Sequential insertion of alkynes and CO or isocyanides into the Pd-C bond of cyclopalladated phenylacetamides. Synthesis of eight-membered palladacycles, benzo[d]azocine-2,4(1 H,3 H)-diones, and highly functionalized acrylonitrile and acrylamide derivatives

Article abstract of DOI:10.1021/om300151n

The cyclopalladated complexes [Pd{κ²C,O-C ₆H₄CH₂C(O)NRR′-2}(tmeda)]TfO [R = R′ = H (1a), R = Me, R′ = H (1b), R = R′ = Me (1c)] react with alkynes XC≡CX′ in 1:3 molar ratio to give the eight-membered palladacycles [Pd{κ²C,O-C(X)C(X′)C₆H ₄CH₂C(O)NRR′-2}(tmeda)]TfO [R = R′ = H and X = X′ = Ph (2aa), CO₂Me (2ab), Et (2ac) or X = Ph, X′ = Me (2ad); R = Me, R′ = H and X = X′ = Ph (2ba), CO₂Me (2bb), Et (2bc) or X = Ph, X′ = Me (2bd); R = R′ = Me and X = X′ = Ph (2ca)]. The treatment of complexes 2aa, 2ac, 2ad, 2ba, 2bc, and 2bd with CO at 50 °C affords the corresponding benzo[d]azocine-2,4(1H,3H)-diones (3), which result from the insertion of a molecule of CO into the Pd-C bond and subsequent C-N reductive coupling and formation of (tmedaH)TfO. The reaction of 2ab with CO in MeOH gives (MeO₂C)₂CC(CO ₂Me)C₆H₄CH₂C(O)NH₂-2 (4ab). Complexes 2aa and 2ab react with 1 equiv of R″NC 1:1 to give [Pd{C(X)C(X′)C₆H₄CH₂C(O)NH ₂-2}(CNR″)(tmeda)]TfO [R″ = t-Bu, X = X′ = Ph (5a), CO₂Me (5b); R = Xy, X = X′ = Ph (5a′), CO₂Me (5b′)]. While 2aa reacts with 1 equiv of R″NC in refluxing CHCl ₃ to give a low yield of the compound XyHNC(O)C(Ph)C(Ph)C ₆H₄CH₂C(O)NH₂-2 (6a) when R″ = Xy, the complex 2aa, 2ba, or 2ca affords the acrylonitrile derivative NCC(Ph)C(Ph)C₆H₄CH₂C(O)NRR′-2 [R = R′ = H (7a), R = Me, R′ = H (7b), R = R′ = Me (7c)] when R″ = t-Bu; alternatively, the latter derivatives can be obtained by refluxing in situ generated solutions of the corresponding cyano complexes [Pd{C(Ph)C(Ph)C₆H₄CH₂C(O)NRR′-2}(CN) (tmeda)] in CHCl₃. The intermediate cyano complex with R = R′ = H (8) has been isolated and characterized. The reactions of 2aa, 2ba, 2ca, and 2ac with 4 equiv of XyNC give [Pd₃(CNXy)₆] and mixtures from which the compounds XyNHC(O)C(Ph)C(Ph)C₆H₄CH ₂CN-2 (9, from 2aa), XyNHC(O)C(Ph)C(Ph)C₆H ₄CH₂C(O)NRR′-2 [R = Me, R′ = H (6b), R = R′ = Me (6c), from 2ba or 2ca, respectively], or [Pd{C(NXy)C(Et)C(Et) C₆H₄CH₂CN-2}Cl(CNXy)₂] (10, from 2ac) can be isolated. The crystal structures of 2aaη2Et₂O, 3aa, 3ac, 8, 9, and 10 have been determined.

Full text of DOI:10.1021/om300151n

Article
pubs.acs.org/Organometallics
Sequential Insertion of Alkynes and CO or Isocyanides into the Pd−C
Bond of Cyclopalladated Phenylacetamides. Synthesis of Eight-
Membered Palladacycles, Benzo[d]azocine-2,4(1H,3H)-diones, and
Highly Functionalized Acrylonitrile and Acrylamide Derivatives
Roberto Frutos-Pedreno, Pablo Gonzalez-Herrero,* and Jose Vicente*
́
́
̃
Grupo de Química Organometal
4021, 30071 Murcia, Spain
́
ica, Departamento de Química Inorgan
́
ica, Facultad de Química, Universidad de Murcia, Apartado
Peter G. Jones
Institut fur Anorganische und Analytische Chemie, Technische Universitat Braunschweig, Postfach 3329, 38023 Braunschweig,
̈
̈
Germany
S
* Supporting Information
ABSTRACT: The cyclopalladated complexes [Pd{κ2C,O-
C6H4CH2C(O)NRR′-2}(tmeda)]TfO [R = R′ = H (1a), R =
Me, R′ = H (1b), R = R′ = Me (1c)] react with alkynes XC
CX′ in 1:3 molar ratio to give the eight-membered pallada-
cycles [Pd{κ2C,O-C(X)C(X′)C6H4CH2C(O)NRR′-2}-
(tmeda)]TfO [R = R′ = H and X = X′ = Ph (2aa), CO2Me
(2ab), Et (2ac) or X = Ph, X′ = Me (2ad); R = Me, R′ = H and
X = X′ = Ph (2ba), CO2Me (2bb), Et (2bc) or X = Ph, X′ =
Me (2bd); R = R′ = Me and X = X′ = Ph (2ca)]. The
treatment of complexes 2aa, 2ac, 2ad, 2ba, 2bc, and 2bd with CO at 50 °C affords the corresponding benzo[d]azocine-
2,4(1H,3H)-diones (3), which result from the insertion of a molecule of CO into the Pd−C bond and subsequent C−N
reductive coupling and formation of (tmedaH)TfO. The reaction of 2ab with CO in MeOH gives (MeO2C)2C
C(CO2Me)C6H4CH2C(O)NH2-2 (4ab). Complexes 2aa and 2ab react with 1 equiv of R″NC 1:1 to give [Pd{C(X)
C(X′)C6H4CH2C(O)NH2-2}(CNR″)(tmeda)]TfO [R″ = t-Bu, X = X′ = Ph (5a), CO2Me (5b); R = Xy, X = X′ = Ph (5a′),
CO2Me (5b′)]. While 2aa reacts with 1 equiv of R″NC in refluxing CHCl3 to give a low yield of the compound
XyHNC(O)C(Ph)C(Ph)C6H4CH2C(O)NH2-2 (6a) when R″ = Xy, the complex 2aa, 2ba, or 2ca affords the acrylonitrile
derivative NCC(Ph)C(Ph)C6H4CH2C(O)NRR′-2 [R = R′ = H (7a), R = Me, R′ = H (7b), R = R′ = Me (7c)] when R″ = t-
Bu; alternatively, the latter derivatives can be obtained by refluxing in situ generated solutions of the corresponding cyano
complexes [Pd{C(Ph)C(Ph)C6H4CH2C(O)NRR′-2}(CN)(tmeda)] in CHCl3. The intermediate cyano complex with R = R′
= H (8) has been isolated and characterized. The reactions of 2aa, 2ba, 2ca, and 2ac with 4 equiv of XyNC give [Pd3(CNXy)6]
and mixtures from which the compounds XyNHC(O)C(Ph)C(Ph)C6H4CH2CN-2 (9, from 2aa), XyNHC(O)C(Ph)
C(Ph)C6H4CH2C(O)NRR′-2 [R = Me, R′ = H (6b), R = R′ = Me (6c), from 2ba or 2ca, respectively], or [Pd{C(
NXy)C(Et)C(Et)C6H4CH2CN-2}Cl(CNXy)2] (10, from 2ac) can be isolated. The crystal structures of 2aa·2Et2O, 3aa, 3ac,
8, 9, and 10 have been determined.
cyclizations of aryl or vinyl halides with alkynes, which are very
useful in heterocyclic synthesis.6
INTRODUCTION
■
Palladacycles constitute an extraordinarily important class of
organometallic compounds because of their participation in
numerous palladium-mediated organic transformations.1 The
Pd−C bond in these compounds shows a rich reactivity toward
unsaturated molecules that has been widely exploited for both
stoichiometric and catalytic syntheses. In particular, the
insertion of alkynes has been used for the synthesis of enlarged
palladacycles, which, in many cases, lead to the formation of
interesting carbocycles and heterocycles after depalladation.2−5
This reaction sequence is the basis of palladium-catalyzed
Medium-size heterocycles (8- to 11-membered) are found in
numerous compounds of great biological or medicinal
relevance.7 These rings are difficult to prepare because of
adverse enthalpic and entropic factors,8 and therefore the
development of efficient methods for their synthesis remains an
active research area.9 Our research group has recently reported
the synthesis of a series of eight-membered palladacycles
Received: February 24, 2012
Published: April 3, 2012
© 2012 American Chemical Society
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derived from the insertion of olefins into the Pd−C bond of
ortho-palladated phenethylamines, which can be employed for
the synthesis of eight-membered cyclic amidines via the
insertion of isonitriles and subsequent depalladation.10 We
have also shown that the six-membered cationic palladacycles
[Pd{κ2C,O-C6H4CH2C(O)NRR′-2}(tmeda)]TfO [R = R′ = H
(1a), R = Me, R′ = H (1b), R = R′ = Me (1c)] undergo C−N
and/or C−O reductive couplings after the insertion of CO into
the Pd−C bond, leading to isoquinoline (A) and/or
isocoumarin (B) derivatives (Scheme 1).11 The fact that
palladacycles [Pd{κ2C,O-C(X)C(X′)C6H4CH2C(O)NRR′-
2}(tmeda)]TfO [R = R′ = H and X = X′ = Ph (2aa),
CO2Me (2ab), Et (2ac) or X = Ph, X′ = Me (2ad); R = Me, R′
= H and X = X′ = Ph (2ba), CO2Me (2bb), Et (2bc) or X =
Ph, X′ = Me (2bd); R = R′ = Me and X = X′ = Ph (2ca)],
resulting from the insertion of one molecule of the alkyne into
the Pd−C bond (Scheme 2). We formulate these complexes
assuming that the alkyne substituents are mutually cis because
this is the geometry in all similar complexes3,4,23 and was
confirmed by the X-ray crystal structure of 2aa·2Et2O (see
below). These relatively easy insertions are certainly favored by
the cationic nature of the precursors 1a−c and the lability of
the Pd−O bond, which facilitates the necessary alkyne
coordination step. Multiple-insertion products were not
observed in any of the cases, which is surprising if we consider
that the large size of palladacycles 2 should facilitate the ring-
opening and the coordination of additional alkyne molecules.
Compounds 2ad and 2bd are the expected major regioisomers
resulting from the insertion of 1-phenylpropyne, in agreement
with the observed reaction pattern for the insertions of
dissymmetric internal alkynes, which favors the isomer with
the more sterically demanding substituent on the carbon atom
next to the metal;15 the regiochemistry of this insertion was
Scheme 1
1
confirmed by means of H/13C heteronuclear multiple-bond
correlation (HMBC) experiments.
The IR spectra of the cyclopalladated complexes 2 show the
ν(CO) band arising from the amide function at around 1660
(2aa−d), 1615 (2ba−d), or 1590 (2ca) cm−1, which
approximately match the frequencies observed for the
corresponding precursors 1a−c.11 This indicates that in all
cases the amide remains coordinated through the oxygen atom.
1
The room-temperature H NMR spectra show the resonances
of the methylenic protons as an AB system, which indicates
that, at this temperature, there are no conformational equilibria
making them equivalent; this is attributable to the restrictions
imposed by the planar vinyl, amide, and arylene groups.
Reactions with CO. Synthesis of Benzo[d]azocine-
2,4(1H,3H)-diones. The derivatives 2aa, 2ac, 2ad, 2ba, 2bc,
and 2bd reacted with CO (1.4 bar) at 50 °C in CHCl3 to give
colloidal Pd, (tmedaH)TfO, and the corresponding benzo[d]-
azocine-2,4(1H,3H)-diones 3 (Scheme 2), which result from an
insertion/C−N reductive coupling sequence. The NH2
derivatives required shorter reaction times (5 h) and led to
higher yields (78−94%) than the NHMe derivatives (24 h, 57−
71%). No C−O coupling products were detected in any of the
cases. The NMe2 derivative 2ca was recovered unreacted after
70 h under the same reaction conditions. As observed for
these couplings take place under very mild conditions
prompted us to examine their suitability for the synthesis of
heterocycles of a larger size. For this purpose, ring enlargement
through the insertion of alkynes prior to the treatment with CO
appeared to be a promising option. In this article, we report the
synthesis of a series of eight-membered palladacycles derived
from alkyne monoinsertions into the Pd−C bond of 1a−c and
a systematic study of their reactivity toward CO or isocyanides,
which afforded benzo[d]azocine-2,4(1H,3H)-diones (C), be-
longing to a new family of the small group of eight-membered
cyclic imides12,13 or, respectively, highly functionalized
acrylamides (D) or acrylonitriles (E).
1
complexes 2, the H NMR data of compounds 3 indicate that
the methylenic protons do not interconvert at room temper-
ature.
Possible intermediates in the formation of compounds 3 are
depicted in Scheme 2. The insertion of CO into the Pd−C
bond of complexes 2 could give the nine-membered pallada-
cycle A, in equilibrium with the amidate B. The latter could
undergo a C−N reductive coupling to give compounds 3, and
the displaced tmeda ligand should be taken up by the HTfO
formed in the A ⇆ B equilibrium. The fact that the NHMe
derivatives require longer reaction times and lead to lower
yields can be explained on the basis of the steric repulsion of
the methyl substituent, which makes the C−N coupling slower.
This is in agreement with our previous report on the C−N
coupling processes that take place after insertion of CO into the
Pd−C bond of the iodo(aryl) complexes [Pd{C6H4(CH2C-
RESULTS AND DISCUSSION
■
Alkyne Monoinsertion Reactions. Synthesis of Eight-
Membered Palladacycles. The reactions of the cyclo-
palladated complexes [Pd{κ2C,O-C6H4CH2C(O)NRR′-2}-
(tmeda)]TfO [NRR′ = NH2 (1a), NHMe (1b), NMe2 (1c)]
with various alkynes XCCX′ in 1:3 molar ratio at room
temperature afforded high yields of the eight-membered
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Scheme 2
Scheme 3
(O)NRR′)-2}I(tmeda)] (R = H, Me; R′ = H)11 and also with
the general observation that palladium-catalyzed intermolecular
amidations of aryl halides that proceed through amidate
intermediates are considerably slower when acyclic secondary
amides are used instead of primary amides.16 The fact that no
C−O reductive couplings are observed suggests that the
required nine-membered aminoenlolate intermediate C is
either formed in minute amounts, because it transforms quickly
into B, or not formed at all.
The complexes with inserted dimethyl acetylene dicarbox-
ylate (DMAD) 2ab and 2bb reacted with CO in CHCl3 at
room temperature but gave mixtures of compounds in which
the corresponding benzazocines 3 could not be identified,
which means that the required C−N reductive coupling is
hindered for the DMAD derivatives. When the reaction of 2ab
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with CO was carried out in MeOH, the product (MeO2C)2C
C(CO2Me)C6H4CH2C(O)NH2-2 (4), resulting from the
methanolysis of the acyl palladium intermediate (Scheme 2),
was obtained as the sole product, although it could be isolated
with only a moderate yield (42%).
In the case of 9, the process is accompanied by the dehydration
of the unsubstituted carbamoyl group to give a nitrile, which
takes place even in the presence of added water. The
dehydration of primary amides to give nitriles is a functional
group transformation of great importance in organic synthesis.
Conventional procedures employ powerful dehydration
reagents under energetic reaction conditions.20 However,
several methods have been developed that make use of
transition-metal compounds as catalysts under milder con-
ditions.21 Of particular relevance to our results is the finding
that PdCl2, [PdCl2(NCMe)2], or Pd(OAc)2 catalyzes at room
temperature the dehydration of a series of primary amides in
aqueous acetonitrile.22 The existence of this precedent and the
mild conditions required for the formation of 9 suggest that the
dehydration step leading to this compound is mediated by
some Pd species whose nature cannot be precisely established
at present. Notably, the reaction does not require the use of a
water/acetonitrile mixture as the solvent. In order to gain
insight into this process, we carried out the 1:4 reaction of
complex 2ac with XyNC in dry CH2Cl2, which also produced
[Pd3(CNXy)6] and (tmedaH)TfO. After separation of these
two products, a mixture was obtained from which a small
amount of a microcrystalline solid could be isolated. An X-ray
diffraction study revealed that this compound is [Pd{C(
NXy)C(Et)C(Et)C6H4CH2CN-2}Cl(CNXy)2] (10), con-
taining two mutually trans XyNC ligands, one chloro ligand,
and an iminoacyl ligand resulting from the insertion of a XyNC
molecule and the dehydration of the carbamoyl group. Apart
from the fact that the chloro ligand must have originated from
the reaction of some intermediate Pd complex with the solvent,
the formation of 10 showed that the dehydration of the
carbamoyl group and the hydrolysis of the iminoacyl ligand can
take place independently.
Reactions with Isonitriles. The reactions of complex 2aa
or 2ab with XyNC or t-BuNC in a molar ratio of 1:1 at room
temperature in CHCl3 led to the formation of [Pd{C(X)
C(X′)C6H4CH2C(O)NH2-2}(CNR″)(tmeda)]TfO [R″ = t-Bu
and X = X′ = Ph (5a), CO2Me (5b); R″ = Xy and X = X′ = Ph
(5a′), CO2Me (5b′)], which result from the displacement of the
coordinated oxygen atom by the isonitrile (Scheme 3).
Complexes 5a, 5b, and 5b′ are sufficiently stable not to
undergo subsequent reactions at room temperature. However,
complex 5a′ was obtained along with decomposition products
and could not be purified. The 1:1 reaction of 2aa with XyNC
at reflux temperature in CHCl3 gave a precipitate of Pd metal
and a mixture containing the acrylamide derivative XyHNC-
(O)C(Ph)C(Ph)C6H4CH2C(O)NH2-2 (6a), which could
be isolated in 24% yield. This result indicates that, although the
insertion of the isocyanide takes place, the formation of an
amidate intermediate analogous to A (Scheme 2) and/or the
subsequent C−N reductive coupling are not favored and that
the hydrolysis of the iminoacyl ligand by residual water takes
place instead. Under the same reaction conditions, 2aa, 2ba, or
2ca and t-BuNC led to the precipitation of Pd(0) and the
formation of the acrylonitrile derivatives NCC(Ph)C(Ph)-
C6H4CH2C(O)NRR′-2 [R = R′ = H (7a); R = Me, R′ = H
(7b); R = R′ = Me (7c)], with the concomitant formation of
isobutene and (tmedaH)TfO (Scheme 3). Several unidentified
decomposition products also formed, and only 7a and 7c could
be isolated in pure form from these reactions (55% or 29%
yield, respectively). Compounds 7 apparently resulted from the
C−C reductive coupling of a cyano(vinyl) palladium complex
that could have formed after the dealkylation of the coordinated
t-BuNC ligand in the corresponding complexes 5 (Scheme 3).
There are numerous examples of t-BuNC ligand dealkylation
reactions, which have been found to be relatively easy if the
complex is cationic or the metal ion is in a high oxidation
state.17 Although we have not found any precedent involving a
Pd complex, the cationic nature of the intermediate complexes
5 may facilitate this process. On the other hand, the coupling of
cyanide and vinyl ligands in the coordination sphere of Pd(II)
has been proposed as the last step in the mechanism of the Pd-
catalyzed arylcyanation of internal alkynes.18 To further support
this reaction path, we prepared the cyano complex [Pd{C-
(Ph)C(Ph)C6H4CH2C(O)NH2-2}(CN)(tmeda)] (8) from
2aa and KCN and refluxed it in CHCl3 solution for 15 h, which
afforded a precipitate of Pd(0) and compound 7a in 61%
isolated yield. Similar yields of derivatives 7b and 7c were
obtained by refluxing in situ generated solutions of the
corresponding cyano complexes in CHCl3.
Crystal Structures. The crystal structure of complex 2aa
(Figure 1) was determined as a diethyl ether disolvate. It shows
that the diphenylacetylene molecule has inserted in a syn
fashion, as is usually the case for alkyne monoinsertions,3,4,23
When 1:4 molar ratios were employed, the reactions of 2aa,
2ba, and 2ca with XyNC at room temperature in CH2Cl2 or
acetone afforded dark red solutions containing the Pd(0)
complex [Pd3(CNXy)6],19 which was identified by its 1H NMR
spectrum. The other reaction products were (tmedaH)TfO and
the acrylamide derivatives XyHNC(O)C(Ph)C(Ph)-
C6H4CH2CN-2 (9, from 2aa) or XyHNC(O)C(Ph)C(Ph)-
C6H4CH2C(O)NRR′-2 [NRR′ = NHMe (6b), NMe2 (6c),
from 2ba or 2ca, respectively]. These compounds result from
the insertion of an XyNC molecule into the Pd−C bond and
the subsequent hydrolysis of the resulting iminoacyl complex.
Figure 1. Thermal ellipsoid plot (30% probability) of the cation of
complex 2aa. Selected bond distances (Å) and angles (deg): Pd−C(4)
1.9930(16), Pd−O(1) 2.0682(11), Pd−N(2) 2.0771(14), Pd−N(3)
2.1874(14), O(1)−C(2) 1.250(2), N(1)−C(2) 1.316(2), C(3)−C(4)
1.338(2), C(3)−C(12) 1.507(2); C(4)−Pd−O(1) 94.00(6), C(4)−
Pd−N(2) 94.26(6), O(1)−Pd−N(3) 87.92(5), N(2)−Pd−N(3)
84.58(5), C(2)−O(1)−Pd 135.22(11), O(1)−C(2)−N(1)
119.42(16), O(1)−C(2)−C(1) 123.39(15), N(1)−C(2)−C(1)
117.19(15).
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and confirms that the amide group remains coordinated to the
Pd through the oxygen. The conformation of the resulting
eight-membered ring is similar to that found in the urea
derivative [Pd{κ2C,O-C(Ph)C(Ph)C6H4NHC(O)NHTo-2}-
(tmeda)]TfO24 (To = p-tolyl) and can be approximately
described as twist boat, although the usual designations of
cyclooctane conformations25 are not strictly applicable. The
coordination environment around the Pd center is distorted
square planar, the main distortions arising from the small bite
angle of the tmeda ligand, leading to an N(2)−Pd−N(3) angle
of 84.58(5)°, and the strain caused by the eight-membered
cycle, leading to a C(4)−Pd−O(1) angle of 94.00(6)°. The
Pd−C(4) bond distance of 1.9930(16) Å is typical of
vinylpalladium complexes.4,5,24,26 The Pd−O(1) distance of
2.0682(11) Å is slightly longer than that found in the six-
membered palladacycle [Pd{κ2C,O-C6H4(CH2C(O)NHMe)-
2}(dbbpy)]TfO (2.031 Å; dbbpy = 4,4′-di-tert-butyl-2,2′-
bipyridyl).11 The NH2 group forms two N−H···O hydrogen
bonds, one of them to one of the diethyl ether molecules and
the other to an oxygen atom of the triflate anion.
Figure 3. Thermal ellipsoid plot (50% probability) of compound 3ac.
Selected bond distances (Å) and angles (deg): C(2)−O(1)
1.2161(13), C(2)−N(3) 1.3952(15), N(3)−C(4) 1.3835(14),
C(4)−O(2) 1.2289(14), C(4)−C(5) 1.5042(15), C(5)−C(6)
1.3446(16); C(2)−C(1)−C(10A) 108.40(9), O(1)−C(2)−N(3)
117.82(10), O(1)−C(2)−C(1) 122.39(10), N(3)−C(2)−C(1)
119.61(9), C(4)−N(3)−C(2) 134.79(10), O(2)−C(4)−N(3)
117.18(10), O(2)−C(4)−C(5) 118.38(10), N(3)−C(4)−C(5)
124.20(10), C(6)−C(5)−C(4) 123.09(10), C(5)−C(6)−C(6A)
121.36(10).
The X-ray diffraction analyses of 3aa and 3ac revealed very
similar structures (Figures 2 and 3, respectively). The eight-
atoms gave 56 hits and an average C−N−C angle of 128.4°.
Both 3aa and 3ac form inversion-related dimers through
hydrogen bonds N(3)−H(03)···O(1)#1 and N(3)−
H(03)···O(2)#1, respectively.
The crystal structure of complex 8 (Figure 4) shows a slightly
distorted square-planar coordination around the Pd atom (the
donor atoms of the ligands lie alternately 0.12 Å out of the
mean plane). The vinyl moiety defines a planar group including
the Pd and the three connected C atoms from the aromatic
rings (mean deviation from plane Pd−C(1)−C(11)−C(2)−
C(21)−C(31), 0.02 Å), which forms an angle of 71.2° with the
mean Pd coordination plane. The Pd−C(1) bond distance of
2.0092(11) Å is similar to the corresponding distance found in
2aa. The two H atoms of the NH2 group are involved in N−
H···N hydrogen bonds with the cyano group, one of them
intramolecular and the other with an inversion-related
molecule, resulting in a pairing of molecules via a central ring
[(NH2)2···(Ncyano)2] of graph set R24(8).
The molecular structure of 9 is shown in Figure 5. The
conformation adopted by this compound in the crystal appears
to be dictated by the formation of an intramolecular N−H···N
hydrogen bond between the NHXy and cyano groups.
The crystal structure of 10 (Figure 6) shows an almost
perfect square-planar coordination around the Pd atom. The
iminoacyl group is practically planar (mean deviation from
plane C(1)−C(10)−N(1)−Pd, 0.01 Å) and forms an angle of
61.0° with the mean Pd coordination plane. The Pd−C(10)
bond distance of 2.040(2) Å is similar to that found for other
iminoacyl Pd complexes in an analogous coordination environ-
ment.11,27
Figure 2. Thermal ellipsoid plot (50% probability) of compound 3aa.
Selected bond distances (Å) and angles (deg): Pd−C(4) 1.9930(16),
Pd−O(1) 2.0682(11), Pd−N(2) 2.0771(14), Pd−N(3) 2.1874(14),
O(1)−C(2) 1.250(2), N(1)−C(2) 1.316(2), C(3)−C(4) 1.338(2),
C(3)−C(12) 1.507(2); C(4)−Pd−O(1) 94.00(6), C(4)−Pd−N(2)
94.26(6), O(1)−Pd−N(3) 87.92(5), N(2)−Pd−N(3) 84.58(5),
C(2)−O(1)−Pd 135.22(11), O(1)−C(2)−N(1) 119.42(16), O(1)−
C(2)−C(1) 123.39(15), N(1)−C(2)−C(1) 117.19(15), C(4)−
C(3)−C(21) 125.70(15), C(4)−C(3)−C(12) 118.06(15), C(21)−
C(3)−C(12) 116.13(14), C(3)−C(4)−C(31) 127.76(15), C(3)−
C(4)−Pd 116.75(12), C(31)−C(4)−Pd 115.36(11), C(2)−N(3)−
C(4) 130.87(11).
membered ring exhibits a folded conformation imposed by the
constraints of the planar imide, ethylene, and benzene groups.
The bond lengths and angles are normal except for the wide
C(2)−N(3)−C(4) angle of 130.87(11)° (3aa) or 134.79(10)°
(3ac), which may be associated with the ring strain. There is
only one precedent of a crystal structure of an eight-membered
cyclic imide, which shows a C−N−C angle of 135.13°.12
A
CONCLUSION
■
search of the Cambridge Database for the grouping C−CO−
NH−CO−C in acyclic systems or rings with more than six
The cationic cyclopalladated phenylacetamides [Pd{κ2C,O-
C6H4CH2C(O)NRR′-2}(tmeda)]TfO (NRR′ = NH2, NHMe,
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Figure 6. Thermal ellipsoid plot (30% probability) of complex 10.
Selected bond distances (Å) and angles (deg): Pd−C(40) 1.976(2),
Pd−C(30) 2.000(3), Pd−C(10) 2.040(2), Pd−Cl 2.4214(6), N(1)−
C(10) 1.258(3), N(2)−C(8) 1.122(6), C(1)−C(2) 1.340(4), C(1)−
C(10) 1.496(3), C(40)−Pd−C(10) 88.64(9), C(30)−Pd−C(10)
91.85(10), C(40)−Pd−Cl 89.32(7), C(30)−Pd−Cl 90.17(8),
N(1)−C(10)−C(1) 119.2(2), N(1)−C(10)−Pd 125.47(18), C(1)−
C(10)−Pd 115.18(17), N(2)−C(8)−C(7) 178.0(6).
Figure 4. Thermal ellipsoid plot (50% probability) of complex 8.
Selected bond distances (Å) and angles (deg): Pd−C(5) 1.9576(12),
Pd−C(1) 2.0092(11), Pd−N(2) 2.1398(10), Pd−N(1) 2.1678(10),
O−C(4) 1.2301(15), N(3)−C(5) 1.1513(16), N(4)−C(4)
1.3304(16), C(1)−C(2) 1.3499(16), C(3)−C(4) 1.5216(16);
C(5)−Pd−C(1) 86.54(5), C(1)−Pd−N(2) 96.11(4), C(5)−Pd−
N(1) 94.60(4), N(2)−Pd−N(1) 83.57(4), C(2)−C(1)−C(11)
124.34(10), C(1)−C(2)−C(21) 121.22(10), O−C(4)−N(4)
122.99(12), N(3)−C(5)−Pd 175.94(11).
nature depends on the reaction conditions and the isocyanide.
Thus, the 1:1 reactions with XyNC or t-BuNC at room
temperature lead to the isocyanide coordination products
[Pd{C(X)C(X′)C6H4CH2C(O)NH2-2}(CNR)(tmeda)]-
TfO, which at higher temperatures may undergo insertion of
the isocyanide ligand into the Pd−C bond and subsequent
hydrolysis to give acyclic acrylamide derivatives (R = Xy), or
the dealkylation of the isocyanide (R = t-Bu) and the C−C
reductive coupling of a cyano(vinyl) palladium intermediate to
give acrylonitrile derivatives. The 1:4 reactions with XyNC at
room temperature gave [Pd3(CNXy)6] and moderate yields of
acyclic N-xylyl acrylamides resulting from the insertion of a
XyNC molecule into the Pd−C bond and the subsequent
hydrolysis of an iminoacyl intermediate; in addition, the
dehydration of the unsubstituted carbamoyl group takes place,
which constitutes a rare example of primary amide dehydration
under exceptionally mild conditions.
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. The complexes [Pd{κ2C,O-
C6H4CH2C(O)NRR′-2}(tmeda)]TfO were prepared as previously
described.11 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 usually at 298 K, unless
otherwise indicated. Chemical shifts are referenced to internal TMS.
The assignments of the 1H and 13C{1H} 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 a Carlo Erba 1106 microanalyzer. Infrared spectra
were recorded in the range 4000−200 cm−1 on a Perkin-Elmer
Spectrum 100 spectrophotometer using Nujol mulls between
polyethylene sheets. High-resolution ESI mass spectra were recorded
on an Agilent 6220 Accurate-Mass TOF LC/MS.
Figure 5. Thermal ellipsoid plot (50% probability) of compound 9.
Selected bond distances (Å) and angles (deg): C(1)−C(2)
1.3416(15), C(2)−C(3) 1.5105(15), C(3)−O(1) 1.2251(13),
C(3)−N(1) 1.3572(14), C(18)−N(2) 1.1391(15), C(41)−N(1)
1.4379(13); C(2)−C(1)−C(11) 122.19(9), C(1)−C(2)−C(3)
121.46(9), O(1)−C(3)−N(1) 123.18(10), O(1)−C(3)−C(2)
121.25(10), N(1)−C(3)−C(2) 115.53(9), N(2)−C(18)−C(17)
177.07(13), C(3)−N(1)−C(41) 122.50(9), O(1)−C(3)−N(1)
123.18(10).
NMe2) undergo alkyne monoinsertion reactions to give eight-
membered palladacycles of the type [Pd{κ2C,O-C(X)C(X′)-
C6H4CH2C(O)NRR′-2}(tmeda)]TfO, whose reactivity toward
CO and isocyanides has been systematically studied. With the
exceptions of those containing inserted DMAD, the NH2 and
NHMe derivatives react with CO to give unprecedented
benzo[d]azocine-2,4(1H,3H)-diones in moderate to high
yields, which result from CO insertion into the Pd−C bond
and subsequent C−N reductive coupling. In contrast, the
analogous reactions with isocyanides do not afford eight-
membered heterocycles, but a series of diverse products whose
X-ray Structure Determinations. Crystals suitable for X-ray
diffraction studies were obtained by liquid−liquid diffusion from
CDCl3/Et2O (2aa·2Et2O), CDCl3/n-pentane (3aa), or CH2Cl2/n-
pentane (8, 9, and 10) or by sublimation at low pressure (3ac).
Numerical details are presented in Table 1. The data for 3aa, 3ac, and
10 were collected on an Oxford Diffraction Nova diffractometer using
mirror-focused Cu Kα radiation in ω-scan mode. The data for
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Table 1. Crystallographic Data for 2aa·2Et2O, 3aa, 3ac, 8, 9, and 10
2aa·2Et2O
3aa
3ac
8
9
10
formula
fw
C37H54F3N3O6PdS
832.29
C23H17NO2
339.38
C15H17NO2
243.30
C29H34N4OPd
561.00
C31H26N2O
442.54
C41H43ClN4Pd
733.64
T (K)
150(2)
100(2)
100(2)
1.54184
monoclinic
P21/n
100(2)
100(2)
0.71073
monoclinic
P21/c
150(2)
1.54184
monoclinic
P21/n
λ (Å)
0.71073
1.54184
triclinic
0.71073
triclinic
cryst syst
space group
a (Å)
triclinic
P1
̅
P1
̅
P1
̅
10.0071(3)
11.2824(3)
19.3538(6)
78.416(4)
82.150(4)
72.009(4)
2029.42(10)
2
8.7948(11)
9.8117(10)
11.3509(13)
104.998(10)
103.082(10)
104.619(10)
869.78(17)
2
11.1524(4)
10.1077(4)
11.2671(4)
90
8.3426(2)
9.7460(3)
17.8648(4)
81.605(3)
83.119(3)
74.056(3)
1376.84(6)
2
15.4806(5)
8.6812(3)
18.5378(6)
90
11.2983(4)
8.6519(3)
37.1625(12)
90
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
V (Å3)
Z
91.129(4)
90
106.395(4)
90
97.241(4)
90
1269.84(8)
4
2390.00(14)
4
3603.7(2)
4
ρcalcd (Mg m−3
)
1.362
1.296
1.273
1.353
1.230
1.352
μ (mm−1
)
0.568
0.658
0.674
0.701
0.074
5.089
a
R1
0.0267
0.0398
0.0352
0.0188
0.0368
0.0346
b
wR2
0.0676
0.1110
0.0909
0.0493
0.0867
0.0875
a
b
2
R1 = ∑||Fo| − |Fc||/∑|Fo| for reflections with I > 2σ(I). wR2 = [∑[w(Fo2 − Fc2)2]/∑[w(Fo )2]0.5 for all reflections; w−1 = σ2(F2) + (aP)2 + bP,
where P = (2Fc2 + Fo )/3 and a and b are constants set by the program.
2
2aa·2Et2O, 8, and 9 were collected on an Oxford Diffraction Xcalibur
diffractometer using monochromated Mo Kα radiation in ω-scan
mode. The measurement temperature was 100 K for all structures
except 2aa·2Et2O and 10, crystals of which shattered at 100 K
(presumably because of a phase transition) and were therefore
measured at 150 K. Absorption corrections were based on multiscans
except for 9, for which no correction was applied. The structures were
solved by direct methods and refined anisotropically on F2 using the
64.0 (CH2, tmeda), 56.9 (CH2, tmeda), 53.2 (Me, tmeda), 49.3 (Me,
tmeda), 48.8 (Me, tmeda), 45.0 (Me, tmeda), 38.3 (CH2, acetamide).
2ab. Yield: 83%. Anal. Calcd for C21H30F3N3O8PdS: C, 38.93; H,
4.67; N, 6.48; S, 4.95. Found: C, 39.07; H, 4.96; N, 6.57; S, 4.84. Mp:
197−200 °C (dec). IR (Nujol, cm−1): ν(NH), 3408, 3319, 3248,
3150; ν(CO), 1708, 1660. 1H NMR (400.9 MHz, CDCl3): δ 8.43 (s, 1
H, NH), 7.52−7.40 (m, 4 H, Ar), 7.32 (s, 1 H, NH), 3.87 (A part of
2
AB system, JHH = 16.0 Hz, 1 H, CH2, acetamide), 3.84 (s, 3 H,
program SHELXL-97 (G. M. Sheldrick, University of Gottingen).14
CO2Me), 3.65 (s, 3 H, CO2Me), 3.51 (B part of AB system, 1 H, CH2,
acetamide), 2.82 (s, 3 H, Me, tmeda), 2.70 (m, 1 H, CH2, tmeda),
2.60−2.53 (m, 4 H, CH2 + Me, tmeda), 2.36 (s, 3 H, Me, tmeda), 2.27
(m, 1 H, CH2, tmeda), 2.16 (m, 1 H, CH2, tmeda), 1.75 (s, 3 H, Me,
tmeda). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 179.3
(CONH2), 171.6 (CO2Me), 163.5 (CPd), 161.0 (CO2Me), 140.8
(C, Ar), 133.3 (C, Ar), 133.0 (PdCCCO2Me), 131.0 (CH, Ar),
129.1 (CH, Ar), 128.4 (CH, Ar), 127.7 (CH, Ar), 64.7 (CH2, tmeda),
57.7 (CH2, tmeda), 54.1 (Me, tmeda), 52.16 (CO2Me), 52.07
(CO2Me), 49.2 (Me, tmeda), 49.1 (Me, tmeda), 45.7 (Me, tmeda),
38.3 (CH2, acetamide).
̈
Treatment of hydrogen atoms is as follows: NH freely refined (for 8
with N−H distance restraints), methyls as rigid groups allowed to
rotated but not tip, other H using a riding model starting from
calculated positions. Special features of refinement: The triflate group of
2aa is slightly disordered (minor component ca. 8%); appropriate
similarity restraints were employed to improve refinement stability, but
dimensions of disordered groups should always be interpreted with
caution.
Synthesis of [Pd{κ2C,O-C(X)C(X′)C6H4CH2C(O)NRR′-2}-
(tmeda)]TfO [R = R′ = H and X = X′ = Ph (2aa), CO2Me (2ab),
Et (2ac) or X = Ph, X′ = Me (2ad); R = Me, R′ = H and X = X′ =
Ph (2ba), CO2Me (2bb), Et (2bc) or X = Ph, X′ = Me (2bd); R = R′
= Me and X = X′ = Ph (2ca)]. A mixture of the appropriate complex
[Pd{κ2C,O-C6H4CH2C(O)NRR′2-2}(tmeda)]TfO (0.15 mmol) and
the alkyne (0.45 mmol) in CH2Cl2 (25 mL) was stirred for 9 h and
then filtered through anhydrous MgSO4. Partial evaporation of the
filtrate (1 mL) and addition of Et2O (20 mL) led to the precipitation
of the corresponding complex 2 as a yellow solid, which was filtered
off, washed with Et2O (3 × 3 mL), and vacuum-dried.
2ac. Yield: 82%. Anal. Calcd for C21H34F3N3O4PdS: C, 42.90; H,
5.83; N, 7.15; S, 5.45. Found: C, 42.60; H, 5.90; N, 7.06; S, 5.35. Mp:
154−155 °C. IR (Nujol, cm−1): ν(NH), 3350, 3197; ν(CO), 1664. 1H
NMR (400.9 MHz, CDCl3): δ 8.35 (br s, 1 H, NH), 7.41−7.24 (m, 4
H, Ar), 6.58 (br s, 1 H, NH), 3.75, 3.63 (AB system, 2JHH = 15.2 Hz, 2
H, CH2, acetamide), 2.68 (s, 3 H, Me, tmeda), 2.50−2.27 (m, 9 H,
CH2, Me, tmeda + CH2CH3), 2.14−2.06 (m, 1 H, CH2, tmeda), 2.02,
2
3
1.89 (AB part of ABX3 system, JHH = 14.6 Hz, JHH = 7.6 Hz, 2 H,
3
CH2CH3), 1.68 (s, 3 H, Me, tmeda), 1.19 (t, JHH = 7.6 Hz, 3 H,
CH2CH3), 0.87 (t, 3JHH = 7.6 Hz, 3 H, CH2CH3). 13C{1H} APT NMR
(100.8 MHz, CDCl3): δ 179.8 (CO), 147.2 (CC), 144.7 (C, Ar),
135.8 (CC), 133.6 (C, Ar), 130.7 (CH, Ar), 128.4 (CH, Ar), 127.2
(CH, Ar), 126.6 (CH, Ar), 63.7 (CH2, tmeda), 56.6 (CH2, tmeda),
52.6 (Me, tmeda), 51.3 (Me, tmeda), 47.4 (Me, tmeda), 45.9 (Me,
tmeda), 38.7 (CH2, acetamide), 26.4, 26.3 (CH2CH3), 14.7, 13.4
(CH2CH3).
2aa. Yield: 91%. Anal. Calcd for C29H34F3N3O4PdS: C, 50.92; H,
5.01; N, 6.14; S, 4.69. Found: C, 50.58; H, 5.21; N, 6.14; S, 4.48. Mp:
123−125 °C. IR (Nujol, cm−1): ν(NH), 3345, 3193; ν(CO), 1667. 1H
3
NMR (400.9 MHz, CDCl3): δ 8.06 (br s, 1 H, NH), 7.76 (d, JHH
=
7.6 Hz, 1 H, Ar), 7.57 (m, 1 H, Ar), 7.40−7.32 (m, 4 H, Ar + Ph),
7.23−7.19 (m, 3 H, Ph), 7.07−6.98 (m, 5 H, Ph), 6.96 (br s, 1 H,
2
NH), 3.69, 3.58 (AB system, JHH = 16.0 Hz, 2 H, CH2, acetamide),
2.63−2.56 (m, 1 H, CH2, tmeda), 2.56 (s, 3 H, Me, tmeda), 2.47 (m, 1
H, CH2, tmeda), 2.33 (s, 3 H, Me, tmeda), 2.22 (m, 1 H, CH2, tmeda),
2.07 (m, 1 H, CH2, tmeda), 1.96 (s, 3 H, Me, tmeda), 1.70 (s, 3 H,
Me, tmeda). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 179.0
(CO), 147.9 (CPd), 144.0 (C, Ar), 142.3 (C, Ph), 137.12 (PdC=CPh),
137.07 (C, Ph), 132.7 (C, Ar), 131.1 (CH, Ar), 129.8 (CH, Ar),
128.67 (CH, Ph), 128,58 (CH, Ph), 128.1 (CH, Ph), 127.9 (CH, Ph),
127.56 (CH, Ar), 127.52 (CH, Ar), 126.2 (CH, Ph), 126.1 (CH, Ph),
2ad. Yield: 74%. Anal. Calcd for C24H32F3N3O4PdS: C, 46.34; H,
5.19; N, 6.76; S, 5.16. Found: C, 46.17; H, 5.44; N, 6,72; S, 4.87. Mp:
156−158 °C. IR (Nujol, cm−1): ν(NH), 3365, 3198; ν(CO), 1661. 1H
NMR (400.9 MHz, CDCl3): δ 8.28 (br s, 1 H, NH), 7.46−7.23 (m, 9
H, Ar + Ph), 6.83 (br s, 1 H, NH), 3.85, 3.54 (AB system, 2JHH = 15.6
Hz, 2 H, CH2, acetamide), 2.54−2.39 (m, 5 H, CH2 + Me, tmeda),
2.33 (s, 3 H, NMe), 2.25−2.18 (m, 1 H, CH2, tmeda), 2.07 (m, 1 H,
CH2, tmeda), 2.03 (s, 3 H, CMe), 2.01 (s, 3 H, NMe), 1.72 (s, 3 H,
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NMe). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 179.3 (CO),
146.2 (C, Ar), 141.7 (C, Ph), 141.1 (C−Pd), 132.6 (PdCC), 131.9
(C, Ar), 130.7 (CH, Ar), 128.4 (CH, Ph), 128.1 (CH, Ph), 128.0 (CH,
Ar), 127.6 (CH, Ar), 127.0 (CH, Ar), 125.8 (CH, Ph), 63.8 (CH2,
tmeda), 56.8 (CH2, tmeda), 52.8 (Me, tmeda), 49.6 (Me, tmeda), 48.4
(Me, tmeda), 45.1 (Me, tmeda), 38.3 (CH2, acetamide), 20.1 (CMe).
2ba. Yield: 88%. Anal. Calcd for C30H36F3N3O4PdS: C, 51.61; H,
5.20; N, 6.02; S, 4.59. Found: C, 51.63; H, 5.22; N, 6.11; S, 4.49. Mp:
207−209 °C. IR (Nujol, cm−1): ν(NH), 3271; ν(CO), 1615. 1H NMR
(400.9 MHz, CDCl3): δ 8.69 (br q, 3JHH = 4.8 Hz, 1 H, NH), 7.75 (d,
3JHH = 7.2 Hz, 1 H, Ar), 7.56−7.51 (m, 1 H, Ar), 7.36−7.18 (m, 7 H,
Ar + Ph), 7.06−6.95 (m, 5 H, Ph), 3.71, 3.55 (AB system, 2JHH = 16.0
tmeda), 52.8 (Me, tmeda), 49.6 (Me, tmeda), 48.1 (Me, tmeda), 45.2
(Me, tmeda), 38.7 (CH2, acetamide), 27.5 (Me, acetamide), 20.1
(CMe).
2ca. Yield: 95%. Anal. Calcd for C31H38F3N3O4PdS·0.25H2O: C,
51.96; H, 5.41; N, 5.86; S, 4.47. Found: C, 51.67; H, 5.70; N, 5.91; S,
1
4.18. Mp: 162−163 °C (dec). IR (Nujol, cm−1): ν(CO), 1590. H
3
NMR (400.9 MHz, CDCl3): δ 7.79 (d, JHH = 7.6 Hz, 1 H, Ar), 7.65
(t, 3JHH = 7.6 Hz, 1 H, Ar), 7.43 (t, 3JHH = 7.6 Hz, 1 H, Ar), 7.31 (m, 3
H, Ar + Ph), 7.24−7.18 (m, 3 H, Ph), 7.09−7.01 (m, 3 H, Ph), 6.98−
2
6.93 (m, 2 H, Ph), 3.55, 3.41 (AB system, JHH = 17.2 Hz, 2 H, CH2,
acetamide), 3.27 (s, 3 H, Me, acetamide), 3.16 (s, 3 H, Me,
acetamide), 2.72−2.57 (m, 2 H, CH2, tmeda), 2.55 (s, 3 H, Me,
tmeda), 2.38 (s, 3 H, Me, tmeda), 2.33 (m, 1 H, CH2, tmeda), 2.18
(m, 1 H, CH2, tmeda), 1.95 (s, 3 H, Me, tmeda), 1.79 (s, 3 H, Me,
tmeda), 1.67 (s, 0.5 H, H2O). 13C{1H} APT NMR (100.8 MHz,
CDCl3): δ 177.3 (CO), 148.4 (CPd), 144.0 (C, Ar), 142.1 (C, Ph),
137.3 (PdCC), 137.2 (C, Ph), 132.0 (C, Ar), 131.8 (CH, Ar), 130.0
(CH, Ar), 128.8 (CH, Ph), 128.5 (CH, Ph), 128.1 (CH, Ph), 127.93
(CH, Ar), 127.89 (CH, Ph), 127.8 (CH, Ar), 126.2 (CH, Ph), 64.2
(CH2, tmeda), 57.1 (CH2, tmeda), 53.5 (Me, tmeda), 49.4 (Me,
tmeda), 48.6 (Me, tmeda), 45.0 (Me, tmeda), 38.6 (Me, acetamide),
38.1 (CH2, acetamide), 37.6 (Me, acetamide).
3
Hz, 2 H, CH2, acetamide), 2.92 (d, JHH = 4.8 Hz, 3 H, Me,
acetamide), 2.63−2.58 (m, 1 H, CH2, tmeda), 2.56 (s, 3 H, Me,
tmeda), 2.54−2.44 (m, 1 H, CH2, tmeda), 2.33 (s, 3 H, Me, tmeda),
2.24 (m, 1 H, CH2, tmeda), 2.10 (m, 1 H, CH2, tmeda), 1.97 (s, 3 H,
Me, tmeda), 1.67 (s, 3 H, Me, tmeda). 13C{1H} APT NMR (100.8
MHz, CDCl3): δ 176.2 (CO), 147.5 (CPd), 144.0 (C, Ar), 142.3 (C,
Ph), 137.3 (PdCCPh), 137.1 (C, Ph), 133.0 (C, Ar), 131.1 (CH),
129.6 (CH), 128.62 (CH, Ph), 128.57 (CH, Ph), 128.1 (CH, Ph),
127.9 (CH, Ph), 127.46 (CH, Ar), 127.41 (CH, Ar), 126.2 (CH, Ph),
126.1 (CH, Ph), 63.8 (CH2, tmeda), 56.9 (CH2, tmeda), 53.1 (Me,
tmeda), 49.3 (Me, tmeda), 48.4 (Me, tmeda), 45.0 (Me, tmeda), 38.5
(CH2, acetamide), 27.5 (Me, acetamide).
Synthesis of 5,6-Substituted Benzo[d]azocine-2,4(1H,3H)-
diones (3). A solution of the appropriate complex 2 (0.23 mmol) in
CHCl3 (10 mL) was stirred under a CO atmosphere (1.4 bar) at 50
°C for 5 h (NH2 derivatives) or 24 h (NHMe derivatives), 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, except for
3bc, which required a 1:2 mixture. The corresponding compound 3
was obtained as a colorless solid after evaporation of the solvents.
5,6-Diphenylbenzo[d]azocine-2,4(1H,3H)-dione (3aa). Yield:
78%. Mp: 238−240 °C. IR (Nujol, cm−1): ν(CO), 1702, 1681.
HRMS (ESI+, m/z): exact mass calcd for C23H18NO2 [M + H]+
requires 340.1332, found 340.1337, error = 1.42 ppm. 1H NMR (400.9
2bb. Yield: 85%. Anal. Calcd for C22H32F3N3O8PdS: C, 39.92; H,
4.87; N, 6.35; S, 4.84. Found: C, 39.77; H, 5.06; N, 6.38; S, 4.66. Mp:
182−184 °C. IR (Nujol, cm−1): ν(NH), 3258; ν(CO), 1707, 1700,
1
3
1614. H NMR (400.9 MHz, CDCl3): δ 8.85 (br q, JHH = 4.4 Hz, 1
2
H, NH), 7.51−7.38 (m, 4 H, Ar), 3.85 (A part of AB system, JHH
16.4 Hz, 1 H, CH2, acetamide), 3.83 (s, 3 H, CO2Me), 3.64 (s, 3 H,
CO2Me), 3.56 (B part of AB system, 1 H, CH2, acetamide), 2.84 (s, 3
=
3
H, Me, tmeda), 2.82 (d, JHH = 4.4 Hz, 3 H, Me, acetamide), 2.80−
2.70 (m, 1 H, CH2, tmeda), 2.64−2.57 (m, 4 H, CH2 + Me, tmeda),
2.37 (s, 3 H, Me, tmeda), 2.29 (s, 1 H, CH2, tmeda), 2.21 (m, 1 H,
CH2, tmeda), 1.74 (s, 3 H, Me, tmeda). 13C{1H} APT NMR (100.8
MHz, CDCl3): δ 176.7 (CO, acetamide), 171.3 (CO2Me), 163.7
(CPd), 160.9 (CO2Me), 141.0 (C, Ar), 133.3 (C, Ar), 132.8 (PdC
C), 131.1 (CH, Ar), 128.9 (CH, Ar), 128.3 (CH, Ar), 127.7 (CH, Ar),
64.5 (CH2, tmeda), 57.7 (CH2, tmeda), 54.2 (Me, tmeda), 52.09
(CO2Me), 51.95 (CO2Me), 49.0 (Me, tmeda), 48.9 (Me, tmeda), 45.7
(Me, tmeda), 38.7 (CH2, acetamide), 27.6 (Me, acetamide).
4
3
MHz, CDCl3): δ 7.64 (br, 1H, NH), 7.44 (dd, JHH = 0.8 Hz, JHH
=
4
7.6 Hz, 1 H, H10), 7.43−7.38 (m, 2 H, Ph), 7.35 (td, JHH = 1.6 Hz,
3JHH = 7.6 Hz, 1 H, H9), 7.26 (td, JHH = 1.6 Hz, 3JHH = 7.6 Hz, 1 H,
4
H8), 7.24−7.09 (m, 7 H, Ph + H7), 6.96−6.93 (m, 2 H, Ph), 4.60 (d,
2JHH = 14.0 Hz, 1 H, CH2), 3.93 (dd, 4JHH = 1.6 Hz, 2JHH = 14.0 Hz, 1
H, CH2). 13C{1H} APT NMR (100.81 MHz, CDCl3): δ 172.2 (C2),
169.6 (C4), 140.1 (C6a), 139.5 (C6), 139.2 (C, Ph), 135.6 (C5),
134.7 (C, Ph), 133.0 (C10a), 130.8 (CH, Ph), 130.6 (C7), 129.7 (CH,
Ph), 129.4 (C9), 128.9 (C10), 128.52 (CH, Ph), 128.45 (CH, Ph),
128.37 (C8), 128.15 (CH, Ph), 128.08 (CH, Ph), 42.6 (C1).
2bc. Yield: 76%. Anal. Calcd for C22H36F3N3O4PdS: C, 43.89; H,
6.03; N, 6.98; S, 5.33. Found: C, 43.98; H, 6.15; N, 6.96; S, 5.23. Mp:
158−162 °C (dec). IR (Nujol, cm−1): ν(NH), 3276; ν(CO), 1623. 1H
3
NMR (400.9 MHz, CDCl3): δ 8.66 (br q, JHH = 4.8 Hz, 1 H, NH),
2
7.39−7.22 (m, 4 H, Ar), 3.70, 3.60 (AB system, JHH = 15.2 Hz, 2 H,
3
5,6-Diethylbenzo[d]azocine-2,4(1H,3H)-dione (3ac). Yield:
84%. Mp: 159−162 °C. IR (Nujol, cm−1): ν(CO), 1720, 1653.
HRMS (ESI+, m/z): exact mass calcd for C15H18NO2 [M + H]+
CH2, acetamide), 2.81 (d, JHH = 4.8 Hz, 3 H, NHMe), 2.68 (s, 3 H,
Me, tmeda), 2.52−2.27 (m, 11 H, CH2, Me, tmeda + CH2CH3), 2.18−
2.11 (m, 1 H, CH2, tmeda), 2.01, 1.89 (AB part of ABX3 system, 2JHH
1
3
244.1332, found 244.1331, error = 0.53 ppm. H NMR (400.9 MHz,
= 14.6 Hz, JHH = 7.6 Hz, 2 H, CH2CH3), 1.64 (s, 3 H, Me, tmeda),
3
3
CDCl3): δ 7.71 (br s, 1 H, NH), 7.35−7.22 (m, 4 H, H7−10), 4.20,
1.15 (t, JHH = 7.6 Hz, 3 H, CH2CH3), 0.85 (t, JHH = 7.6 Hz, 3 H,
CH2CH3). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 176.8 (CO),
147.3 (CC), 144.8 (C, Ar), 135.6 (CC), 133.9 (C, Ar), 130.6
(CH, Ar), 128.3 (CH, Ar), 127.1 (CH, Ar), 126.5 (CH, Ar), 63.6
(CH2, tmeda), 56.6 (CH2, tmeda), 52.5 (Me, tmeda), 51.2 (Me,
tmeda), 47.1 (Me, tmeda), 45.9 (Me, tmeda), 39.0 (CH2, acetamide),
27.2 (NHMe), 26.4, 26.2 (CH2CH3), 14.6, 13.4 (CH2CH3).
3.68 (AB system, 2JHH = 13.6 Hz, 2 H, CH2CO), 2.76 (A part of ABX3
system, 2JHH = 13.6 Hz, 3JHH = 7.6 Hz, 1 H, CH2CH3), 2.60 (q, 3JHH
=
7.6 Hz, 2 H, CH2CH3), 2.34 (B part of ABX3 system, 1 H, CH2CH3),
3
3
1.21 (t, JHH = 7.6 Hz, 3 H, CH2CH3), 0.90 (t, JHH = 7.6 Hz, 3 H,
CH2CH3). 13C{1H} APT NMR (100.8 MHz, CDCl3): 172.2 (C2),
171.0 (C4), 140.0 (C6), 139.4 (C6a), 135.4 (C5), 132.3 (C10a),
128.5, 128.4, 128.1, 127.9 (C7−10), 42.5 (C1), 27.8 (CH2CH3), 25.4
(CH2CH3), 14.0 (CH2CH3), 12.1 (CH2CH3).
2bd. Yield: 88%. Anal. Calcd for C25H34F3N3O4PdS: C, 47.21; H,
5.39; N, 6.61; S, 5.04. Found: C, 47.35; H, 5.21; N, 6.76; S, 4.80. Mp:
138−143 °C (dec). IR (Nujol, cm−1): ν(NH), 3278; ν(CO), 1620. 1H
NMR (400.9 MHz, CDCl3): δ 8.86 (br, 1 H, NH), 7.44−7.23 (m, 9 H,
6-Methyl-5-phenylbenzo[d]azocine-2,4(1H,3H)-dione (3ad).
Yield: 94%. Mp: 217−222 °C. IR (Nujol, cm−1): ν(CO), 1697,
1672. HRMS (ESI+, m/z): exact mass calcd for C18H16NO2 [M + H]+
2
Ar + Ph), 3.88, 3.51 (AB system, JHH = 15.6 Hz, 2 H, CH2,
1
3
278.1176, found 278.1171, error = 1.61 ppm. H NMR (400.9 MHz,
acetamide), 2.92 (d, JHH = 4.4 Hz, 3 H, Me, acetamide), 2.55−2.41
CDCl3): δ 7.78 (br s, 1 H, NH), 7.50−7.46 (m, 2 H, aromatic), 7.44−
7.30 (m, 7 H, aromatic), 4.42 (d, 2JHH = 14.0 Hz, 1 H, CH2), 3.81 (dd,
4JHH = 1.6 Hz, 2JHH = 14.0 Hz, 1 H, CH2), 2.05 (s, 3 H, Me). 13C{1H}
APT NMR (100.8 MHz, CDCl3): δ 172.1 (C2), 169.2 (C4), 140.2
(C6a), 137.7 (C6), 136.3 (C, Ph), 135.4 (C5), 131.2 (C10a), 129.2
(CH, Ph) 129.1 (CH), 128.9 (CH), 128.7 (CH, Ph), 128.4 (CH),
128.3 (CH), 127.9 (CH), 42.5 (CH2), 22.1 (Me).
(m, 7 H, CH2 + Me, tmeda), 2.34 (s, 3 H, Me, tmeda), 2.26−2.21 (m,
1 H, CH2, tmeda), 2.12−2.06 (m, 1 H, CH2, tmeda), 2.04 (s, 3 H, Me,
tmeda), 2.02 (s, 3 H, CMe), 1.70 (s, 3 H, Me, tmeda). 13C{1H} APT
NMR (75.45 MHz, CDCl3): δ 176.6 (CO), 146.2 (C, Ar), 141.7 (C,
Ph), 140.8 (C−Pd), 132.9 (PdCC), 132.3 (C, Ar), 130.9 (CH, Ar),
128.3 (CH, Ph), 128.0 (CH, Ph), 127.8 (CH, Ar), 127.4 (CH, Ar),
127.0 (CH, Ar), 125.8 (CH, Ph), 63.7 (CH2, tmeda), 56.8 (CH2,
3368
dx.doi.org/10.1021/om300151n | Organometallics 2012, 31, 3361−3372

Organometallics
Article
3-Methyl-5,6-diphenylbenzo[d]azocine-2,4(1H,3H)-dione
(3ba). Yield: 71%. Mp: 244−248 °C. IR (Nujol, cm−1): ν(CO),
1703, 1660. HRMS (ESI+, m/z): exact mass calcd for C24H20NO2 [M
+ H]+ requires 354.1489, found 354.1493, error = 1.27 ppm. 1H NMR
(400.9 MHz, CDCl3): δ 7.40−7.11 (m, 12 H, H7−10 + Ph), 6.99 (m,
2 H, Ph), 4.68, 4.05 (AB system, 2JHH = 15.2 Hz, 2 H, CH2), 3.10 (s, 3
H, Me). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 173.6 (C2),
172.3 (C4), 141.1 (C6a), 138.6 (C, Ph), 138.0, 137.7 (C5/C6), 134.5
(C, Ph), 133.7 (C10a), 130.9 (CH, Ph), 129.9 (C7), 129.3 (CH, Ph +
C9/C10), 129.2 (C9/C10), 128.7 (CH, Ph), 128.5 (CH, Ph), 128.3
(C8), 128.2 (CH, Ph), 128.1 (CH, Ph), 44.3 (C1), 31.8 (Me).
5,6-Diethyl-3-methylbenzo[d]azocine-2,4(1H,3H)-dione
(3bc). Yield: 70%. Mp: 72−82 °C. IR (Nujol, cm−1): ν(CO), 1708,
1666. HRMS (ESI+, m/z): exact mass calcd for C16H20NO2 [M + H]+
14.8 Hz, 2 H, CH2, acetamide), 3.16−3.13 (m, 1 H, CH2, tmeda),
2.86−2.75 (m, 1 H, CH2, tmeda), 2.64 (s, 3 H, Me, tmeda), 2.54 (s, 3
H, Me, tmeda), 2.49−2.37 (m, 2 H, CH2, tmeda), 2.25 (s, 3 H, Me,
tmeda), 1.74 (s, 3 H, Me, tmeda), 1.68 (s, 1 H, H2O), 1.52 (s, 9 H, t-
Bu).
Synthesis of [Pd{C(CO2Me)C(CO2Me)C6H4CH2C(O)NH2-
2}(CN-t-Bu)(tmeda)]TfO (5b). To a solution of 2ab (102 mg, 0.16
mmol) in CH2Cl2 (10 mL) was added t-BuNC (18 μL, 0.16 mmol).
The mixture was stirred for 10 min and filtered through anhydrous
MgSO4. Partial evaporation of the filtrate (1 mL) and addition of Et2O
(20 mL) led to the precipitation of a colorless solid, which was
collected by filtration and recrystallized from CH2Cl2/Et2O to give
5b·H2O. Yield: 78 mg, 65%. Anal. Calcd for C26H41F3N4O9PdS: C,
41.69; H, 5.52; N, 7.48; S, 4.28. Found: C, 41.49; H, 5.25; N, 7.50; S,
4.18. Mp: 101−105 °C (dec). IR (Nujol, cm−1): ν(NH), 3423, 3334,
3190; ν(CN), 2222; ν(CO), 1715, 1673. 1H NMR (400.9 MHz,
CDCl3): δ 7.55 (m, 1 H, Ar), 7.44 (m, 3 H, Ar), 6.20 (br, 1 H, NH),
5.56 (br, 1 H, NH), 3.86 (s, 3 H, CO2Me), 3.68 (s, 3 H, CO2Me), 3.44
(s, 2 H, CH2, acetamide), 2.95 (m, 1 H, CH2, tmeda), 2.80 (s, 3 H,
Me, tmeda), 2.74 (s, 3 H, Me, tmeda), 2.61 (m, 2 H, CH2, tmeda),
2.48 (m, 4 H, CH2, Me, tmeda), 2.23 (br, 3 H, Me, tmeda), 1.86 (br, 2
H, H2O), 1.63 (s, 9 H, t-Bu). 13C{1H} APT NMR (75.5 MHz,
CDCl3): δ 172.5 (CONH2), 171.4 (CO2Me), 163.5 (CO2Me), 159.1
(PdC), 138.4 (C, Ar), 134.5 (C, Ar), 134.3 (ArCC), 130.5 (CH,
Ar), 130.0 (CH, Ar), 129.1 (CH, Ar), 127.2 (CH, Ar), 63.1 (CH2,
tmeda), 60.5 (CMe3), 59.1 (CH2, tmeda), 52.4 (CO2Me), 52.1 (Me,
tmeda), 52.0 (CO2Me), 51.2 (Me, tmeda), 49.5 (Me, tmeda), 49.1
(Me, tmeda), 40.4 (CH2, acetamide), 29.7 (CMe3). (CN not
observed).
1
258.1489, found 258.1496, error = 2.94 ppm. H NMR (400.9 MHz,
CDCl3): δ 7.32−7.22 (m, 4 H, H7−10), 4.33, 3.84 (AB system, 2JHH
=
14.8 Hz, 2 H, CH2CO), 3.10 (s, 3 H, NMe), 2.71 (A part of ABX3
system, 2JHH = 13.6 Hz, 3JHH = 7.6 Hz, 1 H, CH2CH3), 2.62−2.46 (m,
2 H, CH2CH3), 2.36 (B part of ABX3 system, 1 H, CH2CH3), 1.12 (t,
3JHH = 7.6 Hz, 3 H, CH2CH3), 0.91 (t, 3JHH = 7.6 Hz, 3 H, CH2CH3).
13C{1H} APT NMR (75.5 MHz, CDCl3): 174.4 (C2), 173.9 (C4),
140.2 (C6a), 137.5 (C5), 137.3 (C6), 132.8 (C10a), 128.8, 128.2,
128.0, 127.1 (C7−10), 44.4 (C1), 31.1 (NMe), 26.3 (CH2CH3), 25.4
(CH2CH3), 13.5 (CH2CH3), 12.0 (CH2CH3).
3,6-Dimethyl-5-phenylbenzo[d]azocine-2,4(1H,3H)-dione
(3bd). Yield: 57%. Mp: 183−188 °C. IR (Nujol, cm−1): ν(CO),
1704, 1662. HRMS (ESI+, m/z): exact mass calcd for C19H18NO2 [M
+ H]+ requires 292.1332, found 292.1335, error = 1.03 ppm. 1H NMR
(400.9 MHz, CDCl3): δ 7.46−7.28 (m, 9 H, aromatic), 4.53, 3.95 (AB
system, 2JHH = 15.2 Hz, 2 H, CH2), 3.05 (s, 3 H, NMe), 2.08 (s, 3 H,
CMe). 13C{1H} APT NMR (75.45 MHz, CDCl3): δ 174.0 (C2), 172.2
(C4), 141.2 (C6a), 137.6 (C6), 135.7 (C, Ph), 135.2 (C5), 131.9
(C10a), 129.4 (CH) 128.83 (CH), 128.76 (CH), 128.73 (CH), 128.5
(CH), 128.2 (CH), 127.2 (CH), 44.4 (C1), 31.6 (NMe), 20.5 (CMe).
Synthesis of Trimethyl 2-(2-(carbamoylmethyl)phenyl)-
ethene-1,1,2-tricarboxylate (4). A solution of 2ab (101 mg, 0.16
mmol) in MeOH (15 mL) was stirred under a CO atmosphere (1.4
bar) for 24 h. The gradual formation of colloidal Pd was observed. The
solvent was removed under reduced pressure, the residue was
extracted with Et2O (6 × 5 mL), and the combined extracts were
filtered through anhydrous MgSO4. The solvent was evaporated to
dryness, and the residue was crystallized from CH2Cl2/n-hexane to
give 4 as a colorless solid, which was filtered off, washed with n-hexane,
and vacuum-dried. Yield: 22 mg, 42%. Mp: 76−83 °C. IR (Nujol,
cm−1): ν(NH), 3405, 3194; ν(CO); 1731, 1720, 1658. HRMS (ESI+,
m/z): exact mass calcd for C16H18NO7 [M + H]+ 336.1078, found
336.1083, error = 1.5 ppm. 1H NMR (400.9 MHz, CDCl3): δ 7.49 (br
Synthesis of [Pd{C(CO2Me)C(CO2Me)C6H4CH2C(O)NH2-2}-
(CNXy)(tmeda)]TfO (5b′). This pale yellow compound was obtained
as a monohydrate as described for 5b·H2O, from 2ab (139.4 mg, 0.22
mmol) and XyNC (28.3 mg, 0.22 mmol). Yield: 143 mg, 83%. Anal.
Calcd for C30H41F3N4O9PdS: C, 45.20; H, 5.18; N, 7.03; S, 4.02.
Found: C, 45.19; H, 4.90; N, 7.01; S, 3.87. Mp: 89 °C. IR (Nujol,
cm−1): ν(NH), 3426, 3335, 3187; ν(CN), 2199; ν(CO), 1710, 1684.
1H NMR (400.9 MHz, CDCl3): δ 7.79 (dd, 4JHH = 1.6 Hz, 3JHH = 7.6
3
4
Hz, 1 H, Ar), 7.5 (br t, JHH = 7.6 Hz, 1 H, Ar), 7.46 (td, JHH = 1.6
3
Hz, JHH = 7.6 Hz, 1 H, Ar), 7.37−7.33 (m, 2 H, Ar + p-H, Xy), 7.19
(d, JHH = 7.6 Hz, 2 H, m-H, Xy), 5.97 (br, 1 H, NH), 5.44 (br, 1 H,
NH), 3.87 (s, 3 H, CO2Me), 3.67 (s, 3 H, CO2Me), 3.31 (d, JHH
3
2
=
15.6 Hz, 1 H, CH2, acetamide), 3.15−2.45 (m, 17 H, Me, CH2, tmeda,
CH2, acetamide), 2.41 (br s, 6 H, Me, Xy), 1.80 (br, 2 H, H2O).
13C{1H} APT NMR (100.8 MHz, CDCl3): δ 172.0 (CONH2), 171.0
(CO2Me), 163.5 (CO2Me), 136.0 (o-C, Xy), 135.4 (ArCC), 134.3
(C, Ar), 131.3 (CH, Ar), 130.7 (CH, Ar), 130.1 (CH, Ar), 129.3 (CH,
Ar), 128.7 (m-C, Xy), 127.6 (p-C, Xy), 124.7 (br, i-C, Xy), 63.7 (CH2,
tmeda), 59.3 (CH2, tmeda), 52.8 (Me, tmeda), 52.5 (CO2Me), 52.2
(CO2Me), 51.7 (Me, tmeda), 49.9 (Me, tmeda), 40.0 (CH2,
acetamide), 18.6 (Me, Xy).
4
d, 3JHH = 7.6 Hz, 1 H, H3, C6H4), 7.39 (td, JHH = 1.6 Hz, 3JHH = 7.6
Hz, 1 H, H4, C6H4), 7.29 (td, 4JHH = 1.6 Hz, 3JHH = 7.6 Hz, 1 H, H5,
4
3
C6H4), 7.19 (dd, JHH = 1.6 Hz, JHH = 7.6 Hz, 1 H, H6, C6H4), 6.25
(br, 1 H, NH), 5.33 (br, 1 H, NH), 3.88 (s, 3 H, CO2Me), 3.82 (s, 3
H, CO2Me), 3.60 (s, 2 H, CH2), 3.57 (s, 3 H, CO2Me). 13C NMR
(100.8 MHz, CDCl3): δ 172.8 (CONH2), 166.7, 164.1, 163.0
(CO2Me), 146.2 (C6H4CC), 133.4 (C2, C6H4), 132.6 (C1,
C6H4), 131.0 (C6H4C=C), 130.04 (C3, C6H4), 129.98 (C4, C6H4),
128.3 (C6, C6H4), 127.4 (C5, C6H4), 53.3, 53.2, 52.8 (CO2Me), 40.5
(CH2).
Synthesis of (Z)-3-(2-(Carbamoylmethyl)phenyl)-N-(2,6-di-
methylphenyl)-2,3-diphenylacrylamide (6a). To a solution of
2aa (202 mg, 0.30 mmol) in CHCl3 (20 mL) was added XyNC (39
mg, 0.30 mmol), and the mixture was refluxed for 48 h. The resulting
dark suspension was filtered through anhydrous MgSO4, the solvent
was removed under vacuum, and the residue was chromatographed on
silica gel, using a 2:1 CH2Cl2/n-hexane mixture as eluent. A colorless
fraction with Rf = 0.65−0.8 was collected. Compound 6a was obtained
as a colorless solid after evaporation of the solvents. Yield: 32 mg, 24%.
Mp: 275−278 °C. IR (Nujol, cm−1): ν(CO), 1667, 1639. HRMS (ESI
+, m/z): exact mass calcd for C31H29N2O2 [M + H]+ requires
Synthesis of [Pd{C(Ph)C(Ph)C6H4CH2C(O)NH2-2}(CN-t-Bu)-
(tmeda)]TfO (5a). To a solution of 2aa (194 mg, 0.28 mmol) in
CH2Cl2 (10 mL) was added t-BuNC (33 μL, 0.29 mmol), and the
mixture was stirred for 1 h. The addition of n-pentane (10 mL) led to
the precipitation of a colorless solid, which was filtered off, washed
with a 1:1 CH2Cl2/n-pentane mixture (5 × 3 mL), and vacuum-dried
to give 5a·0.5H2O. Yield: 134 mg, 61%. Mp: 167−169 °C (dec). Anal.
Calcd for C34H44F3N4O4.5PdS: C, 52.61; H, 5.71; N, 7.22; S, 4.13.
Found: C, 52.51; H, 5.99; N, 7.32; S, 3.85. IR (Nujol, cm−1): ν(NH),
3601, 3408, 3188; ν(CN), 2206; ν(CO), 1691. 1H NMR (400.9 MHz,
CD2Cl2, 263 K): δ 7.87 (d, 3JHH = 7.2 Hz, 1 H, Ar), 7.53 (m, 1 H, Ar),
7.42−7.37 (m, 2 H, Ar), 7.20−7.07 (m, 8 H, Ph), 6.91 (m, 2 H, Ph),
1
461.2224, found 461.2228, error = 0.98 ppm. H NMR (400.9 MHz,
CDCl3): δ 7.61 (m, 1 H, C6H4), 7.58 (br s, 1 H, NH), 7.37−7.22 (m,
8 H, C6H4 + Ph), 7.17 (br s, 1 H, NH), 7.11−7.05 (m, 3 H, Ph),
7.02−6.91 (m, 5 H, Ph + m-H, p-H, Xy), 5.19 (br s, 1 H, NH), 3.32,
2
3.10 (AB system, JHH = 16.0 Hz, 2 H, CH2), 1.94 (s, 6 H, Me, Xy).
13C{1H} APT NMR (100.8 MHz, CDCl3): δ 174.0 (CONH2), 168.0
(CONXy), 145.5 (C6H4CC), 141.6 (C1, C6H4), 139.3 (C, Ph),
137.9 (C, Ph), 137.8 (C6H4CC), 135.3 (o-C, Xy), 133.9 (C2,
C6H4), 133.4 (i-C, Xy), 131.2 (C3, C6H4), 130.6 (C6, C6H4), 130.36
4.59 (br, 1 H, NH), 4.10 (br, 1 H, NH), 3.46, 3.20 (AB system, 2JHH
=
3369
dx.doi.org/10.1021/om300151n | Organometallics 2012, 31, 3361−3372

Organometallics
Article
(CH, Ph), 130.28 (CH, Ph), 128.8 (C4, C6H4), 128.75 (CH, Ph),
128.2 (m-C, Xy), 128.1 (CH, Ph), 127.9 (CH, Ph), 127.8 (CH, Ph),
127.5 (C5, C6H4), 127.3 (p-C, Xy), 40.9 (CH2), 18.6 (Me, Xy).
Synthesis of (Z)-3-(2-(Methylcarbamoylmethyl)phenyl)-N-
(2,6-dimethylphenyl)-2,3-diphenylacrylamide (6b). To a solu-
tion of 2ba (97 mg, 0.14 mmol) in acetone (25 mL) was added XyNC
(70 mg, 0.53 mmol), and the mixture was stirred for 24 h, whereupon
a red solution was obtained. The solvent was removed under vacuum,
and the residue was chromatographed on silica gel, using a 2:1 EtOAc/
n-hexane mixture as eluent. A colorless fraction with Rf = 0.6 was
collected. Compound 6b was obtained as a colorless solid after
evaporation of the solvents. Yield: 33 mg, 50%. Mp: 290−293 °C. IR
(Nujol, cm−1): ν(NH), 3261; ν(CO), 1655, 1629. HRMS (ESI+, m/
z): exact mass calcd for C32H31N2O2 [M + H]+ requires 475.2380,
5.25 (br s, 1 H, NH), 5.21 (br s, 1 H, NH), 3.43, 3.37 (AB system,
2JHH = 15.6 Hz, 2 H, CH2). 13C{1H} NMR (100.8 MHz, CDCl3): δ
172.2 (CO), 156.4 (CCCN), 140.7 (C, C6H4), 137.0 (C, Ph), 133.4
(C, Ph), 133.1 (C, C6H4), 131.4 (C, C6H4), 130.8 (CH, C6H4), 130.17
(CH, Ph), 130.13 (CH, C6H4), 129.6 (CH, Ph), 129.5 (CH, Ph),
128.9 (CH, Ph), 128.7 (CH, Ph), 128.5 (CH, Ph), 128.2 (CH, C6H4),
119.4 (CN), 114.6 (C=CCN), 40.7 (CH2).
Synthesis of (Z)-2-(2-(2-Cyano-1,2-dyphenylvinyl)phenyl)-N-
methylacetamide (7b). This colorless compound was prepared as
described for 7a (method A), from 2ba (83 mg, 0.12 mmol) and KCN
(8 mg, 0.12 mmol). Yield: 28 mg, 67%. Mp: 170−173 °C. IR (Nujol,
cm−1): ν(NH), 3282; ν(CN), 2209; ν(CO), 1640. HRMS (ESI+, m/
z): exact mass calcd for C24H21N2O [M + H]+ requires 353.1648,
1
found 353.1655, error = 1.81 ppm. H NMR (400.9 MHz, CDCl3): δ
1
found 475.2390, error = 2.07 ppm. H NMR (400.9 MHz, CDCl3): δ
7.57−7.53 (m, 1 H, H3, C6H4), 7.51−7.46 (m, 2 H, H4, H5, C6H4),
7.38−7.35 (m, 1 H, H6, C6H4), 7.30−7.24 (m, 5 H, Ph), 7.22 (m, 1 H,
Ph), 7.18−7.14 (m, 2 H, Ph), 7.00 (m, 2 H, Ph), 5.18 (br, 1 H, NH),
3.39, 3.33 (AB system, 2JHH = 16.0 Hz, 2 H, CH2), 2.69 (d, 3JHH = 4.8
Hz, 3 H, Me). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 170.4
(CO), 156.5 (CCCN), 140.9 (C, C6H4), 136.9 (C, Ph), 133.3 (C,
Ph), 133.2 (C, C6H4), 131.7 (CH, C6H4), 130.7 (CH, C6H4), 130.1
(CH, C6H4 + Ph), 129.6 (CH, Ph), 129.4 (CH, Ph), 128.9 (CH, Ph),
128.7 (CH, Ph), 128.4 (CH, Ph), 128.2 (CH, C6H4), 119.3 (CN),
114.6 (C=CCN), 41.3 (CH2), 26.5 (Me).
4
3
7.86 (br, 1 H, NH), 7.62 (dd, JHH = 1.6 Hz, JHH = 7.2 Hz, 1 H,
C6H4), 7.35−7.23 (m, 7 H, C6H4 + Ph), 7.17 (m, 1 H, C6H4), 7.12−
7.04 (m, 3 H, Ph), 7.02−6.89 (m, 6 H, Ph + NH + m-H + p-H, Xy),
3.19, 3.10 (AB system, 2JHH = 16.0 Hz, 2 H, CH2), 2.68 (d, 3JHH = 4.4
Hz, 3 H, Me), 1.97 (s, 6 H, Me, Xy). 13C{1H} APT NMR (100.8
MHz, CDCl3): δ 171.9 (CONMe), 167.9 (CONXy), 145.1 (C6H4C
C), 141.7 (C1, C6H4), 139.3 (C, Ph), 138.0 (C, Ph), 137.8
(C6H4C=C), 135.3 (o-C, Xy), 133.9 (C2, C6H4), 133.6 (i-C, Xy),
131.5 (C3, C6H4), 130.7 (C6, C6H4), 130.35 (CH, Ph), 130.29 (CH,
Ph), 128.8 (C4, C6H4), 128.7 (CH, Ph), 128.1 (m-C, Xy), 127.9 (CH,
Ph), 127.8 (CH, Ph), 127.7 (CH, Ph), 127.5 (C5, C6H4), 127.1 (p-C,
Xy), 41.5 (CH2), 26.4 (NMe), 18.5 (Me, Xy).
Synthesis of (Z)-2-(2-(2-Cyano-1,2-dyphenylvinyl)phenyl)-
N,N-dimethylacetamide (7c). This colorless compound was
prepared as described for 7a (method A), from 2ca (116 mg, 0.16
mmol) and KCN (11 mg, 0.17 mmol). Yield: 37 mg, 62%. Mp: 122−
132 °C. IR (Nujol, cm−1): ν(CN), 2202; ν(CO), 1646. HRMS (ESI+,
m/z): exact mass calcd for C25H23N2O [M + H]+ requires 367.1805,
Synthesis of (Z)-3-(2-(Dimethylcarbamoylmethyl)phenyl)-N-
(2,6-dimethylphenyl)-2,3-diphenylacrylamide (6c). This color-
less compound was obtained as described for 6b, from 2ca (116 mg,
0.16 mmol) and XyNC (85 mg, 0.66 mmol). Yield: 42 mg, 53%. Mp:
203−208 °C. IR (Nujol, cm−1): ν(NH), 3204; ν(CO), 1666, 1634.
HRMS (ESI+, m/z): exact mass calcd for C33H33N2O2 [M + H]+
requires 489.2537, found 489.2539, error = 0.45 ppm. 1H NMR (400.9
1
found 367.1821, error = 4.37 ppm. H NMR (400.9 MHz, CDCl3): δ
7.46−7.39 (m, 3 H, H3, H4, H5 of C6H4), 7.34−7.26 (m, 6 H, H6 of
C6H4 + Ph), 7.23−7.19 (m, 1 H, Ph), 7.16−7.13 (m, 2 H, Ph), 7.04−
7.01 (m, 2 H, Ph), 3.58, 3.45 (br, 2 H, CH2), 2.89 (s, 3 H, Me), 2.80
(s, 3 H, Me). 13C{1H} APT NMR (100.8 MHz, CDCl3): δ 170.2
(CO), 156.8 (CCCN), 139.9 (C, C6H4), 137.2 (C, Ph), 133.9 (C,
Ph), 133.6 (C, C6H4), 130.4 (CH, Ph), 130.3 (CH, C6H4), 129.9 (CH,
C6H4), 129.8 (CH, C6H4), 129.6 (CH, Ph), 129.3 (CH, Ph), 128.72
(CH, Ph), 128.67 (CH, Ph), 128.2 (CH, Ph), 127.3 (CH, C6H4),
119.2 (CN), 113.6 (CCCN), 38.6 (CH2), 37.5 (Me), 35.5 (Me).
Synthesis of [Pd{C(Ph)C(Ph)C6H4CH2C(O)NH2-2}(CN)-
(tmeda)] (8). To a solution of 1a (150 mg, 0.22 mmol) in acetone
(25 mL) was added KCN (14 mg, 0.22 mmol), and the mixture was
stirred for 15 h. The solvent was removed under reduced pressure, the
residue was extracted with CH2Cl2 (6 × 5 mL), and the combined
extracts were filtered through Celite. Partial evaporation of the filtrate
(3 mL) and addition of n-pentane (15 mL) led to the precipitation of a
colorless solid, which was filtered off, washed with n-pentane (3 × 3
mL), and vacuum-dried to give 8. The product was purified by
recrystallization from CH2Cl2/n-pentane. Yield: 98 mg, 80%. Anal.
Calcd for C29H34N4OPd: C, 62.09; H, 6.11; N, 9.99. Found: C, 61.64;
H, 6.03; N, 9.90. Mp: 180 °C (dec). IR (Nujol, cm−1): ν(NH), 3311,
MHz, CDCl3): δ 10.02 (s, 1 H, NH), 7.82 (dd, 4JHH = 1.2 Hz, 3JHH
=
3
7.6 Hz, 1 H, C6H4), 7.38 (br t, JHH = 7.6 Hz, 1 H, C6H4), 7.31 (td,
3
4JHH = 1.2 Hz, JHH = 7.6 Hz, 1 H, C6H4), 7.28−7.26 (m, 2 H, Ph),
7.22−7.16 (m, 3 H, Ph), 7.14−7.05 (m, 4 H, Ph + C6H4), 6.97−6.91
(m, 3 H, m-H, p-H, Xy), 6.84−6.82 (m, 2 H, Ph), 3.16, 2.99 (AB
system, 2JHH = 17.2 Hz, 2 H, CH2), 2.97 (s, 3 H, NMe), 2.68 (s, 3 H,
NMe), 1.90 (br, 6 H, Me, Xy). 13C{1H} APT NMR (100.8 MHz,
CDCl3): δ 171.2 (CONMe), 168.0 (CONXy), 141.9 (C1, C6H4),
140.4 (C6H4CC), 139.7 (C, Ph), 139.5 (C6H4CC), 138.8 (C,
Ph), 135.3 (o-C, Xy), 134.6 (i-C, Xy), 134.2 (C2, C6H4), 132.1 (C6,
C6H4), 132.0 (C3, C6H4), 130.3 (CH, Ph), 130.1 (CH, Ph), 128.4
(C4, C6H4), 128.1 (CH, Ph + C5, C6H4), 127.9 (m-C, Xy), 127.7
(CH, Ph), 127.14 (CH, Ph), 127.09 (CH, Ph), 126.2 (p-C, Xy), 39.2
(CH2), 37.2 (NMe), 35.9 (NMe); Me of Xy not observed.
Synthesis of (Z)-2-(2-(2-Cyano-1,2-diphenylvinyl)phenyl)-
acetamide (7a). Method A: To a solution of 2aa (147 mg, 0.21
mmol) in acetone (20 mL) was added KCN (15 mg, 0.23 mmol), and
the mixture was stirred for 15 h. The solvent was removed under
reduced pressure, CHCl3 (20 mL) was added, and the resulting
suspension was refluxed for 24 h, whereupon the gradual formation of
colloidal Pd was observed. The solvent was evaporated to dryness, the
residue was extracted with a 1:10 CHCl3/Et2O mixture (20 + 5 × 3
mL), and the combined extracts were filtered through anhydrous
MgSO4. The filtrate was evaporated to dryness, and the residue was
crystallized from CH2Cl2/n-hexane (10 mL) to give 7a as a colorless
solid, which was filtered off, washed with n-hexane (3 × 3 mL), and
vacuum-dried. Yield: 44 mg, 61%. Method B: A solution of 2aa (155
mg, 0.23 mmol) and t-BuNC (26.2 mg, 0.23 mmol) in CHCl3 (15
mL) was refluxed for 24 h, whereupon the gradual formation of
colloidal Pd was observed. The reaction mixture was worked up as
described for method A to give 7a. Yield: 42 mg, 55%. Mp: 198−204
°C. IR (Nujol, cm−1): ν(NH), 3398, 3203; ν(CN), 2210; ν(CO),
1655. HRMS (ESI+, m/z): exact mass calcd for C23H19N2O [M + H]+
requires 339.1492, found 339.1491, error = 0.29 ppm. 1H NMR (400.9
MHz, CDCl3): δ 7.55−7.44 (m, 3 H, H3, H4, H5, C6H4), 7.43−7.37
(m, 1 H, H6, C6H4), 7.34−7.14 (m, 8 H, Ph), 7.03−7.00 (m, 2 H, Ph),
1
ν(CN), 2120; ν(CO), 1680. H NMR (400.9 MHz, CDCl3): δ 7.74
(d, 3JHH = 6.0 Hz, 1 H, Ar), 7.61 (br s, 1 H, NH), 7.38−7.34 (m, 1 H,
3
Ar), 7.33−7.27 (m, 4 H, Ar + Ph), 7.13 (t, JHH = 7.2 Hz, 2 H, Ph),
7.09−7.02 (m, 1 H, Ph), 6.99−6.91 (m, 3 H, Ph), 6.86−6.82 (m, 2 H,
2
Ph), 5.12 (br s, 1 H, NH), 3.90 (d, JHH = 15.6 Hz, 1 H, CH2,
3
2
acetamide), 2.99 (td, JHH = 3.2 Hz; JHH = 12.8 Hz, 1 H, CH2,
tmeda), 2.69−2.58 (m, 8 H, CH2, tmeda, acetamide + Me), 2.28 (s, 3
H, Me), 2.28−2.18 (m, 2 H, CH2, tmeda), 1.77 (s, 3 H, Me). 13C{1H}
NMR (100.8 MHz, CDCl3): δ 175.3 (CO), 148.7 (PdC), 147.8 (C,
Ar), 144.8 (C, Ph), 141.3 (PdCC), 140.8 (C, Ph), 135.4 (C, Ar),
131.2 (CN), 130.5 (CH, Ph), 130.4 (CH, Ar), 129.9 (CH, Ph), 127.8
(CH, Ar), 127.7 (CH, Ph), 127.3 (CH, Ph), 127.1 (CH, Ar), 125.3
(CH, Ph), 124.9 (CH, Ph), 124.6 (CH, Ar), 62.4 (CH2, tmeda), 58.2
(CH2, tmeda), 51.7 (Me), 51.2 (Me), 47.5 (Me), 46.9 (Me), 41.4
(CH2, acetamide).
Synthesis of (Z)-3-(2-(Cyanomethyl)phenyl)-N-(2,6-dime-
thylphenyl)-2,3-diphenylacrylamide (9). To a solution of 2aa
(171 mg, 0.25 mmol) in CH2Cl2 (5 mL) was added XyNC (131 mg,
3370
dx.doi.org/10.1021/om300151n | Organometallics 2012, 31, 3361−3372

Organometallics
Article
1.00 mmol), and the mixture was stirred for 15 h, whereupon a dark
red solution was obtained. The solvent was removed under vacuum,
the residue was extracted with a 1:5 CH2Cl2/n-pentane mixture (10 ×
3 mL), and the combined extracts were filtered through Celite.
Evaporation of the solvent under reduced pressure and addition of
Et2O (10 mL) and n-pentane (10 mL) led to the formation of a
colorless solid, which was filtered off, washed with a 1:1 Et2O/n-
pentane mixture (5 × 3 mL), and vacuum-dried to give 9. Yield: 63
mg, 57%. Mp: 217−221 °C. IR (Nujol, cm−1): ν(NH), 3362; ν(CO),
1660. HRMS (ESI+, m/z): exact mass calcd for C31H27N2O [M + H]+
requires 443.2118, found 443.2122, error = 0.83 ppm. 1H NMR (400.9
MHz, CDCl3): δ 7.71 (dd, 4JHH = 1.2 Hz, 3JHH = 7.2 Hz, 1 H, C6H4),
7.43 (td, 4JHH = 1.2 Hz, 3JHH = 7.2 Hz, 1 H, C6H4), 7.40−7.36 (m, 4 H,
aromatic + NH), 7.33 (br d, 3JHH = 7.2 Hz, 1 H, C6H4), 7.31−7.27 (m,
3 H, Ph), 7.15−7.09 (m, 3 H, Ph), 7.02−6.98 (m, 3 H, Ph + p-H, Xy),
AUTHOR INFORMATION
Corresponding Author
*E-mail: jvs1@um.es (J.V.; http://www.um.es/gqo), p.jones@
tu-bs.de (P.G.J.).
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
We thank Ministerio de Educacion
(CTQ2007-60808/BQU), and Fundacion Seneca (04539/
GERM/06) for financial support and a grant to R.F.P.
■
́
y Ciencia (Spain), FEDER
́
REFERENCES
■
3
2
6.93 (d, JHH = 7.2 Hz, 2 H, m-H, Xy), 3.55, 3.37 (AB system, JHH
=
(1) Dupont, J.; Pfeffer, M. Palladacycles. Synthesis, Characterization
and Applications; Wiley-VCH: Weinheim, 2008. Dupont, J.; Consorti,
C. S.; Spencer, J. Chem. Rev. 2005, 105, 2527−2571. Beletskaya, I. P.;
Cheprakov, A. V. J. Organomet. Chem. 2004, 689, 4055−4082. Omae, I.
Coord. Chem. Rev. 2004, 248, 995−1023.
18.4 Hz, 2 H, CH2), 1.82 (s, 6 H, Me, Xy). 13C{1H} APT NMR (100.8
MHz, CDCl3): δ 167.1 (CO), 140.7 (C1, C6H4), 140.6 (C6H4CC),
139.5 (C6H4CC), 138.1 (C, Ph), 137.0 (C, Ph), 135.3 (o-C, Xy),
133.1 (i-C, Xy), 131.4 (C6, C6H4), 130.2 (CH, Ph), 129.9 (CH, Ph),
129.6 (C3, C6H4), 129.0 (C4, C6H4), 128.9 (C2, C6H4), 128.6 (C5 of
C6H4 + CH, Ph), 128.16 (CH, Ph), 128.13 (m-C, Xy), 128.0 (p-C,
Xy), 127.9 (CH, Ph), 127.2 (CH, Ph), 118.9 (CN), 22.5 (CH2), 18.3
(Me, Xy).
(2) Wu, G.; Rheingold, A. L.; Heck, R. F. Organometallics 1987, 6,
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Synthesis of [Pd{C(NXy)C(Et)C(Et)C6H4CH2CN-2}Cl-
(CNXy)2] (10). To a solution of 2ac (120 mg, 0.20 mmol) in dry
CH2Cl2 (15 mL) was added XyNC (108 mg, 0.82 mmol), and the
mixture was stirred for 15 h under an N2 atmosphere, whereupon a
dark red solution was obtained. Partial evaporation of the solvent (2
mL) and addition of n-pentane (15 mL) gave a red-orange oil, which
was extracted with a 1:5 CH2Cl2/n-pentane mixture (10 × 3 mL), and
the combined extracts were filtered through Celite. Evaporation of the
filtrate under reduced pressure and addition of Et2O (5 mL) and n-
pentane (5 mL) led to the formation of a colorless solid, which was
filtered off, washed with a 1:1 Et2O/n-pentane mixture (5 × 3 mL),
and vacuum-dried to give 10. Yield: 17 mg, 12%. Mp: 162−164 °C
(dec). Anal. Calcd for C41H43ClN4Pd: C, 67.12; H, 5.91; N, 7.64.
Found: C, 66.83; H, 6.33; N, 7.59. IR (Nujol, cm−1): ν(CN), 2203;
ν(CNXy), 2179; ν(CN), 1628. 1H NMR (400.9 MHz, CDCl3): δ
3
3
7.38 (d, JHH = 7.6 Hz, 1 H, Ar), 7.26 (t, JHH = 7.6 Hz, 2 H, p-H,
XyNCc), 7.20 (t, 3JHH = 7.6 Hz, 1 H, Ar), 7.11 (t, 3JHH = 7.6 Hz, 4 H,
m-H, XyNCc), 7.01 (t, 3JHH = 7.6 Hz, 1 H, Ar), 6.93 (d, 3JHH = 7.6 Hz,
1 H, Ar), 6.79 (br d, 3JHH = 7.6 Hz, 1 H, m-H, XyNCi), 6.72 (t, 3JHH
=
7.6 Hz, 1 H, p-H, XyNCi), 6.63 (br d, JHH = 7.6 Hz, 1 H, m-H,
3
XyNCi), 4.08, 3.83 (AB system, JHH = 18.4 Hz, 2 H, CH2), 3.26 (A
2
2
3
part of ABX3 system, JHH = 13.4 Hz, JHH = 7.6 Hz, 1 H, CH2CH3),
2.79 (B part of ABX3 system, JHH = 13.4 Hz, JHH = 7.6 Hz, 1 H,
(3) Maassarani, F.; Pfeffer, M.; Le, B. G. Organometallics 1987, 6,
2029−2043. Spencer, J.; Pfeffer, M. Tetrahedron: Asymmetry 1995, 6,
419−426.
2
3
2
3
CH2CH3), 2.49 (A part of ABX3 system, JHH = 14.0 Hz, JHH = 7.6
Hz, 1 H, CH2CH3), 2.41−2.32 (m, 13 H, B part of ABX3 system + Me,
XyNCc), 1.99 (br s, 3 H, Me, XyNCi), 1.65 (br s, 3 H, Me, XyNCi),
(4) Maassarani, F.; Pfeffer, M.; Le, B. G. Organometallics 1987, 6,
2043−2053.
3
3
1.39 (t, JHH = 7.6 Hz, 3 H, CH2CH3), 0.99 (t, JHH = 7.6 Hz, 3 H,
CH2CH3). 13C{1H} APT NMR (75.45 MHz, CDCl3): δ 149.3 (i-C,
XyNCi), 144.8 (ArCC), 141.6 (C, Ar), 135.5 (o-C, XyNCc), 133.8
(ArCC), 130.6 (C, Ar), 130.1 (p-C, XyNCc), 128.8 (CH, Ar), 128.4
(m-C, XyNCi), 128.1 (CH, Ar + m-C, XyNCc), 127.5 (CH, Ar), 127.4
(m-C, XyNCi), 127.3 (CH, Ar), 126.8 (o-C, XyNCi), 125.3 (br, i-C,
XyNCc), 123.1 (p-C, XyNCi), 118.9 (CN), 27.7, 25.3 (CH2CH3), 22.2
(CH2CN), 19.1 (Me, XyNCi), 18.8 (Me, XyNCc), 18.7 (Me, XyNCi),
14.1, 12.6 (CH2CH3); CN, one o-C of XyNCi, and CN of XyNCc
not observed.
(5) Gul, N.; Nelson, J. H.; Willis, A. C.; Rae, A. D. Organometallics
̈
2002, 21, 2041−2048. Vicente, J.; Saura-Llamas, I.; Turpín, J.; Bautista,
D.; Ramírez de Arellano, M. C.; Jones, P. G. Organometallics 2009, 28,
4175−4195.
(6) Zeni, G.; Larock, R. C. Chem. Rev. 2006, 106, 4644−4680.
(7) Majhi, T. P.; Achari, B.; Chattopadhyay, P. Heterocycles 2007, 71,
1011−1052. Shiina, I. Chem. Rev. 2006, 107, 239−273.
(8) Illuminati, G.; Mandolini, L. Acc. Chem. Res. 1981, 14, 95−102.
Maier, M. E. Angew. Chem., Int. Ed. 2000, 39, 2073−2077. Evans, P. A.;
Holmes, B. Tetrahedron 1991, 47, 9131−9166. Ma, S.; Gu, Z. J. Am.
Chem. Soc. 2006, 128, 4942−4943.
(9) Ohno, H.; Hamaguchi, H.; Ohata, M.; Kosaka, S.; Tanaka, T. J.
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ASSOCIATED CONTENT
■
S
* Supporting Information
Crystallographic data in CIF format for 2aa·2Et2O, 3aa, 3ac, 8,
9, and 10. This material is available free of charge via the
Internet at http://pubs.acs.org.
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