An effective and versatile strategy for the synthesis of structurally diverse heteroarylsilanes via Ir( iii )-catalyzed C–H silylation

• Published in: Chemical science (Cambridge) 2021-07, Vol.12 (28), p.9748-9753
• Main Authors: Yan, Zhi-Bo, Peng, Meng, Chen, Qi-Long, Lu, Ka, Tu, Yong-Qiang, Dai, Kun-Long, Zhang, Fu-Min, Zhang, Xiao-Ming
• Format: Article
• Language: English
• Subjects: Catalysis; Chelation; Chemistry; Crystallography; Substrates
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d1sc02344f

A versatile silylation of heteroaryl C–H bonds is accomplished under the catalysis of a well-defined spirocyclic NHC Ir( iii ) complex (SNIr), generating a variety of heteroarylsilanes. A significant advantage of this catalytic system is that multiple types of intermolecular C–H silylation can be achieved using one catalytic system at α, β, γ, or δ positions of heteroatoms with excellent regioselectivities. Mechanistic experiments and DFT calculations indicate that the polycyclic ligand of SNIr can form an isolable cyclometalated intermediate, which leaves a phenyl dentate free and provides a hemi-open space for activating substrates. In general, favorable silylations occur at γ or δ positions of chelating heteroatoms, forming 5- or 6-membered C–Ir–N cyclic intermediates. If such an activation mode is prohibited sterically, silylations would take place at the α or β positions. The mechanistic studies would be helpful for further explaining the reactivity of the SNIr system.