Synthesis of n-vinylpyrroles from n-(2-hydroxyethyl)pyrroles

Full text of DOI:10.1134/S1070428011040257

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 4, pp. 614–615. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © B.F. Kukharev, V.K. Stankevich, V.A. Kukhareva, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 4,
pp. 607–608.
SHORT
COMMUNICATIONS
Synthesis of N-Vinylpyrroles from N-(2-Hydroxyethyl)pyrroles
B. F. Kukharev, V. K. Stankevich, and V. A. Kukhareva
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: irk_inst_chem@irioch.irk.ru
Received September 22, 2010
DOI: 10.1134/S1070428011040257
N-Vinylpyrrole derivatives exhibit versatile biologi-
cal activity and are promising as monomers and inter-
mediate products in the synthesis of a number of com-
pounds possessing practically important properties
[1, 2]. In the recent time, the most convenient method
for the preparation of these compounds is based on
reaction of ketone oximes with acetylene in the system
dimethyl sulfoxide–alkali metal hydroxide (Trofimov
reaction) [1, 2]. However, this procedure cannot be
used to synthesize N-vinylpyrroles from aldehyde
oximes because of concurrent dehydration of the latter
to form nitriles [3].
found that N-vinylindole IIa was formed in 60–68%
yield when compound Ia was heated over KOH at
280°C. The reaction was accompanied by formation of
an appreciable amount of a polymeric product insol-
uble in water (as still residue). Our attempts to carry
out the reaction under reduced pressure almost always
resulted in foaming of the alkali melt, its ejection from
the flask, and clogging of the descending condenser.
The yield of indole IIa increased as the moisture con-
tent of KOH rose. Therefore, subsequent dehydration
experiments were performed with simultaneous supply
of water into the reaction mixture. When the amount of
water was 10 wt % with respect to Ia, the yield of IIa
reached 96%. Obviously, the reason is formation of
a low-boiling azeotrope mixture of IIa with water,
which shortens its contact with alkali and hampers
polymerization.
We previously reported on the formation of
N-(2-hydroxyethyl)pyrroles in up to 73% yield as
a result of a number of base-catalyzed redox processes,
such as oxidation 2,2′-iminodietanol with cyclohexa-
none [4], cleavage of oxazolidines obtained from
carbonyl compounds and 2,2′-iminodietanol [5, 6], and
oxidation of these oxazolidines with carbonyl com-
pounds [7].
Likewise, from pyrroles Ib and Ic we obtained
N-vinyl derivatives IIb and IIc in 94–97% yield. In the
synthesis of low-boiling pyrroles IId and IIe the
process was performed without addition of water and
the yield of IId and IIe was 88–90%. N-Vinylpyrroles
IIb–IId were isolated as colorless liquids. The same
compounds obtained from ketone oximes and acety-
lene were described as colored liquids [2].
It is known that some nitrogen-containing hetero-
cyclic compounds having 2-hydroxyethyl substituents
are capable of undergoing dehydration by the action of
alkali to give the corresponding vinyl derivatives [8].
In the present work we examined dehydration of
N-(2-hydroxyethyl)-4,5,6,7-tetrahydro-1H-indole (Ia)
to N-vinyl-4,5,6,7-tetrahydro-1H-indole (IIa). We
Initial pyrrole Ie was synthesized from the corre-
sponding oxazolidine which was prepared in turn by
condensation of isovaleraldehyde with 2,2′-iminodi-
ethanol. Thus the proposed procedure ensures prepara-
tion of N-vinylpyrroles which cannot be obtained from
aldehyde oximes and acetylene. On the other hand, the
described procedure is more laborious (it includes
three steps), and the yield calculated on the initial
ketone is lower by 10–15% than in the synthesis
through ketone oximes.
R
R
KOH, 280°C
–H2O
R'
R'
N
N
CH2CH2OH
CH=CH2
Ia–Ie
IIa–IIe
RR′ = (CH2)4 (a), (CH2)5 (b); R = H, R′ = Ph (c); R = Me,
R′ = Et (d); R = i-Pr, R′ = H (e).
614

SYNTHESIS OF N-VINYLPYRROLES FROM N-(2-HYDROXYETHYL)PYRROLES
615
2-H). Found, %: C 79.74; H 9.77; N 10.21. C9H13N.
Calculated, %: C 79.95; H 9.69; N 10.36.
N-Vinylpyrroles IIa–IIc (general procedure).
A 100-ml steel flask equipped with dosing devices,
thermocouple, and descending condenser connected to
a receiver was charged with 40 g (0.71 mol) of potas-
sium hydroxide and was heated to 280°C. N-(2-Hy-
droxyethyl)pyrrole Ia–Ic, 0.1 mol, and water (10 wt %)
were supplied simultaneously to the flask over a period
of about 1 h. The distillate was treated with 50 ml of
diethyl ether, and the organic layer was separated,
dried over potassium carbonate, and distilled under
reduced pressure.
1
The H NMR spectrum was recorded on a Bruker
DPX-400 spectrometer (400 MHz) in CDCl3 at 26°C
using hexamethyldisiloxane as internal reference. The
IR spectrum (film) was obtained on a Specord 75IR
instrument. Initial N-(2-hydroxyethyl)pyrroles Ia–Ie
were synthesized by condensation of the corresponding
carbonyl compounds with 2,2′-iminodiethanol accord-
ing to the procedure described in [12], followed by
cleavage of N-(2-hydroxyethyl)oxazolidines thus
formed as reported in [6].
The synthesis of N-vinylpyrroles IId and IIe was
performed in a similar way but without addition of
water. The purity of compounds IIa–IIe was 99.3–
99.7% according to the GLC data.
REFERENCES
1. Trofimov, B.A. and Mikhaleva, A.I., N-Vinilpirroly
(N-Vinylpyrroles), Novosibirsk: Nauka, 1984.
2. Trofimov, B.A., Geteroatomnye proizvodnye atsetilena
(Heteroatom Acetylene Derivatives), Moscow: Nauka,
1981, p. 165.
1-Vinyl-4,5,6,7-tetrahydro-1H-indole (IIa). Yield
96%, bp 112–113°C (14 mm), d420 = 1.0010, nD20
=
1.5580; published data [9]: bp 85–86°C (3 mm), d420 =
1.0010, nD20 = 1.5562.
3. Trofimov, B.A., Mikhaleva, A.I., Korostova, S.E., Bala-
banova, L.N., and Vasil’ev, A.N., Izv. Akad. Nauk SSSR,
Ser. Khim., 1976, p. 690.
1-Vinyl-4,5,6,7,8-hexahydro-1H-cyclohepta[b]-
pyrrole (IIb). Yield 97%, bp 120–121°C (14 mm),
d240 = 0.9940, n2D0 = 1.5555; published data [1]: bp 93–
94°C (1 mm), d420 = 0.9937, nD20 = 1.5560.
4. Kukharev, B.F. and Atavin, A.S., Zh. Org. Khim., 1974,
vol. 10, p. 670.
2-Phenyl-1-vinyl-1H-pyrrole (IIc). Yield 94%,
bp 93–94°C (1 mm), d420 = 1.0451, n2D0 = 1.6195;
published data [10]: bp 94°C (1 mm), d420 = 1.0443,
n2D0 = 1.6190.
5. Kukharev, B.F. and Atavin, A.S., Khim. Geterotsikl.
Soedin., 1973, p. 1580.
6. Kukharev, B.F., Stankevich, V.K., and Kukhareva, V.A.,
Khim. Geterotsikl. Soedin., 1986, p. 533.
7. Kukharev, B.F., Stankevich, V.K., and Kukhareva, V.A.,
2-Ethyl -3-methyl-1-vinyl-1H-pyrrole (IId). Yield
88%, bp 46–48°C (3 mm), d420 = 0.9161, nD20 = 1.5175;
published data [11]: bp 59–60°C (6 mm), d420 = 0.9158,
n2D0 = 1.5175.
Khim. Geterotsikl. Soedin., 1984, p. 700.
8. Kolesnikov, G.S., Sintez vinil’nykh proizvodnykh aroma-
ticheskikh i geterotsiklicheskikh soedinenii (Synthesis of
Vinyl Derivatives of Aromatic and Heterocyclic Com-
pounds), Moscow: Akad. Nauk SSSR, 1960.
3-Isopropyl-1-vinyl-1H-pyrrole (IIe). Yield 90%,
bp 95–97°C (100 mm), d420 = 0.8936, n2D0 = 1.5108. IR
spectrum, ν, cm–1: 3090, 3055 (=C–H), 1635, 1510,
9. Mikhaleva, A.I., Trofimov, B.A., and Vasil’ev, A.N.,
Khim. Geterotsikl. Soedin., 1979, p. 197.
1
1495 (C=C). H NMR spectrum, δ, ppm: 1.19 d (6H,
10. Trofimov, B.A., Korostova, S.E., Balabanova, L.N.,
Mikhaleva, A.I., and Vasil’ev, A.N., Khim. Geterotsikl.
Soedin., 1978, p. 489.
11. Mikhaleva, A.I., Trofimov, B.A., and Vasil’ev, A.N.,
Zh. Org. Khim., 1979, vol. 15, p. 602.
12. Neelakantan, L., J. Org. Chem., 1971, vol. 36, p. 2256.
3
Me, J = 5.9 Hz), 2.79 m (1H, CH), 4.60 d.d (1H,
2
3
trans-CH2=, J = 0.9, Jtrans = 15.8 Hz), 4.96 d.d (1H,
2
3
cis-CH2=, J = 0.9, Jcis = 8.9 Hz), 6.09 d (1H, 4-H,
3
3J = 2.7 Hz), 6.63 d (1H, 5-H, J = 2.7 Hz), 6.69 d.d
3
3
(1H, 1-CH, Jcis = 8.9, Jtrans = 15.8 Hz), 6.73 s (1H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 4 2011