Synthesis of new Calix[4] arene-based phosphorus ligands and their application in the Rh(l) catalyzed hydroformylation of 1-octene

Article abstract of DOI:10.1002/hc.1088

The synthesis of calix[4]arene-based phosphorus diamides and phosphites is described. These oligocyclic ligands have been tested in the Rh(I)-catalyzed hydroformylation of 1-octene. Depending on the reaction conditions, yields up to 99% and n/iso-selectivities between 0.7 and 2.6 have been observed. tert-Butyl groups on the upper rim of the calix[4]arene template had a beneficial effect on the catalytic reaction. In general biuret-derived P-ligands were superior. For comparison, the corresponding "monomeric" ligands have also been synthesized and were employed in the catalytic reaction.

Full text of DOI:10.1002/hc.1088

Heteroatom Chemistry
Volume 12, Number 7, 2001
S
ynthesis of New Calix[4]arene-Based
Phosphorus Ligands and Their Application
in the Rh(I) Catalyzed Hydroformylation
of 1-Octene
1
2
1
1
2
C. Kunze, D. Selent, I. Neda, R. Schmutzler, A. Spannenberg,
2
and A. B o¨ rner
1
Institut f u¨ r Anorganische und Analytische Chemie der Technischen Universit a¨ t, Postfach 3329,
D-38023 Braunschweig, Germany; E-mail: r.schmutzler@tu-bs.de
2
Institut f u¨ r Organische Katalyseforschung an der Universit a¨ t Rostock e.V., Buchbinderstraße 5-6,
D-18055 Rostock, Germany; E-mail: armin.boerner@ifok.uni-rostock.de
Received 15 February 2001; revised 19 March 2001
in homogeneously metal-catalyzed reactions is a
ABSTRACT: The synthesis of calix[4]arene-based
rapidly growing field of general interest [1]. In par-
ticular P-ligands derived from calix[4]arenes form
metal complexes with unique coordination modes
phosphorus diamides and phosphites is described.
These oligocyclic ligands have been tested in the Rh(I)-
catalyzed hydroformylation of 1-octene. Depending on
[2]. In addition, the interior of the cavity represents
the reaction conditions, yields up to 99% and n/iso-
selectivities between 0.7 and 2.6 have been observed.
tert-Butyl groups on the upper rim of the calix[4]arene
template had a beneficial effect on the catalytic reac-
tion. In general biuret-derived P-ligands were superior.
For comparison, the corresponding “monomeric” lig-
ands have also been synthesized and were employed in
the catalytic reaction. �C 2001 John Wiley & Sons, Inc.
a space potentially able to entrap or confine reactive
fragments bound to the transition metal [3]. Sev-
eral calix[4]arene ligands are easily available, and
their synthesis is frequently based on a few steps.
By functionalization of calix[4]arenes with phos-
phorus groups, a broad variety of phosphorus lig-
ands, for example, phosphines or phosphites with
different hapticity, electronic, and steric properties
can be produced [4]. Selective functionalization of
calix[4]arenes allows the incorporation of one [5],
two [6], three [7], four [8] or even more [9] identi-
cal or different [10] phosphorus groups in a single
calix[4]arene template. By substitution of the oppo-
site rim, for example by the incorporation of bulky
alkyl groups, further modifications influencing the
coordination behavior and catalytic properties are
possible.
Heteroatom Chem 12:577–585, 2001
INTRODUCTION
The synthesis of trivalent phosphorus compounds
based on calixarenes and their application as ligands
Dedicated to Professor Marianne Baudler on the occasion of her
0th birthday.
A particular challenge is the application of
calix[4]arene-containing phosphorus ligands in the
homogeneously catalyzed hydroformylation of ole-
fins. This reaction is of pivotal importance for acade-
mic research as well as for industrial application
8
Correspondence to: R. Schmutzler and A. B o¨ rner.
Contract Grant Sponsor: Fonds der Chemischen Industrie.
Contract Grant Sponsor: Oxeno Olefinchemie GmbH, Marl.
�
c 2001 John Wiley & Sons, Inc.
577

578 Kunze et al.
R1
R1
R1
R1
[11]. More than 7 million tons, in particular n-
R1
R1
R1
R1
R1
aldehydes, are produced annually in the bulk and
specialty chemicals business. In the search for new
and more efficient hydroformylation catalysts up to
now mainly Rh(I) catalysts based on monophos-
phines and bisphosphines or monophosphites and
bisphosphites have been investigated. In general,
an excess of the phosphorus ligand has to be ap-
plied to avoid its full displacement from the metal
by the competing CO. Considerable evidence was
accumulated that with bidentate bisphosphines the
ligand bite angle is of crucial importance for the re-
gioselectivity in the hydroformylation product [12].
Other studies revealed that ligands with electron-
withdrawing groups form more active and selec-
tive catalysts [13]. Recently, we showed methoxy or
hydroxy groups adjacent to the phosphorus func-
tionality to also exert a beneficial effect on the
n-regioselective hydroformylation of internal olefins
H3C
CH3
OR2
OR2
OR2
OMe
OMe
OR2
OR2
OR2
OR2
1- 4
5
6, 7
H3C
P
O
N
O
1
1
1
1
t
1:
R
R
R
R
= Bu
N
N
C
C
3
:
= H
R2
=
t
CH3
5:
= Bu
6
:
= H
H3C
1
t
2
4
7
:
:
:
R = Bu
= H
= H
O
O
1
1
R2
=
R
R
P
SCHEME 1 Various ligands used in the hydroformylation
reactions.
suggested that they are electronically closely related
to phosphites. However, the biuret group was consid-
ered to be a better electron acceptor than two aryloxy
groups. Therefore, the comparison with analogous
phosphites like the calix[4]arene-based tetraphos-
phite 2 (Scheme 1) seems to be of general interest. In
order to study the effect of the tert-butyl substituents
on the upper rim of the calix[4]arene fragment,
we also synthesized the analogous compounds 3
and 4. Prior protection of the hydroxy groups in
the 1,3-positions as methyl ether and subsequent
substitution of the remaining hydroxy groups with
phosphorus-containing groups afforded the biden-
tate ligand 5 bearing methoxy groups as potentially
hemilabile [21] ligands in close neighborhood to the
P-ligating atoms. In order to identify catalytic effects
that might be related to the cavity of the calixarene
moiety, we also synthesized the “monomeric” ligands
6 and 7.
For the synthesis of calix[4]arene-containing
phosphorus ligands, the required phenolates were
generated by treatment of the macromolecular
phenols with n-BuLi. Subsequent addition of four
and two equivalents, respectively, of 2-chloro-1,3,5-
trimethyl-1,3,5-triaza-2� � -phosphorin-4,6-dione
afforded the desired derivatives 1–5 (Scheme 2).
The phosphites 2 and 4 (Scheme 2) were syn-
thesized by the same method applying 2-chloro-1,3-
[14].
Due to the broad tunability and variability
outlined above, calix[4]arene-containing phospho-
rus groups as ligands should have an interesting
potential for selective hydroformylation reactions.
Indeed, as recently shown, bidentate bisphosphites
with a calix[4]arene backbone can advantageously
be employed for the Rh(I)-catalyzed hydroformy-
lation of 1-octene under low pressure affording
good n:iso ratios [15]. Calix[4]arene phosphines and
phosphinites, bonded to Pt(II), have also been suc-
cessfully applied in hydroformylation catalysis [16].
In particular, attractive for an industrial application
is the unique air-robustness of calix[4]arene mono-
phosphites reported recently [17]. Such monophos-
phites are less �-acidic than most triarylphosphite
ligands. Moreover, by incorporation of sulfonate
groups in calix[4]arene bisphosphines, water-solubi-
lity of the hydroformylation catalyst can be achieved
[18].
Herein, we describe the synthesis of electron-
poor calix[4]arene based phosphorus diamides and
phosphites and their application in the hydroformyl-
ation of 1-octene. In a previous article, some of us re-
ported that the reaction of p-tert-butyl-calix[4]arene
3
3
3
3
with
2-chloro-1,3,5-trimethyl-1,3,5-triaza-2� � -
phosphorin-4,6-dione gives rise to the calix[4]arene-
based tetradentate ligand 1 [19].
3
3
dioxa-2� � -phospholane as a reagent.
The reaction of 2,6-dimethylphenol with one
equivalent of n-BuLi and subsequent addition of one
equivalent of 2-chloro-1,3,5-trimethyl-1,3,5-triaza-
RESULTS AND DISCUSSION
3
3
2
� � -phosphorin-4,6-dione or 2-choro-1,3-dioxa-
Synthesis of the Ligands
3
3
2
� � -phospholane afforded, after vacuum distil-
In general, phosphoric acid diamides are stronger
lation, the analytically pure compounds 6 and 7
(Scheme 3). These oily colorless liquids proved to
be air- and moisture-sensitive. All new compounds
�
-acids than triarylphosphines and more basic
than triarylphosphites. Van Leeuwen et al. [20]

Synthesis of New Calix[4]arene-Based Phosphorus Ligands 579
R1
R1
R1
R1
1
. 4 BuLi, THF
1. 2 BuLi, THF
2
2
R = H
R = Me
OR2
OH
3
H C
O
N
O
OH
OR2
N
N
C
C
3
2
. 2 Cl
P
CH3
2
. 4 R Cl
H C
3
R1
R1
R1
tBu
tBu
tBu
tBu
R1
OR3
OR3
OR3
OR3
OMe
OMe
OR3
OR3
1
- 4
5
1
t
H C
O
C
R = Bu, H
3
N
H C
3
O
C
3
R =
P
N
CH3
N
N
O
O
N
C
3
R =
P
N
CH3
P
H C
3
O
,
C
H C
3
O
SCHEME 2 Synthesis of the ligands 1–5.
The molecular structure of 3, which was deter-
mined by X-ray crystallography, is depicted in
Figure 1.
The X-ray crystal structure analysis confirmed
the expected cone conformation of the calix[4]arene
framework. The interplanar angles between the aro-
matic rings of the macrocycle and the calixarene
reference plane (the average plane defined by the
1
. BuLi, THF
1
H3C
O
CH3
H C
CH3
3
2. R Cl
OR1
, 7
OH
6
H C
O
3
N
C
C
1
R =
P
N
O
CH3
P
,
N
O
four bridging methylene carbon atoms) are 32.8,
H C
3
�
7
2.5 and 38.5 and 72.3 (Figure 2). This cone con-
formation is distorted such that the distances be-
tween the centers of the opposite phenolic rings show
remarkable differences. The distances between the
SCHEME 3 Synthesis of the ligands 6 and 7.
˚
centers of the opposite phenolic rings are 4.529 A and
˚
reported herein were characterized using mass spec-
trometry, NMR spectroscopy, and elemental anal-
ysis, giving results consistent with their expected
structures.
7.825 A, respectively. As a result, two 1,3,5-triaza-
3
3
2� � -phosphorin-4,6-dionyloxy groups are pointing
away from the calix[4]arene cavity. The remaining
two heterocycles approach each other in order to

580 Kunze et al.
1
13
the H and C NMR spectra. By contrast, the 1,3-
disubstituted compound 5 was characterized by a
31
single resonance in the P NMR spectrum. In the
13
C NMR spectrum one singlet for the C-atoms of
the bridging methylene groups was observed. Both
observations establish a normal cone conformation.
The same standard cone conformation was deduced
from the corresponding NMR spectra of compounds
2
and 4.
Hydroformylation
Rhodium complexes of all new phosphorus ligands
were tested in the hydroformylation of 1-octene. As
illustrated in Scheme 4, depending on the extent
of olefin isomerization prior to the hydroformyla-
tion, besides n-nonanal and 2-methyloctanal, differ-
ent branched aldehydes can be formed from the cor-
responding internal olefins.
The hydroformylation reactions were carried out
FIGURE 1 Molecular structure of 3 in the crystal. Hydro-
gen atoms are omitted for clarity. The thermal ellip-
soids correspond to 30% probability. Selected bond
with a 1:1 mixture of CO and H at a pressure of
2
4
0 or 50 bar. Precatalysts were generated prior to
�
the hydroformylation in situ by mixing the rele-
vant P-ligand with [(acac)Rh(1,5-cyclooctadiene)] in
toluene. Depending on the solubility of the precata-
lysts, toluene, tetrahydrofuran (THF), or methylene
chloride were used as solvents. In addition, the effect
of varying Rh:ligand ratios was also investigated. In
all trials, the ratio Rh:olefin of 1:15,700 was kept con-
stant. Results of the catalytic reactions are summa-
rized in Table 1.
lengths (pm) and angles( ): P(1)–O(2) 166.9(4), P(2)–O(3)
1
66.9(5), P(3)–O(1) 166.9(4), P(4)–O(4) 166.5(5), O(1)–
C(68) 140.9(7), O(4)–C(27) 140.3(7), O(3)–C(18) 142.0(7),
O(2)–C(2) 142.0(8); N(1)–P(3)–N(3) 96.0(3), N(7)–P(2)–N(8)
9
5.1(3), N(6)–P(1)–N(2) 94.8(3), N(5)–P(4)–N(4) 95.6(3),
C(68)–O(1)–P(3) 121.4(3), C(27)–O(4)–P(4) 125.3(4),
C(18)–O(3)–P(2) 124.0(4), C(2)–O(2)–P(1) 124.2(4), C(9)–
C(10)–C(11) 110.0(5), C(17)–C(16)–C(15) 109.9(6), C(5)–
C(4)–C(3) 109.8(5), C(1)–C(20)–C(19) 109.1(5).
It is obvious that all Rh(I)-complexes tested cat-
alyze the hydroformylation of 1-octene. The reaction
is sensitive to the conditions and ligands employed.
In general, the increase of the P:Rh ratio enhances
the n:iso-selectivity. As seen in the reactions with 1
a ligand, the change from toluene to THF as sol-
vent can improve the regioselectivity as well as the
yield. In the case of 5 and 6 the use of higher P:Rh
ratios also improved the overall yield. The applica-
tion of the bidentate ligand 5 bearing two additional
hemilabile methoxy groups had no advantage over
the use of the tetradentate ligand 1. At a P:Rh ra-
tio of 1:1 the presence of four tert-butyl groups in
the p-position of the calix[4]arene template did not
change the catalytic results (1 versus 3) because of
the distance of these groups from the metal center.
Thus, the steric influence of the butyl groups is not
significant. However, at a higher P:Rh ratio, the cat-
alyst based on 1 was superior in terms of activity. It
is noteworthy that, with all ligands (except when 3
was used in a large excess), the activities were good
or even excellent. The comparison of the results ob-
tained with catalysts based on 1 and the monomeric
ligand 6 indicates that the assembly of four ligating
FIGURE 2 Two views (Schakal-92) of 3 showing the relative
arrangement of the opposite aryl rings of the calixarene part.
minimize steric interactions between neighboring
phenolic groups and heterocycles.
In contrast to the crystal structure of the compa-
rable calixarene 1, the opposite aryl rings of com-
pound 3 are neither coplanar nor perpendicular
�
�
(
Figure 2) in the crystalline state (35.2 and 71.3 ,
respectively) [19]. Obviously, the cone conformation
31
dominates in solution. Thus, in the P NMR spec-
trum, two well separated resonances at � = 92.6 and
9
6.7 were observed, because of the hindered rota-
tion about the P–O bond. The bridging methylene
groups were characterized by two sets of signals in

Synthesis of New Calix[4]arene-Based Phosphorus Ligands 581
O
C
cat.
n-nonanal
H
+
CO + H2
H2
2-methyloctanal
C
H
O
cat.
n-octane
H
O
C
cis + trans
cis + trans
2-ethylheptanal
cis + trans
C
H
O
2-propylhexanal
cat.: [Rh]
SCHEME 4 Hydroformylation reaction of 1-octene with consideration of the prior isomerization of the substrate.
phosphorus diamide groups in the calix[4]arene
structure does not disadvantageously affect the yield
as well as the selectivity of the reaction. This is in con-
trast to related investigations of van Leeuwen and
coworkers, who observed a remarkable loss of ac-
tivity by replacement of monodentate by the corre-
sponding bidentate ligands [20].
general, moderate selectivities for the formation of
the n-aldehyde were observed. Yield and regioselec-
tivity of the hydroformylation were dependent on the
structure of the ligand and the reaction conditions
applied. Catalysts based on calix[4]arene-containing
phosphorus diamide groups exhibited superior ac-
tivity in comparison to the corresponding phos-
phites. This result confirms reports in the literature
on effects obtained by the use of simpler phospho-
rus diamide and phosphite ligands [20]. Compared
to the corresponding monomeric ligand, in several
cases calix[4]arene-containing phosphorus diamide
groups exhibited even higher efficiency and selectiv-
ity. The opposite tendency was noted in the series of
phosphites. It seems that bulky groups like tert-butyl
groups in the p-position of the ligating groups have
a beneficial effect on the catalytic reaction. Thus,
the loss of activity by application of high P:Rh ra-
tios found with nonsubstitued calix[4]arene ligands
was prevented by tert-butyl groups in the upper rim.
The effect of additional MeO-groups in the lower
rim of calix[4]arene-containing phosphorus diamide
groups was quite small.
Compared to catalysts based on calix[4]arene bi-
uret ligands, the hydroformylation with phosphites
2, 4, and 7 is much more sensitive to the structure of
the ligands and conditions applied. In terms of activ-
ity, in general, calix[4]arene tetraphosphite-derived
complexes were inferior in comparison to the re-
lated biuret catalysts. A small increase of the P:Rh
ratio even blocked the catalytic reaction. In compari-
son to the biuret ligands slightly higher n-selectivities
were noted. The catalyst formed by the monomeric
ligand 7 was significantly more active than its
calix[4]arene counterpart but displayed reduced
selectivity.
CONCLUSION
A series of new calix[4]arene-containing phosphorus
groups were synthesized and characterized. These
compounds were tested as ligands in the Rh(I) cat-
alyzed hydroformylation of 1-octene. All ligands
could be successfully employed for this reaction. In
EXPERIMENTAL
All experiments were carried out with exclusion of
air and moisture using Schlenk techniques. Solvents

582 Kunze et al.
TABLE 1 Hydroformylation of 1-Octene with Rh-Catalysts based on Ligands of Type 1, 2, and 3a
T
p
[bar]
Yield b
(%)
n-C9
(%)
i-C8
(%)
i-C7
(%)
i-C6
(%)
�
n/isoc
Ligand [ C]
Solvent
Rh:L
1
1
1
5
5
5
3
3
6
6
2
2
4
7
120
120
120
100
100
100
100
100
100
100
120
120
100
100
50
50
50
50
50
50
40
40
40
40
40
40
40
40
Toluene
THF
THF
THF
THF
1:1
1:1
1:10
1:1
1:2
1:10
1:1
1:10
1:4
1:40
1:1
1:5
92.1
95.0
89.4
75.7
88.4
86.6
99.0
4.0
95.9
99.0
39.6
3.4
42.3
46.4
61.7
48.0
50.2
57.7
43.6
69.8
43.8
58.9
68.8
n.d.
34.6
34.2
34.8
35.6
35.0
34.7
34.9
30.2
35.3
32.7
28.5
n.d.
12.8
11.2
3.0
9.8
9.0
10.3
8.2
0.5
6.6
5.8
2.0
8.9
n.d.
9.0
2.3
0.4
n.d.
n.b.
2.1
0.73
0.87
1.61
0.92
1.01
1.36
0.77
2.31
0.78
1.43
2.19
0.0
THF
5.6
CH Cl
12.6
n.d.
11.9
6.1
2.3
n.d.
0.7
2
2
2
2
2
CH Cl
2
CH Cl
2
CH Cl
2
THF
THF
CH Cl
1:1
1:4
27.4
92.4
74.2
60.7
25.1
32.9
2.58
1.54
2
2
2
CH Cl
5.3
2
a
For conditions, see Experimental Section.
Overall yield after 3 hours determined by VPC, with toluene as internal standard.
Corresponds to the sum of all branched aldehydes formed. The amount of octane formed in this reaction is less than 1%.
b
c
were dried according to standard procedures and
distilled immediately prior to use. The NMR spec-
tra were recorded on Bruker AC 200 (200.1 MHz
driven stirrer. In a typical experiment, the autoclave
was flushed several times with argon and after-
wards charged with 5 mL of an 0.0121 M solution
of [(acac)Rh(1,5-cyclooctadien)] in toluene, 51 mL
of solvent, and the amount of the P-ligand indicated.
Then the substrate in solution (15 mL of 1-octene)
was charged into the reservoir. The autoclave was
then pressurized with 30–33 bar of syngas and heated
1
13
for H NMR, 50.3 MHz for C NMR, and 81.0 MHz
3
1
for P NMR spectra), Bruker DRX-400, and Bruker
1
ARX 400 instruments (400.1 MHz for H-NMR, 100.6
1
3
31
MHz for C NMR and 162.0 MHz for P NMR
spectra); solvent CDCl ; shifts are given, relative to
3
1
13
31
�
TMS ( H, C) and 85% H
3
PO
4
( P). The mass spec-
with stirring (1500 rpm) at 100 or 120 C. When the
tra were recorded on a Finnigan Mat 8430 and an
AMD Intectra 402/3. Elemental analysis data were
obtained on a Carlo Erba analytical gas chromato-
graph. The abreviation “i.v.” refers to a pressure of 0.1
mm Hg.
appropriate temperature was reached, the pressure
was increased to 40 or 50 bar. During the whole re-
action, the pressure was kept constant by means of a
pressure controller (Fa. Bronkhorst, NL). Gas chro-
matographic analyses were performed on a Hewlett
Packard 5890 Series II Plus instrument, equipped
with a 50 m methyl siloxane cross-linked phase col-
umn (inner diameter 0.2 mm, film thickness 0.5 �m)
and a flame ionization detector (FID).
p-tert-Butyl-calix[4]arene [22], calix[4]arene [23],
p-tert-butyl-bis-dimethoxycalix[4]arene [24], and
3
3
2
-chloro-1, 3, 5-trimethyl-1,3,5-triaza-2� � -phos-
phorin-4,6-dione [25] were prepared according to
literature procedures.
The X-ray diffraction data of compound 3
were collected on a STOE-IPDS diffractometer
using graphite-monochromated Mo K� radia-
tion. The structure was solved by direct meth-
ods (SHELXS-86) [26] and refined by full-matrix
3
3
p-tert-Butyl-tetrakis(1,3-dioxa-2� � -
phospholanoxy)calix[4]arene 2 (cone
conformation)
A hexane solution of n-BuLi (15.4 mL, 1.6 M,
24.64 mmol) was added to a suspension of p-tert-
butyl-calix[4]arene (4.0 g, 6.16 mmol) in 50 mL of
THF at room temperature. The resulting yellowish
slurry was stirred for 2 hours. Neat 2-chloro-1,3-
dioxa-2� � -phospholane (3.14 g, 24.83 mmol) was
added to the suspension, using a syringe, whereupon
the color changed from yellow to colorless. The re-
action mixture was stirred for 4 days at room tem-
2
least-squares techniques against F (SHELXL-93)
[27]. XP (Siemens Analytical X-ray Instruments,
Inc.) and Schakal-92 were used for structure
representations.
The hydroformylation experiments were per-
formed in a stainless steel 200 mL autoclave
3
3
(Buddeberg GmbH, Mannheim, Germany), equip-
ped with a reservoir, a pressure transducer, a ther-
mocouple, a sampling device, and a magnetically
31
perature and examined by P NMR spectroscopy,

Synthesis of New Calix[4]arene-Based Phosphorus Ligands 583
3
1
which indicated the formation of 2. The suspension
was filtered and the precipitate was dried i.v. for 4
hours. The remaining solid was redissolved in 30 mL
C(:O)NP); P NMR (81.0 MHz, CDCl ): � = 92.6 (s),
3
+
96.7 (s); FAB MS, m/z (%): 1139 (5) [M + Na] , 1117
+
+
(13) [M + H] , 942 (8) [M–C H N O P] , 769 (8) [M
5
9
3
2
+
CH
2
Cl
2
, and LiCl was removed by filtration through
Cl washings of the
+ H � 2x C H N O P], 174 (100) [C H N O P] ; ESI-
5
9
3
2
5
9
3
2
+
Celite. The filtrate and the CH
2
2
MS, m/z (%): 1139 (100) [M + Na] ; Anal. Calcd. for
Celite were combined before evaporation to dryness.
The colorless, moisture-sensitive solid 2 was dried
i.v. for 14 hours at room temperature. (5.03 g, 81%),
C H N O P (1116.94): C, 51.62; H, 5.05; N, 15.05.
48
56 12 12
4
Found: C, 53.50; H, 5.38; N, 12.41.
�
1
m.p. 278 C; H NMR (400.1 MHz, CDCl
3
): � = 0.99
); 3.08 (d, 4 H, J(HH) = 13.3 Hz,
Ar-CH H -Ar); 3.84–3.88 (m, 16 H, O–P–O–CH ), 4.67
Crystal Data of 3
2
(
s, 36 H, C(CH
)
3 3
1
2
Suitable crystals of 3 for the X-ray crystal structure
were obtained by slow diffusion of pentane into a
toluene solution of 3. Crystal dimensions 0.5 � 0.4
� 0.3 mm, colorless determination prisms, space
2
2
1
2
(
d, 4 H, J(HH) = 13.2 Hz, Ar-CH H -Ar); 6.68 (s, 8
13
3
H, Ar-H); C NMR (100.6 MHz, CDCl
): � = 31.29
1
2
(
s, 12 C, C(CH
s, 4 C, C(CH
s, 8 C, m-C); 125.87 (s, 4 C, p-C); 133.32 (s, 8 C, o-C);
3
)
3
); 32.69 (s, 4 C, Ar-CH H -Ar); 33.77
(
3
)
3
); 65.06 (s, 8 C, O–P–O–CH
2
); 124.89
group P2
1
/n, monoclinic, a = 1364.8(3) pm, b =
�
(
1
2254.6(5) pm, c = 2215.6(4) pm, � = 92.49(3) , V =
31
˚
3
� 3
45.51 (s, 4 C, ipso-C); P NMR (81.0 MHz, CDCl
= 124.5 (s); ESI-MS, m/z (%): 1031.3 (100) [M +
Na] , 647.5 (100) [M–4 PO ]; Anal. Calcd. for
(1009.00): C, 61.90; H, 6.79. Found: C,
1.35; H, 7.14.
3
):
6811 A , Z = 4, �
= 1.262 g cm , 29575 reflections
calcd
�
measured, 8747 were independent of symmetry and
3423 were observed (I > 2�(I)), R1 = 0.066, wR2 (all
data) = 0.176, 750 parameters.
+
2
C
2
H
4
C
52
H
68
O
12
P
4
6
Full details (excluding structure factors) have
been deposited at the Cambridge Crystallographic
Data Centre, 12 Union Rd., GB-Cambridge CB2 1EZ,
under the number CCDC-165694. Copies may be ob-
tained free of charge on application to the Director
c( Ta eml e. fa ac x. u: kI n) .t . +12 23 33 60 33; e-mail: deposit@ccdc.
3
3
Tetrakis(1,3,5-trimethyl-1,3,5-triaza-2� � -
phosphorin-4,6-dionyloxy)-calix[4]arene 3
A hexane solution of n-BuLi (11.75 mL, 1.6 mol/L,
1
8.8 mmol) was added dropwise to a stirred solu-
tion of calix[4]arene (2.0 g, 4.7 mmol) in 40 mL of
THF at room temperature. After the mixture had
been stirred for 2 hours, 2-chloro-1,3,5-trimethyl-
3
3
Tetrakis(-1,3-dioxa-2� � -phospholanoxy-)
calix[4]arene 4
3
3
1
,3,5-triaza-2� � -phosphorin-4,6-dione (3.95 g, 18.8
mmol) was added slowly to the yellowish reaction
mixture using a cannula. The resulting suspension
was stirred at room temperature for an additional
A hexane solution of n-BuLi (29.45 mL, 1.6 M,
47.12 mmol) was added to a solution of calix[4]arene
(5.0 g, 11.78 mmol) in 100 mL of THF at room tem-
perature, and the resulting orange slurry was stirred
3
1
2
days. A P NMR spectrum showed the formation
3
3
of 3. The precipitate formed was filtered off and dried
i.v. for 4 hours at room temperature. The residue was
for 2 hours. Subsequently 2-chloro-1,3-dioxa-2� � -
phospholane (5.96 g 47.12 mmol) was added to the
suspension with stirring at room temperature. The
formation of a white precipitate was observed after
a few minutes. The reaction mixture was stirred for
an additional 16 hours at room temperature. Exami-
then dissolved in 20 mL of CHCl
moved by filtration through Celite. The filtrate and
the CHCl washings were combined before evapo-
3
, and LiCl was re-
3
ration to dryness. The colorless, moisture-sensitive
31
solid 3 was dried i.v. for 12 hours at room tempera-
nation by P NMR spectroscopy showed the forma-
tion of 4. The precipitate was separated by filtration
and dried i.v. for 4 hours at room temperature. After
�
1
ture (7.60 g, 68%), m.p. 331 C; H NMR (400.1 MHz,
CDCl NC(:O)); 3.13 (d, 2 H,
): � = 2.56 (s, 12 H, CH
-Ar); 3.19 (d, 12 H, J(HP)
3
3
2
3
J(HH) = 14.9 Hz, Ar-CH
2
drying, the solid was redissolved in 40 mL of CH
and filtered through Celite in order to remove LiCl.
The filtrate and the CH Cl washings were combined
2
Cl
2
2
=
12.5 Hz, CH
3
NP); 3.21 (d, 2 H, J(HH) = 14.5 Hz,
3
Ar-CH
2
-Ar); 3.22 (d, 12 H, J(HP) = 12.4 Hz, CH
3
NP);
2
2
2
3
2
.95 (d, 2 H, J(HH) = 14.1 Hz, Ar-CH
2
-Ar); 4.00 (d,
and evaporated to dryness. Drying of the resulting
precipitate for 12 hours at room temperature gave 4
as a colorless, moisture-sensitive solid. (7.02 g, 76%),
2
H, J(HH) = 13.7 Hz, Ar-CH
2
-Ar); 6.01–7.16 (m, 12
): � = 29.96
-Ar); 31.67
1
3
H, Ar-H); C NMR (100.6 MHz, CDCl
3
�
1
(
(
s, 4 C, CH
s, 2 C, Ar-CH
3
NC(:O)); 31.40 (s, 2 C, Ar-CH
2
m.p. 268 C; H NMR (400.1 MHz, CDCl
3
): � = 3.12 (d,
2
2
1
2
2
-Ar); 34.75 (d, 4 C, J(CP) = 40.0 Hz,
4 H, J(HH) = 13.7 Hz, Ar-CH H -Ar); 3.79–3.91 (m,
2
2
CH
1
=
3
NP); 34.85 (d, 4 C, J(CP) = 39.1 Hz, CH
3
NP);
16 H, O-P-O-CH
2
), 4.66 (d, 4 H, J(HH) = 13.7 Hz,
2
1
2
13
20.44–145.86 (m, 24 C, Ar-C); 152.88 (d, 4 C, J(CP)
Ar-CH H -Ar); 6.53–6.99 (m, 12 H, Ar-H); C NMR
2
1
2
7.8 Hz, C(:O)NP); 152.92 (d, 4 C, J(CP) = 7.7 Hz,
(100.6 MHz, CDCl
3
): � = 32.38 (s, 4 C, Ar-CH H -Ar);

584 Kunze et al.
6
5.12 (s, 8 C, O–P–O–CH
2
); 122.93 (s, 4 C, p-C);
ane, 32.7 mmol) was slowly added at room tem-
perature. The resulting yellow mixture was stirred
for 2 hours. Subsequently, 2-chloro-1,3,5-trimethyl-
1
28.13 (s, 8 C, m-C); 134.50 (s, 8 C, o-C); 147.77 (s, 4
3
1
C, ipso-C); P NMR (81.0 MHz, CDCl
3
+
): � = 124.9 (s);
3
3
FAB MS, m/z (%): 791 (10) [M + Li] , 701 (4) [M +
1,3,5-triaza-2� � -phosphorin-4,6-dione (6.86 g, 32.7
mmol) was added slowly to the yellow suspension,
using a cannula. Stirring at room temperature was
continued for 15 hours to complete the reaction. Ex-
+
Li� PO
2
C
2
H
4
] ; Anal. Calcd. for C36
H
36
O
12
4
P (784.57):
C, 55.11; H, 4.62. Found: C, 55.90; H 4.92.
31
p-tert-Butyl-dimethoxy-bis(1,3,5-trimethyl-1,3,5-
triaza-2� � -phosphorin-4,6-dionyloxy)-
calix[4]arene 5 (cone conformation)
amination of the brownish mixture by P NMR spec-
troscopy indicated the formation of 6. The brownish
mixture was separated from the precipitate by fil-
tration, and the solvent was evaporated i.v. at room
temperature. The resulting oily liquid was dissolved
3
3
A hexane solution of n-BuLi (1 ml, 1.6 M, 1.6
mmol) was added slowly to a solution of p-tert-
butyl-bis-dimethoxycalix[4]arene (0.54 g, 0.8 mmol)
in 5 mL of THF at room temperature. The immediate
formation of a yellowish solution was observed.
After stirring for 2 hours at room temperature, 2-
chloro-1,3,5-trimethyl-1,3,5-triaza-2� � -phospho-
rin-4,6-dione (0.34 g, 1.61 mmol) was added slowly
to the yellow suspension, using a cannula, and the
reaction mixture was stirred for 15 hours at room
temperature. A P NMR spectrum showed the
formation of 5 (� = 94.6). Removal of the precipitate
by filtration led to a yellow solution, which, after
evaporation, gave a yellowish solid. The yellow solid
was dissolved in 10 mL of toluene, and LiCl was
removed by filtration through Celite. The filtrate
and the toluene washings were combined before
in 30 mL of CH
2
2
Cl and filtered again to remove
the LiCl completely. Subsequently, the solvent and
the CH
2
Cl
2
washings were evaporated i.v. Distilla-
�
tion of the oily residue at 137 C (0.1 mm Hg) pro-
vided 3.10 g (32%) of 6 as a colorless viscous liq-
3
3
1
uid. H NMR (200.1 MHz, CDCl
3
): � = 1.99 (s, 6 H,
NC(:O)); 3.17 (d, 6 H,
NP); 6.80–6.91 (AB System,
H, Ar-H); C NMR (50.3 MHz, CDCl
): � = 16.91
s, 2 C, Ar-CH ); 30.14 (s,1 C, CH NC(:O)); 33.77 (d,
C J(CP) = 36.2 Hz, CH NP); 124.73 (s, 1 C, Ar-
Ar-CH
3
); 2.73 (s, 3 H, CH
3
3
J(HP) = 12.6 Hz, CH
3
2
13
3
3
3
1
(
2
3
3
2
3
p-C); 129.59 (s, 2 C, Ar-m-C); 129.90 (s, 2 C, Ar-o-C);
2
1
7
1
49.03 (s, 1 C, Ar-ipso-C); 153.18 (d, 2 C, J(CP) =
31
3
.5 Hz, C(:O)NP); P NMR (81.0 MHz, CDCl
): � =
+
01.7 (s); EI-MS, m/z (%): 295 (18) [M] ; Anal. Calcd.
for C13
H
18
N
3
O
3
P (295.28): C, 52.88; H, 6.14; N, 14.23.
evaporation to dryness. The resulting colorless solid
5
Found: C, 52.72; H, 7.05; N, 13.62.
�
was dried i.v. for 15 hours at 40 C (0.43 g, 55
�
1
%
=
), m.p. 301 C; H NMR (400.1 MHz, CDCl
0.70 (s, 18 H, C(CH ); 1.26 (s, 18 H, C(CH
NC(:O)); 3.11 (d, 4 H, J(HH) =
3
): �
3
3
3
)
3
3
)
3
);
2-(2,6-Dimethylphenoxy)-1,3-dioxa-2� � -
phospholane 7
2
2
1
1
.73 (s, 6 H, CH
3
1
2
3
2.6 Hz, Ar-CH H -Ar); 3.21 (d, 12 H, J(HP) =
2.2 Hz, CH NP); 3.75 (s, 6 H, O-CH ); 3.92 (d, 4
To 2,6-dimethylphenol (5.0 g, 40.9 mmol) dissolved
in 50 mL of THF, n-BuLi (25.56 ml, 1.6 M in hex-
ane, 40.9 mmol) was slowly added at room tem-
perature. After stirring for 2 hours, 2-chloro-1,3,2-
dioxaphospholane (5.17 g, 40.9 mmol) was added
slowly, using a cannula. The reaction mixture was
3
3
2
1
2
H, J(HH) = 12.4 Hz, Ar-CH H -Ar); 6.35 (s, 4 H,
Ar-H); 7.07–7.20 (m, 4 H, Ar-H); C NMR (100.6
MHz, CDCl NC(:O)); 30.83
): � = 30.06 (s, 2 C, CH
s, 12 C, C(CH ); 31.63 (s, 12 C, C(CH
13
3
3
13
(
3
)
3
3
)
3
); the
C
NMR-signals of the bridging methylene C-atoms
were overlapping with the very intense signals of
the methyl carbon atoms of the tert-butyl groups;
3
1
stirred for a further 15 hours. Examination by
P
NMR spectroscopy indicated the formation of 7. The
suspension was separated from the precipitate by
filtration. The solvent was evaporated, and the oily
3
(
3.62 (s, 4 C, C(CH
3
)
3
); 34.21 (s, 4 C, C(CH
d, 4 C, J(CP) = 39.1 Hz, CH NP); 59.85 (s, 2 C,
O-CH ); 124.62–145.48 (m, 24 H, Carom.); 153.32 (d, 4
3
)
3
); 34.74
2
3
liquid residue was dissolved in 40 mL of CH
2
2
Cl .
3
LiCl was removed by filtration through Celite. Sub-
2
31
C, J(CP) = 7.5 Hz, C(:O)NP); P NMR (81.0 MHz,
sequently the solvent and the CH
evaporated i.v. Distillation of the oily residue at 91 C
2
Cl
2
washings were
CDCl
3
): � = 94.6 (s); FAB MS, m/z (%): 1029 (100)
M + Li] , 848 (35) [M� (C P)] , 676 (14)
] , 174 (86) [C P]. Anal. Calcd. for
(1023.20): C, 65.73; H, 7.50; N, 8.21.
Found: C, 65.23; H, 7.46; N, 6.82.
�
+
+
[
[
5
H
9
N
3
O
2
(
0.3 mm Hg) provided 5.65 g (65%) of 7 as a color-
+
C
46
H
60
O
4
5
H
9
N
3
O
2
1
less viscous liquid. H NMR (200.1 MHz, CDCl
2.41 (s, 6 H, Ar-CH ); 4.09–4.29 (m, 4 H, O-P-O-
CH ); 7.00–7.12 (AB System, 3 H, Ar-H); C NMR
50.3 MHz, CDCl ); 64.01
): � = 17.37 (s, 2 C, Ar-CH
s, 2 C, O-P-O-CH ); 123.88 (s, 1 C, p-C); 128.52
s, 2 C, m-C); 130.14 (s, 2 C, o-C); 148.93 (s, 1 C,
3
): �
C
56
H
76
N
6
O
8
P
2
=
3
13
2
2
(
(
(
3
3
2
-(2,6-Dimethylphenoxy)-1,3,5-trimethyl-1,3,5-
3
3
2
triaza-2� � -phosphorin-4,6-dione 6
31
To 2,6-dimethylphenol (4.0 g, 32.7 mmol) dissolved
in 80 mL of THF, n-BuLi (20.44 ml, 1.6 M in hex-
ipso-C); P NMR (81.0 MHz, CDCl
EI-MS, m/z (%): 212 (34) [M] , 197 (4) [M� CH3] ,
3
): � = 131.6 (s);
+
+

Synthesis of New Calix[4]arene-Based Phosphorus Ligands 585
+
1
21 (100) [M� OPO
Anal. Calcd. for C10
Found: C, 56.77; H, 6.38.
2
(CH
2
)
2
] , 91 (100) [OPO
2
(CH
2
)
2
];
[11] (a) Frohning, C. D.; Kohlpaintner, C. W. In Ap-
plied Homogeneous Catalysis with Organometallic
Compounds; Cornils, B.; Herrmann, W. A., Eds.;
VCH: Weinheim, 1996; Vol. 1, p 29; (b) Botteghi, C.;
Marchetti, M.; Paganelli, S. In Transition Metals for
Organic Synthesis; Beller, M.; Bolm, C. Wiley-VCH:
Weinheim, 1998; Vol. 1, p 25.
H
13
O
3
P (212.19): C, 56.61; H, 6.18.
ACKNOWLEDGMENTS
[
12] van Leeuwen, P. W. N. M.; Kamer, P. C. J.; Reek, J. N.
H.; Dierkes, P. Chem Rev 2000, 100, 2741.
We are grateful to Mrs. M. Geisendorf for skilled
technical assistance.
[13] (a) Unruh, J. D.; Christenson, J. R. J Mol Catal 1982,
1
4, 19; (b) Moser, W. R.; Papile, C. J.; Brennon, D. A.;
Duwell, R. A. J Mol Catal 1987, 41, 271.
14] Selent, D.; Wiese, K.-D.; R o¨ ttger, D.; B o¨ rner, A. Angew
Chem 2000, 112, 1694; Angew Chem Int Ed Engl
2000, 39, 1639.
[15] Paciello, R.; Siggel, L.; R o¨ per, M. Angew Chem 1999,
111, 2045; Angew Chem Int Ed Engl, 1999, 38,
1920.
[16] Csok, Z.; Szalontai, G.; Czira, G.; Kollar, L. J
Organomet Chem 1998, 570, 23.
[17] Cobley, C. J.; Ellis, D. D.; Orpen, A. G.; Pringle, P. G.
J Chem Soc, Dalton Trans 2000, 1109.
[18] Shimizu, S.; Shirakawa, S.; Sasaki, Y.; Hirai, C.
Angew Chem 2000, 112, 1313; Angew Chem Int Ed
Engl, 2000, 39, 1256.
[19] Neda, I.; Plinta, H.-J.; Sonnenburg, R.; Fischer, A.;
Jones, P. G.; Schmutzler, R. Chem Ber 1995, 128,
267.
[20] van der Slot, S. C.; Kamer, P. C. J.; van Leeuwen, P.
W. N. M.; Fraanje, J.; Goubitz, K.; Lutz, M.; Spek, A.
L. Organometallics 2000, 19, 2504.
[21] (a) Bader, A.; Lindner, E. Coord Chem Rev 1991, 108,
27; (b) B o¨ rner, A. Eur J Inorg Chem 2001, 327.
[22] (a) Gutsche, C. D.; Muthukrishnan, R. J Org Chem,
1978, 43, 4905; (b) Gutsche, C. D.; Iqbal, M. Org Synth
1990, 68, 234.
[23] Gutsche, C. D.; Lin, L.-G. Tetrahedron 1986, 42, 1633.
[24] Dijkstra, P. J.; Brunink, J. A. J.; Bugge, K.-E.;
Reinhoudt, D. N.; Harkema, S.; Ungaro, R.; Ugozzoli,
F.; Ghidini, E. J Am Chem Soc 1989, 111, 7567.
[25] Meyer, T. G.; Jones, P. G.; Schmutzler, R. Z Natur-
forsch 1992, 47b, 517.
[26] Sheldrick, G. M. Acta Crystallogr 1990, A46, 467.
[27] Sheldrick, G. M. SHELXL-97: A Program for Crys-
tal Structure Refinement, University of G o¨ ttingen,
G o¨ ttingen, Germany, 1997.
REFERENCES
[
[
1] For reviews see: (a) Neda, I.; Kaukorat, T.;
Schmutzler, R. Main Group Chemistry News 1998,
6
(2/3)4; (b) Wieser, C.; Dieleman, C. B.; Matt, D. Co-
ord Chem Rev 1997, 165, 93.
[
2] (a) Wieser, C.; Matt, D.; Fischer, J.; Harriman, A. J
Chem Soc Dalton Trans 1997, 2391; (b) Loeber, C.;
Wieser, C.; Matt, D.; De Cian, A.; Fischer, J.; Toupet,
L. Bull Soc Chim Fr 1995, 132, 166.
[
[
[
3] (a) Wieser-Jeunesse, C.; Matt, D.; De Cian, A. Angew
Chem 1998, 110, 3027; (b) Angew Chem Int Ed Engl
1998, 37, 2861.
4] Dieleman, C. B.; Marsol, C.; Matt, D.; Kyritsakas, N.;
Harriman, A.; Kintzinger, J.-P. J Chem Soc Dalton
Trans 1999, 4139.
5] See, for example, Faidherbe, P.; Wieser, C.; Matt, D.;
Harriman, A.; De Cian, A.; Fischer, J. Eur J Inorg
Chem 1998, 451.
[
[
6] See, for example, Matt, D.; Loeber, C.; Vicens, J.;
Asfari, Z. J Chem Soc 1993, 604.
7] See, for example, (a) Dieleman, C. B.; Matt, D.; Neda,
I.; Schmutzler, R.; Harriman, A.; Yaftian, R. Chem
Commun 1999, 1911; (b) Vollbrecht, A.; Neda, I.;
Th o¨ nnessen, H.; Jones, P. G.; Harris, R. K.; Crowe,
L. A.; Schmutzler, R. Chem Ber/Recueil 1997, 130,
1
715.
[
[
8] See, for example, Dieleman, C. B.; Loeber, C.; Matt,
D.; De Cian, A.; Fischer, J. J Chem Soc Dalton Trans
1995, 3097.
9] Neda, I.; Vollbrecht, A.; Grunenberg, J.; Schmutzler,
R. Heteroatom Chem 1998, 9, 553.
[
10] Dieleman, C. B.; Matt, D.; Neda, I.; Schmutzler, R.;
Th o¨ nnessen, H.; Jones, P. G.; Harriman, A. J Chem
Dalton Trans 1998, 2215.