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The Preparation of 7-Substituted Norbornadiene-2,3-dicarboxylic Anhydrides and a Theoretical and Experimental Study of their Thermolysis to 5-Membered Carbocyclic or Heterocyclic Anhydrides
* 1 , 2 , 3 , 2
1  Laboratory for Physical Organic Chemistry, Department of Organic Chemistry and Biochemistry, Ruder Boškovic Institute, Bijenicka c. 54, 10000 Zagreb, Croatia
2  Intelligent Polymer Research Institute, The University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia
3  Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA

Abstract: New substituted methano-bridged or heteroatom-bridged norbornadienomaleic anhydrides have been prepared and converted to sesquinorbornadiene anhydrides by reaction with cyclic 1,3-dienes. The versatility of parity reversal, in conjuction with N-substituent steric effects, has been used to produce stereoisomers of the N,O-sesquinorbornadiene anhydrides in separate, stereoselective cycloadditions. The anhydrides have been synthesized by cyclisation of their diacids (in situ production) or by flash vacuum pyrolysis of their furan adducts (yielding crystalline products); further fragmentation occurs at these or higher temperatures to produce five-membered carbocyclic or heterocyclic anhydrides. Activation energies have been evaluated for the two fragmentation processes and Diels-Alder reactions using DFT calculations (B3LYP/6-31G*) and these calculations correctly predict which reactions can be intercepted at the norbornadienomaleic anhydride stage.
Keywords: n/a