Synthesis of bicyclo[2.2.1]hept-5-enyl methyl esters of haloacetic acids

Article abstract of DOI:10.1134/S1070427208100182

Synthesis of norbornenyl methyl esters of a number of haloacetic acids via [4+2] cycloaddition of cyclopentadiene to allyl esters of these acids was examined. The yield and isomer composition of the synthesized compounds were examined in relation to the reaction conditions, and the best conditions for their preparation were found.

Full text of DOI:10.1134/S1070427208100182

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 10, pp. 1803–1807. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © T.G. Kyazimova, E.G. Mamedbeili, A.V. Nagiev, E.I. Suleimanova, Kh.S. Khalilov, 2008, published in Zhurnal Prikladnoi Khimii,
2008, Vol. 81, No. 10, pp. 1679–1683 .
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Synthesis of Bicyclo[2.2.1]Hept-5-Enyl Methyl Esters
of Haloacetic Acids
T. G. Kyazimova, E. G. Mamedbeili, A. V. Nagiev, E. I. Suleimanova, and Kh. S. Khalilov
Institute of Chemical Problems, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan
Baku Institute of Petrochemical Processes, National Academy of Sciences of Azerbaijan,
Baku, Azerbaijan
Received January 22, 2008
Abstract—Synthesis of norbornenyl methyl esters of a number of haloacetic acids via [4+2] cycloaddition of
cyclopentadiene to allyl esters of these acids was examined. The yield and isomer composition of the
synthesized compounds were examined in relation to the reaction conditions, and the best conditions for their
preparation were found.
DOI: 10.1134/S1070427208100182
The structure of bicyclo[2.2.1]heptane, or norbor-
nane, is a basis of many important natural compounds
like borneal, camphor, etc. [1]. Similarly to norbornane
and adamantane moieties, the norbornene moiety is a part
of amines, many of which are medical preparations [2].
R = CH2Cl (1, 10); CHCl2 (2, 11); CCl3 (3, 12);
Significant interest in norbornene compounds
also stems from their availability increased due to im-
provement of diene synthesis techniques. In most cases,
this reaction does not involve side processes, which
makes it possible to reveal factors governing the rate,
direction, and equilibrium of the process with and
without catalysts [3].
CH2Br (4, 13); CHBr2 (5, 14); CBr3 (6, 15); CF3
(7, 16); CH3–CHCl (8, 17); CH2Cl–CH2 (9, 18).
Table 1 lists the physicochemical parameters of
the starting allyl esters (10–18).
The target products (19–27) were prepared by
[4+2] cycloaddition of CPD to allyl esters of haloace-
tic acids (10–18) by the scheme
Halogenated functionally substituted norbornenes
are good synthons for preparation of important inter-
mediate halogenated sterically hindered phenols [4–8].
These compounds are also suitable as stanting materi-
als for preparation of α-diketones and γ-lactones [9–12].
This study continues a series dedicated to synthe-
sis of halogen-containing esters of norbornene com-
pounds [13–16]. Here, we prepared bicyclo[2.2.1]-
hept-5-enylmethyl esters of a number of haloacetic acids
by the reaction of cyclopentadiene (CPD) with allyl
esters of haloacetic acids 11–19. The allyl esters 10–18
were synthesized by the well-known technique of esterifi-
cation of corresponding acids 1–9 with allyl alcohol
R = CH2Cl (19), CHCl2 (20), CCl3 (21), CH2Br (22),
CHBr2 (23), CBr3 (24), CF3 (25), CH3–CHCl (26),
CH2Cl–CH2 (27).
The reaction was carried out at temperatures
within 100–180°С in the course of 6–10 h at the diene-
to-dienophile molar ratio of 1 : (1–4).
1803

1804
KYAZIMOVA et al.
Table 1. Constants of allyl esters of haloacetic acids 10–18
Ester
bp, °C (P, mm Hg)
Compound
nD20
dD20
Yield, %
85
Allyl monochloroacetate
Allyl dichloroacetate
43–44 (5)
63–64 (10)
68–69 (10)
1.4460
1.1469
10
1.4544
1.4632
1.4729
1.4704
1.5470
1.3364
1.4468
1.4385
1.3496
1.4648
1.4329
1.4500
2.0061
1.1765
1.0868
1.0806
70
75
65
60
45
60
75
80
11
12
13
14
15
16
17
18
Allyl trichloroacetate
Allyl monobromoacetate
Allyl dibromoacetate
Allyl tribromoacetate
Allyl trifluoroacetate
Allyl α-chloropropionate
Allyl β-chloropropionate
73 (10)
66–67 (10)
80–82 (1)
78–79
81–82 (40)
80–81 (40)
Table 2. Properties of bicyclo[2.2.1]hept-5-enyl methyl esters of haloacetic acids 19–27
Found, %
Calculated, %
Com-
pound (P, mm Hg)
bp, °C
nD20
dD20
Formula
C
H
halogen
17.43
C
H
halogen
91 (1)
1.4930 1.1723
1.5004 1.2492
59.67
6.24
С10Н13O2Cl
C10H12O2Cl2
C10H11O2Cl3
C10H13O2Br
C10H12O2Br2
C10H11O2Br3
C10H11O2F3
C11H15O2Cl
C11H15O2Cl
59.95
6.48
17.71
30.21
39.52
32.65
49.07
59.55
25.91
16.55
16.55
19
20
21
22
23
24
25
26
27
111 (2)
50.92
44.14
48.65
36.23
29.53
54.17
61.05
61.14
5.02
3.88
5.15
3.63
2.52
4.86
6.52
6.73
29.86
39.08
32.24
49.51
59.12
25.68
14.26
14.7
51.06
44.53
48.98
37.03
29.77
54.55
61.54
61.54
5.11
4.08
5.31
3.07
2.72
5.10
6.99
6.99
107–108 (1) 1.5029 1.3243
87–89 (1) 1.5077 1.3443
107–108 (2) 1.5105 1.5871
125–128 (3) 1.5531 1.8910
61–62 (10) 1.4205 1.2249
90–91 (1)
89–90 (1)
1.4821 1.2575
1.4852 1.2614
Table 2 lists the physicochemical characteristics
of the compounds synthesized.
The best conditions for formation of adduct 19 are
as follows: temperature 140°С, reaction time 6 h, and
diene : dienophile ratio 1:1.5. With increasing tempera-
ture, the endo selectivity of the reaction of synthesis of
adduct 19 decreases from 85 to 61%, which can be as-
sociated with conversion of the endo isomer to a thermo-
dynamically more advantageous exo isomer at a high
temperature.
The yield and isomer composition of adducts
19–27 were examined in relation to various reaction
parameters (temperature, time, addend ratio). The re-
sults are presented in Table 3.
It is seen from Table 3 that, as the temperature
increases from 100 to 160°С, the yield of adduct 19
grows from 7.4 to 56.65%. Further increase in tem-
perature (to 180°С) causes a decrease in the yield. A pos-
sible reason is formation of a bis-adduct based on com-
pound 19.
Under similar optimal conditions, we carried out
diene condensation of CPD with other allyl esters of
haloacetic acids. The yield of the adducts varied within
50.92–87.6%; the highest yield was observed for allyl tri-
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SYNTHESIS OF BICYCLO[2.2.1]HEPT-5-ENYL METHYL ESTERS OF HALOACETIC ACIDS
1805
Table 3. Yield and isomer composition of esters 19–27 in relation to the conditions of the reactions of CPD with allyl esters
of haloacetic acids 10–18
Isomer ratio, %
Tempera-
ture
Diene : dienophile
molar ratio
Dienophile
Time, h
Yield of 19–27
endo
95
85
79
71
61
80
82
81.5
82
78
78
83
85
83
85
87
82
78
78
exo
5
100
120
140
160
180
140
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1
6
6
7.14
19.17
55.35
56.65
52.21
51.41
55.75
56.11
56.91
55.89
56.35
50.92
44.14
48.55
39.23
29.67
87.6
10
10
10
10
10
10
10
10
10
10
10
11
12
13
14
15
16
17
18
15
21
29
39
20
18
18.5
18
22
22
17
15
16
15
13
18
22
22
6
6
6
6
1 : 2
6
1 : 3
6
1 : 4
6
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
1 : 1.5
6
10
6
6
6
6
6
6
6
61.05
61.14
6
All the physicochemical data obtained by both
techniques for compounds 19–27 are identical.
fluoroacetate 16 (87.6%), and the lowest, for allyl ester
of tribromoacetic acid 15 (29.63%).
Comparative examination showed that the highest
endo selectivity was observed in the reaction of CPD
with allyl ester of tribromoacetic acid 15 (87%).
The composition and structure of adducts 19–27
were confirmed by IR and Н NMR spectra. The IR
1
spectra of the bicyclic esters synthesized contain charac-
teristic signals of the С=О-group at 1730–1750 cm–1
and of the C–O ester group at 1000–1275 cm–1.
The bands of the carbon–chlorine bond are observed
for chlorine-containing compounds in low-frequency
spectral regions: 750, 760, 780, 760, and 770 cm–1
for compounds 19–21, 7, and 27, respectively. The IR
spectra of bromine-containing esters 22–24 contain
intense bands associated with C–Br vibrations at
650–600 cm–1. The νC–F band of ester 25 is ob-
served near 1050 cm–1. The absorption bands of the eth-
ylene moiety in the norbornene ring lie at 1570–
1555 and 3060–3045 cm–1 (νC=C, νC–H).
The composition and structure of the synthesized
compounds 19–27 were proven by counter synthesis.
First, by the technique described in [17] we carried out
condensation of CPD with allyl alcohol into 2-hy-
droxymethylbicyclo[2.2.1]hept-5-ene 28 whose esteri-
fication with haloacetic acids by the well-known tech-
nique yielded the corresponding esters 19–27:
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KYAZIMOVA et al.
1
The Н NMR spectra of esters 19–27 contain sig- mixture was washed with water, dried over MgSO4,
nals from protons of the double bond in the norbornene
ring (Н5, Н6), manifested at 6–6.25 ppm as a multiplet,
and are characterized by spin-spin coupling constants
J5,6 of 7.0 Hz. The Н3 (2Н) protons give multiplet
signals at high fields with a chemical shift δ of 0.7–
1.2 ppm. The multiplet associated with the Н2 pro-
ton is observed at δ of 2.5 ppm and is characterized by
the constant of spin-spin coupling with the Н3 proton,
J2,3 of 9.6 Hz. The Н1 and Н4 protons are chemically
equivalent and give multiplet signals at δ of 2.70–2.85
ppm. The methylene protons Н8 (СН2О group) give
multiplet signals at δ of 4.15–3.95 ppm:
and distilled.
Bicyclo[2.2.1]hept-5-enyl methyl monochloro-
acetate 19. A mixture of 14.17 g (0.15 mole) of allyl
monochloroacetate 10 and 6.6 g (0.1 mole) of freshly
distilled CPD in the presence of hydroquinone was
heated at 140°С for 6 h in a sealed ampule. Vacuum
distillation yielded 12.69 g (55.25%) of adduct 19,
bp 95°С (1 mm Hg), nD 1.4930, dD 1.1723. IR spec-
trum, ν, cm–1: 1735 (С=О), 1100 (C–O), 750 (C–Cl),
1755 (С=С). Elemental analysis:
20
20
Found, %: C 59.67; Н 6.24; Cl 17.43.
Calculated, %: C 59.95; Н 6.48; Cl 17.71.
2-Hydroxymethylbicyclo[2.2.1]hept-5-ene 28 was
prepared by condensation of CPD with allyl alcohol by
the technique described in [17]. A counter synthesis of
esters 19–27 was carried out by esterficiation of bi-
cyclic alcohol 28 with corresponding carboxylic acids
1–9 by the known technique. All the physicochemical
characteristics of esters 19–27 prepared by counter
synthesis are identical to the data of the same com-
pounds obtained by condensation of CPD with esters
10–18.
CONCLUSION
Norbornenyl methyl esters of a number of
haloacetic acids were synthesized by [4+2] cycloaddi-
tion of cyclopentadiene to allyl esters of these acids.
With increasing temperature, the total yield of the ad-
ducts tends to grow, and the stereoselectivity, to de-
crease. The best conditions for preparation of the com-
pounds synthesized were found.
The isomer composition of esters 19–27 was
determined by gas–liquid chromatography.
EXPERIMENTAL
The IR spectra were recorded on a UR-20 spectro-
photometer at 4000–400 cm–1 for thin films or KBr
1
pellets. The Н NMR spectra were measured on a BS-
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