Cobalt(II)-catalyzed C(sp(2) )O cross-coupling between aryl/heteroaryl alcohols and vinyl/aryl halides in the presence of Cu(I) has been achieved under ligand-free conditions. In this reaction, copper plays a significant role in transmetalation rather than being directly involved in the CO coupling. This unique Co/Cu-dual catalyst system provides an easy access to a library of aryl-vinyl, heteroaryl-styryl, aryl-aryl, and heteroaryl-heteroaryl ethers in the absence of any ligand or additive.
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http://dx.doi.org/10.1002/chem.201500058 | DOI Listing |
Angew Chem Int Ed Engl
December 2024
Center of Chemistry for Frontier Technologies, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.
Inherently chiral calixarenes have garnered significant attention due to their distinctive properties, yet the development of efficient catalytic asymmetric synthesis methods remains a critical challenge. Herein, we report the asymmetric synthesis of calix[4]arenes featuring inherent or both inherent and axial chirality via a cobalt-catalyzed C-H activation/annulation strategy in high yield with excellent enantio- and diastereoselectivity (up to >99 % ee and >20 : 1 dr). Electrooxidation was also suitable for this transformation to obviate the sacrificial metal oxidants, underscoring the environmentally friendly potential of this approach.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
May 2023
State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, 345 Lingling Road, Shanghai, China.
Catalytic enantioselective coupling of 1,1-disubstituted allenes and aldehydes through regiodivergent oxidative cyclization followed by stereoselective protonation or reductive elimination promoted by chiral phosphine-Co complexes is presented. Such processes represent unprecedented and unique reaction pathways for Co catalysis that enable catalytic enantioselective generation of metallacycles with divergent regioselectivity accurately controlled by chiral ligands, affording a wide range of allylic alcohols and homoallylic alcohols that are otherwise difficult to access without the need of pre-formation of stoichiometric amounts of alkenyl- and allyl-metal reagents in up to 92 % yield, >98 : 2 regioselectivity, >98 : 2 dr and >99.5 : 0.
View Article and Find Full Text PDFJ Org Chem
March 2023
Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.
Described here is a method for intermolecular hydroalkoxylation and hydrocarboxylation of 2-azadienes through cobalt-catalyzed hydrogen atom transfer and oxidation. This protocol provides a source of 2-azaallyl cation equivalents under mild conditions, is chemoselective in the presence of other C═C double bonds, and requires no excess amount of added alcohol or oxidant. Mechanistic studies suggest that the selectivity arises from lowering the transition state that leads to the highly stabilized 2-azaallyl radical.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
July 2022
State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, 345 Lingling Road, Shanghai, China.
One of the most straightforward approaches to access chiral silanes is catalytic enantioselective hydrosilylation. Although significant advances have been achieved in enantioselective construction of either a carbon-stereogenic center or a silicon-stereogenic center through enantioselective hydrosilylation, simultaneous establishment of a carbon- and a silicon-stereogenic center in an acyclic molecule through a single intermolecular hydrosilylation remained undeveloped. Herein, an unprecedented cobalt-catalyzed regio-, diastereo- and enantioselective hydrosilylation of 1,3-dienes is presented, enabling construction of a carbon- and a silicon-stereogenic center in a single intermolecular transformation.
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