Studies on alkyl-nitrogen bond formation via reductive elimination from monomeric palladium complexes in high oxidation state

Article abstract of DOI:10.1002/hlca.201200430

Oxidation of a series of defined palladium(II) complexes bearing a bidentate ligand, and a methyl and an amidato substituent was carried out with the aim to gain a better understanding of the inherent requirements for C-N bond-formation from Pd complexes in high oxidation state. This work clarified the role of the individual nitrogen sources and has important implication for alkyl-nitrogen bond-forming reactions catalyzed by Pd. Copyright

Full text of DOI:10.1002/hlca.201200430

Helvetica Chimica Acta – Vol. 95 (2012)
2007
Studies on AlkylꢀNitrogen Bond Formation via Reductive Elimination from
Monomeric Palladium Complexes in High Oxidation State
a
a b
´
by Alvaro Iglesias ) and Kilian Mun˜iz* ) )
a) Institute of Chemical Research of Catalonia (ICIQ), Av. Paꢀsos Catalans 16, ES-43007 Tarragona
(phone: þ34977920813; fax: þ34977920224; e-mail: kmuniz@iciq.es)
b) Catalan Institution for Research and Advanced Studies (ICREA), Pg. Lluꢁs Companys 23,
ES-08010 Barcelona
Dedicated to Professor Dieter Seebach on the occasion of his 75th birthday
Oxidation of a series of defined palladium(II) complexes bearing a bidentate ligand, and a methyl
and an amidato substituent was carried out with the aim to gain a better understanding of the inherent
requirements for CꢀN bond-formation from Pd complexes in high oxidation state. This work clarified the
role of the individual nitrogen sources and has important implication for alkylꢀnitrogen bond-forming
reactions catalyzed by Pd.
Introduction. – Reductive elimination from PdII complexes represents a versatile
reaction to induce single-bond formation [1]. Several important catalytic coupling
reactions include this process as a key step [2]. In the area of Cꢀheteroatom bond
formation, the established BuchwaldꢀHartwig coupling consists of an aryl or alkenyl-
nitrogen bond-formation [3][4]. As a consequence, extensive work has been devoted
to the development of and the study on reductive elimination from amido-
palladium(II) complexes containing aryl groups [3]1). In sharp contrast to these
accomplishments, the reductive formation of alkylꢀN bonds from PdII complexes
represents an unsolved challenge in palladium chemistry, although there have been
attempts to this end [6a]2). As to a rare exception, Stahl and co-workers have reported
an example of CalkylꢀN bond-formation from Pd under oxidative conditions3).
Additional examples have become available, although no general reactivity has so
far been uncovered [8]4).
In the absence of general PdII-catalyzed alkylꢀN coupling reactions, development
of alternative approaches is warranted.
Over the past years, we have pioneered transition-metal catalysis for intramolecular
diamination of alkenes [10][11]. In most of these reactions, alkylꢀN bond-formation
1
)
)
For mechanistic studies on isolated palladium-amidate complexes, see [5].
For an attempt on reductive elimination of alkylamines from alkyl-amido-palladium complexes, see
[6b].
2
3
4
)
)
For a CalkylꢀN bond-formation from Pd under oxidative conditions, see [7].
For examples of Pd-catalyzed oxidative allylic CꢀH amidation, see [9].
ꢂ 2012 Verlag Helvetica Chimica Acta AG, Zꢃrich

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from a s-alkyl-Pd intermediate represents the second step of the overall process, and
we have introduced Pd high-oxidation-state catalysis5) for its realization [13].
In addition, we have recently approached the problem of Pd-catalyzed alkylꢀN
bond-formation as the final step of a sequential intermolecular diamination of alkenes
and have again developed suitable conditions in order to realize the final Csp3ꢀN bond
formation from high-oxidation-state PdIV intermediates (Scheme 1) [14 – 16]. These
reactions require electron-deficient N-atoms in order to be stable under oxidative
conditions and to be transferred from the coordination sphere of the PdIV intermediate.
Scheme 1. Palladium(II/IV)-Catalyzed Intermolecular Diamination of Alkenes
Based on extensive work, we have provided conclusive evidence for this step of
alkylꢀN bond formation from a PdIV intermediate to proceed through a transition state
reminiscent of an SN2 reaction [12]6). This scenario was deduced from D-labeling
studies in intramolecular diamination reactions [11b] as well as from a theoretical study
on PdII/IV-catalyzed CꢀH amidation reactions [18]. It is now a generally accepted
pathway for alkylꢀX bond formation from high-oxidation-state Pd intermediates [19].
Our ongoing efforts to develop an intermolecular diamination of alkenes require
precise knowledge on the nature of the individual nitrogen sources in alkylꢀN bond-
formation reactions. In particular, the involvement of two different N sources in the
regioselective diamination reactions from Scheme 1 poses the question on the role of
the individual N sources throughout the process. Obviously, the more acidic
bis(sulfonylimides) represent the preferred partners in the step of the PdIV-derived
5
)
)
For recent reviews on PdIV catalysis, see [12].
Such a scenario is reminiscent to related Pt intermediates in Shilov chemistry, see [17].
6

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alkylꢀN bond formation. To clarify this point, we embarked in a study on isolated
(alkyl)(amidato)palladium complexes, and we present here a more detailed inves-
tigation in order to uncover the role of the N group in reductive CꢀN bond-formation
from higher-oxidation-state Pd intermediates.
Results and Discussion. – In an attempt to study the context of Csp3ꢀN bond-
forming processes from defined Pd complexes, we prepared the dppf-ligated
(amidato)(methyl)palladium complexes 1a – 1f. Compounds 1a – 1f are most conven-
iently generated upon release of CH4 via protonolysis of the corresponding dimethyl
palladium precursor complex 2. Alternatively, they can be obtained upon treatment of
[PdCl(dppf)(Me)] (3) with a twofold excess of the amide salt. For example, complex 1b
can be synthesized in this way from 3 and potassium phthalimide in 98% isolated yield
(Scheme 2).
Scheme 2. Chemical Structures for (Amidato)(methyl)palladium Complexes 1a – 1f and Their Synthesis
from Dimethyl Palladium Complex 2 and Chloro Methyl Palladium Complex 3
All six complexes, 1a – 1f, proved stable toward several attempts to induce direct
reductive elimination under thermal conditions. This confirms that, for the present
complexes, CꢀN bond formation from (s-alkyl)(amidato)palladium(II) complexes is

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not a feasible process, which is in agreement with the behavior of related aryl
amidatoꢀPdII complexes [5a].
Two of the obtained products were characterized by X-ray analysis7). The resulting
structures are shown in Fig. 1. The structures display the expected square-planar
environment for the central PdII-atom, and very similar structural features regarding
comparable individual PdꢀN and PdꢀCmethyl bond lengths and angles.
Fig. 1. X-Ray crystal structures of [Pd(dppf)(Me)(phthalimide)] (1b) and [Pd(dppf)(Me)(saccharide)]
(1c). Selected bond lengths [ꢆ] and angles [8]: 1b: Pd1ꢀN1, 2.072(2); Pd1ꢀC9, 2.085(3); P1ꢀPd1,
2.3609(7); P2ꢀPd1, 2.2437(8); N1ꢀPd1ꢀC9, 84.45(10). 1c: Pd1ꢀN1, 2.094(4); Pd1ꢀC8, 2.122(5); P1ꢀPd1,
2.3854(14); P2ꢀPd1, 2.2387(14); N1ꢀPd1ꢀC8, 84.90(18).
Iodosobenzene Diacetate as Oxidant. Oxidation with PhI(OAc)2 was initially
investigated for the two isolated complexes 1b and 1c. As expected from our results on
alkene-diamination reactions [11a – 11c][14][16], adding 1 equiv. of this strong oxidant
induced oxidation at Pd to generate PdIV complexes from 1b and 1c. Especially, on the
basis of the similarities for 1b and 1c as observed in their respective X-ray
crystallographic structures, a similar reaction outcome was expected. However, the
reactions followed entirely different pathways and resulted in the formation of
completely different products. Complex 1b did not provide any CꢀN bond formation,
but rather led to exclusive formation of AcOMe. In contrast, complex 1c gave a single
product of CꢀN bond formation, which was identified as 2-methyl-2H-1l6,2-benzo-
thiazol-1,1,3-trione (¼ꢄmethyl saccharideꢅ) (Scheme 3). Based on its 31P-NMR signal,
the remaining PdII product was identified as [Pd(OAc)2(dppf)] which was isolated in
94% yield. This result suggests that oxidation with PhI(OAc)2 occurs chemoselectively
at the Pd-center8). Both the Fe- and the P-atoms of the dppf ligand remain untouched.
7
)
CCDC-693034 (for 1b) and CCDC-693035 (for 1c) contain the supplementary crystallographic data
for this article. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/
data_request/cif.
PhI(OAc)2 as oxidant has recently been key in the development of PdIV catalysis. See [12][19][20a –
20k]. For PdIII complexes, see [20l – 20n].
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Scheme 3. Oxidatively Induced Reductive Elimination of an AlkylꢀN Bond
Next, oxidation reactions on the whole set of compounds 1a – 1f were carried out. In
complete agreement with the earlier observation, a clear anion effect was observed,
and only the anions, whose corresponding acids present a pKa values below that of
AcOH provided the desired Csp3ꢀN coupling. Hence, while PdII complexes bearing
methyl N-tosyl carbamate, saccharide, dibenzenesulfonimide or di-p-toluenesulfona-
mide as the amide moiety smoothly afforded CꢀN coupling under oxidation with
PhI(OAc)2, the same complexes bearing phthalimide or succinimide moieties did not
promote this coupling. Instead, CꢀO formation was obtained owing to acetate transfer
from the oxidant (Table 1, Entries 1 and 2). With dibenzenesulfonimide or di-p-
toluenesulfonamide as amide, the reaction was complete after 10 min (Entries 5 and 6),
indicating that the higher the leaving-group character of the N-containing group is, the
faster the reaction proceeds. These results strongly underline the importance of the
amideꢅs leaving-group character for the successful realization of the CꢀN coupling.
Reactions compiled in Table 1 are expected to proceed through a discrete
octahedral PdIV intermediate A [21], which is generated from the square-planar PdII
precursors 1 upon oxidation with PhI(OAc)2 [12][19][20] (Scheme 4). In such a case,
reductive elimination can arise via previous dissociation of an acetate group, which
gives rise to the pentacoordinate PdIV intermediate B. As a result, acetate acts as the
nucleophile in the reductive functionalization of the Me group leading to formation of
AcOMe.
In contrast, for those cases in which the amide dissociates preferentially, the
resulting pentacoordinate PdIV intermediate C undergoes CꢀN bond formation to the
expected methylated amide as the coupling product. Since the alkyl amination
proceeds via an SN2-type transition state D, previous dissociation of the amide from the
Pd-center in A is a prerequisite. A related proposal was made by Goldberg and co-
workers for stoichiometric CꢀN bond formation via reductive elimination from a
(Me)(tosylamido)-PtIV complex [22].
Overall, the chemoselectivity of the CꢀN over the CꢀO bond formation can be
correlated to the dissociation tendency of the corresponding anion and, ultimately, to
the pKa of the corresponding protonated acid/amide. This is in agreement with the
observed selectivities in Table 1 [23]

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a
Table 1. Oxidation of Amidato(dppf)(methyl)palladium(II) Complexes 1a – 1f with PhI(OAc)2
)
Entry
1
Pd Complex
Parent amide
Time [min]
120
Product
1a
2
3
1b
1c
120
120
5c
4
5
1d
1e
120
10
5d
5e
6
1f
10
5f
a) Reaction conditions: [Pd(amidato)(dppf)(Me)] (0.5 mmol), PhI(OAc)2 (0.55 mmol), CH2Cl2
(0.7 ml), 258.
Scheme 4. Mechanistic Proposal for the PdIV-Mediated CꢀN Coupling from Pd Complexes 1

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However, detection of the relevant s-alkylꢀPdIV intermediates such as A has so far
remained elusive [18]9). For the carbamate complex 1d, 31P-NMR-spectroscopic
monitoring of the oxidation process revealed the clean formation of two new Pd
complexes, i.e., 6a (major) and 6b (minor). We tentatively assign these compounds as
PdIV-amidate intermediates 6a and 6b (Fig. 2), which proved too reactive for isolation.
Until ca. 60% conversion, oxidation of 1d to 6a and 6b was slower than reductive
elimination from 6a and 6b to palladium diacetate 4. During this period, however, the
ratio 6a/6b of the two isomers was not constant. It appears that isomer 6b reacts at a
faster rate than 6a. At ca. 80% conversion, no starting material 1d was left, and only
intermediate 6a remained, which subsequently formed additional product 4. After a
total reaction time of just 90 min, the signals of these intermediate completely vanished
1
and gave rise to those of the well-known complex 4. At this stage, the H-NMR only
displayed signals corresponding to 4 and free methyl N-methyl-N-tosylcarbamate (5d),
indicating that formation of the latter under oxidative conditions is indeed a feasible
and again completely selective process. Oxidation of 1d constitutes the first realization
of a successful observation on Csp3ꢀN bond formation from a discrete monomeric Pd
complex.
A series of three control experiments (Scheme 5) was carried out in order to
illustrate additional features of the stoichiometric coupling reactions. First, the reaction
is not influenced by external anions as deduced from an experiment with 15N labeling.
In this case, treatment of compound 1d-15N with iodosobenzene diacetate in the
presence of 4 equiv. of the sodium salt of unlabeled methyl N-tosylcarbamate gave rise
to the formation of the 15N-labeled coupling compound 5d-15N as the only a product.
This result demonstrates that the N-containing group in the coordination sphere of Pd
is transferred exclusively.
Scheme 5. Competition Experiments with Pd Complex 1d
Second, under these conditions the N-atoms also do not undergo exchange between
preformed Pd complexes. When compound 1d and the corresponding derivative 1g
bearing a CD3 substituent, and tert-butyl N-tosylcarbamate as N source were submitted
For isolated PdIV complexes with potential relevance to related catalytic aryl functionalization, see
[24].
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Fig. 2. 31P-NMR Monitoring of the Oxidation of 1d with Iodosobenzene Diacetate

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to oxidation, no cross-over products were formed, and only the three expected products
4, 5d, and 5g-D3 were obtained. This outcome provides strong evidence that the
involved PdIV intermediates are monomeric in nature10).
The situation may undergo a change for the case of less coordinating anions such as
bis(sulfonylimides). A second cross-over experiment between 1e and 1f-D3 led to an
equimolar mixture of all four CꢀN coupling products (Scheme 6).
Scheme 6. Labeling Experiments for Pd Complex 1e
Anion exchange in Pd complexes was then investigated by performing the oxidation
of this type of Pd compounds in the presence of an excess of a similar amide salt. Thus, a
CH2Cl2 solution of Pd complex 1f was added to 5 equiv. of potassium dibenzenesulfon-
imidate, and the resulting mixture was treated with PhI(OAc)2 (Scheme 6). The
reaction was complete after 10 min, and interestingly two different coupling products,
(PhSO2)2NMe (5e) and Ts2NMe (5f), were obtained in 4 :1 ratio. These results indicate
an equilibrium between amides before oxidation, suggesting that the anion exchange
would take place on PdII complexes rather than at the stage of the high oxidation state
PdIV complexes.
To study the influence of the amidato ligand on the oxidation process, a competition
experiment was carried out. Thus, complexes 1c and 1f were mixed in a 1:1 ratio and
reacted with a limiting amount of 1 equiv. of PhI(OAc)2 in CH2Cl2 at room temperature
(Scheme 7).
Scheme 7. Competitive Experiment Showing Oxidation Selectivity
10
)
This observation leads us to exclude bimetallic Pd catalysis, which so far has only been invoked in
non-related reductive Csp2ꢀheteroatom bond-formation [25]. For the discussion on PdIV
intermediates vs. dimeric PdIII intermediates in aryl functionalization, see [26].

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The maximum conversion of 50% was obtained, and the entire reaction proceeded
to completion within 20 min. Selective oxidation of only one of the complexes took
place, the other one remaining intact and leading to exclusive formation of Ts2NMe.
This indicates that complex 1f reacts with the oxidant much faster than the complex 1c.
Since the only difference between both complexes rests in the amide group utilized, it
can be concluded that the leaving-group character of the amide moiety plays again a
crucial role in the transformation. The better leaving group promotes faster and
selective alkyl-amide couplings, which is in agreement with the empirical rule that
cationic PdIV intermediates promote faster reductive elimination [12][21][27].
Since 1f reacts significantly faster in the reductive CꢀN bond forming reaction than
1c (cf., Table 1), we cannot definitely exclude a scenario of parallel oxidation of both 1f
and 1c, followed by subsequent oxidation of remaining 1f through the PdIV complex
originating from 1c. We consider such an event less likely due to the fact that 1c does
promote CꢀN bond formation under the given reaction conditions. However, it could
be demonstrated that, in the presence of a hexachloropalladate reagent, both 1c and 1f
undergo oxidation, followed by reductive CꢀN bond formation (Scheme 8). Due to the
low solubility of the hexachloropalladate salt, this process is slow and requires
significantly longer reaction times. Still, the reactions were found to be selective and
gave rise to the corresponding N-methylated products 5f and 5c, respectively. In both
cases, after the reaction [PdCl2(dppf)] (7) was indicated as the only dppf-ligated
product in the 31P-NMR spectrum of the crude reaction mixture11).
Scheme 8. Reductive CꢀN Bond Formation Promoted by [PdCl6]2ꢀ
Palladium(IV) catalyses are usually conducted without addition of a chelating
ligand12). To test the ligand scope of the present CꢀN bond-forming reaction, several
(dibenzene)(sulfinimidato)(methyl)palladium(II) complexes bearing bis(phosphine)
or even diamine ligands were synthesized and reacted with PhI(OAc)2. In all cases,
CꢀN coupling was mostly obtained indicating that the process is not dependant of the
11
)
Due to the incomplete yield, we cannot rule out formation of MeCl as minor coupling product,
which may arise from competing elimination or transmetallation processes, respectively.
For some exceptions, see [28]. For a recent report on PdIV catalysis emplying bis(phosphine) ligands,
see [29a]. However, this result was questioned by Kang and Gade, who suggested a metal-free acid-
promoted reaction to be operative in this case; see [29b].
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respective chelating bisphosphine ligand. When 1,2-bis(diphenylphosphino)benzene
and 1,2-bis(diphenylphosphino)ethane were employed, traces of AcOMe were formed
as side products (Table 2, Entries 2 and 3).
Table 2. Oxidation of (Dibenezenesulfonimidato)(methyl)palladium(II) Complexes Bearing Different
a
Ligands with PhI(OAc)2
)
Entry Pd Complex Ligand
Yield of MeꢀN(SO2Ph)2 (1e) [%]b) Yield of AcOMe [%]b)
1
1b
100
0
2
3
4
1h
1i
93
7
7
0
93
1j
100
a) Reaction conditions: 1 equiv. of (dibenzenedisulfonimidato)(methyl)PdII complex, 1 equiv. of
b
1
PhI(OAc)2, CD2Cl2 (0.6 ml), room temperature, 10 – 20 min. ) Yields based on H-NMR integration.
N-Fluorodibenzenesulfonimide ((PhSO2)2NF, NFSI) as Oxidant. This compound is
usually employed as a source for electrophilic fluorination [30]. However, as was
initially demonstrated by Michael and co-workers [31], it can also be used for oxidative
fluorination of a PdII center [32], upon which the remaining bis(sulfonimide) is
engaged in CꢀN bond formation. This concept was employed by Liu in the realization
of a PdII/IV-catalyzed aminofluorination of styrenes [33]13).
We had used NFSI as oxidant and N source in one of the intermolecular
diamination reactions [15]. To continue our study, oxidation reactions of several
amidato(methyl)palladium(II) complexes were performed in the presence of NFSI.
We observed selective formation of N-methyldibenzenesulfonimide (5e) as the only
coupling product of the reductive elimination. Again, these results validate the concept
of the leaving-group effect by which the anion transferred is the one presenting the
lowest coordinating ability in the PdIV transition state.
13
)
For the use of NFSI in a Pd-catalyzed fluorination of an arene, see [34].

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1
All reactions were monitored by H- and 31P-NMR indicating the presence of
selective CꢀN coupling products at the end of the reaction. Hence, employing this
oxidant and using dppf as ligand and succinimide as the amide group, N-methyl-
bis(phenylsulfonyl)imide (5e) was obtained in nearly quantitative yield (Table 3, Entry
1). Changing succinimide by phthalimide or saccharine resulted in formation of the
same product in up to 90% isolated yield (Entries 2 and 3). Dibenzenesulfonimidato
complex 1e afforded the product in quantitative yield (Entry 4). For the bis(tosyl)
derivative 1f, a mixture of two products was obtained, which corresponds to the similar
anion strengths of the two bis(sulfonylimides) (Entry 5). The favored formation of 5e
over 5f may be the result of a kinetic preference after formation of the fluorinated PdIV
intermediate [18]. In these five cases, the PdII species that results from the reductive
elimination could not be identified. This compound exhibits a pronounced singlet in
31P-NMR and presents signals with similar shifts at ca. 26 ppm in all five cases. It is
expected that the product should be the dppf-ligated monofluoride complex
incorporating the initial (amidato)palladium ligand. Palladium fluoride complexes
are usually of problematic stability14), and no efforts were made to further substantiate
their nature in the present study. With bipy as ligand, selective and quantitative Csp3ꢀN
coupling was also achieved in both cases (Entries 5 and 6).
a
Table 3. Oxidative Csp3ꢀN Coupling Promoted by FꢀN(PhSO2)2
)
Entry
Pd Complex
Ligand
Amide
Product
1
2
3
4
5
6
7
1a
1b
1c
1e
1f
1k
1l
dppf
dppf
dppf
dppf
dppf
bipy
bipy
succinimide
phthalimide
saccharine
dibenzenesulfonimide
bistosylimide
phthalimide
saccharine
MeꢀN(SO2Ph)2
MeꢀN(SO2Ph)2
MeꢀN(SO2Ph)2
MeꢀN(SO2Ph)2
MeꢀN(SO2Ph)2
MeꢀN(SO2Ph)2
MeꢀN(SO2Ph)2
b
)
a) Reaction conditions: 1 equiv. of (amidato)(methyl)PdII complex, 1 equiv. of NFSI, CD2Cl2 (0.6 ml),
room temperature, 24 h. b) A mixture of MeꢀN(PhSO2)2 and MeꢀNTs2 in ratio 1.5 : 1 was obtained.
In a final experiment, a 1:1 mixture of complex 1c and its CD3 derivative 1c-D3
were oxidized with NFSI to give the expected product N-methylbis(phenylsulfonyl)-
imide (5e) in 94% yield (Scheme 9). The product shows a 50% deuteration level
indicating that both Pd complexes reacted at comparable rate. The absence of any
detectable secondary isotope effect in the reductive CꢀN bond formation confirms that
this final step is not the rate-limiting event. This is in agreement with the outcome of
our earlier calculations on a related CꢀN bond formation from a s-benzyl-PdIV
intermediate.
14
)
The stability of palladium fluoride complexes is often problematic. For a discussion, see [35].

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Scheme 9. Absence of a Secondary Isotope Effect in Reductive CꢀN Bond Formation
For reactions with NFSI, the selectivity in favor of the bis(phenylsulfonyl)imide
anion as nucleophile in the CꢀN bond formation should also apply to reaction of Pd
complexes with incorporated anions other than amidato groups.
In a final set of reactions, three PdII complexes without coordinated amidato group
were investigated. For dppf-ligated methyl-palladium complexes 1m – 1o bearing
additional Me, Cl, and AcO groups, respectively, oxidation with NFSI again only
furnished the CꢀN bond-formation product 5e (Scheme 10). The example of complex
1m is particularly interesting, as dimethyl complexes of PdIV are usually known to
undergo reductive CꢀC bond formation to release ethane [21]. However, in the present
case, the CꢀN bond formation represents the preferred pathway.
Scheme 10. CꢀN Bond Formation from Palladium Complexes 1m – 1o
These results unambiguously indicate that no prior incorporation of the N
nucleophile into the coordination sphere of Pd is required for the CꢀN bond-forming
event.
Conclusions. – We have investigated a series of defined PdII complexes containing
different amidato ligands in the oxidative CꢀN bond formation upon oxidation with
PhI(OAc)2 and NFSI. Upon formation of PdIV intermediates, different behavior in
reductive elimination was observed, depending on the nature of the N-containing
ligand. For oxidation with PhI(OAc)2, the chemoselectivity of the CꢀN bond formation
over the CꢀO bond formation can be correlated to the dissociation tendency of the
corresponding anion and, ultimately, to the pKa of the corresponding conjugated acid/
amide.
For NFSI as oxidant, the bis(sulfonylimide) anion usually outperforms all other N-
containing groups in the CꢀN bond formation, ensuring complete selectivity.
These results are of high importance to rationalize our reagent combination for
intermolecular regioselective diamination of alkenes. They demonstrate that, regard-
less of the nature of the s-alkyl-palladium intermediate that originates from amino-
palladation, the second step of CꢀN bond formation will always occur selectively. This
selectivity arises from the preferential role of a bis(sulfonimide) as nucleophile in the

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CꢀN bond formation from a PdIV catalyst state. The presence of alternative N-
containing groups as potentially competing nucleophiles does not interfere at this stage.
The authors thank the Fonds der Chemischen Industrie, ICIQ Foundation, ICREA, and the Spanish
Ministry for Economy (CTQ2011-25027) for financial support. Dr. Lydia Brelot (Strasbourg University)
is acknowledged for the X-ray structure analyses. Part of this work is taken from the Ph.D. Thesis of A. I.
[36].
Experimental Part
General. Abbreviations: bipy: 2,2’-bipyridine, dppf: 1,1’-bis(diphenylphosphino)ferrocene, hfacac:
hexafluoroacetylacetonate, HNPhthal: phthalimide, HNSacc: saccharin, NFSI: N-fluorobenzenesulfo-
nimide.
All org. reagents, if not noted otherwise, were purchased from Acros. Palladium salts were purchased
from Strem. CH2Cl2 was dried over CaCl2 and distilled from CaH2. Column chromatography (CC): silica
gel (SiO2; Merck, type 60, 0.063 – 0.2 mm). Reactions were monitored by TLC carried out on 0.25 mm E.
Merck silica gel plates (60F-254) using UV light as visualizing agent and 10% ethanolic phosphomolybdic
acid or ninhydrin soln. and heat as developing agents. IR Spectra: Thermo Scientific Nicolet 6700 FT-IR
spectrometer (smart orbit Diamond). NMR Spectra: Bruker Avance 400 MHz, Bruker DPX 300 MHz,
and Bruker DRX 500 MHz spectrometers; chemical shifts in ppm downfield from TMS; the following
calibrations were used: CDCl3 d(H) 7.26 and d(C) 77.00 ppm, and CD2Cl2 d(H) 5.32 and d(C) 53.80 ppm,
the 15N-NMR spectrum of 1d was recorded with Me15NO2 as external standard. LC/ESI-MS: Agilent 1100
HPLC with a Bruker micro-TOF instrument; unless otherwise stated, a Supelco C8 (5 cm ꢁ 4.6 mm, 5 mm
particules) column was used with an linear elution gradient from 100% H2O (0.5% HCO2H) to 100%
MeCN in 13 min at a flow rate of 0.5 ml/min. EI- and HR-EI-MS: Kratos MS 50 at the service centers of
´
the Kekule-Department, Bonn University, and Bruker Daltonik Autoflex II TOF/TOF spectrometer.
Synthesis of (Amidato)(methyl)palladium Complexes 1. Complexes 1a – 1f were synthesized by
reaction of equimolar amounts free amides and the known complex [Pd(dppf)Me2] [37]. In a typical
experiment, [Pd(dppf)Me2] (1.0 mmol) was dissolved in 4 ml of freshly dist. CH2Cl2 under N2.
Subsequently, the respective amide (1.0 mmol, 1 equiv.) was added slowly over a period of several min
under stirring. The reaction required 1 h for complexes 1c and 1d, 14 h for 1a and 1b, and proceeded
within minutes for 1e and 1f. After that period, the volume of the soln. was reduced, and the product was
precipitated by addition of 3 ml of freshly dist. Et2O. The resulting complexes were dried under reduced
pressure and recrystallized from CH2Cl2/Et2O mixture where required.
cis-Methyl(succinimidato)[1,1’-bis(diphenylphosphino)ferrocene]palladium(II) (1a). Light orange
solid. Yield: 95%. IR: 3412, 3052, 2975, 1712, 1618, 1481, 1435, 1353, 1281, 1265, 1243, 1166, 1097, 734, 697.
1H-NMR (400 MHz, CD2Cl2): 0.45 (dd, J ¼ 7.0, 5.2, 3 H); 1.59 (dd, J ¼ 12.0, 4.6, 2 H); 2.12 (dd, J ¼ 12.0,
4.6, 2 H); 3.59 (s, 2 H); 4.12 (s, 2 H); 4.51 (s, 2 H); 4.85 (s, 2 H); 7.25 (t, J ¼ 7.0, 4 H); 7.36 (t, J ¼ 7.0, 2 H);
7.51 – 7.56 (m, 10 H); 7.84 – 7.89 (m, 4 H). 13C-NMR (100 MHz, CD2Cl2): 9.5 (d, J ¼ 100.4); 31.9; 71.9 (d,
J ¼ 6.1); 73.1 (d, J ¼ 77.3); 74.0 (d, J ¼ 6.9); 75.0 (d, J ¼ 9.2); 77.0 (d, J ¼ 13.0); 128.1 (d, J ¼ 9.2); 128.8
(d, J ¼ 11.5); 130.3; 131.0; 132.8 (d, J ¼ 49.0); 134.4 (d, J ¼ 13.8); 134.9 (d, J ¼ 12.2); 135.4 (d, J ¼ 36.0);
188.5. 31P-NMR (121 MHz, CD2Cl2): 21.31 (d, J ¼ 28.3); 34.33 (d, J ¼ 28.2). HR-ESI-MS: 796.0441
([M þ Na]þ, C39H35FeNNaO2P2Pdþ; calc. 796.0425).
cis-Methyl(phthalimidato)[1,1’-bis(diphenylphosphino)ferrocene]palladium(II) (1b). Yellow solid.
1
Yield: 99%. IR: 3054, 2363, 2346, 1648, 1436, 1371, 1304, 1130, 720, 695. H-NMR (400 MHz, CD2Cl2):
0.54 (s, 3 H); 3.67 (s, 2 H); 4.14 (s, 2 H); 4.51 (s, 2 H); 4.84 (s, 2 H); 7.03 – 7.09 (m, 6 H); 7.25 – 7.29 (m,
4 H); 7.47 – 7.54 (m, 10 H); 7.93 (br. s, 4 H). 13C-NMR (100 MHz, CD2Cl2): 9.5 (d, J ¼ 95.2); 72.0 (d, J ¼
6.0), 74.0 (d, J ¼ 6.8), 75.0 (d, J ¼ 9.1), 76.9 (d, J ¼ 12.1), 120.3, 128.0 (d, J ¼ 9.9); 128.8 (d, J ¼ 10.6);
130.0; 130.7; 131.0; 132.5; 133.0; 134.3 (d, J ¼ 12.9); 134.7; 135.0 (d, J ¼ 12.9); 135.1; 138.1 (d, J ¼ 3.8);
178.8. 31P-NMR (121 MHz, CD2Cl2): 19.28; 33.35. HR-ESI-MS: 844.0419 ([M þ Na]þ,
C43H35FeNNaO2P2Pdþ; calc. 844.0425).
Complex 1b was recrystallized from CH2Cl2 to give suitable crystals for X-ray single crystal
diffraction. Data were collected with a Nonius KappaCCD diffractometer. C43H35FeNO2P2Pd · 2 CH2Cl2,

Helvetica Chimica Acta – Vol. 95 (2012)
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ꢀ
Mr 991.76, triclinic, P1, a ¼ 9.5996(3), b ¼ 13.9609(6), c ¼ 17.1652(7) ꢆ, a ¼ 89.668(2)8, b ¼ 77.079(2)8,
g ¼ 71.674(2)8, V¼ 2123.32(14) ꢆ3, Z ¼ 2, T ¼ 123 K, m(MoKa) ¼ 0.71073, 22625 reflections, 9073 unique
reflections (2qmax ¼ 508), R1 ¼ 0.0503 [I > 2s(I)], wR2 ¼ 0.0866 (all data), 506 parameters and 0
restraints. Empirical absorption correction was applied7).
cis-Methyl(saccharinato)[1,1’-bis(diphenylphosphino)ferrocene]palladium(II) (1c). Orange solid.
Yield: 99%. IR: 2966, 1665, 1431, 1434, 1282, 1253, 1167, 1153, 1148, 1120, 1092, 1026, 975, 744, 695, 676.
1H-NMR (400 MHz, CD2Cl2): 0.78 (dd, J ¼ 4.4, 7.3, 3 H); 3.54 (br. s, 32 H); 4.06 (br. s, 32 H); 4.43 (br. s,
32 H); 4.71 (br. s, 32 H); 6.90 – 6.96 (m, 4 H); 7.00 – 7.05 (m, 2 H); 7.21 – 7.38 (m, 4 H); 7.43 – 7.52 (m,
10 H); 7.79 – 7.85 (m, 4 H). 13C-NMR (100 MHz, CD2Cl2): 11.9 (d, J ¼ 90.5); 72.3 (d, J ¼ 6.1); 74.1 (d,
J ¼ 6.9); 75.0 (d, J ¼ 9.2); 76.9 (d, J ¼ 12.2); 116.8; 119.3; 123.3 (d, J ¼ 8.4); 127.7 (d, J ¼ 9.9); 128.7;
128.9 (d, J ¼ 11.5); 130.1 (d, J ¼ 1.5); 131.2 (d, J ¼ 2.3); 132.4 (d, J ¼ 52.9); 134.5; 134.9 (d, J ¼ 13.0);
135.07 (d, J ¼ 13.8); 166.0. 31P-NMR (CD2Cl2, 121 MHz): 19.0 (d, J ¼ 17.8, 1 P); 35.8 (d, J ¼ 17.8, 1 P).
HR-ESI-MS: 675.0138 ([M ꢀ C6H4NO3S]þ, C35H31FeP2Pdþ; calc. 675.0285).
Complex 1c was recrystallized from CH2Cl2 to give suitable crystals for X-ray single-crystal
diffraction. Data were collected with a Nonius KappaCCD diffractometer. C42H35FeNO3P2PdS · CH2Cl2,
Mr 942.89, monoclinic, P21/c, a ¼ 17.5980(6), b ¼ 12.1880(5), c ¼ 18.7924(5) ꢆ, b ¼ 95.567(2)8, V¼
4011.7(2) ꢆ3, Z ¼ 4, T¼ 123 K, m(MoKa) ¼ 0.71073, 29856 reflections, 9180 unique reflections (2qmax
¼
508), R1 ¼ 0.0587 [I > 2s(I)], wR2 ¼ 0.1371 (all data), 488 parameters and 0 restraints. Empirical
absorption correction was applied7).
cis-[1,1’-Bis(diphenylphosphino)ferrocene](Methoxycarbonyl)(tosyl)amino](methyl)palladium(II)
(1d). Orange solid. Yield: 99%. IR: 3051, 1685, 1481, 1434, 1300, 1284, 1256, 1182, 1165, 1145, 1097, 1079,
1027, 881, 815, 747, 695, 662. 1H-NMR (CD2Cl2, 500 MHz): 0.66 (dd, J ¼ 4.4, 7.0, 3 H); 2.31 (s, 3 H); 3.30
(s, 3 H); 3.70 (br. s, 2 H); 4.19 (br. s, 2 H); 4.55 (br. s, 2 H); 4.74 (br. s, 2 H); 7.09 (d, J ¼ 7.9, 2 H); 7.15 –
7.34 (m, 2 H); 7.36 – 7.45 (m, 4 H), 7. 55 – 7.68 (10 H); 7.67 (d, J ¼ 7.9, 2 H); 7.95 – 8.05 (m, 4 H). 13C-NMR
(CD2Cl2, 100 MHz): 12.7 (dd, J ¼ 3.1, 94.3); 21.1; 51.5; 72.0 (br. s); 73.2 (d, J ¼ 5.4); 74.6 (d, J ¼ 9.2);
76.3 (d, J ¼ 8.5); 79.4 (dd, J ¼ 9.2, 54.0); 127.9 (d, J ¼ 9.2); 128.2 (d, J ¼ 2.3); 128.4, 128.50, 130.0 (br. m);
130.8; 134.6 (d, J ¼ 12.3); 141.2 (d, J ¼ 15.3); 157.2. 31P-NMR (CD2Cl2, 121 MHz): 18.0 (d, J ¼ 19.8, 1 P);
37.1 (d, J ¼ 19.8, 1 P). HR-ESI-MS: 926.0524 ([M þ Na]þ, C44H41FeNNaO4P2PdSþ; calc. 926.0514).
Synthesis of 15N-labeled methyl N-tosyl carbamate was carried out starting from 15NH4NO3
(Eurisotope; 98% isotopic purity) as described in [9c][38]. Reaction with [Pd(dppf)Me2] as described
above gave 1d-15N in 99% yield. 15N-NMR (CD2Cl2, 75 MHz): ꢀ 254 (s, 1 N). HR-ESI-MS: 904.0594
(C44H41Fe15NO4P2106PdSþ; calc. 904.0586).
cis-[1,1’-Bis(diphenylphosphino)ferrocene][(methoxycarbonyl)(tosyl)amino][(D2)methyl]palladium
(II) (1d-D3). IR: 3406, 3054, 2979, 1732, 1374, 1265, 1131, 1045, 736, 704. 1H-NMR (400 MHz, CD2Cl2):
2.31 (s, 3 H); 3.24 (s, 3 H); 3.65 (br. s, 2 H); 4.14 (s, 2 H); 4.50 (s, 2 H); 4.68 (s, 2 H); 7.04 (s, 2 H); 7.22 (br.
s, 2 H); 7.35 (s, 2 H); 7.54 – 7.60 (m, 12 H); 7.93 (br. s, 4 H). 31P-NMR (121 MHz, CD2Cl2): 17.85 (d, J ¼
20.8); 37.28 (d, J ¼ 20.8).
cis-[1,1’-Bis(diphenylphosphino)ferrocene](di-p-toluenedisulfinimidato)(methyl)palladium(II) (1f).
Orange-red solid. Yield: 99%. IR: 3853, 3055, 1494, 1481, 1436, 1317, 1278, 1152, 1133, 1082, 1055, 998,
955, 812, 748, 696, 667. 1H-NMR (400 MHz, CD2Cl2): 0.63 (br. s, 3 H); 2.31 (s, 6 H); 3.48 (br. s, 2 H); 4.14
(s, 2 H); 4.50 (s, 2 H); 4.72 (br. s, 2 H); 6.99 (br. s, 4 H); 7.22 (br. s, 4 H); 7.35 (s, 4 H); 7.38 – 7.42 (m, 4 H);
7.53 (br. s, 5 H); 7.66 (t, J ¼ 8.7, 4 H); 7.84 (br. s, 3 H). 31P-NMR (121 MHz, CD2Cl2): 17.41(d, J ¼ 23.7);
37.44 (d, J ¼ 23.7). HR-ESI-MS: 886.0595 ([M þ Na]þ, C43H37NNaO2P2PdS2þ ; calc. 886.0572).
cis-[1,1’-Bis(diphenylphosphino)ferrocene]{[(tert-butoxy)carbonyl](tosyl)amino}[(D3)methyl]pal-
ladium(II) (1g-D3). Yellow solid. Yield: 99%. IR: 3395, 3054, 2979, 1734, 1674, 1436, 1265, 1165, 1142,
1096, 1070, 736, 702. 1H-NMR (400 MHz, CD2Cl2): 1.34 (s, 9 H); 2.30 (s, 3 H); 3.39 (br. s, 1 H); 3.59 (br. s,
1 H); 4.10 (s, 2 H); 4.50 (br. s, 1 H); 4.57 (br. s, 1 H); 7.02 (d, J ¼ 7.3, 2 H); 7.09 (br. s, 2 H); 7.27 – 7.35 (m,
4 H); 7.54 (s, 10 H); 7.65 (br. s, 2 H); 7.83 – 7.92 (m, 4 H). 13C-NMR (CD2Cl2, 100 MHz): 12.8 (m); 21.3;
28.4; 51.5; 72.0 (br. s); 73.2 (d, J ¼ 5.5); 74.7 (d, J ¼ 9.1); 76.3 (d, J ¼ 8.5); 79.2; 79.5 (dd, J ¼ 9.1, 54.0);
128.0 (d, J ¼ 9.1); 128.5 (d, J ¼ 2.4); 128.5; 128.6; 129.9 (br. m); 130.4; 134.7 (d, J ¼ 12.2); 141.1 (d, J ¼
15.2); 157.4. 31P-NMR (121 MHz, CD2Cl2): 17.95 (d, J ¼ 17.8); 38.02 (d, J ¼ 17.8).
cis-[1,2-Bis(diphenylphosphino)benzene](dibenzenesulfinimidato)palladium(II) (1h). White solid.
Yield: 99%. IR: 3056, 2923, 1733, 1481, 1445, 1436, 1318, 1306, 1265, 1157, 1139, 1097, 1080, 1025, 1001,

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Helvetica Chimica Acta – Vol. 95 (2012)
964, 871, 733, 690, 669. 1H-NMR (400 MHz, CD2Cl2): 0.58 (dd, J ¼ 7.9, 2.3, 3 H); 7.12 (t, J ¼ 7.6, 4 H); 7.31
(t, J ¼ 7.6, 3 H); 7.34 – 7.37 (m, 3 H); 7.41 – 7.45 (m, 8 H); 7.49 (d, J ¼ 7.3, 6 H); 7.52 – 7.63 (m, 10 H).
13C-NMR (100 MHz, CD2Cl2): 12.4 (d, J ¼ 94.3); 128.1; 128.9 (d, J ¼ 9.9); 129.2 (d, J ¼ 11.5); 130.2 (d,
J ¼ 55.9); 130.8; 131.3; 131.5; 131.6; 131.8; 133.2 (d, J ¼ 111.9); 134.0 (d, J ¼ 12.2); 134.5 (d, J ¼ 13.0);
143.9. 31P-NMR (121 MHz, CD2Cl2): 38.25 (d, J ¼ 13.8); 55.86 (d, J ¼ 13.8). HR-ESI-MS: 567.0639
([M ꢀ C12H10NO4S2]þ, C31H27P2Pdþ; calc. 567.0623).
cis-[1,2-Bis(diphenylphosphino)ethane](dibenzenesulfinimidato)(methyl)palladium(II) (1i). White
solid. Yield: 99%. IR: 3055, 2360, 1436, 1264, 1139, 1080, 966, 871, 735, 703. 1H-NMR (400 MHz, CD2Cl2):
0.51 (dd, J ¼ 7.6, 2.3, 3 H); 2.07 – 2.13 (m, 1 H); 2.14 – 2.24 (m, 2 H); 2.25 – 2.32 (m, 1 H); 7.12 (t, J ¼ 7.6,
4 H); 7.30 (t, J ¼ 7.6, 2 H); 7.44 (td, J ¼ 7.6, 1.7, 4 H); 7.48 – 7.57 (m, 12 H); 7.71 – 7.78 (m, 8 H). 13C-NMR
(100 MHz, CD2Cl2): 10.7 (d, J ¼ 94); 26.0 (dd, J ¼ 26.0, 9.9); 29.3 (dd, J ¼ 32.9, 21.4); 128.1 (d, J ¼ 6.9),
129.1 (d, J ¼ 9.9); 129.3 (d, J ¼ 11.5); 129.8 (d, J ¼ 54.4); 131.1 (d, J ¼ 1.5); 131.3; 131.8 (d, J ¼ 2.3);
132.3 (d, J ¼ 27.6); 133.9 (d, J ¼ 11.5); 134.2 (d, J ¼ 12.2); 143.7. 31P-NMR (121 MHz, CD2Cl2): 34.25 (d,
J ¼ 11.8); 57.62 (d, J ¼ 11.8). HR-ESI-MS: 519.0627 ([M ꢀ C12H10NO4S2]þ, C27H27P2Pdþ; calc.
519.0623).
cis-(2,2’-Bipyridine)(dibenzenesulfinimidato)(methyl)palladium(II) (1j). White-off solid. Yield:
99%. IR: 3061, 2985, 2883, 1599, 1472, 1445, 1323, 1306, 1161, 1143, 1081, 1025, 950, 834, 761, 731, 688.
1H-NMR (400 MHz, CD2Cl2): 0.68 (s, 3 H); 7.32 (t, J ¼ 6.4, 1 H); 7.38 (t, J ¼ 7.6, 4 H); 7.49 (t, J ¼ 7.6,
2 H); 7.53 (dd, J ¼ 5.8, 1.1, 1 H); 7.94 (d, J ¼ 7.6, 4 H); 8.07 – 8.09 (m, 2 H); 8.15 (d, J ¼ 7.8, 2 H); 8.48 (d,
J ¼ 5.0, 1 H); 8.54 (d, J ¼ 5.0, 1 H). 13C-NMR (100 MHz, CD2Cl2): 1.9; 121.8; 123.2; 126.7; 126.8; 128.4;
128.5; 132.0; 139.1; 139.6; 143.9; 149.5; 150.3; 157.9. HR-ESI-MS: 276.9963 ([M ꢀ C12H10NO4S2]þ,
C11H11N2Pdþ; calc. 276.9957).
cis-(2,2’-Bipyridine)(Methyl)(phthalimidato)palladium(II) (1k). Yellow solid. Yield: 90%. IR: 2845,
1650, 1624, 1598, 1468, 1442, 1359, 1302, 1118, 753, 730. 1H-NMR (400 MHz, CD2Cl2): 0.68 (s, 3 H); 7.28
(dd, J ¼ 7.6, 0.8, 1 H); 7.45 – 7.49 (m, 1 H); 7.55 – 7.57 (m, 2 H); 7.66 – 7.68 (m, 2 H); 7.89 (td, J ¼ 7.8, 1.4,
1 H); 8.07 (td, J ¼ 7.8, 1.4, 1 H); 8.13 – 8.15 (m, 1 H); 8.25 (d, J ¼ 8.2, 1 H); 8.36 (d, J ¼ 8.2, 1 H); 8.50 (d,
J ¼ 4.6, 1 H). 13C-NMR (100 MHz, CD2Cl2): ꢀ 1.7; 121.1; 122.5; 123.5; 126.5; 126.7; 131.9; 137.7; 139.1;
139.5; 149.1; 153.4; 157.1; 180.0. HR-ESI-MS: 446.0091 (C19H15N3NaO2Pdþ; calc. 446.0096).
cis-(2,2’-Bipyridine)(Methyl)(saccharinato)palladium(II) (1l). White solid. Yield: 99%. IR: 3054,
1667, 1598, 1446, 1297, 1264, 1170, 1148, 1128, 966, 766, 735, 704, 678. 1H-NMR (400 MHz, CD2Cl2): 0.91
(s, 3 H); 7.39 (pseudo-t, J ¼ 6.5, 1 H); 7.55 (td, J ¼ 7.0, 1.1, 1 H); 7.70 (dd, J ¼ 5.2, 3.5, 2 H); 7.83 – 7.85 (m,
1 H); 7.87 – 7.89 (m, 1 H); 7.95 (td, J ¼ 7.0, 1.4, 1 H); 8.12 – 8.17 (m, 2 H); 8.29 (d, J ¼ 8.1, 1 H); 8.52 (dd,
J ¼ 5.2, 0.8, 1 H); 8.59 (d, J ¼ 5.2, 1 H). 13C-NMR (100 MHz, CD2Cl2): ꢀ 0.9, 122.6, 122.7, 123.8, 125.9,
126.3, 126.4, 127.5, 128.5, 137.7, 137.8, 138.9, 139.1, 139.5, 149.2, 156.4, 157.4, 172.5. HR-ESI-MS: 276.9971
([M ꢀ C7H4NO2S]þ, C11H11N2Pdþ; calc. 276.9957).
Representative Oxidation Reaction with PhI(OAc)2. The respective PdII complex 1 (0.5 mmol) was
dissolved in CH2Cl2 (1.5 ml) and stirred under N2. Solid PhI(OAc)2 (161 mg, 0.5 mmol, 1 equiv.) was
added in one portion, and the reaction was followed by TLC or 31P-NMR (for determination of reaction
times, cf. Table 1). After full conversion of all starting material 1, the volume of the reaction was reduced.
Addition of Et2O led to precipitation of the PdII residues and allowed extraction of the methylated amide
product. Purification by chromatography (SiO2, hexane/AcOEt, 3 :1, v/v) gave the products 5 in anal.
pure form. Compounds 5a – 5g are known [39]. The Pd product [Pd(OAc)2(dppf)] was identified by its
1H- and 31P-NMR spectrum [40].
Treatment of the complex 1c-15N with 2 equiv. of PhI(OAc)2 in CH2Cl2 in the presence of 4 equiv. of
sodium methyl N-tosyl carbamate gave rise to a dark red soln. within 2 h (31P-NMR control). AcOEt and
an aq. thiosulfate soln. were added, and the resulting mixture was stirred for 5 min. The org. phase was
separated, and the aq. one was extracted with AcOEt. The combined org. phases were washed with brine
and H2O, dried, and evaporated to dryness. CC (SiOl2; AcOEt/hexanes, 1:2 (v/v)) gave the coupling
product in analytically pure form matching the NMR data for the unlabelled compound. Isomeric purity
was confirmed by a MALDI experiment. HR-MALDI-MS: 244.0540 (C10H1315NO4Sþ; calc. 244.0536).
Representative Oxidation Reaction with NFSI. The respective PdII complex 1 (0.5 mmol) was
dissolved in CH2Cl2, and the mixture was stirred under N2. Solid NFSI (158 mg, 0.5 mmol, 1 equiv.) was
added in one portion, and the reaction was usually terminated after 10 min. After full conversion of all

Helvetica Chimica Acta – Vol. 95 (2012)
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starting material 1, the volume of the reaction was reduced. Addition of Et2O led to precipitation of the
PdII residues and allowed extraction of the methylated amide product 5e.
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Received August 8, 2012