The renaissance of H/D exchange

Pd/C-Catalyzed Stereoselective Arene Hydrogenation of Benzocyclobutenes Enabled by π-Bond Localization

We developed here a Pd/C-catalyzed diastereoselective cis-hydrogenation of benzocyclobutene derivatives under mild conditions to deliver an array of bicyclo[4.2.0]octane scaffolds with up to five stereocenters. The π-bond localization enabled hydrogenation of the arene moiety to occur even at room temperature under 1 atm of a H2 atmosphere.

Metallaphotoredox deuteroalkylation utilizing thianthrenium salts

Deuterium labeling compounds play a crucial role in organic and pharmaceutical chemistry. The synthesis of such compounds typically involves deuterated building blocks, allowing for the incorporation of deuterium atoms and functional groups into a target molecule in a single step. Unfortunately, the limited availability of synthetic approaches to deuterated synthons has impeded progress in this field. Here, we present an approach utilizing alkyl-substituted thianthrenium salts that efficiently and selectively introduce deuterium at the α position of alkyl chains through a pH-dependent HIE process, using D2O as the deuterium source. The resulting α-deuterated alkyl thianthrenium salts, which bear two deuterium atoms, exhibit excellent selectivity and deuterium incorporation in electrophilic substitution reactions. Through in situ formation of isotopically labelled alkyl halides, these thianthrenium salts demonstrate excellent compatibility in a series of metallaphotoredox cross-electrophile coupling with (hetero)aryl, alkenyl, alkyl bromides, and other alkyl thianthrenium salts. Our technique allows for a wide range of substrates, high deuterium incorporation, and precise control over the site of deuterium insertion within a molecule such as the benzyl position, allylic position, or any alkyl chain in between, as well as neighboring heteroatoms. This makes it invaluable for synthesizing various deuterium-labeled compounds, especially those with pharmaceutical significance.

Synthesis of Deuterated Compounds by Flow Chemistry

Development of the efficient and practical method for the synthesis of deuterated compounds which occupies the broadest area among stable isotopes is one of the most essential issues toward the industrial advance and building a sustainable society. This review describes recent advances in deuteration reactions, where the continuous flow chemistry plays pivotal roles for the successful installation of deuterium atom into diverse organic frameworks, opening new fields of isotope-based synthetic chemistry.

Synthesis of Perdeuterated Alkyl Amines/Amides with Pt/C as Catalyst under Mild Conditions

A convenient method for the synthesis of perdeuterated alkyl amides/amines is disclosed. Perdeuterated acetyl amides can be achieved by a hydrogen-deuterium (H/D) exchange protocol with Pt/C as a catalyst and D2O as a deuterium source under mild conditions. After removal or reduction of the acetyl group, this protocol can provide perdeuterated primary, secondary, and tertiary amines, which are difficult to achieve via other methods.

Palladium-Catalyzed Deuteration of Arylketone Oxime Ethers

We report herein the development of palladium-catalyzed deacylative deuteration of arylketone oxime ethers. This protocol features excellent functional group tolerance, heterocyclic compatibility, and high deuterium incorporation levels. Regioselective deuteration of some biologically important drugs and natural products are showcased via Friedel-Crafts acylation and subsequent deacylative deuteration. Vicinal meta-C-H bond functionalization (including fluorination, arylation, and alkylation) and para-C-H bond deuteration of electro-rich arenes are realized by using the ketone as both directing group and leaving group, which is distinct from aryl halide in conventional dehalogenative deuteration.

Photochemistry in Medicinal Chemistry and Chemical Biology

Photochemistry has emerged as a transformative force in organic chemistry, significantly expanding the chemical space accessible for medicinal chemistry. Light-induced reactions enable the efficient synthesis of intricate organic structures and have found applications throughout the different stages of the drug discovery and development processes. Moreover, photochemical techniques provide innovative solutions in chemical biology, allowing precise spatiotemporal drug activation and targeted delivery. In this Perspective, we highlight the already numerous remarkable applications and the even more promising future of photochemistry in medicinal chemistry and chemical biology.

Electrocatalytic Hydrogenation Using Palladium Membrane Reactors

Hydrogenation is a crucial chemical process employed in a myriad of industries, often facilitated by metals such as Pd, Pt, and Ni as catalysts. Traditional thermocatalytic hydrogenation usually necessitates high temperature and elevated pressure, making the process energy intensive. Electrocatalytic hydrogenation offers an alternative but suffers from issues such as competing H2 evolution, electrolyte separation, and limited solvent selection. This Perspective introduces the evolution and advantages of the electrocatalytic Pd membrane reactor (ePMR) as a solution to these challenges. ePMR utilizes a Pd membrane to physically separate the electrochemical chamber from the hydrogenation chamber, permitting the use of water as the hydrogen source and eliminating the need for H2 gas. This setup allows for greater control over reaction conditions, such as solvent and electrolyte selection, while mitigating issues such as low Faradaic efficiency and complex product separation. Several representative hydrogenation reactions (e.g., hydrogenation of C=C, C≡C, C=O, C≡N, and O=O bonds) achieved via ePMR over the past 30 years were concisely discussed to highlight the unique advantages of ePMR. Promising research directions along with the advancement of ePMR for more challenging hydrogenation reactions are also proposed. Finally, we provide a prospect for future development of this distinctive hydrogenation strategy using hydrogen-permeable membrane electrodes.

Isonitriles as Alkyl Radical Precursors in Visible Light Mediated Hydro- and Deuterodeamination Reactions

Herein, we report the use of isonitriles as alkyl radical precursors in light-mediated hydro- and deuterodeamination reactions. The reaction is scalable, shows broad functional group compatibility and potential to be used in late-stage functionalization. Importantly, the method is general for Cα -primary, Cα -secondary and Cα -tertiary alkyl isonitriles. For most examples, high yields were obtained through direct visible-light irradiation of the isonitrile in the presence of a silyl radical precursor. Interestingly, in the presence of an organic photocatalyst (4CzIPN) a dramatic acceleration was observed. In-depth mechanistic studies using UV/Vis absorption, steady-state and time-resolved photoluminescence, and transient absorption spectroscopy suggest that the excited state of 4CzIPN can engage in a single-electron transfer with the isonitrile.

Synthesis of 15N-Pyridines and Higher Mass Isotopologs via Zincke Imine Intermediates

Methods to incorporate stable radioisotopes are integral to pharmaceutical and agrochemical development. However, despite the prevalence of pyridines in candidate compounds, methods to incorporate 15N atoms within their structures are limited. Here, we present a general approach to pyridine 15N-labeling that proceeds via ring-opening to NTf-Zincke imines and then ring-closure with commercially available 15NH4Cl salts. This process functions on a range of substituted pyridines, from simple building block-type compounds to late-stage labeling of complex pharmaceuticals, and 15N-incorporation is >95% in most cases. The reactivity of the Zincke imine intermediates also enables deuteration of the pyridine C3- and C5-positions, resulting in higher mass isotopologs required for LCMS analysis of biological fluids during drug development.

Single Electron Transfer Reductive Deuteration of Acyl Chlorides for the Synthesis of Deuterated Alcohols with a High Deuterium Atom Economy

We present a highly deuterium atom economical approach for the synthesis of deuterated alcohols via the single electron transfer (SET) reductive deuteration of acyl chlorides. Cost-effective sodium dispersion and EtOD-d1 were used as the single electron donor and deuterium donor, respectively. Our approach achieved up to 49% deuterium atom economy, which represents the highest deuterium atom economy yet achieved in SET reductive deuteration reactions. With all 20 tested substrates, excellent regioselectivity and >92% deuterium incorporations were obtained. Furthermore, we demonstrated the potential of this methodology by synthesizing four deuterated analogues of pesticides.

Benzyl Deuteriodifluoromethyl Sulfoxide: An Easily Accessible and Stable Reagent for Direct Deuterodifluoromethylthiolation

A new, stable and scalable reagent based on a sulfoxide skeleton for direct deuteriodifluoromethylthiolation has been developed. The reagent displays excellent reactivities toward Tf2O promoted C-H deuteriodifluoromethylthiolation of electron-rich arenes, indoles, alkenes, and intramolecular lactonization of 2-alkynylbenzoates. Moreover, high deuteration rates and good to excellent yields were achieved under metal-free reaction conditions. As a result, a wide range of deuteriodifluoromethylthilolated compounds were prepared, enabling further applications in drug discovery.

The Future of (Radio)-Labeled Compounds in Research and Development within the Life Science Industry

In this review the applications of isotopically labeled compounds are discussed and put into the context of their future impact in the life sciences. Especially discussing their use in the pharma and crop science industries to follow their fate in the environment, in vivo or in complex matrices to understand the potential harm of new chemical structures and to increase the safety of human society.

Late-Stage C-H Activation of Drug (Derivative) Molecules with Pd(ll) Catalysis

This review comprehensively analyses representative examples of Pd(II)-catalyzed late-stage C-H activation reactions and demonstrates their efficacy in converting C-H bonds at multiple positions within drug (derivative) molecules into diverse functional groups. These transformative reactions hold immense potential in medicinal chemistry, enabling the efficient and selective functionalization of specific sites within drug molecules, thereby enhancing their pharmacological activity and expanding the scope of potential drug candidates. Although notable articles have focused on late-stage C-H functionalization reactions of drug-like molecules using transition-metal catalysts, reviews specifically focusing on late-stage C-H functionalization reactions of drug (derivative) molecules using Pd(II) catalysts are required owing to their prominence as the most widely utilized metal catalysts for C-H activation and their ability to introduce a myriad of functional groups at specific C-H bonds. The utilization of Pd-catalyzed C-H activation methodologies demonstrates impressive success in introducing various functional groups, such as cyano (CN), fluorine (F), chlorine (Cl), aromatic rings, olefin, alkyl, alkyne, and hydroxyl groups, to drug (derivative) molecules with high regioselectivity and functional-group tolerance. These breakthroughs in late-stage C-H activation reactions serve as invaluable tools for drug discovery and development, thereby offering strategic options to optimize drug candidates and drive the exploration of innovative therapeutic solutions.

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.

Photocatalytic Dehalogenative Deuteration of Halides over a Robust Metal-Organic Framework

Deuterium labelling of organic compounds is an important process in chemistry. We report the first example of photocatalytic dehalogenative deuteration of both arylhalides and alkylhalides (40 substrates) over a metal-organic framework, MFM-300(Cr), using CD3 CN as the deuterium source at room temperature. MFM-300(Cr) catalyses high deuterium incorporation and shows excellent tolerance to various functional groups. Synchrotron X-ray powder diffraction reveals the activation of halogenated substrates via confined binding within MFM-300(Cr). In situ electron paramagnetic resonance spectroscopy confirms the formation of carbon-based radicals as intermediates and reveals the reaction pathway. This protocol removes the use of precious-metal catalysts from state-of-the-art processes based upon direct hydrogen isotope exchange and shows high photocatalytic stability, thus enabling multiple catalytic cycles.

B(C6F5)3-Catalyzed Intramolecular Hydroalkoxylation Deuteration Reactions of Unactivated Alkynyl Alcohols

Using D2O as a deuterium source, a method for the deuteration of intra- and extra-cyclic methylene has been developed for cyclic ethers with moderate yield and excellent deuterium incorporation. This transformation features superb functional group tolerance in a wide range of alkynols. Notably, the critical factor to achieve high deuterium incorporation is determined by the hydrogen isotope exchange reaction of an unstable oxonium ion. This novel methodology provides an efficient and concise synthetic route to a number of valuable deuterated cyclic ethers that are often difficult to prepare with other methods.

Deuterium- and Electron-Shuttling Catalysis for Deoxygenative Deuteration of Alcohols

A practical and precise method for visible-light-promoted deoxygenative deuteration of common aliphatic alcohols using D2O as the deuterium source is reported. Upon intermediacy of xanthate anions, a variety of primary, secondary, and tertiary alcohols can be facilely transformed into deuterioalkanes with excellent D-incorporation at predicted sites. The deoxygenation and deuteration sequence is catalyzed by in situ formed deuterated 2-mercaptopyridine, which plays dual roles as a deuterium atom transfer catalyst and an electron shuttle as well.

In situ Generated Iridium Nanoparticles as Hydride Donors in Photoredox-Catalyzed Hydrogen Isotope Exchange Reactions with Deuterium and Tritium Gas

We have studied the photoredox-catalyzed hydrogen isotope exchange (HIE) reaction with deuterium or tritium gas as isotope sources and in situ formed transition metal nanoparticles as hydrogen atom transfer pre-catalysts. By this means we have found synergistic reactivities applying two different HIE mechanisms, namely photoredox-catalyzed and CH-functionalization HIE leading to the synthesis of highly deuterated complex molecules. Finally, we adopted these findings successfully to tritium chemistry.

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.

External Flash Generation of Carbenoids Enables Monodeuteration of Dihalomethanes

In this study, incorporation of one deuterium atom was achieved by H-D exchange of one of the two identical methylene protons in various dihalomethanes (halogen=Cl, Br, and I) through a rapid-mixing microflow reaction of lithium diisopropylamide as a strong base and deuterated methanol as a deuteration reagent. Generation of highly unstable carbenoid intermediate and suppression of its decomposition were successfully controlled under high flow-rate conditions. Monofunctionalization of diiodomethane afforded various building blocks composed of boryl, stannyl, and silyl groups. The monodeuterated diiodomethane, which served as a deuterated C1 source, was subsequently subjected to diverted functionalization methods to afford various products including biologically important molecules bearing isotope labelling at specific positions and homologation products with monodeuteration.

Enantioconvergent construction of stereogenic silicon via Lewis base-catalyzed dynamic kinetic silyletherification of racemic chlorosilanes

Organosilanes possessing an enantioenriched stereogenic silicon center are important in many branches of chemistry, yet they remain challenging to synthesize in a practical and scalable way. Here we report a dynamic kinetic silyletherification process of racemic chlorosilanes with (S)-lactates using 4-aminopyridine as a Lewis base catalyst. This enantioconvergent approach asymmetrically constructs the stereogenic silicon center in a different manner from traditional resolution or desymmetrization. A range of silylethers have been prepared with high diastereoselectivity on up to 10 g-scale, allowing the practical synthesis of diverse enantioenriched organosilane analogs.

Programmable Deuteration of Indoles via Reverse Deuterium Exchange

Methods for selective deuterium incorporation into drug-like molecules have become extremely valuable due to the commercial, mechanistic, and biological importance of deuterated compounds. Herein, we report a programmable labeling platform that allows access to C2, C3, or C2- and C3-deuterated indoles under mild, user-friendly conditions. The C2-deuterated indoles are accessed using a reverse hydrogen isotope exchange strategy which represents the first non-directed C2-deuteration of indoles.

Mild and selective hydrogen-deuterium exchange for aromatic hydrogen of amines

The direct electrophilic deuteration of the aromatic moiety in aromatic and aralkyl amines is reported. The acid-catalyzed deuteration is facilitated by deuterated trifluoromethanesulfonic acid, [D]triflic acid, CF3 SO3 D, TfOD, which acts as both the reaction solvent and the source of the deuterium label. The mild conditions enable room temperature hydrogen/deuterium exchange for most of the para-substituted aromatic amine derivatives studied. In addition, short reaction times and a high degree of aromatic deuteration are achieved and isolation of the product is simple. The optical activity of the chiral aralkyl amines studied was preserved.

Deuterium in drug discovery: progress, opportunities and challenges

Substitution of a hydrogen atom with its heavy isotope deuterium entails the addition of one neutron to a molecule. Despite being a subtle change, this structural modification, known as deuteration, may improve the pharmacokinetic and/or toxicity profile of drugs, potentially translating into improvements in efficacy and safety compared with the non-deuterated counterparts. Initially, efforts to exploit this potential primarily led to the development of deuterated analogues of marketed drugs through a 'deuterium switch' approach, such as deutetrabenazine, which became the first deuterated drug to receive FDA approval in 2017. In the past few years, the focus has shifted to applying deuteration in novel drug discovery, and the FDA approved the pioneering de novo deuterated drug deucravacitinib in 2022. In this Review, we highlight key milestones in the field of deuteration in drug discovery and development, emphasizing recent and instructive medicinal chemistry programmes and discussing the opportunities and hurdles for drug developers, as well as the questions that remain to be addressed.

Formal Anti-Markovnikov Addition of Water to Olefins by Titanocene-Catalyzed Epoxide Hydrosilylation: From Stoichiometric to Sustainable Catalytic Reactions

Here, the evolution of the titanocene-catalyzed hydrosilylation of epoxides that yields the corresponding anti-Markovnikov alcohols is summarized. The study focuses on aspects of sustainability, efficient catalyst activation, and stereoselectivity. The latest variant of the reaction employs polymethylhydrosiloxane (PMHS), a waste product of the Müller-Rochow process as terminal reductant, features an efficient catalyst activation with benzylMgBr and the use of the bench stable Cp₂TiCl₂ as precatalyst. The combination of olefin epoxidation and epoxide hydrosilylation provides a uniquely efficient approach to the formal anti-Markovnikov addition of H₂O to olefins.

Identification of endogenous carbonyl steroids in human serum by chemical derivatization, hydrogen/deuterium exchange mass spectrometry and the quantitative structure-retention relationship

Steroids are tetracyclic aliphatic compounds, and most of them contain carbonyl groups. The disordered homeostasis of steroids is closely related to the occurrence and progression of various diseases. Due to high structural similarity, low concentrations in vivo, poor ionization efficiency, and interference from endogenous substances, it is very challenging to comprehensively and unambiguously identify endogenous steroids in biological matrix. Herein, an integrated strategy was developed for the characterization of endogenous steroids in serum based on chemical derivatization, ultra-performance liquid chromatography quadrupole Exactive mass spectrometry (UPLC-Q-Exactive-MS/MS), hydrogen/deuterium (H/D) exchange, and a quantitative structure-retention relationship (QSRR) model. To enhance the mass spectrometry (MS) response of carbonyl steroids, the ketonic carbonyl group was derivatized by Girard T (GT). Firstly, the fragmentation rules of derivatized carbonyl steroid standards by GT were summarized. Then, carbonyl steroids in serum were derivatized by GT and identified based on the fragmentation rules or by comparing retention time and MS/MS spectra with those of standards. H/D exchange MS was utilized to distinguish derivatized steroid isomers for the first time. Finally, a QSRR model was constructed to predict the retention time of the unknown steroid derivatives. With this strategy, 93 carbonyl steroids were identified from human serum, and 30 of them were determined to be dicarbonyl steroids by the charge number of characteristic ions and the number of exchangeable hrdrogen or comparing with standards. The QSRR model built by the machine learning algorithms has an excellent regression correlation, thus the accurate structures of 14 carbonyl steroids were determined, among which three steroids were reported for the first time in human serum. This study provides a new analytical method for the comprehensive and reliable identification of carbonyl steroids in biological matrix.

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.

Bringing Selectivity in H/D Exchange Reactions Catalyzed by Metal Nanoparticles through Modulation of the Metal and the Ligand Shell

Ru and Rh nanoparticles catalyze the selective H/D exchange in phosphines using D₂ as the deuterium source. The position of the deuterium incorporation is determined by the structure of the P-based substrates, while activity depends on the nature of the metal, the properties of the stabilizing agents, and the type of the substituent on phosphorus. The appropriate catalyst can thus be selected either for the exclusive H/D exchange in aromatic rings or also for alkyl substituents. The selectivity observed in each case provides relevant information on the coordination mode of the ligand. Density functional theory calculations provide insights into the H/D exchange mechanism and reveal a strong influence of the phosphine structure on the selectivity. The isotope exchange proceeds via C-H bond activation at nanoparticle edges. Phosphines with strong coordination through the phosphorus atom such as PPh₃ or PPh₂Me show preferred deuteration at ortho positions of aromatic rings and at the methyl substituents. This selectivity is observed because the corresponding C-H moieties can interact with the nanoparticle surface while the phosphine is P-coordinated, and the C-H activation results in stable metallacyclic intermediates. For weakly coordinating phosphines such as P(o-tolyl)₃, the interaction with the nanoparticle can occur directly through phosphine substituents, and then, other deuteration patterns are observed.

Modified Chemoselective Reduction and Consecutive Regioselective Deuteration Reaction Catalyzed by B(C6F5)3

An efficient chemoselective reduction of isatin derivatives using catalyst B(C₆F₅)₃, benzyldimethylsilane, and H₂O is described. Notably, a small amount of water is shown to be a highly effective reaction promoter that decreases the reaction time and temperature for the synthesis of indolin-3-ones. Moreover, using method, excellent deuterium incorporation is achieved via the catalytic α-deuteration of indolin-3-ones using B(C₆F₅)₃ and D₂O.

Cesium Amide-Catalyzed Selective Deuteration of Benzylic C-H Bonds with D2 and Application for Tritiation of Pharmaceuticals

Hydrogen isotope exchange (HIE) represents one of the most attractive labeling methods to synthesize deuterium- and tritium-labeled compounds. Catalytic HIE methods that enable site-selective C-H bond activation and exchange labeling with gaseous isotopes D₂ and T₂ are of vital importance, in particular for high-specific-activity tritiation of pharmaceuticals. As part of our interest in exploring s-block metals for catalytic transformations, we found CsN(SiMe₃ )₂ to be an efficient catalyst for selective HIE of benzylic C-H bonds with D₂ gas. The reaction proceeds through a kinetic deprotonative equilibrium that establishes an exchange pathway between C-H bonds and D₂ gas. By virtue of multiple C-H bonds activation and high activity (isotope enrichment up to 99 %), the simple cesium amide catalyst provided a very powerful and practically convenient labeling protocol for synthesis of highly deuterated compounds and high-specific-activity tritiation of pharmaceuticals.

Organoboron Reagent-Controlled Selective (Deutero)Hydrodefluorination

(Deuterium-labeled) CF₂ H- and CFH₂ -moieties are of high interest in drug discovery. The high demand for the incorporation of these fluoroalkyl moieties into molecular structures has witnessed significant synthetic progress, particularly in the (deutero)hydrodefluorination of CF₃ -containing compounds. However, the controllable replacement of fluorine atoms while maintaining high chemoselectivity remains challenging. Herein, we describe the development of a selective (deutero)hydrodefluorination reaction via electrolysis. The reaction exhibits a remarkable chemoselectivity control, which is enabled by the addition of different organoboron sources. The procedure is operationally simple and scalable, and provides access in one step to high-value building blocks for application in medicinal chemistry. Furthermore, density functional theory (DFT) calculations have been carried out to investigate the reaction mechanism and to rationalize the chemoselectivity observed.

[13 C+D] Double Labeling with Calcium Carbide: Incorporation of Two Labels in One Step

D-labeling is a valuable tool in advanced synthetic chemistry and pharmacy. However, D-incorporation significantly complicates the identification of products. In fact, D labels are invisible in ¹ H-NMR spectra and cause undesirable splitting in ¹³ C-NMR spectra which decreases the detectable limits. At the same time, ² H-NMR spectra are not effective for precise identification due to low sensitivity and the absence of correlations with ¹ H atoms. Here, ¹³ C-label was considered as an accompanying label for D-label in [¹³ C+D] unit for identification of D-containing sites and to track D-labels. [¹³ C+D]-doubly labeled vinyl derivatives and triazoles were synthesized using ¹³ C-labeled calcium carbide as a source of ¹³ C-label and deuterium oxide as a source of D-label. The reaction occurred in one-step manner accompanied with in situ doubly labeled acetylene formation. Non-labeled, mono-labeled and doubly labeled substrates were isolated in 25-80% yields.

Photocatalytic Deuterium Atom Transfer Deuteration of Electron-Deficient Alkenes with High Functional Group Tolerance

Due to its mild reaction conditions and unique chemoselectivity, hydrogen atom transfer (HAT) hydrogenation represents an indispensable method for the synthesis of complex molecules. Its analog using deuterium, deuterium atom transfer (DAT) deuteration, is expected to enable access to complex deuterium-labeled compounds. However, DAT deuteration has been scarcely studied for synthetic purposes, and a method that possesses the favorable characteristics of HAT hydrogenations has remained elusive. Herein, we report a protocol for the photocatalytic DAT deuteration of electron-deficient alkenes. In contrast to the previous DAT deuteration, this method tolerates a variety of synthetically useful functional groups including haloarenes. The late-stage deuteration also allows access to deuterated amino acids as well as donepezil-d₂ . Thus, this work demonstrates the potential of DAT chemistry to become the alternative method of choice for preparing deuterium-containing molecules.

Reductive Deuteration of Acyl Chlorides for the Synthesis of α,α-Dideuterio Alcohols Using SmI2 and D2O

The synthesis of α,α-dideuterio alcohols has been achieved via single electron transfer reductive deuteration of acyl chlorides using SmI₂ and D₂O. This method is distinguished by its remarkable functional group tolerance and exquisite deuterium incorporation, which has also been applied to the synthesis of valuable deuterated agrochemicals and their building blocks.

Atom-economical synthesis of 1,2-bis(phosphine oxide)ethanes from calcium carbide with straightforward access to deuterium- and 13C-labeled bidentate phosphorus ligands and metal complexes

Straightforward access to bidentate phosphorus ligands and bis(phosphineoxide)ethanes is described based on atom-economic addition reaction. A practical approach was developed to incorporate 2H and 13C labels using easily available reagents.

Sequential Iron-Catalyzed C(sp2)-C(sp3) Cross-Coupling of Chlorobenzamides/Chemoselective Amide Reduction and Reductive Deuteration to Benzylic Alcohols

Benzylic alcohols are among the most important intermediates in organic synthesis. Recently, the use of abundant metals has attracted significant attention due to the issues with the scarcity of platinum group metals. Herein, we report a sequential method for the synthesis of benzylic alcohols by a merger of iron catalyzed cross-coupling and highly chemoselective reduction of benzamides promoted by sodium dispersion in the presence of alcoholic donors. The method has been further extended to the synthesis of deuterated benzylic alcohols. The iron-catalyzed Kumada cross-coupling exploits the high stability of benzamide bonds, enabling challenging C(sp²)-C(sp³) cross-coupling with alkyl Grignard reagents that are prone to dimerization and β-hydride elimination. The subsequent sodium dispersion promoted reduction of carboxamides proceeds with full chemoselectivity for the C-N bond cleavage of the carbinolamine intermediate. The method provides access to valuable benzylic alcohols, including deuterium-labelled benzylic alcohols, which are widely used as synthetic intermediates and pharmacokinetic probes in organic synthesis and medicinal chemistry. The combination of two benign metals by complementary reaction mechanisms enables to exploit underexplored avenues for organic synthesis.

Deuterated Drugs and Biomarkers in the COVID-19 Pandemic

Coronavirus disease 2019 (COVID-19) is a highly contagious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Initially identified in Wuhan (China) in December 2019, COVID-19 rapidly spread globally, resulting in the COVID-19 pandemic. Carriers of the SARS-CoV-2 can experience symptoms ranging from mild to severe (or no symptoms whatsoever). Although vaccination provides extra immunity toward SARS-CoV-2, there has been an urgent need to develop treatments for COVID-19 to alleviate symptoms for carriers of the disease. In seeking a potential treatment, deuterated compounds have played a critical role either as therapeutic agents or as internal MS standards for studying the pharmacological properties of new drugs by quantifying the parent compounds and metabolites. We have identified >70 examples of deuterium-labeled compounds associated with treatment of COVID-19. Of these, we found 9 repurposed drugs and >20 novel drugs studied for potential therapeutic roles along with a total of 38 compounds (drugs, biomarkers, and lipids) explored as internal mass spectrometry standards. This review details the synthetic pathways and modes of action of these compounds (if known), and a brief analysis of each study.

Catalytic Vilsmeier-Haack Reactions for C1-Deuterated Formylation of Indoles

The Vilsmeier-Haack reaction is a powerful tool to introduce formyl groups into electron-rich arenes, but its wide application is significantly restricted by stoichiometric employment of caustic POCl₃. Herein, we reported a catalytic version of the Vilsmeier-Haack reaction enabled by a P(III)/P(V)═O cycle. This catalytic reaction provides a facile and efficient route for the direct construction of C1-deuterated indol-3-carboxaldehyde under mild conditions with stoichiometric DMF-d7 as the deuterium source. The products feature a remarkably higher deuteration level (>99%) than previously reported ones and are not contaminated by the likely unselective deuteration at other sites. The present transformation can also be used to transfer other carbonyl groups. Further downstream derivatizations of these deuterated products manifested their potential applications in the synthesis of deuterated bioactive molecules. Mechanistic insight was disclosed from studies of kinetics and intermediates.

Hyperglycemia and cancer in human lung carcinoma by means of Raman spectroscopy and imaging

Raman spectroscopy and Raman imaging were used to identify the biochemical and structural features of human cancer lung cells (CCL-185) and the cancer cells supplemented with glucose and deuterated glucose at normal and hyperglycemia conditions. We found that isotope substitution of glucose by deuterated glucose allows to separate de novo lipid synthesis from exogenous uptake of lipids obtained from the diet. We demonstrated that glucose is largely utilized for de novo lipid synthesis. Our results provide a direct evidence that high level of glucose decreases the metabolism via oxidative phosphorylation in mitochondria in cancer cells and shifts the metabolism to glycolysis via Warburg effect. It suggests that hyperglycemia is a factor that may contribute to a more malignant phenotype of cancer cells by inhibition of oxidative phosphorylation and apoptosis.

Rhodium(I)-catalyzed directed trideuteromethylation of (hetero)arene C-H bonds with CD3CO2D

A Rh(I)-catalyzed trideuteromethylation of heteroarenes with inexpensive and readily available deuterated acetic acid (CD₃CO₂D) with the aid of a N-containing directing groups is developed. The oxidant-free reaction is applicable to a wide range of heteroarene substrates, including 2-pyridones, indoles, aryl rings, pyrroles and carbazoles. It allows installation of CD₃ groups under straightforward reaction conditions. It is expected that the salient and practical features of this trideuteromethylation protocol will be of use to academic and industrial researchers.