2-Aminobenzimidazole (1a) and its 5,6-dimethyl derivative 1b react with phenylpropynenitrile (2) to give 2-amino-4-phenylpyrimido[1,2-a]benzimidazoles 8a,b in excellent yields. Of these compounds, 2-amino-7,8-dimethyl-4-phenylpyrimido[1,2-a]benzimidazole (8b) has been shown to possess diuretic properties. Acetylenic aldehydes 9a,b also react with 1a,b to give pyrimido[1,2-a]benzimidazoles 13a-13d in good yield.

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2-Aminobenzimidazole (1a) and its 5,6-dimethyl derivative 1b react with 4-hydroxy-2-alkynenitriles 2a-d in ethanol under reflux to give 2-amino-4-(1'-hydroxyalkyl)pyrimido[1,2-a]-benzimidazoles 5a-e and in dimethylformamide at 155°C to give (2,2-dialkyl-2,3-dihydrooxazolo[3,2-a]benzimidazolylidene)ethanenitriles 7a-e.

Two new complexes of nickel (II) with 4-amino-3, 5-bis(pyridyl)-1, 2, 4-triazole (abpt) and iron (II) with 2-(3-phenyl-1H-pyrazole-5-yl) pyridine (phpzpy) have been synthesized and characterized by elemental analysis and IR spectroscopy. The crystal structures of the complexes have been determined by single crystal X-ray diffraction techniques. In the nickel and iron complexes, the ligands are coordinated through nitrogen atoms in bidentate manner. The ligands and their respective complexes have been tested for their antifungal activity againstAspergillus niger, Aspergillus flavus,andCandida albicans. From the study, the complexes showed enhanced activities against the tested organisms compared to the ligands.

Hydroxy-4,4-dialkylbut-2-ynenitriles add primary amines and ring close to give 5-amino-2,2-dialkyl-3-(alkylimino) -2,3-dihydrofurans whereas secondary amines similarly yield 5 -i mi no -2,2 -d i a I kyl-3 -(dia I kylami no) 4 5 -d i hydrof u ra ns.