The Insertion Of A Small Organic Molecule Into A CN Bond To Synthesize A Pyrazole Compound And A Modified Montmorillonite-catalyzed Meyer-Schuster Rearrangement Study

The thesis contains two sections:Section One:As one of the most important heterocyclic compounds,pyrazoles,an unsaturated 5-membered ring containing two nitrogen atoms,have been found to possess an extensive range of pharmacological activities such as analgesic,anticancer,anti-inflammatory,etc,and thus play a significant role in drug discovery.Some pyrazole-containing drugs,such as Celebrex,Rimonabant and Tepoxalin,are already booming in the market.In addition,pyrazole also plays an important role in pesticides and luminescent materials.Consequently,numerous strategies for constructing pyrazole rings have been developed.These methods mainly include condensation reactions,1,3-Dipolar cycloaddition reactions,direct C-H bond amination.However,despite of various advantages in the reported methods,there are still some drawbacks such as the difficulty in preparation of substrates,the complicated synthetic procedure,and the harsh reaction conditions.In this thesis,we have demonstrated a facile protocol for the synthesis of pyrazole derivatives by using simple 1,3-disubstituted propylene and hydrazine as substrates.Various 1,3,5-trisubstituted pyrazoles were installed via the cascade intermolecular/internal C-N formations under neutral and mild DDQ-oxidative conditions.This oxidative protocol,permitting multiple direct C-H bond functionalization in one pot,features great atom economy and mild metal-free conditions.The main contents of this study include:1)First,the conditions for the new method were explored and the optimal conditions were determined with DDQ as oxidant in DCE at 40 0C.2)Under the optimal conditions,a variety of symmetric substrates?16 examples?and asymmetric substrates?5 examples?were easily converted into the corresponding pyrazoles in moderate to excellent yields.3)We synthesized anti-inflammatory activity pyrazole N-[4-?Aminosulfony l?phenyl]-3,5-diphenyl-1H-pyrazole-1-acetamide.4)To gain some insight into the reaction mechanism,a series of experiments were conducted,including the fractional step of C-H bond amination and the capture of intermediates.On the basis of the results,a possible mechanism was proposed.5)The conditions of the cross-coupling of 1,3-diarylpropene with electrophilic hydrazine were also studied and different substrates?9 examples?could be readily transformed to the desired products.Section Two:?,?-Unsaturated carbonyl compounds are a class of conjugated unsaturated compounds containing double functional units.?,?-Unsaturated carbonyl compounds are widely used in the synthesis of natural products,functional materials and drug molecules.In addition,these compounds are also the backbone of a variety of natural products,pharmaceutical molecules and functional materials.The main methods for the synthesis of these compounds include aldol condensation,Wittig reaction,HWE reaction,Meyer-Schuster rearrangement and so on.Among them,Meyer-Schuster rearrangement has attracted considerable attentions because of its readily available starting materials and high atom economy.However,the present reaction system for Meyer-Schuster rearrangement still have some disadvantages such as high-cost catalyst,poor geometric selectivity and harsh reaction conditions.In this thesis,we have developed an efficient Fe³⁺-modified-montmorillonite-catalyzed Meryer-Schuster rearrangement.This method has the advantages of mild conditions,simple operations,good yields and high geometric selectivity.In addition,the montmorillonite catalyst can be recycled after simple filtration.The main contents of this study include:1)Preparation of ion exchanged montmorillonite.2)The conditions for Meyer-Schuster rearrangement reaction were studied,and the optimal conditions were finalized with Fe³⁺ modified montmorillonite as catalyst in DCE at 80 ?.3)Under the optimal conditions,diverse propargyl alcohols substrates?26 examples?were easily converted into the corresponding ?,?-unsaturated carbonyl compounds in moderate to excellent yields with higher E selectivity.4)The catalyst was recycled for three times,and the catalytic effect was not significantly decreased.