Study On The Multi-component One-pot Synthesis Of Highly Functional Pyrano [2,3-c] Pyrazole Compounds And Multi-substituted Pyrimidine Compounds

Pyrazole and pyran are very important structural units,both of which have a high biological activity.The structure of pyrano[2,3-c]pyrazole and its derivatives possessing functional groups as pyrazole and pyran rings,which has higher research value.Triazole and pyrimidine compounds are widely used in pesticide,pharmaceutical,industrial and other applications,and their preparation is also a hot topic in the field of organic synthesis.A series of efficient methods were developed for the synthesis of pyrano[2,3-c]pyrazole and triazole-pyrimidine compounds via one-pot reaction.Here,we used several cheap,green and readily available catalysts and reagents to efficient and green synthesis of these compounds.The first chapter introduces the new progress of green chemistry,the research on heterocyclic compounds,the progress of multi-component one-pot reaction.In addition,a research progress on the one-pot synthesis of multi-substituted pyrano [2,3-c]pyrazole compounds and multi-substituted [1,2,4] triazolopyrimidine compounds has been introduced.In the second chapter,sixteen 1,4-dihydro-pyrano[2,3-c]pyrazole derivatives containing dicarboxylates were synthesized via a one-pot reaction,and the product obtained in 70-92% yields.The result indicated that urea was an effective and green catalyst.Also,we obtained four 6(1H)-oxides substituted-pyrano[2,3-c]pyrazole derivatives in 70-82% yields under similar condition.The above compounds were confirmed by 1H NMR,13 C NMR,IR spectroscopy,and mass spectrometry.The structures of representative compounds 5e and 6b were furthere determined by a single-crystal X-ray diffraction.Finally,we proposed the catalytic mechanism of urea in these one-pot reaction.In the third chapter,we introduce an efficient,direct and economical multi-component one-pot synthesis of multi-substituted pyrano[2,3-c]pyrazole dicarboxylates.The reaction was conducted by using four reactants as ethyl acetoacetate,hydrazine,dimethyl acetylene dicarboxylate and malononitrile,and using cationic surfactant TBAB as a catalyst,anhydrous ethanol as a solvent,The result showed that all the substrates were yield the desired product in a higher yield.The structure of all compounds were confirmed by IR,1H NMR,13 C NMR and HRMS spectra.In addition,a reasonable catalytic reaction mechanism of TBAB catalyst were suggested.In the fourth chapter,we have described an efficient method for the synthesis of [1,2,4]triazolo[1,5-a]pyrimidine derivatives and dihydrobenzo[4,4-a] pyrimidine derivatives via three-component one-pot reaction.The reaction were catalyzed efficiently by resin Amberlyst-15.This method has some benefits including a short reaction time and a simple post-treatment.Moreover,the catalytic activity of the catalyst can be repeated for four times without a significant decrease.Finally,the mechanism of Amberlyst-15 catalytic reaction was studied.