Synlett 2006(3): 0407-0410  
DOI: 10.1055/s-2006-932451
LETTER
© Georg Thieme Verlag Stuttgart · New York

Iron-Catalyzed Cross-Coupling between Alkenyl and Dienyl Sulfonates and Functionalized Arylcopper Reagents

Guillaume Dunet, Paul Knochel*
Department Chemie und Biochemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München, Germany
Fax: +49(89)218077680; e-Mail: Paul.Knochel@cup.uni-muenchen.de;
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Publikationsverlauf

Received 19 December 2005
Publikationsdatum:
06. Februar 2006 (online)

Abstract

Functionalized arylcopper reagents react readily with alkenyl sulfonates in the presence of catalytic amounts of Fe(acac)3 (10 mol%) providing the expected cross-coupling products in good yields. Ester or cyano group are tolerated. This cross-coupling can be performed with dienyl sulfonates leading to the corresponding substituted dienes.

7

Typical Procedure - Preparation of Ethyl 4-(2,2-Di-phenylvinyl)benzoate ( 4b).
A 25 mL flame-dried Schlenk tube flushed with argon was charged with ethyl 4-iodobenzoate (2.9 mmol, 773 mg), DME (5 mL) and cooled to -20 °C. Isopropylmagnesium chloride (2.9 mmol, 1.33 mL of a 2.1 M solution in THF) was then slowly added and the reaction mixture was stirred at -20 °C until GC analysis of reaction aliquots indicated complete exchange. Subsequently, a solution of CuCN·2LiCl (2.8 mmol, 2.8 mL of a 1 M solution in THF) was added and the reaction mixture was stirred for 20 min. A solution of (2,2-diphenylvinyl)trifluoromethanesulfonate (330 mg, 1 mmol) and Fe(acac)3 (38 mg, 0.1 mmol) in DME (3 mL) was added at once at -20 °C and the reaction mixture was stirred at r.t. for 1 h. The reaction was quenched with sat. NH4Cl (aq), and extracted several times with Et2O. The combined organic phases were washed with a 2:1 mixture of NH3 (aq) and NH4Cl (aq), sat. brine, dried over MgSO4 and concentrated under reduced pressure. Purification via column chromatography (elution with a 99:1 pentane-Et2O mixture) afforded the stilbene (4b) as a yellow oil (254 mg, 77%). 1H NMR (300 MHz, CDCl3): δ = 7.72 (unresolved d, J = 8.4 Hz, 2 H), 7.21-7.28 (m, 8 H), 7.08-7.13 (m, 2 H), 6.99 (unresolved d, J = 8.6 Hz, 2 H), 6.91 (s, 1 H), 4.25 (q, J = 7.1 Hz, 2 H), 1.27 (t, J = 7.1 Hz, 3 H). 13C NMR (75 MHz, CDCl3): δ = 166.8, 145.3, 143.3, 142.4, 140.2, 130.7, 129.7, 129.6, 129.1, 128.7, 128.7, 128.3, 128.1, 128.1, 127.5, 61.2, 14.7. HRMS: m/z calcd: 328.1463; found: 328.1455. MS (EI, 70 eV): m/z (%) = 328 (100), 283 (18), 255 (48), 239 (14).
1-[2-(4-Methoxyphenyl)-1-phenylvinyl]benzene ( 4c): 1H NMR (300 MHz, CDCl3): δ = 7.21-7.29 (m, 7 H), 7.18-7.20 (m, 1 H), 7.12-7.16 (m, 2 H), 6.88 (unresolved d, J = 8.6 Hz, 2 H), 6.84 (s, 1 H), 6.59 (unresolved d, J = 8.8 Hz, 2 H), 3.67 (s, 3 H). 13C NMR (75 MHz, CDCl3): δ = 158.8, 144.0, 141.0, 141.0, 131.2, 130.8, 130.5, 129.1, 128.5, 128.0, 127.8, 127.7, 127.6, 113.8, 55.5. HRMS: m/z calcd: 286.1358; found: 286.1341. MS (EI, 70 eV): m/z (%) = 286 (100), 165 (15).
1-{(2-[3-(Trifluoromethyl)phenyl]-1-phenyl-vinyl}benzene ( 4d): 1H NMR (300 MHz, CDCl3): δ = 7.21-730 (m, 9 H), 7.16-7.19 (m, 2 H), 7.08-7.13 (m, 3 H), 6.90 (s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 145.0, 143.1, 140.0, 138.5, 132.9, 130.5, 129.2, 128.7, 128.3, 128.2, 128.0, 126.8, 126.7, 126.6, 123.6, 123.3. HRMS: m/z calcd: 324.1126; found: 324.1118. MS (EI, 70 eV): m/z (%) = 324 (100), 283 (10), 255 (13), 178 (11).
3-(2,2-Diphenylvinyl)benzonitrile ( 4f): 1H NMR (300 MHz, CDCl3): δ = 7.22-7.32 (m, 9 H), 7.19-7.21 (m, 1 H), 7.11-7.16 (m, 2 H), 7.05-7.11 (m, 2 H), 6.83 (s, 1 H). 13C (75 MHz, CDCl3): δ = 145.8, 142.9, 139.7, 139.1, 134.0, 133.3, 132.6, 130.5, 130.4, 129.5, 129.3, 129.1, 128.7, 128.6, 128.5, 128.1, 125.9, 112.6. HRMS: m/z calcd: 281.1204; found: 281.1186. IR (KBr): 3435 (w), 3056, 2228, 1616, 1491, 1444, 796, 765, 701 cm-1.
Ethyl 4-(Cyclohexa-1,5-dienyl)benzoate ( 4j): 1H NMR (300 MHz, CDCl3): δ = 7.92 (unresolved d, J = 8.4 Hz, 2 H), 7.36 (unresolved d, J = 8.4 Hz, 2 H), 6.26 (dq, J = 9.7 Hz, J = 1.8 Hz, 1 H), 6.11 (unresolved t, J = 4.4 Hz, 1 H), 5.93-6.01 (m, 1 H), 4.30 (q, J = 7.1 Hz, 2 H), 2.23-2.33 (m, 2 H), 2.09-2.19 (m, 2 H), 1.32 (t, J = 7.1 Hz, 3 H). 13C (75 MHz, CDCl3): δ = 166.9, 145.3, 135.6, 130.1, 129.2, 128.6, 125.5, 125.4, 125.3, 61.2, 23.3, 22.2; 14.7. HRMS: m/z calcd: 228.1150; found: 228.1135. MS (EI, 70 eV): m/z (%) = 228 (100), 200 (10), 183 (32), 155 (87), 153 (19), 128 (10).
1-(Cyclohexa-1,5-dienyl)-3-(trifluoromethyl)benzene ( 4k): 1H NMR (300 MHz, CDCl3): δ = 7.54 (s, 1 H), 7.30-7.52 (m, 3 H), 6.22 (dq, J = 9.7 Hz, J = 1.8 Hz, 1 H), 6.06 (tt, J = 4.6 Hz, J = 1.3 Hz, 1 H), 5.98 (dtd, J = 9.7 Hz, J = 4.3 Hz, J = 0.9 Hz, 1 H), 2.23-2.33 (m, 2 H), 2.09-2.19 (m, 2 H). 13C NMR (75 MHz, CDCl3): δ = 141.8, 135.3, 129.2, 129.0, 128.8, 125.4, 124.8, 123.8, 122.6, 23.2, 22.2. HRMS: m/z calcd: 224.0813; found: 224.0839. MS (EI, 70 eV): m/z (%) = 224 (82), 223 (32), 209 (58), 183 (87), 155 (100).
1-(Cyclohexa-1,5-dienyl)naphthalene ( 4l): 1H NMR (300 MHz, CDCl3): δ = 7.90-7.98 (m, 1 H), 7.73-7.79 (m, 1 H), 7.68 (d, J = 8.0 Hz, 1 H), 7.32-7.43 (m, 3 H), 7.24 (dd, J = 7.1 Hz, J = 1.3 Hz, 1 H), 6.1 (dq, J = 9.7 Hz, J = 1.8 Hz, 1 H), 5.82-5.93 (m, 2 H), 2.29-2.39 (m, 2 H), 2.18-2.29 (m, 2 H). 13C NMR (75 MHz, CDCl3): δ = 140.8, 136.7, 134.1, 131.8, 128.8, 128.7, 127.7, 126.4, 126.4, 126.0, 126.05, 125.98, 125.9, 125.8, 23.2, 22.4. HRMS: m/z calcd: 206.1096; found: 206.1078. MS (EI, 70 eV): m/z (%) = 207 (15), 206 (100), 205(90), 178 (53), 165 (49).