Palladium - Catalyzed Conversion Of Alkynes: Chlorobenzene Accelerating Effect Coupled With Carbonylated Sonogashira

Palladium catalyzed coupling reaction is very important method to form carbon-carbon bonds. Palladium catalyzed reaction showed the excellent applicability, and promoted the process of transition metal catalysis, especially exhibiting unique advantages on building carbon-carbon bonds. Sonogashira coupling reaction is a powerful weapon to build the spC-sp2C bondes. Palladium catalyzed Sonogashira coupling reaction is moderated, effective and has the good functional compatibility. Based on our recent findings of nonclassic ligand accelerating effect for palladium catalyzed reaction, this dissertation focuse on the Pd catalyzed reactions. The main content are enclosed as the following.First, a ubiquitous accelerating effect of chlorobenzene (PhCl) was observed unexpectedly in the Pd-catalyzed cascade Sonogashira-hydroarylation reaction which were developed to build tri-substituted olefins. The combined PhCl/Pd system could be successfully applied for the synthesis of symmetrical and unsymmetrical tri substituted olefins. Mechanistic investigation including the reaction of acetylene and iodobenzene in CH3OD and the experiment of different halogenated aromatics, which enabled us to propose a mechanism of the reaction system.Second, based on palladium and chlorobenzene catalytic system, two extensive π-conjugated systems were constructed from 1,3-diiodobenzene via the Pd-catalyzed Sonogashira coupling, sequential Suzuki-Miyaura coupling, and hydroarylation reactions with the aid of a catalytic amount of PhCl. Experiments showed that the effect of chlorobenzene widely existed in palladium catalysis of organic reactions, PhCl is a good additive, combined with a variety of organic reactions that is a way to build large conjugated system.Thirdly, a neat carbonylative Sonogashira-coupling reaction was developed with "super-active ester" as the carbonyl electrophiles, which provides a clean and efficient synthetic protocol for a wild spectrum of ynone compounds under CO-, Cu-, ligand- and base-free condition. The aryl and alkyl, naphthenic, heterocyclic aromatic hydrocarbons, ferrocene, polycyclic aromatic hydrocarbons embodies the functional groups tolerance of the reaction system. The superior activity of triazine ester was rationalized by the strong electron-withdrawing ability and the unique affinity of triazine on palladium. Mechanistic experiment clearly demonstrated the ortho-palladation of triazine plays a crucial role for the highly efficient C-O activation.