Transition‐Metal‐Catalyzed Selective Alkynylation of C−H Bonds

Abstract

Alkynylation reactions are one of the most sought‐after synthetic methodologies due to the versatility of C−C triple bond diversifications. Sonogashira coupling was widely used for the synthesis of alkynylated molecules; however, this methodology requires the use of previously halogenated substrates, which is a major drawback. To overcome this issue, a complimentary method, transition‐metal‐catalyzed C−H alkynylation, was emerged as an alternative tool in the recent years. Though the initial reports required the use of either specific directing groups or strong alkynylating agents for effective functionalization, recent studies indicate that transition‐metal‐catalyzed site selective alkynylations can be carried out using mild and readily available alkynylating agents under moderate reaction conditions. In this review, we explain the transition metal cataluyzed site selective alkynylation both C(sp2)−H and C(sp3)−H bonds by emphasizing to the reaction mechanism.

A Triazole‐Based Covalent Gel Loaded with Cu/Pd Bimetallic Nanoparticles for Efficient Catalytic Cross‐Coupling Reactions

“…Among them, Pd-catalyzed Sonogashira-Hagihara and Mizoroki-Heck coupling reactions of aryl or vinyl halides with terminal alkynes or reactive olefins under alkaline conditions are important and commonly used reactions, and the coupling products have been widely used in pharmaceuticals, dyestuff, advanced materials, supramolecular chemistry, etc. [3][4][5] In recent years, the system of bimetallic nanomaterials (NPs) has attracted great attention because of their excellent catalytic activity, selectivity and stability compared to monometallic catalysts. [6,7] Compared with monometallic nanoparticles, there are synergistic interactions between different metals in bimetallic nanoparticles, including electron transfer and exchange, geometrical structure tuning, adsorption and stabilization of reactants and intermediates.…”

“…They have greatly promoted the development of organic chemistry and have been one of the most popular areas of organic chemistry with an indispensable and significance role for the synthesis of complex molecules. Among them, Pd‐catalyzed Sonogashira‐Hagihara and Mizoroki‐Heck coupling reactions of aryl or vinyl halides with terminal alkynes or reactive olefins under alkaline conditions are important and commonly used reactions, and the coupling products have been widely used in pharmaceuticals, dyestuff, advanced materials, supramolecular chemistry, etc [3–5] . In recent years, the system of bimetallic nanomaterials (NPs) has attracted great attention because of their excellent catalytic activity, selectivity and stability compared to monometallic catalysts [6,7] .…”

Transition-metal-catalyzed C–H bond alkylation using olefins: recent advances and mechanistic aspects

“…1–11 Within the domain, transition metal catalysis forms the largest, ever expanding subset contributing to the broad spectrum of applications that ranges from organic synthesis to petrochemical processing. 12–20 In this context, the development of novel methods to access arylation, 21–24 alkenylation 25–27 and alkynylation of C–H bonds 28 has gained tremendous attention. In comparison, alkylative C–H functionalizations have remained fairly scarce in the realm of transition metal catalysis due to the inert nature of the C–H bond, the large kinetic barrier for the C–H bond cleavage and its ubiquitous nature.…”

Dinitrogen Binding and Functionalization in Low-Coordinate Alkynyliron Complexes

“…Transition metal alkynyl complexes have seen an impressive growth in attention throughout the last four decades. [1][2] Not only have they been studied for their bonding properties, 3 the syntheses of multimetallic clusters, [4][5][6][7] and catalysis, [8][9][10][11][12][13] but alkynyl complexes have a multitude of practical applications such as in nonlinear optics, [14][15][16] luminescence, [17][18][19] and therapeutics. [20][21] In particular, iron alkynyl species have been studied as intermediates in iron-catalyzed organic transformations [22][23][24] and towards their use as molecular wires.…”