Calixarene-derived mono-iminophosphoranes: Highly efficient ligands for palladium- and nickel-catalysed cross-coupling

Article abstract of DOI:10.1002/adsc.201300091

The first mono-iminophosphoranes based on a calix[4]arene skeleton have been synthesised and tested in the arylation of aryl bromides and aryl chlorides. Combining these ligands with [Pd(OAc)₂] or [Ni(cod) ₂] resulted in highly active Suzuki-Miyaura and Kumada-Tamao-Corriu cross-coupling catalysts, respectively. TOFs up to ca. 4×10⁵ mol(ArBr)×mol(M)^-1×h^-1 were obtained in each case. The remarkable activities observed probably arise from the ligands' ability to form complexes with cavity-entrapped "MArX" moieties (endo-complexes), their highly crowded metal environment favouring formation of mono-ligated intermediates over that of less reactive bis-ligated ones. Possible supramolecular interactions within the cavity involving the receptor wall and the aromatic substrate may also significantly influence the reaction rates, notably by increasing the proportion of endo-complexes. Copyright

Full text of DOI:10.1002/adsc.201300091

FULL PAPERS
DOI: 10.1002/adsc.201300091
Calixarene-Derived Mono-Iminophosphoranes: Highly Efficient
Ligands for Palladium- and Nickel-Catalysed Cross-Coupling
Laure Monnereau,a David Sꢀmeril,a,* and Dominique Matta,*
a
Laboratoire de Chimie Inorganique Molꢀculaire et Catalyse, Institut de Chimie UMR – CNRS 7177, Universitꢀ de
Strasbourg, 67008 Strasbourg Cedex, France
Fax : (+33)-3-6885-1637; phone: (+33)-3-6885-1719; e-mail: dsemeril@unistra.fr or dmatt@unistra.fr
Received: January 30, 2013; Published online: April 30, 2013
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300091.
Abstract: The first mono-iminophosphoranes based vouring formation of mono-ligated intermediates
on a calix[4]arene skeleton have been synthesised over that of less reactive bis-ligated ones. Possible
and tested in the arylation of aryl bromides and aryl supramolecular interactions within the cavity involv-
chlorides. Combining these ligands with [Pd
ACHTUNGRTEN(NGNU OAc)2] ing the receptor wall and the aromatic substrate may
or [Ni(cod)2] resulted in highly active Suzuki– also significantly influence the reaction rates, notably
ACHTUNGTRENNUNG
Miyaura and Kumada–Tamao–Corriu cross-coupling by increasing the proportion of endo-complexes.
catalysts, respectively. TOFs up to ca. 4ꢁ105 mol-
ACHTUNGTRENNUNG
(ArBr)·mol(M)ꢀ1·hꢀ1 were obtained in each case.
The remarkable activities observed probably arise Keywords: calix[4]arenes; cross-coupling; iminophos-
from the ligandsꢂ ability to form complexes with phoranes; Kumada–Tamao–Corriu reaction; nickel;
cavity-entrapped “MArX” moieties (endo-com- palladium; supramolecular catalysis; Suzuki–Miyaura
plexes), their highly crowded metal environment fa- reaction
Introduction
N bond is in fact a single bond reinforced by negative
hyperconjugation of the lone pair of the nitrogen
Iminophosphoranes, also termed phosphazenes or atom onto other orbitals centred on the phosphorus
phosphinimines, are analogues of Wittig compounds atom.[1,2]
(R3P=CR’2) in which the alkylidene group has been
Iminophosphoranes can bind transition metals via
substituted by an NR unit. They are generally de- their nitrogen atom,[3–12] but their binding strength is
scribed in terms of two mesomeric forms, one contain- rather weak in comparison with that of imines. To in-
ing a P=N double bond (ylene), the other having crease their capacity to form metal complexes, they
+
ꢀ
ꢀ
a zwitterionic ylidic (P N ) structure (Scheme 1). are often covalently associated with another, stronger
ꢀ
The phosphorus substituents strongly influence the P
donor that enables them to bind as chelate species. It
N bond length and polarisation, and therefore play is noteworthy that this class of ligands has only spar-
a major role in controlling the relative weight of the ingly been investigated in homogeneous catalysis. A
two mesomeric forms. Iminophosphoranes are usually few studies have focussed on their use in cross-cou-
represented as possessing
a phosphorus-nitrogen pling reactions, in which the iminophosphoranes em-
double bond, this accounting for its short length. ployed were all potential chelators, particular exam-
However, this representation is only used for the sake ples being bis-iminophosphoranes[13] or iminophos-
ꢀ
of simplicity, theoretical analysis showing that the P
phoranes containing another coordinating func-
tion.[14–16] In the present study, we describe the synthe-
sis of the first mono-iminophophoranes based on
a calix[4]arene unit and their use in Suzuki–Miyaura
and Kumada–Tamao–Corriu (KTC) cross-coupling.
Calixarenes are valuable synthons for the construction
of receptor ligands and/or of sterically demanding li-
gands.[17–19]
Scheme 1. The two low-energy mesomeric forms of an imi-
nophosphorane.
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Results and Discussion
tern exactly as expected for the corresponding [M+
H]+ ion. The 31P NMR spectra all displayed a singlet
Staudinger condensation[20] of calixarenyl-phosphine appearing in a range (ꢀ11–0 ppm) that is typical for
1 with aryl azides 2–6 led quantitatively to the imino- iminophosphoranes.[7] Each 1H NMR spectrum was
phosphorane-calix[4]arenes
7–11,
respectively consistent with a Cs-symmetrical molecule. The coni-
(Scheme 2). Their formation was confirmed by cal conformation of the calix[4]arene moieties was in-
MALDI-TOF analysis, each mass spectrum being ferred from the 13C NMR spectra, in which the two
characterised by a single peak with the isotopic pat- ArCH2Ar signals appeared at ca. 31 ppm.[21] The syn-
thesised iminophosphoranes were only moderately
stable when not kept under nitrogen, their reaction
with air leading quantitatively after few hours to
phosphine oxide 12 and the corresponding aniline de-
rivative.
The five iminophosphoranes were found to be suit-
able for metal binding (Scheme 3). For example, imi-
nophosphorane 9 gave quantitatively complex 13
when reacted with [AuCl
thiophene). Reaction of 9 with [PdCl
H: N,N-dimethylbenzylamine) led to a partial conver-
sion to the complex [PdCl(dmba)(9)] (14) (see the
Supporting Information, Schemes S-2 and S-3). Reac-
tion of two equiv. of 9 with [PdCl2A(PhCN)2] gave the
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
Scheme 2. Synthesis of iminophosphoranes 7–11.
CHTUNGTRENNUNG
Scheme 3. Synthesis of complexes 13–15.
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Calixarene-Derived Mono-Iminophosphoranes: Highly Efficient Ligands
Scheme 4. Suzuki–Miyaura and Kumada–Tamao–Corriu cross-coupling reactions.
bis-iminophosphorane complex 15, which in contrast ligand inhibited the catalytic reaction (Table 1,
to 14 did not undergo ligand dissociation in solution. entry 10). In view of these findings, the following runs
The 31P NMR spectrum revealed that the phosphorus were carried out with an L:Pd ratio of 2:1.
signal of ligand 9 had undergone a downfield shift of
Using the optimal conditions defined above
30.8 ppm upon metal complexation (d=29.9 ppm in (2 equiv. of ligand per palladium atom, NaH, 1008C,
15). Whether this shift is typical of a cis or trans com- 1 h reaction time), the following runs were carried out
plex species is unknown. Dissociation of both imino- using an ArBr/Pd ratio of 105 (10 ppm of palladium).
phosphorane ligands was observed upon addition of The highest conversions were obtained with ligand 10
PPh3 or tetrahydrothiophene in excess to 15, but the (Table 2). For example, while this ligand gave full
complex was stable in tetrahydrofuran as well as diox- conversion of 2-bromo-6-methoxynaphthalene and 1-
ane.
bromonaphthalene (Table 2, entries 3 and 4), the less
Iminophosphoranes 7–11 were assessed both in pal- reactive substrates 2-bromoanisole and 2-bromoto-
ladium-catalysed Suzuki–Miyaura and nickel-cata- luene resulted in conversions of 59.7 and 76.4%, re-
lysed Kumada–Tamao–Corriu cross-coupling reactions spectively (Table 2, entries 2 and 6).
(Scheme 4). Each catalyst was generated in situ by
mixing the ligand and a metal precursor.
Another series of runs was carried out with imino-
phosphoranes 9 and 10 by applying a palladium load-
ing of only 1 ppm (ArBr/Pd ratio of 106) and
(Scheme 5 and Supporting Information, Table S-3).
With the unhindered substrates, the observed activi-
Suzuki–Miyaura Cross-Coupling with Aryl Bromides
ties
were
higher
than
2.1ꢁ105 mol-
These runs were carried out in dioxane at 1008C for
(ArBr)·mol(Pd)ꢀ1·hꢀ1. The highest activity was found
1 hour using two equivalents of iminophosphorane 9 in the arylation of 2-bromo-6-methoxynaphthalene
per palladium atom. The highest conversion observed with ligand 10
[TOF=4ꢁ105 mol-
(ArBr)·mol(Pd)ꢀ1·hꢀ1].
To complete the evaluation of the ligands, the steri-
for 4-bromoanisole (91.1%) was obtained in the pres-
ence of NaH as base (Table 1, entries 1–5 and 8). No
ACHTUNGTRENNUNG
significant differences in activity were seen for ligand/ cally unhindered substrates were also tested at room
palladium ratios between 1 and 2.5, indicating that temperature. For each individual substrate, the catalyt-
the active species contains only one iminophosphor- ic tests were carried out with the ligand that gave the
ane ligand (Table 1, entries 6–9). A large excess of highest conversion when operating at 1008C
(Table 3). The 1 h runs were achieved with a palladium
loading of 0.1 mol%. Under these conditions, the ob-
served conversions lay in the range 40.2–86.6%. The
highest conversion was observed in the arylation of 2-
Table 1. Suzuki–Miyaura cross-coupling of 4-bromoanisole
with phenylboronic acid – search for optimal conditions.[a]
bromo-6-methoxynaphthalene (Table 3, entry 3). Full
conversions were reached after 2–3 h (Supporting In-
formatiion, Table S-4). The catalytic system still re-
mained satisfactory when using a catalyst loading of
only 0.01 mol% (Table 3).
Entry
9/Pd
Base
Conversion [%]
1
2
3
4
5
6
7
8
9
2/1
2/1
2/1
2/1
2/1
1/1
1.5/1
2/1
2.5/1
5/1
K3PO4
Cs2CO3
K2CO3
KOH
NEt3
NaH
NaH
NaH
NaH
61.3
50.1
42.1
40.6
15.5
84.3
90.8
91.1
88.2
54.6
Suzuki–Miyaura Cross-Coupling with Aryl Chlorides
The two iminophosphoranes bearing p-butylphenyl
(9) and o-anisyl (10) substituents, respectively, were
tested in the cross-coupling of PhB(OH)2 with aryl
chlorides (Table 4). Applying a palladium loading of
1 mol% resulted in good conversions after 5 h for the
activated aryl chlorides (1-chloro-4-nitrobenzene, 4-
10
NaH
[a]
[PdACHTUNGTRENNUNG
(OAc)2] (5ꢁ10ꢀ6 mmol, 1ꢁ10ꢀ3 mol%), 9, ArBr
(0.5 mmol), PhB(OH)2 (0.122 g, 1.0 mmol), base
(1.0 mmol), dioxane (1.5 mL), decane (0.050 mL), 1008C,
1 h. The conversions were determined by GC, the cali-
brations being based on decane.
chloroacetophenone
and
4-chlorobenzonitrile;
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Table 2. Palladium-catalysed Suzuki–Miyaura cross-coupling of aryl bromides using iminophosphoranes 7-11 and applying
a ArBr/Pd ratio of 105.[a]
Entry
ArBr
Iminophosphorane
7
8
9
10
11
1
2
conv. [%]
conv. [%]
80.8
72.9
91.1
40.2
87.1
81.7
46.1
100
27.3
80.0
59.7
100
5.8
3
4
conv. [%]
conv. [%]
100
100
100
65.6
55.8
100
30.5
5
6
conv. [%]
conv. [%]
87.6
42.3
39.9
65.9
44.3
38.5
99.7
76.4
29.5
34.3
7
8
conv. [%]
conv. [%]
55.8
90.4
68.3
75.5
86.8
93.7
100
41.5
70.9
98.5
[a]
[PdACHTUNGTRENNUNG
(OAc)2] (5ꢁ10ꢀ6 mmol, 1ꢁ10ꢀ3 mol%), iminophosphorane (1ꢁ10ꢀ5 mmol, 2ꢁ10ꢀ3 mol%), ArBr (0.5 mmol),
PhB(OH)2 (0.122 g, 1.0 mmol), NaH (60% dispersion in mineral oil) (0.040 g, 1.0 mmol), dioxane (1.5 mL), decane
(0.050 mL), 1008C, 1 h. The conversions were determined by GC, the calibrations being based on decane.
Scheme 5. Maximal activities observed for the cross-coupling product formed in the Suzuki–Miyaura reaction using 1 ppm of
(ArBr)·mol(Pd)ꢀ1·hꢀ1.
[PdACHTUNGTRENNUNG(OAc)2] (cf. Supporting Information, Table S-3). TOFs expressed in molACHUTNGTRENNUGN
Table 4, entries 1, 2, 4, 5, 7 and 8) and after 24 h for Kumada–Tamao–Corriu Cross-Coupling with Aryl
the deactivated ones (4-chloroanisole and 4-chloroto- Bromides
luene; Table 4, entries 9–13). When the tests with the
activated aryl chlorides were carried at room temper- For the Kumada–Tamao–Corriu cross-coupling of aryl
ature, the conversions dropped significantly (Table 4, bromides, the catalytic system was generated in situ
entries 3, 6 and 9).
starting from [NiACHTGUNTERNNU(G cod)2] and iminophosphoranes 7, 10
or 11 in 1,4-dioxane at 1008C. To prevent decomposi-
tion of the active species, the runs were performed
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Calixarene-Derived Mono-Iminophosphoranes: Highly Efficient Ligands
Table 3. Suzuki–Miyaura cross-coupling carried out at room temperature.[a]
Entry
ArBr
Iminophosphorane
[Pd
0.1
(OAc)2] [mol%]
Conv. [%]
TOF [molACTHNGUTERNNUG
(ArBr)·mol(Pd)ꢀ1·hꢀ1]
1
2
41.7
12.0
420
1200
9
0.01
3
4
0.1
0.01
86.6
48.2
870
4820
10
10
5
6
0.1
0.01
67.1
20.8
670
2080
7
8
0.1
0.01
52.0
15.9
520
1590
9
9
10
0.1
0.01
40.2
12.0
400
1200
10
10
11
12
0.1
0.01
78.0
29.8
780
2980
[a]
[PdACHTUNGTRENNUNG(OAc)2], iminophosphorane (2 equiv./Pd), ArBr (0.5 mmol), PhB(OH)2 (0.122 g, 1.0 mmol), NaH (60% dispersion in
mineral oil) (0.040 g, 1.0 mmol), dioxane (1.5 mL), decane (0.050 mL), 258C, 1 h.
Table 4. Palladium-catalysed Suzuki–Miyaura cross-coupling of aryl chlorides.
Entry
ArCl
Iminophosphorane
Temperature [8C]
Time [h]
Conversion [%]
1[a]
2[a]
3[b]
4[a]
5[a]
6[b]
7[a]
8[a]
9[b]
10[a]
11[a]
9
10
9
9
10
9
9
10
9
9
100
100
25
100
100
25
100
100
25
100
100
5
5
24
5
5
24
5
5
24
24
24
87.6
78.3
28.9
85.7
67.5
14.2
76.2
73.1
11.3
73.3
66.0
10
12[a]
9
10
100
100
24
24
66.3
51.0
13[a]
[a]
[PdACHTUNGTRENNUNG
(OAc)2] (2.5ꢁ10ꢀ3 mmol, 1 mol%), iminophosphorane (5ꢁ10ꢀ3 mmol, 2 mol%), dioxane (0.75 mL), ArCl
(0.25 mmol), PhB(OH)2 (0.061 g, 0.5 mmol), NaH (60% dispersion in mineral oil) (0.020 g, 0.5 mmol), decane
(0.025 mL). The conversions were determined by GC, the calibrations being based on decane.
[b]
[PdACHTUNGTRENNUNG
(OAc)2] (7.5ꢁ10ꢀ3 mmol, 3 mol%), iminophosphorane (1.5ꢁ10ꢀ2 mmol, 6 mol%).
using two equiv. of ligand per nickel. Applying Comparison with Other Ligands
a ArBr/Ni ratio of 105 (10 ppm of nickel), resulted in
moderate to good conversions after 1 h reaction time In a recent study, we have shown that calixarenyl-
(Table 5). The highest activities were obtained in the monophosphine 1 is ca. 2.3 times more active than
arylation of 2-bromo-6-methoxynaphthalene and 1- PPh3 in the cross-coupling of 4-bromotoluene with
bromonaphthalene, which were converted in 68.8 and phenylboronic acid.[17] Interestingly, the arylation of
85.6% yield, respectively (Table 5, entries 3 and 5). 4-bromotoluene led to higher activities when imino-
ACTHNUTRGNEUNG
Reducing the metal loading to 1 ppm led to activities phosphorane 10 [2.7ꢁ105 mol(ArBr)·mol(Pd)ꢀ1·hꢀ1)
that remained remarkably high, 3.04ꢁ105 mol- was employed instead of calixarenyl-monophosphine
(ArBr)·mol(Ni)ꢀ1·hꢀ1 for 2-bromo-6-methoxynaphtha- [TOF=1.52ꢁ105 mol(ArBr)·mol(Pd)ꢀ1·hꢀ1)
lene and 3.9ꢁ105 mol(ArBr)·mol(Ni)ꢀ1·hꢀ1 for 1-bro- (Table 6, entries 2 and 3). For comparison, the runs
monaphthalene (Table 5, entries 4 and 6). carried out with the PPh3-derived iminophosphorane
A
1
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
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Table 5. Nickel-catalysed Kumada–Tamao–Corriu cross-cou-
pling of aryl bromides.
Entry ArBr
Iminophosphoranes
7
10
11
conv.
[%]
TOF
37.9
46.1
42.6
Figure 1. Ligand 16 used for ranking the calixaryl-imino-
phosphoranes.
1[a]
37900 46100 42600
conv.
[%]
TOF
20.8
32.7
23.9
2[a]
16 (Figure 1) led to a TOF of only 2.41ꢁ104 mol-
20800 32700 23900
AHCTUNGTRENNUNG
(ArBr)·mol(Pd)ꢀ1·hꢀ1, which corrresponds to a 10-fold
conv.
[%]
TOF
conv. 30.4
[%]
TOF
conv.
[%]
TOF
conv. 34.4
[%]
TOF
conv.
[%]
TOF
conv.
[%]
TOF
lower activity than that of 10 (Table 6, entries 3 and
5). We also observed that the catalytic reactions per-
formed in the absence of 10 but in the presence of its
hydrolysis products (namely 12 or o-methoxyaniline)
led to considerably lower activities: thus, with phos-
phine oxide 12 the reaction rate dropped by a factor
of 5. With o-methoxyaniline, the activity was reduced
by a factor of 100 (Table 6, entries 4 and 6). These
findings are a good indication that during the catalytic
runs with iminophosphoranes 7–11, these ligands had
not undergone hydrolysis. Similar observations were
made for the nickel-catalysed Kumada–Tamao–Corriu
coupling reactions (Table 6, entries 7–12).
Is it possible to rationalise the high activities ob-
served with iminophosphoranes 7–11 compared to
those with PPh3? In principle, we have to distinguish
between the Suzuki–Miyaura cross-coupling and the
Kumada–Tamao–Corriu reaction, the corresponding
mechanisms and energetics being different. It is now
well-accepted that in the former reaction, bulky li-
gands, notably phosphines, promote the oxidative ad-
dition step (which is the key step) by facilitating the
formation of mono-ligand Pd(0)-arene complexes,
68.8
60.7
68.7
3[a]
4[b]
68800 60700 68700
17.3 29.7
304000 173000 297000
77.7
85.6
85.5
5[a]
6[b]
77700 85600 85500
38.1 39.0
344000 381000 390000
19.5
20.5
22.4
7[a]
19500 20500 22400
49.3
45.7
45.5
8[a]
49300 45700 45500
[a]
[Ni
phorane
ACHTUNGTRENNUNG
(1.5 mL), ArBr (0.5 mmol), PhMgBr (1 mmol), decane
(0.050 mL), 1008C, 1 h. The conversions were determined
by GC, the calibrations being based on decane. TOFs ex-
pressed in molACHTUNGTRENNUNG
(ArBr)·mol(Ni)ꢀ1·hꢀ1.
[b]
[Ni
ACHTUNGTRENNUNG
(cod)2] (5ꢁ10ꢀ7 mmol, 1ꢁ10ꢀ4 mol%), iminophos-
phorane (1ꢁ10ꢀ6 mmol, 2ꢁ10ꢀ4 mol%).
Table 6. Suzuki–Miyaura and Kumada–Tamao–Corriu cross-coupling reactions - comparison with other ligands.
Entry
Ligand
Metal precursor [mol%]
Conversion [%]
TOF [molACTHNGUTERNNUG
(ArBr)·mol(M)ꢀ1·hꢀ1]
[Pd
1
2
3
4
ACHTUNGTRENNUNG
1ꢁ10ꢀ2
1ꢁ10ꢀ4
1ꢁ10ꢀ4
1ꢁ10ꢀ3
1ꢁ10ꢀ3
1ꢁ10ꢀ2
16.7
15.2
27.0
49.3
24.1
27.3
1670
152000
270000
49300
24100
2730
5
6
[Ni
7
ACHTUNGTRENNUNG
(cod)2] and 1-bromonaphthalene[b]
1ꢁ10ꢀ2
1ꢁ10ꢀ4
1ꢁ10ꢀ4
1ꢁ10ꢀ3
1ꢁ10ꢀ4
1ꢁ10ꢀ2
56.0
38.6
38.1
53.0
5.6
5600
8
9
10
11
12
386000
381000
53000
56000
6310
63.1
[a]
[PdACHTUNGTRENNUNG(OAc)2], ligand (2 equiv./Pd), 4-bromotoluene (0.5 mmol), PhB(OH)2 (0.122 g, 1.0 mmol), NaH (60% dispersion in
mineral oil) (0.040 g, 1.0 mmol), dioxane (1.5 mL), decane (0.050 mL), 1008C, 1 h. The conversions were determined by
GC, the calibrations being based on decane.
[b]
[Ni
ACHTUNGTRENNUNG(cod)2], ligand (2 equiv./Ni), 1-bromonaphthalene (0.5 mmol), PhMgBr (1.0 mmol), dioxane (1.5 mL), decane
(0.050 mL), 1008C, 1 h.
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Calixarene-Derived Mono-Iminophosphoranes: Highly Efficient Ligands
Suzuki–Miyaura reactions performed with “small” ar-
omatic substrates.
The results obtained in the Kumada–Tamao–Corriu
reactions further demonstrate the high efficiency of
the calixarene derivatives 7–11 in cross-coupling reac-
tions. Any explanation of their high efficiency can
only be speculative, as in this reaction the first, irre-
versible step is substrate coordination, and not oxida-
tive addition.[29] Possibly, (Ar Ar’) product dissocia-
ꢀ
tion from the nickel centre is significantly accelerated
by steric effects for those bis-aryls that have been
generated in an endo-complex. In view of the receptor
properties of calixarenes 7–11, it is likely that, as for
the above Pd catalysts, the formation of endo-Ni-
Figure 2. Proposed mono-iminophosphorane palladium(0)
endo-intermediate formed in cross-coupling reactions before
the oxidative addition step.
which are more reactive than the related Pd com-
ACHTUNGTREN(NGNU ArX) complexes occurring after product decomplex-
plexes bearing two ligands (in equilibrium with the ation can be supramolecularly assisted. Of course, for
mono-ligated ones).[22–28] Molecular modelling re- such endo species, mono-ligated intermediates would
vealed that the above iminophosphoranes (L) can again be favoured, these necessarily rendering the
result in [LPd(0)
structures, namely those with the coordinated “Pd(0)-
ACHTUNGTRENNUNG(arene)” moiety located inside the cavity and those
G
N
with it lying outside. The crowding about the metal Conclusions
centre is substantially larger in the isomers with the
“PdACHTUNGTRENNUNG(arene)” entrapped in the cavity (Figure 2) than In summary, we have described the synthesis of the
in the exo-species, so that endo-coordination should first mono-iminophosphoranes based on a calix[4]ar-
favour the formation of mono-ligated intermediates. ene platform. Combined with palladium or nickel,
Furthermore, preliminary calculations showed that in these led to remarkably efficient catalysts for Suzuki–
endo intermediates, pi–pi stacking interactions may Miyaura (Pd) as well as Kumada–Tamao–Corriu (Ni)
occur between the coordinated ArX unit and a phen- cross-coupling reactions. In both reactions, up to ten-
oxy ring of the cavity wall. This supramolecular inter- fold enhancement in catalytic activity was achieved
action may thus directly contribute to the stabilisation with respect to catalysts based on the cavity-free imi-
of endo-coordinated species, and indirectly increase nophosphorane Ph3P=NACTHNUTRGENUG(N o-anisyl). The origin of their
the proportion of mono-ligated species. Interestingly, catalytic performance is likely to arise from their abil-
we observed that in the presence of calixarene 10, the ity to form complexes having cavity-entrapped MArX
arylation of 1-bromo-3,5-di-tert-butylbenzene, a large units that result in a highly crowded metal environ-
substrate which cannot enter the cavity, occurred with ment and therefore favour the formation of mono-li-
only 65.3% conversion under the conditions de- gated intermediates, these being more reactive than
scribed in Table 7, vs. 98.8% in the presence of the bis-ligated complexes. A feature which should in-
cavity-free iminophosphorane 16 (Table 7, entries 1 crease the formation of endo-complexes, whatever the
and 2). These findings support the idea that supra- metal, is the cavityꢂs ability to supramolecularly bind
molecular assistance of the cavity-receptor interaction the aromatic substrate. In the case of the Kumada–
may be helpful for increasing the reaction rate of Tamao–Corriu reaction, the key step in the catalytic
cycle is the formation of an “Ni
(ArX)” moiety after
ꢀ
decomplexation of the Ar Ar’ product, this being fa-
cilitated with intermediates having endo-located
metal centres. Further studies are aimed at exploiting
the supramolecular potential of iminophosphoranes
built on macrocyclic platforms in carbon-carbon bond
forming reactions.
Table 7. Suzuki–Miyaura cross-coupling of 1-bromo-3,5-di-
tert-butylbenzene with phenylboronic acid - comparison with
other ligands.[a]
Entry
Ligand
Conversion [%]
1
2
10
16
65.3
98.8
[a]
[PdACHTUNGTRENNUNG
(OAc)2] (5ꢁ10ꢀ5 mmol, 1ꢁ10ꢀ2 mol%), ligand (1ꢁ
10ꢀ4 mmol, 2ꢁ10ꢀ2 mol%), 1-bromo-3,5-di-tert-butylben-
zene (0.5 mmol), PhB(OH)2 (0.122 g, 1.0 mmol), NaH
(60% dispersion in mineral oil) (0.040 g, 1.0 mmol), diox-
ane (1.5 mL), decane (0.050 mL), 1008C, 1 h. The conver-
sions were determined by GC, the calibrations being
based on decane.
Experimental Section
General Experimental Methods
All reactions were performed in Schlenk-type flasks under
dry nitrogen. Solvents were dried by conventional methods
Adv. Synth. Catal. 2013, 355, 1351 – 1360
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1357

Laure Monnereau et al.
FULL PAPERS
and distilled immediately prior to use. Routine H, 13C and
31P NMR spectra were recorded with an FT Bruker AV-300.
1H NMR spectra were referenced to residual protiated sol-
vent (7.16 ppm for C6D6 and 7.26 ppm for CDCl3), 13C NMR
chemical shifts are reported relative to deuterated solvent
(128.0 ppm for C6D6 and 77.16 ppm for CDCl3) and the
31P NMR data are given relative to external H3PO4. Chemi-
cal shifts and coupling constants are reported in ppm and in
Hz, respectively. Infrared spectra were recorded with
a Bruker FT-IR Alpha-P spectrometer. The catalytic solu-
tions were analysed by using a Varian 3900 gas chromato-
graph equipped with a WCOT fused-silica column (25 mꢁ
0.25 mm, 0.25 mm film thickness). The elemental analysis
was performed by the Service de Microanalyse, Universitꢀ
de Strasbourg. 5-Diphenylphosphino-25,26,27,28-tetrabenzy-
6.67–6.50 (5H, arom. CH), 6.42–6.39 (2H, arom. CH), 4.99
(s, 2H, CH2Ph), 4.96 (s, 2H, CH2Ph), 4.92 and 4.86 (AB spin
system, 4H, CH2Ph, 2J=11.6 Hz), 4.33 and 2.93 (AB spin
1
2
system, 4H, ArCH2Ar, J=13.4 Hz), 4.17 and 2.69 (AB spin
system, 4H, ArCH2Ar, 2J=13.5 Hz), 3.68 (hept, 2H, CH-
ACHUTNGRENNUG CAHTUNGTRENNUGN
(CH3)2, 3J=6.8 Hz), 1.20 (d, 12H, CH(CH3)2, 3J=6.8 Hz);
13C{1H} NMR (75 MHz, CDCl3): d=158.21 (d, arom. Cquat.
O, JPC =3.1 Hz), 155.95, 155.41 (2 s, arom. Cquat.-O), 145.64–
119.55 (arom. C), 76.99 (s, OCH2Ph), 76.89 (s, OCH2Ph),
-
4
76.59 (s, OCH2Ph), 31.86 (s, ArCH2Ar), 29.13 (s, CHACHTUNGTRENNUNG(CH3)2),
24.18 (s, CHACTHNUTRGNEUNG
(CH3)2); 31P{1H} NMR (121 MHz, C6D6): d=
ꢀ8.6 (s, PPh2); IR: n=1327 cmꢀ1 (P=N); anal. calcd. for
C80H74O4PN (Mr=1144.42): C 83.96, H 6.52, N 1.22%;
found: C 84.02, H 6.38, N 1.10%; MS (Maldi-TOF): m/z=
1141.41 [M+H]+ expected isotopic profile.
ACTHNUTRGNEUNG
loxycalix[4]arene (1)[17] and [Ni(cod)2][31] were prepared ac-
5-(4-Butylphenyliminodiphenylphosphoranyl)-25,26,27,28-
1
cording to literature procedures. Aryl azides were synthe-
sized according to a procedure based on the use of TfN3.[32]
Although we have not experienced any problems in han-
dling TfN3, care should be taken due to its potentially ex-
plosive nature. This reagent should be kept in solution and
used immediately after its synthesis.
NMR spectral data of 2-azido-1,3,5-trimethylbenzene
(2),[33] 1-azido-2,6-diisopropylbenzene (3),[32] 1-azido-4-butyl-
benzene (4),[32] 1-azido-2-methoxy-benzene (5),[33] and 1-
azido-4-methoxybenzene (6)[32] were in agreement with
those reported in the literature.
tetrabenzyloxycalix[4]arene (9): H NMR (300 MHz, C6D6):
d=7.77–7.71 (4H, arom. CH), 7.32–7.26 (6H, arom. CH),
7.19–7.00 (26H, arom. CH), 6.77–6.68 (4H, arom. CH), 6.61
3
3
(t, 2H, arom. CH, J=7.5 Hz), 6.54 (t, 1H, arom. CH, J=
7.5 Hz), 6.41 (d, 2H, arom. CH, 3J=6.6 Hz), 5.08 (s, 4H,
CH2Ph), 4.84 (s, 2H, CH2Ph), 4.70 (s, 2H, CH2Ph), 4.33 and
2
2.93 (AB spin system, 4H, ArCH2Ar, J=13.3 Hz), 4.15 and
2.64 (AB spin system, 4H, ArCH2Ar, J=13.3 Hz), 2.57 (t,
2
3
2H, C6H4CH2, J=7.3 Hz), 1.59 (quint, 2H, C6H4CH2CH2,
3J=7.3 Hz), 1.30 (hex, 2H, CH2CH3, 3J=7.2 Hz), 0.84 (t,
3H, CH2CH3, 3J=7.3 Hz); 13C{1H} NMR (75 MHz, C6D6):
d=158.24 (d, Cquat.-O, 4JP,C =3.1 Hz), 155.66, 155.51 (2s,
C
quat.-O), 150.09–123.00 (arom. C), 77.38 (s, OCH2Ph), 77.11
General Procedure for the Synthesis of 5-
(Aryliminodiphenylphosphoranyl)-25,26,27,28-
tetrabenzyloxycalix[4]arenes (7–11)
(s, OCH2Ph), 76.44 (s, OCH2Ph), 35.58 (s, C6H4CH2), 34.62
(s, C6H4CH2CH2), 31.93 (s, ArCH2Ar), 31.63 (s, ArCH2Ar),
22.76 (s, CH2CH3), 14.29 (s, CH2CH3); 31P{1H} NMR
(121 MHz, C6D6): d=ꢀ0.9 (s, PPh2); IR: n=1329 cmꢀ1 (P=
N); anal. calcd. for C78H70O4PN (Mr=1116.37): C 83.92, H
6.32, N 1.25%; found: C 84.04, H 6.23, N 1.12%; MS
(Maldi-TOF): m/z=1116.39 [M+H]+ expected isotopic pro-
file.
5-(2-Methoxyphenyldiphenylphosphoranyl)-25,26,27,28-
tetrabenzyloxycalix[4]arene (10): 1H NMR (300 MHz,
C6D6): d=7.79–7.73 (4H, arom. CH), 7.33–7.27 (9H, arom.
CH), 7.16–7.00 (21H, arom. CH), 6.84–6.70 (6H, arom.
To a solution of 1 (1.00 mmol) in toluene (10 mL) was
added a solution of aryl azide (1.00 mmol) in toluene
(10 mL). After stirring the solution for 16 h at 608C, the re-
action mixture was evaporated to dryness under vacuum to
afford quantitatively the iminophosphorane.
5-(Mesityliminodiphenylphosphoranyl)-25,26,27,28-tetra-
1
benzyloxycalix[4]arene (7): H NMR (300 MHz, C6D6): d=
7.76–7.69 (4H, arom. CH), 7.34–7.28 (6H, arom. CH), 7.20–
3
6.99 (24H, arom. CH), 6.74 (d, 2H, arom. CH, J=7.5 Hz),
3
CH), 6.61 (t, 2H, arom. CH, J=7.0 Hz), 6.58 (t, 1H, arom.
CH, J=7.5 Hz), 6.40 (d, 2H, arom. CH, J=6.6 Hz), 5.06
(s, 4H, CH2Ph), 4.87 (s, 2H, CH2Ph), 4.73 (s, 2H, CH2Ph),
6.61–6.54 (5H, arom. CH), 6.35–6.32 (2H, arom. CH), 4.97
(s, 2H, CH2Ph), 4.93 (s, 2H, CH2Ph), 4.94 and 4.89 (AB spin
system, 4H, CH2Ph, 2J=11.5 Hz), 4.33 and 2.94 (AB spin
3
3
2
2
4.33 and 2.94 (AB spin system, 4H, ArCH2Ar, J=13.3 Hz),
system, 4H, ArCH2Ar, J=13.4 Hz), 4.18 and 2.67 (AB spin
2
2
4.16 and 2.64 (AB spin system, 4H, ArCH2Ar, J=13.3 Hz),
system, 4H, ArCH2Ar, J=13.4 Hz), 2.29 (s, 6H, o-CH3 of
3.31 (s, 3H, CH3OC6H4); 13C{1H} NMR (75 MHz, C6D6): d=
mesityl), 2.12 (s, 3H, p-CH3 of mesityl); 13C{1H} NMR
4
4
157.94 (d, arom. Cquart.-O, JP, C =3.1 Hz), 155.68, 155.48 (2s,
(75 MHz, C6D6): d=158.14 (d, arom. Cquart.-O, JP, C =3.1 Hz),
arom. Cquart.-O), 153.76–112.20 (arom. C), 77.29 (s,
OCH2Ph), 76.99 (s, OCH2Ph), 76.50 (s, OCH2Ph), 54.91 (s,
CH3OC6H4), 31.91 (s, ArCH2Ar), 31.67 (s, ArCH2Ar);
31P{1H} NMR (121 MHz, C6D6): d=0.0 (s, PPh2); IR: n=
1327 cmꢀ1 (P=N); anal. calcd. for C75H64O5PN (Mr=
1090.29): C 82.62, H 5.92, N 1.28%; found: C 82.75, H 5.79,
N 1.21%; MS (Maldi-TOF): m/z=1090.30 [M+H]+ expect-
ed isotopic profile.
155.86, 155.44 (2 s, arom. Cquart.-O), 145.89–122.88 (arom. C),
76.95 (s, OCH2Ph), 76.77 (s, OCH2Ph), 76.66 (s, OCH2Ph),
31.86 (s, ArCH2Ar), 31.76 (s, ArCH2Ar), 22.05 (s, o-CH3 of
mesityl), 21.08 (s, p-CH3 of mesityl); 31P{1H} NMR
(121 MHz, C6D6): d=ꢀ10.8 (s, PPh2); IR: n=1329 cmꢀ1 (P=
N); anal. calcd. for C77H68O4PN (Mr=102.34): C 83.90, H
6.22, N 1.27%; found: C 84.01, H 6.25, N 1.30%; MS
(Maldi-TOF): m/z=1102.39 [M+H]+ expected isotopic pro-
file.
5-(4-Methoxyphenyliminodiphenylphosphoranyl)-
25,26,27,28-tetrabenzyloxycalix[4] arene (11): 1H NMR
(300 MHz, C6D6): d=7.78–7.71 (4H, arom. CH), 7.32–7.27
(6H, arom. CH), 7.16–7.00 (24H, arom. CH), 6.87 (d, 2H,
5-(2,6-Diisopropylphenyliminodiphenylphosphoranyl)-
25,26,27,28-tetrabenzyloxycalix [4]arene (8): 1H NMR
(300 MHz, C6D6): d=7.68–7.62 (4H, arom. CH), 7.33–7.28
3
3
(6H, arom. CH), 7.24 (d, 2H, arom. CH, J=7.7 Hz), 7.16–
arom. CH, J=6.3 Hz), 6.77–6.68 (4H, arom. CH), 6.61 (t,
3
7.00 (23H, arom. CH), 6.78 (d, 2H, arom. CH, J=7.3 Hz),
2H, arom. CH, 3J=7.4 Hz), 6.54 (t, 1H, arom. CH, 3J=
1358
asc.wiley-vch.de
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 1351 – 1360

Calixarene-Derived Mono-Iminophosphoranes: Highly Efficient Ligands
7.3 Hz), 6.40 (d, 2H, arom. CH, 3J=6.4 Hz), 5.08 (s, 4H,
CH2Ph), 4.84 (s, 2H, CH2Ph), 4.71 (s, 2H, CH2Ph), 4.32 and
C), 78.12 (s, OCH2Ph), 78.02 (s, OCH2Ph), 76.61 (s,
OCH2Ph), 35.51 (s, C6H4CH2), 34.40 (s, C6H4CH2CH2), 32.13
(s, ArCH2Ar), 31.82 (s, ArCH2Ar), 23.40 (s, CH2CH3), 14.71
(s, CH2CH3); 31P{1H} NMR (121 MHz, C6D6): d=33.4 (s,
PPh2); anal. calcd. for C78H70AuClNO4P (Mr=1348.79): C
69.46, H 5.23, N 1.04%; found: C 69.58, H 5.47, N 0.88%.
2
2.93 (AB spin system, 4H, ArCH2Ar, J=13.3 Hz), 4.15 and
2
2.64 (AB spin system, 4H, ArCH2Ar, J=13.3 Hz), 3.43 (s,
6H, CH3OC6H4); 13C{1H} NMR (75 MHz, C6D6): d=158.25
4
(d, arom. Cquart.-O, JP,C =2.9 Hz), 155.65, 155.52 (2s, arom.
Cquart.-O), 152.69–114.63 (arom. C), 77.38 (s, OCH2Ph), 77.11
(s, OCH2Ph), 76.43 (s, OCH2Ph), 55.33 (s, CH3OC6H4), 31.92
(s, ArCH2Ar), 31.65 (s, ArCH2Ar); 31P{1H} NMR (121 MHz,
C6D6): d=ꢀ1.2 (s, PPh2); IR: n=1327 cmꢀ1 (P=N); anal.
calcd. for. C75H64O5PN (Mr=1090.29): C 82.62, H 5.92, N
1.28%; found: C 82.51, H 5.98, N 1.33%; MS (Maldi-TOF):
m/z=1090.30 [M+H]+ expected isotopic profile.
Reaction of 9 with [PdCl(o-C6H4CH2NMe2]2
To a stirred solution of 9 (0.050 g, 0.045 mmol) in CH2Cl2
(5 mL) was added a solution of [PdCl(o-C6H4CH2NMe2]2
(0.012 g, 0.022 mmol) in CH2Cl2 (5 mL). After stirring for
0.5 h, the solvent was removed under vacuum to afford
a mixture of complex 14 and free ligand 9. 31P{1H} NMR
(C6D6, 121 MHz): d=26.1 (s, N=PPh2 coordinated to Pd)
and ꢀ0.9 (s br, N=PPh2 free); MS (Maldi-TOF): m/z=
1355.44 [MꢀCl]+ expected isotopic profile for 14 (cf. the
Supporting Information).
5-Diphenylphosphinoyl-25,26,27,28-tetrabenzyloxyca-
lix[4]arene (12): To a solution of 5-diphenylphosphino-
25,26,27,28-tetrabenzyloxycalix[4]arene (1) (0.5 mmol) in
CH2Cl2 (10 mL) was added H2O2 (30% in water, 4 mL,
5.0 mmol). The resulting solution was stirred at room tem-
perature for 2 h. The resulting mixture was treated with
a mixture of CH2Cl2 (10 mL) and water (20 mL). After ex-
traction of the aqueous layer with CH2Cl2 (2ꢁ10 mL), the
organic phases were combined. The resulting solution was
washed with water (2ꢁ10 mL), then dried over Na2SO4 and
evaporated under reduced pressure to afford quantitatively
phosphine oxide 12 as a white solid. 1H NMR (300 MHz,
CDCl3): d=7.43–7.23 (32H, arom. CH), 6.84 (d, 2H, arom.
N,N’-Dichlorido-bis{5-(4-
butylphenyliminodiphenylphosphoranyl)-25,26,27,28-
tetrabenzyloxy-calix[4]arene}palladium(II) (15)
To a stirred solution of 9 (0.050 g, 0.045 mmol) in CH2Cl2
(10 mL) was added a solution of [PdCl2ACHTNUTRGNE(UNG PhCN)2]2 (0.012 g,
0.022 mmol) in CH2Cl2 (5 mL). After stirring for 0.5 h, the
solution was concentrated to ca. 1 mL. Addition of n-hexane
(20 mL) afforded 15 as a brown solid; yield: 0.046 g (75%).
3
CH, J=12.3 Hz), 6.74–6.70 (3H, arom. CH), 6.59–6.53 (2H,
3
arom. CH), 6.44 (d, 2H, arom. CH, J=7.5 Hz), 5.08 and
1H NMR (300 MHz, C6D6): d=7.97 (d, 4H, arom. CH, J=
3
2
5.01 (AB spin system, 4H, CH2Ph, J=11.6 Hz), 4.94 (s, 2H,
3
8.4 Hz), 7.79 (d, 4H, arom. CH, J=8.1 Hz), 7.76 (d, 4H,
CH2Ph), 4.91 (s, 2H, CH2Ph), 4.29 and 3.02 (AB spin
3
2
arom. CH, J=8.0 Hz), 7.32–7.06 (56H, arom. CH), 6.88(d,
system, 4H, ArCH2Ar, J=13.3 Hz), 4.14 and 2.83 (AB spin
4H, arom. CH, 3J=8.1 Hz), 6.75–6.67 (12H, arom. CH),
system, 4H, ArCH2Ar, 2J=13.4 Hz); 13C{1H} NMR
(75 MHz, CDCl3): d=158.75, 155.46, 155.10 (3 s, arom.
Cquart.-O), 137.63–122.49 (arom. C), 77.07 (s, OCH2Ph), 76.75
(s, OCH2Ph), 76.34 (s, OCH2Ph), 31.45 (s, ArCH2Ar), 31.36
(s, ArCH2Ar); 31P{1H} NMR (121 MHz, CDCl3): d=29.1 (s,
O=PPh2); anal. calcd. for. C68H57O5P (Mr=985.15): C 82.90,
H 5.83%; found: C 83.03, H 5.71%.
3
6.44 (d, 4H, arom. H, J=6.6 Hz), 6.02 (t, 2H, arom. CH,
3J=7.3 Hz), 5.08 (s, 8H, CH2Ph), 4.87 (s, 4H, CH2Ph), 4.74
(s, 24, CH2Ph), 4.28 and 2.87 (AB spin system, 8H,
2
ArCH2Ar, J=13.4 Hz), 4.12 and 2.82 (AB spin system, 8H,
2
3
ArCH2Ar, J=13.4 Hz), 2.47 (t, 4H, C6H4CH2, J=7.3 Hz),
1.59–1.49 (4H, C6H4CH2CH2), 1.31–1.15 (4H, CH2CH3),
0.86 (t, 6H, CH2CH3, J=6.4 Hz); 13C{1H} NMR (75 MHz,
3
C6D6): d=159.04 (d, Cquat.-O, 4JP,C =2.4 Hz), 155.22 and
155.10 (2s, Cquat.-O), 145.88–122.14 (arom. C), 77.34 (s,
OCH2Ph), 77.07 (s, OCH2Ph), 76.00 (s, OCH2Ph), 35.09 (s,
C6H4CH2), 33.80 (s, C6H4CH2CH2), 31.46 (s, ArCH2Ar),
31.25 (s, ArCH2Ar), 22.52 (s, CH2CH3), 13.92 (s, CH2CH3);
31P{1H} NMR (121 MHz, C6D6): d=29.9 (s, PPh2); anal.
calcd. for C156H140PdCl2N2O8P2 (Mr=2410.06): C 77.74, H
5.85, N 1.16%; found: C 77.84, H 5.98, N 1.04%.
N-Chlorido-{5-(4-
butylphenyliminodiphenylphosphoranyl)-25,26,27,28-
tetrabenzyl-oxycalix[4]arene}gold(I) (13)
To a stirred solution of 9 (0.100 g, 0.09 mmol) in CH2Cl2
(15 mL) was added a solution of [AuClACHTNUTRGNEUNG(THT)] (0.029 g,
0.09 mmol) in THF (5 mL). After stirring for 5 h, the solu-
tion was concentrated to 1 mL. Addition of n-hexane afford-
ed 13 as a white solid; yield: 0.111 g (93%). 1H NMR
2-Methoxyphenyliminotriphenylphosphorane (16)
3
(300 MHz, C6D6): d=7.44 (d, 2H, arom. CH, J=11.7 Hz),
7.41 (dd, 2H, arom. CH, J=11.7 Hz, J=1.2 Hz), 7.29–7.24
3
4
To a solution of triphenylphosphine (0.262 g, 1.00 mmol) in
toluene (10 mL) was added a solution of 2-methoxyphenyl
azide (0.149 g, 1.00 mmol in toluene (10 mL). After stirring
the solution for 16 h at 608C, the reaction mixture was
evaporated to dryness under vacuum to afford quantitatively
16; yield: 0.382 g (100%). 1H NMR (300 MHz, C6D6): d=
7.84–7.77 (6H, arom. CH), 7.46 (d, 1H, arom. CH ortho to
N, 3J=7.8 Hz), 7.40–7.35 (1H, arom. CH para to CH3O),
7.04–6.96 (9H, arom. CH), 6.80 (dd, 1H, arom. CH para to
(8H, arom. CH), 7.13–6.93 (22H, arom. CH), 6.75 (d, 4H,
3
3
arom. CH, J=7.8 Hz), 6.63 (t, 2H, arom. CH, J=7.3 Hz),
6.47 (dd, 2H, arom. CH, 3J=7.5 Hz, 4J=1.8 Hz), 6.36 (d,
2H, arom. CH, 3J=7.8 Hz), 6.04 (t, 1H, arom. CH, 3J=
7.5 Hz), 5.14 and 5.07 (AB spin system, 4H CH2Ph, 2J=
12.0 Hz), 4.77 (s, 2H, CH2Ph), 4.70 (s, 2H, CH2Ph), 4.26 and
2
2.87 (AB spin system, 4H, ArCH2Ar, J=13.3 Hz), 4.03 and
2
2.60 (AB spin system, 4H, ArCH2Ar, J=13.6 Hz), 2.36 (t,
3
3
2H, C6H4CH2, 3J=7.6 Hz), 1.49–1.42 (2H, C6H4CH2CH2),
N, J=7.8 Hz, J=7.8 Hz), 6.67 (d, 1H, arom. CH ortho to
CH3O, 3J=7.8 Hz), 3.08 (s, 3H, CH3O); 13C{1H} NMR
(75 MHz, C6D6): d=159.01 (s, arom. Cquat.-O), 134.44 (d,
3
1.30–1.20 (2H, CH2CH3), 0.84 (t, 3H, CH2CH3, J=7.1 Hz);
13C{1H} NMR (75 MHz, C6D6): d=159.91 (d, Cquat.-O, JP, C
=
4
1
2.5 Hz), 155.88, 155.77 (2 s, Cquat.-O), 146.05–119.10 (arom.
arom. Cquat.-P, JC,P =71.9 Hz), 132.38 (d, arom. CH ortho to
Adv. Synth. Catal. 2013, 355, 1351 – 1360
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1359

Laure Monnereau et al.
FULL PAPERS
2
P, JC,P =9.4 Hz), 130.49 (s, arom. CH para to P), 128.50 (d,
[5] E. W. Abel, S. A. Mucklejohn, Phosphorus and Sulfur
1981, 9, 235–266.
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3
arom. CH ortho to N, JC,P =7.4 Hz), 127.94 (d, arom. CH
meta to P, JC,P =11.5 Hz), 125.34 (d, arom. Cquat.-N, JC,P
3
2
=
19.8 Hz), 121.64 (s, arom. CH para to N), 117.77 (s, arom.
CH ortho to CH3O), 54.03 (s, CH3O); 31P{1H} NMR
(121 MHz, C6D6): d=ꢀ0.3 (s, PPh2). IR: n=1328 cmꢀ1 (P=
N); anal. calcd. for C25H22OPN (Mr=383.42): C 78.31, H
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Typical Procedure for Palladium-Catalysed Suzuki–
Miyaura Cross-Coupling Reactions
A 10-mL Schlenk tube was charged with a solution of [Pd-
ACHTUNGTRENNUNG(OAc)2] in dioxane, a solution of the ligand in dioxane, aryl
halide (0.5 mmol), phenylboronic acid (0.122 g, 1.0 mmol),
base (1.0 mmol), and decane (0.05 mL, internal reference).
Dioxane was then added so that the total reaction volume
was 1.5 mL. The reaction mixture was heated for 1 h at
1008C. After cooling to room temperature, a small amount
(0.5 mL) of the resulting solution was passed through a Milli-
pore filter and analysed by GC. Some homocoupling prod-
ꢀ
ꢀ
ꢀ
uct (Ph Ph) was detected in each run, but the Ph Ph:Ar
Ph ratio never exceeded 10% (see the Supporting Informa-
tion).
Typical Procedure for Nickel-Catalysed Kumada–
Tamao–Corriu Cross-Coupling Reactions
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A 10-mL Schlenk tube was charged with a solution of [Ni-
ACHTUNGTRENNUNG(cod)2] in dioxane, a solution of the ligand in dioxane, aryl
2011, 47, 6626–6628.
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que 2012, 8–12.
[20] H. Staudinger, J. Meyer, Helv. Chim. Acta 1919, 2, 635–
646.
halide (0.5 mmol), PhMgBr (1 mL, 1.0 mmol, 1M solution in
THF), and decane (0.05 mL, internal reference). Dioxane
was then added so that the total reaction volume was
1.5 mL. The reaction mixture was heated for 1 h at 1008C.
After cooling to room temperature,
a
small amount
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Chem. Int. Ed. 2004, 43, 2201–2203.
(0.5 mL) of the resulting solution was passed through a Milli-
pore filter and analysed by GC. Some homocoupling prod-
ꢀ
ꢀ
ꢀ
uct (Ph Ph) was detected in each run, but the Ph Ph:Ar
Ph ratio never exceeded 15% (see the Supporting Informa-
tion).
[24] T. E. Barder, S. D. Walker, J. R. Martinelli, S. L. Buch-
wald, J. Am. Chem. Soc. 2005, 127, 4685–4696.
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Acknowledgements
The University of Strasbourg is gratefully acknowledged for
a grant to L.M.
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Adv. Synth. Catal. 2013, 355, 1351 – 1360