Mendeleev Commun., 2006, 16(6), 297–299
(15N) spectra. According to published data,12 the nitrogen and
But
But
But
But
carbon chemical shifts are typical of the N,N'-diacetylhydrazine
fragment. The intensity of proton signals of the N,N'-diacetyl-
hydrazine fragment is the same in the solutions with different
polarity (CDCl3, DMSO) and in the wide concentration range.
This indicates that one of the amide fragments in the N,N'-di-
acetylhydrazine bridge has a trans conformation, but another
one shows a cis conformation.13 No considerable changes in the
νC=O (~1705 cm–1) absorption band frequencies were observed
in IR spectra in CHCl3 solutions under dilution. This is typical
of N,N'-diacetylhydrazine bridge containing compounds.14 The
presence of conformers about C(O)–N bond in N,N'-diacetyl-
hydrazine bridge, binding one pair of aromatic rings, as well as
in acetylhydrazone fragments, attached to another two aromatic
rings, leads to the appearance of four signals for tert-butyl
group protons and a number of signals for protons of aromatic
and amide fragments in NMR spectra.
NaOH, THF–H2O
But
But
S
S
But
But
S
S
O
O
O
O
O
O
O
O
S
S
S
O
O
O
O
S
O
O
O
O
1
O
O
HO
OH
O
O
OH
OH
NH2NH2, H2O,
EtOH, reflux
5
SOCl2, reflux
Calix[4]arene 4 can form as a result of an intramolecular
reaction.‡ Probably, the bonding of an aldehyde molecule
(method A) is accompanied by a nucleophilic attack of the
hydrazide group terminal nitrogen atom in calix[4]arene toward
the carbonyl group of neighbouring oppositely disposed hydrazide
or acetylhydrazone fragments, which leads to the formation of
intramolecular cross-links. The following reaction of hydrazine
or 4-nitrobenzaldehyde hydrazone with an excess of aldehyde
results in azine 3 formation, which precipitates during the process.
It is known that hydrazones are highly reactive compounds,
and under heating, moisture or catalyst effect they are capable
to change into azines with the liberation of hydrazine or into the
products of resinification.15,16 Indeed, the reaction of 4-nitro-
benzaldehyde hydrazone with calix[4]arene 6 (method B) is
accompanied by azine 3 formation. The interaction of hydrazine,
But
But
But
But
But
But
But
But
S
S
S
S
S
S
S
S
O
O
O
O
O
O
O
O
O
O
O
O
O
Cl
Cl
O
O
HN
O
NH
HN
NH2
Cl
NH
Cl
H2N
NH2
NH2
6
2
But
But
But
But
method A
O
method B
NH2
‡
Synthesis of 5,11,17,23-tetra-tert-butyl-25,27-bis[(4-nitrobenzylidene)-
N
hydrazinocarbonylmethyloxy]-26,28-[N,N'-hydrazinylene-bis(carbonyl-
methyleneoxy)]-2,8,14,20-tetrathiacalix[4]arene 4.
S
S
S
S
O
Method A. A solution of 4-nitrobenzaldehyde (1.64 mmol) in CHCl3
(10 ml) was added dropwise to a solution of tetrahydrazide 2 (0.4 mmol)
in CHCl3 (50 ml). The reaction mixture was stirred at room temperature
for 20 h. (Similar procedure was carried out in EtOH at the reflux for
5 h). The precipitate of 3 (mp 310 °C) was filtered off. After removing
the solvent from the filtrate under a reduced pressure, ethyl acetate (20 ml)
was added to the residue, and the mixture was heated. After cooling, the
precipitate was filtered off, washed several times with ethyl acetate and
O
O
O
NO2
O
O
O
HO
CHCl3, room
temperature
or
O
OH
NO2
HN
NH
7
N
pyridine,
THF, room
temperature
N
EtOH, reflux
1
recrystallised from EtOH–DMF. Yield 26%, mp 242–246 °C. H NMR
(600 MHz, [2H6]DMSO, 30 °C) d: 0.75 and 0.85 (s, 18H, But), 1.31 and
1.32 (s, 18H, But), 4.7–5.3 (m, 8H, OCH2), 6.8–7.0 (m, 4H, ArH),
7.8–8.4 (m, 12H, ArH), 9.3–9.9 (m, 2H, NHNH), 11.68 and 11.78 [2s,
2H, NHC(O)]. 13C NMR (150.9 MHz, [2H6]DMSO, 30 °C) d: 30.81,
30.85, 31.45 and 31.48 (Me), 34.09, 34.19, 34.61 and 34.77 (CMe3),
71.68, 73.13, 74.56 and 77.20 (OCH2), 128.39, 128.59, 157.86 and
157.95 [C(2) in 4-But-Ar], 132.29, 132.48, 132.95, 136.76, 136.96
and 137.23 [C(3) in 4-But-Ar], 146.89, 147.27, 147.48 and 148.26 [C(4)
in 4-But-Ar], 156.62, 156.27, 161.62 and 161.50 [C(1) in 4-But-Ar],
164.77, 166.25, 166.42, 169.66 and 171.55 (C=O). 15N NMR (60.81 MHz,
[2H6]DMSO, 30 °C) d: 121 and 122 (NHNH), 169 and 175 [NHC(O)],
321 and 322 (N=C), 366 (NO2). IR (n/cm–1): 3326, 3271, 3200 (νNH),
1707, 1680 (νC=O), ~1650 (sh, νC=N), ~1550 (sh, dNH (trans)), 1520
(νas NO ), 1342 (νs NO ), 1273, 1250 (nas COC), 1094 (ns COC), 835 (γ=CH).
NO2
O2N
8
But
But
But
But
NO2
S
S
S
S
O
O
O
O
N
O
O
O
+
O
N
HN
HN
NH
NH
2
N
2
MS (MALDI-TOF), m/z: 1245 [M + H]+, 1269 [M + Na]+, 1284 [M + K]+.
Found (%): C, 59.53; H, 5.72; N, 9.03; S, 10.02. Calc. for C62H66N8O12S4
(%): C, 59.88; H, 5.35; N, 9.01; S, 10.31.
N
Method B. A solution of 4-nitrobenzaldehyde hydrazone 7 (5 mmol)
in THF (25 ml) was added dropwise to a solution of calix[4]arene 6
(1.2 mmol) and pyridine (6 mmol) in THF (40 ml). The reaction mixture
was stirred at room temperature for 2 h. The precipitate of 3 was filtered
off. After removing the solvent from the filtrate under a reduced pressure,
CHCl3 was added to the residue, and the mixture was washed several
times with water. The organic layer was dried with MgSO4. After
removing the solvent from the filtrate under a reduced pressure, 30 ml of
ethyl acetate was added to the residue, and the mixture was heated. After
cooling, the precipitate was filtered off, washed several times with ethyl
acetate and recrystallised from EtOH–DMF. Yield 32%, mp 242–245 °C.
Found (%): C, 60.64; H, 5.54; N, 9.15, S, 10.10. Calc. for C62H66N8O12S4
(%): C, 59.88; H, 5.35; N, 9.01; S, 10.31. The IR and NMR spectra of
compound 4 obtained by methods A and B are identical.
NO2
NO2
O2N
3
4
Scheme 1
magnetic non-equivalence and as a result to the splitting of
1
aromatic proton signals in H NMR spectra with the coupling
constants 4J ~ 1–3 Hz.11 Such a phenomenon has not been
observed. The N,N'-diacetylhydrazine bridge formation has
been proved by the presence of cross peaks between nitrogen
(122 ppm) and NH group protons (~9.5 ppm) in HSQC (15N)
spectra and with oxymethyl protons (4.86 and 5.0 ppm) in HMBC
298 Mendeleev Commun. 2006