Synlett 2010(19): 2883-2886  
DOI: 10.1055/s-0030-1259040
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Cross-Coupling Reactions between C(sp²)-H and C(sp³)-H Bonds via Sequential Dehydrogenation and C-H Insertion

Yoichiro Kuninobu*, Daisuke Asanoma, Kazuhiko Takai*
Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama 700-8530, Japan
Fax: +81(86)2518094; e-Mail: [email protected]; e-Mail: [email protected];
Weitere Informationen

Publikationsverlauf

Received 8 September 2010
Publikationsdatum:
10. November 2010 (online)

Abstract

Formal C(sp²)-H and C(sp³)-H cross-coupling reactions were carried out by iridium-catalyzed transfer dehydrogenation of primary alcohols and sequential manganese-catalyzed insertion of the formed aldehydes into a carbon-hydrogen bond of aromatic or olefinic compounds.

    References and Notes

  • 1 Metal-Catalyzed Cross Coupling Reactions   2nd ed., Vol. 1 and 2:  de Meijere A. Diederich F. Wiley-VCH; Weinheim: 2004. 
  • For recent examples of carbon-metal and carbon-hydrogen bond coupling, see:
  • 2a Giri R. Maugel N. Li J.-J. Wang D.-H. Breazzano SP. Saunders LB. Yu J.-Q. J. Am. Chem. Soc.  2007,  129:  3510 
  • For reviews, see:
  • 2b Li B.-J. Yang S.-D. Shi Z.-J. Synlett  2008,  949 
  • 2c Chen X. Engle KM. Wang D.-H. Yu J.-Q. Angew. Chem. Int. Ed.  2009,  48:  5094 
  • For recent examples of carbon-hydrogen and carbon-halogen bond coupling, see:
  • 3a Wang X. Lane BS. Sames D. J. Am. Chem. Soc.  2005,  127:  4996 
  • 3b Oi S. Sakai K. Inoue Y. Org. Lett.  2005,  7:  4009 
  • 3c Kobayashi K. Sugie A. Takahashi M. Masui K. Mori A. Org. Lett.  2005,  7:  5083 
  • 3d Ackermann L. Althammer A. Born R. Angew. Chem. Int. Ed.  2006,  45:  2619 
  • 3e Yanagisawa S. Sudo T. Noyori R. Itami K. J. Am. Chem. Soc.  2006,  128:  11748 
  • 3f Berman AM. Lewis JC. Bergman RG. Ellman JA. J. Am. Chem. Soc.  2008,  130:  14926 
  • 3g Do H.-Q. Daugulis O. J. Am. Chem. Soc.  2007,  129:  12404 
  • For reviews, see:
  • 3h Bellina F. Rossi R. Tetrahedron  2009,  65:  10269 
  • 3i Daugulis O. Top. Curr. Chem.  2010,  292:  57 
  • 3j Beck EM. Gaunt MJ. Top. Curr. Chem.  2010,  292:  85 
  • 3k Bouffard J. Itami K. Top. Curr. Chem.  2010,  292:  231 
  • For recent examples of carbon-hydrogen and carbon-hydrogen bond coupling, see:
  • 4a Stuart DR. Fagnou K. Science  2007,  316:  1172 
  • 4b Hull KL. Sanford MS.
    J. Am. Chem. Soc.  2007,  129:  11904 
  • 4c Zhao X. Yeung CS. Dong VM. J. Am. Chem. Soc.  2010,  132:  5837 
  • For representative examples, see:
  • 5a Sezen B. Sames D. J. Am. Chem. Soc.  2005,  127:  5284 
  • 5b Li Z. Li C.-J.
    J. Am. Chem. Soc.  2005,  127:  6968 
  • 5c Wang D.-H. Wasa M. Giri R. Yu J.-Q. J. Am. Chem. Soc.  2008,  130:  7190 
  • 5d Li C.-J. Acc. Chem. Res.  2009,  42:  335 
  • 5e Wasa M. Engle KM. Yu J.-Q. J. Am. Chem. Soc.  2010,  132:  3680 
  • 5f Qian B. Guo S. Shao J. Zhu Q. Yang L. Xia C. Huang H. J. Am. Chem. Soc.  2010,  132:  3650 
  • 5g Shabashov D. Daugulis O. J. Am. Chem. Soc.  2010,  132:  3965 
  • 6 Fujita K.-i. Furukawa S. Yamaguchi R. J. Organomet. Chem.  2002,  649:  289 
  • 7a Kuninobu Y. Nishina Y. Takeuchi T. Takai K. Angew. Chem. Int. Ed.  2007,  46:  6518 
  • In addition, we have also reported on rhenium-catalyzed insertion of aldehydes into a C-H bond of aromatic and olefinic compounds. See also:
  • 7b Kuninobu Y. Nishina Y. Nakagawa C. Takai K. J. Am. Chem. Soc.  2006,  128:  12376 
  • 7c Kuninobu Y. Nishina Y. Takai K. Tetrahedron  2007,  63:  8463 
  • 7d Kuninobu Y. Fujii Y. Matsuki T. Nishina Y. Takai K. Org. Lett.  2009,  11:  2711 
  • 8 Fujita K.-i. Tanino N. Yamaguchi R. Org. Lett.  2007,  9:  109 
9

When (E)-3-methyl-3-penten-2-one (2) was used as a hydrogen acceptor, 3-methylpentan-2-one was formed. This result shows that the olefinic moiety of 2 was reduced.

10

Investigation of hydrogen acceptors in dehydrogenation of alcohol 1a {hydrogen acceptor: 1.5 equiv; [Cp*IrCl2]2: 0.50 mol%; K2CO3: 5.0 mol%; toluene, 150 ˚C; 18 h}: (E)-3-methyl-3-penten-2-one >99%; (1E,4E)-1,5-diphenyl-1,4-pentadien-3-one >99%; 3-methyl-2-cyclohexenone 92%; (E)-4-phenyl-3-buten-2-one 92%; 1-penten-3-one 82%; p-benzoquinone 78%; 2-cyclohexenone 57%; 2-cyclo-pentenone 52%; 3-ethoxy-2-cyclohexenone 8%.

11

First, we conducted the reactions between benzyl alcohol (1a), (E)-3-methyl-3-penten-2-one (2), 1-methyl-2-phenyl-1H-imidazole (3a), and HSiEt3 in the presence of catalytic amounts of an iridium complex, [Cp*IrCl2]2, K2CO3, and a manganese complex, MnBr(CO)5, in toluene. However, the desired reaction did not proceed at all. Therefore, we carried out the coupling reactions in two steps.

12

3-Methyl-2-pentanone, which is formed by hydrogenation of (E)-3-methyl-3-penten-2-one (2), was observed by ¹H NMR and GCMS.

13

General Procedure of Formal Cross-Coupling Reaction
A mixture of alcohol (1, 0.500 mmol), (E)-3-methyl-3-penten-2-one (2, 73.6 mg 0.750 mmol), [Cp*IrCl2]2 (2.0 mg, 0.0025 mmol), K2CO3 (3.5 mg, 0.025 mmol), and toluene (1.0 mL) was heated at 150 ˚C for 18 h. Then, imidazole
(3, 0.250 mmol), HSiEt3 (58.1 mg, 0.500 mmol), and MnBr(CO)5 (3.4 mg, 0.013 mmol) were added, and the mixture was stirred at 115 ˚C for 24 h. The product was isolated by column chromatography on silica gel [hexane-EtOAc = 5:1. Before column chromatography, the silica
gel was treated with Et3N {5% solution in hexane-EtOAc
(5/1)}.] to give 4.

14

1-Methyl-2-[2-( p -tolyltriethylsilanyloxymethyl)phenyl]-1 H -imidazole (4c)
¹H NMR (400 MHz, CDCl3): δ = 0.54 (q, J = 8.0 Hz, 6 H), 0.86 (t, J = 8.0 Hz, 9 H), 2.23 (s, 3 H), 2.69 (s, 3 H), 6.15 (s, 1 H), 6.74 (d, J = 8.8 Hz, 2 H), 6.81 (s, 1 H), 6.93 (d, J = 6.8 Hz, 2 H), 7.11 (d, J = 7.2 Hz, 1 H), 7.18 (s, 1 H), 7.28 (t, J = 7.2 Hz, 1 H), 7.50 (t, J = 7.2 Hz, 1 H), 8.03 (d, J = 7.6 Hz, 1 H). ¹³C NMR (100 MHz, CDCl3): δ = 4.7, 6.7, 32.4, 72.5, 120.2, 125.7, 126.1, 126.8, 127.8, 128.1, 128.3, 129.3, 129.8, 136.2, 141.7, 146.4, 146.6; IR (nujol): ν = 1178 (m), 1117 (m), 1072 (m), 1011 (m), 851 (m) cm. HRMS (EI+): m/z calcd for C23H34N2OSi [M+]: 392.2284; found: 392.2291.