Studies On The Synthesis Of And Sulfur-Fluorine Overlap Allenes And Chiral Nitrophosphine Ligands

Sulfur-fluorine overlap heterocyclic ring compounds are widely found in medicines,materials and foods.Sulfur-fluorine overlap allenes as an important organic synthesis intermediate,it can be cyclized to form fluorine-containing thiophene compounds.The thiophene compound is a relatively important sulfur-containing five-membered heterocyclic ring,it's an important structural unit of many natural products and drugs,and also plays an intermediate role in organic synthesis.Thiophene compounds are not only found in some natural product drugs,but also in the fields of printing and dyeing,aerospace,electronics and so on.Therefore,it's of great significance to develope the direct synthesis of sulfur-fluorine overlap olefins and their cyclization to form fluorothiophenes.In the first part of the thesis,the raw material 2-trifluoromethyl-1,3-enyne regioselective nucleophilic addition with benzyl mercaptan as a nucleophile.The yield of sulfur-fluorine overlap allenens was depending on the kinds of base and solvent.We found that the optimal conditions for the sulfur-fluorine overlap allenens was performed in the co-solvent of chloroform and dimethyl sulfoxide at room temperature by using tetramethyl-ethylenediamine as catalytic base.It can also be cyclized by NXS to form3-trifluoromethylhalothiophene.We also attempted to synthesis chiral allenes.The second part of the paper,we initially attempted designed and synthesized a novel pyridine ligand,including a pyridine sulfoxide ligand and an chiral N₄ ligand.Tert-butylsulfinamide coupled with commercial 2-bromo-5-trifluoromethyl-pyridine to give the target ligand.Chiral N₄ ligand is starting from commercial pyridine-2-carboxaldehyde,condensation with amine,addition of Grignard reagent,removal of tert-butyl sulfoxide and nucleophilic substitution,we used this ligand to try in the asymmetric field.The third part of the paper,we designed and synthesized new nitrogen,phosphine and phosphine oxide ligands.Similar to the second part,we start from the commercial pyridine-2-carboxaldehyde,then combine with amine condensation,addition of Grignard reagent,removal of tert-butyl sulfoxide and diphenylphosphine chloride and diphenylphosphonium phosphine to replace in new nitrogen phosphine ligands.We also used nitrogen and phosphine ligands to undergo methylation reaction.Finally,some asymmetric reactions using this type of ligand was tried.