Novel oxime-palladacycle supported on clay composite as an efficient heterogeneous catalyst for Sonogashira reaction

Copper-free Sonogashira cross-coupling reactions: an overview

The Sonogashira reaction is a cross-coupling reaction of a vinyl or aryl halide with a terminal alkyne to form a C-C bond. In its original form, the Sonogashira reaction is performed with a palladium species as a catalyst while co-catalyzed by a copper species and a phosphine or amine. The reaction is conducted under mild conditions, i.e., room temperature, aqueous solutions, and the presence of mild bases. Undeniably, the Sonogashira reaction is among the most competent and efficient reactions widely used in organic synthesis. This named reaction has proved useful in many organic synthesis areas, including the synthesis of pharmaceuticals, heterocycles, natural products, organic compounds, complex molecules having biological activities, nanomaterials, and many more materials that we use in our daily lives. The presence of transition metals as a catalyst was indeed essential in the Sonogashira reaction. However, recently, the reaction has been successfully conducted without copper as a co-catalyst and phosphines or amines as bases. In this critical review, we have focused on developments in the Sonogashira reaction successfully performed in the absence of copper complexes, phosphines or amines, which could be of particular advantage in implementing green chemistry principles and making the reactions more achievable from an economic viewpoint.

Porous organic polymer with in situ generated palladium nanoparticles as a phase-transfer catalyst for Sonogashira cross-coupling reaction in water

A new Pd nanoparticle loaded and imidazolium-ionic liquid decorated organic polymer of Pd@PTC-POP was readily fabricated via a Pd(PPh₃)₄ catalysed in situ one-pot Suzuki cross-coupling reaction between imidazolium attached dibromobenzene and 1,3,5-tri(4-pinacholatoborolanephenyl)benzene. Besides the high thermal and chemical stability, the obtained Pd@PTC-POP can be used as a highly active and reusable phase-transfer solid catalyst to promote the Sonogashira coupling reaction in water. The obtained results indicate that the Pd@PTC-POP herein could create a versatile family of solid phase transfer catalysts for promoting a broad scope of reactions carried out in water.

A Pd nanoparticle loaded and imidazolium-ionic liquid decorated organic polymer, which can be used as a highly active phase-transfer solid catalyst to promote the Sonogashira reaction in water, was reported.