Metal–Organic Cooperative Catalysis in C–C Bond Activation

Abstract

This review describes recent advances that have been made in studies of transition metal-promoted metal-organic cooperative C-C single bond activation reactions of unstrained organic substances, which use 2-aminopicoline as a temporal chelating ligand. In addition, metal-organic cooperative C-C double bond and C-C triple bond cleavage processes are discussed in association with transition metal-catalyzed C-H bond activation. Recent progress made in these areas has opened up the new paradigms in synthetic organic chemistry for the construction of organic frameworks by structural reorganization of organic backbones. Among the many strategies devised, chelation-assisted C-C bond cleavage reactions, which operate through cooperation between metal complexes and organic substances, have attracted perhaps the greatest attention. Utilizing this approach, efficient C-C single bond activation reactions have been developed for a variety of substrates, including linear alkyl ketones, secondary alcohols, primary amines, and cycloalkanones. In addition, reactions that lead to cleavage of C-C double and triple bonds can be facilitated by using the metal-organic cooperation strategy. C-C double bonds in α,β-enones can be cleaved by addition of cyclohexylamine, which facilitates Michael addition and retro-Mannich type fragmentation cascades proceeding via β-aminoketimine intermediates. Aldehydes, which serve as one of the fragmentation products of these processes, can be trapped by chelation-assisted hydroacylation reactions to produce ketones. Finally, C-C triple bond cleavage of alkynes can be achieved through hydroacylation reactions with aldehydes and subsequent C-C double bond cleavage of the resulting α,β-enones.

Metal–Organic Cooperative Catalysis in C–H and C–C Bond Activation

“…To avoid these shortcomings, a new strategy using temporarily installed coordinating auxiliaries has been devised for C–H bond activation (Figure b). ,− In this approach, only a catalytic amount of a coordinating auxiliary is required because it is readily installed in situ into the reactant and removed from the product after the C–H bond activation reaction. In this case, the coordinating auxiliary is called an “organic catalyst”.…”

Two in one: A Brønsted acid grafted photoactive covalent organic framework as metal-free dual photocatalyst for aerobic oxidative C-C cleavage

“…The selective cleavage of C-C bonds to form new chemical bonds is scientifically and technologically very important and forms a valuable tool for synthetic fine chemistry, pharmaceutical synthesis, and petrochemical conversions [1][2][3]. Especially, the C-C bond cleavage of cycloalkanones, prevalent in natural products and pharmaceuticals, could provide strategic bond disconnections in the synthesis of complex bioactive molecules [4][5][6][7]. However, due to the large C-C bond dissociation energy (~332 kJ/mol) and the absence of intrinsic ring strain tension, the C-C bond cleavage of cycloalkanones remains a huge challenge.…”

Heterogeneous Iron-Catalyzed Aerobic Oxidative Cleavage of C–C Bonds in Alcohols to Esters

“…Owing to the widespread use of the cleavage and functionalization of C–C bonds in organic synthesis, petrochemical industry, medical industry, and biomass degradation, the cleavage of C–C bonds is attracting more and more attention. − From the perspective of thermodynamics and spatial configuration, the cleavage of C–C bonds is a huge challenge, but it still attracts the interest of many researchers . Among the different types of C–C bonds, the more prominent feature of the C­(OH)–C bonds is that they are abundant in biomass represented by lignocellulose, so the cleavage of C­(OH)–C bonds is of great significance in biomass valorization. − Traditionally, various stoichiometric or excessive oxidants, such as chromium trioxide, potassium permanganate, and manganese dioxide, were used for the oxidative cleavage of C–C bonds. − However, they produce pollutants and cause serious environmental problems.…”