1,3-Dimethylbarbituric acid was used as a versatile precursor for the
preparation of annelated pyranopyrimidines 2 and 3a-c besides pyrrolop
yrimidine 12. The isolated pyrazolopyrimidines 8a-c and 10 and fused p
yrazolopyrimidines 14a-d were also synthesized. In addition the new ob
tained pyrimidoheterocycles were subjected to bacterial testings.