Synthesis and characterization of geminally dialkylsubstituted tetraindanotetraoxa[8]circulenes

Article abstract of DOI:10.1002/jhet.2113

A synthetic methodology for the synthesis of 2,2-dialkyl-4,7-dimethoxy-2,3- dihydro-1H-inden-1-ones from 4,7-dimethoxy-2,3-dihydro-1H-inden-1-one has been developed, and some of these compounds were converted into the corresponding geminally dialkylsubstituted tetraindanotetraoxa[8]circulenes with the expectation of obtaining discotic liquid crystalline materials.

Full text of DOI:10.1002/jhet.2113

Month 2014
Synthesis and Characterization of Geminally Dialkylsubstituted
Tetraindanotetraoxa[8]circulenes
a
a
*
Søren L. Mejlsøe and Jørn B. Christensen
Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Denmark
*
E-mail: jbc@chem.ku.dk
Received June 11, 2013
DOI 10.1002/jhet.2113
Published online 00 Month 2013 in Wiley Online Library (wileyonlinelibrary.com).
A synthetic methodology for the synthesis of 2,2-dialkyl-4,7-dimethoxy-2,3-dihydro-1H-inden-1-ones
from 4,7-dimethoxy-2,3-dihydro-1H-inden-1-one has been developed, and some of these compounds were
converted into the corresponding geminally dialkylsubstituted tetraindanotetraoxa[8]circulenes with the
expectation of obtaining discotic liquid crystalline materials.
J. Heterocyclic Chem., 00, 00 (2014).
INTRODUCTION
Erdmann [7] as one of the products formed by treatment of
1,4-benzoquinone with acids. We [8] and others [9] have
since worked with methods for synthesizing derivatives of 1a.
Tetraoxa[8]circulene is isoelectronic with the hydrocar-
bon [8]circulene (Figure 1). The first derivatives of these
were very recently reported by Wu and coworkers [10].
Isoelectronic substitution of all carbon–carbon double
bonds in the periphery with S gives octathio[8]circulene
(Figure 1) better known as “sulflower”, which was reported
by Nenajdenko and coworkers [11], and recently, a mixed
tetrathiotetraselana[8]circulene (Figure 1) was reported by
Rosei and coworkers [12]. These fully isoelectronically
substituted circulenes do, however, suffer from very low
solubility. Rajca and coworkers [13] reported an interesting
approach to quasithia[8]circulenes based on ring closure of
The discotic liquid crystals are a subset of the liquid crys-
tals [1] consisting of a core, which is usually a flat aromatic
system surrounded by alkyl chains giving rise to the forma-
tion of π-stacking in the liquid crystalline state. Such systems
are interesting for a number of applications ranging from dis-
play technology to solar cells [2]. A few examples of discotic
liquid crystals are substituted triphenylenes [3], truxenes [4],
benzene-1,3,5-tricarboxamides [5], and phthalocyanines [6].
The heteroaromatic system tetraoxa[8]circulene (1a) (or
systematically tetraphenyleno[1,16-bcd:4,5-b′c′d′:8,9-b″c″
d″:12,13-b″′c″′d″′]tetrafuran) (Figure 1) is an interesting
heteroaromatic system, which is planar and has a very high
stability. It was originally identified by Högberg and
© 2013 HeteroCorporation

S. L. Mejlsøe and J. B. Christensen
Vol 000
Figure 1. Tetraoxa[8]circulene (1a), [8]circulene (1b), octathio[8]circulene (1c), tetrathiotetraselana[8]circulene (1d), hexathio[8]circulene (1e), and
heptathia[8]circulene (1f).
helicenes, giving access to unsymmetrical quasipenta- and
quasihexathia[8]circulenes (Figure 1), which could be
potential candidates for liquid crystalline phases.
the π–π stacking of the aromatic cores as shown in Figure 2,
where the geminal disubstitution on the cyclopentanes was
expected to reduce the π–π stacking.
The simple derivatives of tetraoxa[8]circulene (1a) are
high melting compounds with very low solubilities in any
solvent, and in order to circumvent this problem, a method-
ology was devised for synthesizing octaalkyl derivatives
with the hope that they would form discotic liquid crystal-
line phases [8].
Attachment of eight medium chain alkyl groups (C6–C10)
gave derivatives, which had a discotic mesophase, but only
existing in a small temperature interval indicates that the
effect of the π–π stacking on the melting points could not
be properly balanced by adding longer aliphatic tails to the
discotic core. One possible way to solve this problem could
be to synthesize derivatives with a built-in spacer to reduce
RESULTS AND DISCUSSION
Diethyl 4,7-dimethoxy-1H-indene-2,2(3H)-dicarboxylate
(5g) [8,14] had previously been synthesized, and it was
chosen as the starting material for the synthesis of geminally
substituted octaalkyl derivatives via the corresponding bis
(hydroxymethyl) derivative (5h). However, this synthetic
route was abandoned because of reactivity problems caused
by the neopentyl-arrangement of the geminal mesylates/
chlorides (Scheme 1).
The new route, which is outlined in Scheme 2, was based
on a common intermediate 4,7-dimethoxy-2,3-dihydro-
Figure 2. The geminally dialkylsubstituted tetraindanotetraoxa[8]circulenes synthesized.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Tetraindanotetraoxa[8]circulenes
Scheme 1. First approach to a synthesis of geminally octasubstituted tetraindano[8]circulenes. a: LiAlH4/THF. b: CH3SO2Cl/pyridine. c: Ph3P/CCl4/Δ.
Scheme 2. Synthesis of the circulenes 2d–2f from 4,7-dimethoxy-2,3-dihydro-1H-inden-1-one (6).
1H-inden-1-one (5a)[18], which could be dialkylated α to
the carbonyl group by treatment with an alkyl iodide or
bromide and sodium hydride in tetrahydrofuran (THF)
to give the α,α-disubstituted indanones (5a–5f). The car-
bonyl group was easily removed by catalytic
hydrogenation with hydrogen and Pd on C in acetic acid
using perchlorid acid as a promoter [15] to give the
indanes (4a–4f). Oxidation with cerium ammonium ni-
trate in acetonitrile/water gave the intermediate quinones
in excellent yields, and tetramerization with BF3–etherate
in CH2Cl2 [8] gave the tetraindanotetraoxa[8]circulenes
(2d–2f) (Scheme 2).
The key intermediate 4,7-dimethoxy-2,3-dihydro-1H-
inden-1-one (5a) was synthesized as shown in Scheme 3
from commercially available 2,5-dimethoxybenzaldehyde
by an improved procedure [16] starting with the Knoevenagel
reaction with malonic acid followed by catalytic hydrogena-
tion, conversion to the acid chloride, and cyclization of the
crude acid chloride with anhydrous AlCl3 to give the
indanone (5a) in a good yield.
All the synthesized circulenes were pale yellow solids
that were checked for phase transitions by differential scan-
ning calorimetry (DSC); however, they did not show any
liquid crystalline behavior but did simply just melt.
Scheme 3. Synthesis of 4,7-dimethoxy-2,3-dihydro-1H-inden-1-one (5a) from 2,5-dimethoxybenzaldehyde.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

S. L. Mejlsøe and J. B. Christensen
Vol 000
2,2,9,9,16,16,23,23-Octaoctyltetraindanotetraoxa[8]
circulene (2f). This compound was synthesized from 3f using
the procedure described for the synthesis of 3d. The yield for this
reaction was 0.2 g (15%) of the desired product as a solid yellow
material, mp 122.2°C (DSC). 1H NMR (CDCl3, 300 MHz): δ
3.17 (s, 16H), 1.65–1.64 (m, 16H), 1.27–1.38 (m, 96H), 0.87
(t, 24H). 13C NMR (CDCl3, 75MHz): δ 149.9, 125.5, 115.8,
47.8, 41.8, 39.5, 32.1, 30.7, 29.9, 29.6, 25.1, 22.8, 14.3. MS
(m/z, int.): 1419 (100) (M + H+). Anal. Calcd. for C100H152O4:
C, 84.68; H, 10.80. Found: C, 84.51; H, 11.11.
2,3-Dihydro-1H-indene-4,7-dione (3a). To a solution of 4a
(1.68 g; 9.40 mmol) in MeCN (20 mL) was added a solution of
CAN (13.0 g; 23.7 mmol) in H2O (20 mL) in such a tempo that
the solution did not turn black, typically over a period of
10–20 s. The mixture was stirred for 30 min. H2O (30 mL) was
added, and most MeCN was removed on a rotary evaporator.
The product was extracted with CHCl3 (3 × 50 mL). The
combined organic phases were washed with H2O, dried
(MgSO4), and concentrated under reduced pressure. The
product was purified on a dry column (eluting from heptane
with EtOAc; 10%) yielding 1.3 g (95%) of the product as a
orange crystalline product, mp 38–40 °C. Lit. 40–42 °C [17].
1H NMR (CDCl3, 300 MHz): δ 6.66 (s, 2H), 2.81 (t, J = 7.8 Hz,
4H), 2.04 (t, J = 7.8 Hz, 2H). 13C NMR (CDCl3, 75 MHz): δ
186.5, 148.9, 136.9, 30.8, 21.5. MS (m/z, int.): 148 (100), 119
(15), 91 (88), 66 (61).
CONCLUSION
A synthetic methodology for the synthesis of 2,2-dialkyl-
4,7-dimethoxy-2,3-dihydro-1H-inden-1-ones from 4,7-dimethoxy-
2,3-dihydro-1H-inden-1-one has been developed, and some of
these compounds were converted into the corresponding
geminally dialkylsubstituted tetraindanotetraoxa[8]circulenes
with the expectation of obtaining discotic liquid crystal-
line materials. The hypothesis being that the geminal
disubstitution on the cyclopentanes was expected to re-
duce the π–π stacking between the aromatic cores to favor
formation of mesophases. The compounds did, however,
not show any signs of a mesophase as determined by DSC.
EXPERIMENTAL
Unless otherwise stated, all starting materials were obtained
from commercial suppliers and used as received. Solvents were
of high-performance liquid chromatography grade and were used
as received. Thin-layer chromatography was carried out using
aluminum sheets precoated with silica gel 60F (Merck 5554).
Dry column vacuum chromatography was carried out using silica
gel 60 (Merck 9385, 0.015–0.040 mm). Melting points were de-
termined on a Büchi melting point apparatus and are uncorrected.
1H NMR and 13C NMR spectra were recorded on a Varian
Mercury 300 MHz or a Bruker 500 MHz spectrometer. Fast atom
bombardment spectra were obtained on a Jeol JMS-HX 110
tandem mass spectrometer in the positive ion mode using
3-nitrobenzyl alcohol as matrix. matrix-assisted laser desorption/
ionization–time of flight (TOF) mass spectra were recorded on a
Bruker instrument. Electrospray ionization mass spectra were
recorded on a Micromass Q-TOF apparatus. Microanalyses were
performed by Mrs Birgitta Kegel at the Microanalytical Labora-
tory at the Department of Chemistry, University of Copenhagen.
2,2,9,9,16,16,23,23-Octabutyltetraindanotetraoxa[8]
circulene (2d). To a refluxing solution of BF3–Et2O (3.0 mL) in
CH2Cl2 (30mL) was added a solution of 3d (3.3g; 12.7 mmol) in
CH2Cl2 (50 mL) over a period of 4 h, and the mixture was
refluxed for an additional 24h. The reaction mixture was poured
into HCl(aq) (100mL; 2 M) and stirred for 10min. The phases
were separated, and the organic phase was evaporated to dryness
under reduced pressure to give a crude black material. The desired
product was purified on a dry column (eluting from heptane with
EtOAc) to yield 0.8 g (26%) of 3d as a yellow solid material, mp
2,3-Dihydro-2,2-dimethyl-1H-indene-4,7-dione (3b).
This
compound was synthesized as described for 3a but with 4b
as the starting material. The yield of this reaction was 92%
1
of 4b as an orange crystalline material, mp: 39–41 °C. H NMR
(CDCl3, 300 MHz): δ 6.66 (s, 2H), 2.61 (s, 4H), 1.17 (s, 6H). 13C
NMR (CDCl3, 75 MHz): δ 186.6, 147.7, 136.9, 45.2, 38.2,
29.6. MS (m/z, int.): 176 (43), 161 (100), 133 (23), 105 (26), 77
(26). Anal. Calcd. for C11H12O2: C, 74.98; H, 6.86. Found: C,
74.87; H, 6.98.
2,2-Dibutyl-2,3-dihydro-1H-indene-4,7-dione (3d).
This
compound was synthesized as described for 3a but with 4d as
the starting material. The yield of this reaction was 96% of 4d
1
as an orange oil. H NMR (CDCl3, 300 MHz): δ 6.63 (s, 2H),
2.57 (s, 4H), 1.42–1.37 (m, 4H), 1.30–1.14 (m, 8H), 0.87
(t, 6H). 13C NMR (CDCl3, 75 MHz): δ 186.6, 147.5, 136.9, 44.0,
42.1, 39.6, 26.8, 23.5, 14.2. MS (m/z, int.): 260 (18), 203 (86),
175 (31), 161 (100), 91 (26). Anal. Calcd. for C17H24O2: C,
78.42; H, 9.29. Found: C, 78.10; H, 9.55.
2,2-Dihexyl-2,3-dihydro-1H-indene-4,7-dione (3e).
This
compound was synthesized as described for 3a but with 4e as
the starting material. The yield of this reaction was 95% of 3e
1
1
231.3 °C (DSC). H NMR (CDCl3, 300MHz): δ 3.18 (s, 16H),
as an orange oil. H NMR (CDCl3, 300 MHz): δ 6.64 (s, 2H),
1.65–1.70 (m, 16H), 1.37–1.32 (m, 32H), 0.94 (t, J = 6.6 Hz,
24H). 13C NMR (CDCl3, 75MHz): δ 149.9, 125.5, 115.8, 47.7,
41.8, 39.2, 27.3, 23.8, 14.4. MS (m/z, int.): 968 (100) (M+). Anal.
Calcd. for C68H88O4: C, 84.25; H, 9.15. Found: C, 83.56; H, 9.63.
2,2,9,9,16,16,23,23-Octahexyltetraindanotetraoxa[8]
circulene (2e). This compound was synthesized from 3e using
the procedure described for the synthesis of 2d. The yield for this
reaction was 0.2 g (13%) of the desired product as a solid yellow
material, mp 188.5°C (DSC). 1H NMR (CDCl3, 300 MHz): δ
3.17 (s, 16H), 1.62–1.65 (m, 16H), 1.31–1.40 (m, 64H), 0.89
(t, 24H). 13C NMR (CDCl3, 75 MHz): δ 149.9, 125.4, 115.7,
47.8, 41.8, 39.5, 32.1, 30.4, 25.0, 22.9, 14.3. MS (m/z, int.): 1193
(100) (M+). Anal. Calcd. for C84H120O4: C, 84.51; H, 10.13.
Found: C, 84.11; H, 10.31.
2.58 (s, 4H), 1.42–1.37 (m, 4H), 1.25–1.24 (m, 16H), 0.87
(t, 6H). 13C NMR (CDCl3, 75 MHz): δ 186.6, 147.5, 136.9, 44.0,
42.1, 39.9, 31.9, 30.1, 24.5, 22.7, 14.2. MS (m/z, int.): 316 (20),
245 (22), 231 (82), 161 (100). Anal. Calcd. for C21H32O2: C,
79.70; H, 10.19. Found: C, 79.39; H, 10.17.
2,3-Dihydro-2,2-dioctyl-1H-indene-4,7-dione (3f).
This
compound was synthesized as described for 3a but with 4f as
the starting material. The yield of this reaction was 92% of 3f as
1
an orange oil. H NMR (CDCl3, 300 MHz): δ 6.64 (s, 2H), 2.58
(s, 4H), 1.42–1.37 (m, 4H), 1.31–1.24 (m, 24H), 0.86 (t, 6H).
13C NMR (CDCl3, 75 MHz): δ 186.6, 147.5, 136.9, 44.1, 42.1,
39.9, 32.0, 30.4, 29.7, 29.4, 24.6, 22.8, 14.2. MS (m/z, int.):
373 (100), 259 (77), 161 (51). Anal. Calcd. for C25H40O2: C,
80.59; H, 10.82. Found: C, 80.11; H, 11.25.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Tetraindanotetraoxa[8]circulenes
4,7-Dimethoxyindane (4a).
A solution of 5a (3.46 g;
4,7-Dimethoxyindane-1-one (5a). A mixture of 6 (20.0 g;
71.0 mmol), dimethylformamide (DMF, two drops), and SOCl2
(20.40 g; 12.43 mL; 171.0 mmol) was refluxed for 5 h and
cooled on an ice bath. CH2Cl2 (200 mL) was added and the
mixture cooled to -5 to -10 °C. AlCl3 (25.23 g; 0.19 mol) was
added over a period of 45 min under vigorous stirring, and the
reaction was stirred for an additional 5 min. The reaction
mixture was poured into ice water (300 mL) and stirred
vigorously for 10 min. The two phases were separated, and the
organic phase was washed with H2O (100 mL) followed by
vigorous stirring with saturated NaHCO3(aq) (3 × 150 mL,
10 min each). The organic phase was dried (MgSO4) and
filtered, and the volatile components were removed under
reduced pressure to give a yellow solid material. After a few
hours on a vacuum line, the product was mechanically crushed
and stirred in Et2O (80 mL) for 1.5 h. The product was collected
on a glass filter funnel with suction and dried under reduced
pressure overnight to give 13.1 g (72%) of the product as a pale
yellow powder, mp 122–123 °C. Lit.: 124.5–125 °C (Et2O) [18].
1H NMR (CDCl3, 300 MHz): δ 6.98 (d, J = 8.7 Hz, 1H), 6.73 (d,
J = 8.7 Hz, 1H), 3.90 (s, 3H), 3.85 (s, 3H), 2.98 (t, J = 6.0 Hz,
2H), 2.67 (t, J = 6.0 Hz, 2H). 13C NMR (CDCl3, 75 MHz): δ
205.2, 151.9, 150.6, 146.1, 126.5, 116.7, 109.5, 56.1, 56.0,
36.9, 22.4. MS (m/z, int.): 192 (100), 177 (25), 163 (99), 149
(36) 121 (30).
4,7-Dimethoxy-2,2-dimethylindane-1-one (5b). To a solution
of 6 (5.1 g; 26.5 mmol) in THF (130mL) was added under stirring
NaH (1.7g; ~63.8 mmol) and then MeI (8.9 g; 3.9 mL;
62.7mmol), and it was stirred for about 5 h. The reaction mixture
was poured into H2O (300 mL), and the mixture was made
weakly acidic by an addition of HCl(aq) (2M). The product was
extracted with Et2O/THF (1:1; 100 mL) and then with Et2O
(3× 100 mL). The combined organic phases were washed with
saturated NaHCO3(aq), dried (MgSO4), and concentrated under
reduced pressure to give an orange to brown crude product. The
crude product was purified using a dry column (eluting from
heptane with EtOAc; 10%) to give 3.8g (65%) of the desired
product as yellow crystals, mp 69–70°C. 1H NMR (CDCl3,
300 MHz): δ 6.99 (d, J = 8.7 Hz, 1H), 6.73 (d, J = 8.7Hz, 1H),
3.90 (s, 3H), 3.84 (s, 3H), 2.86 (s, 2H), 1.21 (s, 6H). 13C NMR
(CDCl3, 75MHz): δ 209.5, 152.3, 150.6, 142.9, 124.6, 116.7,
109.6, 56.1, 55.9, 45.6, 39.3, 25.6. MS (m/z, int.): 220 (95), 205
(100), 187 (64), 175 (23). Anal. Calcd. for C13H16O3: C, 70.89;
H, 7.32. Found: C, 70.86; H, 7.30.
18.0 mmol), Pd-C (1.38 g; 10% Pd on carbon) and HClO4
(1.1 mL; 70% in H2O) in HOAc (50 mL) was treated with H2 at
55 psi (H2) for 2.5 h. The reaction mixture was then treated with
NaOAc(s) (1.45 g; 18.0 mmol) to remove HClO4. The mixture
was filtered through a plug of celite with suction. The filtrate
was added H2O (300 mL), and the product was extracted with
CHCl3 (3 × 70 mL). The combined organic phases were washed
with H2O (200 mL), dried (MgSO4), and concentrated under
reduced pressure to yield 2.8 g (87%) of the product as a
white solid material, mp 78–80 °C. Lit.: 65–66 °C (Et2O) [15],
85–85.5 °C [18]. 1H NMR (CDCl3, 300 MHz): δ 6.61 (s, 2H),
3.79 (s, 6H), 2.88 (t, 4H), 2.13–2.03 (m, 2H). 13C NMR
(CDCl3, 75 MHz): δ 150.5, 133.9, 108.7, 55.8, 30.1, 24.9. MS
(m/z, int.): 178 (92), 163 (100), 103 (29), 91 (20).
4,7-Dimethoxy-2,2-dimethylindane (4b).
was synthesized from 5b using the procedure described for 4a.
The yield for this procedure was 1.8 g (88%) of the product as a
white solid material, mp 54–56°C. H NMR (CDCl3, 300MHz):
This compound
1
δ 6.61 (s, 2H), 3.78 (s, 6H), 2.70 (s, 4H), 1.16 (s, 6H). 13C NMR
(CDCl3, 75 MHz): δ 150.7, 132.9, 108.6, 55.8, 44.9, 40.0, 29.5.
MS (m/z, int.): 206 (100), 191 (53), 176 (11), 161 (12). Anal.
Calcd. for C13H18O2: C, 75.69; H, 8.80. Found: C, 75.76; H, 8.91.
2,2-Diethyl-4,7-dimethoxyindane (4c). This compound was
synthesized from 5c using the procedure described for 4a. The
yield for this procedure was 0.7 g (88%) of the product as a white
solid material, mp 38–40 °C. 1H NMR (CDCl3, 300MHz): δ 6.60
(s, 2H), 3.78 (s, 6H), 2.69 (s, 4H), 1.49 (q, J = 7.5 Hz, 4H), 0.85
(t, J = 7.5 Hz, 6H). 13C NMR (CDCl3, 75 MHz): δ 150.5, 132.8,
108.4, 55.8, 46.3, 41.0, 31.2, 9.1. MS (m/z, int.): 234 (100), 205
(25), 175 (13), 149 (17), 91 (16). Anal. Calcd. for C15H22O2: C,
76.88; H, 9.46. Found: C, 77.20; H, 9.69.
2,2-Dibutyl-4,7-dimethoxyindane (4d).
This compound
was synthesized from 5d using the procedure described for 4a
(hydrogenation was complete after 4 h). The yield for this
procedure was 6.8 g (87%) of the product as a clear, almost
1
colorless oil. H NMR (CDCl3, 300 MHz): δ 6.61 (s, 2H), 3.79
(s, 6H), 2.73 (s, 4H), 1.48–1.43 (m, 4H), 1.33–1.24 (m, 8H),
0.91 (t, 6H). 13C NMR (CDCl3, 75 MHz): δ 150.4, 132.7,
108.4, 55.7, 45.6, 41.9, 39.3, 27.1, 23.7, 14.3. MS (m/z, int.):
290 (100), 191 (11), 177 (34), 152 (13). Anal. Calcd. for
C19H30O2: C, 78.57; H, 10.41. Found: C, 78.34; H, 10.66.
2,2-Dihexyl-4,7-dimethoxyindane (4e).
was synthesized from 5e using the procedure described for 4a
This compound
(hydrogenation was complete after 4.5 h). The yield for this
procedure was 1.5 g (81%) of the product as a yellowish oil. H
2,2-Diethyl-4,7-dimethoxyindane-1-one (5c). This compound
was synthesized by alkylation of 5a with EtI as described for 5b.
The yield of this procedure was 1.2 g (66%) of the product as a
yellow crystalline material, mp 75–76°C. 1H NMR (CDCl3,
300 MHz): δ 6.97 (d, J = 8.7 Hz, 1H), 6.71 (d, J = 8.7Hz, 1H),
3.89 (s, 3H), 3.86 (s, 3H), 2.83 (s, 2H), 1.73–1.52 (m, 4H), 0.78
(t, J = 7.5 Hz, 6H). 13C NMR (CDCl3, 75 MHz): δ 209.6, 151.7,
150.4, 144.2, 126.7, 116.5, 109.4, 56.1, 55.9, 53.5, 33.2, 30.0,
8.8. MS (m/z, int.): 248 (66), 219 (100), 205 (88), 191 (54). Anal.
Calcd. for C15H20O3: C, 72.55; H, 8.12. Found: C, 72.65; H, 8.22.
2,2-Dibutyl-4,7-dimethoxyindane-1-one (5d). This compound
was synthesized by alkylation of 6 with n-butyl iodide as described
for 4. The yield of this procedure was 9.1 g (64%) of the product as
a yellow crystalline material, mp. 71–72 °C. 1H NMR (CDCl3,
300 MHz): δ 6.97 (d, J = 8.7 Hz, 1H), 6.71 (d, J = 8.7 Hz, 1H),
3.89 (s, 3H), 3.86 (s, 3H), 2.85 (s, 2H), 1.66–1.48 (m, 4H),
1.27–1.02 (m, 8H), 0.82 (t, J = 7.2 Hz, 6H). 13C NMR (CDCl3,
75 MHz): δ 209.8, 151.7, 150.3, 144.2, 126.6, 116.5, 109.4,
1
NMR (CDCl3, 300 MHz): δ 6.60 (s, 2H), 3.78 (s, 6H), 2.70
(s, 4H), 1.45–1.40 (m, 4H), 1.31–1.25 (m, 16H), 0.87 (t, 6H).
13C NMR (CDCl3, 75 MHz): δ 150.4, 132.7, 108.4, 55.7, 45.8,
41.9, 39.6, 32.0, 30.3, 24.8, 22.9, 14.3. MS (m/z, int.): 346
(100), 189 (13), 177 (33), 152 (9). Anal. Calcd. for C23H38O2:
C, 79.71; H, 11.05. Found: C, 79.71; H, 11.05.
4,7-Dimethoxy-2,2-dioctylindane (4f). This compound was
synthesized from 5f using the procedure described for 4a
(hydrogenation of this compound was complete after 5 h). The
yield for this procedure was 2.4 g (84%) of the product as a
yellow oil. 1H NMR (CDCl3, 300 MHz): δ 6.60 (s, 2H), 3.78
(s, 6H), 2.70 (s, 4H), 1.42–1.25 (m, 28H), 0.88 (t, 6H). 13C
NMR (CDCl3, 75 MHz): δ 150.5, 132.8, 108.4, 55.8, 45.8, 41.9,
39.6, 32.1, 30.7, 29.8, 29.5, 24.8, 22.8, 14.3. MS (m/z, int.):
402 (100), 189 (14), 177 (37), 152 (10). Anal. Calcd. for
C27H46O2: C, 80.54; H, 11.51. Found: C, 80.81; H, 11.84.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

S. L. Mejlsøe and J. B. Christensen
Vol 000
56.1, 55.9, 52.8, 37.8, 34.1, 26.5, 23.5, 14.1. MS (m/z, int.): 304
(5), 248 (33), 205 (100). Anal. Calcd. for C19H28O3: C, 74.96; H,
9.27. Found: C, 74.88; H, 9.47.
concentrated in vacuo. The product was purified by dry
column chromatography (eluting from heptane with EtOAc)
to yield 0.12 g (22%) of C, as a solid white material, mp
50–52 °C. 1H NMR (CDCl3, 300 MHz): δ 6.63 (s, 2H), 3.77
(s, 6H), 3.73 (s, 4H), 2.94 (s, 4H). 13C NMR (CDCl3,
75 MHz): δ 150.5, 130.1, 109.2, 55.7, 50.1, 49.9, 38.4. MS
(m/z, int.): 274 (100) (M+). Anal. Calcd. for C13H16O2Cl2: C,
56.74; H, 5.86; Cl, 25.77. Found: C, 57.11; H, 5.91; Cl, 25.61.
3-(2,5-Dimethoxy-phenyl)-propanoic acid (6). A mixture
of 7 (15.0 g; 72.0 mmol) and Pd-C (1.5 g; 10% Pd on carbon) in
EtOAc (180 mL) was treated with H2 overnight at 40 psi (H2).
The reaction mixture was filtered through a plug of celite with
suction, and the volatile components were removed under reduced
pressure to leave a colorless oil, which crystallized after a few
minutes on an ice bath, yielding 14.8g (98%) of the desired
product as a colorless solid material, mp 63–64°C. Lit.: 65–66°C
2,2-Dihexyl-4,7-dimethoxyindane-1-one (5e). This compound
was synthesized by alkylation of 5a with n-hexyl bromide as
described for 5b. The yield of this procedure was 2.7 g (61%) of
1
the product as a yellow oil. H NMR (CDCl3, 300 MHz): δ 6.97
(d, 1H), 6.71 (d, 1H), 3.88 (s, 3H), 3.85 (s, 3H), 2.84 (s, 2H),
1.65–1.48 (m, 4H), 1.26–1.13 (m, 16H), 0.82 (t, 6H). 13C NMR
(CDCl3, 75 MHz): δ 209.8, 151.7, 150.3, 144.1, 126.5, 116.5,
109.4, 56.1, 55.9, 52.9, 38.0, 34.1, 31.8, 30.1, 24.3, 22.8, 14.2.
MS (m/z, int.): 360 (4), 276 (37), 205 (100). Anal. Calcd. for
C23H36O3: C, 76.62; H, 10.06. Found: C, 76.86; H, 10.31.
2,2-Dioctyl-4,7-dimethoxyindane-1-one (5f). This compound
was synthesized by alkylation of 5a with n-octyl iodide as
described for 5b. The yield of this procedure was 2.4 g (52%) of
1
1
the product as a yellow oil. H NMR (CDCl3, 300 MHz): δ 6.96
(ether-pet.ether) [18]. H NMR (CDCl3, 300 MHz): δ 6.78–6.69
(d, J = 8.7 Hz, 1H), 6.71 (d, J = 8.7 Hz, 1H), 3.88 (s, 3H), 3.85 (s,
3H), 2.84 (s, 2H), 1.64–1.48 (m, 4H), 1.26–1.19 (m, 24H), 0.84
(t, J = 6.9 Hz, 6H). 13C NMR (CDCl3, 75 MHz): δ 209.7, 151.7,
150.3, 144.1, 126.5, 116.4, 109.4, 56.1, 55.9, 52.9, 38.0, 34.1,
32.0, 30.4, 29.6, 29.4, 24.4, 22.8, 14.2. MS (m/z, int.): 416 (3),
304 (48), 205 (100). Anal. Calcd. for C27H44O3: C, 77.83; H,
10.64. Found: C, 77.59; H, 10.78.
(m, 3H), 3.78 (s, 3H), 3.75 (s, 3H), 2.92 (t, J = 7.8 Hz, 2H), 2.65
(t, J = 7.8 Hz, 2H). 13C NMR (CDCl3, 75 MHz): δ 178.9, 153.5,
151.9, 129.8, 116.5, 111.8, 111.2, 55.89, 55.85, 34.0, 26.2. MS
(m/z, int.): 210 (100), 177 (21), 151 (50), 135 (17), 121 (31).
3-(2,5-Dimethoxy-phenyl)-acrylic acid (7). Procedure as described
in organic synthesis for the synthesis of 2,3-dimethoxycinnamic
acid [19].
In a 1000-mL three-necked, round-bottomed flask fitted
Diethyl 4,7-dimethoxy-1H-indene-2,2(3H)-dicarboxylate (5g). This
was synthesized according to the published procedure [8,14].
(4,7-Dimethoxy-2,3-dihydro-1H-indene-2,2-diyl)dimethanol
(5h). To a solution of diethyl 4,7-dimethoxy-1H-indene-2,2-
(3H)-dicarboxylate (5g) (16.1 g; 50.0mmol) in THF (100 mL) was
added dropwise a mixture of LiAlH4 (2.1g; 50.0mmol) in THF
(70 mL) over a period of 15 min, and the reaction was stirred
overnight. Water was added dropwise until the reaction mixture
became greenish followed by stirring for an additional 20min.
The mixture was vacuum filtered through a plug of celite, and the
filtrate was concentrated in vacuo to give 11.6 g (97%) of the diol
(5h) as a solid white material, mp 151–152 °C. 1H NMR (CDCl3,
300 MHz): δ 6.62 (s, 2H), 3.772 (s, 6H), 3.769 (s, 4H), 2.79 (s,
4H), 1.94 (s, 2H). 13C NMR (CDCl3, 75MHz): δ 150.6, 131.2,
109.0, 70.0, 55.7, 48.9, 35.9. MS (m/z, int.): 238.10 (70), 231.11
(100). Anal. Calcd. for C13H18O4: C, 65.53; H, 7.61. Found: C,
65.48; H, 7.63.
with reflux condensator and thermometer was placed 1,4-
dimethoxybenzaldehyde (83.0 g; 0.5 mol) malonic acid (104.0 g;
1.0 mol) and pyridine (200 mL). The mixture was slowly heated
to 50 °C, and the temperature was held until all the malonic acid
has dissolved. Piperidine (7.5 mL) was added. The temperature
was over 30 min raised to 80 °C and held for 1 h followed by
heating to reflux and refluxed for an additional 3 h. The reaction
mixture was allowed to cool to RT, poured into cold H2O
(2000 mL), and made acidic slowly by an addition of HCl(aq)
(conc.; 250 mL) with stirring. The yellow precipitate was
collected on a glass filter funnel with suction, washed with
cold H2O (4 × 100 mL), and dissolved in NaOH(aq) (0.67 M;
1500 mL). The solution was filtered, added with H2O (600 mL),
and acidified by an addition of HCl(aq) (6 M; 300 mL) with stir-
ring. The yellow crystals were collected on a glass filter funnel
with suction and washed with cold H2O (3 × 100 mL). The prod-
uct was dried in a vacuum oven at 75 °C for 3 days to yield 95.7 g
(92%) of the pure product as a yellow crystalline material, mp
138–140 °C (H2O). Lit.: 147 °C [20]. 1H NMR (CDCl3,
300 MHz): δ 11.18 (s, 1H), 8.08 (d, J = 16.2 Hz, 1H), 7.07
(d, J = 3.0 Hz, 1H), 6.96–6.85 (m, 2H), 6.52 (d, J = 16.2 Hz, 1H),
3.86 (s, 3H), 3.80 (s, 3H). 13C NMR (CDCl3, 75MHz): δ 171.9,
153.7, 153.2, 142.3, 123.7, 117.91, 117.85, 113.6, 112.7, 56.2,
56.0. MS (m/z, int.): 208 (M+:100).
(4,7-Dimethoxy-2,3-dihydro-1H-indene-2,2-diyl)bis(methylene)
bismethanesulfonate (5i). To a stirring solution of compound 5h
(10.0 g; 42.0mmol) in CH2Cl2 (200mL) was added MeSO2Cl
(11.0 g; 7.4mL; 96.0mmol) and pyridine (6.64g; 84.0mmol).
When the reaction was complete, the volatile components were
removed under reduced pressure to give a yellow oil, which was
crystallized from MeOH to yield a white powder. The powder
was dried in vacuo overnight to give 15.5 g (94%) of the desired
1
product as a white powder, mp. 129–130 °C. H NMR (CDCl3,
300 MHz): δ 6.64 (s, 2H), 4.24 (s, 4H), 3.77 (s, 6H), 3.05 (s, 6H),
2.89 (s, 4H). 13C NMR (CDCl3, 75 MHz): δ 150.5, 129.3, 109.5,
70.9, 55.7, 46.9, 37.5, 35.9. MS (m/z, int.): 394 (52), 187 (100).
Anal. Calcd. for C15H22O8S2: C, 45.67; H, 5.62; S, 16.26. Found:
C, 45.68; H, 5.58; S, 15.86.
2,2-Bis(chloromethyl)-4,7-dimethoxy-2,3-dihydro-1H-indene
(5j). Ph3P (1.2 g; 4.6 mmol) was added to a slurry of compound
(0.47 g; 2 mmol) in a mixture of CCl4 (25 mL) and DMF
(15 mL). The reaction mixture was refluxed for 3 days,
poured into H2O (400 mL), and extracted with THF/Et2O
(1:1; 2 × 50 mL). The collected organic phases were washed
with H2O (250 mL) and brine, dried (MgSO4), and
REFERENCES AND NOTES
[1] Chandrasekhar, S. Liq Cryst 1993, 14, 3.
[2] (a) Laschat, S.; Baro, A.; Steinke, N.; Giesselmann, F.; Hagele, C.;
Scalia, G.; Judele, R.; Kapatsina, E.; Sauer, S.; Schreivogel, A.; Tosoni, M.
Angew Chem Int Ed 2007, 46, 4832 (b) Sergeyev, S.; Pisula, W.;
Geerts, Y. H. Chem Soc Rev 2007, 36, 1902.
[3] Kumar, S. Liq Cryst 2004, 31, 1037.
[4] Isoda, K.; Yasuda, T.; Kato, T. Chem-an Asian J 2009, 4, 1619.
[5] Cantekin, S.; de Greef, T. F. A.; Palmans, A. R. A. Chem Soc
Rev 41, 6125.
[6] Hanack, M.; Lang, M. Adv Mater 1994, 6, 819.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Tetraindanotetraoxa[8]circulenes
[7] (a) Berg, J. E.; Erdtman, H.; Hoegberg, H. E.; Karlsson, B.;
[11] Chernichenko, K. Y.; Sumerin, V. V.; Shpanchenko, R. V.;
Balenkova, E. S.; Nenajdenko, V. G. Angew Chem Int Ed 2006, 45, 7367.
[12] MacLeod, O. I. J. M.; Chernichenko, K. Y.; Balenkova, E. S.;
Shpanchenko, R. V.; Nenajdenko, V. G.; Rosei, F.; Perepichka, D. F.
Chem Commun 2009, 1192.
Pilotti, A. M.; Soederholm, A. C. Tetrahedron Lett 1977, 1831 (b)
Erdtman, H.; Hogberg, H. E. Tetrahedron 1979, 35, 535 (c) Erdtman, H.;
Hogberg, H. E. Tetrahedron Lett 1970, 3389 (d) Erdtman, H.; Hogberg, H. E.
Chem Commun 1968, 773.
[13] Rajca, A.; Miyasaka, M.; Xiao, S.; Boratýnski, P. J.; Pink, M.;
Rajca, S. J Org Chem 2009, 74, 9105.
[14] Hammershoj, P.; Christensen, J. B. Acta Crystallogr, Sect E:
Struct Rep Online 2005, 61, o3468.
[15] Panetta, C. A.; Sha, D.; Torres, E.; He, Z.; Hussey, C. L.; Fang, Z.;
Heimer, N. E. Synthesis 1997, 1085.
[8] (a) Eskildsen, J.; Reenberg, T.; Christensen, J. B. Eur J Org
Chem 2000, 1637 (b) Eskildsen, J. H.; P.; Reenberg, T. K.; Larsen, U.;
Pittelkow, M.; Leth, S. M.; Peck, R.; Christensen, J. B. Asian Chem. Lett.
2007, 11, 211 (c) Nielsen, C. B.; Brock-Nannestad, T.; Reenberg, T. K.;
Hammershoj, P.; Christensen, J. B.; Stouwdam, J. W.; Pittelkow, M.
Chem-a Eur. J. 16, 13030.
[16] (a) Al-Hamdany, R.; Bruce, J. M.; Heatley, F.; Khalafy, J.,
J. Chem. Soc. Perkin Trans. II 1985, 1395 (b) Etomi, N.; Kumamoto, T.,
Nakanishi, W., Ishikawa, T. Beilstein J Org Chem 2008, 4, 1.
[17] Posternak, T.; Castro, R. d. O., Helv Chim Acta 1948, 31, 536.
[18] Arnold, R. T.; Zaugg, H. E. J Am Chem Soc 1941, 63, 1317.
[19] Koo, J.; Fish, M. S.; Walker, G. N.; Blake, J. Org Synth 1963,
Coll Vol. 4, 327.
[9] (a) Brock-Nannestad, T.; Nielsen, C. B.; Schau-Magnussen, M.;
Hammershoj, P.; Reenberg, T. K.; Petersen, A. B.; Trpcevski, D.;
Pittelkow, M. Eur J Org Chem 6320 (b) Nielsen, C. B.; Brock-Nannestad, T.;
Hammershoj, P.; Reenberg, T. K.; Schau-Magnussen, M.; Trpcevski, D.;
Hensel, T.; Salcedo, R.; Baryshnikov, G. V.; Minaev, B. F.; Pittelkow, M.
Chem-a Eur. J. 19, 3898 (c) Rathore, R.; Abdelwahed, S. H. Tetrahedron Lett
2004, 45, 5267.
[10] Feng, C.-N.; Kuo, M.-Y.; Wu, Y.-T. Angew Chem Int Ed
2013, 52, 7791.
[20] Royer, R.; Bodo, B.; Demerseman, P.; Clacel, J.-M. Bull Soc
Chim France 1971, 2929.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet