Magnetically Recoverable N-Heterocyclic Carbene–Gold(I) Catalyst for Hydroamination of Terminal Alkynes

Abstract

We prepared a magnetically recoverable gold(I) catalyst by immobilizing an N-heterocyclic carbene–gold(I) complex on magnetite and applied it to the hydroamination of alkynes. By employing 2 mol% of the magnetite-supported gold(I) catalyst, the hydroamination of terminal alkynes proceeded smoothly to provide the corresponding imine in a fair chemical yield. Moreover, after the reaction, the magnetic gold(I) catalyst was readily recovered by use of an external magnet and could be reused up to five times.

Key words

amination - N-heterocyclic carbene complexes - catalysis - imines - supported catalysis

• References and Notes

• 1a Dorel R, Echavarren AM. Chem. Rev. 2015; 115: 9028
• 1b Joost M, Amgoune A, Bourissou D. Angew. Chem. Int. Ed. 2015; 54: 15022
• 1c Hashmi AS. K. Angew. Chem. Int. Ed. 2010; 49: 5232
• 1d Li Z, Brouwer C, He C. Chem. Rev. 2008; 108: 3239
• 2a Anokhin MV, Murashkina AV, Averin AD, Beletskaya IP. Mendeleev Commun. 2014; 24: 332
• 2b Alvarado E, Badaj AC, Larocque TG, Lavoie GG. Chem. Eur. J. 2012; 18: 12112
• 2c Zeng X, Frey GD, Kousar S, Bertrand G. Chem. Eur. J. 2009; 15: 3056
• 2d Corma A, Gonzalez-Arellano C, Iglesias M, Navarro MT, Sanchez F. Chem. Commun. 2008; 6218
• 2e Widenhoefer RA, Han X. Eur. J. Org. Chem. 2006; 4555
• 2f Mizushima E, Hayashi T, Tanaka M. Org. Lett. 2003; 5: 3349
• 3a Zhu Y, Laval S, Tang Y, Lian G, Yu B. Asian J. Org. Chem. 2015; 4: 1034
• 3b Lothschutz C, Szlachetko J, van Bokhoven JA. ChemCatChem 2014; 6: 443
• 3c Egi M, Azechi K, Akai S. Adv. Synth. Catal. 2011; 353: 287
• 3d Corma A, Gonzalez-Arellano C, Iglesias M, Ferreras SP, Sanchez F. Synlett 2007; 1771
• 3e Corma A, Puebla EG, Iglesias M, Monge A, Ferreras SP, Sanchez F. Adv. Synth. Catal. 2006; 348: 1899
• 4a Wang D, Deraedt C, Ruiz J, Astruc D. Acc. Chem. Res. 2015; 48: 1871
• 4b Baig RB. N, Nadagouda MN, Varma RS. Coord. Chem. Rev. 2015; 287: 137
• 4c Dalpozzo R. Green Chem. 2015; 17: 3671
• 4d Rossi LM, Costa NJ. S, Silva FP, Wojcieszak R. Green Chem. 2014; 16: 2906
• 4e Baig RB. N, Varma RS. Chem. Commun. 2013; 752
• 4f Polshettiwar V, Luque R, Fihri A, Zhu H, Bouhrara M, Basset J.-M. Chem. Rev. 2011; 111: 3036
• 4g Schätz A, Reiser O, Stark WJ. Chem. Eur. J. 2010; 16: 8950
• 5a Chen S.-W, Zhang Z.-C, Zhai N.-N, Zhong C.-M, Lee S.-g. Tetrahedron 2015; 71: 648
• 5b Wang Z, Yu Y, Zhang YX, Li SZ, Qian H, Lin ZY. Green Chem. 2015; 17: 413
• 5c Karimi B, Mansouri F, Vali H. Green Chem. 2014; 16: 2587
• 5d Li P, Wang L, Zhang L, Wang G.-W. Adv. Synth. Catal. 2012; 354: 1307
• 5e Yang H, Wang Y, Qin Y, Chong Y, Yang Q, Li G, Zhang L, Li W. Green Chem. 2011; 13: 1352
• 5f Zhang X, Li P, Ji Y, Zhang L, Wang L. Synthesis 2011; 2975
• 5g Phan NT. S, Le HV. J. Mol. Catal. A 2011; 334: 130
• 6a Chen S.-W, Zhang Z.-C, Ma M, Zhong C.-M, Lee S.-g. Org. Lett. 2014; 16: 4969
• 6b Che C, Li W, Lin S, Chen J, Zheng J, Wu J, Zheng Q, Zhang G, Yang Z, Jiang B. Chem. Commun. 2009; 5990
• 6c Hirakawa T, Tanaka S, Usuki N, Kanzaki H, Kishimoto M, Kitamura M. Eur. J. Org. Chem. 2009; 789
• 6d Jacinto MJ, Santos OH. C. F, Jardim RF, Landers R, Rossi LM. Appl. Catal., A 2009; 360: 177
• 6e Mori K, Kanai S, Hara T, Mizugaki T, Ebitani K, Jitsukawa K, Kaneda K. Chem. Mater. 2007; 19: 1249
• 6f Kotani M, Koike T, Yamaguchi K, Mizuno N. Green Chem. 2006; 8: 735
• 6g Hu A, Yee GT, Lin W. J. Am. Chem. Soc. 2005; 127: 12486
• 7a Cano R, Perez JM, Ramon DJ. Appl. Catal., A 2014; 470: 177
• 7b Fujita K, Umeki S, Yasuda H. Synlett 2013; 24: 947
• 7c Fujita K, Umeki S, Yamazaki M, Ainoya T, Tsuchimoto T, Yasuda H. Tetrahedron Lett. 2011; 52: 3137
• 8 A previously reported magnetically recoverable phosphine–gold(I) catalyst: Yang W, Wei L, Yi F, Cai M. Catal. Sci. Technol. 2016; 6 in press; DOI: 10.1039/C5CY02159F

Previously reported magnetically recoverable gold(III) catalysts:
• 9a Sadeghzadeh SM. RSC Adv. 2014; 4: 43315
• 9b Li B, Gao L, Bian F, Yu W. Tetrahedron Lett. 2013; 54: 1063
• 10a Liu X, Ma Z, Xing J, Liu H. J. Magn. Magn. Mater. 2004; 270: 1
• 10b Massart R. IEEE Trans. Magn. 1981; 17: 1247
• 11 Lambardo M, Easwar S, Marco AD, Pasi F, Trombini C. Org. Biomol. Chem. 2008; 6: 4224
• 12 Zeng X, Yang X, Zhang Y, Qing C, Zhang H. Bioorg. Med. Chem. Lett. 2010; 20: 1844
• 13 ¹H NMR and ¹³C NMR data of 3 and 4 are shown in the Supporting Information.
• 14 Selected Data for Compound 5 Black powder. IR (KBr): 3086, 2916, 1651, 1558, 1512, 1458, 1042, 949, 903, 856 cm^–1. Anal.; found (%): C, 2.29; H, 0.33; N, 0.22; Cl, 0.87; Au, 3.36. An X-ray diffraction pattern is shown in the Supporting Information.
• 15 General Procedure To a solution of the alkyne 6 (9 mmol) and the amine 7 (3 mmol) were successively added the indicated amounts of the magnetite-supported gold(I) catalyst 5 and an acid under an argon atmosphere. The reaction mixture was stirred at the indicated temperature for 24 h under an argon atmosphere. The magnetite-supported gold(I) catalyst 5 was separated by magnetic decantation using an external magnet, and the reaction mixture was then transferred out of the reaction vessel, followed by washing of the catalyst 5 with the alkyne 6 three times under argon atmosphere. The chemical yield of the imine 8 and the corresponding ketone were determined by integrating ¹H NMR absorptions referring to an internal standard [4-tert-butyltoluene (1 mmol)], which was added to the reaction mixture. Any organic solvents were not used for washing of the catalyst 5 in order to avoid the vaporization of products and an internal standard during the evaporation of organic solvents in vacuo. Also in the case of catalyst recycling as shown in Table 3, ethynylbenzene (6a), namely no organic solvents was used for washing of the catalyst 5 because this catalytic conversion was sequentially carried out without the evaporation of solvents in vacuo after the magnetic decantation.
• 16a Yuan D, Tang H, Xiao L, Huynh HV. Dalton Trans. 2011; 40: 8788
• 16b Duan H, Sengupta S, Petersen JL, Akhmedov NG, Shi X. J. Am. Chem. Soc. 2009; 131: 12100
• 17 NMR spectra of 8a,²¹ 8b,²² 8d,²³ and 8f ²⁴ are in accordance with those reported in the literature.
• 18 Selected Data for New Compounds (E)-4-Bromo-N-{1-(4-tert-butylphenyl)ethylidene}aniline (8c) White powder; yield: 72%; mp 138.0–138.6 °C. IR (KBr): 2963, 2901, 2866, 1628, 1601, 1474, 1296, 1211, 1007, 853, 841, 586 cm^–1. ¹H NMR (400 MHz, CDCl₃): δ = 7.89 (d, J = 8.4 Hz, 2 H, ArH), 7.45 (t, J = 9.2 Hz, 4 H, ArH), 6.66 (d, J = 8.4 Hz, 2 H, ArH), 2.20 (s, 3 H, CH₃), 1.35 [s, 9 H, C(CH₃)₃]. ¹³C NMR (100 MHz, CDCl₃): δ = 166.0, 154.3, 151.0, 136.5, 132.0, 127.1, 125.5, 121.4, 116.1, 35.0, 31.3, 17.4. Anal. Calcd (%) for C₁₈H₂₀NBr: C, 65.46; H, 6.10; N, 4.24; Br, 24.19. Found (%): C, 65.53; H, 5.98; N, 4.28; Br, 24.11. 4-Bromo-N-(2-octylidene)aniline (8e) Colorless oil; E/Z mixture; yield: 75%. IR (KBr): 2954, 2927, 2857, 1661, 1480, 1365, 1231, 1167, 1069, 1008, 842, 654 cm^–1. ¹H NMR and ¹³C NMR resonances were presented as two signals (indicated as major and minor). ¹H NMR (400 MHz, THF-d ₈): δ = 7.38–7.35 (m, 2 H, ArH), 6.56–6.52 (m, 2 H, ArH), 2.37 (t, J = 7.5 Hz, 2 H, CH₂, major), 2.11 (t, J = 7.9 Hz, 2 H, CH₂, minor), 2.08 (s, 3 H, CH₃, minor), 1.74 (s, 3 H, CH₃, major), 1.69–1.62 (m, 2 H, CH₂, major), 1.51–1.44 (m, 2 H, CH₂, minor), 1.42–1.32 (m, 6 H, (CH₂)₃, major), 1.26–1.17 (m, 6 H, (CH₂)₃, minor), 0.91 (t, J = 6.7 Hz, 3 H, CH₃, major), 0.85 (t, J = 7.0 Hz, 3 H, CH₃, minor). ¹³C NMR (100 MHz, THF-d ₈): δ (major) = 172.0, 152.2, 132.32, 121.85, 115.8, 41.8, 32.5, 29.7, 26.5, 23.3, 19.3, 14.3; δ (minor) = 172.4, 151.7, 132.27, 121.80, 115.6, 34.5, 32.2, 29.9, 27.5, 25.6, 23.1, 14.2. MS (EI): m/z calcd for C₁₄H₂₀NBr: 281.0779 [M⁺]; found: 281.0780.
• 19 In Table 2, entry 6, the magnetically recovered gold(I) catalyst 5 was washed with aniline (7b) after the hydroamination.
• 20 The magnetically recovered gold(I) catalyst 5 was reused for the subsequent hydroamination of the alkyne 6a by the addition of 6a, 7a, and trifluoromethanesulfonic acid to the reaction vessel.
• 21 Mirabdolbaghi R, Dudding T. Org. Lett. 2015; 17: 1930
• 22 Weemers JJ. M, Sypaseuth FD, Bäuerlein PS, van der Graaff WN. P, Filot IA. W, Lutz M, Müller C. Eur. J. Org. Chem. 2014; 350
• 23 Liu Y, Du H. J. Am. Chem. Soc. 2013; 135: 6810
• 24 Anderson LL, Arnold J, Bergman RG. Org. Lett. 2004; 6: 2519