Rhodium or Ruthenium-Catalyzed Oxidative C-H/C—H Cross-Coupling: Direct Access to Extended π-Conjugated Systems

摘要

Extended 31-conjugated structures containing bi-, ter-, tetra-, and poly(hetero)aryl motifs are found in many biologically active molecules, ligands, agrochemicals, pharmaceuticals, natural products, and especially, in optical and photochromic materials. Conventional wisdom states that the construction of bi(hetero)arenes mostly relies on the transition-metal-catalyzed C—X/C-M cross-coupling of a (hetero)aryl halide or pseudohalide with a (hetero)aryl organometallic reagent. The further extension of π-conjugated systems from bi-(hetero)aryls to ter-, tetra-and poly(hetero)aryls usually requires the installation of activating groups (such as, CI, Br, I, OTs, SiR3, BR2, SnR3, ZnR) onto the coupling partners. However, these preactivation methods can suffer from long multistep reaction sequences, poor regio-and/or chemo-selectivity, and even poor availability.