OXIDATION WITH POTASSIUM PERMANGANATE
947
derivatives of p-tert-butylcalix[4]arene in yields exceed-
ing 90%/. Oxidation of calixarenes IV and V gives bis
(methylcarbonylmethoxy) (IX) and tetrakis(methylcar-
bonylmethoxy) (X) derivatives of p-tert-butylcalix[4]
arene in 85–90% yields.
degree of substitution of the starting calixarene and
conformation of the alkylation products, and the yields
of the carboxymethoxy derivatives prepared by
hydrolysis are lower than in the reactions considered
above.
The IR spectra of VI–VIII contain absorption
bands of the carbonyl group at 1730–1750 cm–1 and
the νO–H bands at 3250 and 3600 cm–1. The IR spectra
of calixarenes IX and X contain absorption bands of
the carbonyl group at 1710–1715 cm–1. In the 1H NMR
spectra of tetrasubstituted derivatives I, V, VI, and X,
there are a singlet from tert-butyl protons (36H), a pair
of doublets from protons of the methylene bridges, and
a singlet from aromatic protons of the macroring (8H);
this spectral pattern of tetrasubstituted calixarenes is
typical of compounds whose molecules occur in the
cone conformation. The 1Н NMR spectra of
disubstituted calixarenes IV and IX (two signals from
tert-butyl protons with 1 : 1 ratio of integral intensities,
two singlets from aromatic protons with the same
intensity ratio, and a pair of doublets from methylene
protons of the macroring) suggest that the molecules of
these compounds also occur in the cone conformation.
The spectra of calixarenes II and VII contain three
singlets from tert-butyl protons (2 : 1 : 1), three singlets
from protons of the aromatic rings (2 : 1 : 1), and two
pairs of doublets with a relatively small difference in
the chemical shifts (Δδ < 0.5 ppm) from methylene
protons. In the spectra of III and VIII, tert-butyl
protons give four singlets, and aromatic protons give
EXPERIMENTAL
1
The Н NMR spectra were recorded on a Varian
VXR-300 device (300 MHz) from ~10% solutions in
CDCl3, internal reference TMS. The FAB mass spectra
were taken on a VG 70-70EQ mass spectrometer using
a beam of Xe atoms with an energy of 8 keV. The IR
spectra were measured on
a
Specord IR-75
spectrophotometer in СHCl3 solutions.
Oxidation of calix[4]arenes containing olefinic
fragments. A suspension of 0.2 mol of appropriate
calixarene and 1.6 mmol (for I and V) or 0.8 mmol
(for II–IV) of KMnO4 in СН2Сl2–Н2О (15–1.5 ml)
was stirred for 3–3.5 h at 15°С (or for 1.5 h at 40°С).
Excess KMnO4 was removed by adding a solution of
NaHSO3 (1 g in 20 ml of water). The resulting mixture
was washed with 5–10 ml of dilute HCl and a NaHSO3
solution. The organic phase was separated, the aqueous
phase was extracted with CH2Cl2 (3 × 10 ml), and the
combined organic extracts were washed with a sodium
carbonate solution and dried over anhydrous MgSO4.
The solvent was removed under reduced pressure, and
the crude product was recrystallized from aqueous
alcohol.
1
two singlets and a pair of doublets. The Н NMR
5,11,17,23-Tetra-tert-butyl-25,27-bis(p-methyl-
benzyloxy)-26,28-bis(carboxymethoxy)calix[4]arene
VII. Yield 92%, mp 105–107°C. IR spectrum, ν, cm–1:
spectrum of III contains a pair of doublets and two
multiplets with small Δδ from methylene protons of
the macrocyclic moiety; in the spectrum of calixarene
VIII, each proton of the methylene bridges gives a
separate signal, with Δδ < 0.3 ppm. Increased number
of nonequivalent protons of the methylene components
of the calixarene ring and decreased Δδ for the signals
of these protons, as follows from [5–7], suggests
certain flattening of the cone conformation in III or its
distortion in II, VII, and VIII.
1
3250, 3600 (OH), 1730 (C=O). Н NMR spectrum, δ,
ppm: 0.99 s [18H, (СН3)3С], 1.18 s [9H, (СН3)3С],
1.23 s [9H, (СН3)3С], 2.25 s (3H, CH3), 2.31 s (3H,
CH3), 2.96 d (2H, ArCH2Ar, J 13.8 Hz), 3.34 d (2H,
ArCH2Ar, J 13.8 Hz), 4.35 d (2H, ArCH2Ar, J 13.8 Hz),
4.56 d (2H, ArCH2Ar, J 13.0 Hz), 5.14 s (4H, CH2O),
6.38 s (2H, CH2O), 6.44 s (2H, CH2O), 7.07 s (4H,
ArH), 7.09 s (2H, ArH), 7.12 s (2H, ArH), 7.2–7.44 m
(8H, Bzl), 9.5 s (2H, OH). FAB-MS: m/z 973 (М + 1)+.
Such modification of p-tert-butylcalix[4]arene
derivatives allows their solubility to be considerably
increased. For example, the carbonyl derivatives pre-
pared are fairly well soluble in alcohols. Compounds
containing a keto group can also be prepared by direct
alkylation of p-tert-butylcalixarene, and calixarenes
containing acid fragments can be prepared by
hydrolysis of the corresponding esters, but these
methods are insufficiently selective with respect to the
5,11,17,23-Tetra-tert-butyl-25,27-bis(m-methyl-
benzyloxy)-26,28-bis(carboxymethoxy)calix[4]arene
VIII. Yield 95%, mp 92–93°C. IR spectrum, ν, cm–1:
1
3200, 3600 (OH), 1730 (C=O). Н NMR spectrum, δ,
ppm: 0.83 s [9H, (СН3)3С], 0.85 s [9H, (СН3)3С], 1.27 s
[9H, (СН3)3С], 1.31 s [9H, (СН3)3С], 2.31 s (3H, CH3),
2.33 s (3H, CH3), 3.06 d (1H, ArCH2Ar, J 13.8 Hz),
3.15 d (1H, ArCH2Ar), 4.34 d (1H, ArCH2Ar), 4.4 d
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 5 2008
Alekseeva
