Palladium-Catalyzed Halopalladation Reaction And Coupling Reaction Of Alkynes

This thesis is concerned with studying the halopalladation reactionand coupling reaction of alkynes as well as some palladium-catalyzedcoupling reactions. The main contents are included:1. The progress in the palladium-catalyzed halopalladation reaction,cross-coupling reaction and homo-coupling reaction of alkynes aresummarized. The halopalladation reactions of alkynes were firstlyintroduced in detail from the view of trapping the intermediate ofhalopalladation of alkynes. Subsequently, the Sonogashiracross-coupling reactions of alkynes were also described based onligands, catalysts and reaction media. Noteworthy is that themechanisms of the palladium-catalyzed halopalladation reaction andthe Sonogashira reactions of alkynes were also introduced.2. Two types of halopalladation reactions of alkynes using PdCl₂/CuCl₂catalystic system have been developed including: the regioselectiveand stereoselective palladium-catalyzed dimerizations of terminalalkynes method for the synthesis of symmetrical(Z,Z)-1,4-dihalo- 1,3-dienes, and the palladium-catalyzed armulationsof 2-alkynylphenols method for the synthesis of 2-substituted3-halobenzo[b]furans. The results showed that the selectivity of the fore reaction based on the solvent, and the selectivity of the latterreaction was controlled by the HEt₃NX additives.3. Both CuX₂-mediated the annulation reactions ofo-(alk-1-ynyl)benzoates by to synthesize the corresponding4-haloisocoumarins and FeCl₃-catalyzed cyclization ofo-(alk-1-ynyl)benzoates to synthesize 3-substituted isocoumarins werepresented, respectively.4. Two protocols for the palladium-catalyzed homocoupling reactions ofterminal alkynes have demonstrated using thePd(OAc)₂/CuI/DABCO/air system or the PdCl₂/CuI/NaOAc/Me₃NOsystem.5. The Sonogashira reactions were studied under three different reactionconditions. Firstly, Pd(OAc)₂ combined with Dabco was found to bean efficient catalytic system for the mild and aerobic Sonogashiracross-coupling reactions under copper- and ligand-free conditions.Secondly, a general and fast Sonogashira cross-coupling reaction wasprovided using PdCl₂(PPh₃)₂ as the catalyst and TBAF as the baseunder solvent-free conditions. Finally, the palladium-catalyzedcross-coupling reactions of terminal alkynes with(E)-1,2-diiodoalkenes were developed for the synthesis ofunsymmetrical 1,3-butadiynes and 2-ethynylphenol with(E)-1,2-diiodoalkenes for the synthesis of 2-ethynylbenzofurans in one-pot by simple heating using Pd(OAc)₂/CuI catalytic system.6. Three kinds of palladium-catalyzed coupling reactions were studiedincluding: (1) the Stille cross-coupling reactions using thePd(OAc)₂/Dabco catalytic system or the Pd(dba)₂/DAB-Cy catalyticsystem, (2) the ligand-free palladium-catalyzed Suzuki cross-couplingreaction in ionic liquid, and (3) the ammonium chloride-promotedpalladium-catalyzed Ullmann coupling reactions of aryl bromides inwater.