First synthesis of magnesacyclopentadienes from acetylenes by treatment with BuMgHlg in the presence of Zr complexes

Article abstract of DOI:10.1134/S1070428007020030

Treatment of internal acetylenes and allenes with BuMgHlg (Hlg = Cl, Br) in the presence of Cp₂ZrCl₂ selectively leads to the formation of substituted magnesacyclopenta-2,4-dienes and alkylidenemagnesacyclopentenes.

Full text of DOI:10.1134/S1070428007020030

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 2, pp. 176−180. © Pleiades Publishing, Ltd. 2007.
Original Russian Text © U.M. Dzhemilev, A.G. Ibragimov, V.A. D’yakonov, R.A. Zinnurova, 2007, published in Zhurnal Organicheskoi Khimii,
2007, Vol. 43, No. 2, pp. 184−188.
First Synthesis of Magnesacyclopentadienes from Acetylenes
by Treatment with BuMgHlg in the Presence of Zr Complexes
U. M. Dzhemilev,A. G. Ibragimov, V.A. D’yakonov, and R. A. Zinnurova
Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, Ufa,450075 Russia
e-mail: ink@anrb.ru
Received January 18, 2006
Abstract—Treatment of internal acetylenes and allenes with BuMgHlg (Hlg = Cl, Br) in the presence of Cp2ZrCl2
selectively leads to the formation of substituted magnesacyclopenta-2,4-dienes and alkylidenemagnesacyclo-
pentenes.
DOI: 10.1134/S1070428007020030
First publication on the direct catalytic preparation of
a magnesacyclopentanes from olefins using Grignard
reagents or R2Mg appeared in 1989 [1]. Later this
reaction was extended to allenes that in the presence of
Ti-containing catalysts gave rise to 2,5-dialkylidene-
magnesacyclopentanes in high yields [2]. Until our studies
no information was published on the possibility to involve
acetylenes into this process.
zirconium complexes which are the most active and
selective in cyclometallation of unsaturated compounds
[3, 4].As objects of the study were chosen internal acetyl-
enes and available alkylmagnesium halides.
The reaction of 4-octyne with BuMgBr (Et2O) in
molar ratio 1:2 catalyzed by Cp2ZrCl2 (10 mol%) gave
rise at ~20°C within 2 h to 2,3,4,5-tetrapropylmagnes-
acyclopentadiene (Ib) in ~ 50% yield. The structure and
composition of magnesacyclopentadiene Ib were
established from the 13C NMR spectra and from analysis
of products of hydrolysis IIIb and of reaction with
deuterium oxide IVb (Scheme 1).
The target of this study consists in the synthesis of
a new class of organomagnesium compounds, magnesa-
cyclopentadienes, by reaction of internal acetylenes with
Grignard reagents in the presence of catalysts containing
Scheme 1.
R'
R'
3
R'
R'
R'
R
[Zr]
Et2O
4
+
_MgX2
2
5
BuMgX
1
R
R
R
XMg
R
_
Mg
_
)
(
+
MgX
IIа IId
_
Iа Id
H3O+
D3O+
H
D
R'
R
R'
R
R
R
R'
R'
H
D
_
_
IIIа IIId
IVа IVd
[Zr] = Cp2ZrCl2; X = Cl, Br; R = R' = Et (a), Pr (b), Bu (c); R = Me3Si, R' = Bu (d).
176

FIRST SYNTHESIS OF MAGNESACYCLOPENTADIENES
177
Scheme 2.
R
R
R
R
R'
R'
BuMgX, [Zr]
+
_MgX2
_
R'
)
(
R
+
R
Mg
MgX
XMg
_
_
VIа VIc
Vа Vc
H3O+
D3O+
R
R
R'
R'
R
R
D
VIIIа VIIIc
H
H
D
_
_
VIIа VIIc
[Zr] = Cp2ZrCl2; X = Cl, Br; R = Et, R’=Amyl (a); R = Pr, R’=Amyl (b); R = Pr, R’= Ph (c).
13C NMR spectrum of compound Ib contains a down-
field signal at 191.10 ppm that we assumed to belong to
sp2-carbon atom (C2–Mg) of magnesacyclopentadiene
ring. This conclusion was based on previously published
data [5] that in the 13C NMR spectrum of a mixture
containing 2,5-dihexylidenemagnesacyclopentane and
unsaturated acyclic 1,4-dimagnesium compound existing
in a Schlenk equilibrium appeared signals at 188.30 and
166.36 ppm belonging respectively to the sp2-carbon
atoms (C–Mg) in the cyclic and the acyclic compounds
respectively. Therefore the presence in the 13C NMR
spectrum of compound Ib of the signal at 190.16 ppm
and no signal in the region ~166 ppm may indicate that
for the nixture of compounds Ib and IIb the Schlenk
equilibrium is shifted to magnesacyclopentadiene Ib. To
prove this assumption we added to a mixture of com-
pounds Ib and IIb 1,4-dioxane which formed with
magnesium dihalide insoluble in ether complex [6] thus
shifting the Schlenk equilibrium to the cyclic compound
Ib [7]. On removing by centrifugation insoluble in ether
We believe that the formation of the cyclic structure
I originates from Zr-containing cyclic intermediates
arising under the reaction conditions in keeping with the
scheme assumed for the formation of magnesacycles
from α-olefins [8] and α,ω -diolefins [9].
We tried further to carry out intermolecular reaction
of acetylene and allene in equimolar amounts with
BuMgHlg (Hlg = Cl, Br) in the presence of catalyst
Cp2ZrCl2 in order to obtain alkylidenemagnesacyclo-
pentenes whose stucture contained potentially richer
synthetic opportunities than that of magnesacyclopenta-
dienes. Actually, the reaction of a mixture of 3-
hexyne and 1,2-octadiene with excess BuMgBr (acetyl-
ene–allene–BuMgBr, 1:1:2) in Et2O in the presence of
10 mol% Cp2ZrCl2 within 2 h led to the formation of
2,3-diethyl-5-hexylidenemagnesacyclopent-2-ene (Va) in
~45% yield (Scheme 2). In minor quantity (up to 10%)
formed 2,3,4,5-tetraethylmagnesacyclopentadiene (Ia).
Under the above conditions 4-octyne and 1,2-octadiene
or 4-octyne and 1-(1,2-propadienyl)benzene reacted with
excess BuMgHlg (Hlg = Cl, Br) giving the corresponding
alkyl(benzyl)idenemagnesacyclopentanes Vb and Vc in
45–50% yield.Alongside the latter minor amounts of the
corresponding 2,3,4,5-substituted magnesacyclopentadi-
enes Ia and Ib were isolated from the reaction mixture
in an yield not exceeding 15%.
.
magnesium dihalide dioxanate (MgBr2 2dio) the 13C NMR
spectrum of compound Ib contained only the downfield
signal of the carbon atom (C2–Mg) at 190.22 ppm; it also
supported the cyclic structure of compound Ib obtained
in Et2O. The replacement of the initial BuMgBr by
BuMgCl did not significantly influence the yield of the
target product, but in reaction carried out in THF the
yield of compound Ib did not exceed 15%.
Thus we first succeded to involve into the Cp2ZrCl2-
catalyzed reaction with BuMgHlg (Hlg = Cl, Br) acetyl-
enes and their equimolar mixture with allenes and to obtain
a new class of organomagnesium compounds: magnesa-
cyclopentadienes and 2-alkylidenemagnesacyclopentenes
possessing a wide synthetic potential, and also interesting
as new cocatalysts in the Ziegler–Natta systems and
Under the developed conditions (~20°C, 2 h, 10 mol%
of Cp2ZrCl2, Et2O) reactions of 3-hexyne, 5-decyne, and
1-hexynyltrimethylsilane with excess BuMgHlg (Hlg =
Cl, Br) led to the formation of the corresponding
magnesacyclopentadienes Ia, Ic, and Id in 45–50% yields.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 2 2007

178
DZHEMILEV et al.
promising organomagnesium reagents in organic and
organometallic syntheses.
b. Reaction in 1,4-dioxane−ether mixture. 13C NMR
spectrum, δ, ppm: 14.23 (C11,13), 14.88 (C7,9), 31.84
(C10,12), 32.33 (C6,8), 133.79 (C3,4), 191.07 (C2,5).
EXPERIMENTAL
4,5-Diethylocta-3,5-diene (IIIa), bp 89–91°C
(15 mm Hg.). IR spectrum, ν, cm–1: 3080, 2950, 2900,
Products of hydrolysis and of reaction with deuterium
oxide were analyzed on a chromatograph Chrom-5 in
a helium flow, column 1200× 3 mm, stationary phase 5%
SE-30 or 15% PEG-6000 on Chromaton N-AW. IR
spectra were recorded on a spectrophotometer 75IR from
films, mass spectra were obtained on MKh-1306
instrument at 200°C, ionizing electrons energy 70 eV.
1H and 13C NMR spectra were registered from solutions
in CDCl3 on a spectrometer JEOL FX-90 Q [89.55 (1H)
and 22.5 MHz (13C)]. The yields of organo-magnesium
compounds were determined based on GLC analysis of
their hydrolysis products. The reactions with
organomagnesium compounds were carried out in a dry
argon flow. Ethyl ether was distilled over LiAlH4 just
before use. A solution of BuMgHlg (Hlg = Cl, Br) in
Et2O was prepared by procedure from [10].
1
2850, 1640, 1450, 1370, 910, 895, 720. H NMR spectrum,
δ, ppm: 0.82–1.05 m (12H, CH3), 2.06–2.25 m (8H, =C–
CH2), 5.25–5.75 (2H, –HC=C–). 13C NMR spectrum,
δ, ppm: 13.77, 14.55 (C1,8), 20.93, 21.23 (C2,7), 126.50
(C3,6), 141.23 (C4,5). Found, %: C 86.27; H 13.06. [M]+
166. C12H22. Calculated, %: C 86.67; H 13.33.
5,6-Dipropyldeca-4,6-diene (IIIb). bp 95–97°C
(1 mm Hg). IR spectrum, ν, cm–1: 3000, 2950, 2850, 1640,
1
1420, 1380, 970, 810, 790, 720. H NMR spectrum, δ,
ppm: 0.85–1.23 m (12H, CH3), 1.33–1.75 m (8H, CH2),
1.96–2.35 m (8H, =C–CH2), 5.25-5.65 (2H, HC=C).
13C NMR spectrum, δ, ppm: 13.89, 14.61 (C1,10), 22.03,
23.27 (C2,9), 30.04, 30.30 (C3,8), 126.10 (C4,7), 141.41
(C5,6). Found, %: C 86.07; H 13.16. [M]+ 222. C16H30.
Calculated, %: C 86.40; H 13.60.
6,7-Dibutyldodeca-5,7-diene (IIIc). bp 137–139°C
(1 mm Hg). IR spectrum, ν, cm–1: 3000, 2950, 2900, 2820,
1640, 1450, 900, 730. 1H NMR spectrum, δ, ppm: 0.86–
1.12 m (12H, CH3), 1.23–1.79 m (16H, CH2), 1.98–
2.26 m (8H, =C–CH2), 5.25–5.85 (2H, HC=C).
13C NMR spectrum, δ, ppm: 13.76, 14.13 (C1,12), 22.56,
22.97 (C2,11), 27.83 (C3,10), 28.05 (C4,9), 31.13, 31.29,
125.86 (C5,8), 141.27 (C6,7). Found, %: C 85.95; H 13.17.
[M]+ 278. C20H38. Calculated, %: C 86.25; H 13.75.
Acetylene reaction with BuMgHlg (Hlg = Cl, Br)
catalyzed by Cp2ZrCl2. Into a glass reactor under
atmosphere of dry argon at ~ 0°C was charged while
stirring 1.0 mmol of Cp2ZrCl2, 10 mmol of acetylene, and
20 mmol of BuMgHlg (Hlg = Cl, Br) (2 M solution in
Et2O). The temperature was raised to ambient (20–22°C),
and the mixture was stirred for 2 h. In order to identify
the substituted magnesacyclopentadienes by the products
of reaction with deuterium oxide the reaction mixture was
treated with 8% DCl in D2O. The reaction products were
extracted with ether or hexane, the extracts were dried
over MgSO4, the target products were isolated by
fractional distillation. Compounds IVa–IVc were identified
by comparison with authentic samples [11, 12].
2,3-Dibutyl-1,3-butadiene-1,4-diylbistrimethyl-
enesilane (IIId). bp 108–110°C (1 mm Hg). IR spec-
trum, ν, cm–1: 3080, 2920, 2850, 2300, 1640, 1460, 910,
1
720. H NMR spectrum, δ, ppm: 0.30–0.42 [18H,
CSi(CH3)3], 0.85–0.95 m (6H, CH3), 1.1–1.5 m (8H,
CH2), 1.95–2.10 m (4H, =C–CH2), 5.52–5.83 m (2H,
C=CH). 13C NMR spectrum, δ, ppm: 0.28 (C13,14,15,16,17,18),
14.15 (C7,11), 23.21 (C6,10), 31.82 (C5,9), 33.93 (C4,8),
125.32 (C2,3), 161.08 (C1,12). Found, %: C 68.85; H 12.02.
[M]+ 310. C18H38Si2. Calculated, %: C 69.14; H 11.61.
2,3,4,5-Tetraethylmagnesacyclopenta-2,4-diene
(Ia). a. Reaction in ether solution. 13C NMR spectrum,
δ, ppm: 13.38 (C14,17), 14.16 (C8,11), 20.87 (C13,16), 22.76
(C7,10), 31.29 (C12,15), 32.04 (C6,9), 132.75 (C3,4), 190.16
(C2,5).
b. Reaction in 1,4-dioxane−ether mixture. 13C NMR
spectrum, δ, ppm: 13.41 (C14,17), 14.55 (C8,11), 21.00
(C13,16), 22.82 (C7,10), 30.89 (C12,15), 31.68 (C6,9), 132.75
(C3,4), 190.22 (C2,5).
2,3-Dibutyl-1,4-dideutero-1,3-butadiene-1,4-
diylbistrimethylenesilane (IVd). bp 108–110°C
(1 mm Hg). IR spectrum, ν, cm–1: 2170 (CD). 1H NMR
spectrum, δ, ppm: 0.32–0.41 [18H, CSi(CH3)3], 0.83–
0.96 m (6H, CH3), 1.11–1.53 m (8H, CH2), 1.96–2.15 m
(4H, =C–CH2). 13C NMR spectrum, δ, ppm:
0.24(C13,14,15,16,17,18), 14.06 (C7,11), 23.11 (C6,10), 31.72
(C5,9), 33.86 (C4,8), 125.60 (C2,3), 160.72 t (C1,12, JC,D
24.0 Hz). Found, %: C 68.85; (H+D) 12.02. [M]+ 312.
C18H36Si2D2. Calculated, %: C 69.14; H 11.61; D 1.29.
2,3,4,5-Tetrapropylmagnesacyclopenta-2,4-
diene. a. Reaction in ether solution. 13C NMR spectrum,
δ, ppm: 14.13 (C11,13), 14.26 (C7,9), 31.29 (C10,12), 32.07
(C6,8), 133.92 (C3,4), 191.10 (C2,5).
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FIRST SYNTHESIS OF MAGNESACYCLOPENTADIENES
179
1
Reaction of a mixture of acetylenes and allenes
with BuMgHlg (Hlg = Cl, Br) catalyzed by
Cp2ZrCl2. Into a glass reactor under atmosphere of dry
argon at ~ 0°C was charged while stirring 1.0 mmol of
Cp2ZrCl2, 10 mmol of acetylene, 10 mmol of allene, and
20 mmol of BuMgHlg (Hlg = Cl, Br) (2 M solution in
Et2O). The temperature was raised to ambient (20–22°C),
and the mixture was stirred for 2 h. In order to identify
the substituted alkylidenemagnesacyclopentenes by the
products of reaction with deuterium oxide the reaction
mixture was treated with 8% DCl in D2O. The reaction
products were extracted with ether or hexane, the extracts
were dried over MgSO4,the target products were isolated
by fractional distillation.
(CD). H NMR spectrum, δ, ppm: 0.88–0.91 m (9H,
CH3), 1.12–1.68 m (6H, CH2), 1.89–2.47 m (8H, =C–
CH2), 5.38–5.79 m (1H, C=CH). 13C NMR spectrum,
δ, ppm: 13.35, 14.05 (C12), 14.72 (C1), 20.26 (C2), 22.78
(C11), 23.56, 27.32 (C8), 29.74 (C9), 30.41 (C10), 36.54
(C5), (C3), (C6), 130.73 (C7), 132.87 (C4). [M]+ 196.
Found, %: C 85.31; (H+D) 14.02. C14H24D2. Calculated,
%: C 85.63; H 12.32; D 2.05.
*
*
4,7-Dideutero-5-propyl-4,7-tridecadiene (VIIIb).
bp 98–100°C (1 mm Hg). IR spectrum, cm-1: 2175 (CD).
1H NMR spectrum, δ, ppm: 0.91–1.17 m (9H, CH3), 1.23–
1.61 m (10H, CH2), 1.95–2.72 m (8H, =C–CH2), 5.49–
5.78 t (1H, C=CH). 13C NMR spectrum, δ, ppm: 13.79,
14.01 (C13), 14.46 (C1), 22.12, 22.84 (C12), 23.29 (C2),
27.31 (C9), 29.64 (C10), 30.09, 30.31 (C11), 30.52 (C3),
37.23 (C6), *(C4), *(C7), 130.38 (C8), 131.28 (C5). Found,
%: C 85.07; (H+D) 13.96. [M]+ 224. C16H28D2.
Calculated, %: C 85.63; H 12.58; D 1.79.
4-Ethyl-3,6-dodecadiene (VIIa). bp 102–104°C (5
mm Hg). IR spectrum, ν, cm–1: 3030, 2900, 2800, 1650,
1
1490, 1450, 1000, 910, 890, 720, 700. H NMR spectrum,
δ, ppm: 0.87–0.93 m (9H, CH3), 1.1–1.58 m (6H, CH2),
1.95–2.69 m (8H, =C–CH2), 5.45–5.82 m (3H, C=CH).
13C NMR spectrum, δ, ppm: 13.38, 14.02 (C12), 14.65
(C1), 20.19 (C2), 22.85 (C11), 23.78, 27.21 (C8), 29.69
(C9), 30.29 (C10), 36.34 (C5), 125.68 (C3), 128.15 (C6),
130.89 (C7), 131.77 (C4). [M]+ 194. Found, %: C 86.03;
H 12.99. C14H26. Βû ×θCλε-νO, %: C 86.52; H 13.48.
2,5-Dideutero-4-propyl-1-phenyl-1,4-octadiene
(VIIIc). bp 128–130°C (1 mm Hg).IR spectrum,
ν,cm–1: 2170 (CD). H NMR spectrum, δ, ppm: 0.90–
1
1.15 m (6H, CH3), 1.25–1.65 m (4H, CH2), 1.95–2.30 m
(4H, =C–CH2), 2.55–3.25 (2H, =CCH2C=), 6.80 s (1H,
DC=CHPh), 7.25–7.85 (5H, Ph). 13C NMR spectrum,
δ, ppm: 13.85, 14.08 (C8), 23.12, 25.65 (C7), 32.83 (C6),
35.72, 38.85 (C3), *(C5), 126.61, 127.32, 129.49, *(C2),
130.95 (C1), 136.86, 138.56 (C4). [M]+ 230. Found, %:
C 88.25; (H+D) 11.02. C17H22D2. Calculated, %: C 88.63;
H 9.63; D 1.74.
5-Propyl-4,7-tridecadiene (VIIb). bp 98–100°C (1
mm Hg). IR spectrum, ν, cm–1: 3035, 2950, 2860, 1640,
1
1470, 1450, 1390, 1000, 910, 890, 730. H NMR spectrum,
δ, ppm: 0.90–1.15 m (9H, CH3), 1.21–1.59 m (10H, CH2),
1.95–2.70 m (8H, =C–CH2), 5.55–5.85 m (3H, C=CH).
13C NMR spectrum, δ, ppm: 13.86, 14.05 (C13), 14.59
(C1), 22.08, 22.89 (C12), 23.31 (C2), 27.35 (C9), 29.76
(C10), 30.15, 30.28 (C11), 30.46 (C3), 37.15 (C6), 126.18
(C4), 129.15 (C7), 130.65 (C8), 131.18 (C5). [M]+ 222.
Found, % : C 85.92; H 13.12. C16H30. Calculated, % : C
86.40; H 13.60.
The authors are grateful to A.Z. Sharipova
(Laboratory of spectral methods of Institute of Petro-
chemistry and Catalysis, RussianAcademy of Sciences)
for helping to interprete the 13C NMR spectra of
magnesacyclopentadienes and alkylidenemagnesa-
cyclopentenes.
4-Propyl-1-phenyl-1,4-octadiene (VIIc). bp 128–
130°C (1 mm Hg). IR spectrum, ν, cm–1: 3030, 2940,
The study was carried out under a financial support
of the Russian Foundation for Basic Research (grants
nos. 05-03-32367, NSh – 7470.2006.3).
1
2860, 1650, 1490, 1450, 1395, 1050, 920, 870, 720. H
NMR spectrum, δ, ppm: 0.89–1.13 m (6H, CH3), 1.25–
1.68 m (4H, CH2), 1.95–2.29 m (4H, =C–CH2), 2.55–
3.15 (2H, =C–CH2–C=), 5.45–6.82 m (3H,
CH=CCH2HC=CHPh), 7.23–7.65 (5H, Ph). 13C NMR
spectrum, δ, ppm: 13.83, 14.03 (C8), 23.11, 25.55 (C7),
32.84 (C6), 35.68, 38.80 (C3), 125.84 (C5), 126.59, 127.47,
129.52, 129.98 (C2), 130.92 (C1), 136.84, 137.96 (C4).
[M]+ 228. Found, %: C 89.11; H 10.02. C17H24.
Calculated, %: C 89.41; H 10.59.
REFERENCES
1. Dzhemilev, U.M., Sultanov, R.M., Gaimaldinov, R.G., and
Muslukhov, R.R., Primenenie metallokompleksnogo
kataliza v organicheskom sinteze (Application Metallo-
complex Catalysis in Organic Chemistry), Ufa, 1989, p. 40.
2. Dzhemilev, U.M., D’yakonov, V.A., Khafizova, L.O., and
Ibragimov,A.G., Tetrahedron, 2004, vol. 60, p. 1287.
3. Dzhemilev, U.M. and Ibragimov, A.G. Usp. Khim., 2005,
vol. 74, p. 886.
3,6-Dideutero-4-ethyl-3,6-dodecadiene (VIIIa).
bp 102–104°C (5 mm Hg). IR spectrum, ν, cm–1: 2160
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 2 2007

180
DZHEMILEV et al.
4. Dzhemilev, U.M. and Ibragimov, A.G. Usp. Khim., 2000,
J. Am. Chem. Soc., 1994, vol. 116, p. 1845.
vol. 69, p. 134.
10. Ioffe, S.T. and Necmeyanov, A.N., Metody elemento-
organicheskoi khimii. Podgruppa magniya berilliya
kal’tsiya strontsiya bariya (Methods of Organoelemental
Chemistry. Magnium, Berrilium, Calcium, Strontium, Barium
Sub-Group), Moscow: Izd. Akad.Nauk SSSR, 1963, 561 p.
11. Dzhemilev, U.M., Ibragimov, A.G., Ramazanov, I.R., and
Khalilov, L.M., Izv. Akad. Nauk, Ser. Khim., 1997, p. 2269.
12. Dzhemilev, U.M., Ibragimov, A.G., Khafizova, L.O.,
Yakupova, L.R., and Khalilov, L.M., Zh. Org. Khim., 2005,
vol. 41, p. 684.
5. Dzhemilev, U.M., D’yakonov, V.A., Khafizova, L.O., and
Ibragimov,A.G., Zh. Org. Khim., 2005, vol. 41, p. 363.
6. Strohmeier, W. and Seifert, F., Chem. Ber., 1961, vol. 94,
p. 2356.
7. Denise, B., Favarque, J.-F., and Ducom, J., Tetrahedron
Lett., 1970, p. 335.
8. Lewis, D.P., Whitby, R.J., and Jones, R.V.H. , Tetrahedron,
1995, vol. 51, p. 4541.
9. Knight, K.S., Wang, D., Waymouth, R.M., and Ziller, J.,
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