Via the reaction of diexo-oxanorbornanedicarboxylic anhydride with toluene, the diexo-aroylcarboxylic acid (3a) was prepared, which exists partly as the tautomeric lactol (3b). With bifunctional reagents, 3a yields fused heterocycles containing three-six rings. Thus, alkylenediamines result in imidazole- and 1,3-diazepine-fused oxygen-bridged isoindolones (6a,b), alkanolamines form the oxazole- and 1,3-oxazine-fused oxanorbornene derivatives (7a-c), and o-phenylenediamine undergoes cyclization to furnish the condensed benzimidazole (8). The reaction of 3a with diexo-aminonorbornanecarbohydrazide yields a pyrimidopyridazine containing six condensed rings (9). In a similar reaction with diendo-aminonorbornenecarbohydrazide, cyclopentadiene cleaves off to give the tricyclic retro Diels-Alder product (10). The structures, and particulary the configurations at the oxanorbornane ring systems and the position of the aryl substituent, were established by means of 1D- and 2D-NMR spectroscopy and, for 3b and 7c, also by X-Ray measurements.
|Number of pages||12|
|Publication status||Published - Jan 1 2004|
ASJC Scopus subject areas
- Analytical Chemistry
- Organic Chemistry