Recent Progress on Copper-Catalyzed C–C Bond Formation via C(sp2)–H Insertions Using Diazo and Related Compounds

Abstract

Site-selective insertion of metal-carbenes via C(sp2)−H bond functionalizations is an interesting topic to the synthetic chemistry community. Formations and applications of copper carbene intermediates in recent years become significantly increased due to their cost-effectiveness and versatile reactivities. Further, transformations based on C(sp2)−H insertion using diazo and related compounds and its asymmetric versions under copper catalysed conditions have emerged as a new tool for C−C bond formations. This short review summarizes the selective recent advancements in this field.

Rhodium-catalyzed formal four-component reaction with hypervalent iodine diazoesters, alcohols, and isatins for the synthesis of multi-functionalized oxindoles

“…After that, a selection of commercially available transition metal catalysts was evaluated, and Rh 2 (esp) 2 gave results similar to those obtained with Rh 2 (Oct) 4 (Table 1, entry 4 ). By contrast, Cu(CH 3 CN) 4 PF 6 and [PdCl(η 3 -C 3 H 5 )] 2 , which have proven to be successful in metal carbene transformations, 14 were not favorable here and did not furnish any desired product. This result might have been due to the poor capacity of the reaction of these substrates to generate metal carbynoids since most of hypervalent iodine reagents 1b still remained (Table 1, entries 6 and 7).…”