Synthesis Of Fluorocyclopentenes And New Chiral Polydentate Ligands

Five-membered carbocyclic compounds are an important structural unit in natural products and non-natural products.Among them,cyclopentene and its derivatives are core skeletons of many biologically active compounds and are widely found in natural products,drugs and functional materials.The inclusion of the electron-withdrawing CF₃ group in drug candidates has appeared as a general strategy to increase robustness against metabolic oxidation in the“hit to lead”approach.In view of its application in bioactive molecules,the development of a novel and highly efficient method for the synthesis of trifluoromethylcyclopentene is of great importance.In the first part of the dissertation,we studied the tandem intermolecular hydrocarbonation and intramolecular hydrocarbonation?double hydrocarbonation sequence?of 2-trifluoromethyl-1,3-conjugated enynes with 1,3-dicarbonyl compounds leading to ring-trifluoromethylated cyclo-pentene frameworks by combination use of AgNO₃ as a catalyst and Et₃N as a base via allene intermediates.Enynes possessing electron-withdrawing aryl groups on the alkyne moiety are general good candidates for present transformation.In the second part of the dissertation,a novel chiral aminophenol ligand was designed and synthesized.Starting from the commercial salicylaldehyde,we synthesize novel chiral gamma-aminophenol ligands through four steps via condensation with amines,addition with Grignard reagents,removing t-butylsulfinyl group,and condensation with aldehydes.Due to the presence of multiple hydrogen bonds,this type of ligands can form a stable complex with a variety of metals,and we have attempted to use it in the field of asymmetric catalysis.In the third part of the thesis,a series of chiral pyridine ligands containing sulfoxide was designed and synthesized.We synthesized this chiral ligands from 2-pyridinecarboxaldehyde by condensation with amines,addition with Grignard reagents and methylation of nitrogen.This type of ligands contain both pyridine and sulfoxide,two unique metal coordination groups,and we have tried to use it for asymmetric catalytic reactions.