Oxidative Heck reactions provide a facile and efficient route to carbon-carbon bond formations. This review is divided into two main sections, the first consisting of oxidative Heck reactions of organometallic compounds such as organoboranes, organosilanols and arylstannanes, and the second covering oxidative Heck reactions via C-H activation, a topic which has become an attractive theme in organic synthesis. 1 Introduction 2 Oxidative Heck Reactions of Organometallic Compounds 2.1 With Palladium(II) Catalysts 2.1.1 Ligand-Free Reactions 2.1.1.1 Anaerobic 2.1.1.2 Aerobic 2.1.2 Ligand-Based Reactions 2.1.2.1 Aerobic 2.1.2.2 Anaerobic 2.1.3 Asymmetric Reactions 2.1.3.1 Aerobic 2.1.3.2 Anaerobic 2.1.4 With Polymer-Supported Palladium(II) Catalysts 2.2 With Other Transition-Metal Catalysts 2.3 With Other Organometallic Compounds 3 Oxidative Heck Reactions of C-H Compounds 3.1 Catalytic Reactions 3.1.1 Intermolecular Reactions 3.1.1.1 Anaerobic 3.1.1.2 Aerobic 3.1.2 Intramolecular Reactions 3.1.2.1 Anaerobic 3.1.2.2 Aerobic 4 Conclusions and Outlook

A novel amine-functionalized ionic liquid-based periodic mesoporous organosilica (PMO-IL-NH₂) was prepared and characterized and its catalytic performance was investigated in the Knoevenagel reaction. PMO-IL-NH₂ was prepared by simultaneous co-condensation of 3-aminopropyltrimethoxysilane, an ionic liquid and tetramethoxysilane in the presence of a surfactant template under acidic conditions. The material was characterized by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic application of PMO-IL-NH₂ was then successfully carried out in the Knoevenagel condensation of a variety of different aldehydes with ethyl cyanoacetate under solvent-free conditions at room temperature, giving high to excellent yields of the corresponding products. The catalyst was also recovered and reused several times without a significant decrease in either activity or product selectivity. The TEM image and nitrogen sorption analysis of the recovered catalyst after the fifth reaction cycle confirmed its high stability and durability under the applied reaction conditions.

The application of a novel palladium containing ionic liquid based periodic mesoporous organosilica (Pd@PMO-IL) catalyst in the aerobic oxidation of primary and secondary alcohols under molecular oxygen and air atmospheres is investigated. It was found that the catalyst is quite effective for the selective oxidation of several activated and non-activated alcoholic substrates. The catalyst system could be successfully recovered and reused several times without any significant decrease in activity and selectivity. Moreover, the hot filtration test, atomic absorption spectroscopy (AA) and kinetic study with and without selective catalyst poisons showed that the catalyst works in a heterogeneous pathway without any palladium leaching in reaction solution. Furthermore, nitrogen-sorption experiment and transmission electron microscopy (TEM) image proved the superior stability of high-ordered PMO-IL mesostructure during reaction process. TEM image also confirmed the presence of well-distributed Pd-nanoparticles in the uniform mesochannels of the material. These observations can be attributed to the ionic liquid nature of PMO-IL mesostructure which facilitates the reaction through production, chemical immobilization and stabilization of active palladium nanoparticles, as well as preventing Pd-agglomeration during overall process.