Herein, we report the Pd-catalyzed regioselective direct arylation of heteroarenes in which benzenesulfonyl chlorides are used as coupling partners through a desulfitative cross-coupling that can be performed in diethyl carbonate (DEC) or cyclopentyl methyl ether (CPME) as green and renewable solvents or even in neat conditions instead of dioxane or dimethylacetamide (DMA). Under these solvent conditions, the reaction proceeds with a wide range of heteroarenes. C2- or C5-arylated products were obtained with furan and pyrrole derivatives. Benzofuran was also arylated regioselectively at the C2-position, whereas the reaction proceeds selectively at the C3- or C4-positions if thiophenes and benzothiophenes are used. Moreover, in some cases, especially with 1-methylindole, solvent-free conditions afforded better regioselectivities and/or yields than the reaction performed in the presence of solvents.
. Palladium-catalyzed regioselective C-H bond arylations at the C3 position of ortho-substituted fluorobenzenes. Organic and Biomolecular Chemistry, Royal Society of Chemistry, 2017, 15 (35) The influence of an ortho-substituent on fluorobenzene derivatives for palladium-catalyzed C-H bond arylation has been explored. In the presence of 2-bromo, 2-chloro and 2-methoxy substituents, the reaction proceeds nicely using a diphosphine-palladium catalyst and potassium acetate/dimethylacetamide (PivOK/DMA) as catalytic system. In all cases, a regioselective arylation at the the other ortho-position to the fluorine atom (C3) was observed. A variety of electronwithdrawing substituents on the aryl bromide coupling partner, such as formyl, nitro, nitrile, and also heteroaryl bromides was tolerated. Moreover, tri(hetero)aryl derivatives containing a fluorobenzene as central unit have been prepared from 2-bromofluorobenzene through palladium-catalyzed-successive C-H bond (hetero)arylations.
. Palladium-catalyzed direct desulfitative C2 arylations of 3-halo-: N -protected indoles using (hetero)arenesulfonyl chlorides. Organic and Biomolecular Chemistry, Royal Society of Chemistry, 2016, 14 (21) The direct arylation of N-protected 3-haloindole derivatives with benzenesulfonyl chlorides as coupling partners using 5 mol% of bis(acetonitrile)dichloropalladium(II) catalyst and lithium carbonate as base in 1,4-dioxane was investigated. We demonstrated that both iodo and chloro substituents at indolyl C3 position act as temporary blocking groups to allow the formation of 2-arylindoles through a direct desulfitative arylation, followed by in-situ dehalogenation. While, from 3-bromoindole derivatives, 2-aryl-3-bromoindoles were obtained without debromination, and could be converted into 2,3-diarylindoles through a second palladium coupling. which are both of interest as potential intermediates in the synthesis of bioactive molecules.
Heteroarenes. -Using arylsulfonyl chlorides, arylation proceeds with remarkable regioselectivity: furans, benzofurans and N-alkyl/phenyl-pyrrols give C2-arylated products while thiophenes and benzothiophenes give the C3-arylated products. N-Methylindole, however, gives regioisomeric C2/C3 mixtures. Aside DEC dioxane, cyclopentyl methyl ether, water, ethylene glycol, pentanol, propylene carbonate as well as mixtures thereof and neat conditions are applied as eco-friendly solvents with DEC giving the best results. -(HFAIEDH, A.; YUAN, K.; BEN AMMAR*, H.; BEN HASSINE, B.; SOULE, J.-F.; DOUCET, H.; ChemSusChem 8 (2015) 10, 1794-1804, http://dx.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.