Synthesis of 1,4,5,6-tetrachloro-7,7-dimethoxybicyclo[2.2.1]hepta-2,5- dienylmethyl esters of p-substituted benzoic acids

Article abstract of DOI:10.1134/S107042721004021X

The possibility of preparing 1,4,5,6-tetrachloro-7,7-dimethoxybicyclo[2.2. 1]hepta-2,5-dienyl-methyl esters of p-substituted benzoic acids by [4+2]cycloaddition of tetrachlorodimethoxycyclo-pentadine to propargyl esters of the corresponding acids was exam

Full text of DOI:10.1134/S107042721004021X

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 4, pp. 691−694. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © E.G. Mamedbeili, T.G. Kyazimova, S.B. Zeinalov, Kh.I. Gasanov, Z.M. Nagiev, 2010, published in Zhurnal Prikladnoi Khimii, 2010,
Vol. 83, No. 4, pp. 638−641.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Synthesis of 1,4,5,6-Tetrachloro-7,7-dimethoxy-
bicyclo[2.2.1]hepta-2,5-dienylmethyl Esters
of p-Substituted Benzoic Acids
E. G. Mamedbeili, T. G. Kyazimova, S. B. Zeinalov, Kh. I. Gasanov, and Z. M. Nagiev
Institute of Chemical Problems, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan
Institute of Petrochemical Processes, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan
Received June 24, 2009
Abstract—The possibility of preparing 1,4,5,6-tetrachloro-7,7-dimethoxybicyclo[2.2.1]hepta-2,5-dienyl-methyl
esters of p-substituted benzoic acids by [4+2]cycloaddition of tetrachlorodimethoxycyclo-pentadine to propargyl
esters of the corresponding acids was examined. The optimal synthesis conditions were found. The structure of
the compounds synthesized was confirmed by independent synthesis and by IR and 1H NMR spectroscopy.
DOI: 10.1134/S107042721004021X
[4+2]-Cycloaddition involving polychlorocyclo-
pentadienes is a convenient and promising route
to chlorine-substituted norbornene derivatives [3].
Functionally substituted polychlorinated norbornenes, in
turn, are of interest as starting compounds for preparing
new substances.
The physicochemical data for propargyl esters of
p-substituted benzoic acids IIIa–IIIg are given in
Table 1.
The final products Va–Vg were prepared by [4+2]-
cycloaddition of dimethoxytetrachlorocyclopentadiene
IV to IIIa–IIIg. The reaction follows the scheme
Proceeding with studies in the field of synthesis of
polyhalogenated bicyclic esters [4–10], we prepared in
this work 1,4,5,6-tetrachloro-7,7-dimethoxybicyclo[2.2.
1]hepta-2,5-dienylmethyl esters of p-substituted benzoic
acids. By esterification of propargyl aclohol I with
benzoic acids IIa–IIg, we synthesized the corresponding
starting dienophiles IIIa–IIIg:
Cl
Cl
OCH3
+ IIIa_IIIg
OCH3
Cl
Cl
IV
CH3O OCH3
OH
+ HOOCC6H4(n-R)
Cl
Cl
IIa_IIg
I
Cl
OC(O)C6H4(n-R)
Cl
O
C6H4(n-R)
Va_Vg
_H2O
O
IIIa_IIIg
where R = H (Va), Me (Vb), OH (Vc), MeO (Vd), Cl
(Ve), Br (Vf), NO2 (Vg).
where R = H (IIa, IIIa), Me (IIb, IIIb), OH (IIc, IIIc),
MeO (IId, IIId), Cl (IIe, IIIe), Br (IIf, IIIf), NO2 (IIg,
IIIg).
The physicochemical parameters of the compounds
synthesized are given in Table 2.
691

692
MAMEDBEILI et al.
The reaction was performed in the temperature
Under similar optimal conditions, we performed [4+2]-
cycloaddition of IV to the other propargyl esters of p-
substituted benzoic acids, IIIb–IIIg. The yields of the
adducts vary within 65–72%, with the lowest yield
observed with propargyl p-hydroxybenzoate (65%).
On introducing methoxy, chloro, bromo, and nitro
substituents into the p-position of the benzene ring, the
yield increases (to 72%).
range 80–160°С for 2–12 h at the diene : dienophile
molar ratio of 1 : 1–4 : 1. We examined the influence of
these parameters on the yield of Va–Vg. The influence
of temperature was studied with adduct Va, prepared
by condensation of IV with propargyl benzoate IIIa,
chosen as example. The yield of Va strongly depends on
temperature. At temperatures below 80°С, the reaction is
very slow. With an increase in the temperature from 80 to
140°С, the yield of Va increases from 7 to 63%. Further
increase in the temperature to 160°С led to adecrease
in the yield to 54% and to partial tarring of the reaction
mixture.
The compositions and structures of Va–Vg were
confirmed by independent synthesis. First, by the
reaction of tetrachlorodimethoxycyclopentadiene with
propargyl alcohol, following the procedure described in
[11], we prepared 2-hydroxymethyl-1,4,5,6-tetrachloro-
7,7-dimethylbicyclo[2.2.1]hepta-2,5-diene VI. By its
esterification with p-substituted benzoic acids VIIa–
VIIg, we prepared the corresponding bicyclic esters
Va–Vg (see the scheme).
With an increase in the diene : dienophile molar ratio
from 1 : 1 to 3 : 1, the yield of adduct Va increases from
50 to 63%. Further increase in the diene : dienophile
molar ratio to 4 : 1 does not noticeably affect the yield.
Table 1. Constants of esters IIIa–IIIg
Compound
Propargyl benzoate IIIa
Тb, °С (Р, mm Hg)
nD20
d420
Yield, %
85–87 (2)
88–89 (3)
1.5317
1.4970
1.5045
1.5030
1.5440
–
1.0208
0.9518
1.0357
1.0168
1.1482
–
55
62
58
60
48
60
55
Propargyl p-methylbenzoate IIIb
Propargyl p-hydroxybenzoate IIIc
Propargyl p-methoxybenzoate IIId
Propargyl p-chlorobenzoate IIIe
Propargyl p-bromobenzoate IIIf
Propargyl p-nitrobenzoate IIIg
92–94 (4)
90–91 (3)
95–96 (1)
Тm 35 (from heptane)
Тm 33 (from octane)
–
–
Table 2. Constants and analytical data for tetrachlorinated bicyclic esters of p-substituted benzoic acids Va–Vg
Found, %/Calculated, %
Compound Tb, °C (P. mm Hg)
nD20
d420
Formula
C
H
Hlg
Vа
Vb
Vc
Vd
172–173 (1)
180–181 (1)
185–187 (1)
188–190 (1)
1.5480
1.3287
47.2
48.1
3.0
3.3
34.18
33.49
C17H14Cl4O4
C18H16Cl4O4
C17H14Cl4O5
C18H16Cl4O5
1.5580
1.5530
1.5600
1.3490
1.3710
1.3830
48.3
49.3
3.08
3.65
33.70
32.40
42.4
41.8
2.60
3.18
31.64
32.27
48.4
47.5
4.10
3.52
30.08
31.27
Ve
Vf
Vg
205–207 (1)
215–216 (1)
Тm 96
1.5585
1.5760
–
1.3915
1.5260
–
43.11
44.49
2.76
2.83
37.03
38.71
C17H13Cl5O4
39.40
40.56
2.04
2.58
43.21
44.14
C17H13Cl4BrO4
C17H13Cl4O6N
44.2
43.5
2.15
2.77
31.40
30.28
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 83 No. 4 2010

SYNTHESIS OF 1,4,5,6-TETRACHLORO-7,7-DIMETHOXY-BICYCLO[2.2.1]...
693
Scheme.
Cl
Cl
OCH3
OH
+
OCH3
Cl
Cl
I
IV
CH3O OCH3
CH3O OCH3
7
Cl
Cl
Cl
Cl
4
2
5
+ HO2CC6H4(n-R)
3
6
1
Cl
Cl
8
Cl
Cl
CH2OC(O)C6H4(p-R)
CH2OH
_
g
Va Vg
VI
R = H (Va, VIIa), CH3 (Vb, VIIb), OH (Vc, VIIc), CH3O (Vd, VIId), Cl (Ve, VIIe), Br (Vf, VIIf), NO2 (Vg, VIIg).
All the physicochemical constants of compounds
Va–Vg prepared by the two procedures are identical.
gas He (40 cm3 min–1), thermal conductivity detector,
column temperature 140°C, vaporizer temperature 220°С.
TLC analysis was performed by the procedure described
in [12]. As sorbent we used Al2O3 (Brockmann grade II),
eluent heptane–acetone, visualization by irradiation with
a mercury lamp equipped with a color filter.
Thestructureandpurityofthesynthesizedcompounds
were confirmed by IR and 1H NMR spectra. The purity
of the initial and synthesized compounds was checked
by GLC and TLC.
5,5-Dimethoxytetrachlorocyclopenta-1,3-diene IV
was prepared by the procedure described in [13] from
hexachlorocyclopentadiene, bp 108–110°С (11 mm Hg),
nD20 1.5287, d240 1.5010.
In the IR spectra of compounds Va–Vg, there
are characteristics bands of the C=O group at 1725–
1740 cm–1 and ester C–O group at 1200–1050 cm–1.
The C–Cl vibrations are manifested at low frequencies,
840–750 cm–1. The C=C (C5, C6) vibration frequency
is somewhat decreased, 1600–1685 cm–1, because of
chlorine substitution. The stretching vibrations of the
nitro group in IIg and IIIg are manifested at 1390–
Propargyl esters of p-substituted benzoic acids
IIIa−IIIg were prepared according to [14]. To 0.5 mol
of p-substituted benzoic acids IIIa–IIIg, with protection
from atmospheric moisture, we added dropwise with
vigorous stirring 0.5 mol of POCl3 and then 0.8 mol of
propargyl alcohol. The mixture was stirred for 30 min,
after which it was extracted with ether. The ether
solution was washed with a 5% NaHCO3 solution to
neutral reaction and then with water, dried over MgSO4,
and distilled. The physicochemical characteristics of the
esters prepared are given in Table 1.
1
1400 cm–1. In the H NMR spectra of the adducts,
the C=C–H proton in the norbornene ring (C3) gives
a singlet at δ 6.10–6.45 ppm. Two –CH2O protons (C8)
give a triplet at δ 4.10–4.20 ppm. The protons of the
methoxy groups (OCH3 at C7) give singlets at 3.50–
3.60 ppm.
EXPERIMENTAL
1,4,5,6-Tetrachloro-7,7-dimethylbicyclo[2.2.1]-
hepta-2,5-dienylmethylbenzoateVa.Amixtureof7.92 g
(0.03 mol) of tetrachlorodimethoxycyclopentadiene IV
and 1.6 g (0.01 mol) of propargyl benzoate IIIa was
heated at 140°С for 10 h. After vacuum distillation, we
obtained 2.67 g (63%) of Va, bp 172–173°С (1 mm Hg),
nD20 1.5480, d420 1.3287. IR spectrum, ν, cm–1: 1730
(С=О), 1115 (С–О), 750 (C–Cl), 1655 (C=C). 1Н NMR
spectrum, δ, ppm: 3.5 d (6Н, OСН3), 4.2 t (2H, ОCH2),
6.45 s (1Н, С=С–Н).
The IR spectra were recorded on a UR-20 spec-
trophotometer in the range 4000–400 cm–1, and the
1Н NMR spectra, on a Tesla BS-48 spectrometer
(80 MHz) in CCl4 relative to internal reference HMDS.
Chromatographic analysis of the reaction mixture and
determination of the purity of IIIa–IIIg were performed
with an LKhM-8MD chromatograph under the follow-
ing conditions: 300 × 3-mm steel column with 5%
polyethylene glycol succinate on Dinokhrom P, carrier
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MAMEDBEILI et al.
Nauk, Ser. Khim., 2003, no. 2, pp. 279–297.
The other adducts Vb–Vg were prepared similarly.
The physicochemical data for the compounds prepared
are given in Table 2.
3. Mamedbeili (Mamedov), E.G., Klabunovskii, E.I.,
Abdiev, O.B., and Mamedova, I.M., Katal. Prom–sti.,
2008, no. 5, pp. 23–31.
2-Hydroxymethyl-1,4,5,6-tetrachloro-7,7-dimeth
oxybicyclo[2.2.1]hepta-2,5-diene VI was prepared by
the procedure described in [11]. Independent synthesis
of Va–Vg was performed by esterification of VI with
the corresponding p-substituted benzoic acids IIa–IIg
accordingto[14].Allthephysicochemicalcharacteristics
of compounds Va–Vg prepared by independent synthesis
are identical to those of the corresponding compounds
prepared by condensation of IV with propargyl esters
IIIa–IIIg.
4. Mamedov, E.G., Zh. Org. Khim., 2000, vol. 36, no. 12,
pp. 1785–1787.
5. Mamedov, E.G., Zh. Org. Khim., 2002, vol. 38, no. 1,
pp. 25–28.
6. Mamedov, E.G., Zh. Prikl. Khim., 2005, vol. 78, no. 9,
pp. 1577–1579.
7. Kyazimova, T.G., Mamedov, E.G., Babaev, R.S., and
Mamedova, I.M., Zh. Prikl. Khim., 2008, vol. 81, no. 3,
pp. 453–457.
8. Kyazimova, T.G., Mamedbeili, E.G., Nagiev, A.V., and
Suleimanova, E.I., Zh. Prikl. Khim., 2008, vol. 81, no. 10,
pp. 1679–1683.
CONCLUSIONS
9. Mamedbeili (Mamedov), E.G., Kyazimova, T.G., Nagiev,
(1) Polychlorinated bicyclic esters of p-substituted
benzoic acids were prepared by [4+2]cycloaddition
of tetrachlorodimethoxycyclopentadiene to propargyl
esters of p-substituted benzoic acids.
Z.M., et al., Zh. Org. Khim., 2009, vol. 45, no. 1, pp. 81–
84.
10. Mamedbeili (Mamedov), E.G., Kyazimova, T.G.,
Gasanov, Kh.I., et al., Zh. Prikl. Khim., 2009, vol. 82,
no. 2, pp. 288–292.
(2) Optimal synthesis conditions were found: 140°С,
10 h, diene : dienophile ratio 3 : 1; the maximal yield of
the adducts was from 63 to 72%.
11. Veliev, M.G., Ragimov, A.A., Guseinova, D.D., and
Mirzoeva, M.M., Azerb. Khim. Zh., 1980, no. 5, pp. 44–
47.
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