1038997-90-8Relevant articles and documents
Pd/C as a catalyst for completely regioselective c=h functionalization of thiophenes under mild conditions
Tang, Dan-Tam D.,Collins, Karl D.,Ernst, Johannes B.,Glorius, Frank
supporting information, p. 1809 - 1813 (2014/03/21)
The completely C3-selective arylation of thiophenes and benzo[b]thiophenes was achieved by using Pd/C as a heterogeneous catalyst without ligands or additives under mild reaction conditions. The practicability of this transformation is demonstrated by notable functional group tolerance and the insensitivity of the reaction to H2O and air. This method is also applicable to nitrogen- and oxygen-containing heterocycles, yielding the corresponding C2-arylated products. Three-phase tests along with Hg-poisoning and hot-filtration tests suggest that the catalytically active species is heterogeneous in nature. I+ can do better! Pd/C can be used without ligands or additives to catalyze the completely C3-selective arylation of diversely substituted thiophenes and benzo[b]thiophenes under mild reaction conditions. The physical nature of the catalytic species was investigated and the mechanism was studied. Relative rate data generated in a "robustness screen" were used to design a complex substrate that undergoes highly chemoselective sequential functionalization. Copyright
Cu(II)-catalyzed direct and site-selective arylation of indoles under mild conditions
Phipps, Robert J.,Grimster, Neil P.,Gaunt, Matthew J.
supporting information; experimental part, p. 8172 - 8174 (2009/02/02)
We have developed a new site-selective Cu(II)-catalyzed C-H bond functionalization process that can selectively arylate indoles at either the C3 or C2 position under mild conditions. The scope of the arylation process is broad and tolerates broad functionality on both the indole and aryl unit, which makes it amenable to further elaboration. The mechanism of the arylation reaction is proposed to proceed via a Cu(III)-aryl species that undergoes initial electrophilic addition at the C3 position of the indole motif. We speculate that site of indole arylation arises through a migration of the Cu(III)-aryl group from C3 to C2, and this can be controlled by the nature of the group on the nitrogen atom; free (NH)- and N-alkylindoles deliver the C3-arylated product, whereas N-acetylindoles afford the C2 isomer, both with excellent yield and selectivity. Copyright
