Zirconium-catalyzed reaction of terminal alkenes with triethylindium

Article abstract of DOI:10.1134/S1070428013090017

Terminal alkenes (undec-1-ene, oct-1-ene, and allylbenzene) reacted with triethylindium in the presence of a catalytic amount of Cp₂ZrCl ₂ in hexane to give mixtures of three organoindium compounds whose hydrolysis in D₂O afforded 2-substituted 1,4-dideuterobutane containing minor amounts of 2-substituted 1- and 4-deuterobutanes.

Full text of DOI:10.1134/S1070428013090017

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2013, Vol. 49, No. 9, pp. 1253–1256. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © I.R. Ramazanov, L.K. Dil’mukhametova, U.M. Dzhemilev, 2013, published in Zhurnal Organicheskoi Khimii, 2013, Vol. 49, No. 9,
pp. 1271–1274.
Zirconium-Catalyzed Reaction of Terminal Alkenes
with Triethylindium
I. R. Ramazanov, L. K. Dil’mukhametova, and U. M. Dzhemilev
Institute of Petrochemistry and Catalysis, Russian Academy of Sciences,
pr. Oktyabrya 141, Ufa, 450075 Bashkortostan, Russia
e-mail: iramazan@inbox.ru
Received January 8, 2013
Abstract—Terminal alkenes (undec-1-ene, oct-1-ene, and allylbenzene) reacted with triethylindium in the
presence of a catalytic amount of Cp2ZrCl2 in hexane to give mixtures of three organoindium compounds
whose hydrolysis in D2O afforded 2-substituted 1,4-dideuterobutane containing minor amounts of 2-substituted
1- and 4-deuterobutanes.
DOI: 10.1134/S1070428013090017
Carbometalation of olefins and acetylenes provides
a convenient method for building up carbon–carbon
bonds. Catalytic carbomagnesation and carboalumina-
tion have found wide application in practical organic
synthesis [1, 2]. Zirconium-catalyzed reactions of
olefins and acetylenes with alkylmagnesiums and
alkylaluminums follow a complicated pattern. Depend-
ing on the conditions, solvent, and organometallic
reagent nature, these reactions can occur as carbo-
metalation, cyclometalation, or hydrometalation. As
a rule, cyclometalation is promoted by ethyl deriva-
tives of aluminum and magnesium. Cycloalumination
by the action of triethylaluminum was reported for the
first time in 1989 [3], and catalytic cyclomagnesation
of terminal alkenes with Et2Mg was described later
[4, 5]. On the other hand, Cp2ZrCl2-catalyzed reaction
of Et2Zn with terminal alkenes (α-olefins) afforded
only carbometalation products [6]. Thus, the role of the
metal nature is important in this reaction. Organo-
indium reagents turned out to be efficient in cross-
couplings with various aryl halides [7]; therefore, the
synthesis of indiacyclopentanes and their subsequent
functionalization seem to be an important problem.
With a view to develop new methods of synthesis of
organoindium compounds and elucidate the effect of
the metal nature on the ratio of carbo- and cyclo-
metalation products, in the present work we examined
reactions of Et3In with α-olefins in the presence of
a catalytic amount of Cp2ZrCl2.
unsaturated subststrate) in hexane at 40°C (reaction
time 6 h), and the subsequent hydrolysis in D2O
afforded 1-deutero-3-(deuteromethyl)dodecane (Ia)
containing D–H exchange products as impurities
(Scheme 1). The overall yield was 84%. According to
the 13C NMR data, the degree of deuteration of C1 was
66%, and of C13, 80%. Presumably, the reaction mix-
ture obtained after deuterolysis contained dideutero
derivative Ia together with monodeutero derivatives
IIa and IIIa and 3-methyldodecane; a mixture of the
latter three products at a definite ratio is characterized
by the observed deuterium distribution. The 13C NMR
spectrum of Ia with impurities of products of deute-
rium replacement by hydrogen coincided with the
spectrum of the deuterolysis product of aluminacyclo-
pentane derived from undec-1-ene [3], but two ad-
ditional signals were present due to terminal carbon
atom of the ethyl group and methyl carbon atom. The
molecular ion peak in the mass spectrum of the
deuterolysis products had an m/z value of 186, which
unambiguously confirmed structure Ia.
Thus, the Cp2ZrCl2-catalyzed reaction of undec-1-
ene with Et3In gives rise to a mixture of organoindium
compounds A–C and 3-methyldodecane. To determine
the product ratio, the reaction mixture obtained by
Cp2ZrCl2-catalyzed reaction of undec-1-ene with Et3In
was subjected to bromination with Br2 in THF at
–60°C. According to the 1H NMR data, the ratio of the
resulting bromoalkanes IVa, Va, and VIa was ~5:2:3.
GLC analysis showed the absence of 3-methyldo-
decane among the products, which indicated formation
Undec-1-ene reacted with 2 equiv of Et3In in the
presence of Cp2ZrCl2 (10 mol % with respect to the
1253

RAMAZANOV et al.
1254
Scheme 1.
Et3In (2 equiv), Cp2ZrCl2 (0.1 equiv)
hexane, 40°C, 6 h
Me
InEt2
InEt2
InEt2
Me
+
+
R
CH2
InEt2
R
R
Me
R
A
B
C
D
D
D
D2O
+
+
+
+
D
R
R
R
Me
R
R
Ia–Ic
IIa–IIc
IIIa–IIIc
Me
Br
Br
Br
Br2, THF, –60°C
Br
R
Me
IVa, IVb
Va, Vb
VIa, VIb
R = n-C9H19 (a), n-C6H13 (b), PhCH2 (c).
of a mixture of compounds Ia, IIa, and IIIa after
deuterolysis. The ratio of bromoalkanes IVa, Va, and
VIa was fairly consistent with the observed degree of
deuteration. However, the NMR spectra of the mixture
obtained by catalytic reaction of Et3In with undec-1-
ene did not allow us to unambiguously determine the
structure of organoindium compounds A–C.
It should be noted that the mechanism of Cp2ZrCl2-
catalyzed reaction of α-olefins with ethyl derivatives of
transition metals (Al, Mg, Zn, In) depends on the
nature of the organometallic reagent. The reactions
with Et3Al generally follow the cycloalumination path,
and hydrolysis of the reaction mixture with D2O yields
dideutero derivatives with a degree of deuteration of
more than 95%. The catalytic reaction of Et2Zn with
α-olefins gives exclusively carbometalation products.
The results of the present work showed that the
Cp2ZrCl2-catalyzed reaction of terminal alkenes with
Et3In involves both carboindation and other processes
which will be the subject of our further studies.
Oct-1-ene and allylbenzene reacted with triethyl-
indium in a similar way. The degree of deuteration of
compounds Ib and Ic ranged from 55 to 84% (Ib: 62%
at C1 and 84% at C10; Ic: 55% at C1 and 81% at C11).
Dideutero derivatives Ib and Ic were identified by
comparing their 13C NMR spectra with those of 1-deu-
tero-3-(deuteromethyl)nonane [3] and 1-[4-deutero-2-
(deuteromethyl)butyl]benzene [8] which were synthe-
sized previously by deuterolysis of the cycloalumina-
tion products of oct-1-ene and allylbenzene. The reac-
tion mixture obtained from oct-1-ene was subjected to
bromination as described above for the reaction with
undec-1-ene. The yield of dibromo derivative IVb was
40%, and 45% of a mixture of bromoalkanes Vb and
VIb at a ratio of ~2:5 was also isolated. The ratio of
bromo derivatives IVb, Vb, and VIb corresponded to
the degree of deuteration of compound Ib.
We can conclude that one of the main products in
the reactions under study is organoindium compound
A. It is likely to be formed according to a mechanism
analogous to that proposed for the cycloalumination of
α-olefins with Et3Al. In addition, considerable amounts
of organoindium compounds B and C are formed. The
latter can formally be regarded as carboindation prod-
uct; however, simultaneous formation of compound C
suggests a more complicated mechanism of the reac-
tion under study.
EXPERIMENTAL
All reactions were carried out under argon with
commercially available reagents. Hexane was prelim-
inarily distilled over (i-Bu)3Al. Triethylindium was
prepared by transalkylation of InCl3 with triethyl-
aluminum in the presence of KCl [9] and subsequent
distillation. Its purity was checked by 1H and 13C NMR
spectroscopy. The reaction mixtures and products were
analyzed by GLC on a Carlo Erba chromatograph
equipped with a flame ionization detector and a 25-m×
0.2-mm Ultra-1 glass capillary column (Hewlett
Packard); oven temperature 50–170°C; carrier gas
helium. The mass spectra (electron impact, 70 eV)
were obtained on a Finnigan 4021 instrument (ion
source temperature 200°C). The elemental composi-
tions were determined on a Carlo Erba 1106 analyzer.
The bromine content was determined according to
Schöniger [10]. The NMR spectra were recorded on
a Bruker Avance 400 spectrometer at 400.13 MHz for
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ZIRCONIUM-CATALYZED REACTION OF TERMINAL ALKENES
1255
1H and 100.62 MHz for 13C using CDCl3 as solvent
and tetramethylsilane as reference. The degree of deu-
teration at particular carbon atoms was estimated by
comparing the intensities of signals in the 13C NMR
spectra of the hydrolysis products, recorded under
similar conditions (probe temperature, solvent concen-
tration, magnetic field parameters, and pulse sequence
parameters).
(1H each, 4-H), 7.10–7.25 m (4H, 6-H, 7-H, 9-H,
10-H), 7.25–7.35 m (1H, 8-H). 13C NMR spectrum
1
(CDCl3), δC1, ppm: 11.19 t (C1, JCD = 19.00 Hz),
18.64 t (C11, JCD = 19.00 Hz), 29.71 (C2), 31.94 (C3),
43.33 (C4), 125.55 (C8), 128.05 (C7, C9), 129.18 (C6,
C10), 141.73 (C5). Found, %: C 88.17. C11H14D2. Cal-
culated, %: C 87.93.
Typical bromination procedure. Zirconium-cata-
lyzed reaction of α-olefins with Et3In was carried out
as described above, except for deuterolysis. Diethyl
ether, 5 ml, and pyridine, 1 ml, were added to the
reaction mixture, the mixture was cooled to –60°C,
and a solution of 6 mmol (0.31 ml) of bromine in 4 ml
of tetrahydrofuran was added dropwise. The mixture
was stirred for 15 min at –60°C and slowly poured into
a mixture of ice with 5% aqueous HCl. The organic
phase was separated, the aqueous phase was extracted
with diethyl ether, and the extract was combined with
the organic phase, dried over CaCl2, and concentrated
under reduced pressure. The products were isolated by
distillation under reduced pressure.
Typical procedure for the Cp2ZrCl2-catalyzed
reaction of terminal alkenes with triethylindium.
A reactor was filled with argon and charged in succes-
sion with 1 mmol of undec-1-ene, oct-1-ene, or allyl-
benzene, 0.1 mmol (0.029 g) of Cp2ZrCl2, 5 ml of
hexane, and 2 mmol of Et3In, and the mixture was
stirred for 6 h at 40°C. The mixture was then diluted
with 5 ml of hexane and cooled to 0°C, 3 ml of D2O
was added dropwise, and the precipitate was filtered
off. The organic phase was separated, the aqueous
phase was extracted with diethyl ether, and the extract
was combined with the organic phase, dried over
CaCl2, and concentrated under reduced pressure. The
products were isolated by distillation under reduced
pressure.
1-Bromo-3-(bromomethyl)dodecane (IVa). Yield
1
47%, bp 143–144°C (3 mm). H NMR spectrum, δ,
ppm: 0.90 t (3H, C12H3), 1.20–1.50 m (16H, 4-H–
11-H), 1.50–1.60 m (2H, 2-H), 1.85–2.10 m (1H, 3-H),
3.40–3.55 m (4H, 1-H, 13-H). 13C NMR spectrum
(CDCl3), δC, ppm: 14.12 (C12), 22.68 (C11), 26.62 (C5);
29.32, 29.56, 29.60, 29.64 (C6, C7, C8, C9); 31.90 (C10),
32.02 (C1), 32.20 (C4), 34.89 (C3), 37.44 (C2), 40.07
(C13). Found, %: C 45.80; H 7.53; Br 48.1. C13H26Br2.
Calculated, %: C 45.63; H 7.66; Br 46.71.
(1-2H1)-3-[(2H1)Methyl]dodecane (Ia). Overall
yield of Ia, IIa, and IIIa 84%, ratio 46 : 20 : 34.
1
bp 100–103°C (10 mm). H NMR spectrum, δ, ppm:
0.90 t (3H, C12H3, J = 7.0 Hz), 0.80–0.95 m (4H, 1-H,
13-H), 1.00–1.40 m (18H, 2-H–11-H), 1.40–1.45 m
(1H, 3-H). 13C NMR spectrum (CDCl3), δC, ppm:
11.12 t (C1, 1JCD = 19 Hz), 18.91 t (C13, 1JCD = 19 Hz),
14.14 (C12), 22.70 (C11), 27.13 (C5), 29.49 (C2), 29.38
(C7), 29.75 (C6), 29.68 (C8), 30.05 (C9), 31.94 (C10),
34.31 (C3), 36.66 (C4). Mass spectrum: m/z 186 [M]+.
Found, %: C 83.69. C13H26D2. Calculated, %: C 83.78.
M 186.37.
1-Bromo-3-methyldodecane (Va) and 1-bromo-2-
ethylundecane (VIa). Overall yield 45%, ratio ~1:2,
bp 101–106°C (1 mm). 13C NMR spectrum (CDCl3),
δC, ppm: 11.98 (C13′), 14.15 (C12, C11′), 19.35 (C13),
22.71 (C11, C10′), 25.73 (C12′), 26.12 (C5), 26.55 (C4′);
29.30, 29.51, 29.58, 29.60 (C6, C7, C8, C9, C5′, C6′, C7′,
C8′); 30.88 (C4), 31.18 (C3′), 31.52 (C2), 31.95 (C10,
C9′), 35.54 (C3), 36.62 (C2′), 38.29 (C1′), 40.13 (C1).
Found, %: C 58.73; H 10.15; Br 32.2. C13H27Br. Cal-
culated, %: C 59.31; H 10.34; Br 30.35.
(1-2H1)-3-[(2H1)Methyl]nonane (Ib). Overall yield
of Ib, IIb, and IIIb 67%, ratio 46:16:38. bp 55–58°C
(15 mm). 1H NMR spectrum, δ, ppm: 0.90 t (3H, C9H3,
J = 6.8 Hz), 0.80–0.85 m (4H, 1-H, 10-H), 1.00–
1.40 m (12H, 2-H–8-H), 1.40–1.50 m (1H, 3-H).
13C NMR spectrum (CDCl3), δC, ppm: 11.10 t (C1,
1
1JCD = 18 Hz), 18.91 t (C10, JCD = 19 Hz), 14.14 (C9),
1-Bromo-3-(bromomethyl)nonane (IVb). Yield
22.71 (C8), 27.15 (C5), 29.45 (C2), 29.80 (C6), 31.66
(C7), 34.51 (C3), 36.79 (C4). Found, %: C 83.11.
C10H20D2. Calculated, %: C 83.24.
1
40%, bp 127–129°C (3 mm). H NMR spectrum, δ,
ppm: 0.90 t (3H, C9H3, J = 10 Hz), 1.20–1.50 m (10H,
4-H–8-H), 1.80–2.20 m (3H, 2-H, 3-H), 3.35–3.50 m
(1-H, 10-H). 13C NMR spectrum (CDCl3), δC, ppm:
14.13 t (C9), 22.68 (C8), 26.64 (C5), 28.43 (C6), 31.79
(C7), 32.09 (C1), 32.97 (C4), 34.18 (C3), 35.67 (C2),
40.14 (C10). Found, %: C 40.57; H 6.65; Br 54.9.
C10H20Br2. Calculated, %: C 40.03; H 6.72; Br 53.26.
{(4-2H1)-2-[(2H1)Methyl]butyl}benzene (Ic).
Overall yield of Ic, IIc, and IIIc 81%, ratio 36:19:45.
1
bp 70–73°C (10 mm). H NMR spectrum, δ, ppm:
0.80–1.10 m (4H, 1-H, 11-H), 1.12–1.32 m (2H, 2-H),
1.60–1.70 m (1H, 3-H), 2.35–2.45 m and 2.60–2.70 m
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 9 2013

RAMAZANOV et al.
1256
4. Dzhemilev, U.M., Sultanov, R.M., Gaimaldinov, R.G.,
1-Bromo-3-methylnonane (Vb) and 1-bromo-2-
and Tolstikov, G.A., Izv. Akad. Nauk, Ser. Khim., 1991,
p. 1388.
ethyloctane (VIb). Overall yield 45%, ratio ~2 :5,
bp 108–112°C (10 mm). 13C NMR spectrum (CDCl3),
δC, ppm: 11.90 (C10′), 14.10 (C9, C8′), 19.44 (C10),
22.65 (C8, C7′), 25.64 and 25.71 (C5, C4′), 26.03 (C9′),
26.50 (C7, C5′), 30.98 (C6), 31.04 (C3′), 31.83 (C6′),
35.17 (C3), 36.51 (C4), 40.52 (C2′), 31.41 (C2), 38.34
(C1′), 40.94 (C1). Found, %: C 53.66; H 9.37; Br 39.0.
C10H21Br. Calculated, %: C 54.30; H 9.57; Br 36.13.
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