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Upstream product

• 617-86-7 triethylsilane 
• 3475-21-6 4-methyl-2-phenylpyridine 

Relevant academic research and scientific papers

An effective and versatile strategy for the synthesis of structurally diverse heteroarylsilanesviaIr(iii)-catalyzed C-H silylation

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.

Hemilabile N-Xylyl-N ′-methylperimidine carbene iridium complexes as catalysts for C-H activation and dehydrogenative silylation: Dual role of N-xylyl moiety for ortho-C-H bond activation and reductive bond cleavage

Direct dehydrogenative silylation of pyridyl and iminyl substrates with triethylsilane was achieved using (L)Ir(cod)(X) (1) (L = a perimidine-based carbene ligand, X = OAc and OCOPh) complexes as catalysts under toluene refluxing conditions in the presence of norbornene as a hydrogen scavenger, and the silylated products were obtained in good yields. The isolated bis(cyclometalated)iridium complexes, (CaC:)(C aN)IrOAc (2) (CaC: = a cyclometalated perimidine-carbene ligand and CaN = a cyclometalated pyridyl- and iminyl-ligated aromatic substrate), were key intermediates, where cyclometalated five-membered metallacycles of substrates such as phenylpyridine were selectively formed before yielding mono-ortho-silylation products. The bis(cyclometalated)iridium complex ( XyCaC:)(CaN)IrOAc (2d) (XyCaC: = a cyclometalated N-xylyl-N′-methylperimidine-carbene ligand and CaN = a 2-pyridylphenyl ligand), reacted with 2 equiv of Et3SiH to give an iridium hydride complex, (L4)(CaN)Ir(H) (SiEt3) (8d) (L4 = N-CH3, N-3,5-(CH 3)2C6H3 perimidine), via demetalation of a N-3,5-xylyl ring of the carbene ligand of 2d. The formation of 8d was confirmed by isolating the corresponding chloro complex (L 4)(CaN)Ir(Cl)(SiEt3) (8d-Cl) by treatment with CCl4. The N-methyl moiety of the carbene ligand coordinated to 8d was cyclometalated in the presence of norbornene at room temperature to afford (MeCaC:)(C aN)Ir(SiEt3) (10d) (MeC aC: = a cyclometalated N-xylyl-N′-methylperimidine- carbene), while at high temperature 8d reacted with norbornene and Et 3SiH to afford the silylated product, 2-(2-triethylsilyl) phenylpyridine (3a) and norbornane. A deuterium labeling experiment using 2d and Et3SiD (excess) revealed the incorporation of deuterium atoms at two ortho-positions of the N-xylyl group (>90%) and at the 3-position of 2-pyridylphenyl ligand (ca. 40%) within 3 h at room temperature, indicating that the cyclometalation/demetalation of the N-xylylperimidine carbene and 2-phenylpyridine ligands were reversible processes. Isolation of these cyclometalated iridium complexes under controlled conditions and D-labeling experiments thus revealed a dual function of the N-aryl group bound to the perimidine-carbene ligand, which acted as both a neutral carbene ligand and a monoanionic ortho-metalated aryl-carbene ligand through reversible C-H bond activation and Ir-C bond cleavage of the N-aryl group during the catalytic cycle.