Lithium Aluminate Complexes and Alumoles from 1,4-Dilithio-1,3-Butadienes and AlEt2Cl

Article abstract of DOI:10.1021/acs.inorgchem.5b01551

A series of lithium aluminate complexes and alumoles were synthesized from 1,4-dilithio-1,3-butadienes 1 and AlEt₂Cl. Their structures were characterized using single-crystal X-ray structural analysis and NMR spectroscopy. The structure of the lithium aluminate complex 2-TMEDA showed that the Al atom adopted a tetra-coordinated mode bonded with two butadienyl C_sp2 atoms and two ethyl C_sp3 atoms. The lithium cation was located above the alumole ring. The structure of 3a revealed a dimeric 1-ethylalumole in the solid state. Diffusion ordered spectroscopy NMR spectra showed that 3a was also a dimer in C₆D₆ solvent. However, in tetrahydrofuran (THF) solution, the dimeric 3a dissociated into the 1-ethylalumole-THF adduct. The lithium aluminate complex 2 transformed into 3a-THF when treated with 1.0 equiv of AlEt₂Cl. Preliminary reaction chemistry and synthetic applications of the lithium aluminate complex were also investigated.

Full text of DOI:10.1021/acs.inorgchem.5b01551

Article
pubs.acs.org/IC
Lithium Aluminate Complexes and Alumoles from 1,4-Dilithio-1,3-
Butadienes and AlEt2Cl
Yongliang Zhang,† Junnian Wei,† Wen-Xiong Zhang,† and Zhenfeng Xi*,†,‡
†Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering
of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
‡State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry (SIOC), Chinese Academy of Sciences,
Shanghai 200032, China
S
* Supporting Information
ABSTRACT: A series of lithium aluminate complexes and alumoles were synthesized
from 1,4-dilithio-1,3-butadienes 1 and AlEt2Cl. Their structures were characterized
using single-crystal X-ray structural analysis and NMR spectroscopy. The structure of
the lithium aluminate complex 2-TMEDA showed that the Al atom adopted a tetra-
coordinated mode bonded with two butadienyl Csp2 atoms and two ethyl Csp3 atoms.
The lithium cation was located above the alumole ring. The structure of 3a revealed a
dimeric 1-ethylalumole in the solid state. Diffusion ordered spectroscopy NMR spectra
showed that 3a was also a dimer in C6D6 solvent. However, in tetrahydrofuran (THF)
solution, the dimeric 3a dissociated into the 1-ethylalumole−THF adduct. The lithium
aluminate complex 2 transformed into 3a-THF when treated with 1.0 equiv of AlEt2Cl.
Preliminary reaction chemistry and synthetic applications of the lithium aluminate
complex were also investigated.
Preliminary reaction chemistry and synthetic applications of the
lithium aluminate complex 2 and 1-ethylalumole 3a were also
investigated.
INTRODUCTION
■
Organoaluminum chemistry is an important research field in
organometallic chemistry.1 Organoaluminum reagents are
widely used as homogeneous polymerization catalysis,2 Lewis
acid reagents,3 and organic synthons.4 Among all these
compounds, aluminum ate complexes, especially the alkali
metal aluminum ate complexes, have been widely used as
metalation reagents. Because of their mixed-metal synergistic
effect, these aluminum ate complexes can display special
regioselectivity and excellent functional group tolerance.5,6
Aluminacyclopentadienes (alumole) are also useful organo-
metallic compounds.7 They are proposed as intermediates in
organoaluminum-mediated reactions.8 Recently, Tokitoh and
co-workers reported the formation and crystal structure of the
Lewis-base free alumole9 and its analogues such as 1-
bromoalumole10 and 1-aminoalumole.11 However, due to the
limitation of synthetic methods, the synthesis of alumoles is still
challenging.
We have been interested in the synthetic applications of
multiply substituted 1,4-dilithio-1,3-butadienes 1 (dilithio
reagents for short).12 By transmetalation of dilithio reagents,
various novel organometallic compounds could be obtained
and characterized, such as organocopper(I) aggregates,13 heavy
alkaline earth complexes,14 dimagnesiabutadiene compounds,15
and lutetacyclopentadienes.16
RESULTS AND DISCUSSION
■
Synthesis and Structures of Lithium Aluminate
Complexes. Treatment of dilithio reagent 1a with 1.0 equiv
of AlEt2Cl in benzene at room temperature for 3 h afforded the
lithium aluminate complex 2 as white solids in 90% isolated
yield (Scheme 1). The compound 2, soluble in benzene,
toluene, and many polar solvents, was characterized by NMR
spectroscopy in THF-d8 (see Supporting Information for
details). Its 13C NMR spectrum showed that the chemical
shift of the sp2 carbons in alumole ring were 129.1 ppm (C1,
C4) and 160.4 ppm (C2, C3), respectively. When 1.0 equiv of
tetramethylethylenediamine (TMEDA) was added into the
Scheme 1. Synthesis of Lithium Aluminate Complex 2 and
Its TMEDA-Coordinated Complex 2-TMEDA
Herein, we report the synthesis and crystal structures of the
lithium aluminate complex 2 and 1-ethylalumoles 3 through the
reaction of dilithio reagents 1 with AlEt2Cl. Structural
transformations between the compounds 1a, 2, and 3a-THF
(THF = tetrahydrofuran) were observed by in situ NMR.
Received: July 16, 2015
© XXXX American Chemical Society
A
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benzene solution of 2, the corresponding TMEDA-coordinated
complex 2-TMEDA was quantitatively obtained (detected by in
situ NMR, see Supporting Information for details), which was
stable under inert atmosphere.
Single crystals of the complex 2-TMEDA suitable for X-ray
diffraction was obtained via recrystallization from hexane at
room temperature. The structure of the complex 2-TMEDA
demonstrated that the Al atom adopted a tetracoordinated
mode bonded with two Csp2 atoms and two ethyl Csp3 atoms
(Figure 1). The TMEDA-coordinated lithium cation was
Single crystals of compound 3a suitable for X-ray diffraction
were obtained via recrystallization from hexane at room
temperature as colorless crystals. Single-crystal X-ray structural
analysis revealed that 3a exists as a dimeric structure (Figure 2).
The dimeric form was similar to that of the 1-bromoalumole
reported by Tokitoh and co-workers.10a The whole molecule of
3a was disordered (see Supporting Information for details).
Figure 2. Diamond drawing of 3a with 30% probability thermal
ellipsoids. Hydrogen atoms are omitted for clarity. The whole
molecule of 3a was disordered. The major part was shown above.
Selected bond lengths (Å) and angles (deg): Al1−C1 1.975(3), Al1−
C4 2.082(6), C1−C2 1.345(5), C2−C3 1.500(5), C3−C4 1.401(7),
Al1−C9 2.264, Al2−Al1 2.5603(12), Al2−C4 2.124(3), Al2−C9
2.033(2), C9−C10 1.356(3), C10−C10′ 1.503(4). C1−Al1−C4
91.3(2), C2−C1−Al1 106.4(2), C1−C2−C3 118.5(3), C4−C3−C2
122.1(3), C3−C4−Al1 98.7(2), C1−Al1−Al2 102.24(11), C4−Al1−
Al2 53.26(10), C9−Al2−C91 90.26(12), C10−C9−Al2 103.27(14),
C9−C10−C10′ 120.56(12).
Figure 1. Diamond drawing of 2-TMEDA with 30% probability
thermal ellipsoids. Hydrogen atoms are omitted for clarity. Selected
bond lengths (Å) and angles (deg): C1−C2 1.358(4), C2−C3
1.529(4), C3−C4 1.355(4), Al1−C1 2.029(3), Al1−C4 2.034(3),
C1−Li1 2.343(6), C2−Li1 2.354(6), C3−Li1 2.372(6), C4−Li1
2.375(6); C1−Al1−C4 87.23(13), C2−C1−Al1 104.7(2), C1−C2−
C3 118.1(3), C4−C3−C2 118.0(3), C3−C4−Al1 104.8(2).
The NMR spectra of 1-ethylalumole 3a were analyzed
(Figure 3, see Supporting Information for details). The H
1
located above the alumole ring. The dihedral angle (25.086°)
between the plane formed by C1, C2, C3, and C4 and that
formed by C1, C4, and Al1 in 2-TMEDA indicated that the
alumole ring was not coplanar. The dihedral angle was much
larger than that in lithium 1,1-diaminoalumoluide (1.642°)
reported by Tokitoh and co-workers,11 probably because of the
steric effect of the TMEDA-coordinated lithium cation. The
butadiene moiety of the alumole ring exhibited clear bond
alternation, which was similar to the structure of the lithium
1,1-diaminoalumoluide.11 The angle of C1−Al−C4 is
87.23(13), which is smaller than the classic C−Al−C angles
in usual tetracoordinated aluminum compounds [e.g., Al2Me6:
C−Al−C, 104.3(1)−123.2(1) Å17].
Synthesis and Structures of 1-Ethylalumoles. We
recently reported the synthesis of 1,4-dimagnesia-1,3-buta-
dienes.15 These dimagnesia compounds were afforded by the
reaction of dilithio reagents with 2.0 equiv of isopropylmagne-
sium chloride. With the aim of forming 1,4-dialumina-1,3-
butadienes, we treated dilithio reagent 1a with 2.0 equiv of
AlEt2Cl in hexane/Et2O (3/1) at room temperature for 3 h.
However, instead of the target compounds, 1-ethylalumole 3a
was afforded in 70% isolated yield (Scheme 2). In a similar
procedure, compounds 3b and 3c could be prepared.
1
Figure 3. H NMR Spectra of 1-ethyloalumole 3a in C6D6 and THF-
d8.
NMR spectra of 3a could be considered as similar to that of the
1-bromoalumole at −60 °C reported by Tokitoh and co-
workers,9 indicating that the dimeric form of 3a was retained in
C6D6. However, in THF, dissociation of the dimer afforded a
1
different H NMR spectra. Variable temperature NMR spectra
of 3a have been conducted (see Supporting Information for
details). The H NMR spectra showed hardly no difference at
Scheme 2. Synthesis of 1-Ethylalumoles
1
−50, 30, and 90 °C, indicating that the dimeric form could be
kept in a wide range of temperatures. The effect of ethyl group
(our case) and Br atom (Tokitoh’s case) toward the stability
was different. Besides, the TMS groups may also enhance the
stability of 3a. To further confirm this dimeric form, diffusion
ordered spectroscopy (DOSY) NMR experiments were carried
B
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out. DOSY has been used as an efficient method to estimate the
degree of aggregation and molecular weight of compounds by
measuring the diffusion coefficient, D.18 A DOSY NMR
spectrum (see Supporting Information for details) confirmed
that 3a existed in C6D6 as a dimer, giving a calculated estimated
molecular weight of 578, which is about 3% error from the
theoretical value [Mw of alumole dimer = 561].
Scheme 4. Structural Transformations Between 1a, 2, and 3a
as Detected by NMR Spectroscopy
Addition of excess amount of THF to the C6D6 solution of 3
at room temperature quantitatively afforded 1-ethylalumole-
THF adduct 3-THF (Scheme 3). The corresponding NMR
spectra proved these results.
a
Scheme 3. Synthesis of 1-Ethylalumole-THF Adducts
dialkylaluminum chloride. Thus, we treated 2 with 1.0 equiv of
AlEt2Cl in THF-d8. Results showed that 2 transformed into 3a
completely with the concomitant loss of AlEt3. Dialumina
compound 4 was assumed to be the intermediate in this
progress. When reacted with excess EtLi in THF-d8, 3a
transformed into 2.
a
1
Yields were Determined by H NMR Spectroscopy.
Single crystals of compound 3c-THF suitable for X-ray
diffraction were obtained via recrystallization from hexane/
THF (10/1) at room temperature as colorless crystals. The
single-crystal X-ray structure analysis revealed a coplanar AlC4
ring skeleton by the sum of the internal bond angles of 540°
and the dihedral angle of 0.387° between the plane formed by
C1, C2, C3, and C4 and that formed by C1, C4, and Al1
(Figure 4). The lengths of the two Al−C bonds are 1.985(2) Å
Preliminary reactivity of lithium aluminate complex 2 and 1-
ethylalumole 3 were also investigated (Scheme 5). Lithium
Scheme 5. Reaction Chemistry of 2 and 3a
Figure 4. Diamond drawing of 3c-THF with 30% probability thermal
ellipsoids. Hydrogen atoms are omitted for clarity. Selected bond
lengths (Å) and angles (deg): Al1−C1 1.985(2), Al1−C4 1.986(2),
C1−C2 1.347(3), C2−C3 1.523(3), C3−C4 1.359(3); C1−Al1−C4
91.91(10), C2−C1−Al1 104.74(17), C1−C2−C3 119.6(2), C4−C3−
C2 119.3(2), C3−C4−Al1 104.40(16).
aluminate complex 2 reacted with dimethyl acetylenedicarbox-
ylate (DMAD) to give the hexa-substituted benzene 5 in 54%
isolated yield. Treatment of 2 with excess sulfur afforded the
corresponding thiophene compound 6 in 85% isolated yield.
However, the corresponding reactions of 1-ethylalumole 3a
either afforded a much lower yield of products or no products
at all under the same condition. 3a could not react with S8 in
THF. The reaction of 3a and 1.2 equiv of DMAD in THF
afforded the corresponding hexa-substituted benzene 5 in 44%
yield.
and 1.986(2) Å, respectively, which were comparable with the
classic Al−C bonds [e.g., Al2Me6: Al−C, 1.949(2)−2.606(2)
Å17]. The Lewis-base free alumole reported by Tokitoh and co-
workers was stable because of the protection of the bulky Mes*
group.9 In the structure of 3c-THF, the TMS group may
enhance the stability of 3c-THF due to the α-anion-stabilizing
effect of silicon.19
Structural Transformations. Transformation between
compounds 1a, 2, and 3a were investigated by in situ NMR
(Scheme 4). When 1.0 equiv of AlEt2Cl was reacted with 1a in
C6D6, the reaction afforded 2 as the sole product. When 2.0
equiv of AlEt2Cl was used, 3a could be observed as the major
product in THF-d8. According to the literature reports,20 alkali
metal tetraorgano aluminates could be converted into
trialkylaluminum compounds when treated with 1.0 equiv of
According to the work of Tokitoh and co-workers,10b we
proposed the following reaction mechanism (Scheme 6). In this
reaction, DMAD would insert into an Al−C bond of 2 to afford
the alumacycloheptatriene 7, which would then undergo
reductive elimination to generate the final product 5. A similar
reaction mechanism would be considered for the reaction
between 2 and S8.
C
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pressure, and the residue was dissolved in hexane. The filtrate was
reduced under a vacuum, and the residue was resolved with hexane
and stored at room temperature to afford 3 as a colorless solid.
Scheme 6. Proposed Reaction Mechanism from 2 to 5
1
3a, colorless solid, isolated yield 75% (169 mg). H NMR (400
MHz, C6D6) δ: 0.18 (s, 18H, CH3), 0.38 (s, 18H, CH2), 0.52 (q, J =
8.3 Hz, 4H, CH2), 1.04 (t, J = 8.2 Hz, 6H, CH3), 1.98 (s, 6H, CH3),
2.19 (s, 6H, CH3). 13C NMR (100 MHz, C6D6) δ: 0.9 (6 CH3), 3.2 (2
CH2), 3.6 (6 CH3), 10.9 (2 CH3), 23.6 (2 CH3), 29.3 (2 CH3), 126.9
(2 quat. C), 164.3 (2 quat. C), 174.1 (2 quat. C), 205.2 (2 quat. C).
IR: 3026 (w), 2993 (m), 2949 (m), 2898 (w), 2863 (w), 2799 (w),
1526 (w), 1543 (m), 1432 (m), 1246 (s), 1216 (w), 1104 (m), 1012
(m), 976 (w), 895 (m), 836 (s), 787 (m), 752 (m) cm−1.
CONCLUSION
■
1
In summary, we have synthesized and structurally characterized
several lithium aluminate complexes and alumoles. The
structures were determined by NMR spectra and single-crystal
X-ray structural analysis. 1-Ethylalumoles 3 exists as a dimer in
the crystalline state. DOSY NMR spectra of 3a in C6D6
confirmed this dimeric structure. Addition of an excess amount
of THF to the solution of 3 afforded 1-ethylalumole-THF
adduct 3-THF. Structural transformations between compounds
1a, 2, and 3a were investigated by in situ NMR. Preliminary
reaction chemistry and synthetic applications of 2 and 3a were
investigated.
3b, colorless solid, isolated yield 80% (196 mg). H NMR (400
MHz, C6D6) δ: 0.22 (s, 18H, CH3), 0.40 (s, 18H, CH2), 0.53 (q, J =
8.2 Hz, 4H, CH2), 1.05 (t, J = 8.2 Hz, 6H, CH3), 1.38−1.45 (m, 4H,
CH2), 1.56−1.68 (m, 4H, CH2), 2.39−2.47 (m, 2H, CH2), 2.58−2.69
(m, 4H, CH2), 2.77−2.84 (m, 4H, CH2). 13C NMR (100 MHz, C6D6)
δ: 1.5 (6 CH3), 3.3 (2 CH2), 3.7 (6 CH3), 11.0 (2 CH3), 22.3 (2
CH2), 22.3 (2 CH2), 34.2 (2 CH2), 39.8 (2 CH2), 124.9 (2 quat. C),
167.0 (2 quat. C), 172.4 (2 quat. C), 206.8 (2 quat. C). IR: 2941 (s),
2895 (m), 2864 (m), 1527 (w), 1456 (m), 1246 (s), 1100 (m), 953
(s), 838 (s), 771 (m) cm−1. Anal. Calcd (%) for 3b: C, 62.68; H,
10.19. Found: C, 61.76; H, 9.92.
3a-THF. 1H NMR (400 MHz, THF-d8) δ: 0.00 (q, J = 8.1 Hz, 2H,
CH2), 0.05 (s, 18H, CH3), 0.98 (t, J = 8.0 Hz, 3H, CH3), 2.10 (s, 6H,
CH3). 13C NMR (100 MHz, THF-d8) δ: 0.9 (1 CH2), 1.9 (6 CH3), 9.4
(1 CH3), 24.2 (2 CH3), 146.5 (2 quat. C), 168.0 (2 quat. C).
3b-THF. 1H NMR (400 MHz, THF-d8) δ: 0.01 (q, J = 8.2 Hz, 2H,
CH2), 0.05 (s, 18H, CH3), 1.00 (t, J = 8.2 Hz, 3H, CH3), 1.61 (m, 4H,
CH2), 2.58 (m, 4H, CH2). 13C NMR (100 MHz, THF-d8) δ: 1.0 (1
CH2), 2.0 (6 CH3), 9.5 (1 CH3), 24.9 (2 CH2), 35.9 (2 CH2), 144.4
(2 quat. C), 170.1 (2 quat. C).
EXPERIMENTAL SECTION
■
General Procedures. All reactions were carried out under a
slightly positive pressure of dry and oxygen-free argon by using
standard Schlenk line techniques or under an argon atmosphere in a
Mikrouna Super (1220/750) Glovebox. The argon in the glovebox
was constantly circulated through a copper/molecular sieves catalyst
unit. The oxygen and moisture concentrations in the glovebox
atmosphere were monitored by an O2/H2O Combi-Analyzer to ensure
both were always below 1 ppm. Unless otherwise noted, all starting
materials were commercially available and were used without further
purification. Solvents were purified by an Mbraun SPS-800 Solvent
1
3c-THF, colorless solid, isolated yield 36% (679 mg). H NMR
(400 MHz, C6D6) δ: 0.06 (s, 18H, CH3), 0.40 (q, J = 8.0 Hz, 2H,
CH2), 1.12−1.18 (m, 4H, CH2), 1.50 (t, J = 8.0 Hz, 3H, CH3), 3.60−
3.66 (m, 4H, CH2), 6.84−6.90 (m, 2H, CH), 6.94−7.04 (m, 8H, CH).
13C NMR (100 MHz, C6D6) δ: 1.0 (1 CH2), 1.8 (6 CH3), 9.6 (1
CH3), 25.2 (2 CH2), 70.9 (2 CH2), 125.4 (2 quat. C), 127.2 (4 CH),
129.1 (4 CH), 147.8 (2 quat. C), 150.6 (2 quat. C), 172.1 (2 quat. C).
IR: 3058 (w), 3014 (w), 2947 (m), 2891 (m), 1594 (w), 1528 (m),
1462 (w), 1237 (m), 1068 (m), 993 (w), 917 (m), 838 (s), 767 (m)
cm−1. Anal. Calcd (%) for 3c-THF: C, 70.54; H, 8.67. Found: C,
69.64; H, 8.64.
A Typical Procedure for the Reaction of 2. Under an
atmosphere of nitrogen, compound 2 (95 mg, 0.3 mmol) and Et2O
(5 mL) was added into 25 mL Schlenk tube. Then 1.2 equiv of DMAD
(51 mg, 0.36 mmol) or 0.5 equiv of S8 (38 mg, 0.15 mmol) was added.
The reaction mixture was stirred at room temperature for 2 h and
workup; the residue was purified by column chromatography to give
products 5 and 6. Compounds 521 and 622 are known compounds,
whose NMR spectra are consistent with literature reports.
X-ray Crystallographic Studies. Single crystals of 2-TMEDA and
3a suitable for X-ray analysis were grown in hexane at room
temperature for about 2 days. Single crystals of 3c-THF suitable for X-
ray analysis were grown in hexane/THF (10/1) at room temperature
for about 2 days. Data collections for 2-TMEDA, 3a, and 3c-THF
were performed at 180 K on a Rigaku RAXIS RAPID IP
diffractometer, using graphite-monochromated Mo Kα radiation (λ
= 0.71073 Å). The structure of 2-TMEDA, 3a, and 3c-THF were
solved with the Olex2 solve structure solution program using Charge
Flipping and refined with the ShelXL refinement package using least
squares minimization. Refinement was performed on F2 anisotropically
for all the non-hydrogen atoms by the full-matrix least-squares
method. The hydrogen atoms were placed at the calculated positions
and were included in the structure calculation without further
refinement of the parameters. Crystallographic data (excluding
structure factors) have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publication nos. CCDC-
1400964 (2-TMEDA), CCDC-1400965 (3a), CCDC-1400966 (3c-
THF). These data can be obtained free of charge from the Cambridge
1
Purification System and dried over fresh Na chips in the glovebox. H
and 13C NMR spectra were recorded on a Bruker-400 spectrometer
(FT, 400 MHz for 1H; 100 MHz for 13C) or Bruker-500 spectrometer
1
(FT, 500 MHz for H; 126 MHz for 13C) at 30 °C.
Synthesis of Lithium Aluminate Complex 2 and 2-TMEDA.
To a benzene solution (5 mL) of 1,4-dilithio-1,3-butadiene (119 mg,
0.5 mmol), 1.0 equiv of AlEt2Cl (60 mg, 0.5 mmol) was added. The
reaction mixture was stirred at room temperature for 3 h. The solvent
was removed under reduced pressure, and the residue was dissolved in
benzene and filtered. The filtrate was reduced under a vacuum,
affording the lithium aluminate complex 2 as white solid. Then 1.0
equiv of TMEDA (12 mg, 0.1 mmol) was added to the benzene
solution of 2 (32 mg, 0.1 mmol) and stirred for another 1 h at room
temperature. The solution was concentrated and stored at room
temperature to afford 2-TMEDA as a colorless solid.
1
2, white solid, isolated yield 90% (84 mg). H NMR (500 MHz,
THF-d8) δ: −0.39 (q, J = 8.0 Hz, 4H, CH2), 0.00 (s, 18H, CH3), 0.89
(t, J = 8.0 Hz, 6H, CH3), 2.02 (s, 6H, CH3). 13C NMR (126 MHz,
THF-d8) δ: 2.8 (6 CH3), 12.7 (2 CH3), 24.7(2 CH3), 129.1 (2 quat.
C), 160.4 (2 quat. C). Anal. Calcd (%) for 2: C, 60.71; H, 10.83.
Found: C, 60.25; H, 10.66.
2-TMEDA, colorless solid. 1H NMR (400 MHz, C6D6) δ: 0.30 (q, J
= 8.0 Hz, 4H, CH2), 0.39 (s, 18H, CH3), 1.41 (t, J = 8.0 Hz, 6H,
CH3), 1.47(s, 4H, CH2), 1.75 (s, 12H, CH3), 2.23 (s, 6H, CH3). 13C
NMR (100 MHz, C6D6) δ: 2.2 (6 CH3), 11.5 (2 CH3), 24.1 (2 CH3),
45.7 (4, CH3), 56.7 (2, CH2), 164.0 (2 quat. C), 165.6 (2 quat. C). IR:
2950 (s), 2884 (s), 2846 (s), 2796 (m), 1521 (w), 1464 (s), 1361 (w),
1289 (w), 1242 (s), 1185 (w), 1104 (m), 1070 (w), 1020 (m), 945
(m), 838 (s), 752 (m) cm−1. Anal. Calcd (%) for 2-TMEDA: C, 61.06;
H, 11.65; N, 6.47. Found: C, 60.32; H, 11.40; N, 6.30.
Synthesis of Alumoles 3. To a hexane/Et2O (3/1) solution (5
mL) of 1,4-dilithio-1,3-butadiene (0.5 mmol), 2.0 equiv of AlEt2Cl
(121 mg, 1.0 mmol) was added. The reaction mixture was stirred at
room temperature for 3 h. The solvent was removed under reduced
D
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Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif.
K.; Yamamoto, H.; Nozaki, H. J. Am. Chem. Soc. 1974, 96, 6513.
(g) Maruoka, K.; Oshi, M.; Yamamoto, H. J. Org. Chem. 1993, 58,
7638. (h) Wunderlich, S. H.; Knochel, P. Angew. Chem., Int. Ed. 2009,
48, 1501. (i) Kienle, M.; Unsinn, A.; Knochel, P. Angew. Chem., Int. Ed.
2010, 49, 4751. (j) Haag, B.; Mosrin, M.; Ila, H.; Malakhov, V.;
ASSOCIATED CONTENT
* Supporting Information
■
S
́ ́
Knochel, P. Angew. Chem., Int. Ed. 2011, 50, 9794. (k) Hernan-Gomez,
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.5b01551.
A.; Martín, A.; Mena, M.; Santamaría, C. Inorg. Chem. 2011, 50, 11856.
(l) Hao, J.; Li, J.; Cui, C.; Roesky, H. W. Inorg. Chem. 2011, 50, 7453.
(m) Li, J.; Li, X.; Huang, W.; Hu, H.; Zhang, J.; Cui, C. Chem. - Eur. J.
2012, 18, 15263. (n) Conway, B.; Crosbie, E.; Kennedy, A. R.; Mulvey,
R. E.; Robertson, S. D. Chem. Commun. 2012, 48, 4674. (o) Hernan-
Gomez, A.; Martin, A.; Mena, M.; Santamaria, C. Dalton Trans. 2013,
42, 5076.
DOSY NMR spectrum of 3a in C6D6, NMR data, further
experimental details and spectra for all new compounds
(PDF)
Crystallographic data for 2-TMEDA, 3a and 3c-THF
(CIF)
(6) (a) Uchiyama, M.; Naka, H.; Matsumoto, Y.; Ohwada, T. J. Am.
Chem. Soc. 2004, 126, 10526. (b) Naka, H.; Uchiyama, M.;
Matsumoto, Y.; Wheatley, A. E. H.; McPartlin, M.; Morey, J. V.;
Kondo, Y. J. Am. Chem. Soc. 2007, 129, 1921. (c) Naka, H.; Morey, J.
V.; Haywood, J.; Eisler, D. J.; McPartlin, M.; Garcia, F.; Kudo, H.;
Kondo, Y.; Uchiyama, M.; Wheatley, A. E. H. J. Am. Chem. Soc. 2008,
130, 16193.
AUTHOR INFORMATION
Corresponding Author
*E-mail: zfxi@pku.edu.cn.
■
Notes
(7) (a) Eisch, J. J.; Kaska, W. C. J. Am. Chem. Soc. 1962, 84, 1501.
(b) Eisch, J. J.; Kaska, W. C. J. Am. Chem. Soc. 1966, 88, 2976.
The authors declare no competing financial interest.
(c) Hoberg, H.; Krause-Going, R. J. Organomet. Chem. 1977, 127, C29.
̈
ACKNOWLEDGMENTS
(d) Kruger, C.; Sekutowski, J. C.; Hoberg, H.; Krause-Going, R. J.
̈
̈
■
Organomet. Chem. 1977, 141, 141. (e) Hoberg, H.; Krause-Going, R.;
̈
This work was supported by the 973 Program
(2012CB821600) and the Natural Science Foundation of
China (NSFC). The authors are grateful to Dr. Xiang Hao of
ICCAS for analysis of crystallographic data.
Sekutowski, J. C.; Kruger, C. Angew. Chem., Int. Ed. Engl. 1977, 16,
183.
(8) (a) Hoberg, H.; Richter, W. J. Organomet. Chem. 1980, 195, 347.
(b) Negishi, E.; Kondakov, D. Y.; Choueiry, D.; Kasai, K.; Takahashi,
T. J. Am. Chem. Soc. 1996, 118, 9577. (c) Xi, Z.; Li, P. Angew. Chem.,
Int. Ed. 2000, 39, 2950. (d) Zhao, C.; Li, P.; Xi, Z.; Cao, x. Chem. - Eur.
J. 2002, 8, 4292.
(9) Agou, T.; Wasano, T.; Jin, P.; Nagase, S.; Tokitoh, N. Angew.
Chem., Int. Ed. 2013, 52, 10031.
(10) (a) Wasano, T.; Agou, T.; Sasamori, T.; Tokitoh, N. Chem.
Commun. 2014, 50, 8148. (b) Agou, T.; Wasano, T.; Sasamori, T.;
Guo, J.-D.; Nagase, S.; Tokitoh, N. Angew. Chem., Int. Ed. 2015, 54,
9568.
REFERENCES
■
(1) (a) Organoaluminum Compounds; Mole, T.; Jeffrey, E. A. Elsevier:
Amsterdam, 1972. (b) Modern Organoaluminum Reagents: Preparation,
Structure, Reactivity and Use; Woodward, S.; Dagorne, S., Eds.;
Springer-Verlag: Berlin, 2013. (c) Gremaud, L.; Alexakis, A. Angew.
Chem., Int. Ed. 2012, 51, 794. (d) Wei, Y.; Wang, S.; Zhou, S.; Feng,
Z.; Guo, L.; Zhu, X.; Mu, X.; Yao, F. Organometallics 2015, 34, 1882.
(e) Zhou, S.; Yang, Z.; Chen, X.; Li, Y.; Zhang, L.; Fang, H.; Wang,
W.; Zhu, X.; Wang, S. J. Org. Chem. 2015, 80, 6323.
(11) Agou, T.; Wasano, T.; Sasamori, T.; Tokitoh, N. Organometallics
2014, 33, 6963.
(2) For selected examples, see: (a) Soga, K.; Shiono, T. Prog. Polym.
Sci. 1997, 22, 1503. (b) Bolton, P. D.; Mountford, P. Adv. Synth. Catal.
2005, 347, 355. (c) Castro-Osma, J. A.; Alonso-Moreno, C.; García-
(12) For reviews, see: (a) Xi, Z. Acc. Chem. Res. 2010, 43, 1342.
(b) Zhang, S.; Zhang, W.-X.; Xi, Z. Top. Organomet. Chem. 2014, 47, 1.
For recent applications, see: (c) Li, H.; Liu, L.; Wang, Z.; Zhao, F.;
Zhang, S.; Zhang, W.-X.; Xi, Z. Chem. - Eur. J. 2011, 17, 7399.
(d) Zhang, S.; Wei, J.; Zhan, M.; Luo, Q.; Wang, C.; Zhang, W.-X.; Xi,
Z. J. Am. Chem. Soc. 2012, 134, 11964.
(13) Geng, W.; Wei, J.; Zhang, W.-X.; Xi, Z. J. Am. Chem. Soc. 2014,
136, 610.
(14) Li, H.; Wei, B.; Xu, L.; Zhang, W.-X.; Xi, Z. Angew. Chem., Int.
Ed. 2013, 52, 10822.
(15) Wei, J.; Liu, L.; Zhan, M.; Xu, L.; Zhang, W.-X.; Xi, Z. Angew.
Martinez, J. C.; Fernan
Sanchez, A.; Otero, A. Macromolecules 2013, 46, 6388. (d) Hao, P.;
́ ́
dez-Baeza, J.; Sanchez-Barba, L. F.; Lara-
́
Yang, Z.; Li, W.; Ma, X.; Roesky, H. W.; Yang, Y.; Li, J. Organometallics
2015, 34, 105.
(3) For selected examples, see: (a) Taylor, M. S.; Zalatan, D. N.;
Lerchner, A. M.; Jacobsen, E. N. J. Am. Chem. Soc. 2005, 127, 1313.
(b) Wieland, L. C.; Deng, H.; Snapper, M. L.; Hoveyda, A. H. J. Am.
Chem. Soc. 2005, 127, 15453. (c) Hashimoto, T.; Naganawa, Y.;
Maruoka, K. J. Am. Chem. Soc. 2011, 133, 8834. (d) Bleschke, C.;
Tissot, M.; Muller, D.; Alexakis, A. Org. Lett. 2013, 15, 2152.
̈
Chem., Int. Ed. 2014, 53, 5634.
(16) Xu, L.; Wang, Y.-C.; Wei, J.; Wang, Y.; Wang, Z.; Zhang, W.-X.;
Xi, Z. Chem. - Eur. J. 2015, 21, 6686.
(4) For selected examples, see: (a) Nagata, W.; Yoshioka, M.; Hirai,
S. J. Am. Chem. Soc. 1972, 94, 4635. (b) Ooi, T.; Takahashi, M.;
Maruoka, K. Angew. Chem., Int. Ed. 1998, 37, 835. (c) Ishikawa, T.;
Ogawa, A.; Hirao, T. J. Am. Chem. Soc. 1998, 120, 5124. (d) Chen, E.
Y.-X.; Cooney, M. J. J. Am. Chem. Soc. 2003, 125, 7150. (e) Zhou, S.;
Wu, K.-H.; Chen, C.-A.; Gau, H.-M. J. Org. Chem. 2009, 74, 3500.
(f) Nakamura, T.; Suzuki, K.; Yamashita, M. J. Am. Chem. Soc. 2014,
136, 9276. (g) D’yakonov, V. A.; Makhamatkhanova, A. L.;
Dilmukhametova, L. K.; Agliullina, R. A.; Tyumkina, T. V.;
Dzhemilev, U. M. Organometallics 2015, 34, 221.
(17) Huffman, J. C.; Streib, W. E. J. Chem. Soc. D 1971, 911.
(18) (a) Morris, K. F.; Johnson, C. S. J. Am. Chem. Soc. 1992, 114,
3139. (b) Cohen, Y.; Avram, L.; Frish, L. Angew. Chem., Int. Ed. 2005,
44, 520. (c) Macchioni, A.; Ciancaleoni, G.; Zuccaccia, C.; Zuccaccia,
D. Chem. Soc. Rev. 2008, 37, 479. (d) Consiglio, G.; Failla, S.;
Finocchiaro, P.; Oliveri, I. P.; Purrello, R.; Di Bella, S. Inorg. Chem.
2010, 49, 5134. (e) Li, D.; Kagan, G.; Hopson, R.; Williard, P. G. J.
Am. Chem. Soc. 2009, 131, 5627. (f) Su, C.; Guang, J.; Li, W.; Wu, K.;
Hopson, R.; Williard, P. G. J. Am. Chem. Soc. 2014, 136, 11735. (g) Su,
C.; Hopson, R.; Williard, P. G. J. Am. Chem. Soc. 2014, 136, 3246.
(5) For reviews, see: (a) Linton, D. J.; Schooler, P.; Wheatley, A. E.
H. Coord. Chem. Rev. 2001, 223, 53. (b) Mulvey, R. E.; Mongin, F.;
Uchiyama, M.; Kondo, Y. Angew. Chem., Int. Ed. 2007, 46, 3802.
(c) Wunderlich, S. H.; Knochel, P. Angew. Chem., Int. Ed. 2009, 48,
1501. (d) Harrison-Marchand, A.; Mongin, F. Chem. Rev. 2013, 113,
7470. (e) Mongin, F.; Harrison-Marchand, A. Chem. Rev. 2013, 113,
7563. For selected examples, see: (f) Yasuda, A.; Tanaka, S.; Oshima,
́
(h) Oliva-Madrid, M.-J.; García-Lopez, J.-A.; Saura-Llamas, I.; Bautista,
D.; Vicente, J. Organometallics 2014, 33, 33. (i) Robertson, S. D.;
Kennedy, A. R.; Liggat, J. J.; Mulvey, R. E. Chem. Commun. 2015, 51,
5452.
E
DOI: 10.1021/acs.inorgchem.5b01551
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
(19) (a) Prakash, G. K. S.; Reddy, V. P.; Rasul, G.; Casanova, J.; Olah,
G. A. J. Am. Chem. Soc. 1992, 114, 3076. (b) Solomon, S. A.; Layfield,
R. A. Dalton Trans. 2010, 39, 2469.
(20) (a) Ziegler, K.; Gellert, H. G.; Martin, H.; Nagel, K.; Schneider.
J. Liebigs Ann. Chem. 1954, 589, 91. (b) Karsch, H. H.; Appelt, A.;
Kohler, F. H.; Muller, G. Organometallics 1985, 4, 231.
̈
̈
(21) Li, S.; Qu, H. M.; Zhou, L. S.; Kanno, K.; Guo, Q. X.; Shen, B.
J.; Takahashi, T. Org. Lett. 2009, 11, 3318.
(22) Bock, H.; Roth, B. Phosphorus Sulfur Relat. Elem. 1983, 14, 211.
F
DOI: 10.1021/acs.inorgchem.5b01551
Inorg. Chem. XXXX, XXX, XXX−XXX