Sustainable sonochemical synthesis of N‐protected piperazine‐propargylamines using ionic liquids and CuI

We present a simple method to prepare diverse benzimidazolium and imidazolium ionic liquids (ILs) from common starting materials imidazole and benzimidazole. These green ILs promote the synthesis of N‐substituted piperazinyl propargylamines via a versatile CuI‐catalyzed coupling of aldehydes, second...

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Bibliographic Details
Published in:Applied organometallic chemistry 2024-08, Vol.38 (8), p.n/a
Main Authors: Meeniga, Indira, Shaik, Farheen Banu, Mandapalli, Sreeshitha, Peddiagari, Vasu Govardhana Reddy
Format: Article
Language:English
Subjects:
Aldehydes
Alkynes
Amines
Anions
Chemical synthesis
copper iodide
green chemistry protocol
Imidazole
Ionic liquids
N‐protected piperazines
piperazinyl propargylamines
Recyclability
Substitutes
Substrates
Ultrasonic testing
ultrasonication
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Summary:We present a simple method to prepare diverse benzimidazolium and imidazolium ionic liquids (ILs) from common starting materials imidazole and benzimidazole. These green ILs promote the synthesis of N‐substituted piperazinyl propargylamines via a versatile CuI‐catalyzed coupling of aldehydes, secondary amines, and alkynes under ultrasound. Remarkably, the method works across a broad range of substrates, including diversely substituted aldehydes, heterocycles, cyclic amines, and phenylacetylenes. To understand this versatility, we investigated the influence of IL structure (N‐substitution, anion) on reactivity. Symmetrical long‐chain substituents on the benzimidazolium cation and bromide (Br−) anions led to the most efficient propargylamine formation. This approach offers a sustainable and efficient route to propargylamines with minimal waste and catalyst/IL recyclability over five cycles. We have synthesized a variety and a large number of 17 benzimidazolium and imidazolium ionic liquids (ILs), and these can be used as green solvents towards the synthesis of new N‐substituted piperazinyl propargylamines from the coupling between aldehyde, secondary amine, and alkyne in the presence of copper iodide.
ISSN:0268-2605
1099-0739
DOI:10.1002/aoc.7589