Diazo compounds with redox-active leaving groups are versatile reagents for orthogonal functionalizations, previously utilized in the Rh-catalyzed synthesis of highly substituted cyclopropanes. Photochemical activation of aryl-substituted diazoacetates generates carbenes, whereas redox-active esters can furnish C-radicals via the photoexcitation of EDA complexes. However, the photochemical behavior of these two functionalities, while present in one molecule, remains to be defined. We demonstrate that under light irradiation, reactions occur only on the diazo moiety, leaving the NHPI functionality intact. Not only aryl- but also alkyl-substituted NHPI diazoacetates are activated by blue light; either C-H insertion or the hydrogen/carbon 1,2-rearrangement occurs depending on the aryl/alkyl group.
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http://dx.doi.org/10.1021/acs.orglett.3c02055 | DOI Listing |
J Org Chem
January 2025
State Key Laboratory of Chemical Resource Engineering, Department of Organic Chemistry, College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China.
2-Hydroxyl/acetoxy-3-nitroindoles are directly and efficiently prepared in good to excellent yields from diazo(nitro)acetanilides under the catalysis of Cu(MeCN)PF in DCM through an intramolecular aromatic C-H insertion or followed by acetylation. 2-Hydroxyl-3-nitroindoles can be further transformed to 3-halo-3-nitroindolin-2-ones and 3-alkanamidoindolin-2-ones readily. All of them are important synthetic building blocks for construction of indole derivatives.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
University of Melbourne, School of Chemistry, 30 Flemington Rd., VIC 3095, Parkville, AUSTRALIA.
Palladium(II)-catalyzed C-H functionalization has attracted considerable attention as a pathway to late-stage modification of peptides. Herein, we report the Pd-catalyzed C(sp3)-H arylation of peptides directed by an amidoxime ether, which can be easily incorporated into peptides at any amide bond. Site- and stereoselective arylation of peptides has been achieved, including an unprecedented example of C-H arylation of an internal residue.
View Article and Find Full Text PDFJ Org Chem
December 2024
Jiangsu Key Laboratory for Chemistry of Low Dimensional Materials, School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huaian 223300, China.
An unprecedented Pd-catalyzed cascade alkyne insertion/Heck/C-H activation reaction of -iodophenyl alkenyl ethers and diarylacetylenes has been developed. Diversified tetracyclic-fused dihydroindeno[2,1-]chromenes bearing a quaternary center were constructed in an efficient, straightforward, and atom-economic way with good to excellent yields. The protocol features high bonding efficiency, operational simplicity, broad substrate scope, and easy scale-up.
View Article and Find Full Text PDFChem Asian J
December 2024
Department of Medicinal Chemistry, National Institute of Pharmaceutical Education & Research (NIPER), Sector 67, S. A. S., Nagar, Punjab, 160 062, India.
Ru(II)-Catalyzed "On Water" direct aryl C(sp)-H amidation of 2-arylbenzo[d]-thiazole/oxazole with acyl azide is reported under silver-free condition. Deuterium scrambling experiments suggested reversible C-H activation catalyzed by active cationic ruthenium species. The organic solvents such as DCE, DMF, DMSO, MeCN, dioxane, and PhMe were not conducive for the C-H amidation except for PhCl in which case, however, inferior yield (31 %) was obtained.
View Article and Find Full Text PDFACS Omega
December 2024
Natural Products and Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India.
Formaldehyde has been used as a solvent and a source of carbon to insert a methylene group for bridging two imidazo[1,5-]pyridine molecules without using any metal catalysis. This strategy has been extended on other alkyl-, aryl-, and heteroaryl aldehydes as well. This C(sp)-C(sp)-H-C(sp) bond forming reaction proceeds via C(sp)H functionalization of imidazo[1,5-]pyridine and was applied on a wide range of substrates offering moderate to good yields of methylene-bridged/inserted bis-imidazo[1,5-]pyridines.
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