RESUMEN
Alkenes, ethers, and alcohols account for a significant percentage of bulk reagents available to the chemistry community. The petrochemical, pharmaceutical, and agrochemical industries each consume gigagrams of these materials as fuels and solvents each year. However, the utilization of such materials as building blocks for the construction of complex small molecules is limited by the necessity of prefunctionalization to achieve chemoselective reactivity. Herein, we report the implementation of efficient, sustainable, diaryl ketone hydrogen-atom transfer (HAT) catalysis to activate native C-H bonds for multicomponent dicarbofunctionalization of alkenes. The ability to forge new carbon-carbon bonds between reagents typically viewed as commodity solvents provides a new, more atom-economic outlook for organic synthesis. Through detailed experimental and computational investigation, the critical effect of hydrogen bonding on the reactivity of this transformation was uncovered.
Asunto(s)
Alquenos/química , Níquel/química , Alquenos/síntesis química , Carbono/química , Catálisis , Hidrógeno/química , Enlace de Hidrógeno , Teoría CuánticaRESUMEN
The installation of gem-difluoromethylene groups into organic structures remains a daunting synthetic challenge despite their attractive structural, physical, and biochemical properties. A very efficient retrosynthetic approach would be the functionalization of a single C-F bond from a trifluoromethyl group. Recent advances in this line of attack have enabled the C-F activation of trifluoromethylarenes, but limit the accessible motifs to only benzylic gem-difluorinated scaffolds. In contrast, the C-F activation of trifluoroacetates would enable their use as a bifunctional gem-difluoromethylene synthon. Herein, we report a photochemically mediated method for the defluorinative alkylation of a commodity feedstock: ethyl trifluoroacetate. A novel mechanistic approach was identified using our previously developed diaryl ketone HAT catalyst to enable the hydroalkylation of a diverse suite of alkenes. Furthermore, electrochemical studies revealed that more challenging radical precursors, namely trifluoroacetamides, could also be functionalized via synergistic Lewis acid/photochemical activation. Finally, this method enabled a concise synthetic approach to novel gem-difluoro analogs of FDA-approved pharmaceutical compounds.
Asunto(s)
Acetamidas/química , Ésteres/síntesis química , Fluoroacetatos/química , Alquenos/química , Alquilación , Catálisis/efectos de la radiación , Cetonas/química , Cetonas/efectos de la radiación , Estructura MolecularRESUMEN
Photoredox-mediated radical/polar crossover (RPC) processes provide unique solutions to challenging annulations. Herein, we describe an approach to the cyclopropanation of olefins that are embedded within bicyclic scaffolds. Whereas these systems are notoriously recalcitrant toward classical cyclopropanation approaches, RPC cyclopropanation can be executed with ease, leading to polycarbocyclic and polyheterocyclic cyclopropanes. The cyclopropanation proceeds through a photoredox-enabled Giese-type radical addition followed by an intramolecular anionic substitution reaction on a neopentyl leaving group.
RESUMEN
Mesenchymal-epithelial transition factor (MET) is a receptor tyrosine kinase that serves a critical function in numerous developmental, morphogenic, and proliferative signaling pathways. If dysregulated, MET has been shown to be involved in the development and survival of several cancers, including non-small cell lung cancer (NSCLC), renal cancer, and other epithelial tumors. Currently, the clinical efficacy of FDA approved MET inhibitors is limited by on-target acquired resistance, dose-limiting toxicities, and less than optimal efficacy against brain metastasis. Therefore, there is still an unmet medical need for the development of MET inhibitors to address these issues. Herein we report the application of structure-based design for the discovery and development of a novel class of brain-penetrant MET inhibitors with enhanced activity against clinically relevant mutations and improved selectivity. Compound 13 with a MET D1228N cell line IC50 value of 23 nM showed good efficacy in an intracranial tumor model and increased the median overall survival of the animals to 100% when dosed orally at 100 mg/kg daily for 21 days.
Asunto(s)
Antineoplásicos , Inhibidores de Proteínas Quinasas , Proteínas Proto-Oncogénicas c-met , Pirazoles , Proteínas Proto-Oncogénicas c-met/antagonistas & inhibidores , Proteínas Proto-Oncogénicas c-met/metabolismo , Humanos , Animales , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/uso terapéutico , Pirazoles/farmacología , Pirazoles/química , Pirazoles/síntesis química , Línea Celular Tumoral , Relación Estructura-Actividad , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis química , Antineoplásicos/uso terapéutico , Descubrimiento de Drogas , Pirazinas/farmacología , Pirazinas/síntesis química , Pirazinas/química , Pirazinas/uso terapéutico , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/patología , Ratones , Mutación , RatasRESUMEN
The use of bicyclo[1.1.1]pentanes (BCPs) as para-disubstituted aryl bioisosteres has gained considerable momentum in drug development programs. Carbon-carbon bond formation via transition-metal-mediated cross-coupling represents an attractive strategy to generate BCP-aryl compounds for late-stage functionalization, but these typically require reactive organometallics to prepare BCP nucleophiles on demand from [1.1.1]propellane. In this study, the synthesis and Ni-catalyzed functionalization of BCP redox-active esters with (hetero)aryl bromides via the action of a photoactive electron donor-acceptor complex are reported.
Asunto(s)
Carbono/química , Níquel/química , Catálisis , Electrones , Ésteres , Estructura Molecular , Oxidantes , Oxidación-ReducciónRESUMEN
An annulation process for the construction of 1,1-disubstituted cyclopropanes via a radical/polar crossover process is described. The cyclopropanation proceeds by the addition of a photocatalytically generated radical to a homoallylic tosylate. Reduction of the intermediate radical alkylation adduct (via single electron transfer) furnishes an anion that undergoes an intramolecular substitution. The process displays excellent functional group tolerance, characteristic of proceeding through odd-electron intermediates, and occurs under mild conditions with visible light irradiation.