Enantioselective Rh-Catalyzed Addition of Arylboronic Acids to N-Tosylarylimines

Abstract

A highly enantioselective rhodium-catalyzed addition of arylboronic acids to N-tosylarylimines is described, using chiral ­binaphtholic phosphite and phosphoramidite ligands. The best ee values (76-99%), associated with moderate to good chemical yields, were obtained with binaphtholic phosphoramidite ligands containing a bulky chiral amine.

Key words

arylations - arylboronic acids - asymmetric catalysis - imines - rhodium

References and Notes

• 1a Plobeck N. Delorme D. Wei Z.-Y. Yang H. Zhou F. Schwarz P. Gawell L. Gagnon H. Pelcman B. Schmidt R. Sue S.-Y. Walpole C. Brown W. Zhou E. Labarre M. Payza K. St-Onge S. Kamassah A. Morin P.-E. Projean D. J. Med. Chem.  2000,  43:  3878 
• 1b Carson JR. Coats SJ. Codd EE. Dax SL. Lee J. Martinez RP. Neilson LA. Pitis PM. Zhang S.-P. Bioorg. Med. Chem. Lett.  2004,  14:  2109 
• 2a Hermanns N. Dahmen S. Bolm C. Bräse S. Angew. Chem. Int. Ed.  2002,  41:  3692 
• 2b Schmidt F. Stemmler RT. Rudolph J. Bolm C. Chem. Soc. Rev.  2006,  35:  454 
• 2c Bräse S. Baumann T. Dahmen S. Vogt H. Chem. Commun.  2007,  1881 
• 3a Hayashi T. Ishigedani M. J. Am. Chem. Soc.  2000,  122:  976 
• 3b Ueda M. Miyaura N. J. Organomet. Chem.  2000,  595:  31 
• 4 Hayashi T. Kawai M. Tokunaga N. Angew. Chem. Int. Ed.  2004,  43:  6125 
• 5a Miyaura N. Suzuki A. Chem. Rev.  1995,  95:  2457 
• 5b Hayashi T. Yamasaki K. Chem. Rev.  2003,  103:  2829 
• 5c Hall DG. Boronic Acids: Preparation and Applications in Organic Synthesis and Medicine   Wiley-VCH; Weinheim: 2005. 
• 6 Kuriyama M. Soeta T. Hao X. Chen Q. Tomioka K. J. Am. Chem. Soc.  2004,  126:  8128 
• 7a Tokunaga N. Otomaru Y. Okamoto K. Ueyama K. Shintani R. Hayashi T. J. Am. Chem. Soc.  2004,  126:  13584 
• 7b Otomaru Y. Tokunaga N. Shintani R. Hayashi T. Org. Lett.  2005,  7:  307 
• 8 Weix DJ. Shi Y. Ellman JA. J. Am. Chem. Soc.  2005,  127:  1092 
• 9 Duan H.-F. Xie J.-H. Shi W.-J. Zhang Q. Zhou Q.-L. Org. Lett.  2006,  8:  1479 
• 10 Jagt RBC. Toullec PY. Geerdink D. de Vries JG. Feringa BL. Minnaard AJ. Angew. Chem. Int. Ed.  2006,  45:  2789 
• 11a Monti C. Gennari C. Piarulli U. Tetrahedron Lett.  2004,  45:  6859 
• 11b Monti C. Gennari C. Piarulli U. de Vries JG. de Vries AHM. Lefort L. Chem. Eur. J.  2005,  11:  6701 
• 12a Monti C. Gennari C. Piarulli U. Chem. Commun.  2005,  5281 
• 12b Monti C. Gennari C. Piarulli U. Chem. Eur. J.  2007,  13:  1547 
• For recent reviews on combinatorial ligand libraries and high-throughput experimentation in homogeneous catalysis, see:
• 13a Gennari C. Piarulli U. Chem. Rev.  2003,  103:  3071 
• 13b de Vries JG. de Vries AHM. Eur. J. Org. Chem.  2003,  799 
• 13c Satyanarayana T. Kagan HB. Adv. Synth. Catal.  2005,  347:  737 
• 13d De Vries JG. Lefort L. Chem. Eur. J.  2006,  12:  4722 
• 13e Jäkel C. Paciello R. Chem. Rev.  2006,  106:  2912 
• 14a

  For the synthesis of ligands 1-6, see ref. 11.

• 14b For the synthesis of ligand 7, see: Reetz MT. Mehler G. Angew. Chem. Int. Ed.  2000,  39:  3889 
• 14c For the synthesis of ligands 8-10, see: Feringa BL. Pineschi M. Arnold LA. Imbos R. de Vries AHM. Angew. Chem., Int. Ed. Engl.  1997,  36:  2620 
• 14d For the synthesis of ligand 11, see: Choi YH. Choi JY. Yang HY. Kim YH. Tetrahedron: Asymmetry  2002,  13:  801 
• 15 Hayashi T. Ishigedani M. J. Am. Chem. Soc.  2000,  122:  976 
• 16 Recently, Trost and co-workers reported the successful use of ligand 11 in the palladium-catalyzed asymmetric [3+2] trimethylenemethane cycloaddition reactions: Trost BM. Stambuli JP. Silverman SM. Schwörer U. J. Am. Chem. Soc.  2006,  128:  13328 
• 17 Arnold LA. Imbos R. Mandoli A. de Vries AHM. Naasz R. Feringa BL. Tetrahedron  2000,  56:  2865 
• 19 Vedejs E. Lin S. J. Org. Chem.  1994,  59:  1602 

18

General Procedure for the Arylation of N -Tosylaryl-imines: In a flame-dried Schlenk tube flushed with nitrogen, Rh(acac)(C₂H₄)₂ (1.2 mg, 4.65 µmol, 3 mol%) and the ligand (9.30 µmol, 6 mol%) were dissolved in anhyd dioxane (0.75 mL). After stirring for 30 min at r.t., LiF (1.5 mmol) and the substrate (0.15 mmol) were added followed by the appropriate arylboronic acid (0.75 mmol). The resulting mixture was stirred at 50 °C for 24 h, quenched with H₂O (3 mL) and extracted with CH₂Cl₂ (3 mL). The organic phase was dried over Na₂SO₄ and the solvent was evaporated under vacuum. The residue was purified by flash chromatography on silica gel (n-hexane-EtOAc, 7:3) affording the N-tosyl-diarylmethylamine as a white solid.