Dinuclear ruthenium(I) triazenide complexes as catalysts for carbenoid cyclopropanation reactions

Article abstract of DOI:10.1515/znb-2004-0516

The ability of ruthenium(I) triazenide complexes [Ru(CO) ₃(ArNNNAr)]₂ (Ar = C₆H₄-4-X, X = CH₃, Cl, Br) to catalyze the cyclopropanation of alkenes with methyl diazoacetate is investigated. With terminal alkenes (styrene, ethyl vinyl ether, 1-hexene), the cyclopropanecarboxylic esters are formed in good to high yield and with an E:Z diastereoisomer ratio of about 1.0 in most cases. 2-Methyl-2-butene is cyclopropanated in low yield but with a syn-selectivity up to 90:10.

Full text of DOI:10.1515/znb-2004-0516

Dinuclear Ruthenium(I)Triazenide Complexes as Catalysts for Carbenoid
Cyclopropanation Reactions
Claus-Dieter Leger and Gerhard Maas
Abteilung Organische Chemie I, Universita¨t Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
Reprint requests to Prof. Dr. G. Maas. Fax: +49(731)5022803.
E-mail: gerhard.maas@chemie.uni-ulm.de
Z. Naturforsch. 59b, 573 – 578 (2004); received January 13, 2004
The ability of ruthenium(I) triazenide complexes [Ru(CO)3(ArNNNAr)]2 (Ar = C6H4-4-X, X =
CH3, Cl, Br) to catalyze the cyclopropanation of alkenes with methyl diazoacetate is investigated.
With terminal alkenes (styrene, ethyl vinyl ether, 1-hexene), the cyclopropanecarboxylic esters are
formed in good to high yield and with an E : Z diastereoisomer ratio of about 1.0 in most cases.
2-Methyl-2-butene is cyclopropanated in low yield but with a syn-selectivity up to 90:10.
Key words: Catalysis, Cyclopropanation, Diazo Compounds, Ruthenium Complexes,
Triazenide Ligands
Introduction
The inter- and intramolecular cyclopropanation of
alkenes by carbenoid reaction with aliphatic diazo
compounds is effectively catalyzed by several late tran-
sition metal complexes of which those based on cop-
per, rhodium, and (to a lesser extent) palladium are the
most important ones [1]. In the past decade, a variety of
ruthenium complexes have been found to catalyze car-
benoid cyclopropanation reactions [2, 3]. Ruthenium
catalysts currently emerge as interesting alternatives to
the established rhodium catalysts not only because of
the significantly lower price of ruthenium but also be-
cause the rich coordination chemistry of ruthenium –
compared to the rhodium catalysts which are almost
exclusively dinuclear rhodium carboxylates, amidates
and phosphates – could offer a wider range of possibil-
ities to control the chemo-, regio- and stereoselectiv-
ity of catalytic cyclopropanation reactions and of other
carbene transfer reactions as well.
We have recently identified a dinuclear ruthenium(I)
carboxylate complex, [Ru2(CO)4(µ-OAc)2]n (1), as a
suitable catalyst for the cyclopropanation of a wide
range of nucleophilic alkenes with diazoacetic esters
[4, 5], (trialkylsilyl)diazoacetic esters [6], (trimethylsi-
lyl)diazomethane [7], and aryldiazomethanes [7]. A
characteristic structural feature of 1 is its sawhorse
configuration, with Ru–Ru–C(O) angles larger and
Ru–Ru–O angles smaller than 90◦, which is proba-
bly responsible for the unusual syn-selectivity in the
cyclopropanation of trisubstituted alkenes. Based on
these results, we turned our attention to analogues
of 1 in which the acetato bridges are replaced by
1,3-diaryltriazenido ligands and evaluated their perfor-
mance as catalysts for alkene cyclopropanation with
methyl diazoacetate.
Results and Discussion
Synthesis and structural characterization of complexes
3a−c
The synthesis of the dinuclear ruthenium(I) tri-
azenide complexes 3a,b from 1,3-diaryltriazenes 2a,b
and Ru3(CO)12 has been described [8]. We prepared
triazenes 2a– c according to a published procedure for
the preparation of 1-methyl-3-p-tolyltriazene[9] by di-
azotization of the corresponding p-substituted anilines
followed by coupling with the same anilines in a basic
medium (see Experimental Section). Chromatographic
purification of the triazenes was not successful, be-
cause they were not stable towards silica gel and could
not be recovered from neutral alumina. It turned out,
c
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C.-D. Leger – G. Maas · Dinuclear Ruthenium(I) Triazenide Complexes
Scheme 1. Synthesis of complexes 3a–c.
Scheme 2. Cyclopropanation of alkenes with methyl diazoac-
etate.
however, that the crude products, obtained after ex-
traction with cyclohexane from the reaction mixtures,
could be used without complications in the preparation
of complexes 3.
It has been reported that (1,3-di-p-tolyl)triazenide
complex 3a is formed in 47% yield from triazene 2a
and Ru3(CO)12 in refluxing benzene and under a CO
atmosphere [8]. We found that with acetonitrile as sol-
vent and a ca. four- to sixfold higher concentration
of the reactants, the product was obtained after only
3 hours in 63% yield (Scheme 1). Under similar con-
ditions, but in the absence of a CO atmosphere, com-
plexes 3b,c were obtained in 72 and 55% yield, respec-
tively. In contrast to these conditions, it was reported
that the synthesis of 3b in benzene as solvent did re-
quire the presence of a CO atmosphere, because in the
absence of excess carbon monoxide, the axial CO lig-
ands in 3b were replaced by 1,3-bis(4-chlorophenyl)-
triazene molecules [8]. Complex 3a has also been pre-
pared before from [Ru2(CO)4(µ-OAc)2]n by ligand ex-
change with triazene 2a in acetonitrile in 43.5% yield
[8]. Again, we were able to improve the yield to 75%
(see Experimental Section).
Fig. 1. Structure of complex 3b in the crystal (ORTEP plot,
ellipsoids of thermal vibration shown at the 30% probability
level). Top: View perpendicular to the Ru–Ru axis; bottom:
view along the Ru–Ru axis (axial CO ligands not shown).
ordination geometry is similar to the triazenido com-
plex [Ru(ArNNNAr)(CO)2(NH2Ar)]2 (Ar = p-tolyl)
(A) [8], where the axial position at each Ru atom is
occupied by a 4-methylaniline rather than a CO lig-
and, and to the pentazenido complex [Ru(ArN=N–N–
N=NAr)(CO)3]2 (Ar = p-tolyl) (B) [10]. In contrast
to related carboxylato complexes of type 1 [11], the
Ru2N3 rings adopt a twisted rather than a planar con-
formation which correlates with a staggered arrange-
ment of the metal–ligand bonds at Ru1 and Ru1# as
seen in the lower part of Fig. 1. As in complex B,
the bond lengths Ru1–C3 and C3–O3 indicate that the
axial carbonyl ligands are less tightly bound than the
equatorial ones. The octahedral geometry at the metal
centers deviates a bit from ideal values; in particular,
due to the small size of the triazenide bridges, the Ru–
The solid-state structure of complex 3b was deter-
mined by single-crystal X-ray diffraction analysis. A
molecule plot is shown in Fig. 1, relevant bond dis-
tances and angles are given in Table 1. In the crys-
tal, the molecules have exact C2 symmetry. The co-
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˚
Table 1. Selected bond
lengths, bond angles, and
torsion angles for com-
plex 3ba.
Bond lengths (A)
Ru(1)-Ru(1)#1
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-C(3)
Ru(1)-N(1)
Ru(1)-N(3)#1
N(1)-N(2)
N(1)-C(4)
N(2)-N(3)
N(3)-C(10)
N(3)-Ru(1)#1
O(1)-C(1)
Bond angles (◦)
2.6701(6) C(1)-Ru(1)-C(2)
1.886(2) C(1)-Ru(1)-N(1)
1.889(3) C(2)-Ru(1)-N(1)
2.003(2) C(1)-Ru(1)-N(3)#1
2.148(2) C(2)-Ru(1)-N(3)#1
2.149(2) N(1)-Ru(1)-N(3)#1
1.306(2) C(1)-Ru(1)-Ru(1)#1
1.438(2) C(2)-Ru(1)-Ru(1)#1
1.298(2) C(3)-Ru(1)-Ru(1)#1
1.438(3) N(1)-Ru(1)-Ru(1)#1
Torsion angles (◦)
91.40(11) Ru(1)#1-Ru(1)-N(1)-N(2)
169.30(8) Ru(1)-N(1)-N(2)-N(3)
35.39(15)
−19.9(2)
−17.7(2)
−149.8(2)
#1
95.50(9) N(1)-N(2)-N(3)-Ru(1)
86.14(9) Ru(1)-N(1)-C(4)-C(5)
171.33(8) Ru(1)#1-N(3)-C(10)-C(15) −140.9(2)
a
Symmetry transformation
85.83(7) N(1)-Ru(1)-Ru(1)#1-N(3) −26.3(1)
used to generate equivalent
90.48(7) C(1)-Ru(1)-Ru(1)#1-C(2)#1 −35.7(1)
atoms: #1 −x+1/2,y,−z+1.
91.06(7)
174.82(7)
81.23(5)
2.149(2) N(3)#1-Ru(1)-Ru(1)#1 80.67(4)
1.140(3) N(2)-N(1)-Ru(1)
1.141(3) C(4)-N(1)-Ru(1)
1.120(3) N(3)-N(2)-N(1)
122.21(12)
125.58(13)
116.67(17)
O(2)-C(2)
O(3)-C(3)
Ru–N bond angles (80.6, 81.3◦) are distinctly smaller
than the Ru–Ru–Ceq(O) angles (90.5, 91.1◦).
Table 2. Cyclopropanation of styrene with methyl diazoac-
etate catalyzed by 3a–c at 20 ◦C.
a
Catalyst
Catalyst loading
(mol-%)
0.1
Yield (%) of
E-5+Z-5
57
Relative ratioa
E-5 : Z-5
Cyclopropanation reactions
3a
59:41
The potential of complexes 3a – c to catalyze the
carbene transfer from methyl diazoacetate to various
alkenes (Scheme 2) was tested. In order to minimize
the formation of the formal carbene dimers dimethyl
maleate and dimethyl fumarate (Z-6, E-6), the diazo
ester was gradually added during 10 hours to the alkene
phase containin◦g the catalyst. Table 2 shows the results
obtained at 20 C with styrene at three different cata-
lyst concentrations, in styrene/dichloromethane solu-
tions and in neat styrene. It turned out that even with
a catalyst loading of 0.1 mol-%, high yields of cy-
clopropanes 5 were obtained, but the reaction time
of about 3 – 4 weeks was unreasonably long. With
3 mol-% of catalyst, the reaction was completed al-
most immediately after the addition of diazo ester.
The yields were usually better in neat rather than di-
luted styrene, and catalyst 3b in general gave the best
results. Therefore, 3b was also applied to compare
the effectiveness of cyclopropanation of a standard
set of alkenes (Table 3). It was found that terminal
alkenes (styrene, ethyl vinyl ether, 1-hexene) are cyclo-
propanated in good to high yield, while alkenes with
1,2-di- and 1,2,3-trisubstituted double bonds (cyclo-
hexene, 2-methyl-2-butene) give only low yields of the
corresponding cyclopropanes. In contrast, the struc-
turally similar ruthenium(I) acetate complex 1 cat-
alyzes not only cyclopropanation of terminal alkenes
in good to high yields but also that of several inter-
nal double bonds (e.g. 68% yield from cyclohexene
1.0
3.0
0.1
1.0
3.0
0.1
1.0
3.0
61 (79)
60b (70)
98
87 (98)
90c (87)
88
50:50 (49:51)
49:51 (46:54)
63:37
51:49 (53:47)
46:54 (48:52)
69:31
3b
3c
71 (96)
52:48 (48:52)
51:49 (48:52)
74d (80)
a Yields and diastereomer ratios were determined by GC. The values
for the reaction in styrene–CH Cl2 (1 mmol of diazoester, 10 mmol
of styrene, 1 – 1.7 ml of CH2Cl2) are given first; the values in paren-
theses refer to the reaction in neat styrene (1 mmol of diazoester,
26 mmol of styrene); b at 40 ◦C: 64% yield (48:52); c at 40 ◦C: 95%
yield (49:51); d at 40 ◦C: 94% yield (46:54).
2
yield) [4]. These results indicate that cyclopropanation
reactions catalyzed by triazenido-ruthenium(I) com-
plexes 3, by comparison with acetato complex 1, are
even more dominated by the steric demand than by the
nucleophilicity of the olefin. The electrophilic char-
acter of ruthenium-catalyzed cyclopropanation reac-
tions has been established [2, 12, 13], and the observa-
tion that the yields of styrene cyclopropanation in gen-
eral decrease in the order 3b > 3c > 3a indicates an
influence of remote electron-withdrawing substituents
on the electrophilic character of the catalytically ac-
tive species as well. However, ruthenium-based cy-
clopropanation catalysts are typically much less elec-
trophilic than, e.g., the established dinuclear rhodium
acetate and amidate complexes.
According to the generally accepted mechanistic
and 61% from 2-methyl-2-butene), while its effective- picture [1, 2], metal-carbene intermediates are involved
ness decreases significantly only in the case of a tetra- in the carbene transfer reaction. With the coordina-
substituted double bond (2,3-dimethyl-2-butene, 47% tively saturated complexes 3a – c, it is required that
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C.-D. Leger – G. Maas · Dinuclear Ruthenium(I) Triazenide Complexes
Table 3. Cyclopropanation of different alkenes with methyl
diazoacetate catalyzed by 3b (3 mol-%).
plex [Ru2(CO)4(µ-OAc)2]n, they are inferior in terms
of yield for internal alkenes, but they give rise to higher
amounts of the thermodynamically less favored cis- or
syn-cyclopropane with both terminal alkenes and cy-
clohexene.
Entry
Alkene
Yielda (%) of Relative ratio
E-5+Z-5 E-5 : Z-5
R3 (or anti + syn) (or anti : syn)
R1
Ph
EtO
nBu
R2
H
H
1
2
3
4
5
H
H
H
H
90 / 95 / 87
83 / – / –
46:54 / 49:51 / 48:52
63:37 / – / –
52:48 / – / –
52:48 / 60:40 / 56:44
13:87 / 10:90 / 11:89
Experimental Section
H
61 / – / –
–(CH2)4–
Me Me
29 /13b / 7c
General information
Me 18 /16 /22
NMR spectra: Bruker DRX 400 (1H: 400.13 MHz; 13C:
100.62 MHz); as the internal standard, TMS was used for the
1H spectra and the solvent signal (δ(CDCl3) = 77.0 ppm) for
the 13C spectra. – IR spectra: Bruker Vector 22. – GC: Varian
CP-3800 with a flame ionization detector. – Mass spectrom-
etry, MALDI-TOF: Bruker Daltonic Reflex III. – Elemental
analyses: Elementar Vario EL.
a
Yields and diastereomer ratios were determined by method A (en-
tries 1, 4, 5) or method B (entries 2, 3), see experimental section.
Values are given for the following conditions: alkene–CH Cl2, 20 ◦C
2
/ alkene–CH2Cl2, 40 ◦C / neat alkene, 20 ◦C. The scale was the same
as in Table 2, except for entries 2 and 3 (10 mmol of diazoester,
b
100 mmol of alkene); 46% yield (50:50) with catalyst 3c; c 27%
yield (49:51) with catalyst 3a.
Triazenes 2a – c were prepared by analogy to a litera-
ture method [9] and were used without purification. React◦ion
conditions: a) X = CH3: conc. HCl, KNO2, H2O, −10 C;
an axial carbonyl ligand is replaced by the ethoxy-
carbonylcarbene moiety. It is interesting to note that
◦
this ligand exchange appears to occur readily at 20 C.
◦
X = Cl, Br: conc. HCl, 12 h at r. t., then KNO2, −10 C.
◦
A reaction temperature of 40 C provides slightly in-
b) Na2CO3, H2O, H2N–C6H4–4-X, 0 ◦C.
creased yields with the terminal alkenes, but has obvi-
ously no beneficial effect on cyclopropanation of the
internal alkenes (Tables 2 and 3).
Preparation of triazenido ruthenium(I) complexes 3a−c
Hexacarbonylbis(µ-1,3-di-p-tolyltriazenido)diruthenium
(I/I) (3a): Method 1: A solution of 1,3-di-p-tolyltriazene (2a,
0.39 g, 1.7 mmol) and triruthenium dodecacarbonyl (0.19 g,
0.3 mmol) in acetonitrile (8 ml) was heated at reflux for 5 h
under an atmosphere of carbon monoxide, then allowed to
The cyclopropanation of terminal alkenes and of cy-
clohexene using 1 or 3 mol-% of catalysts 3a– c pro-
vides in most cases, and irrespective of the particular
catalyst, almost equal amounts of Z- and E- (or syn-
and anti-) cyclopropanes 5. With 2-methyl-2-butene,
however, a high syn-selectivity is found (Tables 2 and
3). Thus, catalysts 3a – c induce a higher amount of
the thermodynamically less favored Z-(syn-) isomer as
compared to the related ruthenium acetate catalyst 1,
and virtually the same syn preference as 1 in the case
of trisubstituted alkenes. The increased amount of the
Z-cyclopropanein the case of terminal alkenes is worth
being noted, but clearly it is still far away from the high
cis-selectivity achieved with Mezzetti’s RuII(P,P,N,N)
complexes [3, 13] and Katsuki’s RuII(NO+)(salen) cat-
alysts [3e]. Remarkably, the ratio of E-5 in the case of
styrene is significantly higher when only 0.1 mol-% of
catalyst is applied (Table 2). Such a dependence of the
diastereoselectivity on the catalyst concentration is un-
usual, and we have no straightforward explanation at
hand.
◦
stand at 20 C under CO atmosphere. The precipitate was
collected, washed with acetonitrile and ethanol and recrys-
tallized from dichloromethane–ethanol to give yellow micro-
crystals, yield 0.15 g (63%), m.p. 180 – 181 ◦C (lit. [8]: 180 –
184 ◦C). The IR and 1H NMR data agree with those reported
[8]. – 13C NMR (CDCl3, 100.62 MHz): δ = 20.8 (CH3),
122.5, 129.0, 134.9, 154.6, 181.3 (CO), 199.8 (CO).
Method 2: The literature procedure [8] was followed at
a larger (fivefold) scale: A solution of 1,3-di-p-tolyltriazene
(2.50 g, 11.2 mmol) in acetonitrile (50 ml) was prepared
and triethylamine (8 ml) and [Ru2(CO)4(µ-OAc)2]n (1.25 g,
2.95 mmol) were added. The mixture was heated at reflux
for 3 h under an atmosphere of carbon monoxide. The fur-
ther procedure was as d◦escribed above, yielding 1.82 g (75%)
of 3a, m.p. 179 – 181 C (lit. [8]: 43.5% yield, m.p. 180 –
184 ◦C).
Hexacarbonylbis(µ-1,3-di-p-chlorophenyltriazenido)di-
ruthenium(I/I) (3b): A solution of 1,3-di-p-chlorophenyltri-
azene (1.60 g, 6.0 mmol) and Ru3(CO)12 (0.64 g, 1.0 mmol)
in acetonitrile (10 ml) was heated at reflux for 5 h. The prod-
uct crystallized on standing at 20 ◦C for 15 h. Recrystalliza-
tion from dichloromethane–ethanol gave 0.91 g (72%) of yel-
low microcrystals, m.p. 203 – 204 ◦C (lit. [8]: 206 – 209 ◦C).
In conclusion, the dinuclear ruthenium(I) triazenide
complexes [Ru(CO)3(ArNNNAr)]2 effectively cat-
alyze the cyclopropanation of nucleophilic terminal
alkenes with methyl diazoacetate but provide only low
yields when internal alkenes are used. When compared
with the structurally related ruthenium(I) acetate com- The IR and 1H NMR data agree with those reported [8]. –
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577
13C NMR (CDCl3, 100.62 MHz): δ = 123.6, 128.8, 131.4, by flash chromatography. Elution with pentane gave excess
154.7, 180.8 (CO), 198.8 (CO).
alkene in the first fraction, elution with pentane–ether (1:7)
afforded the two diastereomers of cyclopropanes 5 which
were collected in one fraction. Finally, elution with ether
yielded dimethyl fumarate and dimethyl maleate (E- and Z-
6, ca. 1:1 mixture). All cyclopropanes are known and were
identified by comparison of their NMR data with literature
data.
Selected yields (catalyst used / cyclopropanes 5 / carbene
dimers 6): a) From ethyl vinyl ether: 3a / 58% / 20%; 3b /
83% / 14%; 3c / 56% / 2%. b) From 1-hexene: 3a / 40% /
28%; 3b / 61% / 24%; 3c / 50% / 38%. c) From cyclohexene:
3b / 29% / 31%.
Hexacarbonylbis(µ-1,3-di-p-bromophenyltriazenido)di-
ruthenium(I/I) (3c): A solution of 1,3-di-p-bromophenyl-
triazene (0.96 g, 2.68 mmol) and Ru3(CO)12 (0.22 g,
0.34 mmol) in acetonitrile (5 ml) was heated at reflux for 3 h.
Crystallization started after one hour and was complete af-
ter standing at 20 ◦C for 15 h. The product was washed with
acetonitrile and ethanol (2 × 2 ml each) and recrystallized
from dichloromethane–ethanol: 0.19 g (55%) of yellow mi-
crocrystals, m.p. 212 – 214 ◦C. – IR (KBr): ν = 2083, 2063,
2024, 2013, 1998 (all s, CO), 1481 (m), 1365 (s) cm−1. –
1H NMR (CDCl3, 400.13 MHz): δ = 7.09 − 7.11 (m, 8H),
7.31 – 7.43 (m, 8 H). – 13C NMR (CDCl3, 100.62 MHz):
δ = 119.2, 123.9, 131.8, 155.2, 180.8 (CO), 198.8 (CO). –
MALDI-TOF: m/z = 1192 [M + 4 CO], 1136 [M + 2 CO],
768 [M − 2 PhBr]. – C30H16Br4N6O6Ru2 (1087.2): calcd.
C 33.42, H 1.50, N 7.79; found C 33.39, H 1.49, N 7.68.
Crystal structure determination of complex 3b
Suitable crystals were obtained by slow diffusion of
ethanol into a dichloromethane solution of 3b. Data collec-
tion was performed at 220 K with an imaging-plate diffrac-
tometer (IPDS, STOE) using monochromated Mo-Kα radi-
General procedures for cyclopropanation experiments
˚
ation (λ = 0.71073 A). The structure was solved with di-
rect methods and refined with a full-matrix least-squares
procedure using F2 values [14]. Hydrogen atoms are in
calculated positions and were treated by the riding model.
Crystal data: C30H16Cl4N6O6Ru2, M = 900.45, monoclinic,
space group I2/a (no. 15); a = 16.912(3), b = 8.514(1),
Method A (analytical scale): The catalyst (3a – c; 0.1, 1.0
or 3.0 mol-%) was dissolved in a mixture of alkene (8 mmol)
and dichloromethane (1 ml). By means of a syringe pump, a
solution of methyl diazoacetate (1 mmol) in alkene (2 mmol)
and dichloromethane (0.7 ml) was added during 10 h. The
complete consumption of the diazo compound was then mon-
itored by IR spectroscopy. A defined amount of naphtha-
lene was added as an internal standard, and the yields and
diastereomer ratios of cyclopropanes 5 were determined by
gas chromatography, using a Varian CP-WAX 52 column
(30 m×0.32 mm, film thickness 0.25 µm) fitted with a re-
tention gap. The response factor of each cyclopropane was
determined using a sample prepared, purified and isolated ac-
cording to Method B.
◦
˚
c = 23.598(4) A, α = 90, β = 101.01(2), γ = 90 ; V =
3
3335.5(10) A , Z = 4, Dc = 1.793 g cm−3. Data collection:
˚
crystal size 0.54×0.46×0.38 mm, 12512 reflection data in
the range θ = 2.55 − 25.86◦, 3075 independent reflections
(Rint = 0.0268). Structure refinement: 3075 data, 217 param-
eters; the final R indices were R1 = 0.0254, wR2 = 0.0545,
the corresponding values for reflections with I > 2σ(I) were
R1 = 0.0214, wR2 = 0.0529; residual electron density be-
tween 0.32 and −0.56 e A−3
.
Crystallographic data have been deposited as CCDC-
225446. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the
Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge CB2 1EZ, UK; fax: (+44)1223-336-033.
Method B (preparative scale): The catalyst (3a – c,
0.3 mmol) was dissolved in a mixture of alkene (80 mmol)
and dichloromethane (10 ml). By means of a syringe pump,
a solution of methyl diazoacetate (10 mmol) in alkene
(20 mmol) and dichloromethane (2 ml) was added during
20 h. The diazoester had been consumed completely within
30 min after the addition was over (IR control). Silica gel
(Merck Kieselgel 60, 0.063 – 0.200 mm, 7 g) was added,
Acknowledgements
◦
Financial support of this study by the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen In-
dustrie is gratefully acknowledged.
and the volatiles were evaporated at 20 C/800 – 600 mbar.
The residue was then transferred on top of a column charged
with silica gel (40 g) and the product mixture was separated
[1] M. P. Doyle, M. A. McKervey, T. Ye, Modern Cat-
alytic Methods for Organic Synthesis with Diazo Com-
pounds: From Cyclopropanes to Ylides, Wiley, New
York (1998).
[2] Review: G. Maas, Chem. Soc. Rev., in press (2004).
[3] Selected examples: a) A. F. Noels, A. Demonceau,
J. Phys. Org. Chem. 11, 602 (1998) (review);
b) H. Nishiyama, Y. Itoh, Y. Sugawara, H. Matsumoto,
K. Aoki, K. Itoh, Bull. Chem. Soc. Jpn. 68, 1247
(1995); c) H. M. Lee, C. Bianchini, G. Jia, P. Barbaro,
Organometallics 18, 1961 (1999); d) E. Galardon, P. Le
Maux, G. Simonneaux, Tetrahedron 56, 615 (2000);
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578
C.-D. Leger – G. Maas · Dinuclear Ruthenium(I) Triazenide Complexes
e) T. Uchida, R. Irie, T. Katsuki, Tetrahedron 56, 3501
[7] G. Maas, J. Seitz, Tetrahedron Lett. 42, 6137 (2001).
[8] a) S. F. Colson, S. D. Robinson, Polyhedron 7, 417
(1988); b) S. F. Colson, S. D. Robinson, M. Motevalli,
M. B. Hursthouse, Polyhedron 7, 1919 (1988).
[9] E. H. White, A. A. Baum, D. E. Eitel, Org. Synth. Coll.
Vol. V, 797 (1973).
(2000); f) W. Baratta, W. A. Herrmann, R. M. Kratzer,
P. Rigo, Organometallics 19, 3664 (2000); g) Z. Zheng,
X. Yao, C. Li, H. Chen, X. Hu, Tetrahedron Lett. 42,
2847 (2001); h) C.-M. Che, J.-S. Huang, F.-W. Lee,
Y. Li, T.-S. Lai, H.-L. Kwong, P.-F. Teng, W.-S. Lee,
W.-C. Lo, S.-M. Peng, Z. Y. Zhou, J. Am. Chem. Soc.
[10] R. Schmid, J. Stra¨hle, Z. Naturforsch. 43b, 533 (1988).
123, 4119 (2001); i) I. J. Munslow, K. M. Gillespie, [11] K.-B. Shiu, S.-M. Peng, M.-C. Cheng, J. Organomet.
R. J. Deeth, P. Scott, Chem. Commun. 1638 (2001);
j) C. Bonaccorsi, S. Bachmann, A. Mezzetti, Tetrahe-
dron: Asymmetry 14, 845 (2003).
Chem. 452, 143 (1993), and references cited therein.
[12] a) S. B. Park, K. Murata, H. Matsumoto, H. Nishiyama,
Tetrahedron: Asymmetry 6, 2487 (1995).
[4] G. Maas, T. Werle, M. Alt, D. Mayer, Tetrahedron 49,
881 (1993).
[13] S. Bachmann, A. Mezzetti, Helv. Chim. Acta 84, 3063
(2001).
[5] T. Werle, G. Maas, Adv. Synth. Catal. 343, 37 (2001).
[6] G. Maas, M. Alt, D. Mayer, U. Bergstra¨sser, S. Skle-
nak, P. Xavier, Y. Apeloig, Organometallics 20, 4607
(2001).
[14] G. M. Sheldrick, SHELX-97 – Program for the solu-
tion and refinement of crystal structures from diffrac-
tion data, University of Go¨ttingen, Germany (1997).
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