Efficient Suzuki-Miyaura Coupling of Deactivated Aryl Chlorides Catalyzed by an Oxime Palladacycle

Abstract

Aryl chlorides are efficiently cross-coupled with aryl boronic acids using 0.25 mol% of 4,4′-dichlorobenzophenone oxime derived palladacycle as precatalyst in the presence of 1 mol% of [HP(t-Bu)₃]BF₄ as ligand, K₂CO₃ as base, TBAOH as additive, and DMF as solvent under conventional thermal or MW irradiation conditions. Under these simple reaction conditions a wide array of deactivated and hindered aryl chlorides react cleanly to afford in high yields functionalized biaryl derivatives.

Key words

palladacycles - boronic acids - cross-coupling - biaryls - Suzuki reaction

References and Notes

• 1a Littke A. In Modern Arylation Methods   Ackermann L. Wiley-VCH; Weinheim: 2009.  p.25 
• 1b Catellani M. Motti E. Della Ca’ N. Ferraccioli R. Eur. J. Org. Chem.  2007,  4153 
• 1c Alberico D. Scott ME. Lautens M. Chem. Rev.  2007,  107:  174 
• 1d Suzuki A. In Boronic Acids. Preparation, Applications in Organic Synthesis and Medicine   Hall DG. Wiley-VCH; Weinheim: 2005.  p.123 
• For recent selected reviews, see:
• 2a Alonso F. Beletskaya IP. Yus M. Tetrahedron  2008,  64:  3047 
• 2b Miyaura N. In Metal-Catalyzed Cross-Coupling Reactions   2nd ed., Vol. 1:  de Meijere A. Diederich F. Wiley-VCH; Weinheim: 2004.  p.41 
• For recent reviews, see:
• 3a Martin R. Buchwald SL. Acc. Chem. Res.  2008,  41:  1461 
• 3b Fu GC. Acc. Chem. Res.  2008,  41:  1555 
• For representative examples, see:
• 4a Littke AF. Dai C. Fu GC. J. Am. Chem. Soc.  2000,  122:  4020 
• 4b Zapf A. Ehrentraut A. Beller M. Angew. Chem. Int. Ed.  2000,  39:  4153 
• 4c Walker SD. Barder TE. Martinelli JR. Buchwald SL. Angew. Chem. Int. Ed.  2004,  43:  1871 
• For recent reviews, see:
• 5a Marion N. Nolan SP. Acc. Chem. Res.  2008,  41:  1440 
• 5b Würtz S. Glorius F. Acc. Chem. Res.  2008,  41:  1523 
• 5c Organ MG. Chass GA. Fang D.-C. Hopkinson AC. Valente C. Synthesis  2008,  2776 
• 5d Kantchev EAB. O’Brien CJ. Organ MG. Angew. Chem. Int. Ed.  2007,  46:  2768 
• For representative examples, see:
• 6a Gstöttmayr CWK. Böhm VPW. Herdtweck E. Grosche M. Herrmann WA. Angew. Chem. Int. Ed.  2002,  41:  1363 
• 6b Herrmann WA. Öfele K. Schneider SK. Herdtweck E. Hoffmann SD. Angew. Chem. Int. Ed.  2006,  45:  3859 
• 6c Diebolt O. Braunstein P. Nolan SP. Cazin CSJ. Chem. Commun.  2008,  3190 
• 6d Organ MG. Çalimsiz S. Sayah M. Hoi KH. Lough AJ. Angew. Chem. Int. Ed.  2009,  48:  2383 
• 7 Palladacycles: Synthesis, Characterization and Applications   Dupont J. Pfeffer M. Wiley-VCH; Weinheim: 2008. 
• 8a Bedford RB. Cazin CSJ. Chem. Commun.  2001,  1540 
• 8b Schnyder A. Indolese AF. Studer M. Blaser H.-U. Angew. Chem. Int. Ed.  2002,  41:  3668 
• 8c Bedford RB. Cazin CSJ. Hazelwood SL. Angew. Chem. Int. Ed.  2002,  41:  4120 
• 9 Navarro O. Kelly RA. Nolan SP. J. Am. Chem. Soc.  2003,  125:  16194 
• 10 Alacid E. Alonso DA. Botella L. Nájera C. Pacheco MC. Chem. Rec.  2006,  6:  117 
• 11a Alonso DA. Nájera C. Pacheco MC. Org. Lett.  2000,  2:  1823 
• 11b Alonso DA. Nájera C. Pacheco MC. J. Org. Chem.  2002,  67:  5588 
• 12a Botella L. Nájera C. Angew. Chem. Int. Ed.  2002,  41:  179 
• 12b Botella L. Nájera C. J. Organomet. Chem.  2002,  663:  46 
• 12c Alacid E. Nájera C. J. Organomet. Chem.  2009,  694:  1658 
• 13 Appukkuttan P. Van der Eyken E. Eur. J. Org. Chem.  2008,  1133 
• 14 Netherton MR. Fu GC. Org. Lett.  2001,  3:  4295 
• 16 Goubet D. Meric P. Dormoy J.-R. Moreau P. J. Org. Chem.  1999,  64:  4516 
• 18a

  p-Biphenylacetic acid(felbinac) and 2-ethyl-4-biphenylacetic acid with dimethylaminoethanol-(namoxyrate) are anti-inflamatory and analgesic drugs, respectively: USP Dictionary of USAN and International Drugs names.

• 18b p-Biphenylacetamides have been used as mesogenic arms in porphyrin thermotropic liquid crystals: Michaeli S. Hugerat M. Levanon H. Bernitz M. Natt A. Neumann R. J. Am. Chem. Soc.  1992,  114:  3612 

15

At this point, the efficiency of the previously tested phosphane ligands with TBAOH as additive was tested again, showing in all cases lower activities. For example, P(t-Bu)₃ only led to a 31% isolated yield of 4a.

17

Typical Procedure for the Suzuki Coupling under MW Irradiation Conditions (Table 2, Entry 3)
A freshly stock soln of catalyst 1 (150 µg, 0.019 mmol) in DMF (2.5 mL) and [HP(t-Bu)₃]BF₄ (110 g, 0.0375 mmol) in DMF (2.5 mL) were previously prepared and used. A 10 mL MW vessel was charged with K₂CO₃ (1.5 mmol, 207 mg), TBAOH (0.15 mmol, 120 mg), PhB(OH)₂ (1.88 mmol, 225 mg), catalyst 1 (250 µL of the stock soln, 0.0019 mmol, 15 µg, 0.5 mol% Pd), [HP(t-Bu)₃]BF₄ (250 µL of the stock soln, 0.00375 mmol, 11 µg), 4-chloroanisole (0.75 mmol, 92 µL), and DMF (1.5 mL). The vessel was sealed with a pressure lock, and the mixture was heated in air at 130 ˚C by a MW irradiation of 40 W for 20 min in a CEM Discover MW reactor. After allowing the reaction to cool down to r.t., the mixture was filtered through a pad of Celite and poured into an excess of H₂O (5 mL) and extracted with Et₂O (3 × 5 mL). The combined organic phases were washed with H₂O (3 × 5 mL), dried (MgSO₄), and evaporated. The obtained crude product was purified by recrystallization in MeOH-H₂O (3:1), yielding 102 mg of pure 4-methoxybiphenyl (4a, 74%) as a white solid; mp 89-93 ˚C. ^¹H NMR (300 MHz, CDCl₃): δ = 7.57-7.51 (m, 4 H, ArH), 7.42 (t, J = 7.5 Hz, 2 H, ArH), 7.30 (t, J = 7.2 Hz, 1 H, ArH), 6.98 (d, J = 8.7 Hz, 2 H, ArH), 3.86 (s, 3 H, CHO). MS (EI, 70 eV): m/z (%) = 184 (100) [M⁺], 169 (49) [M⁺ - Me], 141 (49), 139 (13), 115 (35).