A highly efficient cobalt-catalyzed deuterogenolysis of diboron: Synthesis of deuterated pinacolborane and vinylboronates

Nickel-Catalyzed Deuteration of Primary, Secondary, and Tertiary Silanes: Scope and Mechanistic Insights

Deuterated silanes are crucial reagents for deuteration, with a diverse range of applications in materials science, pharmaceuticals, and isotopic labeling. While most methods for synthesizing deuterated silanes rely on stoichiometric environmentally harmful processes or noble metal catalysts, research into more sustainable alternatives has received relatively less attention. In this study, we introduce a catalyst based on a nickel PBP-pincer system (PBP = bis(phosphino)boryl), which effectively facilitates catalytic hydrogen/deuterium exchange for primary, secondary, and tertiary silanes, as well as tertiary siloxanes and certain boranes, utilizing a catalyst loading of 2 mol % at 25 °C. DFT calculations identify two reaction pathways that require overcoming similar energy barriers for the H/D exchange step: silane activation assisted by the PBP ligand (ΔG⧧ = 24.1 kcal mol-1) and H/D exchange promoted by nucleophilic Ni-hydride (ΔG⧧ = 22.4 kcal mol-1). These results suggest that both pathways are feasible, with a slight energetic preference for the latter. We also present detailed mechanistic studies, including control experiments, an analysis of catalyst deactivation pathways, and kinetic studies that are in excellent agreement with the outcome of the theoretical calculations.

Stereoselective Semi-Hydrogenations of Alkynes by First-Row (3d) Transition Metal Catalysts

The chemo- and stereoselective semi-hydrogenation of alkynes to alkenes is a fundamental transformation in synthetic chemistry, for which the use of precious 4d or 5d metal catalysts is well-established. In mankind's unwavering quest for sustainability, research focus has considerably veered towards the 3d metals. Given their high abundancy and availability as well as lower toxicity and noxiousness, they are undoubtedly attractive from both an economic and an environmental perspective. Herein, we wish to present noteworthy and groundbreaking examples for the use of 3d metal catalysts for diastereoselective alkyne semi-hydrogenation as we embark on a journey through the first-row transition metals.

First-Row d-Block Element-Catalyzed Carbon-Boron Bond Formation and Related Processes

Organoboron reagents represent a unique class of compounds because of their utility in modern synthetic organic chemistry, often affording unprecedented reactivity. The transformation of the carbon-boron bond into a carbon-X (X = C, N, and O) bond in a stereocontrolled fashion has become invaluable in medicinal chemistry, agrochemistry, and natural products chemistry as well as materials science. Over the past decade, first-row d-block transition metals have become increasingly widely used as catalysts for the formation of a carbon-boron bond, a transformation traditionally catalyzed by expensive precious metals. This recent focus on alternative transition metals has enabled growth in fundamental methods in organoboron chemistry. This review surveys the current state-of-the-art in the use of first-row d-block element-based catalysts for the formation of carbon-boron bonds.

A General Rhodium Catalyst for the Deuteration of Boranes and Hydrides of the Group 14 Elements

Pinacolborane, catecholborane, triethylsilane, triphenylsilane, dimethylphenylsilane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, triethylgermane, triphenylgermane, and triphenylstannane deuterated at the heteroatom position have been catalytically prepared in 50-70% isolated yield, through H/D exchange between the D₂ molecule and the respective boranes and hydrides of the group 14 elements, in the presence of the rhodium(I)-monohydride catalyst precursor RhH{κ³-P,O,P-[xant(PⁱPr₂)₂]} (xant(PⁱPr₂)₂ = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene).