Suzuki-Miyaura coupling on the three upper rims of hexahomotrioxacalix[3]arenes

Article abstract of DOI:10.1016/j.tet.2006.08.073

The efficient functionalization of three upper rims based on Suzuki-Miyaura coupling to temporarily lower rim-protected hexahomotrioxacalix[3]arenes was developed. After deprotection of the three protecting groups, the three upper rim-functionalized and l

Full text of DOI:10.1016/j.tet.2006.08.073

Tetrahedron 62 (2006) 10321–10324
Suzuki–Miyaura coupling on the three upper rims of
hexahomotrioxacalix[3]arenes
*
Kazunori Tsubaki, Masahide Sakakibara, Yuki Nakatani and Takeo Kawabata
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
Received 1 August 2006; revised 22 August 2006; accepted 24 August 2006
Available online 11 September 2006
Abstract—The efficient functionalization of three upper rims based on Suzuki–Miyaura coupling to temporarily lower rim-protected hexa-
homotrioxacalix[3]arenes was developed. After deprotection of the three protecting groups, the three upper rim-functionalized and lower
rim-free hexahomotrioxacalix[3]arenes 5a–5m were synthesized.
Ó 2006 Elsevier Ltd. All rights reserved.
1. Introduction
at one of the three upper rim aryl groups of hexahomotrioxa-
calix[3]arenes using the so-called ‘Mannich route’ in calix-
arene chemistry.3 However, the Mannich route is not suitable
for transformation of the three upper rims in one operation
because the yield of each reaction is around 50%. In this
paper, we report functionalization of the three upper rims
based on Suzuki–Miyaura coupling4 to temporarily lower
rim-protected hexahomotrioxacalix[3]arenes.
Hexahomotrioxacalix[3]arene is a member of the calixarene
family and has structural features of both a calixarene and an
18-crown-6 ether, having a cavity composed of a C3-sym-
metric 18-membered ring (similar to 18-crown-6 ether),
and also a three-dimensional cavity, which can adopt cone
and/or partial-cone conformations (by analogy with calixar-
enes).1 Hexahomotrioxacalix[3]arene skeleton having such
features would be expected to be a useful platform for selec-
tive and specific function or host–guest recognition proper-
ties. However, functionalization of the upper or lower rim
of hexahomotrioxacalix[3]arenes, especially the transforma-
tion of functional groups on the upper rim in the presence of
a phenolic hydroxy group on the lower rim, is quite difficult
due to structural weakness attributed to the combination of
three dibenzyletheral linkages and phenolic hydroxyl groups
(Fig. 1). To overcome these synthetic difficulties, we devel-
oped a stepwise construction of hexahomotrioxacalix[3]-
arenes based on cyclization of the corresponding linear
trimers2 as well as several functional group transformations
2. Results and discussion
Since there have been a few reports on the Suzuki–Miyaura
coupling of the three upper rims of lower rim-alkylated
hexahomotrioxacalix[3]arenes,5 we applied this coupling
to the mono-brominated hexahomotrioxacalix[3]arene 1.2a
First, we tried the modified Suzuki–Miyaura coupling
reported by Buchwald et al.6 on one of the three upper
rims of 1 (Scheme 1).
tBu
tBu
tBu
tBu
O
O
R2
R3
OH HO
OH
OH HO
OH
Upper rim
R2
O
R1
R3
O
O
O
O
OH HO
OH
51%
O
O
O
O
O
OH
OH
HO
Ph
2
Br
1
Lower rim
R1
Scheme 1. Conditions: (2-biphenyl) di-tert-butylphosphine, Pd(OAc)2, and
KF.
Figure 1. Hexahomotrioxacalix[3]arenes.
Hexahomotrioxacalix[3]arene with one bromine on the
upper rim 1 was reacted with 1.5 equiv of boric acid in the
presence of (2-biphenyl) di-tert-butylphosphine (10 mol %),
* Corresponding author. Tel.: +81 774 38 3191; fax: +81 774 38 3197;
e-mail: tsubaki@fos.kuicr.kyoto-u.ac.jp
0040–4020/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.08.073

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K. Tsubaki et al. / Tetrahedron 62 (2006) 10321–10324
palladium acetate (5 mol %), and potassium fluoride
(3 equiv) in THF at 50 ꢀC to give 2 in 51% yield. However,
our attempt to introduce three phenyl groups to the three
upper rims on 37 was not successful due to the formation
of inseparable and complicated product mixtures. Therefore,
we changed our synthetic strategy, so that active hydroxy
groups at the lower rim were temporarily protected by
methoxyethoxymethyl (MEM) groups (Scheme 2). Tribromo-
hexahomotrioxacalix[3]arene 3 was treated with 10 equiv
of MEMCl and sodium hydride in THF at room temperature
to give the desired 4 in 63% yield. Shinkai and co-workers
reported that ring-inversion of hexahomotrioxacalix[3]-
arenes took place through oxygen-through-the-annulus
rotation, and cone/partial-cone ring-inversion was inhibited
by introducing butyl and bulkier groups to the lower rim.8
Based on the results of 1H NMR, MEM-protected 4 is fixed
in a partial-cone conformation.
deprotection of the three MEM groups was successively
performed for concise purification of the lower rim-free
hexahomotrioxacalix[3]arenes 5, and the yields in Table 1
were calculated in two steps based on isolated 5. Since pro-
cedure A had milder reaction conditions, the combined
yields (74–90%) were generally higher than those using
procedure B (36–78%).
In summary, efficient functionalization of the three upper
rims of (lower rim-free) hexahomotrioxacalix[3]arenesbased
on Suzuki–Miyaura coupling was developed. We believe that
products 5a–5m, which have deep cavities and binding sites
on peripheral aromatic rings, will contribute to the field of
host–guest chemistry. In particular, further studies on prod-
ucts 5e and 5j with regard to fluorescence and complexation
with various guest molecules are now in progress.
3. Experimental
3.1. General
Ar
Ar
Br
Br
O
O
OH HO
OH
OR RO
OR
O
O
O
O
Nuclear magnetic resonance (NMR) spectra were taken at
200 or 300 MHz in CDCl3 with chemical shifts being
reported as d ppm from tetramethylsilane as an internal
standard and couplings are expressed in hertz. Preparative
TLC was carried out with silica gel 60 F254 plates (Merck).
(ii) procedure A or B
(iii) H+
Ar
Br
(i)
63%
3: R = H
4: R = CH2OC2H4OCH3
5a-m
3.2. Phenylhexahomotrioxacalix[3]arene 2
Scheme 2. Conditions: (i) MEMCl and NaH; (ii) procedure A: ArB(OH)2,
Pd(OAc)2, (2-biphenyl) di-tert-butylphosphine; procedure B: ArB(OH)2,
Pd(PPh3)4; (iii) 0.2 N HCl.
A mixture of 12a (50.0 mg, 0.083 mmol), phenylboric acid
(15.3 mg, 0.125 mmol), 2-(di-tert-butylphosphino)biphenyl
(3.0 mg, 0.008 mmol), and KF (14.6 mg, 0.25 mmol) was
heated with a heat gun under vacuum and flushed with argon.
A solution of palladium acetate (1.0 mg, 0.004 mmol) in dry
THF (1 ml) was added to the mixture and stirred overnight at
50 ꢀC. To the reaction mixture, 0.1 N aqueous hydrochloric
acid and EtOAc were added. The organic layer was sepa-
rated, and washed successively with water, aqueous sodium
carbonate solution, and brine. After being dried over sodium
sulfate, the solvent was evaporated in vacuo. The residue was
purified by PTLC to furnish pure 2 (25.4 mg) in 51% yield.
Mp¼118–120 ꢀC; IR (KBr) 3348, 2957, 1611, 1486,
Suzuki–Miyaura coupling of the three upper rims of lower
rim-protected 4 was investigated. Among the several proce-
dures reported on modified Suzuki–Miyaura coupling,5 two
procedures (procedures A and B; see Section 3 and Table 1)
were suitable for introducing aromatic rings to the three
upper rims of MEM-protected 4. Procedure A was suitable
for para-substituted boric acids (entries 1–4), and procedure
B was suitable for boric acids possessing a strong electron-
withdrawing group and/or ortho-substitution (entries 5–
13). After a coupling reaction through procedure A or B,
1
1361 cmꢁ1; H NMR (200 MHz, CDCl3) d 1.25 (s, 18H),
Table 1. Suzuki–Miyaura coupling on the three upper rims of hexahomo-
trioxacalix[3]arenes 4
4.74 (s, 4H), 4.75 (s, 4H), 4.76 (s, 4H), 7.14 (s, 4H), 7.20–
7.50 (m, 5H), 7.35 (s, 2H), 8.58 (s, 2H), 8.87 (s, 1H);
HRMS (EI+) calcd for C38H44O6 (M+): 596.3138. Found:
596.3145. Anal. Calcd for C38H44O6$0.5H2O: C, 75.34; H,
7.49. Found: C, 75.03; H, 7.37.
Entry
Ar
Product
Procedurea
Yield (%)b
1
2
3
4
5
6
7
8
Ph
5a9
5b
5c
5d
5e
5f
5g
5h
5i
A
A
A
A
B
B
B
B
B
B
B
B
B
77
90
89
74
36
59
62
78
67
63
43
50
60
p-Me–C6H4
p-MeO–C6H4
p-F–C6H4
3.3. MEM-protected hexahomotrioxacalix[3]arene 4
o-NC–C6H4
p-CHO–C6H4
p-O2N–C6H4
o-MeO–C6H4
o-HO–C6H4
o-EtO2C–C6H4
o-MeCONH–C6H4
3-Pyridinyl
4-Pyridinyl
To a solution of 37 (33.9 mg, 0.053 mmol) in THF (3 ml)
were added sodium hydride (28.3 mg, 0.71 mmol, 60% oil
dispersion in mineral oil) and 2-methoxyethoxymethyl chlo-
ride (60 ml, 0.53 mmol), and the mixture was stirred for 5 h
at room temperature. Aqueous ammonium chloride solution
and EtOAc were added to the reaction mixture. The organic
layer was separated, and washed successively with water,
sodium hydrogen carbonate solution, and brine. After being
dried over sodium sulfate, the solvent was evaporated
in vacuo. The residue was purified by PTLC (hexane/
EtOAc¼2/3) to give 4 as a colorless oil (29.9 mg, 63%
9c
10
11c
12
13
5j
5k
5l
5m
a
Procedure A: ArB(OH)2 (10 equiv), Pd(OAc)2 (10 mol %), (2-biphenyl)
di-tert-butylphosphine (20 mol %), rt, 2 days. Procedure B: ArB(OH)2
(10 equiv), Pd(PPh3)4 (20 mol %), 80 ꢀC, 6–19 h.
Isolated yield.
b
c
Corresponding pinacol ester of boric acid was used.

K. Tsubaki et al. / Tetrahedron 62 (2006) 10321–10324
10323
yield). IR (film) 2876, 1579, 1454, 1361, 1200 cmꢁ1; H
NMR (200 MHz, CDCl3) d 3.17–3.20 (m, 2H), 3.32–3.36
(m, 2H), 3.36 (s, 9H), 3.46–3.51 (m, 4H), 3.67–3.72
(m, 4H), 4.17 (s, 2H), 4.19 (d, J¼10.3 Hz, 2H), 4.20 (d, J¼
12.8 Hz, 2H), 4.32 (d, J¼11.2 Hz, 2H), 4.39 (d,
J¼11.4 Hz, 2H), 4.62 (d, J¼11.2 Hz, 2H), 4.68 (d,
J¼11.2 Hz, 2H), 4.85 (s, 4H), 7.37 (d, J¼2.4 Hz, 2H), 7.41
(d, J¼2.4 Hz, 2H), 7.47 (s, 2H); HRMS (FAB+) calcd for
C36H45O1279Br3Na (M+Na+): 929.0359. Found: 929.0380,
calcd for C36H45O1279Br281BrNa (M+Na+): 931.1034. Found:
931.0357, calcd for C36H45O1279Br81Br2Na (M+Na+):
933.0318. Found: 933.0338, calcd for C36H45O1281Br3Na
(M+Na+): 935.0298. Found: 935.0320. Anal. Calcd for
C36H45O12Br3$H2O: C, 46.62; H, 5.11. Found: C, 46.37;
H, 4.83.
690.2219. Anal. Calcd for C42H33F3O6$H2O: C, 71.18; H,
4.98. Found: C, 71.37; H, 4.82.
1
3.5. Procedure B for the synthesis of compounds 5e–5m
The synthesis of 5e is typical. A solution of 4 (57.6 mg,
0.063 mmol), 2-cyanophenylboric acid (93.1 mg, 0.63 mmol),
Pd(PPh3)4 (14.6 mg, 0.013 mmol), and 2 M aqueous sodium
carbonate (0.38 ml) in toluene (2 ml) and methanol (2 ml)
was stirred for 17 h at 80 ꢀC under an Ar atmosphere. Water
and EtOAc were added to the reaction mixture. The organic
layer was separated, and washed successively with 0.1 N
aqueous hydrochloric acid, water (twice), and brine. After
being dried over sodium sulfate, the solvent was evaporated
in vacuo. The residue was dissolved in EtOAc (10 ml) and
4 N hydrogen chloride in EtOAc (0.5 ml) was added to
the solution and stirred overnight. The reaction mixture
was poured into a mixture of ethyl acetate and water. The
organic layer was separated, washed successively with
water (twice) and brine, dried over Na2SO4, and evaporated
in vacuo to give a pale yellow viscous oil. The residue was
purified by PTLC (CHCl3/EtOAc¼20/1) to furnish pure 5e
(16.3 mg).
3.4. Procedure A for the synthesis of compounds 5a–5d
The synthesis of 5a is typical. A solution of 4 (35.3 mg,
0.039 mmol), phenylboric acid (47.3 mg, 0.388 mmol),
2-(di-tert-butylphosphino)biphenyl (1.7 mg, 0.008 mmol),
palladium acetate (0.9 mg, 0.004 mmol) in degassed toluene
(2 ml), and 2 M aqueous sodium carbonate (0.23 ml) was
stirred for 2 days at room temperature under an Ar
atmosphere. Water and EtOAc were added to the reaction
mixture. The organic layer was separated, and washed
successively with 0.1 N aqueous hydrochloric acid, water
(twice), and brine. After being dried over sodium sulfate,
the solvent was evaporated in vacuo. The residue was dis-
solved in EtOAc (10 ml) and 4 N hydrogen chloride in
EtOAc (0.5 ml) was added to the solution and stirred over-
night. The reaction mixture was poured into a mixture of
ethyl acetate and water. The organic layer was separated,
washed successively with water (twice) and brine, dried
over Na2SO4, and evaporated in vacuo to give a pale yellow
viscous oil. The residue was purified by PTLC (CHCl3/
hexane¼3/1) to furnish pure 5a (19.0 mg) in 77% yield.
3.5.1. Hexahomotrioxacalix[3]arene 5e. Mp¼145–
148 ꢀC; IR (KBr) 3340, 2223, 1612, 1473, 1362 cmꢁ1
;
1H NMR (200 MHz, CDCl3) d 4.83 (s, 12H), 7.36 (s, 6H),
7.36–7.45 (m, 6H), 7.56–7.63 (m, 3H), 7.72 (d, J¼7.6 Hz,
3H), 9.01 (s, 3H); HRMS (FAB+) calcd for C45H34N3O6
(M+H+): 712.2447. Found: 712.2444. Anal. Calcd for
C45H33N3O6$0.5CHCl3: C, 70.84; H, 4.38; N, 5.45. Found:
C, 70.84; H, 4.69; N, 5.11.
3.5.2. Hexahomotrioxacalix[3]arene 5f. Mp¼157–159 ꢀC;
1
IR (KBr) 3340, 1696, 1602, 1480, 1388 cmꢁ1; H NMR
(200 MHz, CDCl3) d 4.85 (s, 12H), 7.45 (s, 6H), 7.87 (d,
J¼8.0 Hz, 6H), 7.92 (d, J¼8.0 Hz, 6H), 8.95 (s, 3H),
10.03 (s, 3H); HRMS (FAB+) calcd for C45H36O9 (M+):
720.2359. Found: 720.2347. Anal. Calcd for C45H36O9$1/
3CHCl3: C, 71.59; H, 4.82. Found: C, 71.91; H, 5.04.
3.4.1. Hexahomotrioxacalix[3]arene 5a. Known.9
3.4.2. Hexahomotrioxacalix[3]arene 5b. Mp¼229–
1
231 ꢀC; IR (KBr) 3361, 1611, 1479, 1361, 1193 cmꢁ1; H
3.5.3. Hexahomotrioxacalix[3]arene 5g. Mp¼236–
NMR (200 MHz, CDCl3) d 2.37 (s, 9H), 4.81 (s, 12H),
7.20 (d, J¼8.2 Hz, 6H), 7.35 (s, 6H), 7.39 (d, J¼8.2 Hz,
6H), 8.83 (s, 3H); HRMS (FAB+) calcd for C45H42O6
(M+): 678.2981. Found: 678.2989. Anal. Calcd for
C45H42O6$0.5H2O: C, 78.58; H, 6.30. Found: C, 78.37;
H, 6.24.
238 ꢀC; IR (KBr) 3340, 1595, 1514, 1476, 1343 cmꢁ1
;
1H NMR (200 MHz, CDCl3) d 4.86 (s, 12H), 7.44 (s, 6H),
7.65 (d, J¼8.6 Hz, 6H), 8.27 (d, J¼8.6 Hz, 6H), 8.97 (s,
3H); HRMS (FAB+) calcd for C42H33N3O12Na (M+Na+):
794.1962. Found: 794.1944. Anal. Calcd for
C42H33N3O12$CHCl3: C, 57.96; H, 3.85; N, 4.72. Found:
C, 57.75; H, 3.89; N, 4.54.
3.4.3. Hexahomotrioxacalix[3]arene 5c. Mp¼134–
1
136 ꢀC; IR (KBr) 3347, 1609, 1519, 1360, 1181 cmꢁ1; H
3.5.4. Hexahomotrioxacalix[3]arene 5h. Mp¼115–
NMR (200 MHz, CDCl3) d 3.83 (s, 9H), 4.80 (s, 12H),
6.93 (d, J¼8.8 Hz, 6H), 7.32 (s, 6H), 7.42 (d, J¼8.4 Hz,
6H), 8.81 (s, 3H); HRMS (FAB+) calcd for C45H42O9
(M+): 726.2829. Found: 726.2834. Anal. Calcd for
C45H42O6$0.5H2O: C, 73.45; H, 5.89. Found: C, 73.09;
H, 5.84.
117 ꢀC; IR (KBr) 3351, 1601, 1478, 1360, 1243 cmꢁ1
;
1H NMR (300 MHz, CDCl3) d 3.77 (s, 9H), 4.79 (s, 12H),
6.92–7.01 (m, 6H), 7.20–7.31 (m, 6H), 7.30 (s, 6H), 8.90 (s,
3H); HRMS (FAB+) calcd for C45H42O9 (M+): 726.2829.
Found: 726.2818. Anal. Calcd for C45H42O9$1.5H2O: C,
71.70; H, 6.02. Found: C, 72.09; H, 5.74.
3.4.4. Hexahomotrioxacalix[3]arene 5d. Mp¼137–
3.5.5. Hexahomotrioxacalix[3]arene 5i. Mp¼138–141 ꢀC;
1
1
139 ꢀC; IR (KBr) 3342, 1605, 1481, 1361, 1223 cmꢁ1; H
IR (KBr) 3363, 1608, 1480, 1361, 1204 cmꢁ1; H NMR
NMR (200 MHz, CDCl3) d 4.81 (s, 12H), 7.03–7.12 (m,
6H), 7.31 (s, 6H), 7.39–7.47 (m, 6H), 8.84 (s, 3H); HRMS
(FAB+) calcd for C42H33F3O6 (M+): 690.2229. Found:
(200 MHz, CDCl3) d 4.78 (s, 12H), 5.13 (s, 3H), 6.91–
6.98 (m, 6H), 7.12–7.25 (m, 6H), 7.25 (s, 6H), 8.92
(s, 3H); HRMS (FAB+) calcd for C42H36O9 (M+): 684.2360.

10324
K. Tsubaki et al. / Tetrahedron 62 (2006) 10321–10324
Found: 684.2371. Anal. Calcd for C42H36O9$0.5CHCl3: C,
68.57; H, 4.94. Found: C, 68.86; H, 5.27.
Supplementary data
1
The H NMR spectra of 2, 4, and 5a–5m. Supplementary
data associated with this article can be found in the online
version, at doi:10.1016/j.tet.2006.08.073.
3.5.6. Hexahomotrioxacalix[3]arene 5j. Mp¼103–106 ꢀC;
1
IR (KBr) 3343, 1728, 1612, 1473, 1364 cmꢁ1; H NMR
(200 MHz, CDCl3) d 1.07 (t, J¼7.0 Hz, 9H), 4.11 (q,
J¼7.0 Hz, 6H), 4.76 (s, 12H), 7.11 (s, 6H), 7.26–7.48 (m,
9H), 7.78 (d, J¼7.4 Hz, 3H), 8.86 (s, 3H); HRMS (FAB+)
calcd for C51H48O12 (M+): 852.3146. Found: 852.3158.
Anal. Calcd for C51H48O12$0.5H2O: C, 71.07; H, 5.73.
Found: C, 71.15; H, 5.72.
References and notes
1. For reviews on calixarene: (a) Gutsche, C. D. Calixarenes; The
Royal Society of Chemistry: Cambridge, 1989; (b) Gutsche,
C. D. Calixarenes Revisited; The Royal Society of Chemistry:
Cambridge, 1998; For reviews on homooxacalixarene: (c)
3.5.7. Hexahomotrioxacalix[3]arene 5k. Mp¼154–
156 ꢀC; IR (KBr) 3345, 1665, 1580, 1521, 1447 cmꢁ1
;
Ibach, S.; Prautzsch, V.; Vogtle, F.; Chartroux, C.; Gloe, K.
€
1H NMR (200 MHz, CDCl3) d 1.99 (s, 9H), 4.81 (s, 12H),
7.00 (s, 3H), 7.17 (br s, 12H), 7.30–7.40 (m, 3H), 8.24 (d,
J¼7.6 Hz, 3H), 8.96 (s, 3H); HRMS (FAB+) calcd for
C48H46N3O9 (M+H+): 808.3234. Found: 808.3223. Anal.
Calcd for C48H45N3O9$1/3CHCl3: C, 68.48; H, 5.39; N,
4.96. Found: C, 68.84; H, 5.57; N, 5.04.
Acc. Chem. Res. 1999, 32, 729–740; (d) Shokova, E. A.;
Kovalev, V. V. Russ. J. Org. Chem. 2004, 40, 607–643; (e)
Shokova, E. A.; Kovalev, V. V. Russ. J. Org. Chem. 2004, 40,
1547–1578.
2. (a) Tsubaki, K.; Otsubo, T.; Tanaka, K.; Fuji, K.; Kinoshita, T.
J. Org. Chem. 1998, 63, 3260–3265; (b) Tsubaki, K.;
Mukoyoshi, K.; Otsubo, T.; Fuji, K. Chem. Pharm. Bull. 2000,
48, 882–884.
3. Tsubaki, K.; Otsubo, T.; Morimoto, T.; Maruoka, H.; Furukawa,
M.; Momose, Y.; Shang, M.; Fuji, K. J. Org. Chem. 2002, 67,
8151–8156.
4. (a) Miyaura, N.; Yamada, K.; Suzuki, A. Tetrahedron Lett. 1979,
20, 3437–3440; (b) Miyaura, N.; Suzuki, A. Chem. Rev. 1995,
95, 2457–2483.
5. (a) Ikeda, A.; Yoshimura, M.; Tani, F.; Naruta, Y.; Shinkai, S.
Chem. Lett. 1998, 27, 587–588; (b) Ikeda, A.; Udzu, H.;
Zhong, Z.; Shinkai, S.; Sakamoto, S.; Yamaguchi, K. J. Am.
Chem. Soc. 2001, 123, 3872–3877; For other transformations
on the upper rims of hexahomotrioxacalix[3]arenes: (c)
Zhong, Z.; Ikeda, A.; Shinkai, S. J. Am. Chem. Soc. 1999, 121,
11906–11907; (d) Araki, K.; Hayashida, H. Tetrahedron Lett.
2000, 41, 1807–1810; (e) Tsubaki, K.; Morimoto, T.; Otsubo,
T.; Fuji, K. Org. Lett. 2002, 4, 2301–2304.
6. (a) Wolfe, J. P.; Singer, R. A.; Yang, B. H.; Buchwald, S. L.
J. Am. Chem. Soc. 1999, 121, 9550–9561; (b) Barder, T. E.;
Walker, S. D.; Martinelli, J. R.; Buchwald, S. L. J. Am. Chem.
Soc. 2005, 127, 4685–4696.
3.5.8. Hexahomotrioxacalix[3]arene 5l. Mp¼135–137 ꢀC;
1
IR (KBr) 3348, 2854, 1612, 1471, 1322 cmꢁ1; H NMR
(200 MHz, CDCl3) d 4.85 (s, 12H), 7.29–7.33 (m, 3H),
7.34 (s, 6H), 7.78 (d, J¼7.6 Hz, 3H), 8.55 (d, J¼3.8 Hz,
3H), 8.76 (s, 3H), 8.91 (s, 3H); HRMS (FAB+) calcd for
C39H34N3O6 (M+H+): 640.2448. Found: 640.2450. Anal.
Calcd for C39H33N3O6$0.5CHCl3: C, 67.83; H, 4.83; N,
6.01. Found: C, 68.12; H, 5.22; N, 5.86.
3.5.9. Hexahomotrioxacalix[3]arene 5m. Mp>300 ꢀC; IR
(KBr) 3332, 1600, 1548, 1477, 1317 cmꢁ1 1H NMR
;
(200 MHz, CDCl3) d 4.85 (s, 12H), 7.43 (d, J¼6.2 Hz,
6H), 7.46 (s, 6H), 8.61 (d, J¼6.2 Hz, 6H), 8.97 (s, 3H);
HRMS (FAB+) calcd for C39H34N3O6 (M+H+): 640.2448.
Found: 640.2451. Anal. Calcd for C39H33N3O6$1.5H2O:
C, 70.26; H, 5.44; N, 6.30. Found: C, 70.27; H, 5.32;
N, 6.22.
Acknowledgements
7. Ikeda, A.; Suzuki, Y.; Yoshimura, M.; Shinkai, S. Tetrahedron
1998, 54, 2497–2508.
8. Araki, K.; Inada, K.; Otsuka, H.; Shinkai, S. Tetrahedron 1993,
49, 9465–9478.
9. Komatsu, N. Tetrahedron Lett. 2001, 42, 1733–1736.
This study was partly supported by the 21st Century COE
Program on Kyoto University Alliance for Chemistry from
the Ministry of Education, Culture, Sports, Science, and
Technology, Japan.