A convergent synthesis of hexahomotriazacalix[3]arene macrocycles

Article abstract of DOI:10.1021/jo001094y

A new, convergent synthesis of hexahomotriazacalix[3]arenes 1a-e is described. The key transformation in this synthesis involves the coupling of the triamines 4a-d with 2,6-bis-(chloromethyl)-4-methylphenol 5 and results in the formation of the hexahomotriazacalix[3] arenes 1a-d in 90-95% yield. The triamines 4a-d were constructed by the one-pot reaction of monochloroaldehyde 3 and a primary amine followed by reduction to yield the triamines 4a-d in 50-55% yield. Deallylation of macrocycle 1d was accomplished by palladium catalysis to obtain the N-unsubstituted macrocycle 1e, which has the potential to be a precursor to a variety of N-substituted hexahomotriazacalix[3]arenes.

Full text of DOI:10.1021/jo001094y

J . Org. Chem. 2000, 65, 8297-8300
8297
A Con ver gen t Syn th esis of Hexa h om otr ia za ca lix[3]a r en e
Ma cr ocycles
Panadda Chirakul,† Philip D. Hampton,* and Zsolt Bencze
Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131
phampton@unm.edu
Received J uly 19, 2000
A new, convergent synthesis of hexahomotriazacalix[3]arenes 1a -e is described. The key
transformation in this synthesis involves the coupling of the triamines 4a -d with 2,6-bis-
(chloromethyl)-4-methylphenol 5 and results in the formation of the hexahomotriazacalix[3]arenes
1a -d in 90-95% yield. The triamines 4a -d were constructed by the one-pot reaction of
monochloroaldehyde 3 and a primary amine followed by reduction to yield the triamines 4a -d in
50-55% yield. Deallylation of macrocycle 1d was accomplished by palladium catalysis to obtain
the N-unsubstituted macrocycle 1e, which has the potential to be a precursor to a variety of
N-substituted hexahomotriazacalix[3]arenes.
In tr od u ction
Calixarenes and related macrocycles have received
considerable attention in recent years from many re-
search groups as host molecules in host-guest chemis-
try.1-3 Our interest in the synthesis of the hexahomotri-
azacalix[3]arenes 1, abbreviated to azacalix[3]arenes in
this paper, is due to their potential of being hosts for the
binding of metal ions and alkylammonium ions.3-5 The
structure of the azacalix[3]arene macrocycles is shown
in Figure 1. The C3 symmetric arrangement of hydrogen-
bond acceptors present in the cup of the azacalix[3]arene
macrocycles resembles the structure of 1,7,13-triaza-18-
crown-6 which has been reported by Lehn to complex
ammonium and alkylammonium ions more strongly than
alkali metal ions.6 We have previously reported that
azacalix[3]arene 1i binds trivalent metal ions (Sc, Y, La)
with the macrocycle acting as either a neutral or tri-
anionic ligand to the metal center.3 Takemura and Vicens
F igu r e 1. Structures of azacalix[3]arene 1 and azacalix[4]-
arene 2 macrocycles.
and their co-workers recently reported the binding of Nd-
(III) by azacalix[3]arene 1h .4
Previous reports of the synthesis of the azacalix[3]-
arene macrocycles 1 utilized a cyclooligomerization ap-
proach.2,4,5 Takemura and co-workers reported that
azacalix[3]arenes 1a , 1b, and 1f-h could be prepared by
the thermal condensation of 2,6-bis(hydroxymethyl)-
phenols with primary amines.4,5 In our hands, these
conditions led to mixtures of azacalix[3]arene 1 and
azacalix[4]arene 2 (Figure 1) macrocycles. We previously
reported the synthesis of azacalix[3]arene 1i by the
reaction of glycine methyl ester hydrochloride with 2,6-
bis(chloromethyl)-4-methylphenol.2 This reaction results
in a mixture of azacalix[3]arene 1i and azacalix[4]arene
2i (6:1 ratio) which could be separated by crystallization
to provide pure 1i in 19% yield. Our interest in the
synthesis of the azacalix[3]arenes for host-guest and
metal-ion binding studies, coupled with the low yields
and the difficult separation of macrocycles 1 and 2, led
us to examine a convergent approach to the synthesis of
the azacalix[3]arene macrocycles.
* To whom correspondence should be addressed.
† Present address: Department of Chemistry, University of Wash-
ington, Seattle, WA 98195.
(1) Gutsche, C. D. Calixarenes Revisited, Monographs in Supramo-
lecular Chemistry; Stoddart, J . F., Ed.; The Royal Society of Chemis-
try: Cambridge, 1998.
(2) Hampton, P. D.; Tong, W.; Wu, S.; Duesler, E. N. J . Chem. Soc.,
Perkin Trans. 2 1996, 1127.
(3) Hampton, P. D.; Wu, S.; Chirakul, P.; Bencze, Z.; Duesler, E. N.
Calixarenes for Separations. In Molecular Recognition by Azacalix[3]-
arenes; Lumetta, G. J ., Rogers, R. D., Gopalan, A. S., Eds.; ACS
Symposium Series, American Chemical Society: Washington, D.C.,
2000, Chapter 15, pp 195-207.
(4) Thuery, P.; Nierlich, M.; Vicens, J .; Takemura, H. J . Chem. Soc.,
Dalton Trans. 2000, 279.
(5) (a) Takemura, H.; Shinmyozu, T.; Miura, H.; Khan, I. U.; Inazu,
T. J . Inclusion Phenom. 1994, 19, 193. (b) Khan, I. U.; Takemura, H.;
Suenaga, M.; Shinmyozu, T.; Inazu, T. J . Org. Chem. 1993, 58, 3158.
(c) Takemura, H.; Yoshimura, K.; Khan, I. U.; Shinmyozu, T.; Inazu,
T. Tetrahedron Lett. 1992, 33, 5775.
In this manuscript, we report a new synthetic route,
shown in Figure 2, which is efficient for the preparation
of the azacalix[3]arene macrocycles 1. This route prevents
the formation of higher cyclics and allows for the syn-
thesis of azacalix[3]arenes 1 possessing a range of N-
substituents in high yields. An N-unsubstituted-azacalix-
(6) Lehn, J . M. Angew. Chem., Intl. Ed. Engl. 1988, 27, 89.
10.1021/jo001094y CCC: $19.00 © 2000 American Chemical Society
Published on Web 11/03/2000

8298 J . Org. Chem., Vol. 65, No. 24, 2000
Chirakul et al.
F igu r e 3. Preparation of aldehyde 3.
methyl)-4-methylphenols are isolated (<2% yield based
on starting aldehyde) as side products which result from
reduction of a monoalkylated imine intermediate. The
poor yields may be due to partial decomposition of
aldehyde 3 in the presence of base. The air-sensitive
triamines 4 were characterized by 1H and 13C NMR, two-
dimensional NOESY experiments, and mass spectrom-
etry.
The synthesis of the aldehyde starting material 3 was
accomplished by protection of 2,6-bis(hydroxymethyl)-4-
methylphenol 6 as its acetonide 7 and oxidation with
pyridinium chlorochromate (PCC) to yield the protected
aldehyde 8 (Figure 3).3,9 A one-pot reaction for deprotec-
tion and chlorination of 8 with concentrated HCl resulted
in the aldehyde 3 in high yield.
F igu r e 2. Convergent synthetic approach to the azacalix[3]-
arenes 1a -d .
Coupling of the triamine dimers 4a -d with 2,6-bis-
(chloromethyl)-4-methylphenol 5 was achieved in DMF
in the presence of potassium carbonate at room temper-
ature for 4 h to yield macrocycles 1a -d in 90-95% yield.
There was no evidence of the formation of higher cyclics
(i.e., hexamers) or polymeric material under these condi-
tions. We believe that the high yield for this coupling step
and the absence of oligomeric or polymeric products may
be due to intramolecular hydrogen-bonding which tem-
plates the cyclization of the acyclic trimer formed after
monoalkylation of the triamine dimer. Azacalix[3]arenes
1a and 1b have previously been synthesized by Take-
mura and co-workers;5 however, a number of significant
differences in the chemical shifts and coupling for these
compounds were noted which may suggest that their
azacalix[3]arenes were contaminated with other cyclic
oligomers.10
[3]arene 1e has been prepared which is a versatile
intermediate for the synthesis of a variety of azacalix-
[3]arenes having different N-substituents. Azacalix[3]-
arenes 1c-e are new compounds.
Resu lts a n d Discu ssion
Two possible convergent synthetic routes to the azacalix-
[3]arenes involve either (1) cyclization of an acyclic trimer
or (2) condensation of a dimer with a monomer to yield
the cyclic trimer 1. Both approaches have been reported
for the structurally related oxacalix[3]arene macrocycles.7
Robson and co-workers have reported the selective
synthesis of the N-unsubstituted azacalix[4]arene 2 (R′
) H) through the condensation of dialdehyde and di-
amine monomers, followed by reduction of the tetraimine
macrocycle.8 We believed that the condensation of the
triamine dimers 4 with the dichloro monomer 5, as shown
in Figure 2, would be the simplest approach to the
synthesis of the azacalix[3]arene macrocycles.
IR spectra of macrocycles 1a -e exhibit an O-H
stretching peak as a broad band in the region of 3230-
3270 cm-1. The low frequency of this stretch indicates
The triamines 4a -d can be prepared by a one-pot
reaction of aldehyde 3 and a primary amine in DMF at
room temperature with K2CO3, followed by reduction
with sodium borohydride (Figure 2). The yields for this
step are 50-55% which are reasonable considering that
a total of six separate reactions are occurring in this
step: double alkylation, imine formation, and imine
reduction. Only small amounts of 2,6-bis(alkylamino-
(9) Fraser, C.; J ohnston, L.; Rheingold, A. L.; Haggerty, B. S.;
Williams, G. K.; Whelan, J .; Bosnich, B. Inorg. Chem. 1992, 31, 1835.
(10) Takemura and co-workers reported (ref 5c) that compound 1a
exhibited a singlet at 7.28 ppm and a multiplet between 6.86 and 6.62
ppm for the macrocycle 3,5-arene protons in the 1H NMR.; no 13C NMR
data were provided for this compound. In contrast, we observed a
multiplet between 7.44 and 7.19 and a singlet at 6.67 ppm. For
compound 1b, Takemura and co-workers also reported (ref 5a) that
the macrocycle arene protons exhibited a multiplet between 6.87 and
6.68 ppm, a singlet at 3.80 ppm for the side chain methine, and a
singlet at 1.48 ppm for the side chain methyl group. We observed a
singlet at 6.67 ppm, a quartet at 4.12 ppm, and a doublet at 1.62 ppm
for the same signals. The multiplet for the macrocycle 3,5-arene protons
in both compounds prepared by Takemura and co-workers suggests a
mixture of oligomers were isolated. Both compounds exhibited singlets
for these protons when they were prepared by the convergent approach
discussed in this paper.
(7) (a) Tsubaki, K.; Otsubo, T.; Tanaka, K.; Fuji, K.; Kinoshita, T.
J . Org. Chem. 1998, 63, 3260. (b) Tsubaki, K.; Mukoyoshi, K.; Otsubo,
T.; Fuji, K. Chem. Pharm. Bull. 2000, 48, 882.
(8) (a) Grannas, M. J .; Hoskins, B. F.; Robson, R. Inorg. Chem. 1994,
33, 1071. (b) Grannas, M. J .; Hoskins, B. F.; Robson, R. J . Chem. Soc.,
Chem. Commun. 1990, 1644.

Hexahomotriazacalix[3]arene Macrocycles
J . Org. Chem., Vol. 65, No. 24, 2000 8299
the reaction was stirred at room temperature for 24 h. Sodium
borohydride (0.22 g, 5.8 mmol) in methanol (20 mL) was then
added dropwise to this mixture. After stirring for 24 h, the
mixture was acidified by the addition of 6 M HCl and refluxed
for 4 h. The reaction mixture was evaporated to dryness, and
the residue was neutralized with 1 M NaOH. Dichloromethane
(25 mL) was then added to this residue, the CH2Cl2 layer was
washed with water and dried over sodium sulfate, and the
solvent was removed in vacuo. The yellow-brown solid was
purified by flash column chromatography on silica gel with
ethyl acetate as the eluent to give 4a in 55% yield as a pale
yellow solid. 1H NMR (500 MHz) 7.30-7.20 (m, 15H), 6.79,
6.74 (pair brs, 4H), 3.80 (s, 4H), 3.70 (s, 6H), 3.63 (s, 4H), 2.16
(s, 6H); 13C NMR (125 MHz) 154.1, 139.5, 137.4, 129.7, 129.6,
129.0, 128.4, 128.2, 127.5, 127.2, 127.0, 124.0, 122.9, 58.3, 54.4,
52.8, 50.5, 20.4; HRMS calcd m/z for C39H43N3O2 (M + H)+
586.3434, found 586.3346.
strong intramolecular hydrogen-bonding between the
phenol groups and the nitrogens in the center of the
macrocycle, which is consistent with the small O (phe-
nol)-N distance in the crystal structure of azacalix[3]-
arene 1i.2 1H NMR spectra of azacalix[3]arenes 1a -d
exhibit singlets for the aromatic protons, the p-methyl
groups, and the methylene groups in the macrocycle ring.
When the temperature was lowered to 210 K, broadening
of the methylene proton peaks in the macrocycle ring was
observed for azacalix[3]arenes 1a -d . In addition, the
methylene signal for the benzyl groups in 1a also
exhibited broadening as the temperature was lowered.
These observations can be explained by rapid nitrogen
inversion and interconversion of the cone and partial-
cone isomers of macrocycles 1a -d on the NMR time scale
at room temperature.
Deallylation of 1d was readily achieved at room tem-
perature in 1 h by treatment of 1d with 2-mercaptoben-
zoic acid in tetrahydrofuran in the presence of 0.05 molar
equivalents (per allyl group) of the preformed catalyst
consisting of a 1:1 molar mixture of tris(dibenzylidene-
acetone)dipalladium(0) and diphenylphosphinobutane.11
After purification by recrystallization from ethyl acetate,
the N-unsubstituted-azacalix[3]arene 1e was obtained in
90% yield.
Syn th esis of N-(S)-(-)-R-Meth ylben zyl-tr ia m in e (4b).
The crude product was separated by flash chromatography on
silica gel with hexane/ethyl acetate (4:1) to give 4b in 59% yield
as a pale yellow solid. 1H NMR (500 MHz) 7.30-7.18 (m, 15H),
6.72, 6.62 (s each, 2H each), 4.03 (q, J ) 6.8 Hz, 1H), 3.74 and
3.70 (d, J ) 13.6 Hz, and q, J ) 6.6 Hz, 4H total), 3.64, 3.53
(pair d, J ) 13.4 Hz, 2H each), 3.35 (d, J ) 13.5 Hz, 2H), 2.12
(s, 6H), 1.50 (d, J ) 7.0 Hz, 3H), 1.31 (d, J ) 6.7 Hz, 6H); 13
C
NMR (125 MHz) 154.2, 139.7, 129.6, 128.8, 128.7, 128.5, 128.1,
127.6, 127.3, 127.1, 126.7, 123.2, 57.0, 50.0, 48.8, 23.7, 20.5;
HRMS calcd m/z for C42H49N3O2 (M + H)+ 628.3825, found
628.3917; [R]25 ) -67.2 (c 1.5, CH2Cl2, optical purity un-
D
known).
Con clu sion
Syn th esis of N-Isobu tyl-tr ia m in e (4c). The crude product
was separated by flash chromatography on silica gel with
hexane/ethyl acetate (2:1) to give 4c in 50% yield as a pale
This convergent synthetic route provides a convenient
synthesis of the azacalix[3]arene macrocycles 1 with a
variety of N-substituents and without contamination by
the azacalix[4]arene macrocycles 2. The synthesis and
coupling of the triamine-dimers 4 tolerates a wide range
of nitrogen substituents and could be performed on a
large scale. The N-unsubstituted macrocycle 1e could be
easily modified through alkylation, Michael addition, or
reductive amination to yield a wide range of substituted
azacalix[3]arenes. We are currently examining the role
of the N-substituent on the host-guest chemistry and
metal-ion binding affinity of the azacalix[3]arene mac-
rocycles 1.
1
yellow solid. H NMR (250 MHz) 6.79, 6.78 (s each, 2H each),
3.81 (s, 4H), 3.59 (s, 4H), 2.43 (d, J ) 7.2 Hz, 4 H), 2.23 (d, J
) 6.6 Hz, 2H), 2.19 (s, 6H), 1.98 (m, 1H), 1.77 (m, 2H), 0.90
(d, J ) 6.7 Hz, 12H), 0.86 (d, J ) 6.4 Hz, 6H); 13C NMR (125
MHz) 154.1, 129.7, 128.7, 127.3, 124.2, 123.1, 63.0, 57.0, 55.2,
51.4, 28.2, 25.7, 21.0, 20.6, 20.5; HRMS calcd m/z for C30H49N3O2
(M + H)+ 484.3825, found 484.3892.
Syn th esis of N-Allyl-tr ia m in e (4d ). The crude product
was separated by flash chromatography on silica gel with
hexane/ethyl acetate (3:1) to give 4d in 53% yield as a pale
1
yellow solid. H NMR (250 MHz) 6.81 (s, 4H), 5.98-5.88 (m,
3H), 5.23-5.10 (m, 6H), 3.85 (s, 4H), 3.68 (s, 4H), 3.26 (d, J )
8.4 Hz, 4H), 3.13 (d, J ) 6.7 Hz, 2H), 2.21 (s, 6H); 13C NMR
(62.9 MHz) 154.3, 136.1, 133.9, 129.7, 129.0, 127.5, 124.1,
122.9, 119.0, 116.5, 55.7, 54.3, 51.2, 50.3, 20.4; HRMS calcd
m/z for C27H37N3O2, calcd (M + Na)+ 458.2783, found 458.2777.
Exp er im en ta l Section
Gen er a l P r oced u r es. N,N-Dimethylformamide (DMF) was
dried over calcium sulfate or type 3 Å molecular sieve for 72
h, followed by distillation under reduced pressure and was
stored over 4 Å molecular sieves. All reactions were run under
N2 atmosphere unless otherwise noted. Flash column chro-
matography was carried out with EM type 60 (230-400 mesh)
silica gel. All compounds were pure based on TLC analysis.
Elemental analyses were not performed on the triamines 4 or
azacalix[3]arene 1e due to their rapid oxidation in air.
Azacalix[3]arenes 1a and 1b are known compounds.5 1H NMR
and 13C NMR were recorded for CDCl3 solutions. High resolu-
tion (HRMS) FAB mass spectra were provided by the Nebraska
Center for Mass Spectrometry, University of Nebraska, in
Lincoln NE.
A Gen er a l P r oced u r e for th e Syn th esis of th e Tr i-
a m in e Dim er s 4a -d . Syn t h esis of N-Ben zyl-t r ia m in e
(4a ). A mixture of 2-chloromethyl-5-methylbenzaldehyde 3
(0.400 g, 2.17 mmol), benzylamine (0.24 mL, 2.2 mmol), and
potassium carbonate (1.0 g, 6.5 mmol) in DMF (30 mL) was
stirred for 15 min at room temperature. This reaction mixture
was added dropwise to a solution of benzylamine (0.12 mL,
1.1 mmol) in DMF (20 mL) over 4 h. After complete addition,
Gen er a l Syn th eses of Aza ca lix[3]a r en es 1a -d . Syn -
th esis of N-Ben zyla za ca lix[3]a r en e (1a ). A solution of 2,6-
bis(chloromethyl)-4-methylphenol (0.118 g, 0.0575 mmol) in
DMF (20 mL) was added dropwise over 3 h to a vigorously
stirred solution of triamine 4a (0.261 g, 0.0445 mmol) in DMF
(10 mL) in the presence of K2CO3 (0.070 g, 0.045 mmol), and
the mixture was stirred for 24 h. The reaction mixture was
concentrated on a rotary evaporator, and the residue was
purified by column chromatography (SiO2, CHCl3/EtOAc ) 2:1)
1
to give the product 1a as a pale yellow solid in 95% yield. H
NMR (500 MHz) 10.80 (brs, 3H), 7.44-7.19 (m, 15H), 6.77 (s,
6H), 3.66, 3.61 (s each, 18H), 2.21 (s, 9H); 13C NMR (125 MHz)
154.7, 137.2, 130.3, 129.7, 127.9, 126.8, 123.5, 57.6, 57.0, 20.4;
HRMS calcd m/z for C48H51N3O3 (M + H)+ 718.4009, found
718.4031.
Syn th esis of N-(S)-(-)-R-Meth ylben zyla za ca lix[3]a r en e
(1b). The crude product was separated by flash chromatog-
raphy on silica gel with hexane/ethyl acetate (5:1) to give 1b
1
in 95% yield as a white solid. H NMR (250 MHz) 10.75 (brs,
3H), 7.29 (brs, 15H), 6.67 (s, 6H), 4.12 (q, J ) 7.5 Hz, 3H),
3.26 (brs, 12H), 2.14 (s, 9H), 1.62 (d, J ) 6.9 Hz, 9H); 13C NMR
(62.9 MHz) 155.2, 140.0, 130.0, 128.9, 127.9, 127.1, 126.8,
123.4, 56.8, 52.7, 29.7, 20.4.; HRMS calcd. m/z for C51H57N3O3
(M+H)+ 759.4400, found 760.4450; [R]25 ) - 67.9 (c 0.5,
D
(11) Tsuji, J . Palladium Reagents and Catalysts; J ohn Wiley &
Sons: Chichester, 1995.
CHCl3, optical purity unknown).

8300 J . Org. Chem., Vol. 65, No. 24, 2000
Chirakul et al.
Syn th esis of N-Isobu tyla za ca lix[3]a r en e (1c). The crude
product was separated by flash chromatography on silica gel
with hexane/ethyl acetate (3:1) to give 1c in 90% yield as a
white solid. 1H NMR (250 MHz) 6.71 (s, 6H), 3.54 (s, 12H),
2.25 (d, J ) 7.0 Hz, 6H), 2.17 (s, 9H), 1.84 (m, 3H), 0.79 (d, J
) 6.3 Hz, 18H); 13C NMR (125 MHz) 154.8, 130.3, 126.8, 123.9,
122.8, 63.4, 58.0, 26.0, 21.3, 20.7; Anal. Calcd for C39H57N3O3:
C 76.06; H, 9.23. Found: C, 75.78; H, 9.27; HRMS calcd m/z
for C39H57N3O3 (M + H)+ 616.4478, found 616.4502.
stirred at room temperature for 1 h. The mixture was treated
with 10% HCl and extracted with ethyl acetate (3 × 10 mL).
The aqueous layer was made basic with 1 M NaOH and
extracted with ethyl acetate (5 × 10 mL). The combined
extracts were dried over sodium sulfate and concentrated in
vacuo. The crude product was recrystallized from ethyl acetate
to obtain product 1e in 90% yield. 1H NMR (250 MHz) 6.82 (s,
6H), 3.86 (s, 12H), 2.22 (s, 9H); 13C NMR (125 MHz) 155.0,
129.2, 126.9, 124.9, 125.8, 50.8, 20.5; HRMS calcd m/z for
Syn th esis of N-Allyla za ca lix[3]a r en e (1d ). The crude
product was separated by flash chromatography on silica gel
with hexane/ethyl acetate (3:1) to give 1d in 95% yield as a
white solid. 1H NMR (250 MHz) 6.76 (s, 6H), 5.98-5.88 (m,
3H), 5.07-4.91 (overlapping pair dd, 6H), 3.73 (brs, 12H), 2.91
(d, J ) 6.8 Hz, 6H), 2.20 (s, 9H); 13C NMR (62.9 MHz) 155.3,
130.0, 126.8, 123.7, 118.5, 112.9, 56.4, 20.4, 11.9; Anal. Calcd.
for C36H45N3O3: C 76.15; H, 7.99; N, 7.40. Found: C, 76.42;
H, 8.24: N, 6.92; FABMS m/z (rel intensity) 569.5 [(M + H)+,
100], 526.4 (34), 485.3 (4), 430.2 (8), 377.3 (20), 322.2 (66),
280.1 (21), 188.2 (76), 133.1 (85); HRMS calcd. m/z for
C
27H33N3O3 (M + H)+ 448.2533, found 448.2591.
Ack n ow led gm en t. This work was supported by the
Petroleum Research Fund (PRF-AC 31925), adminis-
tered by the American Chemical Society. The authors
also thank Dr. Todd M. Alam, Sandia National Labora-
tory, for assistance in VT-NMR studies and for many
helpful discussions. The NSF Chemical Instrumentation
Program is acknowledged for providing a low field and
a high field NMR.
C
36H45N3O3 (M + H)+ 569.3589, found 569.3572.
Syn th esis of N-Un su bstitu ted -a za ca lix[3]a r en e (1e). A
mixture of tris(dibenzylideneacetone)dipalladium [Pd(dba)2]
(0.0075 g, 0.0082 mmol) and 1,4-bis(diphenyl)phosphinobutane
(DPPB, 0.0034 g, 0.0080 mmol) in 1 mL of THF was stirred at
room temperature under nitrogen for 15 min. The preformed
catalyst and mercaptobenzoic acid (0.0294 g, 0.185 mmol) were
added to a solution of N-allylazacalix[3]arene 1d (0.0300 g,
0.0528 mmol) in 5 mL of THF, and the reaction mixture was
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
cedures for compounds 3, 5, 7, and 8, and characterization and
spectral data for triamines 4a -d and azacalix[3]arenes 1a -
e. This material is available free of charge via the Internet at
http://pubs.acs.org.
J O001094Y