Palladium‐Based Catalytic Systems for the Synthesis of Conjugated Enynes by Sonogashira Reactions and Related Alkynylations

Abstract

Conjugated alkynes are recurring building blocks in natural products, a wide range of industrial intermediates, pharmaceuticals and agrochemicals, and molecular materials for optics and electronics. The palladium-catalyzed cross-coupling between sp(2)-hybridized carbon atoms of aryl, heteroaryl, and vinyl halides with sp-hybridized carbon atoms of terminal acetylenes is one of the most important developments in the field of alkyne chemistry over the past 50 years. The seminal work of the 1970s has initiated an intense search for more general and reliable reaction conditions. The interest in the catalytic activation of demanding substrates, the need to minimize the consumption of depletive resources, and the search for easy access to an increased variety of functionalized enynes has led to the current generations of high-turnover catalysts. This Review gives an overview of the highly efficient palladium catalyst systems for the direct alkynylation of C(sp(2)) halides with terminal alkynes, both in homogeneous and heterogeneous phases.

Empowering a transition-metal-free coupling between alkyne and alkyl iodide with light in water

“…Research towards the synthesis of alkynes has been pivotal throughout the history of organic chemistry. Methods to synthesize alkyne compounds consist of two types: the first is the direct formation of the triple bond such as the Corey-Fuchs reaction 12 and the SeyferthGilbert homologation 13 ; and the second involves modifications on the basis of a pre-existing triple bond 14,15 . Diverse metalcatalysed alkyne couplings, including the Glaser-Hay coupling, the Cadiot-Chodkiewicz coupling, the Eglinton coupling, the Castro-Stephens coupling and the Sonogashira coupling, have found wide applications in the synthesis of pharmaceuticals, fine chemicals and polymeric materials 14 .…”

Synthesis and Characterization of Triphenylphosphine Adducts of Ferrocene-Based Palladacycles and Their Performance in the Suzuki and Sonogashira Reactions with Bromo- and Chloroarenes

“…Moreover, the use of a copper reagent results in contamination of the coupling products with metal residues. Thus a lot of efforts are underway toward developing new palladium catalysts and copper-and amine-free conditions for the Sonogashira reaction [23][24][25][26]. Among them, a wide variety of palladacycles have been reported and successfully used in the Sonogashira reaction [5,[27][28][29][30].…”

Iron Powder-CuI Cooperative Catalytic System in Sonogashira Cross-Coupling Reaction

“…[1][2][3][4] This protocol has been widely used as a powerful synthetic tool for the synthesis of prevalent and valuable intermediates for pharmaceuticals and organic materials. [1][2][3][4] Since the coupling intrinsically catalyzed by Pd(PPh 3 ) 4 and CuI was discovered in 1975, 5 many elegant catalytic systems which facilitate such a coupling under the milder and cheaper conditions have been developed by the tuning of a ligand combined with the kind of palladium catalysts. [1][2][3][4] Furthermore, besides such palladium based systems, several catalytic systems which are inexpensive and benign to the environment have been developed for both an academic viewpoint and a large scale industrial application.…”