Synthesis, characterization and catalytic performance in enantioselective reactions by mesoporous silica materials funct
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Synthesis, characterization and catalytic performance in enantioselective reactions by mesoporous silica materials functionalized with chiral thiourea‑amine ligand Yaşar Gök1 · Halil Zeki Gök1 Received: 31 August 2020 / Accepted: 10 October 2020 © Springer Nature B.V. 2020
Abstract Chiral heterogeneous catalysts have been synthesized by grafting of silyl derivatives of (1R, 2R)- or (1S, 2S)-1,2-diphenylethane-1,2-diamine on SBA-15 mesoporous support. The mesoporous material SBA-15 and so-prepared chiral heterogeneous catalysts were characterized by a combination of different techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) surface area. Results showed that (1R, 2R)- and (1S, 2S)-1,2-diphenylethane-1,2-diamine were successively immobilized on SBA-15 mesoporous support. Chiral heterogeneous catalysts and their homogenous counterparts were tested in enantioselective transfer hydrogenation of aromatic ketones and enantioselective Michael addition of acetylacetone to β-nitroolefin derivatives. The catalysts demonstrated notably high catalytic conversions (up to 99%) with moderate enantiomeric excess (up to 30% ee) for the heterogeneous enantioselective transfer hydrogenation. The catalytic performances for enantioselective Michael reaction showed excellent activities (up to 99%) with poor enantioselectivities. Particularly, the chiral heterogeneous catalysts could be readily recycled for Michael reaction and reused in three consecutive catalytic experiments with no loss of catalytic efficacies. Keywords Chirality · Enantioselectivity · Heterogeneous catalysis · Mesoporous materials
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1116 4-020-04301-w) contains supplementary material, which is available to authorized users. * Yaşar Gök [email protected] 1
Department of Biomedical Engineering, Bucak Faculty of Technology, Burdur Mehmet Akif Ersoy University, 15300 Bucak/Burdur, Turkey
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Y. Gök, H. Z. Gök
Introduction Catalysis is one of the most important key technologies for the preparation of organic compounds that facilitate the life of human beings [1–3]. Many products such as modern drugs and agrochemicals can proceed under the catalysis of organic reactions in the presence of homogenous or heterogeneous catalysts [4–9]. After the thalidomide tragedy [10–12], the certain drugs have been intended to contain single enantiomer in consistent with the regulations of FDA [13]. Homogeneous enantioselective catalysis is one of the powerful methods used for many years to meet the demand for enantiopure compounds in pharmaceutical field [5–7]. In this method, prochiral starting compounds can be converted into chiral products as a result of the reaction catalyzed by a small amount of a chiral ligand in enantioselective catalysis. To date, a large number of chiral catalysts with very hi
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