Hydrophilic Pd0 complexes based on sugars for efficient suzuki-miyaura coupling in aqueous systems

Article abstract of DOI:10.1002/ejic.201402456

Two classes of hydrophilic Pd⁰ complexes containing P,N and N,N sugar-based ligands were prepared and tested in the Suzuki-Miyaura cross-coupling reaction under environmentally friendly aqueous conditions. The best catalyst was tolerant towards

Full text of DOI:10.1002/ejic.201402456

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DOI:10.1002/ejic.201402456
0
Hydrophilic Pd Complexes Based on Sugars for Efficient
Suzuki–Miyaura Coupling in Aqueous Systems
[
a]
[a]
[a]
Giulia Tarantino, Massimiliano Curcio, Andrea Pica,
[a]
[a]
[a]
Andrea Carpentieri, Maria E. Cucciolito, Francesco Ruffo,
[
a]
[a]
Aldo Vitagliano, and Matteo Lega*
Keywords: Synthetic methods / Green chemistry / Cross-coupling / N ligands / Palladium
0
Two classes of hydrophilic Pd complexes containing P,N and
N,N sugar-based ligands were prepared and tested in the
Suzuki–Miyaura cross-coupling reaction under environmen-
tally friendly aqueous conditions. The best catalyst was toler-
ant towards different substrates, and its activity is compar-
able with the highest values reported so far for reactions in
aqueous media [loading 0.0010%, turnover frequency (TOF)
–
1
3.5ϫ104 h ].
Introduction
ligands with the desired coordinating motifs. Moreover, as
the chemistry of carbohydrates is well developed, it is easy
Over the last few years, carbohydrates have been widely em- to fine tune the chemical–physical properties to make the
ployed as ligand backbones in the field of homogeneous ligands selectively soluble in desired green solvents, such as
metal-promoted catalysis.[ This choice is motivated by the water or ionic liquids.
1]
[2]
high versatility of these natural molecules; the inexpensive
Although sugar-derived ligands have been applied in sev-
natural precursors are easily functionalized to yield chiral eral catalytic C–C and C–X bond formations (X = O, N, S,
Figure 1. The complexes used in this work. The label of the ligands indicates the donor atoms (PN or NN), the sugar (G = glucose, M
mannose) and the position of the imino function within the sugar ring (1, 2 or 6). The asterisk means that the hydroxy groups are
deprotected; fdn = fumarodinitrile.
=
[
a] Dipartimento di Scienze Chimiche, Università di Napoli
P),[1] their scope has not been extended comprehensively
“
Federico II”, Complesso Universitario di Monte S. Angelo,
Via Cintia, 80126 Napoli, Italy
to other powerful couplings such as the Suzuki–Miyaura
reaction, for which only some sporadic examples have been
E-mail: matteo.lega@unina.it
http://scienzechimiche.dip.unina.it/
[
3]
reported. Nevertheless, in this field, sugar candidates are
really attractive building blocks owing to their solubility in
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201402456.
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water,[ which allows the green and sustainable synthesis of
4]
As expected, all of the complexes were soluble in
aqueous media and could be fruitfully employed in the
[
5]
biaryls.
On this basis, we report the preparation of diphenylphos- Suzuki–Miyaura coupling reaction.
phino–imino (PN) and pyridino–imino (NN) sugar-based
ligands, along with the syntheses of the corresponding
hydrophilic Pd complexes (Figure 1, fdn = fumarodi-
0
Results and Discussion
nitrile). Some imino ligands have recently been employed in
Suzuki–Miyaura couplings,[ but in all cases the activities
ranged from low to moderate.
Synthesis of the Complexes
6]
The strategy for the synthesis of the complexes involved
The design of both PN and NN ligands was aimed at three major steps. First, protected PN and NN ligands were
ensuring their easy, high-yield synthesis. synthesized from suitable precursors. In a second phase,
0
Four imino sugar residues were employed: three of them the corresponding Pd complexes [Pd(PN)(fdn)] or
are derived from glucose functionalized at the 1-, 2- and 6- [Pd(NN)(fdn)] were prepared (Scheme 1, Step i) and then
positions, and the fourth is instead a mannoside derivatized transformed into the deprotected hydrophilic species
at the 6-position.
[Pd(PN*)(fdn)] or [Pd(NN*)(fdn)] (Scheme 1, Step ii).
Scheme 1. Synthesis of the complexes.
Scheme 2. Synthesis of the ligands.
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Some of the ligands were already known (Scheme 2),[7]
and the others were synthesized for the first time. The mol-
ecules were prepared from the corresponding amino or
azido precursors 1, 2 and 3 by condensation with the proper
aldehyde in the former case and by aza-Wittig reactions in
the latter cases. The products were isolated in high yields
by column chromatography or precipitation.
The corresponding [Pd(PN)(fdn)] and [Pd(NN)(fdn)]
complexes were prepared in good yields from fresh
[
Pd (dba) ·CHCl ] (dba = dibenzylideneacetone) by an es-
2 3 3
[7a]
tablished procedure (Scheme 1, Step i).
In toluene, the dba molecules were readily displaced by
one alkene and one chelating molecule, as revealed by the
rapid change of colour of the reaction mixture from brown
to orange-yellow. After the removal of the solvent under
vacuum, the complexes were obtained as yellow to orange Figure 2. Portion of the H NMR spectrum of [Pd(PN-G2)(fdn)].
microcrystalline solids by column chromatography over sil- The signals of the major (M) diastereoisomer and the correspond-
1
ing signals for minor (m) one are evidenced.
ica. All of the isolated complexes could be handled in air
at room temperature and were stored for several weeks at
2
77 K without appreciable decomposition.
Table 1. Diastereomeric ratios within the [Pd(PN)(fdn)] and
Pd(NN)(fdn)] complexes.
The compounds were characterized by H, 13C and 31
1
P
[
NMR spectroscopy. Upon coordination to the Pd centre,
the signals of the olefin undergo a large shift to lower fre-
quencies. This behaviour has been reported previous-
Entry
1[a]
2
Complex
Solvent
Diastereomeric ratio
[Pd(PN-G1)(fdn)]
[Pd(PN-G2)(fdn)]
[Pd(PN-G6)(fdn)]
[Pd(PN-M6)(fdn)]
[Pd(NN-G1)(fdn)]
[Pd(NN-G2)(fdn)]
[Pd(NN-G6)(fdn)]
[Pd(NN-M6)(fdn)]
[Pd(PN-G1*)(fdn)]
[Pd(PN-G2*)(fdn)]
[Pd(PN-G6*)(fdn)]
[Pd(PN-M6*)(fdn)]
[Pd(NN-G1*)(fdn)]
[Pd(NN-G2*)(fdn)]
[Pd(NN-G6*)(fdn)]
[Pd(NN-M6*)(fdn)]
CDCl
CDCl
CDCl
CDCl
3
3
3
3
70:30
86:14
72:28
80:20
80:20
84:16
55:45
60:40
50:50
60:40
87:13
73:27
55:45
65:35
50:50
50:50
[7a,7c,8,9]
ly
and is attributed to the substantial degree of π
[
a]
3
4
5
6
7
8
9
1
0
back-donation in the Pd –olefin bond, which stabilizes the
low oxidation state of the palladium centre. The consequent
partial sp Ǟsp rehybridization of the alkene carbon atoms
[a]
b]
[
CDCl3
2
3
CDCl
CDCl
CDCl
3
3
3
shifts the corresponding signals towards the aliphatic region
1
13
in both the H and the C NMR spectra.
CD
CD
CD
CD
CD
CD
CD
3
3
3
3
3
3
3
OD
OD
OD
OD
OD
OD
OD
0
It is worth noting that water-soluble Pd compounds are
0
[
7a,7b,10]
0
quite rare.
The hydrophilic Pd
complexes 11
1
1
1
1
2
3
4
5
[
Pd(PN*)(fdn)] and [Pd(NN*)(fdn)] were obtained by basic
[b]
hydrolysis of the acetyl and benzoyl groups (Scheme 1,
Step ii). The yellow microcrystalline products, which are
fairly soluble in water, methanol and ethanol, were isolated 16
3
CD OD
in high yields by precipitation with diethyl ether from the
reaction mixtures. Also in this case, all of the isolated com-
plexes could be handled in air at room temperature and
were stored for several weeks at 277 K without appreciable
a] From ref.[7c] [b] From ref.[7b]
[
In almost all cases, a significant discrimination has been
decomposition. The only exception is [Pd(PN-G1*)(fdn)], found. As a general consideration, the O-acylated com-
which slowly underwent a transformation to another spe- plexes have a similar selectivity, and there are only small
cies in solution; this phenomenon is currently under study. differences for the two coordinating systems (PN and NN;
In both the O-acylated and the deprotected species, the Table 1, Entry 1 vs. 5 and 2 vs. 6; exceptions are Entry 3 vs.
coordination of fdn affords two diastereoisomers, because 7 and 4 vs. 8), their position on the sugar backbone (1-, 2-
the olefin is prochiral. The diastereoisomers interconvert or 6-position; Table 1, Entry 1 vs. 2 vs. 3 and Entry 5 vs. 6
by an associative mechanism,[
9–11]
in which an external vs. 7; Entry 7 is the only exception) and the epimer used
olefin coordinates to the metal centre with the enantioface (glucose and mannose; Table 1, Entry 3 vs. 4 and 7 vs. 8).
opposite to that initially coordinated, which then disso-
ciates.
The differences are larger among the deprotected com-
plexes, for which there is a general drop of selectivity, prob-
The isomeric equilibrium is rapidly reached after dissol- ably because of the lack of steric hindrance provided by the
ution of the complexes, and the presence of two resolved acyl groups. For these complexes, the presence of the bulky
patterns for the two isomers indicates that this process is diphenylphosphino group provides a better selectivity com-
slow at room temp. on the NMR timescale (Figure 2 shows pared with that with the pyridyl group (Table 1, Entry 12
[
7c]
an example).
The integration of suitably separated peaks allowed us to
calculate the diastereomeric ratios, which are reported in palladium complex [Pd(NN-G2)(fdn)] was characterized by
vs. 16).
To obtain further evidence of the structures reported, the
Table 1.
X-ray crystallography. Crystallization from methanol–
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acetonitrile (5:1) yielded single crystals (space group P1). Table 2. Selected bond lengths [Å] and angles [°] for the two dia-
stereomers of [Pd(NN-G2)(fdn)].
Quite surprisingly, the asymmetric unit contains two mol-
ecules of the complex, which correspond to the two dia-
stereomers and differ only in the enantioface of the prochi-
ral fumarodinitrile molecule coordinated to the metal cen-
tre. The ORTEP drawings of the two molecules are shown Pd–N1
in Figure 3. The root-mean-square deviation between the
Bond lengths
Pd–C20
Pd–C21
2.026(8)
2.035(10)
2.152(7)
2.157(6)
1.411(1)
2.040(8)
2.067(9)
2.139(8)
2.152(6)
1.4685(2)
Pd–N2
C20–C21
two diastereomers after superposition (calculated excluding
fumarodinitrile and hydrogen atoms) is 0.467 Å.
Bond angles
C20–Pd1–C21
C20–Pd1–N1
C21–Pd1–N1
C20–Pd1–N2
C21–Pd1–N2
N1–Pd1–N2
40.7(4)
41.9(3)
119.9(3)
160.1(3)
163.4(3)
123.8(3)
75.9(3)
118.4(3)
159.1(3)
164.7(3)
122.8(3)
76.8(3)
Suzuki–Miyaura Cross-Coupling Reactions
The Suzuki–Miyaura cross-coupling is an extremely use-
ful tool for C–C bond formation, owing to its versatility
[
14]
and efficiency.
This reaction is usually performed in organic solvents,
neat or mixed with water. The drawbacks of aqueous sol-
vents are the low solubility of several substrates and the
general lower stability of the metal catalysts in water. On
this basis, a large variety of water-compatible protocols has
been developed in recent years, which include the use of
[
14,15]
[16]
hydrophilic complexes,
surfactants
and microwave
[
17]
irradiation. However, only a few of them display signifi-
cant activity.
A good compromise between organic and aqueous sol-
vents is the use of ethanol–water mixtures, as small alcohols
are among the greenest solvents in terms of impact on
health and the environment and in terms of the energy
[
18]
Figure 3. ORTEP drawing of the two diastereomers of [Pd(NN- needed for their manufacture and disposal.
Ethanol in-
G2)(fdn)].
creases the solubility of the substrate, does not interfere
with the separation of the product (as surfactants do) and
All bond lengths and angles are in the normal range. is bioavailable at a low cost. Hydroalcoholic mixtures are
[
19]
Some interesting bond lengths and angles are reported in the media of choice to reduce the use of dangerous, envi-
Table 2. As expected,[8d] the Pd centre has a trigonal- ronmentally unfriendly organic solvents and to offer easy
planar coordination geometry. The coordination plane in- separation of the product from the reaction system.
0
cludes the pyridine ring. The atoms coordinated to the Pd
For these reasons, the water-soluble complexes
centre are coplanar within 0.09 and 0.10 Å for the two dia- [Pd(PN*)(fdn)] and [Pd(NN*)(fdn)] were tested in the Su-
stereomers. In both molecules, the sugar ring adopts the zuki–Miyaura reaction in ethanol–water mixtures. A proto-
expected chair conformation, and the mean plane of the col should be intended as “truly green” when toxic organic
sugar ring is almost perpendicular to the coordination solvent are not involved in any step, including the workup.[
5]
plane (ca. 83 and 105° for the two diastereomers).
Our workup procedure involved an extraction with di-
The coordination bond lengths fall within the expected chloromethane (DCM) and chromatography with hexane–
range for Pd–α-diimine complexes[
12,13]
and are similar to ethyl acetate (Hex/EtOAc) mixtures, but this choice was due
[
7a]
those found for [Pd(N,N-chelate)(olefin)] complexes. The to the small scale of our screening reactions and the neces-
length of the olefinic bond is evidence of the substantial sity of reporting isolated yields also for partial conversions.
rehybridization of the olefinic carbon atoms towards sp3 In test experiments with higher scales and complete conver-
upon coordination (1.41 and 1.47 Å for the two dia- sion, we demonstrated that it was possible to isolate the
stereomers vs. 1.34 Å for the free alkene). Further evidence pure hydrophobic products in almost quantitative yields by
is the large out-of-plane displacements of the cyano groups simple addition of water followed by filtration of the solid
(
the torsion angles for the four C atoms of the fdn molecule products. Analogous protocols have already been re-
[
20]
are 135 and 150°).
ported.
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In principle, the parent O-acylated [Pd(PN)(fdn)] and
The volume that resulted in the best yield (4 mL, Table 3,
[
Pd(NN)(fdn)] species may also function as precatalysts, be- Entry 6, ca. 0.13 m in coupling partners) was used for the
cause the acyl groups are expected to hydrolyze easily under screening of the equivalents of base. As reported, its pres-
the basic coupling conditions. Nevertheless, the deprotected ence is fundamental for this reaction (as confirmed by
species were preliminarily isolated to demonstrate their ac- Table 3, Entry 8). The highest yield was obtained with
tual existence and, hence, to assess the nature of the cata- 2 equiv. of base with respect to the aryl bromide (Table 3,
lytic complexes.
Entry 10).
These optimized conditions were used in the next screen-
Furthermore, their high solubility in ethanol allowed us
to prepare concentrated stock solutions for an accurate dos- ing, in which lower amounts of catalyst were used (Table 4).
age of the catalyst.
Table 4. Screening of catalyst loading with [Pd(PN-M6*)(fdn)].[a]
In all cases, glassware and stir bars were washed three
times with 37% HCl to avoid artefacts caused by Pd resi- Entry Catalyst loading [mol-%][b] Isolated yield [%][c] TOF [h–1]
dues.
The first screenings were performed to optimize the reac-
tion conditions in terms of ethanol–water ratio (Table 3,
Entries 1–5), concentration (Table 3, Entries 3, 6 and 7) and
equivalents of base (Table 3, Entries 8–12).
1
2
3
4
5
1.0
0.10
0.010
0.0050
0.0010
80
95
75
83
0
80
950
7500
16600
0
[a] Conditions: 4-bromoanisole (0.5 mmol), phenylboronic acid
(
0.55 mmol), [Pd(PN-M6*)(fdn)],
K
2
CO
3
(1.0 mmol), water
Table 3. Optimization of reaction conditions with [Pd(PN-
M6*)(fdn)].
(
2 mL), ethanol (2 mL), 1 h, hotplate temperature 120 °C. [b] Cata-
lyst loading with respect to 4-bromoanisole. [c] Average of two runs.
[
a]
Interestingly, catalyst loadings of less than 1.0 mol-% re-
sulted in higher yields, most likely because of the abovemen-
tioned faster deactivation of the catalyst with formation of
metallic Pd at higher complex concentration. The catalyst
had no activity at a concentration of 0.0010 mol-% (Table 4,
Entry 5).
On the basis of these results, the other complexes were
tested with a loading of 0.010 mol-% or lower to find the
most-active catalyst (Table 5). We purposely chose catalyst
loadings and reaction times to maintain conversions far
from completeness so that the performances of the different
complexes could be effectively compared. In almost all
cases, it is possible to achieve complete conversion just by
extending the reaction time.
Entry
EtOH/H
2
O
Volume
[mL]
K
[mmol]
2
CO
3
Isolated
yield[ [%]
b]
(
v/v)
1
2
3
4
5
6
7
8
9
6:0
2:1
1:1
1:2
0:6
1:1
1:1
1:1
1:1
1:1
1:1
1:1
6
6
6
6
6
4
3
4
4
4
4
4
1.5
1.5
1.5
1.5
1.5
1.5
1.5
5
32
47
42
12
69
57
0
21
80
61
56
without base
0.50
Table 5. Screening of complexes at different catalyst loadings.[a]
10
11
12
1.0
Entry Complex
Catalyst load-
ing [mol-%]
Isolated
yield [%]
TOF
[h ]
2.25
[b]
[c]
–1
3.0
1
2
3
4
5
6
7
8
[Pd(PN-G1*)(fdn)]
[Pd(PN-G2*)(fdn)]
[Pd(PN-G6*)(fdn)]
[Pd(NN-M6*)(fdn)] 0.010
[Pd(PN-G1*)(fdn)] 0.0050
[Pd(NN-M6*)(fdn)] 0.0050
[Pd(PN-G1*)(fdn)] 0.0020
[Pd(NN-M6*)(fdn)] 0.0020
0.010
0.010
0.010
87
56
72
68
58
97
0–15
65
8700
5600
7200
6800
11660
19400
–
[
(
a] Conditions: 4-bromoanisole (0.50 mmol), phenylboronic acid
0.55 mmol), [Pd(PN-M6*)(fdn)], (5.0ϫ10 mmol, 1.0 mol-%),
–3
1
h, hotplate temperature 120 °C. [b] Average of two runs.
Phenylboronic acid, 4-bromoanisole and potassium carb-
onate were used as benchmark substrates and base, and
32500
[
Pd(PN-M6*)(fdn)] was selected as the catalyst.
[
(
1
a] Conditions: 4-bromoanisole (0.5 mmol), phenylboronic acid
0.55 mmol), K CO (1.0 mmol), water (2 mL), ethanol (2 mL),
h, hotplate temperature 120 °C. [b] Catalyst loading with respect
The reactions in neat ethanol or water (Table 3, Entries 1
2
3
and 5) resulted in poor yields. This was expected, because
the former is not able to dissolve the base, whereas the latter
does not dissolve the substrate properly. The best water–
ethanol ratio was 1:1 (Table 3, Entry 3).
to 4-bromoanisole. [c] Average of two runs.
All of the PN complexes and one NN complex were
This solvent ratio at total volumes of 6, 4 and 3 mL was tested at a catalyst loading of 0.010% and produced good
used to adjust the concentration (Table 3, Entries 3, 6 and results (Table 5, Entries 1–4). The best-performing PN spe-
7). Unexpectedly, the highest concentration resulted in a cies and the NN complex, namely, [Pd(PN-G1*)(fdn)] and
drop of activity, probably because the higher concentration [Pd(NN-M6*)(fdn)], were then examined at lower catalyst
of complex favours the formation of metallic Pd. Similar loadings of 0.0050 and 0.0020 mol-% (Table 5, Entries 5–8).
behaviour has been reported for the formation of Pd Te
nanoparticles.
In the latter case, the PN catalyst showed a lack of reprodu-
cibility, and the isolated yields ranged from 0 to 15%.
2
3
[
21]
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Owing to the satisfying results achieved with [Pd(NN-
The catalyst was also effective with sterically demanding
M6*)(fdn)], the whole NN family was tested under the same substrates (Table 7, Entries 2, 3, 8, 9), although with slightly
conditions and provided good yields; they are more active lower activity, and towards substrates with electron-releas-
than the corresponding PN species (Table 6).
ing or -withdrawing groups. Disappointingly, aryl chlorides
resulted in very poor conversions; hence, they are not re-
ported in the table.
Table 6. Screening of complexes at different catalyst loadings.[a]
Entry Complex
Catalyst load-
ing [mol-%]
Isolated yield[c] TOF
[b]
–1
[%]
[h ]
1
2
3
4
5
[Pd(NN-G6*)(fdn)]
0.0020
0.0020
0.0020
0.0010
0.0010
0.0010
0.0010
65
4
32500
2000
35000
12000
12000
9250
Conclusions
[Pd(NN-G1*)(fdn)]
[Pd(NN-G2*)(fdn)]
[Pd(NN-G6*)(fdn)]
[Pd(NN-G2*)(fdn)]
[Pd(NN-G6*)(fdn)]
[Pd(NN-G2*)(fdn)]
0
70
12
12
37
38
In this work, two classes of water-soluble Pd complexes
(PN and NN) were prepared and tested in the Suzuki–
[
d]
Miyaura cross-coupling reaction under environmentally
friendly aqueous conditions. The best catalyst, namely,
6
7
[
d]
9500
[
(
Pd(NN-G2*)(fdn)], was active at really low loading
0.0010 mol-%), tolerant towards different substrates and
[
(
a] Conditions: 4-bromoanisole (0.5 mmol), phenylboronic acid
0.55 mmol), K CO (1.0 mmol), water (2 mL), ethanol (2 mL),
2 3
1
h, hotplate temperature 120 °C. [b] Catalyst loading with respect very efficient in comparison to previously reported systems;
4
–1
to 4-bromoanisole. [c] Average of two runs. [d] Reaction time: 4 h.
the TOFs are up to 3.5ϫ10 h , which is close to the best
results
will focus on the expansion of the library to achieve reacti-
vity towards aryl chlorides and eventually catalyst re-
cycling, which, as observed in preliminary studies, is com-
promised by leaching during the extraction of the product.
[
22]
for reactions in aqueous media. Future studies
Only [Pd(NN-G1*)(fdn)] was almost ineffective, proba-
bly because of the higher sensitivity of the sugar function-
alized at the 1-position.
The complexes [Pd(NN-G2*)(fdn)] and [Pd(NN-
G6*)(fdn)] were further employed at 0.0010 mol-% loading
(Table 6, Entries 4 and 5), at which they still presented ap-
preciable yields after 1 h, whereas [Pd(NN-M6*)(fdn)] was
ineffective and, hence, it is not reported in the table.
Experimental Section
When the reaction was prolonged to 4 h, the yield in- General Considerations: NMR spectra were recorded with samples
1
3
creased to 38% (Table 6, Entries 6 and 7); therefore, the in CDCl (CHCl δ = 7.26 ppm and CDCl δ = 77 ppm as in-
3
3
3
complexes are still active after the first hour of reaction. ternal standards), C
6
D
6
[tetramethylsilane (TMS) δ = 0 ppm and
1
3
C
6
D
6
δ = 128.6 ppm as internal standards] and CD
3
OD
OD δ = 49.9 ppm as internal
standards) with 200 (Varian Model Gemini) and 400 MHz (Bruker
The activities of the two complexes were almost the same.
Owing to its easier synthesis, [Pd(NN-G2*)(fdn)] was
tested as the catalyst of choice for the entire set of sub-
strates (Table 7).
1
3
2 3
(CHD OD δ = 3.34 ppm and CD
3
1
DRX-400) spectrometers. P NMR experiments were performed
with aqueous 85% phosphoric acid as an external reference (δ =
0
ppm). The following abbreviations are used to describe the NMR
Table 7. Screening of substrates with [Pd(NN-G2*)(fdn)].[a]
multiplicities: s singlet, d doublet, dd double doublet, t triplet, dt
double triplet, m multiplet, app apparent, br broad. Compounds
PN-G1, PN-G2, PN-G6, PN-M6, NN-G1, [Pd(PN-G1)(fdn)],
[Pd(PN-G6)(fdn)], [Pd(PN-M6)(fdn)], [Pd(NN-G1)(fdn)] and
[
Pd(NN-G1*)(fdn)] were prepared according to literature meth-
[7d,7b,7c]
ods.
4
Tetrahydrofuran (THF) was distilled from LiAlH , and
2
dichloromethane was distilled from CaH .
NN-G2: The amino intermediate 1 (640 mg, 2.0 mmol) was sus-
pended in absolute EtOH (25 mL), and then 2-pyridincarboxyalde-
hyde (240 mg, 2.20 mmol) was added. After 72 h, hexane (80 mL)
was added, and the precipitated product was collected by filtration
and washed three times with hexane (yield: 560 mg, 69%) to afford
Entry
R1
R2
Isolated yield [%][b]
1
2
3
4
5
6
7
8
9
4-OMe
4-OMe
4-OMe
4-OMe
4-OMe
4-OMe
4-OMe
2-OMe
3-OMe
4-NO
4-OH
4-CHO
H
4-Me
3-Me
2-Me
4-NO
74
63
48
Ͻ5
25
Ͻ5
33
30
76
85
15
85
50
24 2 8
a white powder. C19H N O (408.4): calcd. C 55.88, H 5.92, N
1
2
6
2
3
.86; found C 55.64, H 5.85, N 7.01. H NMR (400 MHz, CDCl ,
4-CHO
3
5 °C): δ = 8.64 (d, JH,H = 4.6 Hz, 1 H, aromatic), 8.31 (s, 1 H,
N=CH), 7.97 (d, JH,H = 7.8 Hz, 1 H, aromatic), 7.73 (t, JH,H
4-OH
4-OMe
H
H
H
H
H
H
3
3
=
3
3
7
1
5
.7 Hz, 1 H, aromatic), 7.33 (dd, JH,H = 5.4 Hz, JH,H = 6.7 Hz,
H, aromatic), 5.43 (t, J3-H,4-H = 3J3-H,2-H = 9.6 Hz, 1 H, 3-H),
3
3
3
3
.14 (t, J3-H,4-H = J4-H,5-H, 1 H, 4-H), 4.69 (d, J1-H,2-H = 7.8 Hz,
10
11
12
13
2
3
gem
1 H, 1-H), 4.36 (dd, J6-H,5-H = 4.6,
H), 4.18 (dd, J
6Ј-H,5-H
J6-H,6Ј-H = 12.2 Hz, 1 H, 6-
3
= 1.8 Hz, 1 H, 6Ј-H), 3.84 (m, 1 H, 5-H),
3
3
.49 (s, 3 H, OMe), 3.42 (t, 1 H, 2-H), 2.10 (s, 3 H, OAc), 2.03 (s,
H, OAc), 1.88 (s, 3 H, OAc) ppm. C NMR (100 MHz, CDCl ,
3
1
3
[
(
a] Conditions: aryl bromide (0.50 mmol), arylboronic acid
0.55 mmol), [Pd(NN-G2*)(fdn)], (5ϫ10 mmol, 0.010 mol-%),
–5
25 °C): δ = 171.2, 170.3, 170.2, 166.2, 154.3, 149.9, 137.1, 125.6,
1
h, hotplate temperature 120 °C. [b] Average of two runs.
122.2, 102.9, 74.4, 73.5, 72.3, 69.0, 62.6, 57.6, 21.2, 21.1, 21.0 ppm.
Eur. J. Inorg. Chem. 0000, 0–0
6
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Job/Unit: I42456
/KAP1
Date: 21-07-14 12:06:19
Pages: 11
www.eurjic.org
FULL PAPER
NN-G6 and NN-M6: A known procedure was adapted.[7a] The de-
sired azide (810 mg, 2.0 mmol) was dissolved in dry dichlorometh-
ane (10 mL) under argon. Then, 2-pyridincarboxyaldehyde
[Pd(NN-G2)(fdn)]: C23
N 9.45; found C 46.73, H 4.52, N 9.30. Major diastereoisomer: H
NMR (400 MHz, CDCl , 25 °C): δ = 8.92 (d, JH,H = 4.6 Hz, 1 H,
3
H
N
O
Pd (592.9): calcd. C 46.59, H 4.42,
26
4
8
1
3
3
(235 mg, 2.2 mmol, 210 μL) and PPh
2
Me (440 mg, 410 μL, aromatic), 8.43 (s, 1 H, N=CH), 8.05 (d, JH,H = 7.3 Hz, 1 H,
3
3
2.2 mmol) were added in this order at 0 °C. The reaction mixture
aromatic), 7.76 (t, JH,H = 7.6 Hz, 1 H, aromatic), 7.67 (dd, JH,H
3
3
was left to warm to room temp., and after 72 h the solvent was
removed under vacuum. The crude product was purified by column
chromatography on florisil (eluent Hex/EtOAc = 1:1), yields: NN-
3-H,4-H
= 5.5 Hz, JH,H = 6.8 Hz, 1 H, aromatic), 5.82 (t, J =
3
3
3
J
3-H,2-H = 9.6 Hz, 1 H, 3-H), 5.17 (t, J3-H,4-H = J5-H,4-H, 1 H, 4-
3
3
H), 4.93 (d,
4.1 Hz,
J1-H,2-H = 7.6 Hz, 1 H, 1-H), 4.41 (dd,
J
5-H,6-H
=
=
gem
6-H,6Ј-H = 12.4 Hz, 1 H, 6-H), 4.16 (dd, 3J5-H,6Ј-H
G6 480 mg, 51%; NN-M6 510 mg, 54%. NN-G6: C24
H
26
N
2
O
8
J
(
5
8
8
470.47): calcd. C 61.27, H 5.57, N 5.95; found C 61.49, H 5.68, N
1.2 Hz, 1 H, 6Ј-H), 4.08 (m, 1 H, 5-H), 3.71 (t, 1 H, 2-H), 3.51 (s,
1
3
.83. H NMR (400 MHz, C
6
D
6
, 25 °C): δ = 8.48 (s, 1 H, N=CH),
3 H, OMe), 3.24 (d, JH,H = 9.5 Hz, 1 H, fdn), 2.99 (d, 1 H, fdn),
3
13
.44 (d, JH,H = 4.8 Hz, 1 H, aromatic), 8.13 (m, 2 H, aromatic), 2.09 (s, 3 H, OAc), 2.06 (s, 3 H, OAc), 1.93 (s, 3 H, OAc) ppm.
C
3
.06 (d, JH,H = 7.9 Hz, 1 H, aromatic), 7.16–6.97 (m, 4 H, aro-
NMR (100 MHz, CDCl
3
, 25 °C): δ = 171.1, 170.6, 169.6, 166.9,
3
3
matic), 6.60 (m, 1 H, aromatic), 6.19 (t,
J
3-H,4-H
=
J
3-H,2-H
=
153.7, 152.4, 139.4, 129.7, 127.6, 124.3, 122.9, 101.4, 74.9, 74.8,
72.1, 68.8, 62.2, 58.1, 21.2, 21.1, 21.1, 20.1, 19.8 ppm. Relevant
3
3
9
.9 Hz, 1 H, 3-H), 5.73 (t, J3-H,4-H = J5-H,4-H, 1 H, 4-H), 5.14 (dd,
3
1
J
1-H,2-H = 3.7 Hz, 1 H, 2-H), 4.91 (d, 1 H, 1-H), 4.38 (m, 1 H, 5-
signals for the minor diastereoisomer: H NMR (400 MHz, CDCl
3
,
3
gem
3
3
H), 3.78 (dd, J5-H,6-H = 3.1,
J6-H,6Ј-H = 13.0 Hz, 1 H, 6-H), 3.58
3-H,4-H 3-H,2-H
25 °C): δ = 8.37 (s, 1 H, N=CH), 5.60 (t, J = J =
3
3
3
(dd, J5-H,6Ј-H = 6.7 Hz, 1 H, 6Ј-H), 3.01 (s, 3 H, OMe), 1.60 (s, 3
9.6 Hz, 1 H, 3-H), 5.19 (t, J3-H,4-H = J5-H,4-H, 1 H, 4-H), 4.98 (d,
13
3
3
H, OAc), 1.58 (s, 3 H, OAc) ppm. C NMR (100 MHz, C
5 °C): δ = 169.8, 165.7, 165.0, 155.6, 149.7, 136.1, 133.4, 130.4 (2
C), 130.2, 128.8 (2 C), 124.6, 97.1, 72.0, 71.9, 70.8, 69.0, 61.5, 54.9,
6
D
6
,
J
1-H,2-H = 7.6 Hz, 1 H, 1-H), 3.58 (s, 3 H, OMe), 3.00 (d, JH,H
=
2
9.5 Hz, 1 H, fdn), 2.91 (d, 1 H, fdn) ppm.
[
Pd(NN-G6)(fdn)]: C28 Pd (655.0): calcd. C 51.35, H 4.31,
28 4 8
H N O
3
6
(
=
2.1, 23.1, 20.3, 14.5 ppm. NN-M6: C24
1.27, H 5.57, N 5.95; found C 61.10, H 5.54, N 6.03, H NMR
26 2 8
H N O (470.5): calcd. C
N 8.55; found C 51.65, H 4.44, N 8.86. Relevant signals for the
1
1
major diastereoisomer: H NMR (400 MHz, CDCl
3
, 25 °C): δ =
3
400 MHz, C
6
D
6
, 25 °C): δ = 8.46 (s, 1 H, N=CH), 8.42 (d, JH,H
3
8
(
.84 (d, JH,H = 4.5 Hz, 1 H, aromatic), 8.40 (s, 1 H, N=CH), 8.08
d, JH,H = 7.3 Hz, 1 H, aromatic), 5.79 (t, J3-H,4-H = J3-H,2-H =
.6 Hz, 1 H, 3-H), 5.27 (t, J3-H,4-H = J5-H,4-H, 1 H, 4-H), 4.94 (m,
4.2 Hz, 1 H, aromatic), 8.07 (m, 3 H, aromatic), 7.16–6.97 (m, 4
3
3
3
3
3
H, aromatic), 6.60 (m, 1 H, aromatic), 6.09 (t, J3-H,4-H = J5-H,4-H
=
3
3
9
3
9.6 Hz, 1 H, 4-H), 6.02 (dd, J3-H,2-H = 3.3 Hz, 1 H, 3-H), 5.63
2
J
H, 1-H, 2-H), 4.81 (m, 1 H, 5-H), 3.55 (s, 3 H, OMe), 2.97 (d,
H,H = 9.2 Hz, 1 H, fdn), 2.91 (s, 1 H, fdn), 2.09 (s, 3 H, OAc),
3
(dd, J1-H,2-H = 1.7 Hz, 1 H, 2-H), 4.54 (d, 1 H, 1-H), 4.45 (m, 1
3
3
gem
H, 5-H), 3.90 (dd, J5-H,6-H = 1.4 Hz,
6
1
C
1
7
J6-H,6Ј-H = 11.3 Hz, 1 H,
1
.92 (s, 3 H, OAc) ppm. Relevant signals for the minor diastereoiso-
3
-H), 3.70 (dd, J5-H,6Ј-H = 7.3 Hz, 1 H, 6Ј-H), 2.98 (s, 3 H, OMe),
1
3
mer: H NMR (400 MHz, CDCl
3 H,H
, 25 °C): δ = 8.58 (d, J =
.67 (s, 3 H, OAc), 1.56 (s, 3 H, OAc) ppm. 13C NMR (100 MHz,
4
.5 Hz, 1 H, aromatic), 8.28 (s, 1 H, N=CH), 3.53 (s, 3 H, OMe)
6
D
6
, 25 °C): δ = 169.8, 165.8, 164.8, 155.6, 149.6, 136.0, 133.4,
1
ppm. The other signals are in the following regions: H NMR
400 MHz, CDCl , 25 °C): δ = 8.06–7.02 (15 H, aromatic), 4.21–
3
.00 (m), 3.83 (m) ppm. C NMR (100 MHz, CDCl , 25 °C): δ =
30.3 (2 C), 130.2, 128.9, 128.8, 128.7, 124.6, 120.9, 98.9, 70.6, 70.4,
0.0, 69.4, 62.0, 54.8, 20.4, 20.3 ppm.
(
4
3
13
General Procedure for the Preparation of the [Pd(ligand)(fdn)] Com-
plexes: A known procedure was adapted:[7d] [Pd
(dba) ·CHCl
215 mg, 0.21 mmol) was added to a solution of the desired ligand
0.50 mmol) and fdn (39 mg, 0.50 mmol) in toluene (5 mL). After
h, the solution was filtered through Celite, and the solvent was
evaporated; the crude product was purified by column chromatog-
raphy over silica (eluent Hex/EtOAc 1:1 for PN family, neat EtOAc
for NN family), and the pure product was isolated as a yellow
microcrystalline solid (yields 68–85%).
170.9, 170.9, 170.1, 169.9, 166.4, 166.1, 165.2, 164.9, 153.7, 153.4,
152.6, 152.4, 143.8, 139.4, 139.0, 135.1, 134.3, 134.1, 131.0, 130.6,
130.4, 129.4, 129.2, 129.1, 128.8 (2 C), 128.6, 128.4, 127.0, 126.8,
125.8, 123.2, 123.0, 122.7, 97.2, 97.0, 72.3, 71.5 (2 C), 71.1, 70.2,
70.0, 69.1, 68.2, 65.3, 63.7, 57.1, 56.4, 21.2 (2 C), 21.0 (2 C), 19.3,
18.9, 18.8, 18.7 ppm.
2
3
3
]
(
(
1
[
Pd(NN-M6)(fdn)]: C28
28 4 8
H N O Pd (655.0): calcd. C 51.35, H 4.31,
1
N 8.55; found C 51.61, H 4.14, N 8.77. Major diastereoisomer: H
NMR (400 MHz, C
aromatic), 8.05 (d, JH,H = 4.7 Hz, 1 H, N=CH), 7.26–6.86 (m, 4
3
6
3
D
6
, 25 °C): δ = 8.46 (d, JH,H = 7.3 Hz, 2 H,
[
36 3 8
Pd(PN-G2)(fdn)]: C36H N O PPd (776.1): calcd. C 55.71, H 4.68,
1
3
N 5.41; found C 55.87, H 4.56, N 5.55. Major diastereoisomer: H H, aromatic), 6.70 (t, JH,H = 7.6 Hz, 1 H, aromatic), 6.30 (m, 2
NMR (400 MHz, CDCl
4
3
3
3
, 25 °C): δ = 8.29 (d, JH,P = 1.5 Hz, 1 H,
H, aromatic), 6.06 (dd, J3-H,4-H = 10.1 Hz, J3-H,2-H = 3.3 Hz, 1 H,
3
3-H), 5.94 (t, J3-H,4-H = 3J5-H,4-H, 1 H, 4-H), 5.68 (dd, 3J1-H,2-H
3
N=CH), 7.65–7.05 (m, 14 H, aromatic), 6.08 (t,
J
3-H,4-H
=
=
3
3
3
3
J
3-H,2-H = 9.6 Hz, 1 H, 3-H), 5.12 (t, J3-H,4-H = J5-H,4-H, 1 H, 4- 1.6 Hz, J3-H,2-H = 3.3 Hz, 1 H, 2-H), 4.97 (m, 1 H, 5-H), 4.39 (m,
3
1-H,2-H = 7.8 Hz, 1 H, 1-H), 4.36 (dd, 3
3
3
H), 5.04 (d,
4
(
H, OMe), 3.14 (dd, JH,H = 9.6 Hz,
(
1
J
J
5-H,6-H
=
1 H, 1-H), 3.95 (d, J6-H,6Ј-H = 12.4 Hz, 1 H, 6-H), 3.40 (dd, J5-
H,6Ј-H = 9.6 Hz, 1 H, 6Ј-H), 3.33 (s, 3 H, OMe), 2.82 (s, 2 H, fdn),
gem
.0 Hz,
J6-H,6Ј-H = 12.3 Hz, 1 H, 6-H), 4.24 (m, 1 H, 5-H), 4.14
dd, J5-H,6Ј-H = 1.8 Hz, 1 H, 6Ј-H), 3.44 (t, 1 H, 2-H), 3.20 (s, 3 1.73 (s, 3 H, OAc), 1.59 (s, 3 H, OAc) ppm. Relevant signals for
3
3
cis
1
J
H,P = 3.0 Hz, 1 H, fdn), 2.99
H,P, 1 H, fdn), 2.07 (s, 3 H, OAc), 2.04 (s, 3 H, OAc),
6 6
the minor diastereoisomer: H NMR (400 MHz, C D , 25 °C): δ =
3
trans
3
3
t, JH,H
=
J
8.13 (d, JH,H = 7.3 Hz, 2 H, aromatic), 7.92 (d, JH,H = 4.0 Hz, 1
13
3
.67 (s, 3 H, OAc) ppm. C NMR (100 MHz, CDCl
3
, 25 °C): δ
H, N=CH), 7.26–6.86 (m, 4 H, aromatic), 6.64 (t, JH,H = 7.0 Hz,
=
170.7, 170.2, 170.1, 169.1, 137.7, 137.6, 137.3, 137.1, 135.2, 134.1,
1 H, aromatic), 6.34 (m, 2 H, aromatic), 6.10 (dd, 3J3-H,4-H
=
=
3
3
1
1
2
33.9, 133.8, 132.9, 132.7, 132.7, 132.6, 131.7, 131.4, 130.8, 130.6,
29.5, 129.4, 129.2, 129.1, 101.1, 80.9, 73.8, 72.2, 69.3, 62.0, 57.2,
10.0 Hz,
J
J
3-H,2-H = 3.3 Hz, 1 H, 3-H), 5.88 (t,
J
3-H,4-H
3
3
3
5-H,4-H, 1 H, 4-H), 5.72 (dd, J1-H,2-H = 1.5 Hz, J3-H,2-H = 3.0 Hz,
1 H, 2-H), 4.94 (m, 1 H, 5-H), 4.55 (m, 1 H, 1-H), 3.90 (d,
31
7.1, 25.4 (JC,P = 44 Hz), 20.5, 20.5, 20.0 ppm. P NMR
, 25 °C): δ = 16.15 ppm. Relevant signals for the
gem
3
(162 MHz, CDCl
3
J
6-H,6Ј-H = 12.1 Hz, 1 H, 6-H), 3.82 (dd, J5-H,6Ј-H = 9.6 Hz, 1
1
minor diastereoisomer: H NMR (400 MHz, CDCl
8
=
3
3
, 25 °C): δ =
H, 6Ј-H), 3.35 (s, 3 H, OMe), 2.82 (s, 2 H, fdn), 1.73 (s, 3 H, OAc),
4
3
3
13
.36 (d, JH,P = 1.5 Hz, 1 H, N=CH), 5.78 (t, J3-H,4-H = J3-H,2-H
6 6
1.53 (s, 3 H, OAc) ppm. C NMR (100 MHz, C D , 25 °C) for the
3
9.6 Hz, 1 H, 3-H), 5.19 (d, J1-H,2-H = 7.8 Hz, 1 H, 1-H), 3.39 (s,
two diastereoisomers: δ = 169.7, 169.6, 169.5, 169.4, 166.7, 166.3,
164.1 (2 C), 163.9, 153.0 (2 C), 152.6, 152.2, 152.1, 137.8 (2 C),
3
transJH,P = 9.6 Hz, 1 H, fdn) ppm.
H, OMe), 2.61 (t, JH,H
=
Eur. J. Inorg. Chem. 0000, 0–0
7
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Job/Unit: I42456
/KAP1
Date: 21-07-14 12:06:19
Pages: 11
www.eurjic.org
FULL PAPER
3
3
1
1
7
37.5, 135.5, 134.2, 133.8, 130.9, 130.4, 129.4, 129.3, 129.2, 129.0,
28.7, 125.6, 122.9, 122.7 (2 C), 122.6 (2 C), 104.0, 99.3, 99.0, 70.8,
0.3, 70.2, 70.0, 69.9, 69.8, 69.6, 68.5, 65.6, 63.4, 56.5, 55.7, 20.5
3J1-H,2-H = 3.6 Hz, 1 H, 1-H), 4.12 (t, J5-H,6-H = J5-H,4-H = 9.3 Hz,
3
3
1 H, 5-H), 3.90 (t, 1 H, 6Ј-H), 3.62 (t, J3-H,4-H = J3-H,2-H = 9.1 Hz,
1 H, 3-H), 3.30 (dd, covered by the signal of the solvent, 2-H), 3.16
3
trans
(2 C), 20.3 (2 C), 20.2, 20.1, 19.3, 19.2 ppm.
(m, 2 H, 4-H, fdn), 2.94 (t, JH,H
2
=
J
H,P = 9.7 Hz, 1 H, fdn),
.50 (s, 3 H, OMe) ppm. C NMR (100 MHz, CD OD, 25 °C): δ
171.4, 140.9, 140.5, 138.5, 136.2, 136.1, 135.6, 135.5, 135.3, 134.3,
33.3, 132.9, 131.8, 131.5, 131.4, 131.0, 125.0, 102.0, 89.4, 76.4,
1
3
3
General Procedure for the Preparation of the [Pd(ligand*)(fdn)]
Complexes: The desired [Pd(ligand)(fdn)] complex (0.50 mmol) was
suspended in methanol (5 mL), and KOH was added (2.8 mg,
=
1
7
3
1
5.0, 74.9, 73.5, 59.7, 56.2, 32.1, 26.5, 25.7, 25.3, 19.7 ppm.
P
0
.050 mmol). The reaction was monitored by NMR spectroscopy;
small samples of the solution were taken, the solvent was evapo-
rated, and the residue was dissolved in CD OD. After completion
of the reaction, the solution was concentrated to a volume of
.5 mL, and the product was precipitated by the addition of diethyl
NMR (162 MHz, CD
for the minor diastereoisomer: H NMR (400 MHz, CD
3
OD, 25 °C): δ = 20.2 ppm. Relevant signals
1
3
OD,
5 °C): δ = 8.42 (d, JH,P = 2.0 Hz, 1 H, N=CH), 4.57 (d,
3
4
2
gem
3
J
6-H,6Ј-H = 10.6 Hz, 1 H, 6-H), 4.47 (d, J1-H,2-H = 4.5 Hz, 1 H,
0
3
1
1
-H) ppm. P NMR (162 MHz, CD
3
OD, 25 °C): δ = 19.7 ppm.
ether (10 mL). The yellow, microcrystalline product was washed
three times with diethyl ether and dried under vacuum (yields 80–
[
Pd(PN-M6*)(fdn)]: C30 PPd (650.0): calcd. C 55.44, H
.65, N 6.46; found C 55.76, H 4.87, N 6.48. Relevant signals for
the major diastereoisomer: H NMR (400 MHz, CDCl
30 3 5
H N O
9
5%).
Pd(PN-G1*)(fdn)]: C29
.44, N 6.61; found C 54.39, H 4.28, N 6.32. Relevant signals for
4
1
3
, 25 °C): δ
[
4
28 3 5
H N O PPd (635.94): calcd. C 54.77, H
3
=
8.37 (br s, 1 H, N=CH), 4.79 (d, J6-H,6Ј-H = 11.0 Hz, 1 H, 6-H),
4.47 (s, 1 H, 1-H), 3.68 (t, J3-H,4-H = 3J5-H,4-H = 9.5 Hz, 1 H, 3-
3
1
the major diastereoisomer: H NMR (400 MHz, CD
3
OD, 25 °C):
3
cis
3
δ = 8.69 (d, 4
H), 3.20 (dd, JH,H = 9.6,
=
JH,P = 2.9 Hz, 1 H, fdn), 2.89 (t, JH,H
JH,P, 1 H, fdn), 2.61 (s, 3 H, OMe) ppm. Relevant signals for
the minor diastereoisomer: H NMR (400 MHz, CDCl , 25 °C): δ
3
J
H,P = 2.5 Hz, 1 H, N=CH), 7.80–7.10 (m, 28 H,
trans
3
aromatic), 4.55 (d, J1-H,2-H = 8.3 Hz, 1 H, 1-H), 2.81 (t, 1 H, 2-H)
1
ppm. 31P NMR (162 MHz, CD
3
OD, 25 °C): δ = 22.9 ppm. Rel-
3
1
= 8.37 (br s, 1 H, N=CH), 4.71 (d, J6-H,6Ј-H = 11.3 Hz, 1 H, 6-H),
evant signals for the minor diastereoisomer: H NMR (400 MHz,
4.48 (s, 1 H, 1-H), 3.65 (t, J3-H,4-H = 3J5-H,4-H = 9.5 Hz, 1 H, 3-
3
4
3
CD OD, 25 °C): δ = 8.61 (d, JH,P = 2.8 Hz, 1 H, N=CH), 4.43 (d,
3
cis
3
3
31
H), 3.11 (dd, JH,H = 9.6,
=
JH,P = 3.0 Hz, 1 H, fdn), 2.74 (t, JH,H
JH,P, 1 H, fdn), 2.53 (s, 3 H, OMe) ppm. The other signals
are in the following regions: H NMR (400 MHz, CDCl , 25 °C):
3
δ = 7.65–7.10 (m, aromatic), 4.20–3.55 (m) ppm. C NMR
(100 MHz, CDCl , 25 °C): δ = 169.3, 168.5, 137.9–129.3 (aro-
matic), 125.1, 123.0, 100.8, 100.7, 73.2, 72.4, 72.2, 70.9 (2 C), 70.4,
0.0, 69.7, 54.4, 54.2, 25.2, 24.7, 23.8 (JP,C = 43 Hz), 22.6 (JP,C =
4 Hz) ppm. P NMR (162 MHz, CDCl
J
1-H,2-H = 8.3 Hz, 1 H, 1-H) ppm. P NMR (162 MHz, CD
3
OD,
trans
2
5 °C): δ = 21.9 ppm. The other signals are in the following regions:
1
1
H NMR (400 MHz, CD
3
OD, 25 °C): δ = 3.98–3.90 (m, 3 H), 3.85–
1
3
3
(
.75 (m, 2 H), 3.69–3.53 (m, 4 H), 3.52–3.42 (m, 4 H), 3.16–3.00
m, 2 H) ppm. 1 C NMR (100 MHz, CD
3
3
3
OD, 25 °C): δ = 172.79,
1
1
71.56, 164.0–130.0 (aromatic), 128.7, 128.5, 126.4 (2 C), 105.6,
04.4, 83.5, 83.0, 81.9, 81.8, 76.8, 76.7, 74.8, 73.9, 66.4, 65.7, 27.3
7
4
3
1
3
, 25 °C): δ = 17.8 ppm.
(d, JP,C = 44 Hz), 26.9 (d, JP,C = 59 Hz, 2 C), 26.4 (d, JP,C = 46 Hz)
ppm.
[Pd(NN-G2*)(fdn)]: C17
20 4 5
H N O
Pd (466.8): calcd. C 43.74, H 4.32,
N 12.00; found C 43.59, H 4.32, N 11.67. Relevant signals for the
[
4
Pd(PN-G2*)(fdn)]: C30
.65, N 6.46; found C 55.81, H 4.50, N 6.39. Relevant signals for
30 3 5
H N O PPd (650.0): calcd. C 55.44, H
1
major diastereoisomer: H NMR (400 MHz, CD
3
OD, 25 °C): δ =
3
1
8.63 (s, 1 H, N=CH), 4.92 (d, J
1-H,2-H
= 7.7 Hz, 1 H, 1-H), 3.50
the major diastereoisomer: H NMR (400 MHz, CD
3
OD, 25 °C):
δ = 8.46 (d, 4
3
(s, 3 H, OMe), 3.02 (AB q, 2 H, fdn) ppm. Relevant signals for the
1-H,2-H
JH,P = 2.9 Hz, 1 H, N=CH), 5.12 (d, J =
1
3
3
minor diastereoisomer: H NMR (400 MHz, CD OD, 25 °C): δ =
7
.9 Hz, 1 H, 1-H), 4.36 (t, J3-H,4-H = J3-H,2-H = 9.2 Hz, 1 H, 3-
3
3
H), 3.93 (dd, J6-H,6Ј-H = 11.4 Hz, 3
3
8.60 (s, 1 H, N=CH), 4.90 (d, J
1-H,2-H
= 7.7 Hz, 1 H, 1-H), 3.57
J
5-H,6-H = 1.4 Hz, 1 H, 6-H),
H,H = 8.0 Hz, 1 H, fdn), 2.86 (t,
H,H = JH,P, 1 H, fdn) ppm. P NMR (162 MHz, CD OD, 25 °C):
δ = 18.9 ppm. Relevant signals for the minor diastereoisomer: H
.21 (s, 3 H, OMe), 3.16 (d, 3
J
(s, 3 H, OMe), 2.97 (s, 2 H, fdn) ppm. The other signals are in the
3
J
1
3
31
following regions: H NMR (400 MHz, CD OD, 25 °C): δ = 8.87
3
3
1
(m, aromatic), 8.16 (m, aromatic), 7.95 (m, aromatic), 7.64 (m, aro-
4
matic), 4.11 (t, J
H,H
= 8.7 Hz), 3.97–3.85 (m), 3.60–3.32 (m), 3.07–
NMR (400 MHz, CD
3
OD, 25 °C): δ = 8.45 (d, JH,P = 2.7 Hz, 1
1
3
3
2.94 (m) ppm. C NMR (100 MHz, CD OD, 25 °C): δ = 171.32,
H, N=CH), 5.04 (d,
J
1-H,2-H = 7.9 Hz, 1 H, 1-H), 4.22 (t,
3
3
3
gem
171.06, 157.2, 157.1 (2 C), 157.0, 143.8 (2 C), 133.1, 131.5, 127.7,
126.8, 108.2, 106.1, 81.1, 80.7, 80.1, 79.6, 77.7, 74.7, 74.1, 69.8,
65.6, 65.4, 60.5, 60.3, 21.2, 20.9, 18.4 ppm.
J
3-H,4-H = J3-H,2-H = 9.2 Hz, 1 H, 3-H), 3.89 (dd,
6-H,6Ј-H
J =
3
1
(
=
1
(
2
3
1.4 Hz, J5-H,6-H = 1.4 Hz, 1 H, 6-H), 3.10 (s, 3 H, OMe), 3.09
dd, JH,H = 8.0 Hz, JH,P = 3.5 Hz, 1 H, fdn), 2.84 (t, JH,H = JH,P
3
3
31
3
8.0 Hz, 1 H, fdn) ppm. P NMR (162 MHz, CD OD, 25 °C): δ =
8.5 ppm. The other signals are in the following regions: H NMR
[Pd(NN-G6*)(fdn)]: C17
20 4 5
H N O Pd (466.8): calcd. C 43.74, H 4.32,
1
N 12.00; found C 44.01, H 4.36, N 11.66. Relevant signals for the
400 MHz, CD OD, 25 °C): δ = 7.75 (m, 2 H, aromatic), 7.66 (m,
3
1
major diastereoisomer: H NMR (400 MHz, CD
3
OD, 25 °C): δ =
H, aromatic), 7.60–7.30 (m, 22 H, aromatic), 7.08 (m, 2 H), 3.78–
.66 (m, 3 H), 3.55–3.45 (m, 3 H) ppm. 1 C NMR (100 MHz,
3
8
.62 (s, 1 H, N=CH), 4.59 (d, J1-H,2-H = 2.0 Hz, 1 H, 1-H), 4.27
3
3
3
3
(
t, J3-H,4-H = J5-H,4-H = 9.0 Hz, 1 H, 4-H), 3.76 (t, 3J5-H,6-H = J6-
3
CD OD, 25 °C): δ = 170.5, 170.0, 137.8–129.0 (aromatic), 122.2,
1
5
H,6Ј-H = 10.0 Hz, 1 H, 6-H), 3.42 (s, 3 H, OMe), 2.94 (AB q, 2 H,
03.9, 101.4, 82.2, 81.0, 76.8, 76.4, 73.5, 72.9, 70.8, 70.5, 61.6, 61.4,
6.6, 56.2, 23.6, 22.5, 22.3 (d, JP,C = 46 Hz), 21.8 (d, JP,C = 46 Hz)
1
fdn) ppm. Relevant signals for the minor diastereoisomer:
NMR (400 MHz, CD
H
=
3
OD, 25 °C): δ = 8.59 (s, 1 H, N=CH), 4.57
d, J1-H,2-H = 2.0 Hz, 1 H, 1-H), 4.24 (t, J = J
3-H,4-H 5-H,4-H
9.0 Hz, 1 H, 4-H), 3.86 (t, J5-H,6-H = J6-H,6Ј-H = 10.0 Hz, 1 H, 6-
ppm.
Pd(PN-G6*)(fdn)]: C30
.65, N 6.46; found C 55.11, H 4.88, N 6.62. Relevant signals for
3
3
3
(
3
3
[
4
H
30
N
3
O
5
PPd (650.0): calcd. C 55.44, H
H), 3.30 (s, 3 H, OMe), 2.91 (s, 2 H, s, fdn) ppm. The other signals
1
1
the major diastereoisomer: H NMR (400 MHz, CD
δ = 8.51 (d, JH,P = 2.0 Hz, 1 H, N=CH), 8.01 (d, JH,H = 7.8 Hz,
1
3
OD, 25 °C):
are in the following regions: H NMR (400 MHz, CD
3
OD, 25 °C):
4
3
δ = 8.85 (m, 2 H, aromatic), 8.15 (m, 2 H, aromatic), 7.92 (m, 2 H,
3
H, aromatic), 7.84 (m, 1 H, aromatic), 7.72 (t, JH,H = 7.6 Hz, 1
aromatic), 7.62 (m, 2 H, aromatic), 4.48 (m, 2 H), 3.70–3.65 (m, 2
3
13
H, aromatic), 7.59 (t, JH,H = 7.4 Hz, 1 H, aromatic), 7.50–7.15 (m, H), 3.50–3.25 (m, 2 H) ppm. C NMR (100 MHz, CD
3
OD, 25 °C):
1
0 H, aromatic), 4.77 (d, gemJ6-H,6Ј-H = 11.4 Hz, 1 H, 6-H), 4.35 (d,
δ = 166.1, 165.7, 152.8 (2 C), 152.5, 152.3, 139.0 (2 C), 128.1 (2 C),
Eur. J. Inorg. Chem. 0000, 0–0
8
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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/KAP1
Date: 21-07-14 12:06:19
Pages: 11
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FULL PAPER
126.3 (2 C), 122.4 (2 C), 122.0 (2 C), 99.4, 99.03, 73.4 (2 C), 72.0
Table 8. Crystallographic data.
(
(
2 C), 71.8 (2 C), 70.3, 69.2, 64.0, 63.0, 54.5, 53.8, 16.5 (2 C), 15.3
2 C) ppm.
Empirical formula
Mr
23 26 4 8
C H N O Pd
592.88
[
Pd(NN-M6*)(fdn)]: C17
H
20
N
4
O
5
Pd (466.8): calcd. C 43.74, H 4.32, Crystal system, space
triclinic, P1
group
N 12.00; found C 43.39, H 4.18, N 12.36. Relevant signals for the
1
Temperature /K
a, b, c /Å
α, β, γ /°
V /Å
Z
293
major diastereoisomer: H NMR (400 MHz, CD
3
OD, 25 °C): δ =
9.3980(9), 11.8020 (12), 12.8400 (9)
69.362 (8), 84.886 (10), 70.297 (8)
1254.0 (2)
2
604
Mo-Kα
0.79
0.22ϫ0.17ϫ0.11
1.57
Bruker-Nonius KappaCCD
normal-focus sealed X-ray tube
17102
9727
7323
8
.63 (s, 1 H, N=CH), 3.30 (s, 3 H, OMe) ppm. Relevant signals for
1
the minor diastereoisomer: H NMR (400 MHz, CD
3
OD, 25 °C):
3
δ = 8.61 (s, 1 H, N=CH), 3.29 (s, 3 H, OMe) ppm. The other
1
signals are in the following regions: H NMR (400 MHz, CD
5 °C): δ = 8.85 (m, aromatic), 8.14 (m, aromatic), 7.92 (m, aro-
matic), 7.70 (m, aromatic), 4.50 (m), 4.20 (m), 3.78 (m), 3.63 (m),
3
OD,
F(000)
2
Radiation type
–
1
μ /mm
Crystal size /mm
2
1
1
.91 (m, fdn) ppm. 13C NMR (100 MHz, CD
3
OD, 25 °C): δ =
–
3
D
calcd. /Mgm
70.8, 170.4, 157.6 (2 C), 157.3 (2 C), 143.8 (2 C), 132.8 (2 C),
31.0 (2 C), 127.1, 126.8, 105.7, 105.4, 75.9, 75.4 (2 C), 75.1, 74.9
2 C), 73.3, 73.1, 68.8, 67.7, 58.9, 58.2, 21.3 (2 C), 19.9 (2 C) ppm.
Diffractometer
Radiation source
Measured reflections
Independent reflections
Observed reflections
(
X-ray Crystal-Structure Determination of [Pd(NN-G2)(fdn)]: Crys-
tals suitable for X-ray diffraction were grown by slow evaporation
of a methanol–acetonitrile (1:5) solution at room temperature. A
dark yellow crystal (0.22ϫ0.17ϫ0.11 mm) was mounted at room
temperature, and the data were collected with a Bruker-Nonius
Kappa CCD diffractometer equipped with a graphite-monochro-
[IϾ2σ(I)]
Rint
0.055
27.5, 3.3
h = –12, 11
k = –15, 15
l = –16, 16
θmax, θmin /°
Range of h, k, l
mated Mo-K
α
radiation source (λ = 0.71073 Å, CCD rotation
images). Semi-empirical absorption correction (SADABS) was ap-
2
2
2
R [F Ͼ 2σ(F )], wR(F ), S 0.047, 0.093, 1.02
[23]
plied. The structure was solved by direct methods (SHELXS)
(Δ/σ)max
Δρmax /eÅ
Δρmin /eÅ
Flack parameter
Parameters
0.002
0.54
–0.55
0.02(3)
651
2
–3
and refined by the full-matrix least-squares method on F against
all independent measured reflections (SHELXL).[
23]
All non-
–3
hydrogen atoms were refined anisotropically. The final refinement
converged to an R value of 0.0474 for 7323 reflections with
IϾ2σ(I) and 0.0796 for all 9727 reflections (Table 8).
Number of restraints
3
CCDC-995160 contains the supplementary crystallographic data
for this article. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
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of phenylboronic acid (0.55 mmol, 67 mg) and 4-bromanisole
(0.50 mmol, 63 μL) in absolute ethanol (1 mL) were added a solu-
tion of potassium carbonate (1.00 mmol, 138 mg) in water (2 mL)
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(3ϫ10 mL), dried with anhydrous sodium sulfate, filtered and con-
centrated under vacuum. The solution was filtered through a short
pad of silica and then chromatographed over silica gel (eluent: hex-
aneǞhexane/ethyl acetate 4:1). The structure of the pure product
was confirmed by MS and by comparison of the NMR spectra
with previously reported data.
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Published Online: ᭿
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© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Job/Unit: I42456
/KAP1
Date: 21-07-14 12:06:19
Pages: 11
www.eurjic.org
FULL PAPER
Cross-Coupling
G. Tarantino, M. Curcio, A. Pica,
A. Carpentieri, M. E. Cucciolito, F. Ruffo,
A. Vitagliano, M. Lega* ................. 1–11
Hydrophilic Pd0 Complexes Based on
Sugars for Efficient Suzuki–Miyaura
Coupling in Aqueous Systems
Sugar-derived hydrophilic Pd0 complexes
are prepared and tested in aqueous Suzuki–
Miyaura cross-coupling reactions. These
conditions allow the green and sustainable
synthesis of biaryls. The best catalysts
achieve very good performances [turnover
Keywords: Synthetic methods
chemistry / Cross-coupling / N ligands /
Palladium
/ Green
4
–1
frequencies (TOFs) up to 3.5ϫ10 h ;
catalyst loadings down to 0.0010 mol-%],
among the best reported for this reaction
in aqueous conditions.
Eur. J. Inorg. Chem. 0000, 0–0
11
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim