Microwave-Assisted Synthesis of Camphor-Derived Chiral Imidazolium Ionic Liquids and Their Application in Diastereoselective Diels-Alder Reaction

Abstract

Starting from cheap chiral pool precursors camphorsulfonic acid and camphene, several imidazolium ionic liquids were synthesized in high overall yield. Both thermal and microwave-assisted­ synthesis was used in the quaternization step to obtain new chiral ionic liquids (CILs) bearing a bornyl structural motif as cation. Furthermore, these CILs were used as solvent in the Diels-Alder­ reaction of acrylic acid and cyclopentadiene and showed good yields and diastereoselectivities.

Key words

ionic liquids - microwave synthesis - imidazolium salts - Diels-Alder reaction - diastereoselectivity

References

• For reviews:
• 1a Wasserscheid P. Keim W. Angew. Chem. Int. Ed.  2000,  39:  3772 
• 1b Olivier-Bourbigou H. Magna L. J. Mol. Catal. A: Chem.  2002,  182-183:  419 
• 1c Wasserscheid P. Welton T. Ionic Liquids in Synthesis   Wiley-VCH; Weinheim, Germany: 2003. 
• For reviews:
• 2a Baudequin C. Brégeon D. Levillain J. Guillen F. Plaquevent J.-C. Gaumont A.-C. Tetrahedron Asymmetry  2005,  16:  3921 
• 2b Ding J. Armstrong DW. Chirality  2005,  17:  281 
• 3a Arduengo AJ. Harlow RL. Kline M. J. Am. Chem. Soc.  1991,  113:  361 
• 3b Hermann WA. Koecher C. Angew. Chem., Int. Ed. Engl.  1997,  36:  2162 
• 4 Oppolzer W. Tetrahedron  1987,  43:  1969 
• 5 Machado MY. Dorta R. Synthesis  2005,  2473 
• 6 Nobuoka K. Kitaoka S. Kunimitsu K. Iio M. Harran T. Wakisaka A. Ishikawa Y. J. Org. Chem.  2005,  70:  10106 
• 7 Gadenne B. Hesemann P. Moreau JJE. Tetrahedron Lett.  2004,  45:  8157 
• 8 Yarovaya OL. Korchagina DV. Gatilov YV. Barkash VA. Russ. J. Org. Chem.  2002,  38:  810 
• 9 Avery JS. Burbridge CD. Goodgame DML. Spectrochim. Acta  1968,  24A:  1721 
• 10a Sitze MS. Schreiter ER. Patterson EV. Freeman RG. Inorg. Chem.  2001,  40:  2298 
• 10b Hayashi S. Hamaguchi H. Chem. Lett.  2004,  33:  1590 
• 11 Friedman HL. J. Am. Chem. Soc.  1952,  74:  5 
• 12 Meracz I. Oh T. Tetrahedron Lett.  2003,  44:  6465 
• 13 Earle MJ. McComac PB. Seddon KR. Green Chem.  1999,  1:  23 
• 14 Howarth J. Hanlon K. Fayne D. McCormac P. Tetrahedron Lett.  1997,  38:  3097 
• 15 Janus E. Goc-Maciejewska I. Łożyński M. Pernak J. Tetrahedron Lett.  2006,  47:  4079 
• 16 Pegot B. Van Buu O. Gori D. Vo-Than G. Beilstein J. Org. Chem.  2006,  2:  18 
• 17 Buston J. Coldham I. Mulholland K. J. Chem. Soc., Perkin Trans. 1  1999,  2327 
• 18 Zeijden AAH. Mattheis C. Synthesis  1996,  847 
• 19 Arehart SV. Pugh C. J. Am. Chem. Soc.  1997,  119:  3027