Palladium-Catalyzed Allylation of Polyfluoroarenes with Allylic Pivalates

Abstract

An efficient 1,5-cyclooctadiene–PdCl₂/dicyclohexyl(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphine (XPhos) catalytic system was developed for C–H allylation of polyfluoroarenes with allylic pivalates. The reactions showed excellent functional-group tolerance, good yields, and high regioselectivities. Mechanistic investigations supported a (π-allyl)palladium complex pathway through a directed oxidative addition of the allylic pivalate to palladium, followed by sequential nucleophilic attack by the polyfluorobenzene and reductive elimination. In a gram-scale reaction, a palladium loading of 0.5 mol% was enough to afford the required product in good yield.

Key words

polyfluoroarenes - allylation - palladium catalysis - C–H functionalization - fluoro compounds

• References and Notes

• 1a Purser S. Moore PR. Swallow S. Gouverneur V. Chem. Soc. Rev. 2008; 37: 320
• 1b Müller K. Faeh C. Diederich F. Science 2007; 317: 1881
• 1c Wang J. Sánchez-Roselló M. Aceña JL. del Pozo C. Sorochinsky AE. Fustero S. Soloshonok VA. Liu H. Chem. Rev. 2014; 114: 2432
• 1d Jiang T. Zhou Y. Chen Z. Sun P. Zhu J. Zhang Q. Wang Z. Shao Q. Jiang X. Li B. Chen K. Jiang H. Wang H. Zhu W. Shen J. ACS Med. Chem. Lett. 2015; 6: 602
• 1e Schwehm C. Li J. Song H. Hu X. Kellam B. Stocks MJ. ACS Med. Chem. Lett. 2015; 6: 324
• 1f Hansen KB. Hsiao Y. Xu F. Rivera N. Clausen A. Kubryk M. Krska S. Rosner T. Simmons B. Balsells J. Ikemoto N. Sun Y. Spindler F. Malan C. Grabowski EJ. J. Armstrong JD. III. J. Am. Chem. Soc. 2009; 131: 8798
• 2 Jia X. Wang J. Ding X. Yang J. Li N. Zhao N. Huang Z. J. Org. Chem. 2015; 80: 10874
• 3a Meyer EA. Castellano RK. Diederich F. Angew. Chem. Int. Ed. 2003; 42: 1210
• 3b Murphy AR. Fréchet JM. J. Chem. Rev. 2007; 107: 1066
• 3c Babudri F. Farinola GM. Naso F. Ragni R. Chem. Commun. 2007; 1003
• 4a Roberts RM. Khalaf AA. Friedel–Crafts Alkylation Chemistry: A Century of Discovery . Marcel Dekker; New York: 1984
• 4b Kodomari M. Nawa S. Miyoshi T. J. Chem. Soc., Chem. Commun. 1995; 1895
• 4c Hayashi R. Cook GR. Org. Lett. 2007; 9: 1311
• 5a Weaver J. Senaweera S. Tetrahedron 2014; 70: 7413
• 5b Ahrens T. Kohlmann J. Ahrens M. Braun T. Chem. Rev. 2015; 115: 931
• 5c Amii H. Uneyama K. Chem. Rev. 2009; 109: 2119
• 5d Lafrance M. Rowley CN. Woo TK. Fagnou K. J. Am. Chem. Soc. 2006; 128: 8754
• 5e He M. Soulé J.-F. Doucet H. ChemCatChem 2014; 6: 1824
• 5f Fang X. Huang Y. Chen X. Lin X. Bai Z. Huang K.-W. Yuan Y. Weng Z. J. Fluorine Chem. 2013; 151: 50
• 5g Sun L. Rong M. Kong D. Bai Z. Yuan Y. Weng Z. J. Fluorine Chem. 2013; 150: 117
• 6 For a recent review, see: Cristina Silva Costa D. Arab. J. Chem. 2017; DOI: 10.1016/j.arabjc.2017.07.017.
• 7a Kiyotsuka Y. Acharya HP. Katayama Y. Hyodo T. Kobayashi Y. Org. Lett. 2008; 10: 1719
• 7b Vinogradov AS. Krasnov VI. Platonov VE. Russ. J. Org. Chem. 2008; 44: 95
• 7c Pigge FC. Synthesis 2010; 1745
• 8 Fan S. Chen F. Zhang X. Angew. Chem. Int. Ed. 2011; 50: 5918
• 9 Yu Y.-B. Fan S. Zhang X. Chem. Eur. J. 2012; 18: 14643
• 10 Yao T. Hirano K. Satoh T. Miura M. Angew. Chem. Int. Ed. 2011; 50: 2990
• 11 Xie W. Chang S. Angew. Chem. Int. Ed. 2016; 55: 1876
• 12a Yang G. Yu Z. Jiang X. Yu C. Tetrahedron Lett. 2015; 56: 4689
• 12b Yang G. Jiang X. Liu Y. Li N. Yin G. Yu C. Asian J. Org. Chem. 2016; 5: 882
• 12c Yang G.-H. Liu M. Li N. Wu R. Chen X. Pan L.-L. Gao S. Huang X. Wang C. Yu C.-M. Eur. J. Org. Chem. 2015; 616
• 13 Yu C. Hu G. Zhang C. Wu R. Ye H. Yang G. Shi X. J. Fluorine Chem. 2013; 153: 33
• 14 1,2,3,4,5-Pentafluoro-6-[(2E)-3-phenylprop-2-en-1-yl]benzene (4a); Typical Procedure COD–PdCl₂ (5 mol%), XPhos (10 mol%), Cs₂CO₃ (1.2 mmol, 1.2 equiv), and toluene (3 mL) were added sequentially to a Schlenk tube containing allylic pivalate (E)-3a (1.0 mmol, 1.0 equiv) and pentafluorobenzene (1a; 2.0 mmol, 2.0 equiv) under argon, and the mixture was stirred at 120 ℃ (oil bath) for 8 h until the reaction was complete (TLC). The mixture was then diluted with EtOAc (40 mL), washed with brine (3 × 20 mL), and dried (Na₂SO₄). After filtration and evaporation of the solvent, the residue was purified by chromatography (silica gel, hexane) to give a white solid; yield: 279 mg (98%); mp 62–64 °C. ¹H NMR (600 MHz, CDCl₃): δ = 7.33–7.25 (m, 4 H), 7.24–7.20 (m, 1 H), 6.47 (d, J = 15.7 Hz, 1 H), 6.21 (dt, J = 15.7, 6.7 Hz, 1 H), 3.59 (dd, J = 6.7, 1.3 Hz, 2 H). ¹³C NMR (151 MHz, CDCl₃): δ = 145.00 (dm, J = 246.4 Hz), 139.87 (dm, J = 252.4 Hz), 137.52 (dm, J = 250.4 Hz), 136.57, 132.44, 128.55, 127.64, 126.19, 124.24, 113.23 (t, J = 19.1 Hz), 25.60. ¹⁹F NMR (565 MHz, CDCl₃): δ = –143.90 (dd, J = 22.3, 8.4 Hz, 2 F), –157.23 (t, J = 22.3 Hz, 1 F), –162.48 (td, J = 22.3, 8.4 Hz, 2 F). MS (EI): m/z = 284 [M]⁺.