Study On Copper-Catalyzed Cross-Coupling Rections

Copper-catalyzed cross-coupling reactions are simple, efficient, and versatile routes for the formation of carbon-carbon, carbon-nitrogen and carbon-oxygen bonds, which represents the key step in a wide range of preparative organic processes. In recent years, research works focused on the development of better catalysts, modification of reaction conditions, exploration of reaction mechanisms, and application of these cross-coupling reactions for the synthesis of interesting or promising compounds. In this thesis, recent reviews aiming at the developments on copper-catalyzed Ullmann-type cross-coupling reactions, copper-catalyzed oxidative cross-coupling reactions of alkynes and copper-catalyzed oxidative esterification reactions are summarized and several novel catalytic systems are developed for the synthesis of aromatic amines, ynamines and esters.Some cheap and readily available phenol-aldehyde-amine type Mannich bases were synthesized and used as ligands in copper-catalyzed cross-coupling reactions of aryl halides with imidazoles or ammonia. It was found that, electron-rich Mannich bases are beneficial for the reactions. When ammonia was used as nucleophile, no additional base was needed for the reaction, which made the reaction more economic, green and easy to operate.A new copper catalyzed system was developed for the Ullmann type cross-coupling reactons of aryl iodides and ureas. The method allows the preparation of a variety of symmetrical and asymmetrical diaryl ureas under mild reaction conditions without the use of ligands.Oxidative cross-coupling of alkynes and phenol-aldehyde-amine type Mannich bases was developed. It was found that2,4-di-tert-butyl-phenol type Mannich base was beneficial for the reaction. A series of propargylamines were synthesized from this kind of Mannich bases and alkynes under mild conditions. The reaction was found to proceed via retro-Mannich fragmentation.Copper-catalyzed oxidative esterification reactions were studied. Coupling of aldehydes and dialkyl peroxides afforded carboxylic esters of tertiary alcohols. In this transformation, the dialkyl peroxide plays a dual role as an oxidant and a tertiary alcohol precursor. In the presence of CuI/(3-diketimine ligand/DTBP, primary alcohols, secondary alcohols and tertiary alcohols can all react with aldehydes to afford corresponding esters in high yields. The selective of this oxidative esterifiction remarkably depends on the rection medium. Under solvent-free conditions,"self"-oxidative esterification of benzyl alcohols as well as cross-esterification of benzyl alcohols with various aliphatic alcohols proceeded smoothly to give the corresponding esters in good yields. If DMF was used as solvent, benzyl alcohols are selectively converted to corresponding aldehydes in excellent yields.Oxidative cross-coupling of cycloalkanes and arylboronic acids was developed. It was found that ammonium bromide was benifical for the reactions. Under optimized conditions, a series of aryl cycloalkanes were synthesized in good yields. In the presence of Cu(OTf)2/DTBP, oxidative sp3C-H olefination reaction of cycloalkanes with alkenes under mild conditions was realized for the first time. The reaction was found to undergo a radical pathway.