Tandem H/D Exchange-SET Reductive Deuteration Strategy for the Synthesis of α,β-Deuterated Amines Using D2O

Deuteration-Based Design, Green Synthesis, and Insecticidal Activity of Hexacyclic Pyrazol-3-amide Derivatives as Insect Growth Regulators

The deuterium kinetic isotope effect (DKIE) underscores the stability of C-D bond, which can improve pharmacokinetic properties and reduce toxicity in compounds. Herein, the application of the deuteration strategy to improve the activity of insect growth regulators (IGRs) by replacing the C-H bond with a C-D bond at the benzylic position, known as the "soft spot", is first investigated. The corresponding deuterated intermediates were obtained through a novel green and efficient method utilizing samarium diiodide (SmI2) as a reductive deuterating agent and 2-methyltetrahydrofuran (2-MTHF) as a solvent to address environmental concerns. Subsequently, six deuterated compounds (D-1 to D-6) of hexacyclic pyrazol-3-amide derivatives are synthesized and compared in terms of insecticidal activity against Plutella xylostella, revealing lower LC50 values than nondeuterated compounds (H-1 to H-6). Particularly, compound D-3 exhibited significantly better activity (LC50: 11 mg/L) than H-3 (LC50: 197 mg/L), even higher than commercial tebufenozide. Additionally, the inhibitory activities against ecdysone receptor/ultraspiracle protein (EcR/USP) and three chitinases─OfChtI, OfChtII, and OfChi-h─demonstrate that deuteration enhances binding affinity specifically to the Chitinase OfChtI. After deuteration, the compounds exhibited a lower ClogP value and reduced energy gap, along with a slight reduction in lipophilicity and electrostatic potential, which together may contribute to improved activity. This work suggests that deuteration strategy is a promising approach to improve the compounds' efficacy for pest control.

Synthesis of Selectively 13C/2H/15N- Labeled Arginine to Probe Protein Conformation and Interaction by NMR Spectroscopy

The charged arginine side chain is unique in determining many innate properties of proteins, contributing to stability and interaction surfaces, and directing allosteric regulation and enzymatic catalysis. NMR experiments can be used to reveal these processes at the molecular level, but it often requires selective insertion of carbon-13, nitrogen-15, and deuterium at defined atomic positions. We introduce a method to endow arginine residues with defined isotope patterns, combining synthetic organic chemistry and cell-based protein overexpression. The resulting proteins feature NMR active spin systems with optimized relaxation pathways leading to simplified NMR spectra with a sensitive response to changes in the chemical environment of the nuclei observed.

Samarium Diiodide/Samarium-Mediated Deoxygenative Hydrosilylation of Ketones

The first deoxygenative hydrosilylation of ketones promoted by samarium diiodide and samarium has been reported. In this approach, secondary alkyl silanes are synthesized from unactivated ketones and chlorosilanes in one step. The carbonyl group of ketones is activated by SmI2-mediated single-electron transfer process, which follows a deoxygenative elimination of O=Sm. Broad substrate scope and excellent functional group tolerance has been demonstrated.

Organophotocatalytic α-deuteration of unprotected primary amines via H/D exchange with D2O

We report a straightforward H/D exchange method for the synthesis of α-deuterated primary amines from a diverse set of primary amines with high levels of deuteration and chemo- and site selectivity and preparative utility. This cost-effective strategy enables the direct conversion of primary amines to α-deuterated counterparts using D2O as the deuterium source under mild reaction conditions without requiring additional functionality manipulation and with minimal byproduct production.

Remote Radical 1,3-, 1,4-, 1,5-, 1,6- and 1,7-Difunctionalization Reactions

Radical transformations are powerful in organic synthesis for the construction of molecular scaffolds and introduction of functional groups. In radical difunctionalization reactions, the radicals in the first functionalized intermediates can be relocated through resonance, hydrogen atom or group transfer, and ring opening. The resulting radical intermediates can undertake the following paths for the second functionalization: (1) couple with other radical groups, (2) oxidize to cations and then react with nucleophiles, (3) reduce to anions and then react with electrophiles, (4) couple with metal-complexes. The rearrangements of radicals provide the opportunity for the synthesis of 1,3-, 1,4-, 1,5-, 1,6-, and 1,7-difunctionalization products. Multiple ways to initiate the radical reaction coupling with intermediate radical rearrangements make the radical reactions good for difunctionalization at the remote positions. These reactions offer the advantages of synthetic efficiency, operation simplicity, and product diversity.

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.

One-pot H/D exchange and low-coordinated iron electrocatalyzed deuteration of nitriles in D2O to α,β-deuterio aryl ethylamines

Developing a step-economical approach for efficient synthesis of α,β-deuterio aryl ethylamines (α,β-DAEAs) with high deuterium ratios using an easy-to-handle deuterated source under ambient conditions is highly desirable. Here we report a room-temperature one-pot two-step transformation of aryl acetonitriles to α,β-DAEAs with up to 92% isolated yield and 99% α,β-deuterium ratios using D2O as a deuterium source. The process involves a fast α-C - H/C - D exchange and tandem electroreductive deuteration of C ≡ N over an in situ formed low-coordinated Fe nanoparticle cathode. The moderate adsorptions of nitriles/imine intermediates and the promoted formation of active hydrogen (H*) on unsaturated Fe sites facilitate the electroreduction process. In situ Raman confirms co-adsorption of aryl rings and the C ≡ N group on the Fe surface. A proposed H*-addition pathway is confirmed by the detected hydrogen and carbon radicals. Wide substrate scope, parallel synthesis of multiple α,β-DAEAs, and successful preparation of α,β-deuterated Melatonin and Komavine highlight the potential.

One-Pot Sequential Hydrogen Isotope Exchange/Reductive Deuteration for the Preparation of α,β-Deuterated Alcohols using Deuterium Oxide

An efficient one-pot sequential hydrogen isotope exchange (HIE)/reductive deuteration approach was developed for the preparation of α,β-deuterated alcohols using ketones as the precursors. The HIE step can also be used for the synthesis of α-deuterated ketones. This method has been applied in the synthesis of four deuterated drug and MS internal standards.

Current Electrochemical Approaches to Selective Deuteration

The selective deuteration of organic molecules through electrochemistry is proving to be an effective alternative to conventional 2H labelling strategies, which traditionally require high temperatures, high pressures of deuterium gas...