Synthesis of N-butoxyphenylmaleimides

Article abstract of DOI:10.1023/A:1013872506983

Reactions of equimolar amounts of o-, m-, and p-butoxyanilines with maleic anhydride give the corresponding N-butoxyphenylmaleamic acids which undergo cyclization into N-butoxyphenylmaleimides by the action of acetic anhydride in dimethylformamide in the presence of sodium acetate.

Full text of DOI:10.1023/A:1013872506983

Russian Journal of Organic Chemistry, Vol. 37, No. 11, 2001, pp. 1614 1615. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 11, 2001,
pp. 1687 1688.
Original Russian Text Copyright
2001 by Kolyamshin, Vasil’eva, Kol’tsov.
Synthesis of N-Butoxyphenylmaleimides
O. A. Kolyamshin, S. Yu. Vasil’eva, and N. I. Kol’tsov
I.N. Ul’yanov Chuvash State University, Moskovskii pr. 15, Cheboksary, 428015 Russia
Received March 29, 2001
Abstract Reactions of equimolar amounts of o-, m-, and p-butoxyanilines with maleic anhydride give the
corresponding N-butoxyphenylmaleamic acids which undergo cyclization into N-butoxyphenylmaleimides
by the action of acetic anhydride in dimethylformamide in the presence of sodium acetate.
Maleimide derivatives are promising as monomers
for preparation of heat-resistant polymeric materials
[1] and also as biologically active substances [2, 3].
However, known compounds of this series are rela-
tively few in number. Therefore, we have synthesized
new N-butoxyphenylmaleimides and studied their
properties. N-Substituted maleimides IIIa IIIc were
prepared by cyclization of maleamic acids IIa IIc
formed by reaction of equimolar amounts of butoxy-
anilines Ia Ic with maleic anhydride. The cyclization
of IIa IIc was effected by the action of acetic an-
hydride in the presence of anhydrous sodium acetate
in dimethylformamide as solvent.
spectra; maleimides IIIa and IIIc were also examined
by H NMR spectroscopy. In the IR spectra of IIIa
1
IIIc, C H stretching vibrations of the maleimide
1
CH CH moiety appeared at 3080 3085 cm , and
carbonyl absorption bands were located at 1650
1
1
1690 cm . The H NMR spectra of IIIa and IIIc
contained a singlet at 7.10 ppm from protons of the
five-membered ring; the aromatic protons of com-
pound IIIa gave a complex multiplet in the region
7.00 7.40 ppm, and those of IIIc appeared as two
doublets in the region
6.93 7.57 ppm.
N-(o-Butoxyphenyl)maleamic acid (IIa). To a so-
lution of 13.7 g (0.08 mol) of o-butoxyaniline in
12 ml of diethyl ether we slowly added with stirring
a solution of 8.14 g (0.08 mol) of maleic anhydride
in 20 ml of diethyl ether. After 2 h, the precipitate
was filtered off, washed with diethyl ether (5 5 ml),
and dried in air. Yield 17.7 g (84%), mp 101 103 C.
1
IR spectrum, , cm : 3290 (NH); 3095 (CH CH);
1670 (CO); 1590, 810 (C6H4).
Compounds IIb and IIc were synthesized in
a similar way using benzene as solvent.
N-(m-Butoxyphenyl)maleamic acid (IIb). Yield
1
90%, mp 145 147 C. IR spectrum, , cm : 3270,
3195 (NH); 3075 (CH CH); 1670 (CO); 1215
(COC); 1595, 825, 750 (C6H4).
N-(p-Butoxyphenyl)maleamic acid (IIc). Yield
1
52%, mp 169 172 C. IR spectrum, , cm : 3250
(NH); 3075 (CH CH); 1670 (CO); 1200 (COC);
1680, 1580, 810 (C6H4).
I III, ortho (a), meta (b), para (c).
N-(o-Butoxyphenyl)maleimide (IIIa). A mixture
of 17.6 g (0.067 mol) of maleamic acid IIa, 10.2 g
(0.1 mol) of acetic anhydride, 5.5 g (0.067 mol) of
sodium acetate, and 50 ml of DMF was stirred for 4 h
at 50 60 C. The mixture was cooled to 20 C and
Maleimides IIIa and IIIc are slightly yellowish
crystalline substances, and compound IIIb is a vis-
cous liquid. Their structure was confirmed by the IR
1070-4280/01/3711-1614$25.00 2001 MAIK Nauka/Interperiodica

SYNTHESIS OF N-BUTOXYPHENYLMALEIMIDES
1615
poured into 300 ml of water, and the precipitate was
ground, filtered off, washed with water (5 5 ml),
and dried in air. Yield 14.8 g (90%), mp 71 73 C.
Double recrystallization from isopropyl alcohol gave
fine yellow needles with mp 78 79 C. IR spectrum,
N-(p-Butoxyphenyl)maleimide (IIIc). Yield 92%,
mp 85 88 C. IR spectrum, , cm : 3080 (CH CH);
1
1670 (CO); 1220 (COC); 3050, 1585, 1490, 805
1
(C6H4). H NMR spectrum, , ppm: 0.85 t (3H, CH3),
1.38 sext (2H, CH2), 1.70 quint (2H, CH2), 3.98 t
(2H, CH2O), 7.10 s (2H, 2CH ), 6.93 d (2H, Harom),
7.57 d (2H, Harom).
1
, cm : 3085 (CH CH); 1660, 1650 (CO); 1210
1
(COC); 3060, 1600, 800 (C6H4). H NMR spectrum,
, ppm: 0.9 t (3H, CH3), 1.35 sext (2H, CH2), 1.60 q
(2H, CH2), 3.98 t (2H, CH2O), 7.10 s (2H, 2CH ),
7.00 7.40 m (4H, Harom).
The IR spectra were recorded on a Specord 75IR
spectrophotometer from thin films. The 1H NMR
spectra were obtained on a Bruker AM-300 instrument
(300.13 MHz) from solutions in DMSO-d6.
Compounds IIIb and IIIc were synthesized in
a similar way.
REFERENCES
N-(m-Butoxyphenyl)maleimide (IIIb). After
pouring the reaction mixture into water, an oily
material separated and was extracted into benzene.
The extract was dried over anhydrous magnesium
sulfate and evaporated to obtain 65% of product IIIb
1. Arkhipova, I.A., Zhubanov, B.A., and Rafikov, S.R.,
Usp. Khim., 1978, vol. 47, no. 4, pp. 705 738.
2. JPN Patent no. 938, 1973; Ref. Zh., Khim., 1973,
1
no. 22N528P.
as a red viscous oil. IR spectrum, , cm : 3085
(CH CH); 1690 (CO); 1200 (COC); 3050, 1570, 800,
750 (C6H4).
3. US Patent no. 5066490, 1991; Ref. Zh., Khim., 1993,
no. 60N39P.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 11 2001