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2,5‐disubstituted N,N'‐alkylpiperazines represent an interesting target in organic synthesis both for pharmaceutical or agrochemical applications and as a promising class of ligands in coordination chemistry. We report here a microwave‐enhanced synthesis of these compounds starting from non‐activated N‐alkyl aziridines in the presence of catalytic amounts of simple ammonium metallates. A remarkable TOF of 2787.9 h−1 has been observed in the case of [TBA]2[ZnI4] as the catalyst (catalyst loading 0.1 mol %) and with an almost complete selectivity (up to 97 %) in favor of both diastereoisomers (meso and chiral form) of the target 2,5‐disubstituted piperazines, obtained in 1 : 1 ratio. The two isomers are easily separated, because the meso form precipitates in pure from the reaction crude. A stereochemical investigation and the unprecedented isolation of 2,6‐disubstituted N,N'‐alkylpiperazines allowed us to shed light on the reaction mechanism. [ABSTRACT FROM AUTHOR]

An enantioselective phosphine‐catalyzed [3+2] cycloaddition between aza‐aurones and allenoates is here described. The reaction proceeded under mild reaction conditions to afford 2‐spirocyclopentyl indolin‐3‐one derivatives as single γ‐isomer and with high levels of stereocontrol. [ABSTRACT FROM AUTHOR]

The development of alternative benign reaction conditions to perform multicomponent reactions is an interesting and desirable strategy to increase the sustainability of organic synthesis. In this paper, we report a new version of A3‐coupling MCR for the preparation of differently substituted propargylamines starting from aldehydes, alkynes and amines in an acidic DES as reaction media, under dielectric heating, and in the presence of a tetraaza‐macrocyclic silver complex as catalyst. The reaction scope is broad in terms of aldehyde partners. Electron‐rich phenylacetylenes are the more reactive alkynes partners, whereas the nature of the amine is the more serious limitation as only secondary cyclic amines are tolerated. [ABSTRACT FROM AUTHOR]

The Cover Feature shows the synthesis of substituted indolo[1,2‐a]quinoline‐5(6H)‐ones starting from 1‐(2‐ethynylphenyl)‐1H‐indoles and N‐oxides by a gold‐catalyzed oxidation of the triple bond, followed by an acid‐promoted intramolecular cyclization at the indole C‐2 position. More information can be found in the Research Article by E. Brambilla, V. Pirovano and co‐workers (DOI: 10.1002/ejoc.202400083). Cover design by Dominica Del Grosso...By Elisa Brambilla; Mariaclara Gugiatti; Silvia Rizzato; Giorgio Abbiati and Valentina PirovanoReported by Author; Author; Author; Author; Author [Extracted from the article]

2,5-disubstituted N,N'-alkylpiperazines represent an interesting target in organic synthesis both for pharmaceutical or agrochemical applications and as a promising class of ligands in coordination chemistry. We report here a microwave-enhanced synthesis of these compounds starting from non-activated N-alkyl aziridines in the presence of catalytic amounts of simple ammonium metallates. A remarkable TOF of 2787.9 h -1 has been observed in the case of [TBA] 2 [ZnI 4 ] as the catalyst (catalyst loading 0.1 mol %) and with an almost complete selectivity (up to 97 %) in favor of both diastereoisomers (meso and chiral form) of the target 2,5-disubstituted piperazines, obtained in 1 : 1 ratio. The two isomers are easily separated, because the meso form precipitates in pure from the reaction crude. A stereochemical investigation and the unprecedented isolation of 2,6-disubstituted N,N'-alkylpiperazines allowed us to shed light on the reaction mechanism., (© 2024 The Authors. Chemistry - An Asian Journal published by Wiley-VCH GmbH.)