Copper-Mediated Selective Mono- and Sequential Organochalcogenation of C–H Bonds: Synthesis of Hybrid Unsymmetrical Aryl Ferrocene Chalcogenides

An 8-aminoquinoline-directed, copper/1,10-phenanthroline-mediated selective mono-organothiolation of the C–H bond in ferroceneamide has been developed using aryl/alkyl disulfide substrates. The sequential ferrocene C–H organochalcogenation (chalcogen = S, Se, and Te) has also been established for the synthesis of novel hybrid unsymmetrical aryl chalcogenides with the aid of a catalytic amount of Cu­(OAc)2 under ambient reaction conditions. The developed protocol results in a broad functional group tolerance to allow alkyl-, aryl-, heteroaryl-, bromo-, chloro-, and nitro-containing diorgano dichalcogenides as coupling partners. Furthermore, the 8-aminoquinoline directing group is easily removed to afford the aldehyde functionality after C–H organochalcogenation. A mechanistic understanding of the copper-mediated selective mono-organothiolation reaction suggests that the rigid bicoordinated 1,10-phenanthroline ligand and freshly generated copper­(II) from Cu­(I) in the less polar solvent acetonitrile are crucial to the selective mono-C–H functionalization of ferroceneamide.