Heterocyclic studies. Part XVII. Some 2,3-dihydroimidazo-[1,2-a]- and [1,2-c]-pyrimidines

A number of 7-substituted 2,3-dihydro-5-methyl-8-nitroimidazo[1,2-c]pyrimidines (III; X = OH, OMe, SH, NH2, NHMe, NMe2, or NH·CH2Ph) were synthesised by treatment of 4-chloro-6-(2-chloroethylamino)-2-methyl-5-nitropyrimidine with nucleophilic reagents and cyclisation of the resulting intermediates. Some 5-(substituted amino)-2,3-dihydro-7-methyl-8-nitroimidazo[1,2-c]pyrimidines (V; X = NHEt or NH·CH2Ph) were similarly prepared from 2-chloro-4-(2-chloroethylamino)-6-methyl-5-nitropyrimidine.Cyclisation of 4-(substituted amino)-2-(2-chloroethylamino)-6-methyl-5-nitropyrimidines gave 7-(substituted amino)-2,3-dihydro-5-methyl-6-nitroimidazo[1,2-a]pyrimidines (VII; X = NH2, NHMe, NHEt, or NH·CH2Ph) rather than the 7-methyl isomers (VIII). One of the 7-methyl isomers (VIII; X = NHEt) was synthesised by an alternative route. 1 H N.m.r. spectra of 14 of the compounds are recorded.