Highly effective hydrosilylation reactions catalysed by iridium (III) metallacycles in green conditions

Within the context of hydrosilylation, Ir(III) cyclometallated complexes were found to display novel catalytic properties for the intermolecular tandem hydroamination-hydrosilylation reaction between alkynes and amines.1... [ view full abstract ]

Within the context of hydrosilylation, Ir(III) cyclometallated complexes were found to display novel catalytic properties for the intermolecular tandem hydroamination-hydrosilylation reaction between alkynes and amines.¹ Following this seminal work, we have devoted research efforts to define the potential of such Ir(III) metallacycles² in the hydrosilylation of a diversity of organic compounds.³ We have demonstrated specific metallacycle catalysts, obtained from easily accessible and robust pre-catalysts, are efficient in the reduction of amides, esters and carboxylic acids which are known to be difficult substrates. Indeed, well-defined Ir(III) metallacycle catalysts are extremely active and selective even at low catalyst loadings providing the reduced organics in high yields and TONs. Carboxylic acids could be reduced selectively into alcohols, esters into aldehydes,⁴ and amides into amines⁵ (Figure 1). Besides the results devoted to the catalytic hydrosilylation processes, the reaction mechanisms have be highlighted on the basis of extensive advanced NMR and HRMS experiments as well as on the isolation of key catalytic intermediates and on theoretical calculations.

References

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