products predominate. The systemis redox-neutral and, thus, avoids exogenous oxidants, resulting in simple andscalable conditions. Numerous variations of alkene hydrobenzylation are made possible, includingaccess to the privileged heterodibenzyl (1,2-diarylethane) motif andchallenging quaternary carbon variants.

Background and this work

Optimization studies

Variation of Conjugated Alkene

Variation of Arylmethyl Bromide

Unconjugated Alkenes and Natural Product Scaffolds

Experiments relevant to the mechanism

RyanA. Shenvi et al have identified an iron porphyrin catalyst [Fe(T4CPP)Cl]that is effective to cross-couple alkenes with benzyl bromides via radicalintermediates, even when two benzyl radicals of similar stability are formed asintermediates. The coupling scope includes mono-, di-, tri-, and tetrasubstituted alkenesamong conjugated and unconjugated alkenes alike. When styrenes areused as substrates, two similar benzyl radicals are produced as intermediates,yet the heterodimeric products predominate. In contrast to precious metalcatalysts, alkenes are functionalized by these base metal complexes without theneed for either carbon to bind to the metal center. As a result, these systemsrepresent powerful platforms for the synthesis and modification of naturalproducts in which alkenes are often crowded and unreactive toward traditionalmetal complexes.

来源：新浪财经