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8168206 
Journal Article 
Methyl(phenyl)pyrimido [1,2-a[benzimidazolium and 4-phenyl-1,2,4-triazolo [1,5-a]pyrimidinium compounds 
Chuiguk, VA; Manzhos, AV 
1988 
54 
8 
101-103 
English 
The preparation of an unknown 1-substituted pyrimido[1,2-a]benzimidazolium salts (II) by the reaction of secondary amines with 1,3-dikestones in the presence of acids is described. The authors used a scheme in the pyrazole and indiazole series, which led to the preparation of 1-substituted pyrazolo[1,5-b]pyrimidinium and pyrimido[1,2-b]indiazolium compounds and in the tetrazole series, where 2-azido-1-phenylpyrimidinium salts were obtained. 2-Methylamino- and 2-anilinobenzimidazoles react according to the scheme presented with participation of trifluoroacetic acid to form salts II after reaction with sodium perchlorate. The latter are yellow or orange colored, in contrast to the colorless isomeric salts I. Upon using 1,2-methylaminobenzimidazole and an asymmetric diketone (benzoyl-acetone in the scheme), one of the two possible isomers, namely IIb, is obtained, the structure of which was clearly confirmed by its PMR spectrum.