Palladium-catalyzed Glaser Reaction And Dearomatization Reaction

Palladium-catalyzed C-C bond formation is one of the important tools in organic synthesis, which is widely used in synthesis of natural products, polymers, liquid crystals, and advanced materials. In present work, we investgated the palladium-catalyzed Glaser reaction and Dearomatization reaction, the main content are summarized below:1. Highly efficient Glaser reaction is developed catalyzed by Pd(PPh₃)₄/Ag₂O catalytic system. In the past, a stoichiometric ratio of a reoxidant and amine are necessary for successful homocoupling in the Pd-catalyzed homocoupling reactions of terminal alkynes. Amines are always rancidly and reoxidant such as I₂, BrCH₂COOEt, CICH₂COCH₃ are always toxic and environment-unfriendly. Those defects limit their application. In our research work, the Ag₂O is found to promote this reaction. Later, we evaluate the effect of various palladium catalysts and the quantity of Ag₂O on the Pd-catalyzed homo-coupling of phenylacetylene. We find that in the present of 1% Pd (PPh₃)₄, stoichiometric ratio Ag₂O and THF as solvent, all kinds of terminal alkynes afforded moderate to excellent yields. It is worth to note that the procedural simplicity, environment-friendly, efficient and the product easy purification.2. Palladium-catalyzed dearomatization reaction is developed. At present, all of the palladium-catalyzed dearomatization reactions give the allylative dearomatization products. Our goal is to extend this type reaction by change various organotins. First, we use benzene and naphthalene allyltributylstannane as reactants to give benzene and naphthalene allylative dearomatization products. When we use tributyl(penta-2,4-dienyl)stannane, it gives two isomeric penta-2,4-dienyl dearomatization products, one is ortho, another is para. Then, we study the dearomatization reaction of tributyl(penta-2,4-dienyl)stannane with the other chloromethyl naphthalenes. To our surprise, the tributyl(penta-2,4-dienyl)stannane can occur dearomatization reaction with 2-(chloromethyl)naphthalene and 9-(chloromethyl)-phenanthrene which is not observed dearomatization reaction with allyltributylstannane. Those work develope palladium-catalyzed dearomatization reactions.