Addition of bromotrichloromethane and tetrachloromethane to cis-cyclooctene, cyclohexene, and norbornadiene in the presence of palladium(II) complexes

Article abstract of DOI:10.1023/B:RUJO.0000003181.02370.cf

Addition of bromotrichloromethane and tetrachloromethane to alkenes in the presence of palladium(II) complexes begins with single-electron transfer from the palladium atom to polyhalomethane molecule, followed by fragmentation of the radical anion thus formed and generation of trichloromethyl radical. Halogen transfer to a carbon-centered radical arising from addition of trichloromethyl radical at the double bond occurs both from the polyhalomethane molecule and from halide palladium complex.

Full text of DOI:10.1023/B:RUJO.0000003181.02370.cf

Russian Journal of Organic Chemistry, Vol. 39, No. 7, 2003, pp. 933 946. Translated from Zhurnal Organicheskoi Khimii, Vol. 39, No. 7, 2003,
pp. 994 1007.
Original Russian Text Copyright
2003 by Dneprovskii, Ermoshkin, Kasatochkin, Boyarskii.
Addition of Bromotrichloromethane and Tetrachloromethane
to cis-Cyclooctene, Cyclohexene, and Norbornadiene
in the Presence of Palladium(II) Complexes
A. S. Dneprovskii , A. A. Ermoshkin, A. N. Kasatochkin, and V. P. Boyarskii
St. Petersburg State University, Universitetskii pr. 26, St. Petersburg, 198504 Russia
Received September 11, 2002
Abstract Addition of bromotrichloromethane and tetrachloromethane to alkenes in the presence of palla-
dium(II) complexes begins with single-electron transfer from the palladium atom to polyhalomethane mole-
cule, followed by fragmentation of the radical anion thus formed and generation of trichloromethyl radical.
Halogen transfer to a carbon-centered radical arising from addition of trichloromethyl radical at the double
bond occurs both from the polyhalomethane molecule and from halide palladium complex.
Incorporation of unsaturated compounds into coor-
dination sphere of a transition metal provides one
of the most promising ways of controlling their reac-
tivity. Nucleophilic and electrophilic reactions of
coordinated alkenes and alkynes are extensively
studied; however, there are almost no published data
on participation of coordinated alkenes in radical
reactions. In a few publications it was noted that
copper [1 3], iron [1], ruthenium [4, 5], and some
other transition metal complexes effectively initiate
radical addition of polyhalomethanes. According to
the authors, the role of ruthenium complex is not
limited to generation of trichloromethyl radical, but
it also participates in the stage of halogen transfer
to carbon-centered radical which is formed as a result
of radical addition. This leads to a considerable
increase in the yield of 1-chloro-2-trichloromethyl-
cyclohexane and stereoselectivity of the process per-
formed in the presence of a catalytic amounts of
Ru(II) complex (trans cis isomer ratio 96:4), as
compared to the reaction in the presence of benzoyl
peroxide (trans cis isomer ratio 53:47) [4]. It should
be emphasized that in most cases the authors’ atten-
tion was given to the initiation stage, while problems
concerning possible participation in the process of
coordinated alkenes and effect of transition metal
complexes on the nature of elementary stage and
mechanism of the chain process were not raised.
chloromethane to a series of cycloalkenes with those
obtained for analogous reactions in the presence of
Pd(II) complexes and stoichiometric reactions of
Pd(II) complexes with the same olefins and reagents.
Our choice was dictated by the fact that palladium
gives stable individual complexes with most alkenes
and alkadienes. On the other hand, radical reactions
in the presence of palladium complexes have been
studied very poorly. Tsuji et al. [6 9] studied addition
of polyhalogenated compounds to alkenes in the pres-
ence of Pd(II) complexes and reducing agents; the
authors concluded that Pd(0) compounds formed by
reduction of the initial complexes initiate radical
chain process.
As substrates we used cis-cyclooctene (I), cyclo-
hexene (II), and norbornadiene (III), and the reagents
were bromotrichloromethane and tetrachloromethane.
Radical reactions were initiated by benzoyl peroxide
or azobis(isobutyronitrile); also, photochemical initia-
tion was applied. The addition of bromotrichloro-
methane to cis-cyclooctene (I) gives compounds
IV VIII (Scheme 1). The reaction mixtures were
analyzed by GLC and NMR spectroscopy; the prod-
ucts were identified by comparing their retention
parameters (obtained in two columns with stationary
phases of different polarities) with those of authentic
samples and by the presence of characteristic signals
in the NMR spectra. The structure of compounds
IV VIII prepared by independent methods was con-
We compared the results of studying the classical
radical addition of bromotrichloromethane and tetra-
1
____________
firmed by H NMR spectroscopy. The reaction condi-
Deceased.
tions and product ratios are given in Table 1.
1070-4280/03/3907-0933$25.00 2003 MAIK Nauka/Interperiodica

934
DNEPROVSKII et al.
Scheme 1.
Products IV and VI are formed by normal radical
obtained in the presence of Pd(II) complex (Table 1).
As follows from the data in Table 1, the yield of
products IV/V almost does not depend on the con-
centration of palladium complex; it increases with
reaction time. By special experiments we showed
that under similar conditions but in the absence of
an initiator, the substrate conversion does not exceed
4%. The overall yield of products IV VII reaches
50 mol per mole of the transition metal complex,
which suggests chain character of the process.
addition at the double bond. The formation of 1,4-ad-
ducts V and VII may be explained by 1,5-transan-
nular hydrogen shift in the initially formed radical A
and its transformation into radical B (Scheme 1).
A large amount of compound VIII obtained under
standard conditions of radical initiation results from
allylic bromination whose mechanism is shown in
Scheme 2 [10, 12].
Scheme 2.
The reaction in the presence of Pd(II) complex also
gives products VI and VII in an amount of 1 2 mol %
relative to the overall yield of IV and V. The ratio
VI:VII in the reaction mixture varies within the range
8 11, regardless of the Pd(L1)Cl2 concentration (L1 is
cis-cyclooctene as ligand). The latter factor only
slightly affects the product ratio VI+VII/IV+V
which changes from 0.01 to 0.025. Compounds IV
and V remain unchanged on heating in BrCCl3 (97 C,
7 h) in the presence of 1 equiv of PdCl2. According
1
to the H NMR data, the cis trans ratio in product IV
is 1:1, and it does not change in going from the
reaction initiated by benzoyl peroxide to the reaction
in the presence of Pd(L1)Cl2.
The addition of bromotrichloromethane to cyclo-
hexene (II) leads to formation of products IX XIV
(Scheme 3). The products were identified by GLC
using two columns with stationary phases of different
polarities; their retention parameters coincided with
those of authentic samples prepared by independent
When the reaction was performed in the presence
of dimethylglyoxime cobalt complexes (which effec-
tively trap bromine atom), compound VIII was
formed in a small amount; analogous results were
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

ADDITION OF BROMOTRICHLOROMETHANE AND TETRACHLOROMETHANE
935
Table 1. Product composition in the addition of polyhalomethanes to cis-cyclooctene (I) (in percent relative to the initial
amount of I)a
Initiator, mol per mole
Temperature, Reaction
Reagent
BrCCl3
IV
V
VI
VII
VIII
of I
C
time, h
Pd(L1)Cl2, 0.035b
(C6H5COO)2, 0.04
Pd(L1)Cl2, 0.012b
Pd(L1)Cl2, 0.023b
Pd(L1)Cl2, 0.035b
Pd(L1)Cl2, 0.07b
Pd(L1)Cl2, 0.112b
No initiator
80
80
80
80
80
80
80
80
80
70
2
3
3
3
3
3
3
9
38.6
64.1
54.2
54.1
55.7
55.4
49.5
3.61
80
71.3
3.3
6.1
5.7
4.9
4.8
4.6
4.5
0.38
8
0.5
0
0.045
0
0.7
11.5
1.1
1.1
1.1
1.1
1
0.2
0.8
0.80
0.83
0.46
0.75
0.53
1.15
0
0.075
0.076
0.094
0.075
0.14
0
Pd(L1)Cl2, 0.035b
PhCH2
9
0.33
1.03
0
0.11
0
6.7
Co(dmgH)2(PPh3), 0.04c
p-ClC6H4CH2
80
2.1
79.5
8.7
0
0
1
Co(dmgH)2(Py), 0.02c
UV irradiation
UV irradiationd
PdBr2, 0.03
20
20
80
97
97
97
0.5
4
14
4
20
20
18.5
44
2.42
0
0.56
1.84
1.27
1.5
10.5
0
4.28
7.99
0
0
0.95
0.64
3.37
5.55
0
0
8.47
21
0
0
0
CCl4
10.05
79.4
40.6
50.5
(C6H5COO)2, 0.02
PdBr2, 0.02
PdBr2, 0.03
0
a
Conversion of I 5 95%; the material balance precision was no less than 90%; the yields were determined by GLC using biphenyl
as internal standard and by H NMR spectroscopy, the relative error being no larger than 7%; [I] = 0.57 M, excess polyhalomethane
1
was used as solvent, [BrCCl3] = 9.4 M, [CCl4] = 9.6 M.
b
c
d
L1 is cis-cyclooctene as ligand.
dmgH is dimethylglyoxyme monoanion.
Data of [10]; preparative yields are given.
methods. The 1H NMR data also confirmed their
structure. The reaction conditions and product ratios
are given in Table 2. The addition of bromotrichloro-
methane to cyclohexene (II) in the presence of
a chemical initiator or under UV irradiation [13]
afforded a mixture of compounds IX, X, and XIII.
Our results showed that the addition of CBrCl3 to
cyclohexene in the dark, initiated by a catalytic
amount of Pd(L1)Cl2 yields products IX and X at the
same ratio. Furthermore, compounds XI, XII, and
XIV are also formed in the Pd-catalyzed reaction.
The ratio IX:X does not depend on the palladium
concentration, but it increases on raising the tempera-
ture: from 1.1 at 20 C to 1.5 at 80 C. The overall
yield of products IX and X increases as the concentra-
tion of the palladium complex rises (Table 2).
Scheme 3.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

936
DNEPROVSKII et al.
Table 2. Product composition in the addition of polyhalomethanes to cyclohexene (II) (in percent relative to the initial
amount of II)a
Initiator, mol
per mole of II
Tempera- Reaction
Reagent
BrCCl3
IX
X
XI
XII
XIII
XIV
ture,
C
time, h
Pd(L1)Cl2, 0.044b
Pd(L1)Cl2 0.044b
No initiator
20
5
0.31
1.15
2.97
12.67
19.4
1.66
2.99
6.02
8.85
17.6
0.28
0.87
2.02
8.33
0
0
0
0
3.0
11.2
19.0
0
0
0
0
12.1
<0.2
0.74
0
0
0
0.8
2.12
3.85
4.78
0
50
80
80
80
80
80
80
80
80
3
3
0.67
1.42
3
3
3
3
2.1
0.0085 0.0035
0
0
0
<0.001
0.023
0.067
0.14
0
0
0
0
C8H12N4, 0.014c
(C6H5COO)2, 0.013
Pd(L1)Cl2, 0.0088b
Pd(L1)Cl2, 0.027b
Pd(L1)Cl2, 0.044b
Pd(L1)Cl2, 0.062b
p-ClC6H4CH2
12.9
1.16
2.02
3.98
6.15
0.0028
0.0066
0.023
0.042
0
11.3
Co(dmgH)2(Py), 0.02d
UV irradiation
20
20
97
97
97
97
97
97
97
97
97
97
2
4
14.5
5
14.5
14.5
14.5
11.57
5
11.57
11.57
27
13.62
28.4
0
0
0
1.22
2.93
0
10.90
23.2
0
0
0
0
13.76
24.1
0
0
0
0
0
0
0
0
0
1.3
UV irradiatione
No initiatorf
CCl4
0
0
0
0.94
2.22
2.09
0.96
1.24
0.72
3.50
3.02
4.64
0.39
0.99
2.60
1.81
0.91
1.08
0.53
2.72
1.35
1.83
0.30
(C6H5COO)2, 0.02f
Pd(L1)Cl2, 0.04b, f
PdBr2, 0.02f
1.60
1.21
1.3
1.19
0.89
2.41
2.57
3.34
0.5
0.49
1.18
PdBr2, 0.04f
No initiator
0
0
0
0
(C6H5COO)2, 0.02
Pd(L1)Cl2, 0.02b
Pd(L1)Cl2, 0.04b
PdBr2, 0.02
0
0
0
0
0
0
0.048
0.042
a
Conversion of II 0.5 40%; the material balance precision was no less than 90%; the yields were determined by GLC using biphenyl
as internal standard and by H NMR spectroscopy, the relative error being no larger than 7%; [II] = 0.73 M, excess polyhalo-
1
methane was used as solvent, [BrCCl3] = 9.4 M, [CCl4] = 9.6 M.
b
L1 is cis-cyclooctene as ligand.
c
Azobis(isobutyronitrile).
d
dmgH is dimethylglyoxyme monoanion.
Data of [13]; preparative yields are given.
Solvent CH3CN, [CCl4] = 4.8 M.
e
f
The ratio of the Cl CCl3 and Br CCl3 adducts
BrCCl3), as well as under UV irradiation or in the
presence of benzoyl peroxide, is accompanied by
allylic bromination. 3-Bromocyclohexene (XIII) is
formed in up to 60% yield (relative to the overall
yield of adducts IX and X). On the other hand, when
(dimethylglyoximato)cobalt is used as initiator, the
amount of the allylic bromination product decreases
to 40% (with respect to IX+X; Table 2). In the addi-
tion of BrCCl3 to cis-cyclooctene (I), the yield of
bromide VIII (relative to the overall yield of IV
and V) under typical conditions of radical initiation
is 40% (UV irradiation) or 16% (benzoyl peroxide),
while in the presence of (dimethylglyoximato)cobalt
it decreases to 1% (Table 1). As noted above, cobalt
complexes eliminate chains involving bromine atom
(XI+XII/IX+X) increases from 0.001 to 0.012 as
the concentration of Pd(L1)Cl2 rises from 0.0064 M
to 0.045 M. Compounds XI and XII could be formed
by both halogen transfer from the palladium complex
and as a result of a secondary process, halogen ex-
change in IX and X by the action of Pd(L1)Cl2.
We have found that under the given conditions com-
pounds IX and X are capable of being converted into
XI and XII in the presence of an equimolar amount of
Pd(L1)Cl2. After 3 h at 80 C, the fraction of XI+XII
reaches 4 6% of the overall amount of IX+X.
As with cis-cyclooctene (I), the addition of BrCCl3
to cyclohexene (II) in the absence of chemical or
photochemical initiation (due to thermolysis of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

ADDITION OF BROMOTRICHLOROMETHANE AND TETRACHLOROMETHANE
Br ; therefore, a mechanism analogous to that shown Scheme 4.
937
in Scheme 2 cannot be proposed to explain the forma-
tion of product XIII.
The data in Tables 1 and 2 indicate that cyclo-
hexene (II) is considerably less reactive than com-
pound I in the addition of CCl3 at the double bond.
We determined the relative rate constant for the addi-
tion of trichloromethyl radical, kI/II = 6.70 (80 C), by
extrapolation of its dependence on the substrate
conversion to the zero conversion in the competing
addition of BrCCl3 to cycloalkenes I and II:
The addition of BrCCl3 to cyclohexene in the pres-
ence of Pd(L1)Cl2 is accompanied by formation of
3-chlorocyclohexene (XIV) in 30 40% yield (relative
to the overall yield of adducts IX and X); in this
case, no compound XIII was detected in the reaction
mixture (Table 2). Product XIV can be formed along
three different paths:
(1) Chloropalladation of cyclohexene (II, L2) in
the presence of trace amounts of chloride ion or
insertion of II into the Pd Cl bond in the complex
Pd(L2)Cl2, followed by -elimination of hydrogen
from position 3 of the resulting 2-chlorocyclohexyl-
palladium chloride (which leads to formation of XIV,
Pd(0), and HCl [18]), seems to be the least probable.
The amount of product XIV decreases from 42 to
32% (relative to the overall yield of IX and X) as
the concentration of Pd(II) complex in the reaction
mixture rises from 0.027 to 0.044 mol per mole of
cyclohexene (Table 2);
[IV] + [V] [II]
kI/II
=
.
[IX] + [X] [I]
Here, [II] and [I] are the initial concentrations of
cycloalkenes II and I, respectively, which were equal
to 0.68 and 0.53 M; excess BrCCl3 was used as sol-
vent, [BrCCl3] = 8.76 M, and benzoyl peroxide
(2 mol %), as initiator; the conversion of cyclohexene
ranged from 2 to 14%.
The absolute rate constant for the addition of tri-
chloromethyl radical at the double bond of cyclo-
hexene at 80 C, calculated from the data of [14], is
577 l mol 1 s . The absolute rate constant for hydro-
1
gen abstraction by trichloromethyl radical from the
allylic position of cyclohexene was estimated at
312 l mol 1 s (calculated from the relative rate con-
1
stant for hydrogen abstraction by CCl3 from cyclo-
hexene with respect to toluene [15] and the absolute
rate constant for hydrogen abstraction by trichloro-
(2) Chlorine atom transfer from Pd(II) complex to
radical E will be discussed in detail below;
methyl radical from toluene [16]), 103 l mol 1 s
1
(calculated from the relative rate constant for hydro-
gen abstraction from cyclohexene with respect to
recombination of CCl3 radicals and the absolute rate
constant for recombination of CCl3 radicals [16]), and
(3) Halogen exchange (replacement of bromine by
chlorine) in the initially formed compound XIII in
the presence of Pd(L1)Cl2 is quite probable. We have
shown that heating of adduct XIII in BrCCl3 as
solvent in the presence of Pd(L1)Cl2 (80 C, 3 h) leads
to formation of compound XIV in an amount compar-
able with the amount of Pd(L1)Cl2.
1
4960 l mol 1 s (calculated for a temperature of
80 C [17]). Thus the absolute rate constants for
hydrogen abstraction by trichloromethyl radical from
the allylic position of cyclohexene and for CCl3 addi-
tion at the double bond are comparable.
The addition of BrCCl3 to norbornadiene (III)
(Scheme 5, X = Br), both under typical conditions of
radical initiation [19 21] and in the presence of Pd(II)
complexes, results mainly in formation of a mixture
of three products, XVa, XVIIa, and XVIIIa [20].
The reaction mixtures were analyzed by GLC and
NMR spectroscopy, and the products were identified
as in the above cases. The strucure and steric con-
figuration of compounds XVa, XVIIa, and XVIIIa
obtained by independent methods were established by
Taking the above into account, a mechanism of
formation of compound XIII can be proposed
(Scheme 4), which explains different effects of cobalt
complexes on the allylic bromination of cycloalkenes
I and II: The contribution of the reaction shown in
Scheme 4 (relative to the addition at the double bond)
for cis-cyclooctene is considerably smaller than for
cyclohexene (in the first approximation, the difference
in the reactivities of allylic C H bonds of cis-cyclo-
octene and cyclohexene can be neglected).
1
1H and 13C NMR spectroscopy, including H NMR
correlation techniques (COSY, NOESY). In the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

938
DNEPROVSKII et al.
Scheme 5.
X = Br (a), Cl (b).
NOESY spectrum we observed cross peaks corre-
sponding to 7 -H/5-H and 7 -H/5-H; on the basis of
these data, the major unrearranged product of BrCCl3
addition to diene III was assigned structure XVa
with endo-oriented bromine atom. Presumably, the
second unrearranged product (compound XVIa) is
also formed in the reaction mixture in an amount not
exceeding 10% of the amount of XVa (according to
the GLC and 1H NMR data). In the 1H NMR spectrum
of XVa obtained by radical addition of BrCCl3 to
diene III, a set of signals assignable to XVIa was
observed.
reaction mixture no longer changed. At low tempera-
tures, a catalytic system analogous to that proposed
in [6 9] [we used PdCl2 instead of Pd(OAc)2], turned
out to be inefficient. More than 2 days was necessary
to obtain an appreciable yield (Table 3, run no. 9).
Zero-valence palladium compounds (Table 3; run
nos. 10, 11, 16, 17, and 21) are also capable of initiat-
ing the radical addition process, but their activity at
20 C was lower than the activity of the Pd(II) DMSO
systems. The complex Pd(DMSO)2Cl2 effectively
catalyzes the addition at 20 C. Complexes like
Pd(DMSO)2Cl2 are readily obtained by dissolution of
PdX2 in DMSO [22]. According to [23], diene ligands
in Pd(diene)X2 complexes undergo fast exchange with
DMSO. The 1H NMR spectrum of Pd(L3)Cl2 in
DMSO-d6 is consistent with these data: the observed
proton chemical shifts coincide with those of free
diene III. Therefore, in the reaction performed in
DMSO, the presence of free diene III (Table 3, run
nos. 4, 7, and 14) and the complex Pd(DMSO)2X2 in
the system may be assumed (Table 3, run nos. 2 7
and 14). The catalytic system based on Pd(II) salt,
triphenylphosphine, and potassium carbonate is effec-
tive up to 66 80 C (Table 3, run nos. 15 and 20).
By special experiments we showed that the contribu-
tion of processes occurring under these conditions
(66 C, 20 35 min; 80 C, 1 h) in the absence of Pd(II)
with participation of CBrCl3, PPh3, or K2CO3 (or
various their combinations) and leading to CBrCl3
addition products is small. The overall yield of com-
pounds XVa, XVIIa, and XVIIIa in the presence of
triphenylphosphine and potassium carbonate (diene
III:PPh3 :K2CO3 ratio 1:0.02:1) did not exceed 12%
in 1 h at 80 C.
The steric structure of adducts XVIIa and XVIIIa
1
was also determined by H NOESY technique. The
NOESY spectrum of XVIIa showed coupling between
3-H and 5-H, whereas no coupling was observed
between 7 -H and 5-H and between 7 -H and 3-H.
The NOESY spectrum of XVIIIa contained a cross
peak from 7 -H and 5-H, while neither 3-H/5-H nor
7 -H/3-H coupling was detected.
The addition of BrCCl3 to the complexes Pd(L3)Cl2
and Pd(L3)Br2 which contain norbornadiene as ligand
(L3) resulted in formation of the same main products,
XVa, XVIIa, and XVIIIa.
We examined the reaction of CBrCl3 with nor-
bornadiene under initiation in different ways and
determined the activity of Pd(II) complexes in the
addition of CBrCl3 to diene III and to Pd(L3)Cl2 and
Pd(L3)Br2 (Table 3). The reactions occurring in
DMSO in the presence of Pd(II) complexes are
characterized by a high rate. The product yields given
in Table 3 (run nos. 2 8 and 14) were attained in less
than 5 min even at 20 C. The composition of the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

ADDITION OF BROMOTRICHLOROMETHANE AND TETRACHLOROMETHANE
939
Table 3. Product composition in the addition of BrCCl3 to norbornadiene (III) (in percent with respect to the initial
amount of diene III), initiated in different waysa
Run
no.
Temperature,
C
Initiator, mol
per mole of III
Solvent
[III], M
XVa
XVIIa
XVIIIa
1
1a
2
3
4
5
6
7
8
20
UV irradiation, 5 min
UV irradiation, 30 min
PdCl2, 0.03
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
Benzene
DMSO
DMSO
DMSO
DMSO
Benzene
DMSO
Benzene
Benzene
Benzene
Benzene
Benzene
Benzene
Benzene
0.2
0.2
3.4
0.2
0.2
3.4
0.63
0.2
0.2
3.4
3.4
0.2
0.2
0.2
3.4
0.2
3.4
3.4
3.4
2.5
2.5
2.5
2.5
1.24
14.9
1.01
11.8
12.4
0.8
16.9
11.5
13.1
1.9
2.21
26.5
1.91
22.6
22.1
1.4
29.4
22.6
28.1
3.5
1.55
18.6
1.07
15.6
15.5
0.8
18.8
15.8
18.8
1.6
PdCl2, 0.50
Pd(L3)Cl2,b 1.00
Pd(L3)Cl2, 0.03
Pd(L3)Cl2, 0.28
Pd(L3)Br2, 1.00b
Pd(OAc)2, 0.50
9
PdCl2/PPh3/K2CO3,c, d 0.01
Pd(PPh3)4, 0.03
10
10a
11
12
13
14
15
16
17
18
19
20
21
1.2
2.4
1.4
Pd(PPh3)4, 0.50
0.07
0.11
5.5
0.74
4.1
5.5
0.9
1.2
0.2
0.14
0.24
32.1
3.29
27
22.4
2.6
4.8
1.2
56
55.8
20.1
0.08
0.15
22.5
1.97
18.9
12.1
1.6
2.6
0.7
29.7
30.7
10.8
Pd (metal), 0.13
C8H12N4,f 0.01 0.05
(C6H5COO)2, 0.01 0.05
PdCl2, 1.00b
66e
PdCl2/PPh3/K2CO3,c 0.01
Pd(PPh3)4, 0.01
Pd (metal), 0.01
No initiator
(C6H5COO)2, 0.01
PdCl2/PPh3/K2CO3,c 0.01
Pd (metal), 0.01
80g
4.3
3.5
3.1
a
Conversion of III 0.3 100%; the material balance precision was no less than 90%; the yields were determined by GLC using
biphenyl as internal standard, the relative error being no larger than 7%; [BrCCl3] = 3.5 M.
Diene III (L3) was introduced as Pd(L3)X2.
Conditions proposed by Tsuji et al. [6 9]: III:PdCl2 :PPh3 :K2CO3 = 1:0.01:0.02:1.
Reaction time 53 h.
Reaction time 35 min.
Azobis(isobutyronitrile).
b
c
d
e
f
g
[BrCCl3] = 2.5 M; reaction time 1 h.
The ratio of adducts XVa/(XVIIa + XVIIIa) is
gives rise to compounds XVb, XVIIb, and XVIIIb
(Scheme 5). We have found that Pd(II) compounds are
also capable of promoting addition of CCl4 at the
double bond of the the above alkenes to give the same
adducts. The reaction mixtures were analyzed by GLC
and NMR spectroscopy. The products were identified
in the same way as in the addition of BrCCl3, using
authentic samples prepared by independent methods.
The addition of carbon tetrachloride to diene III
under initiation by UV light or azobis(isobutyronitrile)
yields mainly nortricyclane derivatives XVIIb and
XVIIIb. The amount of unrearranged adduct XVb is
only 3% of the overall yield of compounds XVIIb
and XVIIIb; this may be due to reduction of the rate
of halogen transfer from polyhalomethane to alkyl
equal to 0.33 at 20 C, 0.1 at 66 C, and 0.05 at 80 C
(Table 3). It remains the same in going from the con-
ditions of typical radical initiation to initiation by
Pd(II) derivatives, as well as in the reaction of CBrCl3
with Pd(L3)Cl2 or Pd(L3)Br2. As shown in [21],
the ratio of bicyclic (XVa) and tricyclic adducts
(XVIIa+XVIIIa) depends on the temperature and
concentration of bromotrichloromethane, which is
consistent with our data.
The addition of CCl4 to cis-cyclooctene (I) in the
presence of radical initiator gives products VI and VII
(Scheme 1, Table 1); adducts XI, XII, and XIV are
formed from cyclohexene (II) under similar condi-
tions (Scheme 3, Table 2); and norbornadiene (III)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

940
DNEPROVSKII et al.
radical in going from CBrCl3 to CCl4 [21]. Products
XVIIb and XVIIIb are formed at a ratio of 59:41;
the same ratio is typical of adducts XVIIa and
XVIIIa obtained in the reaction of diene III with
bromotrichloromethane.
Palladium(II) bromide as initiator gives rise to
a large amount of bromine-containing adducts which
can formally be regarded as products of addition of
CBrCl3 (Tables 1, 2). The formation of the complex
Pd(L1)Br2 in situ may be responsible for a fairly good
solubility of PdBr2 in the reaction mixture. The lack
of chlorine-to-bromine exchange in the CCl4 adducts
formed in the presence of PdBr2 was proved by
special experiment. After heating of the tetrachlorides
for 20 h at 97 C in the presence of PdBr2, no bromo-
trichloromethane adducts were detected.
In the addition to cis-cyclooctene (I) at low sub-
strate conversion, compounds IV and V prevail
among the products (Scheme 1). As the reaction
progresses, the corresponding tetrachlorides appear in
the reaction mixture, the overall yield of all addition
products reaching 11 mol per mole of PdBr2. It should
be emphasized that the ratio of by-products IV and
V in the Pd(L1)Br2-initiated addition of CCl4 is the
reverse, as compared to the ratio of the same products
formed by addition of CBrCl3 under conditions of
radical initiation. The ratio of by-products VI and
VII in the addition of CBrCl3 in the presence of
Pd(L1)Cl2 is the reverse with respect to that observed
in the addition of CCl4 in the presence of radical
initiators. These data clearly indicate halogen transfer
to alkyl radical from palladium and rule out the stage
of halogen exchange in CCl4 in the presence of PdBr2
and subsequent addition of BrCCl3.
We have found that carbon tetrachloride adds to
diene III in the dark at 20 C in the presence of Pd(II)
salts and complexes using DMSO as solvent, but in
the absence of radical initiators. The reaction is com-
plete in less than 10 min, and the ratio of products
XVb, XVIIb, and XVIIIb is the same as in the
reaction performed under typical radical initiation
conditions (provided that the concentration of CCl4
is the same). The reaction is accompanied by poly-
merization of the diene, and the yield of the addition
products is less than 4% calculated on the initial
diene. Similar results were obtained in the reaction of
CCl4 with preliminarily prepared Pd(L3)X2 complex.
In the addition of CCl4 to diene III in the presence
of PdBr2, as well as in the reaction with Pd(L3)Br2,
adducts XVIIa and XVIIIa were formed (which can
formally be regarded as products of BrCCl3 addition).
Their overall yield exceeds the overall yield of the
CCl4 addition products (XVb, XVIIb, and XVIIIb)
almost twofold, indicating the occurrence of bromine
atom transfer from the Pd(II) complex to alkyl radical
G. Therefore, we can conclude that the rate of
bromine transfer from the palladium complex is
higher than the rate of chlorine transfer from CCl4.
Compounds XVb, XVIIb, and XVIIIb were shown
to be stable under the given conditions.
A radical mechanism of the process, where the role
of palladium complex consists of generation of tri-
chloromethyl radical which then reacts with the
uncoordinated substrate (the latter is always present
in the reaction mixture due to equilibrium dissociation
of the complex) is supported by the following data:
(1) The reactions performed under typical radical
initiation conditions (UV irradiation or chemical
initiator) and in the presence of palladium(II) com-
plexes give the same products;
The addition of carbon tetrachloride to cyclohexene
in the presence of Pd(L1)Cl2 affords a different stereo-
chemical composition of the adducts: the product ratio
XI:XII is 70:30 against 56:44 under typical radical
initiation conditions (excess CCl4 as solvent, see
Table 2). Adducts XI and XII were proved to be
stable under the reaction conditions [in the presence
of Pd(L1)Cl2]. The reaction promoted by Pd(L1)Cl2
also afforded traces of cyclohexyl chloride which may
be formed by addition of HCl [which is released by
reduction of Pd(II) compounds] to cyclohexene.
(2) There are no differences in the stereoisomeric
composition of these products (this is seen especially
clearly in the reactions with bromotrichloromethane);
(3) The lack of an appreciable effect of palladium
concentration on the ratio of unrearranged and rear-
ranged products, e.g., in the reactions with diene III
(Scheme 5) and cycloalkene I (Scheme 1), which
involve competition between rearrangement of the
primarily formed radical and halogen transfer thereto.
Two possible ways of formation of trichloromethyl
radical in the presence of Pd(II) derivatives can be
proposed. The first of these is based on the mechanism
[7 9] including formation of low-valence palladium
The use of Pd(II) complex as initiator in the addi-
tion of CCl4 to cis-cyclooctene (I) leads to a consider-
able increase of the yield of unrearranged product VI
(Table 1). Compound VI is formed as a mixture of
cis and trans isomers at a ratio of 41.7:58.3. Dia-
stereoisomers of VII are characterized by similar
retention parameters in GLC analysis and similar
chemical shifts of the HCCl and HCCCl3 protons in
1
the H NMR spectra. The same applies to stereo-
isomers of compound V.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

ADDITION OF BROMOTRICHLOROMETHANE AND TETRACHLOROMETHANE
941
Scheme 6.
(1)
(2)
(3)
compounds. Triphenylphosphine is presumed to
reduce Pd(II) to Pd(0) in the presence of a base. The
subsequent single-electron transfer (SET) from Pd(0)
to polyhalomethane molecule yields radical anion
whose fragmentation leads to trichloromethyl radical,
while halide ion is bound to Pd(I) derivative. The
alkyl radical formed as a result of addition of tri-
chloromethyl radical at the double bond abstracts
halogen atom from palladium, thus regenerating
catalytically active Pd(0) species.
However, this mechanism is hardly consistent with
the fact that preliminarily prepared Pd(0) compounds
exhibit appreciably lower catalytic activity than Pd(II)
complexes, especially at low temperatures (as shown
in the addition of CBrCl3 to diene III; see Table 3).
The observed very high activity of Pd(II) complexes
at 20 C in the absence of reducing agents cannot be
explained in terms of the above mechanism as well.
The effect of oxygen traces on the yield of CBrCl3
adducts with cis-cyclooctene provides some support
to the reaction mediated by Pd(0) compounds. No
reaction occurs in the presence of oxygen, while
addition products are formed in low yields in the
presence of traces of oxygen. The yields given in
Table 1 were reached only when traces of oxygen
were removed completely from the reaction mixture
(see Experimental).
The second possible path of formation of trichloro-
methyl radical includes single-electron transfer from
palladium(II) complex with donor ligands. Scheme 6
illustrates the mechanism of addition of polyhalo-
methanes, initiated by chloride Pd(II) complexes;
an analogous scheme may be drawn for initiation by
bromide complexes. Reaction (3) regenerates the
initial Pd(II) species, and halogen transfer to alkyl
radical from palladium(III) complex formed by reac-
tion (1) gives cross-halogenation products. The forma-
tion of the latter cannot be rationalized in terms of the
mechanism involving Pd(0) compounds. No products
with X = Cl were detected in the addition of bromo-
trichloromethane to diene III, initiated by Pd(0)
compounds.
A mechanism analogous to that shown in Scheme 6
was proposed for the addition of CCl4 to cis-cyclo-
octene, initiated by triphenylphosphine ruthenium(II)
complexes [5]. Vedernikov et al. [24] presumed that
trichloromethyl radicals are formed in the catalytic
chlorination of hydrocarbons with carbon tetrachloride
in the presence of Pd(II) complexes. Oxidative addi-
tion of CCl4 to a Pd(II) complex with donor ligands
gives Pd(IV) complex which then undergoes dissocia-
tion into trichloromethyl radical and Pd(III) complex.
The existence of Pd(III) complexes was proved by
Cotton et al. [25] who reported on the synthesis of
a fairly stable Pd(III) compound by two-electron
oxidation of a dinuclear Pd(II) complex containing
four bidentate N-donor ligands, 1,3,4,6,7,8-hexahydro-
2H-pyrimido[1,2-a]pyrimidine anions. In this connec-
tion, it should be noted that the complex Pd(L1)Cl2
used in the present study is in fact a dinuclear com-
plex, {Pd(L1)Cl2}2, having two bridging chloride
ligands [26].
The mechanism shown in Scheme 6 is supported
by strong acceleration of the Pd(II)-initiated addition
of CBrCl3 in the presence of DMSO which is a donor
ligand. For example, the yield of adducts IX and X
increases from 2 to 7% in the presence of 2.5 mol of
DMSO per mole of Pd(L1)Cl2 (50 C, [Pd(L1)Cl2] =
0.032 M, Table 2). In the reactions with diene III in
the presence of Pd(OAc)2 in bromotrichloromethane
or benzene and in acetonitrile at 20 C (i.e., in solvents
which do not form complexes with palladium), the
yields of compounds XVa, XVIIa, and XVIIIa
(Scheme 5) did not exceed 9% in 18 h. After addition
of DMSO to the reaction mixture, the yield of XVa,
XVIIa, and XVIIIa quickly increased and attained
12% even in 5 min. The reaction of CBrCl3 with
diene III in DMSO in the presence of Pd(OAc)2 [the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

942
DNEPROVSKII et al.
Scheme 7.
concentrations of CBrCl3, diene III, and Pd(OAc)2
were 3.5, 2.0, and 0.2 M, respectively] was accom-
panied by strong evolution of heat, and the overall
yield of adducts XVa, XVIIa, and XVIIIa reached
86% in less than 5 min. These findings indicate the
necessity for a strong donor ligand (such as DMSO)
to be present in the coordination sphere of Pd(II)
to facilitate transformation of Pd(II) into Pd(III).
Obviously, acetate ion does not stabilize high-valence
palladium state. It is also probable that the structure
of Pd(OAc)2 (which is a trimer with bridging acetate
moieties [26]) hampers insertion of diene III molecule
into the metal coordination sphere and that there are
no such hindrances for DMSO.
The following explanation may be proposed for the
observed small reduction of the XVIIIa/XVIIa ratio
with increase in the concentration of diene III, when
the reaction was carried out in DMSO (Table 3).
Trichloromethyl radical is likely to react with both
free diene and the complex Pd(L3)X2 (Scheme 7).
Increase in the concentration of diene III in the reac-
tion mixture, the concentration of CBrCl3 remaining
unchanged, was accompanied by decrease in the
DMSO concentration, i.e., the ratio [DMSO]/[III]
changed from 45 ([III] = 0.2 M) to 1.2 ([III] =
3.4 M). This led to displacement of equilibrium (4)
and increased contribution of the reaction pathway
involving Pd-coordinated diene III (as bidentate
ligand; the palladium atom occupies the endo posi-
tion; the structure of the complex Pd(L3)Cl2 was
determined in [27]).
Halogen transfer to that radical from the endo side
should be more difficult than from the exo side. As
a result, we observe reduction in the yield of XVIIIa,
as compared to XVIIa.
It should be noted that in the addition of bromotri-
chloromethane to cis-cyclooctene (I) in the presence
of Pd(L1)Cl2, as well as in the presence of dimethyl-
glyoxime cobalt complexes, allylic bromination prod-
uct VIII is formed in an insignificant amount. This
indicates that palladium complex also acts as efficient
trap of bromine atoms, so that the allylic bromination
pathway is suppressed.
We can conclude that the addition of polyhalo-
methanes at the double bond of cycloalkenes involves
palladium(II) complexes both at the stage of radical
chain initiation (via single-electron transfer to poly-
halomethane and subsequent generation of trichloro-
methyl radical) and at the stage of halogen transfer.
The transfer occurs from both polyhalomethane mole-
cule and halide palladium complex.
EXPERIMENTAL
The NMR spectra were recorded on a Bruker
AMX-300 spectrometer operating at 300 MHz (for
1H). The structure of the products was confirmed by
the 1H, 13C, 1H-2D-COSY, and 1H-2D-NOESY
spectra. The product compositions were determined by
gas liquid chromatography and NMR spectroscopy.
GLC analysis was performed on a Chrom-5 chromato-
graph using 2.5-m 3-mm glass columns which were
packed with 10% of SE-30 on Chromaton N-Super
and 5% of OV-225 on the same support; carrier gas
argon; flame ionization detector.
(4)
Palladium(II) chloride (99%), norbornadiene (99%),
bromotrichloromethane (99%), cis-cyclooctene (99%),
and acetonitrile (chromatographically pure) were
commercial reagents. Carbon tetrachloride, benzene,
and dimethyl sulfoxide were purified by standard
Taking into account the above stated, trichloroalkyl
radical coordinated to palladium [Scheme 6, reac-
tion (3)] is likely to be formed via attack by trichloro-
methyl radical at the double bond of diene III.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

ADDITION OF BROMOTRICHLOROMETHANE AND TETRACHLOROMETHANE
943
1
procedures [28, 29]. Potassium carbonate (analytical
grade) was calcined for 3 h at 300 C. Cyclohexene
(99.5%, GLC) was synthesized by the procedure
described in [29].
65.5 C. H NMR spectrum (CDCl3), , ppm: 4.23 br.s
(1H, HCCl), 2.7 br.s (1H, HCCCl3), 2.6 1.4 m (12H,
CH2) (cf. [11]).
3-Bromocyclooctene (VIII) and 3-bromocyclo-
hexene (XIII) were synthesized by standard procedure
[29]. Compound VIII: bp 96 98 C (17 mm); pub-
1-Bromo-2-trichloromethylcyclooctane (IV) and
1-bromo-4-trichloromethylcyclooctane (V). A 10-ml
ampule was charged with a mixture of 1.2 ml
(9 mmol) of cis-cyclooctene (I), 125 mg (0.27 mmol)
of (PhCH2)Co(dmgH)2Py as radical initiator, and 5 ml
(51 mmol) of bromotrichloromethane. The mixture
was purged with a slight stream of argon over a period
of 15 min to remove dissolved oxygen, and the
ampule was sealed and heated for 2 h at 70 C. The
ampule was opened, excess bromotrichloromethane
was distilled off, and the residue was distilled under
reduced pressure, a fraction with bp 150 160 C
(15 mm) being collected. The distillate contained
regioisomeric products IV (trans/cis ratio 1:1) and
V [10] at a ratio of 70:30 (according to the GLC and
1
lished data [30]: bp 94 97 C (18 mm). H NMR
spectrum (CDCl3), , ppm: 5.81 m (1H, CBrCH C),
5.62 m (1H, HC CCBr), 4.97 m (1H, HCBr), 2.3
1.2 m (10H, CH2).
Compound XIII: bp 63 65 C (11 mm); published
data [29]: bp 75 C (16). H NMR spectrum (CDCl3),
, ppm: 5.94 m (1H, CBrCH C), 5.84 m (1H,
HC CCBr), 4.87 m (1H, HCBr), 2.3 1.65 m (6H,
CH2).
trans-1-Bromo-2-trichloromethylcyclohexane
(IX) and cis-1-bromo-2-trichloromethylcyclohexane
(X). A 50-ml test tube was charged with 15.4 ml
(0.152 mmol) of cyclohexene and 15 ml (0.152 mmol)
of bromotrichloromethane. The mixture was purged
with a slight stream of argon over a period of 15 min
to remove dissolved oxygen and was then irradiated
with UV light (medium-pressure mercury lamp) for
2.5 h with stirring at 30 C under a slight stream of
argon. When the reaction was complete, the mixture
was distilled under reduced pressure, a fraction with
bp 134 139 C (10 11 mm) being collected. Accord-
ing to the GLC and H NMR data, the product was
a mixture of diastereoisomers IX and X at a ratio of
58:42; published data [13]: bp 73 84 C (0.15 mm).
Yield 7.28 g (17%). H NMR spectrum (CDCl3), ,
ppm: 5.02 br.s (0.42H, HCBr, X), 4.86 m (0.58H,
HCBr, IX), 3.07 m (0.58H, HCCCl3, IX), 2.50 m
(0.42H, HCCCl3, X), 2.45 1.3 m (8H, CH2, IX+X).
trans-1-Chloro-2-trichloromethylcyclohexane
(XI) and cis-1-chloro-2-trichloromethylcyclohexane
(XII) were synthesized by the procedure reported in
[31]. According to the GLC and H NMR data, the
mixture contained diastereoisomers XI and XII at
a ratio of 57:43. H NMR spectrum (CDCl3), , ppm:
4.97 br.s (0.43H, HCCl, XII), 4.49 m (0.57H, HCCl,
XI), 2.84 m (0.57H, HCCCl3, XI), 2.64 m (0.43H,
HCCCl3, XII), 2.52 1.3 m (8H, CH2, XI+XII).
1
1
1H NMR data). H NMR spectrum (CDCl3), , ppm:
5.03 m (0.35H, HCBr, cis-IV), 4.76 m (0.35H, HCBr,
trans-IV), 4.43 m (0.30H, HCBr, V), 2.98 m (0.35H,
HCCCl3, trans-IV), 2.82 m (0.35H, HCCCl3, cis-IV),
2.72 m (0.30H, HCCCl3, V), 2.62 1.15 m [12H, CH2,
IV+V].
1-Chloro-2-trichloromethylcyclooctane (VI).
A 60-ml ampule was charged with 4.07 g of copper(I)
chloride, 14 ml of carbon tetrachloride, 3 ml of cyclo-
alkene I, and 26.5 ml of acetonitrile. The mixture
was purged with a slight stream of argon over a period
of 15 min to remove dissolved oxygen, and the
ampule was sealed and heated for 61 h at 95 C. The
ampule was opened, the solvent was distilled off,
the residue was treated with carbon tetrachloride, the
resulting solution was filtered through a 2-cm layer
of silica gel, the solvent was distilled off from the
filtrate, and the residue was distilled under reduced
pressure, a fraction with bp 135 140 C (12 mm)
being collected. The product was a mixture of cis
and trans isomers of VI at a ratio of 26:74 (according
1
1
1
1
1
1
to the H NMR data; the H NMR spectrum was
analogous to the spectrum of regioisomeric com-
pounds IV, in keeping with published data [11]).
1H NMR spectrum (CDCl3), , ppm: 4.94 m (0.26H,
HCCl, cis-VI), 4.61 m (0.74H, HCCl, trans-VI), 2.95
(0.26H, HCCCl3, cis-VI), 2.83 (0.74H, HCCCl3,
trans-VI), 2.3 1.2 m [12H, CH2, cis-VI+trans-VI).
3-Chlorocyclohexene (XIV) was synthesized by
the procedure described in [32]. A mixture of 5.1 g
(32 mmol) of compound XIII, 0.3 g (1.3 mmol) of
benzyltriethylammonium chloride, 50 ml of chloro-
form, and 100 ml of a saturated solution of calcium
chloride was heated for 12 h under stirring in an inert
atmosphere. When the reaction was complete, the
organic layer was separated, washed with water
(3 30 ml), dried over Na2SO4, and evaporated. The
1-Chloro-4-trichloromethylcyclooctane (VII) was
synthesized as described below for compounds XVIIb
and XVIIIb. The major components of the isolated
product were diastereoisomers of VII, one of which
was isolated in the pure form by recrystallization from
ethanol, mp 63.5 64 C; published data [11]: mp 64
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

944
DNEPROVSKII et al.
residue was distilled under reduced pressure, a frac-
tion with bp 50 C (20 mm) being collected. Yield 1 g
(27%); published data [31]: bp 84 C (100 mm). H
NMR spectrum (CDCl3), , ppm: 5.84 m (2H,
CH CH), 4.58 m (1H, HCBr), 2.3 1.65 m (6H, CH2).
remove dissolved oxygen, and the ampule was sealed
and heated for 15 h at 66 C. The ampule was opened,
excess carbon tetrachloride was distilled off, and
the residue was distilled under reduced pressure,
a fraction with bp 133 C (10 mm) being collected.
The product was a mixture of diastereoisomers XVIIb
and XVIIIb at a ratio of 65:35 (according to the GLC
and H NMR data). Yield 6.4 g (83%). H NMR
spectrum (CDCl3), , ppm: XVIIb: 3.91 s (1H, 5-H),
2.82 s (1H, 3-H), 2.55 s (1H, 4-H), 2.37 d (1H, 7 -H),
2.02 d (1H, 7 -H), 1.80 1.65 m (3H, 1-H, 2-H, 6-H);
XVIIIb: 4.0 s (1H, 5-H), 3.61 s (1H, 3-H), 2.49 s
(1H, 4-H), 2.37 d (1H, 7 -H), 1.80 1.65 m (3H, 1-H,
2-H, 6-H), 1.45 s (1H, 7 -H).
1
endo-5-Bromo-exo-6-trichloromethylbicyclo-
[2.2.1]hept-2-ene (XVa), exo-5-bromo-exo-6-tri-
chloromethylbicyclo[2.2.1]hept-2-ene (XVIa), exo-
5-bromo-exo-3-trichloromethyltricyclo[2.2.1.02,6]-
heptane (XVIIa), and endo-5-bromo-exo-3-tri-
chloromethyltricyclo[2.2.1.02,6]heptane (XVIIIa).
A 50-ml test tube was charged with a solution of 3 ml
(29.5 mmol) of diene III in 29.5 ml (300 mmol) of
bromotrichloromethane. The mixture was purged with
a slight stream of argon over a period of 15 min to
remove dissolved oxygen and was then irradiated with
UV light (medium-pressure mercury lamp) for 20 min
at 30 C with stirring under a slight stream of argon.
When the reaction was complete, excess bromotri-
chloromethane was distilled off, and the residue was
distilled under reduced pressure, a fraction boiling
in the temperature range from 100 to 150 C (2 mm)
being collected. The distillate was subjected to
column chromatography on silica gel using petroleum
ether as eluent. As a result, two fractions (1 and 2)
were isolated.
1
1
Dichloro(norbornadiene)palladium(II) was pre-
pared by a modified procedure [33]. Palladium(II)
chloride, 642 mg (3.62 mmol), was dissolved at
100 C in 11.3 ml of benzonitrile. The solution was
diluted with 10 ml of benzene and was separated from
the precipitate of PdCl2 by decanting, and 2 ml
(20 mmol) of diene III was added. After 10 min,
the precipitate was filtered off, washed in succession
with benzene and hexane, and dried under reduced
pressure. Yield 960 mg (98.3%). mp 200 202 C
(decomp.); published data [34]: mp 190 200 C
1
(decomp.). H NMR spectrum (DMSO-d6), , ppm:
Fraction 1 contained compound XVa as the major
component; 1H NMR spectrum (CDCl3), , ppm:
6.59 d.d (1H, 2-H), 6.30 d.d (1H, 3-H), 4.35 t (1H,
5-H), 3.30 s (1H, 4-H), 3.15 m (1H, 1-H), 2.89 d.d
(1H, 6-H), 2.29 d (1H, 7 -H), 1.66 m (1H, 7 -H).
Also, a small amount (12%, according to the GLC and
1H NMR data) of compound XVIa was present. The
1H NMR spectrum contained signals at 6.27 and
6.19 ppm, which are typical of protons at the double
bond in XVIa.
6.76 br.s (4H, CH ), 3.56 br.s (2H, CH), 1.88 br.s
(2H, CH2).
Dibromo(norbornadiene)palladium(II) [35] was
synthesized in a similar way. Yield 88.5%.
Dichlorobis(cyclooctene)di- -chlorodipalla-
dium(II). A mixture of 196 mg (1.103 mmol) of
palladium(II) chloride, 1.5 ml (11.5 mmol) of cyclo-
alkene I, and 30 ml of toluene was heated for 2 h at
100 C under stirring. The resulting brown solution
was separated from unreacted PdCl2. The solution was
cooled, the precipitate was filtered off, and the filtrate
was transferred back into the flask with unreacted
palladium(II) chloride. This procedure was repeated
twice more. The crystalline products were combined,
washed with toluene, and dried under reduced pres-
sure. Light brown fine crystals, yield 291 mg (91.7%).
1H NMR spectrum (DMSO-d6), , ppm: 5.59 m
(2H, CH ), 2.09 br.s (4H, CH2C ), 1.44 s (8H, CH2).
The concentration of cis-cyclooctene (I) in the com-
plex was determined from the intensity ratio of proton
signals of cis-cyclooctene (I) and internal standard
Fraction 2 contained a mixture of diastereoisomers
XVIIa and XVIIIa at a ratio of 69:31 (according
1
1
to the GLC and H NMR data). H NMR spectrum
(CDCl3), , ppm: XVIIa: 3.96 s (1H, 5-H), 2.83 s
(1H, 3-H), 2.57 s (1H, 4-H), 2.37 d (1H, 7 -H), 2.06 d
(1H, 7 -H), 1.84 1.55 m (3H, 1-H, 2-H, 6-H);
XVIIIa: 4.03 s (1H, 5-H), 3.65 s (1H, 3-H), 2.51 s
(1H, 4-H), 2.37 d (1H, 7 -H), 1.84 1.55 m (3H, 1-H,
2-H, 6-H), 1.46 s (1H, 7 -H).
exo-5-Chloro-exo-3-trichloromethyltricyclo-
[2.2.1.02,6]heptane (XVIIb) and endo-5-chloro-exo-
3-trichloromethyltricyclo[2.2.1.02,6]heptane
(XVIIIb). A 20-ml ampule was charged with a solu-
tion of 3.2 ml (31.5 mmol) of diene III and 0.5 g
(2 mmol) of benzoyl peroxide in 10 ml (104 mmol)
of carbon tetrachloride. The mixture was purged with
a slight stream of argon over a period of 15 min to
1
in the H NMR spectrum (DMSO-d6) of a mixture of
10.05 mg (0.0349 mmol) of the complex and 11 mg
of naphthalene (internal standard): 0.0346 mmol
(99.1%). mp 160 170 C (decomp.); published data
[36]: mp 163 167 C (decomp.).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

ADDITION OF BROMOTRICHLOROMETHANE AND TETRACHLOROMETHANE
945
Palladium(II) bromide [37], palladium(II) acetate
[38], and tetrakis(triphenylphosphine)palladium(0)
[23] were synthesized by known methods.
a specified temperature for a required time. The
ampule was opened, and the mixture was treated as
described above in c prior to analysis.
d. Reaction of XCCl3 with Pd(L3)X2 (X = Cl, Br).
The reactions were carried out in vessels consisting
of two parts separated by a thin glass membrane. One
part of the vessel was charged with a solution of
Pd(L3)X2 (0.01 0.08 mmol) and biphenyl (internal
standard, 0.001 0.003 mmol) in DMSO, and the other
part was charged with a required amount of XCCl3.
Dissolved oxygen was removed from both parts as
described in a, the vessel was adjusted to a constant
temperature, the reactants were quickly mixed by
breaking the membrane, and the mixture was main-
tained for a required time at a specified temperature.
Prior to analysis, the vessel was opened, and the
mixture was treated as described in c.
Procedures for kinetic measurements. a. Reac-
tion of XCCl3 (X = Cl, Br) with norbornadiene (III)
under typical radical initiation conditions. An ampule
was charged with a solution of diene III (0.02
0.7 mmol), azobis(isobutyronitrile) or benzoyl per-
oxide (0.001 0.005 mmol), XCCl3 (0.5 2.0 mmol),
and biphenyl (internal standard, 0.001 0.003 mmol)
in DMSO. A slight stream of argon was passed
through the mixture over a period of 5 10 min to
remove dissolved oxygen, and the mixture was heated
or irradiated with UV light (medium-pressure mercury
lampa) over a required period (from 5 min to 30 h)
1
and was then analyzed by GLC or H NMR spec-
troscopy.
f. Reaction of BrCCl3 with diene III in the pres-
ence of the catalytic system PdCl2 PPh3 K2CO3.
An ampule was charged with palladium(II) chloride,
triphenylphosphine, potassium carbonate, diene III,
and bromotrichloromethane at a molar ratio of
0.01:0.02:1:1:1; benzene was used as solvent. The
mixture was freed from dissolved oxygen by purging
with a slight stream of argon, and the ampule was
sealed and was maintained at a specified temperature
for a required time. Prior to analysis, the mixture
was treated as described in c.
b. Reactions of XCCl3 (X = Cl, Br) with cyclo-
alkenes I and II under typical radical initiation con-
ditions were carried out following procedure a, but
excess XCCl3 was used as solvent. Some experiments
were performed with (PhCH2)Co(dmgH)2Py as
initiator.
c. Reactions of XCCl3 (X = Cl, Br) with cyclo-
alkenes I and II in the presence of Pd(II) compounds.
A 1.5-ml ampule was charged with Pd(II) compound
(0.003 0.03 mmol), cycloalkene I or II (0.3
0.4 mmol), and 0.5 ml of XCCl3. A slight stream of
argon was passed through the mixture over a period
of 5 6 min to remove dissolved oxygen, the mixture
was frozen with liquid nitrogen, and the gas phase
over it was evacuated to a residual pressure of
1 2 mm. The ampule was disconnected from the
vacuum system and was carefully warmed to room
temperature. The procedure was repeated for three
times, and the evacuated ampule with frozen liquid
phase was sealed and was kept at a specified tempera-
ture for a required time. The ampule was opened, the
mixture was passed through a column charged with
silica gel (1 2 cm) to remove palladium compounds,
organic products were eluted with hexane, and the
resulting solution was evaporated. Biphenyl (internal
standard) was added, and the product mixture was
This study was financially supported by the Rus-
sian Foundation for Basic Research (project no. 01-
03-32330a) and by the Universities of Russia Founda-
tion (project no. UR.05.01.011).
REFERENCES
1. Asscher, M. and Vofsi, D., J. Chem. Soc., 1963,
p. 1887.
2. Murai, S. and Tsutsumi, S., J. Org. Chem., 1966,
vol. 31, p. 3000.
3. Hajek, M. and Silhavy, P., Collect. Czech. Chem.
Commun., 1983, vol. 48, p. 1710.
4. Matsumoto, H., Nikaido, T., and Nagai, Y., Tetra-
hedron Lett., 1975, p. 899.
1
5. Matsumoto, H., Nakano, T., Takasu, K., and
analyzed by GLC or H NMR spectroscopy.
Nagai, Y., J. Org. Chem., 1978, vol. 43, p. 1734.
d. Reaction of XCCl3 (X = Cl, Br) with diene III
in the presence of Pd(II) and Pd(0) compounds.
An ampule was charged with specified amounts of
appropriate palladium compound, diene III, XCCl3,
and DMSO as solvent (the amount of the latter was
varied so that to attain a required reactant concentra-
tion). The mixture was freed from oxygen as described
above in a. The ampule was sealed and was kept at
6. Tsuji, J., Sato, K., and Nagashima, H., Chem. Lett.,
1981, p. 1169.
7. Tsuji, J., Sato, K., and Nagashima, H., Tetrahedron,
1985, vol. 41, p. 393.
8. Nagashima, H., Sato, K., and Tsuji, J., Chem. Lett.,
1981, p. 1605; Nagashima, H., Sato, K., and Tsuji, J.,
Tetrahedron, 1985, vol. 41, p. 5645.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003

946
DNEPROVSKII et al.
9. Tsuji, J., Sato, K., and Nagashima, H., Tetrahedron
25. Cotton, F.A., Gu, J., Murillo, C.A., and Tim-
mons, D.J., J. Am. Chem. Soc., 1998, vol. 120,
p. 13280.
Lett., 1982, vol. 23, p. 893; Tsuji, J., Sato, K., and
Nagashima, H., Tetrahedron, 1985, vol. 41, p. 5003.
10. Traynham, J.G., Couvillon, T.M., and Bhacca, N.S.,
26. Maitlis, P.M., The Organic Chemistry of Palladium,
J. Org. Chem., 1967, vol. 32, p. 529.
New York: Academic, 1971, vol. 1, p. 112.
11. Traynham, J.G. and Couvillon, T.M., J. Am. Chem.
Soc., 1967, vol. 89, p. 3205.
27. Baenziger, N.C., Doyle, J.R., and Carpenter, C.,
Acta Crystallogr., 1961, vol. 14, p. 303.
12. Tanner, D.D., Arhart, R.J., Blackburn, E.V.,
Das, N.C., and Wada, N., J. Am. Chem. Soc., 1974,
vol. 96, p. 829; Tanner, D.D. and Wada, N., J. Am.
Chem. Soc., 1975, vol. 97, p. 2190; Tanner, D.D.,
Blackburn, E.V., Reed, D.W., and Setiloan, B.P.,
J. Org. Chem., 1980, vol. 45, p. 5183; Dneprov-
skii, A.S. and Eliseenkov, E.V., Ross. Khim. Zh.,
1999, vol. 43, p. 57.
28. Gordon, A.J. and Ford, R.A., The Chemist’s Compa-
nion, New York: Wiley, 1972. Translated under the
title Sputnik khimika, Moscow: Mir, 1976, p. 438.
29. Organikum. Organisch-chemisches Grundpraktikum,
Berlin: Wissenschaften, 1976, 15th ed. Translated
under the title Organikum. Praktikum po organiche-
skoi khimii, Moscow: Mir, 1979, vol. 1, pp. 230,
306; vol. 2, p. 356.
13. Traynham, J.G., Lane, A.G., and Bhacca, N.S.,
30. Ziegler, K. and Wilms, H., Justus Liebigs Ann.
Chem., 1950, vol. 567, p. 1.
J. Org. Chem., 1969, vol. 34, p. 1302.
14. Melville, H.W., Robb, J.C., and Tutton, R.C.,
31. Kooyman, E.C. and Farenhorst, E., Recl. Trav.
Chim. Pays Bas, 1951, vol. 70, p. 867.
Discus. Faraday Soc., 1951, p. 154.
15. Kooyman, E.C., Discuss. Faraday Soc., 1951, p. 163.
32. Dehmlow, E.V. and Dehmlow, S.S., Phase-Transfer
Catalysis, Weinheim: Chemie, 1983, 2nd ed. Tran-
slated under the title Mezhfaznyi kataliz, Moscow:
Mir, 1987, pp. 88, 109.
16. Landolt-Bornstein. Numerical Data and Functional
Relationships in Science and Technology. New
Series. Group II: Atomic and Molecular Physics,
Berlin: Springer, 1984, vol. 13.
33. Kharasch, M.S., Seyler, R.C., and Mayo, F.R., J. Am.
Chem. Soc., 1938, vol. 60, p. 882.
17. Alfassi, Z.B. and Feldman, L., Int. J. Chem. Kinet.,
1981, vol. 13, p. 771.
34. Abel, E.W., Bennett, M.A., and Wilkinson, G.,
18. Tsuji, J., Palladium Reagents and Catalysts. Innova-
tions in Organic Synthesis, Chichester: Wiley, 1998,
p. 19.
J. Chem. Soc., 1959, p. 3178.
35. Alexander, R.A., Baenziger, N.C., Carpenter, C.,
and Doyle, J.R., J. Am. Chem. Soc., 1960, vol. 82,
p. 535.
19. Brace, N.O., J. Org. Chem., 1962, vol. 27, p. 3027.
20. Davies, D.I. and Parfitt, L.T., J. Chem. Soc. C, 1967,
36. Huettel, R., Dietl, H., and Christ, H., Chem. Ber.,
p. 2691.
1964, vol. 97, p. 2037.
21. Giese, B. and Jay, K., Chem. Ber., 1977, vol. 110,
37. Handbuch der praparativen anorganischen Chemie,
Brauer, G., Ed., Stuttgart: Enke, 1981. Translated
under the title Rukovodstvo po neorganicheskomu
sintezu, Moscow: Mir, 1985, vol. 5, p. 1831.
p. 1364.
22. Kukushkin, Yu.N., Vlasova, R.A., and Pazukhi-
na, Yu.L., Zh. Prikl. Khim., 1968, vol. 41, p. 2381.
23. Inorganic Syntheses, Cotton, F.A., Ed., New York:
38. Dzhemilev, U.M., Popod’ko, N.R., and Kozlo-
va, E.V., Metallokompleksnyi kataliz v organiche-
skom sinteze. Alitsiklicheskie soedineniya (Metal
Complex Catalysis in Organic Synthesis. Alicyclic
Compounds), Moscow: Khimiya, 1999, p. 100.
McGraw Hill, 1972, vol. 13, pp. 53, 121.
24. Vedernikov, A.N., Kuramshin, A.I., Sayakhov, M.D.,
Sobanov, A.A., and Solomonov, B.N., Russ. J. Org.
Chem., 1997, vol. 33, p. 29.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 7 2003