Abstract
A cycloaurated phosphinothioic amide gold(III) complex was supported on amorphous silica with the aid of an imidazolium ionic liquid (IL) physisorbed in the SiO2 pores (SiO2–IL) and covalently bonded to the SiO2 (SiO2@IL). Gold(0) nanoparticles (AuNPs) were formed in situ and subsequently immobilized on the SiO2–IL/SiO2@IL phase. The resulting catalytic systems Au–SiO2–IL and Au–SiO2@IL promoted the solvent-free A3 coupling reaction of alkynes, aldehydes, and amines in high yields under solvent-free conditions with very low catalyst loading and without the use of additives. The Au–SiO2@IL catalyst showed good recyclability and could be reused at least five times with yields of propargylamines of ≥80%. This synthetic method provides a green and low cost way to effectively prepare propargylamines. Additionally, 31P high resolution magic angle spinning (HRMAS) NMR spectroscopy is introduced as a simple technique to establish the Au loading of the catalyst.
Highlights
Propargylamines are versatile synthetic intermediates and important structural elements of numerous natural and synthetic products that show a wide range of biological activities [1,2,3,4,5].Traditionally, these compounds have been synthesized by the nucleophilic attack of metal acetylides on imines or their derivatives, but these reagents are used in stoichiometric amounts, are highly moisture sensitive, and require strictly controlled reaction conditions [6]
During theofcourse of the the Au(III)-complex was transformed into the Sonogashira-type o-alkynylphosphinothioic amide 6 reaction, the Au(III)-complex was transformed into the Sonogashira-type o-alkynylphosphinothioic with of Au(I) nanoparticles, which arewhich the real
We developed an environmentally benign, economically friendly, and sustainable A3 coupling reaction of alkynes, aldehydes, and amines by employing a cycloaurated phosphinothioic amide gold(III) complex immobilized in a silica-supported ionic liquid
Summary
Propargylamines are versatile synthetic intermediates and important structural elements of numerous natural and synthetic products that show a wide range of biological activities [1,2,3,4,5]. These compounds have been synthesized by the nucleophilic attack of metal acetylides on imines or their derivatives, but these reagents are used in stoichiometric amounts, are highly moisture sensitive, and require strictly controlled reaction conditions [6]. The contamination of products with metals is a major problem in pharmaceutical development, since trace amounts of metal contamination could have unwanted effects on biological systems
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