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An IBX/NIS-induced intramolecular oxidative annulation of Mannich-type substrates is reported. This metal-free approach involving iodination, NH-oxidation, intramolecular C-N bond formation, and retro-Claisen-Schmidt sequence provides the construction of imidazo[1,2-a]pyridine, imidazo[1,2-a]pyrimidine as well as imidazo[1,2-a]pyrazine frameworks with yields up to 93%. In addition, a sequential one-pot process is also presented.
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http://dx.doi.org/10.1039/c9ob01708a | DOI Listing |
Chem Commun (Camb)
August 2025
School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, 510006, P. R. China.
An efficient synthesis of indolizines from pyridinium 1,4-zwitterionic thiolates and sulfoxonium ylides a formal [(5+1)-1] pathway has been demonstrated. This reaction process involved an iridium(III)-catalyzed (5+1) annulation, oxidation, and ring-contraction/desulfuration. This protocol featured mild conditions, broad substrate scope, and functional-group compatibility, and could be applied in late-stage modification of multiple bioactive molecules.
View Article and Find Full Text PDFJ Org Chem
September 2025
Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210023, China.
The Rh(III)-catalyzed C-H activation/annulation protocol enables efficient assembly of isoquinoline derivatives from -chloroimines and alkenes under oxidant-free mild conditions. This strategy overcomes traditional limitations by merging operational simplicity with an exceptional functional group tolerance. The scalable methodology provides direct access to pharmaceutically relevant scaffolds, exemplified by the synthesis of papaverine using readily available substrates.
View Article and Find Full Text PDFOrg Lett
August 2025
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, China.
A significant advancement has been made in the dimerization and cyclization of styrenes in one step to construct nitrogen-containing heterocyclic skeletons. Herein, we report a novel [2+2+1] dimerization annulation of styrenes and TMSN via Schmidt rearrangement, enabling straightforward access to 1-pyrrolines from the most easily available materials. Different from 5--trig cyclization, this strategy not only obviated the needs of an oxidant, a metal, and presynthesis but also possessed simple and green operations.
View Article and Find Full Text PDFOrg Biomol Chem
August 2025
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China.
A series of axially chiral 5,5'-substituted 2,2'-bipyridine ligands featuring tunable properties have been synthesized. These ligands have been successfully applied to palladium-catalyzed asymmetric oxidative [2 + 2] annulation of arylboronic acids and alkenes, providing a diverse range of chiral benzocyclobutenes in excellent enantioselectivities with a broad substrate scope.
View Article and Find Full Text PDFInt J Mol Sci
July 2025
School of Chemical & Environmental Engineering, Pingdingshan University, Pingdingshan 467000, China.
Our work introduces a facile and efficient metal-free [3+3] annulation approach for the synthesis of polysubstituted pyridines via the reaction between β-enaminonitriles and β,β-dichloromethyl peroxides. This strategy operates under mild conditions, demonstrating broad substrate scope and excellent functional group tolerance. Mechanistic investigations suggest that the reaction proceeds through a Kornblum-De La Mare rearrangement followed by SV-type C-Cl bond cleavage and intramolecular cyclization/condensation.
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