Study Of Transition Metal Catalyzed C-C Bond And C-O Bond Activation Reaction

Transition-metal-catalyzed C-C bond cleavage has been considered as one of themost interesting subject in organometallic chemistry. The C-C activation step isthermodynamically unfavorable. Additionally, the kinetic barrier is thought to behigher for C-C activation than for C-H activation. The key is the difference in orbitaldirectionality between the C-H and C-C bond. Therefore, C-H activation is morefavorable than C-C bond activation. In order to facilitate C-C bond cleavage, themeasures must be taken so that C-C cleavage prevail thermodynamically andkinetically over the competing C-H cleavage. Currently, many important reactionmodels based on chelation-assisted C-C activation have been developed. Herein, wereport C-C bond formation through a chelating assisted C-C activation. The substrateshaving a N-directing group, for example,1-(quinolin-8-yl)ethanone, phenyl-(quinolin-8-yl)methanone, ethyl benzo[h]quinoline-10-carboxylate, benzo[h]quinolin-10-ylmethanol et al., was reacted with arylboronic acid to obtain the desired productsin the presence of rhodium catalyst. The cross-coupling reaction provide a powerfulmeans to assemble C-C bond.In recent years, The C-O activation reaction has made encouraging progress.However, compared with C-H bond and C-O bond activation, there are still largedifferences. There are two types of processes which the low transition metal organiccompounds react with esters derivatives through oxidative addition. One is thecleavage of an alkyl-O bond (alkyl fission) in esters, and the other is the cleavage ofan acyl-O bond (acyl fission) in esters. Among them, the cleavage of an acyl-O bond(acyl fission) in esters, catalyzed by transition metal complexes, is very rare. The acylgroup may be used to construct ketones by C-O bond activation. A new method forbuilding aryl-aryl ketones containing heterocyclic rings through chelation-assistedC–O bond activation catalyzed by a rhodium complex has been developed. In thisreaction, methyl quinoline-8-carboxylate, methyl quinoxaline-5-carboxylate, and theirderivatives were reacted with an excess amount of a substituted phenyl boronic acidin the presence of a rhodium(I) complex to give substituted phenyl-(quinolin-8-yl)methanone, phenyl-quinoxalin-5-yl-methanone, and their derivatives in medium tohigh yields. Quinoline and quinoxaline derivatives are important building blocks in the construction of organic molecules having special properties.8-Benzoylquinolinehas been frequently used as a core structure for the design of modern pharmaceuticalsand related compounds, such as tubulin polymerization inhibitors, cannabinoidreceptor ligands, drugs for the treatment of bone metabolic disorders, and anti-ulceragents. The current method offers a possible synthetic pathway to efficiently buildsimilar compounds from readily available materials.