Synthesis and structural characterization of a series of mono-O-(diphenylphosphinobenzyl)calix[6]arenes with and without tert-butyl moieties at the upper rim

Article abstract of DOI:10.1246/bcsj.82.1187

abs Synthesis and characterization of a series of mono-O- (diphenylphosphinobenzyl)calix[6]arenes are presented. The two types of calix[6]arene moieties were prepared: 1 (with tert-butyl groups at the upper rim) and 2 (without the tert-butyl groups). With

Full text of DOI:10.1246/bcsj.82.1187

© 2009 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 82, No. 9, 1187–1193 (2009) 1187
Synthesis and Structural Characterization of a Series of
Mono-O-(diphenylphosphinobenzyl)calix[6]arenes with
and without tert-Butyl Moieties at the Upper Rim
Tetsuaki Fujihara,1 Sho Kubouchi,1,2 Yasushi Obora,2 Makoto Tokunaga,2
Kazuhiro Takenaka,2 and Yasushi Tsuji*1,2
1Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510
2Catalysis Research Center and Division of Chemistry, Graduate School of Science, Hokkaido University,
Sapporo 001-0021
Received April 13, 2009; E-mail: ytsuji@scl.kyoto-u.ac.jp
Synthesis and characterization of a series of mono-O-(diphenylphosphinobenzyl)calix[6]arenes are presented. The
two types of calix[6]arene moieties were prepared: 1 (with tert-butyl groups at the upper rim) and 2 (without the tert-butyl
groups). With regard to the position of a phosphorus atom, the diphenylphosphino group was introduced onto the ortho,
meta, or para positions with the benzyl ether moiety. These phosphines as well as their oxides were fully characterized by
elemental analysis, NMR measurements, and HR-ESI-MS. The NMR study indicated that 1 had a cone conformation
whereas 2 was very flexible in solution. These phosphines were found to be effective ligands in Rh-catalyzed
hydroformylation.
Calix[6]arene is a cyclic compound consisting of six phenol
units connected by methylene bridges in the ortho position.1
The molecules can be functionalized to provide a wide range of
unique molecular architectures.2 Recently, calix[6]arenes bear-
ing various coordination sites and their metal complexes have
been developed.3 Among them, combination of calixarenes
with phosphine functionalities, namely phosphinocalixarenes,
have received considerable attention, since phosphine ligands
generally play an important role in transition-metal-catalyzed
reactions.4 However, examples of phosphinocalix[6]arenes are
very limited5-7 because of lengthy multi-step syntheses. There-
fore, major attention has been paid to phosphinocalix[4]arenes8
due to their rigid conformation and rather simple preparation
methods.
We have developed several phosphinocalixarenes bearing
calix[4]arene9 and calix[6]arene5,6 functionalities. As for the
calix[6]arene, a triphosphinocalix[6]arene which functioned
as a tripodal phosphine ligand afforded capsule-shaped Ir(I)
and Rh(I) complexes.5 The X-ray crystal structure analysis,
31P{1H} NMR spectroscopy, and theoretical calculations indi-
cated that the complexes encapsulated a variety of molecules
size-selectively. Recently, we have also reported synthesis and
characterization of the first example of mono-phosphinoca-
lix[6]arenes.6
previous study.10 Therefore, the diphenylphosphino group was
introduced onto the ortho (1a and 2a), meta (1b and 2b), or
para (1c and 2c) positions, respectively, of the benzyl ether
moiety (Scheme 1). To the best of our knowledge, 2a-2c are
the first examples of phosphinocalix[6]arenes without tert-butyl
groups on the upper rim which can realize very flexible ring
structure. We synthesized analytically pure 1a and 1b (prep-
aration of 1c has been reported in a previous paper6) and 2a-2c,
and fully characterized them. In solution, 1a-1c adapt cone
conformation, while 2a-2c have flexible structures.
Results and Discussion
Synthesis and Crystal Structure. A series of mono-O-
(diphenylphosphinobenzyl)calix[6]arenes were synthesized
straightforwardly as shown in Scheme 2, where penta-O-
methylcalix[6]arene compounds (311 and 412) were used
as the starting materials. The reaction of 3 with Ph2P(O)-
C6H4CH2Br bearing the Ph2P(O) moiety at the ortho (5a13),
meta (5b13), or para (5c6,13) position gave the corresponding
calix[6]arenes bearing the phosphine oxide functionality
R
R
R
R
R
R
5
5
5
O
OMe
O
OMe
O
OMe
In the present study, a series of mono-O-(diphenylphos-
phinobenzyl)calix[6]arenes have been designed and synthe-
sized (Scheme 1). We focus our attention on flexibility of the
calix[6]arene moiety. Therefore, the two types of calix[6]arene
moieties were prepared: i.e., 1 (with the tert-butyl groups at the
upper rim: R = t-Bu) and 2 (without the tert-butyl groups:
R = H). Furthermore, location of the coordinating diphosphino
moiety may be crucial in catalytic reactions as described in a
PPh2
PPh2
PPh2
1b: R = t-Bu
2b: R = H
1a: R = t-Bu
2a: R = H
1c: R = t-Bu
2c: R = H
Scheme 1. A series of mono-O-(diphenylphosphinobenzyl)-
calix[6]arene.
Published on the web September 9, 2009; doi:10.1246/bcsj.82.1187

1188 Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009)
Monophosphinocalix[6]arenes
R
R
R
R
Ph2P(O)C6H4CH2Br (5a-c)
NaH
DMF, 50 °C, 20 h
5
5
OH
OMe
O
OMe
3: R = t-Bu
4: R = H
P(O)Ph2
7a: o-, R = H
7b: m-, R = H
7c: p-, R = H
6a: o-, R = t-Bu
6b: m-, R = t-Bu
6c: p-, R = t-Bu
R
O
R
5
Figure 2. 1H NMR spectra of 1b (a) and 2b (b) in CDCl3 at
room temperature. * indicates a signal for an impurity.
PhSiH3
OMe
toluene
reflux, 2 d
PPh2
Similar 1,2,3-alternate conformations in crystalline state were
also reported for some calix[6]arene derivatives.6,14
1a: o-, R = t-Bu 2a: o-, R = H
1b: m-, R = t-Bu 2b: m-, R = H
1c: p-, R = t-Bu 2c: p-, R = H
Structure in Solution. To elucidate the structure of 1 and 2
1
in solution, H and 13C{1H} NMR spectra of 1a and 1b and
2a-2c were measured in CDCl3. As shown in Figure 2a, the
1H NMR spectrum of 1b exhibited axial bridging methylene
proton resonances as three doublets at 4.08, 4.20, and 4.38 ppm
in a 1:1:1 ratio, and the corresponding equatorial proton
resonances as three doublets at 3.42, 3.67, and 3.80 ppm in a
1:1:1 ratio with geminal coupling (2JH-H = 15 Hz). It is well-
known that the difference of chemical shift (¦¤) between axial
and equatorial proton resonances of the bridging methylenes is
dependent on the orientation of the adjacent aromatic rings.15
For 1b, the ¦¤ values (0.96, 0.47, and 0.28 ppm) are quite
comparable to values reported for mono-O-benzyl-substituted
calix[6]arenes,6,16 which take cone conformation in solution.
Furthermore, in the 1H NMR spectrum of 1b, tert-butyl protons
appear as four singlet peaks in a ratio of 1:1:2:2 at 0.93, 1.25,
1.01, and 1.27 ppm, and methoxy protons as three singlet peaks
in a ratio of 1:2:2 at 2.75, 2.46, and 3.27 ppm. It is also well-
known that bridging methylene carbon (Ar-CH2-Ar) reso-
nances appear at ca. 31 ppm when two adjacent aryl rings are in
the syn orientation, and ca. 37 ppm in the anti orientation.16,17
Actually, the bridging methylene carbon resonances of 1b
appeared around 31 ppm (30.45, 30.64, and 30.70 ppm) not
around 37 ppm, indicating the cone conformation with all the
adjacent aryl rings in syn orientation. The phosphine 1a as well
Scheme 2. Synthetic route of 1a-1c and 2a-2c.
Figure 1. ORTEP drawing of 6a. Hydrogen atoms were
omitted for clarity.
(6a-6c). The reduction of 6a-6c with PhSiH3 in toluene
under reflux afforded the desired phosphines 1a-1c in good
yields. The phosphinocalix[6]arenes without the tert-butyl
groups (2a-2c) were also synthesized by the same procedure
using 412 and 5a-5c via the corresponding phosphine oxides
(7a-7c). These new compounds (6a and 6b, 7a-7c, 1a and 1b,
and 2a-2c) were fully characterized by elemental analysis, HR-
ESI-MS, and NMR spectra.
Single crystals of 6a suitable for X-ray diffraction study
were obtained. The crystal structure shows that 6a adopts a
1,2,3-alternate conformation in which three pairs of diametri-
cally opposite phenyl rings (A-D, B-E, and C-F) orient in anti
position to each other (Figure 1). In the crystal structure, four
aromatic rings (A, C, D, and F) stand up as the pinched
positions whereas the other two aromatic rings (B and E)
splay outwards as the flattened positions. The dihedral angles
between the aromatic ring (A-F) and the calixarene reference
plane (an average plane defined by the six bridging methylene
carbon atoms: the maximum deviation is 0.172 ¡) are 66.7,
40.1, 83.3, 108.2, 38.6, and 82.1° for A-F, respectively.
1
as oxides 6a and 6b showed the same characteristic H and
13C NMR spectra. Thus, these NMR data clearly indicated that
1a and 1b and 6a and 6b adopt the cone conformation6,16-18 in
solution.
Calix[6]arenes without the tert-butyl groups at the upper rim
are more flexible due to easy ring inversions19 than analogs
with the tert-butyl moiety.20 Actually, in the 1H NMR spectrum
of 2b the bridging methylene proton resonances appeared as
three singlet peaks at 3.89, 3.92, and 3.97 ppm in a 1:1:1 ratio
(Figure 2b). In addition, the methoxy protons also appeared as
three singlet peaks at 3.16, 2.89, and 3.22 ppm in a ratio of
1:2:2. All these singlet resonances remained singlets over the
temperature range from room temperature to ¹60 °C, although
some signals slightly broadened at the low temperature. These
results suggest that 2b has very flexible structure in solution.
The phosphines 2a and 2c as well as their phosphine oxides
7a-7c also show similar spectra, indicating they also have
flexible structures.

T. Fujihara et al.
Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009) 1189
Figure 3. Conformers and optimized structures (B3LYP/LANL2DZ-CONFLEX5/MMFF94s) of 1a and 1b and 2a-2c.
Conformation Analysis of Calix[6]arene Ring.
The
force field.22 These structures thus obtained were further
optimized by DFT calculation at B3LYP23/LANL2DZ24 level.
Figure 3 shows the optimized structures of the cone and the
1,2,3-alternate conformations for 1a and 1b and 2a-2c. For 1a,
1b, and 1c6 bearing the tert-butyl groups (R = t-Bu), the cone
conformations are more stable than the 1,2,3-alternate by 0.93,
NMR study suggested that 1a-1c and 6a-6c have cone
conformations in solution. In contrast, 2a-2c and 7a-7c have
very flexible structures in solution due to ring inversion. In
order to obtain further insight into the structures of calix[6]-
arene moieties, conformation analysis of 1 and 2 by theoretical
calculations were carried out for the cone and the 1,2,3-
alternate conformers. In each conformation, the lowest energy
structures were found with CONFLEX521 using a MMFF94s
¹1
1.39, and 0.96 kcal mol (1 kcal mol¹1 = 4.184 kJ mol¹1), re-
spectively (Table 1, Entries 1-3). These calculation data are
1
consistent with the H NMR spectra which indicate the cone

1190 Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009)
Monophosphinocalix[6]arenes
Table 1. Energy Difference (¦E) between 1,2,3-Alternate
and Cone Conformationsa)
arene moiety on the phosphine core may affect the activity
due to its bulkiness. On the other hand, the regioselectivity
of the linear and branch products was not affected by the
phosphine ligands as listed in Table 2, suggesting the bulkiness
and rigidity of calix[6]arene is not be enough to control the
selectivity under the present reaction conditions.
¹1 a),b)
Entry Phosphine Stable conformation ¦E/kcal mol
1
2
3
4
5
6
1a
1b
1c
2a
2b
2c
Cone
Cone
Cone
Cone
1,2,3-Alternate
1,2,3-Alternate
0.93
1.39
0.96c)
2.19
Conclusion
¹2.16
¹0.65
Novel
mono-O-(diphenylphosphinobenzyl)calix[6]arenes
with tert-butyl groups at the upper rim (1) and without the
tert-butyl moieties (2) were synthesized and fully character-
ized. The X-ray crystal structure analysis of 6a showed that the
phosphine oxide analog of 1a with tert-butyl moieties adapted
the 1,2,3-alternate conformation. The NMR study indicated
that, in solution, 1 and the corresponding phosphine oxides
with the tert-butyl groups at the upper rim (6) had the cone
conformation, whereas 2 and the corresponding phosphine
oxide (7) without the tert-butyl moieties were very flexible.
Studies of application to transition-metal-catalyzed reactions
are in progress.
a) Energy difference (¦E) = E(1,2,3-alternate) ¹ E(cone).
b) DFT calculation (B3LYP/LANL2DZ). c) See Ref. 6.
Table 2. Rh-Catalyzed Hydroformylation of 1-Hexenea)
[Rh(COD) ]BF (0.5 mol%)
2
4
Phosphine (2.0 mol%)
CO : H (1 : 1, 10 atm)
CHO
2
CHO
C H
C H
4
9
4
9
C H
benzene, 70 °C, 16 h
4
9
linear
branch
Entry
Ligand
Yield/%b) (linear:branch)
1
2
3
4
5
6
7
1a
1b
1c
2a
2b
2c
94 (63:37)
70 (72:28)
85 (71:29)
81 (67:33)
89 (70:30)
82 (60:40)
46 (73:27)
Experimental
General.
All reactions were performed under argon
using standard Schlenk techniques. Solvents were dried and
purified before use by usual methods. 5,11,17,23,29,35-Hexa-
tert-butyl-38,39,40,41,42-pentamethoxycalix[6]arene-37-ol (3),11
38,39,40,41,42-pentamethoxycalix[6]arene-37-ol (4),12 5,11,17,-
23,29,35-hexa-tert-butyl-37-(4-diphenylphosphinoylbenzyloxy)-
38,39,40,41,42-pentamethoxycalix[6]arene (6c),6 and 5,11,17,23,-
29,35-hexa-tert-butyl-37-(4-diphenylphosphinobenzyloxy)-38,39,-
40,41,42-pentamethoxycalix[6]arene (1c)6 were also prepared
according to literature procedures. Medium-pressure column
chromatography (Yamazen YFLC-540) was performed on silica
gel (Wakogel C-400HG; particle size 20-40 ¯m) with a UV
detector (Yamazen UV-10V). Preparative-scale GPC was carried
out with a Japan Analytical Industry LC-9104 instrument. 1H
(400 MHz), 13C{1H} (100 MHz), and 31P{1H} NMR (162 MHz)
spectra were recorded with a JEOL ECX-400 instrument. The
1H NMR spectroscopic data are referenced relative to residual
protonated solvent (7.26 ppm in CDCl3). 13C NMR chemical shifts
are reported relative to CDCl3 (77.0 ppm). The 31P NMR spectro-
scopic data are given relative to external 85% H3PO4. ESI mass
spectra were recorded with a JEOL JMS-SX102A instrument at the
GC-MS & NMR Laboratory of the Faculty of Agriculture at
Hokkaido University. Elemental analysis and HR-ESI-MS were
performed at the Center for Instrumental Analysis of Hokkaido
University.
5,11,17,23,29,35-Hexa-tert-butyl-37-(2-diphenylphosphinoyl-
benzyloxy)-38,39,40,41,42-pentamethoxycalix[6]arene (6a). 2-
Diphenylphosphinoylbenzyl bromide (5a: 1.90 g, 5.1 mmol) was
added to a suspension of 3 (1.40 g, 1.3 mmol) and NaH (106 mg,
2.7 mmol) in DMF (30 mL). The reaction mixture was stirred at
50 °C for 20 h. After cooling to room temperature, the unreacted
NaH was slowly quenched by adding MeOH and H2O. The crude
product was extracted with Et2O/toluene (3:1) and the organic
layer was dried over MgSO4. After filtration, the solvent was
removed in vacuo. Purification was performed with preparative
GPC. Remove of volatiles gave an analytically pure product as
pale-yellow solids (1.75 g, 97%). Anal. Calcd for C90H109O7P¢
CHCl3: C, 75.21; H, 7.63%. Found: C, 74.83; H, 7.90%. HR-ESI-
MS m/z calcd for [M + Na]+: 1355.7809; found: 1355.7812.
PPh3
a) 1-Hexene (1.0 mmol), [Rh(COD)2](BF4) (0.005 mmol),
phosphine (0.02 mmol), CO/H2 (1:1, 10 atom), benzene
(1.0 mL), 70 °C, 16 h. b) Yield based on the GC internal
standard technique.
conformations are dominant in solution. On the other hand,
2a-2c have very flexible structures due to the fast ring
inversion.19 For these flexible 2a-2c, the cone conformer
¹1
is more stable for 2a by 2.19 kcal mol (Entry 4), while the
1,2,3-alternate conformers are more stable for 2b and 2c
(Entries 5 and 6). Since these conformers were not observed by
the 1H NMR spectra of 2 measured at low temperature, the
energy barrier of the ring inversion would be very small. As for
the orientation of diphenylphosphino groups, it is interesting
that the lone pair on the phosphorus atoms of the ortho
derivatives (1a and 2a) point to the calix[6]arene moieties in
the lowest energy cone conformation (Figures 3a and 3e).
Catalysis. In order to investigate the efficacy of 1a-1c and
2a-2c as a ligand in catalysis, the Rh-catalyzed hydrofor-
mylation25,26 of 1-hexene was carried out. The reaction was
performed with a 1:1 mixture of CO/H2 gas (10 atm) in the
presence of a catalytic amount of [Rh(COD)2]BF4 combined
with 1a-1c or 2a-2c (P/Rh = 4) in benzene at 70 °C (Table 2).
Among the phosphine employed, 1a was found to be the most
effective ligand to afford a mixture of 1-heptanal (linear) and
2-methylhexanal (branch) in 94% total yield (Entry 1). The
phosphinocalix[6]arenes 1b and 1c provided the products in 70
and 85% yields, respectively (Entries 2 and 3). The phosphine
without the tert-butyl group 2a-2c also gave the products in
81%, 89%, and 82% yields, respectively (Entries 4-6). Under
the present conditions, PPh3 as the ligand was less effective
(46% yield, Entry 7). These results indicate that the calix[6]-

T. Fujihara et al.
Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009) 1191
1H NMR (CDCl3): ¤ 0.98 (s, 18H), 1.14 (s, 9H), 1.28 (s, 9H),
5,11,17,23,29,35-Hexa-tert-butyl-37-(3-diphenylphosphino-
1.30 (s, 18H), 2.34 (s, 6H, OCH3), 2.71 (s, 3H, OCH3), 3.03 (d,
benzyloxy-38,39,40,41,42-pentamethoxycalix[6]arene
(1b).
2
2H, ArCH2Ar, JH,H = 15 Hz), 3.34 (s, 6H, OCH3), 3.65 (d, 2H,
The compound was synthesized with 6b (0.65 g, 0.49 mmol) and
PhSiH3 (1.8 mL, 15 mmol) by a method similar to that used for
1a. White solids were obtained (0.59 g, 90%). HR-ESI-MS m/z
calcd for [C90H109O6P + Na]+: 1339.7860; found: 1339.7844.
1H NMR (CDCl3): ¤ 0.93 (s, 9H), 1.01 (s, 18H), 1.25 (s, 9H),
1.27 (s, 18H), 2.46 (s, 6H, OCH3), 2.75 (s, 3H, OCH3), 3.27 (s,
2
2
ArCH2Ar, JH,H = 15 Hz), 3.80 (d, 2H, ArCH2Ar, JH,H = 15 Hz),
2
3.95 (br.s, 2H, ArCH2Ar), 4.08 (d, 2H, ArCH2Ar, JH,H = 15 Hz),
4.20 (d, 2H, ArCH2Ar, JH,H = 15 Hz), 5.10 (s, 2H), 6.71 (s, 2H),
2
6.78 (s, 2H), 6.85 (s, 2H), 7.00 (s, 3H), 7.10 (br.s, 3H), 7.16 (s,
1H), 7.45 (br.s, 6H), 7.62 (br.s, 6H), 8.27 (br.s, 1H); 13C{1H} NMR
(CDCl3): ¤ 29.92, 30.56, 30.65, 31.26, 31.37, 31.50, 31.65, 34.14,
34.21, 34.26, 59.96, 60.04, 60.18, 71.30, 124.09, 124.89, 126.05,
2
6H, OCH3), 3.42 (d, 2H, ArCH2Ar, JH,H = 15 Hz), 3.67 (d, 2H,
2
2
ArCH2Ar, JH,H = 15 Hz), 3.80 (d, 2H, ArCH2Ar, JH,H = 15 Hz),
4.08 (d, 2H, ArCH2Ar, 2JH,H = 15 Hz), 4.20 (d, 2H, ArCH2Ar,
2JH,H = 15 Hz), 4.38 (d, 2H, ArCH2Ar, 2JH,H = 15 Hz), 4.84 (s,
2H), 6.82 (s, 2H), 6.83 (s, 2H), 6.89 (s, 2H), 7.11 (s, 2H), 7.13 (s,
2H), 7.20 (s, 2H), 7.25-7.34 (m, 11H), 7.37 (t, 1H, J = 10 Hz),
7.42 (d, 1H, J = 8 Hz), 7.58 (d, 1H, J = 8 Hz); 13C{1H} NMR
(CDCl3): ¤ 30.45, 30.64, 30.70, 31.31, 31.40, 31.59, 31.63, 34.15,
34.25, 59.94, 60.00, 60.13, 74.44, 124.48, 124.95, 125.14, 126.92,
3
126.56, 126.92, 127.15, 127.81, 128.73 (d, JP,C = 11 Hz), 132.02
(d, 3JP,C = 12 Hz), 132.17, 132.71, 132.84, 132.99, 133.24, 133.27,
133.60 (d, 2JP,C = 13 Hz), 133.79 (d, 2JP,C = 12 Hz), 143.80,
143.86, 145.64, 145.72, 145.76, 146.00, 151.37, 153.52, 153.95,
154.40; 31P{1H} NMR (CDCl3): ¤ 32.9.
5,11,17,23,29,35-Hexa-tert-butyl-37-(2-diphenylphosphino-
benzyloxy)-38,39,40,41,42-pentamethoxycalix[6]arene (1a).
A
2
solution of 6a (1.70 g, 1.3 mmol) in toluene (25 mL) was refluxed
in the presence of PhSiH3 (4.7 mL, 38 mmol) for 2 d. The solvent
was then removed under reduced pressure and the residue
dissolved in CH2Cl2 (ca. 2 mL). Reprecipitation with MeOH
afforded the product as white solids. An analytically pure
product was obtained by recrystallization from CH2Cl2/MeOH
(2:5). White solids were obtained (1.04 g, 62%). Anal. Calcd for
C90H109O6P¢CH3OH: C, 80.97; H, 8.44%. Found: C, 80.99; H,
8.48%. HR-ESI-MS m/z calcd for [M + Na]+: 1339.7860; found:
127.01, 127.48, 128.58 (d, JP,C = 7 Hz), 128.78, 133.20, 133.26,
2
133.31, 133.43, 133.69 (d, JP,C = 8 Hz), 133.93, 137.10, 137.22,
138.10, 138.18, 145.72, 145.74, 145.96; 31P{1H} NMR (CDCl3):
¤ ¹4.79.
37-(2-Diphenylphosphinoylbenzyloxy)-38,39,40,41,42-penta-
methoxycalix[6]arene (7a). The compound was synthesized with
5a (1.18 g, 3.2 mmol) and 4 (1.87 g, 2.7 mmol) by a method similar
to that used for 6a. Pale-yellow solids were obtained (1.37 g, 52%).
HR-ESI-MS m/z calcd for [C66H61O7P + Na]+: 1020.1499; found:
1
1
1339.7833. H NMR (CDCl3): ¤ 1.00 (s, 18H), 1.13 (s, 9H), 1.26
1019.4050. H NMR (CDCl3): ¤ 2.75 (s, 6H, OCH3), 3.24 (s, 9H,
(s, 9H), 1.27 (s, 18H), 2.40 (s, 6H, OCH3), 2.73 (s, 3H, OCH3),
OCH3), 3.59 (s, 4H, ArCH2Ar), 3.89 (s, 4H, ArCH2Ar), 3.96 (s,
4H, ArCH2Ar), 5.22 (s, 2H), 6.68-6.73 (m, 3H), 6.80-6.83 (m,
4H), 6.89 (t, 2H, J = 8 Hz), 6.94-7.02 (m, 10H), 7.44 (br.t, 4H,
J = 8 Hz), 7.51 (t, 2H, J = 7 Hz), 7.57-7.64 (m, 6H), 8.11 (m, 1H);
13C{1H} NMR (CDCl3): ¤ 29.86, 30.30, 30.39, 60.08, 60.15,
60.48, 71.86, 123.30, 123.48, 123.54, 123.90, 127.72, 128.61,
128.75 (d, 3JP,C = 11 Hz), 128.88, 129.26, 129.52, 130.26, 132.09,
132.14, 132.18, 132.67, 134.39, 134.45, 134.59, 134.74, 153.83,
156.17, 156.43, 156.70; 31P{1H} NMR (CDCl3): ¤ 32.9.
2
3.27 (s, 6H, OCH3), 3.35 (d, 2H, ArCH2Ar, JH,H = 15 Hz), 3.67
2
2
(d, 2H, ArCH2Ar, JH,H = 15 Hz), 3.83 (d, 2H, ArCH2Ar, JH,H
=
15 Hz), 4.03 (d, 2H, ArCH2Ar, 2JH,H = 15 Hz), 4.16 (d, 2H,
2
2
ArCH2Ar, JH,H = 15 Hz), 4.32 (d, 2H, ArCH2Ar, JH,H = 15 Hz),
5.14 (s, 2H), 6.79 (s, 2H), 6.81 (s, 2H), 6.88 (s, 2H), 7.00 (s, 2H),
7.09-7.31 (m, 13H), 7.41 (t, 2H, J = 8 Hz), 7.62 (t, 1H, J = 8 Hz),
8.00 (m, 2H); 13C{1H} NMR (CDCl3): ¤ 30.50, 31.29, 31.39,
31.48, 31.62, 34.14, 34.20, 34.25, 59.90, 59.94, 126.87, 128.59 (d,
2JP,C = 8 Hz), 128.79, 133.20, 133.26, 133.43, 133.56, 133.71,
133.82, 133.92, 134.01, 136.03, 145.58, 154.50; 31P{1H} NMR
(CDCl3): ¤ ¹15.6.
37-(2-Diphenylphosphinobenzyloxy)-38,39,40,41,42-penta-
methoxycalix[6]arene (2a). The compound was synthesized with
7a (1.37 g, 1.4 mmol) and PhSiH3 (5.0 mL, 41 mmol) by a method
similar to that used for 1a. White solids were obtained (0.89 g,
66%). HR-ESI-MS m/z calcd for [C66H61O6P + Na]+: 1003.4103;
5,11,17,23,29,35-Hexa-tert-butyl-37-(3-diphenylphosphinoyl-
benzyloxy)-38,39,40,41,42-pentamethoxycalix[6]arene
(6b).
1
The compound was synthesized with 3 (1.0 g, 1.0 mmol) and 3-
diphenylphosphinoylbenzyl bromide (5b, 0.35 g, 1.4 mmol) by a
method similar to that used for 6a. Pale-yellow solids were
obtained (1.1 g, 88%). Anal. Calcd for C90H109O7P¢CHCl3: C,
75.21; H, 7.63%. Found: C, 75.00; H, 7.85%. HR-ESI-MS m/z
calcd for [M + Na]+: 1355.7809; found: 1355.7806. 1H NMR
(CDCl3): ¤ 0.92 (s, 9H), 0.98 (s, 18H), 1.25 (s, 9H), 1.26 (s, 18H),
2.42 (s, 6H, OCH3), 2.71 (s, 3H, OCH3), 3.30 (s, 6H, OCH3), 3.39
found: 1003.4113. H NMR (CDCl3): ¤ 2.82 (s, 6H, OCH3), 3.20
(s, 6H, OCH3), 3.24 (s, 3H, OCH3), 3.85 (s, 4H, ArCH2Ar), 3.91
(s, 4H, ArCH2Ar), 3.97 (s, 4H, ArCH2Ar), 5.13 (s, 2H), 6.72
(t, 1H, J = 8 Hz), 6.78-7.31 (m, 29H), 7.39 (t, 1H, J = 7 Hz), 7.84
(m, 1H); 13C{1H} NMR (CDCl3): ¤ 30.30, 30.38, 60.11, 60.45,
72.40, 123.35, 123.51, 123.82, 127.21, 127.67, 127.84, 128.69 (d,
2JP,C = 6 Hz), 128.91, 128.98, 129.16, 129.31, 129.54, 130.14,
2
133.02, 133.91, 134.05, 134.46, 134.56 (d, JP,C = 9 Hz), 134.77,
2
2
(d, 2H, ArCH2Ar, JH,H = 15 Hz), 3.62 (d, 2H, ArCH2Ar, JH,H
=
134.84, 136.19, 154.37, 156.24, 156.42, 156.72; 31P{1H} NMR
(CDCl3): ¤ ¹15.8.
15 Hz), 3.75 (d, 2H, ArCH2Ar, 2JH,H = 15 Hz), 4.13 (d, 2H,
2
2
ArCH2Ar, JH,H = 15 Hz), 4.21 (d, 2H, ArCH2Ar, JH,H = 15 Hz),
4.37 (d, 2H, ArCH2Ar, 2JH,H = 15 Hz), 4.90 (s, 2H), 6.80 (br.s,
2H), 6.81 (s, 2H), 6.86 (br.s, 3H), 7.10 (br.s, 2H), 7.13 (s, 2H), 7.18
(br.s, 2H), 7.39 (br.t, 4H, J = 7.8 Hz), 7.48 (br.t, 3H, J = 6.0 Hz),
7.64-7.70 (m, 4H), 7.78 (d, 1H, J = 5.0 Hz), 7.80 (s, 1H);
13C{1H} NMR (CDCl3): ¤ 30.32, 30.43, 30.53, 31.27, 31.36,
31.62, 34.14, 34.25, 59.97, 60.13, 73.86, 124.50, 124.85, 124.98,
126.95, 127.12, 127.42, 128.53, 128.65, 131.98 (d, 2JP,C = 11 Hz),
132.12, 132.23, 133.10 (d, 2JP,C = 11 Hz), 133.28, 133.38, 133.65,
133.78, 145.73, 145.79, 153.52, 154.37; 31P{1H} NMR (CDCl3):
¤ 29.6.
37-(3-Diphenylphosphinoylbenzyloxy)-38,39,40,41,42-penta-
methoxycalix[6]arene (7b). The compound was synthesized with
5b (0.13 g, 0.35 mmol) and 4 (0.21 g, 0.29 mmol) by a method
similar to that used for 6a. Pale-yellow solids were obtained
(0.33 g, 95%). Anal. Calcd for C66H61O7P¢CHCl3¢MeOH: C,
71.11; H, 5.79%. Found: C, 71.03; H, 5.64%. HR-ESI-MS m/z
calcd for [M + Na]+: 1020.1499; found: 1019.4043. 1H NMR
(CDCl3): ¤ 2.89 (s, 6H, OCH3), 3.16 (s, 3H, OCH3), 3.22 (s, 6H,
OCH3), 3.89 (s, 4H, ArCH2Ar), 3.92 (s, 4H, ArCH2Ar), 3.97 (s,
4H, ArCH2Ar), 4.79 (s, 2H), 6.76-7.05 (m, 20H), 7.37 (br.t, 4H
J = 4 Hz), 7.43-7.49 (m, 2H), 7.54 (d, 1H, J = 8 Hz), 7.66-7.79

1192 Bull. Chem. Soc. Jpn. Vol. 82, No. 9 (2009)
Monophosphinocalix[6]arenes
(m, 4H), 7.77 (d, 1H, J = 12 Hz); 13C{1H} NMR (CDCl3): ¤ 30.26,
30.47, 30.67, 60.11, 60.17, 60.38, 74.17, 128.38, 128.57, 128.69,
128.86, 128.93, 129.34, 129.68, 129.86, 131.19 (d, 3JP,C = 11 Hz),
131.65 (d, 3JP,C = 11 Hz), 132.15 (d, 2JP,C = 11 Hz), 133.12,
133.25, 134.36, 134.48, 134.61, 134.77, 138.29 (d, 3JP,C = 12 Hz),
154.22, 156.21, 156.54, 156.64; 31P{1H} NMR (CDCl3): ¤ 29.5.
37-(3-Diphenylphosphinobenzyloxy)-38,39,40,41,42-penta-
hydrogen atoms were located on the calculated positions and not
refined. All calculations were performed using the CrystalStructure
software package. Crystal data for 6a¢0.5C2H4Cl2¢0.5CH3OH¢
0.5H2O: C94.5H114ClO7P, Mr = 1428.36, T = 153 K, triclinic,
ꢀ
space group P1 (No. 2), a = 11.569(2), b = 14.136(14), c =
26.665(18) ¡, ¡ = 81.21(1)°, ¢ = 89.21(9)°, £ = 83.26(13)°,
¹1
U = 4280(5) ¡3, Z = 2, ®(Mo K¡) = 1.15 cm
,
observed
methoxycalix[6]arene (2b).
The compound was synthesized
reflections 8888 (I > 3·(I)), R, Rw = 0.101, 0.231 (I > 3·(I)).
Crystallographic data have been deposited with Cambridge
Crystallographic Data Centre: Deposition number CCDC-697714
for compound 6a. Copies of the data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html (or from
the Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge, CB2 1EZ, U.K.; Fax:+44 1223 336033; e-mail:
deposit@ccdc.cam.ac.uk).
Theoretical Calculation. Molecular-orbital calculations were
performed with the Gaussian 03 program28 on a HIT HPC-IA642/
SS 1.3/3D-4G. Conformation analysis of each conformer was
performed with CONFLEX521 program using MMFF94s22 as
a force field. DFT calculation was carried out at B3LYP23/
LANL2DZ24 level.
with 7b (0.12 g, 0.12 mmol) and PhSiH3 (0.43 mL, 3.5 mmol) by a
method similar to that used for 1a. White solids were obtained
(0.06 g, 52%). Anal. Calcd for C66H61O6P¢CH2Cl2¢MeOH: C,
74.37; H, 6.15%. Found: C, 74.43; H, 6.24%. HR-ESI-MS m/z
calcd for [M + Na]+: 1003.4103; found: 1003.4120. 1H NMR
(CDCl3): ¤ 2.90 (s, 6H, OCH3), 3.17 (s, 3H, OCH3), 3.24 (s,
6H, OCH3), 3.91 (s, 4H, ArCH2Ar), 3.95 (s, 4H, ArCH2Ar),
3.98 (s, 4H, ArCH2Ar), 4.76 (s, 2H), 6.79-7.43 (m, 32H);
13C{1H} NMR (CDCl3): ¤ 30.31, 30.45, 30.67, 60.11, 60.17,
2
60.39, 74.82, 123.48, 123.56, 123.85, 128.16, 128.63 (d, JP,C
=
2
7 Hz), 128.88 (d, JP,C = 8 Hz), 129.31, 129.70, 130.02, 133.35,
133.55, 133.73, 133.92, 134.50, 134.64, 134.75, 134.85, 137.09,
137.19, 137.41, 137.53, 137.92, 137.99, 154.30, 156.21, 156.53,
156.72; 31P{1H} NMR (CDCl3): ¤ ¹4.73.
37-(4-Diphenylphosphinoylbenzyloxy)-38,39,40,41,42-penta-
methoxycalix[6]arene (7c). The compound was synthesized with
4-diphenylphosphinoylbenzyl bromide (5c: 0.61 g, 1.64 mmol) and
4 (0.97 g, 1.37 mmol) by a method similar to that used for 6a. A
light-yellow solid was obtained. Yield: 0.9 g (66%). HR-ESI-MS
m/z calcd for [C66H61O7P + Na]+: 1020.1499; found: 1019.4055.
1H NMR (CDCl3): ¤ 2.87 (s, 3H, OCH3), 3.05 (s, 6H, OCH3), 3.24
(s, 6H, OCH3), 3.88 (s, 4H, ArCH2Ar), 3.89 (s, 4H, ArCH2Ar),
3.96 (s, 4H, ArCH2Ar), 4.50 (s, 2H), 6.68 (t, 2H, J = 8 Hz),
6.80 (d, 2H, J = 8 Hz), 6.85-6.88 (m, 6H), 6.94-7.01 (m, 8H),
7.33 (br.d, 2H, J = 7 Hz), 7.43 (br.t, 4H, J = 8 Hz), 7.53 (t, 2H,
J = 7 Hz), 7.57-7.60 (m, 2H), 7.64-7.67 (m, 4H); 13C{1H} NMR
(CDCl3): ¤ 30.33, 30.48, 60.11, 60.14, 60.20, 73.78, 123.39,
123.51, 123.60, 124.00, 127.61, 127.69, 128.57 (d, 3JP,C = 11 Hz),
128.80, 129.40, 129.46, 129.63, 131.94, 132.14, 132.20, 134.29,
134.45 (d, 2JP,C = 11 Hz), 134.58, 134.70, 134.77, 154.42, 156.15,
156.44, 156.60; 31P{1H} NMR (CDCl3): ¤ 29.5.
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37-(4-Diphenylphosphinobenzyloxy)-38,39,40,41,42-penta-
methoxycalix[6]arene (2c). The compound was synthesized with
7c (0.9 g, 0.9 mmol) and PhSiH3 (3.4 mL, 27 mmol) by a method
similar to that used for 1a. White solids were obtained (0.73 g,
82%). Anal. Calcd for C66H61O6P¢0.5CH2Cl2¢0.5MeOH: C,
77.40; H, 6.20%. Found: C, 77.58; H, 6.31%. HR-ESI-MS m/z
calcd for [M + Na]+: 1003.4103; found: 1003.4132. 1H NMR
(CDCl3): ¤ 3.00 (s, 3H, OCH3), 3.08 (s, 6H, OCH3), 3.32 (s, 6H,
OCH3), 3.99 (s, 8H, ArCH2Ar), 4.04 (s, 4H, ArCH2Ar), 4.64 (s,
2H), 6.78 (t, 2H, J = 8 Hz), 6.90-7.38 (m, 30H); 13C{1H} NMR
(CDCl3): ¤ 30.44, 30.54, 30.59, 60.21, 60.25, 60.28, 74.43,
4
a) L. Brandsma, S. F. Vasilevsky, H. D. Verkruijsse,
2
123.50, 123.57, 123.69, 123.94, 128.15 (d, JP,C = 7 Hz), 128.67
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2
(d, JP,C = 7 Hz), 128.76, 128.85, 129.51, 129.70, 129.74, 133.81,
133.94, 134.04, 134.41, 134.61, 134.72, 134.78, 134.91, 136.51,
136.58, 137.36, 137.43, 138.51, 154.60, 156.23, 156.64, 156.69;
31P{1H} NMR (CDCl3): ¤ ¹5.20.
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Rigaku/Saturn70 CCD diffractometer using graphite-monochro-
mated Mo K¡ radiation (- = 0.71070 ¡) at 153 K, and processed
using CrystalClear (Rigaku). The structures were solved by a direct
method (SIR9227) and refined by full-matrix least-square refine-
ment on F2. The non-hydrogen atoms, except one disordered t-butyl
group and solvated molecules, were refined anisotropically. All
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