Copper-promoted three-component

A copper-promoted three-component reaction involving N-substituted pyrroles, sodium nitrite, and 2,2,2-trifluoroethanamine hydrochloride yielded two examples of 2-pyrrolo trifluoromethylketoximes 85—86 (20140L1606). The reaction, which involves the in situ generation of 2,2,2-trifluorodiazoethane and nitrite species, displayed lower yields with ester- and cyano-substituted substrates. 

Ramana, T., and Punniyamurthy, T. (2012). Preparation of 2-azido-l-substituted-l//-benzo[7 imidazoles using a copper-promoted three-component reaction and their further conversion into 2-amino and 2-triazolyl derivatives. Chem. Eur. 7., 18, 13279-13283. 

Shi, L., Tu, Y.-Q., Wang, M., Zhang, F.-M., Fan, C.-A. (2004). Microwave-promoted three-component coupling of aldehyde, alkyne, and amine via C-H activation catalyzed by copper in water. Organic Letters, 6, 1001-1003. 

Because of the pure performance of traditional Cu catalysts in the hydrogenation of C02, efforts have been made to find new, more effective catalysts for direct C02 hydrogenation. The problem is to improve selectivity, specifically, to find catalysts that display high selectivity toward methanol formation and, at the same time, show low selectivity in the reverse water-gas shift reaction, that is, in the formation of CO. It appears that copper is the metal of choice for methanol synthesis from C02 provided suitable promoters may be added. Special synthesis methods have also been described for the preparation of traditional three-component Cu catalysts (Cu-ZnO-A1203 and Cu-Zn0-Cr203) to improve catalytic performance for C02 reduction. 

Aminopyridines can be used in other ways copper-catalysed interaction with diazo-ketones and three-component reactions involving an isonitrile and an aldehyde also give imidazo[l,2-a]pyridines such condensations can be promoted using an ionic liquid" or scandium triflate with microwave heating." In the former route, 2-substituted products result and from the latter, 3-aminoimidazo[l,2-a]pyridines are formed. 

Kobayashi and coworkers showed that Lewis add surfactant-combined catalysts such as scandium tris(dodecyl sulfate), Sc(03SCi2H25)3, or copper bis(dodecyl sulfate), Cu(03SCi2H25)2, were efficient catalysts for the three-component Mannich-type reaction, with 73-95% yield being obtained in neat water.Neutral salts such as sodium triflate and sodium iodide catalyzed the condensation reaction in water between preformed imines and silicon enolates, or the three-component Mannich-type reaction using aromatic amines, with 49-93% yields and 0-80% diastereoselectivities. Mechanistic studies indicated that both sodium triflate and the Mannich adduct itself cooperatively promote the reaction. 

Prof. Hao s synthesis commenced with the copper(I) chloride-catalyzed oxidation of the tryptamine derivative to afford ketone 42 [74], A three-component Strecker-type reaction was designed to react the ketone 42 with tryptamine and TMSCN to finish the first ring closure. After examining a series of both Lewis acid and Bronsted acids, the authors found a catalytic amount of TMSOTf promoted the transformation and afforded nitrile intermediate 43, which is ready for the Houben-Hoesch-type cyclization [75]. Treatment by TfOH (trifluoromethanesulfonic acid) [76] in DCM and the... 

A highly related method showed that pyrrole ring formation from 50 to produce indolizines 52 is promoted efficiently by various transition-metal catalysts, such as platinum(II) [17], indium(lll) [17], copper(I) [18,19], gold(I) [18], and silver(I) [18] (Scheme 19.11). It should be noted that these reactions were reported independently by the three research groups at nearly the same time [17-19]. The palladium-catalyzed two-component reaction of alkynylpyridines 53 with aryl halides is a convenient strategy for the synthesis of highly substituted fused pyrroles 55 [20]. 

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