Base‐Catalyzed Selective Deuteration of Alkynes

Graphene Oxide Membrane Reactor for Electrochemical Deuteration Reactions

The deuteration of organic molecules is considerably important in organic and medicinal chemistry. An electrochemical membrane reactor using proton-conducting graphene oxide (GO) nanosheets was developed to synthesize valuable deuterium-labeled products via an efficient hydrogen-to-deuterium (H/D) exchange under mild conditions at ambient temperature and atmospheric pressure. Deuterons (D+) formed by the anodic oxidation of heavy water (D2O) at the Pt/C anode permeate through the GO membrane to the Pt/C cathode, where organic molecules with functional groups (C≡C and C═O) are deuterated with adsorbed atomic D species. Deuteration occurs in outstanding yields with high levels of D incorporation. We also achieved the electrodeuteration of a drug molecule, ibuprofen, demonstrating the promising feasibility of the GO membrane reactor in the pharmaceutical industry.

Alkali-metal bases in catalytic hydrogen isotope exchange processes

The preparation of compounds labelled with deuterium or tritium has become an essential tool in a range of research fields. Hydrogen isotope exchange (HIE) offers direct access to said compounds, introducing these isotopes in a late stage. Even though the field has rapidly advanced with the use of transition metal catalysis, alkali-metal bases, used as catalysts or under stoichiometric conditions, have also emerged as a viable alternative. In this minireview we describe the latest advances in the use of alkali-metal bases in HIE processes, showcasing their synthetic potential as well as current challenges in the field. It is divided in different sections based on the isotope source used, emphasizing their benefits, disadvantages and limitations. The influence on the choice of alkali-metal in these processes as well as their possible mechanistic pathways are also discussed.

K2CO3/18-Crown-6-Catalyzed Selective H/D Exchange of Heteroarenes with Bromide as a Removable Directing Group

The K₂CO₃/18-crown-6-catalyzed H/D exchange of heretoarenes in high atom % deuterium incorporation is disclosed. The use of a weak base as a catalyst leads to excellent site selectivity and broad functional group tolerance. Control experiments indicated that the use of bromide, which enhances the adjacent C-H bond reactivity, as a removable directing group is essential. Moreover, conversion of bromide to other functional groups is also performed to construct other useful deuterated compounds.

Straightforward and Efficient Deuteration of Terminal Alkynes with Copper Catalysis

The mild and effective preparation of deuterated organic molecules is an active area of research due to their important applications. Herein, we report an air-stable and easy to access copper(I) complex as catalyst for the deuteration of mono-substituted alkynes. Reactions were carried out in technical solvents and in the presence of air, to obtain excellent deuterium incorporation in a range of functionalised alkynes.

Selectivity Controlled Hydroamination of Alkynes to Sulfonyl Fluoride Hubs: Development and Application

A hydroamination of unactivated alkynes and lithium bis(fluorosulfonyl)imide (LiN(SO₂F)₂) is described under mild conditions, affording a single regioisomer of the sulfonyl fluorides. This method features broad functional group compatibility and delivers the target vinyl fluorosulfonimides in good to excellent yields. Moreover, gram-scale hydroamination of terminal and internal alkynes is achieved. Further transformations exploiting the reactivity of the vinyl fluorosulfonimide are subsequently developed for the synthesis of fluorosulfates and diphenyl sulfate.

Recent Developments for the Deuterium and Tritium Labeling of Organic Molecules

Organic compounds labeled with hydrogen isotopes play a crucial role in numerous areas, from materials science to medicinal chemistry. Indeed, while the replacement of hydrogen by deuterium gives rise to improved absorption, distribution, metabolism, and excretion (ADME) properties in drugs and enables the preparation of internal standards for analytical mass spectrometry, the use of tritium-labeled compounds is a key technique all along drug discovery and development in the pharmaceutical industry. For these reasons, the interest in new methodologies for the isotopic enrichment of organic molecules and the extent of their applications are equally rising. In this regard, this Review intends to comprehensively discuss the new developments in this area over the last years (2017-2021). Notably, besides the fundamental hydrogen isotope exchange (HIE) reactions and the use of isotopically labeled analogues of common organic reagents, a plethora of reductive and dehalogenative deuteration techniques and other transformations with isotope incorporation are emerging and are now part of the labeling toolkit.