Monosodium salt of p-tert-butylcalix[4]arene in the reactions with electrophilic reagents. Synthesis and structure of monofunctionalized calix[4]arenes

Article abstract of DOI:10.1007/s10847-012-0109-9

Monosodium salt of p-tert-butylcalix[4]arene reacts with alkyl halides or aroyl chlorides in DMF formed the cone-shaped monoalkyloxycalix[4]arenes or 1,3-diacyloxycalix[4]arenes, respectively. Diacyloxycalix[4]arenes are easily transformed into monoacylox

Full text of DOI:10.1007/s10847-012-0109-9

J Incl Phenom Macrocycl Chem (2012) 74:265–275
DOI 10.1007/s10847-012-0109-9
ORIGINAL ARTICLE
Monosodium salt of p-tert-butylcalix[4]arene in the reactions
with electrophilic reagents. Synthesis and structure
of monofunctionalized calix[4]arenes
•
Olexander A. Yesypenko Vyacheslav I. Boyko Mariia A. Klyachina
•
•
•
Svitlana V. Shishkina Oleg V. Shishkin Volodymyr V. Pyrozhenko
•
•
•
Ivan F. Tsymbal Vitaly I. Kalchenko
Received: 25 July 2011 / Accepted: 4 January 2012 / Published online: 11 February 2012
ꢀ Springer Science+Business Media B.V. 2012
Abstract Monosodium salt of p-tert-butylcalix[4]arene
reacts with alkyl halides or aroyl chlorides in DMF formed
the cone-shaped monoalkyloxycalix[4]arenes or 1,3-dia-
cyloxycalix[4]arenes, respectively. Diacyloxycalix[4]are-
nes are easily transformed into monoacyloxycalix[4]arenes
in the partial cone conformation by interaction with
NaOMe. The influence of intramolecular hydrogen bond-
ing on course of alkylation and acylation reactions as well
as the structure of the synthesized compounds in solution
and crystalline state are discussed.
functions. Due to their capability to recognize, they can
bind and separate similar in properties cations, anions, or
neutral organic molecules. Applications of calixarenes as
chemical sensors, extractants for radioactive waste pro-
cessing, materials for non-linear optics, and bio-active
compounds were reported [2–4].
To increase efficiency and selectivity of calixarene
complexation the functionalization at the wide and/or
narrow rims of the macrocycle is carried out. The alkyl-
ation and acylation of phenolic hydroxyl groups is the most
important method for modification. Monoethers of calixa-
renes are used as starting materials for the synthesis of
di-, three- and tetraheterofunctional host-molecules. The
special attention to the monoalkylation processes associ-
ated with design and synthesis of inherently chiral
calix[4]arenes, which are based on the unsymmetrical array
of different substituents on the calix[4]arene skeleton. Over
the past decade, many inherently chiral calixarenes have
been prepared, and some of them have been applied to
chiral recognition and asymmetric catalysis [5–9]. Mono-
acylcalixarenes considered as convenient model for
studying of the mechanism of acylation/deacylation pro-
teolytic enzymes [10].
Keywords Alkylation ꢀ Acylation ꢀ Conformers ꢀ
Monoalkyloxy-p-tert-butylcalix[4]arenes ꢀ
Monoacyloxy-p-tert-butylcalix[4]arenes ꢀ
1,3-diacyloxy-p-tert-butylcalix[4]arenes
Introduction
Calixarenes [1], which have the unique cape-shaped
structure, are widely used as building blocks for the syn-
thesis of host molecules with different supramolecular
Tert-butyl depleted monoalkoxycalix[4]arenes are
obtained in 75% yield by the reaction of tetrahydroxyca-
lix[4]arene with excess of alkyl halides in presence of one
equivalent of NaOMe [11]. But in the case of p-tert-butyl-
calix[4]arene 1, due to its bad solubility both in polar and
nonpolar solvents, the products of the further (deeper)
alkylation are formed alongside with monoalkylated deriv-
atives [12, 13], and the significant part of the starting tet-
rahydroxycalixarene remains unreacted. Therefore, several
indirect methods are proposed for the synthesis of mono-
alkyloxy-p-tert-butylcalix[4]arenes. These methods involve
preliminary protection of three hydroxyl groups of
O. A. Yesypenko ꢀ V. I. Boyko (&) ꢀ M. A. Klyachina ꢀ
V. V. Pyrozhenko ꢀ I. F. Tsymbal ꢀ V. I. Kalchenko
Institute of Organic Chemistry, National Academy of Sciences
of Ukraine, Murmanska Str 5, Kyiv 02660, Ukraine
e-mail: v_boyko@ioch.kiev.ua
S. V. Shishkina (&) ꢀ O. V. Shishkin
STC ‘‘Institute for Single Crystal’’, National Academy of
Sciences of Ukraine, Lenin Ave 60, Kharkhiv 61001, Ukraine
e-mail: sveta@xray.isc.kharkov.com
O. V. Shishkin
V.N.Karazin Kharkiv National University, 4 Svobody Sq,
Kharkiv 61077, Ukraine
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Alkylation of p-tert-butylcalix[4]arene monosodium
salt 2
tetrahydroxycalixarene [14, 15] or dealkylation of its di- or
tetraalkylated derivatives with iodotrimethylsilane [16] or
aluminum chloride [17]. However, these methods are pre-
paratively inconvenient. Monobenzoyloxycalix[4]arene
was prepared also with high yield by the interaction of
p-tert-butylcalix[4]arene with chlorine anhydrides of ben-
zoic acids at the presence of 15-fold butyl-imidazole excess
[10, 18]. Unfortunately, the configuration of these com-
pounds is not determined unambiguously. Only triflate and
mesylate derivatives are known for monosulfo-p-tert-
butylcalix[4]arenes [19, 20].
The solution of alkyl iodide or alkyl bromide
(6.5–8.0 mmol) in DMF (5 mL) was added to the solution
of the salt 2 obtained in situ from calix[4]arene 1 (1.00 g, a
complex with toluene, 1.35 mmol) in dry DMF (40 mL). In
the case of alkyl bromide the KI (0.03 g) was added. The
reaction mixture was stirred at 60–70 ꢁC for 15–20 h. The
solution was concentrated under reduced pressure to the
volume of 25 mL and treated with 3% HCl (100 mL).
After stirring for 2–3 h the precipitate was filtered off,
washed with water and dried in the air. The product was
refluxed in diethyl ether (20–25 mL) for 1–2 h (in the case
of 3d 10 mL of ethyl acetate were used) and left for
15–20 h at 5–10 ꢁC. The precipitate of tetrahydroxycalix-
arene 1 was filtered off, the solvent was evaporated, residue
was refluxed in methanol (7–10 mL) and cooled at 5 ꢁC for
10–15 h. The precipitate was filtered off and dried in the
air.
It is assumed that the intermediates in the reaction of
hydroxycalixarenes with electrophile (alkyl and acyl
halides, sulfochloride) in the presence of inorganic base are
salts of calix[4]arenes [21]. The salts of tetrahydroxyca-
lix[4]arene with alkaline metals were received earlier
[22–24], but their chemical properties were not investigated.
In this article we investigate behavior of monosodium
salt of p-tert-butylcalix[4]arene in the reactions of alkyl-
ation and acylation.
5,11,17,23-Tetra-tert-butyl-25-methyloxy-26,27,28-tri-
hydroxycalix[4]arene 3a. Yield 0.69 g (77%), Mp
205–206 ꢁC (203–204 ꢁC [16]).
5,11,17,23-Tetra-tert-butyl-25-propyloxy-26,27,28-tri-
hydroxycalix[4]arene 3b. Yield 0.66 g (72%), Mp
238–240 ꢁC (239–240 ꢁC [25]).
5,11,17,23-Tetra-tert-butyl-25-octyloxy-26,27,28-tri-
hydroxycalix[4]arene 3c. Yield 0.63 g (65%), Mp
164–165 ꢁC (164–166 ꢁC [17]).
5,11,17,23-Tetra-tert-butyl-25-ethyloxycarbonylmethyl-
oxy-26,27,28-trihydroxycalix[4]arene 3d. Yield 0.70 g
(71%), Mp 273–274 ꢁC (275–276 ꢁC [12]).
Materials and methods
¨
Melting points were determined on a Boetius apparatus and
1
were uncorrected. The H NMR spectra were recorded on
Varian VXR-300 spectrometer (299.943 MHz), 13C
NMR— on Varian GEMINI 2000 (100.607 MHz), the
internal standard— TMS. IR spectra were recorded on
UR-20 spectrometer. Reactions were carried out in anhy-
drous solvents and in atmosphere of argon.
Acylation of p-tert-butylcalix[4]arene
monosodium salt 2
Synthesis of p-tert-butylcalix[4]arene monosodium
salt 2
The solution of the benzoyl chloride or sulfochloride
(1.50 mmol) in DMF (5 mL) at 30–40 ꢁC was added to the
solution of the salt 2 obtained in situ from calix[4]arene 1
(1.00 g, a complex with toluene, 1.35 mmol) in dry DMF
(40 mL). The reaction mixture was stirred at 30–40 ꢁC for
15–20 h and cooled to 5–10 ꢁC. The precipitate was fil-
tered off, washed with DMF and dried in the air. The
product was purified from tetrahydroxycalix[4]arene 1 by
refluxing in 5 mL of chloroform for 1 h. After cooling for
2–3 h at 5–10 ꢁC calixarene 1 was filtered off, washed with
small amount of the cooled solvent and dried in the air. The
yield of compound 1 was 44–49%. Calix[4]arenes 4b,
c were obtained after removal of the solvent from the fil-
trate. Compound 4a was obtained by crystallization of the
residue from acetonitrile.
A suspension of p-tert-butylcalix[4]arene 1 (1.00 g, a
complex with toluene, 1.35 mmol) and MeONa (0.08 g,
1.48 mmol) in dry DMF (40 mL) was stirred at 60–70 ꢁC
until full dissolution of reagents and then for 1 h. The
solvent was removed in vacuo (0.02-mm Hg, 55–65 ꢁC in a
bath). The solid was washed twice by diethyl ether and
dried in vacuo. The salt 2 was obtained as a solvate with
two molecules of DMF (white solid) in 96% yield (1.21 g).
Mp [ 300 ꢁC (Mp 338–340 ꢁC [23]). IR (KBr), m, cm-1
:
3185 (OH, broad, ass.), 1670 (C = O, DMF); IR (CH2Cl2),
1
m, cm-1: 3190 (OH, broad, ass), 1675 (C = O, DMF). H
NMR (benzene-D6), d: 1.27 (s, 36H, t-Bu), 1.91 and 2.43
(s ? s, 2 9 3H ? 2 9 3H, Me groups of DMF), 3.52
(d, 4H, Ar–CH2eq, 2JHH = 12.3 Hz), 4.83 (d, 4H, Ar–CH2ax
,
2JHH = 12.3 Hz), 7.19 (s, 8H, Ar–H), 7.66 (s, 2 9 1H,
CH = O of DMF), 13.81 (br s, 3H, OH).
5,11,17,23-Tetra-tert-butyl-25,27-bis(40-methylphenyl
sulfonyloxy)-26,28-dihydroxycalix[4]arene 4a. White
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267
Reaction of 25-(40-methylphenylcarboxy) calix[4]arene
solid. Yield 0.340 g (26%), Mp 301–302 ꢁC (acetonitrile).
IR (KBr), m, cm-1: 3560 (OH, broad), 1365 and 1380 (SO2
ass), 1165 (SO2 sim); IR (CH2Cl2), m, cm-1: 3560 (OH,
broad), 1380 (SO2 ass), 1165 (SO2 sim). 1H NMR (CDCl3),
d: 0.85 (s, 18H, t-Bu), 1.28 (s, 18H, t-Bu), 2.49 (s, 6H,
5c with 4-chlorobenzoyl chloride
To the solution of salt 2 obtained in situ from calix[4]arene
1 (0.483 g, 0.652 mmol) in dry DMF (20 mL) mono-
aroylcalixarene 5c (0.500 g, 0.652 mmol) was added. The
reaction mixture was stirred for 4–5 h at 60–70 ꢁC and
then the solution of 4-chlorobenzoyl chloride (0.170 g,
1.98 mmol) in DMF (5 mL) was added. The reaction
mixture was stirred for 4–5 h at 60–70 ꢁC and cooled. The
precipitate was filtered off, washed with DMF and dried in
the air. Product was separated from tetrahydroxyca-
lix[4]arene 1 by refluxing in 5 mL of chloroform for 1 h.
After cooling for 2–3 h at 5–10 ꢁC, calixarene 1 was
filtered off, washed with small amount of the cooled sol-
vent and dried in the air. Yield of compound 1 was 0.384 g.
Chloroform was evaporated, the crude product (containing
2
Ar–CH3), 3.06 (d, 4H, Ar–CH2eq, JHH = 14.1 Hz), 3.94
(d, 4H, Ar–CH2ax, 2JHH = 14.1 Hz), 4.55 (s, 2H, OH), 6.64
(s, 4H, Ar–H), 7.01 (s, 4H, Ar–H), 7.37 (d, 4H, SO2–O–
3
Ar–H, JHH = 8.2 Hz), 7.83 (d, 4H, SO2–O–Ar–H,
3JHH = 8.2 Hz). 13C NMR (CDCl3), d: 21.89 (SO2PhCH3),
30.91, 31.73 (CCH3), 32.30 (Ar–CH2–Ar), 33.99, 34.06
(Ar–CMe3), 125.22, 125.91 (CAr–H), 127.88 (CPh–Me),
128.38, 129.78 (CPh–H), 133.08, 133.20 (CAr–H), 141.84,
142.30 (CAr–t-Bu), 145.10 (CPh–SO2), 149.10 (CAr–OSO2),
149.78 (CAr–OH). Anal. Found, %: C 72.77; H 7.16;
S 6.70. Calc. for C58H68O8S2, %: C 71.88; H 7.04;
S 6.69.
1
5,11,17,23-Tetra-tert-butyl-25,27-bis(40-chlorophenyl-
carboxy)-26,28-dihydroxycalix[4]arene 4b. White solid.
Yield 0.314 g (25%), Mp [ 340 ꢁC (ethyl acetate). IR
(KBr), m, cm-1: 3565 (OH, monomeric), 1736 (C = O);
IR (CH2Cl2), m, cm-1: 3565 (OH, monomeric), 1735
8–9% of 4c accordingly H NMR spectrum) was crystal-
lized from ethyl acetate. Calix[4]arene 4d was filtered off
and dried. The filtrate (solution in DMF) was poured to 3%
HCl (50 ml). After stirring for 1–2 h, the precipitate was
filtered off, washed with water and dried in the air. The
precipitate was refluxed in chloroform (5 mL) for 1–2 h
and left for 15–20 h at 5–10 ꢁC. The rest of 4-chloroben-
zoic acid was filtered off, the filtrate was evaporated. The
residue was unreacted 5c (0.083 g).
1
(C = O). H NMR (CDCl3), d: 0.99 (s, 18H, t-Bu), 1.18
(s, 18H, t-Bu), 3.49 (d, 4H, Ar–CH2eq, JHH = 14.2 Hz),
2
3.92 (d, 4H, Ar–CH2ax,
2JHH = 14.2 Hz), 5.06 (s, 2H,
OH), 6.90 (s, 4H, Ar–H), 7.01 (s, 4H, Ar–H), 7.47 (d, 4H,
3
5,11,17,23-Tetra-tert-butyl-25-(40-methylphenylcarb-
oxy)-27-(40-chlorophenylcarboxy)-26,28-dihydroxycalix
[4]arene 4d. White solid. Yield 0.325 g (55%),
C(O)–Ar–H, JHH = 8.4 Hz), 8.24 (d, 4H, C(O)–Ar–H,
3JHH = 8.4 Hz). 13C NMR (CDCl3), d: 31.12, 31.59
(CCH3), 33.43 (Ar–CH2–Ar), 33.95, 34.19 (Ar–CMe3),
125.48, 126.04 (CPhH), 127.64, 127.73 (CPh–CH2),
129.26, 131.58 (CAcH), 131.65 (CAc–C(O)O), 140.31
(CAc–Cl), 142.66, 142.89 (CPh–t-Bu), 148.90 (CPh–OC(O)),
150.11 (CPh–OH), 163.84 (C(O)O). Anal. Found, %: C 74.88;
H 6.86; Cl 7.50. Calc. for C58H62Cl2O6, %: C 75.23; H 6.75;
Cl 7.66.
1
Mp [ 350 ꢁC (ethyl acetate). H NMR (CDCl3), d: 0.98
(s, 18H, t-Bu), 1.17 (s, 18H, t-Bu), 2.53 (s, 3H, CH3),
2
3.47 (d, 2H, Ar–CH2eq, JHH = 14.0 Hz), 3.48 (d, 2H,
Ar–CH2eq
2JHH = 14.0 Hz), 3.95 (d, 2H, Ar–CH2ax
14.2 Hz), 5.18 (s, 2H, OH), 6.89 (s, 4H, Ar–H), 7.02 (s,
, ,
2JHH = 14.2 Hz), 3.93 (d, 2H, Ar–CH2ax
,
2JHH
=
3
5,11,17,23-Tetra-tert-butyl-25,27-bis(40-methylphenyl-
carboxy)-26,28-dihydroxycalix[4]arene 4c. White solid.
Yield 0.360 g (30%), Mp [ 340 ꢁC (benzene). IR (KBr), m,
4H, Ar–H), 7.30 (d, 2H, Me–Ar–H, JHH = 8.0 Hz),
3
7.47 (d, 2H, Cl–Ar–H, JHH = 8.6 Hz), 8.19 (d, 2H,
3
Me–Ar–H, JHH = 8.0 Hz), 8.28 (d, 2H, Cl–Ar–H,
3JHH = 8.6 Hz). Anal. Found, %: C 78.19; H 7.56; Cl
3.70. Calc. for C59H65ClO6, %: C 78.25; H 7.23; Cl 3.91.
cm-1: 3560 (OH), 1730 (C = O); IR (CH2Cl2), m, cm-1
:
3560 (OH), 1730 (C = O). 1H NMR (CDCl3), d: 0.98
(s, 18H, t-Bu), 1.18 (s, 18H, t-Bu), 2.50 (s, 6H, Ar–CH3),
3.46 (d, 4H, Ar–CH2eq,
2JHH = 14.3 Hz), 3.97 (d, 4H,
Ar–CH2ax, 2JHH = 14.3 Hz), 5.26 (s, 2H, OH), 6.87 (s, 4H,
Ar–H), 7.21 (s, 4H, Ar–H), 7.31 (d, 4H, C(O)–O–Ar–H,
Reaction of bis(40-methylphenylsulfonyloxy) calix[4]arene
4a with sodium methoxide
3
3JHH = 7.6 Hz), 8.24 (d, 4H, C(O)–O–Ar–H, JHH
=
7.6 Hz). 13C NMR (CDCl3), d: 21.89 (CAcCH3), 31.15,
31.63 (CCH3), 33.29 (Ar–CH2–Ar), 33.95, 34.17
(Ar–CMe3), 125.44, 125.87 (CPhH), 126.74, 127.80
(CPh–CH2), 129.57, 130.42 (CAcH), 131.79 (CAc–C(O)O),
142.44, 143.10 (CPh–t-Bu), 143.99 (CAc–Me), 148.56
(CPh–OC(O)), 150.27 (CPh–OH), 164.77 (C(O)O). Anal.
Found, %: C 79.60; H 8.02. Calc. for C60H68O6, %: C
81.41; H 7.74.
The suspension of 4a (0.10 g, 0.10 mmol) and powdered
MeONa (0.01 g, 0.18 mmol) in 5 mL of DMF was stirred at
30–40 ꢁC to full dissolution of reagents. The reaction
mixture was stirred 30 min and then was poured to 3% HCl
(10 mL). The mixture of compounds 5a and 6 were
extracted by chloroform (3 9 5 mL), the organic layer was
washed with water and dried over Na2SO4. Chloroform was
evaporated, the residue was stirred in boiling methanol
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3
(5 mL), precipitate (calixarene 5a) filtered off, washed with
methanol and dried in the air. The filtrate was concentrated
under reduced pressure to the 1/2 of volume. After 48 h at
-10 ꢁC the precipitate was filtered off. After removal of
methanol from filtrate, calixarene 6 was obtained as color-
less substance.
2JHH = 14.1 Hz), 6.45 (d, 2H, SO2Ar–H, JHH = 8.2 Hz),
6.98 (s, 2H, Ar–H), 7.06 (c, 2H, Ar–H), 7.24 (s, 2H, Ar–H),
7.26 (s, 2H, Ar–H), 7.42 (d, 2H, SO2Ar–H, 3JHH = 8.2 Hz),
3
7.62 (d, 4H, SO2Ar–H, JHH = 8.2 Hz), 8.19 (d, 2H,
3
SO2Ar–H, JHH = 8.2 Hz).
5,11,17,23-Tetra-tert-butyl-25-(40-methylphenylsulfo-
nyloxy)-26,27,28-trihydroxycalix[4]arene 5a. White
solid. Yield 0.026 g (44%), Mp 292–294 ꢁC. IR (KBr), m,
cm-1: 3520 (OH), 3340 and 3282 (OHꢀꢀꢀO, broad), 1365
(SO2 ass), 1165 (SO2 sim); IR (CH2Cl2), m, cm-1: 3500
(OH), 3350 (OHꢀꢀꢀO, broad), 1365 (SO2 ass), 1165 (SO2
Reaction of diacyloxycalic[4]arenes 4b, c with sodium
methoxide
The suspension of 4b, c (0.1 g, 0.10 mmol) and powdered
MeONa (0.01 g, 0.18 mmol) in 5 mL of dry DMF was
stirred at 40–50 ꢁC to full dissolution of reagents
(10–15 min). The reaction mixture was poured to 3% HCl
(10 mL). After stirring for 30 min product was filtered off,
washed with water and dried in the air.
1
sim). H NMR (CDCl3), d: 1.09 (s, 9H, t-Bu), 1.17 (s, 9H,
t-Bu), 1.19 (s, 18H, t-Bu), 2.47 (s, 3H, Ar–CH3), 3.24
(d, 2H, Ar–CH2eq
Ar–CH2eq
2JHH = 13.9 Hz), 4.08 (d, 2H, Ar–CH2ax
2JHH = 13.9 Hz), 4.17 (d, 2H, Ar–CH2ax 2JHH
,
2JHH = 13.9 Hz), 3.42 (d, 2H,
,
,
5,11,17,23-Tetra-tert-butyl-25-(40-chlorophenylcarb-
oxy)-26,27,28-trihydroxycalix[4]arene 5b. White solid.
Yield 0.081 g (95%), Mp 316–317 ꢁC with decomp.
(acetone) ([ 200 ꢁC [10]). IR (KBr), m, cm-1: 3510
(OH), 3365 and 3320 (OHꢀꢀꢀO,broad), 1725 (C = O); IR
(CH2Cl2), m, cm-1: 3490 (OH), 3330 (OHꢀꢀꢀO, broad),
1725 (C = O). 1H NMR (CDCl3, 50 ꢁC), d: 0.74 (s, 18H,
t-Bu), 1.40, 1.41 (s ? s, 9H ? 9H, t-Bu), 3.54 (d, 2H,
,
=
13.9 Hz), 6.99 (s, 8H, Ar–H), 7.39 (d, 2H, SO2–O–Ar–H,
3JHH = 8.2 Hz), 7.73 (s, 2H, OH), 7.95 (d, 2H, SO2–O–
3
Ar–H, JHH = 8.2 Hz), 9.22 (s, 1H, OH). 13C NMR
(CDCl3), d: 21.75 (Ph–CH3), 31.00, 31.40, 31.57 (CCH3),
32.59, 32.63 (Ar–CH2–Ar), 33.97, 34.01, 34.31 (Ar–CMe3),
125.93, 125.98, 126.14, 127.33 (CAr–H), 127.49, 127.96,
128.15, 128.22 (C–CH2), 129.10, 130.38 (CPh–H), 134.57
(CPh–CH3), 141.98, 143.72, 144.41 (CAr–t-Bu), 146.10
(CPh–S), 147.34 (CAr–OS), 149.26, 150.60 (CAr–OH).
Anal. Found, %: C 77.30; H 6.93; S 3.81. Calc. for
C51H62O6S, %: C 76.27; H 7.78; S 3.99.
2
Ar–CH2eq, JHH = 13.8 Hz), 3.86 (d, 2H, Ar–CH2–Ar-
2
anti, JHH = 16.8 Hz), 4.03 (d, 2H, Ar–CH2–Ar-anti,
2JHH = 16.8 Hz), 4.16 (d, 2H, Ar–CH2ax
, =
2JHH
3
13.8 Hz), 6.34 (d, 2H, Cl–Ar–H, JHH = 8.1 Hz), 6.41
3
(d, 2H, Cl–Ar–H, JHH = 8.1 Hz), 6.49 (d, 2H, Ar–H,
5,11,17,23-Tetra-tert-butyl-25,26,27-tri(40-methylphenyl-
sulfonyloxy)-28-hydroxycalix[4]arene 6. White solid. Yield
0.043 g (44%), Mp 133–135 ꢁC. IR (KBr), m, cm-1: 3590
(OH), 1380 (SO2 ass), 1165 (SO2 sim); IR (CH2Cl2), m,
4JHH = 2.2 Hz), 6.70 (s, 2H, OH), 6.84 (d, 2H, Ar–H,
4JHH = 2.2 Hz), 7.21 (s, 2H, Ar–H), 7.37 (s, 2H, Ar–H),
8.63 (s, 1H, OH). 13C NMR (CDCl3), d: 31.23, 31.91,
32.08 (CCH3), 32.32 (Ar–CH2–Ar), 33.74, 34.59, 34.97
(Ar–CMe3), 38.59 (Ar–CH2–Ar, anti), 125.13, 125.35,
125.73 (CPhH), 126.63, 127.48 (CPh–CH2), 127.62
(CPhH), 127.90 (CAcH), 128.63 (CPh–CH2), 130.83
(CAcH), 131.40 (CPhH), 139.03 (CAc–Cl), 143.72, 144.41
(CPh–t-Bu), 146.42 (CAc–C(O)O), 147.56 (CPh–OC(O)),
149.34, 150.19 (CPh–OH), 162.00 (C(O)O). Anal.
1
cm-1: 3590 (OH), 1380 (SO2 ass), 1165 (SO2 sim). H
NMR (CDCl3), d: 0.79 (s, 18H, t-Bu), 1.28, 1.29 (s ? s,
9H ? 9H, t-Bu), 2.44 (s, 6H, Ar–CH3), 2.50 (s, 3H,
Ar–CH3), 2.60 (d, 2H, Ar–CH2eq, 2JHH = 14.1 Hz), 3.05 (d,
2
2H, Ar–CH2eq, JHH = 14.5 Hz), 4.01 (d, 2H, Ar–CH2ax
,
2JHH = 14.5 Hz), 4.02 (s, 1H, OH), 4.18 (d, 2H, Ar–CH2ax
,
Alk-Hal
MeONa, DMF
70 oC
OH
OH
OH
+
OH
OH
OH
OH
OH
OH
OH
O
O
Na
Alk
1
2
3a-d
Alk = CH3(a);
n-C3H7 (b);
n-C8H17 (c);
CH2C(O)OC2H5(d)
Scheme 1 Synthesis of calix[4]arene monosodium salt 2 and monoalkyloxycalix[4]arenes 3a–d
123

J Incl Phenom Macrocycl Chem (2012) 74:265–275
269
Acyl-Hal
+
1/2
1/2
+
OH
OH
OH
OH
O
OH
OH
O
OH
OH
O
OH
Na
Acyl
Acyl
2
4a-c
1
Acyl = SO2C6H4-CH3-4 (a);
C(O)C6H4-Cl-4 (b);
C(O)C6H4-CH3-4 (c)
Scheme 2 Sulfonylation and acylation of monosodium salt 2
MeONa
+
DMF
O
S
OH
OH
O
O
OH
OH
OH
O
O
O
S
OH
O
O
O
O
O
O
S
S
S
S
O
O
O
O
O
O
4a
5a
6
Ar
O
O
MeONa
DMF
OH
OH
OH
OH
O
O
OH
OH
O
OH
OH
O
O
O
Ar
Ar
Ar
8b,c
5b,c
4b,c
Ar = C6H4-Cl-4 (b);
C6H4-CH3-4(c)
Scheme 3 Reaction of calix[4]arenes 4a, b, c with sodium methoxide
3
Found, %: C 77.90; H 7.73; Cl 4.46. M 787.49. Calc. for
C51H59ClO5, %: C 77.79; H 7.55; Cl 4.50. M? 787.3.
5,11,17,23-Tetra-tert-butyl-25-(40-methylphenylcarboxy)-
26,27,28-trihydroxycalix[4]arene 4c. White solid. Yield
0.080 g (92%), Mp 310–311 ꢁC (acetonitrile) ([ 200 ꢁC
[10]). IR (KBr), m, cm-1: 3510 (OH), 3380 (OHꢀꢀꢀO, broad),
1718 (C = O); IR (CH2Cl2), m, cm-1: 3480 (OH), 3325
3JHH = 8.0 Hz), 6.52 (d, 2H, Me–Ar–H, JHH = 8.0 Hz),
6.54 (d, 2H, Ar–H, 4JHH = 2.2 Hz), 6.78 (s, 2H, OH), 6.86
4
(d, 2H, ArH, JHH = 2.2 Hz), 7.17 (s, 2H, Ar–H), 7.34 (s,
2H, Ar–H), 8.63 (s, 1H, OH). 13C NMR (CDCl3), d: 21.50
(Ar–CH3), 31.26, 31.90, 32.09 (CCH3), 32.39 (Ar–CH2–
Ar), 33.79, 34.53, 34.94 (Ar–CMe3), 38.03 (Ar–CH2–Ar,
anti), 125.29, 125.31, 125.70, 127.55 (CPhH), 128.59
(CAcH), 128.62 (CPh–CH2), 129.80 (CAcH), 131.89
(CPh–CH2), 143.06 (CAc–Me), 143.63, 144.17 (CPh–t-Bu),
146.31 (CAc–C(O)O), 147.61 (CPh–OC(O)), 148.40,
149.94 (CPh–OH), 163.34 (C(O)O). Anal. Found,
%: C 80.93; H 8.10. Calc. for C52H62O5, %: C 81.42; H
8.15.
1
(OHꢀꢀꢀO, broad), 1720 (C = O). H NMR (CDCl3, 50 ꢁC),
d: 0.76 (s, 18H, t-Bu), 1.37 and 1.38 (s ? s, 9H ? 9H,
t-Bu), 2.10 (s, 3H, Ar–CH3), 3.51 (d, 2H, Ar–CH2eq, 2JHH
=
2
13.7 Hz), 3.88 (d, 2H, Ar–CH2–Ar-anti, JHH = 16.3 Hz),
3.98 (d, 2H, Ar–CH2–Ar-anti, 2JHH = 16.3 Hz), 4.10 (d, 2H,
Ar–CH2ax
,
2JHH = 13.7 Hz), 6.39 (d, 2H, Me–Ar–H,
123

270
J Incl Phenom Macrocycl Chem (2012) 74:265–275
The X-ray diffraction study
Mr = 844.12, Z = 4, space group P21/n, dcalc = 1.164 g/
cm3, l(MoKa) = 0.116 mm-1, F (000) = 1816. Intensi-
ties of 20071 reflections (8152 independent, Rint = 0.060)
were measured on the ‘‘Xcalibur-3’’ diffractometer
(graphite monochromated MoKa radiation, CCD detector,
x-scanning, 2Hmax = 50ꢁ).
The colorless crystals of 5a C51H62O6S ꢀ C2H3N are
monoclinic. At 100 K a = 12.7285 (5), b = 12.5200 (3),
´
3
˚
˚
c = 30.661 (1) A, b = 99.617 (3)ꢁ, V = 4817.4 (3) A ,
The colorless crystals of 5b C51H59O5Cl ꢀ C3H6O are
Table 1 Absorption bands in IR spectra for OH-groups of
calix[4]arenes 3 and 5 (KBr,m,cm-1
)
monoclinic. At 100 K a = 25.0535 (5), b = 9.8937 (2),
´
3
˚
˚
c = 18.5773 (3) A, b = 93.726 (2)ꢁ, V = 4595.1 (2) A ,
Mr = 845.51, Z = 4, space group P21/c, dcalc = 1.222 g/
cm3, l(MoKa) = 0.134 mm-1, F (000) = 1816. Intensi-
ties of 22931 reflections (8004 independent, Rint = 0.030)
were measured on the ‘‘Xcalibur-3’’ diffractometer
(graphite monochromated MoKa radiation, CCD detector,
x-scanning, 2Hmax = 50ꢁ).
Comp.
R
OH associated OH monomeric
3a
3b
3c
3d
5a
5b
5c
CH3
3175, 3280
–
n-C3H7
3260, 3330
3200, 3365
3220, 3365
–
n-C8H17
–
CH2C(O)OC2H5
–
4-MeC6H4S(O)2 (mono) 3285, 3340
4-ClC6H4C(O) (mono) 3320, 3365
3520
3510
3510
The structures were solved by direct method using
SHELXTL package [26]. Positions of the hydrogen atoms
were located from electron density difference maps and
refined by ‘‘riding’’ model with Uiso = nUeq of the carrier
atom (n = 1.5 for methyl and hydroxyl group and for water
molecule and n = 1.2 for other hydrogen atoms). The
hydrogen atoms of hydroxyl group which take part in the
formation of the hydrogen bonds are refined in isotropic
approximation. The restrains for the bond lengths (Csp3–
4-CH3C6H4C(O) (mono) 3380
.
.
.
.
O
O
.
O
O
.
.
.
.
H
H
H
H
H
H
.
.
.
.
.
.
O
O
O
O
.
O
O
O
O
.
.
.
.
H
.
.
.
.
Acyl
O
Acyl
O
Alk
Acyl
.
.
.
H
H
H
O
O
Csp3 1.54 A) in the disordered fragments were applied
˚
A
B
C
D
during the refinement of the structures. Full-matrix least-
squares refinement of the structures against F2 in
Fig. 1 The hydrogen bonds in monoalkyloxycalix[4]arene (A) and
monoacyloxycalix[4]arenes (B, C, D)
+
+
1
+
OH
OH
OH
OH
OH
O
O
OH
+
OH
O
O
OH
Na
Na
O
O
5c
2
7
O
Cl
Cl
OH
O
O
OH
O
O
Cl
4d
Scheme 4 Synthesis of heteroacylated calix[4]arene 4d
123

J Incl Phenom Macrocycl Chem (2012) 74:265–275
271
anisotropic approximation for non-hydrogen atoms using
8095 (5a), 7980 (5b) reflections was converged to:
wR2 = 0.083 (R1 = 0.046 for 4218 reflections with
F [ 4r (F), S = 0.810) for structure 5a and wR2 = 0.124
(R1 = 0.046 for 5194 reflections with F [ 4r (F),
S = 0.926) for structure 5b. The final atomic coordinates,
and crystallographic data for molecules 5a and 5b have
been deposited to with the Cambridge Crystallographic
Data Centre, 12 Union Road, CB2 1EZ, UK (fax: ?44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk) and are
available on request quoting the deposition numbers CCDC
816614 for 5a and CCDC 816615 for 5b.
The various result of alkylation and acylation of
monosodium salt of p-tert-butylcalix[4]arene 2 can be
explained by different acidity of the hydroxyl groups of
monofunctionalized derivatives, which is caused by the
change of hydrogen bonding system. All the hydrogen
atoms of the hydroxyl groups of compounds 3 take part in
the formation of hydrogen bonds: two OH…OH and one
OH…OAlk. This is confirmed by their IR spectra, which
contain the only broad absorption bands of the associated
hydroxyl groups at 3190–3365 cm-1 (Table 1). Therefore
transformation into anion requires the additional energy for
cleavage of the hydrogen bonds.
In the case of monoacyloxycalixarenes 5 oxygen atoms
bearing electron acceptor carbonyl or sulfonyl groups,
consequently, aren’t hydrogen bonded. As a result, only
two hydrogen atoms form the hydrogen bonds and the third
one remain free and it is observed broad absorption bands
Results and discussion
Calixarene monosodium salt 2 was formed by stirring of
the suspension of calix[4]arene 1 and sodium methoxide
(in an equimolar ratio) in DMF at 60–70 ꢁC (Scheme 1).
Unlike the starting reagents (tetrahydroxycalix[4]arene 1
and sodium methoxide), salt 2 is well soluble in DMF.
After evaporation of solvent the salt was obtained as a
solvate with two molecules of DMF. It should be noted,
that monosodium salt 2 is also well soluble in acetone,
acetonitrile, chloroform and while heating in benzene and
toluene. It isn’t dissolved in diethyl ether and THF. The
solution of calix[4]arene monosodium salt 2 was used for
chemical transformations in situ. Due to the good solubility
of salt 2 and alkylating or acylating reagents in DMF the
processes were carried out in the homogeneous environ-
ment, which raised the selectivity of the reactions.
a
For alkylation of calix[4]arene monosodium salt 2 the
5–6-fold excesses of the corresponding alkylating reagents
were used. In the case of less reactive alkyl bromides the
catalytic quantity of dry KI was added for their conversion
to more active alkyl iodides. The reaction was performed at
C35
C36
C34
C9
C33
ꢁ
60–70 C for 15–20 h to give the cone-shaped mono-
C10
alkyloxycalix[4]arenes 3a–d in 65–77% yields (Scheme 1).
The sulfonylation and acylation of monosodium salt 2
by the equimolar quantity of sulfonyl or benzoyl chloride
led to the formation of trace amounts of monoacylated
calixarenes while the basic products of the reaction were
distal diacylated calix[4]arenes 4a–c and tetrahydroxyca-
lix[4]arene 1 (Scheme 2).
C11
C12
C14
C7
C8
C13
C16
C4
C5
C15
C38
C32
C31
2
OH
1
C29
C17
C37
3OH
OH
C39
C3
C6
C1
C20
C19
4O
C18
C40
C30
C2
C27
Calixarenes 4a–c reacts with sodium methoxide, but the
ways of its transformations are different. In the solution of
DMF there is a disproportionating of disulfonyloxycalixa-
rene 4a with the formation of mono- 5a and trisulfonylated
calixarenes 6. The same disproportionation of 1,3-bistriflate
calyx[4]arene under the influence of palladium catalysts was
previously observed, but the product yield was significantly
lower [19]. In the case of diacyloxycalixarenes 4b, c occurs
elimination of one of the acyl group (Scheme 3).
C28
C26
C21
C22
C23
C46
C47
C48
C25
C24
1
S
MeC51
b
C45
O
5
C41
O
C49
6
C50
C44
C42
C43
Fig. 2 The molecular structure of 5a (a) and numbering scheme of
atoms (b) according to X-ray diffraction data
123

272
J Incl Phenom Macrocycl Chem (2012) 74:265–275
of the associated hydroxyl groups at 3285–3380 cm-1 and
narrow band of the monomeric OH group at 3510 cm-1 in
the IR spectra. The lower energy is required for the remove
of proton, which isn’t hydrogen bonded, therefore these
compounds easily form anion C even by the interaction
with such a weak base as salt 2 (Fig. 1). Anion C formed in
this case can be stabilized by the hydrogen bonding with
the only one neighboring hydroxyl group. Therefore C
undergoes the fast transformation into anion D, which is
more favorable because it can be stabilized by two
hydrogen bonds.
Compound 4d is a major product of the reaction and can
be formed only from p-Cl-benzoyl chloride and anion 7.
According to the 1H NMR spectrum the mixture of
products contains 37% of 4d (64% based on conversion of
monoacylated calixarene 5c). When 5c was replaced by
monoalkylated calixarene 3b the mixture with the major
unreacted monopropyloxycalixarene 3b was obtained.
According to the 1H NMR spectrum at the room temper-
ature in CDCl3 solution diacyloxycalixarenes 4b, c are
present in the flattened cone conformations as proved by the
small distances betweentheresonance signals of theaxial and
equatorial protons of methylene bridges (Dd * 0.5 ppm).
This value is nearly 1 ppm for sulfonyloxycalixarenes 4a, 5a,
and 6 that conforms to a regular cone conformation.
The following reaction of the salt D with acyl chloride
gives 1,3-disubstituted products 4. The reaction of 5c with
p-Cl-benzoyl chloride in the presence of calixarene sodium
salt confirms the stronger acidity of monoacylated deriva-
tive in comparison to monoalkylated one. After stirring of
the equimolar quantities of monoacylated derivative 5c and
sodium salt 2 in DMF within 9 h acyl chloride was added
(Scheme 4).
The X-ray diffraction study of the compound 5a
demonstrates that these molecules in the crystalline phase
have a cone conformation of macrocycle (Fig. 2).
Moreover, the molecule 5a and solvent acetonitrile
molecule form the ‘‘host–guest’’ complex (Fig. 2a). It is
1
Fig. 3 The H NMR spectrum
of 5c–8c (300 MHz, CDCl3) at
-60 ꢁC (a), 25 ꢁC (b) and
50 ꢁC (c)
123

J Incl Phenom Macrocycl Chem (2012) 74:265–275
273
possible to assume that the formation of this complex
provides additional promotion of the cone conformation of
macrocycle which is stabilized by relatively strong intra-
molecular hydrogen bond at lower rim. The p-toluenesul-
fonyl substituent has exo-orientation relatively the
macrocycle cavity and it is orthogonal with respect to the
C22…C27 aromatic ring (the C26–C27–O4–S1 torsion
angle is -88.1 (2)ꢁ). The tolyl group is located in –sc-
conformation relatively the C27–O4 bond and is turned in
such way that the plane of the C45…C50 aromatic ring is
orthogonal to the O4–S1 bond (the C45–S1–O4–C27, and
the O4–S1–C45–C46 torsion angles are -70.8 (2)ꢁ, and
87.2 (2)ꢁ, respectively).
For further studies of the spatial structure of the acylated
calixarene we performed X-ray diffraction study. In the
crystalline phase the molecule 5b is observed as mono-
solvate with acetone where the macrocycle has a partial
cone conformation (Fig. 4a). The chlorophenylcarboxylic
substituent at the inverted aromatic ring is turned in such
way that the chlorophenyl fragment is located inside the
cavity of the macrocycle and it has almost orthogonal
orientation with respect to the opposite aromatic ring.
However, conjugation between chlorophenyl ring and
carbonyl group is not disturbed (the O4–C45–C46–C47
torsion angle is 4.8 (3)ꢁ).
Completely different situation is observed for mono-
1
acyloxycalixarenes 5b, c. The H NMR spectrum at room
temperature in the CDCl3 solution are typical for partial
cone conformation 8b, c (Fig. 3b), although previously a
cone conformation was given for this type of compounds
[18]. They have the pair of doublets from the equatorial and
axial protons of methylene groups between syn-oriented
phenyl rings (AX-spin system, d 3.53 ppm and 4.12 ppm,
2JHH = 13.7 Hz) and pair of doublets from the protons of
methylene groups between anty-oriented phenyl rings (AB-
2
spin system, d 3.90 ppm and 4.00 ppm, JHH = 16.2 Hz).
In the 13C NMR spectrum the signals of carbonic atoms of
methylene bridges are at 38.03 ppm (between anty-oriented
phenyl rings) and 32.39 ppm (between syn-oriented phenyl
rings) that confirmed the partial cone conformation [27]. At
the same time the broadened signals in this spectrum indi-
cate the occurrence of some dynamic processes in solution
of monoacyloxycalixarenes which are probably associated
with conformation conversions of macrocycle. For a more
detailed study of these processes we carried out investiga-
tion of compounds 5b, c using dynamic NMR methods. We
found that at -60 ꢁC monoacyloxycalixarenes exists in
solution as mixture of two interconvertible conformers:
cone (red line) 5b, c and partial cone (black line) 8b, c in
the ratio 1: 4 for 5c–8c (Fig. 3a) and 1: 10 for 5b–8b. In
consideration of large volume of acyl substitute such con-
version is only possible sequential inversion of unsubsti-
tuted phenolic rings.
a
C35
C36
C34
C9
C33
C10
C11
C12
C14
C7
C8
C13
C16
C38
C40
C32
C4
C15
C5
C1
2
OH
1OH
C29
C17
3OH
C31
C39
C3
C6
C20
C19
C37
4O
It should be noted that in the low temperature we
observe one more dynamic process for partial cone con-
former. It is shown by change in the form of signals for
aromatic protons of acyl substituent. With decreasing
temperature these signals first broadened and then divided
into four doublets with nearly equal intensity
(3JHH = 7.7 Hz) in the range of 7.5, 6.9, 5.4, and 4.7 ppm
(Fig. 3a). The location of aromatic protons in the range of
4.5–5.5 ppm is unusual and indicates their effective mag-
netic shielding of other benzene rings of macromolecule.
This is only possible if the acyl fragment is located inside
the cavity of the macrocycle.
C18
C30
C2
C27
C22
O5
C28
C26
C21
C45
C23
C46
C25
C24
C47
C51
C41
C50
C42
C48
C44
b
C49
Cl 1
C43
Fig. 4 The molecular structure of 5b (a) and numeration of atoms
(b) according to X-ray diffraction data
123

274
J Incl Phenom Macrocycl Chem (2012) 74:265–275
5. Nam, K.C., Kim, J.M., Park, Y.J.: Synthesis and structure iden-
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Enhanced alkaline hydrolysis of monoesterified 4-tert-butylca-
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(1994)
Fig. 5 The packing of 5b molecules in the crystal phase
11. Shu, C.-M., Chung, W.-S., Wu, S.-H., Ho, Z.-S., Lin, L.-G.:
Synthesis of calix[4]arenes with four different ‘‘lower rim’’
substituents. J. Org. Chem. 64, 2673–2679 (1999)
The solvent acetone molecules are situated between
chains formed by molecules 5b along the [001] crystallo-
graphic direction (Fig. 5). It can be assumed that they do
not influence molecular structure of 5b.
¨
12. Groenen, L.C., Ruel, B.H.M., Casnati, A., Verboom, W., Pochini,
A., Ungaro, R., Reinhoudt, D.N.: Synthesis of monoalkylated
calix[4]arenes via direct alkylation. Tetrahedron 47, 8379–8384
(1991)
So mono functionalized trihydroxycalix[4]arenes may
exist in cone conformation as well as partial cone con-
formation. Their ratio is determined of substitute and kind
of solvents. Now we investigate the influence of these
factors on the equilibrium in this process.
´
´
13. Santoyo-Gonzalez, F., Torres-Pinedo, A., Sanchez-Ortega, A.:
Regioselective monoalkylation of calixarenes. Synthesis of
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Small, A.C., Lattman, M.: From a novel silyl p-tert-butylca-
lix[4]arene triether to mono-0-alkyl substitution: a unique, effi-
cient, and selective route to mono-0-substituted calix[4]arenes.
Organometallics 13, 5157–5159 (1994)
Conclusion
15. Gutsche, C.D., Lin, L.-G.: Calixarenes 12. The synthesis of
functionalized calixarenes. Tetrahedron 42, 1633–1640 (1986)
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In this work it is shown that alkylation of monosodium salt
of p-tert-butylcalix[4]arene in DMF goes selectively, leads
to the monoalkyloxycalix[4]arenes in good yields and may
be used as preparative method of monoalkylation. Reaction
of monosodium salt with benzoyl chloride derivatives in
these conditions leads to the 1,3-diacylated products, which
transform into monoacyloxycalix[4]arenes by the treatment
with sodium methoxide. It is established, that monoacy-
lated calix[4]arenes in chloroform solution and in crystal
phase adopts a partial cone conformation in which phe-
nylacylic group is located inside of the macrocycle cavity.
20. Chowdhury, S., Bridson, J.N., Georghiou, P.E.: Synthesis of
calix[4]arene triflates and their unusual chemical reactivity in
palladium-catalyzed reactions. J. Org. Chem. 65, 3202–3299
(2000)
21. Casnati, A.: Calixarenes: from chemical curiosity to a rich source
for molecular receptors. Gazz. Chim. Ital. 127, 637–649 (1997)
22. Hanna, T.A., Liu, L., Angeles-Boza, A.M., Kou, X., Gutsche,
C.D., Ejsmont, K., Watson, W.H., Zakharov, L.N., Incarvito,
Ch.D., Rheingold, A.L.: Synthesis, structures, and conformational
characteristics of calixarene monoanions and dianions. J. Am.
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