A new and efficient synthesis of 8H-benzo[e]phenanthro[1,10-bc]silines from 2-((2-(arylethynyl)aryl)silyl)aryl triflates under palladium catalysis has been developed. The reaction mechanism was experimentally investigated and a catalytic cycle involving C-H/C-H coupling through a new mode of 1,4-palladium migration with concomitant alkene stereoisomerization is proposed.
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http://dx.doi.org/10.1002/anie.202000217 | DOI Listing |
Molecules
January 2025
Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, School of Pharmacy, Yantai University, Yantai 264005, China.
A Cu-promoted highly chemoselective dimerization of 5-aminopyrazoles to produce pyrazole-fused pyridazines and pyrazines is reported. The protocol generates switchable products via the direct coupling of C-H/N-H, C-H/C-H and N-H/N-H bonds, with the merits of broad substrate scope and high functional group compatibility. Gram-scale experiments demonstrated the potential applications of this reaction.
View Article and Find Full Text PDFChem Commun (Camb)
November 2024
Organometallic Synthesis and Catalysis Lab, Organic Chemistry Division, CSIR-National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune - 411 008, India.
We report the first regioselective C2-C7 oxidative coupling of indoles using a palladium catalyst upon the strategic installation of -pyridinyl and C3-carbonyl, which delivers 2,7-biindoles with a broad scope (25 examples; up to 93% yield). Isolation of the catalytic intermediate reveals the initial activation of the C(7)-H bond, followed by the C(2)-H bond in indoles, and the reaction proceeds a Pd(II)/Pd(0) pathway.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
Oxidative cross-dehydrogenative C-H/C-H functionalizations represent an exemplary approach for synthesizing carbonyl compounds via α-heteroarylation. Here we present the development of a direct anodic oxidative coupling process between 2-acylimidazoles and divergent heterocyclic systems including indole, pyrrole, and furan, facilitated by ferrocene-assisted asymmetric nickel electrocatalysis with high levels of enantioselectivity. Mechanistic investigations indicate that the reaction initially involves the formation of a chiral Ni-bound α-carbonyl radical, which is then captured by the heteroarene radical cation via intermolecular stereoselective radical/radical cation coupling.
View Article and Find Full Text PDFChem Asian J
December 2024
Key Laboratory of Medicinal Chemistry for Natural Resource (Yunnan University), Ministry Education, School of Pharmacy, School of Chemical Science and Technology, Yunnan University, Kunming, 650091, P. R. China.
2,3'-Bisindoles with C-C linkages have attracted interest in medicinal chemistry, yet their synthesis is intricate with many steps. Notably, direct C-H/C-H cross-coupling of non-directed heteroaromatics remains challenging, often requiring precious metals and oxidants to enhance coupling efficiency. Herein, we present a copper-catalyzed C-H/C-H cross-coupling method for N-substituted indoles without directing groups, facilitated by molecular oxygen under gentle conditions.
View Article and Find Full Text PDFJ Org Chem
September 2024
Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, China.
We herein disclose a highly efficient one-pot synthetic strategy for dihydrobenzo[]fluorenes via cascade rhodium(III)-catalyzed -C-H activation/annulation of thiobenzamides with aryl ethynyl ketones and subsequently copper(II)-promoted intramolecular C-H/C-H cross-coupling reactions. Mechanistic investigations suggest that Cu(II) plays two crucial roles by serving as a sulfide scavenger to regenerate the Rh(III) catalyst and promoting the intramolecular C-H/C-H cross-coupling reaction. This protocol greatly streamlines accesses to a variety of appealing tetracyclic benzo[]fluorene skeletons, which may have potential biological activity and medicinal properties.
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