Combined cycloalumination of cyclic 1,2-dienes and olefins with EtAlCl2 in the presence of Cp2ZrCl2 catalyst

Article abstract of DOI:10.1016/j.tetlet.2008.12.115

Catalytic intermolecular cycloalumination of cyclo-1,2-dienes and olefins assisted by EtAlCl₂ in the presence of Cp₂ZrCl₂ as catalyst gave rise to unsaturated di- and polycyclic aluminacarbocycles.

Full text of DOI:10.1016/j.tetlet.2008.12.115

Tetrahedron Letters 50 (2009) 1270–1272
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Tetrahedron Letters
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Combined cycloalumination of cyclic 1,2-dienes and olefins with EtAlCl2 in
the presence of Cp2ZrCl2 catalyst
*
Vladimir A. D’yakonov , Rustam K. Timerkhanov, Tatiana V. Tumkina, Natal’ya R. Popod’ko,
Askhat G. Ibragimov, Usein M. Dzhemilev
Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, 141 Prospekt Oktyabrya, Ufa 450075, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Catalytic intermolecular cycloalumination of cyclo-1,2-dienes and olefins assisted by EtAlCl2 in the pres-
ence of Cp2ZrCl2 as catalyst gave rise to unsaturated di- and polycyclic aluminacarbocycles.
Ó 2009 Elsevier Ltd. All rights reserved.
Received 23 September 2008
Revised 17 December 2008
Accepted 22 December 2008
Available online 9 January 2009
Dedicated to Professor John Birmingham on
the occasion of his 80th birthday
Keywords:
Cycloalumination
Olefins
Allenes
Zr complexes
Homogeneous catalysis
Organoaluminum compounds
Dzhemilev reaction
Recently,1 we reported the catalytic cycloalumination of cyclo-
1,2-dienes assisted by Et3Al and EtAlCl2–Mg in the presence of
Cp2ZrCl2 as catalyst to afford bi- and tricyclic organoaluminum
compounds (OACs) (Scheme 1).
In order to explore the possibility of combined cycloalumina-
tion and also to elaborate procedures for obtaining bi-, tri-, and tet-
racyclic OACs we have studied the reaction between 1,2-dienes
or cyclonona-1,2-diene under the chosen conditions, did not ex-
ceed 14%.
The structure of OAC 1a was confirmed by means of 1H, 13C and
Dept 135° NMR, and two-dimensional (HH COSY, HSQC, and
HMBC) experiments. In the NMR spectra, strong broadening of sig-
nals due to the quadruple relaxation of 27Al nuclei (I = 5/2) and due
to the presence of stereoisomers in solution was observed. Actu-
ally, OAC 1a corresponds to a complex with a molecule of tetrahy-
drofuran, in which the cycloalumination reaction was carried out.
The aluminum atom is connected to the solvent molecule, and is
tetracoordinated. Taking into account the two diastereomeric cen-
ters at C9 and C10, it is reasonable to expect an increase in the
number of diastereoisomers. Therefore, we have studied in detail
the NMR (1H and 13C) spectra of compounds 4a and 5a obtained
after acid hydrolysis and deuterolysis of 1a.
(cyclonona-1,2-diene and cyclotrideca-1,2-diene) and olefins (
olefins, norbornene) using Cp2ZrCl2 as catalyst, which is highly
selective and efficient in these reactions.2
-Olefins such as hex-
a-
a
1-ene, hept-1-ene, dec-1-ene, styrene, and allyl benzene were se-
lected for investigation.
Based on a model cycloalumination reaction of cyclonona-1,2-
diene with hex-1-ene (1:1.2 ratio), it was found that slow dropwise
addition of cyclonona-1,2-diene (10 mmol in 15 ml THF) into the
reaction mixture containing hex-1-ene (12 mmol), EtAlCl2
(24 mmol), Mg (powder, 36 mmol), and Cp2ZrCl2 (1.1 mmol in
15 ml THF) under an argon atmosphere for 3 h led to OAC 1a in
71% yield (Scheme 2).3
Compounds 4a and 5a were analyzed by 1D and 2D NMR exper-
iments. Mass spectra of these compounds were also recorded. Eval-
uation of the signals in the 1H and 13C NMR spectra allows
unambiguous assignment of the structures. Thus, the position of
the alkyl chain substituent in compound 4a was confirmed by
the presence of cross-peaks between the proton H(C1) (d 5.51)
and the quaternary C3 carbon atom in the HMBC spectrum. The
double bond Z-configuration at the C2 carbon atoms was deter-
mined unambiguously by the magnitude of the vicinal spin–spin
Together with OAC 1a, the total yield of symmetrical products
2a4 and 3a,1 resulting from homocycloalumination of hex-1-ene
* Corresponding author. Tel./fax: +7 347 2842750.
E-mail addresses: Ink@anrb.ru, DyakonovVA@rambler.ru (V.A. D’yakonov).
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2008.12.115

V. A. D’yakonov et al. / Tetrahedron Letters 50 (2009) 1270–1272
1271
[Zr], Mg
EtAlCl2
> 70%
[Zr]
Et3Al
> 85%
( )n
( )n
( )n
( )n
Al
Et
Al
Et
Scheme 1.
4
R
R
R
3
( )n
( )n
( )n
+
+
2
1
X
X
X
X
X X
8a,b (X= H)
6a-e (X= H)
7a-e (X =D)
4a-f (X= H)
5a-f (X =D)
9a,b (X =D)
H3O+ (D3O+)
R
R
R
R
( )n
( )n
( )n
( )n
( )n
+
+
1
[Zr], Mg
EtAlCl2
2
Al
Et
Al
Et
Al
Et
1a-f
2a-e
3a,b
3a,b
( )n
( )n
( )n
+
+
[Zr], Mg
EtAlCl2
Al
Et
Al
Et
Al
Et
10a,b
11
H3O+ (D3O+)
( )n
( )n
+
+
X
X
X X
X
X
8a,b (X= H)
12a,b (X=H)
14 (X=H)
15 (X=D)
9a,b (X =D)
13a,b (X=D)
Scheme 2.
interaction constant (SSIC), 3J (H(C1), H(C2)) = 10 Hz.5 The location
of the deuteriums at C2 and C15 in partially deuterized compound
5a was confirmed by the absence of a proton signal at 5.23 ppm in
the 1H NMR spectrum, and also by the triplet splitting for the C2
and C15 carbon signals at d 132.9 (1JCD = 23 Hz) and d 16.3
(1JCD = 19 Hz), respectively.
(C17 and H11) indicated formation of a cyclic aluminum-containing
moiety. The 27Al NMR spectrum exhibited a signal at d 135, which
corresponds to the area of tetracoordinated aluminum atoms.
Thus, we have identified compounds 1a, 4a, and 5a as 12-ethyl-
10-n-butyl-12-aluminabicyclo[7.3.01,9]dodec-1(2)-ene, 3-(1-meth-
ylpentyl)cyclonon-1-ene, and 2-deutero-3-(1-deuteromethylpen-
tyl)cyclonon-1-ene, respectively.
Together with hex-1-ene, unsaturated compounds such as
hept-1-ene, dec-1-ene, styrene, allyl benzene, and norbornene
have been used in the combined cycloalumination reaction with
cyclonona-1,2-diene. These reactions were shown to proceed anal-
ogously to those described above. In each experiment, together
with the target aluminacyclopentanes 1b–e and 3a, the products
A comparison between the 13C NMR spectra of the OAC 1a and
the hydrocarbon 4a shows that the chemical shifts of the carbon
atoms in the cyclononene unit C3ÀC8 and the C13ÀC16 alkyl chain
have insignificant variations. The signals of the double bond carbon
atoms are shifted down field. This is particularly manifested by the
C1 carbon atom, the resonance of which is observed at d 177.5
(176.5). The C11, C15, and C17 carbon atoms also exhibit two sig-
nals per carbon atom (1:2 line intensity ratio), possibly due to dia-
stereomers. The 13C NMR spectrum of OAC 1a also demonstrates
the expected bands at d 10.1 and d 1.6 (1.2), which are attributable
to the ethyl group bound to the aluminum atom. The cyclopentane
ring C11 carbon atom adjacent to Al resonated at d 9.5 and d 10.0.
In spite of the proximity of the chemical shifts belonging to the
adjacent C11 and C17 carbon atoms, it was possible to identify them
unambiguously from the HSQC and HMBC experiments, since the
chemical shifts of the corresponding protons differed from each
other. Cross-peaks in the HMBC spectrum between C11 and H17
of homocycloalumination of a-olefins 2b–e or norbornene 11 and
cyclonona-1,2-diene 3a were observed, the total amount of which
varied in the range of 10À15%, and were identified from the prod-
ucts of hydrolysis 6b–e, 8a, and 14 and deuterolysis 7b–e, 9a, and
15. The structure of all the OACs was proved by spectral methods,
and also by comparison with known samples.4,6
Similar to cyclonona-1,2-diene, cyclotrideca-1,2-diene was
found to participate in the combined cycloalumination reaction
with
a-olefins or norbornene in the presence of EtAlCl2 and
Cp2ZrCl2 to afford the corresponding OACs 1f and 10b in yields of

1272
V. A. D’yakonov et al. / Tetrahedron Letters 50 (2009) 1270–1272
Table 1
Combined cycloalumination of cyclic 1,2-dienes and olefins
Entry
Cyclic 1,2-diene
Olefin
Yields of aluminacyclopentanes 1–3, 10 and 11a (%)
Total yield (%)
1
2
3
4
5
6
7
8
Cyclonona-1,2-diene
Cyclonona-1,2-diene
Cyclonona-1,2-diene
Cyclonona-1,2-diene
Cyclonona-1,2-diene
Cyclonona-1,2-diene
Cyclotrideca-1,2-diene
Cyclotrideca-1,2-diene
Hex-1-ene
Hept-1-ene
Dec-1-ene
Styrene
Allyl benzene
Norbornene
Hex-1-ene
Norbornene
71 (1a)
68 (1b)
63 (1c)
65 (1d)
62 (1e)
67 (3a)
58 (1f)
60 (3b)
11 (2a)
9 (2b)
7 (2c)
11 (2d)
8 (2e)
10 (11)
13 (2a)
12 (11)
3 (3a)
4 (3a)
6 (3a)
4 (3a)
5 (3a)
4 (3a)
1 (3b)
1 (3b)
85
81
76
80
75
81
72
73
a
Determined by GLC of the acid hydrolysis products.
3. Reaction between cyclic 1,2-dienes and olefins in the presence of EtAlCl2 and
Cp2ZrCl2: A glass reactor under a dry argon atmosphere at ambient temperature
was charged under stirring with 10 ml of THF, Mg (36 mmol), Cp2ZrCl2
(1.1 mmol), olefin (12 mmol), and EtAlCl2 (24 mmol). A solution of cyclic 1,2-
diene (10 mmol) in 10 ml of THF was then added dropwise over 3 h. The mixture
was stirred for an additional 2 h. The reaction mixture (crude 1a–f or 10a,b) was
quenched with an 8–10% aqueous solution of HCl (or DCl, 10–12% solution in
D2O). The organic layer was diluted with hexane, separated, and dried over
MgSO4. Evaporation and vacuum distillation furnished the target products 4a–f,
12a,b or 5a–f, 13a,b. 12-Ethyl-10-n-butyl-12-aluminabicyclo[7.3.01,9]dodec-
1(2)-ene (1a): 1H NMR (400 MHz, C7D8): d 5.13 (br s, 1H), 1.0À1.92 (br m,
22H), 0.8À1.0 (br m, 3H), 0.4À0.75 (br m, 3H), À0.4À0.2 (m, 4H); 13C NMR
(100 MHz, C7D8): d 177.5 (176.5), 130.8, 44.5, 42.0, 36.1, 32.6, 30.7, 27.5, 26.8,
26.1, 26.0, 24.5, 23.6, 14.9, 10.1, 10.0 (9.5), 1.6 (1.2). 27Al NMR (104.28 MHz,
C7D8): 135 ppm. 3-(1-Methylpentyl)cyclonon-1-ene (4a): bp 133–135 °C
(10 Torr). 1H NMR (400 MHz, CDCl3): d 5.51 (m, 1H), 5.23 (m, 1H), 2.37 (m,
1H), 2.19 (m, 1H), 2.08 (m, 1H), 1.15–1.65 (m, 17H), 0.89 (t, J = 7 Hz, 3H), 0.81 (d,
J = 7 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 133.3, 129.3, 41.1, 38.4, 34.9, 31.8,
29.7, 26.8, 26.5, 26.3, 26.0, 25.3, 23.3, 16.6, 14.4. MS, m/z: 208 (M+). Anal. Calcd
for C15H28: C, 86.46; H, 13.54. Found: C, 86.31; H, 13.55%. 2-Deutero-3-(1-
deuteromethylpentyl)cyclonon-1-ene (5a): bp 133–135 °C (10 Torr). 1H NMR
(400 MHz, CDCl3): d 5.51 (t, J = 8 Hz, 1H), 2.36 (m, 1H), 2.18 (m, 1H), 2.07 (m,
1H), 1.14–1.66 (m, 17H), 0.86 (t, J = 7 Hz, 3H), 0.79 (d, J = 7 Hz, 2H); 13C NMR
(100 MHz, CDCl3): d 132.9 (t, JCD = 23 Hz), 129.2, 40.9, 38.3, 35.1, 32.5, 31.7, 27.1,
26.4, 26.3, 26.0, 25.3, 22.9, 16.3 (t, JCD = 19 Hz), 14.3. MS, m/z: 210 (M+). Anal.
Calcd for C15H26D2: C, 85.63; H, 12.46; D, 1.91. Found: C, 85.49; H + D, 14.36.
4. (a) Dzhemilev, U. M.; Ibragimov, A. G.; Morozov, A. B.; Muslukhov, R. R.;
Tolstikov, G. A. Bull. Russ. Acad. Sci., Div. Chem. Sci. 1992, 41, 1089–1093; (b)
Muslukhov, R. R.; Khalilov, L. M.; Zolotarev, A. P.; Morozov, A. B.; Ibragimov, A.
G.; Dzhemilev, U. M.; Tolstikov, G. A. Bull. Russ. Acad. Sci., Div. Chem. Sci. 1992, 41,
1646–1652.
58% and 60%, together with homocycloalumination products 2a,
11, and cyclotrideca-1,2-diene 3b (Table 1). The mixtures of hydro-
lysis products were extracted with hexane and purified by distilla-
tion in vacuo. All the products were isolated in 95À98% purity.
In conclusion, we have described for the first time the Cp2ZrCl2
catalyzed combined cycloalumination of cyclic allenes with olefins
(or norbornene) assisted by EtAlCl2. As a result, unsaturated bi- and
polycyclic OACs were obtained in high yields with high selectivity.
We envisage that these OACs can be used for the synthesis of car-
bocyclic,2c,7 heterocyclic,8 and bifunctional1,2b,9 compounds.
Acknowledgments
This work was financially supported by the Russian Foundation
for Basic Research (Grant No. 08-03-00789), by Grants of the RF
President (MC-1039.2007.3 and Sci.Sh.-2349.2008.3), and by the
Russian Science Support Foundation.
Supplementary data
Supplementary data (Spectral data for compounds 4bÀf, 5bÀf,
12a,b, and 13a,b) associated with this article can be found, in the
online version, at doi:10.1016/j.tetlet.2008.12.115.
5. Gordon, A. J.; Ford, R. A. In The Chemist’s Companion; J. Wiley and Sons: New
York–London–Sydney–Toronto, 1972. pp. 300–302.
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