Synthesis and reactivity of ortho-palladated 3-phenylpropanamides. Insertion of CO, XyNC, and alkynes into the Pd-C bond. Synthesis of seven-and nine-membered palladacycles and benzazepine-and benzazonine-based heterocycles

Article abstract of DOI:10.1021/om4000192

Aryl palladium complexes [Pd{C₆H₄(CH ₂)₂C(O)NRR′)-2}I(tmeda)] [NRR′ = NH ₂ (1a), NHMe (1b), NMe₂ (1c); tmeda = N,N,N′, N′-tetramethylethylenediamine] are prepared by oxidative addition of t

Full text of DOI:10.1021/om4000192

Article
pubs.acs.org/Organometallics
Synthesis and Reactivity of Ortho-Palladated 3‑Phenylpropanamides.
Insertion of CO, XyNC, and Alkynes into the Pd−C Bond. Synthesis of
Seven- and Nine-Membered Palladacycles and Benzazepine- and
Benzazonine-Based Heterocycles
Roberto Frutos-Pedreno, Pablo Gonzalez-Herrero,* and Jose Vicente*
́
́
̃
Grupo de Química Organometal
30071 Murcia, Spain
́
ica, Departamento de Química Inorgan
́
ica, Facultad de Química, Universidad de Murcia, Apdo. 4021,
Peter G. Jones
Institut fur Anorganische und Analytische Chemie, Technische Universitat Braunschweig, Postfach 3329, 38023 Braunschweig,
̈
̈
Germany
S
* Supporting Information
ABSTRACT: Aryl palladium complexes [Pd{C6H4(CH2)2C(O)-
NRR′)-2}I(tmeda)] [NRR′ = NH2 (1a), NHMe (1b), NMe2
(1c); tmeda = N,N,N′,N′-tetramethylethylenediamine] are
prepared by oxidative addition of the corresponding 3-(2-
iodophenyl)propanamides to “Pd(dba)2” ([Pd2(dba)3]·dba; dba
= dibenzylideneacetone) in the presence of tmeda. The cationic
seven-membered palladacycles [Pd{κ2C,O-C6H4(CH2)2C(O)-
NRR′)-2}(tmeda)]TfO (2a−c) are obtained by reacting 1a−c
with AgTfO. Neutral amidate complexes of the type [Pd{κ2C,N-
C6H4(CH2)2C(O)NR)-2}(tmeda)] [R = H (3a), Me (3b)] are obtained upon deprotonation of the amide function in 1a or 1b
with KOtBu. The reaction of 1a with CO at room temperature affords the stable acyl derivative [Pd{C(O)C6H4(CH2)2C-
(O)NH2-2}I(tmeda)] (4), while 2a gives Pd, (tmedaH)TfO, and 4,5-dihydro-2H-benzo[c]azepine-1,3-dione (5a). Compound
5a can also be obtained in high yield by treating the amidate complex 3a with CO, while a low yield of 2-methyl-4,5-dihydro-2H-
benzo[c]azepine-1,3-dione (5b) was obtained from 3b under the same conditions. Complexes 1a−c react with 3 equiv of XyNC
to give trans-[Pd{C(NXy)C6H4(CH2)2C(O)NRR′-2}I(CNXy)2] [NRR′ = NH2 (6a), NHMe (6b), NMe2 (6c)]. By refluxing
a CHCl3 solution of 6a or 1a and XyNC in 1:1 molar ratio, mixtures of 1-(2,6-dimethylphenylimino)-1,2,4,5-
tetrahydrobenzo[c]azepin-3-one (7a) and 2-(2-cyanoethyl)-N-(2,6-dimethylphenyl)benzamide (8a) are obtained. Complexes
2a−c react with alkynes in 1:1 molar ratio to give nine-membered palladacycles of the type [Pd{κ2C,O-C(X)
n
C(X)C6H4(CH2)2C(O)NRR′-2}(tmeda)]TfO [NRR′ = NH2, X = Ph (9a), C6H4 Bu-4 (10a), C6H4Br-4 (11a), CO2Me
(12a); NRR′ = NHMe, X = Ph (9b); NRR′ = NMe2, X = Ph (9c)]. The reaction of 2a with an excess of 3-hexyne gives the
complex [Pd{η3-C6H4(C4Et4)(CH2)2C(O)NH2}(tmeda)]TfO (13), containing a spirocyclic ligand coordinated to Pd through a
η3-allylic bond. The derivatives 9a, 10a and 11a react with CO at 50 °C in CHCl3 to give colloidal Pd, (tmedaH)TfO, and the
corresponding 6,7-disubstituted 1,2-dihydro-4H-benzo[e]azonine-3,5-diones (14, 15, 16), which result from a CO insertion/C−
N reductive coupling sequence.
the organic ring generally has one fewer member. Palladacycles
larger than six members are relatively uncommon and have
been considered difficult to prepare because they tend to be
unstable.1,9 However, methods for the enlargement of pallada-
cycles are of utility, even when the product can not be isolated,
because in many cases the desired organic ring is among the
products of decomposition (see below).
INTRODUCTION
■
Palladacycles are key intermediates in palladium-mediated
cyclization reactions,1−3 which have become one of the most
valuable tools for the synthesis of carbo- and heterocycles.4,5
The use of these reactions for the synthesis of medium-size
rings (seven- to eleven-membered) through C−C or C−
heteroatom coupling is of particular importance, because they
form the basic structural motif in many compounds of
biological or pharmacological significance6 and are difficult to
prepare by other methods.7 However, the ring size of the
majority of the isolated palladacycles described to date (five- or
six-membered)3,8 is not appropriate for this purpose because
Insertion reactions into the Pd−C bond are the best known
method to enlarge the ring size of palladacycles. Thus, alkyne
Received: January 10, 2013
Published: February 20, 2013
© 2013 American Chemical Society
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monoinsertion reactions lead to a two-atom enlargement and
have allowed the synthesis of seven-10−17 or, less frequently,
eight-membered12,13,15,18−22 palladacycles. Alkyne di-insertions
may lead to the expansion of the cyclopalladated ligand through
the incorporation of a butadienyl fragment, giving
nine-10,15,17,23,24 or ten-membered15 palladacycles that are
generally stabilized by the π-coordination of one internal
double bond. Similarly, palladacycle enlargements from six to
eight members have been achieved by insertion of olefins into
the Pd−C bond,25,26 while insertion of CO or isocyanides has
allowed conversions from six to seven members.27,28 In
addition, sequential insertion of one or two molecules of
alkyne and CO or isocyanides have allowed conversions from
six to nine22 or five to ten24 members. Some of these enlarged
palladacycles undergo depalladation reactions under certain
conditions25,27 or are not isolable and decompose sponta-
neously22,26,27,29 to give heterocyclic compounds.
Scheme 1
We have previously shown that ortho-palladated phenyl-
acetamides of the type [Pd{C6H4CH2C(O)NRR′-2}I(tmeda)]
and their cyclopalladated derivatives [Pd{κ2C,O-C6H4CH2C-
(O)NRR′-2}(tmeda)]TfO (NRR′ = NH2, NHMe, NMe2)
undergo C−N and/or C−O reductive couplings after the
insertion of CO or XyNC into the Pd−C bond, leading to
isoquinoline and/or isocoumarin derivatives under relatively
mild conditions.30 These reactions involve the deprotonation of
NH2 or NHMe groups (C−N couplings) or the α-CH2 group
(C−O couplings), which is effected by the tmeda ligand. In a
subsequent study, we reported the synthesis of a series of eight-
membered palladacycles of the type [Pd{κ2C,O-C(X)C(X′)-
C6H4CH2C(O)NRR′-2}(tmeda)]TfO (NRR′ = NH2, NHMe),
obtained from alkyne monoinsertion reactions.22 The enlarged
palladacycles also reacted with CO to give 3-benzazocine-
2,4(1H,3H)-diones, resulting from an analogous CO insertion/
C−N reductive coupling sequence. With the main objective of
exploring the limits of this methodology for the synthesis of
heterocycles of a larger size, the present paper extends our
reactivity studies to ortho-palladated 3-phenylpropanamides,
from which seven-membered palladacycles can be obtained
that, in turn, can be enlarged through the insertion of alkynes
into the Pd−C bond to give nine-membered derivatives. Only a
few examples of isolated nine-membered palladacycles have
been previously reported that are not stabilized by the
coordination of an internal double bond,24,31 and none of
them were obtained from alkyne monoinsertion reactions. A
systematic study of the reactivity of the new complexes toward
CO or XyNC has allowed the synthesis of seven- and nine-
membered heterocycles.
the solvent. Their IR spectra in CH2Cl2 solution show the
ν(CO) band at 1646 (2a), 1608 (2b) or 1591 (2c) cm−1;
these frequencies are appreciably lower than those of the
corresponding free amides (range 1670−1635 cm−1), which
confirms that the amide function is coordinated to the metal
through the oxygen atom. Complexes 2a and 2c could not be
obtained in analytically pure form because reprecipitations from
acetone/Et2O or CH2Cl2/Et2O led to partial decomposition.
However, they can be employed for the synthesis of other
products (see below).
Deprotonation of the amide function in complexes 1a and 1b
with excess KOtBu in CH2Cl2 led in good yield to the neutral
palladacycles [Pd{κ2C,N-C6H4(CH2)2C(O)NR-2}(tmeda)] [R
= H (3a), Me (3b)], which resulted from the displacement of
the iodo ligand by the nitrogen of the anionic amidate group.
Their solid-state IR spectra show the ν(CO) band at 1551
(3a) or 1558 (3b) cm−1, which is typical of N-coordinated
amidato complexes.32,33 The attempts to deprotonate the α-
CH2 in the NMe2 derivative 1c with KOtBu were unsuccessful.
Reactions with CO. Arylpalladium complexes react with
CO, often reversibly, to give acyl derivatives resulting from the
insertion of this molecule into the Pd−C bond.3,20,30,34−37 This
type of reaction has been extensively studied because it
RESULTS AND DISCUSSION
■
Synthesis of Ortho-Palladated 3-Phenylpropana-
mides and Cyclometalated Derivatives. The aryl deriva-
tives [Pd{C6H4(CH2)2C(O)NRR′-2}I(tmeda)] [NRR′ = NH2
(1a), NHMe (1b), NMe2 (1c); Scheme 1] were obtained in
moderate yields by oxidative addition of the corresponding 3-
(2-iodophenyl)propanamides to “Pd(dba)2” ([Pd2(dba)3]·dba;
dba = dibenzylideneacetone) in the presence of tmeda in
CH2Cl2 at room temperature.
The reactions of complexes 1 with 1 equiv of AgTfO in
acetone led to the precipitation of AgI and the formation of the
corresponding cationic palladacycles [Pd{κ2C,O-
C6H4(CH2)2C(O)NRR′-2}(tmeda)]TfO (2a−c). These com-
pounds turned out to be highly hygroscopic amorphous solids
that could not be crystallized and were isolated by evaporating
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constitutes a key step in palladium-catalyzed carbonylations.5,38
In many cases, acyl intermediates may further react with
nucleophiles to give carbonyl-containing organic products.
Treatment of complex 1a with CO in CH2Cl2 at room
temperature afforded the expected insertion product [Pd{C-
(O)C6H4(CH2)2C(O)NH2-2}I(tmeda)] (4) in good yield
(Scheme 1). In contrast to its homologue with ortho-palladated
phenylacetamide,30 complex 4 is remarkably stable, and we did
not observe any decomposition to Pd(0) in solution under CO
at room temperature, which implies that the possible C−N
reductive coupling is much less favored. We then carried out
the reactions of in situ generated solutions of palladacycles 2a−
c in CH2Cl2 with CO (1.4 bar) at room temperature, in the
expectation that their cationic nature and cyclic structure would
facilitate the insertion/reductive coupling sequence. When
starting from the NH2 derivative 2a, colloidal Pd, (tmedaH)-
TfO, and 4,5-dihydro-2H-benzo[c]azepine-1,3-dione39 (5a;
42% isolated yield) were obtained. However, the NHMe and
NMe2 derivatives (2b and 2c, respectively) were recovered
unreacted. With hindsight, it is reasonable to assume that CO
inserts reversibly into the Pd−C bond of 2b and 2c, but a
subsequent C−N or C−O reductive coupling does not occur.
The C−N coupling process may be difficult for 2b because of
the lower acidity of the NH proton and the steric hindrance of
the methyl group, while the anticipated C−O coupling
processes from both 2b and 2c may not be possible because
the α-CH2 protons are not acidic enough, and thus the
necessary deprotonation step does not take place.
The amidate complexes 3a and 3b were also treated with CO
(1.4 bar) in CDCl3 to test the feasibility of the C−N coupling.
Whereas 3a reacted in 3 h at room temperature to give
compound 5a in 88% yield, derivative 3b required heating at 60
°C for 24 h to produce a 30% yield of 2-methyl-4,5-dihydro-
2H-benzo[c]azepine-1,3-dione (5b), which was identified by its
NMR data.40 The reaction mixture also contained several
unidentified species that reverted to complex 3b upon
evaporation of the solvent, which suggests that they are CO
insertion or coordination products. This result confirmed that
the methyl substituent of the amide function is a major obstacle
for the C−N coupling step, consistent with our previous
findings that the C−N couplings of ortho-palladated phenyl-
acetamides are generally much slower for NHMe derivatives
than for their NH2 homologues.30
The reactions of palladacycles 2 and 3 with CO are related to
those of cyclopalladated arylalkylamines, which may afford
esters41 or lactams.27−29,34,42−44 The lack of reactivity of the
NMe2 derivative 2c contrasts with the ability of classical
cyclopalladated N,N-dialkylbenzylamines to give C−N reduc-
tive coupling products after the insertion of CO into the Pd−C
bond by losing one of the alkyl groups.34,42
Reactions with XyNC. Isocyanides insert into the Pd−C
bond of organopalladium complexes to give iminoacyl
derivatives.34,45,46 These reactions have been the subject of
considerable interest because of their involvement in many
stoichiometric14,27,29,43,47 and catalytic48 palladium-mediated
syntheses. The reactions of 1a−c with 3 equiv of XyNC (Xy =
2,6-dimethylphenyl) at room temperature gave the iminoacyl
complexes trans-[Pd{C(NXy)C6H4(CH2)2C(O)NRR′-2}I-
(CNXy)2] [NRR′ = NH2 (6a), NHMe (6b), NMe2 (6c)],
which result from the displacement of the tmeda ligand by two
of the isocyanide molecules and the insertion of a third
isocyanide into the Pd−C bond. Complexes 6a−c were also
obtained when using only 1 equiv of isocyanide at room
temperature, leaving two-thirds of the starting complex
unreacted. The behavior of 1a−c toward XyNC is quite usual
for arylpalladium derivatives20,37,46,49 but differs from that of
the analogous ortho-palladated phenylacetamides [Pd-
{C6H4CH2C(O)NRR′-2}I(tmeda)], which react with 1 equiv
of the isocyanide to give iminoisoquinoline or iminoisocoumar-
in derivatives resulting from an insertion/C−N or C−O
reductive coupling sequence.30 This is a clear indication that
the C−N or C−O couplings are much more difficult for the
phenylpropanamide derivatives, in agreement with the behavior
of acyl complex 4.
We then attempted the 1:1 reaction of 1a with XyNC in
CHCl3 at reflux temperature, which gave a precipitate of Pd
metal, (tmedaH)I, and an approximately 1:0.85 mixture of 1-
[(2,6-dimethylphenyl)imino]-1,2,4,5-tetrahydro-3H-2-benzaze-
pin-3-one (7a) and 2-(2-cyanoethyl)-N-(2,6-dimethylphenyl)-
benzamide (8a). A similar mixture, but with a higher
proportion of 8a (0.45:1), was obtained when complex 6a
was stirred at reflux temperature in CHCl3. Thus, two
competing transformations of iminoacyl intermediates take
place: (i) an intramolecular C−N reductive coupling leading to
compound 7a, and (ii) the hydrolysis of the iminoacyl ligand,
which is accompanied by the dehydration of the unsubstituted
carbamoyl group to give 8a. We have previously shown that a
similar hydrolysis/dehydration sequence takes place when the
eight-membered palladacycle [Pd{κ2C,O-C(Ph)C(Ph)-
C6H4CH2C(O)NH2-2}(tmeda)]TfO reacts with 4 equiv of
XyNC.22 The reactions of complexes 1b or 1c with XyNC in
1:1 molar ratio in CHCl3 at reflux temperature gave mixtures of
products that could not be identified.
Reactions with Alkynes. The reactions of in situ generated
solutions of complexes 2 in CH2Cl2 with various alkynes at
room temperature afforded high yields of the nine-membered
palladacycles [Pd{κ2C,O-C(X)C(X)C6H4(CH2)2C(O)-
NRR′-2}(tmeda)]TfO [NRR′ = NH2, X = Ph (9a),
n
C6H4 Bu-4 (10a), C6H4Br-4 (11a), CO2Me (12a); NRR′ =
NHMe, X = Ph (9b); NRR′ = NMe2, X = Ph (9c)], resulting
from the insertion of one molecule of the alkyne into the Pd−C
bond (Scheme 2). These reactions required the use of strictly 1
equiv of the alkyne and were complete in less than 3 h, except
for the case of 11a, which required 20 h. The use of an excess of
alkyne led to complex mixtures, probably as a result of
polyinsertion reactions. These monoinsertions are thus, in
general, considerably faster than those from the six-membered
palladacycles [Pd{κ2C,O-C6H4CH2C(O)NRR′-2}(tmeda)]-
TfO, previously reported by us,22 which require an excess of
the alkyne and longer reaction times. Presumably, the larger
size of palladacycles 2 facilitates the ring-opening and the
alkyne coordination step. The IR spectra of complexes 9−12
show the ν(CO) band in the range 1651−1592 cm−1,
indicating that the amide function remains coordinated to the
metal through the oxygen atom, which was confirmed by the
crystal structure of 9a (see below).
The reaction of 2a with 3-hexyne gave the complex [Pd{η3-
C6H4(C4Et4)(CH2)2C(O)NH2}(tmeda)]TfO (13), which con-
tains a spirocyclic ligand coordinated to Pd through a η3-allylic
bond (Scheme 2). This type of ligand has been previously
reported to arise from the insertion of two molecules of the
alkyne and a subsequent cyclization of the resulting butadienyl
fragment.18,19,50 Complex 13 was obtained in high yield by
using an excess of 3-hexyne, but it is also formed when only 1
equiv of this alkyne is employed and the reaction is carried out
at low temperatures, and therefore a monoinsertion product
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with a folded conformation (Figure 2). The Pd−N(1) bond
distance of 2.0165(11) Å is similar to that found in the six-
membered cyclic amidate [Pd{κ2C,N-C6H4CH2C(O)NMe-
2}(dbbpy)] [2.012(3), 2.009(3) Å;30 dbbpy = 4,4′-di-tert-
butyl-2,2′-bipyridyl] and is typical of palladium amidate
complexes.55 The C(9)−O(1) bond length of 1.2566(16) Å
is longer than the corresponding distance in the free
propanamide group of 1b [1.223(2) Å], which can be ascribed
to a significant delocalization of the negative charge over the
NCO group. The molecules are linked into loose
inversion-symmetric dimers by weak contacts N−H···Pd and
C−Hmethyl···O.
Scheme 2
The crystal structure of compound 8a is shown in Figure 3.
The asymmetric unit contains two pairs of independent
molecules; each pair participates in an infinite chain parallel
to the a axis, whereby the molecules are linked through N
H···OC hydrogen bonds between the amide groups.
The crystal structure of complex 9a (Figure 4) shows that
the diphenylacetylene molecule has inserted in a syn fashion, as
usual for alkyne monoinsertions, while the amide group
remains coordinated to the Pd through the oxygen. The
conformation of the resulting C,O-palladacycle can be
approximately described as boat-chair. The square-planar
coordination environment around the Pd center is slightly
distorted, mainly because of the small bite of the tmeda ligand
[angle N(2)−Pd−N(3): 85.59(4)°], while the nine-membered
ring does not seem to cause any strain, as deduced from the
C(1)−Pd−O(1) angle of 90.47(4)°. The Pd−C(1) bond
distance of 2.0039(11) Å is typical of vinylpalladium
complexes.13,16−18,20,56 The Pd−O(1) distance of 2.0498(9)
Å is slightly shorter than that found in the eight-membered
palladacycle [Pd{κ2C,O-C(Ph)C(Ph)C6H4CH2C(O)NH2-
2}(tmeda)]TfO [2.0682(11) Å].22 The two H atoms of the
NH2 group are each involved in a hydrogen bond with one
oxygen atom of different triflate anions.
The structure of complex 13 (Figure 5) was solved as a
CH2Cl2 monosolvate. The spirocyclic ligand is coordinated to
palladium via η3-allylic interaction through the atoms C6, C7,
and C8. The coordination environment around the metal is
similar to that found in analogous [Pd(η3-allyl)(tmeda)]+
derivatives.57 The cations are linked by hydrogen bonds N−
H···O across inversion centers; the triflate anion is connected
to the amide moiety and to the CH2Cl2 molecule through one
N−H···O and two short C−H···O hydrogen bonds. The
extended structure consists of inversion-symmetric dimers (see
Supporting Information).
analogous to complexes 9−12 could not be isolated. The
proclivity of 3-hexyne to give polyinsertion products is typical
of electron-rich alkynes, for which it is often impossible to
isolate the monoinsertion product.51
Reactions of Alkyne-Monoinsertion Products with
CO. Synthesis of 1,2-dihydro-4H-benzo[e]azonine-3,5-
diones. Treatment of palladacycles 9a, 10a and 11a with CO
(1.4 bar) at 50 °C in CHCl3 for 15 h gave colloidal Pd,
(tmedaH)TfO, and the corresponding 6,7-disubstituted 1,2-
dihydro-4H-benzo[e]azonine-3,5-diones (14, 15, 16), which
were isolated in moderate to good yields (Scheme 2). These
heterocycles are the expected products from a CO insertion/
C−N reductive coupling sequence. Only a few nine-membered
cyclic imides have been previously reported, which were
synthesized via ring expansion reactions52 or oxidation of nine-
membered lactams.53 Under the same reaction conditions,
complex 12a, containing inserted dimethylacetylenedicarbox-
ylate (DMAD), was recovered unreacted, probably because the
low nucleophilicity of the vinylic carbon bonded to palladium
hampers the CO insertion step.
The crystal structure of compound 14 is shown in Figure 6.
The nine-membered ring exhibits a boat-like conformation.
The ring strain is revealed by the C(3)−N(4)−C(5) angle of
134.31(8)°, which is appreciably wider than the average value
of 125.2° found for acyclic imides in the Cambridge Structural
Database. There are no reported structures of cyclic imides of
this size available for comparison, and the only three eight-
membered examples display similar C−N−C angles.22,58 The
molecules of 14 form inversion-related dimers through
hydrogen bonds N(4)−H(04)···O(3)#1 (see the Supporting
Information).
The reactions of NHMe and NMe2 derivatives (9b and 9c,
respectively) gave mixtures of unidentified compounds. As
previously noted for the seven-membered precursors, the
failure to give C−N or C−O coupling products can be ascribed
to the steric hindrance of the methyl substituent in 9b and/or
the lower acidity of the NH and α-CH2 protons in both cases.
Crystal Structures. The crystal structure of complex 1b is
shown in Figure 1. As usually observed for ortho-substituted
arylpalladium derivatives, the aromatic ring of the aryl ligand is
almost perpendicular to the Pd coordination mean plane, which
can be attributed to the steric demand of the ortho substituent.
The coordination environment and bond distances and angles
around the Pd center are similar to those found in analogous
derivatives.30,33,36,54 Molecules are linked via hydrogen bonds
N−H···I to form zigzag chains parallel to the c axis.
CONCLUSIONS
■
Ortho-palladated 3-phenylpropanamides are suitable precursors
for the synthesis of seven-membered cationic or neutral
palladacycles. The reactions of the former with alkynes have
allowed the isolation of nine-membered palladacycles, which, to
The amidate group of complex 3a is coordinated to the Pd
atom through the nitrogen, forming a seven-membered ring
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Figure 1. Above: Thermal ellipsoid plot (50% probability) of complex 1b. Selected bond distances (Å) and angles (deg): Pd−C(1) 2.015(2), Pd−
N(2) 2.2052(16), Pd−N(3) 2.1240(15), Pd−I 2.5827(2); C(1)−Pd−N(3) 92.23(6), N(3)−Pd−N(2) 83.92(6), C(1)−Pd−I 87.83(5), N(2)−Pd−
I 96.14(4), C(6)−C(1)−Pd 117.17(14), C(2)−C(1)−Pd 123.40(15). Below: Association of molecules of 1b via the c glide plane. Hydrogen bonds
are indicated by dashed lines.
the best of our knowledge, are the first of that size obtained
from alkyne monoinsertions. A series of seven- or nine-
membered cyclic imides and one iminobenzazepinone have
been obtained from CO or XyNC insertion/C−N reductive
coupling sequences.
EXPERIMENTAL SECTION
■
General Considerations, Materials, and Instrumentation.
Unless otherwise noted, all preparations were carried out at room
temperature under atmospheric conditions. Synthesis grade solvents
were obtained from commercial sources. CH2Cl2 was degassed and
dried using a Pure Solv MD-5 solvent purification system from
Innovative Technology, Inc. [Pd2(dba)3]·dba was prepared following
the reported procedure.59 The compounds 3-(2-iodophenyl)-
propanamide, 3-(2-iodophenyl)-N-methylpropanamide, and 3-(2-
iodophenyl)-N,N-dimethylpropanamide were prepared via copper-
catalyzed halogen exchange60 from the corresponding bromo
compounds, which in turn were obtained from commercially available
3-(2-bromophenyl)propanoic acid (see the Supporting Information).
All other reagents were obtained from commercial sources and used
without further purification. NMR spectra were recorded on Bruker
Avance 200, 300, or 400 spectrometers at 298 K. Chemical shifts are
When compared to analogous cyclopalladated phenyl-
acetamides, the reactivity of the palladacycles described in
this article shows important differences, which are mainly
attributable to their larger ring size. These can be summarized
in two main points: (1) The insertions of alkynes into the Pd−
C bond of seven-membered cationic palladacycles are, in most
cases, considerably faster: the monoinsertion product can be
isolated for diarylalkynes and dimethylacetylenedicarboxylate
by using strictly 1 equiv of the alkyne, whereas 3-hexyne gave a
di-insertion product containing a spirocyclic ligand coordinated
through an η3-allylic bond. (2) Cyclizations via C−N couplings
after the insertion of CO or XyNC into the Pd−C bond proved
to be more difficult and were only satisfactory when starting
from the palladacyclic derivatives with the unsubstituted amide
function; in the cases of NHMe derivatives, the C−N couplings
are hampered because of the steric hindrance of the methyl
substituent and the lower acidity of the NH proton.
referred to internal TMS. The assignments of the H and 13C{1H}
1
NMR spectra were made with the help of HMQC and HMBC
experiments. Inserted and coordinated XyNC are denoted by XyNCi
and XyNCc, respectively, and the 1,2-C6H4 arylene group is denoted
by Ar. Melting points were determined on a Reichert apparatus and
are uncorrected. Elemental analyses were carried out with Carlo Erba
1106 and LECO CHNS-932 microanalyzers. Infrared spectra were
recorded in the range 4000−200 cm−1 on a Perkin-Elmer Spectrum
100 spectrophotometer using Nujol mulls between polyethylene
sheets or CH2Cl2 solutions. High-resolution ESI mass spectra were
recorded on an Agilent 6220 Accurate-Mass TOF LC/MS.
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compound crystallizes by chance in a Sohncke space group; in the
absence of significant anomalous dispersion, Friedel opposite
reflections were merged, and the absolute structure is thus
indeterminate. For 13·CH2Cl2, H atoms at coordinated C atoms
were refined freely, but all freely refined hydrogens were subjected to
NH or CH distance restraints.
Synthesis of [Pd{C6H4(CH2)2C(O)NRR′-2}I(tmeda)] [NRR′ =
NH2 (1a), NHMe (1b), NMe2 (1c)]. To a suspension of Pd(dba)2
(903 mg, 1.57 mmol) in CH2Cl2 (20 mL) were added tmeda (0.3 mL,
2.00 mmol) and 3-(2-iodophenyl)propanamide, 3-(2-iodophenyl)-N-
methylpropanamide, or 3-(2-iodophenyl)-N,N-dimethylpropanamide
(1.57 mmol), and the mixture was stirred for 1 h under an N2
atmosphere. The resulting black suspension was filtered through
anhydrous MgSO4, and the clear orange filtrate was concentrated (1
mL). The addition of Et2O (20 mL) led to the precipitation of a pale
orange solid, which was filtered off, washed with Et2O (5 × 3 mL),
recrystallized from CH2Cl2/Et2O, and vacuum-dried to give the
corresponding complex 1.
1a. Yield: 68%. Anal. Calcd for C15H26IN3OPd: C, 36.20; H, 5.27;
N, 8.44. Found: C, 35.82; H, 5.22; N, 8.20. Mp: 147−152 °C (dec). IR
1
(Nujol, cm−1): ν(NH), 3370, 3156; ν(CO), 1652. H NMR (400.9
MHz, CDCl3): δ 7.27−7.23 (m, 1 H, Ar), 6.89−6.86 (m, 1 H, Ar),
6.85−6.77 (m, 2 H, Ar), 6.03 (br, 1 H, NH), 5.30 (br, 1 H, NH), 3.84,
3.23 (AB part of ABXY system, 2JAB = 12.8 Hz, 3JAX = 3JBY = 10.4 Hz,
3JAY = 4.4 Hz, 3JBX = 7.2 Hz, 2 H, CH2, propanamide), 2.95−2.83 (m,
2 H, CH2, tmeda + propanamide), 2.71 (s, 3 H, Me), 2.66 (s, 3 H,
Me), 2.69−2.49 (m, 4 H, CH2, tmeda + propanamide), 2.43 (s, 3 H,
Me), 2.15 (s, 3 H, Me). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ
176.2 (CO), 143.72, 143.66 (C, Ar), 135.9, 127.1, 124.6, 123.2 (CH,
Ar), 62.1, 58.2 (CH2, tmeda), 50.4, 50.2, 49.1, 48.7 (Me), 36.7, 35.9
(CH2, propanamide).
1b. Yield: 67%. Anal. Calcd for C16H28IN3OPd: C, 37.55; H, 5.51;
N, 8.21. Found: C, 37.31; H, 5.50; N, 7.83. Mp: 142−145 °C (dec). IR
1
(Nujol, cm−1): ν(NH), 3384; ν(CO), 1656. H NMR (400.9 MHz,
CDCl3): δ 7.24 (m, 1 H, Ar), 6.87−6.76 (m, 3 H, Ar), 6.01 (br c, 3JHH
= 4.8 Hz, 1 H, NH), 3.78, 3.24 (AB part of ABXY system, 2JAB = 12.8
Figure 2. Above: Thermal ellipsoid plot (50% probability) of complex
3a. Selected bond distances (Å) and angles (deg): Pd−C(1)
1.9875(12), Pd−N(1) 2.0165(11), Pd−N(2) 2.1058(11), Pd−N(3)
2.1882(11), C(9)−O(1) 1.2566(16), C(9)−N(1) 1.3337(17); C(1)−
Pd−N(1) 88.66(5), C(1)−Pd−N(2) 92.80(5), N(1)−Pd−N(3)
94.28(4), N(2)−Pd−N(3) 84.28(4), C(2)−C(7)−C(8) 111.28(11),
C(9)−C(8)−C(7) 120.52(11), O(1)−C(9)−N(1) 123.43(12),
O(1)−C(9)−C(8) 116.18(12), N(1)−C(9)−C(8) 120.32(12),
C(9)−N(1)−Pd 134.03(9). Below: A loose dimer of 3a, with weak
hydrogen bonds N−H···Pd (2.94 Å) and C−Hmethyl···O (2.49 Å)
indicated as dashed lines.
3
3
3
3
Hz, JAX = JBY = 10.0 Hz, JAY = 4.4 Hz, JBX = 7.6 Hz, 2 H, CH2,
propanamide), 2.89−2.76 (m, 2 H, CH2, tmeda + propanamide), 2.73
(d, 3JHH = 4.8 Hz, 3 H, NHMe), 2.71 (s, 3 H, Me, tmeda), 2.66 (s, 3 H,
Me, tmeda), 2.69−2.48 (m, 4 H, CH2, tmeda + propanamide), 2.43 (s,
3 H, Me, tmeda), 2.15 (s, 3 H, Me, tmeda). 13C{1H} APT NMR
(100.8 MHz, CDCl3): δ 174.3 (CO), 143.8, 143.6 (C, Ar), 135.9,
127.1, 124.5, 123.2 (CH, Ar), 62.1, 58.2 (CH2, tmeda), 50.3, 50.2,
49.2, 48.7 (Me, tmeda), 37.2, 36.0 (CH2, propanamide), 26.0
(NHMe).
1c. Yield: 55%. Anal. Calcd for C17H30IN3OPd: C, 38.84; H, 5.75;
N, 7.99. Found: C, 38.48; H, 5.81; N, 7.88. Mp: 170 °C (dec). IR
(Nujol, cm−1): ν(CO), 1639. 1H NMR (400.9 MHz, CDCl3): δ 7.26−
7.22 (m, 1 H, Ar), 6.88−6.85 (m, 1 H, Ar), 6.82−6.77 (m, 2 H, Ar),
3.83−3.74 (m, 1 H, CH2, propanamide), 3.29−3.16 (m, 2 H, CH2,
tmeda + propanamide), 3.00 (s, 3 H, Me, propanamide), 2.96 (s, 3 H,
Me, propanamide), 2.88−2.82 (m, 1 H, CH2, tmeda), 2.69 (s, 3 H,
Me, tmeda), 2.65 (s, 3 H, Me, tmeda), 2.69−2.42 (m, 4 H, CH2,
tmeda + propanamide), 2.40 (s, 3 H, Me, tmeda), 2.19 (s, 3 H, Me,
tmeda). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 173.6 (CO),
144.6, 143.8 (C, Ar), 136.1, 127.1, 124.2, 123.0 (CH, Ar), 62.0, 58.2
(CH2, tmeda), 50.3, 50.2, 49.2, 48.8 (Me, tmeda), 37.6, 35.3 (Me,
propanamide), 34.9, 34.3 (CH2, propanamide).
X-ray Structure Determinations. Crystals suitable for X-ray
diffraction studies were obtained by liquid−liquid diffusion from
CH2Cl2/Et2O (1b), CH2Cl2/n-pentane (3a), CDCl3/n-pentane (8a),
CDCl3/Et2O (9a), CH2Cl2/n-pentane (13·CH2Cl2), Et2O/n-hexane
(14). Numerical details are given in the Supporting Information
(Table S1). The data for 1b, 3a, 8a, 9a, and 13·CH2Cl2 were collected
on an Oxford Diffraction Xcalibur diffractometer using monochro-
mated Mo Kα radiation in ω-scan mode. The data for 14 were
collected on an Oxford Diffraction Nova diffractometer using mirror-
focused Cu Kα radiation in ω-scan mode. Absorption corrections were
based on multiscans. The structures were solved by direct methods
and refined anisotropically on F2 using the program SHELXL-97 (G.
Synthesis of [Pd{κ2C,O-C6H4(CH2)2C(O)NRR′-2}(tmeda)]TfO
[NRR′ = NH2 (2a), NHMe (2b), NMe2 (2c)]. To a solution of the
appropriate complex 1 (0.25 mmol) in acetone (20 mL) was added
AgTfO (63 mg, 0.25 mmol), and the mixture was stirred for 30 min.
The solvent was removed under reduced pressure, the residue was
extracted with CH2Cl2 (6 × 5 mL), and the combined extracts were
filtered through anhydrous MgSO4. Partial evaporation of the filtrate
(1 mL) and addition of Et2O (20 mL) led to the precipitation of an
oily solid. The mother liquor was decanted, and the precipitate was
thoroughly dried under vacuum to give the corresponding complex 2
as a pale yellow solid. Reprecipitations from acetone/Et2O or CH2Cl2/
M. Sheldrick, University of Gottingen).61 Treatment of hydrogen
̈
atoms was as follows: NH hydrogens were refined freely, methyl
hydrogens incorporated into idealized rigid groups allowed to rotate
but not tip, other H using a riding model starting from calculated
positions.
Exceptions and Special Features. For 1b, the two largest difference
peaks lay near C2. These could not be interpreted and may be caused
by unidentified twinning or disorder phenomena. For 3a, the TMEDA
group is slightly disordered, with the minor position being occupied to
the extent of 7%. For 8a, no absorption correction was applied. This
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Figure 3. Above: Thermal ellipsoid plot (50% probability), hydrogen bonds and crystal packing of compound 8a. Selected bond distances (Å) and
angles (deg) of one of the four independent molecules: C(1)−C(7) 1.497(3), C(7)−O(1) 1.238(2), C(7)−N(1) 1.345(3), C(11)−N(1) 1.435(3),
C(10)−N(2) 1.143(3); O(1)−C(7)−N(1) 122.0(2), O(1)−C(7)−C(1) 121.2(2), N(1)−C(7)−C(1) 116.77(18), C(7)−N(1)−C(11)
121.02(17), N(2)−C(10)−C(9) 179.5(3). Below: Packing diagram of 8a, showing chains of molecules linked by hydrogen bonds (dashed
lines). The upper chain consists of molecules 3, 4, 3, 4, ..., and the lower chain of 2, 1, 2, 1, ..., in each case starting from the left.
Et2O did not improve the purity of the products, and acceptable
elemental analyses were obtained only for 2b.
2b. Yield: 91%. Anal. Calcd for C17H28F3N3O4PdS: C, 38.24; H,
5.29; N, 7.87; S, 6.01. Found: C, 38.17; H, 5.26; N, 7.86; S, 6.31. Mp:
60−65 °C (dec). IR (CH2Cl2, cm−1): ν(CO), 1608. HRMS (ESI+, m/
z): exact mass calcd for C16H28N3OPd [M]+ requires 384.1267, found
384.1274, error = 1.82 ppm. HRMS (ESI−, m/z): exact mass calcd for
CF3O3S [M]− requires 148.9526, found 148.9529, error = 2.26 ppm.
2a. Yield: 84%. IR (CH2Cl2, cm−1): ν(CO), 1646. HRMS (ESI+,
m/z): exact mass calcd for C15H26N3OPd [M]+ requires 370.1111,
found 370.1103, error = 2.16 ppm. HRMS (ESI−, m/z): exact mass
calcd for CF3O3S [M]− requires 148.9526, found 148.9532, error =
1
4.03 ppm. H NMR (300.1 MHz, CDCl3): δ 7.84 (br, 1 H, NH),
3
1H NMR (300.1 MHz, CDCl3): δ 8.17 (br c, JHH= 4.8 Hz, NH),
7.06−7.02 (m, 1 H, Ar), 6.96−6.92 (m, 2 H, Ar), 6.86−6.81 (m, 1 H,
Ar), 6.42 (br, 1 H, NH), 4.41 (m, 1 H, CH2 propanamide), 3.05−2.95
(m, 2 H, CH2, tmeda + propanamide), 2.81 (s, 3 H, Me), 2.79−2.62
(m, 5 H, CH2, tmeda + propanamide), 2.58 (s, 3 H, Me), 2.50 (s, 3 H,
Me), 2.46 (s, 3 H, Me). 13C{1H} APT NMR (75.5 MHz, CDCl3): δ
181.0 (CO), 145.5, 143.0 (C, Ar), 132.0, 126.6, 126.0, 125.1 (CH, Ar),
64.3, 57.2 (CH2, tmeda), 53.7, 50.3, 47.9, 46.7 (Me), 34.1, 30.7 (CH2,
propanamide).
7.06−7.02 (m, 1 H, Ar), 6.96−6.89 (m, 2 H, Ar), 6.83−6.79 (m, 1 H,
Ar), 4.44 (m, 1 H, CH2 propanamide), 3.15−2.88 (m, 3 H, CH2,
tmeda + propanamide), 2.86−2.58 (m, 4 H, CH2, tmeda +
propanamide), 2.82 (s, 3 H, Me, tmeda), 2.65 (s, 3 H, Me, tmeda),
2.63 (d, 3JHH= 4.8 Hz, NHMe), 2.53 (s, 3 H, Me, tmeda), 2.44 (s, 3 H,
Me, tmeda). 13C{1H} APT NMR (75.5 MHz, CDCl3): δ 178.0 (CO),
145.4, 142.9 (C, Ar), 131.9, 126.6, 125.8, 125.0 (CH, Ar), 64.3, 57.2
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Figure 4. Thermal ellipsoid plot (50% probability) and hydrogen bonds (dashed lines) in an inversion-symmetric dimer of complex 9a. Selected
bond distances (Å) and angles (deg): Pd−C(1) 2.0039(11), Pd−O(1) 2.0498(9), Pd−N(2) 2.0889(10), Pd−N(3) 2.1524(11), O(1)−C(11)
1.2547(15), N(1)−C(11) 1.3199(17), C(1)−C(2) 1.3534(16), C(2)−C(3) 1.5015(16); C(1)−Pd−O(1) 90.47(4), C(1)−Pd−N(2) 96.38(4),
O(1)−Pd−N(3) 87.44(4), N(2)−Pd−N(3) 85.59(4), C(11)−O(1)−Pd 134.38(8), C(2)−C(1)−Pd 118.42(9), C(1)−C(2)−C(3) 119.94(10),
C(4)−C(9)−C(10) 112.69(10), C(11)−C(10)−C(9) 111.75(10), O(1)−C(11)−N(1) 123.21(12), O(1)−C(11)−C(10) 117.48(11), N(1)−
C(11)−C(10) 119.31(11).
Figure 6. Thermal ellipsoid plot (50% probability) and crystal packing
of compound 14. Selected bond distances (Å) and angles (deg):
Figure 5. Thermal ellipsoid plot (50% probability) of complex 13.
Selected bond distances (Å) and angles (deg): Pd−C(6) 2.2193(12),
Pd−C(7) 2.0828(12), Pd−C(8) 2.1385(12), Pd−N(2) 2.2027(11),
Pd−N(3) 2.1708(11), O(1)−C(13) 1.2361(17), N(1)−C(13)
1.3359(19), C(1)−C(2) 1.3484(19), C(1)−C(5) 1.5218(17),
C(2)−C(3) 1.480(2), C(3)−C(4) 1.3491(17), C(3)−C(18)
1.5030(18), C(4)−C(5) 1.5336(17), C(5)−C(10) 1.5231(17),
C(5)−C(6) 1.5255(17), C(6)−C(7) 1.4076(17), C(7)−C(8)
1.4186(18), C(8)−C(9) 1.4662(17), C(9)−C(10) 1.3425(17);
N(3)−Pd−N(2) 83.19(4), C(7)−Pd−N(2) 134.17(5), C(8)−Pd−
N(2) 172.91(5), C(7)−Pd−N(3) 127.03(5), C(8)−Pd−N(3)
99.94(4), C(7)−Pd−C(8) 39.25(5), C(7)−Pd−C(6) 38.03(5),
C(8)−Pd−C(6) 65.85(5), N(3)−Pd−C(6) 164.72(4), N(2)−Pd−
C(6) 110.31(4), C(7)−C(6)−C(5) 118.87(11), C(6)−C(7)−C(8)
113.96(11), C(7)−C(8)−C(9) 119.70(11), O(1)−C(13)−N(1)
122.72(13), O(1)−C(13)−C(12) 119.71(13), N(1)−C(13)−C(12)
117.57(12).
C(1)−C(2) 1.5566(14), C(2)−C(3) 1.5060(13), C(3)−O(3)
1.2232(12), C(3)−N(4) 1.3865(13), N(4)−C(5) 1.3911(13),
C(5)−O(5) 1.2165(12), C(5)−C(6) 1.5150(13), C(6)−C(7)
1.3466(14); C(11A)−C(1)−C(2) 115.88(8), C(3)−C(2)−C(1)
110.73(8), O(3)−C(3)−N(4) 117.94(9), O(3)−C(3)−C(2)
120.96(9), N(4)−C(3)−C(2) 121.09(8), C(3)−N(4)−C(5)
134.31(8), O(5)−C(5)−N(4) 117.94(9), O(5)−C(5)−C(6)
119.33(9), N(4)−C(5)−C(6) 122.69(8), C(7)−C(6)−C(5)
118.94(9), C(6)−C(7)−C(7A) 118.26(8).
2c. Yield: 58%. IR (CH2Cl2, cm−1): ν(CO), 1591. HRMS (ESI+,
m/z): exact mass calcd for C17H30N3OPd [M]+ requires 398.1424,
found 398.1437, error = 3.27 ppm. HRMS (ESI−, m/z): exact mass
calcd for CF3O3S [M]− requires 148.9526, found 148.9530, error =
3.20 ppm. 1H NMR (400.9 MHz, CDCl3): δ 7.08−7.04 (m, 1 H, Ar),
6.98−6.91 (m, 2 H, Ar), 6.85−6.82 (m, 1 H, Ar), 4.66 (td, 3JHH = 3.2
2
Hz, JHH = 13.6 Hz, 1 H, CH2 propanamide), 3.19−3.09 (m, 2 H,
CH2, tmeda + propanamide), 3.00 (s, 3 H, Me, propanamide), 2.97−
2.94 (m, 1 H, CH2), 2.89 (s, 3 H, Me, propanamide), 2.82 (s, 3 H, Me,
tmeda), 2.82−2.67 (m, 3 H, CH2), 2.64 (s, 3 H, Me, tmeda), 2.62 (s, 3
(CH2, tmeda), 53.9, 50.0, 48.1, 46.5 (Me, tmeda), 34.6, 30.9 (CH2,
propanamide), 26.8 (NHMe).
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H, Me, tmeda), 2.57−2.47 (1 H, CH2), 2.48 (s, 3 H, Me, tmeda).
13C{1H} APT NMR (100.8 MHz, CDCl3): δ 176.0 (CO), 145.6, 143.4
(C, Ar), 132.0, 126.2, 125.9, 124.9 (CH, Ar), 64.4, 57.2 (CH2, tmeda),
54.0, 50.1, 48.1, 46.7 (Me, tmeda), 38.0, 37.0 (Me, propanamide),
34.1, 31.1 (CH2, propanamide).
HRMS (ESI+, m/z): exact mass calcd for C10H10NO2 [M + H]+
requires 176.0706, found 176.0709, error = 1.71 ppm. 1H NMR (400.9
MHz, CDCl3): δ 8.36 (br, 1 H, NH), 8.12 (dd, 4JHH = 1.6 Hz, 3JHH
=
4
3
7.6 Hz, 1 H, H9), 7.52 (td, JHH = 1.6 Hz, JHH = 7.6 Hz, 1 H, H7),
4
3
7.42 (td, JHH = 1.2 Hz, JHH = 7.6 Hz, 1 H, H8), 7.23 (m, 1 H, H6),
3.13−3.10 (m, 2 H, H5), 2.91−2.89 (m, 2 H, H4). 13C{1H} APT
NMR (100.8 MHz, CDCl3): δ 173.3 (C3), 166.2 (C1), 140.5 (C5a),
133.6 (C7), 133.1 (C9), 129.9 (C9a), 128.8 (C6), 127.6 (C8), 36.8
(C4), 29.1 (C5).
Synthesis of [Pd{κ2C,N-C6H4(CH2)2C(O)NR-2}(tmeda)] [R = H
(3a), Me (3b)]. To a solution of 1a or 1b (0.46 mmol) in CH2Cl2 (25
mL) was added KOtBu (414 mg, 3.69 mmol), and the resulting
suspension was stirred for 4 h and then filtered through Celite. Partial
evaporation of the pale yellow filtrate (3 mL) and slow addition of n-
pentane (20 mL) led to the precipitation of a colorless solid, which
was filtered off, recrystallized from CH2Cl2/n-pentane, and vacuum-
dried to give the corresponding complex 3.
Synthesis of trans-[Pd{C(NXy)C6H4(CH2)2C(O)NRR′-2}I-
(CNXy)2] [NRR′ = NH2 (6a), NHMe (6b), NMe2 (6c)]. A mixture
of the appropriate complex 1 (0.16 mmol) and XyNC (66 mg, 0.50
mmol) in CH2Cl2 (20 mL) was stirred for 15 min and filtered through
Celite. Partial evaporation of the yellow filtrate (2 mL) and addition of
n-pentane (30 mL) led to the precipitation of a yellow solid, which was
filtered off, recrystallized from CH2Cl2/n-pentane and vacuum-dried to
give the corresponding complex 6.
3a. Yield: 83%. Anal. Calcd for C15H25N3OPd: C, 48.72; H, 6.81; N,
11.36. Found: C, 48.54; H, 7.21; N, 11.21. Mp: 140−143 °C (dec). IR
(Nujol, cm−1): ν(CO), 1551. 1H NMR (400.9 MHz, CDCl3): δ 7.19−
7.14 (m, 1 H, Ar), 6.90−6.84 (m, 3 H, Ar), 4.16 (m, 1 H, CH2,
3
2
6a. Yield: 77%. Anal. Calcd for C36H37IN4OPd: C, 55.79; H, 4.81;
N, 7.23. Found: C, 55.63; H, 4.61; N, 7.45. Mp: 138−140 °C (dec). IR
(Nujol, cm−1): ν(NH), 3440; ν(CN), 2180; ν(CO), 1677; ν(C
N), 1584. 1H NMR (300.1 MHz, CDCl3): δ 7.86 (m, 1 H, Ar), 7.33−
propanamide), 4.09 (br, 1 H, NH), 2.92 (td, JHH = 4.0 Hz, JHH
=
12.8 Hz, 1 H, CH2, propanamide), 2.85−2.79 (m, 1 H, CH2, tmeda),
2.68 (s, 3 H, Me, tmeda), 2.72−2.67 (m, 1 H, CH2, propanamide),
2.55 (s, 3 H, Me, tmeda), 2.66−2.47 (m, 3 H, CH2, tmeda), 2.44 (s, 3
H, Me, tmeda), 2.31−2.27 (m, 1 H, CH2, propanamide), 2.27 (s, 3 H,
Me, tmeda). 13C{1H} APT NMR (50.3 MHz, CDCl3): δ 178.4 (CO),
151.4, 145.8 (C, Ar), 132.6, 125.6, 124.5, 123.4 (CH, Ar), 62.4, 58.0
(CH2, tmeda), 51.9, 48.9, 47.9, 47.2 (Me, tmeda), 37.8, 36.8 (CH2,
propanamide).
3
7.20 (m, 5 H, Ar + p-H, XyNCc), 7.07 (d, JHH = 7.8 Hz, 4 H, m-H,
XyNCc), 6.90 (s, 3 H, XyNCi), 6.24 (br, 1 H, NH), 5.20 (br, 1 H,
NH), 3.43−3.71 (m, 2 H, CH2, propanamide), 2.99−2.94 (m, 2 H,
CH2, propanamide), 2.22 (s, 6 H, Me, XyNCi), 2.20 (s, 12 H, Me,
XyNCc). 13C{1H} APT NMR (75.5 MHz, CDCl3): δ 178.8 (CN),
174.6 (CO), 149.9 (i-C, XyNCi), 145.1 (C, Ar), 143.0 (br, i-C,
XyNCc), 136.7 (C, Ar), 135.6 (o-C, XyNCc), 130.1 (CH, Ar +
XyNCc), 129.6, 128.8 (CH, Ar), 128.2 (CH, XyNCi), 128.0 (CH,
XyNCc), 127.0 (o-C, XyNCi), 126.6 (CH, Ar), 123.7 (CH, XyNCi),
39.4, 30.4 (CH2), 19.1 (Me, XyNCi), 18.7 (Me, XyNCc); CN of
XyNCc not observed.
3b. This complex was obtained as an hydrate. Yield: 79%. Anal.
Calcd for C16H29.4N3O2.2Pd: C, 47.40; H, 7.31; N, 10.36. Found: C,
47.33; H, 7.55; N, 10.33. Mp: 108−109 °C. IR (Nujol, cm−1): ν(CO),
1
1558. H NMR (400.9 MHz, CDCl3): δ 7.27−7.22 (m, 1 H, Ar),
6.85−6.80 (m, 3 H, Ar), 3.86−3.70 (m, 2 H, CH2, propanamide),
3.12−3.05 (m, 1 H, CH2, propanamide), 2.79−2.72 (m, 1 H, CH2,
tmeda), 2.72 (s, 3 H, Me, propanamide), 2.68−2.60 (m, 13 H, Me,
CH2, tmeda + CH2, propanamide), 2.28 (s, 3 H, Me, tmeda), 1.96 (s,
2 H, H2O). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 176.1 (CO),
149.1, 144.0 (C2, Ar), 132.7, 127.5, 123.9, 122.9 (CH, Ar), 62.1, 58.3
(CH2, tmeda), 51.5, 49.3, 48.8, 48.2 (Me, tmeda), 38.6 (CH2,
propanamide), 36.4 (Me, propanamide), 33.8 (CH2, propanamide).
Synthesis of [Pd{C(O)C6H4(CH2)2C(O)NH2-2}I(tmeda)] (4). CO
was bubbled through a stirred solution of 1a (103 mg, 0.21 mmol) in
CH2Cl2 (10 mL) for 30 min, and the resulting solution was filtered
through Celite. Partial evaporation of the filtrate (5 mL) and addition
of n-pentane (20 mL) led to the precipitation of a yellow solid, which
was collected by filtration, washed with CH2Cl2/n-pentane (5 × 5
mL), and vacuum-dried to give 4·0.5CH2Cl2. Yield: 101 mg, 86%.
Anal. Calcd for C16.5H27ClIN3O2Pd: C, 34.88; H, 4.79; N, 7.40.
Found: C, 34.58; H, 5.06; N, 7.24. Mp: 91−94 °C. IR (Nujol, cm−1):
ν(NH), 3385, 3144; ν(CO), 1677, 1640. 1H NMR (400.9 MHz,
CDCl3): δ 9.09 (dd, 4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1 H, Ar), 7.45 (td,
6b. Yield: 74%. Anal. Calcd for C37H39IN4OPd: C, 56.32; H, 4.98;
N, 7.10. Found: C, 56.50; H, 5.27; N, 7.10. Mp: 131−133 °C (dec). IR
(Nujol, cm−1): ν(NH), 3347; ν(CN), 2178; ν(CO), 1673; ν(C
1
4
N), 1586. H NMR (400.9 MHz, CDCl3): δ 7.76 (dd, JHH = 1.2 Hz,
3JHH = 7.2 Hz, 1 H, Ar), 7.34−7.28 (m, 2 H, Ar), 7.27−7.21 (m, 3 H,
Ar + p-H, XyNCc), 7.07 (d, 3JHH = 7.2 Hz, 4 H, m-H, XyNCc), 6.91 (s,
3 H, XyNCi), 6.33 (br c, 3JHH = 4.8 Hz, 1 H, NH), 3.40−3.35 (m, 2 H,
CH2, propanamide), 2.96−2.92 (m, 2 H, CH2, propanamide), 2.57 (d,
3JHH = 4.8 Hz, 3 H, NMe), 2.22 (s, 6 H, Me, XyNCi), 2.20 (s, 12 H,
Me, XyNCc). 13C{1H} APT NMR (75.5 MHz, CDCl3): δ 178.6 (C
N), 172.8 (CO), 149.9 (i-C, XyNCi), 145.3 (C, Ar), 143.0 (br, i-C,
XyNCc), 137.1 (C, Ar), 135.6 (o-C, XyNCc), 130.2 (CH, Ar), 130.1
(CH, XyNCc), 128.8 (CH, Ar), 128.2 (CH, XyNCi), 128.0 (CH,
XyNCc), 127.0 (o-C, XyNCi), 126.6 (CH, Ar), 123.7 (CH, XyNCi),
40.3, 30.9 (CH2), 25.8 (NMe), 19.1 (Me, XyNCi), 18.7 (Me, XyNCc);
CN of XyNCc not observed.
6c. Yield: 79%. Anal. Calcd for C38H41IN4OPd: C, 56.83; H, 5.15;
N, 6.98. Found: C, 56.94; H, 5.34; N, 6.93. Mp: 139−140 °C (dec.).
IR (Nujol, cm−1): ν(CN), 2174; ν(CO), 1649; ν(CN), 1590. 1H
NMR (300.1 MHz, CDCl3): δ 8.08 (d, 3JHH = 7.2 Hz, 1 H, Ar), 7.34−
4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1 H, Ar), 7.31 (td, 4JHH = 1.2 Hz, 3JHH
=
7.6 Hz, 1 H, Ar), 7.11 (dd, 4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1 H, Ar), 6.07
(s, 1 H, NH), 5.30 (s, 1 H, CH2Cl2), 5.13 (s, 1 H, NH), 3.17 (m, 2 H,
CH2, propanamide), 2.76 (m, 2 H, CH2, tmeda), 2.59 (s, 6 H, Me,
tmeda), 2.55 (m, 2 H, CH2, tmeda), 2.52 (s, 6 H, Me, tmeda), 2.49
(m, 2 H, CH2, propanamide). 13C{1H} APT NMR (75.5 MHz,
CDCl3): δ 175.3 (CONH2), 139.6 (CH, Ar), 138.4, 136.8 (C, Ar),
130.9, 130.6, 126.2 (CH, Ar), 61.8, 57.6 (CH2, tmeda), 50.4, 48.9 (Me,
tmeda), 37.4, 31.2 (CH2, propanamide); PdC not observed.
3
7.19 (m, 5 H, Ar + p-H, XyNCc), 7.06 (d, JHH = 7.5 Hz, 4 H, m-H,
XyNCc), 6.90 (s, 3 H, XyNCi), 3.33−3.28 (m, 2 H, CH2,
propanamide), 2.89−2.84 (m, 2 H, CH2, propanamide), 2.85 (s, 3
H, NMe), 2.77 (s, 3 H, NMe), 2.21 (s, 18 H, Me, XyNCi + XyNCc).
13C{1H} APT NMR (75.5 MHz, CDCl3): δ 177.8 (CN), 172.4
(CO), 149.8 (i-C, XyNCi), 145.1, 136.8 (C, Ar), 135.6 (o-C, XyNCc),
131.3, 130.6 (CH, Ar), 129.9 (CH, XyNCc), 128.4 (CH, Ar), 128.0
(CH, XyNCi), 127.9 (CH, XyNCc), 126.9 (o-C, XyNCi), 126.2 (CH,
Ar), 123.4 (CH, XyNCi), 37.1 (NMe), 36.5 (CH2), 35.2 (NMe), 30.3
(CH2), 19.2 (Me, XyNCi), 18.7 (Me, XyNCc); i-C and CN of
XyNCc not observed.
Synthesis of 4,5-Dihydro-2H-benzo[c]azepine-1,3-dione
(5a). To a solution of 1a (134 mg, 0.27 mmol) in acetone (15 mL)
was added AgTfO (70 mg, 0.27 mmol), and the resulting suspension
was stirred for 15 min. The solvent was removed under vacuum, the
residue was extracted with CH2Cl2 (6 × 5 mL), and the combined
extracts were filtered through Celite. The filtrate was stirred under a
CO atmosphere (1.4 bar) for 6 h, whereupon a black precipitate of Pd
gradually formed. The solvent was removed under vacuum, the residue
was extracted with a 1:10 CH2Cl2/n-hexane mixture (6 × 5 mL), and
the combined extracts were filtered through Celite. Evaporation of the
solvents under reduced pressure gave 5a as a colorless solid. Yield: 20
mg, 42%. Mp: 115−118 °C. IR (Nujol, cm−1): ν(CO), 1668, 1662.
Synthesis of 1-(2,6-Dimethylphenylimino)-1,2,4,5-
tetrahydrobenzo[c]azepin-3-one (7a) and 2-(2-Cyanoethyl)-N-
(2,6-dimethylphenyl)benzamide (8a). To a solution of 1a (217
mg, 0.44 mmol) in CHCl3 (15 mL) was added XyNC (57.2 mg, 0.44
mmol), and the mixture was refluxed for 24 h. A black precipitate of
Pd gradually formed. The solvent was removed under vacuum, the
residue was extracted with Et2O (6 × 5 mL), and the extracts were
1900
dx.doi.org/10.1021/om4000192 | Organometallics 2013, 32, 1892−1904

Organometallics
Article
filtered through Celite. Partial evaporation of the solvents (3 mL) and
slow addition of n-pentane (30 mL) led to the precipitation of a
colorless solid, which was filtered off, washed with n-pentane (5 × 3
mL), and vacuum-dried to give 8a. The filtrate was evaporated to
dryness, the residue was stirred in n-pentane (30 mL) for 1 h, and the
resulting suspension was filtered through Celite. Compound 7a was
obtained as a yellow oil after evaporation of the solvent.
65.0, 56.6 (CH2, tmeda), 53.3, 49.1, 48.9, 44.7 (Me), 37.7, 30.3 (CH2,
propanamide).
9b. Yield: 75%. Anal. Calcd for C31H38F3N3O4PdS: C, 52.28; H,
5.38; N, 5.90; S, 4.50. Found: C, 52.28; H, 5.42; N, 5.93; S, 4.37. Mp:
153−155 °C (dec). IR (Nujol, cm−1): ν(NH), 3278; ν(CO), 1614.
HRMS (ESI+, m/z): exact mass calcd for C30H38N3OPd [M]+ requires
562.2050, found 562.2059, error = 1.60 ppm. HRMS (ESI−, m/z):
exact mass calcd for CF3O3S [M]− requires 148.9526, found 148.9529,
7a. Yield: 57 mg, 47%. IR (Nujol, cm−1): ν(NH), 3325; ν(CO),
1707; ν(CN), 1633. HRMS (ESI+, m/z): exact mass calcd for
C18H19N2O [M + H]+ requires 279.1492, found 279.1496, error = 1.55
ppm. 1H NMR (400.9 MHz, CDCl3): δ 8.19 (dd, 4JHH = 1.6 Hz, 3JHH
= 7.6 Hz, 1 H, H9), 7.47 (td, 4JHH = 1.6 Hz, 3JHH = 7.6 Hz, 1 H, H7),
7.44 (overlapped broad signal, 1 H, NH), 7.42 (td, 4JHH = 1.6 Hz, 3JHH
= 7.6 Hz, 1 H, H8), 7.23 (m, 1 H, H6), 7.10 (m, 2 H, m-H, Xy), 6.97
(m, 1 H, p-H, Xy), 3.08−3.05 (m, 2 H, H5), 2.88−2.86 (m, 2 H, H4),
2.14 (s, 6 H, Me). 13C{1H} APT NMR (75.5 MHz, CDCl3): δ 172.8
(C3), 147.7 (C1), 143.5 (i-C, Xy), 139.6 (C5a), 132.5 (C9a), 131.4
(C7), 131.2 (C9), 128.7 (m-C, Xy), 128.0 (C6), 127.5 (C8), 124.3 (p-
C, Xy), 38.0 (C4), 29.4 (C5), 17.9 (Me); o-C of Xy not observed.
8a. Yield: 22 mg, 18%. Anal. Calcd for C18H18N2O: C, 77.67; H,
6.52; N, 10.06. Found: C, 77.70; H, 6.70; N, 10.10. Mp: 120−122 °C.
IR (Nujol, cm−1): ν(NH), 3243; ν(CN), 2245; ν(CO), 1643. HRMS
(ESI+, m/z): exact mass calcd for C18H19N2O [M + H]+ requires
error = 2.18 ppm. 1H NMR (400.9 MHz, CDCl3): δ 8.48 (br c, 3JHH
=
4
3
4.8 Hz, 1 H, NH), 7.75 (dd, JHH = 1.2 Hz, JHH = 7.2 Hz, 1 H, Ar),
4
3
7.48 (td, JHH = 1.2 Hz, JHH = 7.2 Hz, 1 H, Ar), 7.40−7.37 (m, 2 H,
Ph), 7.25 (td, 4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1 H, Ar), 7.22−7.19 (m, 3
4
3
H, Ph), 7.09 (dd, JHH = 1.2 Hz, JHH = 7.6 Hz, 1 H, Ar), 7.03−6.99
(m, 3 H, Ph), 6.87−6.85 (m, 2 H, Ph), 3.29−3.22 (m, 1 H, CH2,
3
2
propanamide), 2.98 (td, JHH = 3.2 Hz, JHH = 12.8 Hz, 1 H, CH2,
3
tmeda), 2.69 (d, JHH = 4.8 Hz, 3 H, Me, propanamide), 2.68−2.52
(m, 4 H, CH2, propanamide + tmeda), 2.58 (s, 3 H, Me, tmeda),
2.39−2.35 (m, 1 H, CH2, tmeda), 2.36 (s, 3 H, Me, tmeda), 2.26−2.21
(m, 1 H, CH2, tmeda), 1.94 (s, 3 H, Me, tmeda), 1.91 (s, 3 H, Me,
tmeda). 13C{1H} APT NMR (75.5 MHz, CDCl3): δ 180.2 (CO),
144.1 (C, Ar), 143.2 (CPd), 142.3 (C, Ph), 139.0 (PdCC), 138.42,
138.39 (C, Ph, Ar), 131.2, 129.8 (CH, Ar), 128.8, 128.7, 128.5, 127.7
(CH, Ph), 127.5, 126.18 (CH, Ar), 126.15, 126.0 (CH, Ph), 64.5, 56.8
(CH2, tmeda), 52.8, 49.4, 48.6, 45.1 (Me, tmeda), 34.5, 31.4 (CH2,
propanamide), 27.6 (Me, propanamide).
1
279.1492, found 279.1496, error = 1.6 ppm. H NMR (400.9 MHz,
CDCl3): δ 7.69 (dd, 4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1 H, H6, Ar), 7.52
(td, 4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1 H, H4, Ar), 7.44 (m, 1 H, H3, Ar),
9c. Yield: 62%. Anal. Calcd for C32H40F3N3O4PdS: C, 52.93; H,
5.55; N, 5.79; S, 4.42. Found: C, 52.96; H, 5.71; N, 5.79; S, 4.90. Mp:
153−154 °C (dec). IR (Nujol, cm−1): ν(CO), 1592. HRMS (ESI+, m/
z): exact mass calcd for C31H40N3OPd [M]+ requires 576.2206, found
576.2217, error = 1.81 ppm. HRMS (ESI−, m/z): exact mass calcd for
CF3O3S [M]− requires 148.9526, found 148.9525, error = 0.22 ppm.
7.41 (m, 1 H, H5, Ar), 7.20−7.13 (m, 4 H, NH + Xy), 3.14 (t, 3JHH
=
7.2 Hz, 2 H, CH2CH2CN), 2.86 (t, 3JHH = 7.2 Hz, 2 H, CH2CH2CN),
2.34 (s, 6 H, Me). 13C{1H} APT NMR (75.5 MHz, CDCl3): δ 167.7
(CO), 137.8 (C2, Ar), 135.5 (C1, Ar), 135.4 (o-C, Xy), 133.3 (i-C,
Xy), 131.4 (C3, Ar), 131.1 (C4, Ar), 128.4 (m-C, Xy), 127.8 (p-C,
Xy), 127.6 (C5, Ar), 127.1 (C6, Ar), 119.4 (CN), 30.0 (CH2CH2CN),
19.6 (CH2CH2CN), 18.6 (Me).
4
3
1H NMR (400.9 MHz, CDCl3): 7.69 (dd, JHH = 1.6 Hz, JHH = 7.6
Hz, 1 H, Ar), 7.50 (td, 4JHH = 1.6 Hz, 3JHH = 7.6 Hz, 1 H, Ar), 7.44−
4
3
7.40 (m, 2 H, Ph), 7.33 (td, JHH = 1.6 Hz, JHH = 7.6 Hz, 1 H, Ar),
7.22−7.19 (m, 3 H, Ph), 7.11 (dd, 4JHH = 1.6 Hz, 3JHH = 7.6 Hz, 1 H,
Ar), 7.06−6.99 (m, 3 H, Ph), 6.86−6.83 (m, 2 H, Ph), 3.59−3.51 (m,
1 H, CH2, propanamide), 3.23 (s, 3 H, Me, propanamide), 2.95 (s, 3
H, Me, propanamide), 2.95−2.87 (m, 2H, CH2, propanamide +
tmeda), 2.74−2.54 (m, 4 H, CH2, propanamide + tmeda), 2.51 (s, 3
H, Me, tmeda), 2.44 (s, 3 H, Me, tmeda), 2.41−2.35 (m, 1 H, CH2,
tmeda), 2.08 (s, 3 H, Me, tmeda), 2.06 (s, 3 H, Me, tmeda). 13C{1H}
APT NMR (100.8 MHz, CDCl3): δ 178.6 (CO), 145.2 (CPd), 143.8
(C, Ar), 142.6, 139.3 (C, Ph), 138.9 (PdCC), 138.0 (C, Ar), 130.6,
130.3 (CH, Ar), 128.95, 128.91, 128.4 (CH, Ph), 127.7 (CH, Ar),
127.6 (CH, Ph), 126.7 (CH, Ar), 126.1, 125.9 (CH, Ph), 64.7, 56.9
(CH2, tmeda), 52.4, 50.1, 48.5, 45.9 (Me, tmeda), 39.4, 37.4 (Me,
propanamide), 33.5, 29.4 (CH2, propanamide).
[Pd{κ2C,O-C(X)C(X)C6H4(CH2)2C(O)NRR′-2}(tmeda)]TfO
n
[NRR′ = NH2, X = Ph (9a), C6H4 Bu-4 (10a), C6H4Br-4 (11a),
CO2Me (12a); NRR′ = NHMe, X = Ph (9b); NRR′ = NMe2, X = Ph
(9c)]. A mixture of the appropriate complex 1 (0.27 mmol) and
AgTfO (74 mg, 0.29 mmol) in acetone (15 mL) was stirred for 30
min. The solvent was removed under vacuum, the residue was
extracted with CH2Cl2 (6 × 5 mL), and the combined extracts were
filtered through anhydrous MgSO4. The alkyne (0.27 mmol) was then
added to the filtrate, and the solution was stirred at room temperature
for 3 h (except for the synthesis of 11a, which required 20 h) and then
filtered through anhydrous MgSO4. The filtrate was evaporated to
dryness, and the residue was crystallized from CH2Cl2/Et2O (9a−c,
12a), Et2O/n-pentane (10a), or acetone/n-pentane (11a). Analytically
pure samples of the products were obtained by successive
recrystallizations.
10a. Yield: 60%. Anal. Calcd for C38H52F3N3O4PdS: C, 56.33; H,
6.47; N, 5.19; S, 3.96. Found: C, 56.48; H, 6.77; N, 5.08; S, 4.20. Mp:
104−105 °C. IR (Nujol, cm−1): ν(NH), 3335, 3191; ν(CO), 1649.
HRMS (ESI+, m/z): exact mass calcd for C37H52N3OPd [M]+ requires
660.3145, found 660.3154, error = 1.36 ppm. HRMS (ESI−, m/z):
exact mass calcd for CF3O3S [M]− requires 148.9526, found 148.9529,
9a. Yield: 77%. Anal. Calcd for C30H36F3N3O4PdS: C, 51.61; H,
5.20; N, 6.02; S, 4.59. Found: C, 51.49; H, 5.26; N, 6.01; S, 4.32. Mp:
163−164 °C (dec). IR (Nujol, cm−1): ν(NH), 3395, 3218; ν(CO),
1651. HRMS (ESI+, m/z): exact mass calcd for C29H36N3OPd [M]+
requires 548.1893, found 548.1901, error = 1.46 ppm. HRMS (ESI−,
m/z): exact mass calcd for CF3O3S [M]− requires 148.9526, found
1
error = 1.97 ppm. H NMR (400.9 MHz, CDCl3): δ 7.74 (br, 1 H,
NH), 7.73 (m, 1 H, Ar), 7.45−7.40 (m, 3 H, Ph + Ar), 7.29 (m, 1 H,
1
3
148.9530, error = 3.20 ppm. H NMR (400.9 MHz, CDCl3): δ 7.76
Ar), 7.25 (br, 1 H, NH), 7.13 (m, 1 H, Ar), 7.01 (d, JHH = 8.0 Hz, 2
4
3
H, Ph), 6.77 (d, 3JHH = 8.0 Hz, 2 H, Ph), 6.66 (d, 3JHH = 8.0 Hz, 2 H,
Ph), 3.01 (td, 3JHH = 3.2 Hz, 2JHH = 12.8 Hz, 1 H, CH2, tmeda), 2.80−
2.75 (m, 1 H, CH2, propanamide), 2.69 (td, 3JHH = 2.8 Hz, 2JHH = 13.6
Hz, 1 H, CH2, tmeda), 2.56 (s, 3 H, Me, tmeda), 2.53−2.43 (m, 6 H,
CH2, nBu + propanamide), 2.38 (s, 3 H, Me, tmeda), 2.37−2.31 (m, 1
H, CH2, propanamide), 2.23−2.20 (m, 1 H, CH2, tmeda), 2.12−2.08
(m, 1 H, CH2, tmeda), 1.98 (s, 3 H, Me, tmeda), 1.90 (s, 3 H, Me,
(dd, JHH = 1.2 Hz, JHH = 7.6 Hz, 1 H, Ar), 7.74 (overlapped broad
signal, 1 H, NH), 7.53 (br, 1 H, NH), 7.50−7.44 (m, 3 H, Ph + Ar),
4
3
7.29 (td, JHH = 1.2 Hz, JHH = 7.6 Hz, 1 H, Ar), 7.20−7.16 (m, 2 H,
Ph), 7.13−7.10 (m, 2 H, Ar + Ph), 7.00−6.94 (m, 3 H, Ph), 6.81−6.78
3
2
(m, 2 H, Ph), 3.03 (td, JHH = 3.2 Hz, JHH = 12.8 Hz, 1 H, CH2,
3
tmeda), 2.89−2.83 (m, 1 H, CH2, propanamide), 2.68 (td, JHH = 3.2
Hz, JHH = 14.0 Hz, 1 H, CH2, tmeda), 2.56 (s, 3 H, Me), 2.53−2.40
2
n
(m, 2 H, CH2, propanamide), 2.36 (s, 3 H, Me), 2.38−2.31 (m, 1 H,
CH2, propanamide), 2.27−2.24 (m, 1 H, CH2, tmeda), 2.15−2.11 (m,
1 H, CH2, tmeda), 1.97 (s, 3 H, Me), 1.88 (s, 3 H, Me). 13C{1H} APT
NMR (75.5 MHz, CDCl3): δ 184.2 (CO), 145.1 (C, Ar), 143.8
(CPd), 142.6 (C, Ph), 140.34 (PdCC), 140.28 (C, Ph), 139.8 (C,
Ar), 130.6, 130.02 (CH, Ar), 129.96, 129.5, 128.3, 127.40 (CH, Ph),
127.35 (CH, Ar), 125.8 (CH, Ph), 125.7 (CH, Ar), 125.5 (CH, Ph),
tmeda), 1.58−1.44 (m, 4 H, CH2, Bu), 1.35−1.21 (m, 4 H, CH2,
3
3
nBu), 0.91 (t, JHH = 7.2 Hz, 3 H, Me), 0.87 (t, JHH = 7.2 Hz, 3 H,
Me). 13C{1H} APT NMR (75.5 MHz, CDCl3): δ 183.8 (CO), 145.1
(C, Ar), 142.9 (CPd), 140.6 (C, C6H4 Bu-4), 140.0 (C, Ph), 139.7 (C,
C6H4 Bu-4), 139.4 (C, Ar), 139.3 (PdC=C), 137.3 (C, C6H4nBu-4),
130.5, 130.2 (CH, Ar), 129.6, 129.1, 128.4, 127.4 (CH, C6H4 Bu-4),
127.2, 125.7 (CH, Ar), 64.8, 56.6 (CH2, tmeda), 53.2, 48.9, 48.8, 44.6
n
n
n
1901
dx.doi.org/10.1021/om4000192 | Organometallics 2013, 32, 1892−1904

Organometallics
Article
(Me, tmeda), 37.1 (CH2, propanamide), 35.3, 35.1, 33.3, 33.2 (CH2,
(C1−4), 129.4 (C10), 114.2 (C9), 107.8 (C7), 103.1 (C6), 70.7 (C5),
64.6 (C8), 60.2 (CH2, tmeda), 51.0 (br, Me, tmeda), 31.7, 25.2 (CH2,
propanamide), 22.4, 19.12, 19.09, 18.3 (CH2CH3), 15.3, 15.1, 14.9,
14.5 (CH2CH3).
n
nBu), 30.5 (CH2, propanamide), 22.2, 22.1 (CH2, Bu), 13.92, 13.88
n
(Me, Bu).
11a. Yield: 72%. Anal. Calcd for C30H34Br2F3N3O4PdS: C, 42.10; H,
4.00; N, 4.91; S, 3.75. Found: C, 42.33; H, 4.14; N, 4.86; S, 3.66. Mp:
172−173 °C (dec). IR (Nujol, cm−1): ν(NH), 3378, 3199; ν(CO),
1646. HRMS (ESI+, m/z): exact mass calcd for C29H34N3OPd [M]+
requires 706.0093, found 706.0093, error = 0 ppm. HRMS (ESI−, m/
z): exact mass calcd for CF3O3S [M]− requires 148.9526, found
148.9526, error = 0 ppm. 1H NMR (400.9 MHz, CDCl3): δ 8.19 (br, 1
H, NH), 7.70 (dd, 4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1 H, Ar), 7.53 (br, 1
H, NH), 7.45−7.41 (m, 3 H, C6H4Br-4 + Ar), 7.35−7.30 (m, 3 H,
Synthesis of (Z)-6,7-Diphenyl-1,2-dihydro-4H-benzo[e]-
azonine-3,5-dione (14), (Z)-6,7-Bis(4-butylphenyl)-1,2-dihy-
dro-4H-benzo[e]azonine-3,5-dione (15), and (Z)-6,7-Bis(4-bro-
mophenyl)-1,2-dihydro-4H-benzo[e]azonine-3,5-dione (16). A
solution of the corresponding complex 9a, 10a, or 11a (0.30 mmol) in
CHCl3 (15 mL) was stirred under a CO atmosphere (1.4 bar) at 50
°C for 15 h, whereupon a black precipitate of Pd gradually formed.
The suspension was filtered through anhydrous MgSO4, and the
solvent was removed under reduced pressure. The residue was purified
by flash chromatography on silica gel, using a 3:1 EtOAc/n-hexane
mixture as eluent [Rf = 0.8−0.9 (14), 0.7−0.8 (15), 0.8 (16)]. The
compounds were isolated as colorless solids (14 and 16) or as a yellow
oil (15) after evaporation of the solvents.
4
3
C6H4Br-4 + Ar), 7.16 (dd, JHH = 1.2 Hz, JHH = 7.6 Hz, 1 H, Ar),
7.11−7.08 (m, 2 H, C6H4Br-4), 6.64−6.61 (m, 2 H, C6H4Br-4), 3.02
(td, 3JHH = 3.2 Hz, 2JHH = 13.2 Hz, 1 H, CH2, tmeda), 2.82−2.70 (m, 2
H, CH2, propanamide + tmeda), 2.53 (s, 3 H, Me), 2.46−2.44 (m, 2
H, CH2, propanamide), 2.40 (s, 3 H, Me), 2.35−2.31 (m, 1 H, CH2,
propanamide), 2.27−2.23 (m, 1 H, CH2, tmeda), 2.12−2.08 (m, 1 H,
CH2, tmeda), 2.01 (s, 3 H, Me), 2.00 (s, 3 H, Me). 13C{1H} APT
NMR (75.5 MHz, CDCl3): δ 184.7 (CO), 145.0 (C, Ar), 143.6
(CPd), 141.6 (C, C6H4Br-4), 140.41 (C, Ar), 140.36 (PdCC), 139.6
(C, C6H4Br-4), 131.9, 131.6, 131.4, 130.7 (CH, C6H4Br-4), 130.5,
129.7, 127.6, 125.6 (CH, Ar), 120.1, 119.5 (CBr), 65.2, 56.7 (CH2,
tmeda), 53.5, 49.4, 49.0, 44.8 (Me), 38.7, 29.9 (CH2, propanamide).
12a. Yield: 85%. Anal. Calcd for C22H32F3N3O8PdS: C, 39.92; H,
4.87; N, 6.35; S, 4.84. Found: C, 40.13; H, 5.11; N, 6.37; S, 4.67. Mp:
144−146 °C (dec). IR (Nujol, cm−1): ν(NH), 3385, 3263, 3226;
ν(CO), 1712, 1683, 1669. HRMS (ESI+, m/z): exact mass calcd for
C21H32N3O5Pd [M]+ requires 512.1377, found 512.1385, error = 1.56
ppm. HRMS (ESI−, m/z): exact mass calcd for CF3O3S [M]− requires
14. Yield: 52%. Mp: 202−203 °C. IR (Nujol, cm−1): ν(NH), 3224;
ν(CO), 1685. HRMS (ESI+, m/z): exact mass calcd for C24H20NO2
1
[M + H]+ requires 354.1489, found 354.1493, error = 1.19 ppm. H
NMR (400.9 MHz, CDCl3): δ 7.68 (br, 1 H, NH), 7.36−7.08 (m, 14
H, H8−11 + Ph), 3.99−3.91 (m, 1 H, H2), 3.25−3.19 (m, 1 H, H1),
3.07−2.99 (m, 1 H, H1), 2.87−2.82 (m, 1 H, H2). 13C{1H} APT
NMR (75.5 MHz, CDCl3): δ 172.4 (C3), 169.6 (C5), 141.7 (C7),
140.1 (C7a), 137.0 (C, Ph), 135.6 (C11a), 134.6 (C, Ph), 134.1 (C6),
131.2 (C11), 129.8 (CH, Ph), 129.4 (CH, Ph + C8), 128.9 (CH, Ph),
128.8 (C10), 128.6 (CH, Ph), 128.32 (CH, Ph), 128.28 (CH, Ph),
127.7 (C9), 34.4 (C2), 31.2 (C1).
15. Yield: 46%. IR (CH2Cl2, cm−1): ν(CO), 1701, 1681. HRMS
(ESI+, m/z): exact mass calcd for C32H36NO2 [M + H]+ requires
1
466.2741, found 466.2746, error = 1.15 ppm. H NMR (400.9 MHz,
1
148.9526, found 148.9528, error = 1.62 ppm. H NMR (400.9 MHz,
CDCl3): δ 7.59 (br, 1 H, NH), 7.31−7.21 (m, 5 H, H8−10 + H2 and
CDCl3): δ 7.84 (s, 1 H, NH), 7.79 (s, 1 H, NH), 7.46 (dd, 4JHH = 1.2
Hz, 3JHH = 7.6 Hz, 1 H, Ar), 7.38 (td, 4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1
H, Ar), 7.33 (td, 4JHH = 1.2 Hz, 3JHH = 7.6 Hz, 1 H, Ar), 7.21 (m, 1 H,
Ar), 3.89 (s, 3 H, CO2Me), 3.61 (s, 3 H, CO2Me), 3.07−2.78 (m, 4 H,
CH2, tmeda + propanamide), 2.90 (s, 3 H, Me, tmeda), 2.86 (s, 3 H,
Me, tmeda), 2.55−2.48 (m, 1 H, CH2, propanamide), 2.34 (s, 3 H,
Me, tmeda), 2.35−2.23 (m, 2 H, CH2, tmeda + propanamide), 2.20−
2.17 (m, 1 H, CH2, tmeda), 2.03 (s, 3 H, Me, tmeda). 13C{1H} APT
NMR (75.5 MHz, CDCl3): δ 184.2 (CONH2), 172.9, 162.3 (CO2Me),
159.6 (CPd), 140.6, 139.9 (C, Ar), 135.2 (PdCC), 129.7, 128.9,
128.1, 126.3 (CH, Ar), 65.5, 57.7 (CH2, tmeda), 55.0 (Me, tmeda),
52.11, 52.04 (CO2Me), 49.2, 48.6, 45.0 (Me, tmeda), 39.3, 31.1 (CH2,
propanamide).
n
H6 of C6H4 Bu-4), 7.15−7.13 (m, 1 H, H11), 7.11−7.07 (m, 2 H, H3
n
n
and H5 of C6H4 Bu-4), 7.01−6.98 (m, 2 H, H2 and H6 of C6H4 Bu-
n
4), 6.96−6.94 (m, 2 H, H3 and H5 of C6H4 Bu-4), 3.97−3.91 (m, 1 H,
H2), 3.23−3.17 (m, 1 H, H1), 3.04−2.96 (m, 1 H, H1), 2.83−2.78
3
n
3
(m, 1 H, H2), 2.59 (t, JHH = 8.0 Hz, 2 H, CH2, Bu), 2.52 (t, JHH
=
8.0 Hz, 2 H, CH2, nBu), 1.59−1.49 (m, 4 H, CH2, nBu), 1.39−1.25 (m,
n
3
3
4 H, CH2, Bu), 0.92 (t, JHH = 7.2 Hz, 3 H, Me), 0.89 (t, JHH = 7.2
Hz, 3 H, Me). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 172.6
n
(C3), 170.0 (C5), 143.4, 143.3 (C, C6H4 Bu-4), 141.0 (C7), 140.5
(C7a), 135.7 (C11a), 134.3 (C, C6H4 Bu-4), 133.4 (C6), 131.9 (C,
C6H4 Bu-4), 131.1 (C11), 129.7 (CH, C6H4 Bu-4), 129.5 (C8), 129.2,
128.9 (CH, C6H4 Bu-4), 128.7 (C10), 128.2 (CH, C6H4 Bu-4), 127.7
(C9), 35.4, 35.3 (CH2, Bu), 34.4 (C2), 33.3, 33.2 (CH2, Bu), 31.2
(C1), 22.3 (CH2, Bu), 13.91, 13.89 (Me).
n
n
n
n
n
n
n
Synthesis of [Pd{η3-C6H4(C4Et4)(CH2)2C(O)NH2}(tmeda)]TfO
(13). To a solution of 1a (262 mg, 0.53 mmol) in acetone (15 mL)
was added AgTfO (136 mg, 0.53 mmol), and the resulting suspension
was stirred for 30 min. The solvent was removed under vacuum, the
residue was extracted with CH2Cl2 (6 × 5 mL), and the combined
extracts were filtered through anhydrous MgSO4. 3-Hexyne (180 μL,
1.57 mmol) was then added to the filtrate, and the mixture was stirred
for 15 h and filtered through anhydrous MgSO4. Partial evaporation of
the filtrate (5 mL) and addition of n-pentane (30 mL) gave a yellowish
orange precipitate, which was collected by filtration and recrystallized
from CH2Cl2/Et2O to give 13 as a yellow solid. Yield: 291 mg, 81%.
Anal. Calcd for C28H46F3N3O4PdS: C, 49.16; H, 6.78; N, 6.14; S, 4.69.
Found: C, 48.71; H, 6.79; N, 6.05; S, 4.50. Mp: 122−123 °C (dec). IR
(Nujol, cm−1): ν(NH), 3353, 3160; ν(CO), 1684. HRMS (ESI+, m/
z): exact mass calcd for C27H46N3OPd [M]+ requires 534.2676, found
534.2697, error = 3.93 ppm. HRMS (ESI−, m/z): exact mass calcd for
CF3O3S [M]− requires 148.9526, found 148.9529, error = 2.05 ppm.
n
16. Yield: 72%. Anal. Calcd for C24H17Br2NO2: C, 56.39; H, 3.35;
N, 2.74. Found: C, 56.31; H, 3.38; N, 2.82. Mp: 155−157 °C. IR
(Nujol, cm−1): ν(NH), 3200; ν(CO), 1702, 1682. HRMS (ESI+,
m/z): exact mass calcd for C24H18Br2NO2 [M + H]+ requires 511.968,
1
found 511.969, error = 2.01 ppm. H NMR (400.9 MHz, CDCl3): δ
7.64 (br, 1 H, NH), 7.47−7.43 (m, 2 H, C6H4Br-4), 7.34−7.28 (m, 4
H, H9, H10 + C6H4Br-4), 7.24−7.21 (m, 2 H, C6H4Br-4), 7.20−7.16
(m, 2 H, H8, H11), 6.97−6.93 (m, 2 H, C6H4Br-4), 3.81−3.73 (m, 1
H, H2), 3.21−3.15 (m, 1 H, H1), 3.09−3.01 (m, 1 H, H1), 2.87−2.82
(m, 1 H, H2). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 172.0
(C3), 168.8 (C5), 141.1 (C7), 139.4 (C7a), 135.7 (C, C6H4Br-4),
135.4 (C11a), 133.6 (C6), 133.1 (C, C6H4Br-4), 132.4, 131.8 (CH,
C6H4Br-4), 131.4 (C11), 131.3, 130.9 (CH, C6H4Br-4), 129.3 (C8),
129.2 (C10), 128.0 (C9), 123.2, 123.0 (CBr), 34.5 (C2), 31.1 (C1).
1H NMR (400.9 MHz, CDCl3): δ 6.70 (br, 1 H, NH), 6.10 (d, 3JHH
=
ASSOCIATED CONTENT
■
6.0 Hz, H9), 6.01 (dd, JHH = 6.4 Hz, 3JHH = 6.8 Hz, H7), 5.24 (br, 1
H, NH), 4.69−4.64 (m, 2 H, H6, H8), 2.91−2.63 (m, 8 H, CH2CH3 +
CH2, tmeda), 2.78 (s, 12 H, Me, tmeda), 2.39−2.23 (m, 6 H, CH2CH3
+ CH2, propanamide), 2.01−1.79 (m, 1 H, CH2CH3), 1.78−1.62 (m,
2 H, CH2CH3 + CH2, propanamide), 1.56−1.47 (m, 1 H, CH2,
propanamide), 1.16 (t, 3JHH = 7.6 Hz, 3 H, CH2CH3), 1.11−1.06 (m, 6
3
S
* Supporting Information
Experimental procedures and spectroscopic and analytical data
for 3-(2-bromophenyl)propanamide, 3-(2-bromophenyl)-N-
methylpropanamide, 3-(2-bromophenyl)-N,N-dimethylpropa-
namide, and their iodo analogues. 1H and 13C{1H} NMR
spectra of 2a, 2c, 7a, 14 and 15. Crystallographic data in CIF
format for 1b, 3a, 8a, 9a, 13·CH2Cl2 and 14. Table of
3
H, CH2CH3), 0.98 (t, JHH = 7.6 Hz, 3 H, CH2CH3). 13C{1H} APT
NMR (100.8 MHz, CDCl3): δ 174.5 (CO), 147.6, 146.3, 139.8, 138.2
1902
dx.doi.org/10.1021/om4000192 | Organometallics 2013, 32, 1892−1904

Organometallics
Article
(12) Spencer, J.; Pfeffer, M.; Kyritsakas, N.; Fischer, J. Organo-
metallics 1995, 14, 2214−2224.
crystallographic data. Packing diagrams for 13 and 14. This
material is available free of charge via the Internet at http://
pubs.acs.org.
(13) Spencer, J.; Pfeffer, M.; DeCian, A.; Fischer, J. J. Org. Chem.
1995, 60, 1005−1012.
(14) Vicente, J.; Abad, J.-A.; Shaw, K. F.; Gil-Rubio, J.; Ramírez de
Arellano, M. C.; Jones, P. G. Organometallics 1997, 16, 4557−4566.
AUTHOR INFORMATION
■
́
(15) Benito, M.; Lopez, C.; Morvan, X.; Solans, X.; Font-Bardia, M.
Corresponding Author
*E-mail: jvs1@um.es (J.V.), p.jones@tu-bs.de (P.G.J.).
Dalton Trans. 2000, 4470−4478.
(16) Gul, N.; Nelson, J. H.; Willis, A. C.; Rae, A. D. Organometallics
̈
Notes
2002, 21, 2041−2048. Kelly, A. E.; MacGregor, S. A.; Willis, A. C.;
Nelson, J. H.; Wenger, E. Inorg. Chim. Acta 2003, 352, 79−97.
(17) Vicente, J.; Saura-Llamas, I.; Turpín, J.; Bautista, D.; Ramírez de
Arellano, M. C.; Jones, P. G. Organometallics 2009, 28, 4175−4195.
(18) Maassarani, F.; Pfeffer, M.; Le, B. G. Organometallics 1987, 6,
2043−2053.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank Ministerio de Educacion
(CTQ2007-60808/BQU, CTQ2011-24016) and Fundacion
́
eca (04539/GERM/06) for financial support and a grant
to R.F.P.
́
y Ciencia (Spain), FEDER
́
(19) Dupont, J.; Pfeffer, M.; Theurel, L.; Rotteveel, M. A.; De, C. A.;
Fischer, J. New J. Chem. 1991, 15, 551−558.
Sen
́ ́
(20) Vicente, J.; Abad, J. A.; Lopez-Serrano, J.; Jones, P. G.; Najera,
C.; Botella-Segura, L. Organometallics 2005, 24, 5044−5057.
(21) Albert, J.; Granell, J.; Luque, A.; Font-Bardia, M.; Solans, X.
ez, J.-A.; Oliva-Madrid, M.-
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