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ANTINA et al.
extracted with diethyl ether, extract was dried with
sodium sulfate, concentrated, and distilled in a vacuum
of water-jet pump. Yield 9.9 g (50%). 1Н NMR
spectrum (CDCl3), δ, ppm: 1.87 s (3H, 4-CH3), 1.97 s
(3H, 2-CH3), 5.37 s (1H, H3), 5.92 s (1H, H5), 7.07 br.s
(1H, NH).
trum (CDCl3), δ, ppm: 0.24 s [9H, Si(CH3)3], 2.36 s
(6H, 3,5-CH3), 9.33 br.s (1H, NH), 9.47 s (1H, CHO).
2-Formyl-4-ethynyl-3,5-dimethylpyrrole (XIV).
To a solution of 0.35 g (1.60 mmol) of pyrrole XIII in
12 ml of THF was added 1.6 ml of 1.0 М solution of
tetrabutylammonium fluoride in THF. This mixture
was stirred for 1 h at room temperature, then poured
into Petri dish, and dried at room temperature. The
residue was dissolved in methylene chloride and
subjected to chromatography on a silica gel eluting
with methylne chloride and collecting the first yellow
zone. Then the eluate was concentrated. Yield 200 mg
(85%). IR spectrum, ν, cm–1: 3236 (NH), 2108 (C≡C),
1639 (СО). 1Н NMR spectrum (CDCl3), δ, ppm: 2.38 s
(6H, 3,5-CH3), 3.21 s (1H, ≡CH), 9.49 s (1H, CHO),
9.65 br.s (1H, NH).
2-Formyl-3,5-dimethylpyrrole (XI). To a solution
of 28.5 g (0.3 mol) of pyrrole X in 200 ml of DMF was
added 36.6 ml (0.4 mol) of phosphorus oxychloride at
15°С under stirring. This mixture was stirred at room
temperature for 1.5 h and poured into 900 ml of water,
then it was alkalinized with 20% KOН solution
(~2.4 mol). The precipitate was filtered off, washed
with water, and dried. Yield 28.9 g (78%), mp 88°С
(water). IR spectrum, ν, cm–1: 3242 (NH), 1639 (СО).
1Н NMR (CDCl3), δ, ppm: 2.20 s (3H, 5-CH3), 2.23 s
(3H, 3-CH3), 5.55 s (1H, H4), 9.13 s (1H, CHO), 11.20
br.s (1H, NH).
1,2-Bis(2'-formyl-3',5'-dimethyl-4'-pyrrolyl)-
acetylene (XV). A mixture of 0.40 g (2.72 mmol) of
pyrrole XIV and 0.68 g (2.72 mmol) of pyrrole XII
was dissolved in 25 ml of diethylamine. Then to this
mixture were added 35 mg (0.05 mmol) of dichlorobis
(triphenylphosphine)palladium(II) and 18.0 mg
(0.47 mmol) of copper(I) iodide. The mixture was
refluxed with Bunsen valve for 3 h to yield dark oil.
The mixture was poured into a Petri dish and kept at
room temperature to complete solvent removal. The
residue was extracted in Soxhlet apparatus with
methylene chloride, filtered off and dried at room
2-Formyl-4-iodo-3,5-dimethylpyrrole (XII). To a
solution of 3.0 g (24.4 mmol) of pyrrole XI in 30 ml of
methanol was gradually added under stirring a solution
of 6.2 g (24.4 mmol) of iodine and 4.1 g (24.4 mmol)
of potassium iodide in 20 ml of methanol and 20 ml of
water. This mixture was diluted with water to 200 ml,
the precipitate was filtered off, washed with sodium
hydrogen carbonate solution, with water, and dried.
The product was purified by extraction in Soxhlet
apparatus with petroleum ether, then filtered off and
dried in air at room temperature. Yield 4.1 g (68%),
mp 167–70°С (methanol). IR spectrum, ν, cm–1: 3207
(NH), 1636 (СО). 1Н NMR spectrum (CDCl3), δ, ppm:
2.28 s (3H, 5-CH3), 2.35 s (3H, 3-CH3), 9.48 s (1H,
CHO), 10.51 br.s (1H, NH).
1
temperature. Yield 0.6 g (82%). Н NMR spectrum
(CDCl3), δ, ppm: 2.31 s (6H, 5-CH3), 2.36 s (6H, 3-CH3),
9.50, (2H, CHO), 9.60 br.s (2H, NH).
1,2-Bis(2',4',7',9'-tetramethyl-8'-ethyldipyrrolyl-
methen-3'-yl)acetylene dihydrobromide (III·2HBr).
To a suspension of 0.54 g (2.0 mmol) of acetylene XV
and 0.5 g (4.1 mmol) of pyrrole XVI in 25 ml of
methanol was added 1.0 ml of concentrated
hydrobromic acid under stirring at room temperature
for 2 h. The the precipitate was filtered off, washed
with water, diethyl ether, and dried in air at room tem-
2-Formyl-4-[(trimethylsilyl)ethynyl]-3,5-dimethyl-
pyrrole (XIII). 1.0 g (4.0 mmol) of pyrrole XII,
50.0 mg (0.07 mmol) of dichlorobis(triphenylphos-
phine)palladium(II) and 26.0 mg (0.14 mmol) of cop-
per(I) iodide were dissolved in 40.0 ml of diethyl-
amine. Then to this mixture 0.9 ml (6.0 mmol) of tri-
methylsilylacetylene was added, and this solution was
refluxed with Bunsen valve for 1 h to obtain dark oil.
The mixture was poured into Petri dish and kept to
complete solvent evaporation. The residue was dis-
solved in methylene chloride and subjected to
chromatography on silica gel eluting with methylene
chloride and collecting the second bright yellow zone.
The eluate was concentrated and dried in air at room
temperature. Yield 0.8 g (91%). IR spectrum, ν, cm–1:
1
perature. Yield 0.54 g (42%). Н NMR spectrum
(CDCl3), δ, ppm: 1.08 t (6H, CH3–Et), 2.29 s (6H, 7'-
CH3), 2.32 s (6H, 2'-CH3), 2.43 q (4H, CH2–Et), 2.71 s
(12H, 4',9'-CH3), 7.06 s (2H, meso-H), 13.30 br.s (4H,
NH). ESP (CHCl3), λmax, nm (log ε): 491 (5.21).
2-Ethoxycarbonyl-4-acetyl-3,5-dimethylpyrrole
(XVII). To a solution of 200 ml (1.57 mol) of aceto-
acetic ester in 350 ml of acetic acid was added a solu-
tion of 109 g (1.57 mol) of sodium nitrite in 150 ml of
water under stirring (temperature below 30°С). The
1
3223 (NH), 2152 (C≡C), 1640 (СО). Н NMR spec-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 11 2010