A general approach toward Janus diones: synthesis of dicyclopenta[b,g]naphthalene-1,3,6,8(2H,7H)-tetraone

Article abstract of DOI:10.1016/j.tetlet.2008.10.028

A general approach toward Janus diones involving the reaction of pyromellitic or naphthalenetetracarboxylic dianhydrides with ethyl(triphenylphosphoranylidene)acetate and subsequent rearrangement of the products is described. This approach allows avoiding the formation of poorly soluble intermediates, in which purity cannot be effectively controlled. Dicyclopenta[b,g]naphthalene-1,3,6,8(2H,7H)-tetraone 3, a promising precursor of molecular and polymeric advanced materials is described.

Full text of DOI:10.1016/j.tetlet.2008.10.028

Tetrahedron Letters 49 (2008) 7276–7278
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Tetrahedron Letters
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A general approach toward Janus diones: synthesis of
dicyclopenta[b,g]naphthalene-1,3,6,8(2H,7H)-tetraone
*
Claude Niebel, Vladimir Lokshin, Vladimir Khodorkovsky
Centre Interdisciplinaire de Nanoscience de Marseille CINaM (UPR CNRS 3118), Université de la Méditerranée, 13288 Marseille Cedex 9, France
a r t i c l e i n f o
a b s t r a c t
Article history:
A general approach toward Janus diones involving the reaction of pyromellitic or naphthalenetetracarb-
oxylic dianhydrides with ethyl(triphenylphosphoranylidene)acetate and subsequent rearrangement of
the products is described. This approach allows avoiding the formation of poorly soluble intermediates,
in which purity cannot be effectively controlled. Dicyclopenta[b,g]naphthalene-1,3,6,8(2H,7H)-tetraone
3, a promising precursor of molecular and polymeric advanced materials is described.
Ó 2008 Elsevier Ltd. All rights reserved.
Received 22 August 2008
Revised 2 October 2008
Accepted 6 October 2008
Available online 11 October 2008
Keywords:
Arenes
S-indacene
Polyketones
Indandiones
NLO chromophores
Recently, we described an efficient synthesis of the elusive s-
indacene-1,3,5,7(2H,6H)-tetraone (Janus dione) 1.1 This compound
is a strong electron acceptor and can be used as a precursor for
the preparation of reversible multi-stage redox systems, such as
dianion 22 and highly efficient two-photon absorbing (TPA) chro-
mophores.3 Moreover, 1,3-indandiones are employed as precursors
naphthalenetetracarboxylic dianhydride with ethyl acetoacetate
in the presence of triethylamine in acetic anhydride yielded a com-
plex mixture of insoluble products. One of the problems was that
2,3,6,7-naphthalenetetracarboxylic dianhydride, as described in,5
appeared to be not the individual compound. However, using the
pure samples of the dianhydride6 also did not afford acceptable
CN
NC
NC
NC
CN
CN
O
O
O
O
O
O
O
O
CN
NC
3
2
1
for the preparation of C60 and higher fullerenes (see4 and refer-
ences cited therein), and using the symmetrical Janus diones opens
new flexible synthetic routes. From this point of view, hitherto un-
known naphthalene-derived analogue (dicyclopenta[b,g]naphtha-
lene-1,3,6,8(2H,7H)-tetraone) 3 presents a special interest as a
full fragment of the C60 molecule.
yields of the desired product. Therefore, we investigated different
approaches, in particular, the rearrangement of ylidene derivatives
4a and 4b, which are easily available by the Wittig reaction of
2,3,6,7-naphthalenetetracarboxylic dianhydride with ethyl(triphe-
nylphosphoranylidene)acetate7 (Scheme 1).
Herein, we report on a simple and general approach applicable
for the preparation of a variety of 1,3-indandione derivatives, in
particular those that are especially prone to self-condensation like
Janus diones 1 and 3.
Our first attempts to prepare 3 using the same method em-
ployed for the synthesis of 1 failed. The condensation of 2,3,6,7-
Phthalylideneacetic acid rearranges into unstable 1,3-indandi-
* Corresponding author. Tel.: +33 0 4 91 82 93 22; fax: +33 0 4 91 82 93 01.
E-mail address: khodor@luminy.univ-mrs.fr (V. Khodorkovsky).
one-2-carboxylic acid in the presence of alcoholates.8 We found that
0040-4039/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2008.10.028

C. Niebel et al. / Tetrahedron Letters 49 (2008) 7276–7278
7277
OEt
O
O
O
O
O
O
O
4a
O
Ph3P=CHCOOEt
+
O
O
EtO
O
O
O
O
O
O
1. MeONa
2. Bu4NOH
O
O
4b
EtO
OEt
O
O
O
O
EtO
O
O
OEt
O
O
O
O
EtO
O
O
H
6
H
Bu4N
+
H
OEt
O
O
EtO
O
2Bu4N
5
O
OEt
O
O
H
7
- CH2=CH2
-CO2
O
O
O
O
O
O
O
Br2
Br
Br
Br
Br
O
8
3
Scheme 1.
the rearrangement of ester derivatives 4a and 4b, both as individual
compounds and as a mixture, can also be achieved with sodium
methanolate in a high yield. However, the resulting disodium salt
is only poorly soluble and its purity cannot be effectively controlled.
Therefore, conversion of the disodium salt into the more soluble TBA
salt 5 is desirable to prevent the formation, upon acidification, of the
mono-anionic salt 6, which is practically insoluble in water and
organic solvents.9 The rearrangement can also be achieved using
TBA hydroxide, however, in this case we observed the formation
of considerable amounts of salt 6. Neutralization of this salt requires
prolonged action of an acid, and thus is accompanied by the forma-
tion of 3 and its further immediate polymerization.
Acidification of 5 dissolved in acetonitrile afforded diester 7.
Refluxing 7 in anhydrous acetonitrile led to slow precipitation of
3 as colorless leaflets.10 This compound is poorly soluble in organic
solvents, insoluble in water and, like the most of 2-unsubstituted
1,3-indandione derivatives, easily undergoes self-condensation in
the presence of acids and bases. Following the same procedure,
R1
R1
N
R2
N
R2
O
O
O
O
O
O
O
O
10
9
R2
N
R2
N
R1
R1
R1 = CH2COOEt
R2 = C16H33

7278
C. Niebel et al. / Tetrahedron Letters 49 (2008) 7276–7278
detailed account of the TPA properties of derivatives 9 and 10 will
be published elsewhere.
In summary, the rearrangement of derivatives 4 in the presence
of sodium methanolate and using the soluble TBA salt 5 enable the
preparation of both known Janus dione 1 and new derivative 3 in
high yields. Both compounds are valuable precursors for the syn-
thesis of molecular and polymeric advanced materials.
Acknowledgments
We thank the French Ministry of Education and Ecole Doctorale
des Sciences Chimiques (ED 250, Marseille) for a fellowship to C.N.
The authors are thankful to Dr. P. Krief for helpful discussions.
Figure 1. Ortep plot of 8 at 50% probability level. Selected distances in Å: C1–C2
1.414(5); C2–C3 1.371(5); C3–C4 1.474(5); C4–C5 1.539(6); C3–C7 1.411(5); C4–O1
1.200(5); C5–Br1 1.938(4).
References and notes
1. Krief, P.; Becker, J. Y.; Ellern, A.; Khodorkovsky, V.; Neilands, O. Synthesis 2004,
2509–2512.
2. Krief, P. Janus Dione: An Old-new Precursor for Advanced Materials. Ph.D. Thesis,
Ben Gurion University of the Negev, Beer Sheva, Israel, 2004, 93p.
3. (a) Gvishi, R.; Berkovic, G.; Kotler, Z.; Krief, P.; Becker, J. Y.; Khodorkovsky, V.
Proc. SPIE Int. Soc. Opt. Eng. 2001, 4262, 340–346; (b) Gvishi, R.; Berkovic, G.;
Kotler, Z.; Krief, P.; Sigalov, M.; Shapiro, L.; Khodorkovsky, V. Proc. SPIE Int. Soc.
Opt. Eng. 2003, 5036, 437–442; (c) Gvishi, R.; Berkovic, G.; Kotler, Z.; Krief, P.;
Shapiro, L.; Skorka, J.; Klug, J. T.; Khodorkovsky, V. Proc. SPIE Int. Soc. Opt. Eng.
2003, 5211, 82–90.
4. Amsharov, K. Yu.; Jansen, M. J. Org. Chem. 2008, 73, 2931–2934.
5. Webster, O. W.; Sharkey, W. H. J. Org. Chem. 1962, 27, 3354–3355.
6. Niebel, C.; Lokshin, V.; Khodorkovsky, V. Tetrahedron Lett. 2008, 49, 5551–
5552.
7. Niebel, C.; Lokshin, V.; Sigalov, M.; Krief, P.; Khodorkovsky, V. Eur. J. Org. Chem.
2008, 21, 3689–3699.
8. Gabriel, S.; Neumann, A. Ber. Deutsch. Chem. Ges. 1893, 26, 951–955.
9. Sodium methanolate solution was prepared by dissolving sodium (0.07 g,
3.06 mmol) in dry methanol (3 ml). This solution was rapidly added to a
suspension of a mixture of 4a and 4b7 (0.50 g, 1.23 mmol) in methanol (20 ml)
at room temperature. After refluxing for 5 h, the reaction mixture was cooled
down to room temperature. The yellow precipitate was isolated by filtration,
washed with methanol (5 ml), and dried to give the intermediate disodium salt
(0.54 g). The disodium salt was suspended in water (40 ml), and
a 40%
methanol solution of TBA hydroxide (2.38 g, 3.68 mmol) was added. After
stirring for 30 min at room temperature, the orange precipitate was filtered,
washed with water (10 ml), and dried to give 5 (0.91 g, 83%). This decomposes
above 210 °C without melting.
Figure 2. Changes in the absorption spectrum of 3 in methylene chloride upon
consecutive addition of DBU (up to 2 equiv). The 300–500 nm range is shown in the
inset.
1H NMR (DMSO-d6): d 7.80 (4H, s), 4.00 (4H, q, 3J = 7.1 Hz), 3.06–3.22 (16H, m),
1.44–1.64 (16H, m), 1.22–1.36 (16H, m), 1.17 (6H, t, 3J = 7.1 Hz), 0.91 (24H, t,
3J = 7.2 Hz).
10. Concentrated hydrochloric acid (0.12 ml of 37% HCl, 1.46 mmol) was added to
a solution of 5 (0.50 g, 0.56 mmol) in acetonitrile (30 ml) at room temperature.
The yellow precipitate of 7 was filtered, washed with acetonitrile (5 ml), and
dried at room temperature (0.22 g, 97%). A suspension of 7 (0.20 g, 0.49 mmol)
in anhydrous acetonitrile (50 ml) was heated under reflux until the yellow
suspension dissolves (about 30 min). Pure 3 (0.12 g, 92%) crystallized upon
cooling as colorless leaflets, which were collected by filtration and dried.
Compound 3 sublimes above 290 °C without decomposition. 1H NMR (CDCl3):
d 8.78 (4H, s), 3.46 (4H, s).
derivative 1 can be prepared from the corresponding ylidene deriv-
atives, which are readily available from pyromellitic anhydride7, in
75% overall yield.
Bromination of 3 afforded 2,2,7,7-tetrabromodicyclopenta[b,g]-
naphthalene-1,3,6,8(2H,7H)-tetraone 8, the structure of which has
been confirmed by the X-ray analysis11 (Fig. 1). This compound is a
strong brominating agent: even gentle heating of its acetone solu-
tions leads to the formation of bromoacetone as evidenced by the
1H NMR spectrum.
Derivative 3 in methylene chloride exhibits a number of weak
vibronically split bands around 360 nm and a strong sharp absorp-
tion band at about 290 nm (Fig. 2).
The dianion of 3 can be generated in solution by addition of
2 equiv of a base. It features a broad band around 430 nm in dichlo-
romethane (Fig. 2), showing thus a considerable blue shift com-
pared to absorption of the dianion of 1 (500 nm).1
Similar to compound 1, derivative 3 easily condenses with p-
dialkylaminobenzaldehydes in acetic acid upon reflux, affording
the corresponding conjugated donor–acceptor–donor derivatives
9 and 10.12 Both chromophores exhibit strong charge transfer
absorption bands at 535 and 540 nm (in toluene), respectively.
An interesting feature of two-photon absorption of 10 is the
presence of two equally strong absorption bands at 772 and
974 nm with the cross-section coefficient about 1000 GM. The
11. Bromine (0.47 ml, 9.17 mmol) was added to
a suspension of 3 (0.06 g,
0.23 mmol) in DMSO/H2O (1:1.4 ml). The reaction mixture was stirred at
room temperature for 2 h. The light orange precipitate was filtered off, washed
with water, and dried. The crude
8 (0.12 g, 91%) was crystallized from
methylene chloride to afford colorless prisms, which turned brown at 210 °C
and melted above 290 °C.1H NMR (THF-d8): d 9.13 (4H, s). 1H NMR (acetone-
d6): d 9.31 (4H, s). 13C NMR (THF-d8): d 187.12 (4 Â C), 141.40 (4 Â C), 134.62
(4 Â C), 130.39 (4 Â CH), 53.22 (2 Â CBr2).
Crystallographic data were collected on Bruker-Nonius KappaCCD
diffractometer with MoK
a radiation, k = 0.71073 Å, C16H4Br4O4. Unit cell
parameters: a 13.3498(3); b 12.3157(2); c 10.1692(2), space group Pbca. The
crystal structure has been deposited at the Cambridge Crystallographic Data
Centre and allocated the deposition number CCDC 698427.
12. Compound 9: a green solid, mp 260 °C (yield 71%). 1H NMR (CDCl3): d 8.55 (4H,
d, 3J = 9.0 Hz), 8.34–8.40 (2H, m), 7.84 (2H, s), 6.70 (4H, d, 3J = 9.0 Hz), 4.23 (4H,
q, 3J = 7.1 Hz), 4.16 (4H, s), 3.44–3.56 (4H, m), 1.12–1.42 (62H, m), 0.87 (6H, t,
3J = 7.1 Hz).
Compound 10: a green solid, mp 280 °C (yield 73%). 1H NMR (CDCl3): d 8.61
(4H, d, 3J = 8.9 Hz), 8.56–8.58 (4H, m), 7.89 (2H, s), 6.71 (4H, d, 3J = 8.9 Hz), 4.24
(4H, q, 3J = 7.1 Hz), 4.16 (4H, s), 3.46–3.56 (4H, m), 1.17–1.34 (62H, m), 0.87
(6H, t, 3J = 7.1 Hz).