Abstract: Pyrido[2,3-d]pyrimidine-2,4,7-triones with reactive substituents in the 5- and 6-
position were used as synthons for new polyheterocyclic systems. 5-azido-6-phenyl derivatives
1 (X= N3, Y = Ph) cyclize thermally to indoles 2, 5-azido-6-nitro compounds 1 (X=
N3, Y = NO2) react to furoxanes 3, from 5-azido-6-acyl compounds 1 (X=N3, Y=COR) ring
closed isoxazoles 4 are obtained. Thermally induced cyclization to tetracyclic quinolines 5
is achieved with 5-phenylamino-6-formyl compounds 1 (X= NHPh, Y=CH=O). Reaction of
5-hydroxy-6-amino derivatives 1 (X= OH, Y= NH2) with acyl halides gives oxazoles 6. 5-Hydroxy
compounds 1 (X=OH, Y= H) react with malonates to give pyranes 7.
Determination of the suitable reaction conditions were investigated by DSC (differential
Scanning Calorimetry). Some of these compounds revealed interesting bioliogical activity.
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