Trans-Dichlorobis{(1R,4S)-1,7,7-trimethyl-3-[(S)-α-methylbenzylimino] bicyclo[2.2.1]heptan-2-one-N}Palladium(II): Synthesis and structural examination

Article abstract of DOI:10.1134/S1070328413010107

A reaction of (1R,4S)-1,7,7-trimethyl-3-[(S)-α-methylbenzylimino] bicyclo[2.2.1]heptan-2-one with lithium tetrachloropalladate gave a chiral palladium(II) complex with monodentate coordination of the organic ligand. The structure of the complex was confirmed by NMR spectra and X-ray diffraction data.

Full text of DOI:10.1134/S1070328413010107

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2013, Vol. 39, No. 1, pp. 37–40. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © O.A. Zalevskaya, Ya.A. Gur’eva, L.L. Frolova, I.N. Alekseev, P.A. Slepukhin, A.V. Kuchin, 2013, published in Koordinatsionnaya Khimiya, 2013, Vol. 39,
No. 1, pp. 41–44.
transꢀDichlorobis{(1
R,4S
)ꢀ1,7,7ꢀTrimethylꢀ3ꢀ[(
S
)ꢀ
α
ꢀ
Methylbenzylimino]bicyclo[2.2.1]heptanꢀ2ꢀoneꢀ
N}Palladium(II):
Synthesis and Structural Examination
O. A. Zalevskayaa, Ya. A. Gur’evaa,*, L. L. Frolovaa, I. N. Alekseeva, P. A. Slepukhinb, and A. V. Kuchina
a Institute of Chemistry, Komi Research Center, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
b Postovskii Institute of Organic Synthesis, Ural Research Center, Russian Academy of Sciences, Yekaterinburg, Russia
*eꢀmail: gurjevaꢀja@chemi.komisc.ru
Received March 27, 2012
Abstract—A reaction of (1
R
,4S
)ꢀ1,7,7ꢀtrimethylꢀ3ꢀ[(
S
)ꢀαꢀmethylbenzylimino]bicyclo[2.2.1]heptanꢀ2ꢀone
with lithium tetrachloropalladate gave a chiral palladium(II) complex with monodentate coordination of the
organic ligand. The structure of the complex was confirmed by NMR spectra and Xꢀray diffraction data.
DOI: 10.1134/S1070328413010107
H5 )
, 1.91 (m, 1H,
H6 )
J
Chiral palladium complexes are known to be
4
, 3.05 (d, 1H, H ,
J
= 4.7 Hz),
β
β
widely used as catalysts in modern asymmetric syntheꢀ
sis [1, 2]. In connection with this, the preparation and
structural studies of new palladium complexes are of
current interest. Derivatives of naturally occurring
monoterpenoids can serve as starting materials for the
synthesis of enantiomerically pure ligands. Here, we
used (1R,4S)ꢀcamphor quinone (special purity grade
4.64 (q, 1H, H11,
7.1 Hz), 7.34 (dd, 2H, Ar,
(d, 2H, Ar, = 7.3 Hz).
= 6.6 Hz), 7.27 (d, 1H, Ar,
J =
J
= 7.1 Hz, = 7.3 Hz), 7.43
J
J
13C NMR ( , ppm): 9.12 (C10), 17.73 (C8), 20.86
δ
(C9), 23.39 (C6), 24.41 (C12), 29.94 (C5), 44.18 (C7),
49.04 (C4), 57.87 (C1), 62.47 (C11), 126.88, 127.10,
128.51 (C–HAr), 144.27 (Ar), 169.98 (C3), 206.40
(C2).
98%) for the synthesis of imine I.
EXPERIMENTAL
IR (KBr,
(C=N)).
ν
, cm–1): 1751 (
ν
(C=O)), 1672
(
ν
(
1R,4S)ꢀCamphor quinone ( 20 –97.8 (
с
1.5, tolꢀ
α
[ ]D
For C18H23NO
anal. calcd. (%): C, 80.3;
Found (%): C, 79.2;
uene) was prepared as described in [3].
(
S
)ꢀ
α
ꢀMethylꢀ
H, 8.55;
H, 8.76;
N, 5.2.
N, 4.8.
benzylamine (ee 99.5%, Lancaster), palladium chloꢀ
ride (highꢀpurity grade, 98%), and lithium chloride
(reagent grade) were employed as purchased. Methaꢀ
nol, chloroform, hexane, benzene, and diethyl ether
(analytical grade all) were used as solvents. Silica gel
(70–230 mesh, Lancaster) was used for column chroꢀ
matography.
Synthesis of С36H46N2O2Cl2Pd (II). A suspension
of PdCl2 (74 mg, 0.4 mmol) and LiCl (35 mg,
0.8 mmol) in methanol (5 mL) was refluxed for 1 h.
The resulting dark red solution of Li2PdCl4 was cooled
Synthesis of С18H23NO (I)
.
Camphor quinone
ꢀmethylbenzylamine
to room temperature and a solution of imine
I
(566 mg, 3 mmol) and )ꢀ
(S
α
(112 mg, 0.4 mmol) in methanol (5 mL) was added.
The reaction mixture was stirred at room temperature
for 1 h and concentrated in vacuo. The product was
extracted from the residue with chloroform and preꢀ
cipitated with hexane. The yield of complex II was
171 mg (60%), yellow crystals.
(410 mg, 3 mmol) were dissolved in dry benzene
(20 mL) and then BF3 · Et2O (141 mg, 1 mmol) was
added. The resulting solution was refluxed for 12 h and
concentrated in vacuo. The product was isolated by
column chromatography on SiO2 with hexane–
diethyl ether as an eluent. The yield of compound
I
1H NMR (
, ppm, J, Hz): 0.62 (s, 3H, CH3), 0.73
δ
20
was 600 mg (75%), yellow crystals,
+30.3 (
с
0.6,
α
[ ]D
6
(s, 3H, CH ), 1.05 (s, 3H, CH ), 1.06 (m, 1H,
, 1.6
H )
α
3
3
EtOH)
.
H5 ) H6 )
5
1H NMR (
δ
, ppm): 0.92 (s, 3H, CH3), 1.03 (s, 3H,
α
(m, 3H,
,
,
, 2.31 (d, 3H, CH3,
J
= 7.0 Hz),
= 7.0
= 7.1 Hz), 7.33 (dd, 2H, Ar,
= 7.4 Hz), 7.70 (d, 2H, Ar, = 7.4 Hz).
H )
β
β
6
2.59 (d, 1H, H4,
Hz), 7.26 (d, 1H, Ar,
7.1 Hz,
J J
= 3.5 Hz), 6.05 (q, 1H, H11,
CH ), 1.05 (s, 3H, CH ), 1.12 (m, 1H,
, 1.48 (m,
H )
α
3
3
J
J =
5
1H,
, 1.58 (d, 3H, CH ,
J
= 6.6 Hz), 1.77 (m, 1H,
H )
α
J
J
3
37

38
ZALEVSKAYA et al.
Table 1. Crystallographic parameters and the data collecꢀ
tion and refinement statistics for structure II
For C36H46N2O2Cl2Pd
anal. calcd. (%): C, 60.3;
H, 6.41;
H, 6.53;
N, 3.92.
N, 3.84.
Parameter
Crystal system
Value
Found (%):
C, 60.3;
Monoclinic
716.05
The 1H and 13C NMR spectra of imine
plex II were recorded on a Bruker AVANCEꢀII 300
spectrometer (300.17 and 75.49 MHz, respectively) in
I
and comꢀ
M
CDCl3 with the signals of chloroform (δН 7.27
δС 77.00) as the internal standards. The IR spectra
of compounds and II were recorded on an IR Presꢀ
,
Space group
Unit cell parameters
P21
I
tige 21 spectrometer (KBr pellets, diffuse reflection
mode). Elemental analysis was carried out using gas
chromatography on an EA 1110 CHNSO analyzer.
The course of the reactions was monitored, and the
purity of the reaction products was checked, by TLC
on Sorbfil plates.
a
, Å
, Å
9.8336(8)
14.0082(11)
13.0059(9)
105.336(7)
1727.8(2)
2
b
c
, Å
Xꢀray diffraction study of complex II was carried
β
V
Z
, deg
out at 22 С on an Xcalibur S automated diffractometer
°
, Å3
equipped with the CCD detector according to a stanꢀ
dard procedure (Мо radiation, = 0.71073 Å,
scan mode, scan step ).
K
λ
α
graphite monochromator,
ω
1
°
An absorption correction was applied analytically
using a multifaceted crystal model [4]. The structure
was solved by direct methods and refined anisotropiꢀ
cally (for all nonꢀhydrogen atoms) on F2 by the fullꢀ
matrix leastꢀsquares method with the SHELXTLꢀ97
program package [5]. All hydrogen atoms were located
from the difference electronꢀdensity map and refined
isotropically. Crystallographic parameters and the data
collection and refinement statistics for structure II are
given in Table 1.
ρcalcd, g/cm3
1.376
μ
, mm–1
0.725
θ
scan range, deg
28.29–2.59
11068
Number of measured reflections
Number of independent reflecꢀ
6984 (0.0229)
tions (Rint
)
The atomic coordinates and other parameters of
structure II have been deposited with the Cambridge
Crystallographic Data Centre (no. 875043;
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.
uk/data_request/cif).
Number of reflections
with > 2
4784
I
σ
(I)
Completeness, % (for
θ
, deg)
99.9 (26.00)
1.025
S
RESULTS AND DISCUSSION
Number of parameters refined
388
Imine
of (1R,4S)ꢀcamphor quinone with
zylamine. The condensation may produce two geoꢀ
metric isomers with Zꢀ and ꢀconfigurations of the
C=N bond. The NMR spectra of imine contain one
I
was obtained in 75% yield by condensation
(S)ꢀ ꢀmethylbenꢀ
α
R
R
factor for
I
> 2
σ
(
I
)
R
1 = 0.0292, wR2 = 0.0505
1 = 0.0495, wR2 = 0.0519
1.081/–0.411
–0.023(18)
factor for all reflections
Å–3
R
E
I
Δρmax/Δρmin, e
set of signals, which suggests the formation of only one
geometric isomer. Using 2D correlation spectroscopy
(NOESY), we found that imine I has Eꢀconfiguration:
Flack parameter
the NOESY experiment revealed a coupling between
the benzylic proton and the H(4) proton of the terpene
fragment.
13C NMR ( , ppm): 9.36 (C10), 17.60 (C8), 20.57
δ
(C9), 21.20 (C12), 23.21 (C6), 29.47 (C5), 44.53 (C7),
54.25 (C4), 57.31 (C1), 67.07 (C11), 127.46, 128.20,
128.48 (C–HAr), 141.49 (Ar), 181.11 (C3), 201.74
(C2).
Ligand
I was obtained for use in the synthesis of
cyclopalladated complexes. Benzylamine derivatives
are known to readily undergo orthoꢀpalladation at the
aromatic ring [6]. For this purpose, we carried out a
complexation reaction as described by Cope in [7].
IR (KBr,
ν
, cm–1): 1757 (
ν
(C=O)), 1662 ( (C=N)). However, it turned out that no cyclopalladation occurs
ν
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

SYNTHESIS AND STRUCTURAL EXAMINATION
39
C(30)
C(3)
under these conditions; in the resulting complex II
,
C(32)
the imine functions as a monodentate ligand.
C(15)
C(19)
C(26)
C(25)
C(27)
C(4)
O(1)
H3C
C(33)
C(29)
C(21)
10
H
C(28)
Ph
C(9)
C(20)
C(12)
N(2)
1
Cl(4)
C(11)
O
N
O
N
Cl
Pd
Cl
Ph
CH3
N
O
6
5
Li PdCl /CH OH
2
7
8
2
3
4
3
C(36)
9
C(6)
C(8)
N(1)
C(5)
Pd(1)
Cl(2)
C(34)
C(17)
4
11
C(31)
Ph
CH3
H
H
C(23)
C(18)
C(10)
C(14)
C(35)
O(2)
12
C(24)
C(2)
(I
)
(II)
The 1H and 13C NMR spectra of complex II agree
with the structure shown above. The spectra retain all
the signals of the starting imine, with their small
downfield shifts for the nuclei in close vicinity of palꢀ
ladium. The fact that the benzene ring is monosubstiꢀ
tuted is evident from the multiplicity and integrated
intensity of the signals for its protons. The absence of
doubled signals suggests the formation of an individual
isomer.
C(13)
C(22)
C(7)
C(16)
C(1)
Structure II in the crystal (the H atoms are omitted).
atoms. The carbon atoms at the N atoms are virtuꢀ
ally coplanar (deviations are < 0.017 Å); their plane
makes an angle of 82.3 with the plane of the coorꢀ
°
dination environment of the Pd atom. Structure II
does not have symmetry С2 because the other phenyl
substituent changes from the (–)ꢀanticlinal to
(+)ꢀanticlinal conformation relative to the Pd
Structure II determined from Xꢀray diffraction
data is shown in figure; the bond lengths and bond
angles are listed in Table 2.
In structure II, the Pd atom has a square planar
environment with trans arrangement of the Cl atom. The corresponding torsion angles C(18)–
Table 2. Selected bond lengths
d
and bond angles
, Å
ω
in structure II
Bond
d
Bond
O(2)–C(5)
d, Å
Pd(1)–N(2)
Pd(1)–N(1)
Pd(1)–Cl(2)
Pd(1)–Cl(4)
O(1)–C(28)
2.025(3)
2.039(2)
1.189(4)
1.278(3)
1.504(4)
1.270(3)
1.489(4)
N(1)–C(8)
N(1)–C(11)
N(2)–C(12)
N(2)–C(17)
2.3017(11)
2.3106(11)
1.190(4)
Angle
ω
, deg
Angle
ω
, deg
N(2)Pd(1)N(1)
N(2)Pd(1)Cl(2)
N(1)Pd(1)Cl(2)
N(2)Pd(1)Cl(4)
N(1)Pd(1)Cl(4)
Cl(2)Pd(1)Cl(4)
C(8)N(1)C(11)
C(8)N(1)Pd(1)
C(11)N(1)Pd(1)
C(12)N(2)C(17)
C(12)N(2)Pd(1)
C(17)N(2)Pd(1)
O(2)C(5)C(24)
175.44(12)
91.53(8)
89.57(7)
88.00(8)
90.75(7)
178.08(5)
117.6(3)
120.3(2)
122.1(2)
120.8(3)
126.7(2)
112.27(19)
129.2(3)
O(2)C(5)C(8)
N(1)C(8)C(31)
N(1)C(8)C(5)
C(9)C(11)N(1)
N(1)C(11)C(4)
N(1)C(11)H(11
127.4(2)
131.2(3)
124.0(3)
113.3(3)
111.1(3)
107.4
A
)
N(2)C(12)C(20)
N(2)C(12)C(28)
N(2)C(17)C(34)
N(2)C(17)C(18)
132.9(3)
122.4(3)
111.4(3)
112.7(3)
106.1
N(2)C(17)H(17
O(1)C(28)C(3)
O(1)C(28)C(12)
A
)
128.4(4)
127.4(4)
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

40
ZALEVSKAYA et al.
3. Hattori, K., Yoshida, T., Rikuta, K., and Miyakoshi, T.,
C(17)–N(2)–Pd(1) and C(9)–C(11)–N(1)–Pd(1)
are 120.6(3)° and 111.5(3)°, respectively.
Chem. Lett. (Japan), 1994, p. 1885.
4. Clark, R.C. and Reid, J.S., Acta Crystallogr., Sect. A:
Found. Crystallogr., 1995, vol. 51, p. 887.
REFERENCES
5. Sheldrick, G.M., Acta Crystallogr., Sect. A: Found.
Crystallogr., 2008, vol. 64, p. 112.
6. Bruce, M.I., Goodal, B.L., and Stone G.A., J. Chem.
Soc., Dalton Trans., 1978, vol 7, p. 687.
1. Dunina, V.V., Gorunova, O.N., Zykov, P.A., and
Kochetkov, K.A., Usp. Khim., 2011, vol. 80, no. 1, p. 53.
2. Dupont, J., Consorti, C.S., and Spencer, J., Chem.
Rev., 2005, no. 105, p. 2527.
7. Cope, A.C. and Friedrich, E.C., J. Am. Chem. Soc.
1968, vol. 90, p. 909.
,
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013