Copper–Zeolites as Catalysts for the Coupling of Terminal Alkynes: An Efficient Synthesis of Diynes

Abstract

CuI‐modified zeolites, especially CuI–USY, proved to be very efficient catalysts for the homocoupling of terminal alkynes. Such heterogeneous catalysts offer a very simple (no added ligand) and convenient synthesis of diynes, including carbohydrate derivatives. A strong influence of the zeolite pore size has been observed, high (quantitative) yields being obtained with zeolites having large internal cages. The role of zeolite acidic sites in the reaction has been pointed out. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Copper nanoparticles supported on silica coated maghemite as versatile, magnetically recoverable and reusable catalyst for alkyne coupling and cycloaddition reactions

“…As shown in Table 6 (entries [7][8][9] pyrrolidine, a cyclic secondary amine, gave similar results to those obtained with morpholine when reacted with benzaldehyde and phenylacetylene, whereas acyclic amines such as diethylamine and diisopropylamine rendered the corresponding A 3 coupling products after longer reaction time and in modest yield.…”

“…For instance, a CuAl hydrotalcite exhibited excellent recyclability at room A c c e p t e d M a n u s c r i p t 5 temperature in acetonitrile, although stoichiometric amounts of N,N,N,N-tetramethylethylenediamine (TMEDA) and catalyst (110 mol%) were required [8]. Copper(I) zeolites were tested for the title reaction in N,N-dimethylformamide (DMF) at 110 °C and 30 mol% copper loading, with no apparent possibility of catalyst recycling [9]. Mizuno and co-workers reported a catalyst consisting of Cu(OH)x/TiO 2 (5 mol% Cu) that did not require the presence of a base and showed high catalytic activity in toluene at 100 °C under 1 atm O 2 [10].…”

Heterogeneously Catalyzed Efficient Alkyne–Alkyne Homocoupling by Supported Copper Hydroxide on Titanium Oxide

“…[21][22][23] In the reported heterogeneous systems with copper-containing hydrotalcites, excess amounts of additives (at least stoichiometric amounts with respect to alkynes) such as NaOH [20] and N,N,N',N'-tetramethylethylenediamine [22] are necessary to attain high yields, high pressure of molecular oxygen (> 20 atm) is necessary, [21] and/or the scope is limited only to ethynylbenzene. [21] In some cases, large amounts of catalysts (110 mol % for copper-containing hydrotalcite system [22] and 10-30 mol % for copper-containing zeolite system [23] ) are required. Therefore, the development of efficient heterogeneous systems without any additives is still challenging and could solve the above-mentioned problems.…”

“…[21][22][23] In the gram-scale reaction of 1 a (20-fold scaled up) for 1 h, 99 % yield of 2 a was obtained. No reaction proceeded in the absence of the catalyst or in the presence of TiO 2 ( 4 ]PF 6 , and copper(I)-phenylacetylide were not effective for the homocoupling (Table 1, entries [4][5][6][7][8].…”

Copper-Impregnated Magnetite as a Heterogeneous Catalyst for the Homocoupling of Terminal Alkynes

“…The presence of a steric hindrance at the aromatic decreased the yield (entry 6). Finally, the reaction could also be performed using the less reactive aliphatic alkynes and the expected products 2 were obtained in all the tested cases (entries [10][11][12][13][14], albeit with slightly lower yields. Encouraged by the success obtained in the homocoupling of terminal alkynes, the hydration reaction of 1,3-diynes to afford the corresponding 2,5-disubstituted furans was examined, which is catalyzed by different copper salts.…”