Studies On The Copper-Catalyzed Intramolecular Vinylation Of Amides And Thiols And On The Election Transfer-Induced Ortho-Amination Of 2-Naphthols

The transition metal-catalyzed C-X(X = N,S) bond formations have been a useful and efficient method in organic synthesis.Our attention was focused on the synthesis of N-and S-heterocycles via N-vinylation of amides and S-vinylation of thiols with intramolecular Ullmann coupling(IUC) as the strategy.Additionally,we also developed a methodology for the ortho-amination of 2-naphthols triggered by electron transfer.The dissertation could be described as the following three parts:1.The feasibility of the intramolecular N-vinylation of amides in a 4-exo mode under typical Ullmann reaction conditions was explored.Employing CuI(5 mol%), N,N-dimethylglycine hydrochloride(10 mol%) and K₂CO₃(2 equiv.) in refluxing THF as the optimized reaction conditions,the four-membered 4-alkylidene-2-azatidinones could be efficiently synthesized.The competition experiments revealed that the 4-exo ring closure is fundamentally preferred over other modes of cyclization.With primary amide substrates,tandem C-N bond formation and ring expansion reactions were then successfully developed to produce eight-and nine-membered lactams in excellent yields.2.On the basis of the above N-vinylaiton of amides,the Cu(â… )-catalyzed intramolecular C-S coupling of thiols was implemented for the first time with CuI (10 mol%) as the catalyst and K₃PO₄·3H₂O(2 equiv.) as the base.The ligand-free reaction allowed the convenient generation of 2-methylenethietanes.For vinyl chloride,the reactions were conducted in refluxing dioxane,while the reactions of the corresponding vinyl bromides proceeded at a lower temperature(refluxing MeCN). This strategy was then extended to formation of five-and six-membered heterocyclic thioenol ethers.Moreover,the preference of 4-exo cyclization was also observed in the competition experiments,revealing its generality in Cu(â… )-catalyzed intramolecular vinylation reactions.3.With TEMPO(5 mol%) as the catalyst,N-methyl-N-phenyl-hydrazine(1.2 equiv.) as the amine source,the direct ortho-amination of 2-naphthols could be easily achieved.The reaction was carried out at room temperature under air atmosphere.The procedure was simple,highly efficient and practical.The possible mechanism was discussed,which could involve a radical-polar crossover reaction induced by electron transfer.As a comparison,the amination of phenols turn out to be unsuccessful under various conditions tested.