Palladium-Catalyzed Deuterodehalogenation of Halogenated Aryl Triflates Using Isopropanol-d8 as the Deuterium Source

In this study, a novel and efficient Pd-catalyzed chemoselective deuterodehalogenation reaction of halogenated aryl triflates was developed using isopropanol-d8 as the deuterium source. This chemoselective reaction afforded an unconventional chemoselectivity order of C-Br > C-Cl > C-OTf. This catalytic system was successfully applied to chemoselective hydrodehalogenation of chloroaryl triflates, providing excellent C-Cl chemoselectivity over C-OTf.

Oxidation of Pd(II) with disilane in a palladium-catalyzed disilylation of aryl halides: a theoretical view

Density functional theory (DFT) calculation has been used to reveal the mechanism of the Pd-catalyzed disilylation reaction of aryl halides. The DFT calculations indicate that the reaction starts with the oxidative addition of the C-I bond to the Pd(0) catalyst. Concerted metalation-deprotonation (CMD) can then generate a five-membered palladacycle. Insertion of Pd(ii) into the Si-Si bond in disilane followed by two sequential steps of reductive eliminations yields the disilylation product and regenerates the Pd(0) catalyst. According to the NPA charge analysis along the reaction coordinates, the formal oxidative addition of the Si-Si bond to palladium could be considered as the insertion of palladium into the Si-Si bond. However, the conventional oxidative addition of the C-I bond to palladium is exactly an oxidation process with the electron transfer from the palladium atom to the C-I bond. Therefore, electron rich Pd(0) is beneficial for the oxidation process, and Pd(ii) prone to acquire electrons is beneficial for the insertion process.

Lewis acid-catalyzed synthesis of silafluorene derivatives from biphenyls and dihydrosilanes via a double sila-Friedel–Crafts reaction

The synthesis of silafluorene derivatives from aminobiphenyl compounds and dihydrosilanes via a double sila-Friedel–Crafts reaction using a borane catalyst has been achieved.

Ruthenium-Catalyzed Site-Selective Intramolecular Silylation of Primary C-H Bonds for Synthesis of Sila-Heterocycles

Incorporating the silicon element into bioactive organic molecules has received increasing attention in medicinal chemistry. Moreover, organosilanes are valuable synthetic intermediates for fine chemicals and materials. Transition metal-catalyzed C-H silylation has become an important strategy for C-Si bond formations. However, despite the great advances in aromatic C(sp²)-H bond silylations, catalytic methods for aliphatic C(sp³)-H bond silylations are relatively rare. Here we report a pincer ruthenium catalyst for intramolecular silylations of various primary C(sp³)-H bonds adjacent to heteroatoms (O, N, Si, Ge), including the first intramolecular silylations of C-H bonds α to O, N, and Ge. This method provides a general, synthetically efficient approach to novel classes of Si-containing five-membered [1,3]-sila-heterocycles, including oxasilolanes, azasilolanes, disila-heterocycles, and germasilolane. The trend in the reactivity of five classes of C(sp³)-H bonds toward the Ru-catalyzed silylation is elucidated. Mechanistic studies indicate that the rate-determining step is the C-H bond cleavage involving a ruthenium silyl complex as the key intermediate, while a η²-silene ruthenium hydride species is determined to be an off-cycle intermediate.