5.6- Diaminopyrimidine, reaction with 1,2-dicarbonyl compounds

The use of 2,6-diaminopyrimidin-4-one 52 in a related solution phase cyclo condensation reaction with various aldehydes and 1,3-dicarbonyl compounds furnished a number of pyrido[2,3-d]pyrimidines 53 [102], The ZnBr2-catalyzed reactions proceeded much faster under microwave heating conditions than in an oil-bath, requiring only 20 min dielectric heating at 160 °C (vs. 3 days at 110 °C with oil-bath heating) to go to comple-... 

In this type of reaction, certain diaminopyrimidines were transformed into pterins by condensation with a 1,2-dicarbonyl compound, such as 2,3-butanedione. 

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