A Borane-Catalyzed Metal-Free Hydrosilylation of Chromones and Flavones

Published as part of the Cluster Silicon in Synthesis and Catalysis

Abstract

A Piers-type hydrosilylation of chromones and flavones has been successfully realized for the first time using 0.1 mol % of borane catalyst generated in situ by hydroboration of pentafluorostyrene with HB(C₆F₅)₂ to afford a variety of chromanones and flavanones in 60–99% yields. An attempt for the asymmetric transformation with chiral diyne and HB(C₆F₅)₂ gave chromanones and flavanones in high yields with up to 32% ee.

Key words

hydrosilylation - chromones - flavones - chromanones - flavanones - borane catalyst - alkene - chiral diyne

• References and Notes

• 1a Chemistry of Heterocyclic Compounds: Chromens, Chromanones, and Chromones. Vol. 31. Ellis G.-P. John Wiley and Sons; New York: 1977
• 1b Flavonoids: Chemistry, Biochemistry and Applications . Andersen ØM. CRC, Taylor and Francis; Boca Raton: 1986
• 1c Flavonoids: Biosynthesis, Biological Effects and Dietary Sources. Keller RB. Nova Science; Hauppauge: 2009
• 2a Kulkarni PR. Org. Chem.: Indian J. 2014; 10: 417
• 2b Meng L. Wang J. Synlett 2016; 27: 656

For selected reports, see:
• 3a Biddle MM. Lin M. Scheidt KA. J. Am. Chem. Soc. 2007; 129: 3830
• 3b Wang L.-J. Liu X.-H. Dong Z.-H. Fu X. Feng X.-M. Angew. Chem. Int. Ed. 2008; 47: 8670
• 3c Wang H.-F. Cui H.-F. Chai Z. Li P. Zheng C.-W. Yang Y.-Q. Zhao G. Chem. Eur. J. 2009; 15: 13299
• 3d Hintermann L. Dittmer C. Eur. J. Org. Chem. 2012; 5573

For selected reports, see:
• 4a Chen J. Chen J. Lang F. Zhang X. Cun L. Zhu J. Deng J. Liao J. J. Am. Chem. Soc. 2010; 132: 4552
• 4b Korenaga T. Hayashi K. Akaki Y. Maenishi R. Sakai T. Org. Lett. 2011; 13: 2022
• 4c Holder JC. Marziale AN. Gatti M. Mao B. Stoltz BM. Chem. Eur. J. 2013; 19: 74
• 4d He Q. So CM. Bian Z. Hayashi T. Wang J. Chem. Asian J. 2015; 10: 540
• 5a Valla C. Baeza A. Menges F. Pfaltz A. Synlett 2008; 3167
• 5b Zhao D.-B. Beiring B. Glorius F. Angew. Chem. Int. Ed. 2013; 52: 8454
• 6 Parks DJ. Piers WE. J. Am. Chem. Soc. 1996; 118: 9440
• 7 Oesteich M. Hermeke J. Mohr J. Chem. Soc. Rev. 2015; 44: 2202

For selected reports, see:
• 8a Blackwell JM. Foster KL. Beck VH. Piers WE. J. Org. Chem. 1999; 64: 4887
• 8b Blackwell JM. Sonmor ER. Scoccitti T. Piers WE. Org. Lett. 2000; 2: 3921
• 8c Berkefeld A. Piers WE. Parvez M. J. Am. Chem. Soc. 2010; 132: 10660
• 8d Simonneau A. Oestreich M. Angew. Chem. Int. Ed. 2013; 52: 11905
• 8e Pérez M. Hounjet LJ. Caputo CB. Dobrovetsky R. Stephan DW. J. Am. Chem. Soc. 2013; 135: 18308
• 8f Adduci LL. McLaughlin MP. Bender TA. Becker JJ. Gagné MR. Angew. Chem. Int. Ed. 2014; 53: 1646
• 8g Houghton AY. Hurmalainen J. Mansikamäki A. Piers WE. Tuononen HM. Nat. Chem. 2014; 6: 983
• 8h Gandhamsetty N. Joung S. Park S.-W. Park S. Chang S. J. Am. Chem. Soc. 2014; 136: 16780
• 8i Granhamsetty N. Park J. Jeong J. Park S.-W. Park S. Chang S. Angew. Chem. Int. Ed. 2015; 54: 6832
• 8j Chen J. Chen EY.-X. Angew. Chem. Int. Ed. 2015; 54: 6842
• 8k Mehta M. Holthausen MH. Mallov I. Pérez M. Qu Z.-W. Grimme S. Stephan DW. Angew. Chem. Int. Ed. 2015; 54: 8250
• 8l Simonneau A. Oestreich M. Nat. Chem. 2015; 7: 816
• 9 Feng X. Du H. Tetrahedron Lett. 2014; 55: 6959
• 10a Rendler S. Oestreich M. Angew. Chem. Int. Ed. 2008; 47: 5997
• 10b Hog DT. Oestreich M. Eur. J. Org. Chem. 2009; 5047
• 10c Mewald M. Oestreich M. Chem. Eur. J. 2012; 18: 14079
• 10d Hermeke J. Mewald M. Oestreich M. J. Am. Chem. Soc. 2013; 135: 17537
• 10e Chen D. Leich V. Pan F. Klankermayer J. Chem. Eur. J. 2012; 18: 5184
• 10f Süsse L. Hermeke J. Oestreich M. J. Am. Chem. Soc. 2016; 138: 6940
• 11 Greb L. Oña-Burgos P. Kubas A. Falk FC. Breher F. Fink K. Paradies J. Dalton Trans. 2012; 41: 9056
• 12 Kim Y. Chang S. Angew. Chem. Int. Ed. 2016; 55: 218
• 13a Liu Y. Du H. J. Am. Chem. Soc. 2013; 135: 6810
• 13b Wei S. Du H. J. Am. Chem. Soc. 2014; 136: 12261
• 13c Ren X. Li G. Wei S. Du H. Org. Lett. 2015; 17: 990
• 13d Zhang Z. Du H. Org. Lett. 2015; 17: 2816
• 13e Zhang Z. Du H. Org. Lett. 2015; 17: 6266
• 14a Zhu X. Du H. Org. Biomol. Chem. 2015; 13: 1013
• 14b Ren X. Du H. J. Am. Chem. Soc. 2016; 138: 810
• 15 Massey AG. Park AJ. J. Organometallic Chem. 1964; 2: 245
• 16a Parks DJ. von H Spence RE. Piers WE. Angew. Chem., Int. Ed. Engl. 1995; 34: 809
• 16b Parks DJ. Piers WE. Yap GP. A. Organometallics 1998; 17: 5492
• 17 General Procedure for Hydrosilylations To a tube, HB(C₆F₅)₂ (0.0035 g, 0.01 mmol), 2,3,4,5,6-pentafluorostyrene (0.0019 g, 0.01 mmol), and dry toluene (0.10 mL) were added in a nitrogen atmosphere glovebox. The resulting mixture was stirred for 5 min at r.t. to afford a catalyst solution (0.10 M). To a sealing tube (15 mL), catalyst solution (0.0004 mmol, 4 μL, 0.1 M), PhMe₂SiH (0.0649 g, 0.48 mmol), chromone or flavone 1(0.0644 g, 0.4 mmol), and dry toluene (0.8 mL) were added. The reaction mixture was stirred at 80 °C for 15 h, and then was cooled to r.t. followed by addition of TFA (0.0547 g, 0.48 mmol). The resulting mixture stirred at r.t. for 10 min and was concentrated and purified by column chromatography on silica gel to afford the corresponding products 3. 2-Isopropylchroman-4-one (3d) Colorless oil, 0.0593 g, 78% yield. ¹H NMR (400 MHz, CDCl₃): δ = 7.87 (d, J = 7.6 Hz, 1 H), 7.46 (dd, J = 8.0, 7.6 Hz, 1 H), 6.99 (m, 2 H), 4.21–4.16 (m, 1 H), 2.75–2.62 (m, 2 H), 2.12–2.18 (m, 1 H), 1.08 (d, J = 6.8 Hz, 3 H), 1.05 (t, J = 6.8 Hz, 3 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 193.1, 162.0, 136.0, 127.0, 121.1, 121.0, 118.0, 82.6, 40.1, 32.2, 17.92, 17.90 ppm. 2-(2-Fluorophenyl)chroman-4-one (3i) Light yellow oil, 0.0582 g, 60% yield. ¹H NMR (400 MHz, CDCl₃): δ = 7.95 (d, J = 7.6 Hz, 1 H), 7.64 (dd, J = 7.6, 7.6 Hz, 1 H), 7.52 (dd, J = 8.6, 8.0 Hz, 1 H), 7.40–7.32 (m, 1 H), 7.27–7.20 (m, 1 H), 7.14–7.04 (m, 3 H), 5.79 (dd, J = 13.2, 2.8 Hz, 1 H), 3.06 (dd, J = 16.8, 13.2 Hz, 1 H), 2.93 (dd, J = 16.8, 3.2 Hz, 1 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 191.6, 161.6, 159.7 (d, J_C–F = 246.0 Hz), 136.3, 130.3 (d, J_C–F = 9.0 Hz), 127.6 (d, J_C–F = 4.0 Hz), 127.2, 126.3 (d, J_C–F = 13.0 Hz), 124.7 (d, J_C–F = 3.0 Hz), 121.9, 121.0, 118.2, 115.8 (d, J_C–F = 21.0 Hz), 73.9 (d, J_C–F = 3.0 Hz), 43.8 ppm.¹⁹F NMR (470 MHz, CDCl₃): δ = –121.8 ppm.