A versatile three‐component coupling of aldehydes, alkynes and amines has been developed, catalyzed by Ni2+‐exchanged Y‐zeolite, which acts as an environmentally benign, recyclable, efficient and heterogeneous catalyst. This three‐component (A3) coupling (reported for the first time to proceed under nickel catalysis) is carried out under solvent‐free conditions, and the corresponding propargylamines are obtained in good to excellent yields.

No abstract

First simultaneous generation and utilization of both copper-triazole and -ketenimine intermediates in copper-catalyzed sulfonyl azide-alkyne cycloaddition reactions is achieved for the one-pot synthesis of triazolopyrimidines via a novel copper-catalyzed multicomponent cascade of sulfonyl azides, alkynes, and azirines. Significantly, the reaction proceeds under very mild conditions in good yields.

Top Cat! Cu(II)-hydrotalcite (HT) is used as a catalyst for the regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles by [3+2] cycloaddition of various azides and alkynes. The catalyst enjoys advantages such as faster reactivity, good stability, reusability, high catalytic activity without any additives at room temperature, and does not require a nitrogen atmosphere for this "click-chemistry" transformation.

Transition metal and organic catalysts have established their own domains of excellence. It has been expected that merging the two unique domains should provide complimentary or unprecedented opportunities in converting simple raw materials to functional products. N-heterocyclic carbenes alone are excellent organocatalysts. When used with transition metals such as copper, N-heterocyclic carbenes are routinely practiced as strong-coordinating ligands. Combination of an N-heterocyclic carbene and copper therefore typically leads to deactivation of either or both of the two catalysts. Here we disclose the direct merge of copper as a metal catalyst and N-heterocyclic carbenes as an organocatalyst for relay activation of alkynes. The reaction involves copper-catalysed activation of alkynes to generate ketenimine intermediates that are subsequently activated by an N-heterocyclic carbene organocatalyst for stereoselective reactions. Each of the two catalysts (copper metal catalyst and N-heterocyclic carbene organocatalyst) accomplishes its own missions in the activation steps without quenching each other.

A novel one-pot azide-alkyne/ketenimine-nitrone cycloaddition sequence that is induced by copper(I) and allows the transformation of sulfonyl azides, alkynes, and nitrones to highly substituted imidazolidin-4-ones is described. The corresponding heterogeneous version utilizing Cu(I)-modified zeolites as recyclable heterogeneous catalysts shows marginally improved yield and diastereoselectivity.

Herein, we report aza-aromatics based organic mediators as a readily accessible alternative to the traditional approach of using transition metal catalyst systems for the activation of alcohols in borrowing hydrogen reactions.

A heterogeneous and commercially available nanoscale iron catalyst for direct N- and C-alkylation reactions of anilines and methylketones with alcohols under hydrogen autotransfer conditions.