DABCO-promoted Synthesis Of Pyrazoles From Tosylhydrazones And Nitroalkenes

Pyrazoles and their derivatives represent important heterocyclic motifs which have been found widespread application in the pharmaceutical and agrochemical industries. Compounds containing the pyrazole moiety have been shown to possess a wide range of biological activities like antibacterial, antispasmodic, anti-inflammatory, plant growth regulators and anti-platelet aggregation. Since Knorr’s seminal report,130years ago, a wide range of synthetic variants have been reported in the literature.An efficient synthesis of substituted pyrazoles from tosylhydrazones and nitroalkenes was developed. In comparison with the previously reported1,3-dipolar cycloaddition reaction of diazo compounds with electron-deficient alkenes or alkynes, this methodology proceeded with a sequential Baylis-Hillman/intramolecular cyclization mechanism and a variety of reversed regioselectivity products were prepared in good yields.The thesis comsists of the following three main parts:the first part summarizes the applications of pyrazole derivatives and their preparation methods. In the second part, we talked about the process of DABCO-promoted synthesis of pyrazoles from tosylhydrazones and nitroalkenes, meanwhile the reaction mechanism was discussed. The third part includes the experiment procedure and analytic data.