Diversity-Oriented Synthesis Of ?-CF₃-1,3-enyne And Hydrazine Derivatives,Synthesis Of Novel Chiral NHC Ligands

Privileged N-N bond-containing heterocycles,such as pyrazolidines,pyrazolines,and pyrazoles are three types of valuable compounds,because of their universality in many natural products and pharmacologically active molecules,as well as versatile utility as cornerstones in organic synthesis.On the other hand,incorporation of trifluoromethyl groups into drugs often significantly alters their metabolic stability,lipophilicity,and biological activity.In addition,trifluoromethylated N-heterocycles play crucial roles in medicinal chemistry,agricultural chemistry,and materials science.Given its application in biologically active molecules,it is of great interest to develop novel and efficient methods for the synthesis of CF₃-containing N-N bond heterocycles.In recent years,pyridine-functionalized nitrogen-heterocyclic carbene clamp ligands have received extensive attention from chemists.It is studied that pyridine-functionalized bidentate or tridentate nitrogen-heterocyclic carbene clamp ligands can coordinate with many early transition metals or post-transition metals,and are widely used in different research fields.Based on the synthesis experience of chiral phosphine ligands in our group,we envisage the synthesis of new chiral NHC ligands using chiral t-butyl sulfinamide as a chiral auxiliary.The first part of the thesis,we studied the tandem hydroamination of?-trifluoromethyl-1,3-conjugated enynes with hydrazine derivatives.It was found that cyclotrifluoromethylated pyrazoles,pyrazolines and pyrazolidines could be obtained in moderate to good yields by changing the substituents on the hydrazine N atom under the same reaction conditions.It is found that enynes substituted with electron withdrawing groups are more suitable for this reaction.In the second part of the thesis,a novel chiral Sulfinamide Pyridine Fuctionalized N-Heterocyclic Carbenes ligands was designed and synthesized.Starting from the commercial 6-bromopyridine-2-carbaldehyde,we synthesize novel chiral NHC ligands through the steps via protecting the aldehyde group,coupling with imidazole,deprotection,nucleophilic addition with chiral t-butyl sulfinamide,and then reacting with methyl iodide.We initially tried to use it in the field of asymmetric catalysis.