Synthesis of functionalized macrocyclic derivatives of trioxabicyclo[3.3.0] nonadiene

Article abstract of DOI:10.3762/bjoc.8.83

C72-Macrocyclic systems functionalized with nitroaryl and arylamino groups were synthesized from the bisdioxine diacid dichloride 1,3,5,7-tetra-tert-butyl- 2,6,9-trioxabicyclo[3.3.1]nona-3,7-diene-4,8-dicarbonyl dichloride (3).

Full text of DOI:10.3762/bjoc.8.83

Synthesis of functionalized macrocyclic derivatives
of trioxabicyclo[3.3.0]nonadiene
Sabine Leber1,2, Gert Kollenz*1 and Curt Wentrup*2
Full Research Paper
Open Access
Address:
Beilstein J. Org. Chem. 2012, 8, 738–743.
1Institute of Chemistry, Karl-Franzens University of Graz,
Heinrichstrasse 28, A-8010 Graz, Austria and 2School of Chemistry
and Molecular Biosciences, The University of Queensland, Brisbane,
QLD 4072, Australia
doi:10.3762/bjoc.8.83
Received: 28 March 2012
Accepted: 30 April 2012
Published: 15 May 2012
Email:
Gert Kollenz* - gert.kollenz@uni-graz.at;
Curt Wentrup* - wentrup@uq.edu.au
Associate Editor: S. C. Zimmerman
© 2012 Leber et al; licensee Beilstein-Institut.
License and terms: see end of document.
* Corresponding author
Keywords:
bisdioxine; macrocyclic amines; macrocyclic nitro compounds;
tetraoxaadamantane
Abstract
C72-Macrocyclic systems functionalized with nitroaryl and arylamino groups were synthesized from the bisdioxine diacid
dichloride 1,3,5,7-tetra-tert-butyl-2,6,9-trioxabicyclo[3.3.1]nona-3,7-diene-4,8-dicarbonyl dichloride (3).
Introduction
The concave, axially chiral [1], bridged bisdioxine diacid It may also be possible to stabilize reactive intermediates
dichloride 3 is obtained by acid hydrolysis and subsequent chlo- and unusual functional groups in the concave interiors
rination of the surprisingly stable α-oxoketene 2, itself obtained of the bisdioxine-derived macrocycles. Okazaki and
by dimerization of dipivaloylketene (1) (Scheme 1) [2,3]. The co-workers designed bowl-shaped [8] and lantern-shaped
concave structure of 3 and its derivatives together with the steri- [9] molecules containing a functionalized aryl group,
cally hindering tert-butyl groups make it an interesting spacer which allowed the preparation of, among other things, stable
group, and it thus has been applied successfully in syntheses of simple enols [8] and a variety of unusual sulfur [9], selenium
several macrocyclic polyether and polymethyleneoxy rings [10,11] and germanium [12] species. Clearly, the bisdioxine
containing one, two or three bisdioxine units, e.g., 4 and 5 macrocycles such as 4 and 5 will not be nearly as rigid, but
(Scheme 1) [4,5]. Capping of a calix[6]arene with the they may nevertheless exert some steric protection. Herein
bisdioxine unit has also been achieved recently [6]. Some of we report the realisation of the first step toward this end,
these materials exhibit pronounced complexation of metal ions, the preparation of functionalized macrocyclic bisdioxine
such as Cs+, Hg2+, Cu2+, Ag+, and Au3+ [5-7].
derivatives.
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Scheme 1: Synthesis of macrocyclic bisdioxine derivatives (R,S-form of 4 and S-form of 5 shown; see Supporting Information File 1 for details).
Results and Discussion
Functional group manipulation on aromatic rings often starts
with the nitro group. Therefore, a synthesis of suitable nitro-
aromatic diols for combination with the diacid dichloride 3 was
required. The desired 2-nitro-1,4-phenylene derivative 7 was
prepared by treatment of hydroquinone with 3-bromopropanol
followed by nitration of the resulting diol 6 (Scheme 2). The
isomeric 1,2,3-trisubstituted aromatic 10 was obtained by ether-
ification of nitroresorcinol (Scheme 3).
Scheme 3: Synthesis of the 1,2,3-trisubstituted aryl derivatives.
analysis and their 1H- and 13C NMR spectra. All proton and
carbon resonances could be assigned by comparison with data
for other, related, macrocycles [1-7] (see Supporting Informa-
tion File 2 for spectral details). Since 3 is chiral (existing in
enantiomeric R and S forms) [1,4], the nitro compounds 8 and
Scheme 2: Synthesis of the 1,2,4-trisubstituted aryl derivatives.
11 must also be chiral, i.e., they must exist as mixtures of
diastereoisomeric forms (see the Supporting Information File 1
for drawings of the principal structures). This will also be the
case for the derivatives described below. The splitting of several
signals in the NMR spectra may be ascribed to the presence of
mixtures of diastereoisomers and conformers.
The two diols 7 and 10 reacted readily with the diacid dichlo-
ride 3 in boiling toluene in the presence of triethylamine to
afford the 2:2 adducts 8 and 11, respectively (Scheme 2 and
Scheme 3). These compounds were characterized by elemental
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Beilstein J. Org. Chem. 2012, 8, 738–743.
Reduction
large enough to permit the formation of one tetraoxaadaman-
Several methods were attempted for the reduction of the nitro tane unit, but this will reduce the available space, with the
groups in 8 and 11. Reductions with NaBH4 and sulfur [13] or consequence that the attack by a water molecule on the second
with ammonium formate and Pd/C under microwave irradiation bisdioxine unit from the concave inside of the macrocycle does
[14] were unsuccessful. However, compound 8 was completely not take place. Moreover, no tetraoxaadamantane derivative of
reduced to the diamine 9 by using the classical reduction with nitro compound 11 was obtainable. Here, the cavity is too small
Sn and HCl (Scheme 2). The reaction was complete in 1 h. for the formation of a tetraoxaadamantane. Further investi-
Under the same conditions it took 3 h for the 2,6-disubstituted gations of reactivity and functional group manipulation in the
nitro compound 11 to be completely consumed. Compound 11 macrocycles described herein are foreseen.
is more compact than 8 (see below), and the reduction of 11
was evidently more difficult. Although the product was largely Experimental
the desired diamine 13, mass spectrometry indicated the pres- General. All solvents were dried to achieve the minimum
ence of the singly reduced nitro derivative 12 as an impurity degree of water content. Melting points are uncorrected. Dry-
(Scheme 3).
column flash chromatography (DCFC) was performed
according to a literature method [17] by using silicagel 6H from
A remarkable reaction is the ready conversion of macrocyclic as Merck, Darmstadt and eluting with CH2Cl2/MeOH 100:5,
well as open-chain bisdioxine derivatives to 2,4,6,8-tetraoxa- unless indicated otherwise. Thin-layer chromatography (TLC)
adamantanes on acid hydrolysis [4,7,15]. This transformation was performed on silica gel. LC–MS was performed by using a
was also achieved with the dinitro compound 8, which yielded mixture of 77% CH3CN, 18% H2O, and 5% MeOH as mobile
the mono-tetraoxaadamantane derivative 14 (Scheme 4), but all phase, unless otherwise indicated, and an atmospheric-pressure
attempts to convert the second bisdioxine unit were fruitless, chemical ionization source. All NMR spectra were recorded for
presumably due to steric hindrance. Force-field calculations CDCl3 solutions. Assignments of NMR signals for bisdioxine
[16] indicate that the internal cavity is much smaller in 11 than and tetraoxaadamantane units were made in agreement with
in 8, and in fact it was not possible to prepare a tetraoxa- previously reported data [1-7,15].
adamantane derivative of nitro compound 11. There is a signifi-
cant cavity in 8, obviously large enough to form one tetraoxa- 1,3,5,7-Tetra-tert-butyl-2,6,9-trioxabicyclo[3.3.1]nona-3,7-
adamantane derivative, but this reduces the available space, diene-4,8-dicarbonyl dichloride (3): Flash vacuum thermo-
with the consequence that the attack by a water molecule on the lysis of 5-tert-butyl-4-pivaloylfuran-2,3-dione generates dipi-
second bisdioxine unit from the concave inside of the macro- valoylketene (1), which slowly dimerizes to the dimeric
cycle does not take place.
oxoketene 2 at room temperature [2,3]. Hydrolysis and subse-
quent chlorination with thionyl chloride afforded the bisdioxine
diacid dichloride 3 [3].
4,4’-(2-Nitro-1,4-phenylene)bis(4-oxabutanol) (7): Diol 6 was
prepared according to the literature [18]. To a solution of 6
(750 mg, 3.32 mmol) in 65 mL of glacial acetic acid was added
22 mL of 37% HNO3 under stirring. The solution turned
intensely yellow immediately. After being stirred for 30 min the
mixture was diluted with 100 mL of water, neutralized with aq
KOH, and extracted several times with CH2Cl2. The combined
organic layers were dried over Na2SO4, filtered, and concen-
trated in vacuo. The resulting oily product (1.44 g) was purified
by DCFC to yield 350 mg (39%) of intensely yellow crystals,
mp 48–49 °C; 1H NMR δ 2.05–2.11 (m, 4H, CH2), 2.66 (s, br,
2H, OH), 3.86–3.93 (m, 4H, CH2OH), 4.12–4.15 (m, 2H,
OCH2), 4.23–4.26 (m, 2H, OCH2), 7.05–7.15 (m, 2H, arom.
Scheme 4: Synthesis of the tetraoxaadamantane derivative 14.
Conclusion
The difficulty of reduction of the nitro compounds, in particu- H5, H6), 7.46–7.47 (m, 1H, arom. H3); 13C NMR δ 31.7 (CH2),
lar the 1,2,3-trisubstituted compound 11, as well as the conver- 31.9 (CH2), 59.9 (CH2OH), 60.4 (CH2OH), 66.4 (OCH2), 68.4
sion of only one of the bisdioxine units in 8 to a tetraoxa- (OCH2), 110.9 (arom. C3), 116.0 (arom. C6), 121.7 (arom. C5),
adamantane suggests that these macrocycles provide steric 139.4 (arom. C2), 146.8 (arom. C1), 152.3 (arom. C4); the
protection of the functional groups. The cavity in 8 is obviously NMR spectra were assigned on the basis of comparison with
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Beilstein J. Org. Chem. 2012, 8, 738–743.
standard data compilations; LC–MS (CH2Cl2) m/z: 271; Anal. 28.7 (CH3(t-Bu)), 37.3 (C(t-Bu)), 39.5 (C(t-Bu)), 61.6 (CH2O),
calcd for C12H17NO6: C, 53.13; H, 6.32; N, 5.16; found: C, 64.5 (CH2O), 68.2 (CH2O), 98.1 (bisdioxine C1/C5), 102.3
53.30; H, 6.43; N, 5.10.
(bisdioxine C4/C8), 112.2 (arom.), 114.3 (arom.), 126.6
(arom.), 128.8 (arom.), 130.9 (arom.), 153.6 (arom. C4), 163.0
Bis(2-nitro-1,4-phenylene)macrocycle 8: A sample of diacid (bisdioxine C3/C7), 169.6 (CO); LC–MS m/z: 1287.8 [M + H]+;
dichloride 3 (500 mg, 1.05 mmol) was dissolved in 25 mL of Anal. calcd for C72H106N2O18: C, 67.15; H, 8.30; N, 2.18;
toluene. The diol 7 (285 mg, 1.05 mmol) was separately found: C, 67.42; H, 8.34; N, 2.16.
dissolved in 8 mL of toluene, and 1 mL of Et3N in 17 mL of
THF was added. The two solutions were placed in separate 4,4’-(2-Nitro-1,3-phenylene) bis(4-oxabutanol) (10): A mix-
dropping funnels attached to a flask containing 80 mL of ture of 2-nitroresorcinol (2.5 g, 16.1 mmol), 4.75 g (34.2 mmol)
toluene, fitted with a reflux condenser and protected from mois- of 3-bromopropanol and 8 g (57.9 mmol) K2CO3 in 25 mL
ture. The apparatus was flushed with N2. The two solutions acetone was heated under reflux for 12 h under N2 with the
were simultaneously added dropwise to the toluene under reflux exclusion of moisture. After cooling to rt, 100 mL of water was
over a 3 h period, and the resulting mixture was heated under added, and the mixture was extracted with CH2Cl2. The organic
reflux for 20 h. After cooling to 60 °C and filtering on a folded phase was dried over Na2SO4 and concentrated in vacuo, and
filter, the resulting solution was evaporated, and the material so the resulting oily product was purified by DCFC, eluting with
obtained was triturated with 5 mL diethyl ether to form a yellow CH2Cl2/MeOH 20:1 to afford 1.18 g (27%) of light-yellow
precipitate. DCFC afforded 163 mg (23%) of yellow crystals, crystals, mp 72–73 °C; 1H NMR δ 1.99–2.05 (m, 4H, CH2),
mp 264–266 °C dec; 1H NMR δ 1.04 (s, 36H, CH3(t-Bu)), 2.18 (s, br, 2H, OH), 3.80–3.83 (m, 4H, CH2-OH), 4.20–4.23
1.10–1.15 (36H, CH3(t-Bu)), 2.11–2.15 (m, 8H, CH2), (m, 4H, O-CH2), 6.64–6.66 (m, 2H, arom. H4/H6), 7.29–7.35
3.96–4.06 (m, 12H, CH2-O), 4.43–4.48 (m, 4H, CH2O), 6.90 (m, 1H, arom. H5); 13C NMR δ 31.5 (CH2), 59.4 (CH2OH),
(m, 2H, arom. H6), 7.02 (m, 2H, arom. H5), 7.34 (m, 2H, arom. 66.6 (O-CH2), 105.5 (arom. C4/C6), 131.3 (arom. C2), 132.3
H3); 13C NMR δ 24.6 (CH3), 28.0 (two signals, CH2), 28.6 (arom. C5), 151.3 (arom. C1/C3); LC–MS (CH2Cl2) m/z: 271;
(CH3), 37.3 (C(t-Bu)), 39.5 (C(t-Bu)), 61.0 and 61.3 (two Anal. calcd for C12H17NO6: C, 53.13; H, 6.32; N, 5.16; found:
signals, CH2O), 64.9 (two signals, CH2O), 66.3 (CH2O), 98.1 C, 53.37; H, 6.42; N, 5.04.
(bisdioxine C1/C5), 102.3 (two signals, bisdioxine C4/C8),
110.4 (arom. C3), 116.0 (arom. C6), 121.3 (arom. C5), 139.5 Bis(2-nitro-1,3-phenylene)macrocycle 11: This compound
(arom. C2), 146.6 (arom. C1/C3), 152.1 (arom. C4/C6), 163.1 was prepared from the diacid dichloride 3 and the diol 10 using
(three signals, bisdioxine C3/C7), 169.4 (three signals, CO); the method described for 8. Yield 176 mg (25%), white crystals,
NMR spectra were assigned on the basis of previously reported mp 300–302 °C dec; 1H NMR δ 1.03 (s, 36H, CH3(t-Bu)), 1.09
data for related bisdioxine derivatives [3-7]; IR (KBr): (s, 36H, CH3(t-Bu)), 2.11–2.13 (m, 8H, CH2), 4.00–4.06 (m,
3000–2800, 1720, 1619, 1535 cm−1; LC–MS m/z: 1347.8 [M + 12H, CH2O), 4.37–4.40 (m, 4H, CH2O), 6.44 (m, 4H, arom.
H]+; Anal. calcd for C72H102N2O22: C, 64.16; H, 7.63; N, 2.08; H4), 7.24 (m, 2H, arom. H5); 13C NMR δ 24.5 (CH3-(t-Bu)),
found: C, 63.77; H, 7.68; N, 1.95.
27.9 (CH2), 28.4 (CH3(t-Bu)), 37.2 (C(t-Bu)), 39.4 (C(t-Bu)),
60.6 (CH2O), 65.4 and 65.4 (two signals, CH2O), 97.95 and
Bis(2-amino-1,4-phenylene)macrocycle 9: A mixture of 97.98 (two signals, bisdioxine C1/C5), 102.12, 102.14 (two
100 mg (0.07 mmol) of 8 and 40 mg (2.4 mmol) of tin granules signals, bisdioxine C4/C8), 105.1 (arom. C4), 131.1 (arom. C2),
in 10 mL of THF was heated to reflux. Subsequently, 300 µL of 132.2 (arom. C5), 150.8 (arom. C1), 162.8 (two signals,
conc. HCl was added dropwise, which resulted in strong gas bisdioxine C3/C7), 169.2 (two signals, CO); IR (KBr)
evolution. The reaction was followed by TLC (CH2Cl2/MeOH 2800–3000, 1721, 1615, 1541 cm−1; LC–MS m/z: 1347.5 [M +
100:1), which indicated completion after 1 h. The reaction mix- H]+; Anal. calcd for C72H102N2O22: C, 64.16; H, 7.63; N, 2.08;
ture was cooled, neutralized with 2 M NaOH, and filtered. The found: C, 64.32; H, 7.82; N, 2.07.
resulting solution was extracted with CH2Cl2 and concentrated,
and the residue was triturated with diethyl ether, which caused Bis(2-amino-1,3-phenylene)macrocycle 13: The dinitro com-
the formation of a white precipitate. The product was purified pound 11 (44 mg; 0.03 mmol) was reduced with 20 mg
by DCFC, eluting with hexane/diethyl ether/MeOH 100:30:2 to (1.69 mmol) of tin granules in 5 mL of THF and 150 µL of
yield 10 mg (10%) of a slightly yellow solid. 1H NMR δ 1.04 conc. HCl, as described for the reduction of 8 above. It took 3 h
(s, 36H, CH3(t-Bu)), 1.14 (s, 36H, CH3(t-Bu)), 2.06–2.08 (m, for the starting material to be fully consumed, yielding 10 mg of
8H, CH2), 3.84–4.01 (m, 12H, CH2O), 4.45–4.48 (m, 4H, the diamine as a white precipitate. 1H NMR δ 1.04–1.16 (m,
CH2O), 6.10 (m, 2H, arom. H3), 6.26 (m, 2H, arom. H5), 6.52 72H, t-Bu), 2.18 (m, 8H, CH2), 3.99–4.01 (m, 12H, CH2O),
(m, 2H, arom. H6); 13C NMR δ 24.6 (CH3(t-Bu)), 28.2 (CH2), 4.38–4.58 (m, 4H, CH2O), 6.25–6.50 (m, 6H, arom. H4, H5,
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Beilstein J. Org. Chem. 2012, 8, 738–743.
H6); 13C NMR δ 24.6 (CH3(t-Bu)), 28.5 (CH3(t-Bu)), 29.7 (UQ) and Prof. Klaus Zangger (Graz) for the recording of NMR
(CH2), 37.4 (C(t-Bu)), 39.5 (C(t-Bu)), 61.4 (CH2O), 64.5 spectra. SL gratefully acknowledges the award of a Visiting
(CH2O), 98.1 (bisdioxine C1/C5), 102.3 (bisdioxine C4/C8), Scholar stipend at UQ.
104.9 (arom. C4/C6), 117.0 (arom. C5), 146.4 (arom. C1/C3),
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Acknowledgements
This work was supported by the Karl Franzens Universität
Graz, The University of Queensland, and the Australian
Research Council. We are indebted to Ms Lynette Lambert
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Beilstein J. Org. Chem. 2012, 8, 738–743.
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