5-Aminouracil as a Building Block in Heterocyclic Synthesis, Part II. One-pot Synthesis of Pyrido[3,2-d:6,5-d′]dipyrimidines under Microwave Irradiation without Catalyst

The derivatives of fused pyrimidines are valued not only for their rich and varied chemistry, but also for many important biological properties [1 – 3]. Among them, the pyridodipyrimidines (PDP) have been shown to exhibit antibacterial and antiviral properties [4, 5] as well as NAD-type redox catalytic activity [6 – 10]. A few methods are reported in the literature for the preparation of pyrido[2,3-d:6,5-d′]dipyrimidine2,4,6,8-tetrones [4 – 18], but to the best of our knowledge, there are no reports in the literature for the formation of pyrido[3,2-d:6,5-d′]dipyrimidine-2,4,6,8tetrones. Recently, we described a new, simple and efficient synthesis of 6,7,8,10-tetrahydropyrimido[5,4-b]quinoline-2,4,9-(1H,3H,5H)-triones (4) [19], by the reaction of 5-aminouracil (1), benzaldehyde derivatives 2 and dimedone (3) under microwave irradiation without catalyst, which could have interesting effects on biological targets (Scheme 1).