A bulky and electron-rich N-heterocyclic carbene–palladium complex (SIPr)Ph2 Pd­(cin)Cl was synthesized and characterized. It was found to be highly efficient and versatile for the coupling of different (hetero)­aryl chlorides with various (hetero)­aryl amines at room temperature, especially for the challenging amination of five- or six-membered ring heteroaryl chlorides with five- or six-membered ring heteroaryl amines. It was also successfully applied with high yields to the synthesis of various commercial pharmaceuticals and candidate drugs or compounds with potential pharmacological activities. All of these demonstrate its excellent catalytic efficacy in Buchwald–Hartwig amination and broad application prospects in relevant pharmaceutical preparations. DFT calculations suggest that the steric-induced electronic interaction makes the ligand more electron-donating, and the steric effect effectively regulates the rotation of the iPr-Ph-iPr group in the catalyzed system due to the introduction of the diphenyl skeleton. Considering the electronic effect and the steric effect together, the oxidative addition activation barriers of the (SIPr)Ph2 and (SIPr) ligands are close to each other. Reductive elimination is the rate-determining step of the (SIPr)Ph2 Pd­(cin)­Cl-catalyzed system in the catalytic cycle, and the appropriate steric hindrance of the (SIPr)Ph2 ligand greatly reduces the energy barrier of this step. The perfect combination of the electron-donating and steric hindrance abilities of the ligand significantly improves the catalytic activity.

A series of Pd–PEPPSI complexes were designed and synthesized. The relationship between catalyst structure and properties was systematically investigated. It was revealed that “bulky‐yet‐flexible” C3 bearing ancenaphthyl backbone was a highly efficient precatalyst and could be successfully employed in Suzuki–Miyaura reactions of (hetero)aryl chlorides with (hetero)arylboronic acids at a low palladium loading in the presence of a weak inorganic base in air.

Through the strategy to enhance the bulkiness on both the backbone and the N-aryl moieties, we designed and synthesized a type of bulky α-diimine palladium complex (i.e., {[Ar-N[double bond, length as m-dash]C(R)-C(R)[double bond, length as m-dash]N-Ar]PdCl2, (Ar = 2-benzhydryl-4,6-dimethylphenyl)}, C1, R = H; C2, R = An; C3, R = Ph). The structures of these palladium complexes were well characterized, while C1 and C3 were further characterized by X-ray diffraction. The catalytic performances of the precatalysts were screened for direct C-H bond arylation of heteroarenes. The bidentate N,N-palladium complex C3 with both a backbone and N-aryl bulkiness was found to be a highly efficient precatalyst under aerobic conditions. With a low palladium loading of 0.5-0.1 mol%, a variety of heteroarenes with challenging bulky steric aryl bromides as well as heteroaryl bromides are all applicable for this cross-coupling reaction.

The copper(II)-catalyzed [4+1] cyclizations and copper(I)-catalyzed [3+2] cycloadditions of iodonium ylides and alkynes were successfully developed by employing efficient and safe iodonium ylides instead of traditional diazo compounds. Highly functionalized...

Iridium-catalyzed intramolecular asymmetric allylic etherification of salicylic acid derivatives was successfully realized for the first time. By using chiral-bridged biphenyl phosphoramidite ligand L7, a class of novel chiral 1,4-benzoxazepinones was...