C-H Alkenylation of Heteroarenes: Mechanism, Rate, and Selectivity Changes Enabled by Thioether Ligands
| Autor: | Bradley J. Gorsline, Long Wang, Peng Ren, Brad P. Carrow |
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| Rok vydání: | 2017 |
| Předmět: |
010405 organic chemistry
Site selectivity Cationic polymerization General Chemistry 010402 general chemistry Photochemistry 01 natural sciences Biochemistry Combinatorial chemistry Catalysis 0104 chemical sciences chemistry.chemical_compound Colloid and Surface Chemistry Thioether chemistry Selectivity Bond cleavage |
| Zdroj: | Journal of the American Chemical Society. 139(28) |
| ISSN: | 1520-5126 |
| Popis: | Thioether ancillary ligands have been identified that can greatly accelerate the C–H alkenylation of O-, S-, and N-heteroarenes. Kinetic data suggest thioether–Pd-catalyzed reactions can be as much as 800× faster than classic ligandless systems. Furthermore, mechanistic studies revealed C–H bond cleavage as the turnover-limiting step, and that rate acceleration upon thioether coordination is correlated to a change from a neutral to a cationic pathway for this key step. The formation of a cationic, low-coordinate catalytic intermediate in these reactions may also account for unusual catalyst-controlled site selectivity wherein C–H alkenylation of five-atom heteroarenes can occur under electronic control with thioether ligands even when this necessarily involves reaction at a more hindered C–H bond. The thioether effect also enables short reaction times under mild conditions for many O-, S-, and N-heteroarenes (55 examples), including examples of late-stage drug derivatization. |
| Databáze: | OpenAIRE |
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