Modular routes towards new N,O-bidentate ligands containing an electronically delocalised β-enaminone chelating backbone

Article abstract of DOI:10.1002/ejoc.200800372

Polyketones are synthesised by a transition-metal-catalysed copolymerisation of olefins and carbon monoxide. Nickel complexes with N,O-chelating ligands turned out to be promising catalysts in that field. In this work a series of new N,O ligands with an electronically delocalised β-enaminone backbone were synthesised and fully characterised. The ligand design was inspired by the ligand found in the most efficient nickel catalyst for polyketone synthesis and developed to a highly modular LEGO-like arsenal of reactions to versatile substituted β-enaminone ligands. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejoc.200800372

FULL PAPER
DOI: 10.1002/ejoc.200800372
Modular Routes Towards New N,O-Bidentate Ligands Containing an
Electronically Delocalised β-Enaminone Chelating Backbone
Udo Beckmann,*[a] Eva Eichberger,[a] Monika Lindner,[a] Melanie Bongartz,[a] and
Peter C. Kunz[a]
Keywords: Polyketones / β-Enaminones / N,O ligands / Bidentate chelate ligands
Polyketones are synthesised by a transition-metal-catalysed
copolymerisation of olefins and carbon monoxide. Nickel
complexes with N,O-chelating ligands turned out to be
promising catalysts in that field. In this work a series of new
N,O ligands with an electronically delocalised β-enaminone
backbone were synthesised and fully characterised. The li-
gand design was inspired by the ligand found in the most
efficient nickel catalyst for polyketone synthesis and devel-
oped to a highly modular LEGO®-like arsenal of reactions to
versatile substituted β-enaminone ligands.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
Introduction
The copolymerisation of olefins and carbon monoxide is
an area of growing interest[1] and the key reaction to poly-
ketones, a class of new polymers with outstanding proper-
ties.[2–5] Ketonex® (Shell), Carilon® (BP) or Kadel® (Sol-
vay) are registered trademarks for polyketones and a recent
market analysis by Frost & Sullivan predicts a bright future
for the polyketone market.[6] Industrially, the copolymeris-
ation reaction is catalysed by palladium complexes[7] with
high efficiencies. The major disadvantage is the high cost of
the transition metal and the fact, that the catalyst can not
be recovered from the polymer. So the search is underway
for more efficient and cheaper alternatives. Nickel turned
out to be the most promising in that field.[8–12] The most
efficient nickel catalyst for the copolymerisation of ethene
and carbon monoxide to date is shown in Figure 1. This
diamagnetic nickel(II) complex is already structurally char-
acterised[8] and contains a bidentate N,O-chelating ligand
which coordinates to the nickel center in a square planar
manner forming a six-membered chelate ring. The electron
density is delocalised over this ring system. Very little is
known to date about the influence of the substituents in the
N,O ligand on the catalytic activity of its corresponding
nickel complex. Perfluorated alkyl chains (C3F7, see Fig-
ure 1) lead to very high efficiencies of catalysis up to
11000 g of polyketone per gram Ni whereas alkoxy goups
in the same position drops the efficiency to nearly zero.[8]
Figure 1. The most efficient nickel complex for the copolymeri-
sation of ethene and CO to date.
We want to get a profound understanding of the factors
that determine the efficiency of such nickel complexes as
polyketone catalysts. Therefore we have decided to develop
a systematic series of N,O-chelating ligands inspired by the
ligand found in the most efficient nickel catalyst for poly-
ketone synthesis today. This should then enable us to fine-
tune the electron density on the transition metal and there-
with control the catalytic behaviour.
Results and Discussion
In order to vary the substitution pattern on a more gene-
ral N,O ligand we developed modular routes to N,O-biden-
tate ligands containing an electronically delocalised β-en-
aminone chelating backbone (see Figure 2). We synthesised
and fully characterised a number of new ligand molecules
meeting the mentioned criteria. In this work the focus is
on variations on the ligand framework, their coordination
chemistry will be discussed separately. The substituent R1
is gradually varied from perfluorated alkyl chains to alkyl
chains and substituted aryl residues whereas R2 is varied
from CϵN to H, NO2 or C(O)OR. The ring size, formed
by substituents R3 and R4, can be gradually varied from
[a] Institut für Anorganische Chemie und Strukturchemie,
Lehrstuhl I: Bioanorganische Chemie und Katalyse, Heinrich-
Heine-Universität Düsseldorf,
Universitätsstraße 1, 40225 Düsseldorf, Germany
Fax: +49-211-81-12287
E-mail: Udo.Beckmann@uni-duesseldorf.de
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
Eur. J. Org. Chem. 2008, 4139–4147
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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U. Beckmann, E. Eichberger, M. Lindner, M. Bongartz, P. C. Kunz
FULL PAPER
five to six- and seven-membered rings. But also open-chain derived acetoacetates such as for example ethyl
ligands, i.e. R3 and R4 being individual substituents such as 4,4,5,5,6,6,6-heptafluoro-3-oxohexanoate, which lead to R2
H, alkyl or substituted aryl, can be synthesised and some = H after decarboxylation. The above-mentioned ester is
representatives are discussed. Furthermore new ligand best prepared from ethyl 4,4,5,5,6,6,6-heptafluorobutyrate
molecules are presented comprising two β-enaminone che- and ethyl 2-bromoacetate in a Reformatsky reaction.[16]
lating backbones and are therefore capable of coordinating
Table 1. Substitution pattern of ligands and ligand precursors, lead-
two metal sites.
ing to one N,O-bidentate β-enaminonic coordination site contain-
ing R3, R4 = –(CH2)n– with n = 3,4,5 (see Scheme 1).
R1
R2
R3,R4
4
OMe
OEt
OMe
OEt
OEt
CN
CN
CN
NO2
CH2CH2CH2
5
CH2CH2CH2CH2
CH2CH2CH2CH2CH2
CH2CH2CH2
6
7
8
–N=CH–Ph CH2CH2CH2
[a]
9
–
CN
CN
CN
NO2
CN
CN
CN
CN
CN
CN
CH2CH2CH2
Figure 2. General formula of the ligands (a) and ligand precursors
(b) synthesised.
[a]
10
11
12
13
14
15
16
17
18
19
20
21
–
CH2CH2CH2CH2
CH2CH2CH2CH2CH2
CH2CH2CH2
[a]
–
[a]
–
Inspired by ligand 13 which forms the catalytically most
efficient nickel complex (see Figure 1), a possible route to
ligands with R3,R4 = –(CH2)n– (n = 3,4,5) is shown in
Scheme 1 (see Table 1). The first step is the conversion of
lactams into O-alkylated imines. This is necessary to acti-
vate the carbonyl function for the subsequent step and can
be accomplished by reaction with dialkyl sulfate[13] or
Meerwein salts such as triethyloxonium tetrafluorobo-
rate.[14] The desired products were obtained in 75–90% yield
(1–3). In the next step the substituents R2 and R1 are intro-
duced by a Knoevenagel type condensation with appropri-
ate esters such as cyanoacetates (R2 = CN, 4–6), nitro-
acetates (R2 = NO2, 7), malonates[15] [R2 = C(O)OR] or
n-C3F7
n-C3F7
n-C3F7
n-C3H7
p-O2NC6H4
p-ClC6H4
p-MeOC6H4 CN
Naph
Mes
CH2CH2CH2
CH2CH2CH2CH2
CH2CH2CH2CH2CH2
CH2CH2CH2
CH2CH2CH2
CH2CH2CH2
CH2CH2CH2
CH2CH2CH2
CH2CH2CH2
CN
CN
[a] Ligand precursor (see Figure 2b).
All compounds prepared by this method comprise at
least one oxygen bridged OR1 group owing to the ester
used. Compound 7 was already known in the literature,[17]
but we improved the synthetic protocol to simplify the
work-up and obtained twice the yield reported. In the case
of 7 two competing interactions occur: N–H–O hydrogen
bonding is possible to the carbonyl group as well as to one
nitro oxygen (see Figure 3). Thus, both E/Z isomers are
formed and are observed in the proton NMR spectrum. In
contrast, compounds 4–6 are formed only as their Z iso-
mers since N–H–O hydrogen bonding is only possible to
the carbonyl oxygen.
Figure 3. E/Z Isomerism of ligand 7.
The nitro function in 7 can be reduced to yield the very
air-sensitive amine[17] which can in situ be used for Schiff
base condensation. Using benzaldehyde the Schiff base 8
was obtained. This opens a new way to derivatise the β-
enaminones in the R2 position.
Introducing an R1 residue which is not an alkoxide re-
quires first the C(O)OR1 ester group to be cleaved under
alkaline conditions and then be decarboxylated in acidic
medium (9–12). Here, 9–11 are formed as their E/Z mixture,
Scheme 1. Synthesis of ligands containing R3, R4 = –(CH2)n– with
n = 3,4,5.
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Modular Routes Towards New N,O-Bidentate Ligands
but 12 forms a N–H–O hydrogen bond to one nitro oxygen nitrile function reacts to yield 4-(1-amino-2-cyanovinyl)-
and therefore results as its Z isomer only. The resulting vi- benzonitrile (23). No 3-amino-3-[4-(1-amino-2-cyanovinyl)-
nylic proton after decarboxylation is relatively acidic due to phenyl]acrylonitrile was found.
the electron-withdrawing group in the geminal position. We
used this to introduce a non-alkoxide R1 substituent by re-
action with carboxylic acid chlorides or carboxylic acid an-
hydrides in presence of a base such as triethylamine. The
only limitation here is the availability of the acid chloride,
so a great variety of substitutions is possible (13–21). In
some cases, N-acylation occurs as a side-reaction (42–45,
see Table 2), similar to the reaction of β-enaminonitriles
with acid chlorides.[18,19] Cyclohexanecarboxylic acid chlo-
ride exclusively leads to the N-acylated product (46). From
these observations arises the assumption that bulky, steri-
cally demanding carboxylic acid chlorides prefer the N- vs.
C-acylation.[19] The N-acylation product is easily distin-
guished from its isomeric C-acylation product by the ab-
sence of the NH resonance and the characteristic downfield
1
shift of the vinylic proton of more than 2 ppm in the H
NMR spectrum.[19] Due to the deshielding effect of the N–
H–O hydrogen bond in the C-acylated product the reso-
nance of the NH proton is shifted more than 6 ppm down-
field compared to the NH resonance in non-acylated start-
Scheme 2. Synthesis of ligands containing individual substituents
ing material. The Z-configuration of the C-acylated prod-
uct is further supported by the presence and shift of the
C=O stretching vibration in the infrared spectrum, which is
shifted to lower wave numbers due to the N–H–O hydrogen
bonding compared to the stretching frequency of a free car-
bonyl group.
R3 and R4 (R2 = CN).
Table 3. Substitution pattern of ligands and ligand precursors, lead-
ing to one N,O-bidentate β-enaminonic coordination site contain-
ing individual substituents R3 and R4, R2 = CN (see Scheme 2).
R1
R2
R3
R4
[a]
Table 2. Substitution pattern of N-acylated byproducts (see
Scheme 1).
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
–
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
p-FC6H4
p-NCC6H4
Me
Ph
Ph
p-FC6H4
Ph
Ph
Me
Me
Me
Me
Ph
Me
Me
Me
Ph
H
H
H
H
H
H
H
H
[a]
–
n-C3F7
CF3
CCl3
R1
R2
R3,R4
42
43
44
45
46
p-O2NC6H4
p-MeOC6H4
Naph
Mes
c-C6H11
CN
CN
CN
CN
CN
CH2CH2CH2
CH2CH2CH2
CH2CH2CH2
CH2CH2CH2
CH2CH2CH2
n-C3F7
n-C3F7
n-C7F15
CCl3
H
[a]
–
C(O)CCl3
Ph
p-Tol
p-Tol
Ph
Ph
p-Tol
p-Tol
[a]
–
[a]
–
All fluorinated compounds have also been characterised
[a]
–
by 19F NMR spectroscopy. As expected, the absolute mag-
CCl3
3
nitude of the JFF coupling constants in the perfluorated
n-C3F7
n-C3F7
n-C3F7
alkyl chains is lower than of the 4JFF coupling constants.[20]
3JFF coupling constants were not observed due to their
magnitude being in the order of the linewidth.
[a] Ligand precursor (see Figure 2b).
A different route has to be followed to open-chain li-
gands with R3 and R4 being individual substituents and not
Like in the case of compounds 9–11 the E/Z ratio of the
forming a closed alkyl chain (see Scheme 2 and Table 3). 3-amino-2-enenitrile does not matter when introducing R1
(E/Z)-3-Aminobut-2-enenitrile is readily commercially (24–30) by reaction with acyl chlorides or anhydrides,
available and can directly be used to react with carboxylic respectively: the newly formed hydrogen bond directs the
acid chlorides to give the corresponding C- and N-acylated product into Z configuration (see Scheme 2). In the case of
products (24–26), respectively.[19] The reaction of acetoni- 30, also the N-acylated product was observed (31). Intro-
trile with benzonitrile in presence of KOtBu gives (E/Z)-3- duction of an aryl or alkyl residue in position R4 is ac-
amino-3-phenylacrylonitrile in good yields.[21] The reaction complished by reaction with primary aryl or alkylamines in
is also successful with p-fluorobenzonitrile (22) but fails aqueous diluted acetic acid. Preparation details date back
when using pentafluorobenzonitrile. Only starting material to the year 1908,[22,23] so we re-investigated the published
is recovered in this case. With terephthalonitrile only one procedure and characterised the products (32–34) by mod-
Eur. J. Org. Chem. 2008, 4139–4147
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U. Beckmann, E. Eichberger, M. Lindner, M. Bongartz, P. C. Kunz
FULL PAPER
ern techniques such as NMR, IR and MS. The substituent Table 4. Substitution pattern of ligands leading to one N,O-biden-
R1 (35–38) can then subsequently be introduced as afore-
tate β-enaminonic coordination site containing individual substitu-
ents R3 and R4, R2 = H (see Scheme 3).
said.
R1
R2
R3
R4
(E/Z)-3-Amino-3-phenylacrylonitrile can be converted
into 3-oxo-3-phenylpropanenitrile, which has been reported
39
n-C3F7
n-C3F7
n-C3F7
H
H
H
Me
Ph
H
H
H
H
as early as 1890.[24] This reaction is also successful using 40
41
(E/Z)-3-amino-3-(4-fluorophenyl)acrylonitrile. These β-cy-
ano ketones can be used in Knoevenagel-type condensa-
tions with the designated O-alkylated enamine to introduce
R1 and R2. After the conversion of a β-enaminonitrile com-
prising an appropriate R3 residue, the corresponding β-cy-
ano ketone now bears the substituent in the future R1 posi-
tion of the target ligand molecule. This opens an alternative
route for introducing a desired substituent R1 besides the
reaction of the β-enaminonitrile with acyl chlorides or car-
boxylic anhydrides, respectively. This might be of impor-
tance, e.g. if the acyl chloride or the anhydride, respectively,
is not available.
Aromatic and aliphatic nitriles can be converted into im-
idic acid esters by reaction with dry HCl gas in absolute
alcoholic solution and subsequent deprotonation,[25–28]
which can then be used in the Knoevenagel condensation.
In our experiments, 2,2,2-trifluoroacetamide did neither re-
act with dialkyl sulfate nor with HCl/ethanol to yield ethyl
2,2,2-trifluoroacetimidate. This compound has to be pre-
pared by a different route starting from CF3CN.[29]
In order to obtain compounds with R3 = H, we started
from alkoxy acrylates such as ethyl (Z)-2-cyano-3-ethoxy-
acrylate, which is reacted with the appropriate primary or
secondary amine. The cyano group in the starting material,
representing R2 in the ligand, can be replaced by an ester[30]
or nitro function[31,32] with equal success.
Ligand molecules featuring R2 = R3 = H can be prepared
from vinyl ethers by reaction with an appropriate acyl chlo-
ride, followed by a primary amine,[36] which introduces R4,
or aqueous ammonia (R4 = H, 41).
We extended the system to ligands bearing two β-en-
aminonic coordination sites (see Scheme 4 and Table 5).
Generally, this was achieved by linking two single β-en-
aminone units together at the R1 and R4 position, respec-
tively. We synthesised several ligand molecules focusing on
perfluorated alkyl chains like in the single coordination site
ligands. Diacyl dichlorides can be used to link two β-en-
Compounds comprising R2 = H can be obtained in high
yields starting from the appropriate dimethoxyethane (see
Scheme 3 and Table 4). Reaction with an appropriate car-
boxylic acid anhydride and subsequently with a primary
amine,[33] which introduces R4, or aqueous ammonia (R4 =
H) yields the target compounds (39, 40). Karpenko et al.
prepared compounds of this type via a different route start-
ing from fluorinated β-diketones.[34] β-Enaminones com-
prising R2 = H can also be synthesised starting from ter-
minal alkynes and acyl chlorides under modified Sonoga-
shira conditions followed by the reaction with primary
amines.[35]
Scheme 4. Synthesis of ligands bearing two N,O-bidentate β-enami-
nonic coordination sites.
Scheme 3. Synthesis of ligands containing R2 = H.
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Modular Routes Towards New N,O-Bidentate Ligands
aminone units via R1. Benary et al. used 3-amino-3-phenyl- enaminone ligands, e.g. such as indigo,[39,40] are also inter-
acrylonitrile in the reaction with oxalyl dichloride in esting as potential ligands for polymerisation catalysts.
1923.[37] Similarly, reacting oxalyl dichloride with (E/Z)-3-
aminobut-2-enenitrile yields two directly connected β-en-
aminone coordination sites (47). Analogously, 2,2,3,3,4,4- Experimental Section
hexafluoropentanedioyl dichloride reacts with [pyrrolidin-
(2E/2Z)-ylidene]acetonitrile to yield the corresponding co-
ordination sites linked by a linear (CF2)3 spacer (48).
General: All solvents were dried by standard procedures. One-di-
mensional NMR spectra were recorded at room temperature, pro-
ton NMR spectra were recorded on a Bruker Avance DRX 200
spectrometer and 13C and 19F NMR spectra were recorded on a
Table 5. Substitution pattern of ligands and ligand precursors lead-
ing to two N,O-bidentate β-enaminonic coordination sites (see
Scheme 4).
Bruker Avance DRX 500 spectrometer. The proton and carbon
chemical shifts are given in ppm and referenced to the solvent resid-
ual signals[41] [CDCl3: 1H 7.26 ppm, 13C 77.16 ppm; C6D6: 1H
7.16 ppm, 13C 128.1 ppm. CD3OD: 1H 3.31 ppm, 13C 49.0 ppm;
R1
R2
R3
R4
1
(CD3)2CO: H 2.05 ppm; 13C 29.8/206.3 ppm]. The coupling con-
47
48
49
50
51
52
53
link[a]
CN
CN
CN
CN
CN
CN
CN
Me
H
stants are reported as their absolute value. Ethyl nitroacetate,[42]
CF2CF2CF2
CH2CH2CH2
(E)-3-amino-3-phenylacrylonitrile,[21]
(E)-1-ethoxy-4,4,5,5,6,6,6-
[b]
–
Me
Me
Me
Me
Me
CH2CH2
heptafluorohex-1-en-3-one[36] and (1,1-dimethoxyethyl)benzene[43]
were prepared according to literature procedures. The fluorine
chemical shifts are given relative to CFCl3. Infrared spectra were
recorded on a FT-IR Bruker IFS 66 spectrometer. EI-MS data were
recorded on a Varian MAT 311 A instrument.
n-C3F7
CH2CH2
CH2CH2
p-Ph
CCl3
[b]
–
n-C3F7
p-Ph
[a] Both carbonyl groups are directly linked together (oxalyl). [b]
Ligand precursor (see Scheme 4).
Methyl
[Cyanopyrrolidin-(2Z)-ylidene]acetate
(4):
22.6 g
(200 mmol) 5-ethoxy-3,4-dihydro-2H-pyrrole (1) and 69.3 g
(700 mmol) methyl cyanoacetate were mixed and kept for several
days at room temperature. White crystals formed which were sepa-
rated and washed with pentane to yield 33 g (85%) of 4. H NMR
(200 MHz, CDCl3, room temp.): δ = 2.13 (m, 2 H, CH2–CH2–
CH2), 2.94 (m, 2 H, CH2–C–N), 3.71 (m, 2 H, CH2–N), 3.74 (s, 3
Reaction of (E/Z)-3-aminobut-2-enenitrile with 1,2-di-
aminoethane yields a bis(β-amino)-enenitrile linked via R4
by a (CH2)2 spacer (49).[38] Further reaction with carboxylic
acid chlorides such as trichloro acetic acid chloride (51) or
2,2,3,3,4,4,4-heptafluorobutyryl chloride (50) yields the de-
sired ligand molecules with two β-enaminonic coordination
sites. Linking is also possible by the use of a phenylene
spacer if p-phenylenediamine is used instead of 1,2-diamino-
ethane. This way a bis-β-amino-ene-nitrile linked via R4
by a p-phenylene spacer is obtained (52), which can analo-
gously be reacted with 2,2,3,3,4,4,4-heptafluorobutyryl
chloride to yield the corresponding ligand with two β-en-
aminonic coordination sites (53).
1
H, CH ), 8.95 [s (br), 1 H, NH] ppm. IR (KBr disk): ν = 3318 (s,
˜
3
N–H), 2959 (m, C–H), 2202 (vs, CϵN), 1667 (s, C=O), 1598 (s,
C=C) cm–1. MS (EI): m/z = 166 [M+], 135 [M+ – OMe].
C8H10N2O2 (166.18): calcd. C 57.82, H 6.07, N 16.86; found C
57.90, H 5.77, N 16.70.
Ethyl [Cyanopiperidin-(2Z)-ylidene]acetate (5): The synthesis was
carried out according to the literature.[45] 1H NMR (200 MHz,
3
CDCl3, room temp.): δ = 1.27 (t, JHH = 7.1 Hz, 3 H, ethyl CH3),
1.79 (m, 4 H, CH2–CH2–CH2–CH2), 2.69 (m, 2 H, CH2–C–N),
Variation of the spacer might be of interest, since the
ethylene spacer provides an electronic insulation between
the two coordination sites whereas the phenylenediamine
3
3.39 (m, 2 H, CH2–N–C), 4.15 (q, JHH = 7.1 Hz, 2 H, ethyl CH2),
10.12 [s (br), 1 H, NH] ppm. IR (KBr disk): ν = 3228 (m, N–H),
˜
2956 (s, C–H), 2199 (vs, CϵN), 1666 (s, C=O), 1612 (s, C=C) cm–1.
linker allows electronic exchange. This is an additional as- MS (EI): m/z = 194 [M+], 149 [M+ – OEt]. C10H14N2O2 (194.23):
calcd. C 61.84, H 7.27, N 14.42; found C 61.54, H 7.36, N 14.09.
pect in controlling the electronic structure of coordinated
metals bound to a ligand with multiple coordination sites.
Methyl [Azepan-(2Z)-ylidene]cyanoacetate (6): 14.1 g (100 mmol) 7-
ethoxy-3,4,5,6-tetrahydro-2H-azepine (3) and 39.6 g (400 mmol)
methyl cyanoacetate were mixed and refluxed for 3 h. After cooling
to room temperature, 50 mL of methanol was added, followed by
200 mL of water. A white solid precipitated, was washed with water
Conclusions
1
and dried. Yield 11.5 g (59%). H NMR (200 MHz, CDCl3, room
We have synthesised a series of new ligand molecules
containing one or two N,O-bidentate coordination sites
with an electronically delocalised β-enaminone chelating
backbone. The ligand design was inspired by a ligand found
in a nickel(II) complex which represents the most efficient
nickel catalyst for the copolymerisation reaction of ethene
and CO to date. We presented versatile and modular routes
for the synthesis of such types of ligands rather than focus-
ing on a special pathway yielding only a single compound.
We now have a library of ligands. The coordination chemis-
try of the newly synthesised ligands and their use in nickel-
mediated (co)polymerisation reactions is currently ongoing
temp.): δ = 1.6–1.9 (m, 6 H, CH2–CH2–CH2–CH2–CH2), 2.82 (m,
2 H, CH2–C–N), 3.48 (m, 2 H, CH2–N–C), 3.79 (s, 3 H, CH3),
10.16 [s (br), 1 H, NH] ppm. IR (KBr disk): ν = 3268 (s, N–H),
˜
2931 (s, C–H), 2194 (vs, CϵN), 1656 (vs, C=O), 1605 (vs, C=C)
cm–1. MS (EI): m/z = 194 [M+], 163 [M+ – OMe]. C10H14N2O2
(194.23): calcd. C 61.84, H 7.27, N 14.42; found C 61.77, H 7.33,
N 14.17.
4,4,5,5,6,6,6-Heptafluoro-3-oxo-2-[pyrrolidin-(2Z)-ylidene]hexaneni-
trile (13): The synthesis was carried out according to the litera-
ture.[8] 1H NMR (200 MHz, CDCl3, room temp.): δ = 2.25 (qi, 3JHH
= 7.8 Hz, 2 H, CH2–CH2–CH2), 3.14 (t, 3JHH = 7.8 Hz, 2 H, CH2–
3
C–N), 3.92 (t, JHH = 7.8 Hz, 2 H, CH2–N–C), 10.70 [s (br), 1 H,
research in our group. Furthermore, naturally occurring β- NH] ppm. 19F NMR (471 MHz, CDCl3, room temp., ppm): δ =
Eur. J. Org. Chem. 2008, 4139–4147
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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4143

U. Beckmann, E. Eichberger, M. Lindner, M. Bongartz, P. C. Kunz
FULL PAPER
–80.8 (t, JFF = 8.9 Hz, 3 F, CF3), –117.8 (q, JFF = 8.9 Hz, 2 F, 24. 1H NMR (200 MHz, CDCl3, room temp.): δ = 2.46 (s, 3 H,
4
4
CO–CF2), –126.6 (m,
2
F, CF2–CF3) ppm. 13C{1H} NMR CH3), 7.65 [s (br), 1 H, NH], 10.82 [s (br), 1 H, NH] ppm. 19F
4
(126 MHz, CDCl3, room temp., not all C signals were observed): δ
= 20.1 (CH2–C–N), 34.9 (CH2–CH2–CH2), 50.8 (CH2–N–C), 109.9
NMR (471 MHz, [D4]MeOD, room temp.): δ = –82.5 (t, JFF
=
4
9.2 Hz, 3 F, CF3), –118.2 (q, JFF = 9.1 Hz, 2 F, CO–CF2), –127.9
(tt, 1JFC = 267, 2JFC = 32 Hz, CF2–CF3), 116.1 (CN), 116.5 (t, 2JFC
(m, 2 F, CF –CF ) ppm. IR (KBr disk): ν = 3307, 3170 (s, N–H),
˜
2
3
= 33 Hz, CF3), 118.8 (t, JFC = 34 Hz, CO–CF2), 178.4 (N–C=C), 2222 (vs, CϵN), 1643 (vs, C=O) cm–1. MS (EI): m/z = 278 [M+],
2
187.6 (CO) ppm. IR (KBr disk): ν = 3283 (vs, N–H), 2983 (m, C– 109 [M+ – C3F7]. C8H5F7N2O (278.13): calcd. C 34.55, H 1.81, N
˜
H), 2213 (vs, CϵN), 1642 (vs, C=O), 1589 (vs, C=C) cm–1. MS
(EI): m/z = 304 [M+], 285 [M+ – F], 135 [M+ – C3F7]. C10H7F7N2O
(304.17): calcd. C 39.49, H 2.32, N 9.21; found C 39.34, H 2.15, N
9.15.
10.07; found C 34.47, H 1.68, N 9.99.
2-[1-Amino-1-phenylmeth-(Z)-ylidene]-4,4,4-trifluoro-3-oxobutyro-
nitrile (25): 1.5 g (10 mmol) (E)-3-Amino-3-phenylacrylonitrile was
dissolved in 20 mL of tetrahydrofuran and 1.0 g (10 mmol) triethyl-
amine was added. This solution was added dropwise to a solution
of 3.1 g (15 mmol) trifluoroacetic acid anhydride in 20 mL of tetra-
hydrofuran. The yellowish solution was heated to reflux for one
hour and was left to attain room temperature overnight. The reac-
tion mixture was poured on 100 g of ice and 1 mL of concentrated
aqueous HCl (37%) was added. After melting of the ice the organic
phase was extracted with dichloromethane (5ϫ50 mL), dried with
MgSO4 and the solvent was removed in vacuo. The product crystal-
lises after a short time in the refrigerator and was recrystallised
from diethyl ether yielding 1.5 g (64%) of 25. 1H NMR (500 MHz,
CDCl3, room temp.): δ = 6.73 [s (br), 1 H, NH], 7.49–7.59 (m, 2
H, o-H), 7.60–7.68 (m, 3 H, m,p-H), 10.74 [s (br), 1 H, NH] ppm.
4,4,5,5,6,6,6-Heptafluoro-3-oxo-2-[piperidin-(2Z)-ylidene]hexane-
nitrile (14): 1.2 g (10 mmol) [piperidine-(2E/2Z)-ylidene]acetonitrile
(10) was dissolved in 100 mL of toluene, 1.0 g (10 mmol) triethyl-
amine was added and the solution was cooled to 0 °C. 2.4 g
(10 mmol) 2,2,3,3,4,4,4-heptafluorobutyryl chloride was dissolved
in 50 mL of toluene and added dropwise to the chilled solution.
The mixture was stirred at 0 °C for one hour and subsequently at
room temperature overnight. After filtration and treatment with
saturated NaHCO3 solution the toluene solution was dried with
MgSO4 and the solvent was removed in vacuo. The yellowish solid
was recrystallised from diethyl ether yielding 1.9 g (60%) of colour-
less needles. 1H NMR (500 MHz, CDCl3, room temp.): δ = 1.91
(m, 4 H, CH2–CH2–CH2–CH2), 2.84 (m, 2 H, CH2–C–N), 3.55 (m, 19F NMR (471 MHz, CDCl3, room temp., ppm): δ = –74.6 (s, 3 F,
2 H, CH2–N–C), 12.16 [s (br), 1 H, NH] ppm. 19F NMR
CF3) ppm. 13C{1H} NMR (126 MHz, CDCl3, room temp.): δ =
4
1
(471 MHz, CDCl3, room temp., ppm): δ = –80.8 (t, JFF = 9.2 Hz,
78.4 (C=C–CN), 116.2 (CN), 116.5 (d, JFC = 290 Hz, CF3), 127.7
3 F, CF3), –117.1 (q, 4JFF = 9.2 Hz, 2 F, CO–CF2), –126.4 (m, 2 F,
(o-C), 129.5 (m-C), 132.0 (i-C), 133.1 (p-C), 174.8 (C=C–CN),
CF2–CF3) ppm. 13C{1H} NMR (126 MHz, CDCl3, room temp., 179.2 (CO) ppm. IR (KBr disk): ν = 3307, 3176 (vs, N–H), 2220
˜
not all C signals were observed): δ = 18.1 (CH2–CH2–C–N), 20.6
(CH2–CH2–N–C), 28.5 (CH2–C–N), 42.9 (CH2–N–C), 80.1 (=C–
(vs, CϵN), 1659 (vs, C=O), 1636 (vs, C=C), 1219, 1175, 1144 (s,
C–F) cm– 1 . MS (EI): m/z = 240 [M+ ], 171 [M+ – CF3 ].
CN), 115.9 (CN), 174.6 (N–C=C) ppm. IR (KBr disk): ν = 3139 C11H7F3N2O (240.18): calcd. C 55.01, H 2.94, N 11.66; found C
˜
(m, N–H), 2981 (m, C–H), 2206 (vs, CϵN), 1633 (vs, C=O), 1605 54.88, H 2.90, N 11.54
(vs, C=C) cm–1. MS (EI): m/z = 318 [M+], 299 [M+ – F], 149 [M+
C3F7]. C11H9F7N2O (318.19): calcd. C 41.52, H 2.85, N 8.80; found
C 41.47, H 2.71, N 8.73.
–
2-[1-Amino-1-(4-fluorophenyl)meth-(Z)-ylidene]-4,4,5,5,6,6,6-hepta-
fluoro-3-oxohexanenitrile (27): 1.6 g (10 mmol) (E/Z)-3-Amino-3-
(4-fluorophenyl)acrylonitrile (22) was dissolved in 80 mL of tetra-
hydrofuran and 1.5 g (15 mmol) triethylamine was added. 3.4 g
(15 mmol) 2,2,3,3,4,4,4-heptafluorobutyryl chloride was added
dropwise via a syringe and the mixture was stirred for three days.
Another portion of 1.5 g (6.0 mmol) 2,2,3,3,4,4,4-heptafluorobu-
tyryl chloride and 0.6 g (6.0 mmol) triethylamine was added drop-
[2-Azepan-(2Z)-ylidene]-4,4,5,5,6,6,6-heptafluoro-3-oxohexanenitrile
(15): The synthesis was carried out as for 14, except that 1.4 g
(10 mmol) [azepan-(2E/2Z)-ylidene]acetonitrile (11) was used.
Yield 2.3 g (70%) of colourless needles after recrystallisation from
1
diethyl ether. H NMR (500 MHz, CDCl3, room temp.): δ = 1.75
(m, 4 H, CH2–CH2–CH2–C–N), 1.89 (m, 2 H, CH2–CH2–N–C), wise and the mixture stirred overnight. After washing with satu-
2.94 (m, 2 H, CH2–C–N), 3.62 (m, 2 H, CH2–N–C), 12.09 [s (br), rated sodium hydrogen carbonate solution and drying over MgSO4
1 H, NH] ppm. 19F NMR (471 MHz, CDCl3, room temp., ppm): the organic solvents were removed in vacuo yielding 2.2 g (63%) of
4
4
1
δ = –80.8 (t, JFF = 9.2 Hz, 3 F, CF3), –116.6 (q, JFF = 9.2 Hz, 2
F, CO–CF2), –126.3 (m, 2 F, CF2–CF3) ppm. 13C{1H} NMR H, NH], 7.22 (m, 2 H, m-H), 7.62 (m, 2 H, o-H), 10.89 [s (br), 1
(126 MHz, CDCl3, room temp., not all C signals were observed): δ
H, NH] ppm. 13C{1H} NMR (126 MHz, CDCl3, room temp.): δ =
= 23.5 (CH2–CH2–C–N), 27.2 (CH2–CH2–CH2–C–N), 30.2 (CH2– 80.1 (C=C–CN), 109.9 (tt, JFC = 268, JFC = 32 Hz, CF2–CF3),
27. H NMR (200 MHz, CDCl3, room temp.): δ = 6.96 [s (br), 1
1
2
2
2
C–N), 32.6 (CH2–CH2–N–C), 46.2 (CH2–N–C), 80.1 (=C–CN),
116.7 (CN), 180.5 (N–C=C) ppm. IR (KBr disk): ν = 3137 (m, N–
H), 2947 (m, C–H), 2209 (vs, CϵN), 1631 (vs, C=O), 1603 (vs, 165.4 (d, JFC = 256 Hz, p-C), 174.1 (C–NH2), 180.4 (t, JFC
C=C) cm–1. MS (EI): m/z = 332 [M+], 313 [M+ – F], 163 [M+
C3F7]. C12H11F7N2O (332.22): calcd. C 43.38, H 3.34, N 8.43; –80.7 (t, JFF = 9.2 Hz, 3 F, CF3), –105.0 (tt, JHF = 8, JHF
116.1 (CN), 116.8 (d, JFC = 22 Hz, m-C), 118.8 (t, JFC = 33 Hz,
CF3), 129.1 (d, JFC = 3.4 Hz, i-C), 130.5 (d, JFC = 9.2 Hz, o-C),
4
3
˜
1
2
=
–
25 Hz, CO) ppm. 19F NMR (471 MHz, CDCl3, room temp.): δ =
4
3
4
=
4
found C 43.38, H 3.44, N 8.26.
5 Hz, 1 F, p-CF), –116.5 (q, JFF = 9.3 Hz, 2 F, CO–CF2), –126.2
(s, 2 F, CF –CF ) ppm. IR (KBr disk): ν = 3304, 3161 (s, N–H),
2221 (vs, CϵN), 1635 (vs, C=O), 1605 (m, C=C), 1189 (vs, C–F)
cm–1. MS (FAB): m/z = 359 [M+]. C13H6F8N2O (358.19): calcd. C
43.59, H 1.69, N 7.82; found C 43.34, H 1.65, N 7.66.
˜
2
3
2-[1-Aminoeth-(Z)-ylidene]-4,4,5,5,6,6,6-heptafluoro-3-oxohexane-
nitrile (24): 0.86 g (10 mmol) (E/Z)-3-aminobut-2-enenitrile was
dissolved in 100 mL of tetrahydrofuran and 1.1 g (10 mmol) trieth-
ylamine was added. The mixture was cooled to 0 °C and a solution
of 2.4 g (10 mmol) 2,2,3,3,4,4,4-heptafluorobutyryl chloride in 2-[1-Amino-1-phenylmeth-(Z)-ylidene]-4,4,5,5,6,6,6-heptafluoro-3-
50 mL of tetrahydrofuran was added dropwise while stirring over oxohexanenitrile (28): The synthesis was carried out as for 27, ex-
a period of 3 h. The yellowish mixture was allowed to thaw over-
night and filtered. The solvent was removed in vacuo and the crude
product was recrtystallised from CH2Cl2 yielding 1.4 g (50%) of
cept that 1.4 g (10 mmol) (E)-3-amino-3-phenylacrylonitrile was
used. Yield 56%. 1H NMR (200 MHz, CDCl3, room temp.): δ =
6.96 [s (br), 1 H, NH], 7.53 (m, 2 H, o-H), 7.60 (m, 3 H, m,p-H),
4144
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Eur. J. Org. Chem. 2008, 4139–4147

Modular Routes Towards New N,O-Bidentate Ligands
10.89 [s (br), 1 H, NH] ppm. 13C{1H} NMR (126 MHz, CDCl3, C), 174.2 (C=C–CN), 179.3 (CO) ppm. 19F NMR (471 MHz,
2
room temp.): δ = 80.1 (C=C–CN), 109.9 (t, JFC = 32 Hz, CF2–
CDCl3, room temp.): δ = –80.7 (t, 4JFF = 9.2 Hz, 3 F, CF3), –116.8
(q, JFF = 9.3 Hz, 2 F, CO–CF2), –126.2 (m, 2 F, CF2–CF3) ppm.
2
2
4
CF3), 116.2 (CN), 116.5 (t, JFC = 34 Hz, CF3), 118.8 (t, JFC
=
33 Hz, CO–CF2), 127.8 (o-C), 129.4 (m-C), 133.0 (p-C), 133.1 (i- IR (KBr disk): ν = 3157 (m, N–H), 3068, 3043 (m, C–Harom.), 2966,
˜
2
C), 175.2 (C-NH2), 180.4 (t, JFC = 25 Hz, CO) ppm. 19F NMR 2931 (w, C–Hali), 2219 (vs, CϵN), 1627 (vs, C=O), 1558 (vs, C=C),
4
(471 MHz, CDCl3, room temp.): δ = –80.7 (t, JFF = 9 Hz, 3 F,
CF3), –116.5 (q, JFF = 9 Hz, 2 F, CO–CF2), –126.1 (s, 2 F, CF2–
1242 (s, C–F) cm–1. MS (EI): m/z = 368 [M+], 199 [M+ – C3F7].
C15H11F7N2O (368.25): calcd. C 48.92, H 3.01, N 7.61; found C
4
CF ) ppm. IR (KBr disk): ν = 3313, 3184 (s, N–H), 2214 (vs, 48.86, H 3.28, N 7.46.
˜
3
CϵN), 1657 (vs, C=O), 1632 (s, C=C), 1208 (vs, C–F) cm–1. MS
(FAB): m/z = 340 [M+], 171 [M+ – C3F7], 143 [M+ – COC3F7], 77
[Ph+]. C13H7F7N2O (340.20): calcd. C 45.90, H 2.07, N 8.23; found
C 45.92, H 2.17, N 8.20.
4,4,5,5,6,6,6-Heptafluoro-3-oxo-2-[1-phenyl-1-p-tolylaminometh-
(Z)-ylidene]hexanenitrile (38): 2.4 g (10 mmol) (E)-3-phenyl-3-(p-
tolylamino)acrylonitrile (34) was dissolved in 100 mL of tetra-
hydrofuran and 1.0 g (10 mmol) triethylamine was added. 2.3 mL
(15 mmol) 2,2,3,3,4,4,4-heptafluorobutyryl chloride were added
dropwise with a syringe while stirring. The mixture turns yellowish
and a white precipitate forms. After a week of stirring at room
temperature the solution was filtered and the solvent was removed
in vacuo. The residue was dissolved in toluene and extracted three
times with saturated sodium hydrogen carbonate solution. After
drying over Na2SO4 the solvent was removed in vacuo and the
remainig solid recrystallised from diethyl ether. Yield 1.7 g (40%).
1H NMR (500 MHz, CDCl3, room temp.): δ = 2.26 (s, 3 H, CH3),
2-[1-Amino-1-phenylmeth-(Z)-ylidene]-4,4,5,5,6,6,7,7,8,8,9,9,
10,10,10-pentadecafluoro-3-oxodecanenitrile (29): 1.4 g (10 mmol)
(E)-3-amino-3-phenylacrylonitrile was dissolved in 100 mL
of diethyl ether and 1.0 g (10 mmol) triethylamine was added.
The mixture was cooled to –20 °C and 4.3 g (10 mmol)
2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctanoyl chloride was
added dropwise while stirring. The solution was allowed to thaw
and stir overnight and was washed three times with saturated so-
dium hydrogen carbonate solution. After drying over Na2SO4 the
solvent was removed in vacuo and the remaining solid was recrys-
tallised from diethyl ether/pentane to yield 0.9 g (18%) of 29. 1H
NMR (200 MHz, CDCl3, room temp.): δ = 6.58 (s, 1 H, NH), 7.54
(m, 5 H, Ph), 10.98 [s (br), 1 H, NH] ppm. 19F NMR (471 MHz,
CDCl3, room temp.): δ = –80.9 (t, 4JFF = 10.1 Hz, 3 F, CF3), –115.9
(m, 2 F), –121.3 (m, 2 F), –121.9 (m, 2 F), –122.1 (m, 2 F), –122.6
3
3
6.72 (d, JHH = 8.5 Hz, 2 H, o-Htol), 7.00 (d, JHH = 8.0 Hz, 2 H,
m-Htol), 7.35 (d, 3JHH = 7.5 Hz, 2 H, o-HPh), 7.42 (t, 3JHH = 7.5 Hz,
3
2 H, m-HPh), 7.49 (t, JHH = 7.5 Hz, 1 H, p-HPh), 13.38 [s (br), 1
H, NH] ppm. 13C{1H} NMR (126 MHz, CDCl3, room temp.): δ =
21.1 (CH3), 82.8 (C=C–CN), 115.7 (CN), 124.4 (o-Ctol), 128.8 (o-
C
Ph), 129.2 (m-CPh), 130.1 (m-Ctol), 130.2 (p-Ctol), 131.8 (p-CPh),
(m, 2 F), –126.0 (m, 2 F) ppm. IR (KBr disk): ν = 3358 (s, N–H),
˜
133.7 (i-CPh), 138.1 (i-Ctol), 172.4 (C=C–CN) ppm. 19F NMR
2218 (vs, CϵN), 1698 (vs, C=O) cm–1. MS (EI): m/z = 540 [M+],
171 [M+ – C7F15]. C17H7F15N2O (540.23): calcd. C 37.80, H 1.31,
N 5.19; found C 37.92, H 1.64, N 5.20.
4
(471 MHz, CDCl3, room temp.): δ = –80.6 (t, JFF = 9.2 Hz, 3 F,
CF3), –116.3 (q, 4JFF = 9.1 Hz, 2 F, CO–CF3), –126.0 (m, 2 F, CF2–
CF ) ppm. IR (KBr disk): ν = 2963 (m, C–Hali), 2216 (s, CϵN),
˜
3
1627 (vs, C=O), 1214 (s, C–F) cm–1. MS (EI): m/z = 430 [M+], 261
[M+ – C3F7]. C20H13F7N2O (430.32): calcd. C 55.82, H 3.05, N
6.51; found C 55.95, H 3.22, N 6.58.
4,4,5,5,6,6,6-Heptafluoro-3-oxo-2-[1-phenylaminoeth-(Z)-ylidene]-
hexanenitrile (36): 1.9 g (12 mmol) (E/Z)-3-(phenylamino)but-2-en-
enitrile (32) was dissolved in 100 mL of tetrahydrofuran and 1.2 g
(12 mmol) triethylamine was added. A solution of 2.8 g (12 mmol)
2,2,3,3,4,4,4-heptafluorobutyryl chloride (25) in tetrahydrofuran
was added dropwise. The yellowish solution is stirred overnight.
After filtration the solvent was removed in vacuo, the residue dis-
solved in toluene and extracted three times with saturated sodium
hydrogen carbonate solution. After drying over MgSO4 the solvent
was removed in vacuo and the remainig solid recrystallised from
diethyl ether. Yield 2.1 g (49%). 1H NMR (500 MHz, CDCl3, room
temp.): δ = 2.42 (s, 3 H, CH3), 7.19 (m, 2 H, o-H), 7.45 (m, 3 H,
m,p-H), 13.33 [s (br), 1 H, NH] ppm. 13C{1H} NMR (126 MHz,
CDCl3, room temp., not all C signals were observed): δ = 19.8
(CH3), 82.3 (C=C–CN), 116.0 (CN), 125.6 (o-C), 129.4 (p-C), 130.2
(m-C), 135.5 (i-C), 174.2 (C=C–CN), 179.5 (CO) ppm. 19F NMR
(Z)-2-Amino-5,5,6,6,7,7,7-heptafluorohept-2-en-4-one (39): 2.1 g
(20 mmol) 2,2-dimethoxypropane was dissolved in 5 mL of chloro-
form and 3.2 g (40 mmol) pyridine was added. The mixture
was cooled in an ice bath and a solution of 16.4 g (40 mmol)
2,2,3,3,4,4,4-heptafluorobutyric anhydride in 5 mL of chloroform
was added dropwise. After stirring overnight 40 mL of water was
added and stirring was continued for further 4 h. The mixture was
extracted with 50 mL of dichloromethane and the extract washed
with 20 mL of aqueous, diluted hydrochloric acid, 30 mL of 10%
sodium carbonate solution and water (2 ϫ30 mL). After drying
over Na2SO4 the solvent was removed in vacuo and the dark red
oil was dissolved in 40 mL of acetonitrile. 4 mL (55 mmol) concen-
trated aqueous ammonia solution (25%) was added dropwise with
stirring which was continued for further 48 h. The solvent was then
removed in vacuo and 50 mL of dichloromethane was added. The
solution was washed with water (2 ϫ 30 mL) and dried with
Na2SO4. The solvent was removed and the residue was recrystal-
lised from pentane yielding 2.0 g (40%) of 39. 1H NMR (200 MHz,
CDCl3, room temp.): δ = 2.11 (s, 3 H, CH3), 5.43 (s, 1 H, CH),
5.93 [s (br), 1 H, NH], 10.11 [s (br), 1 H, NH] ppm. 13C{1H} NMR
(126 MHz, CDCl3, room temp., not all C signals were observed): δ
4
(471 MHz, CDCl3, room temp.): δ = –80.7 (t, JFF = 9.2 Hz, 3 F,
CF3), –116.8 (q, 4JFF = 9.1 Hz, 2 F, CO–CF2), –126.2 (m, 2 F, CF2–
CF ) ppm. IR (KBr disk): ν = 3046 (mw, C–H ), 2217 (s, CϵN),
˜
3
ar
1625 (vs, C=O), 1574 (vs, C=C) cm–1. MS (EI): m/z = 354 [M+],
185 [M+ – C3F7]. C14H9F7N2O (354.23): calcd. C 47.47, H 2.56, N
7.91; found C 47.48, H 2.85, N 8.01.
4,4,5,5,6,6,6-Heptafluoro-3-oxo-2-[1-p-tolylaminoeth-(Z)-ylidene]-
hexanenitrile (37): The synthesis was carried out as for 36 except
that 2.1 g (12 mmol) (E/Z)-3-(p-tolylamino)but-2-enenitrile (34) = 23.1 (CH3), 90.9 (CH), 168.5 (C=CH), 178.4 (CO) ppm. 19F
was used. Yield 1.6 g (29%). 1H NMR (200 MHz, CDCl3, room
temp.): δ = 2.39 (s, 3 H, C=C–CH3), 2.41 (s, 3 H, p-CH3), 7.09 (m,
2 H, o-H) 7.27 (m, 2 H, m-H), 13.25 [s (br), 1 H, NH] ppm.
NMR (471 MHz, CDCl3, room temp.): δ = –81.1 (t, 4JFF = 8.9 Hz,
4
3 F, CF3), –121.7 (q, JFF = 8.9 Hz, 2 F, CO–CF2), –127.5 (m, 2 F,
CF –CF ) ppm. IR (KBr disk): ν = 3301, 3168 (vs, br, N–H), 1612
˜
2
3
13C{1H} NMR (126 MHz, CDCl3, room temp., not all C signals (vs, C=O), 1546 (vs, C=C) cm–1. MS (EI): m/z = 253 [M+], 84 [M+ –
were observed): δ = 19.7 (C=C–CH3), 21.3 (p-CH3), 82.1 (C=C–
C3F7]. C7H6F7NO (253.12): calcd. C 33.22, H 2.39, N 5.53; found
CN), 116.1 (CN), 125.3 (o-C), 130.7 (m-C), 132.9 (p-C), 139.6 (i- C 33.48, H 2.50, N 5.30.
Eur. J. Org. Chem. 2008, 4139–4147
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4145

U. Beckmann, E. Eichberger, M. Lindner, M. Bongartz, P. C. Kunz
(Z)-1-Amino-4,4,5,5,6,6,6-heptafluoro-1-phenylhex-1-en-3-one (40): 100 mL of tetrahydrofuran and 1.0 g (10 mmol) triethylamine was
FULL PAPER
The synthesis was carried out as for 39, except that 3.3 g (20 mmol)
added. 2.3 g (10 mmol) 2,2,3,3,4,4,4-heptafluorobutyryl chloride
was added dropwise with stirring, and stirring was continued over-
1
(1,1-dimethoxyethyl)benzene[43] was used. Yield 4.9 g (78%). H
NMR (500 MHz, CDCl3, room temp.): δ = 5.84 (s, 1 H, CH), 6.11 night. The solvent was then removed and the solid washed with
3
[s (br), 1 H, NH], 7.51 (t, JHH = 7.8 Hz, 2 H, m-HPh), 7.57 (t,
water until no Cl– was detected. The residue was dried and dis-
solved in a minium of acetone. Upon addition of methanol, a white
3JHH = 7.5 Hz, 1 H, p-HPh), 7.61 (d, JHH = 8.0 Hz, 2 H, o-HPh),
3
10.31 [s (br), 1 H, NH] ppm. 13C{1H} NMR (126 MHz, CDCl3, solid precipitated which was collected by filtration and dried. Yield
room temp., not all C signals were observed): δ = 89.8 (C=CH),
1.4 g (51%). 1H NMR (200 MHz, [D6]acetone, room temp.): δ =
126.5 (o-C), 129.5 (m-C), 132.2 (p-C), 135.5 (i-C), 167.3 (C=CH), 2.58 (s, 6 H, CH3), 4.25 (s, 4 H, CH2), 11.92 [s (br), 2 H, NH] ppm.
179.2 (CO) ppm. 19F NMR (471 MHz, CDCl3, room temp.): δ = 13C{1H} NMR (126 MHz, [D6]acetone, room temp., CFx and CO
4
4
–81.0 (t, JFF = 8.9 Hz, 3 F, CF3), –121.5 (q, JFF = 8.9 Hz, 2 F, not observed): δ = 19.1 (CH3), 45.3 (CH2), 82.1 (C=C–CN), 117.2
CO–CF ), –127.3 (m, 2 F, CF –CF ) ppm. IR (KBr disk): ν = 3296, (CN), 177.3 (C=C–CN) ppm. 19F NMR (471 MHz, [D6]acetone,
˜
2
2
3
3155 (s, N–H), 1608 (vs, C=O), 1577 (vs, C=C) cm–1. MS (EI): m/z
= 315 [M+], 146 [M+ – C3F7]. C12H8F7NO (315.19): calcd. C 45.73,
H 2.56, N 4.44; found C 45.64, H 2.55, N 4.34.
room temp.): δ = –80.4 (t, JFF = 9.4 Hz, 3 F, CF3), –115.8 (m, 2
4
F, CO–CF ), –125.9 (m, 2 F, CF –CF ) ppm. IR (KBr disk): ν =
˜
2
2
3
3094 (w, C–H), 2214 (vs, CϵN), 1630 (vs, C=O), 1587 (vs, C=C),
1228 (vs, C–F) cm–1. MS (EI): m/z = 582 [M+], 413 [M+ – C3F7],
285 [M+ – C7H7N2O], 135 [C7H7N2O]. C18H12F14N4O2 (582.30):
calcd. C 37.13, H 2.08, N 9.62; found C 37.02, H 2.24, N 9.38.
(Z)-1-Amino-4,4,5,5,6,6,6-heptafluorohex-1-en-3-one (41): 2.7 g
(10 mmol) (E)-1-ethoxy-4,4,5,5,6,6,6-heptafluorohex-1-en-3-one[36]
was dissolved in 10 mL of water and 1.0 mL (13 mmol) concen-
trated aqueous ammonia solution (25%) was added. Stirring was
continued overnight and the mixture was extracted three times with
30 mL of diethyl ether. The collected organic phases were dried
with MgSO4 and the solvents were evaporated to yield 1.5 g (63%)
of 41 as an oil. H NMR (200 MHz, C6D6, room temp.): δ = 4.22
[s (br), 1 H, NH], 5.14 [d, JHH = 7.2 Hz (cis), 1 H, CH–CO], 5.82
[ddd, JHH = 7.2 Hz (CH, cis), JHH = 7.8 Hz (NH, cis), JHH
2-[1-{4-{(Z)-2-Cyano-4,4,5,5,6,6,6-heptafluoro-1-methyl-3-oxohex-
1-enylamino}phenylamino}eth-(Z)-ylidene]-4,4,5,5,6,6,6-heptafluoro-
3-oxohexanenitrile (53): 1.2 g (5.0 mmol) 3-[4-(2-Cyano-1-methyl-
vinylamino)phenylamino]but-2-enenitrile 52 and 1.0 g (10 mmol)
triethylamine was dissolved in 300 mL of tetrahydrofuran. 2.7 g
(11 mmol) 2,2,3,3,4,4,4-heptafluorobutyryl chloride was dissolved
in 50 mL of tetrahydrofuran and was added dropwise with stirring
during 1 h. Stirring was continued overnight and the precipitate
was filtered. The solvent was removed under vacuo and the residue
was recrystallised from diethyl ether yielding 2.2 g (70%) of a beige
1
3
3
3
3
=
14.8 Hz (NH, trans), 1 H, CH–NH2]. 8.90 [s (br), 1 H, NH] ppm.
13C{1H} NMR (126 MHz, C6D6, room temp.): δ = 89.8 (CH–CO),
1
2
2
109.8 (tt, JFC = 265, JFC = 31 Hz, CF2–CF3), 117.4 (t, JFC
=
1
2
powder. H NMR (500 MHz, CDCl3, room temp.): δ = 2.47 (s, 6
34 Hz, CF3), 119.7 (t, JFC = 34 Hz, CO–CF2), 155.2 (CH–NH2),
H, CH3), 7.39 (s, 4 H, arom.), 13.38 (s, 2 H, NH) ppm. 13C{1H}
2
180.2 (t, JFC = 24 Hz, CO) ppm. 19F NMR (471 MHz, C6D6,
room temp.): δ = –81.1 (t, 4JFF = 8.9 Hz, 3 F, CF3), –121.3 (q, 4JFF
= 8.6 Hz, 2 F, CO–CF2), –127.3 (s, 2 F, CF2–CF3) ppm. IR (KBr
NMR (126 MHz, CDCl3, room temp.): δ = 19.9 (CH3), 83.3 (C=C–
1
2
CN), 109.9 (tt, JFC = 269, JFC = 31 Hz, CF2–CF3), 115.3 (CN),
2
2
116.6 (t, JFC = 34 Hz, CF3), 118.9 (t, JFC = 34 Hz, CO–CF2),
disk): ν = 3374, 3222 (m, N–H), 1653 (s, C=O), 1522 (s, C=C),
˜
2
1229 (vs, C–F) cm–1. MS (EI): m/z = 239 [M+], 70 [M+ – C3F7].
C6H4F7NO (239.09): calcd. C 30.14, H 1.69, N 5.86; found C 30.31,
H 1.55, N 5.39.
127.4 (o,m-C), 136.1 (i-C), 174.1 (C=C–CN), 180.1 (t, JFC
=
25 Hz, CO) ppm. 19F NMR (471 MHz, CDCl3, room temp.): δ =
4
4
–80.7 (t, JFF = 9 Hz, 3 F, CF3), –116.8 (q, JFF = 9 Hz, 2 F, CO–
CF ), –126.1 (s, 2 F, CF –CF ) ppm. IR (KBr disk): ν = 3426 (w,
˜
2
2
3
4,4,5,5,6,6-Hexafluoro-3,7-dioxo-2,8-bis[pyrrolidin-(2Z)-ylidene]-
nonanedinitrile (48): 1.1 g (10 mmol) [pyrrolidin-(2E/2Z)-ylidene]-
acetonitrile (9) was dissolved in 100 mL of toluene and 1.0 g
(10 mmol) triethylamine was added. The mixture was cooled to
0 °C. 1.4 g (5 mmol) 2,2,3,3,4,4-hexafluoropentanedioyl dichloride
was added dropwise and stirring was continued overnight. The
white precipitate was filtered and dried. Water (50 mL) was added,
the mixture was stirred for 1 h, filtered and washed with water until
the filtrate contais no Cl–. The white solid was dried. Yield 1.3 g
(62%). 1H NMR (200 MHz, [D6]acetone, room temp.): δ = 2.23
N–H), 2979 (m, CH), 2216 (vs, CϵN), 1631 (vs, C=O), 1570 (s,
C=C), 1236 (vs, C–F) cm–1. MS (EI): m/z = 630 [M+], 461 [M+
–
C3F7], 394 [M+ – C(CN)COC3F7], 263 [M+ – CH3CC(CN)-
COC3F7], 200 [C3F7CO]. C22H12F14N4O2 (630.34): calcd. C 41.92,
H 1.92, N 8.89; found C 41.86, H 2.22, N 8.74.
Supporting Information (see also the footnote on the first page of
this article): Preparation details and full characterisation of com-
pounds 1–3, 7–12, 16–23, 26, 30–35, 42–47, 49, 51 and 52;
refs.[44,46–48] refer to material in the Supporting Information.
3
3
(qi, JHH = 7.7 Hz, 4 H, CH2–CH2–CH2), 3.12 (t, JHH = 8.0 Hz,
3
4 H, CH2–C–N), 3.99 (t, JHH = 7.5 Hz, 4 H, CH2–N–C), 10.80 [s
Acknowledgments
(br), 2 H, NH] ppm. 13C{1H} NMR (126 MHz, [D6]acetone, room
temp., not all C signals were observed): δ = 20.4 (CH2–C–N), 35.9
(CH2–CH2–CH2), 52.3 (CH2–N–C), 76.6 (=C–CN), 117.1 (CN),
178.9 (C=C–CN) ppm. 19F NMR (471 MHz, [D6]acetone, room
temp.): δ = –115.2 (m, 4 F, CO–CF2), –121.5 (m, 2 F, CF2–CF2–
We thank Mareike Meyer, Nadine Brückmann and Holger Willms
for their valuable help in the preparation of various compounds
and Dr. Tamara Chenskaya for helpful discussions.
CF ) ppm. IR (KBr disk): ν = 3258 (vs, N–H), 2211 (vs, CϵN),
˜
2
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Published Online: July 4, 2008
Eur. J. Org. Chem. 2008, 4139–4147
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4147