New approach to the synthesis of azinylcymantrenes

Article abstract of DOI:10.1021/om200159f

A versatile synthetic protocol was proposed for direct C-C coupling of a cymantrene fragment with various azaheterocycles on the basis of nucleophilic substitution of hydrogen in the absence of metal catalysts.

Full text of DOI:10.1021/om200159f

ARTICLE
pubs.acs.org/Organometallics
New Approach to the Synthesis of Azinylcymantrenes
Irina A. Utepova,† Alexandra A. Musikhina,† Oleg N. Chupakhin,*,†,‡ and Pavel A. Slepukhin‡
†Ural Federal University, 19 Mira Street, 620002 Ekaterinburg, Russia
‡Institute of Organic Synthesis of the Russian Academy of Sciences, 22 S. Kovalevskoy Street, 620219 Ekaterinburg, Russia
S Supporting Information
b
ABSTRACT: A versatile synthetic protocol was proposed for direct CꢀC
coupling of a cymantrene fragment with various azaheterocycles on the basis
of nucleophilic substitution of hydrogen in the absence of metal catalysts.
’ INTRODUCTION
To our knowledge there are no available data concerning
the synthesis of hetarylcymantrenes. R-Pyridylcymantrenes and
γ-pyridylcymantrenes were synthesized by the recyclization
of pyrylium salts with ammonium acetate in 9% yield.13 The
(quinolin-8-yl)cymantrene was synthesized by the Negishi cross-
coupling of a zinc derivative of cymantrene with 8-bromoquino-
linecatalyzed byPd(PPh3)2 with prolonged storageof the reaction
mixture.14
In this paper we describe the nucleophilic substitution of
hydrogen in π-deficient azines using a lithiocymantrene as the
nucleophilic reagent. This strategy first was used as a synthetic
approach to the CꢀC coupling of cymantrene with heterocyclic
derivatives. It has been shown that this versatile approach can be
applied to various azines, such as mono-, di-, and triazines bearing
heteroatoms in different positions in the ring, to substituted and
unsubstituted azines, and to benzannelated systems.
Nowadays, different synthetic approaches are used to modify
hetaryl-containing metallocenes.1 The majority of experimental
studies deal with derivatives of ferrocene. Thus, hetarylferrocenes
can be constructed either by building up the heterocyclic
subunits based on functional groups attached to the ferrocene
fragment or by coupling reactions in order to incorporate
heterocyclic fragments into the core structure of ferrocenes.
However, the first method has a number of inherent limitations:
the range of the available ferrocene blocks is rather limited or
cannot be obtained in principle. Therefore in modern synthetic
studies, transition metal catalyzed cross-coupling reactions lead-
ing to the formation of various CꢀC and CꢀX (X is a
heteroatom) bonds have found increasing use. Previously, we
have shown that the synthetic strategy of the oxidative nucleo-
philic substitution of hydrogen (SNH(AO)) without transition
metal catalysts can be successfully applied to the synthesis of
molecular assemblies of ferrocene with azines,2 including planar
chiral compounds3 as well as hetaryl-substituted nitronyl nitroxides.4
Cyclopentadienyltricarbonylmanganese (cymantrene) is an
interesting analogue of ferrocene half-sandwich transition metal
complexes.5 Cymantrene derivatives are used as base compounds
to obtain metallic nanostructured materials,6 metal complex
ꢀpeptide bioconjugates with cytotoxic activity,7 sensors,8 and
ligands for metallocomplexes.9 The possibility of the use of
cymantrene derivatives in bioorganic chemistry as redox labels
for proteins is extensively examined at the present time.10 High
catalytic activity in asymmetric reactions is peculiar to the
cymantrene derivatives bearing the azomethine bond.11 Certain
hetarylcymantrenes under UV irradiation proved to eliminate
one of the carbonyl ligands following the formation of chelate
complexes with a manganeseꢀazine nitrogen bond. These
compounds have been shown to be applicable for the design
of photochromic systems.12
The obtained hetarylcymantrenes bear complexing groups
and can be used as ligands for the synthesis of complexes with
metals and charged or neutral molecules.
’ RESULTS AND DISCUSSION
H
According to the current conception of the SN reactions
mechanism,15 the first step is known to be the addition of
lithiocymantrene to azine to form σH-adducts A (Scheme 1).
The addition step runs without the commonly used activation of
hetarenes. Lithium derivatives are supposed to undergo hydro-
lysis in the presence of water to dihydro compounds 3. The
second step is the aromatization of dihydroazines 3. Oxidation of
σH-adducts of mono- and diazines runs spontaneously due to
the contact of 3aꢀi with air, analogous to the synthesis of
azinylferrocenes.2 The yields ofthe reaction products are increased
Received: February 19, 2011
Published: May 16, 2011
r
2011 American Chemical Society
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Scheme 1. SNH Reaction of the Lithiocymantrene with Mono- and Diazines
Table 1. Yields of Compounds 4aꢀj
about 20% if a mild oxidizing agent such as DDQ (2,3-
dichloro-5,6-dicyanobenzoquinone) is used instead of atmo-
spheric oxygen.
reaction of butylation of azines 1a,b,i with using n-BuLi as
reagent. The butylation products were observed (about 5%),
but they were easily separated from the target products 4 by
column chromatography. t-BuLi as a lithiated agent for cyman-
trene was used to prevent the formation of the products of
butylation of heterocycles 1a,b,i.
Lithiocymantrene 2 has been synthesized by the metalation of
cymantrene with n-BuLi for 0.5 h in dry THF under an atmo-
sphere of argon.16 Lithiocymantrene 2 readily reacts with azines
1aꢀi in a molar ratio of ca. 1:1 (Scheme 1). After addition of the
solution of electrophilic reagents 1aꢀi in dry THF to colorless
lithium derivatives of cymantrene at ꢀ78 °C the solution
immediately becomes dark. The reaction mixture was kept at
this temperature for 1.5 h and then was gradually warmed to
room temperature. Then DDQ in THF was added, and the color
of the solution changed from dark brown to dark green. All
hetarylcymantrenes are light brown, stable, solid compounds
with melting points varying from 20 to 170 °C (Table 1).
The yields of the reaction products vary from 50% to 80%. The
low yields of compounds 4a,b,i, 20ꢀ30%, are due to the side
The structures of the cymantrenes (4) bearing azines were
proved by NMR and IR spectroscopy, mass spectrometry, and
1
elemental analysis. In the H NMR spectra the characteristic
signals of protons of monosubstituted cymantrene are observed
as two multiplets with the two-proton intensity at δ 4.9ꢀ6.2 ppm
and the signals of heterocyclic protons at δ 7.2ꢀ9.2 ppm. All the
mass spectra have a peak of molecular ions. In the IR spectra
the characteristic absorption bands (ν = 1900ꢀ2020 cmꢀ1
)
corresponding to CO stretching vibrations of cymantrene are
observed. The molecular and crystal structures of the products
were obtained by X-ray analysis. The crystal of quinoxalinylcymantrene
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(Figure 1) was obtained by recrystallization from a diethyl ether/
methanol mixture.
compound 3j, in turn, makes it clear that the hydrogen atom is
bound to N(2).
It is well known that increasing the substrate electrophility by
an introduction of electron-withdrawing exocyclic groups or
heteroatoms leads to an increase of the stability of σH-adducts
The NMR spectrum is not essentially changed upon a
temperature decrease to ꢀ40 and ꢀ75 °C. The signal of the
proton of the NH group in (CD3)2CO is shifted downfield upon
the temperature decrease from 25 °C to ꢀ75 °C with the spectra
recorded every 10 degrees.
The ethylated 3j derivative was synthesized because no single
crystal of σH-adduct could be obtained. However, the alkylation
of derivative 3j runs on N(4). Thus derivative 5 was synthesized
by the reaction of 3j with iodoethane. The reaction took place at
room temperature in dry THF under basic conditions in the
presence of sodium hydride (Scheme 4).
The position of the ethyl group at N(4) of the 1,2,4-triazine
part in compound 5 is evident from the observed cross-peak
between C(5) and protons of the NCH2 group in the HMBC
spectrum. When alkylation of 3j proceeds, the upfield shifts of
signals of sp3-hybridized C(5) (Δδ 4.1 ppm) and C(3) (Δδ 1.4
ppm) are observed in the 13C NMR spectra of compounds 5. The
structure of compound 5 has been proved by X-ray analysis
(Figure 3). The crystal of 5 was obtained by crystallization from a
mixture of dichloromethane and heptane.
According to the X-ray analysis, derivative 4h crystallizes in the
space group P21/c (monoclinic crystal system). The bond
lengths and bond angles are within the normal range. The
quinoxaline ring is planar; the deviations of the atoms from
the mean square plane are <0.027 Å. The angle between the
H
in SN transformations. The use of 1,2,4-triazine derivatives as
more electrophilic reagents has allowed us to isolate and to
characterize the intermediates, contrary to the unstable σH-
adducts of mono- and diazines with lithiocymantrene. Thus,
lithium derivatives of cymantrene readily react with azine 1j,
forming the corresponding stable adduct 3j. Compound 3j is
transformed into aromatic product triazinylcymantrene 4j in the
presence of DDQ in THF at room temperature with nearly
quantitative yield (Scheme 2).
In the IR spectrum of compound 3j the NH stretching
1
vibrations at 3300ꢀ3500 cmꢀ1 are observed. In the H NMR
spectrum of compound 3j the characteristic signals of dihydroa-
zines are observed: a singlet at δ 5.77 ppm assigned to the proton
at the sp3-hybridized C atom and a signal of the NH group at δ
11.38 ppm. In the 13C NMR spectrum of derivative 3j the signal
of the sp3-hybridized C(5) at δ 49.79 ppm is observed.17 In the
1H NMR spectra of aromatic compound 4j the signals of the
protons at C(5) and N(4) are absent. The signals of the protons
of the Cp fragment of 4j (4.8ꢀ5.4 ppm) are shifted from those of
adduct 3j (4.4ꢀ5.0 ppm downfild in comparison with 4j). In the
13C NMR spectra the characteristic signal of the sp3-hybridized
carbon atom is absent. It was impossible to ascertain the position
of the proton at the N atom in 3j based on 2D heteronuclear
13
13
1Hꢀ C HSQC and 1Hꢀ C HMBC experiments. Due to the
prototropic tautomerism, this proton can be bound to either
N(2) (structure A3j) or to N(4) (structure B3j) (Scheme 3). In
the 2D HMBC spectra of 3j only the cross-peaks between this
proton and the signals of C(3) and C(6) are observed. The
singlet structure of the signals of H(5) and of NH in the 1H NMR
spectra (in CDCl3 and C3D6O at room temperature) of
Scheme 3. Tautomeric Transformation of 3j
Scheme 4. Reaction of Ethylation of the σH-Adduct
Figure 1. ORTEP structure of 4h with 50% probability thermal
ꢀ
ellipsoids. Selected bond distances (Å) and angles (deg): C(2)ꢀC(11),
1.470(2); C(15)ꢀC(11)ꢀC(2), 125.33(16); N(1)ꢀC(2)ꢀC(11),
117.56(15); C(3)ꢀC(2)ꢀC(11), 120.98(15); C(12)ꢀC(11)ꢀC(2),
127.50(16).
Scheme 2. Reaction of Lithiocymantrene with 3,6-Diphenyl-1,2,4-triazine
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According to the X-ray analysis, derivative 5 crystallizes in the
centrosymmetric space group P21/c (monoclinic crystal system).
The triazine ring is nonaromatic, no equalization of the bond
lengths in the conjugated double bond system of dihydrotriazine
being observed. The triazine cycle is bent along the C6 N2
3 3 3
line. The angle between the mean square C6C7N1N2 and
C6N3C14N2 planes is 34.45(5)°. The deviations of the corre-
sponding atoms from the C6C7N1N2 plane are smaller than
0.02 Å, whereas the deviation from the C6N3C14N2 plane is
0.09 Å due to steric distortions caused by the sp3-hybridized
atom C6. The distance between the Mn atom and the centroid of
the cyclopentadienyl ring is 1.770(2) Å. The distance between
the Mn atoms in the molecular packing is more than 6.0 Å. The
molecular packing is formed by chains of the molecules running
along the 0c axis.
It has been shown that lithiocymantrene is less stable than the
ferrocene analogue. Lithioferrocene was obtained at room tem-
perature or under heating. Lithiocymantrene is stable only at
negative temperatures. The rise in temperature results in a drastic
decrease of the yields of the products or even in the absence of
them. Lithiocymantrene is prone to have less reactivity in
reactions with azines in comparison with lithioferrocene.2 The
yields of azinylcymantrenes are lower than those for azinylferro-
cenes, 10% on average. This might be connected with the sudden
change of the temperature at the moment of the heterocycle
addition to 1, leading to lithiocymantrene destruction. In some
organic solvents (hexane, benzene) hetarylcymantrenes are not
stable in light; the solutions become disturbed owing to the
precipitation.
Figure 2. Fragment of the molecular packing of quinoxalin-2-ylcyman-
trene 4h.
’ CONCLUSION
An efficient, versatile, noncatalytic method of CꢀC coupling
for the synthesis of monosubstituted heterocyclic cymantrene
derivatives has been proposed. This method provides a common
approach to the synthesis of cymantrene ensembles with various
azaheterocycles.
’ EXPERIMENTAL SECTION
Figure 3. ORTEP drawing of 5 with 50% probability thermal ellipsoids.
General Procedures. All reactions were carried out under argon
ꢀ
Selected bond distances (Å) and angles (deg): C(6)ꢀC(5), 1.5073(19);
using standard Schlenk techniques. The 1H NMR (400 MHz) and 13
C
N(3)ꢀC(6), 1.4729(16); N(3)ꢀC(14), 1.3577(17); N(2)ꢀC(14),
1.3077(18); N(2)ꢀN(1), 1.4014(16); C(6)ꢀC(7), 1.5186(19); C-
(7)ꢀN(1), 1.2868(17); C(5)ꢀC(6)ꢀC(7), 113.73(11); C(4)ꢀC
(5)ꢀC(6), 127.79(12); N(1)ꢀC(7)ꢀC(6), 120.24(12); N(3)ꢀC-
(6)ꢀC(7), 105.68(10); C(14)ꢀN(3)ꢀC(6), 115.72(11); N(2)ꢀC-
(14)ꢀN(3), 123.29(12); C(14)ꢀN(2)ꢀN(1), 116.51(11); C(7)ꢀ
N(1)ꢀN(2), 120.15(12); N(3)ꢀC(6)ꢀC(5), 111.17(11); C(1)ꢀC-
(5)ꢀC(6), 125.17(13).
NMR (100 MHz) and 2D 13C and 1H NMR spectra were recorded on a
Bruker AVANCE II (400 MHz) instrument. Chemical shifts are given in
δ values (ppm) using TMS as the internal standard and CDCl3 as the
solvent. The mass spectra were measured on a Bruker Daltonics micrO-
TOF-Q II mass spectrometer equipped with an orthogonal electrospray
ionization (ESI) source, a six-port divert valve, and syringe pump kd
Scientific witha flow rate of180μL/h. The IR spectra were recorded using
a Perkin-Elmer Spectrum One B Fourier-transform infrared spectrometer
equipped with a diffuse reflection attachment. The elemental analysis was
carried out on an automated Perkin-Elmer PE 2400 series II CHNS/O
analyzer. The course of the reactions was monitored by TCL on 0.25 mm
silica gel plates (Merck 60F 254). Column chromatography was per-
formed on Alfa Aesar silica gel (Avocado Research Chemical Ltd., silica
gel 60, 0.035ꢀ0.070 mm (220ꢀ440 mesh)). Cymantrene and starting
heterocycles were purchased from Aldrich.
cyclopentadienyl and quinoxaline planes is 9.67(5)°. The dis-
tance from the Mn atom to the centroid of the cyclopentadienyl
ring is 1.772(2) Å. Compound 4h has a laminate molecular
packing characterized by the alternation of the layers of cymantrene
and quinoxaline fragments (Figure 2) oriented in the plane b0c.
There are the following short contacts within the layers: the short
contact between the carbonyl oxygen atoms (O1 O1 [2ꢀx, ꢀy,
3,6-Diphenyl-1,2,4-triazine was prepared according to the published
3 3 3
procedure.19
ꢀz], 3.039(2) Å), the short πꢀπ contact between the quinoxaline
fragments (C2 C8 [x, 0.5ꢀy, 0.5þz], 3.397(2) Å), and the short
Crystallographic Data for 4h and 5. Crystals of 4h and 5 were
obtained by crystallization from diethyl ether as yellow single crystals.
X-ray diffraction analysis was performed on an Xcalibur S X-ray
diffractometer equipped with CDD detector (Mo KR graphite-
3 3 3
πꢀπ contact between the quinoxaline and cymantrene fragments
(C10 C12 [x, 0.5ꢀy, 0.5þz], 3.335(2) Å). The distance
3 3 3
between the Mn atoms in the molecular packing is >6.5 Å.
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Table 2. Rf, IR, Elemental Analysis, and ESI-MS Data for 4aꢀj
Rf (eluent)
IR (cm-1)
elemental analysis
Found: C, 55.27; H, 3.31; N, 4.66
ESI-MS
282
4a
4b
4c
4d
4e
4f
0.5 (benzene/EtOAc, 9.5:0.5)
ν(CO) 2010, 1917
Calc for C13H8MnNO3: C, 55.52; H, 2.85; N, 4.98
Found: C, 59.65; H, 3.11; N, 7.51
0.2 (hexane/EtOAc, 8:2)
0.5 (CH2Cl2)
ν(CO) 2001, 1922, 1908
ν(CO) 2011, 1940, 1911
ν(CO) 2011, 1910
359
332
332
382
283
283
333
383
436
Calc for C18H11MnN2O3: C, 60.34; H, 3.07; N, 7.82
Found: C, 61.35; H, 3.18; N, 4.12
Calc for C17H10MnNO3: C, 61.63; H, 3.02; N, 4.23
Found: C, 61.60; H, 2.88; N, 4.17
0.4 (CH2Cl2)
Calc for C17H10MnNO3: C, 61.63; H, 3.02; N, 4.23
Found: C, 66.12; H, 3.09; N, 3.59 Calc for C21H12MnNO3:
C, 66.14; H, 3.15; N, 3.67
0.3 (benzene/EtOAc, 9.5:0.5)
0.3 (EtOAc)
ν(CO) 2021, 2012, 1923
ν(CO) 2021, 2012, 1929, 1915
ν(CO) 2014, 1913
Found: C, 50.95; H, 2.63; N, 9.55
Calc for C12H7MnN2O3: C, 51.06; H, 2.48; N, 9.93
Found: C, 51.03; H, 2.27; N, 9.93
4g
4h
4i
0.6 (EtOAc)
Calc for C12H7MnN2O3: C, 51.06; H, 2.48; N, 9.93
Found: C, 56.34; H, 3.31; N, 8.57
0.4 (CH2Cl2)
ν(CO) 2016, 1947, 1917
ν(CO) 2012, 1910
Calc for C16H9MnN2O3: C, 57.83; H, 2.71; N, 8.43
Found: C, 62.74; H, 2.95; N, 7.13 Calc for C20H11MnN2O3:
C, 62.83; H, 2.88; N, 7.33
0.4 (hexane/EtOAc, 1:1)
0.5 (benzene/EtOAc, 9.5:0.5)
4j
ν(CO) 2016, 1914
Found: C, 63.49; H, 3.54; N, 9.66
Calc for C23H14MnN3O3: C, 63.45; H, 3.22; N, 9.66
1
monochromated radiation, λ = 0.71073 Å, ω-scanning technique, the
scanning step was 1° and the exposure time per frame was 10 s at 295(2)
K for 4h and 120(2) K for 5. The low temperature was maintained with a
Cryojet (Oxford Instruments) open-flow N2 gas cryostat. Analytical
absorption correction was used in the reflection intensity integration.20
The structure was solved by the direct method and refined applying full
Yield: 350 mg (80%). Mp: 165 °C. Rf = 0.2 (eluent benzene). H
NMR (400 MHz, CDCl3): δ ꢀ4.47 (s, 1H, C5H4), 4.54 (s, 1H, C5H4),
4.82 (s, 1H, C5H4), 4.89 (s, 1H, C5H4), 5.77 (s, 1H, 5-H), 7.49 (m, 6H,
1
Ph), 7.82 (m, 4H, Ph), 8.98 (s, 1H, NH) ppm. H NMR (400 MHz,
(CD3)2CO, 25 °C): δ ꢀ4.74 (m, 2H, C5H4), 4.92 (s, 1H, C5H4), 5.10
(s, 1H, C5H4), 5.76 (s, 1H, 5-H), 7.49 (m, 6H, Ph), 7.97 (t, 2H, 3J = 6.5
Hz, Ph), 8.10 (t, 2H, 3J = 6.5 Hz, Ph), 10.69 (s, 1H, NH) ppm. 1H NMR
(400 MHz, (CD3)2CO, ꢀ75 °C): δ ꢀ4.80 (s, 1H, C5H4), 4.91 (s, 1H,
C5H4), 4.96 (s, 1H, C5H4), 5.29 (s, 1H, C5H4), 5.81 (s, 1H, 5-H), 7.51
(m, 6H, Ph), 8.11 (m, 4H, Ph), 11.29 (s, 1H, NH) ppm. 13C NMR
(100 MHz, CDCl3): δ ꢀ49.79 (C5); 79.51, 81.18, 84.41, 85.03 (CH-Cp);
100.85 (C-Cp); 126.24, 126.56, 128.87, 128.94, 129.90, 131.30 (CH-Ph);
132.20, 134.04 (C-Ph); 143.56 (C6); 153.12 (C3). IR (cmꢀ1): ν(NH)
2954, 2923, 2853, ν(CO) 2012, 1915. ESI-MS: 438. Anal. Found: C,
63.63; H, 3.38; N, 9.34. Calc for C23H16MnN3O3: C, 63.16; H, 3.66;
N, 9.61.
Synthesis of (3,6-Diphenyl-1,2,4-triazin-5-yl)cymantrene,
4j. A solution of DDQ (227 mg, 1 mmol) in THF (5 mL) was added to a
solution of(3,6-diphenyl-2,5-dihydro-2(H)-1,2,4-triazin-5-yl)cymantrene
(3j) (437 mg, 1 mmol) in anhydrous THF (7 mL) at room temperature.
The suspension was immediately filtrated off through the neutral alumina
layer, the alumina layer was repeatedly washed with THF, and the solvent
was evaporated. The residue was purified on silica gel. The eluate was
concentrated to dryness in vacuo.
matrix least-squares against F2 with anisotropic displacement para-
hkl
meters for all non-hydrogen atoms using the SHELX97 program
package.21 All hydrogen atoms were located in different electron density
maps and refined using a riding model with fixed thermal parameters.
General Procedure for the Synthesis of 4a,b,i. A 1.7 M
solution of t-BuLi in pentane (0.71 mL, 1.2 mmol) was added to a
solution of cymantrene (1 mmol) in anhydrous THF (5 mL) under an
atmosphere of argon at ꢀ78 °C. After 40 min stirring of the reaction
mixture the solution of corresponding heterocycles 2a,b,i (1.0 mmol) in
anhydrous THF (7 mL) was added. After stirring the reaction mixture
at ꢀ78 °C for 1.5 h and then for an hour at room temperature, water
(2 mmol) and a solution of DDQ (3.8 mmol) in THF (10 mL) were
added. Finally, the reaction mixture was filtrated off through neutral
alumina and was purified on silica gel (using appropriate solvent as the
eluent). The eluate was concentrated to dryness in vacuo.
General Procedure for the Synthesis of 4cꢀh. The synthetic
approach is similar to the procedure described above: 1.6 M solution of
n-BuLi in hexane (0.76 mL, 1.2 mmol), cymantrene (1 mmol) in dry
THF (5 mL), heterocycles 1cꢀh (1.0 mmol) in anhydrous THF, water
(2 mmol), and DDQ (3.8 mmol) in THF (10 mL).
Experimental data for 4aꢀj are summarized in Tables 2 and 3.
Synthesis of (R,S)-[(3,6-Diphenyl-2,5-dihydro-2(H)-1,2,4-
triazin-5-yl)]cymantrene, 3j. A 1.6 M solution n-BuLi in hexane
(0.76 mL, 1.2 mmol) was added to a solution of cymantrene (204 mg,
1 mmol) in anhydrous THF (5 mL) under an atmosphere of argon
at ꢀ78 °C. After 30 min of stirring of the reaction mixture a solution of 3,
6-diphenyl-1,2,4-triazine (1j) (233 mg, 1 mmol) in anhydrous THF
(7 mL) was added. The reaction mixture was stirred for 1.5 h at ꢀ78 °C
and then for 1 h at room temperature. Finally, the reaction mixture was
purified on silica gel (using benzene as the eluent). The eluate was
concentrated to dryness in vacuo.
Synthesis of (R,S)-[(4-Ethyl-3,6-diphenyl-5(H)-1,2,4-tria-
zin-5-yl)]cymantrene, 5. Sodium hydride (24 mg, 1 mmol) was
added to a solution of ligand 3j (437 mg,1 mmol) in dry THF (10 mL)
under argon at room temperature, and the reaction mixture was stirred
until complete dissolution. Then EtI (0.9 mL, 4 mmol) was added, and
the mixture was stirred at room temperature for 5 h. The solution was
concentrated in vacuo and purified on silica gel. Yield: 279 mg (60%).
1
Mp: 167 °C. Rf = 0.2 (eluent benzene/EtOAc, 9:1). H NMR (400
MHz, CDCl3): δ ꢀ1.03 (t, 3H, 3J = 6.7 Hz, N-CH2-Me), 3.51 (m, 2H,
N-CH2-Me), 4.61 (d, 1H, 3J = 1.5 Hz, C5H4), 4.75 (m, 2H, C5H4), 5.24
3
(t, 1H, J = 1.5 Hz, C5H4), 5.60 (s, 1H, 5-H),7.48 (m, 6H, Ph), 7.80
(t, 2H, 3J = 6.2 Hz, Ph), 8.17 (t, 2H, 3J = 1.5 Hz, Ph) ppm. 13C NMR
(100 MHz, CDCl3): δ ꢀ15.18 (N-CH2-Me); 45.63 (N-CH2-Me);
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Organometallics
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45.68 (C5); 80.21, 81.13, 84.87, 85.16 (CH-Cp); 97.46 (C-Cp); 126.35,
127.80, 128.09, 128.79, 129.29, 130.17 (CH-Ph); 132.81, 133.41 (C-Ph);
148.06 (C6); 151.69 (C3). IR (cmꢀ1): ν(CO) 2015, 1948, 1921. ESI-MS:
466. Anal. Found: C, 64.24; H, 4.56; N, 8.60. Calc for C25H20MnN3O3:
C, 64.52; H, 4.30; N, 9.03.
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’ ASSOCIATED CONTENT
S
Supporting Information. Crystallographic data in CIF
b
format, experimental details, and characterization for other
hetarylcymantrenes. This material is available free of charge via
the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
(14) Enders, M.; Kohl, G.; Pritzkow, H. J. Organomet. Chem. 2001,
622, 66–73.
(15) Chupakhin, O. N.; Charushin, V. N.; van der Plas, H. Nucleo-
philic Aromatic Substitution of Hydrogen; Academic Press: San Diego,
1994; p 367.
Corresponding Author
*E-mail: chupakhin@ios.uran.ru.
’ ACKNOWLEDGMENT
(16) Loim, N. M.; Kondratenko, M. A.; Sokolov, V. I. J. Org. Chem.
This study was financially supported by the Council on Grants
of the President of the Russian Federation (Program for State
Support of Leading Scientific Schools of the Russian Federation,
Grant NSh-65261.2010.3, Grant MK-1901.2011.3) and the
Russian Foundation for Basic Research (Project No. 10-03-
00756-a).
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