Kevin D. Hesp

Expedient synthesis of N-acyl anthranilamides and β-enamine amides by the Rh(III)-catalyzed amidation of aryl and vinyl C-H bonds with isocyanates.

A Rh(III)-catalyzed protocol for the amidation of anilide and enamide C-H bonds with isocyanates has been developed. This method provides direct and efficient syntheses of N-acyl anthranilamides, enamine amides, and pyrimidin-4-one heterocycles.

Rhodium(III)‐Catalyzed Alkenyl CH Bond Functionalization: Convergent Synthesis of Furans and Pyrroles

Ring in the new: a new annulation for the efficient synthesis of substituted furans and pyrroles is reported. The Rh(III) -catalyzed reaction of O-methyl α,β-unsaturated oximes with aldehydes and N-tosyl imines affords secondary alcohol and amine intermediates, respectively. Cyclization and aromatization occurs under the reaction conditions to provide access to biologically relevant furans and pyrroles in good yields. Cp*=C(5)Me(5), DCE=1,2-dichloroethane, THF=tetrahydrofuran.

Palladium-Catalyzed Synthesis of (Hetero)Aryl Alkyl Sulfones from (Hetero)Aryl Boronic Acids, Unactivated Alkyl Halides, and Potassium Metabisulfite

A palladium-catalyzed one-step synthesis of (hetero)aryl alkyl sulfones from (hetero)arylboronic acids, potassium metabisulfite, and unactivated or activated alkylhalides is described. This transformation is of broad scope, occurs under mild conditions, and employs readily available reactants. A stoichiometric experiment has led to the isolation of a catalytically active dimeric palladium sulfinate complex, which was characterized by X-ray diffraction analysis.

Rhodium-Catalyzed Synthesis of Branched Amines by Direct Addition of Benzamides to Imines

Rhodium-catalyzed addition of benzamide C-H bonds to a range of aromatic N-sulfonyl aldimines has been developed and proceeds with high functional group compatibility. The synthetic utility of the resulting branched amine products has also been demonstrated by the preparation of isoindoline and isoindolinone frameworks.

Fluorodecarboxylation for the Synthesis of Trifluoromethyl Aryl Ethers

The synthesis of mono-, di-, and trifluoromethyl aryl ethers by fluorodecarboxylation of the corresponding carboxylic acids is reported. AgF2 induces decarboxylation of aryloxydifluoroacetic acids, and AgF, either generated in situ or added separately, serves as a source of fluorine to generate the fluorodecarboxylation products. The addition of 2,6-difluoropyridine increased the reactivity of AgF2 , thereby increasing the range of functional groups and electronic properties of the aryl groups that are tolerated. The reaction conditions used for the formation of trifluoromethyl aryl ethers also served to form difluoromethyl and monofluoromethyl aryl ethers.

Expedient Synthesis of α-(2-Azaheteroaryl) Acetates via the Addition of Silyl Ketene Acetals to Azine-N-oxides

A new and expedient synthesis of α-(2-azaheteroaryl) acetates is presented. The reaction proceeds rapidly under mild conditions via the addition of silyl ketene acetals to azine-N-oxides in the presence of the phosphonium salt PyBroP. This procedure affords diverse α-(2-azaheteroaryl) acetates which are highly desirable components/building blocks in molecules of pharmaceutical interest but are traditionally challenging to synthesize via contemporary methods. The reaction optimization and mechanism as well as a novel electronically enhanced PyBroP derivative are described.

Expedient Synthesis of α-Heteroaryl Piperidines Using a Pd-Catalyzed Suzuki Cross-Coupling–Reduction Sequence

A method for the modular synthesis of α-heteroaryl piperidines is reported. The two-step procedure consists of an initial Pd-catalyzed Suzuki cross-coupling of the heteroaryl bromide with a boronate ester derived from N-Boc piperidone, followed by subsequent tetrahydropyridine reduction. Using this method, α-heteroaryl piperidine products featuring a broad range of pharmaceutically relevant azine and diazine substitutions have been prepared.

Copper-Catalyzed Regio- and Enantioselective Hydroamination of Alkenes with Hydroxylamines

Adding value: The catalytic hydroamination of alkenes with amines holds promise to rapidly deliver value-added chiral amines from simple and accessible starting materials. The use of mild, Cu-catalyzed electrophilic amination strategies for the regioselective preparation of both linear and chiral branched amines is highlighted.

Base-Controlled Completely Selective Linear or Branched Rhodium(I)-Catalyzed C−H ortho-Alkylation of Azines without Preactivation

A [RhI ]/bisphosphine/base catalytic system for the ortho-selective C-H alkylation of azines by acrylates and acrylamides is reported. This catalytic system features an unprecedented complete linear or branched selectivity that is solely dependent on the catalytic base that is used. Complete branched selectivity is even achieved for ethyl methacrylate, which enables the introduction of a quaternary carbon center. Excellent functional group compatibility is demonstrated for both linear and branched alkylations. The operational simplicity and broad scope of this transformation allow for rapid access to functionalized azines of direct pharmaceutical and agrochemical relevance.

Receptor-Mediated Delivery of CRISPR-Cas9 Endonuclease for Cell-Type-Specific Gene Editing

CRISPR-Cas RNA-guided endonucleases hold great promise for disrupting or correcting genomic sequences through site-specific DNA cleavage and repair. However, the lack of methods for cell- and tissue-selective delivery currently limits both research and clinical uses of these enzymes. We report the design and in vitro evaluation of S. pyogenes Cas9 proteins harboring asialoglycoprotein receptor ligands (ASGPrL). In particular, we demonstrate that the resulting ribonucleoproteins (Cas9-ASGPrL RNP) can be engineered to be preferentially internalized into cells expressing the corresponding receptor on their surface. Uptake of such fluorescently labeled proteins in liver-derived cell lines HEPG2 (ASGPr+) and SKHEP (control; diminished ASGPr) was studied by live cell imaging and demonstrates increased accumulation of Cas9-ASGPrL RNP in HEPG2 cells as a result of effective ASGPr-mediated endocytosis. When uptake occurred in the presence of a peptide with endosomolytic properties, we observed receptor-facilitated and cell-type specific gene editing that did not rely on electroporation or the use of transfection reagents. Overall, these in vitro results validate the receptor-mediated delivery of genome-editing enzymes as an approach for cell-selective gene editing and provide a framework for future potential applications to hepatoselective gene editing in vivo.