T 037204

The reactions of diendo- or diexo-aminonorbornenecarboxylic acids, esters or hydrazides, with bi- or trifunctional reagents lead to condensed heterocycles. When these are heated to their melting point or boiled in an organic solvent, cyclopentadiene is cleaved off and mono-, bi- or tricyclic hetero compounds are formed. The method does not require extreme conditions or special tools such as flash vacuum pyrolysis, and is suitable for the formation of heterocycles on a preparative scale. The ready acces of the target compounds can be explained by the formation of a quasi-aromatic structure, i.e. an oxazinone, oxazinedione or thioxooxazinone ring containing the O and N heteroatoms in the 1,3-positions or, starting from hydrazides, two nitrogens in vicinal positions.

The project is aimed at the preparation of new condensed hetero compounds and is intended to establish the scope and limitations of the new method. On application of a double retro Diels-Alder process, the two reactants are built onto different molecules of cyclopentadiene. According to the literature, furan can readily be split off by heating from the parent compounds. Accordingly, the extension of the method to the oxanorbornenes, i.e. starting from furan and building up the molecules on it, is also planned. By means of this modification, new types of heterocycles not containing an aromatic structure are expected to be synthesized.