Arene complexes of transition metals in reactions with nucleophilic reagents: XXX. Reaction of π-halomesitylene [Tetramethyl(ethyl) cyclopentadienyl]rhodium(II) complexes with anions derived from CH acids

Article abstract of DOI:10.1134/S1070428007120056

Reactions of fluoro-and chloromesitylene π-complexes [(η⁶-1-Hlg-2,4,6-Me₃C₆H₂) (η⁵-C₅EtMe₄)Rh]-(BF₄) ₂ (Hlg = F, Cl) with diethyl malonate anion in THF or a

Full text of DOI:10.1134/S1070428007120056

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 12, pp. 1765–1772. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © L.I. Goryunov, N.M. Romanova, G.S. Zhilovskii, V.D. Shteingarts, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43,
No. 12, pp. 1765–1771.
Arene Complexes of Transition Metals in Reactions
with Nucleophilic Reagents: XXX.* Reaction of π-Halomesitylene
[Tetramethyl(ethyl)cyclopentadienyl]rhodium(II) Complexes
with Anions Derived from CH Acids
L. I. Goryunova, N. M. Romanovaa, b, G. S. Zhilovskiic, and V. D. Shteingartsa, c
a Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 9, Novosibirsk, 630090 Russia
e-mail: shtein@nioch.nsc.ru
b Novosibirsk State Pedagogical University, Novosibirsk, Russia
c Novosibirsk State University, Novosibirsk, Russia
Received November 22, 2006; revised July 12, 2007
Abstract—Reactions of fluoro- and chloromesitylene π-complexes [(η6-1-Hlg-2,4,6-Me3C6H2)(η5-C5EtMe4)Rh]-
(BF4)2 (Hlg = F, Cl) with diethyl malonate anion in THF or acetone-d6 at 20°C initially (within the first 5–
30 min) involve nucleophile addition at unsubstituted carbon atom in the arene ligand with formation of
π-cyclohexadienyl complexes {[η5-1-(EtOCO)2CH-1-H-3-Hlg-2,4,6-Me3C6H2](η5-C5EtMe4)Rh}(BF4). The sub-
sequent replacement of the halogen atom yields {[η6-1-(EtOCO)2CH-2,4,6-Me3C6H2](η5-C5EtMe4)Rh}(BF4)2,
where the arene ligand is readily withdrawn from π-coordination by the action of chloride ion or the solvent.
Dimethyl mesitylmalonate was isolated in 76% yield. Likewise, the reactions with anions derived from
malononitrile and ethyl cyanoacetate gave 25–38% of the corresponding derivatives 1-R-2,4,6-Me3C6H2 where
R = (NC)2CH or EtOCO(NC)CH.
DOI: 10.1134/S1070428007120056
Activation of haloarenes via π-coordination to tri-
carbonylchromium, cyclopentadienyliron, and cyclo-
pentadienylruthenium complexes is widely used in
reactions leading to formation of new Carom–C bonds
as a result of nucleophilic replacement of the halogen
atom (fluorine or chlorine) by anions derived from CH
acids [2–4]. Arenes modified in such a way are with-
drawn from the π-complexes containing Cr(CO)3 or
FeC5H5 fragments by oxidation or pyrolysis which
leads to decomposition of the complexes. Moriarty
et al. [3] succeeded in replacing the RuC5H5 fragment
by the action of acetonitrile under irradiation and ob-
tained the complex (MeCN)3RuC5H5(PF6) which can
be used repeatedly [3]. Dicationic cyclopentadienyl-
rhodium fragments exert a powerful activating effect,
which is comparable with the overall effect of three
nitro groups in the ortho and para positions with
respect to halogen; in addition, these fragments are
capable of readily exchanging π-coordinated arene
ligands. As a result, catalytic aromatic nucleophilic
substitution of halogen atoms by alkoxy groups has
become possible [5]. Therefore, synthesis of π-halo-
Scheme 1.
Me
Me
Hlg
Me
Hlg
MeNO2, 100°C, 2–3 h
RhL(BF4)2
+
RhL(BF4)2
Me
–PhH
Me
Me
II
Ia, Ib
L = C5EtMe4, Hlg = F (a, 90%), Cl (b, 93%).
* For communication XXIX, see [1].
1765

GORYUNOV et al.
1766
arene rhodium(III) complexes and their reactions with
CH acid anions attract interest.
lene π-complex [(η6-1,3,5-Me3C6H3)(η5-C5EtMe4)Rh]-
(BF4)2 (Ic). Signals from carbon atoms in the methyl
and ethyl groups of the pentaalkylcyclopentadienyl
fragment are observed at δC 8.5–10.8, 10.8–12.8 (CH3)
and 17.4–18.9 ppm (CH2). Carbon nuclei in the cyclo-
pentadienyl ring resonate at δC 109.5–114.8 (C2, C5),
108.4–113.8 (C3, C4), and 111.8–117.0 ppm (C1); the
downfield signal belongs to the carbon atom bearing
ethyl group. The C1–C5 signals are split into doublets
due to coupling with rhodium, J(103Rh–13C) = 7–9 Hz.
Aromatic carbon atoms give rise to signals in the
regions δC 105.7–107.6 (CH, cf. δC 106.6 ppm for
benzene complex II) and 113.0–123.2 ppm (CMe). All
aromatic carbon signals are split into doublets with
a coupling constant J(103Rh–13C) of 3–5 Hz, indicating
η6-coordination to the rhodium atom [13]. Methyl car-
bon atoms in coordinated mesitylene and chloromes-
itylene and the methyl carbon atom in the para posi-
tion with respect to fluorine in fluoromesitylene are
characterized by similar chemical shifts (δC 17.4–
17.9 ppm), while signals from the o-methyl groups in
the latter appear in a stronger field (δC 12.1 ppm) and
are split into doublets due to coupling with fluorine,
JCF = 2 Hz. The effect of the chlorine atom in the
benzene ring of Ib on the chemical shift of the adjacent
carbon atom (δC 122.4 ppm) is comparable with that of
methyl group, but no appreciable effect of chlorine on
the position of the other aromatic carbon signals is
observed. The presence of fluorine atom in complex Ia
leads to a considerable downfield shift of the C–F
carbon signal (δC 141.2 ppm) and an appreciable
upfield shift of signals from the neighboring carbon
atoms (δC 113.0 ppm). All aromatic carbon nuclei in
complex Ia (except for C4) show coupling with fluor-
ine: JCF = 285 (C1), 17 (C2, C6), 6 Hz (C3, C5).
In the present work we examined reactions of
1-fluoro- and 1-chloro-2,4,6-trimethylbenzene com-
plexes [(η6-1-Hlg-2,4,6-Me3C6H2)(η5-C5EtMe4)Rh]-
(BF4)2 as model substrates with anions derived from
diethyl malonate, malononitrile, and ethyl cyanoace-
tate. These complexes were synthesized previously
from the benzene-containing analog [(η6-C6H6)-
(η5-C5EtMe4)Rh](BF4)2 (II) via ligand exchange, and
complex Ia was generated only in situ [5, 6]. We
have isolated complex Ia in 90% yield according to
Scheme 1 under the conditions analogous to those re-
ported for the synthesis of individual complex Ib [6].
Several procedures have been proposed for the pre-
paration of benzene complex II. These procedures are
based on generation of [(η5-C5EtMe4)Rh]2+ dication
via elimination of chloride ions from the complex
[(η5-C5EtMe4)RhCl2]2 by the action of strong acids
(such as CF3COOH [7] or H2SO4 [8]) or anhydrous
silver salts (AgBF4 [9] or AgBF4 ·C6H6 [10]). In the
present work we used AgBF4 complex with 1,4-di-
oxane; this complex is nonhygroscopic, and it can be
stored for several months in the dark at room tempera-
ture [11]. Complex II was thus obtained in a fairly
high yield (74%). Taking into account simplicity of
the preparation of the reagent and complex II, our
modification may be regarded as convenient and
efficient.
π-Haloarene rhodium complexes Ia and Ib were
examined by 13C NMR spectroscopy (see table). The
given data are very consistent with those reported pre-
viously for benzene rhodium(III) complexes [12] and
the data obtained in the present work for the mesity-
13C NMR spectra of complexes [(η6-(1-X-2,4,6-Me3C6H2)(η5-C5EtMe4)Rh](BF4)2 [Ia–Ic; X = F (a), Cl (b), H (c)]
13C NMR spectrum, δC, ppm (JRh,C, Hz)
Complex
no.
1-X-2,4,6-Me3C6H2
1-Et-C5Me4
Et
Me
Iaa
141.2 d.d (4) (C1, JCF = 285), 113.0 d.d (3) (C2, 112.1 (8) (C3, C4), 113.2 (7) (C2, C5), 11.7 (CH3), 8.8, 9.1
C6, JCF = 17), 107.6 t (C3, C5, JCF ≈ JRh,C ≈ 6), 114.7 (8) (C1)
17.6 (CH2)
120.7 (4) (C4), 12.1 d (2-CH3, 6-CH3, JCF
=
2 Hz), 17.4 (4-CH3)
Iba
Icb
122.4 (4) (C1), 122.3 (4) (C2, C6), 107.1 (5) (C3, 111.8 (8) (C3, C4), 112.9 (8) (C2, C5), 11.5 (CH3), 8.5, 8.8
C5), 120.8 (4) (C4), 17.7 (2-CH3, 6-CH3), 17.5 114.3 (8) (C1)
(4-CH3)
17.4 (CH2)
123.2 (4) (C1, C3, C5), 105.7 (3) (C2, C4, C6), 17.9 111.1 (9) (C3, C4), 112.2 (7) (C2, C5), 11.9 (CH3), 9.1, 9.4
(CH3) 17.8 (CH2)
113.8 (8) (C1)
a
In MeNO2–acetone-d6.
In MeNO2.
b
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 12 2007

ARENE COMPLEXES OF TRANSITION METALS ... XXX.
1767
Scheme 2.
Me
Me
Me
RhL(BF4)2
XO–, CD3COCD3
24 h
XO
Me
O
O
X
1/2
(BF4)3
–HBF4
Me
Me
Me Me
RhL
Me
RhL
IVa
IVb
Me
Me
RhLBF4
RhL(BF4)2
Me
MCH(COOEt)2
20°C
F
F
5
1
MBF4
Me
Me
Me
α
H
CH(COOEt)2
Ia
IIIa
Me
MCH(COOEt)2
(1) THF, 48 h
(2) CF3COOH, MeNO2
CH(COOEt)2
+
SnRhLA2
Me
Me
V (76%)
VIa
L = C5EtMe4; M = Li, Na; X = H, D; S is solvent; A = BF4, CH(COOEt)2.
Scheme 3.
Me
Me
CH(COOEt)2
Cl
CD3COCD3, 48 h
+
SnRhLA2 +
Me
Me
Me
Me
V (50%)
VIb
50%
Me
Me
RhLBF4
RhL(BF4)2
MCH(COOEt)2
20°C
Cl
Cl
5
1
MBF4
Me
Me
Me
Me
α
H
CH(COOEt)2
Ib
IIIb
Me
Me
MCH(COOEt)2
(1) THF-d8, 24 h
(2) MeNO2, 1 h
CH(COOEt)2
Me
Cl
+
V
+
VIb +
Me
Me
Me
RhL(BF4)2
VII (40%)
10%
50%
L = C5EtMe4; M = Li, Na; S is solvent; A = Cl, BF4, CH(COOEt)2.
According to the 1H and 19F NMR data, reactions of
complexes Ia and Ib with [CH(COOEt)2]– ion generat-
ed from diethyl malonate and MeONa, EtONa, NaH,
or LiH initially (within 5–30 min) give {2–6-η-1-exo-
[bis(ethoxycarbonyl)methyl]-3-fluoro-2,4,6-trimethyl-
cyclohexadienyl}(η5-tetramethylethylcyclopentadi-
enyl)rhodium(III) (IIIa) (Scheme 2) and {2_6-η-1-exo-
[bis(ethoxycarbonyl)methyl]-3-chloro-2,4,6-trimethyl-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 12 2007

GORYUNOV et al.
1768
cyclohexadienyl}(η5-tetramethylethylcyclopentadi-
enyl)rhodium(III) (IIIb) (Scheme 3), respectively.
Complex IIIa displayed the following signals in the
products formed from complex Ib and diethyl malo-
nate anion in acetone-d6 was 50% (Scheme 3). After
keeping the mixture for 12–24 h at 20°C, signals of
complex IIIb disappeared from the spectrum, and the
final products were compounds V and VIb and un-
coordinated chloromesitylene. Unlike the reaction with
fluoromesitylene complex Ia, no 2,4,6-trimethylphenol
complex IV was detected. A probable reason is higher
affinity of the chloromesitylene complex, which is
a softer electrophile than its fluorine-containing ana-
log, for relatively soft [CH(COOEt)2]– nucleophile
rather than for hard D(H)O– species.
1H NMR spectrum, δ, ppm: 5.41 d (1H, 5-H, JHF
=
4 Hz), 3.83 m (1H, 1-H, JHH = 4 Hz), 3.11 d (1H, α-H,
JHH = 4 Hz). Likewise, signals at δ 5.47 (s, 1H, 5-H),
3.87 (d, 1H, 1-H, JHH = 4 Hz), and 3.08 ppm (d, 1H,
α-H, JHH = 4 Hz) were assigned to complex IIIb.
Analogous reaction of mesitylene complex Ic with
diethyl malonate in the presence of a base gave a mix-
ture of {2,6-η-1-exo-[bis(ethoxycarbonyl)methyl]-
2,4,6-trimethylcyclohexadienyl}(η5-tetramethylethyl-
cyclopentadienyl)rhodium(III) tetrafluoroborate (IIIc)
(70%) and solvate complex VIa (30%).
Another specificity of the transformation of chloro-
mesitylene complex Ib is that the reaction mixture
contains chloride ions. The latter are capable of effec-
tively interacting with the metal-containing fragment
[(C5EtMe4)Rh]2+ with liberation of the arene and
Me
RhLBF4
5
1
formation of solvate complex like VIb. The H NMR
1
Me
Me
α
spectrum of the reaction mixture in THF-d8, recorded
in 30 min after mixing the reactants, contained signals
of cyclohexadienyl complex IIIb whose fraction at-
tained 82%. In addition, initial complex Ib, uncoor-
dinated chloromesitylene, and solvate complex VIb
were present. After 3 h, a large amount of a solid mate-
rial separated from the reaction mixture. Presumably,
this material was [η6-1-bis(ethoxycarbonyl)methyl-
2,4,6-dimethylbenzene](η5-tetramethylethylcyclo-
pentadienyl)rhodium(III) tetrafluoroborate (VII) which
(as might be expected) is poorly soluble in THF. When
the mixture was kept for 24 h more and nitromethane
H
CH(COOEt)2
IIIc
1
The following signals in the H NMR spectrum of
the product mixture were assigned to complex IIIc, δ,
ppm: 5.26 s (2H, 3-H, 5-H), 4.08 q (4H, OCH2, J =
7.0 Hz), 3.63 d (1H, 1-H, J = 5.0 Hz), 2.97 d (1H, α-H,
J = 5.0 Hz), 2.35 q (2H, CH2CH3, J = 7.5 Hz), 2.26 s
(3H, CH3), 1.94 s (6H, CH3), 1.92 s (6H, CH3), 1.18 t
(6H, CH3, J = 7.0 Hz), 1.06 t (3H, CH2CH3, J =
1
7.5 Hz). The H NMR parameters of complexes IIIa–
IIIc are very consistent with each other and those
reported previously for cyclohexadienyl complexes ob-
tained from acetylacetone or methyl ketone anion and
benzene [9] or p-xylene [14] pentaalkylcyclopentadi-
enyl rhodium complexes. The 19F NMR spectrum of
the product mixture obtained from complex Ia con-
tained a signal at δF 18.4 ppm (cf. δF 36.2 ppm for Ia).
1
was added, the precipitate dissolved. In the H NMR
spectrum of the solution thus formed we observed
a singlet at δ 7.36 ppm, which is likely to belong to
protons in the aromatic ring of complex VII. Its frac-
tion among the products was ~40%, but we failed to
isolate it as individual substance because of its trans-
formation into compounds V and VIb. Treatment of
a solution of [(η5-C5EtMe4)RhCl2]2 in nitromethane
with AgBF4 in the presence of excess diethyl mesityl-
malonate gave a mixture which contained (according
The fraction of IIIa in the reaction mixtures in
acetone-d6 or THF was 50 and 80%, respectively.
When the reaction mixture in acetone-d6 was kept for
24 h, dimeric complex IVb was obtained (see Experi-
mental), presumably as a result of replacement of the
fluorine atom by H(D)O– anion generated from water
present in the solvent. Using tetrahydrofuran as sol-
vent, we isolated diethyl mesitylmalonate (V) in 76%
yield. Compound V was synthesized previously in
65% yield by reaction of ethyl mesitylacetate with
diethyl oxalate [15].
1
to the H NMR data) up to 70% of complex VII.
Obviously, it was formed according to Scheme 4.
Apart from the aromatic proton signal at δ 7.36 ppm,
the 1H NMR spectrum of the mixture contained signals
at δ 2.4–2.6 and 2.0–2.1 ppm, which are typical of
methyl protons in the arene and cyclopentadienyl
ligands in rhodium(III) π-complexes [5, 6, 9, 12].
With a view to extend the series of CH acids
capable of reacting with complexes Ia and Ib we
examined their reactions with malononitrile in the
1
According to the H NMR spectra of the reaction
mixtures, the fraction of complex IIIb among the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 12 2007

ARENE COMPLEXES OF TRANSITION METALS ... XXX.
1769
Scheme 4.
Me
CH(COOEt)2
Me
CH(COOEt)2
2AgBF4, MeNO2, 20°C, 0.5 h
–2AgCl
Me
Me
1/2(LRhCl2)2
[(MeNO2)nRhL](BF4)2
Me
Me
RhL(BF4)2
VII (70%)
L = C5EtMe4.
Scheme 5.
Me
Me
CHYZ
Cl
S, 20°C, 24 h
Ia, Ib
+
NaCHYZ
SmRhLA2 + SnRhLA2 +
Me
Me
Me
Me
VIII
VIa, VIb
Me
CHYZ
Me
150°C (0.1 mm)
VIII
Me
IX (30–38%), X (30%)
L = C5EtMe4; Hlg = F, Cl; S = CD3COCD3, THF; A = BF4, Cl; IX, Y = Z = CN; X, Y = CN, Z = COOEt.
presence of sodium carbonate in acetone-d6 and with
ethyl cyanoacetate sodium salt (generated by the action
of sodium hydride) in THF. According to the 1H NMR
data, these reactions resulted in the formation of un-
coordinated halomesitylenes and complexes like VIII
and VI (Scheme 5). The latter displayed signals in the
region δ 1.5–1.8 ppm, which are typical of methyl
groups in the cyclopentadienyl ligand in rhodium(III)
solvate complexes [5, 6, 16]. In this case, no appreci-
able amounts of cyclohexadienyl complexes analogous
to IIIa or IIIb were formed. Presumably, the reason is
that malononitrile and ethyl cyanoacetate (pKa 11–12
and 9, respectively [17]) are considerably stronger CH
acids than diethyl malonate (pKa 13); therefore, the
equilibrium in the formation of complexes like IIIa or
IIIb is displaced almost completely toward initial
compounds Ia and Ib, as it was reported for arene
(tricarbonyl)chromium complexes [2].
mesitylene and malononitrile in basic medium in the
presence of CuI [18]. Analogous transformations of
bromoarenes are characterized by poor yields, while
chloroarenes fail to react at all. Compound X was
synthesized previously from 2,4,6-trimethylbenzoni-
trile and diethyl carbonate (yield 41%) [19], as well as
from bromomesitylene and ethyl cyanoacetate in the
presence of Pd complex as catalyst (yield 88%) [20].
Taking into account that the coordination entity
[(η5-C5EtMe4)Rh]2+ is very stable, it seemed to be pos-
sible to recycle it via transformation into the initial
complexes. In fact, treatment of solvate complexes
VIb, formed in the reaction of Ib with diethyl malo-
nate anion in THF, with benzene or chloromesitylene
with addition of AgBF4 gave complexes II (80%) and
Ib (86%), respectively. Thus we have demonstrated the
possibility for repeated use of the activating cyclo-
pentadienylrhodium fragment in the above transforma-
tions which can be regarded as occurring in a pseudo-
catalytic way.
The isolation of mesitylmalononitrile (IX) and
ethyl mesityl(cyano)acetate (X) was more difficult as
compared to diethyl mesitylmalonate, and it required
pyrolytic vacuum distillation (see Experimental); their
yields were 38 and 25%, respectively. Compound IX
was prepared previously in 54% yield from iodo-
On the whole, our results show prospects in using
π-coordination with rhodium(III)-based complexes as
a method for activation of haloarenes to reactions with
anions derived from CH acids.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 12 2007

GORYUNOV et al.
1770
EXPERIMENTAL
tion, washed with diethyl ether (2×10 ml), and dried
for 1 h at 20°C under reduced pressure (0.1 mm). Yield
1.26 g (74%). The H NMR spectrum of II was con-
sistent with that reported in [7].
1
The NMR spectra were recorded on Bruker WP-
1
200SY (200.13 MHz for H and 188.28 MHz for 19F)
and Bruker AM-400 spectrometers (100.61 MHz for
13C). The chemical shifts were measured relative to
acetone-d6 (1H, δ 2.04 ppm), MeNO2 (1H, δ 4.29 ppm),
CDCl3 (13C, δC 76.09 ppm), and C6F6 (19F, δF 0.0 ppm).
Reaction of complex Ia with diethyl malonate.
a. A solution of 0.02 g (0.355 mmol) of sodium meth-
oxide in 0.24 ml of methanol and 0.113 g (0.71 mmol)
of diethyl malonate were placed into a reactor con-
nected to a high-vacuum setup. The mixture was
stirred for 30 min at 20°C under argon, the solvent was
distilled off under reduced pressure (0.06 mm), 0.2 g
(0.36 mmol) of complex Ia and 0.5 ml of acetone-d6
were added, and the mixture was stirred at 0–15°C.
Nitromethane was kept for 24 h over P2O5 and dis-
tilled twice, a fraction with bp 101°C being collected.
Benzene of chemically pure grade was purified by
distillation, bp 80°C. Diethyl ether was distilled and
dried first over CaCl2 and then over sodium. Diethyl
malonate of pure grade was distilled (bp 165°C) and
stored over 3-Å molecular sieves. Acetone-d6 was kept
for 48 h over anhydrous potassium carbonate and was
distilled under reduced pressure into a receiver con-
taining 3-Å molecular sieves. Tetrahydrofuran and
THF-d8 were purified by treatment with potassium di-
phenylketyl. Malononitrile of pure grade was purified
by chromatography on aluminum oxide using diethyl
ether as eluent and was dried by evacuation at
a residual pressure of 0.06 mm. Ethyl cyanoacetate
was distilled under reduced pressure (0.06 mm). Tris-
(1,4-dioxane)silver tetrafluoroborate was prepared ac-
cording to the procedure reported in [11]. The com-
plexes [(η6-1,3,5-Me3C6H3)(η5-C5EtMe4)Rh](BF4)2 [3]
and [(η6-1-Cl-2,4,6-Me3C6H2)(η5-C5EtMe4)Rh](BF4)2
[4] were synthesized by known methods.
1
The reaction course was monitored by H and 19F
NMR spectroscopy in 5-min intervals and after 24 h.
2,4,6-Trimethylphenol complex IV was isolated and
identified as described in [6].
b. A reactor was charged under argon with 0.016 g
(0.67 mmol) of sodium hydride and 0.137 g
(0.85 mmol) of diethyl malonate, the reactor was
evacuated, ~2 ml of THF was condensed thereto, and
the mixture was stirred until hydrogen no longer
evolved. Complex Ia, 0.235 g (0.42 mmol), was then
added, the mixture was stirred for 48 h, 4 drops of
CF3COOH and ~1 ml of MeNO2 were added, the
mixture was filtered, and the filtrate was evaporated at
20°C under reduced pressure (0.06 mm). The residue
was treated with hexane (3 ×2 ml), the extract was
evaporated, and the residue was purified by thin-layer
chromatography (Silufol, hexane–CH2Cl2, 1:1). Yield
of diethyl mesitylmalonate (V) 0.089 g (76%).
1H NMR spectrum, δ, ppm: 6.85 s (2H), 2.30 s (6H),
2.24 s (3H), 1.25 t (6H, J = 7.5 Hz), 4.20 q (4H, J =
7.5 Hz), 4.97 s (1H).
Complex (Ia). A mixture of 0.915 g (1.82 mmol) of
complex II, 0.456 g (3.30 mmol) of fluoromesitylene,
and 4 ml of nitromethane was heated for 2 h at the
boiling point with simultaneous removal of the liberat-
ed benzene by distillation. The mixture was diluted
with ~5 ml of diethyl ether, and the crystalline product
was separated by centrifugation, washed with diethyl
ether (3×5 ml), and dried for 2 h at 20°C in a vacuum
Reaction of complex Ib with diethyl malonate.
a. A reactor was charged under argon with 0.002 g
(0.24 mmol) of LiH and 0.035 g (0.22 mmol) of di-
ethyl malonate. The mixture was evacuated and stirred
for 30 min, excess diethyl malonate was distilled off
under reduced pressure (0.05 mm), 0.116 g (0.20 mmol)
of complex Ib and 0.5 ml of acetone-d6 were added,
and the mixture was stirred for 15 min and analyzed by
1H NMR spectroscopy. The mixture was then stirred
for 48 h, 2 drops of hydrochloric acid were added, and
the solvent was distilled off under reduced pressure
(water-jet pump). The residue was extracted with di-
ethyl ether (4×5 ml), the solvent was distilled off, and
the residue was purified by TLC (Silufol, hexane–
CH2Cl2, 1:1). Yield of V 0.031 g (56%).
1
(0.1 mm). Yield 0.92 g (90%). The H and 19F NMR
spectra were consistent with those given in [3]. The
13C NMR spectrum of Ia is given in table. Found, %:
C 42.67; H 5.14; F 30.20. C20H28B2F9Rh. Calculated,
%: C 42.59; H 5.01; F 30.32.
Complex (II). A mixture of 1.10 g (1.7 mmol) of
[(C5EtMe4)RhCl2]2, 3.16 g (6.8 mmol) of AgBF4 ·
3C4H8O2, 0.5 ml of benzene, and 2.5 ml of nitro-
methane was stirred for 10 min under argon. The pre-
cipitate of AgCl was separated by centrifugation, the
liquid phase was diluted with ~60 ml of diethyl ether,
and the colorless crystals were separated by centrifuga-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 12 2007

ARENE COMPLEXES OF TRANSITION METALS ... XXX.
1771
b. A reactor was charged with 0.015 g (0.66 mmol)
of metallic sodium, 0.2 ml of ethanol was condensed
thereto under reduced pressure (0.06 mm), and the
mixture was stirred until the sodium dissolved com-
pletely. Diethyl malonate, 0.147 g (0.92 mmol), was
then added under argon, the mixture was stirred for
30 min, the solvent was distilled off under reduced
pressure (0.06 mm), 0.367 g (0.63 mmol) of complex
Ib was added, and ~1 ml of THF-d8 was condensed
thereto. The mixture was stirred for 10 min and
analyzed by 1H NMR spectroscopy. After 24 h, THF-d8
was distilled off under reduced pressure, and the
residue was dissolved in nitromethane and analyzed by
1H NMR spectroscopy.
Reaction of complex Ib with ethyl cyanoacetate.
A reactor was charged under argon with 0.054 g
(0.19 mmol) of sodium hydride, 0.039 g (0.35 mmol)
of ethyl cyanoacetate, and ~1 ml of THF. The mixture
was stirred for 30 min, 0.100 g (0.17 mmol) of com-
plex Ib was added, the mixture was stirred for 24 h,
one drop of hydrochloric acid was added, and the
solvent was distilled off under reduced pressure
(0.04 mm). The residue was heated at 150–200°C
under reduced pressure (0.04 mm), and the distillate
collected in a cooled receiver was subjected to thin-
layer chromatography (Silufol, hexane–CH2Cl2, 1:1)
to isolate 0.01 g (25%) of ethyl cyano(mesityl)acetate
1
(X). The H NMR spectrum of the product was iden-
tical to that given in [19].
Reaction of complex Ic with diethyl malonate.
Diethyl malonate, 0.073 g (0.416 mmol), was added to
a solution of 0.04 g (0.364 mmol) of potassium tert-
butoxide in 0.45 ml of t-butyl alcohol, the mixture was
stirred for 5 min under argon, 0.19 g (0.35 mmol) of
complex Ic and 0.5 ml of acetone were added, and the
mixture was stirred for 10 min and diluted with ~5 ml
of diethyl ether. The precipitate was separated by
centrifugation, washed with ~5 ml of diethyl ether, and
dried for 1 h under reduced pressure (water-jet pump)
at 20°C. The product was 0.150 g (~70%) of a mixture
of complexes IIIc and VIa at a molar ratio of 7:3.
This study was performed under financial support
by the Ministry of Education of the Russian Federation
(project no. 2000.5.90).
REFERENCES
1. Goryunov, L.I. and Shteingarts, V.D., Russ. J. Org.
Chem., 1999, vol. 35, p. 246.
2. Semmelhack, M.F., Comprehensive Organometallic
Chemistry II, Abel, E.W., Stone, F.G.A., and Wilkin-
son, G., Eds., Oxford: Pergamon, 1995, vol. 12, p. 979.
3. Moriarty, R.M., Ku, Y.-Y., and Gill, U.S., J. Chem. Soc.,
Chem. Commun., 1987, p. 1493.
Reaction of complex Ia with malononitrile.
A mixture of 0.113 g (0.20 mmol) of complex Ia,
0.02 g (0.37 mmol) of sodium carbonate, 0.015 g
(0.22 mmol) of malononitrile, and 0.5 ml of acetone-d6
was stirred for 5 h. The mixture was filtered, the
filtrate was evaporated, and the residue was heated at
110–220°C under reduced pressure (0.065 mm). The
distillate collected in a cooled receiver was subjected
to thin-layer chromatography (Silufol, hexane–CH2Cl2,
1:1) to isolate 0.014 g (38%) of mesitylmalononitrile
4. Moriarty, R.M., Ku, Y.-Y., and Gill, U.S., Organo-
metallics, 1988, vol. 7, p. 660.
5. Goryunov, L.I., Terent’eva, Yu.A., Litvak, V.V., and
Shteingarts, V.D., Zh. Org. Khim., 1990, vol. 26,
p. 1058.
6. Goryunov, L.I. and Shteingarts, V.D., Zh. Org. Khim.,
1991, vol. 27, p. 1144.
7. Rybinskaya, M.I., Kudinov, A.R., and Kaganovich, V.S.,
J. Organomet. Chem., 1983, vol. 246, p. 279.
1
(IX). H NMR spectrum, δ, ppm: 6.94 s (2H), 2.47 s
(6H), 2.27 s (3H), 5.27 s (1H).
8. Kaganovich, V.S., Kudinov, A.R., and Rybinskaya, M.I.,
Metalloorg. Khim., 1988, vol. 1, p. 294.
Reaction of complex Ib with malononitrile.
A mixture of 0.116 g (0.20 mmol) of complex Ib,
0.053 g (0.5 mmol) of sodium carbonate, 0.0146 g
(0.22 mmol) of malononitrile, and 0.5 ml of acetone-d6
was stirred for 48 h using a magnetic stirrer. The mix-
ture was filtered, the filtrate was evaporated, and the
residue was heated at 110–220°C under reduced pres-
sure (0.06 mm). The distillate collected in a cooled
receiver was subjected to thin-layer chromatography
(Silufol, hexane–CH2Cl2, 1:1) to isolate 0.011 g (30%)
of mesitylmalononitrile (IX).
9. Bailey, N.A., Blunt, E.H., Fairhurst, G., and White, C.,
J. Chem. Soc., Dalton Trans., 1980, p. 829.
10. Goryunov, L.I. and Nikitin, Yu.M., Russ. J. Gen. Chem.,
1994, vol. 64, p. 648.
11. Lapitskaya, M.A., Mel’nikova, V.I., Vorob’eva, L.G.,
Kerzina, Z.A., and Pivnitskii, K.K., Zh. Obshch. Khim.,
1990, vol. 60, p. 1496.
12. Goryunov, L.I., Nikitin, Yu.M., and Shteingarts, V.D.,
Russ. J. Org. Chem., 1998, vol. 34, p. 1645.
13. Espinet, P., Bailey, P.M., Downey, R.F., and Mait-
lis, P.M., J. Chem. Soc., Dalton Trans., 1980, p. 1048.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 12 2007

GORYUNOV et al.
1772
14. Fish, R.H., Kim, H.S., Fong, R.H., and Adams, R.D.,
18. Suzuki, H., Kobayashi, T., and Osuka, A., Chem. Lett.,
Organometallics, 1990, vol. 9, p. 1327.
1983, vol. 12, p. 589.
15. Van Zanter, B. and Nauta, W., Recl. Trav. Chim. Pays–
Bas, 1960, vol. 79, p. 1211.
16. Houghton, R.P., Voyle, M., and Price, R., J. Chem. Soc.,
Perkin Trans. 1, 1984, p. 925.
19. De Jongh, H.A.P., De Jongh, C.R.H.I., Sinnige, J.M., De
Klein, W.J., Huysmans, W.G.B., Mijs, M.J., Van den
Hoek, W.J., and Smidt, J., J. Org. Chem., 1972, vol. 37,
p. 1960.
17. Gordon, A.J. and Ford, R.A., The Chemist’s Com-
panion, New York: Wiley, 1972.
20. You, J. and Verkade, J.G., J. Org. Chem., 2003, vol. 68,
p. 8003.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 12 2007