Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• conditions, although the transition-metal catalysts were preserved, the reactions require high temperature conditions [76]. In 2008, Wang and co-workers [77] for the first time employed an NHC–Cu(I) complex (2 mol %) and its silica-immobilized version 141 (2 mol %) as catalyst for an A3 coupling reaction

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• coupling reaction for the synthesis of 2-triazolylimidazo[1,2-a]pyridine 74 (Scheme 26) [31]. The reaction involved the use of copper oxide as a catalyst and sodium ascorbate as a reducing agent using triazolyl aldehyde 73, amidine 3 and terminal alkynes 2 as reaction substrates at 70 °C (Scheme 26). Here

• copper catalyst dissolved in ionic liquid to four synthetic cycles. Nanotechnology coupled with heterogeneous catalysis has emerged as an efficient field of catalysis for various organic transformations. Inspired from this Bagdi et al. have reported a nano-copper oxide-mediated three-component A3

Effect of the ortho-hydroxy group of salicylaldehyde in the A³ coupling reaction: A metal-catalyst-free synthesis of propargylamine

• Sujit Ghosh,
• Kinkar Biswas,
• Suchandra Bhattacharya,
• Pranab Ghosh and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 552–557, doi:10.3762/bjoc.13.53

• known as A3 coupling reaction, remains the most common and straightforward method for the synthesis of propargylamine. The A3 coupling reaction is reported under transition-metal-catalyzed conditions using copper [12][17][18][19], gold [17][20][21], silver [17][22], zinc [17][23], nickel [24], iron [25

• possibility for the Glaser coupling of the terminal alkyne as the byproduct [37]. Interestingly, hitherto there is no report for the A3 coupling reaction in the absence of a metal catalyst except of one example in a three-component reaction using an alkynylcarboxylic acid instead of a terminal alkyne [38]. In

• intermediates. Various metal-catalyzed methods for the synthesis of propargylamine. Plausible mechanism for the metal-free A3 coupling from salicylaldehyde. Optimization of metal-catalyst-free A3 coupling reaction. Supporting Information Supporting Information File 320: Experimental procedure, characterization

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• ions, generated from the condensation of amines and aldehydes, represents the most convenient method to access propargylamines [4]. Although numerous examples of the A3-coupling reaction have been reported, there are still many challenges and opportunities for this multicomponent coupling reaction. The

• expansion of its scope to include difficult substrates such as aliphatic primary amines and ammonia, the development of highly enantioselective A3-coupling reactions with broad substrate specificity, and the incorporation of the A3-coupling reaction into tandem processes are all challenges that are expected

• rather low in toluene. In this context, Tang and co-workers very recently presented some original mono- and dinuclear silver–NHC complexes derived from 1-[2-(pyrazol-1-yl)phenyl]imidazole, which displayed good catalytic activity on a model A3-coupling reaction under Zou conditions at a slightly lower

A³-Coupling catalyzed by robust Au nanoparticles covalently bonded to HS-functionalized cellulose nanocrystalline films

• Jian-Lin Huang,
• Derek G. Gray and
• Chao-Jun Li

Beilstein J. Org. Chem. 2013, 9, 1388–1396, doi:10.3762/bjoc.9.155

• ][13]. In addition, the three-component aldehyde–alkyne–amine (A3) coupling and asymmetric aldehyde–alkyne–amine (AA3) coupling reactions have received increasing attention due to the easy formation of high-value product propargylamines [14][15][16]. Notably, the A3 coupling reaction has also been

• performances The A3-coupling reaction of benzaldehyde, piperidine, and phenylacetylene was selected as the probe reaction to examine the catalytic activity of the Au@HS-CNC catalyst. Table 1 summarizes the catalytic performances of the catalyst with different Au-loadings, which were measured by inductively

• optimal Au-loading to be 4.4 mol %. Besides the Au-loading, we also investigated the effects of reaction solvents, temperature and reaction time on the catalytic efficiency. As shown in Table 1, one could conclude from the influence of the reaction time on the activity that the A3-coupling reaction