Article
Chemistry, Organic
Bedadyuti Vedvyas Pati, Prateep Singh Sagara, Asit Ghosh, Gopal Krushna Das Adhikari, Ponneri Chandrababu Ravikumar
Summary: The study demonstrates the regioselective annulation of N-amino-7-azaindole with 1,3-diynes catalyzed by ruthenium(II). The bioactive N-amino-7-azaindole serves as a new bidentate directing group to produce a range of 3-alkynylated isoquinolones. The protocol is efficient for both aryl- and heteroaryl-substituted amides, resulting in pharmacologically useful 7-azaindole-based isoquinolones with diverse functionalities.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Lukass Lukasevics, Aleksandrs Cizikovs, Liene Grigorjeva
Summary: An efficient protocol for the C(sp(2))-H carbonylation of amino acid derivatives based on an inexpensive cobalt(II) salt catalyst is reported. The method utilizes picolinamide as a traceless directing group and Co(dpm)(2) as the catalyst, allowing for a broad range of phenylalanine derivatives bearing diverse functional groups to be tolerated. Moreover, the method can be successfully applied for the C(sp(2))-H carbonylation of short peptides, enabling access for peptide late-stage carbonylation.
Article
Chemistry, Organic
Prakriti Dhillon, Prasad Anaspure, Jesper G. Wiklander, Subban Kathiravan, Ian A. Nicholls
Summary: The regiochemical outcome of a cobalt(ii) catalysed C-H activation reaction of aminoquinoline benzamides with unsymmetrical 1,3-diynes under relatively mild reaction conditions can be controlled by the choice of diyne. The choice of diyne allows access to either 3- or 4-hydroxyalkyl isoquinolinones, facilitating the synthesis of more complex isoquinolines.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Aleksandrs Cizikovs, Lukass Lukasevics, Liene Grigorjeva
Summary: Utilizing the traceless directing group (TDG) strategy in transition metal-catalyzed C-H bond functionalization under high valent cobalt catalysis allows for selective and atom-economic construction of C-C and C-heteroatom bonds.
Review
Chemistry, Physical
Athanasios Zarkadoulas, Ioanna Zgouleta, Nikolaos V. Tzouras, Georgios C. Vougioukalakis
Summary: This review article summarizes the work done on TDG-assisted catalysis with manganese, iron, cobalt, nickel, or copper catalysts, and discusses the structure-activity relationships observed, by presenting the catalytic pathways and range of transformations reported thus far.
Article
Chemistry, Organic
Bubul Das, Anjali Dahiya, Ashish Kumar Sahoo, Bhisma K. Patel
Summary: The isocyanate group in aryl isocyanates acts as a transformable transient directing group, leading to the ortho olefination reaction and the formation of o-alkenylanilines. In alcoholic solvents, aryl isocyanates are converted into carbamates, initiating the insertion of acrylates via ortho C-H activation. Specifically, tAmOH serves as both a solvent and a transient directing mediator. The o-alkenylanilines are further transformed into azacoumarins and C-4 aryl-substituted azacoumarins through Pd(II)-catalyzed C-H functionalizations using aryl iodides as coupling partners.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Jakub Brzeskiewicz, Rafal Loska
Summary: The palladium-catalyzed C(sp2)-H functionalization of bromoaryl aldonitrones leading to benzocyclobutenone-derived ketonitrones is described, allowing for the preparation of a wide range of strained, four-membered ketonitrones with broad functional group tolerance. Downstream transformations of the formed products were demonstrated, illustrating the synthetic utility of the obtained benzocyclobutenone-derived nitrones for the construction of polycyclic nitrogen-containing scaffolds.
Review
Chemistry, Organic
Jinhwan Park, Jongwoo Son
Summary: Metal-catalyzed C-sp2-H oxygenation is an important synthetic transformation that allows the incorporation of useful functional groups using a simple protocol. Cobalt catalysis, as a sustainable alternative, has gained attention due to its natural abundance and cost-effectiveness. In this Review, recent advances in cobalt-catalyzed C-sp2-H alkoxylation and acetoxylation are highlighted, along with discussions on various directing groups.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Suresh Kumar Yadav, Balu Ramesh, Masilamani Jeganmohan
Summary: This study describes an air-stable, highly abundant, and cost-effective Co(III)-catalyzed redox-neutral [4 + 2] annulation reaction of aromatic sulfoxonium ylides with 1,3-diynes, resulting in the synthesis of useful substituted 1-naphthol derivatives in a regioselective manner. Furthermore, the prepared 1-naphthols with internal alkynes were converted into polycarbocyclic molecules and spiro-dienone derivatives with high yields. A possible reaction mechanism involving ortho C-H activation as a key step was proposed and supported by deuterium labeling and kinetic isotope labeling studies.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Jian Wei, Xiaoru Shao, Hua Zhao, Hongjian Yang, Shuxian Qiu, Hongbin Zhai
Summary: A palladium-catalyzed ortho C-H arylation reaction with MHP as the directing group has been investigated, generating biaryl derivatives in an environmentally friendly manner and tolerating a wide range of functional groups. The directing group in the product can be easily removed under mild reductive conditions.
Article
Chemistry, Multidisciplinary
Yan-Zhen Chen, Jian-Guo Fu, Xiao-Ming Ji, Shu-Sheng Zhang, Chen-Guo Feng
Summary: A new method for traceless directing cross-coupling of unreactive C(sp(3))-H bonds and azole C(sp(2))-H bonds has been described. The success of this cascade process relies on the careful selection of a bulky and electron-rich phosphine ligand, and it offers broad substrate scope, excellent regioselectivity, and good functional group tolerance.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Lukass Lukasevics, Aleksandrs Cizikovs, Liene Grigorjeva
Summary: In this study, we reported a cobalt-catalyzed C-H arylation method using picolinamide as a directing group for phenylalanine derivatives. The reaction displayed good tolerance towards various functional groups and exhibited high yields. The obtained imine products can be easily transformed to 1-aminoisoquinoline derivatives under reductive conditions, providing an attractive alternative. Control experiments suggested that C-H activation might proceed via an electrophilic pathway.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Sanjeev Kumar, Saiprasad Nunewar, Tharun Kumar Sabbi, Vinaykumar Kanchupalli
Summary: Here, we report the Rh(III)-catalyzed C-H activation followed by redox-neutral [3 + 2] annulation of sulfoxonium ylides with 1,3-diynes, delivering alkynated indenone derivatives. This method shows a broad substrate scope, good functional group tolerance, and mild reaction conditions.
Review
Chemistry, Inorganic & Nuclear
Aleksandrs Cizikovs, Liene Grigorjeva
Summary: C-H bond activation and functionalization is a powerful tool for accessing various organic molecules efficiently. The cobalt-catalyzed oxidative C-H bond activation and functionalization has gained significant interest in the past two decades and various synthetic protocols for C-C, C-Het, and C-Hal bond formation reactions have been published. The authors conducted experiments and collected evidence to gain insights into the reaction mechanism, successfully isolating reactive Co(III) intermediates. This review summarizes the current knowledge regarding isolated and synthesized Co(III) intermediates in cobalt-catalyzed, bidentate chelation assisted C-H bond functionalization and their reactivity.
Article
Chemistry, Multidisciplinary
Qi-Jun Yao, Jia-Hao Chen, Hong Song, Fan-Rui Huang, Bing-Feng Shi
Summary: This study reports an unprecedented enantioselective C-H functionalization enabled by a simple cobalt/salicyloxazoline (Salox) catalysis. Chiral Salox ligands can be easily prepared in one step and used for the synthesis of various P-stereogenic compounds with high yields and excellent enantioselectivities. The isolation and characterization of several intermediates provide insights into the mechanism of active catalytic cobalt species generation, the action of Salox ligands, and the mode of stereocontrol.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Arnab Dey, Neetipalli Thrimurtulu, Chandra M. R. Volla
Article
Chemistry, Organic
Anurag Singh, Arnab Dey, Chandra M. R. Volla
Summary: In the Rh(III)-catalyzed redox-neutral coupling of N-phenoxyacetamides and alkylidenecyclopropanes, diverse chemical reactions can be achieved leading to either o-dienylation of phenols or [3+2]-annulation to generate dihydrobenzofurans. The nucleophilic directing group plays a crucial role in controlling the stereoselectivity of the products, demonstrating high synthetic utility for gram scale reactions and further derivatization.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Arnab Dey, Chandra M. R. Volla
Summary: This study achieved a novel bidentate directing-group-assisted cobalt-catalyzed oxidative C-H activation of aryl hydrazones followed by a syn-diastereoselective [3 + 2] annulation reaction using allenes as annulation partners, bypassing the need for stoichiometric metal oxidants and operating under aerobic conditions.
Article
Chemistry, Organic
Anurag Singh, Arnab Dey, Kuntal Pal, Om Prakash Dash, Chandra M. R. Volla
Summary: A novel method for achieving C4 chlorination/bromination or acetoxylation of indoles by transient directing group (TDG) assistance has been disclosed in this study. The use of inexpensive CuX2 as the halide source highlights the practicality of this approach.
