Indium(III) as π-acid catalyst for the electrophilic activation of carbon–carbon unsaturated systems.

Pérez Sestelo, J. ; Sarandeses, L. A.; Martínez, M. M.; Alonso-Marañón, L.


Org. Biomol. Chem. 2018, 16, 5733–5747 (DOI: 10.1039/c8ob01426d).

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This review focuses on the utilization of indium(III) as p-acid for the activation of C–C unsaturated bonds in organic synthesis. In addition to its well-known s-coordination with carbonyl derivatives, indium(III) undergoes efficient p-coordination with unsaturated systems to trigger nucleophilic addition.

Accordingly, indium(III) halides and salts (InX3, X = Cl, Br, I, OTf, ONf, NTf2) have been reported as useful catalysts for a broad range of carbon–carbon and carbon–heteroatom bond formation reactions, including hydrofunctionalization (hydroarylation, hydroamination, hydroalkoxylation, and hydrothiolation), enyne cycloisomerization, and related reactions. In these reactions the counterion has a significant effect on the catalytic activity, and the development of novel In(III) complexes and the generation of highly electrophilic cationic indium(III) species has increased its synthetic applications as a p-acid catalyst.