Pincer Ruthenium Catalyzed Intramolecular Silylation of C(sp²)–H Bonds

Published as part of the Cluster Silicon in Synthesis and Catalysis

Abstract

Reported herein is a highly efficient intramolecular silylation of aromatic C–H bonds catalyzed by a pincer ruthenium complex, giving benzoxasiloles under relatively mild reaction conditions with broad substrate scope and low catalyst loadings. The silylation product can be further converted into a biaryl product by Pd-catalyzed Hiyama–­Denmark cross-coupling reactions.

Key words

C–H bond functionalization - silylation - ruthenium - pincer ligand - C–C coupling

• References and Notes


For reviews on transition-metal-catalyzed C–H bond functionalizations, see:
• 1a Goldberg KI. Goldman AS. Activation and Functionalization of C–H Bonds . ACS Symposium Series 885, American Chemical Society; Washington, DC: 2004: 1-43
• 1b Lyons TW. Sanford MS. Chem. Rev. 2010; 110: 1147
• 1c Rouquet G. Chatani N. Angew. Chem. Int. Ed. 2013; 52: 11726
• 1d Engle KM. Yu J.-Q. J. Org. Chem. 2013; 78: 8927
• 1e Hartwig JF. Larsen MA. ACS Cent. Sci. 2016; 2: 281
• 1f Jones WD. Top. Organomet. Chem. 2016; 56: 67
• 1g Gensch T. Hopkinson MN. Glorius F. Wencel-Delord J. Chem. Soc. Rev. 2016; 45: 2900
• 1h Dixneuf PH. Doucet H. C–H Bond Activation and Catalytic Functionalization I . Vol. 55. Springer International Publishing; New York: 2016
• 1i Dixneuf PH. Doucet H. C–H Bond Activation and Catalytic Functionalization II . Vol. 56. Springer International Publishing; New York: 2016

For reviews on silylation of inert C–H bonds, see:
• 2a Cheng C. Hartwig JF. Chem. Rev. 2015; 115: 8946
• 2b Yang Y. Wang C. Sci. China: Chem. 2015; 58: 1266
• 2c Sharma R. Kumar R. Kumar I. Singh B. Sharma U. Synthesis 2015; 47: 2347
• 2d Xu Z. Huang W.-S. Zhang J. Xu L.-W. Synthesis 2015; 47: 3645
• 2e Xu Z. Xu L.-W. ChemSusChem 2015; 8: 2176

Selected examples for silylation of C(sp³)–H bonds, see:
• 3a Djurovich PI. Dolich AR. Berry DH. J. Chem. Soc., Chem. Commun. 1994; 1897
• 3b Kakiuchi F. Tsuchiya K. Matsumoto M. Mizushima B. Chatani N. J. Am. Chem. Soc. 2004; 126: 12792
• 3c Simmons EM. Hartwig JF. Nature 2012; 483: 70
• 3d Kuninobu Y. Nakahara T. Takeshima H. Takai K. Org. Lett. 2013; 15: 426
• 3e Mita T. Michigami K. Sato Y. Chem. Asian J. 2013; 8: 2970
• 3f Ghavtadze N. Melkonyan FS. Gulevich AV. Huang C. Gevorgyan V. Nat. Chem. 2014; 6: 122
• 3g Li B. Driess M. Hartwig JF. J. Am. Chem. Soc. 2014; 136: 6586
• 3h Murai M. Takeshima H. Morita H. Kuninobu Y. Takai K. J. Org. Chem. 2015; 80: 5407
• 3i Lee T. Hartwig JF. Angew. Chem. Int. Ed. 2016; 55: 8723
• 3j Liu Y.-J. Liu Y.-H. Zhang Z.-Z. Yan S.-Y. Chen K. Shi B.-F. Angew. Chem. Int. Ed. 2016; 55: 13859
• 3k Li W. Huang X. You J. Org. Lett. 2016; 18: 666
• 3l Kon K. Suzuki H. Takada K. Kohari Y. Namikoshi T. Watanabe S. Murata M. ChemCatChem 2016; 8: 2202
• 3m Fukumoto Y. Hirano M. Chatani N. ACS Catal. 2017; 7: 3152

For reviews for transformation of organosilicon compounds, see:
• 4a Komiyama T. Minami Y. Hiyama T. ACS Catal. 2017; 7: 631
• 4b Nakao Y. Hiyama T. Chem. Soc. Rev. 2011; 40: 4893
• 4c Denmark SE. Sweis RF. Acc. Chem. Res. 2002; 35: 835
• 5a Nguyen MH. Smith AB. Org. Lett. 2014; 16: 2070
• 5b Nguyen MH. Smith AB. Org. Lett. 2013; 15: 4872
• 5c Nguyen MH. Smith AB. Org. Lett. 2013; 15: 4258
• 5d Martinez-Solorio D. Hoye AT. Nguyen MH. Smith AB. Org. Lett. 2013; 15: 2454
• 5e Chu T.-Y. Lu J. Beaupre S. Zhang Y. Pouliot J.-R. Wakim S. Zhou J. Leclerc M. Li Z. Ding J. Tao Y. J. Am. Chem. Soc. 2011; 133: 4250
• 5f Chen J. Cao Y. Macromol. Rapid Commun. 2007; 28: 1714

Selected examples for undirected intermolecular silylations of C(sp²)–H bonds:
• 6a Gustavson WA. Epstein PS. Curtis MD. Organometallics 1982; 1: 884
• 6b Toshiyasu S. Yuko T. Touru S. Masato T. Chem. Lett. 1987; 16: 2375
• 6c Ishikawa M. Okazaki S. Naka A. Sakamoto H. Organometallics 1992; 11: 4135
• 6d Ishiyama T. Sato K. Nishio Y. Miyaura N. Angew. Chem. Int. Ed. 2003; 42: 5346
• 6e Lu B. Falck JR. Angew. Chem. Int. Ed. 2008; 47: 7508
• 6f Cheng C. Hartwig JF. Science 2014; 343: 853
• 6g Toutov AA. Liu W.-B. Betz KN. Fedorov A. Stoltz BM. Grubbs RH. Nature 2015; 518: 80
• 6h Cheng C. Hartwig JF. J. Am. Chem. Soc. 2015; 137: 592
• 6i Lee K.-S. Katsoulis D. Choi J. ACS Catal. 2016; 6: 1493
• 6j Rubio-Pérez L. Iglesias M. Munárriz J. Polo V. Passarelli V. Pérez-Torrente JJ. Oro LA. Chem. Sci. 2017; 8: 4811

Selected examples for directed intermolecular silylations of C(sp²)–H bonds:
• 7a Williams NA. Uchimaru Y. Tanaka M. J. Chem. Soc., Chem. Commun. 1995; 1129
• 7b Kakiuchi F. Matsumoto M. Sonoda M. Fukuyama T. Chatani N. Murai S. Furukawa N. Seki Y. Chem. Lett. 2000; 750
• 7c Kakiuchi F. Igi K. Matsumoto M. Chatani N. Murai S. Chem. Lett. 2001; 422
• 7d Kakiuchi F. Igi K. Matsumoto M. Hayamizu T. Chatani N. Murai S. Chem. Lett. 2002; 396
• 7e Kakiuchi F. Matsumoto M. Tsuchiya K. Igi K. Hayamizu T. Chatani N. Murai S. J. Organomet. Chem. 2003; 686: 134
• 7f Tobisu M. Ano Y. Chatani N. Chem. Asian J. 2008; 3: 1585
• 7g Ihara H. Suginome M. J. Am. Chem. Soc. 2009; 131: 7502
• 7h Oyamada J. Nishiura M. Hou Z. Angew. Chem. Int. Ed. 2011; 50: 10720
• 7i Kanyiva KS. Kuninobu Y. Kanai M. Org. Lett. 2014; 16: 1968
• 8 Tsukada N. Hartwig JF. J. Am. Chem. Soc. 2005; 127: 5022
• 9a Simmons EM. Hartwig JF. J. Am. Chem. Soc. 2010; 132: 17092
• 9b Li Q. Driess M. Hartwig JF. Angew. Chem. Int. Ed. 2014; 53: 8471
• 10a Kuznetsov A. Gevorgyan V. Org. Lett. 2012; 14: 914
• 10b Kuznetsov A. Onishi Y. Inamoto Y. Gevorgyan V. Org. Lett. 2013; 15: 2498
• 11a Hua Y. Asgari P. Dakarapu US. Jeon J. Chem. Commun. 2015; 51: 3778
• 11b Hua Y. Jung S. Roh J. Jeon J. J. Org. Chem. 2015; 80: 4661
• 11c Hua Y. Asgari P. Avullala T. Jeon J. J. Am. Chem. Soc. 2016; 138: 7982
• 11d Asgari P. Dakarapu US. Nguyen HH. Jeon J. Tetrahedron 2017; 73: 4052
• 12a Lee T. Wilson TW. Berg R. Ryberg P. Hartwig JF. J. Am. Chem. Soc. 2015; 137: 6742
• 12b Su B. Zhou T.-G. Li X.-W. Shao X.-R. Xu P.-L. Wu W.-L. Hartwig JF. Shi Z.-J. Angew. Chem. Int. Ed. 2017; 56: 1092
• 12c Lee T. Hartwig JF. J. Am. Chem. Soc. 2017; 139: 4879
• 13a Manna K. Zhang T. Lin W. J. Am. Chem. Soc. 2014; 136: 6566
• 13b Manna K. Zhang T. Greene FX. Lin W. J. Am. Chem. Soc. 2015; 137: 2665
• 14 Lin Y. Jiang K.-Z. Cao J. Zheng Z.-J. Xu Z. Cui Y.-M. Xu L.-W. Adv. Synth. Catal. 2017; 359: 2247
• 15a Ureshino T. Yoshida T. Kuninobu Y. Takai K. J. Am. Chem. Soc. 2010; 132: 14324
• 15b Kuninobu Y. Yamauchi K. Tamura N. Seiki T. Takai K. Angew. Chem. Int. Ed. 2013; 52: 1520
• 15c Murai M. Matsumoto K. Takeuchi Y. Takai K. Org. Lett. 2015; 17: 3102
• 15d Murai M. Okada R. Nishiyama A. Takai K. Org. Lett. 2016; 18: 4380
• 15e Murai M. Okada R. Asako S. Takai K. Chem. Eur. J. 2017; 23: 10861
• 16a Zhang Q.-W. An K. Liu L.-C. Yue Y. He W. Angew. Chem. Int. Ed. 2015; 54: 6918
• 16b Zhang Q.-W. An K. Liu L.-C. Zhang Q. Guo H. He W. Angew. Chem. Int. Ed. 2017; 56: 1125
• 17 Shibata T. Shizuno T. Sasaki T. Chem. Commun. 2015; 51: 7802
• 18a Omann L. Oestreich M. Angew. Chem. Int. Ed. 2015; 54: 10276
• 18b Omann L. Oestreich M. Organometallics 2017; 36: 767
• 19 Zhang Y. Fang H. Yao W. Leng X. Huang Z. Organometallics 2016; 35: 181
• 20a Fang H. Hou W. Liu G. Huang Z. J. Am. Chem. Soc. 2017; 139: 11601
• 20b Fang H. Guo L. Zhang Y. Yao W. Huang Z. Org. Lett. 2016; 18: 5624
• 21 General Procedure for Silylation of (Hydrido)silyl Ethers 2 A 5 mL dried Schlenk tube was charged with 1b, (hydrido)silyl ether 2 (0.5 mmol), and hydrogen acceptor (TBE or COE, 1 equiv) under Ar atmosphere. Then the flask was sealed tightly with a Teflon plug and stirred at 80–120 °C for complete conversion. After that, the reaction mixture was cooled to room temperature. Mesitylene (0.5 equiv, 0.25 mmol) was added as an internal standard, and the yield was determined by ¹H NMR spectroscopy. The crude mixture was purified by flash column chromatography (silica gel, PE/EtOAc = 100:1 as eluent) to obtain the benzoxasilole product 3. Data for 3a are given here as an example. The general procedure was followed with Ru complex 1b (2.7 mg, 5.0 μmol), (hydrido)silyl ether 2a (97.2 mg, 0.5 mmol), and COE (65.0 μL, 0.5 mmol) at 80 °C for 24 h. The benzoxasilole product 3a was afforded as a colorless liquid (95.0 mg, 99% yield). ¹H NMR (400 MHz, CDCl₃): δ = 7.56 (d, J = 8.0 Hz, 1 H), 7.43 (t, J = 8.0 Hz, 1 H), 7.32 (t, J = 8.0 Hz, 1 H), 7.25 (d, J = 8.0 Hz, 1 H), 1.58 (s, 6 H), 0.42 (s, 6 H). ¹³C NMR (101 MHz, CDCl₃): δ = 158.0, 134.5, 130.8, 129.8, 126.9, 122.2, 83.5, 32.2, 1.4. These spectroscopic data correspond to reported data.^5d
• 22 It is noteworthy that tertiary (hydrido)silyl ethers bearing two diisopropyl on the silicon atom are unreactive under the Ru-catalyzed silylation conditions.
• 23 Smith AB. Hoye AT. Martinez-Solorio D. Kim W.-S. Tong R. J. Am. Chem. Soc. 2012; 134: 4533
• 24 General Procedure for Hiyama-Denmark Coupling 3a with PhI In an Ar-filled glovebox, a 5 mL dried Schlenk tube was charged with Pd(OAc)₂ (3.4 mg, 15.0 μmol, 5 mol%), PPh₃ (8.6 mg, 33.0 μmol, 11.0 mol%), CH₃ONa (81.0 mg, 1.5 mmol), and p-xylene (1 mL). Then, benzoxasilole 3a (57.8 mg, 0.3 mmol) and PhI (0.60 mmol) were added. The tube was sealed tightly with a Teflon plug under Ar atmosphere. The reaction mixture was stirred at room temperature for 1 h, and subsequently heated at 80 °C for 12 h. Then the reaction mixture was cooled to room temperature, and MeOH (1.5 mL) and 10% NaOH (2 mL) were added under vigorous stirring at 50 °C for 48 h. The resulting solution was extracted with EtOAc and washed with brine (15 mL), dried over anhydrous Na₂SO₄. After filtration and evaporation of the solvent, the crude mixture was purified by flash column chromatography (silica gel, EtOAc/PE = 1:50) to obtain the desired product 4a as a white solid (49.5 mg, 78%, m.p. 68–70 °C). ¹H NMR (400 MHz, CDCl₃): δ = 7.67 (d, J = 8.0 Hz, 1 H), 7.38 (m, 6 H), 7.26 (t, J = 8.0 Hz, 1 H), 7.10 (d, J = 8.0 Hz, 1 H), 1.89 (s, 1 H), 1.49 (s, 6 H). ¹³C NMR (101 MHz, CDCl₃): δ = 146.2, 143.9, 140.0, 132.2, 129.6, 127.9, 127.5, 127.2, 126.2, 125.9, 74.2, 32.7. Spectral data are in agreement with published data.²⁵
• 25 Casarini D. Lunazzi L. Mancinelli M. Mazzanti A. Rosini C. J. Org. Chem. 2007; 72: 7667