Unusual transformation of the diarylmethanol derivative into an unknown 1,2,3,6,7,10-hexahydroxylated anthracene system

Article abstract of DOI:10.1021/jo052599x

10-Benzyloxy-1,2,3-trimethoxy-6,7-(methylene-1,3-dioxy)anthracene as a potential material for molecular electronics was synthesized from the O-benzyl-protected diarylmethanol derivative containing the 1,3-dioxyethylene acetal function via a one-pot proced

Full text of DOI:10.1021/jo052599x

SCHEME 1. Synthesis of O-Benzyl-Protected
Diarylmethanol 4 from 6-Bromopiperonal 1
Unusual Transformation of the Diarylmethanol
Derivative into an Unknown
1,2,3,6,7,10-Hexahydroxylated Anthracene System
Piotr Bałczewski,*,†,‡ Marek Koprowski,†
Agnieszka Bodzioch,† Bernard Marciniak,‡ and
Ewa Ro´z˘ycka-Sokołowska‡
Department of Heteroorganic Chemistry, Center of Molecular
and Macromolecular Studies, Polish Academy of Sciences,
90-363 -Lo´dz´, Sienkiewicza 112, Poland, and Institute of
Chemistry and EnVironmental Protection, Jan Długosz
UniVersity of Cze¸stochowa, 42-200 Cze¸stochowa,
Armii Krajowej 13/15, Poland
butyl groups [2-tert-butyl-9,10-diphenylanthracene, 2-tert-butyl-
9,10-di(4-tert-butylphenyl)anthracene],8-10 9,10-bis(3′,5′-diaryl)-
phenylanthracene (JBEM),11 rotaxane of methyl-exo-pyridinean-
thracene,12,13 2,3,6,7-tetramethyl-9,10-dinaphthylanthracene
(TMADN),14 2,6-bis(4-trifluoromethylphenyl)anthracene,15 and
2,6-dithienylanthracene,15 have been intensely investigated as
light-emitting materials in multilayer electroluminescence di-
odes.
pbalczew@bilbo.cbmm.lodz.pl
ReceiVed December 19, 2005
In investigations on materials for molecular electronics, we
needed diarylmethanols with the protected OH function and free
benzaldehyde group starting from 6-bromopiperonal 1. Because
an attempt to introduce the 3,4,5-trimethoxyphenyl group in a
one-pot procedure using the Kuroda et al. protocol16 gave a
complex mixture of unidentified compounds, a protection of
the aldehyde group in 1 with ethylene glycol to give 2 was
necessary (Scheme 1).
10-Benzyloxy-1,2,3-trimethoxy-6,7-(methylene-1,3-dioxy)anthracene
as a potential material for molecular electronics was syn-
thesized from the O-benzyl-protected diarylmethanol deriva-
tive containing the 1,3-dioxyethylene acetal function via a
one-pot procedure under acidic conditions (1 N HCl,
methanol, 60 h) in 60% yield. The replacement of methanol
for benzene resulted in hydrolysis of the acetal function in
96% yield.
Because of varying reports17-19 concerning the reaction time
(from 8 to 48 h for reactions of a similar scale), the protection
reaction was monitored with 1H NMR. In our hands, it required
26 h for completion to give 2 on a multigram scale and in almost
100% purity. The Br/Li exchange reaction in the latter with
n-BuLi/n-hexane in a THF solution to give 2-Li followed by
condensation with 3,4,5-trimethoxybenzaldehyde afforded the
(5) Liu, S. W.; Huang, C. A.; Lee, J. H.; Yang, K. H.; Chen, C. C.;
Chang, Y. Thin Solid Films 2004, 312-313, 453-454.
(6) Shi, J.; Tang, C. W. Appl. Phys. Lett. 2002, 80, 3201-3203.
(7) Liu, T. H.; Shen, W. J.; Balaganesan, B.; Yen, C. K.; Iou, C. Y.;
Chen, H. H.; Chen, C. H. Synth. Met. 2003, 137, 1033.
(8) Chen, C. H.; Tang, C. W. Appl. Phys. Lett. 2001, 79, 3711-3713.
(9) Kim, Y. H.; Shin, D. C.; Kim, S. H.; Ko, C. H.; Yu, H. S.; Chea, Y.
S.; Kwon, S. K. AdV. Mater. 2001, 13, 1690-1693.
(10) Balaganesan, B.; Shen, W.-J.; Chen, C. H. Tetrahedron Lett. 2003,
44, 5747-5750.
Increasing interest in ultrapure and structurally perfect crystals
and thin layers of π-conjugated molecular semiconductors, such
as polycyclic aromatic hydrocarbons (anthracene, tetracene, and
pentacene), is connected with their potential application as active
elements in new generations of relatively cheap optoelectronic
devices, e.g., the field-effect transistors and light-emitting
diodes.1-4 Physical properties of these compounds, unlike
traditional inorganic semiconducting materials requiring multiple
processing steps, may be simply tailored through chemical
modification. Some anthracene derivatives prepared as thin
layers, such as 9,10-di-(2-naphthyl)anthracene (ADN),5-7 9,-
10-diphenylanthracene (DPA) and its derivatives containing tert-
(11) Jiang, X.-Y.; Zhang, Z.-L.; Zheng, X.-Y.; Wu, Y.-Z.; Xu, S.-H. Thin
Solid Films 2001, 401, 251-254.
(12) Giro, G.; Cocchi, M.; Fattori, V.; Gadret, G.; Ruani, G.; Cavallini,
M.; Biscarini, F.; Zamboni, R.; Loontjens, T.; Thies, J.; Leigh, D. A.;
Morales, A. F.; Mahrt, R. F. Synth. Met. 2001, 122, 63-65.
(13) Gadret, G.; Ruani, G.; Cavallini, M.; Biscarini, F.; Murgia, M.;
Zamboni, R.; Giro, G.; Cocchi, M.; Fattori, V.; Loontjens, T.; Thies, J.;
Leigh, D. A.; Morales, A. F.; Mahrt, R. F. Appl. Surf. Sci. 2001, 175-176,
369-373.
(14) Kan, Y.; Wang, L.; Gao, Y.; Duan, L.; Wu, G.; Qin, Y. Synth. Met.
2004, 141, 245-249.
(15) Ando, S.; N, J.-I.; Fujiwara, E.; Tada, H.; Inoue, Y.; Tokito, S.;
Yamashita, Y. Chem. Mater. 2005, 17, 1261-1264.
(16) Kuroda, T.; Takahashi, M.; Kondo, K.; Iwasaki, T. J. Org. Chem.
1995, 60, 9560.
* To whom correspondence should be addressed. Phone: +48 42 6803202.
Fax: +48 42 6847 126.
† Polish Academy of Sciences.
‡ Jan Długosz University of Cze¸stochowa.
(1) Karl, N. Introduction. In Organic Electronic Materials; Farchioni,
R., Grosso, G., Eds.; Springer-Verlag: Berlin Heidelberg, 2001; Chapter
6, pp 215-239.
(2) Belaid, R.; Barhoumi, T.; Hachani, L.; Hassine, L.; Bouchriha, B.;
Synth. Met. 2002, 131, 23-30.
(17) Bogucki, D. E.; Charlton, J. L. J. Org. Chem. 1995, 60, 588-593.
(18) Arnold, B. J.; Mellows, S. M.; Sammes, P. G. J. Chem. Soc. Perkin
Trans. 1, 1973, 1266-1270.
(19) Geen, G. R.; Mann, I. S.; Mullane, V.; McKillop, A. Tetrahedron
1988, 54, 9875-9894.
(3) Gundlach, D. J.; Nichols, J. A.; Zhou, L.; Jackson, T. N. Appl. Phys.
Lett. 2002, 80, 2925-2927.
(4) Herwig, P. T.; Mu¨llen, K. AdV. Mater. 1999, 11, 480-483.
10.1021/jo052599x CCC: $33.50 © 2006 American Chemical Society
Published on Web 03/04/2006
J. Org. Chem. 2006, 71, 2899-2902
2899

SCHEME 2. Differentiated Reactivity of 4 toward 1 N HCl
diarylmethanol 3 in 75-97% yield. Synthesis of 3 via the
corresponding Grignard reagent 2-MgBr in THF18 and via
2-Li in ether/THF20,21 solutions was also described. Protection
of the OH group with benzyl bromide in the presence of KI
(5%) afforded 4 in 71% yield. Selective hydrolysis of the acetal
function in the latter was carried out in benzene with 1 N HCl
at 80 °C within 18 h to give the required diarylmethanol
derivative 5 with the free aldehyde group in 96% yield (Scheme
2).
FIGURE 1. Perspective view of 6, showing the atomic numbering
scheme. Displacement ellipsoids are drawn at the 30% probability level,
and H atoms are shown as small spheres of arbitrary radii.
However, when the hydrolysis was carried out with 1 N HCl
in MeOH (room temperature, 18 h), 10-benzyloxy-1,2,3-
trimethoxy-6,7-(methylene-1,3-dioxy)anthracene 6 as a well-
crystallizing solid was unexpectedly formed in nonoptimized
38% yield accompanied by the substrate 4 (33% yield) (Scheme
2). Prolongation of the reaction time to 60 h gave 6 in 60%
yield. When MeOH was replaced by i-PrOH, only 4 was present
in the reaction mixture under the same reaction conditions (60
h, room temperature, 1 N HCl). In acetone (60 h, room
temperature, 1 N HCl), the anthracene 6, the aldehyde 5, and
unidentified impurities were formed in a ratio of 3.7:1:1.5 (6:
59% yield). The result in THF (60 h, room temperature, 1 N
HCl) was similar to that obtained in refluxing benzene (Scheme
2): 6/5/4 ) 1:8.4:3 (5: 67% yield; 6: 8% yield). Shortening
of the reaction time to 1 h was possible in refluxing MeOH (6:
50% yield; no 4 and 5) or i-PrOH (6: 44% yield; no 4 and 5).
The compound 6 is the first representative of the 1,2,3,6,7,-
10-hexahydroxylated anthracene system protected with three
different protecting groups. Formation of 10-hydroxy-1,2,3-
trimethoxy-6,7-(methylene-1,3-dioxy)anthracene, based on the
mass molecular peak only, was postulated by Galletti et al. as
a possible byproduct in the 800 °C pyrolysis reaction leading
to an isobenzofuran derivative.22
The plausible explanation of this interesting transformation
includes a primary formation of benzyl carbocation 7 and its
intramolecular Friedel-Crafts-type cyclization to give σ-com-
plex 8. In the next step, a new benzyl carbocation 10 formed
after removal of the glycol molecule from 9 undergoes aroma-
tization to the new anthracene system 6 which was separated
as a well-crystallizing solid (Scheme 3). The loss of a proton
from 8 can be alternatively effected via 1,4-elimination of
ethylene glycol; however, this mechanistic proposal requires a
protonation of the glycol moiety oxygen and formation of the
doubly charged intermediate.
SCHEME 3. Mechanistic Proposal for the Formation of the
Anthracene 6 from 4
The anthracene 6 crystallizes in the triclinic P1h space group
with two molecules per unit cell. The anthracene and dioxolane
rings as a whole are essentially planar with the largest deviations
from the best least-squares plane of 0.028(2) Å for atom C5
(Figure 1). Methoxy atoms O4, O5, O6, and C23 and also
benzyloxy atom O3 are nearly coplanar. The dihedral angle
between the phenyl ring plane and the plane formed by
anthracene and dioxolane rings is 51.8(1)°. There are two
intramolecular contacts of type C-H‚‚‚O involving (1) atoms
C5-H5 and O6 (C5-H5 ) 0.93, H5‚‚‚O6 ) 2.50, and C5‚‚‚
O6 ) 2.822(2) Å and C5-H5‚‚‚O6 ) 100.4°) and (2) atoms
C25-H25A and O5 (C25-H25A ) 0.96, H25A‚‚‚O5 ) 2.49,
and C25‚‚‚O5 ) 3.066(3) Å and C25-H25A‚‚‚O5 ) 118.8°).
The crystal packing of 6 is stabilized by a C-H‚‚‚O intermo-
lecular hydrogen bond, with C16-H16A ) 0.97, H16A‚‚‚O5(i)
) 2.49, and C16‚‚‚O5(i) ) 3.238(3) Å and C16-H16A‚‚‚O5(i)
) 134.2° (symmetry code: (i) -x, -y, 1 - z) (Figure 2). This
intermolecular hydrogen bond forms the R2 (18) graph-set23
2
dimer. The dimeric units are connected via the intermolecular
C-H‚‚‚π hydrogen bond between C23 and H23A atoms of the
molecule at (x, y, z) and a benzene ring formed by atoms C4-
C6/C11-C13 (Cg3) of the molecule at (1 - x, -y, 1 - z); the
(20) Patil, P. A.; Joshi, R. R.; Narasimhan, N. S. Indian J. Chem., Sect.
B 1987, 1025-1029.
(21) Gokhale, S. M.; Joshi, R. R.; Narasimhan, N. S. Indian J. Chem.,
Sect. B 1987, 1030-1034.
(22) Galletti, C. G.; Ward, R. S.; Pelter, A.; Goubet, D. J. Anal. Appl.
Pyrolysis 1992, 24, 139-146.
(23) Bernstein, J.; Davis, R. E.; Shimoni, L.; Chang, N.-L. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 1555-1575.
2900 J. Org. Chem., Vol. 71, No. 7, 2006

2
FIGURE 2. Part of the crystal structure of 6, showing the intermolecular hydrogen bond C-H‚‚‚O (double dashed line) forming the R2 (18)
graph-set dimer, the intramolecular C-H‚‚‚O contacts (bold line), and the intermolecular C-H‚‚‚π interactions (dashed line). The Cg3 and Cg5
centroids of C4-C6/C11-C13 and C17-C22 benzene rings, respectively, are denoted by crosslets. H atoms, except for atoms H5, H16A, H23A,
and H25A have been omitted for clarity.
THF (5 mL) was added a solution of 3 (1.38 g, 3.54 mmol) in
THF (10 mL) at room temperature. The resulting mixture was stirred
for 30 min. Then benzyl bromide (1.82 g, 10.62 mmol) in THF (2
mL) was added, and stirring was continued for 18 h at the same
temperature. After evaporation of the solvent, the residue was
diluted with ethyl acetate (100 mL) and washed with water (2 ×
20 mL). The organic layer was dried (MgSO4) and then filtered,
and the solvent was removed to leave a pale yellow oil which was
purified by column chromatography (petroleum ether/EtOAc in a
gradient as an eluent) (yield 71% (1.27 g)). 4: Rf ) 0.45 (n-hexane/
H23A‚‚‚Cg3 and C23‚‚‚Cg3 distances are 2.87 and 3.770(3)
Å, respectively, and the C-H‚‚‚Cg angle is 156°.
As a concluding remark, the first isolated representative of
the unknown 1,2,3,6,7,10-hexahydroxylated anthracene system
was synthesized in a one-pot unexpected transformation from
the diarylmethanol derivative. This compound is a potential
material for molecular electronics.
Experimental Section
1
ethyl acetate 1:1 v/v); H NMR (C6D6, 200 MHz) δ 3.23-3.58
Crystallographic Data of 6: C25H22O6, M ) 418.43, triclinic,
P1h, a ) 7.985(2) Å, b ) 11.404(2) Å, c ) 12.996(3) Å, R )
113.74(3)°, â ) 92.24(3)°, γ ) 104.11(3)°, V ) 1038.0(5) Å, Z )
2 molecules per unit cell, Dc ) 1.339 g/cm3, F(000) ) 440, crystal
size of 0.40 × 0.30 × 0.28 mm. Diffraction data were collected at
293(2) K, using a diffractometer with graphite-monochromated Cu
KR radiation (λ ) 1.54178 Å) and a ω/2θ scan mode to θ ) 67.90°.
The structure was solved by direct methods and refined by full-
matrix least-squares on F 2 with SHELXL-97.24 Carbon and oxygen
atoms were refined anisotropically, and hydrogen atoms were
introduced at calculated positions as riding atoms, with C-H
distances in the range 0.93-0.97 Å. The three free variables for
Uiso(H) were refined according to SHELXL97:24 R1 ) 0.055, wR2
) 0.149, S ) 1.057 for 3161 with I > 2σ(I) unique reflections and
287 parameters. Further details on the crystal structure investigation
have been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication number CCDC 289080.
5-[Benzyloxy(3,4,5-trimethoxyphenyl)-methyl]-6-[1,3]dioxolan-
2-yl-benzo[1,3]dioxole 4. To a suspension of NaH (0.155 g, 3.89
mmol, 60% in mineral oil) and KI (0.181 mmol, 30 mg) in dry
2
(m, 4H), 3.39 (s, 6H), 3.81 (s, 3H,), 4.52 (dAB, JHH ) 12.1 Hz,
1H), 4.62 (dAB, 2JHH ) 12.1 Hz, 1H), 5.17-5.24 (m, 2H), 5.97 (s,
1H), 6.07 (s, 1H), 6.97 (s, 2H), 7.02-7.37 (m, 5H), 7.29 (s, 1H),
7.36 (s, 1H); 13C NMR (CD2Cl2, 50 MHz) δ 56.2, 60.6, 65.37,
65.42, 70.8, 77.3, 101.1, 101.7, 104.2, 106.5, 107.4, 127.8, 128.1,
128.6, 128.8, 129.7; 135.3; 137.8; 138.8 147.4; 148.8; 153.5. MS
(EI, 70 eV) - m/z(%): 389 (M(-PhCH2), 40); 372 (M(-PhCH2-
OH), 56), 344 (M(-PhCH2OH, -CH2CH2), 75), 327 (M(-PhCH2-
OH, -CH2CH2OH), 35), 313 (M(-C6H2(OCH3)3), 19), 221 (M(-
C6H2(OCH3)3, -PhCH3), 47), 177 (M(-C6H2(OCH3)3, -PhCH3,
-CH2CH2OH), 100); MS (CI, isobutane) - m/z (%) 481 (M + 1,
6), 420 (M + 1(-OCH2CH2OH), 9), 374 (M + 1(-PhCH2O), 100),
314 (M + 1(-PhCH2O, -OCH2CH2O), 3); HR MS (EI, 70 eV)
-480 (M, 24); calcd for C27H28O8 480.17842, found 480.17872.
6-[Benzyloxy-(3,4,5-trimethoxyphenyl)-methyl]-benzo[1,3]-
dioxole-5-carbaldehyde 5. The compound 4 (0.617 g, 1.285 mmol)
was dissolved in benzene (35 mL), and then an aqueous solution
of 1 N HCl (15 mL) was added. The mixture was vigorously stirred
in a Schlenk tube at 80 °C in an inert atmosphere (argon) for 18 h.
After addition of additional an amount of benzene (50 mL), the
solution was washed with water (3 × 10 mL). The organic layer
was dried, and the benzene was removed in vacuo. Column
(24) Sheldrick, G. M. SHELXL97; University of Go¨ttingen: Germany,
1997.
J. Org. Chem, Vol. 71, No. 7, 2006 2901

chromatography (n-hexane/ethyl acetate) of the residue gave 0.54
g (96%) of the aldehyde 5 as a pale yellow oil. 5: Rf ) 0.55
(hexane/ethyl acetate 2:1 v/v), Rf ) 0.75 (petroleum ether/ethyl
mL), and the organic layer was washed with water (5 mL), NaHCO3
aq (5 mL), and again with water (5 mL) and then dried over
anhydrous MgSO4. After filtration, the solvents were removed in
vacuo to give a pale orange solid. The crude product was purified
with column chromatography (n-hexane/ethyl acetate or petroleum
ether/acetone) to give 26 mg of pure anthracene 6 (yield 60%). 6:
Rf ) 0.55 (petroleum ether/ethyl acetate 3:1 v/v); Rf ) 0.85
1
acetate 1:1 v/v in a gradient as an eluent); H NMR (C6D6, 200
MHz) δ 3.38 (s, 6H), 3.79 (s, 3H), 4.46-4.47 (m, 2H), 5.14-5.18
(m, 2H), 6.44 (s, 1H), 6.83 (s, 2H), 7.04-7.38 (m, 5H), 7.19 (s,
1
1H), 7.35 (s, 1H), 10.08 (s,1H); H NMR (CDCl3, 200 MHz) δ
2
1
3.81 (s, 6H), 3.83 (s, 3H), 4.53 (dAB, JHH ) 11.7 Hz, 1H), 4.60
(petroleum ether/ethyl acetate 1:1 v/v); mp ) 146-148 °C; H
(dAB, 2JHH ) 11.7 Hz, 1H), 6.05-6.06 (m, 2H), 6.22 (s, 1H), 6.62
(s, 2H), 7.10 (s, 1H), 7.26-7.35 (m, 6H), 10.11 (s, 1H); 13C NMR
(C6D6, 50 MHz) δ 56.5, 61.1, 71.9, 78.6, 102.7, 105.7, 109.0, 111.2,
129.0, 129.4, 129.7, 138.0, 139.3, 139.6, 142.6, 148.6, 153.3, 155.0,
190.2; 13C NMR (CD2Cl2, 50 MHz) δ 56.2, 60.6, 71.3, 78.0, 102.7,
104.5, 108.4, 109.6, 128.0, 128.1, 128.7, 128.8, 137.2, 138.3, 141.5,
147.9, 152.8, 153.7; the signal due to the C-CHO is covered by
signals of the OCH2C6H5 group both in CD2Cl2 and C6D6; MS (CI,
isobutane) m/z(%) 437 (M+1, 1), 419 (M + 1(-H2O), 5), 345
(M(-PhCH2), 30), 329 (M(-PhCH2OH), 100); MS (CI, isobutane)
m/z(%) 437 (M + 1, 1), 419 (M + 1(-H2O), 5), 345 (M(-PhCH2),
30), 329 (M(-PhCH2OH), 100); HR MS (CI, isobutane) 437 (M
+ 1, 1), 436 (M, 1); calcd for C25H25O7 (M + H) 437.16002, found
437.15840.
NMR (C6D6, 200 MHz) δ 3.40 (s, 3H), 3.86 (s, 3H), 3.96 (s, 3H),
4.98 (s, 2H), 5.26 (s, 2H), 7.06-7.45 (m, 5H), 7.32 (s, 1H), 7.77
(s, 1H), 8.51 (s, 1H); 1H NMR (CD3CN, 200 MHz) δ 3.86 (s, 3H),
3.90 (s, 3H), 4.04 (s, 3H), 5.10 (s, 2H), 6.04 (s, 2H), 7.17 (s, 1H),
7.26 (s, 1H), 7.36-7.64 (m, 5H), 8.17 (s, 1H); 13C NMR (CDCl3,
50 MHz) δ 55.7, 61.2, 61.4, 76.4, 95.4, 97.0, 101.0, 103.3, 115.0,
121.7, 122.4, 124.0, 127.9, 128.2, 128.7, 128.9, 137.6, 140.3, 147.2,
147.4, 148.0, 148.9, 152.5; MS (CI, isobutane) - m/z (%) 419 (M
+ 1, 100), 327 (M(-PhCH2), 79); HR MS (CI, isobutane) 419 (M
+ 1, 100); calcd for C25H23O6 (M + H) 419.14946, found
419.14919.
Supporting Information Available: Characterization data for
compounds 2 and 3, 1H/13C NMR spectra of compounds 2-6,
crystallographic data of 6 (CIF), and full crystallographic discussion
on 6. This material is available free of charge via the Internet at
http://pubs.acs.org.
10-Benzyloxy-1,2,3-trimethoxy-6,7-(methylene-1,3-dioxy)an-
thracene 6. The compound 4 (0.05 g, 0.104 mmol) was dissolved
in MeOH (5 mL), and then an aqueous solution of 1 N HCl (1
mL) was added. The mixture was stirred at ambient temperature
for 60 h. The reaction mixture was extracted with ethyl acetate (20
JO052599X
2902 J. Org. Chem., Vol. 71, No. 7, 2006