Arylcalixarenyl Phosphines in Palladium-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions

Article abstract of DOI:10.1002/ejoc.201600055

Two electron-rich arylcalixarenylphosphines have been synthesized in three steps from the appropriate 5-bromocalix[4]arene precursor 1. The combination of 5-(2-diisopropylphosphinophenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (5) and 5-(2-dicyclohexylphosphinophenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (6), respectively, with [Pd₂(dba)₃] (dba = dibenzylideneacetone) generated effective catalysts for the cross-coupling reactions of hindered aryl chlorides and arylboronic acids. Dicyclohexylphosphino-substituted ligand 6 had a higher activity that that of 5, and the structures of ligand 5 and [AuCl·5] were determined by single-crystal X-ray diffraction studies. The solid-state structure of [AuCl·5] revealed that the gold atom lies above the outer face of the calixarene unit, with distances of 3.08 and 3.28 ? between the gold atom and the two closest aromatic carbon atoms of the calixarene moiety.

Full text of DOI:10.1002/ejoc.201600055

DOI: 10.1002/ejoc.201600055
Full Paper
Phosphine Ligands
Arylcalixarenyl Phosphines in Palladium-Catalyzed Suzuki–
Miyaura Cross-Coupling Reactions
Fethi Elaieb,[
a,b,c]
Ahmed Hedhli,* David Sémeril,* and Dominique Matt*
[b]
[a]
[a]
Abstract: Two electron-rich arylcalixarenylphosphines have acids. Dicyclohexylphosphino-substituted ligand 6 had a higher
been synthesized in three steps from the appropriate 5-bromo- activity that that of 5, and the structures of ligand 5 and
calix[4]arene precursor 1. The combination of 5-(2-diisopropyl- [AuCl·5] were determined by single-crystal X-ray diffraction
phosphinophenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (5) studies. The solid-state structure of [AuCl·5] revealed that the
and 5-(2-dicyclohexylphosphinophenyl)-25,26,27,28-tetraprop- gold atom lies above the outer face of the calixarene unit, with
yloxycalix[4]arene (6), respectively, with [Pd (dba) ] (dba = di- distances of 3.08 and 3.28 Å between the gold atom and the
2
3
benzylideneacetone) generated effective catalysts for the cross- two closest aromatic carbon atoms of the calixarene moiety.
coupling reactions of hindered aryl chlorides and arylboronic
Introduction
As an extension of our studies on cavity-shaped phos-
phines, we now describe the synthesis of a new class of bi-
arylphosphines, namely, 5-(2-diorganylphosphinophenyl)calix-
[
9]
Electron-rich dialkylbiarylphosphines, in particular Buchwald-
[
4]arenes, which are hereafter referred to as arylcalixarenylphos-
type phosphines (which contain an o-substituted remote aryl
[
1]
phines (Figure 1), and report their use in Pd-catalyzed coupling
reactions of bulky aryl chlorides and sterically hindered aryl
boronic acids. In contrast to classical Buchwald-type biarylphos-
phines, the ligands described herein contain a biaryl unit that
has one arene ring with two unsymmetrical faces because it is
ring), are known to improve the reactivity of many palladium-
catalyzed coupling reactions, including Suzuki–Miyaura cou-
[
2]
[3]
[4]
pling (SMC), aryl amination and amidation, enolate aryl-
[
5]
[6]
ation, and Sonogashira coupling reactions. Ligands of this
family have been extensively applied to the syntheses of liquid
crystalline materials, pharmaceuticals, biologically active com-
pounds, natural products, and polymers, and the efficiency of
the catalysts that contain these ligands is directly correlated
[
10]
part of the calixarene skeleton.
[
1c]
with their structure.
It is now well-recognized that the re-
markable performance of such ligands in a SMC reaction arises
from their ability to behave as hemilabile P,C-chelators, involv-
ing the ipso carbon atom of the remote aryl ring, which favors
the formation of monoligand palladium intermediates over that
[
7]
of bis(ligand) complexes. This property, together with the
presence of a strong phosphorus donor, positively affects the
[
8]
rate of the oxidative addition step. If such phosphines
strongly sterically hinder the catalytic center, then the reductive
elimination step may also be facilitated.
Figure 1. The two arylcalixarenylphosphines synthesized and examined in the
present study.
[
a] Université de Strasbourg, Laboratoire de Chimie Inorganique Moléculaire
Results and Discussion
et Catalyse, UMR 7177 CNRS-UDS,
1
rue Blaise Pascal, 67008 Strasbourg cedex, France
Phosphines 5 and 6 were prepared in three steps from bromo-
E-mail: dsemeril@unistra.fr
[11]
calixarene 1
according to Scheme 1. Calixarene 1 was first
dmatt@unistra.fr
converted into a boronic acid derivative, which was subse-
quently transformed in situ to give arylated calixarene 2 by
employing a Suzuki–Miyaura coupling with 1,2-dibromobenz-
ene. Compound 2 was obtained in 56 % isolated yield. The di-
alkylphosphino moieties were then introduced by a halogen/
lithium exchange reaction followed by treatment with the ap-
propriate chlorophosphine at 65 °C. As the resulting phosphines
can be readily oxidized to give the corresponding phosphine
http://lcimc.u-strasbg.fr
b] Ecole Nationale Supérieure d'Ingénieurs de Tunis, Laboratoire de Chimie
Moléculaire Organique,
[
[
5
avenue Taha Hussein, Montfleury, 1008 Tunis, Tunisia
E-mail: ahmed.hedhli@esstt.rnu.tn
c] Faculté des Sciences de Bizerte, Université de Carthage,
7
021 Jarzouna, Tunisia
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under http://dx.doi.org/10.1002/ejoc.201600055.
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oxides, the crude reaction mixtures were first treated with BH3 skewed away from being directed into the calixarene cavity.
to produce the borane adducts, which were conveniently puri- The calixarene unit in this conformation has greater steric influ-
fied by chromatography [70 % yield (for 3) and 65 % yield (for ence on reactions that take place at the phosphorus atom com-
4
)]. The free phosphines were then quantitatively formed upon pared with that in which the phosphorus atom is turned to-
heating the purified borane adducts in a MeOH/toluene (1:4) wards the exterior of the cavity. A SPARTAN calculation revealed
mixture at reflux for 5 h.
that the cone angle increases by approximately 10° upon
changing from the conformation with the exo-oriented lone
pair to that in which the lone pair of the phosphorus atom is
directed towards the interior of the cavity (Tolman cone angle
[
13]
of the latter conformer: Θ = 150 °C).
Clearly, given the free
rotation of the biaryl axis, ligand 5 should be regarded as a
ligand with variable bulk.
To gain some insight into the coordination behavior of these
biarylphosphines, phosphine 5 was treated with 1 equiv. of
[
AuCl(THT)] (THT: tetrahydrothiophene), which quantitatively
1
led to complex 7 (Scheme 2). As for 5, the H NMR spectrum
of 7 was in accord with a calixarene moiety in a cone conforma-
tion (see Exp. Section). An X-ray study (Figure 3) revealed that
in the solid state, the gold and phosphorus atoms lie outside
Scheme 1. Stepwise preparation of phosphines 5 and 6 (THF = tetrahydro-
furan, Cy = cyclohexyl).
Scheme 2. Synthesis of complex 7.
Each phosphine was characterized by a singlet found in the
3
1
corresponding P NMR spectrum [δ = –4.0 ppm (for 5) and
1
–
6
13.5 ppm (for 6)]. As expected, the H NMR spectra of 5 and
are in agreement with those of C -symmetrical molecules, as
s
both have two distinct AB patterns for the diastereotopic
ArCH Ar protons. The large AB separations (Δδ > 1 ppm) unam-
2
biguously show that the calixarene core has maintained its con-
[
12]
ical shape in the tranformation of 1 into 5 or 6. The structure
of 5 was confirmed by a single-crystal X-ray diffraction study
(
Figure 2). Interestingly, in the solid state, the phosphorus atom
is oriented in such as way that its lone pair is only slightly
Figure 3. Molecular structure of 7. Interplanar angles between opposite phen-
olic rings: 13.2° and 72.5°. Dihedral angle between the two rings of the biaryl
subunit: 73.3°. Selected bond lengths [Å] and angle [°]: P–Au 2.239(1), Au–Cl
2.291(1); PAuCl 179.69(2).
Figure 2. Molecular structure of 5. Interplanar angles between opposite phen-
olic rings: 25.8° and 76.4°. Dihedral angle between the two rings of the biaryl
subunit: 49.1°.
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the cone, which is defined by the calixarene core. The gold ion catalysts were generated in situ by combining different palla-
is exactly above a C–C bond of the remote biaryl unit with dium precursor complexes with 1.5 equiv. of phosphine.
Au···C distances of 3.083 Å (Au···C-24) and 3.285 Å (Au···C-25;
C-24 is the ipso carbon atom of the remote aryl ring). These
values are close to those found in Echavarren's biarylphosphine
2
gold complex 8 (3.02 and 3.25 Å) and typically reflect weak η -
[
14]
Au···arene interactions (Figure 4). At this stage, we are unable
Scheme 4. Suzuki–Miyaura cross-coupling reactions of aryl chlorides with aryl
boronic acids (L = phosphine ligand).
2
to state whether a conformer of 7 with the gold atom η -
bonded to the interior of the cavity exists in solution. However,
we anticipate that filling the cavity with a chlorogold moiety
would certainly result in strong repulsions between the chlorine
atom and the cavity walls.
To determine the optimal catalytic conditions, [Pd(OAc) ] and
2
ligand 5 were used in the cross-coupling reaction of 4-chloro-
anisole and phenylboronic acid at 100 °C in 1,4-dioxane. Each
experiment was stopped after 1 h. In the first series of reactions,
we determined the optimal base by employing either NaH,
KOH, Cs CO , or tBuOK. As can be inferred from the results
2
3
(
Table 1 Entries 1–4), the most efficient base was tBuOK, which
led to a conversion of 62.6 %. When [Pd (dba) ] (dba = dibenz-
2
3
ylideneacetone) was used as the palladium precursor instead of
[
(
Pd(OAc) ], the conversion increased from 62.6 to 71.1 %
Table 1, Entry 5).
2
Figure 4. Echevarren's gold complex 8. Important distances: 3.02 Å (Au···C-1)
and 3.25 Å (Au···C-2).
Table 1. Suzuki–Miyaura cross-coupling reaction of 4-chloroanisole with
phenylboronic acid – a search for optimal catalytic conditions.[ The conver-
sions were determined by GC analysis with the calibrations based on decane.
Ligand 5 also readily forms complexes with palladium(II). For
a]
example, the reaction of [PdCl (PhCN) ] with 2 equiv. of 5 in
2
2
CH Cl quantitatively gave the complex trans-[PdCl (5) ] (9;
2
2
2
2
Entry
[Pd]
Phosphine
Base
Conversion (%)
Scheme 3). The trans-selectivity of this reaction is a reflection
of the high steric encumbrance of phosphine 5. The trans con-
figuration of the palladium complex was unambiguously in-
1
2
3
4
5
6
7
[Pd(OAc)
[Pd(OAc)
[Pd(OAc)
[Pd(OAc)
2
2
2
2
]
]
]
]
5
5
5
5
5
6
6
NaH
KOH
Cs CO
2 3
tBuOK
tBuOK
tBuOK
tBuOK
32.8
33.0
11.7
62.6
71.1
84.8
91.5
1
3
ferred from the C NMR spectrum, which shows a virtual triplet
1
3
[15]
for the PCHMe carbon atoms (| J + JP, C| = 20.5 Hz).
[Pd (dba) ]
2
P, C
2
3
[Pd(OAc)
2
]
[Pd
2
(dba)
3
]
[
a] Reagents and conditions: [Pd] (1.0 mol-%), phosphine (1.5 mol-%), 4-Me-
OC Cl (0.25 mmol), PhB(OH) (0.37 mmol), base (0.37 mmol), decane
0.025 mL), dioxane (0.75 mL), 100 °C, 1 h.
6
H
4
2
(
Under the determined optimal conditions {i.e., with
[
Pd (dba) ] and tBuOK}, the conversion reached 91.5 % by using
2
3
phosphine 6, the activity of which was approximately 30 %
higher than that of 5 (Table 1, Entry 7). Reducing the palladium
loading to 0.05 mol-% and carrying out the reaction for 22 h at
1
00 °C gave a conversion of 89.6 %. This corresponds to a turn-
over number (TON) of 1790 mol(ArCl)/mol(Pd), which was found
to be 30 % higher than that obtained with the Buchwald ligand
[
16]
(
o-biphenyl)PCy {TON = 1440 mol(ArCl)/mol(Pd)}. The differ-
2
ence in reactivity between the latter and 6 may be a reflection
of the greater, time-averaged steric encumbrance of the calix-
arenylphosphine (see above).
The catalytic system [Pd (dba) ]/6 was further examined in
2
3
the cross-coupling reactions of phenyl boronic acid with four
sterically hindered aryl chlorides, namely, 2-chlorotoluene, 2-
chloroanisole, chloro-2,6-dimethylbenzene, and 9-chloroanthra-
cene. 2-Chlorotoluene and 2-chloroanisole were converted into
the corresponding biaryls in high yields within 2 h (94.5 and
Scheme 3. Synthesis of palladium complex 9.
8
8.4 % conversion; Table 2, Entries 1 and 2). As expected, essen-
tially complete conversion with the bulkier 2,6-dimethylchloro-
benzene and 9-chloroanthracene required longer reaction
times (Table 2, Entries 3 and 4). A similar trend was observed
Catalytic Suzuki–Miyaura Cross-Coupling with 5 and 6
The two phosphines were then employed in palladium-cata- when the latter substrates were treated with the three encum-
lyzed Suzuki–Miyaura cross-coupling reactions (Scheme 4). The bered reagents (2-methylphenyl)boronic acid, (2-methoxy-
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Table 2. Suzuki–Miyaura cross-coupling of aryl chlorides catalyzed by using
phenyl)boronic acid, and naphthalene-1-boronic acid. These re-
[
a]
[
2 3
Pd (dba) ]/6. The conversions were determined by GC analysis with the
actions with the combination of [Pd (dba) ] and phosphine 6
2
3
calibrations based on decane.
resulted in ortho-trisubstituted biphenyls in moderate to good
yields. For example, the reactions of chloroanthracene and each
of the three boronic acids gave the corresponding ortho-trisub-
stituted biphenyls in 80.5, 95.1, and 97.3 % yield, respectively,
after 16, 16, and 8 h (Table 2, Entries 8, 12, and 16).
Overall, arylcalixarenylphosphine 6 in combination with pal-
ladium acts as an efficient cross-coupling catalyst towards aryl
chlorides, especially for the synthesis of encumbered biaryls.
However, the activity of the Pd/6 system remains approximately
5
00 times lower than that of the Buchwald ligands, which incor-
porate additional methoxy groups at the ortho-carbon atoms
[
1c]
of the remote aryl group. These ligands assist the oxidative
addition step by forming intermediate electron-enriched P,O-
chelate complexes, but they also possibly sterically favor the
[
17]
reductive elimination step.
Conclusions
Herein, we have described the synthesis of the first conical
calix[4]arenes, in which the upper rim is substituted by an o-
phosphinated phenyl group and, therefore, belong to the class
of ligands commonly designated as biarylphosphines. The
structure of 5 was established by an X-ray diffraction study,
which revealed that in the solid form, the phosphorus atom is
placed on the inner side of the cavity delineated by the calix-
arene core. In contrast, in complex [AuCl·5], the P–Au–Cl rod is
turned outwards from the cavity with a neighboring phenoxy
ring weakly π-interacting with the gold ion. Arylcalixarenyl-
phosphine 6 was more active as a catalyst ligand in the SMC
reaction than Buchwald ligand (o-biphenyl)PCy . This result was
2
a direct consequence of its greater bulkiness, which is imposed
by the presence of the calixarene cavity. Ligand 6 was also em-
ployed in the effective cross-coupling reaction of a variety of o-
substituted aryl chlorides with encumbered boronic acids. Its
activity, however, remained lower than that of those Buchwald
phosphines equipped with methoxy groups attached at the o-
carbon atoms of the remote aryl ring, which may anchimerically
assist in the reaction. With regard to this, it would be of interest
to extend our studies to related arylcalixarenylphosphines that
have both rims substituted with weak donors.
Experimental Section
General Methods: All manipulations that involve phosphorus de-
rivatives were performed in Schlenk-type flasks under argon. Sol-
vents were dried by conventional methods and distilled immedi-
ately prior to use. CDCl was passed through a 5 cm thick alumina
3
column and stored under nitrogen over molecular sieves (4 Å). The
routine 1H, C{ H} and P{ H} NMR spectroscopic data were re-
13
1
31
1
corded with Bruker FT spectrometers (AVANCE 400 and 500). The
1
chemical shifts in the H NMR spectra are referenced to the residual
protiated solvent (δ = 7.26 ppm for CHCl and 7.11 ppm for C D H).
3
6 5
The chemical shifts of the 13C NMR spectra are reported relative to
the deuteriated solvents (δ = 77.16 ppm for CDCl and 128.06 ppm
[
a] Reagents and conditions: [Pd
2
(dba)
3
] (0.5 mol-%), 6 (1.5 mol-%), ArCl
3
for C
are given relative to external H PO . Chemical shifts and coupling
D
). The chemical shifts of the 31P NMR spectroscopic data
(
0.25 mmol), ArB(OH) (0.37 mmol), tBuOK (0.37 mmol), decane (0.025 mL),
2
6 6
dioxane (0.75 mL), 100 °C.
3
4
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constants are reported in ppm and Hz, respectively. Cq denotes a
quaternary carbon atom. Elemental analyses were performed by
the Service de Microanalyse, Institut de Chimie, CNRS-Université de
H, arom. CH, C H ), 7.16–7.09 (m, 2 H, arom. CH, C H ), 6.96–6.93
6
4
6 4
(m, 1 H, arom. CH, C H ), 6.83–6.75 (m, 5 H, arom. CH, calixarene),
6
4
6.61–6.54 (m, 6 H, arom. CH, C H ), 4.58 and 3.13 (AB spin system,
6
4
[
11]
2
2
Strasbourg. 5-Bromo-25,26,27,28-tetrapropyloxycalix[4]arene (1),
J = 13.6 Hz, 4 H, ArCH Ar), 4.55 and 3.13 (AB spin system, J =
2
AuCl(THT)],[ and [PdCl (PhCN) ]
18]
[19]
were prepared according to
13.6 Hz, 4 H, ArCH Ar), 3.98 (t, J = 7.0 Hz, 2 H, OCH ), 3.90 (t, J =
2 2
3
3
[
2
2
3
literature procedures.
7.0 Hz, 2 H, OCH ), 3.81 (t, J = 6.8 Hz, 4 H, OCH ), 2.21–2.06 [m, 2
2
2
3
H, CH(CH ) ], 1.95–1.84 (m, 8 H, CH CH ), 1.23 [dd, J = 14.8 Hz,
J = 6.8 Hz, 6 H, CH(CH ) ], 0.99 [dd, J = 14.8 Hz, J = 6.8 Hz, 6
H, CH(CH ) ], 0.95 (t, J = 7.2 Hz, 9 H, CH CH ), 0.93 (t, J = 7.2 Hz,
H, CH CH ), 0.88–0.80 (m, 3 H, BH ) ppm. C{ H} NMR (125 MHz,
3
2
2
3
P, H
5
-(2-Bromophenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (2):
nBuLi (1.6 in hexane, 0.53 mL, 0.86 mmol) was slowly added to a
solution of 5-bromo-25,26,27,28-tetrapropyloxycalix[4]arene (1,
.460 g, 0.78 mmol) in THF (15 mL) at –78 °C. After 0.5 h, the result-
ing carbanion was quenched by the addition of B(OMe) (1.67 mL,
3
3
3
3
2
P, H
M
3
3
3
2
2
3
3
1
1
3
2
3
3
0
C D , 341 K): δ = 157.46 (s, arom. Cq-O), 157.24 (s, arom. Cq-O),
6
6
3
1
56.81 (s, arom. Cq-O), 146.90–122.63 (arom. carbons), 77.20 (s,
1
1
.56 mmol), and the mixture was stirred at room temperature for
2 h. The reaction mixture was hydrolyzed with a solution of HCl
OCH ), 77.12 (s, OCH ), 31.78 (s, ArCH Ar), 31.67 (s, ArCH Ar), 24.67
2
2
2
2
1
[
d, J = 32.3 Hz, CH(CH ) ], 23.73 (CH CH ), 23.67 (CH CH ), 23.57
P, C 3 2 2 3 2 3
(
1 M, 50 mL). The product was then extracted into CH Cl2 (3 ×
2
(
CH CH ), 19.30 [s, CH(CH ) ], 18.77 [s, CH(CH ) ], 10.61 (CH CH ),
0.56 (CH CH ), 10.49 (CH CH ) ppm. P{ H} NMR (162 MHz, C D ,
2 3 2 3 6 6
2 3 3 2 3 2 2 3
2
0 mL). The combined organic layers were dried with Na SO and
2 4
31
1
1
3
7
reduced under vacuum. The crude 5-boronic-25,26,27,28-tetra-
propyloxycalix[4]arene acid was used without any further purifica-
tion in the next step. A 100 mL Schlenk tube was filled with the
crude boronic acid, 1,2-dibromobenzene (2.77 mL, 11.78 mmol),
41 K): δ = 45.8 [s, P(BH )iPr ] ppm. C H BO P (798.88): calcd. C
3
2
52 68
4
8.18, H 8.58; found C 78.22, H 8.68.
[5-(2-Dicyclohexylphosphinophenyl)-25,26,27,28-tetrapropyl-
[
Pd(PPh ) ] (0.050 g, 0.40 mmol), and Cs CO (0.300 g, 0.94 mmol). oxycalix[4]arene]borane (4): Purification by column chromatogra-
3 4 2 3
[
1,2-Dibromobenzene was used in an excess amount to avoid for-
phy (CH Cl /pentane, 20:80 v/v) afforded compound 4 (65 % yield).
2
2
1
mation of the corresponding 1,2-dicalixarenylbenzene]. N,N-dimeth-
ylformamide (DMF, 50 mL) was then added, and the resulting mix- 7.37–7.30 (m, 2 H, arom. CH, C H ), 6.89 (d, J = 6.0 Hz, 2 H, arom.
ture was heated at 110 °C for 24 h. The solvent was evaporated
under vacuum, and the residue was dissolved in CH Cl (50 mL).
The resulting solution was washed with water (4 × 25 mL), and the
organic layer was dried with Na SO and reduced under vacuum.
The crude product was purified by column chromatography (petro- spin system, J = 13.2 Hz, 4 H, ArCH Ar), 4.08–3.98 (m, 4 H, OCH ),
leum ether) to afford 2 (0.280 g, 56 % yield) as a white solid.
NMR (400 MHz, CDCl ): δ = 7.61 (dd, J = 7.8 Hz, J = 1.2 Hz, 1 H,
arom. CH, C H ), 7.28 (td, J = 7.5 Hz, J = 1.2 Hz, 1 H, arom. CH, 1.28–1.08 (m, 16 H, CH CH3 and Cy), 1.01 (t, J = 7.0 Hz, 6 H,
H NMR (400 MHz, CDCl ): δ = 8.02–7.97 (m, 1 H, arom. CH, C H ),
3
6
4
3
6
4
3
CH, calixarene), 6.81 (d, J = 6.0 Hz, 2 H, arom. CH, calixarene), 6.74–
6.68 (m, 3 H, arom. CH, calixarene), 6.59–6.53 (m, 3 H, arom. CH,
calixarene and C H ), 6.31 (s, 2 H, arom. CH, calixarene), 4.61 and
2
2
6
4
2
3.19 (AB spin system, J = 13.2 Hz, 4 H, ArCH Ar), 4.53 and 3.19 (AB
2
4
2
2
2
2
1
3
3
H
3.89 (t, J = 6.0 Hz, 2 H, OCH ), 3.82 (t, J = 6.6 Hz, 2 H, OCH ), 2.08–
2
2
3
4
1.92 (m, 8 H, CH CH ), 1.78–1.65 (m, 8 H, Cy), 1.58–1.42 (m, 4 H, Cy),
2 3
3
3
4
3
6
4
2
3
4
13
1
C H ), 7.12 (td, J = 7.6 Hz, J = 1.8 Hz, 1 H, arom. CH, C H ), 7.03 CH CH ), 0.80–0.35 (m, 3 H, BH ) ppm. C{ H} NMR (125 MHz,
6
4
6
4
2
3
3
dd, J = 7.5 Hz, 4J = 1.8 Hz, 1 H, arom. CH, C H ), 6.78 (m, 4 H,
3
CDCl ): δ = 157.13 (s, arom. Cq-O), 156.15 (s, arom. Cq-O), 146.38–
(
6
4
3
arom. CH, calixarene), 6.74 (s, 2 H, arom. CH, calixarene), 6.68–6.65
122.07 (arom. carbons), 77.63 (s, OCH ), 77.13 (s, OCH ), 76.79 (s,
2
2
3
3
1
(
m, 4 H, arom. CH, calixarene), 6.57 (dd, J = 7.5 Hz, J = 7.5 Hz, 1
OCH ), 34.06 [d, J = 34.1 Hz, CH(CH ) ], 31.28 (s, ArCH Ar), 31.16
2 P, C 2 5 2
2
2
H, arom. CH, calixarene), 4.56 and 3.24 (AB spin system, J = 13.5 Hz,
4
ArCH Ar), 3.97 (t, J = 7.5 Hz, 4 H, OCH ), 3.94 (t, J = 7.5 Hz, 2 H,
OCH ), 3.90 (t, J = 7.5 Hz, 2 H, OCH ), 2.09–1.96 (m, 8 H, CH CH ),
1
1
(s, ArCH Ar), 28.72 [s, CH(CH ) ], 27.94 [s, CH(CH ) ], 27.23 [d, J
=
2
2 5
2 5
P, C
2
2
H, ArCH Ar), 4.54 and 3.22 (AB spin system, J = 13.2 Hz, 4 H,
13.3 Hz, CH(CH ) ], 26.92 [d, JP, C = 11.6 Hz, CH(CH ) ], 25.87 [s,
2
2 5 2 5
3
3
CH(CH ) ], 23.52 (CH CH ), 23.26 (CH CH ), 10.70 (CH CH ), 10.22
2 5 2 3 2 3 2 3
2
2
3
31
1
(CH CH ) ppm. P{ H} NMR (162 MHz, CDCl ): δ = 35.4 [s,
2
2
2
3
2
3
3
3
3
.10 (t, J = 7.2 Hz, 3 H, CH CH ), 1.07 (t, J = 7.5 Hz, 3 H, CH CH ), P(BH )Cy ] ppm. C H BO P (879.01): calcd. C 79.25, H 8.71; found
2 3 2 3 3 2 58 76 4
.06 (t, 3J = 7.5 Hz, 6 H, CH CH ) ppm. C{ H} NMR (125 MHz,
13
1
C 79.36, H 8.85.
General Procedure for the Synthesis of 5-(2-Phosphinophenyl)-
2
3
CDCl ): δ = 156.72 (s, arom. Cq-O), 156.51 (s, arom. Cq-O), 156.15 (s,
3
arom. Cq-O), 142.81–121.99 (arom. carbons), 76.97 (s, OCH ), 76.91
2
25,26,27,28-tetrapropyloxycalix[4]arenes 5 and 6: A solution of
(
(
(
s, OCH ), 76.81 (s, OCH ), 31.12 (s, ArCH Ar), 23.50 (CH CH ), 23.44
2 2 2 2 3
the appropriate [5-(2-phosphinophenyl)-25,26,27,28-tetrapropyloxy-
calix[4]arene]borane (0.60 mmol) in MeOH/toluene (1:4, 15 mL) was
heated at reflux for 5 h. After cooling to room temperature, the
reaction mixture was evaporated to dryness, and the residue was
dried overnight at 40 °C under vacuum to afford the corresponding
phosphine quantitatively.
CH CH ), 23.35 (CH CH ), 10.55 (CH CH ), 10.42 (CH CH ) ppm. MS
2
3
2
3
2
3
2
3
+
ESI): m/z = 769.28 [M + Na] (expected isotopic profiles).
C H BrO (747.80): calcd. C 73.88, H 6.87; found C 73.91, H 6.90.
46
51
4
General Procedure for the Synthesis of [5-(2-Phosphinophenyl)-
5,26,27,28-tetrapropyloxycalix[4]arene]boranes 3 and 4: n-
Butyllithium (1.6 in hexane, 0.68 mL, 1.08 mmol) was slowly
2
M
5
-(2-Diisopropylphosphinophenyl)-25,26,27,28-tetrapropyloxy-
added to a solution of 5-(2-bromophenyl)-25,26,27,28-tetrapropyl-
oxycalix[4]arene (0.600 g, 0.87 mmol) in THF (50 mL) at –78 °C. After
1
3
calix[4]arene (5): H NMR (500 MHz, C D ): δ = 7.45 (d, J = 7.5 Hz,
6
6
1
H, arom. CH, C H ), 7.35–7.33 (m, 1 H, arom. CH, C H ), 7.22–7.17
6 4 6 4
0
.5 h, the resulting carbanion was quenched with ClPR2
1.30 mmol), and the mixture was stirred at 65 °C for 16 h. The
reaction was cooled to 0 °C, and BH ·THF (1 in THF, 2 mL, 2 mmol)
(
m, 4 H, arom. CH, C H , calixarene), 6.96–6.87 (m, 5 H, arom. CH,
6 4
(
3
calixarene), 6.65 (t, J = 7.5 Hz, 2 H, arom. CH, calixarene), 6.60 (d,
M
3
3
J = 7.0 Hz, 2 H, arom. CH, C H ), 4.61 and 3.27 (AB spin system,
6
4
was added. After stirring for 5 h at room temperature, the solvents
were evaporated under reduced pressure, and the crude product
was purified by column chromatography (see below).
2
2
J = 13.0 Hz, 4 H, ArCH Ar), 4.58 and 3.18 (AB spin system, J =
2
3
3
1
7
3.5 Hz, 4 H, ArCH Ar), 3.99 (t, J = 7.7 Hz, 4 H, OCH ), 3.73 (t, J =
2
2
.2 Hz, 4 H, OCH ), 2.04–1.92 [m, 6 H, CH CH and CH(CH ) ], 1.88–
2
2
3
3 2
3
3
[
5-(2-Diisopropylphosphinophenyl)-25,26,27,28-tetrapropyl-
1.80 (m, 4 H, CH CH ), 1.07 [dd, J = 14.0 Hz, J = 6.5 Hz, 6 H,
2
3
3
P, H
3
oxycalix[4]arene]borane (3): Purification by column chromatogra- CH(CH ) ], 1.01 [dd, J = 11.5 Hz, J = 7.0 Hz, 6 H, CH(CH ) ], 0.94
3
2
P, H
3 2
3
3
phy (CH Cl /petroleum ether, 20:80 v/v) afforded compound 3
(t, J = 7.5 Hz, 6 H, CH CH ), 0.90 (t, J = 7.5 Hz, 6 H, CH CH ) ppm.
2
2
2 3 2 3
1
13
1
(
70 % yield). H NMR (400 MHz, C D , 341 K): δ = 8.46–8.40 (m, 1
C{ H} NMR (125 MHz, C D ): δ = 157.78 (s, arom. Cq-O), 156.69 (s,
6 6
6
6
Eur. J. Org. Chem. 2016, 1867–1873
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Full Paper
arom. Cq-O), 156.32 (s, arom. Cq-O), 151.00–122.55 (arom. carbons),
7.05 (s, OCH ), 76.86 (s, OCH ), 31.65 (s, ArCH Ar), 31.60 (s,
added to a stirred solution of 5 (0.050 g, 0.06 mmol) in CH Cl
(10 mL). After stirring for 0.5 h, the reaction mixture was concen-
trated to about 1 mL, and n-hexane (20 mL) was added. The yellow
2
2
7
2
2
2
1
ArCH Ar), 25.16 [d, J = 16.1 Hz, CH(CH ) ], 23.76 (CH CH ), 23.67
2
P, C
3 2
2
3
2
(
[
(
CH CH ), 23.55 (CH CH ), 20.58 [d, J = 19.9 Hz, CH(CH ) ], 20.40
precipitate was separated by filtration and dried under vacuum to
2
3
2
3
P, C
3 2
2
1
d, J = 12.6 Hz, CH(CH ) ], 10.76 (CH CH ), 10.36 (CH CH ), 10.35
give compound 9 (0.053 g, 97 % yield). H NMR (500 MHz, CDCl ):
P, C
3 2
2
3
2
3
3
31
1
CH CH ) ppm. P{ H} NMR (162 MHz, C D ): δ = –4.0 (s, PiPr ) ppm.
δ = 7.99–7.95 (m, 1 H, arom. CH, C H ), 7.31–7.24 (m, 2 H, arom.
2
3
6
6
2
6 4
C H O P (785.05): calcd. C 79.56, H 8.35; found C 79.38, H 8.30.
CH, C H ), 6.90–6.79 (m, 5 H, arom. CH, C H , calixarene), 6.72 (t,
52
65
4
6 4 6 4
3
J = 7.2 Hz, 1 H, arom. CH, calixarene), 6.49–6.44 (m, 6 H, arom. CH,
5
-(2-Dicyclohexylphosphinophenyl)-25,26,27,28-tetrapropyl-
2
calixarene), 4.46 and 3.16 (AB spin system, J = 13.5 Hz, 4 H,
1
oxycalix[4]arene (6): H NMR (400 MHz, C D ): δ = 7.77–7.74 (m,
6
6
2
ArCH Ar), 4.41 and 3.05 (AB spin system, J = 13.5 Hz, 4 H, ArCH Ar),
2
2
1
H, arom. CH, C H ), 7.58–7.53 (m, 1 H, arom. CH, C H ), 7.42–7.38
6 4 6 4
3
3
3
(
.90 (t, J = 7.0 Hz, 2 H, OCH ), 3.89 (t, J = 7.5 Hz, 2 H, OCH ), 3.81
2
2
(
m, 4 H, arom. CH, calixarene, C H ), 7.35 (s, 2 H, arom. CH, calixa-
6 4
3
t, J = 6.2 Hz, 4 H, OCH ), 2.45–2.40 [br. signal, 2 H, CH(CH ) ], 2.00–
2
3
2
rene), 7.13 (s, 2 H, arom. CH, calixarene), 7.09–7.04 (m, 1 H, arom.
3
3
1
.85 (m, 8 H, CH CH ), 1.26 [dd, J = 15.0 Hz, J = 7.5 Hz, 6 H,
CH(CH ) ], 1.10 [dd, J = 14.5 Hz, J = 7.5 Hz, 6 H CH(CH ) ], 1.01
3
2
3
3
P, H
3
HH
CH, calixarene), 6.86 (t, J = 7.5 Hz, 2 H, arom. CH, calixarene), 6.77
3
3 2
P, H
3 2
(
d, J = 7.2 Hz, 2 H, arom. CH, calixarene), 4.82 and 3.49 (AB spin
3
3
(
(
t, J = 7.5 Hz, 6 H, CH CH ), 0.99 (t, J = 7.5 Hz, 3 H, CH CH ), 0.98
2
2 3 2 3
system, J = 13.5 Hz, 4 H, ArCH Ar), 4.77 and 3.37 (AB spin system,
J = 13.2 Hz, 4 H, ArCH Ar), 4.23–4.16 (m, 4 H, OCH ), 3.91 (t, J =
2
3
13
1
t, J = 7.5 Hz, 3 H, CH CH ) ppm. C{ H} NMR (125 MHz, CDCl ):
2
3
2
3
3
2
2
δ = 157.08 (s, arom. Cq-O), 156.49 (s, arom. Cq-O), 156.20 (s, arom.
7
.2 Hz, 4 H, OCH ), 2.25–1.84 (m, 18 H, CH CH and Cy), 1.78–1.74
2 2 3
Cq-O), 146.86–121.97 (arom. carbons), 76.86 (s, OCH ), 76.82 (s,
3
2
(m, 2 H, Cy), 1.55–1.33 (m, 10 H, Cy), 1.14 (t, J = 7.5 Hz, 6 H, CH CH ),
2 3
1
OCH ), 31.11 (s, ArCH Ar), 31.03 (s, ArCH Ar), 24.07 [virtual t, | J
+
.10 (t, 3J = 7.5 Hz, 3 H, CH CH ), 1.09 (t, J = 7.5 Hz, 3 H,
3
2
2
2
P, C
1
2
3
3
JP, C| = 20.1 Hz, CH(CH ) ], 23.47 (CH CH ), 23.34 (CH CH ), 23.18
13
1
3 2
2
3
2
3
CH CH ) ppm. C{ H} NMR (125 MHz, C D ): δ = 157.85 (s, arom.
2
3
6 6
(
1
CH CH ), 21.15 [s, CH(CH ) ], 19.66 [s, CH(CH ) ], 10.67 (CH CH ),
2 3 3 2 3 2 2 3
Cq-O), 156.75 (s, arom. Cq-O), 156.31 (s, arom. Cq-O), 151.51–122.53
31
1
0.60 (CH CH ), 10.37 (CH CH ) ppm. P{ H} NMR (162 MHz, CDCl ):
1
2 3 2 3 3
(
1
arom. carbons), 77.05 (s, OCH ), 76.83 (s, OCH ), 35.75 [d, JP, C =
2 2
δ = 46.3 (s, PiPr ) ppm. C104H130Cl O P Pd (1747.42): calcd. C 71.48,
2
2
2 8 2
6.8 Hz, CH(CH ) ], 31.70 (s, ArCH Ar), 31.54 [d, J = 12.4 Hz,
2 5 2 P, C
CH(CH ) ], 31.21 (s, ArCH Ar), 30.35 [d, JP, C = 10.5 Hz, CH(CH2)5],
H 7.50; found C 71.55, H 7.61.
2
2
5
2
X-ray Crystal Structure Analysis of 5: Single crystals of 5 suitable
for X-ray analysis were obtained by slow diffusion of hexane into
2
7.53 [s, CH(CH ) ], 27.38 [s, CH(CH ) ], 26.91 [s, CH(CH ) ], 23.78
2 5 2 5 2 5
(
(
CH CH ), 23.70 (CH CH ), 23.55 (CH CH ), 10.79 (CH CH ), 10.37
2 3 2 3 2 3 2 3
3
1
1
a chloroform solution of phosphine 5. Crystal data: Mr =
CH CH ) ppm. P{ H} NMR (162 MHz, C D ): δ = –13.5 (s,
2
3
6
6
–
1
+
785.01 g mol , monoclinic, space group P2 /c, a = 17.7981(15) Å,
PCy ) ppm. MS (ESI): m/z = 865.53 [M + H] (expected isotopic pro-
1
2
b = 15.3224(14) Å, c = 19.0158(13) Å, ꢀ = 117.920(6)°, V =
files). C H O P (865.17): calcd. C 80.52, H 8.50; found C 80.61, H
58 73 4
3
–3
–1
4
1
582.2(7) Å , Z = 4, D = 1.138 mg m , μ = 0.103 mm , F(000) =
8
.64.
x
696, T = 173(2) K. The sample (0.500 × 0.350 × 0.300 mm) was
Chlorido[5-(2-diisopropylphosphinophenyl)-25,26,27,28-tetra-
propyloxycalix[4]arene] Gold(I) (7): A solution of [AuCl(THT)]
studied on a Kappa APEX II diffractometer (graphite monochro-
mated Mo-K radiation, λ = 0.71073 Å). The data collection (2θ
=
max
α
(
0.063 g, 0.2 mmol) in CH Cl (25 mL) was added to a stirred solu-
2 2
55.9°, omega scan frames by using 0.7° omega rotation and 30 s
tion of 5 (0.155 g, 0.2 mmol) in CH Cl (25 mL). After stirring at
2
2
per frame, range hkl: h –19,23 k –20,20 l –25,11) gave 11043 reflec-
room temperature for 0.5 h, the reaction mixture was concentrated
to about 2 mL, and then n-hexane (20 mL) was added. A white
precipitate formed, which was then separated by filtration and dried
[20]
tions. The structure was solved with SIR-97,
which revealed the
non-hydrogen atoms of the molecule. After anisotropic refinement,
all of the hydrogen atoms were found with a Fourier difference
1
under vacuum to give compound 7 (0.124 g, 95 % yield). H NMR
[21]
map. The structure was refined with SHELXL97 by the full-matrix
(
500 MHz, CDCl ): δ = 7.48–7.44 (m, 1 H, arom. CH, C H ), 7.35–7.31
3
6
4
least-square techniques (use of F square magnitude; x, y, z, ꢀij for
C, O, and P atoms; x, y, z in riding mode for H atoms); 536 variables
3
(m, 2 H, arom. CH, C H ), 6.91 (d, J = 7.0 Hz, 2 H, arom. CH, calixa-
6
4
3
3
rene), 6.87 (d, J = 7.0 Hz, 2 H, arom. CH, calixarene), 6.73 (t, J =
.0 Hz, 2 H, arom. CH, calixarene), 6.61–6.57 (m, 1 H, arom. CH,
C H ), 6.41 (s, 3 H, arom. CH, calixarene), 6.18 (s, 2 H, arom. CH,
2
2
and 8258 observations with I > 2.0 σ(I); calcd. w = 1/[σ (F ) +
o
7
2
2
2
(
0.0492P) + 3.8030P] where P = (F + 2F )/3, with the resulting
R = 0.0531, RW = 0.1380, and SW = 1.020, Δρ < 0.878 e Å .
o c
–3
6
4
2
calixarene), 4.53 and 3.25 (AB spin system, J = 13.5 Hz, 4 H,
ArCH Ar), 4.49 and 3.17 (AB spin system, J = 13.0 Hz, 4 H, ArCH Ar),
4
(
X-ray Crystal Structure Analysis of 7: Single crystals of 7 suitable
for X-ray analysis were obtained by slow diffusion of methanol into
2
2
2
3
3
.03 (t, J = 7.0 Hz, 4 H, OCH ), 3.99 (t, J = 7.5 Hz, 2 H, OCH ), 3.75
2
2
a
1
1
6
3
chloroform solution of the complex. Crystal data: Mr =
3
t, J = 6.0 Hz, 2 H, OCH ), 2.35–2.28 [m, 2 H, CH(CH ) ], 2.05–1.88
2 3 2
–1
017.42 g mol , triclinic, space group P1¯, a = 11.2854(7) Å, b =
3
3
(
m, 8 H, CH CH ), 1.23 [dd, J = 18.5 Hz, J = 6.5 Hz, 6 H, CH(CH ) ],
2 3 P, H 3 2
2.4261(8) Å, c = 19.8280(13) Å, α = 87.284(2)°, ꢀ = 79.750(1)°, γ =
3
3
1
1
7
.12 (t, J = 7.0 Hz, 3 H, CH CH ), 1.07 (t, J = 7.2 Hz, 3 H, CH CH ),
2 3 2 3
3
–3
6.829(1)°, V = 2514.7(3) Å , Z = 2, D = 1.344 mg m , μ =
.051 mm , F(000)
3
3
3
x
.01 [dd, J = 17.5 Hz, J = 7.0 Hz, 6 H, CH(CH ) ], 0.95 (t, J =
.0 Hz, 6 H, CH CH ) ppm. C{ H} NMR (125 MHz, CDCl ): δ = 157.52
P, H
3 2
–1
= 1040, T = 173(2) K. The sample
1
3
1
2
3
3
(0.320 × 0.180 × 0.160 mm) was studied on a Kappa APEX II diffrac-
(
s, arom. Cq-O), 156.44 (s, arom. Cq-O), 155.97 (s, arom. Cq-O),
tometer (graphite monochromated Mo-K radiation, λ = 0.71073 Å).
α
1
7
3
2
49.95–121.95 (arom. carbons), 78.19 (s, OCH ), 77.19 (s, OCH ),
2 2
The data collection (2θmax = 61.8°, omega scan frames by using 0.7°
omega rotation and 30 s per frame, range hkl: h –16,9 k –17,17 l
1
6.75 (s, OCH ), 31.28 (s, ArCH Ar), 31.13 (s, ArCH Ar), 27.23 [d, J =
P, C
2
2
2
3.8 Hz, CH(CH ) ], 23.78 (CH CH ), 23.54 (CH CH ), 23.16 (CH CH ),
3
2
2
3
2
3
2
3
–
9
28,28) gave 60478 reflections. The structure was solved with SIR-
0.36 [s, CH(CH ) ], 19.71 [s, CH(CH ) ], 10.94 (CH CH ), 10.76
3
2
3 2
2
3
[20]
7,
which revealed the non-hydrogen atoms of the molecule.
3
1
1
(CH CH ), 10.13 (CH CH ) ppm. P{ H} NMR (162 MHz, CDCl ): δ =
2 3 2 3 3
After anisotropic refinement, all of the hydrogen atoms were found
with a Fourier difference map. The structure was refined with
4
9.4 (s, PiPr ) ppm. C H AuClO P (1017.46): calcd. C 61.38, H 6.44;
2 52 65 4
found C 61.45, H 6.52.
[
21]
SHELXL97
by the full-matrix least-square techniques (use of F
trans-P,P-Dichlorido-bis[5-(2-diisopropylphosphinophenyl)-
square magnitude; x, y, z, ꢀij for Au; C, Cl, O and P atoms; x, y, z in
2
5,26,27,28-tetrapropyloxy-calix[4]arene]palladium(II) (9): A so-
riding mode for H atoms); 540 variables and 13416 observations
2
2
2
lution of [PdCl (PhCN) ] (0.012 g, 0.03 mmol) in CH Cl (10 mL) was
with I > 2.0 σ(I); calcd. w = 1/[σ (F ) + (0.0264P) + 1.0409P] where
2
2
2
2
o
Eur. J. Org. Chem. 2016, 1867–1873
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1872
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
P = (F 2 + 2F )/3, with the resulting R = 0.0289, R = 0.0608 and
2
[6] D. Gelman, S. L. Buchwald, Angew. Chem. Int. Ed. 2003, 42, 5993–5996;
Angew. Chem. 2003, 115, 6175.
o
c
W
–
3
SW = 1.055, Δρ < 1.692 e Å .
[
7] T. E. Barder, S. D. Walker, J. R. Martinelli, S. L. Buchwald, J. Am. Chem. Soc.
CCDC 1447135 (for 5) and 1447135 (for 7) contain the supplemen-
tary crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre.
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