Photoredox-Mediated Deoxygenative Alkylation of DNA-Tagged Alkenes with Activated Alcohols

Alcohol Activation by Benzodithiolylium for Deoxygenative Alkylation Driven by Photocatalytic Energy Transfer

The 1,3-benzodithiolylium (BDT) cation was identified as an efficient hydroxyl-activating reagent for the photocatalytic deoxygenative radical functionalization of alcohols in the absence of any electron transfer process. A series of unprecedented photocatalytic energy transfer (EnT)-driven deoxygenative radical coupling reactions of alcohols with bifunctional oxime carbonates have been developed based on the activation by BDT. Nickel-catalyzed radical sorting followed by C(sp3)─C(sp3) bond construction facilitates the heteroselective cross-coupling of two distinct alkyl radicals originating from parallel radical relays. These reactions allow the versatile synthesis of diverse nitrogen-containing molecules, including amino acid derivatives, imines, nitriles, and pyrrolines, by using ubiquitous alcohols as regiodefined alkyl building blocks.

Visible-light-induced radical-cascade alkylation/cyclization of acrylamides: access to 3,3-dialkylated oxindoles

A visible-light-induced deoxygenative alkylation/cyclization of acrylamides with alcohols activated by CS2 has been developed by using xanthate salts as alkyl radical precursors in the presence of tricyclohexylphosphine. It proceeds through a tandem radical addition/cyclization process, and this protocol provides a reliable and practical approach to building the skeleton of 3,3-disubstituted oxindoles in moderate to good yields. Notable features of this reaction include readily available starting reagents, broad substrate scope and mild reaction conditions.

Oxoammonium Salt-Mediated On-DNA Alcohol Oxidation for DEL Synthesis

On-DNA carboxylic acids are important synthetic intermediates in the synthesis of DNA-encoded library (DEL) structures. Herein, we report an oxoammonium salt-mediated, room temperature, solution-phase oxidation of DNA-linked primary alcohols into carboxylic acids. This method exhibits a wide substrate scope, encompassing aliphatic, benzylic, and heterobenzylic alcohols, and is compatible with DEL encoding strategies. This advancement facilitates a DEL strategy to utilize unprotected alcohols as inert, masked carboxylic acids and enables access to noncommercial bifunctional carboxyl intermediates to enhance the accessible chemical diversity within DELs.

Hydrophobic Surfactant-DNA Complex (Surf-DNA) Enables DNA-Encoded-Library-Compatible Decarboxylative Arylation under Anhydrous Conditions

DNA-encoded libraries (DELs) are a key technology for identifying small-molecule hits in both the pharmaceutical industry and academia, but their chemical diversity is largely limited to water-compatible reactions to aid in the solubility and integrity of encoding DNA tags. To broaden the DEL chemical space, we present a workflow utilizing DNA-cationic surfactant complexation that enables dissolution and reactions on-DNA in anhydrous organic solvents. We demonstrate its utility by developing DEL-compatible photoredox decarboxylative C(sp2)-C(sp3) coupling under water-free conditions. The workflow is optimized for the 96-well format necessary for large-scale DEL productions, and it enables screening and optimization of DEL-compatible reactions in organic solvents.

Visible-Light-Promoted Deoxygenative Alkylation of Quinoxalin-2(1H)-ones with Activated Alcohols

A one-pot strategy for deoxygenative alkylation of alcohols with quinoxalin-2(1H)-ones was developed by using xanthate salts as alcohol-activating groups for radical generation in the presence of tricyclohexylphosphine under visible-light-promoted conditions. The remarkable features of this reaction include a broad substrate scope, excellent functional group tolerance, mild conditions, and simple operation. Moreover, the synthetic utility of this reaction was validated by the success of two-step one-pot reactions, scale-up synthesis, and chemoselective radical monodeoxygenation of diols.

Evolution of chemistry and selection technology for DNA-encoded library

DNA-encoded chemical library (DEL) links the power of amplifiable genetics and the non-self-replicating chemical phenotypes, generating a diverse chemical world. In analogy with the biological world, the DEL world can evolve by using a chemical central dogma, wherein DNA replicates using the PCR reactions to amplify the genetic codes, DNA sequencing transcripts the genetic information, and DNA-compatible synthesis translates into chemical phenotypes. Importantly, DNA-compatible synthesis is the key to expanding the DEL chemical space. Besides, the evolution-driven selection system pushes the chemicals to evolve under the selective pressure, i.e., desired selection strategies. In this perspective, we summarized recent advances in expanding DEL synthetic toolbox and panning strategies, which will shed light on the drug discovery harnessing in vitro evolution of chemicals via DEL.

Synthesis of Functionalized Triazoles on DNA via Azide-Acetonitrile "Click" Reaction

Triazoles are privileged structural motifs that are embedded in a number of molecules with interesting biological activities. In this work, we developed a practical and general synthetic strategy to construct a medicinally important 5-amino-1,2,3-triazole moiety on DNA by coupling DNA-conjugated azides and monosubstituted acetonitriles via azide-acetonitrile "click" reaction. Under mild reaction conditions, this reaction displayed a broad substrate scope. Most substrates gave moderate-to-excellent conversions. Thus, this DNA-compatible reaction could be employed in practical DNA-encoded library (DEL) construction and potentially expand the chemical space of DNA-encoded libraries.

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.