First report of a nano‐Cu₂O‐catalyzed protocol for homo‐coupling reaction of terminal alkynes in water/ionic liquid medium

Abstract

A new, efficient and green protocol for the nano-Cu 2 O-catalyzed homo-coupling reaction of terminal alkynes has been developed, using water/ionic liquid as an environmentally friendly solvent. Moreover, the system also allows the synthesis of unsymmetric 1,3-diynes by cross-coupling of two different terminal alkynes. It is noteworthy that the nano-Cu 2 O-catalyzed methodology is a good supplement to copper catalyst for the Glaser-type homo-coupling reaction.Additional supporting information may be found in the online version of this article at the publisher's web site. Scheme 2. Nano-Cu 2 O-catalyzed coupling reaction of 1-ethynylbenzene and 1-ethynyl-4-methoxybenzene.Scheme 3. Possible mechanism for the nano-Cu 2 O-catalyzed coupling reaction of terminal alkyne.

A walk around the application of nanocatalysts for cross-dehydrogenative coupling of C–H bonds

“…Concurrently, Tang and Liu along with their co-workers reported an example of unsymmetrical 1,3-diyne synthesis via the reaction of phenylacetylene with 4-methoxyphenylacetylene using 10 mol% of Cu 2 O NPs as catalyst in a binary solvent H 2 O/TBAB (tetrabutylammonium bromide) in a 1 : 4 ratio. 56 However, the target diyne was isolated in only 30% yield along with a mixture of both possible homo-coupling products.…”

“…53 Without slight doubt, the most straightforward approach to the synthesis of symmetrical 1,3-diynes is the oxidative homo-coupling of two terminal alkynes, which known as the Glaser coupling. 54 Although numerous efficient metal nanocatalysts have been reported for this interesting and useful reaction (Table 4), 55–70 the nanometal-catalyzed hetero-coupling reactions between two different alkynes were less developed. Noteworthy, due to the competitive reaction pathways between homo-coupling and hetero-coupling reactions, synthesis of unsymmetrical 1,3-diynes is more difficult compared to the symmetrical ones.…”

Efficient Ru-Catalyzed Electrochemical Homo- and Heterocoupling Reaction of Terminal Alkynes: Synthesis, In Vitro Anticancer Activity, and Docking Study

“…The coupling of terminal alkynes could achieve a diyne fragment substituted with various functionalities attached to both sides resulting in symmetrical or unsymmetrical 1,3-diynes. The straightforward synthesis of homocoupled 1,3-diynes was reported by Glaser–Eglinton–Hay–Cadiot–Chodkiewicz with adequate results. − In the standard synthesis of 1,3-diynes, copper is assigned to be an outstanding catalyst. − Apart from that, some bimetallic metal additives with copper were used for the preparation of 1,3-diynes from different alkyne sources. − In addition to that, some nanocomposites, − charge-transfer catalysts, and visible light-induced , reaction media acted as active catalysts to afford these diyne building blocks. Likewise, there are numerous methodologies that exist in the literature for the synthesis of 1,3-diyne moieties. − However, the push for this methodology is still continuing and under strong consideration by various academia along with pharmaceutical industries.…”

Cu Catalyst Supported on Nitrogen and Phosphorus Co-Doped Carbon Nanosheets for Homocoupling of Terminal Alkynes Using CO2 as a Soft Oxidant

“…In contrast to homogeneous catalysts, Cu-based heterogeneous catalysts are more attractive from the viewpoint of sustainable chemistry owing to their recyclability. The reported heterogeneous Cu catalysts with O 2 as the oxidant for the coupling generally involve nano-Cu 2 O, Cu nanotubes, Cu–Cu 2 O–C nanocomposites, Cu/TiO 2 , Cu/SiO 2 , Cu-doped TiO 2 , Cu­(OH) x /TiO 2 , Cu­(OH) x /OMSs (OMS, manganese oxide-based octahedral molecular sieve), Cu–Al layered double hydroxides (CuAl–LDHs), Cu-based metal–organic frameworks, , NHC–Cu complexes immobilized on carbon materials, and various heterogenized Cu salts. − …”