Intramolecular mobility of η5-ligands in chiral zirconocene complexes and the enantioselectivity of alkene functionalization by organoaluminum compounds

Article abstract of DOI:10.1039/c6dt01366j

The effect of solvent nature (CD₂Cl₂, d₈-toluene, d₈-THF) on the conformational behavior of neomenthyl-substituted zirconocenes CpInd?ZrCl₂ (Cp = η⁵-C₅H₅, Ind? = η⁵-neomenthylindenyl), CpCp′ZrCl₂ (Cp = η⁵-C₅H₅, Cp′ = η⁵-neomenthyl-4,5,6,7-tetrahydroindenyl), and Ind?₂ZrCl₂ (Ind? = η⁵-neomenthylindenyl) was shown by means of dynamic NMR spectroscopy, and the constants and thermodynamic parameters of conformer exchange were determined. The experimental conformational composition of the complexes was compared with structures obtained by quantum chemical modeling using the DFT methods PBE/3ζ and M06-2X/cc-pVDZ(H, C, Cl)/cc-pVDZ-PP(Zr), which predicted three rotamers in the case of both CpInd?ZrCl₂ and CpCp′ZrCl₂, and seven rotational isomers for Ind?₂ZrCl₂, three of these being C₂-symmetric and the others being asymmetric. The enantioselectivity of the conformationally mobile complex Ind?₂ZrCl₂ in the reactions of terminal alkenes with AlR₃ (R = Me, Et) was compared with that of rigid ansa-complexes, rac-p-S, p-S-[Y(η⁵-C₉H₁₀)₂]ZrX₂ (Y = SiMe₂, C₂H₄; X = S-binaphtholate). Faster exchange between the conformers of Ind?₂ZrCl₂ in a chlorinated solvent gives the structural isomer of catalytically active sites, which affords higher substrate conversion and reaction enantioselectivity. Binding of the ligands to ansa-zirconocenes prevents the rotational isomerism of the complexes, providing the same configuration of the β-stereogenic center in the methyl- and ethylalumination products (unlike the conformationally mobile complex Ind?₂ZrCl₂) with an enantiomeric purity of 50-65%.

Full text of DOI:10.1039/c6dt01366j

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Intramolecular mobility of η5-ligands in chiral
zirconocene complexes and the enantioselectivity
of alkene functionalization by organoaluminum
compounds†
Cite this: DOI: 10.1039/c6dt01366j
Lyudmila V. Parfenova,*a Irina V. Zakirova,a Pavel V. Kovyazin,a
Stanislav G. Karchevsky,b Galina P. Istomina,a Leonard M. Khalilova and
Usein M. Dzhemileva
The effect of solvent nature (CD2Cl2, d8-toluene, d8-THF) on the conformational behavior of neo-
menthyl-substituted zirconocenes CpInd*ZrCl2 (Cp = η5-C5H5, Ind* = η5-neomenthylindenyl), CpCp’-
ZrCl2 (Cp = η5-C5H5, Cp’ = η5-neomenthyl-4,5,6,7-tetrahydroindenyl), and Ind*2ZrCl2 (Ind* = η5-neo-
menthylindenyl) was shown by means of dynamic NMR spectroscopy, and the constants and thermo-
dynamic parameters of conformer exchange were determined. The experimental conformational
composition of the complexes was compared with structures obtained by quantum chemical modeling
using the DFT methods PBE/3ζ and M06-2X/cc-pVDZ(H, C, Cl)/cc-pVDZ-PP(Zr), which predicted three rota-
mers in the case of both CpInd*ZrCl2 and CpCp’ZrCl2, and seven rotational isomers for Ind*2ZrCl2, three of
these being C2-symmetric and the others being asymmetric. The enantioselectivity of the conformationally
mobile complex Ind*2ZrCl2 in the reactions of terminal alkenes with AlR3 (R = Me, Et) was compared with
that of rigid ansa-complexes, rac-p-S, p-S-[Y(η5-C9H10)2]ZrX2 (Y = SiMe2, C2H4; X = S-binaphtholate). Faster
exchange between the conformers of Ind*2ZrCl2 in a chlorinated solvent gives the structural isomer of cata-
lytically active sites, which affords higher substrate conversion and reaction enantioselectivity. Binding of the
ligands to ansa-zirconocenes prevents the rotational isomerism of the complexes, providing the same
configuration of the β-stereogenic center in the methyl- and ethylalumination products (unlike the confor-
mationally mobile complex Ind*2ZrCl2) with an enantiomeric purity of 50–65%.
Received 8th April 2016,
Accepted 13th July 2016
DOI: 10.1039/c6dt01366j
www.rsc.org/dalton
contribution of the conformational mobility of η5-ligands at a
metal atom to the activity and stereoselectivity of the catalytic
Introduction
The synthesis of chiral transition metal η5-complexes is a vig-
orously developing field of chemistry. The interest in these
compounds is first of all due to their possible use as stereo-
selective catalysts for the construction of C–H, C–C, and
metal–C bonds. Among these, chiral Ti and Zr complexes
played a crucial role in the development of catalytic methods
for the synthesis of stereoregular oligo- and polymers1 and for
enantioselective functionalization of alkenes with organo-
magnesium and -aluminum compounds.2
systems.3 In these studies, it was demonstrated that the stereo-
selectivity of zirconocenes (R*Ind)2ZrCl2 containing substi-
tuted indenyl ligands (R* = neomenthyl, neoisomenthyl,
menthyl, isomenthyl) in propene polymerization is correlated
with their structural features, namely, the relative configur-
ation of the stereogenic centers in the η5-ligand, which finally
determines the conformational composition of complexes.3a,d
It was found that the more homogeneous conformational com-
position provides higher polypropylene isotacticity.
Investigations on the Group IV metallocenes as catalysts for
alkene polymerization prompted the idea about the possible
Carbometalation of alkenes, which can be conceived as the
first step of Ziegler–Natta polymerization, is a substantive
efficient method for alkene functionalization. The applicability
of enantiomerically pure zirconium catalysts for asymmetric
carbometalation of alkenes with AlR3 was first demonstrated
in ref. 4. Thus, the reaction of 1-octene with AlMe3 in the pres-
ence of bis(1-neomenthylindenyl)zirconium dichloride (3),
bis(1-neoisomenthylindenyl)zirconium dichloride, or bis(1-
neoisomenthyl-4,5,6,7-tetrahydroindenyl)zirconium dichloride
aInstitute of Petrochemistry and Catalysis, Russian Academy of Sciences,
Prospect Oktyabrya, 141, 450075 Ufa, Russian Federation.
E-mail: luda_parfenova@mail.ru
bInstitute of Petroleum Refining and Petrochemistry of the Republic of Bashkortostan,
Iniciativnaya st., 12, 450065 Ufa, Russian Federation
†Electronic supplementary information (ESI) available. See DOI:
10.1039/c6dt01366j
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Thus, in order to elucidate the influence of the intra-
molecular dynamics of ligands in zirconocene complexes on
the activity and stereoselectivity of the catalyst systems in the
reactions of OAC with alkenes, we studied the conformational
composition of complexes 1–3 depending on the solvent
nature by dynamic NMR spectroscopy (CH2Cl2, toluene, THF).
The structures of the possible conformers of the complexes
were simulated by DFT calculations. The obtained results were
compared with the catalytic activity and enantioselectivity of
ansa-zirconocenes 4–7 with a fixed geometry (Scheme 2) in
carbo- and cycloalumination of terminal alkenes.
Scheme 1
afforded 2-methyl-1-octanol with an enantioselectivity of
65–85%ee (S), 50%ee (S), and 6%ee (S), respectively
(Scheme 1).4a The rigid ansa-zirconocenes, (R,R)-ethylene-bis-
(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride or (R,R)-
ethylene-bis-(4,5,6,7-tetrahydro-1-indenyl)zirconium – (R)-l′,l″-
bi-2-naphtholate, showed low enantioselectivity at a level of
8%ee (R) and 6%ee (R), correspondingly.
The study of the enantioselectivity of olefin carboalumina-
tion with AlMe3 in the presence of p-S, p-S-enantiomers of
ansa-zirconocenes containing ethanediyl or dimethylsilylene
bridges showed that the use of allylbenzene as the substrate
results, after oxidation of the reaction mixture, in 2-methyl-3-
phenyl-1-propanol with an enantiomeric excess of 25–33%ee,
which scarcely depends on the catalyst structure.5 In this
study, the highest enantioselectivity (about 80%ee) was
achieved in styrene methylalumination, catalyzed by the
[Ph3C][B(C6F5)4]-activated p-S, p-S-ethylene-bis-(1-indenyl)zirco-
nium dichloride.
Results and discussion
Conformational analysis of complexes 1–3
The conformations of CpInd*ZrCl2 (1) were investigated by
low-temperature NMR spectroscopy in CD2Cl2 and d8-toluene.
In both solvents, lowering the temperature led to broadening
of the Cp and indenyl H2 and H3 signals in the downfield
region of the 1H NMR spectrum of complex 1 (Fig. 1). In di-
chloromethane at 175 K, structures with discrete signals of Cp
ligands could be observed.
In order to elucidate the structures of the possible confor-
mers of complex 1, we carried out a quantum chemical study
using the DFT methods PBE/3ζ7,8 and M06-2X/cc-pVDZ(H, C, Cl)/
cc-pVDZ-PP(Zr),9–12 which demonstrated their applicability to
the description of the Zr-containing systems. Analysis of the
potential energy surface for the molecule revealed three key
rotation isomers 1A, 1B, and 1C (Fig. 2, Table 1). According to
the calculations using PBE/3ζ, rotamer 1B predominates,
whereas the populations of 1C and 1A are considerably lower.
The population ratio for rotamers 1B and 1C is 10 : 1. Calcu-
lations in M06-2X showed the prevalence of 1B and 1C with a
ratio 6 : 4.
Investigation of the reaction of terminal alkenes with AlR3
(R = Me, Et) catalyzed by enantiomerically pure Zr complexes,
(cyclopentadienyl)(1-neomenthylindenyl)zirconium dichloride
(1),
(cyclopentadienyl)(1-neomenthyl-4,5,6,7-tetrahydroinde-
nyl)zirconium dichloride (2), and bis-(1-neomenthylindenyl)
zirconium dichloride (3), demonstrated6 that the chemo- and
enantioselectivity of these reactions are substantially affected
by the catalyst and alkene structures, OAC nature, and reaction
conditions (temperature, reactant ratio, solvent). Presumably,
the key factor determining the dependence of enantio-
selectivity on the solvent nature and OAC structure is the con-
formational behavior of the η5-ligands in bimetallic Zr,Al-
intermediates, which control the reaction pathways.
The observed differences between the Cp chemical shifts
for the conformers of complex 1 (Fig. 1a, 175 K) can be attribu-
ted to the changes in dihedral angles between the η5-ligand
planes (α) in the rotamers (Fig. 2). According to our calcu-
lations, this difference can be as large as 16°. The smallest α
angles among the conformers were found for the most popu-
lated 1B and 1C.
A similar investigation of complex CpCp′ZrCl2 (2) in the
same solvents demonstrated the splitting of the 1H NMR
signals of characteristic protons at C2 and C3 carbon atoms of
the substituted tetrahydroindenyl ligand at temperatures
below 220 K (Fig. 3). In toluene, the conformers differed also
by the Cp-ring chemical shifts (Fig. 3b, 197–210 K). In di-
chloromethane at 197 K, the spectrum exhibited two proton
signals at δH 6.83 and 6.18 ppm and proton signals at δH 5.59
and 5.67 ppm in 88 : 12 ratio (Fig. 3). This type of splitting was
found in both toluene and THF, the ratio of the conformers
remaining at the same level (Table 2). In all cases, the differ-
ence between the chemical shifts of the H2 and H3 protons
was greater for the major conformer than for the minor one.
Scheme 2
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Fig. 1 Variable temperature 1H NMR study of complex 1 in CD2Cl2 (a) and d8-toluene (b).
0.06 kcal mol−1, ΔH≠ = 7.47
0.52 kcal mol−1, and ΔS≠
=
=
−14.89 10.76 cal (mol K)−1; in toluene, k195 = 3.1 s−1, ΔG=195
11.08 0.02 kcal mol−1, ΔH≠ = 7.20 0.24 kcal mol−1, and ΔS≠
= −19.85 4.90 cal (mol K)−1; in THF, k195 = 5.1 s−1, ΔG=195
10.88 0.05 kcal mol−1, ΔH≠ = 7.89 0.67 kcal mol−1, ΔS≠
=
=
−15.57 13.67 cal (mol K)−1
.
The exchange rate between the conformers of complex 2
increases in the series toluene < THF < dichloromethane,
which is attributable to the decrease in the Gibbs activation
energy due to solvation effects.
The quantum chemical study on the structure of the poss-
ible conformers of complex 2 revealed the same rotamers as in
complex 1 (Fig. 2, Table 1). PES scanning for complex 2 using
both calculation methods showed rotamer 2A to predominate
(∼99% population). Particularly this form participates in the
crystallization of the complex.13a Compared with conformer
2A, populations of conformers 2B and 2C were much lower
(Table 1).
Evaluation of the solvation effect on the conformer distri-
bution of complexes 1 and 2 within the conductor-like polari-
sable continuum model (CPCM)14 exhibited an increase of the
relative content of minor conformer 1A up to ∼2% in the case
Fig. 2 Structure and dihedral angle α for conformers 1A–C and 2A–C.
For this complex, the rate constants for the rotamer inter- of more polar solvents
–
THF and dichloromethane
conversion were calculated, and activation parameters were (Table S1†), and substantial growth of the conformer 2B frac-
derived from the Eyring equation (ln(k/T) vs. 1/T plot, tion up to ∼14% as well. It should be noted that theoretical
Fig. S8†): in dichloromethane, k190 = 12.5 s−1, ΔG1=90 = 10.24
populations of complex 2 rotamers practically do not depend
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Table 1 Calculated relative Gibbs energies, populations and NMR shifts
of the conformers of complexes 1–3 at 180 K
(Table 1); therefore, the population of 3B is greater than 99%.
According to X-ray diffraction data,3a the complex in the crystal
occurs in conformation 3A.
A variable temperature NMR study of solutions of Ind*2ZrCl2
(3) in CD2Cl2, d8-toluene, and d8-THF showed that (i) the
dynamic pattern in the NMR spectra is associated with the mobi-
lity of indenyl ligands relative to each other and the Zr atom, (ii)
mobility of the η5-ligand and, hence, the conformational compo-
sition of the complex depends on the solvent nature.
For example, lowering the temperature of a solution of
complex 3 in CD2Cl2 down to 180 K induces splitting of the
resonance lines of protons at C2 and C3 in the 1H NMR spectra
into three groups of signals, indicating the existence of at least
three conformers. Two of them (3a,b) refer to C2-symmetry and
one (3c) has C1-symmetry, their ratio in CD2Cl2 being
70 : 15 : 15 (Fig. 5, Table 2). This result is consistent with pub-
lished data.3a,d The analysis of the chemical shifts of the
observed conformers indicates that the C2-symmetric rotamer
3a can be related to the theoretically predicted structures 3A,G.
The upfield shift of the H3 signal of the other conformer of the
same symmetry (3b)3a,d is apparently caused by the shielding
effect of the benzene moiety of the opposing indenyl ligand,
which is consistent with the results on chemical shift calcu-
lations showed in Table 1; this provides grounds for assigning
the theoretical structure 3B to conformer 3b. The signals of
the H2 and H3 protons of the C1-symmetric conformer 3c are
located at 6–7 ppm, which is indicative of the absence of the
shielding effect from the benzene ring of the opposing ligand.
This is the only case of theoretical structure 3C.
δ (1H), ppm
ΔG°180
,
Complex Conformer kcal mol−1 P180, % H2
H3
Δδ(H2–H3)
PBE/3ζ
1
2
3
1A
1B
1C
1.51
0.00
0.64
0.5
90.0
9.5
2A
2B
2C
0.00
1.29
2.53
98.9
1.1
0.0
3A
3B
3C
3D
3E
3F
3G
2.58
0.00
4.47
6.87
3.40
12.58
12.86
0.0
100.0
0.0
0.0
0.0
0.0
0.0
M06-2X
1
1A
1B
1C
1.99
0.00
0.09
0.0
57.9
42.1
7.05 6.12 0.93
7.86 6.28 1.58
7.84 7.10 0.74
2
3
2A
2B
2C
0.00
1.44
2.01
99.3
0.6
0.1
6.70 5.54 1.16
7.45 5.79 1.66
7.50 6.54 0.96
3A
3B
3C
1.58
0.00
6.77
0.4
99.6
0.0
7.68 6.73 0.95
7.66 5.03 2.62
8.05 6.56 1.49
8.44 7.18 1.26
7.14 4.84 2.30
7.97 7.48 0.49
5.56 6.88 -1.32
8.19 6.64 1.55
4.38 6.00 -1.63
7.72 7.54 0.18
7.41 6.73 0.69
3D
3E
3F
3G
9.23
3.26
0.0
0.0
0.0
0.0
Unlike CD2Cl2, in d8-toluene, complex 3 was found to com-
prise only two C2-symmetric conformers, 3a and 3b, in a ratio
of 20 : 80 (Table 2). The same pattern was observed in THF.
Thus, conformer 3B most probably predominates in these sol-
vents, as has been theoretically predicted.
15.35
15.19
The rate constants and thermodynamic parameters for the
on the nature of the solvent, which corresponds to the NMR exchange between the rotamers of complex 3 in toluene were
experiment. Moreover, we attempted to assign the structure of determined on the basis of lineshape analysis for the H2
conformers 2a,b on the basis of calculated NMR chemical proton signals in the 1H NMR spectrum: k190 = 18.7 s−1
shifts of characteristic protons H2 and H3 in the theoretically ΔG1=90 = 10.09 0.06 kcal mol−1, ΔH≠ = 8.15 0.38 kcal mol−1
,
,
possible rotamers 2A–C. Thus, as follows from the calculations ΔS≠ = −10.30 7.88 cal (mol K)−1 (Fig. S8†). It can be stated
shown in Table 1, the proximity of H2 and/or H3 with the Cl that the interconversion rate for complex 3 is higher than that
atom should provide a downfield shift of the NMR signals of in complex 2. Thus, going from neomenthyl-substituted tetra-
these protons. Only the main conformer 2a satisfies this con- hydroindenyl to the indenyl ligand accelerates the intra-
dition, in which the H2 proton experiences a deshielding effect molecular dynamic process, apparently, due to a decrease in
(Table 2), however the theoretical population of the corres- the activation barrier.
ponding rotamer 2B in all three solvents is 7–15%. Thus, a
As follows from Fig. 6, gradual addition of dichloromethane
more detailed theoretical studies of the conformer solvation to a toluene solution of complex 3 induces a change in the
process and its influence on the NMR chemical shifts are conformer ratio, so that at a high content of CD2Cl2, confor-
required, namely, consideration of specific solvation probably mer 3a actually starts to predominate.
with the gradual inclusion of solvent molecules.
Theoretical modelling of the solvent effect on the confor-
Quantum chemical calculations for the complex Ind*2ZrCl2 mer 3A–G distribution demonstrated the possibility of the
(3) showed the existence of seven conformers, three of them increase in the 3A content to the ratio 3A : 3B ≈ 1 : 1
having C2 symmetry (3A, 3B, 3G) and the others having the C1 (Table S1†) both in dichloromethane and THF, however, the
symmetry (Fig. 4). Conformer 3B was found to be energetically model that is used for the system description does not explain
most favorable. The relative Gibbs energy difference between the exceptional influence of the chlorine-containing solvent on
the major and minor conformers is more than 1.5 kcal mol−1 the complex 3 conformational behavior.
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Fig. 3 Variable temperature 1H NMR study of complex 2 in CD2Cl2 (a) and d8-toluene (b) (*-solvent).
Table 2 1H NMR chemical shifts of the conformers of complexes 2 and 3 in CD2Cl2, d8-toluene and d8-THF (400.13 MHz, T = 190 K)
δ (1H), ppm
Complex
Solvent
Conformer
Conformer ratio
H2
H3
Δδ(H2–H3)
2
CD2Cl2 (190 K)
2a
2b
2a
2b
2a
2b
88
12
90
10
87
13
6.83
6.18
5.47
4.96
7.01
6.51
5.59
5.67
4.79
4.82
5.82
5.89
1.24
0.51
0.68
0.14
1.19
0.62
d8-Toluene (190 K)
d8-THF (190 K)
3
CD2Cl2 (180 K)
3a
3b
3c
70
15
15
7.15
6.63
7.04
6.74
6.13
6.07
—
7.41
6.85
—
6.32
4.80
6.43
6.36
5.87
4.40
—
6.35
4.83
—
0.83
1.83
0.64
0.31
0.26
1.67
—
1.06
2.02
—
d8-Toluene (180 K)
d8-THF (185 K)
3a
3b
3c
3a
3b
3c
20
80
0
18
82
0
Thus, the conformational composition and the mobility of Catalytic action of enantiomerically pure zirconocenes in the
the η5-ligand largely depend on the nature of the solvent, reactions of alkenes with trialkylalanes
which may play a considerable role in the control of the cata-
lytic activity and enantioselectivity of chiral zirconocenes in The results of our previous studies on the activity and enantio-
the alkene functionalization by OAC.
selectivity of catalysts 1–3 in the alkene carbo- and cyclometa-
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Fig. 4 Structure of conformers of complex Ind*2ZrCl2 (3).
Fig. 5 Variable temperature 1H NMR study of complex 3 in CD2Cl2 (a) and d8-toluene (b).
6c
lation by organoaluminum or -magnesium compounds,6 with AlEt3 conducted in CH2Cl2. Terminal alkenes react with
which are summarized in Scheme 3 and Table 3, gave an idea organomagnesium compounds in Et2O or THF in the presence
on the substantial contribution of the conformational mobility of catalysts 2 or 3 with low conversion and low enantio-
of η5-ligands. Thus, we found that the best results for alkene selectivity (<8%ee).6d The cyclometalation of substituted allyl-
carbometalation, catalyzed by complexes 1–3 are achieved in benzenes with EtAlCl2 (Et2AlCl) and the Mg metal in THF in
dichloromethane.6a,c It was demonstrated that replacement of the presence of catalytic amounts of complexes 1–3 gives trans-
AlMe3 by AlEt3 in the reaction catalyzed by complex (3) results 2,3-dibenzyl-substituted aluminacyclopentanes with enantio-
in the R to S change of the absolute configuration of the meric purity of not more than 16%ee.6e
β-stereogenic center in the carboalumination products.6a
In order to determine the degree of influence of the ligand
Indeed, if one considers the conformational mobility of η5- intramolecular mobility on the reaction enantioselectivity, we
ligands in the key intermediates of alkene carbometallation studied the catalytic properties of enantiomerically pure com-
[L2ZrR(μ-Cl)AlR3],15 the dependence of the stereochemical plexes with a fixed geometry. It was found that ansa-complexes
result of the reaction on the type of AlR3 becomes evident.6a 4–7 provide somewhat lower enantioselectivity than the confor-
Further, the cycloalumination of terminal alkenes gives mationally mobile catalyst 3 (Table 4) both in carbo- and
aluminacyclopentanes in up to 85% yield and 24–57%ee;6b,c cycloalumination of alkenes. The application of neither
the highest enantioselectivity (∼57%ee) in cycloalumination binaphtholate (6) nor dichloride (4) complexes with Si-bonded
was found in the reaction of vinyl-substituted hydrocarbons ligands in the reaction of 1-octene with AlMe3 resulted in the
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Fig. 6 1H NMR of complex 3 in d8-toluene (0.05 M l−1) and admixtures of CD2Cl2 (T = 188 K): (a) 0 mmol CD2Cl2, (b) 1.6 mmol CD2Cl2, (c) 3.0 mmol
CD2Cl2, (d) 4.9 mmol CD2Cl2.
Scheme 3
formation of products. The MAO activation of the catalyst 4 The catalyst structures containing a binaphtholate moiety (6,
afforded carbometallation product (8) in ∼66% yield and an 7) provide much lower enantiomeric excess of 12. The enantio-
enantiomeric excess of 65%, R (Scheme 4). Moreover, function- meric purity of cyclic OAC (13) upon the use of catalysts 4–7
ally substituted oligomers 11 were also formed in up to 34% was 12–26%ee, S. The reaction of 1-hexene with AlEt3 catalyzed
yield.
by these complexes also resulted in the regioselective for-
In the reaction of AlEt3 with 1-hexene, the highest enantio- mation of enantiomerically enriched functionally substituted
selectivity towards carboalumination (12) at a level of 50–51% oligomers 14 with up to 6 units (Table 4). Analysis of the iso-
ee, R, was found for dichloride complexes 4 and 5 (Scheme 5). lated functionally substituted dimers 11 and 19 demonstrated
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Table 3 Catalytic activity and enantioselectivity of zirconocenes 1–3 in the reactions of organoaluminum and -magnesium compounds with
alkenes
Product yield,a % (ee%, R/S)
Catalyst
Reagents
Solvent
Alkene conversion, %
Carbometalation
Cyclometalation
Ref.
1, 2 mol%
1, 2 mol%
1, 5 mol%
1, 5 mol%
1, 5 mol%
2, 2 mol%
2, 2 mol%
3, 8 mol%
3, 8 mol%
3, 8 mol%
3, 8 mol%
3, 8 mol%
3, 5 mol%
3, 5 mol%
3, 5 mol%
AlEt3, 1-hexene
AlMe3, 1-octene
CH2Cl2
Toluene
THF
Toluene
THF
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
Toluene
CH2Cl2
C6H6
85
59
60
32
83
53
99
94
99
99a
85
30
10
7
30 (27, S)
58 (3, R)
51 (3, S)
18 (8, S)
—
51 (41, S)
36 (13, R)
81 (69, R)
92 (59, S)
3 (7, S)
34 (62, S)
4
39 (20, R)
6a
6a
6d
6d
6e
6a
6a
6a
6a
EtMgBr, 1-octene
EtMgBr, 1-octene
EtAlCl2, allylbenzene
AlMe3, 1-hexene
AlEt3, 1-hexene
AlMe3, 1-hexene
AlEt3, 1-octene
4 (5, S)
6 (2, S)
21 (13)
38 (11, R)
7 (3, S)
1
42 (57, S)
23 (24, R)
4
4
AlEt3, 1-octene
AlEt3, vinylcyclohexane
AlEt3, vinylcyclohexane
MgEt2, 1-octene
EtMgBr, 1-octene
EtAlCl2, allylbenzene
6c
6b
6d
THF
Toluene
THF
4
3
—
65
34 (16)
6e
a The reaction runs in the presence of MAO only (30 mol%) and gives 95% of oligomers after 3 h.
Table 4 Reaction of 1-hexene with AlEt3, catalyzed by complexes 4–7 (mole ratio [Zr] : alkene : AlEt3 = 1 : 50 : 60, CH2Cl2, 72 h, 20 °C)
Product yield,a % (ee%, R/S)
Catalyst
Alkene conversion, %
12
13
14
p-S, p-S-4
p-S, p-S-5
S, p-S, p-S-6
S, p-S, p-S-7
99
95
99
98
64 (50, R)
62 (51, R)
15 (15, R)
60 (30, R)
15 (12, S)
18 (11, S)
30 (20, S)
21 (26, S)
13, n = 2–6, [α]2D5(19) = +3.3°
10, n = 2, [α]2D5(19) = +0.35°
54, n = 2
12, n = 2, [α]2D5(19) = −1.5°
a Determined by GC of deuterolysis products.
Scheme 4
that the reaction gave a single diastereomer. The result is con- η5-ligands in the Zr,Al-bimetallic intermediates (in particular,
sistent with published data indicating a high stereoselectivity distribution of conformers of the active sites and the activation
of ansa-complexes in the alkene polymerization.16
energies of alkene insertion).6a
Thus, fixing the geometry of the zirconocene complex
Apparently, the predominance of the R-enantiomers of car-
results in the formation of methyl- and ethylalumination pro- bometalation products in the reactions catalyzed by complexes
ducts with the same configuration of the β-stereogenic center 4–7 occurs upon substrate re-coordination to the Zr–C bond of
(unlike the conformationally mobile complexes). This result the active complex having the p-S, p-S-configuration of the con-
confirms once again the hypothesis stating that in the case of formationally rigid ligand environment (Scheme 6). In the
conformationally flexible complexes (e.g., 3), the reaction case of complex 3, the formation of R-enantiomers in the reac-
enantioselectivity is dictated by the intramolecular mobility of tion of alkenes with AlMe3 can be due to the involvement of
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Scheme 5
Scheme 6
the active site originated from conformer 3G, whereas ide, is possible in this case. The use of toluene or THF as the
S-isomers are produced via a 3A-like intermediate (Scheme 7). solvent causes the domination of sterically hindered confor-
The solvent can make an additional contribution to the mer 3B and, hence, the activity and enantioselectivity of the
enantioselectivity control by changing the interconversion rate catalyst system decrease. Thus, it follows that a homogeneous
between the conformers of catalytically active sites and thus conformational composition and slow interconversion of con-
forming a particular conformational composition. The higher formers are not necessary conditions for the reaction to
enantioselectivity of the reaction of alkenes with AlEt3 cata- proceed with high yield and enantioselectivity (unlike the
lyzed by 3 in a chlorine-containing solvent4b,6a than in the case stereoselective polymerization catalyzed by conformationally
of hydrocarbon or oxygen-containing solvent may be attribut- homogeneous complexes3a,d). A significant issue is the ligand
able to the more diverse conformational composition, which, mobility: the more variable is a complex (to a certain limit),
as we have shown in relation to the initial zirconocene dichlor- the more versatile it is. In other words, the greater the number
Scheme 7
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of “keys” (i.e., catalytically active sites with a certain geometry) AlR3 (R = Me, Et) and the relationship between the confor-
it can form, the greater the number of “locks” (substrates) mational composition of flexible complexes and their activity
that can be subjected to chemo- and enantioselective trans- and enantioselectivity in the same reactions depending on the
formation. As a result, the chemo- and enantioselectivity of the solvent nature provide the conclusion about a substantial con-
reactions are determined by the kinetic factor, namely, the rate tribution of the conformational composition and ligand mobi-
of the key–lock pair reaction. Provided a good match of pair lity to the activity of catalytic systems and the degree of
components, high rate and high stereoselectivity along a par- asymmetric induction. In this connection, further optimiz-
ticular reaction route can be achieved.
ation of the ligand environment, namely, the search for appro-
priate conformers that could be formed via either introduction
of suitable substituents into the indenyl ligand or upon
binding of ligands could advance these studies towards the
design of more efficient catalysts for alkene functionalization
Conclusions
The conformational composition and intramolecular exchange by organomagnesium and -aluminum reagents.
between the conformers of neomenthyl-substituted zircono-
cenes, CpInd*ZrCl2, CpCp′ZrCl2, and Ind*2ZrCl2, depending
on the nature of the solvent (CD2Cl2, d8-toluene, d8-THF) were
studied by dynamic NMR spectroscopy and DFT calculations.
Quantum chemical modeling demonstrated the possibility
of the existence of three rotamers of complexes CpInd*ZrCl2
Experimental
General procedures
and CpCp′ZrCl2. According to dynamic NMR, even at low All operations for organometallic compounds were performed
temperatures (170–180 K), the exchange between CpInd*ZrCl2 under argon according to the Schlenk technique. The zircono-
conformers in CD2Cl2 and d8-toluene is not completely cenes 1–3, and racemic 4 and 5 were prepared using the stan-
retarded. In the case of the complex CpCp′ZrCl2, slow inter- dard procedures from ZrCl4 (99.5%, Aldrich) (1, 2,13,6a 3,3a,6b
conversion of two rotamers was found below 220 K, the ratio rac-4,17 rac-5 18). Kinetic resolution of rac-4 and rac-5 was
of the rotamers (∼90 : 10) being virtually independent of the carried out using lithium S-binaphtholate according to the
solvent nature. In the chlorinated solvent, the exchange method described in ref. 19. The solvents (hexane, benzene,
between the conformers of CpCp′ZrCl2 is accelerated.
toluene) were distilled from i-Bu2AlH immediately prior to use;
For the complex Ind*2ZrCl2, the existence of seven rotamers THF and diethyl ether were dried and distilled from sodium/
is theoretically possible, three of them being C2-symmetric and benzophenone before use. Dichloromethane was dried over
the others being asymmetric. Experimentally we found no P2O5. Commercially available 98% AlEt3, 97% AlMe3 (Aldrich)
more than three rotamers of the complex. The replacement of and 10 wt% MAO in toluene (Aldrich) were involved in the
dichloromethane by toluene or THF results in a considerable reactions. Terminal alkenes 1-hexene (97%, Acros) and
change in the conformational composition, namely, in the 1-octene (99%, Acros) were used.
number and the ratio of rotamers: only two C2-symmetric con-
The 1H, 13C, and 77Se NMR spectra were recorded on a
formers in an ∼80 : 20 ratio were found both in toluene and in Bruker AVANCE-400 spectrometer (400.13 MHz (1H),
THF. Switching from the mixed CpCp′ZrCl2 complex contain- 100.62 MHz (13C), and 76.35 MHz (77Se)). A low temperature
ing the substituted tetrahydroindenyl ligand to the bisindenyl NMR study on the conformational behavior of complexes 1–3
Ind*2ZrCl2 complex is accompanied by increase in the intra- was carried out in the interval of 170–300 K. The constants
molecular ligand mobility and decrease in the interconversion and activation parameters of conformer exchange were found
barriers for the conformers.
using lineshape analysis of NMR spectra in program Bruker
The catalytic properties of conformationally rigid com- TopSpin 3.0. d8-Toluene, d8-tetrahydrofuran and CD2Cl2 were
plexes, rac-p-S, p-S-[Y(η5-C9H10)2]ZrX2 (Y = SiMe2, C2H4; X = employed as the solvent and internal standard. The 77Se
S-binaphtholate), in reactions of alkenes with AlR3 (R = Me, Et) chemical shifts are referred to Me2Se. 1D and 2D NMR spectra
were studied. The reaction of alkenes with AlMe3 catalyzed by (COSY HH, HSQC, HMBC) were recorded using standard
rac-p-S, p-S-[Me2Si(η5-C9H10)2]ZrCl2 in the presence of MAO Bruker pulse sequences. The optical rotation [α]D20 was
gave methylalumination products in 66% yield and with measured on a Perkin Elmer-341 polarimeter. Chromato-
enantiomeric purity of 65%ee, R. The alkene carboalumination graphic analysis was carried out on a CARLO ERBA 1150
with AlEt3 catalyzed by rac-p-S, p-S-[Y(η5-C9H10)2]ZrCl2 (Y = instrument in a helium flow, a 50 000 × 0.32 mm column, an
SiMe2, C2H4) afforded 2-ethyl-substituted derivatives in ULTRA-1 stationary phase, and a flame ionization detector.
62–64% yield and an enantiomeric excess of 50–51%ee, R. The The deuterated products were analyzed by GC/MS on an auto-
reaction of AlR3 with alkenes in the presence of enantiomeri- mated QP 2010 Ultra GC/MS assembled with a TD-20 Shi-
cally pure Zr ansa-complexes provided enantiomerically madzu thermal desorber. The enantioselectivity of 1-alkene
enriched functionally substituted oligomeric products as well.
carbo- and cyclometallation was estimated from the enantio-
A comparison of the catalytic action of conformationally meric purity of the alcohols resulting from oxidation and
mobile neomenthyl-substituted bisindenyl complex Ind*2ZrCl2 hydrolysis of the reaction products. The alcohols isolated in
and rigid ansa-zirconocenes in the reactions of alkenes with a pure state were involved in the reaction with R-(+)-phenyl-
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selenopropionic acid (R-PSPA)20 to give diastereomeric esters,
p-S, p-S-(Dimethylsilanediyl {η5-4,5,6,7-tetrahydroindenyl})
1
which were then analyzed by 1H, 13C, and 77Se NMR.
zirconium]-S-binaphtholate (6). Yield: 0.44 g, 30% (99%ee, H
1
NMR). [α]2D5 = +127° (c 0.27 in CH2Cl2). H NMR (C6D6) δ 0.557
Computational details
(s, 6H, SiMe2), 0.97–1.12 (m, 2H, C6HaxHeq), 1.20–1.34 (m, 2H,
All calculations were carried out at the DFT level. The primary C7HaxHeq), 1.41–1.55 (m, 2H, C6HaxHeq), 1.55–1.70 (m, 2H,
conformer screening by η5-ligand rotation, subsequent geome- C7HaxHeq), 1.69–1.84 (m, 2H, C5HaxHeq), 1.87–2.03 (m, 2H,
try optimization of the minima, vibrational frequency analysis, C5HaxHeq), 2.29–2.40 (m, 4H, C8H2), 5.46 (d, J = 2.4 Hz, 2H,
and calculation of thermodynamic corrections to the total C2H), 5.92 (d, J = 3 Hz, 2H, C3H); 6.90 (m, 2H, C17H), 7.08 (m,
energy of the compounds were carried out using the PRIRODA 2H, C16H), 7.20 (d, J = 8.7 Hz, 2H, C12H), 7.28 (d, J = 8.4 Hz,
06 program7 with the Perdew–Burke–Ernzerhof (PBE) func- 2H, C18H), 7.75 (d, J = 7.9 Hz, 2H, C15H), 7.81 (d, J = 8.7 Hz,
tional8 in combination with a 3ζ basis set7b,c (orbital basis sets 2H, C13H). 13C NMR (C6D6) δ −2.3 (SiMe), 21.99 (C6), 22.79
of contracted Gaussian-type functions of size (5s1p)/[3s1p] for (C7), 23.01 (C5), 26.12 (C8), 105.29 (C1), 111.76 (C2), 118.74 (C3),
H, (11s6p2d)/[6s3p2d] for C, (15s11p2d)/[10s6p2d] for Cl, and 127.20 (C9), 137.59 (C4), 118.73 (C20), 121.89 (C12), 122.53 (C16),
(20s16p11d)/[14s11p7d] for Zr, which were used in combi- 125.89 (C17), 127.02 (C18), 127.77 (C15), 128.96 (C13), 135.30
nation with the density-fitting basis sets of uncontracted Gaus- (C19), 135.55 (C14), 160.06 (C11).
sian-type functions of size (5s2p) for H, (10s3p3d1f) for C,
(14s3p3d1f1g) for Cl, and (22s5p5d4f4g) for Zr). Further DFT
calculations were performed using the Gaussian 09 software
Reaction of alkenes with AlR3 (R = Me, Et) in the presence of
complexes 4–7
package, Revision D.01 program.21 The density functional A 25 mL glass reactor mounted on a magnetic stirrer and filled
M06-2X10 with the cc-pVDZ basis set for the main group with argon was charged with catalyst (4–7) (0.03 mmol),
elements (H, C, Cl)11 and the cc-pVDZ-PP basis set for the tran- CH2Cl2 or C6H5CH3 (10 ml), alkene (1.5 mmol), and AlR3
sitional metal (Zr)12 was employed as the method applicable (1.8–7.2 mmol). In the reaction with AlMe3, MAO (1.5 mmol,
for the description of Zr-containing systems.9 We used the 10 wt% in toluene) was added. The reaction was carried out at
Conductor-like Polarisable Continuum Model (CPCM)14 for 20 °C with continuous stirring for 72–120 hours. After com-
the estimation of solvent effects on the conformer distribution. pletion of the reaction, a part of the reaction mixture was
Calculated thermodynamic parameters were determined at quenched with 10% DCl at 0 °C. The products were extracted
180 K. NMR shifts were calculated using the GIAO method.22 with benzene and filtered, and the organic layer was dried
Visualization of quantum chemical data was carried out using with Na2SO4. The product yield (8, 9, 12–14) was determined
the program ChemCraft.23
by analyzing the hydrolysis and deuterolysis products by GLC
and GC/MS.
Synthesis of enantiomerically pure ansa-complexes 4 and 6
The remaining reaction mixture was cooled to 0 °C and oxi-
The complexes were synthesized according to ref. 17 and 18 dized by bubbling O2 for 2 h, and then kept in an oxygen
and derivatized by the procedure described in ref. 19. A 50 mL atmosphere for 24 hours more. The products were quenched
glass reactor mounted on a magnetic stirrer was charged with HCl and extracted into diethyl ether, and the organic
under argon with S-binaphthol (1.1 mmol, 0.32 g) and toluene layer was dried with Na2SO4, filtered, and concentrated. Func-
(20 mL). The mixture was cooled to −78 °C and butyllithium tionally substituted dimers (19) were isolated by column
(0.88 ml, 2.5 M in hexane) was added. The temperature of the chromatography on silica gel using a 6 : 1 hexane : diethyl
reaction mixture was brought to 20 °C and the mixture was ether system. Monohydric alcohols (10, 17) were isolated by
stirred until a white lithium S-binaphtholate precipitate formed. column chromatography on silica gel in a 4 : 1 hexane : diethyl
Complex rac-4 (2.2 mmol, 1.0 g) was preliminary mixed with ether system. Dihydric alcohol (18) was isolated as an oily
toluene (20 ml) and the resulting solution of the complex was liquid after 17 upon the subsequent washing of the column
added in small portions with cooling (down to −78 °C) to a with acetone. The organic fractions were dried with Na2SO4.
mixture of lithium S-binaphtholate. The reaction mixture was
The NMR spectra of compounds 17 and 18 and their PSPA
warmed up to room temperature (22 °C) and stirred for 12 h esters corresponded to published data.6a,d
until a white precipitate was formed. After solvent evaporation,
(2R,S)-Methyl-1-octanol (8).6a Yield: 0.12 g, 55%. Elemental
dichloromethane (20 mL) was added to the residue and the analysis (%) calc. for C9H20O: C, 74.93; H, 13.97; O, 11.09%.
solution was filtered through a glass filter. The filtrate was con- Found: C, 74.61; H, 14.03; O, 11.36%. n2D0 = 1430; b.p. 131 °C.
3
centrated to give 6 as a microcrystalline precipitate.
1H NMR (CDCl3) δ 0.89 (t, J = 6.8 Hz, 3H, CH2CH3), 0.92 (d,
Binaphtholate complex 6 (0.05 g, 0.075 mmol) was dis- 3J = 6.8 Hz, 3H, CHCH3), 1.03–1.16 (m, 1H, CHCHHCH2),
solved in dichloromethane (20 mL), and Me3SiCl (0.15 mmol) 1.36–1.44 (m, 1H, CHCHHCH2), 1.22–1.36 (m, 8H, CH2), 1.61
was added. The reaction mixture was stirred for 1 h. By 1H (oct, J = 6.8 Hz, 1H, CH), 3.51 (dd, J = 10.4 Hz, J = 5.6 Hz,
3
2
3
NMR monitoring, the formation of dichloride complex p-S, 1H, CHHOH), 3.41 (dd, 2J = 10.4 Hz, J = 6.4 Hz, 1H, CHHOH).
3
p-S-4 (90%, 99%ee) was observed. The complex was isolated by 13C NMR (CDCl3) δ 14.1 (C9), 16.7 (C3), 22.8 (C8), 27.2 (C5), 29.8
recrystallization from toluene.
The NMR spectra of compounds 4, 5, 7 corresponded to
published data (4,17 5,18b,c 719).
(C6), 32.0 (C7), 33.4 (C4), 36.0 (C2), 67.8 (C1).
(R)-PSPA ester of (2R,S)-methyl-1-octanol (20). 1H NMR
(CDCl3) δ 0.88 (t, 3H, 3J = 7.3 Hz, CH3CH2CH), 0.859 (d, 3H,
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3J = 7.2 Hz, CH3), 1.21–1.40 (m, 8H, CH2), 1.61–1.75 (m, 1H,
CH2CH), 1.55 (d, 3H, J = 7.1 Hz, CH3CH), 3.74–3.82 (m, 1H,
Notes and references
3
CHSe), 3.76–3.87 (m, 1H, CHHO), 3.89–3.97 (m, 1H, CHHO),
7.21–7.40 (m, 3H, Ph), 7.62 (dd, 2H, J = 7.3 Hz, Ph). 13C NMR
(CDCl3) δ 14.0 (C9), 16.8 (C3), 17.7 (CH3CHSe), 22.6 (C8), 25.7
(C), 29.5 (C5), 31.2 (C7), 34.97 (C4), 38.4 (C2), 37.54 (CHSe), 70.0
(C1), 128.4, 128.97, 129.1, 135.5, 137.1 (Ph), 173.7 (CvO). 77Se
NMR (CDCl3) δ 452.36 (SR), 452.66 (RR).
1 (a) Y. Okamoto and T. Nakano, Chem. Rev., 1994, 94, 349–
372; (b) C. Janiak, Coord. Chem. Rev., 2006, 250, 66–94;
(c) S. Ito and K. Nozaki, in Catalytic Asymmetric Synthesis,
ed. I. Ojima, John Wiley & Sons, Inc., Hoboken, New Jersey,
USA, 2010, pp. 931–985.
2 (a) A. H. Hoveyda and J. P. Morken, Angew. Chem., Int. Ed.,
1996, 35, 1263–1284; (b) U. M. Dzhemilev and
A. G. Ibragimov, Russ. Chem. Rev., 2000, 69, 121–135;
(c) E.-i. Negishi, in Catalytic Asymmetric Synthesis, ed.
I. Ojima, Wiley-VCH, New York, 2000, pp. 165–189;
(d) A. H. Hoveyda, in Titanium and Zirconium in Organic
Synthesis, ed. I. Marek, Wiley-VCH Verlag GmbH & Co.
KgaA, Weinheim, Germany, 2002, pp. 180–229;
(e) E.-i. Negishi, Bull. Chem. Soc. Jpn., 2007, 80, 233–257;
(f) U. M. Dzhemilev and A. G. Ibragimov, J. Organomet.
Chem., 2010, 695, 1085–1110; (g) E.-i. Negishi, ARKIVOC,
2011, 8, 34–53; (h) I. Ojima, J. J. Kaloko, S. J. Chaterpaul,
C. F. Lin and Y. H. G. Teng, in Catalytic Asymmetric Syn-
thesis, ed. I. Ojima, John Wiley & Sons, Inc., Hoboken, New
Jersey, USA, 2010, pp. 643–681; (i) S. Xu and E.-i. Negishi,
Heterocycles, 2014, 88, 845–877.
4-Methyl-2-n-octyl-1-dodecanol (11). Yield: 0.21 g, 29%.
Elemental analysis (%) calc. for C21H44O: C, 80.69; H, 14.19; O,
5.12%. Found: C, 80.21; H 14.98; O 4.81%. 1H NMR (CDCl3)
δ 0.88 (d, 3H, 3J = 7.3 Hz, C13H3), 0.904 (t, 3H, 3J = 7.3 Hz,
C21H3, C12H3), 0.997–1.082 (m, 1H, C3HH), 1.247–1.329 (m,
1H, C3HH), 1.053–1.445 (m, 2H, C5HH), 1.24–1.33 (m, 2H,
C5HH), 1.44–1.523 (m, 1H, C4H), 1.503–1.595 (m, 1H, C2H),
1.16–1.47 (m, 22H, CH2), 3.466–3.596 (m, 2H, C1H2). 13C NMR
(CDCl3) δ 14.09 (C14, C21), 19.98 (C13), 22.68 (C20, C11), 26.86,
27.07, 26.98, 26.66 (C15), 29.4 (C9), 29.64, 29.69 (C6), 30.02
(C17), 30.09 (C16), 30.30 (C4), 30.86 (C18), 31.73 (C14), 31.95
(C19), 37.48 (C5), 37.89, 37.92 (C2), 38.87 (C3), 65.68, 66.22 (C1).
m/z (EI) (%): 294 [M − H2O] (1), 279 (1), 252 (1), 223 (1), 210
(1), 197 (3), 181 (16), 169 (4), 155 (7), 140 (15), 139 (8), 138 (7),
126 (7), 112 (13), 99 (21), 97 (38), 85 (68), 69 (67), 57 (100).
2-n-Butyl-4-ethyl-1-octanol (19). Yield: 0.023 g, 7%. Elemen-
tal analysis (%) calc. for C14H30O: C, 78.43; H, 14.10; O, 7.46%.
Found: C, 78.56; H, 14.03; O, 7.41%. 1H NMR (CDCl3) δ 0.86 (t,
3H, J = 7.2 Hz, C14H3), 0.88–0.97 (m, 6H, C8H3, C12H3),
1.11–1.17 (m, 1H, C3HH), 1.20–1.26 (m, 1H, C3HH), 1.22–1.29
(m, 2H, C5H2), 1.22–1.37 (m, 4H, C7H2C6H2, C11H2C12H2),
1.25–1.34 (m, 2H, C13H2), 1.25–1.34 (m, 1H, C4H), 1.27–1.40
(m, 2H, C9H2), 1.49–1.59 (m, 1H, C2H), 3.49–3.61 (m, 2H,
C1H2). 13C NMR (CDCl3) δ 10.67 (C14), 14.10 (C12), 14.16 (C8),
26.09 (C13), 23.17 (C7, C11), 28.74 (C10), 28.99 (C6), 31.03 (C9),
33.09 (C5), 35.35 (C3), 36.23 (C4), 37.99 (C2), 66.07 (C1). m/z (EI)
(%): 196 [M − H2O]+ (<1), 185 (<1), 167 (2), 154 (1), 139 (7), 125
(6), 112 (14), 97 (20), 83 (37), 70 (51), 57 (100).
1-Hexene oligomers (16). Yield: 0.032 g, 10%. n = 3, m/z (EI)
(%): 282 [M] (<1), 253 (2), 225 (13), 197 (<1), 183 (9), 169 (8), 155
(5), 141 (8), 127 (14), 113 (22), 99 (29), 85 (62), 71 (85), 57
(100.00). n = 4, m/z (EI) (%): 337 [M − C2H5]+ (<1), 309 (6), 267
(4), 253 (6), 211 (4), 183 (8), 169 (7), 155 (6), 141 (9), 127 (14), 113
(20), 99 (26), 85 (50), 71 (63), 57 (100). n = 5, m/z (EI) (%): 393
[M − C4H9]+ (5), 355 (<1), 337 (2), 295 (2), 281 (3), 267 (7), 253
(4), 225 (4), 211 (6), 197 (7), 183 (10), 169 (9), 155 (8), 141 (10),
127 (14), 113 (21), 99 (28), 85 (51), 71 (64), 57 (100). n = 6, m/z
(EI) (%): 477 [M − C4H9]+ (3), 460 (<1), 421 (1), 400 (<1), 379 (<1),
365 (1), 354 (2), 337 (3), 309 (3), 295 (3), 281 (7), 267 (8), 253 (7),
239 (5), 225 (6), 207 (16), 197 (8), 183 (11), 169 (11.5), 155 (10),
141 (11), 127 (15), 113 (21), 99 (27), 85 (52), 71 (66), 57 (100).
3 (a)
G.
Erker,
M.
Aulbach,
M.
Knickmeier,
D. Wingbermuhle, C. Krueger, M. Nolte and S. Werner,
J. Am. Chem. Soc., 1993, 115, 4590–4601; (b) G. W. Coates
and R. M. Waymouth, Science, 1995, 267, 217–219;
(c) E. Hauptman and R. M. Waymouth, J. Am. Chem. Soc.,
1995, 117, 11586–11587; (d) M. Knickmeier, G. Erker and
T. Fox, J. Am. Chem. Soc., 1996, 118, 9623–9630;
(e) J. L. Maciejewski Petoff, M. D. Bruce, R. M. Waymouth,
A. Masood, T. K. Lal, R. W. Quan and S. J. Behrend, Organo-
metallics, 1997, 16, 5909–5916; (f) C. D. Tagge,
R. L. Kravchenko, T. K. Lal and R. M. Waymouth, Organo-
metallics, 1999, 18, 380–388; (g) S. Knuppel, J.-L. Faure,
G. Erker, G. Kehr, M. Nissinen and R. Frohlich, Organo-
metallics, 2000, 19, 1262–1268; (h) R. L. Halterman,
D. R. Fahey, E. F. Bailly, D. W. Dockter, O. Stenzel,
J. L. Shipman, M. A. Khan, S. Dechert and H. Schumann,
Organometallics, 2000, 19, 5464–5470; (i) T. Dreier,
F. Hannig, G. Erker, K. Bergander and R. Frohlich, J. Phys.
Org. Chem., 2002, 15, 582–589; ( j) S. Lin and
R. M. Waymouth, Acc. Chem. Res., 2002, 35, 765–773;
(k) M. Finze, S. E. Reybuck and R. M. Waymouth, Macro-
molecules, 2003, 36, 9325–9334; (l) G. M. Wilmes,
M. B. France, S. R. Lynch and R. M. Waymouth, Organo-
metallics, 2004, 23, 2405–2411; (m) S. E. Reybuck and
R. M. Waymouth, Macromolecules, 2004, 37, 2342–2347;
(n) A. L. Lincoln, G. M. Wilmes and R. M. Waymouth,
Organometallics, 2005, 24, 5828–5835.
4 (a) D. Y. Kondakov and E.-i. Negishi, J. Am. Chem.
Soc., 1995, 117, 10771–10772; (b) D. Y. Kondakov
and E.-i. Negishi, J. Am. Chem. Soc., 1996, 118,
1577–1578.
Acknowledgements
The authors thank the Russian Foundation of Basic Research
(Grants
No.
15-03-03227a,
16-33-00162mol_a,
16-33-
5 R. A. Petros, J. M. Camara and J. R. Norton, J. Organomet.
Chem., 2007, 692, 4768–4773.
60203mol_a_dk) for financial support.
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Paper
6 (a) L. V. Parfenova, T. V. Berestova, T. V. Tyumkina,
P. V. Kovyazin, L. M. Khalilov and R. J. Whitby, Tetrahedron:
Asymmetry, 2010, 21, 299–310; (b) L. V. Parfenova,
P. V. Kovyazin, T. V. Tyumkina, T. V. Berestova,
L. M. Khalilov and U. M. Dzhemilev, J. Organomet. Chem.,
34, 1143–1170; (b) H.-H. Brintzinger and D. Fischer, Adv.
Polym. Sci., 2013, 258, 29–42; (c) L. Corradini, G. Guerra
and L. Cavallo, Top. Stereochem., 2003, 24, 1–46;
(d) Y. Nakayama and T. Shiono, Molecules, 2005, 10, 620–
633.
2013, 723, 19–25; (c) L. V. Parfenova, P. V. Kovyazin, 17 (a) W. A. Herrmann, J. Rohrmann, E. Herdtweck,
T. V. Tyumkina, A. V. Makrushina, L. M. Khalilov and
U. M. Dzhemilev, Tetrahedron: Asymmetry, 2015, 26, 124–
135; (d) T. V. Berestova, T. A. Raznitsina, L. V. Parfenova
and L.M. Khalilov, Bull. Bashkir Univ., 2011, 16, 1147–1151;
(e) L. V. Parfenova, T. V. Berestova, P. V. Kovyazin,
W. Spaleck and A. Winter, Angew. Chem., Int. Ed. Engl.,
1989, 28, 1511–1512; (b) H. J. G. Luttikhedde,
R. P. Leino, J. H. Nasman, M. Ahlgren and T. Pakkanen,
Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1995, 51,
1488–1490.
A. R. Yakupov, E. S. Mesheryakova, L. M. Khalilov and 18 (a) F. R. W. P. Wild, L. Zsolnai, G. Huttner and
U. M. Dzhemilev, J. Organomet. Chem., 2014, 772–773,
292–298.
7 (a) D. N. Laikov and Y. A. Ustynyuk, Russ. Chem. Bull., 2005,
54, 820; (b) D. N. Laikov, Chem. Phys. Lett., 1997, 281, 151–
156; (c) D. N. Laikov, PhD dissertation, Moscow State Uni-
versity, 2000 (in Russian).
H.-H. Brintzinger, J. Organomet. Chem., 1982, 232, 233–247;
(b) F. R. W. P. Wild, M. Wasiucionek, G. Huttner and
H.-H. Brintzinger, J. Organomet. Chem., 1985, 288, 63–67;
(c) Sc. Collins, Br. A. Kuntz, N. J. Taylor and D. G. Ward,
J. Organomet. Chem., 1988, 342, 21–29.
19 (a) W. M. Davis and St. L. Buchwald, J. Am. Chem. Soc.,
1991, 113, 2321–2322; (b) B. Chin and St. L. Buchwald,
J. Org. Chem., 1997, 62, 2267–2268.
8 J. P. Perdew, K. Burke and M. Ernzerhof, Phys. Rev. Lett.,
1996, 77, 3865–3868.
9 Y. Sun and H. Chen, J. Chem. Theor. Comput., 2013, 9, 20 N. V. Orlov and V. P. Ananikov, Chem. Commun., 2010, 46,
4735–4743. 3212–3214.
10 Y. Zhao and D. G. Truhlar, Theor. Chem. Acc., 2008, 120, 21 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
215–241.
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone,
B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng,
J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta,
F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers,
K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand,
K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar,
J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene,
J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo,
R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin,
R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin,
K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador,
J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö. Farkas,
J. B. Foresman, J. V. Ortiz, J. Cioslowski and D. J. Fox, Gaus-
sian 09, Revision D.01, Gaussian, Inc., Wallingford CT,
2009.
11 (a) T. H. Dunning, Jr., J. Chem. Phys., 1989, 90, 1007–1023;
(b) D. E. Woon and T. H. Dunning Jr., J. Chem. Phys., 1993,
98, 1358–1371; (c) E. R. Davidson, Chem. Phys. Lett., 1996,
260, 514–518.
12 K. A. Peterson, D. Figgen, M. Dolg and H. Stoll, J. Chem.
Phys., 2007, 126, 124101.
13 (a) L. Bell, R. J. Whitby, R. V. H. Jones and
M. C. H. Standen, Tetrahedron Lett., 1996, 37, 7139–7142;
(b) G. Dawson, C. A. Durrant, G. G. Kirk, R. J. Whitby,
R. V. H. Jones and M. C. H. Standen, Tetrahedron Lett.,
1997, 38, 2335–2338; (c) L. Bell, D. C. Brookings,
G. J. Dawson, R. J. Whitby, R. V. H. Jones and
M. C. H. Standen, Tetrahedron, 1998, 54, 14617–14634.
14 (a) V. Barone and M. Cossi, J. Phys. Chem. A, 1998, 102,
1995–2001; (b) M. Cossi, N. Rega, G. Scalmani and
V. Barone, J. Comput. Chem., 2003, 24, 669–681.
15 L. V. Parfenova, V. Z. Gabdrakhmanov, L. M. Khalilov and
U. M. Dzhemilev, J. Organomet. Chem., 2009, 694, 3725– 22 S. K. Wolf and T. Ziegler, J. Chem. Phys., 1998, 109, 895–
3731. 905.
16 (a) H.-H. Brintzinger, D. Fischer, R. Mülhaupt, B. Rieger 23 G. A. Zhurko and D. A. Zhurko, ChemCraft, version 1.6,
and R. M. Waymouth, Angew. Chem., Int. Ed. Engl., 1995,
2009.
This journal is © The Royal Society of Chemistry 2016
Dalton Trans.