ABSTRACT Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that rapid isomerization was accomplished with sodium tert-butoxide (tBuONa), and the exo-content at the equilibrium was ca. 60%. The hydrolyses of endo-rich MNBC (endo/exo = 80/20) under various conditions were carried out. The exo selectivity for resulting NBCA was improved when the hydrolysis was conducted with equimolar water at room temperature in the presence of the stronger base (tBuONa) (endo/exo: 18/82). Whereas the use of excess amount of water led to rapid and non-selective hydrolysis affording high endo content of the product. The plausible reaction mechanism involving rapid equilibrium of thermodynamic isomerization and kinetically preferred hydrolysis of exo ester is proposed.
Cite this paper
M. Kanao, A. Otake, K. Tsuchiya and K. Ogino, "Stereo-Selective Synthesis of 5-Norbornene-2-exo-carboxylic Acid—Rapid Isomerization and Kinetically Selective Hydrolysis," International Journal of Organic Chemistry, Vol. 2 No. 1, 2012, pp. 26-30. doi: 10.4236/ijoc.2012.21005.
 R. Hoffmann and R. B. Woodward, “Orbital Symmetries and endo-exo Relationships in Concerted Cycloaddition Reactions,” Journal of American Chemical Society, Vol. 87, No. 19, 1965, pp. 4388-4389.
 A. C. Kinsman and M. A. Kerr, “Highly Selective Diels-Alder Reactions of Dienophiles with 1,3-Cyclo-hexadiene Mediated by Yb(OTf)3?2H2O and Ultra-high Pressures,” Organic Letters, Vol. 2, No. 22, 2000, pp. 3517-3520. doi:10.1021/ol0065773
 C. Janiak and P. G. Lassahn, “Metal Catalysts for the Vinyl Polymerization of Norbornene,” Journal of Molecular Catalysis A, Vol. 166, No. 2, 2001, pp. 193-209.
 C. W. Bielawski and R. H. Grubbs, “Living Ring-Open- ing Metathesis Polyme-rization,” Progress in Polymer Science, Vol. 32, No. 1, 2007, pp. 1-29.
 M. D. Rahman, D. S. McKenzie, J. B. Bae, T. Kudo, W. K. Kim, M. Padmana-ban and R. R. Dammel, “Novel Hybrid Copolymers of Cycloo-lefin/Maleic Anhydride (COMA)/Methacrylate for 193-nm Resist Compositions,” Proceedings of the 18th International Society for Optical Engineering, Advances in Resist Technology and Processing, Santa Clara, Vol. 4345, 25 February-2 March 2001, pp. 159-167.
 K. Nakano, S. Iwasa, K. Maeda and E. Hasegawa, “Thermally Stable Alkylsulfonium Salts for ArF Excimer Laser Resists,” Journal of Photopolymer Science and Technology, Vol. 14, No. 3, 2001, pp. 357-362.
 J. M. Pollino, L. Stubbs and M. Weck, “Living ROMP of exo-Norbornene Esters Possessing PdII SCS Pincer Complexes or Diaminopyridines,” Macromolecules, Vol. 36, No. 7, 2003, pp. 2230-2234. doi:10.1021/ma025873n
 Mitsubishi Rayon Co. Ltd., “Production Method of 5-Norbornene-2-carboxylic Acid and Its Esters,” JP patent No. JP2006-160712AO, 2006.
 V. E. Gouverneur, K. N. Houk, B. de-Pascual-Teresa, B. Beno, K. D. Janda and R. A. Lerner, “Control of the exo and endo Pathways of the Diels-Alder Reaction by Antibody Catalysis,” Science, Vol. 262, No. 5131, 1993, pp. 204-208. doi:10.1126/science.8211138
 J. M. Fraile, J. I. Garc?′a, D. Gracia, J. A. Mayoral and E. Pires, “First Asymmetric Di-els-Alder Reactions of Furan and Chiral Acrylates Usefulness of Acid Heterogeneous Catalysts,” Journal of Organic Chemistry, Vol. 61, No. 26, 1996, pp. 9479-9482. doi:10.1021/jo961513k
 A. Avenoza, M. P. Bueno, C. Cativiela and J. A. Mayoral, “Asymmetric Synthesis of Exo-Norbornane-2-carboxylic Acids,” Tetrahedron: Asymmetry, Vol. 3, No. 3, 1992, pp. 343-346. doi:10.1016/S0957-4166(00)80270-0
 M. Kawamura and K. Kudo, “Exo-Selective Asymmetric Diels-Alder Reaction of Acrylate Ester,” Chirality, Vol. 14, No. 9, 2002, pp. 727-730. doi:10.1002/chir.10130
 J. D. Roberts, E. R. Trumbull Jr., W. Bennett and R. Armstrong, “The Reaction of Norbornylene with N-Bromosuccinimide Nortricyclene and Its Derivatives,” Journal of American Chemical Society, Vol. 72, No. 7, 1950, pp. 3116-3124. doi:10.1021/ja01163a086
 C. D. Ver Nooy and C. S. Rondestvedt Jr., “Formation of Nortricyclene Derivatives by Bromination of exo-2,5-Methylene-1,2,5,6-tetrahydrobenzoic Acids,” Journal of American Chemical Society, Vol. 77, No. 13, 1955, pp. 3583-3586. doi:10.1021/ja01618a048
 M. Kanao, A. Otake, K. Tsuchiya and K. Ogino, “Stereo-Selective Synthesis of exo-Norbornene Derivatives for Resist Materials,” Journal of Photopolymer Science and Technology, Vol. 22, No. 3, 2009, pp. 365-370. doi:10.2494/photopolymer.22.365
 S. Niwayama and Y. Hiraga, “New exo/endo Selectivity Observed in Monohydrolysis of Dialkyl Bicyclo[2.2.1]- hept-5-ene-2,3-dicarboxylates,” Tetrahedron Letters, Vol. 44, 2003, pp. 8567-8570.