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matography on Al2O3, eluents benzene (7:3) and
benzene acetonitrile (1:1). Yield of 9-methylpyrido-
[1,2-a]benzimidazole (IV) 0.35 g (60%).
from 2-propanol. Yield 20%, mp 172 173 C, dark
gray powder.
6,7,8,9-Tetrafluoro-1,3-dimethylpyrimido[1,2-a]-
benzimidazolium perchlorate (Ve). Sodium picrate,
0.055 g, in 10 ml of acetonitrile was added to a solu-
8-Chloro-5-ethyl-1,3-dimethylpyrimido[1,2-a]-
benzimidazolium perchlorate (Va). 8-Chloro-1,3-
dimethylpyrimido[1,2-a]benzimidazole (IIIb), 0.195 g, tion of 0.1 g of tosylate Vb in 10 ml of chloroform,
and 0.17 g ethyl tosylate were heated for 5 h at 120
125 C. The mixture was cooled, washed with ether,
treated with 2-propanol, and filtered. The filtrate was
evaporated, the dry residue was dissolved in 15 ml of
acetonitrile, treated with 0.122 g of Co(ClO4)2 2H2O
in 10 ml of 2-propanol, and left to stand for 0.5 h.
After cooling with ice, the cobalt tosylate precipitate
was filtered off and washed with chloroform. The
filtrate was evaporated, and the residue was recrystal-
lized from 2-propanol.
and the mixture was left to stand for 0.5 h. After
cooling, the sodium tosylate precipitate was filtered
off, the filtrate was evaporated, the residue was dis-
solved in chloroform, the solution was filtered, the
filtrate was evaporated, and the residue was dried to
obtain a dark orange powder, mp 52 55 C.
6,7,8,9-Tetrafluoro-1,3-dimethylpyrimido[1,2-a]-
benzimidazolium iodide (Vf). a. A mixture of tetra-
fluoroazinazole IIIc, 0.1 g, ethyl iodide, 10 ml, and
15 ml of acetonitrile was refluxed for 10 h. The reac-
tion progress was followed by TLC on Silufol plates
(UV-Vis, acetonitrile). The solvent was distilled off,
the residue was washed with ether, and dried; chro-
matographically and spectrally the product was iden-
tical to iodide Vf obtained by method b.
6,7,8,9-Tetrafluoro-1,3-dimethylpyrimido[1,2-a]-
benzimidazolium tosylate (Vb). Tetrafluoroazinazole
IIIc, 1 g, and 0.75 g of ethyl tosylate were heated at
120 C for 6 h. The reaction progress was followed by
the consumption of base IIIc by TLC on Silufol
plates, eluent acetonitrile benzene, 1:1. After the re-
action was complete, the reaction mixture was cooled
and washed with ether, dissolved with heating in
2-propanol, filtered, the filtrate was evaporated, and
the residue was dried. Yield 95%. The light brown
glassy material was powdered.
b. A solution of 0.035 g of KI in 10 ml of aceto-
nitrile was added to a solution of 0.1 g of tosylate Vb
in 10 ml of chloroform. The mixture was left to stand
for 0.5 h, after which the precipitate was filtered off
and washed with chloroform. The filtrate was eva-
porate, the dry residue was dissolved in chloroform,
the solution, if necessary, was filtered, the solvent was
distilled off, and the residue was dried to obtain a
light yellow material, mp 45 50 C. According to IR
data, it contained a potassium tosylate admixture.
Chromatographically and spectrally the product was
identical to iodide Vf obtained by method a.
6,7,8,9-Tetrafluoro-1,3-dimethylpyrimido[1,2-a]-
benzimidazolium perchlorate (Vc). Tosylate Vb,
0.2 g, in 20 ml of chloroform was added to a solution
of 0.063 g of Co(ClO4)2 2H2O in acetonitrile, and
the mixture was left to stand for 0.5 h, and cooled.
The cobalt tosylate precipitate was filtered off and
washed with chloroform. The filtrate was evaporated
and dried. Yield 80%. The light orange glassy
material was powdered, mp 70 75 C (deliquesces),
5-Ethyl-9-methylpyrido[1,2-a]benzimidazolium
iodide (VI) and 7-ethyl-5-methylquino[1,2-a]-
benzimidazolium iodide (VII) were obtained by
alkylation of 9-methylpyrido[1,2-a]benzimidazole
(IV) and 5-methylquino[1,2-a]benzimidazole (0.1 g),
respectively, with ethyl iodide (10 ml) in acetonitrile
(15 ml), refluxing for 3 4 h. The reaction progress
was followed by the consumption of the starting base
by TLC on Silufol plates (UV-Vis, eluent acetonitrile).
The solvent was removed, the precipitate was washed
with ether, suspended in ether, and filtered off.
1
155 158 S (decomp.). H NMR spectrum (Me2CO-
d6), , ppm (J, Hz): 1.62 t (Me), 2.64 s (Me), 3.26 s
(Me), 4.93 q (CH2, 3), 7.93 s (H2). 19F NMR spec-
trum (Me2SO-d6, relative to C6F6), F, ppm (J, Hz):
135.1 m (1F, 4, 10), 152.7 t.d (1F, 4, 21),
158.4 d.d (1F, 21), 159.6 t (21).
6,7,8,9-Tetrafluoro-5-ethyl-1,3-dimethylpyri-
mido[1,2-a]benzimidazolium tetraphenylborate
(Vd). A solution of 0.073 g of NaBPh4 in 10 ml of
acetonitrile was added to a solution of 0.1 g of
tosylate Vb in 15 ml of chloroform. The mixture was
left to stand for 0.5 h and then cooled. The sodium
tosylate was filtered off, washed with chloroform, and
the filtrate was evaporated. The residue was dissolved
in chloroform, the solution was filtered, the filtrate
was evaporated, and the dry residue was crystallized
6,7,8,9-Tetrafluoro-1-{3-(6,7,8,9-tetrafluoro-5-
ethyl-3-methylpyrimido[1,2-a]benzimidazol-1-
ylidene)-1-propenyl}-5-ethyl-3-methylpyrimido-
[1,2-a]benzimidazolium tosylate (VIIIa). Triethyl
orthoformate, 0.25 g, and one drop of acetic anhydride
were added to a solution of 0.2 g of 6,7,8,9-tetrafluoro-
5-ethyl-1,3-dimethylpyrimido[1,2-a]benzimidazolium
tosylate (Vb) in 2 ml of pyridine. The mixture was
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 3 2002
Frolov
