Nano-sized clinoptilolite as a green catalyst for the rapid and chemoselective N-formylation of amines

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Nano‑sized clinoptilolite as a green catalyst for the rapid and chemoselective N‑formylation of amines Mina Amirsoleimani1 · Mohammad A. Khalilzadeh1 · Daryoush Zareyee1 Received: 10 August 2020 / Accepted: 8 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020

Abstract An ultrasound-assisted, simple, fast and efficient method reported for the chemoselective N-formylation of amines with formic acid in the presence of nanozeolite clinoptilolite (nano-CP) under solvent-free reaction conditions to give the corresponding formamides. The ultrasound increased the rate of the reaction and afforded excellent yields at room temperature. This method has the advantages of high yields, mild conditions, simple methodology, easy work up and short reaction times. The catalyst was characterized by different techniques, was recovered and reused several times without the significant loss of its catalytic performance.

Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s1114​ 4-020-01886​-6) contains supplementary material, which is available to authorized users. * Mohammad A. Khalilzadeh [email protected] 1



Department of Chemistry, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran

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Reaction Kinetics, Mechanisms and Catalysis

Graphic abstract

Keywords  Formylation · Nanozeolite · Clinoptilolite · Amines

Introduction Protection of functional groups is an essential artifice employed to prevent or to modify the reaction of a special functional group during a synthetic sequence. Improvement of the existing methods for protection/deprotection of functional groups constitutes a topic of constant interest. In this context amine protection is an important transformation and can be achieved via divers protecting groups. Among them, formyl group has attracted much attention due to its high versatility and usefulness for the protection of amine functionality in organic molecules [1]. The amide bond is widely utilized in natural products and medicinal intermediates, and about 25% of the known medicines have at least one amide bond. In addition, the formyl group is also applied for the protection of the amino group during peptide synthesis [1]. Formamides are important intermediates in the preparation of amine derivatives and have been widely used in the synthesis of many fine chemicals and pharmaceutically valuable compounds [2]. They are also important precursors for isonitriles [3], ureas [4], isocyanates [5], isothiocyanates [6], catalyst for allylation and hydrosilylation of carbonyls [7–9]. In addition, formyl group is also applied for the protection of the amino group during peptide synthesis [10]. Therefore the

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Reaction Kinetics, Mechanisms and Catalysis

development of an efficient methodology for the synthesis of N-formylated amines is highly essential. By far, classic reagents such as ammonium, methyl or ethyl formate, paraformaldehyde have been used to synthesize formamides with divers catalysts including Silphos ­[PCl3–n(SiO2)n] [11], bic