Study On Ruthenium-catalyzed C-C,C-O Bond Formation With Pirmary Alcohols

Carbon-Carbon (C-C) and Carbon-Oxygen (C-O) bonds are the basic structural units oforganic molecules, hence the formation of C-C and C-O bonds plays an important role inorganic chemistry. The construction of C-C bond is the foundation of organic synthesis, C-Oprovides the necessary basis for the diversity of organic compounds. The search foratom-efficient, mild, green and environmental-benign catalytic system for the construction ofnovel C-C and C-O bonds that form new compounds has been attracting considerableattentions in synthetic chemistry. In this paper, we firstly studied the synthesis of a serious of14-aryl or alkyl-14H-dibenzo[a,j]xanthenes under solvent-free condition, by usingsubstitutied-benzaldehydes and2-naphthol as reagents, which is a foundation for thereaction of primary alcohols and2-naphthol and to yield corresponding xanthenes. Then, weaccomplished the work of the α-pyridyl methylation of ketones. Replacing simple ketoneswith p-nitroacetophenone under the same conditions, we obtained an ester instead of themethylation product. Afterwards, we conducted a thorough investigation on this topic.Fistly, an efficient synthesis of14-aryl or alkyl-14H-dibenzo[a,j]xanthenes wasdemonstrated, allowing to assemble a wide range of products in good to excellent yields. Therepresented method consistently has the advantages of short reaction time (1-1.5h), ease ofmanipulation, eco-compatible process, use of low-cost and easily available iron catalyst.Then, we accomplished the work of α-pyridyl methylation of ketones. Under theoptimized reaction conditions, all the ketones (expect for p-nitroacetophenone) used in thereaction can be α-pyridyl methylated in good to excellent isolated yields.We conclude that thesubstitution patterns of pyridyl methanol substrates have little influence on the formation ofdesired products, however, the substituents having different electronic properties on the arylring of acetophenones affected the reaction yields significantly.Finally, we conducted a study on the reaction of p-nitroacetophenone with pyridylmethanols. Surprisingly, it was found that a C-C bond cleavage occurs between the carbonylgroup and the α-carbon of ketones. Afterwards, the carbonyl fragments in combination withprimary alcohols yield the corresponding ester products. Further experiments showed that thereaction of1,3-diones and pyridyl methanols gave a similar result. The mechanism of thisreaction is currently under investigation in our group. It is noteworthy that synthesis of estersby employing this cleavage process has never been reported. The discovery of this syntheticmethod is an important supplement of transition-metal catalyzed C-O bond formations.In the work this master thesis, two totally different pathways were found in the reactionof α-pyridyl methylation of ketones, it is a significant important advance in transition-metalcatalyzed C-C and C-O bond formations. Also, it has provided a practical basis for thecleavage of many new C-C bonds and the formations of C-O bonds...