Synthesis
General procedure for the synthesis of (3aR,4S,7R,7aS)-rel-hexahydro-4,7-methanoisobenzofuran-1,3-dione from cis-5-norbornene-exo-2,3-dicarboxylic anhydride: 200 g of cis-5-norbornene-exo-2,3-dicarboxylic anhydride (from step 2) was mixed with 1.5 L of toluene, heated until completely dissolved, and then transferred to a 4-L high pressure reactor. 10 g of Pd/Pt catalyst was added to the reactor and the system was purged under 10 bar hydrogen pressure for 5 minutes. After purging, the hydrogen pressure was adjusted to 12 bar and the hydrogenation reaction was carried out at 160°C and 20 bar hydrogen pressure. After the reaction lasted 70 minutes, the catalyst was removed. The reaction mixture was transferred to 5 L of hexane and after filtration and drying, 182 g of white solid product (compound 4) was obtained. The structure of the product was confirmed by NMR (1H and 13C NMR, JEOL JNM-LA400) and IR spectroscopy (AVATAR 360FT-IR). The relevant spectral data are displayed in Figures 1, 2, 4 and 5, respectively.
References
[1] Journal of Organic Chemistry, 1982, vol. 47, # 20, p. 3953 - 3959
[2] Organic Preparations and Procedures International, 1999, vol. 31, # 2, p. 220 - 222
[3] Chemical and Pharmaceutical Bulletin, 1991, vol. 39, # 9, p. 2288 - 2300
[4] Chemical and Pharmaceutical Bulletin, 1995, vol. 43, # 12, p. 2139 - 2151
[5] Monatshefte fur Chemie, 2004, vol. 135, # 7, p. 839 - 847
