The Hydroamination of methyl acrylates with amines over zeolites
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Catalysis Letters Vol. 102, Nos. 3–4, August 2005 ( 2005) DOI: 10.1007/s10562-005-5854-6
The Hydroamination of methyl acrylates with amines over zeolites Jana Horniakovaa, Kenichi Komuraa, Hisashi Osakia, Yoshihiro Kubotaa,b, and Yoshihiro Sugia,* a Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Gifu, 501-1193 Japan Department of Materials Science and Engineering, Graduate School of Engineering, Yokohama National University, Yokohama 240-8501 Japan
b
Received 16 December 2004; accepted 29 March 2005
H-form zeolites, H-FAU and H-BEA have been studied as heterogeneous catalysts for the hydroamination. They catalyzed the reaction of methyl acrylate with aniline to give N-[2-(methoxycarbonyl)ethyl]aniline (1) as a main product. H-BEA and H-FAU zeolites efficiently catalyzed the hydroamination to afford anti-Markovnikov adduct as a main product. The conversion of aniline around 55–85% was achieved within 18 h over H-BEA and H-FAU zeolites with SiO2/Al2O3 molar ratio of 25–30; however, the formation of N,N-bis[2-(methoxycarbonyl)ethyl]aniline (2) as a product of double addition of methyl acrylate to aniline has also been observed as a by-product over H-BEA and H-FAU catalysts. The influences of the reaction parameters such as temperature and catalyst amount, and type of a,b-unsaturated esters and amines have been also investigated. KEY WORDS: zeolite; hydroamination; methyl acrylate; aniline.
1. Introduction As countless examples of nitrogen-containing organic molecules can be found in pharmaceutical, agricultural, and industrial areas, the synthesis of carbon–nitrogen bonds is of fundamental interest in organic chemistry. Among the numerous methods developed for the synthesis of nitrogen-containing building blocks such as amines, imines, and enamines, the most efficient and atom-economical method is the direct addition of amines to carbon–carbon double and triple bonds. Most of the studies are based on the addition of aniline or substituted anilines to aliphatic or aromatic alkynes [1]. This is probably related to lower Lewis basicity of the aniline nitrogen atom compared to aliphatic amine one. The lower Lewis basicity is a consequence of the mesomeric effect between the amine lone-pair and the phenyl group. Recently, there have been several reports on the hydroamination of aniline catalyzed by transition metals such as palladium [2–4], ruthenium [5], nickel [6], and rhodium [7]. It was also possible to perform the hydroamination of acrylic acid derivatives with cyclic amines [2,6,8–11]. To the present date, ion-exchanged BEA zeolite, Cu(I)/H-BEA, Rh(I)/H-BEA and Zn/H-BEA, have been reported as active catalysts for the heterogeneous hydroamination, such as the cyclization of 6-aminohex1-yne and 3-aminopropylvinyl ether and the addition of aniline to phenylacetylene [12–15]. On the contrary, H-BEA was the most active catalyst for the hydroamination of 1,3-cyclohexadiene with aniline, while the incorporation of Zn2+ (Zn/H-BEA) led to the decrease of catalytic activity [16]. Recent
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