The atom-efficient and environmentally benign catalytic hydrogenation of carboxylic acid esters to alcohols has been accomplished in recent years mainly with precious-metal-based catalysts, with few exceptions. Presented here is the first cobalt-catalyzed hydrogenation of esters to the corresponding alcohols. Unexpectedly, the evidence indicates the unprecedented involvement of ester enolate intermediates.
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http://dx.doi.org/10.1002/anie.201502418 | DOI Listing |
J Am Chem Soc
January 2025
Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States.
Monoanionic, bidentate-auxiliary-directed, cobalt-catalyzed C-H bond functionalization has become a very useful tool in organic synthesis. A comprehensive investigation into isolated organometallic intermediates and their reactivity within the catalytic cycle is lacking. We report here mechanistic studies of cobalt-catalyzed, aminoquinoline-directed C(sp)-H bond functionalization.
View Article and Find Full Text PDFOrg Lett
January 2025
The Institute for Advanced Studies, Wuhan University, Wuhan, Hubei Province, People's Republic of China 430072.
Herein we describe a dual photo/cobalt-catalyzed anti-Markovnikov hydroacylation of aryl alkenes using aldehyde as acyl source. The key to success is the cobalt catalyzed hydrogen atom transfer, which enables effective formation of the desired products and efficient regeneration of the photocatalyst under mild conditions. This protocol features broad substrate scopes, good functional group tolerance, high efficiency and regioselectivity.
View Article and Find Full Text PDFOrg Lett
October 2024
Jiangsu Key Laboratory of Neuropsychiatric Diseases and Department of Medicinal Chemistry, College of Pharmaceutical Sciences, Soochow University, 199 Ren-Ai Road, Suzhou, Jiangsu 215123, China.
Cobalt-catalyzed enantioconvergent cross-coupling of C(sp)-H bonds with -generated sulfenate anions is achieved to access chiral sulfoxides, which are found in the structures of many biologically active agents. The more challenging aliphatic C-H bonds as well as sterically hindered substrates containing tertiary C-H bonds could also be tolerated well. Mechanistic studies indicate that the transformation could undergo a CoS(O)R-mediated single-electron transfer with -fluorocarboxamides, followed by a 1,5-hydrogen atom transfer and then a pivotal organocobalt(IV)-controlled enantioselective cross-coupling process.
View Article and Find Full Text PDFJ Org Chem
October 2024
Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati 517507, India.
Sustainable chemical production demands the creation of innovative catalysts and catalytic technologies. While the development of coherent and robust catalytic systems using earth-abundant transition metals is essential, it remains a significant challenge. Herein, an expedient divergence strategy for tandem dehydrogenative C(sp)-H alkylation and cyclization reactions of 9-fluorene using a newly developed ,-bidentate cobalt catalytic system is developed.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK.
A highly enantioselective cobalt-catalyzed semipinacol rearrangement of symmetric α,α-diarylallylic alcohols is disclosed. A chiral cobalt-salen catalyst generates a highly electrophilic carbocation surrogate following hydrogen atom transfer and radical-polar crossover steps. This methodology provides access to enantioenriched α-aryl ketones through invertive displacement of a cobalt(IV) complex during 1,2-aryl migration.
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