Studies On Lewis-acid Catalyzed To The Preparation Of Pyrazoles

This thesis aims at the studies on the new method for synthesis of pyrazoles with diazoacetate compounds to terminal alkynes by Lewis-acid catalyzed, which is divided two parts as follows:Partâ… : The research progress of diazo compounds in organic synthesis.In this part we mainly introducled the common reaction types of diazo compounds and its application in organic synthesis. The content included: 1, X-H (such as C-H, O-H, N-H) insertion reaction; 2, cycloaddition reaction; 3,1,3 - dipolar cycloaddition reactions ; 4, ylide reaction and so on. At the same time, the relate research results made in recent years was summarized in details.Partâ…¡: Studies on the synthesis of pyrazoles with diazoacetates compounds to terminal alkynes promoted by Lewis acid.We described a highly effective method for the synthesis of pyrazole derivatives. Using Zn(â…¡) as catalyst, we successfully realized the [3+2] cycloaddition reaction of terminal alkynes to diazoacetates compounds. This method shows advantages in terms of easily available starting materials, mild reaction conditions and simplicity of operation. In addition, the scope of the substrates were examined, and a possible reaction mechanism was proposed. All of the new compounds were characterized by NMR, MS, IR spectra.