An atom economical protocol for the construction of 9-(diorganomethylidene)fluorenes through palladium-catalyzed coupling reactions of 2-iodobiphenyls with alkenyl bromides has been reported. The reaction proceeds through the C-H activation/oxidative addition/reduction elimination/intramolecular Heck coupling reaction to afford a series of 9-(diorganomethylidene)fluorenes with good yields. Control experiments demonstrate that a five-membered palladacycle acts as a key intermediate and β-H elimination serves as the rate-limiting step.
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http://dx.doi.org/10.1039/d1ob01547h | DOI Listing |
J Org Chem
January 2025
Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, United States.
A regiodivergent palladium-catalyzed Suzuki-Miyaura reaction has been successfully implemented to synthesize (-)-lyngbyatoxin, (-)-teleocidin A2, and (-)-7-geranylindolactam V. This ligand-controlled cross-coupling strategy allowed for the direct preparation of these natural products from a single advanced synthetic intermediate, providing the shortest reported route to each compound. Subsequent studies in cancer cell lines were conducted to explore the chemotherapeutic applications of these natural products.
View Article and Find Full Text PDFOrg Lett
December 2024
Division of Medicinal Chemistry, CSIR-Institute of Microbial Technology, Chandigarh 160036, India.
A novel palladium-catalyzed intramolecular C-H amination via oxidative coupling exploiting inactivated N-substituted aryl amines on indoles for the one-pot synthesis of novel 11-benzo[4,5]imidazo[1,2-]indole derivatives is reported. The optimized reaction conditions accommodated a wide range of electronic variations on both the indole and the pendant aryl amine ring, resulting in products with good to excellent yields.
View Article and Find Full Text PDFJ Org Chem
December 2024
Department of Chemistry, Indian Institute of Science Education and Research (IISER)-Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.
A Pd (II)-catalyzed direct C3-(sp)-H alkenylation of heteroarenes using benzothiazole as a directing group was successfully achieved. A wide range of 2--alkylpyrroles undergo an oxidative coupling with a variety of acrylates to furnish highly regio- and chemoselective E-alkenylation products at the C3 position. An important intermediate complex has been isolated and characterized so as to have an insight into the mechanism.
View Article and Find Full Text PDFHelv Chim Acta
April 2024
Department of Chemistry, Texas A&M University, PO Box 30012, College Station, TX 77842-30012, United States.
We describe herein the design and synthesis of a new class of dialkylarylphosphine ligands incorporating a Lewis-basic urea subunit. The ligand synthesis consisted of six linear steps and was enabled by the discovery of a new N-to-N alkyl migration reaction. This new series of dialkylarylphosphine urea ligands were applied in common palladium-catalyzed cross-coupling reactions for the formation of carbon-carbon and carbon-nitrogen bonds in moderate to high yields.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
Nickel-catalyzed cross-electrophile coupling (XEC) reactions of (hetero)aryl electrophiles represent appealing alternatives to palladium-catalyzed methods for biaryl synthesis, but they often generate significant quantities of homocoupling and/or proto-dehalogenation side products. In this study, an informer library of heteroaryl chloride and aryl bromide coupling partners is used to identify Ni-catalyzed XEC conditions that access high selectivity for the cross-product when using equimolar quantities of the two substrates. Two different catalyst systems are identified that show complementary scope and broad functional-group tolerance, and time-course data suggest that the two methods follow different mechanisms.
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