Anti-Markonikov reactions, 6. Rhodium-catalyzed amination of vinylpyridines: Hydroamination versus oxidative amination

Article abstract of DOI:10.1002/(SICI)1099-0682(199907)1999:7<1121::AID-EJIC1121>3.0.CO;2-8

Cationic rhodium complexes catalyze the amination of 2- and 4- vinylpyridine with secondary amines. Depending on the substrate and the reaction conditions either oxidative amination to yield the corresponding enamines 1a-8a or hydroamination to give 2-aminoethylpyridines 1b-8b occurs. In all cases products with anti-Markovnikov regioselectivity are obtained. For mechanistic studies novel cationic complexes of rhodium(I)-containing cyclooctadiene and vinylpyridine 12 as well as complexes containing cyclooctadiene, vinylpyridine, and morpholine 13 were prepared and characterized by NMR spectroscopy and X-ray diffraction analysis.

Full text of DOI:10.1002/(SICI)1099-0682(199907)1999:7<1121::AID-EJIC1121>3.0.CO;2-8

FULL PAPER
Anti-Markonikov Reactions, 6[°]
Rhodium-Catalyzed Amination of Vinylpyridines: Hydroamination versus
Oxidative Amination
Matthias Beller,*[a,b] Harald Trauthwein,[b] Martin Eichberger,[†] Claudia Breindl,[b]
and Thomas E. Müller[b]
Keywords: Coordination chemistry / Rhodium / Aminations / Hydroaminations / Oxidative aminations / Vinylpyridines
Cationic rhodium complexes catalyze the amination of 2- and
4-vinylpyridine with secondary amines. Depending on the
regioselectivity are obtained. For mechanistic studies novel
cationic complexes of rhodium(I)-containing cyclooctadiene
substrate and the reaction conditions either oxidative and vinylpyridine 12 as well as complexes containing
amination to yield the corresponding enamines 1a؊8a or
hydroamination to give 2-aminoethylpyridines 1b؊8b
occurs. In all cases products with anti-Markovnikov
cyclooctadiene, vinylpyridine, and morpholine 13 were
prepared and characterized by NMR spectroscopy and X-ray
diffraction analysis.
amination of olefins occurs, we became interested in the
reaction of vinylpyridines. Additional interest in these reac-
tions results from the fact that 2-(2Ј-aminoethyl)pyridines
are used as building blocks for pharmaceuticals and fine
chemicals for hydrometallurgy.[4]
Introduction
The construction of carbonϪnitrogen bonds by using
transition metal catalysts, especially for the synthesis of
amines, has become an area of intensive research. Catalytic
aminations of olefins[2] to selectively give primary, second-
ary, or tertiary amines are particularly interesting because
of the atom efficiency of the process and the availability of
feedstocks. One of the few examples is the newly developed
intermolecular oxidative amination of aromatic olefins to
give enamines.[3] Interestingly, this reaction yields the anti-
In contrast to styrene, 2- and 4-vinylpyridine are Michael
systems, i.e. the double bond is in conjugation with an elec-
tron-withdrawing group. This activation favors the anti-
Markovnikov hydroamination of 2- and 4-vinylpyridine.
However, in contrast to acrylamide or acrylnitrile, which
react quantitatively with amines without a catalyst even un-
der mild conditions, 2- and 4-vinylpyridine react only slug-
gishly without a catalyst due to the weaker electron-with-
drawing effect of the pyridine ring.
Markovnikov products in
(Scheme 1).
a highly selective manner
The hydroamination of vinylpyridines was first reported
in the late 1940s.[5] Typically, the hydroamination of vinyl-
pyridines is catalyzed by either acid or base.[6] For example,
Matusko et al. obtained good results with vinylpyridines by
employing a mixture of methanol and acetic acid.[7] How-
ever, some amines, like pyrrolidine, are not basic enough
to react under these conditions. Successful amination of 2-
vinylpyridine occurs when the reaction is performed with
the addition of catalytic sodium metal in order to generate
the more nucleophilic amide.[8] Surprisingly, the use of tran-
sition metal catalysts in the amination of vinylpyridines is
rare.[9]
Scheme 1. Anti-Markovnikov oxidative amination of styrene
This amination process allows the conversion of simple
monoamines, such as piperidine and diethylamine, into the
corresponding ω-enamines in good yields by employing cat-
ionic (phosphane)rhodium complexes as catalysts. An ad-
ditional equivalent of the aromatic olefin is concurrently
reduced to ethylbenzene. For the first time the transition-
metal-catalyzed hydroamination of styrene is possible in an
anti-Markovnikov manner with amines, such as morph-
oline, that contain a hemilabile second coordination site.[1]
In connection with mechanistic studies to understand the
features that control whether hydroamination or oxidative
In this report we present for the first time various amin-
ation reactions of 2- and 4-vinylpyridines using cationic
rhodium catalysts. Depending on the reaction conditions,
varying amounts of hydroamination and oxidative amin-
ation products are obtained. In order to understand the
mechanistic background, new cationic rhodium complexes
that contain 2-vinylpyridine as a ligand have been isolated
and characterized by X-ray crystallography. These com-
plexes are shown to be important intermediates in the cata-
lytic hydroamination of vinylpyridines.
[°] Part 5: Ref.[1]
[a]
Institut für Organische Katalyseforschung (IfOK) an der Uni-
versität Rostock e.V.,
Buchbinderstraße 5Ϫ6, D-18055 Rostock, Germany
[b]
Anorganisch-chemisches Institut, Technische Universität Mün-
chen,
Lichtenbergstraße 4, D-85747 Garching, Germany
[†]
Deceased 1997.
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999
1434Ϫ1948/99/0707Ϫ1121 $ 17.50ϩ.50/0
1121

M. Beller, H. Trauthwein, M. Eichberger, C. Breindl, T. E. Müller
FULL PAPER
is evident that enamine and ethylpyridine are formed
mainly during the first hours. After about 10 h, no further
enamine formation is observed. In contrast, only a small
amount of aminoalkylpyridine is formed at the beginning
of the reaction, but the rate of its formation remains nearly
constant until all piperidine is consumed. Similar to the oxi-
dative amination of styrene, the enamine formation is prob-
ably catalyzed by cationic rhodium species that contain
monodentate phosphane ligands. During the course of the
reaction the rhodium catalyst is deactivated, either by loss
of its cationic character or by the formation of chelate com-
plexes with the products behaving as bidentate ligands. In-
dependent of the oxidative amination process, the forma-
tion of the alkylamine proceeds by a different mechanism.
In order to gain further insight into the different reaction
pathways and to evaluate the critical reaction parameters
for both oxidative amination and hydroamination we varied
the catalyst system and the reaction conditions (Table 1).
The oxidative amination proceeds best with THF as the
solvent (entries 1, 6). The catalyst is also active in toluene,
although the formation of alkylamine is increased (entry
2). The dipolar aprotic solvent dimethylacetamide (DMAC)
completely inhibits the enamine formation and lowers the
yield of alkylamine (entry 3). By reducing the amount of
catalyst from 2.5 mol-% to 1 mol-% (entry 1 vs. 4) it is
shown that the oxidative amination is more sensitive than
the hydroamination to the concentration of the cationic
catalyst. This is a good indication that the hydroamination
reaction is catalyzed by various rhodium species, while the
oxidative amination is catalyzed by a discrete cationic
(phosphane)rhodium complex. Further support for this as-
sumption comes from the fact that the presence of phos-
phane is a prerequisite for enamine formation (entry 5). In
the presence of [Rh(cod)2]BF4 without triphenylphosphane,
only hydroamination occurs to give N-[2-(2Ј-pyridyl)ethyl]-
piperidine (2b) in high yields (97%). By lowering the ratio
of vinylpyridine to piperidine to 2:1 the oxidative amination
becomes the major reaction pathway and N-[2-(2Ј-pyridy-
l)ethenyl]piperidine (2a) is isolated in 82% yield (entry 6).
The different influence of the olefin/amine ratio on the oxi-
dative amination of styrenes and 2-vinylpyridines can be
explained by the different coordination ability of styrene
and 2-vinylpyridine. 2-Vinylpyridine is able to coordinate
to the rhodium center through the pyridine-nitrogen atom,
which is not possible for styrene. The coordination of the
nitrogen atom of pyridine activates the olefinic bond in 2-
vinylpyridine for a nucleophilic attack of the amine, which
enhances hydroamination but has no effect on the oxidative
amination. In contrast, we assume that the oxidative amin-
ation proceeds by an amine-activation mechanism. A lower
concentration of 2-vinylpyridine would favor the coordi-
nation of the amine to the rhodium center, which facilitates
NϪH activation.
Results and Discussion
Catalytic Amination of 2- and 4-Vinylpyridine
Cationic (phosphane)rhodium complexes such as
[Rh(cod)2]BF4/2 PPh3 are the only known class of active
transition metal catalysts for the intermolecular anti-Mar-
kovnikov amination and hydroamination of styrenes.[2] In
order to investigate how these catalysts effect the amination
of a more activated olefin the reaction of 2-vinylpyridine
with piperidine was chosen for initial studies (Scheme 2).
Under the typical reaction conditions of the oxidative amin-
ation of styrene (THF reflux, 2.5 mol-% [Rh(cod)2]BF4/
2 PPh3, 20 h) three products are obtained. The major prod-
uct, N-[2-(2Ј-pyridyl)ethyl]piperidine (2b), resulting from a
hydroamination reaction, was isolated in 53% yield. Also,
for the first time an intermolecular oxidative amination of
2-vinylpyridine was achieved giving N-[2-(2Ј-pyridyl)ethen-
yl]piperidine (2a) in 47% yield. A second equivalent of 2-
vinylpyridine is concurrently reduced to 2-ethylpyridine,
which was isolated in 42% yield. All yields are based on pip-
eridine.
Scheme 2. Rhodium-catalyzed amination of 2-vinylpyridine
As expected, all amination reactions occur exclusively
with anti-Markovnikov regioselectivity. This is explained by
the strong polarization of the vinyl group by the pyridine
ring. When the reaction is performed under identical con-
ditions without a catalyst the hydroamination product N-
[2-(2Ј-pyridyl)ethyl]piperidine is obtained in only 3% yield.
Hence, both the hydroamination and the oxidative amin-
ation are catalyzed by the cationic rhodium catalyst.
Figure 1. Time/concentration diagram for the reaction of 2-vinylpy-
ridine and piperidine
In order to investigate the influence of pKa, steric and
electronic parameters of the amines on the amination reac-
In a further catalysis experiment the reaction of piperi- tion, we tested different aliphatic amines R2NH, such as
dine with 2-vinylpyridine to form the different amination piperazines, which have an additional functional group
products was followed with time. As depicted in Figure 1 it (Table 2).
1122
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132

Anti-Markonikov Reactions, 6
FULL PAPER
Table 1. Rhodium-catalyzed reaction of 2-vinylpyridine and piperidine[a]
Entry Olefin/Amine
Catalyst (mol-%)
Solvent, reaction time
Amine product Enamine
Ethylpyridine Amine
(%)
(%)
(%)
product/Enamine
1
2
3
4
5
6
4:1
4:1
4:1
4:1
4:1
2:1
[Rh(cod)2]BF4/2 PPh3 (2.5) THF, reflux, 20 h
[Rh(cod)2]BF4/2 PPh3 (2.5) Toluene, reflux, 20 h
53
61
47
30
42
24
21
7
1.1
2.0
Ϫ
5.9
48.5
0.2
[Rh(cod)2]BF4/2 PPh3 (2.5) DMAC, 140 °C, 20 h 44
< 0.1
8
[Rh(cod)2]BF4/2 PPh3 (1.0) THF, reflux, 20 h
[Rh(cod)2]BF4 (2.5) THF, reflux, 20 h
[Rh(cod)2]BF4/2 PPh3 (2.5) THF reflux, 20 h
47
97
16
2
82
2
46
[a]
The yield was determined by GC with hexadecane as internal standard and is referred to amine.
Table 2. Rhodium-catalyzed amination of 2-vinylpyridine with aliphatic amines[a]
Entry Amine (pKa)[23]
Enamine (%)
Amine product[b] (%)
Ethylpyridine (%)
Amine product/Enamine
1
2
3
4
5
6
7
8
Pyrrolidine (11.27)
Piperidine (11.02)
Hexahydroazepine
Morpholine (8.33)
Thiomorpholine
54 [1a]
47 [2a]
30 [3a]
2 [4a]
21 (3) [1b]
53 (8) [2b]
29 (< 1) [3b]
98 (5) [4b]
56
42
25
2
0.4
1.1
1.0
49
< 1
98 (26) [5b]
< 1
> 99
[c]
[c]
[c]
Piperazine (9.83)
N-Methylpiperazine
N-Phenylpiperazine
Ϫ
20 [7a]
8 [8a]
62 (6) [7b]
91 (10) [8b]
< 1
23
6
< 1
< 1
3.1
11.4
Ϫ
9aϪc HNR2, R ϭ Et (10.49), iPr, nBu < 1
10
n-Butylamine
< 1
< 1
Ϫ
[a]
2-Vinylpyridine/amine ϭ 4:1, 2.5 mol-% [Rh(cod)2]BF4/2 PPh3 referred to amine, THF reflux, 20 h. The yield was determined by GC
[b]
with hexadecane as internal standard and is referred to amine. Ϫ
as the rhodium-catalyzed reaction are shown in parentheses. Ϫ The reaction of piperazine is shown in Scheme 3.
The results of the uncatalyzed reaction under the same conditions
[c]
The reactions were performed in refluxing THF for 20 h. from 2-ethylpyridine, mono- and dialkylated piperazines
In all cases only the 2-(2Ј-aminoethyl)pyridine derivatives 6a؊d were obtained in a ratio of 2.2:1:2.1:1.
were detected as hydroamination products due to the polar-
The ratio of hydroamination products 6b and 6d to en-
ization of the double bond. The yields, which were obtained amines 6a and 6c is approximately 2:1. Surprisingly, no
without a catalyst, are given in brackets. Apart from product with two enamine groups was detected. Hence, it
thiomorpholine the amines reacted only to a slight extent is assumed that the dialkylated products are formed mainly
(< 10%) without a catalyst. Also, no oxidative amination by a consecutive reaction of N-[2-(2Ј-pyridyl)ethyl]pipera-
was observed, i.e. neither the corresponding enamine nor zine. This might be due to the better coordination ability of
ethylpyridine was formed. Comparing the ring size of the N-[2-(2Ј-pyridyl)ethyl]piperazine (6b) in comparison to N-
amine applied (pyrrolidine, piperidine, and hexahydroazep- [2-(2Ј-pyridyl)ethenyl]piperazine (6a).
ine) it is evident that the yield of the oxidative amination
In addition to aliphatic amines, we tested aromatic am-
product decreases with increased ring size of the amine, ines (aniline, pyrrole) as well as amides (acetamide) in the
with pyrrolidine providing the highest yield in enamine. Bi- rhodium-catalyzed amination of 2-vinylpyridines. Unfortu-
functional amines predominantly led to hydroamination re- nately, these substrates did not react in either a hydroami-
actions. It is likely that the conformation favored by the nation or in an oxidative reaction. We explain this behavior
chelating effect infers the β-H-elimination step that is re- as being due to the lower pKa value of these substrates com-
quired for oxidative amination. Interestingly, enamine for- pared to that of 2-vinylpyridine [pKa(pyridine) ϭ 5.2]. Due
mation was observed to some extent with all three pipera- to the lower nucleophilicity, hydroamination does not occur
zine derivatives. This is in contrast to the rhodium-catalyzed even after activation of vinylpyridine. Oxidative amination
amination of styrene and piperazine derivatives. In the lat- is not observed because the formation of (amine)rhodium
ter reaction chelating amines inhibit the reaction, which is complexes is unfavorable. Hence, NϪH activation by the
caused by the formation of insoluble (piperazine)rhodium rhodium center is not possible.
complexes.[10] Thus, we assume that the amination of 2-vi-
nylpyridine proceeds by activation of the 2-vinylpyridine.
Next, we studied the reaction of 4-vinylpyridine with
three amines (Table 3). None of the amines reacted with 4-
Piperazine, which has two reactive NϪH groups, leads to vinylpyridine in the absence of a rhodium catalyst. In the
the formation of five different products (Scheme 3). Apart presence of the catalyst system [Rh(cod)2]BF4/2 PPh3 all
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132
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M. Beller, H. Trauthwein, M. Eichberger, C. Breindl, T. E. Müller
FULL PAPER
Scheme 3. Reaction of 2-vinylpyridine and piperazine; the yields obtained without catalyst are given in parentheses
Table 3. Rhodium-catalyzed amination of 4-vinylpyridine with ali- elimination can take place to give enamines and dihydrido-
phatic amines[a]
metal complexes.
In contrast to other olefins, vinylpyridines can be acti-
Entry Amine
Enamine Pyridylamine Ethylpyridine
vated by cationic rhodium complexes either by coordination
of the double bond, the heteroaromatic ring or by coordi-
nation of the nitrogen atom. As suggested above, the mode
of coordination of the vinylpyridine is of fundamental im-
portance for explaining the various results obtained in the
amination of 2- and 4-vinylpyridine. Therefore, we investi-
(%)
(%)
(%)
1
2
Piperidine
< 1
Hexahydroaze- < 1
pine
57 [9]
21 [10]
< 1
< 1
3
Morpholine
< 1
54 [11]
< 1
[a]
4-Vinylpyridine/amine ϭ 4:1, 2.5 mol-% [Rh(cod)2]BF4/2 PPh3 gated the coordination chemistry of cationic rhodium com-
referred to amine, THF reflux, 20 h. The yield is referred to amine
and was determined by GC with hexadecane as internal standard.
plexes with amines and 2-vinylpyridine as ligands.
In contrast to the organometallic chemistry of cationic
rhodium complexes with secondary amines that has been
described recently,[10] rhodium complexes with 2-vinylpyri-
dine as a ligand have not been studied in detail. Denise and
Pannetier described the synthesis of [Rh(cod)(2-vinylpyri-
dine)2]PF6 by treatment of [Rh(cod)Cl]2 with 2-vinylpyri-
dine and NaPF6.[12] However, no detailed characterization
by NMR and X-ray studies of this complex has been per-
formed. Therefore, we synthesized [Rh(cod)(2-vinylpyri-
dine)2]OSO2CF3 (12) by combining [Rh(cod)Cl]2 and AgO-
SO2CF3 followed by addition of 2-vinylpyridine.
amines employed gave only the terminal hydroamination
products 9, 10, 11. Oxidative amination was not observed.
It is evident that for oxidative amination to occur both the
nitrogen atom of the pyridine ring and the vinyl group have
to be in steric proximity to the rhodium center.
Mechanistic Studies ؊ Cationic Rhodium Complexes
with 2-Vinylpyridine as Ligand
1
At room temperature the H-NMR spectrum (Figure 2)
of 12 shows several broad resonances indicating fluxionality
Amination of olefins can take place either by activation in the molecule. The signals at δ ϭ 8.9 and 8.7 are assigned
of the olefin or by activation of the amine NϪH bond.[11] to 6-H in the pyridine ring and the internal proton of the
In general, non-functionalized olefins become susceptible olefin, respectively. The other signals in the olefinic and
1
towards nucleophiles upon complexation to an electrophilic aromatic region of the H-NMR spectrum are sharper and
metal center. Addition of a nucleophile to the metal-bound are ascribed to 4-H (δ ϭ 7.66), 3-H (δ ϭ 7.55), and 5-H
olefin and protolysis yields the corresponding product and (δ ϭ 7.32). The terminal olefinic protons of the vinyl group
the catalyst. Alternatively, β-hydride elimination results in show resonances at δ ϭ 6.05. Clearly, the protons that are
the formation of imines or enamines. It is important to note adjacent to the rhodium center have broader signals com-
that catalytic activation of olefins in the presence of amines pared to the protons that are further away from the metal
is difficult to achieve due to the strong binding of amines center. The resonances of both the olefinic protons at δ ϭ
to electrophilic metal centers. One possible amine activation 4.0 and the two sets of aliphatic protons of the cod ligand
pathway involves oxidative addition of an amine to an un- at δ ϭ 2.7 and 2.0 are very broad at room temperature,
saturated metal center in a low oxidation state. The re- which is most likely caused by free rotation of the 2-vinyl-
sulting amido hydrido complex may insert an olefin into pyridine. Upon cooling 12 to Ϫ60°C the broad signals in
1
the metalϪnitrogen bond yielding an aminoalkyl hydrido the H-NMR spectrum sharpen to give clearly distinguish-
complex. Subsequent reductive elimination of the amine able signals. It is interesting to note that the resonances of
produced regenerates the catalyst. Alternatively, β-hydride the olefins show a vicinal and geminal coupling of J ϭ 11
1124
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132

Anti-Markonikov Reactions, 6
FULL PAPER
Scheme 4. Catalytic cycles for the amination of aromatic olefins by (a) amine activation and (b) olefin activation
In both the 1H-NMR and the 13C-NMR spectra a second
set of patterns (5% intensity) appears upon lowering the
temperature. We tentatively ascribe this minor pattern to a
rhodium species with pyridine rings, where both vinylic
groups are pointing in the same direction.
Scheme 5. Synthesis of the cationic complex [Rh(cod)(2-vinylpyri-
dine)2]CF3SO3 (12)
and 17 Hz, respectively. The signals of the cod protons,
which appear as three sharp pseudo-doublets, can be used
as a probe for the conformation of 12. Due to steric re-
asons, both vinyl groups should be opposite to each other.
Figure 3. The molecular structure of [Rh(cod)(2-vinylpyridine)2]ϩ
Crystals of 12 were obtained by slowly adding diethyl
ether to a dichloromethane solution of 12. The X-ray analy-
sis (Table 4) is in agreement with the conformation dis-
cussed on the basis of the NMR studies. The rhodium
center is in an approximately square-planar coordination
Figure 2. 1H-NMR spectrum of [Rh(cod)(2-vinylpyridi-
ne)2]CF3SO3 at room temperature and at Ϫ60°C in CDCl3
The 13C-NMR spectrum supports this conformational sphere. The lengths of the rhodiumϪamine bonds
˚
˚
analysis. At room temperature the resonances of the olefinic [RhϪN11 ϭ 2.129(2) A and RhϪN21 ϭ 2.118(3) A] and
carbon atoms of the cod ligand are very broad. However, the distances from rhodium to the centers X1 and X2 of the
˚
at Ϫ60°C two doublets appear, due to the Rh-C coupling cod double bonds C1ϪC2 and C5ϪC6 (RhϪX1 ϭ 2.019 A,
˚
(JRh-C ϭ 12.6 and 11.7 Hz). This confirms that the olefinic RhϪX2 ϭ 2.018 A) are within the typical range. The angles
carbon atoms are not identical. Also, there is no interaction X1ϪRhϪX2 (87.6°) and N11ϪRhϪN21 [89.2(1)°] are
between the vinyl group of the 2-vinylpyridine and the rho- close to right angles. The coordination sphere is distorted
dium center, as no Rh-C coupling was detected here.
tetraedric. Associated distances from a mean plane contain-
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132
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M. Beller, H. Trauthwein, M. Eichberger, C. Breindl, T. E. Müller
FULL PAPER
˚
Table 4. Selected bond lengths [A] and angles [°] of [Rh(cod)(2- 6). This is confirmed by mass spectrometry and elemental
vinylpyridine)2]CF3SO3 (12)
analysis as well as by IR spectroscopy, where a strong NϪH
frequency at 3215 cmϪ1 is observed. Interestingly, there is
RhϪN(11)
RhϪC(1)
RhϪC(5)
C(1)ϪC(2)
C(17)ϪC(18)
2.129 (2)
2.122 (4)
2.121 (3)
1.385 (5)
1.303 (6)
RhϪN(21)
RhϪC(2)
RhϪC(6)
C(5)ϪC(6)
C(27)ϪC(28)
2.118 (3)
2.139 (3)
2.143 (3)
1.386 (6)
1.308 (6)
no indication for an attack of the amine on the activated
vinyl group of the 2-vinylpyridine.
The ease of formation of the (morpholine)(2-vinylpyri-
dine)rhodium complexes suggests that these complexes are
precursors for the intermediates in the catalytic cycle.
N(11)ϪRhϪC(2)
N(21)ϪRhϪC(1)
N(21)ϪRhϪC(5)
N(11)ϪRhϪN(21)
92.42 (11)
157.70 (13)
91.04 (14)
89.23 (10)
N(11)ϪRhϪC(6)
N(21)ϪRhϪC(2)
N(21)ϪRhϪC(6)
163.90 (13)
164.34 (13)
92.74 (14)
N(11)ϪC(16)ϪC(17) 117.4 (3
N(21)ϪC(26)ϪC(27) 117.2 (3)
C(1)ϪRhϪC(2)
C(1)ϪRhϪC(6)
C(2)ϪRhϪC(5)
C(5)ϪRhϪC(6)
37.93 (14)
82.2 (2)
81.7 (2)
37.9 (2)
C(1)ϪRhϪC(5)
C(1)ϪRhϪN(11)
C(2)ϪRhϪC(6)
C(5)ϪRhϪN(11)
97.9 (2)
89.94 (12)
90.0 (2)
158.06 (13)
˚
˚
ing the rhodium atom are X1 ϩ0.057 A, X2 Ϫ0.061 A, N21
˚
˚
ϩ0.053 A and N11 Ϫ0.057 A. The 2-vinylpyridine ligands
are arranged perpendicular to the coordination plane
(82.1°, 89.2°), so that both ring systems are also perpen-
dicular to each other (88.2°). The vinylic groups are on op-
posite sides of the coordination plane and are slightly
twisted against the parent aromatic ring (5.9° and 13.6° for
the vinyl group defined by C16, C17, C18 and C26, C27,
C28, respectively). There is no coordinative interaction of
the vinylic group in the two 2-vinylpyridine ligands with the
rhodium center. This is confirmed by a shorter vinylic
Figure 4. 1H-NMR spectrum of [Rh(cod)(morpholine)(2-vinylpyri-
dine)]CF3SO3 (13) at room temperature and at Ϫ90°C in CD2Cl2
˚
double bond [C17ϪC18 ϭ 1.303(6) A, C27ϪC28 ϭ
1.308(6) A] compared to the double bonds in the cod ligand
[C1ϪC2 ϭ 1.385(5) A, C5ϪC6 ϭ 1.386(6) A].
˚
˚
˚
Figure 5. 13C-NMR spectrum of [Rh(cod)(morpholine)(2-vinylpy-
ridine)]CF3SO3 (13) at room temperature and Ϫ90°C in CDCl3
The 1H- and 13C-NMR spectra of [Rh(cod)(morpho-
line)(2-vinylpyridine)]CF3SO3 (13) are depicted in Figures 4
1
and 5, respectively. The signals in the H-NMR spectrum
at room temperature are broad, especially in the aliphatic
region. H-NMR analysis at Ϫ90°C shows sharper signals,
Scheme 6. Reaction of [Rh(cod)(2-vinylpyridine)2]CF3SO3 (12)
with morpholine
1
which indicates the existence of a preferential confor-
Cationic rhodium complexes containing an amine as well mation. The splitting of the resonances reveals interesting
as a 2-vinylpyridine ligand are likely intermediates in the details about the preferred low-temperature conformation.
catalytic cycle of the amination of 2-vinylpyridine. In order The multiplets at δ ϭ 3.67 and 3.43 are assigned to the
to gain more insight into this system we studied olefinic cod protons as well as the protons of the morpho-
the stoichiometric reaction of [Rh(cod)(2-vinylpyri- line protons adjacent to the oxygen atom. There is also a
dine)2]CF3SO3 (12) with 2 equivalents of morpholine. The splitting of the resonance of the methylene group of the
reaction
led
to
[Rh(cod)(morpholine)(2-vinylpyri- morpholine ligand adjacent to the nitrogen atom with sig-
dine)]CF3SO3 (13), which was formed in 84% yield (Scheme nals observed at δ ϭ 3.05 and 2.75.
1126
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132

Anti-Markonikov Reactions, 6
FULL PAPER
The 13C-NMR spectrum shows similar behavior. The ole- RhϪN21 ϭ 2.129(3) A, as expected for cationic amineϪ-
finic and the aliphatic cod resonances are very broad at rhodium bonds.[10] The bond lengths from rhodium to the
room temperature, but at Ϫ90°C the broad olefinic signal centers X1 and X2 of the two double bonds C1ϪC2 and
˚
˚
at δ ϭ 82.9 is split into four doublets, while the broad ali- C5ϪC6 associated with the cod ligand are 2.023 A and
˚
phatic signal at δ ϭ 29.3 is split into four singlets. Infor- 2.007 A, respectively. Each ligand around the rhodium
mation about the conformation of the morpholine ligand center is arranged nearly perpendicular to the two neigh-
can be obtained from the 13C-NMR spectrum at Ϫ90°C. bors with X1ϪRhϪX2 ϭ 87.4°, X2ϪRhϪN11 ϭ 91.3°,
The signal of the methylene group adjacent to the oxygen N11ϪRhϪN21 ϭ 91.3(1)° and N21ϪRhϪX1 ϭ 89.9°.
atom is a singlet, whereas the resonance of the methylene There is a slight pyramidal distortion, which can be seen by
group adjacent to the nitrogen atom is a doublet. The latter positive distances for each of the coordinating atoms from
˚
methylene groups seem to be influenced by the 2-vinylpyri- a plane through the rhodium center (X1 ϩ0.022 A, X2
˚
˚
˚
dine ring, whereas the methylene groups adjacent to the ϩ0.075 A, N11 ϩ0.027 A and N21 ϩ0.073 A). The 2-vinyl-
oxygen atom in the morpholine ligand are too far away pyridine is arranged nearly perpendicular (87.8°) to the co-
from the pyridine ring for the resonance to be split. Com- ordination plane. The vinyl group is twisted by 1.7° against
plex 13 was also characterised by X-ray crystallography. the aromatic ring of the 2-vinylpyridine. The double bond
The molecular structure of 13 is shown in Figure 6 of the vinyl group is significantly shorter than the double
˚
and selected bond lengths and angles are summarized in bonds of the cod ligand [C27ϪC28 ϭ 1.310(6) A vs.
˚
˚
Table 5.
C1ϪC2 ϭ 1.360(5) A, C5ϪC6 ϭ 1.360(6) A]. This is in
agreement with an elongation of the C1ϪC2 and C5ϪC6
bonds caused by their coordination to the rhodium center.
There is no coordinative interaction of the rhodium center
with the vinyl group in 2-vinylpyridine. The proton of the
amine forms a hydrogen bond with the tosylate [H11···O1 ϭ
˚
˚
2.27 A, N11ϪH11 ϭ 0.83(2) A, N11ϪH11···O1 ϭ 160.3°]
and there is a CϪH···O hydrogen bond between the aro-
matic ring and the oxygen atom of the morpholine ligand
˚
in
a
neighboring molecule (H24···O14
ϭ
2.33 A,
[13]
˚
C24ϪH24 ϭ 0.93 A, C24ϪH24···O14 ϭ 159.0°).
Table 6. Examples for complexes containing vinylpyridine as li-
gand; the lengths of the vinylic CϪC bond, its distance from the
metal center and the twist of the vinyl group against the pyridine
ring are given
˚ ˚
d(CC) [A] d(MX) [A] α [°] Ref.
Complex
12
13
1.303(6)
1.308(6)
1.310(6)
n. b.
n. b.
n. b.
5.9
13.6
1.7
[24a]
[24b]
[Cu2(µ-vpy)2(vpy)2](ClO4)2 1.307(23) n. b.
1.368(17) 1.917
10.0
2.4
Figure 6. The molecular structure of [Rh(cod)(morpholine)-
Ϫ
(2-vinylpyridine)]ϩCF3SO3
1.358(16) 1.903
1.319(23) n. b.
1.380(7)
1.378(7)
1.29(2)
1.414(5)
1.433(5)
5.7
14.9
1.9
[Cu(vpy)Cl]ϱ
1.940
1.984
n. b.
1.848
1.854
2.068
˚
Table 5. Selected bond lengths [A] and angles [°] of [Rh(cod)(mor-
7.8
[24b]
[24c]
pholine)(2-vinylpyridine)]CF3SO3 (13)
[Cu(vpy)I]ϱ
[Ni(PPh3)(vpy)]2
10.0
9.9
9.6
RhϪC(1)
RhϪC(5)
RhϪN(11)
C(1)ϪC(2)
2.132(3)
2.123(3)
2.155(2)
1.360(5)
1.310(6)
37.12(14)
82.26(14)
81.01(13)
160.00(12)
90.60(12)
91.89(12)
115.0(2)
109.5(2)
89.65(11)
115.3(3)
RhϪC(2)
RhϪC(6)
RhϪN(21)
C(5)ϪC(6)
2.139(3)
2.111(3)
2.129(3)
1.360(6)
[Os3(µ-H)2(CO)9(µ-CH-η2- 1.43(2)
vpy)]
[Os3(µ-H)2(CO)9(µ3-C-vpy)] 1.39(2)
17.0
[24d]
[24d]
n. b.
28.2
C(27)ϪC(28)
C(1)ϪRhϪC(2)
C(1)ϪRhϪC(6)
C(2)ϪRhϪC(5)
C(2)ϪRhϪN(11)
C(5)ϪRhϪN(11)
C(6)ϪRhϪN(11)
C(12)ϪN(11)ϪRh
C(16)ϪN(11)ϪC(12)
N(21)ϪRhϪC(2)
N(21)ϪC(26)ϪC(27)
C(1)ϪRhϪC(5)
C(1)ϪRhϪN(11)
C(2)ϪRhϪC(6)
C(5)ϪRhϪC(6)
C(5)ϪRhϪN(21)
C(6)ϪRhϪN(21)
C(16)ϪN(11)ϪRh
N(21)ϪRhϪC(1)
94.4(2)
X ϭ center of the vinylic CϪC bond, vpy ϭ 2-vinylpyridine, n.
b. ϭ non bonded.
162.78(13)
92.33(14)
37.5(2)
157.1(2)
165.0(2)
112.7(2)
90.46(12)
The X-ray structures of complexes 12 and 13 reveal that
in the solid state there is no binding interaction of the rho-
dium center with the vinyl group in 2-vinylpyridine. The
consequence of this are relatively short CϪC bond lengths
in the vinyl groups, a fact that is in agreement with other
late transition metal complexes containing the 2-vinylpyri-
N(21)ϪRhϪN(11) 91.30(9)
The rhodium center is coordinated in a square-planar dine ligand (Table 6). The dimeric [Cu2(µ-vpy)2(vpy)2]-
˚
fashion with the bond lengths RhϪN11 ϭ 2.155(2) A and (ClO4)2 (vpy ϭ 2-vinylpyridine) incorporates two copper
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132
1127

M. Beller, H. Trauthwein, M. Eichberger, C. Breindl, T. E. Müller
FULL PAPER
centers bridged by two vinylpyridine molecules with each and completely characterized. 12 reacts selectively with
of the copper atoms coordinating one further vinylpyridine morpholine to give [Rh(cod)(morpholine)(2-vinylpyri-
molecule in a monodentate fashion through the nitrogen dine)]CF3SO3 (13), which is a likely intermediate in the
atom. The CϪC bonds of the two vinyl groups coordinated catalytic cycle.
˚
˚
to the copper center [1.368(17) A, 1.358(16) A] are slightly
longer compared to non-coordinated vinyl groups
˚
˚
[1.307(23) A, 1.319(23) A]. Similar vinylic CϪC bond
Experimental Section
lengths are observed in the complexes [Cu(vpy)Cl]ϱ and
˚
˚
Materials and Methods: All reactions of air- and/or water-sensitive
compounds were performed using standard high-vacuum or
Schlenk techniques. All solvents were dried and distilled prior to
use according to standard procedures. Amines were distilled from
[Ni(PPh3)(vpy)]2 [1.380(7) A, 1.378(7) and 1.414(5) A,
˚
1.433(5) A, respectively], which contain the vinylpyridine in
a bridging fashion, whereas the vinylpyridine ligand in the
complex [Cu(vpy)I]ϱ is bound only through the nitrogen
atom that is associated with a shorter vinylic CϪC bond
CaH2, silver salts and other chemicals were purchased from Fluka
[14]
or Aldrich and used as received. [Rh(cod)Cl]2
and
˚
[Rh(cod)2]BF4[15] were prepared as described in the appropriate ref-
erence.
[1.29(2) A]. Other examples are the complexes [Os3(µ-
H)2(CO)9(µ-CH-η2-vpy)] and [Os3(µ-H)2(CO)9(µ3-C-vpy)].
In these complexes the nitrogen atom of the vinylpyridine
moiety is bound to a methylidyne and methylidene bridge
connecting three or two osmium atoms, respectively. The
vinyl group in the former complex is coordinated to the
metal center, whereas it is not coordinated in the second
Physical and Analytical Methods: H- and 13C-NMR spectra were
1
recorded with a Bruker AT 360 and referenced in ppm relative to
tetramethylsilane. Ϫ Infrared spectra were obtained with a PerkinϪ
Elmer 1600 spectrometer. Ϫ Mass-spectrometric analysis was per-
formed with a Finnigan MAT 311A by the Fast Atom Bombard-
ment (FAB) method. Ϫ Elemental analyses were performed by the
complex. This is associated with slightly longer CϪC bond
˚
lengths in the first complex [1.43(2) A] compared to the Microanalytical Laboratory of the Technische Universität
˚
München. Ϫ GC analyses were conducted with a HewlettϪPack-
ard 6890 instrument using an HP-1 capillary column. Yields were
determined against hexadecane as an internal standard. GC/MS
analyses were conducted with a Hewlett-Packard 5890 with 70-eV
electron impact ionization (detector: HP 5970 B).
latter complex [1.39(2) A].
The comparison with these data confirms that in 12 and
13 there is no binding interaction of the rhodium center
with the vinyl group in 2-vinylpyridine. Hence, the acti-
vation of 2-vinylpyridine in the presence of cationic rho-
dium complexes towards hydroamination most likely pro-
ceeds by a coordination of the rhodium center to the pyri-
dine nitrogen atom, which leads to a decrease in the elec-
tron density of the vinyl group. Clearly, oxidative amination
that takes place in the presence of additional phosphane
ligands must take place by a different mechanism. Unfortu-
nately, all efforts to isolate or characterize an (amine)(phos-
phane)(vinylpyridine)rhodium complex turned out to be
unsuccessful. Further work in this direction is in progress.
Reaction of 2-Vinylpyridine with Pyrrolidine: 45 mg of
[Rh(cod)2]BF4 (0.11 mmol) and 58 mg of PPh3 (0.22 mmol) were
mixed in 10 mL of THF. Subsequently, 0.37 mL of pyrrolidine
(4.40 mmol) and 1.90 mL of 2-vinylpyridine (17.6 mmol) were ad-
ded at room temperature. The reaction was heated to reflux for
20 h before being cooled to room temperature. The yield of (E)-N-
[2-(2-pyridyl)ethenyl]pyrrolidine (1a) was determined by gas chro-
matography with hexadecane as an internal standard. Ϫ In order
to isolate a more stable derivative of (E)-N-[2-(2-pyridyl)ethenyl]-
pyrrolidine (1a) , 0.5 g of Pd/C (5%) was added to the crude reac-
tion and the mixture was stirred for 48 h under H2 at a pressure of
1 atm. After filtration, the solvent was removed by evaporation.
The residue was dissolved in 20 mL of dichloromethane and ex-
tracted three times with 5% HCl. The combined aqueous phases
were neutralized by adding NaOH until pH ϭ 9 was reached and
the product was extracted three times with dichloromethane. The
combined organic layers were dried with MgSO4 and the solvent
was distilled off. N-[2-(2-Pyridyl)ethyl]pyrrolidine (1b) was ob-
tained after column chromatography (chloroform/methanol, 50:1)
in 75% yield.
Conclusion
For the first time the oxidative amination of 2-vinylpyri-
dine is described. In the presence of cationic (phos-
phane)rhodium complexes both oxidative amination as well
as hydroamination occurs to yield products with anti-Mar-
kovnikov regiochemistry. Interestingly, the ratio of enamine
to alkylamine is strongly influenced by the solvent, the
phosphane and the ratio of olefin to amine. It is assumed
that the hydroamination is initiated by an activation of the
2-vinylpyridine through coordination of the pyridine nitro-
gen atom to the rhodium center. In contrast, oxidative am-
ination proceeds by a different mechanism. While cyclic am-
ines that do not contain additional heteroatoms give good
yields of the corresponding enamines, hydroamination
dominates in the case of bidentate amines such as morph-
oline. Hydroamination of 4-vinylpyridine is achieved under
surprisingly mild conditions.
(E)-N-[2-(2-Pyridyl)ethenyl]pyrrolidine (1a): GC yield: 54%. Ϫ MS;
m/z: 174 [Mϩ], 145 [Mϩ Ϫ C2H3], 131 [Mϩ Ϫ C3H7], 118 [Mϩ
C3H7N], 105 [C5H4NϪC2H5ϩ].
Ϫ
N-[2-(2-Pyridyl)ethyl]pyrrolidine (1b): GC yield (before hydrogen-
ation): 54%; GC yield (after hydrogenation): 75%. Ϫ MS; m/z: 176
[Mϩ], 106 [C5H4NϪC2H4ϩ], 84 [(C5H10)NCH2ϩ]. Ϫ 1H NMR
3
(360 MHz, 25°C, CDCl3): δ ϭ 8.50 [d, J(H,H) ϭ 5.6 Hz, 1 H, 6-
3
4
H], 7.57 [dt, J(H,H) ϭ 7.8 Hz, J(H,H) ϭ 4.8 Hz, 1 H, 4-H], 7.14
[d, 3J(H,H) ϭ 7.8 Hz, 1 H, 3-H], 7.08 (m, 1 H, 5-H), 3.04 (m, 2 H,
PyϪCH2ϪCH2ϪN), 2.87 (m, 2 H, PyϪCH2), 2.61 (m, 4 H,
NϪCH2), 1.79 [q, 3J(H,H) ϭ 3.2 Hz, 4 H, NϪCH2ϪCH2].
Ϫ13C{1H} NMR (91 MHz, 25°C, CDCl3): δ ϭ 160.2 (C-2), 149.2
A possible intermediate for the catalyst formation,
[Rh(cod)(2-vinylpyridine)2]CF3SO3 (12) was synthesized (C-6), 136.2 (C-4), 123.1 (C-3), 121.2 (C-5), 56.0 (PyϪCϪC), 54.1
1128 Eur. J. Inorg. Chem. 1999, 1121Ϫ1132

Anti-Markonikov Reactions, 6
FULL PAPER
(CϪN), 35.7 (PyϪC), 22.5 (NϪCϪC). Ϫ MS; m/z: 176 [Mϩ], 106
[C5H4NϪC2H4ϩ], 84 [(C5H10)NCH2ϩ].
(PyϪCϪC), 53.2 (CH2ϪN), 35.1 (PyϪC). Ϫ MS; m/z ϭ 192 [M Ϫ
Hϩ], 132, 106 [C5H4NϪC2H4ϩ], 100 [CH2ϭN(CH2)4Oϩ].
Reaction of 2-Vinylpyridine with Thiomorpholine: In a procedure
analogous to the synthesis of 1, 0.44 mL of thiomorpholine
(4.40 mmol) and 1.90 mL of 2-vinylpyridine (17.6 mmol) in 10 mL
of THF were treated in the presence of 45 mg of [Rh(cod)2]BF4
(0.11 mmol) and 58 mg of PPh3 (0.22 mmol). 5 was purified by
column chromatography (hexane/ethyl acetate/NEt3, 1:1:0.01).
Reaction of 2-Vinylpyridine with Piperidine: In a procedure anal-
ogous to the synthesis of 1, 0.44 mL of piperidine (4.40 mmol) and
1.90 mL of 2-vinylpyridine (17.6 mmol) in 10 mL of THF were
treated in the presence of 45 mg of [Rh(cod)2]BF4 (0.11 mmol) and
58 mg of PPh3 (0.22 mmol).
(E)-N-[2-(2-Pyridyl)ethenyl]piperidine (2a): GC yield: 47%. Ϫ MS;
m/z: 188 [Mϩ], 159 [Mϩ Ϫ C2H5], 131 [Mϩ Ϫ C3H7N], 118 [Mϩ
Ϫ C4H8N], 106 [C5H4NϪC2H5ϩ].
N-[2-(2-Pyridyl)ethyl]thiomorpholine (5): GC yield: 98%; isolated
yield: 41% (375 mg). Ϫ 1H NMR (360 MHz, 25°C, CDCl3): δ ϭ
3
3
8.37 [d, J(H,H) ϭ 5.9 Hz, 1 H, 6-H], 7.46 [dt, J(H,H) ϭ 7.6 Hz,
4J(H,H) ϭ 1.7 Hz, 1 H, 4-H], 7.06 (m, 1 H, 3-H), 6.96 (m, 1 H, 5-
H), 2.84 [t, 3J(H,H) ϭ 4.7 Hz, 4 H, SϪCH2ϪCH2ϪNϪPy], 2.75
(m, 4 H, PyϪCH2ϪCH2), 2.79 [t, 3J(H,H) ϭ 4.7 Hz, 4 H, CH2ϪS].
N-[2-(2-Pyridyl)ethyl]piperidine (2b): GC yield (before hydrogen-
ation): 53%; GC yield (after hydrogenation): > 99.9%; isolated
yield: 86% (718 mg). Ϫ 1H NMR (360 MHz, 25°C, CDCl3): δ ϭ
3
3
8.47 [d, J(H,H) ϭ 4.8 Hz, 1 H, 6-H], 7.54 [dt, J(H,H) ϭ 7.9 Hz,
Ϫ
13C{1H} NMR (91 MHz, 25°C, CDCl3): δ ϭ 160.1 (C-2), 149.0
4J(H,H) ϭ 4.8 Hz, 1 H, 4-H], 7.14 [d, J(H,H) ϭ 7.9 Hz, 1 H, 3-
3
(C-6), 136.1 (C-4), 123.0 (C-3), 121.0 (C-5), 58.8 (PyϪCϪCϪN),
54.6 (CH2ϪN), 35.2 (PyϪCH2ϪCH2ϪN), 17.8 (CH2ϪS). Ϫ MS;
m/z: 208 [Mϩ], 175 [Mϩ Ϫ SH], 116 [S(C4H8)NCH2ϩ].
H], 7.05 (m, 1 H, 5-H), 2.96 (m, 2 H, PyϪCH2ϪCH2ϪN), 2.68 (m,
2
H, PyϪCH2), 2.44 (m, 4 H, CH2ϪN), 1.56 (m, 4 H,
NϪCH2ϪCH2), 1.40 (m, 2 H, NϪCH2ϪCH2ϪCH2). Ϫ 13C{1H}
NMR (91 MHz, 25°C, CDCl3): δ ϭ 160.6 (C-2), 149.1 (C-6), 136.2
(C-4), 123.1 (C-3), 120.9 (C-5), 59.2 (PyϪCϪC), 54.4 (CϪN), 35.7
(PyϪC), 25.9 (NϪCϪC), 24.3 (NϪCϪCϪC). Ϫ MS; m/z: 190
[Mϩ], 106 [C5H4NϪC2H4ϩ], 98 [(C5H10)NCH2ϩ].
Reaction of 2-Vinylpyridine with Piperazine: In a procedure anal-
ogous to the synthesis of 1, 0.38 g of piperazine (4.40 mmol) and
1.90 mL of 2-vinylpyridine (17.6 mmol) in 10 mL of THF were
treated in the presence of 45 mg of [Rh(cod)2]BF4 (0.11 mmol) and
58 mg of PPh3 (0.22 mmol).
Reaction of 2-Vinylpyridine with Hexahydroazepine: In a procedure
analogous to the synthesis of 1, 0.50 mL of hexahydroazepine
(4.40 mmol) and 1.90 mL of 2-vinylpyridine (17.6 mmol) in 10 mL
of THF were treated in the presence of 45 mg of [Rh(cod)2]BF4
(0.11 mmol) and 58 mg of PPh3 (0.22 mmol).
N-[2-(2-Pyridyl)ethyl]piperazine (6a): GC yield (before hydrogen-
ation): 33%; GC yield (after hydrogenation): 48%. Ϫ 1H NMR
3
(360 MHz, 25°C, CDCl3): δ ϭ 8.26 [d, J(H,H) ϭ 4.0 Hz, 1 H, 6-
3
4
H], 7.34 [dt, J(H,H) ϭ 7.8 Hz, J(H,H) ϭ 1.8 Hz, 1 H, 4-H], 6.92
3
[d, J(H,H) ϭ 7.8 Hz, 1 H, 3-H], 6.86 (m, 1 H, 5-H), 2.74 (m, 2 H,
(E)-N-[2-(2-Pyridyl)ethenyl]hexahydroazepine (3a): GC yield:
30%. Ϫ MS; m/z: 202 [Mϩ], 187 [Mϩ Ϫ CH3], 173 [Mϩ Ϫ C2H5],
145 [Mϩ Ϫ C4H9], 131 [Mϩ Ϫ C5H11], 117 [Mϩ Ϫ C6H13], 106
[Mϩ Ϫ C6H13N].
PyϪCH2), 2.54 (m, 2 H, PyϪCH2ϪCH2), 2.39 (m, 8 H, CH2ϪN).
Ϫ
13C{1H} NMR (91 MHz, 25°C, CDCl3): δ ϭ 159.8 (C-2), 149.0
(C-6), 136.1 (C-4), 123.0 (C-3), 121.0 (C-5), 58.1 (PyϪCϪC), 51.6
(CϪNϪCϪCϪPy), 44.1 (CϪNH), 35.2 (PyϪC). Ϫ MS; m/z: 191
N-[2-(2-Pyridyl)ethyl]hexahydroazepine (3b): GC yield (before
hydrogenation): 30%; GC yield (after hydrogenation): 59%; isolated
yield: 36% (323 mg). Ϫ 1H NMR (360 MHz, 25°C, CDCl3): δ ϭ
[Mϩ], 149 [Mϩ
[HNC4H8NCH2ϩ].
Ϫ
C2H4N], 106 [C5H4NϪC2H4ϩ], 99
(E)-N-[2-(2-Pyridyl)ethenyl]piperazine (6b): GC yield: 15%. Ϫ MS;
m/z: 189 [Mϩ], 147 [Mϩ Ϫ C2H4N], 133 [Mϩ Ϫ C3H6N], 106
[C5H4NϪC2H4ϩ].
3
8.37 [d, J(H,H) ϭ 5.6 Hz, 1 H, 6-H], 7.56 [t, 3J(H,H) ϭ 8.8 Hz,
3
4-H], 7.16 (m, 1 H, 3-H), 7.07 (m, 1 H, 5-H), 2.94 [t, J(H,H) ϭ
4.7 Hz, 4 H, CH2ϪNϪPy], 2.75 (m, 4 H, PyϪCH2ϪCH2), 1.64
(m, 8 H, CH2ϪCH2ϪCH2ϪN). Ϫ 13C{1H} NMR (91 MHz, 25°C,
CDCl3): δ ϭ 160.4 (C-2), 149.0 (C-6), 136.0 (C-4), 123.0 (C-3),
120.9 (C-5), 58.0 (PyϪCϪC), 54.6 (CϪNϪEt), 35.9 (PyϪC), 27.6
(CϪCϪCϪN), 26.8 (CϪCϪCϪN). Ϫ MS; m/z: 204 [Mϩ], 112
[C6H12NCH2].
Bis{N,NЈ-[2-(2-pyridyl)ethyl]}piperazine (6c): GC yield (before
1
hydrogenation): 31%; GC yield (after hydrogenation): 46%. Ϫ H
3
NMR (360 MHz, 25°C, CDCl3): δ ϭ 8.48 [d, J(H,H) ϭ 5.9 Hz, 2
3
4
H, 6-H], 7.56 [dt, J(H,H) ϭ 11.4 Hz, J(H,H) ϭ 1.7 Hz, 2 H, 4-
H], 7.15 [d, 3J(H,H) ϭ 11.4 Hz, 2 H, 3-H], 7.06 (m, 2 H, 5-H), 2.84
[t, 3J(H,H)
ϭ 4.7 Hz, 4 H, PyϪCH2], 2.75 (m, 4 H,
Reaction of 2-Vinylpyridine with Morpholine: In a procedure anal-
ogous to the synthesis of 1, 0.38 mL of morpholine (4.40 mmol)
and 1.90 mL of 2-vinylpyridine (17.6 mmol) in 10 mL of THF were
treated in the presence of 45 mg of [Rh(cod)2]BF4 (0.11 mmol) and
58 mg of PPh3 (0.22 mmol).
PyϪCH2ϪCH2), 2.79 [t, 3J(H,H) ϭ 4.7 Hz, 8 H, CH2ϪN]. Ϫ
13C{1H} NMR (91 MHz, 25°C, CDCl3): δ ϭ 159.9 (C-2), 149.2
(C-6), 136.3 (C-4), 123.2 (C-3), 121.2 (C-5), 58.0 (PyϪCϪC), 57.3
(CϪNϪCϪCϪPy), 35.4 (PyϪC).
(E)-N-[2-(2-Pyridyl)ethenyl]-NЈ-[2-(2-pyridyl)ethyl]piperazine
(6d): GC yield: 15%. Ϫ MS; m/z: 294 [Mϩ], 279 [Mϩ Ϫ CH3], 189
[Mϩ Ϫ C5H4NϪC2H4], 161, 133, 106 [C5H4NϪC2H4ϩ].
(E)-N-[2-(2-Pyridyl)ethenyl]morpholine (4a): GC yield: 2%. Ϫ MS;
m/z: 190 [Mϩ], 159 [Mϩ Ϫ CH3O], 131 [Mϩ Ϫ C3H7O], 118 [Mϩ
Ϫ C4H8O], 105 [C5H4NϪC2H4ϩ].
Reaction of 2-Vinylpyridine with N-Methylpiperazine: In a pro-
cedure analogous to the synthesis of 1, 0.49 mL of N-methylpipera-
zine (4.40 mmol) and 1.90 mL of 2-vinylpyridine (17.6 mmol) in 10
mL of THF were treated in the presence of 45 mg of [Rh(cod)2]BF4
(0.11 mmol) and 58 mg of PPh3 (0.22 mmol).
N-[2-(2-Pyridyl)ethyl]morpholine (4b): GC yield (before hydrogen-
ation): 98%; GC yield (after hydrogenation): > 99.9%; isolated
yield: 81% (684 mg). Ϫ 1H NMR (360 MHz, 25°C, CDCl3): δ ϭ
3
3
8.50 [d, J(H,H) ϭ 4.8 Hz, 1 H, 6-H], 7.55 [dt, J(H,H) ϭ 7.8 Hz,
3J(H,H) ϭ 4.8 Hz, 1 H, 4-H], 7.19 [d, J(H,H) ϭ 7.8 Hz, 1 H, 3-
H], 7.08 (m, 1 H, 5-H), 3.66 [t, J(H,H) ϭ 4.5 Hz, 4 H, CH2ϪO],
3
(E)-N-[2-(2-Pyridyl)ethenyl]-NЈ-methylpiperazine (7a): GC yield:
20%. Ϫ MS; m/z: 203 [Mϩ], 188 [Mϩ Ϫ CH3], 159 [Mϩ Ϫ C2H6N],
131 [Mϩ Ϫ C4H10N], 118, 106 [C5H4NϪC2H4ϩ].
3
2.98 (m,
2
H, PyϪCH2ϪCH2ϪN), 2.75 (m,
2
H,
3
PyϪCH2ϪCH2ϪN), 2.50 [t, J(H,H) ϭ 4.5 Hz, 4 H, CH2ϪN]. Ϫ
13C{1H} NMR (91 MHz, 25°C, CDCl3): δ ϭ 159.8 (C-2), 148.8 N-[2-(2-Pyridyl)ethyl]-NЈ-methylpiperazine (7b): GC yield (before
(C-6), 135.8 (C-4), 122.7 (C-3), 120.7 (C-5), 66.4 (CH2ϪO), 58.2 hydrogenation): 62%; GC yield (after hydrogenation): 82%; isolated
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132
1129

M. Beller, H. Trauthwein, M. Eichberger, C. Breindl, T. E. Müller
FULL PAPER
yield: 65% (586 mg). Ϫ 1H NMR (360 MHz, 25°C, CDCl3): δ ϭ
Reaction of 4-Vinylpyridine with Morpholine: In a procedure anal-
3
8.42 [d, J(H,H) ϭ 5.8 Hz, 1 H, 6-H], 7.50 (m, 1 H, 4-H), 7.08 (m, ogous to the synthesis of 1, 0.38 mL of morpholine (4.40 mmol)
1 H, 3-H), 7.00 (m, 1 H, 5-H), 2.94 (m, 2 H, PyϪCH2ϪCH2), 2.70 and 1.90 mL of 4-vinylpyridine (17.6 mmol) in 10 mL of THF were
(m, 2 H, PyϪCH2), 2.54 (s, br., 4 H, NϪCH2), 2.48 (s, br., 4 H, treated in the presence of 45 mg of [Rh(cod)2]BF4 (0.11 mmol) and
NϪCH2), 2.21 (s, 3 H, NϪCH3). Ϫ 13C{1H} NMR (91 MHz, 58 mg of PPh3 (0.22 mmol).
25°C, CDCl3): δ ϭ 160.2 (C-2), 149.1 (C-6), 136.2 (C-4), 123.0 (C-
N-[2-(4-Pyridyl)ethyl]morpholine (11): GC yield: 54%; isolated
3), 121.0 (C-5), 58.2 (PyϪCϪC), 54.9 (CH2ϪN), 52.9 (CH2ϪN),
yield: 44% (37 mg). Ϫ 1H NMR (360 MHz, 25°C, CDCl3): δ ϭ
45.9 (NϪCH3), 35.7 (PyϪC). Ϫ MS; m/z: 205 [Mϩ], 161 [Mϩ
Ϫ
3
3
8.28 [d, J(H,H) ϭ 4.5 Hz, 2 H, H-2], 7.01 [d, J(H,H) ϭ 4.5 Hz,
C2H6N], 149 [Mϩ
Ϫ Ϫ C4H8N], 106
C3H6N], 135 [Mϩ
3
2 H, 3-H], 3.60 [t, J(H,H) ϭ 4.4 Hz, 4 H, CH2ϪO], 2.67 (m, 2 H,
[C5H4NϪC2H4ϩ].
PyϪCH2ϪCH2), 2.51 (m, 2 H, PyϪCH2), 2.40 [t, 3J(H,H) ϭ
4.4 Hz, 4 H, CH2N]. Ϫ 13C{1H} NMR (91 MHz, 25°C, CDCl3):
δ ϭ 149.5 (C-2), 149.1 (C-4), 124.0 (C-3), 66.7 (CϪO), 59.1
(PyϪCϪC), 53.4 (CϪN), 32.4 (PyϪC). Ϫ MS; m/z: 192 [M Ϫ Hϩ],
132, 106 [C5H4NϪC2H4ϩ], 100 [CH2ϭN(CH2)4Oϩ].
Reaction of 2-Vinylpyridine with NЈ-Phenylpiperazine: In a pro-
cedure analogous to the synthesis of 1, 0.67 mL of N-phenylpipera-
zine (4.40 mmol) and 1.90 mL of 2-vinylpyridine (17.6 mmol) in 10
mL of THF were treated in the presence of 45 mg of [Rh(cod)2]BF4
(0.11 mmol) and 58 mg of PPh3 (0.22 mmol).
[(1,2,5,6-η)-1,5-Cyclooctadiene]bis[N-(2-vinylpyridine)]rhodium(I)
Tetrafluoroborate (12): 100 mg of [Rh(cod)Cl]2 (0.20 mmol) and
80 mg of AgBF4 (0.41 mmol) were dissolved in 2 mL of THF and
the solution was stirred for 10 min. After filtering off the AgCl
precipitate, the orange solution was cooled to 0°C and 94 mg of 2-
vinylpyridine (0.90 mmol) was added. After stirring the reaction
mixture for several minutes, a yellow precipitate was obtained.
(E)-N-[2-(2-Pyridyl)ethenyl]-NЈ-phenylpiperazine (8a): GC yield:
8%. Ϫ MS; m/z: 265 [Mϩ], 207 [Mϩ Ϫ C3H8N], 160 [Mϩ
C5H4NϪC2H3], 120 [C5H4NϪC2H4Nϩ], 104 [C5H4NϪC2H2ϩ].
Ϫ
N-[2-(2-Pyridyl)ethyl]-NЈ-phenylpiperazine (8b): GC yield (before
hydrogenation): 91%; GC yield (after hydrogenation): 99%; isolated
1
yield: 88% (1033 mg). Ϫ H NMR (360 MHz, 25°C, CDCl3): δ ϭ
3
3
8.52 [d, J(H,H) ϭ 5.9 Hz, 1 H, 6-H], 7.60 [dt, J(H,H) ϭ 7.7 Hz, After filtration, the crude product was washed three times with 1
4J(H,H) ϭ 1.7 Hz, 1 H, 4-H], 7.26 (m, 3 H, 3-H, H-8), 7.12 (m, 1 mL of THF and three times with pentane. Drying in vacuo fur-
H, H-10), 6.99 (m, 3 H, 5-H, H-9), 3.28 [t, 3J(H,H) ϭ 4.7 Hz, 4 H, nished 154 mg of 12 (76%). Ϫ 1H NMR (400 MHz, CDCl3, 20°C):
CH2ϪN], 3.10 (m, 2 H, PyϪCH2ϪCH2), 2.94 (m, 2 H, PyϪCH2),
δ ϭ 8.92 (s, br., 1 H, 6-H), 8.71 (s, br., 1 H, H-7), 7.66 [t, 3J(H,H) ϭ
3
2.79 [t, 3J(H,H) ϭ 4.7 Hz, 4 H, CH2ϪN]. Ϫ 13C{1H} NMR 7.9 Hz, 1 H, 4-H], 7.55 [d, J(H,H) ϭ 7.9 Hz, 1 H, 3-H], 7.32 (s, 1
3
(91 MHz, 25°C, CDCl3): δ ϭ 160.2 (C-2), 151.2 (C-7), 149.1 (C-
6), 136.3 (C-4), 129.0 (C-9), 123.2 (C-3), 121.2 (C-5), 119.7 (C-
10), 116.0 (C-8), 58.3 (PyϪCϪC), 53.1 (CϪN), 52.9 (CϪN), 35.7
H, 5-H), 6.05 [d, br., J(H,H) ϭ 17.6 Hz, 2 H, H-8], 4.17 [s, br., 2
H, CH (cod)], 3.90 [s, br., 2 H, CH (cod)], 2.81 [s, br., 2 H, CH2
(cod)], 2.64 [s, br., 2 H, CH2 (cod)], 2.10 [s, br., 2 H, CH2 (cod)],
(PyϪC). Ϫ MS; m/z: 267 [Mϩ], 175 [C6H5ϪN(C4H8NCH2)ϩ], 161 1.84 [s, br., 2 H, CH2 (cod)]. Ϫ 13C NMR (100 MHz, CDCl3,
[C6H5ϪN(C4H8N)ϩ],
[C5H4NϪC2H4NCH3ϩ],
[C5H4NϪC2H4ϩ].
148
[C5H4NϪC2H4N(CH2)2ϩ],
120
[C5H4NϪC2H4Nϩ],
135 20°C): δ ϭ 157.1 (C-2), 151.0 (C-6), 138.2 (C-8), 135.7 (C-4), 124.4
106 (C-5), 123.0 (C-7), 121.8 (C-3), 85.4 [CH (cod)], 83.9 [CH (cod)],
1
31.5 [CH2 (cod)], 29.6 [CH2 (cod)]. Ϫ At Ϫ60°C, in both the H-
NMR and the 13C-NMR spectra, a second set of weak resonances
Reaction of 4-Vinylpyridine with Piperidine: In a procedure anal-
ogous to the synthesis of 1, 0.44 mL of piperidine (4.40 mmol) and
1.90 mL of 4-vinylpyridine (17.6 mmol) in 10 mL of THF were
treated in the presence of 45 mg of [Rh(cod)2]BF4 (0.11 mmol) and
58 mg of PPh3 (0.22 mmol).
(w) appears, which has only 1/10 of the intensity of the main one
1
(ss): H NMR (400 MHz, CDCl3, Ϫ60°C): δ ϭ 9.43 (w, m, 1 H),
3
3
8.92 [ss, d, J(H,H) ϭ 4.4 Hz, 1 H, 6-H], 8.74 [ss, dd, J(H,H) ϭ
11.0 Hz, 3J(H,H) ϭ 17.0 Hz, 1 H, H-7], 8.08 [w, dd, 3J(H,H) ϭ
11.0 Hz, 3J(H,H) ϭ 17.0 Hz], 7.66 [ss, t, 3J(H,H) ϭ 7.9 Hz, 1 H,
3
N-[2-(4-Pyridyl)ethyl]piperidine (9): GC yield: 57%; isolated yield:
36% (301 mg). Ϫ 1H NMR (360 MHz, 25°C, CDCl3): δ ϭ 8.34 [d,
4-H], 7.55 [ss, d, J(H,H) ϭ 8.0 Hz, 1 H, 3-H], 7.42 (w, m, 1 H),
7.28 (ss, m, 1 H, 5-H), 6.09 [ss, dd, br., 3J(H,H) ϭ 17.6 Hz,
3J(H,H) ϭ 11.0 Hz, 2 H, H-8], 6.00 (w, m, 1 H), 5.89 [w, d,
3J(H,H) ϭ 11.0 Hz], 4.16 [ss, m, 2 H, CH (cod)], 4.06 (w, s, 1 H),
3.93 (w, s, 1 H), 3.83 [ss, m, 2 H, CH (cod)], 2.84 [ss, m, 2 H, CH2
(cod)], 2.64 [ss, m, br., 2 H, CH2 (cod)], 2.17 [ss, m, 2 H, CH2
(cod)], 1.97 (w, m, 1 H), 1.82 (w, m, 1 H), 1.84 [ss, br., 2 H, CH2
(cod)]. Ϫ 13C NMR (100 MHz, CDCl3, Ϫ60°C): δ ϭ 157.1 (ss, C-
2), 156.0 (w, C-2), 151.1 (ss, C-6), 150.6 (w, C-6), 138.4 (ss, C-8),
138.1 (w, C-8), 136.5 (w, C-4), 135.6 (ss, C-4), 124.7 (w, C-5), 124.5
(ss, C-5), 123.5 (ss, C-7), 122.3 (w, C-7), 122.0 (ss, C-3), 121.6 (w,
C-3), 88.2 [w, d, 1J(C,Rh) ϭ 11.7 Hz, CH (cod)], 85.2 [ss, d,
1J(C,Rh) ϭ 11.7 Hz, CH (cod)], 84.9 [ss, d, 1J(C,Rh) ϭ 11.7 Hz,
CH (cod)], 81.2 [w, d, 1J(C,Rh) ϭ 11.7 Hz, CH (cod)], 32.1 [ss,
CH2 (cod)], 30.6 [w, CH2 (cod)], 30.4 [w, CH2 (cod)], 29.1 [ss, CH2
(cod)]. Ϫ C22H26BF4N2Rh (508.17): calcd. C 52.0, H 5.2, N 5.5;
found C 51.8, H 5.3, N 5.4.
3
3J(H,H) ϭ 4.9 Hz, 2 H, H-2], 7.01 [d, J(H,H) ϭ 4.9 Hz, 2 H, 3-
H], 2.65 (m,
2 H, PyϪCH2ϪCH2ϪN), 2.44 (m, 2 H,
PyϪCH2ϪCH2ϪN), 2.37 (m, 4 H, NϪCH2), 1.47 (m, 4 H,
NϪCH2ϪCH2), 1.31 (m, 2 H, NϪCH2ϪCH2ϪCH2). Ϫ 13C{1H}
NMR (91 MHz, 25°C, CDCl3): δ ϭ 149.6 (C-2), 149.6 (C-4), 124.1
(C-3), 59.8 (PyϪCϪCϪN), 54.4 (CϪN), 32.9 (PyϪC), 25.9
(NϪCϪC), 24.3 (NϪCϪCϪC). Ϫ MS; m/z: 190 [M Ϫ Hϩ], 105
[C5H4NϪC2H3ϩ], 98 [CH2ϭN(CH2)5ϩ].
Reaction of 4-Vinylpyridine with Hexahydroazepine: In a procedure
analogous to the synthesis of 1, 0.50 mL of hexahydroazepine
(4.40 mmol) and 1.90 mL of 4-vinylpyridine (17.6 mmol) in 10 mL
of THF were treated in the presence of 45 mg of [Rh(cod)2]BF4
(0.11 mmol) and 58 mg of PPh3 (0.22 mmol).
N-[2-(4-Pyridyl)ethyl]hexahydroazepine (10): GC yield: 21%; iso-
1
lated yield: 13% (116 mg). Ϫ H NMR (360 MHz, 25°C, CDCl3):
δ ϭ 8.40 [d, 3J(H,H) ϭ 4.9 Hz, 2 H, H-2], 7.05 [d, 3J(H,H) ϭ Crystal Data and Structure Refinement of 12: Crystals were grown
4.9 Hz, 2 H, 3-H], 2.71 (m, 8 H, PyϪCH2ϪCH2ϪNϪCH2), 1.17 by slow diffusion of Et2O into a solution of [Rh(cod)(2-vinylpyri-
(m, 8 H, NϪCH2ϪCH2ϪCH2). Ϫ 13C{1H} NMR (91 MHz, 25°C, dine)2]CF3SO3 in CH2Cl2. A yellow crystal of dimensions 0.35 ϫ
CDCl3):
δ
ϭ
149.7 (C-2), 149.6 (C-4), 124.3 (C-3), 58.9
0.30 ϫ 0.17 mm was mounted by the Lindeman technique. Cell
(PyϪCϪCϪN), 54.4 (CϪN), 33.4 (PyϪC), 27.9 (NϪCϪC), 27.0 constants were determined by least-squares refinement of 5000 re-
(NϪCϪCϪC). Ϫ MS; m/z: 203 [Mϩ], 112 [C6H12NCH2ϩ].
flections in the intervall 16.8° < 2Θ < 49.8° with the program
1130
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132

Anti-Markonikov Reactions, 6
FULL PAPER
CELL.[16] Crystal data: monoclinic P21/n; a ϭ 11.3081(7) A, b ϭ the tosylate. R1 ϭ 0.0281, for F2 > 2 σ(F2); wR2 ϭ 0.0701;[17]
˚
3
Goof(F2) ϭ 1.035; ∆ρmax ϭ 0.40, ∆ρmin ϭ Ϫ0.50 eϪ Ϫ3. The data
A
˚
˚
˚
17.0699(6) A, c ϭ 12.2946(7) A, β ϭ 90.911(6)°; V ϭ 2372.9(2) A ;
formula unit ϭ C23H26F3N2O3RhS with Z ϭ 4; FW ϭ 570.43; analysis and the drawing were made using the programs STRUX-
F(000) ϭ 1160; µ(Mo-Kα) ϭ 8.59 cmϪ1; λ(Mo-Kα) ϭ 0.71069 A; V, [18] SIR-92,[19] SHELXL-93,[20] and SCHAKAL-97.[21]
˚
ρ
calcd. ϭ 1.597 g cmϪ3. Preliminary examination and data collection
were carried out with an imaging-plate diffraction system (IPDS;
STOE & Cie) equipped with a rotating anode (NONIUS FR591;
50 kV; 80 mA) and graphite monochromator. The data were col-
lected at 293(2) K with an exposure time of 5.0 min per image
(rotation scan modus from φ ϭ 0.0° to 300° with ∆φ ϭ 1°). 24641
reflections were collected (2.05° < Θ < 24.6°). Final full-matrix
least-squares refinement (on F2) based on 3760 unique reflections
of which 3753 were used converged with 452 variable parameters
and 15 restraints. Non-hydrogen atoms were refined aniso-
tropically, hydrogen atoms were refined isotropically with U(H) ϭ
1.2 Ueq(parent atom). R1 ϭ 0.0300, for F2 > 2 σ(F2); wR2 ϭ
0.0770;[17] Goof(F2) ϭ 0.953; ∆ρmax ϭ 0.56, ∆ρmin ϭ Ϫ0.42 eϪ
Acknowledgments
We thank Dr. E. Herdtweck and Dr. W. Scherer (TU München)
for performing the X-ray analyses. Prof. B. Hanson (Virginia Tech)
is thanked for helpful comments on this manuscript. H. T. thanks
the Fonds der Chemischen Industrie for a fellowship and T. E. M.
for a Liebig-Stipendium. Financial support (Be 1931Ϫ3/1) from the
Deutsche Forschungsgemeinschaft (DFG) and loans of precious
metals by the Degussa AG and the Hoechst AG are gratefully
acknowledged.
A
Ϫ3. The data analysis and the drawing were made using the pro-
grams and
STRUX-V,[18] SIR-92,[19] SHELXL-93,[20]
SCHAKAL-97.[21]
[1]
M. Beller, H. Trauthwein, M. Eichberger, C. Breindl, T. E.
Müller, O. Thiel, J. Herwig, Chem. Eur. J. 1999, 5, 1306.
[2]
[(1,2,5,6-η)-1,5-Cyclooctadiene](N-morpholine)[N-(2-vinylpyridine)]-
rhodium(I) Trifluoromethylsulfonate (13): 100 mg of [Rh(cod)(2-vi-
nylpyridine)2]CF3SO3 (0.18 mmol) was dissolved in 1 mL of THF.
16 mg of morpholine was added to the yellow solution. Immedi-
ately a yellow precipitate was obtained, which was filtered off and
washed three times with 1 mL of THF and 1 mL of pentane. After
drying in vacuo, 83 mg (84%) of 13 was obtained. Ϫ 1H NMR
(400 MHz, CD2Cl2, 20°C): δ ϭ 8.85 (s, 1 H, 6-H), 8.38 (s, br., 1
For a recent review see: T. E. Müller, M. Beller, Chem. Rev.
[2a]
1998, 98, 675. Ϫ
D. R. Coulson (Du Pont), US 3.758.586,
[2b]
1973; Chem. Abstr. 1973, 79, 125808g. Ϫ
D. R. Coulson,
Tetrahedron Lett. 1971, 429. Ϫ [2c] L. S. Hegedus, Angew. Chem.
1988, 100, 1147; Angew. Chem. Int. Ed. Engl. 1988, 27, 1113. Ϫ
[2d] A. L. Casalnuovo, J. L. Calabrese, D. Milstein, J. Am. Chem.
[2e]
Soc. 1988, 110, 6738. Ϫ
D. Steinborn, B. Thies, I. Wagner,
[2f]
´
M. R. Gagne, T. J.
[2g]
R. Taube, Z. Chem. 1989, 29, 333. Ϫ
Marks, J. Am. Chem. Soc. 1989, 111, 4108. Ϫ
D. Selent, D.
Scharfenberg-Pfeiffer, G. Reck, R. Taube, J. Organomet. Chem.
3
[2h]
´
M. R. Gagne, C. L. Stern, T. J. Marks, J.
H, H-7), 7.48 [d, J(H,H) ϭ 6.5 Hz, 1 H, 4-H], 7.80 (s, 1 H, 3-H),
1991, 415, 417. Ϫ
Am. Chem. Soc. 1992, 114, 275. Ϫ [2i] J.-J. Brunet, D. Neibecker,
K. Philippot, Tetrahedron Lett. 1993, 34, 3877. Ϫ [2j] R. C. Lar-
3
7.41 (s, 1 H, 5-H), 6.29 [d, J(H,H) ϭ 17.0 Hz, 1 H, H-8 (trans)],
3
6.03 [d, J(H,H) ϭ 11.0 Hz, 1 H, H-8 (cis)], 4.34 [s, br., 2 H, CH
ock, T. R. Hightower, L. A. Hasvold, K. P. Peterson, J. Org.
[2k]
(cod)], 3.63 [s, br., 7 H, CH (cod), NϪH, CH2ϪO], 2.79 (s, br., 2
H, NϪCH2), 2.53 [s, br., 6 H, CH2 (cod), NϪCH2], 1.9 [s, br., 4
H, CH2 (cod)]. Ϫ 13C NMR (100 MHz, CDCl3, 20°C): δ ϭ 156.2
(C-2), 149.2 (C-6), 137.3 (C-8), 134.9 (C-4), 124.9 (C-5), 123.5 (C-
7), 121.3 (C-3), 82.9 [CH (cod)], 65.5 (CϪO), 48.0 (CϪN), 29.3
[CH2 (cod)]. Ϫ IR (KBr): ν˜ ϭ 3215 cmϪ1 s, 2941 m, 2987 m, 1601
m, 1480 s, 1444 m, 1272 ss, 1263 ss, 1249 ss, 1153 ss, 1029 ss, 880 s.
Ϫ MS; (FAB) m/z: 316 [Mϩ Ϫ morpholine]. Ϫ C19H28BF4N2ORh
(552.41): calcd. C 44.9, H 5.2, N 4.8; found C 44.9, H 4.7, N 5.2.
Chem. 1996, 61, 3584. Ϫ
Y. Li, T. J. Marks, J. Am. Chem.
Y. Li, T. J. Marks, J. Am. Chem. Soc.
Y. W. Li, T. J. Marks, Organometallics
[2l]
Soc. 1996, 118, 707. Ϫ
[2m]
1996, 118, 9295. Ϫ
1996, 15, 10212. Ϫ [2n] C. Hahn, J. Sieler, R. Taube, Chem. Ber.
[2o]
1997, 130, 939. Ϫ
R. Dorta, P. Egli, F. Zürchner, A. Togni,
J. Am. Chem. Soc. 1997, 119, 10857. Ϫ [2p] C. Hahn, A. Vitagli-
ano, F. Giordano, R. Taube, Organometallics 1998, 17, 2060.
[3] [3a]
M. Beller, M. Eichberger, H. Trauthwein, Angew. Chem.
1997, 109, 2306; Angew. Chem. Int. Ed. Engl. 1997, 36, 2225. Ϫ
[3b]
M. Beller, M. Eichberger, H. Trauthwein, Catalysis of Or-
ganic Reactions (Ed.: F. Herkes), Marcel Dekker, 1998.
[4]
[4a] G. Roscher, F. Hofmann, K. A. Adey, W. Jeblick, H.-J. Klim-
isch in UllmannЈs Enzyclopädie der Technischen Chemie, vol. 23,
4th ed. (Ed.: W. Gerhartz), VCH, Weinheim, 1983, p. 612. Ϫ
Crystal Data and Structure Refinement of 13: Crystals were grown
by slow diffusion of Et2O into a solution of [Rh(cod)(morpho-
line)(2-vinylpyridine)]CF3SO3 in CH2Cl2. A yellow crystal of di-
mensions 0.25 ϫ 0.27 ϫ 0.1 mm was mounted by the Lindeman
technique. Cell constants were determined by least-squares refine-
ment of 1998 reflections in the intervall 27.3° < 2Θ < 51.7° with
the program CELL. Crystal data: triclinic PϪ1; a ϭ 9.7085(2), b ϭ
[4b]
P. C. Jain, V. Kapoor, N. Anand, A. Ahmad, G. Patnaik, J.
Med. Chem. 1967, 10, 812.
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10.7786(2), c ϭ 12.6294(2) A, α ϭ 76.3538(14)°, β ϭ 72.1748(14)°,
3
˚
γ
ϭ
65.7518(11)°;
V
ϭ
1137.86(4) A ; empirical formula
C20H28F3N2O4RhS, Z ϭ 2; FW ϭ 552.41; F(000) ϭ 564; µ(Mo-
Kα) ϭ 8.95 cmϪ1; λ(Mo-Kα) ϭ 0.71073 A; ρcalcd. ϭ 1.612 g cmϪ3
.
˚
[10]
Preliminary examination and data collection were carried out with
a Kappa-CCD equipped with a rotating anode (NONIUS FR591;
50 kV; 80 mA) and graphite monochromator. The data were col-
lected at 293(2) K with an exposure time of 20 s per image (detec-
torϪimage 30 mm, rotation-scan modus from φ ϭ 0.0° to 360° with
∆φ ϭ 1°). 15058 reflections were collected (4.60° < Θ < 26.35°).
Final full-matrix least-squares refinement (on F2) based on 3917
unique reflections converged with 367 variable parameters and 28
restraints. Non-hydrogen atoms were refined anisotropically, hydro-
gen atoms were refined isotropically with U(H) ϭ 1.2 Ueq(parent
atom) using a riding model. The R factor is slightly increased due
to disorder in the cod ligand (C4 and C7), the 2-vinylpyridine and
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Eur. J. Inorg. Chem. 1999, 1121Ϫ1132
1131

M. Beller, H. Trauthwein, M. Eichberger, C. Breindl, T. E. Müller
FULL PAPER
[15]
R. R. Schrock, J. A. Osborn, J. Am. Chem. Soc. 1971, 93, 3089.
C. Burla, G. Polidori, M. Camalli, SIR-92, University of Bari,
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[16]
IPDS Operating System, Version 2.7, STOE & Cie. GmbH,
[20]
Darmstadt, Deutschland, 1996.
G. M. Sheldrick, SHELXL-93, Program for the Refinement of
[17]
[18]
2
2 2
R1 ϭ Σ(ԽԽFoԽ Ϫ ԽFcԽԽ)/ΣԽFoԽ); wR2 ϭ {Σ[w(Fo Ϫ Fc ) ]/
Crystal Structures (Ed.: G. M. Sheldrick), University of
Göttingen, Germany, 1993.
Σ[w(Fo2)2]}1/2
.
[21]
G. Artus, W. Scherer, T. Priermeier, E. Herdtweck, STRUX-
V, A Program System to Handle X-ray Data, TU München,
Germany, 1994.
E. Keller, SCHAKAL-97, Albert-Ludwigs-Universität Freiburg,
Germany, 1997.
Received November 10, 1998
[I98386]
[19]
A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M.
1132
Eur. J. Inorg. Chem. 1999, 1121Ϫ1132