Intramolecular hydroamination with homogeneous zinc catalysts: Evaluation of substituent effects in N,N′-disubstituted aminotroponiminate zinc complexes

Article abstract of DOI:10.1002/chem.200601765

A series of symmetrical and unsymmetrical N,N′-disubstituted aminotroponimines (ATIHs) have been prepared. Substituents ranging from linear to cyclic alkyl groups, chelating ethers, and aryl groups were employed. The corresponding aminotroponiminate zinc

Full text of DOI:10.1002/chem.200601765

DOI: 10.1002/chem.200601765
Intramolecular Hydroamination with Homogeneous Zinc Catalysts:
Evaluation of Substituent Effects in N,N’-Disubstituted
Aminotroponiminate Zinc Complexes
[
b]
[a]
[b]
Maximilian Dochnahl, Karolin Lçhnwitz, Jens-Wolfgang Pissarek,
[
b]
[b]
[b]
[a]
Mustafa Biyikal, Sabrina R. Schulz, Sebastian Schçn, Nils Meyer,
Peter W. Roesky,* and Siegfried Blechert*
[
a]
[b]
Abstract: A series of symmetrical and
unsymmetrical N,N’-disubstituted ami-
notroponimines (ATIHs) have been
prepared. Substituents ranging from
linear to cyclic alkyl groups, chelating
ethers, and aryl groups were employed.
The corresponding aminotroponimi-
nate zinc complexes were then synthe-
sized and characterized by a number of
techniques, including by X-ray crystal-
lography. Herein we report on the in-
vestigations into their activity in the in-
tramolecular hydroamination of nonac-
tivated alkenes. We also demonstrate
that complexes bearing ligands with
cyclic alkyl groups show superior activ-
ity in a number of selected reactions
with functionalized aminoalkenes.
Keywords: heterocycles · homoge-
neous catalysis · hydroamination ·
substituent effects · zinc
Introduction
Aminotroponimines (ATIHs) are a well-known class of li-
[1]
gands that were discovered in 1960s. Early studies demon-
strated that these interesting molecules display a very rich
coordination chemistry. Thus a large number of main-group
Scheme 1. Aminotroponiminates as anionic bidentate ligands.
[2]
and transition-metal complexes have been synthesized.
ATI ligands behave as anionic bidentate nitrogen donors
and form very stable chelate complexes. Although the imine
and amine CÀN bonds in the neutral ATIH ligand have dif-
The synthesis of nitrogen-containing molecules is of great
interest for academic and industrial researchers as a large
number of natural products and pharmaceuticals contain
[4]
ferent bond lengths, the anionic ligand usually shows perfect
amine or amide moieties. Currently, these compounds are
prepared in multistep reactions leading to substantial num-
bers of byproducts and waste. Thus, hydroamination, the
direct addition of an NÀH bond to a CÀC multiple bond is
C2 symmetry, indicating a delocalization of the negative
[3]
charge through the seven-membered ring (Scheme 1).
potentially an economically and environmentally superior
[
a] Dipl.-Chem. K. Lçhnwitz, Dipl.-Chem. N. Meyer,
Prof. Dr. P. W. Roesky
[5]
process (Scheme 2). A number of catalysts have been used
[
6]
[7]
Institut für Chemie und Biochemie, Freie Universität Berlin
Fabeckstrasse 34-36, 14195 Berlin (Germany)
Fax : (+49)83-85-24-40
in this reaction based mainly on lithium, Group 4 metals,
[8–10]
[11]
the lanthanides,
the platinum metals, and more recent-
[12]
[13]
[14]
[15]
ly on calcium, copper, silver, and gold. Early tran-
sition metals offer the advantage of being highly effective
E-mail: roesky@chemie.fu-berlin.de
[
b] Dr. M. Dochnahl, Dipl.-Chem. J.-W. Pissarek,
Dipl.-Chem. M. Biyikal, Dipl.-Chem. S. R. Schulz, S. Schçn,
Prof. Dr. S. Blechert
Institut für Chemie, Technische Universität Berlin
Strasse des 17 Juni 115, 10623 Berlin (Germany)
Fax : (+49)30-31-42-36-19
E-mail: blechert@chem.tu-berlin.de
Supporting information for this article is available on the WWW
under http://www.chemistry.org or from the author.
Scheme 2. Intramolecular hydroamination of alkenes.
6654
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Chem. Eur. J. 2007, 13, 6654 – 6666

FULL PAPER
for this transformation, however, their sensitivity towards
air and moisture and their incompatibility with polar func-
tional groups limit their use in organic synthesis. In general,
late transition metals are relatively stable and compatible
with a large number of functional groups. On the other
hand, they are rather expensive and some of them are also
toxic.
Recently, we reported on the zinc-catalyzed hydroamina-
[16,17]
tion of unactivated alkynes and olefins.
demonstrate that the new catalyst N-isopropyl-N’-
isopropylamino)troponiminato(methyl)zinc,
{(iPr) ATI}ZnMe] (I), readily reacts with a large number of
We were able to
(
[
ACHTREUNG
2
functionalized aminoolefins and aminoalkynes leading to
five-, six-, and seven-membered heterocycles. Zinc complex
I has several advantages over the previously known cata-
2
Scheme 3. Synthesis and structure of [{(iPr) ATI}ZnMe] (I).
lysts: It is easily prepared in high yields (Scheme 3), it
shows an unprecedented tolerance towards polar functional
groups, and it is relatively stable towards air and moisture.
In comparison with other late-transition-metal catalysts it
shows high reactivity and furthermore zinc is an inexpensive
and nontoxic metal which makes its use in catalysis attracti-
Scheme 4. Possible reaction mechanisms for the transition-metal-cata-
lyzed hydroamination reaction.
[
18]
hemilabile coordinating groups could also protect the active
site of the catalyst from bimolecular decomposition.
[
16a]
ve.
Herein, we summarize the results of our investigations on
the effect of steric modifications to the nitrogen substituents,
including the cyclohexyl-substituted catalyst 3c, whose cata-
In principle, zinc-catalyzed hydroamination can proceed
through two mechanistic pathways: a) Lewis acid catalysis
with activation of the CÀC double (or triple) bond or b) ac-
[16b]
lytic activity has already been reported.
tivation of the amine leading to a metalloamide which then
[5b]
undergoes olefin insertion (Scheme 4).
It has been reported that hydroamination with lantha-
nides and early transition metals proceeds through the acti-
Results and Discussion
[5k]
vation of the NÀH bond.
On the other hand, with late
transition metals, activation of the CÀC multiple bond with
Based on the above-mentioned assumptions we investigated
the effect of alteration of the N-alkyl substituents of the
first generation catalyst I. Three different modifications
were examined. 1) Steric effects, by the introduction of alkyl
groups varying from small methyl to larger benzyl and cy-
clohexyl groups. This included the sterically demanding 1-
ethylpropyl group and the cyclododecyl group. 2) Chelation,
by probing the effects of tethered ethers on the behavior of
zinc complexes. This entailed the study of different tether
lengths, which would give oxazametallacycles with different
ring sizes, and their effect on the catalyst. 3) Electronic ef-
fects, by investigating the effect of basicity, and hence the
donor strength of the ligandꢁs nitrogen atoms, with com-
plexes bearing N,N’-diaryltroponimine ligands. These would
be expected to be poorer s donors and were compared with
bis-alkyl complexes.
concomitant attack by the nitrogen nucleophile has been
[18,19]
postulated.
It is still to be revealed which of the two
mechanistic possibilities is applicable to the case of zinc-cat-
alyzed hydroamination.
To find more active and stable catalysts for catalytic hy-
droamination, we focussed our attention on the modification
of the ligand structure. We postulated that modifications of
the alkyl groups on the nitrogen atoms should have a major
effect as they may influence the coordination sphere of the
zinc atom, that is, the number of molecules that are bound
to the zinc atom. Modifications to the alkyl groups may also
facilitate ring closure and in particular the displacement of
product molecules from the catalyst by substrate molecules
as a result of steric effects. The introduction of large alkyl or
Chem. Eur. J. 2007, 13, 6654 – 6666
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6655

P. W. Roesky, S. Blechert et al.
[
a]
Table 1. Synthesis of substituted 2-aminotropones.
Entry
Amine
Product
General
procedure
Yield
[%]
[
b]
1
2
3
MeNH
2
A
A
A
70
iPrNH
2
89
92
CyNH
2
Scheme 5. Synthetic path to aminotroponimines starting from tropolone.
4
5
6
7
C
C
12
H
23NH
2
B
B
A
A
74
92
73
94
Ligand synthesis: The synthesis of aminotroponimines is a
[20]
well established procedure (Scheme 5).
First, tropolone,
which can be prepared in high yields on a multigram
5
H11NH
2
[21]
[22,23]
scale, is converted into 2-tosyloxytropone.
The latter
is then treated with the corresponding amine to give the
substituted 2-aminotropone. Activation with Meerweinꢁs salt
BnNH
2
(
Et OBF ) followed by aminolysis of the resulting vinylo-
3 4
gous ether gives the desired aminotroponimine. This step-
wise approach to aminotroponimines has the advantage of
also enabling the synthesis of unsymmetrical derivatives.
To obtain high yields reproducibly, the procedures used
for the synthesis of 2-aminotropones and aminotroponi-
mines were modified. For amines with low boiling points, a
large excess of the amine was used (General procedure A).
The reactions were then conducted in a neat solution of 2-
tosyloxytropolone and the amine. On the other hand, for re-
actions with more expensive and less volatile or even solid
amines we had to find a stoichiometric procedure. In these
cases reactions were performed in refluxing ethanol using
triethylamine as a base (General Procedure B). The results
of the reactions are summarized in Table 1. The yields for
the synthesis of 2-aminotropones are in the range of 70–
MeO(CH
2
)
)
2
3
NH
NH
2
2
8
9
MeO(CH
2
A
B
92
94
PhNH
2
[a] General procedure A: 2-Tosyloxytropone, amine (excess), 08C to
room temperature, 16 h. General procedure B: 2-Tosyloxytropone
(
1 equiv), amine (1.2 equiv), NEt
3
(1.5 equiv), EtOH, reflux, 6 h. [b] Iso-
lated yield of >95% purity.
94%. The best results were obtained when a large excess of
the corresponding amine was used. 2-Methylaminotropone
use of a large excess of the amine was suitable for cheap,
volatile amines (General procedure C), whereas 2 equiva-
lents of the more expensive, nonvolatile amines were used
in reactions with activated aminotropone derivatives in etha-
nol in the presence of triethylamine as an external base
(General procedure D).
(
1a) was synthesized in 70% yield when 2-tosyloxytropone
[24]
was treated with a 40% aqueous solution of methylamine.
The already known 2-(isopropylamino)tropone (2a) was ob-
tained in high yield by modification of a literature proce-
[20]
dure.
2-(Cyclohexylamino)tropone (3a) was synthesized
in a very high yield of 92%. 2-(Cyclododecylamino)- (5a)
and 2-(1-ethylpropylamino)tropone (6a) were prepared by
applying the stoichiometric procedure B. Reaction with ben-
zylamine afforded 2-benzylaminotropone (7a) in a reasona-
ble yield of 73%. Aminotropones 8a and 9a bearing ether
moieties were also obtained in excellent yields of 94 and
By using these procedures, the corresponding aminotropo-
nimines were synthesized in high yields. The only exceptions
[24]
were
N-methyl-2-(methylamino)troponimine
[(Me) ATI]H (1b), which was synthesized in a moderate
2
[3]
yield of 50%, and N-phenyl-2-(phenylamino)troponimine
[(Ph) ATI]H (10b). The latter was isolated in a yield of only
2
9
2%, respectively (Table 1, entries 7 and 8). The 94% yield
35% which is in agreement with the literature and is attrib-
uted to the poor nucleophilicity of aniline.
obtained for the synthesis of 2-(phenylamino)tropone (10a)
is higher than the yield reported in the literature.
[3]
Having prepared this series of substituted 2-aminotro-
pones we started to synthesize the corresponding aminotro-
ponimines (Table 2). Two procedures were used in the final
step of the ATI ligand synthesis. As for the earlier step, the
Metal complex syntheses: The previously reported complex
[{(iPr) ATI}ZnMe] (I) was prepared by reaction of
2
[16a]
[(iPr) ATI]H with ZnMe in high yield.
In a similar syn-
2
2
thetic procedure we treated the neutral aminotroponimines
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Intramolecular Hydroamination with Zinc Catalysts
FULL PAPER
[
a]
Table 2. Synthesis of N,N’-disubstituted aminotroponimines.
Entry 2-Aminotropone Product
General
procedure [%]
Yield
[
b]
1
2
1a
2a
C
C
50
83
3
4
5
6
7
8
3a
3a
5a
6a
7a
8a
C
C
D
D
D
C
90
72
74
88
74
59
Scheme 6. Synthesis of aminotroponiminate-zinc complexes.
position [{(R/R’)ATI} Zn] (1c and 8c–11c) were obtained
2
(
Scheme 6B). The yields of the latter complexes and com-
pound 2c were then optimized by using the appropriate stoi-
chiometric ratio of the ligand and ZnEt . Complex 8c was
2
synthesized in THF because of the low solubility of ligand
8
b in toluene. Clearly steric arguments are not the major
factors controlling complex formation. We suggest that in-
stead the pK of the aminotroponimines is one factor that
a
influences the reactivity. We and others have previously ob-
served that the reactivity of the methyl group in compounds
of general composition L-ZnMe (L=ligand) is less than in
[16,25]
ZnMe2.
Thus, substitution of the second methyl group is
eased by using more acidic ligands. Clearly the phenyl-sub-
stituted ligands 10b and 11b are such species. Moreover, an-
cillary groups on the aminotroponimines also influence the
reactivity, as observed in 8b and 9b. We suggest that the
oxygen atoms of the tethers of the first ligand in an
9
0
1
9a
C
D
C
83
35
80
[
{(R) ATI}ZnMe] intermediate coordinate to the zinc atom
2
and thus increase the reactivity of the remaining methyl
group. Nevertheless, by using appropriate ligands both
mono- and disubstituted complexes can be obtained. We ob-
served this previously with the n-propyl-bridged bis-amino-
1
1
10a
10a
[26]
troponimine H
A
H
R
U
G
In a similar way [(iPr) ATI]H
2
2
(
2b) can react to give either [{(iPr) ATI}ZnMe] (I) or
2
[
{(iPr) ATI} Zn] (2c).
These new complexes were characterized by standard an-
2 2
[
a] General procedure C: Aminotropone (1 equiv), Et
CH Cl , room temperature, 3 h, then amine (excess) overnight. General
procedure D: Aminotropone (1 equiv), Et OBF (1 equiv), CH Cl , room
temperature, 3 h, then amine (2 equiv), ethanol, room temperature.
b] Isolated yield of >95% purity.
3 4
OBF (1 equiv),
2
2
alytical/spectroscopic techniques and the solid-state struc-
tures of selected compounds were established by single-crys-
tal X-ray diffraction. A comparison of the H and C{ H}
NMR spectra of the starting material ZnMe ( H: d=
0
3
4
2
2
1
13
1
[
1
2
1
3
1
[27]
.51 ppm, C{ H} d=À4.2 ppm)
with those of the com-
1
13
1
1
[
(R/R’)ATI]H (1b and 3–11b) with ZnMe2 in toluene at
plexes 3c ( H: d=0.08 ppm, C{ H} d=À9.9 ppm), 4c ( H:
1
3
1
1
room temperature (Scheme 6, Table 3).
d=0.04 ppm, C{ H} d=À9.9 ppm), 5c ( H: d=0.13 ppm,
C{ H} d=À10.1 ppm), 6c ( H: d=0.00 ppm, C{ H} d=
C{ H} d=
1
3
1
1
13
13
1
All reactions were judged to be complete after the evolu-
tion of gas had stopped which was usually the case after
three hours. Under these conditions the reaction of ligands
1
1
À10.8 ppm), and 7c ( H: d=À1.08 ppm,
1
13
1
À14.1 ppm) showed that the H and C{ H} NMR signals of
3
b–7b led exclusively to the formation of high yields of
the Zn-CH group have shifted to a higher field in each
3
methylzinc complexes of the general composition [{(R/
R’)ATI}ZnMe] (3c–7c) in (Scheme 6A). In contrast, by
using ligands 1b and 8b–11b, homoleptic complexes of com-
case. As observed earlier the NMR signals of the aminotro-
poniminate ligands are only slightly influenced by coordina-
tion. The most significant shifts are observed for those
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6657

P. W. Roesky, S. Blechert et al.
[
a]
Table 3. Synthesis of ATI-Zn complexes.
aminotroponiminate moiety of
the ligand is smaller than that
in a symmetric triangle (N1-
Zn1-N2 82.17(8)8).
Entry
Aminotroponimine
Zinc catalyst
General
procedure
Yield [%]
1
2
3
4
5
6
7
8
9
1b
2b
3b
4b
5b
6b
7b
8b
9b
10b
11b
[{(Me)
[{(iPr)
[{(Cy)
[{(Cy/iPr)}ZnMe] (4c)
[{(cyDod) ATI}ZnMe] (5c)
[{(iPent) ATI}ZnMe] (6c)
[{(Bn) ATI}ZnMe] (7c)
2
ATI}
ATI}
ATI}ZnMe] (3c)
2
Zn] (1c)
E/F
F
E
E
E
61
97
88
47
84
97
88
85
75
97
55
2
2
Zn] (2c)
Crystals from compound 5c
were grown from dichlorome-
thane at À238C. The solid-
state structure shows that one
solvent molecule is located in
the unit cell. Compound 5c
crystallizes in the triclinic
2
2
2
E
[
b]
2
E
[
c]
[{(C
[{(C
2
OMe)
OMe)
2
ATI}
ATI}
2
Zn] (8c)
Zn] (9c)
F
3
2
2
E/F
E/F
E/F
1
1
0
1
[{(Ph)
[{(Ph/iPr)ATI}
2
ATI}
2
Zn] (10c)
Zn] (11c)
¯
space group P1 (Figure 2). The
2
observed ZnÀN and ZnÀC
[
a] General procedure E: Aminotroponimine (1.1 mmol), ZnMe
General procedure F: aminotroponimine (1.1 mmol), ZnEt (0.6 mmol), room temperature, toluene, 3 h.
b] Slightly modified procedure. [c] Reaction in THF.
2
(1.2 mmol), room temperature, toluene, 3 h.
bond
lengths
(ZnÀN1
ZnÀN2
ZnÀC32
2
[
197.1(2) pm,
1
1
97.0(2) pm,
94.1(3)) and angles are as ex-
and
groups that are located close to the coordinating nitrogen
atoms.
pected. As observed for 3c the N-Zn-C32 angles are some-
what different (N1-Zn-C32 138.53(13)8 and N2-Zn-C32
(
139.16(13)8).
Molecular structures of 3c, 5c, and 7c in the solid state:
The structures of selected mono-, [{(R/R’)ATI}ZnMe], and
disubstituted complexes, [{(R/R’)ATI} Zn], were established
2
by single-crystal X-ray diffraction. In general, the monosub-
stituted complexes 3c, 5c, and 7c are monomeric in the
solid state (Figure 1–Figure 3). The zinc atoms are trigonal
planar, coordinated by the methyl group and the two nitro-
gen atoms (N1 and N2) of the aminotroponiminate ligand.
¯
Compound 3c crystallizes in the triclinic space group P1
having two independent molecules in the asymmetric unit
(
1
Figure 1). The observed ZnÀN bond lengths (Zn1ÀN1
97.0(2) pm, Zn1ÀN2 196.6(2) pm) are in the expected
range (e.g., in
Zn1ÀN1 198.0(4) pm, Zn1ÀN2
The bond length between the zinc and
Figure 2. Perspective ORTEP view of the molecular structure of 5c.
Thermal ellipsoids are drawn at the 50% probability level. Hydrogen
atoms have been omitted for clarity. Selected distances [pm] and angles
I
[
8]: ZnÀN1 197.1(2), ZnÀN2 197.0(2), ZnÀC32 194.2(3); N1-Zn-N2
[16]
1
95.5(4) pm).
8
2.31(10), Zn-N1-C1 114.30(2), Zn-N1-C8 124.56(2), Zn-N2-C7 114.68(2),
carbon atom of the methyl group (194.4(3) pm) is also in the
same region as that in I (194.1(5) pm). The N2-Zn1-C20
angle (137.12(11)8) is somewhat smaller than the corre-
sponding N1-Zn1-C20 angle (140.47(11)8), which may be a
result of packing effects. The N-Zn1-N bit angle inside the
Zn-N2-C20 123.46(2), N1-Zn-C32 138.53(13), N2-Zn-C32 139.16(13).
Compound 7c crystallizes in the orthorhombic space
group Pbcn with four molecules in the unit cell (Figure 3).
A crystallographic C axis is observed along Zn and C12.
2
The bond lengths between the zinc and nitrogen atoms
(
ZnÀN 197.68(2) pm) and between the zinc and methyl
carbon atom (ZnÀC12 194.1(3) pm) are in the same range
as those in 3c, 5c, and I.
Molecular structures of 1c, 8c, 9c, and 10c in the solid
state: The solid-state molecular structures of the disubstitut-
ed complexes 1c, 8c, 9c, and 10c were also determined by
single-crystal X-ray diffraction. In all these compounds the
zinc atom is surrounded by two aminotroponiminate ligands.
Thus, the zinc atoms are tetracoordinated by four nitrogen
atoms forming distorted tetrahedral coordination polyhedra
(Figures 4–7). The distortion of the coordination polyhedra
is a result of the fixed bite angle (N-Zn-N) of the aminotro-
poniminate ligand. Compound 1c crystallizes in the ortho-
rhombic space group Pbcn having four molecules in the unit
cell (Figure 4). The zinc atom is located at a center of crys-
Figure 1. Perspective ORTEP view of the molecular structure of 3c.
Thermal ellipsoids are drawn at the 50% probability level. Hydrogen
atoms have been omitted for clarity. Selected distances [pm] and angles
[
8]: Zn1ÀN1 197.0(2), Zn1ÀN2 196.6(2), Zn1ÀC20 194.4(3); N1-Zn1-N2
2.17(8), Zn1-N1-C1 114.8(2), Zn1-N1-C8 123.5(2), Zn1-N2-C7 114.77(2),
Zn1-N2-C14 124.5(2), N1-Zn1-C20 140.47(11), N2-Zn1-C20 137.12(11).
8
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Intramolecular Hydroamination with Zinc Catalysts
FULL PAPER
Figure 5. Perspective ORTEP view of the molecular structure of 8c.
Thermal ellipsoids are drawn at the 50% probability level. Hydrogen
atoms have been omitted for clarity. Selected distances [pm] and angles
Figure 3. Perspective ORTEP view of the molecular structure of 7c.
Thermal ellipsoids are drawn at the 50% probability level. Hydrogen
atoms have been omitted for clarity. Selected distances [pm] and angles
[
8]: Zn N1 201.7(2), Zn N2 198.0(2), Zn N4 198.5(2), Zn N3 198.6(2),
À
À
À
À
N1 C8 146.5(3), N2 C11 145.6(3), N3 C21 146.9(3), N4 C24 146.5(3);
N1-Zn-N2 80.94(9), N1-Zn-N3 118.14(8), N1-Zn-N4 120.47(8), N2-Zn-N4
À
À
À
À
[
8]: ZnÀN 197.74(14), ZnÀC12 194.2(3); N-Zn-N’ 81.49(8), Zn-N-C5
1
26.15(11), N-Zn-C12 139.25(4), Zn-N-C1 114.77(11).
1
29.23(8), N2-Zn-N3 131.59(9), N3-Zn-N4 81.50(8).
Figure 4. Perspective ORTEP view of the molecular structure of 1c.
Thermal ellipsoids are drawn at the 50% probability level. Hydrogen
atoms have been omitted for clarity. Selected distances [pm] and angles
[
8]: ZnÀN1 198.0(3), ZnÀN2 199.2(3), N1ÀC8 146.2(4), N2ÀC9 146.7(4);
N1-Zn-N2 80.42(10), N1-Zn-N1’ 137.37(15), N2-Zn-N2’ 121.02(14), Zn-
Figure 6. Perspective ORTEP view of the molecular structure of 9c.
Thermal ellipsoids are drawn at the 50% probability level. Hydrogen
atoms have been omitted for clarity. Selected distances [pm] and angles
N1-C8 126.0(2), Zn-N1-C1 114.9(2).
[
1
8]: ZnÀN 198.42(11); N-Zn-N’ 124.83(4), N-Zn-N’’ 81.81(6), Zn-N-C1
tallographic symmetry, thus only one ligand is in the asym-
metric unit. The bond lengths and angles are in the expected
range (ZnÀN1 198.0(3) pm, ZnÀN2 199.2(3) pm, N1-Zn-N2
14.39(9), Zn-N1-C8 125.62(9).
8
0.42(10)8, N1-Zn-N1’ 137.37(15)8, and N2-Zn-N2’
21.02(14)8).
Compound 10c crystallizes in the monoclinic space group
1
P2 /c having four molecules in the unit cell (Figure 7). As
1
¯
Compound 8c crystallizes in the triclinic space group P1
seen for compounds 1c, 8c, and 9c, the zinc atom is tetra-
coordinated. The phenyl rings of the aminotroponiminate li-
gands are rotated out of the plane of the seven-membered
rings, thus breaking the symmetry of the molecule. In com-
parison with the previously discussed structures no signifi-
cant deviations of the bond lengths and angles from the ex-
pected values were observed.
having two molecules in the unit cell (Figure 5). The oxygen
atoms of the tethers do not coordinate to the zinc atom.
Even though the side-chains point towards the zinc atom,
the shortest ZnÀO distance (ZnÀO2 289.21 pm) indicates
there is no interaction. We suggest that the side-chains fold
as a result of packing effects.
Compound 9c crystallizes in the tetragonal space group
I4 /a having four molecules in the unit cell (Figure 6). The
molecular structure shows a highly symmetrical molecule,
Hydroamination reactions: The zinc catalysts 1c–11c were
then tested in the catalytic hydroamination reactions of non-
activated alkenes and compared with the reactions of the
first generation catalyst I. We decided to investigate the cyc-
lization of four different aminoalkenes 12a–15a. These com-
pounds were chosen because they possess different groups
on the backbones of the carbon chains. Groups in these po-
sitions facilitate the cyclization process by the well-known
1
for example, a crystallographic C axis is observed along C4-
2
Zn-C4’. As a result of the high symmetry all the ZnÀN
bonds have the same length of 198.42(11) pm. The N-Zn-N
bond angles are in the expected range (N-Zn-N’ 124.83(4)8,
N-Zn-N’’ 81.81(6)8). As observed in compound 8c, the
oxygen atoms do not coordinate to the zinc atom in the
solid state. The distance between the zinc and the oxygen
atoms is over 400 pm and so no intramolecular interactions
are observed.
[28]
Thorpe–Ingold effect. On the other hand, the substrates
are distinguished by different aromatic and heteroaromatic
groups, providing information on the effect of heteroatoms
Chem. Eur. J. 2007, 13, 6654 – 6666
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6659

P. W. Roesky, S. Blechert et al.
of catalysts all showed more or less the same medium activi-
ty: After 10 h, when the reaction was stopped they showed
conversions of about 90%. This group consists of
[
{(Me) ATI} Zn] (1c), [{(iPr) ATI} Zn] (2c), [{(iPent)2-
2 2 2 2
ATI}ZnMe]
(6c),
[{(C OMe) ATI} Zn]
(9c),
3
2
2
[
{(Ph) ATI} Zn] (10c), and [{(Ph/iPr) ATI}ZnMe] (11c).
2
2
2
The third group of catalysts, which are quite unreactive in
this transformation, comprises [{(Bn) ATI}ZnMe] (7c), the
2
unsymmetric complex [{(Cy/iPr)ATI}ZnMe] (4c), and
[
{(C OMe) ATI} Zn] (8c). Catalyst 8c was by far the least
2 2 2
reactive giving a conversion of only 23%. From these pri-
mary experiments the following statements can be made.
There is a considerable difference in reactivity between
complexes bearing one or two ATI ligands (Table 4, com-
pare entries 1 and 3). First generation catalyst I is much
more reactive in this transformation than catalyst 2c. There
is also a large difference in reactivity between the two cata-
lysts bearing coordinating ether groups (Table 4, entries 9
and 10). Catalyst 9c bearing a three-carbon spacer between
the nitrogen and the ether moiety proved to be much more
reactive than catalyst 8c bearing a two-carbon spacer.
Figure 7. Perspective ORTEP view of the molecular structure of 10c.
Thermal ellipsoids are drawn at the 50% probability level. Hydrogen
atoms have been omitted for clarity. Selected distances [pm] and angles
[
8]: ZnÀN1 197.48(2), ZnÀN2 198.81(2), ZnÀN3 199.76(2), ZnÀN4
97.08(2); N1-Zn-N2 80.80(7), N1-Zn-N3 109.67(7), N1-Zn-N4 138.73(7),
N2-Zn-N3 137.51(7), N2-Zn-N4 118.86(7), N3-Zn-N4 80.93(7), Zn-N1-C1
15.59(1), Zn-N1-C8 121.25(1).
1
1
present in the molecules. All the reactions were carried out
in benzene at 808C and a relatively low catalyst loading of
We next investigated the hydroamination rates for the
cyclization of N-(2,2-diphenylpent-4-enyl)-N-(furan-2-ylme-
thyl)amine (13a). Table 5 shows that in the case of amino-
furan 13a cyclohexyl-substituted catalyst 3c again displays
the highest activity. Catalyst 5c bearing two large cyclodo-
decyl groups was the second most active catalyst. However,
it took twice as long for the reaction to reach complete con-
version. First generation catalyst I was less active in this
transformation, requiring 6 h for completion of the reaction.
A larger group of catalysts needed about 7 h to reach com-
plete conversion. For this reason it seems reasonable to pos-
tulate that in the case of substrate 13a the coordination of
the zinc atom to the substrate (or product) molecule has a
major effect on the reaction rate. Catalysts 8c and 9c
showed only minor activity in this transformation. This
2
1
.5 mol% was chosen. The reactions were conducted with
equivalent (with respect to the catalyst) of [PhNMe H][B-
2
A
C
H
T
R
E
U
N
G
(C F ) ] as a co-catalyst. The cyclization of N-(1-allylcyclo-
5 5 4
hexylmethyl)benzylamine (12a) was chosen as the first test
substrate because this substrate is widely used in catalytic
hydroamination reactions (Table 4), thus allowing the results
[11]
to be compared with previously reported catalyst systems.
It is apparent that there are three groups of catalyst. One
group showed very high activity in the transformation car-
ried out and comprises the first generation catalyst
[
{(iPr) ATI}ZnMe] (I), [{(Cy) ATI}ZnMe] (3c), and [{(cy-
2
2
Dod) ATI}ZnMe] (5c). Use of these catalysts in the hydroa-
2
mination reaction resulted in complete conversion after 1 h
for 5c and after 20–30 min for 3c and I. The second group
[
a]
Table 5. Cyclization of N-(2,2-diphenylpent-4-enyl)-N-(furan-2-ylme-
thyl)amine (13a).
Table 4. Cyclization of N-(1-allylcyclohexylmethyl)benzylamine (12a).
[
a]
[
b]
[b]
Entry
Catalyst
iPr) AT I{ }( ZnMe] (I)
[{(Me) ATI} Zn] (1c)
iPr) AT I{ }( Zn] (2c)
[{(Cy) ATI}ZnMe] (3c)
[{(Cy/iPr)}ZnMe] (4c)
t [h]
Conversion [%]
Entry
Catalyst
iPr) AT I{ }( ZnMe] (I)
[{(Me) ATI} Zn] (1c)
iPr) AT I{ }( Zn] (2c)
[{(Cy) ATI}ZnMe] (3c)
[{(Cy/iPr)}ZnMe] (4c)
t [h]
Conversion [%]
1
2
3
4
5
6
7
8
9
[
2
0.5
10
10
0.3
10
1
10
10
10
10
10
10
quant.
91
1
2
3
4
5
6
7
8
9
[
2
6
7
12
2.5
7
5
9
7
quant.
91
2
2
2
2
[
2
2
91
[
2
2
91
[c]
[c]
2
quant. (91)
2
quant. (95)
70
quant.
99
96
quant.
quant.
quant.
quant.
78
[
[
cyDod)
iPent) A{ T( I}ZnMe] (6c)
ATI}ZnMe] (7c)
2
{A( TI}ZnMe] (5c)
[
[
cyDod)
iPent) A{ T( I}ZnMe] (6c)
ATI}ZnMe] (7c)
2
{A( TI}ZnMe] (5c)
2
2
[{(Bn)
2
73
23
94
84
[{(Bn)
2
[{(C
[{(C
2
OMe)
OMe)
2
ATI}
ATI}
2
Zn] (8c)
Zn] (9c)
[{(C
[{(C
2
OMe)
OMe)
2
ATI}
ATI}
2
Zn] (8c)
Zn] (9c)
96
24
7
10
11
12
3
2
2
10
11
12
3
2
2
[{(Ph)
[{(Ph/iPr)ATI}
2
ATI}
2
Zn] (10c)
Zn] (11c)
[{(Ph)
[{(Ph/iPr)ATI}
2
ATI}
2
Zn] (10c)
Zn] (11c)
quant.
quant.
2
88
2
7
[
[
[
a] Reaction conditions: 2.5 mol% catalyst and 2.5 mol% [PhNMe
2
H]
. [b] Determined by H NMR spectroscopy.
c] Isolated yield of the analytically pure sample.
[a] Reaction conditions: 2.5 mol% catalyst and 2.5 mol% [PhNMe
[B(C F ) ] in 0.5 mL C D
6 5 4 6 6
2
H]
. [b] Determined by H NMR spectroscopy.
[c] Isolated yield of the analytically pure sample.
1
1
B(C
6
F
5
)
4
] in 0.5 mL C
6
D
6
6660
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ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 6654 – 6666

Intramolecular Hydroamination with Zinc Catalysts
FULL PAPER
could be explained by chelation of the ligand and the sub-
strate to the zinc atom, making the catalyst coordinatively
saturated and hence slowly reacting.
was only as active as the majority of the investigated cata-
lysts giving about 80–90% yields. Astonishingly, the binary
catalyst [{(iPr) ATI} Zn] (2c) reacted as fast as catalyst I in
2
2
The cyclization of the norbornene derivative 14a was in-
vestigated next (Table 6). This was prepared in three steps
from norbornene-2-carbonitrile. This carbonitrile was depro-
tonated with LDA and alkylated with allyl bromide in excel-
lent yield. The resulting nitrile was then treated with LiAlH4
leading to the corresponding primary amine, which was
treated with thiophene-2-carbaldehyde. The imine thus
this transformation. This is in contrast to the cyclization of
substrate 12a, in which I showed a much higher activity.
Again the reactions involving catalysts 8c and 9c bearing
chelating moieties were considerably slower than the rest.
Asymmetric induction by the substrate during the cycliza-
tion process was too weak to induce any diastereoselectivity
in the studied reactions.
formed was then reduced with NaBH to give the secondary
amine 14a (Scheme 7).
Intramolecular hydroamination of symmetrical dienes
leads to the formation of heterocycles bearing a side-chain
with an alkene moiety. This alkene can then be used for
other synthetically interesting transformations. The reaction
itself is of particular interest because during a single cycliza-
tion two new stereocenters are formed of which one is an
all-carbon quaternary stereocenter. Hence it was important
for us to find out if it would be possible to obtain any diaste-
reoselectivity in this cyclization reaction. As substrate 15a
lacks large groups in the b position with respect to the
amine, we had to use 5 mol% of the catalyst and 2.5 mol%
of the co-catalyst in order to obtain reasonable conversions.
However, all the reactions were still conducted at 808C
(Table 7).
The cyclization of diene 15a revealed a dramatic differ-
ence in the reactivities of the catalysts tested. Catalyst 3c re-
mains the most active in this reaction. Use of this catalyst in
the test reaction resulted in complete conversion after only
3 h. All the other investigated catalysts were far less reac-
tive. Catalyst I needed 24 h for complete conversion, that is,
eight times longer, and catalyst 5c required 60 h, the reac-
tion thus being 20 times slower. The other catalysts were
much less reactive. With the majority of the catalysts we ob-
served only 50–70% conversion after seven days (168 h).
This means that catalyst 3c is around 100 times more reac-
tive than the average catalyst with this substrate. Catalysts
4
Scheme 7. Reagents and conditions: a) 1. iPr
8C; 2. allyl bromide, 08C to RT, 94%; b) LiAlH
c) 1. thiophene-2-carbaldehyde, MeOH, RT, 6 h; 2. NaBH
6 h, 81%.
2
NH, nBuLi, THF, À78 to
, Et O, 16 h, 94%;
(1.5 equiv),
0
4
2
4
1
Aminoalkene 14a is of interest because it contains both
an interesting thiophene heteroaromatic system and a bicy-
clic system that could be further functionalized. We thought
it would be interesting to compare the hydroamination con-
versions achieved after a certain time with the different cat-
alysts. We estimated that the best comparison of reactivity
could be made when the reaction had been in progress for
several hours (Table 6).
Once again, catalyst 3c with two cyclohexyl groups was
by far the most active: It took only 2 h to reach 96% con-
version. The same conversion was obtained with catalyst 5c
after 4 h. On the other hand, the reaction with the first gen-
eration catalyst I was much slower and after 7 h only 88%
conversion had been achieved. This means that catalyst I
[
a]
Table 7. Cyclization of diene 15a.
[
a]
Table 6. Cyclization of bicyclic amine 14a.
[b,c]
Entry
Catalyst
iPr) AT {I (} ZnMe] (I)
[{(Me) ATI} Zn] (1c)
iPr) AT {I (} Zn] (2c)
[{(Cy) ATI}]ZnMe] (3c)
[{(Cy/iPr)}ZnMe] (4c)
t [h]
Conversion [%]
[
b]
Entry
Catalyst
[ iPr) A (T I]ZnMe (I)
[(Me) ATI] Zn (1c)
[ iPr) A (T I] Zn (2c)
[(Cy) ATI]ZnMe (3c)
[(Cy/iPr)ATI]ZnMe (4c)
[ cyDod() ATI]ZnMe (5c)
[ iPent)(ATI]ZnMe (6c)
[(Bn) ATI]ZnMe (7c)
t [h]
d.r.
Conversion [%]
1
2
3
4
5
6
7
8
9
[
2
7
7
7
2
7
4
7
7
7
7
7
7
88
82
86
96 (86)
83
2
2
1
2
3
4
5
6
7
8
9
2
24
168
168
3
168
60
168
168
168
168
168
168
1.3:1
1.0:1
1.15:1
1.3:1
1.2:1
1.35:1
1.2:1
1.3:1
n.d.
quant.
62
[
2
2
2
2
[
d]
2
2
2
56
[
c]
2
quant. (97)
[
[
cyDod)
iPent) A{ (T I}ZnMe] (6c)
ATI}ZnMe] (7c)
2
{ A( TI}ZnMe] (5c)
96
91
80
60
64
87
77
59
quant.
55
2
2
[{(Bn)
2
2
[{(C
[{(C
2
OMe)
OMe)
2
ATI}
ATI}
2
Zn] (8c)
Zn] (9c)
2
47
3
25
71
10
11
12
3
2
2
[ C
[(C
2
OM (e )
OMe)
2
ATI]
ATI]
2
Zn (8c)
Zn (9c)
[{(Ph)
[{(Ph/iPr)ATI}
2
ATI}
2
Zn] (10c)
Zn] (11c)
10
11
3
2
2
n.d.
1.1:1
1.3:1
2
[(Ph)
[(Ph/iPr)ATI]
2
ATI]
2
Zn (10c)
Zn (11c)
1
2
2
70
[
[
[
a] Reaction conditions: 2.5 mol% catalyst and 2.5 mol% [PhNMe
2
H]
. [b] Determined by H NMR spectroscopy.
c] The diastereomeric ratio (d.r.) was 1:1 in each case. [d] Isolated yield
1
B(C
6
F
5
)
4
] in 0.5 mL C
6
D
6
[a] Reaction conditions: 5.0 mol% of catalyst and 2.5 mol% of
1
[PhNMe
2 6 5 4 6 6
H][B(C F ) ] in 0.5 mL C D . [b] Determined by H NMR spec-
of the analytically pure sample.
troscopy. [c] Isolated yield of the analytically pure sample.
Chem. Eur. J. 2007, 13, 6654 – 6666
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6661

P. W. Roesky, S. Blechert et al.
8
c and 9c were again slower than the other investigated cat-
vent and the residual solvent signals were used as the internal references
(
3 6 6
CDCl : d=7.26 and 77.0 ppm; C D : d=1.15 and 128.1 ppm). The fol-
alysts; in particular, catalyst 8c was virtually unreactive in
this transformation. The diastereoselectivity of this transfor-
mation was very low in all the investigated cases. Catalyst
lowing abbreviations have been used to describe the peak patterns when
appropriate: s (singlet), d (doublet), t (triplet), m (multiplet), and br
(
broad). Mass spectra were recorded with a Finnigan MAT 95 SQ or a
5
c bearing large cyclododecyl groups displayed the highest
Varian MAT 771 spectrometer using the electronic impact technique (EI)
with an ionization energy of 70 eV or by using the fast atom bombard-
ment (FAB) technique with caesium. IR spectra were obtained with a
Perkin-Elmer 881 or Nicolet Magna 750 spectrometer. Melting points
were determined with a Leica Galen III instrument and are uncorrected.
Elemental analyses were carried out with an Elementar vario EL appara-
tus.
diastereoselectivity of 1.35:1. On the other hand, the diaste-
reoselectivity reported for a similar compound is about the
same.
fluenced by the size of the substituent on the ligand. When
the somewhat smaller catalysts I and 3c were used in the re-
action, the selectivity diminished to 1.3:1. Catalyst 1c bear-
ing only small methyl groups showed no diastereoselectivity
at all in this transformation.
[10e]
The observed diastereoselectivity seemed to be in-
Catalysis: General procedure for the zinc-catalyzed hydroamination reac-
tion:
(430 mmol).
PhNMe H][B
A
predried NMR tube was charged with the aminoalkene
solution of the catalyst (11 mmol, 2.5 mol%) and
] (9 mg, 11 mmol, 2.5 mol%) in C (0.5 mL) was
A
[
2
A
H
R
U
G
6
F
5
)
4
6 6
D
added under nitrogen. The NMR tube was flame-sealed under vacuum.
The reaction mixture was then heated to 808C for the stated time. The
reaction progress was monitored by H NMR spectroscopy. When the re-
Conclusions
1
action was judged to be complete, the crude reaction mixture was sub-
jected to column chromatography on silica gel.
We have synthesized a series of aminotroponiminate zinc
complexes with different substituents on the nitrogen atoms.
A number of reliable procedures for the synthesis of the li-
gands and the catalysts have been developed. Most of the
complexes could be characterized by single-crystal X-ray
structure analysis. We have tested their activity in a number
of hydroamination reactions. Substrates bearing several sub-
stituents on the carbon backbone and different functional
groups were employed to investigate the effect of both het-
eroatoms and substrate geometry on the reaction. We have
demonstrated that zinc catalysts are indeed highly active
catalysts in this transformation. Most importantly, we dis-
Ligand synthesis
General procedure A for the synthesis of 2-(alkylamino)tropones: 2-To-
[
13]
syloxytropone
(2.73 g, 10.0 mmol) was added in one portion to the
neat amine (15 mL) at 08C. The mixture was allowed to warm to room
temperature and stirred overnight. All volatiles were removed under re-
duced pressure and the oily residue was taken up in 2n NaOH (15 mL)
and CH
30 mL). The combined organic phases were washed with brine (20 mL)
and dried with MgSO . The crude product was purified by flash column
chromatography (SiO ).
General procedure B for the synthesis of 2-(alkylamino)tropones: 2-Tosy-
2 2 2 2
Cl (30 mL). The aqueous phase was extracted with CH Cl (2”
4
2
[
23]
loxytropone (2.73 g, 10.0 mmol), the corresponding amine (12.6 mmol),
and triethylamine (1.53 g, 15.1 mmol) were dissolved in ethanol (25 mL).
The mixture was refluxed for 6 h and then cooled to room temp. All vol-
atiles were removed under reduced pressure and the oily residue was
covered the new complex [{(Cy) ATI}ZnMe] (3c) which
2
[16b]
showed superior reactivity in all the test reactions.
We at-
tribute this to both a higher reactivity and a better long-
term stability. It has also been demonstrated that alkylzinc
complexes bearing one ATI ligand, [{(R/R’)ATI}ZnMe],
were in general more reactive than their homoleptic coun-
taken up in 2n NaOH (15 mL) and CH
was extracted twice with CH Cl (30 mL). The combined organic phases
were washed with brine (20 mL) and dried with MgSO . The crude prod-
uct was purified by flash column chromatography (SiO ).
General procedure Cfor the synthesis of N,N’-dialkylaminotroponimines:
2 2
Cl (30 mL). The aqueous phase
2
2
4
2
terparts, [{(R/R’)ATI} Zn]. The incorporation of donating
2
Et
3
OBF
4
(1.75 g, 9.21 mmol) was dissolved in CH
2
Cl
Cl
2
(10 mL). A solution
2
(10 mL) was slowly
ether groups into the ring substituents led to a loss of activi-
ty in the hydroamination reaction. We have shown that
there are major differences in the reactivities of catalysts 8c
and 9c bearing two- and three-carbon spacers, respectively,
in the side-chain. It seems that coordinative saturation and
thus deactivation of the catalyst is more effective with cata-
lyst 8c. Modification of the electronic properties by chang-
ing to phenyl groups did not have any significant effect on
the reactivity. Finally, we have demonstrated that incorpora-
tion of oxygen atoms into the substrates led to prolonged re-
action times. We ascribe this to the complexation of the oxo-
philic zinc atom which reduces its reactivity.
of the 2-(alkylamino)tropone (9.20 mmol) in CH
2
added. The solution was stirred at room temperature for 3 h, cooled to
08C, and the corresponding amine (20 mL) was then slowly added. The
solution was allowed to warm to room temperature and stirred overnight.
All volatiles were removed under reduced pressure and the oily residue
was taken up in 2n NaOH (10 mL) and CH
phase was extracted twice with CH Cl (20 mL). The combined organic
phases were washed with brine (20 mL) and dried with MgSO . The
crude product was purified by flash column chromatography (SiO ).
General procedure D for of the synthesis of N,N’-dialkylaminotroni-
mines: Et OBF (620 mg, 3.26 mmol) was dissolved in CH Cl (5 mL). A
solution of the 2-alkylaminotropone (3.04 mmol) in CH Cl (5 mL) was
2 2
Cl (20 mL). The aqueous
2
2
4
2
3
4
2
2
2
2
slowly added. The solution was stirred at room temperature for 3 h and
then all volatiles were removed in vacuo. The residue was taken up in
ethanol (15 mL) and the corresponding amine (7.91 mmol) was added.
The mixture was stirred at room temperature until TLC analysis showed
completion of the reaction. Then all volatiles were removed under re-
duced pressure, the oily residue was taken up in 2n NaOH (10 mL) and
Experimental Section
CH
0 mL). The combined organic phases were washed with brine (20 mL)
and dried with MgSO . The crude product was purified by flash column
chromatography (SiO ).
2-(Methylamino)tropone (1a): Compound 1a was prepared in accord
2 2 2 2
Cl (20 mL). The aqueous phase was extracted with CH Cl (2”
General methods: Deuteriated benzene was purchased from Deutero
2
GmbH and stored over 4 Š molecular sieves prior to use. [PhNMe
(C ] was purchased from Strem. Silica gel 60 F254 plates were used for
TLC analyses. Flash column chromatography was performed on silica gel
2
H][B-
4
A
C
H
T
R
E
U
N
G
6 5 4
F )
2
1
13
(
MP Silica, 32–63, 60 Š). H and C NMR spectra were recorded with a
[
24]
Bruker AM 400 or DRX 500 spectrometer using CDCl or C as sol-
3
6
D
6
with a modified literature procedure in 70% yield.
6662
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ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 6654 – 6666

Intramolecular Hydroamination with Zinc Catalysts
FULL PAPER
2
-(Isopropylamino)tropone (2a): Compound 2a was prepared in accord
N-Cyclohexyl-2-(cyclohexylamino)troponimine [(Cy)
2
ATI]H (3b): Prepa-
[
20]
with a modified literature procedure in 89% yield.
ration according to general procedure C afforded 3b as a yellow oil in
1
9
0% yield. H NMR (CDCl
3
, 400 MHz): d=1.24–1.47 (m, 10H), 1.60–
2
-(Cyclohexylamino)tropone (3a): Preparation according to general pro-
1
1.68 (m, 2H), 1.72–1.82 (m, 4H), 1.84–1.95 (m, 4H), 3.47–3.55 (m, 2H),
3
cedure A afforded 3a as a yellow solid in 92% yield. H NMR (CDCl ,
4
2
6
7
2
.05 (t, J=9.2 Hz, 1H), 6.29 (d, J=11.6 Hz, 2H), 6.65–6.71 (m, 2H),
00 MHz): d=1.23–1.46 (m, 5H), 1.64–1.72 (m, 1H), 1.76–1.86 (m, 2H),
.01–2.10 (m, 2H), 3.45–3.55 (m, 1H), 6.58 (d, J=10.8 Hz, 1H), 6.64 (t,
1
3
.88 ppm (brs, 1H; NH). C NMR (CDCl
3
, 100 MHz): d=24.8, 26.0,
). MS (EI, 70 eV): m/z
1
3
6.9, 32.9, 53.5, 109.7, 116.9, 132.4, 151.4 ppm (C
q
J=9.4 Hz, 1H), 7.15 (t, J=12.4 Hz, 1H), 7.21–7.37 ppm (m, 1H).
C
+
NMR (CDCl
3
, 100 MHz): d=24.7, 25.6, 32.1, 51.1, 108.8, 121.7, 128.1,
), 176.4 ppm (C ). MS (EI, 70 eV): m/z (%): 203
100) [M ], 160 (37), 146 (39), 121 (40), 98 (38), 93 (65), 55 (23). HRMS:
calcd for C13 17NO: 203.1310; found: 203.1309. Elemental analysis calcd
%) for C13 17NO: C 76.81, H 8.43, N 6.85; found: C 76.60, H 8.23, N
(%): 284 (58) [M ], 241 (17), 213 (17), 201 (100), 131 (19), 73 (54).
1
36.2, 137.1, 154.6 (C
q
q
HRMS: calcd for C19
H
28
N
2
: 284.2252; found: 284.2256. Elemental analy-
: C 80.23, H 9.92, N 9.85; found: C 79.92, H
+
(
sis calcd (%) for C19
H
28
N
2
H
H
9.98, N 9.51.
(
N-Isopropyl-2-(cyclohexylamino)troponimine
[(Cy/iPr)ATI]H
(4b):
7
.12.
Preparation from 3a by the reaction of isopropylamine according to gen-
eral procedure C afforded 4b as a yellow oil in 72% yield. H NMR
(CDCl , 400 MHz): d=1.24 (d, J=6.3 Hz, 6H), 1.27–1.47 (m, 5H), 1.61–
3
1
2
-(Cyclododecylamino)tropone (5a): Preparation according to general
1
procedure B afforded 5a as a pale brownish solid in 74% yield. H NMR
(
CDCl
3
, 400 MHz): d=1.32–1.52 (m, 18H), 1.53–1.64 (m, 2H), 1.70–1.82
1.69 (m, 1H), 1.74–1.83 (m, 2H), 1.88–1.97 (m, 2H), 3.50 (sept., J=
4.1 Hz, 1H), 3.82 (sept., J=6.3 Hz, 1H), 6.06 (t, J=9.2 Hz, 1H), 6.28 (d,
J=11.2 Hz, 2H), 6.66–6.71 (m, 2H), 7.77 ppm (brs, 1H; NH). C NMR
(
m, 2H), 3.69–3.79 (m, 1H), 6.55 (d, J=10.6 Hz, 1H), 6.63 (t, J=9.4 Hz,
1
3
13
1
1
1
H), 7.12 (d, J=11.3 Hz, 1H), 7.19–7.31 ppm (m, 2H). C NMR (CDCl
00 MHz): d=21.2, 23.2, 23.3, 23.8, 24.1, 29.1, 49.1, 108.5, 121.6, 127.9,
36.3, 137.1, 155.1 (C ), 176.5 ppm (C ). MS (EI, 70 eV): m/z (%): 287
3
,
(CDCl
3
, 100 MHz): d=23.0, 24.9, 26.0, 32.9, 45.9, 53.5, 109.5, 110.0, 117.0,
), 151.6 ppm (C ). MS (EI, 70 eV): m/z (%): 244
(88) [M ], 229 (52), 201 (100), 161 (61), 147 (20), 132 (24), 131 (30).
HRMS: calcd for C16 : 244.1939; found: 244.1944. Elemental analy-
sis calcd (%) for C16 : C 78.64, H 9.90, N 11.46; found: C 78.56, H
.83, N 11.65.
N-Cyclododecyl-2-(cyclododecylamino)troponimine
132.4, 132.5, 151.3 (C
q
q
q
q
+
+
(
(
100) [M ], 244 (22), 160 (34), 146 (28), 133 (29), 132 (29), 122 (20), 121
39), 93 (26), 84 (22), 55 (24). HRMS: calcd for C19 29NO: 287.2249;
H
H
24
N
2
found: 287.2251.
H
24
N
2
9
2
-(1-Ethylpropylamino)tropone (6a): Preparation according to general
1
procedure B afforded 6a as a yellow solid in 92% yield. H NMR
CDCl , 400 MHz): d=0.94 (t, J=7.5 Hz, 6H), 1.55–1.78 (m, 4H), 3.44–
.53 (m, 1H), 6.56–6.68 (m, 2H), 7.11–7.19 (m, 1H), 7.20–7.28 ppm (m,
2
[(cyDod) ATI]H
(
3
(5b): Preparation according to general procedure D afforded 5b as
1
3
2
1
yellow crystals (ethanol) in 74% yield. M.p. 1288C. H NMR (CDCl3,
1
3
H). C NMR (CDCl
36.3, 137.1, 155.7 (C
3
, 100 MHz): d=10.3, 26.7, 55.2, 108.8, 121.7, 127.8,
), 176.4 ppm (C ). MS (EI, 70 eV): m/z (%): 191
400 MHz): d=1.29–1.55 (m, 42H), 1.63–1.74 (m, 2H), 3.67–3.74 (m, 2H),
6.04 (t, J=9.2 Hz, 1H), 6.25 (d, J=11.2 Hz, 2H), 6.65–6.73 (m, 2H),
q
q
+
13
(
C
41) [M ], 163 (11), 162 (100), 105 (12), 77 (12). HRMS: calcd for
17NO: 191.1310; found: 191.1311.
-(Benzylamino)tropone (7a): Preparation according to general proce-
7.93 ppm (brs, 1H; NH). C NMR (CDCl , 100 MHz): d=21.3, 23.2,
3
12
H
23.3, 24.3, 24.6, 29.7, 51.6, 109.3, 116.6, 132.4, 151.7 ppm (C ). MS (EI,
q
+
2
70 eV): m/z (%): 452 (100) [M ], 298 (35), 297 (32), 285 (89), 132 (34),
1
dure A afforded 7a as pale yellow crystals in 73% yield. M.p. 1248C. H
NMR (CDCl , 400 MHz): d=4.56 (d, J=6.0 Hz, 2H), 6.53 (d, J=
0.4 Hz, 1H), 6.69 (t, J=9.4 Hz, 1H), 7.14–7.37 (m, 8H), 7.60 ppm (brs,
131 (64). HRMS: calcd for C31
H
52
N
2
: 452.4130; found: 452.4134. Elemen-
: C 82.24, H 11.58, N 6.19; found: C
tal analysis calcd (%) for C31
H
52
N
2
3
1
1
1
82.02, H 11.40, N 6.69.
1
3
H; NH). C NMR (CDCl
27.8, 128.9, 129.2, 136.2, 136.4 (C
3
, 100 MHz): d=47.0, 109.1, 122.7, 127.3,
), 137.4, 155.4 (C ), 177.0 ppm (C ).
N-(1-Ethylpropyl)-2-(1-ethylpropylamino)troponimine
2
[(iPent) ATI]H
q
q
q
(6b): Preparation according to general procedure C afforded 6b as a
+
1
MS (EI, 70 eV): m/z (%): 211 (100) [M ], 210 (17), 106 (40), 91 (94), 77
11), 65 (21). HRMS: calcd for C14 13NO: 211.0997; found: 211.0991. El-
13NO: C 79.59, H 6.20, N 6.63;
yellow solid in 88% yield. H NMR (CDCl , 400 MHz): d=0.87 (t, J=
3
(
H
7
9
1
.4 Hz, 12H), 1.48–1.68 (m, 8H), 3.46 (pent., J=6.0 Hz, 2H), 6.03 (t, J=
emental analysis calcd (%) for C14
H
.1 Hz, 1H), 6.28 (d, J=11.2 Hz, 2H), 6.63–6.70 (m, 2H), 7.96 ppm (brs,
found: C 79.38, H 6.21, N 6.60.
13
H; NH). C NMR (CDCl
3
, 100 MHz): d=10.5, 27.5, 57.2, 109.4, 116.6,
+
2
-(2-Methoxyethylamino)tropone (8a): Preparation according to general
132.3, 152.1 ppm (C
232 (77), 131 (100), 161 (30), 132 (38), 131 (77). HRMS: calcd for
: 261.2331; found: 261.2330.
N-Benzyl-2-(benzylamino)troponimine [(Bn)
according to general procedure D afforded 7b as a yellow solid in 74%
q
). MS (EI, 70 eV): m/z (%): 261 (28) [M ], 260 (25),
1
procedure A afforded 8a in 94% yield. H NMR (CDCl
.99 (pent., J=5.9 Hz, 2H), 3.35 (s, 3H), 3.43 (q, J=6.1 Hz, 2H), 3.49 (t,
J=5.9 Hz, 2H), 6.56 (d, J=10.4 Hz, 1H), 6.65 (t, J=9.5 Hz, 1H), 7.13 (d,
3
, 400 MHz): d=
1
17 28 2
C H N
2
ATI]H (7b): Preparation
1
3
J=11.3 Hz, 1H), 7.18–7.28 (m, 2H), 7.41 ppm (brs, 1H; NH). C NMR
CDCl , 100 MHz): d=28.6, 40.2, 58.8, 70.0, 108.5, 122.0, 128.4, 136.3,
37.2, 155.8 (C
, 149 (10), 148 (100), 135 (20), 134 (48), 106 (19), 105 (14), 77 (18).
HRMS: calcd for C11 : 193.1103; found: 193.1103.
-(3-Methoxypropylamino)tropone (9a): Preparation according to gener-
(
1
]
3
1
yield. M.p. 768C. H NMR (CDCl
H), 6.65 (brs, 2H), 7.04 (brs, 2H), 7.22–7.42 ppm (m, 10H). C NMR
CDCl , 100 MHz): d=49.6, 114.1 (brs), 122.1 (brs), 127.3, 128.5, 128.6,
36.0 (brs), 137.7 (brs, C ), 153.0 ppm (C ). MS (EI, 70 eV): m/z (%):
3
, 400 MHz): d=4.75 (s, 4H), 6.52 (brs,
+
), 176.7 ppm (C
q
). MS (EI, 70 eV): m/z (%): 193 (66) [M
13
q
1
(
1
3
H
15NO
2
q
q
+
2
300 (17) [M ], 209 (100), 106 (24), 91 (78), 65 (16). HRMS: calcd for
1
al procedure A afforded 9a in 92% yield. H NMR (CDCl
3
, 400 MHz):
C H N : 310.1626; found: 310.1630.
1
9
24
2
d=3.40 (s, 3H), 3.49 (q, J=5.5 Hz, 2H), 3.68 (t, J=5.5 Hz, 2H), 6.54 (d,
J=10.3 Hz, 1H), 6.67 (t, J=9.4 Hz, 1H), 7.14 (d, J=11.3 Hz, 1H), 7.21
N-(2-Methoxyethyl)-2-(2-methoxyethylamino)troponimine
(C OMe) ATI]H (8b): Preparation according to general procedure C af-
forded 8b as a brown oil in 59% yield. H NMR (CDCl
[
2
2
1
3
(
t, J=10.3 Hz, 1H), 7.22–7.28 (m, 1H), 7.40 ppm (brs, 1H; NH).
C
1
3
, 400 MHz): d=
.43 (s, 6H), 3.50 (t, J=6.0 Hz, 4H), 3.73 (t, J=6.0 Hz, 4H), 6.18 (t, J=
NMR (CDCl , 100 MHz): d=42.6, 59.0, 70.0, 108.5, 122.3, 128.9, 136.1,
3
3
9
+
1
]
37.2, 155.6 (C
, 134 (100), 106 (23), 84 (23). HRMS: calcd for C10
found: 179.0942.
q
), 176.8 ppm (C
q
). MS (EI, 70 eV): m/z (%): 179 (39) [M
13
.4 Hz, 1H), 6.31 (d, J=10.5 Hz, 2H), 6.74–6.81 ppm (m, 2H). C NMR
, 100 MHz): d=46.1, 59.0, 72.1, 110.6, 118.4, 133.3, 153.4 ppm
H13NO
2
: 179.0946;
(
(
CDCl
). MS (EI, 70 eV): m/z (%): 236 (19) [M ], 191 (100), 134 (17), 131
3
+
C
q
2
-(Phenylamino)tropone (10a): Compound 10a was prepared in accord
13 20 2 2
(18). HRMS: calcd for C H N O : 236.1525; found: 236.1522.
[
3]
with a slightly modified literature procedure in 94% yield.
N-(3-Methoxypropyl)-2-(3-methoxypropylamino)troponimine
(C OMe) ATI]H (9b): Preparation according to general procedure C af-
forded 9b as a brown oil in 83% yield. H NMR (CDCl
.01 (pent., J=6.5 Hz, 4H), 3.36 (s, 6H), 3.40 (t, J=6.8 Hz, 2H), 3.53 (t,
J=6.2 Hz, 2H), 6.13 (t, J=9.2 Hz, 1H), 6.29 (d, J=10.8 Hz, 2H), 6.71–
N-Methyl-2-(methylamino)troponimine [(Me)
1
yield.
2
ATI]H (1b): Compound
[
3
2
b was prepared in accord with a modified literature procedure in 50%
1
3
, 400 MHz): d=
[
24]
2
N-Isopropyl-2-(isopropylamino)troponimine [(iPr)
pound 2b was prepared in accord with a modified literature procedure in
8
2
ATI]H (2b): Com-
1
3
3
6.78 (m, 2H), 7.75 ppm (brs, 1H; NH). C NMR (CDCl , 100 MHz): d=
[
20]
3% yield.
30.2, 43.3, 58.7, 71.0, 110.2, 117.7, 133.0, 153.1 ppm (C
q
). MS (EI, 70 eV):
Chem. Eur. J. 2007, 13, 6654 – 6666
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6663

P. W. Roesky, S. Blechert et al.
+
m/z (%): 264 (62) [M ], 205 (100), 191 (75), 133 (40), 132 (31), 131 (54).
HRMS: calcd for C15 : 264.1838; found: 264.1837.
N-Phenyl-2-(phenylamino)troponimine [(Ph) ATI]H (10b): Compound
0b was prepared in accord with a literature procedure in 35% yield.
(78), 229 (54), 201 (100), 161 (47). HRMS: calcd for C17
322.13874; found: 322.13715.
26 2
H N Zn:
24 2 2
H N O
[N-Cyclododecyl-2-(cyclododecylamino)troponiminato]methylzinc [{(cy-
Dod) ATI}ZnMe] (5c): Preparation from 5b according to general proce-
dure E afforded 5c in 84% yield. X-ray quality crystals could be grown
2
[
3]
1
2
N-Isopropylamino-2-(phenylamino)troponimine [(iPr/Ph)ATI]H (11b):
Preparation from 3a by the reaction of isopropylamine according to gen-
eral procedure C afforded 4b as a yellow oil in 80% yield. H NMR
, 400 MHz): d=1.36 (d, J=6.4 Hz, 6H), 3.84–3.94 (m, 1H), 6.19–
.26 (m, 2H), 6.59–6.73 (m, 3H), 6.84–6.91 (m, 2H), 7.04 (tt, J=1.1, J=
1
from dichloromethane at À408C. H NMR (C
6 6
D , 500 MHz): d=0.13 (s,
1
3H), 1.31–1.42 (m, 38H), 1.54–1.57 (m, 4H), 1.88–1.92 (m, 4H), 4.02 (m,
2
9
H), 6.36 (t, J=9.0 Hz, 1H), 6.92 (d, J=11.3 Hz, 2H), 7.04 ppm (t, J=
(
CDCl
3
1
3
.4 Hz, 2H). C NMR (C
6
D
6
, 125 MHz): d=À10.1, 21.7, 23.3, 23.4, 24.2,
6
7
1
3
24.6, 31.3, 53.8, 111.3, 117.6, 134.3, 160.4 ppm. MS (EI, 80 eV): m/z (%):
.4 Hz, 1H), 7.32–7.39 (m, 2H), 7.56 ppm (brs, 1H; NH). C NMR
, 100 MHz): d=22.3, 43.8, 105.2, 111.9, 119.1, 120.4, 121.0, 122.5,
33.1, 133.9, 150.1 (C ), 151.6 (C ), 155.0 ppm (C ). MS (EI, 70 eV): m/z
+
5
1
30 (100) [M ], 515 (43), 452 (69), 409 (14), 285 (46), 215 (36), 201 (33),
31 (25). HRMS: calcd for C32 Zn: 530.3578; found: 530.3576.
(
CDCl
3
54 2
H N
1
(
(
q
q
q
+
%): 238 (22) [M ], 180 (81), 149 (26), 134 (100), 106 (77), 104 (31), 77
76). HRMS: calcd for C16
analysis calcd (%) for C16
0.27, H 7.72, N 12.17.
Synthesis of the metal complexes
[N-(1-Ethylpropyl)-2-(1-ethylpropylamino)troponiminato]methylzinc
[{(iPent) ATI}ZnMe] (6c): Preparation from 6b according to general
procedure E afforded 6c as an orange oil in 97% yield. H NMR (C
500 MHz): d=0.00 (s, 3H), 0.79 (t, J=7.4 Hz, 12H), 1.60 (m, 8H), 3.54
H
H
18
N
N
2
: 238.1470; found: 238.1470. Elemental
: C 80.63, H 7.61, N 11.75; found: C
2
1
6 6
D ,
18
2
8
(
6
2
pent, J=6.4 Hz, 4H), 6.35 (t, J=9.2 Hz, 1H), 6.74 (d, J=11.6 Hz, 2H),
1
3
.96 ppm (t, J=9.0 Hz, 2H). C NMR (C
6
D
6
, 125 MHz): d=À10.8, 11.0,
General procedure E: A solution of the corresponding aminotroponi-
mine (1.1 mmol) in toluene (10 mL) was slowly added to a solution of
ZnMe (1.2m in toluene, 1.0 mL, 1.2 mmol) in toluene (10 mL). The solu-
2
tion was stirred at room temperature for 3 h. The reaction was judged to
be complete when gas evolution had ceased. All volatiles were removed
under reduced pressure and the yellow residue was washed twice with
pentane (5 mL).
9.4, 59.9, 111.5, 117.9, 134.4, 161.4 ppm. MS (EI, 80 eV): m/z (%): 338
+
(
(
8
15) [M ], 309 (41), 260 (24), 231 (100), 201 (14), 189 (10), 161 (25), 131
43). Elemental analysis calcd (%) for C18 Zn: C 63.62, H 8.90, N
.24; found: C 63.69, H 8.81, N 8.21.
N-Benzyl-2-(benzylamino)troponiminato]methylzinc [{(Bn)
7c): A solution of aminotroponimine 7b (1.8 mmol) in toluene (10 mL)
(1.2m in toluene, 2.0 mL,
.4 mmol) in toluene (10 mL). After 30 min a solid began to precipitate
30 2
H N
[
(
2
ATI}ZnMe]
was slowly added to a solution of ZnMe
2
2
General procedure F: A solution of the aminotroponimine (1.1 mmol) in
toluene (10 mL) was slowly added to a solution of ZnEt (1.0m in tolu-
2
ene, 0.6 mL, 0.6 mmol) in toluene (10 mL). The solution was stirred at
room temperature for 3 h. The reaction was judged to be complete when
the evolution had ceased. All volatiles were removed under reduced
pressure and the yellow residue was washed twice with pentane (5 mL).
from solution. The reaction mixture was stirred for 1 h then heated until
a clear solution was observed. The solution was cooled to room tempera-
ture without stirring and then filtered. The filtered crystals were washed
1
twice with pentane (5 mL). Yield: 88%. H NMR (C
6
D
6
, 500 MHz): d=
À1.08 (s, 3H), 4.12 (s, 2H), 4.34 (s, 2H), 6.19–6.39 (m, 2H), 6.62 (d, J=
Bis[N-Methyl-2-(methylamino)troponiminato]zinc [{(Me)
Preparation from 1b according to general procedure F afforded 1c in
1% yield. X-ray quality crystals could be grown from dichloromethane
2 2
ATI} Zn] (1c):
1
1.2 Hz, 1H), 6.81 (t, J=11.1 Hz, 1H), 6.89–6.96 (m, 4H), 7.06–7.13 ppm
13
(
m, 7H). C NMR (C
6
D
6
, 125 MHz): d=À14.1, 54.2, 112.3, 116.3, 118.8,
26.9, 135.1, 139.7, 140.6, 161.0 ppm. Elemental analysis calcd (%) for
Zn: C 69.57, H 5.85, N 7.38%; found: C 70.12, H 5.87, N 7.11.
Bis[N-(2-Methoxyethyl)-2-(2-methoxyethylamino)troponiminato]zinc
6
1
1
at À408C. H NMR (C
.0 Hz, 2H), 6.42 (d, J=11.4 Hz, 4H), 6.97 ppm (t, J=9.3 Hz, 4H).
NMR (C , 125 MHz): d=37.9, 111.0, 116.1, 135.0, 162.2 ppm. MS (EI,
0 eV): m/z (%): 358 (18) [M ], 148 (16), 145 (75), 133 (57), 106 (100).
HRMS: calcd for C19 Zn: 358.113591; found: 358.11337.
Bis[N-isopropyl-2-(isopropylamino)troponiminato]zinc [{(iPr)
2c): Preparation from 2b according to general procedure F afforded 2c
6 6
D , 500 MHz): d=2.92 (s, 12H), 6.30 (t, J=
22 22 2
C H N
1
3
9
C
6
D
6
[
(
(
{(C
2
OMe)
2
ATI}
2
Zn] (8c):
A
solution of aminotroponimine 8b
+
8
2.1 mmol) in THF (10 mL) was slowly added to a solution of ZnEt
1.0m in toluene, 1.1 mL, 1.1 mmol) in toluene (10 mL) at À788C. The so-
2
28 2
H N
2
ATI}
2
Zn]
lution was slowly warmed to room temperature and stirred for 3 h. The
reaction was judged to be complete when the gas evolution had stopped.
All volatiles were removed under reduced pressure and the yellow resi-
(
1
in 97% yield. H NMR (C
.81 (sept., J=6.3 Hz, 4H), 6.23 (t, J=9.1 Hz, 2H), 6.48 (d, J=11.7 Hz,
H), 6.93 ppm (t, J=9.1 Hz, 4H). C NMR (C
8.3, 112.1, 115.4, 134.6, 160.0 ppm. MS (EI, 80 eV): m/z (%): 470 (100)
M ], 455 (74), 427 (41), 267 (11), 235 (14), 187 (44), 145 (44). HRMS
calcd for C26 Zn: 470.23879; found: 470.23859.
N-Cyclohexyl-2-(cyclohexylamino)troponiminato]methylzinc
{(Cy) ATI}ZnMe] (3c): Preparation from 3b according to general proce-
6
D
6
, 500 MHz): d=1.17 (d, J=6.3 Hz, 24H),
1
3
4
4
due was washed twice with pentane (5 mL). Yield: 85%. H NMR (C D ,
6
6
1
3
6
D
6
, 125 MHz): d=24.0,
500 MHz): d=2.82 (s, 12H), 3.45 (s, 16H), 6.23 (t, J=9.9 Hz, 2H), 6.42
1
3
(d, J=11.2 Hz, 4H), 6.91 ppm (t, J=9.2 Hz, 4H). C NMR (C D ,
6
6
+
[
125 MHz): d=50.4, 58.4, 72.6, 111.2, 115.5, 137.1, 161.4 ppm. MS (EI,
+
H
38
N
4
80 eV): m/z (%): 534 (46) [M ], 502 (10), 489 (100), 304 (25), 239 (7).
[
[
38 4 4
HRMS: calcd for C26H N O Zn: 534.218451; found: 534.21844.
2
Bis[N-(3-Methoxypropyl-2-(3-methoxypropylamino)troponiminato]zinc
[{(C OMe) ATI} Zn] (9c): Preparation from 9b according to general pro-
dure E afforded 3c in 88% yield. X-ray quality crystals could be grown
3
2
2
1
from toluene at À408C. H NMR (C
6
D
6
, 500 MHz): d=0.08 (s, 3H),
cedure F afforded 9c in 75% yield. X-ray quality crystals can be grown
1
1
.05–1.91 (m, 20H), 3.50–3.59 (m, 2H), 6.38 (t, J=9.1 Hz, 1H), 6.73 (d,
from hot toluene. H NMR (C D , 500 MHz): d=1.91–1.98 (m, 8H), 3.00
6
6
1
3
J=11.6 Hz, 2H), 6.99 ppm (dd, J=9.1, J=11.7 Hz, 2H). C NMR (C
25 MHz): d=À9.7, 25.7, 26.0, 35.2, 57.1, 111.3, 117.5, 134.1, 159.9 ppm.
MS (EI, 80 eV): m/z (%): 362 (17) [M ], 347 (11), 284 (29), 201 (100),
31 (82). Elemental analysis calcd (%) for C20 Zn: C 66.02, H 8.31,
N 7.70; found: C 65.69, H 8.65, N 7.33.
6
D
6
,
(s, 12H), 3.09 (t, J=5.8 Hz, 8H), 3.51 (m, 8H), 6.22 (t, J=9.2 Hz, 2H),
1
3
1
6 6
6.57 (d, J=11.2 Hz, 4H), 6.91 ppm (dd, J=9.1 Hz, 4H). C NMR (C D ,
+
125 MHz): d=31.8, 47.7, 57.9, 70.5, 111.6, 116.0, 134.9, 161.0 ppm. MS
+
1
H
30
N
2
(EI, 80 eV): m/z (%): 590 (37) [M ], 327 (100), 269 (10), 203 (24), 131
(9). Elemental analysis calcd (%) for C H N O Zn: C 60.85, H 7.83, N
3
0
46
4
4
9
.46; found C 60.54, H 7.74, N 9.07.
[
N-Cyclohexyl-2-(isopropylamino)troponiminato]methylzinc [{(Cy/iPr)A-
[
16b]
TI}ZnMe] (4c):
Preparation from 4b according to general procedure
Bis[N-phenyl-2-(phenylamino)troponiminato]zinc [{(Ph) ATI} Zn] (10c):
2
2
1
E afforded 4c as a brown-yellow oil in 47% yield. H NMR (C
6
D
6
,
Preparation from 10b according to general procedure F afforded 10c in
97% yield. X-ray quality crystals could be grown from toluene at À408C.
5
1
2
00 MHz): d=0.04 (s, 3H), 1.14 (d, J=6.2 Hz, 6H), 1.19 (d, J=13.0 Hz,
H), 1.34–1.52 (m, 5H), 1.62 (d, J=13.2 Hz, 2H), 1.87 (d, J=11.5 Hz,
H), 3.53 (dt, J=3.1, J=8.0 Hz, 1H), 3.76 (sept., J=6.2 Hz, 1H), 6.37 (t,
1
H NMR (C D , 500 MHz): d=6.05 (t, J=9.2 Hz, 2H), 6.44–6.50 (m,
6
6
1
3
4H), 6.90–6.95 (m, 8H), 7.03–7.06 (m, 8H), 7.16–7.20 ppm (m, 8H).
C
J=9.2 Hz, 1H), 6.59 (d, J=11.3 Hz, 1H), 6.71 (t, J=11.5 Hz, 1H),
NMR (C D , 125 MHz): d=116.7, 120.1, 123.9, 124.3, 129.7, 134.9, 149.7,
160.5 ppm. MS (EI, 80 eV): m/z (%): 606 [M ] (80), 303 (10), 272 (100),
6
6
1
3
+
7
.00 ppm (m, 2H). C NMR (C
6
D
6
, 125 MHz): d=À9.9, 24.4, 25.9, 26.2,
3
5.4, 48.3, 57.3, 111.5, 111.6, 117.7, 134.4, 134.5, 160.1, 160.2 ppm. MS
30 4
245 (9), 169 (13). HRMS: calcd for C38H N Zn: 606.176191; found:
+
+
(
EI, 80 eV): m/z (%): 322 (3) [M ], 306 (14) [M ÀCH
3
], 322 (3), 244
606.17654.
6664
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 6654 – 6666

Intramolecular Hydroamination with Zinc Catalysts
FULL PAPER
À1
Bis[N-Phenyl-2-(isopropylamino)troponiminato]zinc [{(Ph/iPr)ATI}
2
Zn]
0.959 mm , qmax =25.08, 4699 [Rint =0.0566] independent reflections mea-
sured of which 3625 were considered observed with I>2s(I), max. and
(
1
11c): Preparation from 11b according to general procedure E afforded
1
À3
1c in 55%. H NMR (C
6
D
6
, 500 MHz): d=0.97 (d, J=6.1 Hz, 6H), 1.20
min. residual electron densities 0.395 and À0.408 eA , 320 parameters,
(
d, J=6.2 Hz, 6H), 3.72 (sept., J=6.3 Hz, 2H), 6.18 (t, J=9.1 Hz, 2H),
.52 (d, J=11.6 Hz, 2H), 6.62 (t, J=10.1 Hz, 2H), 6.82 (m, 4H), 7.17 (m,
H), 7.07 ppm (m, 6H). C NMR (C D , 125 MHz): d=23.0, 23.9, 48.1,
6 6
1 2
R [I>2s(I)]=0.0348, wR (all data)=0.0734.
6
4
1
1
1
Complex 9c: C30
46 4 4 1
H N O Zn, M=592.10, tetragonal, space group I4 /a,
1
3
6
3
a=1333.30(14), c=1754.11(14) pm, V=3118.3(5)”10 pm , T=200(2) K,
Z=4, m(MoKa)=0.826 mm , qmax =29.28, 2111 [Rint =0.0391] independ-
ent reflections measured of which 1790 were considered observed with
À1
14.25, 114.5, 118.1, 123.3, 124.0, 129.6, 134.66, 134.8, 149.9, 159.6,
+
60.5 ppm. MS (EI, 80 eV): m/z (%): 538 (2) [M ], 238 (17), 149 (42),
34 (100), 106 (59). HRMS: calcd for C32
H
34
N
4
Zn (540.03): 538.20749;
I>2s(I), max. and min. residual electron densities 0.258 and
À3
found: 538.20782.
X-ray crystallographic studies on 1c, 3c, 5c, and 7c–10c: Crystals of 1c,
c, 7c, 9c, and 10c were grown from toluene. Crystals of 5c were ob-
À0.277 eA , 90 parameters, R1 [I>2s(I)]=0.0300, wR2 (all data)=
0.0757.
3
Complex 10c: C H N Zn, M=608.05, monoclinic space group P2 /c, a=
3
8
30
4
1
tained from dichloromethane and 8c from pentane. A suitable crystal
was covered in mineral oil (Aldrich) and mounted on a glass fiber. The
1213.17(10), b=1662.63(14), c=1723.14(15) pm, b=120.648(6), V=
2990.2(5)”10 pm , T=200(2) K, Z=4, m(MoKa)=0.855 mm , qmax =
6
3
À1
crystal was transferred directly to the À738C N
2
cold stream of a Stoe
IPDS II 2T diffractometer. Subsequent computations were carried out
with an Intel Pentium IV PC.
29.58, 5233 [Rint =0.0354] independent reflections measured of which
3934 were considered observed with I>2s(I), max. and min. residual
À3
electron densities 0.227 and À0.302 eA , 388 parameters, R [I>2s(I)]=
1
0
2
.0304; wR (all data)=0.0589.
All structures were solved by Patterson or direct methods (SHELXS-
[
29]
9
7
). The remaining non-hydrogen atoms were located from successive
difference Fourier map calculations. The refinements were carried out by
using full-matrix least-squares techniques on F, minimizing the function
2
2
2
(
F
o
ÀF
o o
c o c
) , where the weight is defined as 4F /2(F ) and F and F are the
observed and calculated structure factor amplitudes, using the program
[
30]
Acknowledgements
SHELXL-97. Carbon-bound hydrogen atom positions were calculated
and allowed to ride on the carbon atom to which they are bonded by as-
suming a CÀH bond length of 0.95 Š. The hydrogen atom contributions
This work was supported by the Deutsche Forschungsgemeinschaft (Gra-
duiertenkolleg: Synthetische, mechanistische und reaktionstechnische As-
pekte von Metallkatalysatoren). M.D. gratefully acknowledges a fellow-
ship from the Fonds der Chemischen Industrie (K174/11).
were calculated but not refined. The locations of the largest peaks in the
final difference Fourier map and the magnitude of the residual electron
densities in each case were of no chemical significance. Positional param-
eters, hydrogen atom parameters, thermal parameters, bond lengths and
angles have been deposited as Supporting Information.
[
[
[
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960, 82, 995–996; b) W. R. Brasen, H. E. Holmquist, R. E. Benson,
(
8c), -630415 (9c), and -630416 (10c) contain the supplementary crystal-
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Complex 1c: C18
22 2
H N Zn, M=359.77, orthorhombic space group Pbcn,
6
3
a=1391.10(14), b=1846.1(2), c=662.16(9) pm, V=1700.5(3)”10 pm ,
T=200(2) K, Z=4, m(MoKa)=1.449 mm , qmax =258, 1496 [Rint =0.0632]
À1
[
[
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Complex 3c: C20
73.58(7), b=1100.97(8), c=2007.60(13) pm, a=76.685(5), b=86.477(6),
¯
30 2
H N Zn, M=363.83, triclinic space group P1, a=
9
6
3
g=64.209(5)8, V=1883.6(2)”10 pm , T=200(2) K, Z=4, m(MoKa)=
À1
1
.306 mm , qmax =258, 6621 [Rint =0.0553] independent reflections mea-
sured of which 5389 were considered observed with I>2s(I), max. and
À3
min. residual electron densities 0.370 and À0.359 eA , 417 parameters,
1 2
R [I>2s(I)]=0.0341, wR (all data)=0.0874.
¯
2
Zn, M=617.07, triclinic, space group P1, a=
Complex 5c: C33
H
56
N
2
Cl
8
1
88.04(11), b=1101.09(10), c=1798.35(2) pm, a=101.462(8), b=
6
3
03.789(9), g=97.943(9)8, V=1641.6(3)”10 pm , T=200(2) K, Z=2,
À1
m(MoKa)=0.934 mm , qmax =29.58, 5746 [Rint =0.0498] independent re-
4
555–4563.
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À3
2
3
s(I), max. and min. residual electron densities 0.964 and À0.726 eA
,
2
44 parameters, R
1
[I>2s(I)]=0.0464; wR
2
(all data)=0.1214.
[
7] a) M. C. Wood, D. C. Leitch, C. S. Yeung, J. A. Kozak, L. L. Schafer,
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H
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N Zn, M=379.79, orthorhombic, space group Pbcn,
Angew. Chem. 2007, 119, 358–362; Angew. Chem. Int. Ed. 2007, 46,
6
3
a=626.46(5), b=2093.38(2), c=1392.52(14) pm, V=1826.6(3)”10 pm ,
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3
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À1
, qmax =29.28, 2433 [Rint =
0
.0378] independent reflections measured of which 1605 were considered
5
observed with I>2s(I), max. and min. residual electron densities 0.242
À3
and À0.337 eA , 116 parameters, R
1 2
[I>2s(I)]=0.0301; wR (all data)=
2
0
.0659.
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Complex 8c: C26
H
38
N
4
O
4
Zn, M=535.97, triclinic space group P1, a=
9
1
66.14(2), b=1033.3(2), c=1471.4(3) pm, a=98.89(3), b=95.52(3), g=
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6
3
Chem. Eur. J. 2007, 13, 6654 – 6666
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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Published online: May 16, 2007
6666
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Chem. Eur. J. 2007, 13, 6654 – 6666