Synthesis Research Of Fused-Pyrazole Compounds

This thesis mainly focused on the synthesis of benzopyran[3,4-c]pyrazole-based compounds, we both designed two different synthetic route and synthesized a series of fused-pyrazole compounds. However, The key to the study is construction of pyrazole ring in the research process, employing two kinds methods in synthesis of pyrazole ring. On the one hand, the creation of pyrazole ring fromα,β-unsaturated carbonyl compounds and hydrazides; On the other hand, BF3·Et2O-induced intramolecular 1,3-dipolar cycloaddition reaction has been employed as synthetic tools to provide a series of fused-pyrazole compounds. The thesis includes two aspects of studies:1. The synthesis of benzopyran[3,4-c)pyrazole-based by BF3-Catalyzed 1,3-dipolar cycloaddition reactionPreparing compoundsⅡ-8 from phenols as starting materials by iodonation, which reacted with ethyl bromoacetate to afford intermediateⅡ-9, followed by Sonogashira cross-coupling to obtain coupling productⅡ-10, followed by DIBAL-H reduction to obtain reduzateⅡ-11, which treated with TsNHNH2 to afford hydrazonesⅡ-12, followed by BF3-Catalyzed intramolecular 1,3-dipolar cycloaddition reaction to afford a series of fused-pyrazole compoundsⅡ-13.2. The synthesis of benzopyran[3,4-c] pyrazolone-based compounds from a,p-unsaturated carbonyl compoundsPreparing compoundⅢ-16 from 2-hydroxyphenylacetic acid by iodonation and esterification, which reacted with ethyl bromoacetate to afford intermediate. Then treatment of intermediate with potassium tert-butoxide in THF affordedα,β-unsaturated carbonyl compoundⅢ-18, followed by Suzuki reaction. In the end, the target compoundsⅢ-20 were obtained through cyclization reaction between compoundsⅢ-19 and hydrazine hydrate.