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S y n t h e s i s o f S o m e N o v e l P y r i m i d o [ 1 , 2 -a ] b e n z i m i d a z o l e sAbstract: The synthesis of some potentially active 2-(trifluoromethyl)pyrimido[1,2-a]benzimidazoles and pyrimido[1,2-a]benzimidazol-2(1H)-ones by the cyclization of 4-alkoxyvinyl trifluoro(chloro)methyl ketones with 2-aminobenzimidazole is described. The structure of the products was assigned based on 1 H and 13 C NMR as well as 2D-NMR experiments. Some of the obtained products exhibited significant DNA-topoisomerase I inhibitory activity.

Reaction of 4-trichloromethyl-1H-pyrimidin-2-ones with 5-bromo-1,1,1-trichloro(fluoro)-4-methoxy-alk-3-en-2-ones affords 1-[5,5,5-trichloro(fluoro)-2-methoxy-4-oxopent-2-en-1-yl]-4-trichloromethyl-1H-pyrimidin-2-ones. Reaction of the latter trichloromethylated compound with amines, hydroxylamine, and hydrazines affords a series of 1-(2-alkylamine-5,5,5-trichloro-4-oxopent-2-en-1-yl)-4-trichloromethyl-1H-pyrimidin-2-ones and 1-(5-trichloromethyl-5-hydroxy-4,5-dihydro-3-azol-3-ylmethyl)-4-trichloromethyl-1H-pyrimidin-2-ones, respectively.

N-Alkylation of pyrimidinone (II) with enones (I) permits a convenient synthesis of the substitution products (III). Their utility for the synthesis of derivatives and a variety of heterocycles is demonstrated. -(ZANATTA*, N.; FLORES, D. C.; AMARAL, S. S.; BONACORSO, H. G.; MARTINS, M. A. P.; FLORES, A. F. C.; Synlett 2005, 20, 3079-3082; Dep. Quim., Univ. Fed. Santa Maria, 97119 Santa Maria, Rio Grande do Sul, Brazil; Eng.) -Mais 17-158

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