Synlett 2002(8): 1253-1256
DOI: 10.1055/s-2002-32969
LETTER
© Georg Thieme Verlag Stuttgart · New York

Electron Transfer Driven Transformations of Transition Metal π-Complexes: Samarium(II) Iodide Mediated Coupling of Fluoroarene-Cr(CO)3 Complexes with Ketones

Hans-Günther Schmalz*, Oliver Kiehl, Battsengel Gotov
Institut für Organische Chemie, Universität zu Köln, Greinstrasse 4, 50939 Köln, Germany
Fax: +49(221)4703064; e-Mail: schmalz@uni-koeln.de;
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Publikationsverlauf

Received 21 May 2002
Publikationsdatum:
25. Juli 2002 (online)

Abstract

Fluoro-substituted η6-arene tricarbonylchromium complexes react with aliphatic ketones in the presence of SmI2 and tBuOH under C-C bond formation to give the corresponding tertiary benzylic alcohols in up to 77% yield. Chlorobenzene-Cr(CO)3 exhibit a similar reactivity. The reactions proceed through attack of a ketyl radical to the complexed arene followed by single electron reduction of the 17 VE intermediate. The overall reaction parallels a nucleophilic aromatic substitution of fluoride (SNAr) and preferentially occurs in a meta-tele fashion.

    References

  • Selected overviews:
  • 1a Schmalz H.-G. Siegel S. In Transition Metals for Organic Synthesis   Vol. 1:  Beller M. Bolm C. Wiley-VCH; Weinheim: 1998.  p.550 
  • 1b Hegedus LS. Transition Metals in the Synthesis of Complex Organic Molecules   2nd ed.:  University Science Books; Sausalito, CA: 1999.  Chap. 10.
  • 1c Pape AR. Kaliappan KP. Kündig EP. Chem. Rev.  2000,  100:  2917 
  • 1d Kamikawa K. Uemura M. Synlett  2000,  938 
  • 1e Kamikawa K. Watanabe T. Uemura M. J. Synth. Org. Chem., Jpn.  2001,  59:  1078 
  • 1f Carpentier J.-F. Petit F. Mortreux A. Dufand V. Basset J.-M. Thivolle-Cazat J. J. Mol. Catal.  1993,  81:  1 
  • 2a Schmalz H.-G. Siegel S. Bats JW. Angew. Chem., Int. Ed. Engl.  1995,  34:  2383 ; Angew. Chem. 1995, 107, 2597
  • 2b Schmalz H.-G. Siegel S. Schwarz A. Tetra-hedron Lett.  1996,  37:  2947 
  • 2c Hoffmann O. Schmalz H.-G. Synlett  1998,  1426 
  • 2d Schwarz O. Brun R. Bats JW. Schmalz H.-G. Tetrahedron Lett.  2002,  43:  1009 
  • 3a Merlic CA. Walsh JC. J. Org. Chem.  2001,  66:  2265 
  • 3b Taniguchi N. Uemura M. Synlett  1997,  51 
  • 3c Taniguchi N. Hata T. Uemura M. Angew. Chem. Int. Ed.  1999,  38:  1232 
  • 3d Taniguchi N. Uemura M. Tetrahedron  1998,  54:  12775 
  • 3e Monovich LG. Le Huerou Y. Ronn M. Molander GA. J. Am. Chem. Soc.  2000,  122:  52 
  • 4a Schmalz H.-G. de Koning CB. Bernicke D. Siegel S. Pfletschinger A. Angew. Chem. Int. Ed.  1999,  38:  1620 
  • 4b Schmalz H.-G. Siegel S. Bernicke D. Tetrahedron Lett.  1998,  39:  6683 
  • 5a Kagan HB. New J. Chem.  1990,  14:  453 
  • 5b Molander GA. Chem. Rev.  1992,  92:  29 
  • 5c Inanaga J. Heteroat. Chem.  1990,  3:  75 
  • 6 Yeh M.-CP. Wang F.-C. Tu J.-J. Chang S.-C. Chou C.-C. Liao J.-W. Organometallics  1998,  17:  5656 
  • 7 Siegel S. PhD Thesis   TU Berlin; Berlin: 1998. 
  • 9a Semmelhack MF. In Comprehensive Organometallic Chemistry II   Vol. 12:  Abel EW. Stone FGA. Wilkinson G. Pergamon Press; New York: 1995.  p.979 
  • 9b Semmelhack MF. In Comprehensive Organometallic Chemistry II   Vol. 12:  Abel EW. Stone FGA. Wilkinson G. Pergamon Press; New York: 1995.  p.1039 
  • 9c Rose-Munch F. Gagliardini V. Renard C. Rose E. Coord. Chem. Rev.  1998,  178-180:  249 
  • 9d Rose-Munch F. Rose E. Curr. Org. Chem.  1999,  3:  445 
  • 10 Mahaffy CA. Pauson PL. Inorg. Synth.  1990,  28:  136 
  • 11 Inanaga J. Ishikawa M. Yamaguchi M. Chem. Lett.  1987,  1485 
  • 12 Batey RA. Motherwell WB. Tetrahedron Lett.  1991,  32:  6649 
  • 15 Rose-Munch F. Rose E. Semra A. Mignon L. Garcia-Oricain J. Knobler C. J. Organomet. Chem.  1989,  363:  297 
  • 16 Merlic CA. Miller MM. Hietbrink BN. Houk KN. J. Am. Chem. Soc.  2001,  123:  4904 
  • 17 Lin HC. Zhang HJ. Yang L. Li CZ. Org. Lett.  2002,  4:  823 
8

Only one enantiomer of racemic compounds is depicted.

13

Typical Experimental Procedure: A flame dried Schlenk flask was charged with 15 mL of a 0.1 M solution of SmI2 in THF and HMPA (1.5 mL) under argon. After cooling to 0 °C, a solution of the fluorobenzene-Cr(CO)3 complex(11) (116 mg, 0.5 mmol), tBuOH (145 µL, 1.5 mmol) and acetone (45 µL, 0.6 mmol) in THF (3 mL) was added dropwise via cannula over a period of 5 min. The resulting mixture was stirred at 0 °C for 90 min and for 60 min at r.t. before it was quenched with saturated aqueous NaHCO3 (5 mL). After stirring for another 5 min, the reaction mixture was filtered through a short pad of Celite® and washed with MTBE. The organic layer was washed with saturated NaHCO3 solution, brine, dried over Na2SO4 and evaporated. The residue was purified by chromatography (20g of SiO2, CyH-EtOAc = 3:1) to give 105 mg (77%) of complex 12 as yellow crystalline compound. Mp 73 °C. 1H NMR (270 MHz, CDCl3): 1.56 (s, 6 H); 5.31 (t, 2 H, J = 6.5 Hz); 5.42 (t, 1 H, J = 6.5 Hz); 5.64 (d, 2 H, J = 6.5 Hz). 13C NMR (67.7 MHz, CDCl3): 31.3; 70.8; 91.3; 91.5; 93.4; 121.3; 232.53. FT-IR (ATR): 3576; 3483; 3092; 2985; 2932; 1948; 1892; 1854; 1457; 1415; 1366; 1168; 1154; 1096; 1054; 966; 861; 821; 662 cm-1. HRMS: for C12H12CrO4 calcd.: 272.0141; found: 272.0144.
Compound 13: Mp 98 °C. 1H NMR (400 MHz, CDCl3): 1.58-1.70 (m, 5 H); 1.70-1.86 (m, 5 H); 5.26 (t, 2 H, J = 6.5 Hz); 5.44 (t, 1 H, J = 6.5 Hz); 5.68 (d, 2 H, J = 6.5 Hz). 13C NMR (100 MHz, CDCl3): 21.8; 25.2; 38.9; 71.4; 90.8; 92.1; 94.0; 121.8; 233.4. FT-IR (ATR): 3582; 3093; 2936; 2859; 1959; 1869; 1449; 1411; 1350; 1309; 1261; 1203; 1153; 1123; 1034; 1022; 978; 849; 814; 688 cm-1. HRMS: for C15H16CrO4 calcd.: 312.0454; found: 312.0454.
Compound 14: Mp 71 °C. 1H NMR (270 MHz, CDCl3): 1.77-2.09 (m, 8 H); 5.31-5.43 (m, 3 H); 5.64 (dd, 2 H, J 1 = 6.5 Hz, J 2 = 2 Hz). 13C NMR (67.7 MHz, CDCl3): 24.3; 42.4; 81.6; 91.4; 92.1; 92.8; 118.7; 233.4. FT-IR (ATR): 3582; 3443; 3088; 2958; 2875; 1957; 1865; 1458; 1412; 1327; 1295; 1233; 1189; 1152; 1009; 949; 903; 882; 817; 661
cm-1. HRMS: for C14H14CrO4 calcd.: 298.0297; found: 298.0293.
Compound rac-15: Mp 119 °C. 1H NMR (400 MHz, CDCl3): 1.64 (s, 3 H); 1.97 (t, 2 H, J = 5.5 Hz); 3.79 (dtt, 1 H, J 1 = 10 Hz, J 2 = 5.5 Hz, J 3 = 5 Hz); 3.90 (dtt, 1 H, J 1 = 10 Hz, J 2 = 5.5 Hz, J 3 = 5 Hz); 5.25 (t, 1 H, J = 6 Hz); 5.29 (t, 1 H, J = 6.5 Hz); 5.43 (t, 1 H, J = 6 Hz); 5.45 (d, 1 H, J = 6 Hz); 5.80 (d, 1 H, J = 6.5 Hz). 13C NMR (100 MHz, CDCl3): 29.1; 44.9; 59.7; 70.6; 90.5; 90.6; 91.7; 92.0; 93.7; 120.0; 233.1. FT-IR (ATR): 3363; 2978; 2893; 1958; 1870; 1457; 1413; 1378; 1298; 1153; 1083; 1054; 1014; 965; 881; 816; 662
cm-1. HRMS: for C13H14CrO5 calcd.: 302.0246; found: 302.0247.
Compound rac-16: Mp 114 °C. 1H NMR (400 MHz, CDCl3): 1.60 (s, 3 H); 2.72 (d, 1 H, J = 16 Hz); 2.79 (d, 1 H, J = 16 Hz); 3.74 (s, 3 H); 5.22 (t, 2 H, J = 6.5 Hz); 5.46 (t, 1 H, J = 6.5 Hz); 5.62 (d, 1 H, J = 6.5 Hz); 5.68 (d, 1 H, J = 6.5 Hz). 13C NMR (100 MHz, CDCl3): 30.0; 46.6; 52.1; 70.9; 89.6; 89.7; 91.8; 92.1; 94.0; 117.9; 172.0; 232.7. FT-IR (ATR): 3482; 3092; 2954; 2927; 1958; 1866; 1854; 1713; 1457; 1438; 1412; 1374; 1342; 1207; 1180; 1095; 1069; 1049; 1009; 958; 857; 816; 660 cm-1. HRMS: for C14H14CrO6 calcd.: 330.0195; found: 330.0195.

14

Preliminary attempts to employ aldehydes instead of ketones under similar conditions were not successful. In these cases, only the reduced aldehydes (alcohols) and some pinacol-type coupling products were formed, and the unchanged fluorobenzene-Cr(CO)3 derivatives could be reisolated.