Synthesis, characterization, and biological evaluation as antibacterial agents of water-soluble calix[4]arenes and phenol derivatives incorporating carboxylate groups

Article abstract of DOI:10.1002/hlca.201200044

As part of specific investigations dedicated to the building of a chemical library of calixarenes with anti-infective properties, some H ₂O-soluble calix[4]arene derivatives incorporating carboxylate groups at the upper rim and heterocycles at

Full text of DOI:10.1002/hlca.201200044

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Synthesis, Characterization, and Biological Evaluation as Antibacterial
Agents of Water-Soluble Calix[4]arenes and Phenol Derivatives
Incorporating Carboxylate Groups
by Maxime Mourer, Ste´phane Fontanay, Raphae¨l E. Duval, Jean-Bernard Regnouf-de-Vains*
´
´
SRSMC, UMR 7565 Universite de Lorraine – CNRS, Groupe dꢀEtude des Vecteurs Supramoleculaires
´
´
du Medicament, Faculte de Pharmacie, 5, rue Albert Lebrun, BP 80403, F-54001 Nancy Cedex (phone:
þ 33-3-83682315; fax: þ 33-3-83682345; e-mail: jean-bernard.regnouf@pharma.uhp-nancy.fr)
As part of specific investigations dedicated to the building of a chemical library of calixarenes with
anti-infective properties, some H2O-soluble calix[4]arene derivatives incorporating carboxylate groups at
the upper rim and heterocycles at the lower rim have been prepared and characterized as have their
constitutive functional monomers. In vitro antibacterial testing against Gram-positive and Gram-
negative reference strains shows that the derivative with two 5,5’-dicarboxylated 2,2’-bithiazole subunits
in alternate positions at the lower rim displays an activity at ca. 70 mm (128 mg/ml) on S. aureus ATCC
29213.
Introduction. – Faced with the emergence of strains of pathogenic microorganisms
resistant to present antibiotics [1], research dedicated to the discovery of new drugs in
this field has resulted in some interesting approaches involving calixarene derivatives.
Nevertheless, as summarized in some recent reviews [2 – 5], few studies have focused
on the therapeutic potential of calixarene compounds as anti-infective agents. For
example, in the mid-1950s, the calixarene derivative ꢁmacrocyclonꢀ [6], and, more
recently, some parent structures [7 – 9] were studied with respect to the treatment of
tuberculosis and other mycobacterioses. The building of designed calixarenic mimics of
vancomycin has also been performed, with the aim of generating antimicrobial activity
[10], and some biological studies related to plasmid DNA binding and cell transfection
were reported by Ungaro and co-workers [11 – 13]. Certain hydrophilic derivatives
have shown interesting levels of activity against bacteria, [14], fungi, cancerous cells,
and enveloped viruses [15 – 21].
To progress in this direction, we focused on the development of new molecular
devices, designed to function as hydrophobic [22] or hydrophilic [23] molecular drug
dispensers. These are based on a calixarene platform with penicillin or quinolone
moieties attached via a labile bond at the lower rim. We developed poly-ionic
calixarene derivatives which display intrinsic antibacterial activity. The first derivatives
of this type were designed as spatially organized and constrained tetra-guanidinium
entities, in which the ionic groups were tethered at the upper rim of the calix[4]arene
platform, the lower rim remaining free (OH groups) [24] or partially substituted [25].
These compounds, assumed to interact with and damage negatively charged bacterial
surfaces, displayed useful antibacterial activities against various reference [24] or
resistant [26] Gram-negative or Gram-positive bacterial strains. We found that these
ꢂ 2012 Verlag Helvetica Chimica Acta AG, Zꢃrich

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cationic molecules have an impact on the bacterial wall [27] and should modify
bacterial membrane permeability [28].
The two initial studies were carried out by a comparison of calix[4]arene derivatives
with their constitutive phenolic monomers, showing the importance of pre-organization
of guanidinium functions in the acquisition of antibacterial properties [24][25].
In parallel, various H2O-soluble poly-anionic calixarene derivatives were evaluated
as anti-HIV compounds. Among them, derivatives of the tetra-para-(carboxymethyl)-
calix[4]arene (1; cf. Scheme 1), i.e., sodium salts 11 and 13 (2,2’-bipyridyl) [29], 12 and
14 (2,2’-bithiazolyl) [30], and 15 (unsubstituted) [30] of the present study, showed
interesting inhibitory activities which varied with the cell and HIV-1 strains: IC50 values
lay between 5 and 40 mm, associated with low cytotoxicity (CC50 > 100 mm).
To verify if such derivatives were also antibacterial, and if cyclooligomerization
would result in the gain or acquisition of activity as found in the guanidinium family
[24], we evaluated their activity against Gram-negative and Gram-positive reference
strains. The study was conducted as for guanidinium analogs [24][25], with comparison
of calixarene derivatives and their constitutive functional monomers.
The tetra-para-(carboxymethyl)calix[4]arene (1) has not been extensively studied
in the therapeutic field; it appears essentially to be a candidate for treatment of HIV
infection [15][30], or as an antithrombotic agent [31].
The therapeutic possibilities of 2-(4-hydroxyphenyl)acetic acid (17; cf. Scheme 2)
and its derivatives have been widely studied, but few reports dealt with antimicrobial
activity. Tuncel and Nergiz [32] described the absence of antibacterial activity (agar
dilution technique) of 17 against E. coli O157:H7 (minimum inhibitory concentration
(MIC) 600 mg/ml) and S. aureus NCTC 10657 S-6 (MIC > 600 mg/ml). In a recent
patent, 17 and its ester derivatives were evaluated as conservative antibacterial agents
against A. niger, C. albicans, E. coli, P. aeruginosa, and S. aureus (no data available)
[33].
Results and Discussion. – 6-(Bromomethyl)-6’-methyl-2,2’-bipyridine (3) was
prepared according to Rodriguez-Ubis et al. [34], its 4,4’-dimethyl ester analog 5
according to Psychogios et al. [35]. 4-(Bromomethyl)-4’-methyl-2,2’-bithiazole (4) and
its 5,5’-diethyl ester analog 6 were prepared according to Pellet-Rostaing et al. [36], and
Lehn and Regnouf-de-Vains [37], respectively. Calixarene esters, 2, 8, and 10, then
sodium salts 12, 14, and 15 were prepared by the method of Mourer et al. [30]. The
sodium salts 11 and 13 have been previously partially described [38]. The synthetic
pathways are outlined in Scheme 1.
The tetra acetic acid 1 and then the tetraethyl tetraacetate 2 were prepared
according to the procedures of Gutsche and co-workers [39].
Introduction of the heterocyclic subunits in alternate positions, at the lower rim of 2
was carried out by reaction of bromomethyl derivatives 3 and 5 with 2, in dry MeCN, in
the presence of 1 equiv. of K2CO3 as base, to give, with yields of ca. 60% after
chromatography on alumina, the corresponding tetra-ester 7 and octa-ester 9. These
were saponified with NaOH in hydro-alcoholic medium; the addition of HCl resulted
in the precipitation of the corresponding tetra- and octa-acids that were carefully rinsed
with H2O to remove the highest amount of residual NaCl. The acids were then carefully
titrated with aq. NaOH under pH-meter monitoring, until solubilization was complete.

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The resulting solutions were dialyzed on a Float-A-Lyser device (cellulose acetate,
molecular weight cut off (MWCO) 100 D) and lyophilized to give the tetra-sodio
derivative 11, and the octa-sodio derivative 13, respectively.
As direct preparation of 15 from the tetra acid resulting from acidic hydrolysis of
the corresponding tetra-nitrile yielded a colored compound, we decided to prepare it
from the pure ester 2, according to the above mentioned procedure.
Syntheses of monomer species was conducted as outlined in Scheme 2. Methyl (4-
hydroxyphenyl)acetate (16) and the corresponding acid 17 were commercially
available. The reaction of bromomethyl derivatives 3 – 6 with 1 equiv. of 16 and
K2CO3 in dry MeCN afforded the esters 18 – 21, respectively, with yields of between 50
and 97% after chromatography on alumina; the esters were then saponified in an
hydro-alcoholic medium, and consecutive acidification resulted in precipitation of the
corresponding acids 22 – 25; the latter were collected, washed, then cautiously
neutralized by NaOH (pH-meter monitoring), until solubilization was complete, to
give, after lyophilization, the corresponding mono- or trisodium salts 26 – 29,
Scheme 2
i) MeCN, K2CO3, reflux; 18: 77%, 19: 50%, 20: 97%, 21: 73%. ii) a) H2O, EtOH, NaOH, reflux; b) HCl,
H2O; (22: 70%, 23: 93%, 24: 97%, 25: 61%. iii) 0.1m NaOH, pH-meter monitoring; 26: final pH 7.70,
96%; 27: final pH 8.50, 94%; 28: final pH 7.30, 79%; 29: final pH 7.90, 82%; 30: final pH 8.0, 94%.

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respectively. The sodium salt 30 of (4-hydroxyphenyl)acetic acid was prepared from
commercial acid 17 by the same procedure.
Calixarene derivatives 11 and 13 have been described previously [38], as well as
have derivatives 12, 14, and 15 [30]. Due to their low solubility, the structures of
corresponding acid derivatives were only assessed by 1H-NMR. All other compounds,
1
esters and salts, were fully characterized, and gave satisfactory H- and 13C-NMR,
elemental and electrospray ionization mass analyses. More particularly, 1H- and
13C-NMR conformational studies of the calixarene family showed that the cone
conformation was preserved, with ArꢀCH2ꢀAr resonance signals appearing as AB
1
systems around 3.50 and 4.35 ppm in H-NMR and as a singlet around 31 – 32 ppm in
13C-NMR (Table 1) [40].
Table 1. Partial 1H- and 13C-NMR Data (400 and 100 MHz, resp., in D2O, r.t.) of H2O-Soluble
Calixarenes 11 – 15. d in ppm, J in Hz.
ArCH2Ar
d(H)
d(C)
11
12
13
14
15
3.55, 4.38 (AB, JAB ¼ 13.1)
3.48, 4.35 (AB, JAB ¼ 13.3)
3.40, 4.19 (AB, JAB ¼ 12.8)
3.47, 4.40 (AB, JAB ¼ 13.4)
3.00, 4.18 (AB, JAB ¼ 12.08)
30.99
30.74
30.99
31.19
32.19
Initial C,H,N elemental analyses of calixarene salts 12, 14, and 15 suggested the
presence of H2O molecules and supplementary NaCl. The latter, resulting from
titration of residual free or salting HCl, was not fully eliminated during the dialysis
steps. This led us, as we had already done for calixarenes 11 and 13, to complete the
elemental analyses by flame photometry. This gave results consistent with the proposed
formulae (Table 2). Compound 12 was thus found to be associated with 1 NaCl and 6
H2O, 14 with 5 NaCl and 7 H2O, and 15 with 1.5 NaCl and 5.5 H2O.
Table 2. Sodium Content [%] of H2O-Soluble Calixarenes 11 – 15a)
Molecular formula (MW)
Na
Calc.
Found
11
12
13
14
15
C60H48N4Na4O12 · 5.0 H2O · 2 NaCl (1315.90)
C52H40N4Na4O12S4 · 6 H2O · NaCl (1299.60)
C64H44N4Na8O20 · 7.0 H2O · 16 NaCl (2433.94)
C56H36N4Na8O20S4 · 7 H2O · 5 NaCl (1815.24)
C36H28Na4O12 · 5.5 H2O · 1.5 NaCl (931.21)
10.40
8.84
22.70
16.45
13.58
10.16
8.95
22.40
16.08
14.03
a) Evaluated by flame photometry.
Positive-ion-mode ESI-MS analysis of calixarene derivatives 12 (Fig. 1) and 14
(Fig. 2) gave unsatisfactory results. Much better results were obtained in the negative-
ion mode, following the general observations made previously with compounds 11 and
13 [38]. Compound 12 exhibited mainly dicharged species at m/z 521.19, 532.16, and
543.24 a.m.u., corresponding to the loss of 4, 3, and 2 Na ions, respectively, balanced
when necessary by the gain of 2 or 1 protons. At a lower intensity, monocharged species

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Fig. 1. Negative-ion-mode ESI mass spectrum of calixarene 12
were detected at m/z 1109.58, 1086.52, 1064.59, and 1042.61 a.m.u., corresponding here
to the loss of 1, 2, 3, or 4 Na ions available, respectively, balanced when necessary by
protonation.
Fig. 2. Negative-ion-mode ESI mass spectrum of calixarene 14

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In the same mode, ESI-MS of compound 14 exhibited, in a m/z domain between 500
and 700 a.m.u., a succession of three di-charged ionic families, one resulting from the
loss of 1 to 8 Na ions, one from the loss of two carboxylate groups and 5 to 8 Na ions,
and one from the loss of four carboxylate groups and 5 to 8 Na ions, balanced by
protonation.
All monomeric species gave analyses in accordance with the proposed formulae.
1
The acids 22 – 25 were characterized by H-NMR and elemental analysis.
Positive-ion-mode ESI-MS analysis of monomeric salts 26 – 29 indicated the
presence of only the mono-charged species, involving at least, in each case, an adduct
of a Na cation.
Biological Evaluations. – Antibacterial activities, i.e., minimum inhibitory concen-
trations (MIC), of H2O-soluble calixarenes 11 – 15, and of their corresponding
monomers 26 – 30 were determined against Gram-negative (Escherichia coli ATCC
25922 and Pseudomonas aeruginosa ATCC 27853) and Gram-positive (Staphylococcus
aureus ATCC 25923 and ATCC 29213, and Enterococcus faecalis ATCC 29212)
reference strains, according to microdilution protocols performed in 96-well U shape
microtiter plates [41][42].
The results compiled in Table 3 show that, except for the pair calixarene 14/S. aureus
ATCC 25923, none of the compounds displays any antibacterial activity under 256 mg/
ml. At this stage of the study, one can suggest an effective discrimination between
antiviral and antibacterial activities, in favor of the former. Compound 14 exhibits its
activity at a MIC value of 128 mg/ml, corresponding to a 70 mm concentration; it is at
least two times (mass ratio) and six times (molar ratio) more active than its monomer
29 (>256 mg/ml, 462 mm). This could be interpreted, but to a much lesser extent, as a
positive effect of cyclooligomerization, as already observed for guanidinium derivatives
[24].
Conclusions. – We have prepared a new series of H2O-soluble anionic calixarenes
bearing in alternate positions at the lower rim two 2,2’-bipyridine or 2,2’-bithiazole
Table 3. Minimum Inhibitory Concentration (MIC) Valuesa) in mg/ml ([mm])
Compound (MW) E. coli
ATCC 25922
S. aureus
ATCC 25923
S. aureus
ATCC 29213
E. faecalis
ATCC 29212
P. aeruginosa
ATCC 27853
11 (1315.9)
26 (385.5)
12 (1299.6)
27 (415.6)
13 (2433.9)
28 (618.8)
14 (1815.2)
29 (554.4)
15 (931.2)
30 (184.1)
> 256 (> 194) > 256 (> 194) > 256 (> 194) > 256 (> 194) > 256 (> 194)
> 256 (> 664) > 256 (> 664) > 256 (> 664) > 256 (> 664) > 256 (> 664)
> 256 (> 197) > 256 (> 197) > 256 (> 197) > 256 (> 197) > 256 (> 197)
> 256 (> 616) > 256 (> 616) > 256 (> 616) > 256 (> 616) > 256 (> 616)
> 256 (> 105) > 256 (> 105) > 256 (> 105) > 256 (> 105) > 256 (> 105)
> 256 (> 414) > 256 (> 414) > 256 (> 414) > 256 (> 414) > 256 (> 414)
> 256 (> 141)
128 (70.5)
> 256 (> 141) > 256 (> 141) > 256 (> 141)
> 256 (> 462) > 256 (> 462) > 256 (> 462) > 256 (> 462) > 256 (> 462)
> 256 (> 275) > 256 (> 275) > 256 (> 275) > 256 (> 275) > 256 (> 275)
> 256 (> 1390) > 256 (> 1390) > 256 (> 1390) > 256 (> 1390) > 256 (> 1390)
a) Obtained by broth microdilution method, according to NCCLS (formerly CLSI) guideline (see Exper.
Part).

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subunits; their monomeric analogs were also prepared. These carboxylated species do
not display clear antibacterial activities. In contrast to the previously described
guanidino analogs, the cyclotetramerization of inactive 2-(4-hydroxyphenyl)acetic acid
and some ether derivatives to their calix[4]arene analogs does not result in an increase
in or acquisition of any antibacterial activity, at least at useful therapeutic levels.
Nevertheless, the calixarene species 14 integrating two 2,2’-bithiazole-5,5’-dicarbox-
ylate subunits exhibits activity against the S. aureus ATCC 25923 strain. It is under
current investigation to determine the role of its structure (acetate and carboxylated
2,2’-bithiazole groups) in relation to its selective activity, and to develop more potent
derivatives.
Experimental Part
General. Chemistry: All commercially available products were used without further purification
unless otherwise specified. TLC: silica gel plates (SiO2, ref. 1.05554; Al2O3, ref. 1.05581, Merck). M.p.:
Electrothermal 9200 cap. apparatus; uncorrected. UV/VIS Spectra : SAFAS UV mc2 apparatus, lmax in
1
nm, e in molꢀ1 dm3 cmꢀ1. IR Spectra: Bruker Vector 22 apparatus (KBr); ˜n in cmꢀ1. H- and 13C-NMR
spectra: Bruker DRX 400; d in ppm, J in Hz. ES-MS: Micromass Platform II apparatus, at the Service
´
Commun de Spectrometrie de Masse Organique, Nancy; in m/z. Elemental analyses: Service de
Microanalyse, Nancy. Dialysis were performed on Float-A-Lyser, cellulose acetate, molecular weight cut
off (MWCO) 100 D.
For each calixarene derivative, A denotes the unsubstituted phenol ring, B the substituted one; C-
atom numbering in heterocycles was defined as shown in Scheme 1.
Biology. The drugs were prepared in sterile dist. H2O and inoculums in MuellerꢀHinton medium.
Bacteria were grown in MuellerꢀHinton broth (Difco, 275730), or MuellerꢀHinton agar (Difco, 225250);
purity of isolates was checked at the time of every test by examination of colony morphology and Gram
staining. For MIC determination experiments, bacteria were inoculated in 96-well U shape microtiter
plates to yield a final inoculum of 1 ꢁ 105 colony-forming units (CFU)/ml. Then, various concentrations
of the drugs were added. The cultures were grown for 18 – 24 h at 358. The resulting bacterial growth was
measured with an ELISA plate reader (Multiskan EX, Thermo Electron Corporation, France) at a
wavelength of 540 nm. Each MIC value was determined three times, involving three blanks (medium,
medium þ drug, medium þ bacteria).
Calixarene Esters: General Procedure for Compounds 7 and 9. A suspension of tetraethyl ester 2
(1 equiv.) and K2CO3 (1 equiv.) in dry MeCN was refluxed under Ar during 30 min. The halogenomethyl
derivative (2 equiv.) was then added, and reflux was continued during ca. 6 h (TLC monitoring). After
cooling to r.t., the solvent was evaporated to dryness, and the resulting solid material was dissolved in
CH2Cl2. The insoluble inorg. materials were filtered off, and the org. phase was concentrated and then
chromatographed to give the substituted ester.
Tetraethyl
25,27-Dihydroxy-26,28-bis[(6’-methyl-2,2’-bipyridin-6-yl)methoxy]calix[4]arene-
5,11,17,23-tetraacetate (¼ Tetraethyl 2,2’,2’’,2’’’-{25,27-Dihydroxy-26,28-bis[(6’-methyl-2,2’-bipyridin-6-
yl)methoxy]pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3(28),4,6,9(27),10,12,15(26),16,18,21,23-do-
decaene-5,11,17,23-tetrayl}tetraacetate; 7). From 2 (0.1 g, 0.13 mmol), K2CO3 (0.018 g, 0.13 mmol),
MeCN (10 ml), and 6-(bromomethyl)-6’-methyl-2,2’-bipyridine (3; 0.068 g, 0.26 mmol). TLC Monitor-
ing: SiO2; CH2Cl2/MeOH 98 :2. Chromatography: Chromatotron, Al2O3, 1-mm thickness, CH2Cl2/
hexane 4 :1: 7 (0.09 g, 0.074 mmol; 57%). White powder. M.p. 90 – 918. IR (KBr): 1733.1 (C¼O). UV/
VIS (CH2Cl2): 286 (49226). 1H-NMR (400 MHz, CDCl3): 1.21 (t, J ¼ 7.3, 2 MeCH2O of B); 1.27 (t, J ¼ 7.3,
2 MeCH2O of A); 2.65 (s, 2 Meꢀbpy); 3.33 (s, 2 CH2COOEt of B); 3.43, 4.42 (AB, JAB ¼ 13.1, 4
ArCH2Ar); 3.51 (s, 2 CH2COOEt of A); 4.07 – 4.20 (m, 4 MeCH2O); 5.23 (s, 2 OCH2ꢀbpy); 6.88 (s, 4
arom. H of B); 7.04 (s, 4 arom. H of A); 7.13 (d, J ¼ 7.6, 2 HꢀC(5’) of bpy); 7.57 – 7.66 (m, 2 HꢀC(4), 2
HꢀC(4’) of bpy); 8.04 – 8.11 (m, 2 HꢀC(5) of bpy, 2 OH); 8.20 (d, J ¼ 7.8, 2 HꢀC(3’) of bpy); 8.38 (d, J ¼
7.3, 2 HꢀC(3) of bpy). 13C-NMR (100 MHz, CDCl3): 14.5 (MeCH2O of B); 14.7 (MeCH2O of A); 25.0

Helvetica Chimica Acta – Vol. 95 (2012)
1381
(Meꢀbpy); 32.0 (ArCH2Ar); 41.0 (CH2COOEt of A); 41.3 (CH2COOEt of B); 61.1, 61.2 (MeCH2O of A
and B); 79.2 (OCH2ꢀbpy); 118.7 (C(3’) of bpy); 120.5 (C(3) of bpy); 121.4 (C(5) of bpy); 123.7 (C(5’) of
bpy); 124.8 (Cp of A); 128.1 (Co of A); 129.9 (Cm of A); 130.6 (Cm of B); 131.3 (Cp of B); 133.5 (Co of B);
137.5 (C(4’) of bpy); 138.6 (C(4) of bpy); 151.7 (Cipso of B); 153.0 (Cipso of A); 155.7 (C(2’) of bpy); 156.3
(C(2) of bpy); 156.6 (C(6) of bpy); 158.3 (C(6’) of bpy); 172.1 (COOEt of B); 172.6 (COOEt of A). ES-
MS (pos.): 1133.94 ([M þ H]þ). Anal. calc. for C68H68N4O12 · CH2Cl2 (1218.23): C 68.03, H 5.79, N 4.59;
found: C 67.83, H 5.71, N 4.66.
Tetraethyl 25,27-Dihydroxy-26,28-bis{[4,4’-bis(methoxycarbonyl)-6’-methyl-2,2’-bipyridin-6-yl]me-
thoxy}calix[4]arene-5,11,17,23-tetraacetate (¼ Tetramethyl 6,6’-{[5,11,17,23-Tetrakis(2-ethoxy-2-oxoeth-
yl)-26,28-dihydroxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3(28),4,6,9(27),10,12,15(26),16,18,
21,23-dodecaene-25,27-diyl]bis(oxymethanediyl)}bis(6’-methyl-2,2’-bipyridine-4,4’-dicarboxylate); 9).
From 2 (0.1 g, 0.13 mmol), K2CO3 (0.018 g, 0.13 mmol), MeCN (10 ml), dimethyl 6-(bromomethyl)-6’-
methyl-2,2’-bipyridine-4,4’-dicarboxylate (5; 0.098 g, 0.26 mmol). TLC Monitoring: Al2O3, CH2Cl2. After
filtration of insoluble inorg. materials, addition to the CH2Cl2 soln. of an excess MeOH resulted in the
formation of a gel that was filtered and dried prior chromatography. Chromatography: column, Al2O3;
CH2Cl2: 9 (0.102 g, 0.075 mmol, 57%). White powder. M.p. 108 – 1098. IR (KBr): 1733.2 (C¼O). UV/VIS
(CH2Cl2): 286 (61139). 1H-NMR (400 MHz, CDCl3): 1.22 (t, J ¼ 7.3, 2 MeCH2O of A or B); 1.28 (t, J ¼ 7.3,
2 MeCH2O of B or A); 2.76 (s, 2 Meꢀbpy); 3.38 (s, 2 CH2COOEt of B); 3.45 (s, 2 C(4’)ꢀCOOMe); 3.47,
4.41 (AB, JAB ¼ 13.1, 4 ArCH2Ar); 3.51 (s, 2 CH2COOEt of A); 3.98 (s, 2 C(4)ꢀCOOMe); 4.09 – 4.21 (m, 4
MeCH2O); 5.42 (s, 2 OCH2ꢀbpy); 6.94 (s, 4 arom. H of B); 7.05 (s, 4 arom. H of A); 7.76 (s, 2 HꢀC(5’) of
bpy); 8.32 (s, 2 OH); 8.74 (s, 2 HꢀC(3’) of bpy); 8.78 (s, 2 HꢀC(3) of bpy); 9.10 (s, 2 HꢀC(5) of bpy).
13C-NMR (100 MHz, CDCl3): 14.6, 14.7 (MeCH2O of A and B); 25.0 (Meꢀbpy); 32.1 (ArCH2Ar); 41.0
(CH2COOEt of A); 41.3 (CH2COOEt of B); 52.6 (C(4)ꢀCOOMe); 53.1 (C(4’)ꢀCOOMe); 61.1, 61.2
(MeCH2O of A and B); 78.8 (OCH2ꢀbpy); 117.9 (C(3’) of bpy); 120.0 (C(3) of bpy); 121.8 (C(5) of bpy);
123.3 (C(5’) of bpy); 124.8 (Cp of A); 127.9 (Co of A); 129.8 (Cm of A); 130.7 (Cm of B); 131.5 (Cp of B);
133.6 (Co of B); 139.1, 139.7 (C(4), C(4’) of bpy); 151.7 (Cipso of B); 153.1 (Cipso of A); 156.1 (C(2’) of
bpy); 156.2 (C(2) of bpy); 158.7 (C(6) of bpy); 159.8 (C(6’) of bpy); 165.4 (C(4’)ꢀCOOMe); 166.4
(C(4)ꢀCOOMe); 172.1 (COOEt of B); 172.6 (COOEt of A). ES-MS (pos.): 1364.75 ([M þ H]þ). Anal.
calc. for C76H76N4O20 (1365.44): C 66.85, H 5.61, N 4.10; found: C 66.95, H 5.60, N 4.12.
Calixarene Salts via Acids: General Procedure for Compounds 11 – 15. The ester (1 equiv.) was
suspended in a 1:1 mixture EtOH/H2O. Solid NaOH (40 equiv.) was added to the mixture, which was
maintained at reflux (TLC monitoring). The soln. was cooled to r.t., and EtOH was evaporated under
vacuum; the resulting aq. soln. was acidified with 1m HCl, affording a precipitate that was filtered (with or
without centrifugation) and dried (P2O5) to give the corresponding acid. The latter was suspended in dist.
H2O, and 0.1m aq. NaOH was carefully added until solubilization was complete (pH-meter monitoring).
The resulting soln. was filtered and then lyophilized. The resulting solid was dissolved in dist. H2O,
dialyzed, and finaly lyophilized to give the corresponding sodium salt.
Tetrasodium 25,27-Dihydroxy-26,28-bis[(6’-methyl-2,2’-bipyridin-6-yl)methoxy]calix[4]arene-
5,11,17,23-tetraacetate (¼ Tetrasodium 2,2’,2’’,2’’’-{25,27-Dihydroxy-26,28-bis[(6’-methyl-2,2’-bipyridin-6-
yl)methoxy]pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3(28),4,6,9(27),10,12,15(26),16,18,21,23-do-
decaene-5,11,17,23-tetrayl}tetraacetate; 11). From 7 (0.24 g, 0.197 mmol), EtOH/H2O (30 ml), and NaOH
(0.34 g, 8.61 mmol), reflux 7 h. TLC Monitoring (Al2O3; CH2Cl2): tetra acid (0.21 g, 92%), then: H2O
(30 ml), 0.1m NaOH; final pH 8.25: 11 (0.206 g, 78%). Woolly white powder. Tetra acid: White solid.
1H-NMR (100 MHz, (D6)DMSO): 2.55 (s, 2 Meꢀbpy); 3.27 (s, 2 CH2COOH of A or B); 3.38 (s, 2
CH2COOH of A or B); 3.44, 3.32 (AB, JAB ¼ 13.1, 4 ArCH2Ar); 5.16 (s, 2 OCH2ꢀbpy); 6.93 (s, 4 arom. H
of A or B); 7.07 (s, 4 arom. H of A or B); 7.24 (d, J ¼ 7.3, 2 arom. H of bpy); 7.60 – 7.72 (m, 4 arom. H of
bpy); 7.81 (d, J ¼ 7.5, 2 arom. H of bpy); 8.19 (d, J ¼ 8.0, 2 arom. H of bpy); 8.29 – 8.35 (m, 6 arom. H of
bpy, 2 OH). Salt 11: see [38].
Octasodium 25,27-Bis[(4,4’-dicarboxy-6’-methyl-2,2’-bipyridin-6-yl)methoxy]-26,28-dihydroxyca-
lix[4]arene-5,11,17,23-tetraacetate (¼Octasodium 6,6’-{[5,11,17,23-Tetrakis(carboxylatomethyl)-26,28-di-
hydroxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3(28),4,6,9(27),10,12,15(26),16,18,21,23-dodeca-
ene-25,27-diyl]bis(oxymethanediyl)}bis(6’-methyl-2,2’-bipyridine-4,4’-dicarboxylate); 13). From 9 (0.29 g,
0.21 mmol), EtOH/H2O (20 ml), and NaOH (0.34 g, 8.61 mmol), reflux 24 h. TLC Monitoring (Al2O3,

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CH2Cl2), centrifugation: octa-acid (0.22 g, 94%); then: H2O (40 ml), 0.1m NaOH, initial pH 2.30, final
pH 7.92: 13 (0.26 g, 53%). Woolly light yellow powder. Octa-acid: Light yellow powder. 1H-NMR
(400 MHz, (D6)DMSO): 2.66 (s, 2 Meꢀbpy); 3.10 – 3.66 (m, 4 H of ArCH2Ar, 4 CH2COOH); 4.28 (d, J ¼
12.8, 4 H of ArCH2Ar); 5.38 (s, 2 OCH2ꢀbpy); 6.96 (s, 4 arom. H of A or B); 7.07 (s, 4 arom. H of A or B);
7.71, 8.50, 8.53, 8.65, 9.07 (5 s, 8 arom. H of bpy, 2 OH). Salt 13: see [38].
Tetrasodium 25,27-Dihydroxy-26,28-bis[(4’-methyl-2,2’-bithiazol-4-yl)methoxy]calix[4]arene-
5,11,17,23-tetraacetate (¼ Tetrasodium 2,2’,2’’,2’’’-{25,27-Dihydroxy-26,28-bis[(4’-methyl-2,2’-bithiazol-4-
yl)methoxy]pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3(28),4,6,9(27),10,12,15(26),16,18,21,23-do-
decaene-5,11,17,23-tetrayl}tetraacetate; 12). In addition to [30]: flame photometry: calc. for
C52H40N4Na4O12S4 · 6 H2O · NaCl (1299.60): Na 8.84; found: Na 8.95. ES-MS (neg.): 1109.58 ([M ꢀ
Na]ꢀ), 1087.59 ([M ꢀ 2 Na þ H]ꢀ), 1065.61 ([M ꢀ 3 Na þ 2 H]ꢀ), 1043.62 ([M ꢀ 4 Na þ 3 H]ꢀ), 543.24
([M ꢀ 2 Na]2ꢀ), 532.16 ([M ꢀ 3 Na þ H]2ꢀ), 521.19 ([M ꢀ 4 Na þ 2 H]2ꢀ).
Octasodium 25,27-Bis[(5,5’-dicarboxy-4’-methyl-2,2’-bithiazol-4-yl)methoxy]-26,28-dihydroxyca-
lix[4]arene-5,11,17,23-tetraacetate (¼Octasodium 4,4’-{[5,11,17,23-Tetrakis(carboxylatomethyl)-26,28-di-
hydroxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3(28),4,6,9(27),10,12,15(26),16,18,21,23-dodeca-
ene-25,27-diyl]bis(oxymethanediyl)}bis(4’-methyl-2,2’-bithiazole-5,5’-dicarboxylate); 14). In addition to
[30]: flame photometry: calc. for C56H36N4Na8O20S4 · 5 NaCl · 7 H2O (1815.40): Na 16.45; found: Na 16.08.
ES-MS (neg.): 685.88 ([M ꢀ Na þ H]2ꢀ), 674.92 ([M ꢀ 2 Na]2ꢀ), 663.90 ([M ꢀ 3 Na þ H]2ꢀ), 652.93
([M ꢀ 4 Na þ 2 H]2ꢀ), 641.97 ([M ꢀ 5 Na þ 3 H]2ꢀ), 631.01 ([M ꢀ 6 Na þ 4 H]2ꢀ), 619.92 ([M ꢀ 7 Na þ
5 H]2ꢀ), 609.02 ([M ꢀ 8 Na þ 6 H]2ꢀ), 598.00 ([M ꢀ 5 Na þ 3 H ꢀ 2 (COO)]2ꢀ), 586.97 ([M ꢀ 6 Na þ 4
H ꢀ 2 (COO)]2ꢀ), 575.95 ([M ꢀ 7 Na þ 5 H ꢀ 2 (COO)]2ꢀ), 564.99 ([M ꢀ 8 Na þ 6 H ꢀ 2 (COO)]2ꢀ),
554.02 ([M ꢀ 5 Na þ 3 H ꢀ 4 (COO)]2ꢀ), 543.06 ([M ꢀ 6 Na þ H ꢀ 4 (COO)]2ꢀ), 532.04 ([M ꢀ 7 Na þ 5
H ꢀ 4 (COO)]2ꢀ), 521.07 ([M ꢀ 8 Na þ 6 H ꢀ 4 (COO)]2ꢀ).
Tetrasodium 25,27,26,28-Tetrahydroxycalix[4]arene-5,11,17,23-tetraacetate (¼ Tetrasodium 2,2’,2’’,2’’’-
[25,26,27,28-Tetrahydroxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3(28),4,6,9(27),10,12,15(26),16,
18,21,23-dodecaene-5,11,17,23-tetrayl]tetraacetate; 15). In addition to [30]: flame photometry: calc. for
C36H28Na4O12 · 1.5 NaCl · 5.5 H2O (931.21): Na 13.58; found: Na 14.03.
Monomer Esters: General Procedure for Compounds 18 – 21. A suspension of methyl 2-(4-
hydroxyphenyl)acetate (16; 1 equiv.) and K2CO3 (1 equiv.) in dry MeCN was refluxed under Ar during
30 min. The halogenoalkyl derivative was then added, and reflux was continued during ca. 4 h (TLC
monitoring). After cooling to r.t., the solvent was evaporated to dryness, and the resulting solid material
was dissolved in CH2Cl2. The inorg. materials were filtered off, and the org. phase was chromatographed
to give the desired ester.
Methyl 2-{4-[(6’-Methyl-2,2’-bipyridin-6-yl)methoxy]phenyl}acetate (18). From 16 (0.1 g,
0.60 mmol), K2CO3 (0.08 g, 0.60 mmol), MeCN (30 ml), 3 (0.16 g, 0.60 mmol), reflux 4 h (TLC
monitoring: Al2O3; CH2Cl2). Chromatography: Al2O3; CH2Cl2: 18 (0.16 g, 0.46 mmol, 77%). White
1
powder. M.p. 90 – 918. IR (KBr): 1731.2 (C¼O). UV/VIS (CH2Cl2): 288 (16805). H-NMR (400 MHz,
CDCl3): 2.65 (s, Meꢀbpy); 3.57 (s, CH2COOMe); 3.68 (s, COOMe); 5.27 (s, OCH2ꢀbpy); 6.98 (d, J ¼ 8.6,
2 arom. H); 7.15 – 7.24 (m, 3 arom. H of C6H4, bpy); 7.51 (d, J ¼ 7.5, 1 H of bpy); 7.72 (t, J ¼ 7.7, 1 H of
bpy); 7.82 (t, J ¼ 7.8, 1 H of bpy); 8.20 (d, J ¼ 7.8, 1 H of bpy); 8.34 (d, J ¼ 7.8, 1 H of bpy). 13C-NMR
(100 MHz, CDCl3): 25.1 (Meꢀbpy); 40.7 (CH2COOMe); 52.4 (COOMe); 71.3 (OCH2ꢀbpy); 115.4 (Cm);
118.6, 120.4, 121.4, 123.7 (C(3,3’,5,5’) of bpy); 126.9 (Cp); 130.8 (Co); 137.5, 138.0 (C(4,4’) of bpy); 157.2
(Cipso); 155.8, 156.3, 158.1, 158.3 (C(6,6’,2,2’) of bpy); 172.7 (C¼O). ES-MS (pos.): 347.70 ([M þ H]þ),
289.40 ([M ꢀ COOMe þ H]þ). Anal. calc. for C21H20N2O3 · 0.1 H2O (350.20): C 72.02, H 5.81, N 8.00;
found: C 71.89, H 5.81, N 7.74.
Methyl 2-{4-[(4’-Methyl-2,2’-bithiazol-4-yl)methoxy]phenyl}acetate (19). From 16 (0.1 g,
0.60 mmol), K2CO3 (0.08 g, 0.60 mmol), MeCN (30 ml), 4-(bromomethyl)-4’-methyl-2,2’-bithiazole (4;
0.16 g, 0.58 mmol), reflux 7 h (TLC monitoring: Al2O3; CH2Cl2). Chromatography: Al2O3, CH2Cl2: 19
(0.10 g, 0.27 mmol, 46%). White powder. M.p. 101 – 1028. IR (KBr): 1742.1 (C¼O). UV/VIS (CH2Cl2):
1
330 (16950). H-NMR (400 MHz, CDCl3): 2.53 (s, Meꢀbtz); 3.58 (s, CH2COOMe); 3.69 (s, COOMe);
5.24 (s, OCH2ꢀbtz); 6.96 (d, J ¼ 8.3, 2 arom. H); 7.00 (s, 1 H of btz); 7.21 (d, J ¼ 8.1, 2 arom. H); 7.40 (s,
1 H of btz). 13C-NMR (100 MHz, CDCl3): 17.5 (Meꢀbtz); 40.7 (CH2COOMe); 52.4 (CH2COOMe); 66.7
(OCH2ꢀbtz); 115.3 (Cm); 116.3, 118.1 (C(5,5’) of btz); 127.1 (Cp); 130.8 (Co); 157.9 (Cipso); 154.2, 154.7,

Helvetica Chimica Acta – Vol. 95 (2012)
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160.8, 162.2 (C(2,2’,4,4’) of btz); 172.6 (C¼O). ES-MS (pos.): 360.00 ([M þ H]þ). Anal. calc. for
C17H16N2O3S2 · 0.5 H2O (369.45): C 55.26, H 4.64, N 7.58, S 17.35; found: C 55.86, H 4.40, N 7.68, S 17.47.
Dimethyl 6-{[4-(2-Methoxy-2-oxoethyl)phenoxy]methyl}-6’-methyl-2,2’-bipyridine-4,4’-dicarboxylate
(20). From 16 (0.24 g, 1.45 mmol), K2CO3 (0.20 g, 1.45 mmol), MeCN (50 ml), 5 (0.55 g, 1.45 mmol),
reflux 7 h (TLC monitoring: Al2O3; CH2Cl2/hexane 90 :10). Chromatography: Al2O3; CH2Cl2/hexane
9 :1: 20 (0.67 g, 1.41 mmol, 97%). White powder. M.p. 160 – 1618. IR (KBr): 1736.8 (C¼O). UV/VIS
1
(CH2Cl2): 310 (17074). H-NMR (400 MHz, CDCl3): 2.79 (s, Me – bpy), 3.60 (s, CH2COOMe); 3.72 (s,
CH2COOMe); 4.03 (s, COOMeꢀbpy); 4.03 (s, COOMeꢀbpy); 5.37 (s, OCH2ꢀbpy); 7.04 (d, J ¼ 8.8, 2
arom. H); 7.25 (d, J ¼ 8.8, 2 arom. H); 7.82 (s, 1 H of bpy); 8.15 (s, 1 H of bpy); 8.79 (s, 1 H of bpy); 8.94 (s,
1 H of bpy). 13C-NMR (100 MHz, CDCl3): 25.0 (Meꢀbpy); 40.7 (CH2COOMe); 52.4 (CH2COOMe);
53.1 (COOMeꢀbpy); 53.1 (COOMeꢀbpy); 71.0 (OCH2ꢀbpy); 115.4 (Cm or Co); 118.1, 120.0, 121.0, 123.3
(C(3,3’,5,5’) of bpy); 127.2 (Cp); 130.8 (Cm or Co); 139.1, 139.8 (C(4,4’) of bpy); 157.9 (Cipso); 156.1, 156.6,
158.7, 159.8 (C(2,2’,6,6’) of bpy); 166.1, 166.4 (C¼O of bpy); 172.6 (C¼O). ES-MS (pos.): 463.00 ([M þ
H]þ), 405.00 ([M ꢀ COOMe þ H]þ), 300.00 ([bpy(COOMe)2 þ H]þ). Anal. calc. for C25H24N2O7 · 0.5
H2O (473.47): C 63.42, H 5.32, N 5.91; found: C 63.49, H 5.08, N 5.89.
Diethyl 4-{[4-(2-Methoxy-2-oxoethyl)phenoxy]methyl}-4’-methyl-2,2’-bithiazole-5,5’-dicarboxylate
(21). From 16 (0.20 g, 1.18 mmol), K2CO3 (0.15 g, 1.30 mmol), MeCN (30 ml), diethyl 4-(bromo-
methyl)-4’-methyl-2,2’-bithiazole-5,5’-dicarboxylate (6; 0.55 g, 1.30 mmol), reflux 4 h (TLC monitoring;
Al2O3, CH2Cl2). Chromatography: Al2O3, CH2Cl2/hexane 3 :1: 21 (0.43 g, 0.85 mmol, 72%). Yellow
powder. M.p. 113 – 1148. IR (KBr): 1719.8 (C¼O). UV/VIS (CH2Cl2): 350 (26193). 1H-NMR (400 MHz,
CDCl3): 1.35 (t, J ¼ 7.0, MeCH2O); 1.38 (t, J ¼ 7.0, MeCH2O); 2.78 (s, Meꢀbtz); 3.57 (s, CH2COOMe);
3.68 (s, COOMe), 4.30 – 4.40 (m, 2 MeCH2O); 5.49 (s, OCH2ꢀbtz); 7.01 (d, J ¼ 8.6, 2 arom. H); 7.20 (d,
J ¼ 8.6, 2 arom. H). 13C-NMR (100 MHz, CDCl3): 14.5, 14.6 (MeCH2O); 17.9 (Meꢀbtz); 40.7
(CH2COOMe); 52.4 (COOMe); 62.0, 62.5 (COOCH2Me); 64.4 (OCH2ꢀbtz); 115.6 (Cm or Co); 125.4,
127.1, 128.4 (C(5,5’), Cp); 130.7 (Cm or Co); 158.2, 158.8, 161.3, 161.6, 161.8 (C(4,4’,2,2’), Cipso); 162.2, 163.4
(COOEt); 172.7 (COOMe). ES-MS (pos.): 505.12 ([M þ H]þ); 527.14 ([M þ Na]þ). Anal. calc. for
C23H24N2O7S2 (504.58): C 54.75, H 4.79, N 5.55, S 12.70; found: C 54.76, H 4.67, N 5.58, S 12.80.
Monomer Salts via Acids: General Procedure for Compounds 26 – 30. The ester (1 equiv.) was
suspended in a mixture of EtOH and H2O. A soln. of NaOH (10 equiv.) in H2O was added, and the
resulting mixture was refluxed during 7 h. The soln. was cooled to r.t., and EtOH was evaporated under
vacuum; the resulting aq. soln. was acidified with 1m HCl, affording the corresponding acid as a
precipitate, which was filtered, then washed with H2O, and dried. The acid derivative was then suspended
in dist. H2O, and 0.1m aq. NaOH was carefully added until solubilization was complete (pH-meter
monitoring). The resulting soln. was filtered and then lyophilized to give the desired sodium salt.
Sodium 2-{4-[(6’-Methyl-2,2’-bipyridin-6-yl)methoxy]phenyl}acetate (26). From 18 (0.30 g,
0.86 mmol), EtOH/H2O 1:1 (30 ml), NaOH (0.34 g, 8.61 mmol) in H2O (10 ml): 22 (0.20 g, 0.60 mmol,
70%); then, 22 (0.17 g, 0.51 mmol), H2O (30 ml), 0.1m NaOH, final pH 7.70. 26 (0.19 g, 0.49 mmol, 96%
vs. acid, 67% vs. 18).
1
Data of 22. White powder. IR (KBr): 1702.9 (C¼O). H-NMR (400 MHz, (D6)DMSO): 2.58 (s,
Meꢀbpy); 3.49 (s, CH2COOH); 5.26 (s, OCH2ꢀbpy); 7.01 (d, J ¼ 8.6, 2 arom. H); 7.19 (d, J ¼ 8.6, 2 arom.
H); 7.33 (d, J ¼ 7.6, 1 H of bpy); 7.55 (d, J ¼ 7.4, 1 H of bpy); 7.84 (t, J ¼ 7.8, 1 H of bpy); 7.97 (t, J ¼ 7.7, 1 H
of bpy); 8.20 (d, J ¼ 7.8, 1 H of bpy); 8.32 (d, J ¼ 7.8, 1 H of bpy). Anal. calc. for C20H18N2O3 (334.37): C
71.84, H 5.42, N 8.37; found: C 71.60, H 5.40, N 8.35.
Data of 26. Woolly white powder. M.p. 200 – 2018. IR (KBr): 1583.1, 1571.9 (C¼N and C¼O). UV/
1
VIS (H2O): 286 (14346). H-NMR (400 MHz, D2O): 2.62 (s, Meꢀbpy); 3.49 (s, CH2COOH); 5.33 (s,
OCH2ꢀbpy); 7.07 (d, J ¼ 7.8, 2 arom. H); 7.26 (d, J ¼ 8.1, 2 arom. H); 7.41 (d, J ¼ 8.1, 1 H of bpy); 7.63 (d,
J ¼ 7.8, 1 H of bpy); 7.79 (d, J ¼ 7.8, 1 H of bpy); 7.85 – 7.95 (m, 2 H of bpy); 8.00 (t, J ¼ 7.6, 1 H of bpy).
1H-NMR (400 MHz, (D6)DMSO): 2.57 (s, Me – bpy); 3.14 (s, CH2COOH); 5.22 (s, OCH2ꢀbpy); 6.90 (d,
J ¼ 8.1, 2 arom. H); 7.15 (d, J ¼ 8.1, 2 arom. H); 7.32 (d, J ¼ 7.5, 1 H of bpy); 7.54 (d, J ¼ 7.5, 1 H of bpy);
7.84 (t, J ¼ 7.7, 1 H of bpy); 7.96 (t, J ¼ 7.7, 1 H of bpy); 8.20 (d, J ¼ 7.8, 1 H of bpy); 8.31 (d, J ¼ 7.8, 1 H of
bpy). 13C-NMR (100 MHz, (D6)DMSO): 24.6 (Meꢀbpy); 45.6 (CH2COONa); 70.7 (OCH2ꢀbpy); 114.3
(Cm); 118.0, 119.7, 122.0, 124.0 (C(3,3’,5,5’) of bpy); 130.5 (Co); 133.1 (Cp); 137.8, 138.4 (C(4,4’) bpy);
156.1 (Cipso); 154.7, 155.3, 157.2, 157.9 (C(6,6’,2,2’) of bpy); 175.1 (COONa). ES-MS (pos.): 379.18 ([M þ

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Helvetica Chimica Acta – Vol. 95 (2012)
Na]þ), 357.21 ([M þ H]þ), 335.30 ([M ꢀ Na þ 2 H]þ). ES-MS (neg.): 333.33 ([M ꢀ Na]ꢀ), 289.39 ([M ꢀ
COONa]ꢀ), 183.41 ([CH2ꢀBpyꢀMe]ꢀ). Anal. calc. for C20H17N2NaO3 · 0.5 NaCl (385.56): C 62.30, H
4.44, N 7.26; found: C 62.24, H 4.81, N 7.19.
Sodium 2-{4-[(4’-Methyl-2,2’-bithiazol-4-yl)methoxy]phenyl}acetate (27). From 19 (0.29 g,
0.79 mmol), EtOH/H2O 0.5 :1 (30 ml), NaOH (0.33 g, 8.18 mmol) in H2O (10 ml). Acidification and
centrifugation: acid 23 (0.28 g, 0.77 mmol, 97%); then H2O (40 ml), 0.1m NaOH, final pH 8.5: 27 (0.30 g,
0.72 mmol, 94% vs. acid, 91% vs. 19).
Data of 23: Pale yellow powder. IR (KBr): 1720.5 (C¼O). 1H-NMR (400 MHz, (D6)DMSO): 2.44
(s, Meꢀbtz); 3.50 (s, CH2COOH); 5.20 (s, OCH2ꢀBtz); 7.01 (d, J ¼ 8.3, 2 arom. H); 7.20 (d, J ¼ 8.3, 2 arom.
H); 7.51 (s, 1 H of btz); 7.89 (s, 1 H of btz); 12.24 (s, COOH). Anal. calc. for C16H14N2O3S2 · 0.5 HCl
(364.66): C 52.73, H 4.42, N: 7.68; found: C 52.74, H 4.33, N 7.66.
Data of 27: Woolly white powder. M.p. 206 – 2068. IR (KBr): 1578 (br., C¼N and C¼O). UV/VIS
(H2O): 331 (14841). 1H-NMR (400 MHz, D2O): 2.46 (s, Meꢀbtz); 3.49 (s, CH2COONa); 5.24 (s,
OCH2ꢀBtz); 7.05 (d, J ¼ 8.1, 2 arom. H); 7.26 (d, J ¼ 8.3, 2 arom. H); 7.32 (s, 1 H of btz); 7.72 (s, 1 H of
btz). 1H-NMR (400 MHz, (D6)DMSO): 2.44 (s, Me – btz); 3.17 (s, CH2COOH); 5.16 (s, OCH2ꢀBtz); 6.90
(d, J ¼ 7.5, 2 arom. H); 7.16 (d, J ¼ 7.5, 2 arom. H); 7.50 (s, 1 H of btz); 7.86 (s, 1 H of btz). 13C-NMR
(100 MHz, (D6)DMSO): 17.0 (Meꢀbtz); 45.4 (CH2COONa); 65.5 (OCH2ꢀbtz); 114.3 (Cm); 117.6, 120.5
(C(5,5’) of btz); 130.4 (Co); 133.0 (Cp); 156.0 (Cipso); 153.8, 154.1, 159.9, 161.2 (C(2,2’,4,4’) of btz); 175.4
(COONa). ES-MS (pos.): 407.13 ([M þ K]þ), 391.12 ([M þ Na]þ), 369.15 ([M þ H]þ), 325.21 ([M ꢀ
COONa þ Na þ H]þ). ES-MS (neg.): 345.21 ([M ꢀ Na]ꢀ), 301.27 ([M ꢀ COONa]ꢀ), 195.29
([CH2ꢀBtzꢀMe]ꢀ). Anal. calc. for C16H13N2NaO3S2 · 0.5 NaCl · H2O (415.62): C 46.23, H 3.63, N 6.74,
S 15.43; found: C 46.59, H 3.47, N 6.76, S 15.27.
Trisodium 6-{[4-(Carboxylatomethyl)phenoxy]methyl}-6’-methyl-2,2’-bipyridine-4,4’-dicarboxylate
(28). From 20 (0.52 g, 1.10 mmol), EtOH/H2O 0.5 :1 (30 ml), NaOH (0.44 g, 11.2 mmol) in H2O
(10 ml): acid 24 (0.46 g, 1.09 mmol, 99%); then H2O (30 ml), 0.1m NaOH, final pH 7.30: 28 (0.53 g,
0.86 mmol, 78%).
Data of 24: White powder. 1H-NMR (400 MHz, (D6)DMSO): 2.69 (s, Meꢀbpy), 3.50 (s,
CH2COOMe); 5.38 (s, OCH2ꢀbpy); 7.06 (d, J ¼ 8.1, 2 arom. H); 7.20 (d, J ¼ 7.8, 2 arom. H); 7.79 (s,
1 H of bpy); 7.98 (s, 1 H of bpy); 8.67 (s, 1 H of bpy); 8.77 (s, 1 H of bpy). Anal. calc. for C22H18N2O7
(422.39): C 62.55, H 4.29, N 6.63; found: C 62.71, H 4.31, N 6.73.
Data of 28: Woolly white powder. M.p. > 2908 (dec.). IR (KBr): 3406.3 (COONa), 1606.4, 1559.69
(br., C¼N and C¼O). UV/VIS (H2O): 302 (12676). 1H-NMR (400 MHz, D2O): 2.70 (s, Meꢀbpy), 3.50 (s,
CH2COOMe); 5.41 (s, OCH2ꢀbpy); 7.12 (d, J ¼ 8.1, 2 arom. H); 7.27 (d, J ¼ 8.1, 2 arom. H); 7.72 (s, 1 H of
bpy); 7.99 (s, 1 H of bpy); 8.14 (s, 1 H of bpy); 8.27 (s, 1 H of bpy). 13C-NMR (100 MHz, D2O): 23.5
(Meꢀbpy); 44.0 (CH2COONa); 70.6 (OCH2ꢀbpy); 115.6 (Cm or Co); 119.4, 121.3, 121.7, 123.5
(C(3,3’,5,5’) bpy); 130.8 (Cm or Co); 131.1 (Cp); 146.8, 147.4 (C(4,4’) of bpy); 155.6, 156.6, 156.6, 159.9
(C(2,2’,6,6’) of bpy); 157.6 (Cipso); 173.0, 173.5 (COONa of bpy); 181.7 (CH2COONa). ES-MS (pos.):
511.01 ([M þ Na]þ), 489.10 ([M þ H]þ), 445.10 ([M ꢀ 2 Na þ 3 H]þ). ES-MS (neg.): 465.16 ([M ꢀ
Na]ꢀ), 443.19 ([M ꢀ 2 Na þ H]ꢀ), 421.22 ([M ꢀ 3 Na þ 2 H]ꢀ) or ([M ꢀ COONa]ꢀ), 399.00 ([M ꢀ
COONa ꢀ Na þ H]ꢀ), 377.27 ([M ꢀ COONa ꢀ 2 Na þ 2 H]ꢀ), 354.29 ([M ꢀ 2 COONa þ H]ꢀ), 332.31
([M ꢀ 2 COONa ꢀ Na þ 2 H]ꢀ), 288.37 ([M ꢀ 3 COONa þ 2 H]ꢀ). Anal. calc. for C22H15N2Na3O7 · Na-
Cl · 4 H2O (618.81): C 42.70, H 3.74, N 4.52; found: C 42.67, H 3.43, N 4.54.
Trisodium 4-{[4-(Carboxylatomethyl)phenoxy]methyl}-4’-methyl-2,2’-bithiazole-5,5’-dicarboxylate
(29). From 21 (0.38 g, 0.75 mmol), EtOH/H2O 3 :1 (20 ml), NaOH (0.30 g, 7.5 mmol) in H2O (10 ml):
acid 25 (0.20 g, 0.46 mmol, 62%); then acid (0.19 g, 0.44 mmol), H2O (30 ml), 0.1m NaOH, final pH 7.90:
29 (0.20 g, 0.36 mmol, 82%).
Data of 25: Pale yellow powder. IR (KBr): 1686.2 (COOH). 1H-NMR (400 MHz, (D6)DMSO): 2.70
(s, Meꢀbtz); 3.50 (s, CH2COOH); 5.45 (s, OCH2ꢀbtz); 6.99 (d, J ¼ 8.6, 2 arom. H); 7.19 (d, J ¼ 8.6, 2 arom.
H). Anal. calc. for C18H14N2O7S2 (434.45): C 49.76, H 3.24, N 6.44, S 14.76; found: C 49.73, H 3.28, N 6.42,
S 14.80.
Data of 29. Light yellow woolly powder. 1H-NMR (400 MHz, D2O): 2.70 (s, Me – btz), 3.49 (s,
CH2COONa); 5.57 (s, OCH2ꢀbtz); 7.08 (d, J ¼ 8.3, 2 arom. H); 7.25 (d, J ¼ 8.3, 2 arom. H). 13C-NMR

Helvetica Chimica Acta – Vol. 95 (2012)
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(100 MHz, D2O): 16.2 (Meꢀbtz); 43.9 (CH2COONa); 64.1 (OCH2ꢀbtz); 115.6 (Cm or Co); 130.7 (Cm or
Co); 131.0, 133.7, 137.2 (C(5,5’), Cp); 153.4, 156.3, 156.6, 159.6, 161.1 (C(4,4’,2,2’) of btz, Cipso); 167.2, 168.7
(COONa of btz); 181.7 (COONa). ES-MS (pos.): 523.00 ([M þ Na]þ). ES-MS (neg.): 455.13 ([M ꢀ 2
Na þ H]ꢀ), 433.21 ([M ꢀ 3 Na þ 2 H]ꢀ) or ([M ꢀ COONa]ꢀ), 411.22 ([M ꢀ COONa ꢀ Na þ H]ꢀ),
389.23 ([M ꢀ COONa ꢀ 2 Na þ 2 H]ꢀ), 367.30 ([M ꢀ 2 COONa þ H]ꢀ), 345.32 ([M ꢀ 2 COONa ꢀ
Na þ 2 H]ꢀ). Anal. calc. for C18H11N2Na3O7S2 · 3 H2O (554.39): C 38.99, H 3.09, N 5.05; found: C 39.32, H
2.86, N 5.03.
Sodium 2-(4-Hydroxyphenyl)acetate (30): 2-(4-Hydroxyphenyl)acetic acid (17; 1 g, 6.57 mmol) was
suspended in dist. H2O (40 ml), and 0.1m aq. NaOH was carefully added until solubilization was complete
(final pH 8.0). The resulting soln. was filtered and then lyophilized to give 30 (1.14 g, 6.2 mmol, 94%).
White woolly solid. 1H-NMR (400 MHz, D2O): 3.46 (s, CH2); 6.87 (d, J ¼ 8.6, 2 arom. H); 7.18 (d, J ¼ 8.4,
2 arom. H). 1H-NMR (400 MHz, (D6)DMSO): 3.15 (s, CH2); 6.63 (d, J ¼ 8.3, 2 arom. H); 7.00 (d, J ¼ 8.3,
2 arom. H). 13C-NMR (100 MHz, (D6)DMSO): 45.2 (CH2COONa); 115.0 (Co or Cm); 129.5 (Cipso or Cp);
130.2 (Co or Cm); 155.8 (Cipso or Cp); 176.5 (COONa). Anal. calc. for C8H7NaO3 · 0.25 NaOH (184.09): C
52.18, H 3.97; found: C 52.46, H 3.98.
We are grateful to the MRES and CNRS for financial support. The authors thank J.-M. Ziegler, F.
Dupire, and S. Adach for mass measurements and elemental analyses.
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Received January 30, 2012