Effect of substituents at 1,4-positions of polycyclic aromatic compounds and preparation of 2,3-difunctionalized pentacenes and naphthacenes

Article abstract of DOI:10.3987/COM-07-S(U)28

Effects of substituents at 1,4-positions of polycyclic aromatic compounds were investigated in the case of reduction of 2,3-bis(alkoxycarbonyl)arenes with the LiAlH₄/AlCI₃ system. 2,3-Bis(alkoxycarbonyl)dihydronaphthacenes and dihydropentacenes 1 were treated with a mixture of LiAlH₄ and AlCl₃. The products were dependent on the substituents at 1,4-positions. Similar type of influence of the substituents at 1,4-positions was observed in the oxidation of diols 2 to dialdehydes 4. Without substituents at 1,4-positions, dialdehydes 4 were conveniently obtained. However, with substituents at 1,4-positions, dialdehydes 4 were not obtained. Instead,1,3-dihydroisobenzofuran-l,3-diol or 1,3-dihydroisobenzofuran-l-ol derivatives 5, 6 were obtained in good yields. Preparation of pentacene imides and pentacene carboxylic acid anhydride was also reported.

Full text of DOI:10.3987/COM-07-S(U)28

HETEROCYCLES, Vol. 73, 2007
519
HETEROCYCLES, Vol. 73, 2007, pp. 519 - 536. © The Japan Institute of Heterocyclic Chemistry
Received, 27th June, 2007, Accepted, 13th September, 2007, Published online, 14th September, 2007. COM-07-S(U)28
EFFECT OF SUBSTITUENTS AT 1,4-POSITIONS OF POLYCYCLIC
AROMATIC
COMPOUNDS
AND
PREPARATION
OF
2,3-DIFUNCTIONALIZED PENTACENES AND NAPHTHACENES
Shi Li, Lishan Zhou, Zhiyi Song, Fengyu Bao, Ken-ichiro Kanno, and
Tamotsu Takahashi*
Catalysis Research Center, Hokkaido University and SORST, Japan Science and
Technology Agency (JST), Kita-ku, Sapporo 001-0021, Japan
Abstract – Effects of substituents at 1,4-positions of polycyclic aromatic
compounds
were
investigated
in
with
the
the
case
of
reduction
of
2,3-bis(alkoxycarbonyl)arenes
LiAlH4/AlCl3
system.
2,3-Bis(alkoxycarbonyl)dihydronaphthacenes and dihydropentacenes 1 were
treated with a mixture of LiAlH4 and AlCl3. The products were dependent on
the substituents at 1,4-positions. Similar type of influence of the substituents at
1,4-positions was observed in the oxidation of diols 2 to dialdehydes 4. Without
substituents at 1,4-positions, dialdehydes 4 were conveniently obtained.
However, with substituents at 1,4-positions, dialdehydes 4 were not obtained.
Instead, 1,3-dihydroisobenzofuran-1,3-diol or 1,3-dihydroisobenzofuran-1-ol
derivatives 5, 6 were obtained in good yields. Preparation of pentacene imides
and pentacene carboxylic acid anhydride was also reported.
INTRODUCTION
In 1997, Jackson et al. reported that pentacene showed the comparable or higher mobility compared with
amorphous silicon as organic semiconductor.1 Since pentacene is not soluble in organic solvent, we
proposed and reported substituted soluble pentacene derivatives (Scheme 1)2 for wet process fabrication
of organic semiconductors.
After our report, several groups reported the formation of substituted pentacenes.3-7 Although various
substituted pentacenes have been reported, functionalized pentacenes are still limited. So far alkyl,
alkenyl, aryl, alkynyl, silyl, halogeno, cyano, alkoxy, aryloxy, thienyl, alkoxy carbonyl groups have been
reported.

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HETEROCYCLES, Vol. 73, 2007
Scheme 1. Homologation Method for the Formation of Soluble and Substituted Pentacene Derivatives
R
R
R
R
R
R
R
R
CO2Me
CO2Me
R
R
R
R
R
R
Cp2ZrBu2
i) LAH
Li
R
Br
Br
R
R
ZrCp2
ii) PBr3
R
R
R
R
R
R
R
R
R
R
R
R
R
R
CO2Me
CO2Me
R
R
CO2Me
CO2Me
R
R
DMAD
CuCl
DDQ
i) LAH
Li
R
Br
Br
ii) PBr3
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
CO2Me
CO2Me
R
CO2Me
CO2Me
i) Cp2ZrBu2
DDQ
R
R
ii) CuCl, DMAD
R
R
R
R
During the course of our study on functionalized polycyclic aromatic compound formation such as
2,3-difunctionalized pentacenes and naphthacenes, we found the effects of substituents at 1,4-positions of
polycyclic aromatic compounds. In this paper, we would like to report the effects of the substituents at
1,4-positions and the formation of 2,3-difunctionalized pentacene and naphthacene derivatives derived
from 2,3-bis(methoxycarbonyl)pentacenes and naphthacenes as shown in Scheme 2.
Scheme 2. Formation of 2,3-Difunctionalized Acene Derivatives
R
R
R
OH
O
CO2H
CO2H
OH
R
R
R
R
R
O
O
O
CO2Me
CO2Me
OH
OH
R
R
R
R
O
O
NR
O
R
R
RESULTS AND DISCUSSION
EFFECTS OF SUBSTITUENTS AT 1,4-POSITIONS IN THE REDUCTION OF 2,3-DIESTER
GROUPS OF POLYCYCLIC COMPOUNDS WITH ALUMINUM HYDRIDES AND
ALUMINUM TRICHLORIDE

HETEROCYCLES, Vol. 73, 2007
521
The results of reduction of two ester groups of 1,4-bis(trimethylsilyl)-2,3- bis(methoxycarbonyl)-
5,12-dihydronaphthacene (1a) with a series of aluminum hydrides were shown in Table 1. To obtain the
desired diol 2a in high yield, a suitable choice of an aluminum hydride and a solvent was critical. The
reaction of diester 1a with DIBAL-H was disappointing to afford the desired diol 2a only in low yield
(entry 1), although diester 1a was consumed completely. With LiAlH4 in THF, the yield was improved
but still not satisfactory (entry 2). It was worth noting that just changing the solvent from THF to ether
dramatically improved the yield (entry 3). When diester 1a was mixed with LiAlH4 in THF, the color of
the mixture turned to dark red and was kept during the reaction. The color change would indicate
electron transfer reaction, which caused undesired side reaction. In contrast, the reaction in ether
showed no color change.
Scheme 3
3 LiAlH4
LiAlH4
LiAlH4
AlCl3
AlCl3
3 LiCl
LiCl
4 AlH3
2 AlH2Cl
3 AlHCl2
3 AlCl3
LiCl
Table 1. Reduction of Diester 1a with Aluminum Hydrides
TMS
TMS
TMS
TMS
CO2Me
CO2Me
aluminum hydride
solvent, rt, 3 h
OH
OH
O
TMS
TMS
1a
2a
Solvent
3a
Yieldsa of 2a (%)
Yieldsa of 3a (%)
Entry
Reagents
Amount (eq.)
DIBAL-Hb,c
1
2
3
4
5
6
7
6
3
3
toluene
THF
6
67
100
26
16
6
-
c
-
LiAlH4
LiAlH4
Et2O
Et2O
Et2O
Et2O
Et2O
-
LiAlH4: AlCl3 (AlH3)
LiAlH4: AlCl3 (AlH2Cl)
LiAlH4: AlCl3 (AlHCl2)
LiAlH4: AlCl3
3:1
3:3
74
84
94
93
3:9
3:12
7
a NMR yields. b This reaction was carried out at -78 °C. c No starting material remained.
Surprisingly, the cyclic ether derivative 3a was obtained as a major product when AlCl3 was combined
with LiAlH4 in the reduction system (entries 4-7). The combination of LiAlH4 and AlCl3 in different

522
HETEROCYCLES, Vol. 73, 2007
ratios could provide different types of aluminum hydrides as shown in Scheme 3 as reported in the
literature.8 Thus the reducing ability of the resulting aluminum hydrides could be tuned. The yield of
cyclic ether derivative 3a increased with increase of the ratio of AlCl3 to LiAlH4, and the best yield for 3a
was obtained when the ratio of LiAlH4: AlCl3 was 3:9 (entry 6). Further increasing of the ratio of AlCl3
did not improve the yield of 3a (entry 7).
Table 2. Substituent Effects in the Reduction of Diester 1 with LiAlH4 and AlCl3
R
R
R
CO2Me
CO2Me
LAH (3 eq.), AlCl3 (9 eq.)
Et2O, rt, 3 h
OH
OH
O
R
R
R
Substrate 1
Entry
Diol 2
Cyclic Ether 3
Yieldsa of 2 (%)
Yieldsa of 3 (%)
Substrate 1
TMS
CO2Me
1
2
3
6
94
-
CO2Me
TMS
a
CO2Me
97b
65
CO2Me
b
Ph
Ph
Ph
CO2Me
35
CO2Me
Ph
c
Pr
Pr
Pr
CO2Me
CO2Me
4
5
6
45
41
-
55
59
Pr
d
Bu
Bu
Bu
Bu
CO2Me
CO2Me
e
t-Bu
CO2Me
CO2Me
85c
t-Bu
f
a NMR yields. b Isolated yield.
c Refluxing in Et2O for 2 days. Starting material was recovered in 15%.

HETEROCYCLES, Vol. 73, 2007
523
The tendency for the formation of the cyclic ethers was strongly affected by steric bulkiness of the
ortho-substituents at 1,4-positions. Table 2 summarizes the results of the reduction of a series of
aromatic diester compounds with the LiAlH4-AlCl3 (3:9) mixed reagent.
When
3,4,5,6-tetraphenylphthalate dimethyl ester 1c was reduced with LiAlH4-AlCl3, a mixture of the
corresponding diol 2c and cyclic ether 3c was obtained in the ratio of 65:35, respectively (entry 3).
Similarly, the reductions of n-propyl- or n-butyl-substituted substrates 1d and 1e also afforded mixtures
of the corresponding diols and cyclic ethers in comparable ratios (entries 4 and 5). When
di-t-butyl-substituted substrate 1f was used for the reduction, cyclic ether 3f was formed as a single
product. No corresponding diol 2f was formed. At room temperature, the yield of 3f was 12% and
starting material 1f recovered in 88%. Even after refluxing the reaction mixture in diethyl ether for 2
days, the starting material 1f still remained in 15% and cyclic ether 3f was formed in 85% as a single
product (entry 6). On the other hand, the reduction of diester 1b without substituents at 1,4-positions
afforded only the corresponding diol 2b in quantitative yield (entry 2). No cyclic ether 3b was formed
in this case. Probably, increasing of the steric bulkiness of the ortho-substituents would induce close
proximity of the two aluminoxy moieties of the intermediate, which could cause the formation of the
corresponding cyclic ether 2.
EFFECTS OF SUBSTITUENTS AT 1,4-POSITIONS IN THE OXIDATION OF
2,3-BIS(HYDROXYMETHYL)AROMATIC COMPOUNDS
Oxidation of 2,3-bis(hydroxymethyl)acene derivatives was also strongly affected by sterical bulkiness of
ortho-substituents at 1,4-positions. The results of Swern oxidation of a series of aromatic diol
compounds are summarized in Table 3.9 When diols 2g-i having no ortho-substituents were oxidized
with oxalyl chloride-DMSO-Et3N, the corresponding dialdehydes 4g-i were obtained cleanly in 71, 90,
and 30%, respectively (entries 1-3). However, n-propyl-substituted substrate 2j was used for the
oxidation, 1,3-dihydro-isobenzofuran-1,3-diol derivative 5j was formed in 55% yield (entry 4). Other
two cases 2a,k having ortho-trimethylsilyl- or n-propyl groups also could not give corresponding
dialdehydes. Their crude NMR spectra suggested that 5a and 5k have isobenzofuran-1,3-diol structures,
but full characterization of them was failed due to their instability and impurity. Although careful
work-up and purification was preformed, all such attempts gave contaminated products. Oxidation of
n-butyl-substituted substrate 2l afforded 1,3-dihydro-isobenzofuran-1-ol derivative 6l in 62% (entry 7).
The corresponding dialdehyde was not formed in this case.
The existence of the ortho-substituents would interfere with the coplanar conformation between the
aromatic ring and the carbonyl moieties, and it would increase the reactivity of these carbonyl groups due
to interception of the π-conjugation with the aromatic ring. Thus destabilized carbonyl groups could

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HETEROCYCLES, Vol. 73, 2007
facilitate the cyclization with water or the neighboring hydroxy group to produce the corresponding
isobenzofuranols 5 or 6.
Table 3. Substituent Effects in the Oxidation of 2,3-Bis(hydroxymethyl)acenes 2
R
oxalyl chloride
OH
OH
Product 4, 5, 6
DMSO, Et3N
R
(Swern oxidation)
Substrate 2
Yieldsa (%)
71
Entry
1b
Substrate 2
Product
CHO
OH
OH
CHO
g
4g
Pr
Pr
Pr
Pr
CHO
CHO
OH
OH
2
3
90
30
h
i
4h
CHO
CHO
OH
OH
4i
Pr
Pr
OH
Pr
Pr
Pr
Pr
OH
OH
4
O
55
OH
Pr
Pr
j
5j
TMS
TMS
OH
O
OH
OH
5c
-
-
OH
TMS
TMS
Pr
a
5a
Pr
Pr
Pr
OH
O
Pr
Pr
Pr
Pr
6c
OH
OH
OH
Pr
Pr
Pr
Pr
k
5k
Et
Et
Bu
Bu
Bu
Bu
Bu
OH
O
Et
Et
Et
Et
OH
OH
62
7
Bu
Bu
Bu
Et
Et
l
6l
a Isolated yields. b See Ref. 9. c See Experimental Section.
FORMATION OF NAPHTHACENE- AND PENTACENE DICARBOXYLIC ANHYDRIDES
AND IMIDES
Preparation of naphthacene- and pentacene dicarboxylic anhydrides 8a,l from the corresponding

HETEROCYCLES, Vol. 73, 2007
525
2,3-diester polycyclic compounds 1a,l was shown in Scheme 4. Diesters 1a,l reacted with lithium
iodide in refluxing pyridine to afford the corresponding dicarboxylic anhydrides 7a,l.10 These
compounds were aromatized with DDQ at 100 °C in degassed toluene to afford the corresponding
naphthacene- and pentacene anhydrides 8a,l in 25 and 60% yields, respectively.
The formation of pentacene imides was shown in Scheme 5. The dicarboxylic anhydride 7l was treated
with primary amines to give the corresponding imides 9lo,lp in good yields.11 Aromatization of 9lo,lp
with DDQ at 100 °C in degassed toluene afforded the corresponding pentacene imides 10lo,lp in 76 and
68% yields, respectively.
Unexpectedly, solubility of these pentacene imides was relatively lower than that of pentacene diesters,
although these were highly alkylated. Probably, this is due to the planarity of the imide moieties in these
pentacenes. Such structural changing would cause strong π-π interaction between the pentacene
molecules.
When 1,4-nonsubstituted tetrahydropentacene 1m reacted with lithium iodide in refluxing pyridine, the
two-ester groups were converted to carboxylic ones to afford diacid 11m in 96% yield. It is different
from the reaction of 1,4-dibutyldihydropentacene 1l to produce the corresponding dicarboxylic anhydride
Scheme 4. Formation of Naphthacene- and Pentacene Dicarboxylic Anhydride
TMS
TMS
TMS
TMS
TMS
TMS
O
O
CO2Me
CO2Me
iii)
i), ii)
O
O
(25%)
(31%)
O
O
1a
7a
8a
Et
Et
Bu
Bu
Et
Et
Bu
Bu
Bu
Et
Et
Bu
Bu
Bu
O
O
Et
Et
Et
Et
CO2Me
Et
Et
i), ii)
iii)
O
O
CO2Me
(80%)
(60%)
O
O
Bu
Bu
Bu
Bu
1l
7l
8l
i) 15 eq LiI, reflux, pyridine, 2 h. ii) 3 N HCl iii)1 eq. DDQ, 100 °C, 3 h
Scheme 5. Formation of Pentacene Imides
Et
Et
Bu
Bu
Bu
Bu
Et
Bu
Bu
Et
Et
Bu
Bu
Bu
O
O
O
N R
Et
Et
Et
Et
Et
Et
i)
ii)
O
N R
O
O
O
Et
Bu
Bu
Bu
9lo (R = n-hexyl, 96%)
9lp (R = 2-ethylhexyl, 92%)
10lo (R = n-hexyl, 76%)
10lp (R = 2-ethylhexyl, 68%)
7l
i) R NH2 toluene, reflux, 6 h ii) 1 eq. DDQ, toluene, 100 °C, 3 h

526
HETEROCYCLES, Vol. 73, 2007
7l (Scheme 4). Probably it is also due to the steric effect of ortho-substituents same as the cyclic ether
formation as mentioned before. The carboxylic acid 11m was heated at 140 °C in acetic anhydride to
give the corresponding dicarboxylic anhydride 7m in 98% yield.
Anhydride 7m was treated with primary amines to give imides 9mp-r. Thus formed 9mp-r were
aromatized with DDQ at 100 °C in degassed toluene. In this way, three kinds of pentacene imides
10mp-r were synthesized in high yields (Scheme 6). Surprisingly the solubility of these pentacene
imides 10mp-r were much lower than the corresponding 2,3-bis(methoxycarbonyl)pentacene, although
much longer alkyl chains were substituted on the imide nitrogen atom.
For the imide formation step, 1,4-bis-silylated anhydride 7n did not react with primary amines probably
due to the steric hindrance of the bulky trimethylsilyl groups (Scheme 7).
Scheme 6. Formation of Pentacene Imides
O
CO2Me
i), ii)
iii)
CO2H
CO2H
O
CO2Me
(96%)
(98%)
O
1m
iv)
11m
v)
7m
O
O
N-R
N-R
O
O
9mp (R = 2-ethylhexyl, 91%)
9mq (R = n-octyl, 90%)
9mr (R = n-octadecyl, 94%)
10mp (R = 2-ethylhexyl, 91%)
10mq (R = n-octyl, 90%)
10mr (R = n-octadecyl, 90%)
iii) Ac O, 140 °C, 1 h
i) 15 eq. LiI, pyridine, reflux, 2 h. ii) 3 N HCl.
2
v) 1 eq. DDQ, toluene, 100 °C, 3 h.
iv) R-NH2, toluene, reflux, 6 h.
Scheme 7
TMS
TMS
O
TMS
TMS
O
CO2Me
R-NH2
LiI (15 eq.)
reflux, pyridine
O
N-R
CO2Me
toluene, reflux
O
TMS
O
TMS
(79%)
1n
7n
9n
CONCLUSION
Effect of the substituents at 1,4-positions of polycyclic aromatic compounds was remarkable for the
functionalization of 2,3-positions. Various functional groups could be introduced into substituted
naphthacenes and pentacenes by the functionalization of the corresponding 2,3-bis(alkoxycarbonyl)
naphthacenes and pentacenes which were obtained by zirconium-mediated homologation.
EXPERIMENTAL

HETEROCYCLES, Vol. 73, 2007
527
General Information. Manipulations were carried out under a nitrogen atmosphere using standard
Schlenk techniques. Diethyl ether was dried over 4 Å molecular sieves. Lithium aluminum hydride
and aluminum trichloride were purchased from KANTO Chemical Co. Ltd. NMR spectra were
recorded on a JEOL JNM-AL300 NMR spectrometer. Tetramethylsilane (TMS) was used as the
reference for 1H and 13C NMR.
Compounds 1a-n, 2j-l were prepared according to the literature.2,12
A Representative Procedure for the Reduction with LiAlH4 and AlCl3:
1,4-Bis(trimethylsilyl)-2,3-bis(hydroxymethyl)-5,12-dihydronaphthacene (2a).
4,13-Bis(trimethylsilyl)-1,3,5,12-tetrahydro-2-oxacyclopenta[b]naphthacene (3a).
To a suspension of LiAlH4 (114 mg, 3.0 mmol) in Et2O (10 mL), AlCl3 (1.20 g, 9.0 mmol) was added and
the mixture was stirred at 0 °C for 0.5 h. Diester 1a (490 mg, 1.0 mmol) was added to the mixture.
After stirring for 3 h at rt, the reaction mixture was carefully quenched with water and 2 N H2SO4 at 0 °C.
The organic layer was extracted with AcOEt. The extract was washed with saturated aqueous NaHCO3
solution, brine, and dried over Na2SO4. After removal of the solvent, the residue was purified by a
column chromatography on silica gel (AcOEt: hexane = 1: 10 as eluent) to afford the title compound 3a
as colorless solid (349 mg, 84% isolated yield, 94% NMR yield), and the corresponding diol 2a as
colorless solid (21 mg, 5% isolated yield, 6% NMR yield).
2a: 1H NMR (CDCl3, Me4Si) δ: 0.60 (s, 18 H), 3.40 (brs, 2 H), 4.18 (s, 4 H), 4.77 (s, 4 H), 7.39-7.42 (m,
2 H), 7.71 (s, 2 H), 7.77-7.80 (m, 2 H); 13C NMR (CDCl3, Me4Si) δ: 3.6, 38.7, 62.6, 124.1, 125.3, 127.2,
132.4, 136.4, 140.2, 143.3, 144.1; HRMS (EI) calcd for C26H34O2 Si2: 434.2097. Found: 434.2101.
3a: 1H NMR (CDCl3, Me4Si) δ: 0.48 (s, 18 H), 4.17 (s, 4 H), 5.11 (s, 4 H), 7.41-7.44 (m, 2 H), 7.73 (s, 2
13
H), 7.78-7.81 (m, 2 H); C NMR (CDCl3, Me4Si) δ: 2.1, 38.3, 74.5, 124.0, 125.3, 127.3, 131.1, 132.4,
136.7, 141.8, 143.1; HRMS (EI) calcd for C26H32OSi2: 416.1992. Found: 416.1987.
Preparation of 2,3-Bis(hydroxymethyl)-5,12-dihydronaphthacene (2b) from 1b.
The title compound was prepared in 97% isolated yield by the same way as described for 2a.
1
2b: H NMR (DMSO-d6, Me4Si) δ: 4.05 (s, 4 H), 4.52 (s, 4 H), 5.08 (brs, 2 H), 7.37 (s, 2 H), 7.41-7.45
13
(m, 2 H), 7.84 (s, 2 H), 7.82-7.85 (m, 2 H); C NMR (DMSO-d6, Me4Si) δ: 35.7, 60.3, 124.8, 125.3,
125.9, 127.1, 131.8, 134.9, 136.1, 137.3; HRMS (EI) calcd for C20H18O2: 290.1307. Found: 290.1321.
Preparation of 1,2-Bis(hydroxymethyl)-3,4,5,6-tetraphenylbenzene (2c).
Preparation of 4,5,6,7-Tetraphenyl-1,3-dihydroisobenzofuran (3c).
The compounds 2c and 3c were prepared in 65 and 35% NMR yields, respectively, by the same way as

528
HETEROCYCLES, Vol. 73, 2007
described for 2a, 3a.
2c: 1H NMR (CDCl3, Me4Si) δ: 2.71 (brs, 2 H), 4.68 (s, 4 H), 6.72-6.82 (m, 10 H), 7.10-7.17 (m, 10 H);
13C NMR (CDCl3, Me4Si) δ: 61.1, 125.4, 126.5, 126.6, 127.4, 130.4, 130.9, 137.3, 139.7, 140.1, 141.4,
142.0; HRMS (EI) calcd for C32H26O2: 442.1933. Found: 442.1926.
1
3c: H NMR (CDCl3, Me4Si) δ: 5.11 (s, 4 H), 6.79-6.91 (m, 10 H), 7.07-7.21 (m, 10 H); 13C NMR
(CDCl3, Me4Si) δ: 74.4, 125.5, 126.6, 126.8, 127.8, 129.3, 131.4, 134.7, 137.6, 139.3, 139.5, 140.5;
HRMS (EI) calcd for C32H24O: 424.1827. Found: 424.1832.
1,4,6,11-Tetrapropyl-2,3-bis(hydroxymethyl)-5,12-dihydronaphthacene (2d).
4,6,11,13-Tetrapropyl-1,3,5,12-tetrahydro-2-oxacyclopenta[b]naphthacene (3d).
The compounds 2d and 3d were prepared in 45 and 55% NMR yields, respectively, by the same way as
described for 2a, 3a.
1
2d: H NMR (CDCl3, Me4Si) δ: 1.15 (t, J = 7.2 Hz, 6 H), 1.17 (t, J = 7.2 Hz, 6 H), 1.59-1.77 (m, 8 H),
2.56 (brs, 2 H), 2.88-2.94 (m, 4 H), 3.17-3.23 (m, 4 H), 4.09 (s, 4 H), 4.83 (s, 4 H), 7.43-7.46 (m, 2 H),
8.04-8.07 (m, 2 H); 13C NMR (CDCl3, Me4Si) δ: 14.8, 14.9, 24.3, 25.3, 30.6, 30.9, 31.8, 59.8, 124.5,
124.7, 131.0, 132.2, 133.4, 135.9, 136.3, 137.1; HRMS (EI) calcd for C32H42O2: 458.3185. Found:
458.3187.
1
3d: H NMR (CDCl3, Me4Si) δ: 1.08 (t, J = 7.2 Hz, 6 H), 1.17 (t, J = 7.2 Hz, 6 H), 1.60-1.77 (m, 8 H),
2.63-2.68 (m, 4 H), 3.17-3.23 (m, 4 H), 4.06 (s, 4 H), 5.15 (s, 4 H), 7.42-7.46 (m, 2 H), 8.04-8.08 (m, 2
H); 13C NMR (CDCl3, Me4Si) δ: 14.6, 14.8, 23.8, 24.3, 29.7, 30.9, 33.0, 73.8, 124.5, 124.7, 130.0, 131.0,
132.1, 133.7, 135.5, 135.9; HRMS (EI) calcd for C32H40O: 440.3079. Found: 440.3078.
1,4,6,13-Tetrabutyl-2,3-bis(hydroxymethyl)-5,14-dihydropentacene (2e).
4,6,13,15-Tetrabutyl-1,3,5,14-tetrahydro-2-oxacyclopenta[b]pentacene (3e).
The compounds 2e and 3e were prepared in 41% and 59% NMR yields, respectively, from 1e by the same
way as described for 2a, 3a.
2e: 1H NMR (CDCl3, Me4Si) δ: 1.08 (t, J = 7.2 Hz, 6 H), 1.11 (t, J = 7.2 Hz, 6 H), 1.61-1.82 (m, 16 H),
2.30 (brs, 2 H), 2.95-3.00 (m, 4 H), 3.35-3.40 (m, 4 H), 4.16 (s, 4 H), 4.88 (s, 4 H), 7.42-7.47 (m, 2 H),
13
8.00-8.03 (m, 2 H), 8.60 (s, 2 H); C NMR (CDCl3, Me4Si) δ: 14.0, 14.1, 23.4, 23.6, 28.7, 29.4, 30.7,
33.1, 34.2, 59.9, 122.9, 124.9, 128.2, 130.1, 130.8, 131.6, 132.8, 136.0, 136.4, 137.1; HRMS (EI) calcd
for C40H52O2: 564.3967. Found: 564.3958.
3e: 1H NMR (CDCl3, Me4Si) δ: 1.03 (t, J = 7.2 Hz, 6 H), 1.09 (t, J = 7.2 Hz, 6 H), 1.50-1.78 (m, 16 H),
2.66-2.72 (m, 4 H), 3.33-3.37 (m, 4 H), 4.11 (s, 4 H), 5.16 (s, 4 H), 7.41-7.44 (m, 2 H), 7.99-8.02 (m, 2
13
H), 8.59 (s, 2 H); C NMR (CDCl3, Me4Si) δ: 14.0, 14.1, 23.2, 23.5, 28.7, 29.8, 30.6, 32.7, 33.1, 73.8,

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122.9, 124.9, 128.2, 130.1, 130.1, 130.8, 131.6, 133.1, 135.5, 135.8; HRMS (EI) calcd for C40H50O:
546.3862. Found: 546.3860.
Preparation of 4,9-Di-tert-butyl-1,3,5,6,7,8-hexahydronaphtho[2,3-c]furan (3f) from 1f.
LiAlH4 (114 mg, 3.0 mmol) was mixed with AlCl3 (1.20 g, 9.0 mmol) in anhydrous Et2O (10 mL) at 0 °C
for 0.5 h. Diester 1f (360 mg, 1.0 mmol) was added to the mixture. After refluxing for 2 days,
hydrolysis with water and 2 N H2SO4 was performed carefully at 0 °C. The mixture was extracted with
AcOEt. The extract was washed with saturated aqueous NaHCO3 and brine then dried over Na2SO4.
Column chromatography on silica gel (AcOEt: hexane = 1: 10 as eluent), 212 mg of title compound was
obtained as white crystals in 74% isolated yield (85% NMR yield).
3f: 1H NMR (CDCl3, Me4Si) δ: 1.45 (s, 18 H), 1.58-1.63 (m, 4 H), 2.80-2.84 (m, 4 H), 5.19 (s, 4 H); 13C
NMR (CDCl3, Me4Si) δ: 20.0, 27.6, 32.6, 37.0, 73.4, 134.6, 139.3, 141.2; HRMS (EI) calcd for C20H30O:
286.2297. Found: 286.2274.
A Representative Procedure for the Swern Oxidation:
Preparation of Benzene-1,2-dialdehyde (4g) from 2g.
To a 20 mL Schlenk tube, oxalyl chloride 0.22 mL (2.5 mmol) was added into 3 mL of dry CH2Cl2 under
nitrogen. Then 0.35 mL (5 mmol) of DMSO in 1 mL of dry CH2Cl2 was added dropwise at -78 °C.
After 5 min, to a solution of 1 mmol of diol 2g in 1 mL of dry CH2Cl2 was dropwisely added 0.5 mL of
DMSO. The reaction mixture was stirred for 1 h, and then 3 mL of Et3N was added slowly at -78 °C.
Then it was warmed to rt. After 1 h, the reaction mixture was poured into water and extracted with
AcOEt. The combined organic layer was dried over Na2SO4, filtered, and evaporated to give the crude
products. Chromatography on Aluminium Oxide 90 active neutral (hexane: AcOEt = 3:1) gave 95 mg
of the title compound as a pale yellow solid in 71% isolated yield.
All spectral data were identical to the reported ones.9
Preparation of 3,4-Dipropylbenzene-1,2-dialdehyde (4h) from 2h.
The title compound was prepared in 90% isolated yield as a white solid from 2h by the same way as
described for 4g.
4h: 1H NMR (CDCl3, Me4Si) δ: 1.01 (t, J = 7.5 Hz, 6 H), 1.60-1.70 (m, 4 H), 2.71 (t, J = 7.5 Hz, 4 H),
13
7.74 (s, 2 H), 10.49 (s, 2 H); C NMR (CDCl3, Me4Si) δ: 14.0, 23.8, 34.6, 132.2, 134.1, 147.3, 192.4;
HRMS (EI) calcd for C14H18O2: 218.1307. Found: 218.1307.
Preparation of 9,10-Dihydroanthracene-2,3-dialdehyde (4i) from 2i.

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HETEROCYCLES, Vol. 73, 2007
The title compound was prepared in 30% isolated yield as a white solid from 2i by the same way as
described for 4g.
4i: 1H NMR (CDCl3, Μe4Si) δ: 4.07 (s, 4 H), 7.25-7.32 (m, 4 H), 7.88 (s, 2 H), 10.53 (s, 2 H); 13C NMR
(CDCl3, Μe4Si) δ: 36.1, 126.8, 127.5, 130.3, 134.5, 134.6, 143.3, 192.1; HRMS calcd for C16H12O2:
236.0837. Found: 236.0837.
Preparation of 4,5,6,7-Tetrapropyl-1,3-dihydroisobenzofuran-1,3-diol (5j) from 2j.
The title compound was prepared in 55% isolated yield as a pale yellow solid from 2j by the same way as
described for 4g.
1
5j: H NMR (CDCl3, Me4Si) δ: 0.99-1.07 (m, 12 H), 1.44-1.66 (m, 8 H), 2.47-2.59 (m, 6 H), 2.67-2.77
(m, 2 H), 3.82 (s, 2 H), 6.15 (s, 2 H); 13C NMR (CDCl3, Me4Si) δ: 14.8, 14.9, 24.4, 25.0, 31.3 (2C), 99.5,
134.2, 135.9, 141.2; HRMS (EI) calcd for C20H32O3: 320.2351. Found: 320.2351.
Swern Oxidation of 2a.
Swern oxidation of 2a was carried out as described above. Before poured into water, the reaction
mixture was concentrated in vacuo and the reaction was checked by NMR study. NMR study clearly
indicated no formation of dialdehyde derivatives. Furthermore, the characteristic peak at 98.7 ppm on
13C NMR spectrum suggest the structure of anthra[2,3-c]furan-1,3-diol derivative analogized to 5j. The
selected data are listed below. After column separation, it was found that the product was contaminated
with Et3N and undefined compounds.
5a:13C NMR (CDCl3, Me4Si) δ: 1.4, 37.9, 98.7, 123.2, 124.9, 126.5, 131.6, 132.9, 136.1, 143.1, 144.6.
Swern Oxidation of 2k.
The reaction of 2a was carried out in the same way as described above. After column separation, the
product was contaminated with Et3N and undefined products. Its NMR data of reaction mixture
indicated the formation of 4,6,7,8,9,11-hexapropyl-1,3,5,10-tetrahydro-anthra[2,3-c]furan-1,3-diol (5k).
13
5k: C NMR (CDCl3, Me4Si) δ: 14.7, 15.0, 15.1, 24.1, 24.5, 25.0, 29.3, 31.3, 32.2, 32.3, 99.6, 132.2,
133.4, 135.1, 135.6, 136.6, 138.9.
Preparation of 8,9,10,11-Tetraethyl-4,6,13,15-tetrabutyl-1,3,5,14-tetrahydro-penta[2,3-c]furan-1-ol
(6l) from 2l.
The title compound was prepared in 62% isolated yield as a pale green solid from 2l by the same way as
described for 4g.
1
6l: H NMR (CDCl3, Me4Si) δ: 1.03 (t, J = 7.2 Hz, 6 H), 1.10 (t, J = 7.2 Hz, 6 H), 1.29 (t, J = 7.5 Hz, 6
H), 1.43 (t, J = 7.5 Hz, 6 H), 1.52-1.71 (m, 12 H), 1.77-1.83 (m, 4 H), 2.67-2.73 (m, 3 H), 2.89-2.93 (m, 5

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531
H), 3.27 (q, J = 7.2 Hz, 4 H), 3.37 (t, J = 6.9 Hz, 4 H), 4.12 (s, 4 H), 5.02 (d, J = 13 Hz, 1H), 5.28 (d, J =
13 Hz, 1H) 6.54 (dd, J = 12.0 and 1.8 Hz, 1 H), 8.77 (s, 2 H); 13C NMR (CDCl3, Me4Si) δ: 13.94, 13.97,
14.00, 15.4, 15.9, 22.1, 23.0, 23.2, 23.4, 23.5, 28.7, 29.2, 29.8, 29.9, 30.3, 32.6, 33.1, 33.4, 71.6, 102.1,
119.46, 119.49, 128.8, 128.9, 130.1, 131.6, 132.0, 132.1, 132.6, 134.70, 134.73, 135.20, 135.9, 136.9,
137.1, 138.3; HRMS (EI) calcd for C48H66O2: 674.5063. Found: 674.5076.
A Representative Procedure for Cleavage of Carboxylic Esters with Lithium Iodide:
Preparation of 1,4-Bis(trimethylsilyl)-5,12-dihydronaphthacene-2,3-dicarboxylic Anhydride (7a)
from 1a.
1,4-Bis(trimethylsilyl)-2,3-bis(methoxycarbonyl)-5,12-dihydronaphthacene 1a (490 mg, 1.0 mmol) and
LiI (2 g, 15.0 mmol) were added to 30 mL of anhydrous pyridine. Under nitrogen atmosphere, the
solution was heated to reflux for 3 h. After cooling to rt, the solvent was removed in vacuo. The
residue was acidified with aqueous 3 N HCl (pH = 1) and extracted with CHCl3. After removal of the
solvent, the residue was dissolved in 3 mL of CHCl3 and it was put into 10 mL of MeOH. The resulting
precipitate was collected by filtration, and dried in vacuo to afford the title compound 138 mg as a yellow
solid in 31 % isolated yield.
7a: 1H NMR (CDCl3, Me4Si) δ: 0.59 (s, 18 H), 4.33 (s, 4 H), 7.43-7.45 (m, 2 H), 7.74 (s, 2 H), 7.81-7.90
13
(m, 2 H); C NMR (CDCl3, Me4Si) δ: 2.2, 39.0, 124.7, 125.8, 127.3, 132.6, 134.5, 135.1, 141.2, 152.3,
164.1; HRMS (EI) calcd for C26H28Si2: 444.1577. Found: 444.1572.
Preparation of 1,4-Bis(trimethylsilyl)pentacene-2,3-dicarboxylic Anhydride (8a) from 7a.
DDQ (13.6 mg, 0.06 mmol) in 2 mL of toluene was dropwisely added to 7a (26.6 mg, 0.06 mmol) in 1
mL of toluene at 100 °C over 3 h. After cooling to rt, the precipitate was removed by filtration, and the
filtrate was concentrated in vacuo. The residue was dissolved in CHCl3 (30 mL) and filtered to remove
the remaining hydroquinone. The solvent was removed in vacuo, the residue was dissolved in 1 mL of
CHCl3, and the mixture was put into 10 mL of degassed MeOH. The mixture was stirred for 10 min to
produce precipitate of the title compound as red solid, which was collected by filtration (6.6 mg, 25%
yield).
8a: 1H NMR (CDCl3, Me4Si) δ: 0.72 (s, 18 H), 7.51-7.53 (m, 2 H), 8.06-8.08 (m, 2 H), 8.71 (s, 2 H), 9.35
13
(s, 2 H); C NMR (CDCl3, Me4Si) δ: 2.4, 126.5, 127.2, 128.4, 129.9, 130.4, 132.3, 132.9, 135.1, 150.6,
164.0; HRMS (EI) calcd for C26H26Si2 442.1420. Found: 442.1421.
Preparation of 1,4,6,13-Tetrabutyl-8,9,10,11-tetraethyl-5,14-dihydropentacene-2,3-dicarboxylic
Anhydride (7l) from 1l.

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HETEROCYCLES, Vol. 73, 2007
The title compound was prepared in 80% isolated yield as a yellow solid from 1l by the same way as
described for 7a.
7l: 1H NMR (CDCl3, Me4Si) δ: 1.06 (t, J = 7.3 Hz, 6 H), 1.11 (t, J = 7.3 Hz, 6 H), 1.30 (t, J = 7.5 Hz, 6 H),
1.43 (t, J = 7.5 Hz, 6 H), 1.59-1.72 (m, 12 H), 1.74-1.86 (m, 4 H), 2.90 (q, J = 7.5 Hz, 4 H), 3.24-3.41 (m,
13
12 H), 4.25 (s, 4 H), 8.80 (s, 2 H); C NMR (CDCl3, Me4Si) δ: 13.9, 14.0, 15.4, 15.9, 22.0, 23.0, 23.1,
23.5, 27.6, 28.7, 30.3, 32.9, 33.1, 119.7, 126.3, 128.8, 129.1, 129.6, 132.4, 134.8, 137.4, 139.3, 146.7,
163.5; HRMS (ESI) calcd for C48H62O3: 686.4699. Found: 686.4669.
Preparation of 1,4,6,13-Tetrabutyl-8,9,10,11-tetraethylpentacene-2,3-dicarboxylic Anhydride (8l)
from 7l.
DDQ (114 mg, 0.5 mmol) in 2 mL of toluene was dropwisely added to 7l (343 mg, 0.5 mmol) in 1 mL of
toluene at 100 °C over 3 h. After cooling to rt, the resulting reaction mixture was purified by a flash
chromatography under N2 (silica gel, CHCl3 as eluent) to afford the title compound as blue solid (205 mg,
60% yield).
8l: 1H NMR (CDCl3, Me4Si) δ: 1.08 (t, J = 7.2 Hz, 6 H), 1.14 (t, J = 7.2 Hz, 6 H), 1.33 (t, J = 7.6 Hz, 6 H),
1.51 (t, J = 7.6 Hz, 6 H), 1.64-1.81 (m, 8 H), 1.85-1.93 (m, 4 H), 2.00-2.07 (m, 4 H), 2.92 (q, J = 7.2 Hz,
4 H), 3.34 (q, J = 7.2 Hz, 4 H), 3.78 (t, J = 7.6 Hz, 4 H), 4.01 (t, J = 7.6 Hz, 4 H), 9.20 (s, 2 H), 9.42 (s, 2
H); 13C NMR (CDCl3, Me4Si) δ: 14.0, 14.1, 15.3, 15.7, 22.1, 23.1, 23.4, 23.7, 27.3, 28.8, 33.3, 34.1,
119.0, 120.4, 125.4, 127.7, 128.3, 129.6, 130.3, 134.7, 135.3, 138.4, 146.3, 163.5; HRMS (EI) calcd for
C48H60O3: 684.4542. Found: 684.4546.
Preparation of 1,4,6,13-Tetrabutyl-8,9,10,11-tetraethyl-5,14-dihydro-(N-n-hexyl)pentacene-2,3-
dicarboxylic Imide (9lo) from 7l.
In a 50 mL flask fitted with a water separator and a refluxing condenser were placed anhydride 7l (686
mg, 1.0 mmol), n-hexylamine (159 µL, 1.2 mmol) and 15 mL of toluene. The flask was heated to
maintain a vigorous reflux for 6 h. After cooling to rt, the mixture was washed with aqueous 3 N HCl,
saturated aqueous NaHCO3, brine and dried over Na2SO4. After evaporation of the solvent, 738 mg of
title compound was obtained as a yellow solid in 96% isolated yield.
9lo: 1H NMR (CDCl3, Me4Si) δ: 0.86 (t, J = 6.9 Hz, 3 H), 1.06 (t, J = 6.9 Hz, 6 H), 1.11 (t, J = 6.9 Hz, 6
H), 1.30 (t, J = 7.2 Hz, 12 H), 1.41-1.45 (m, 8 H), 1.59-1.74 (m, 12 H), 1.76-1.83 (m, 4 H), 2.90 (q, J =
7.5 Hz, 4 H), 3.28 (q, J = 7.5 Hz, 4 H), 3.34-3.41 (m, 8 H), 3.62 (m, 2 H), 4.20 (s, 4 H), 8.79 (s, 2 H); 13C
NMR (CDCl3, Me4Si) δ: 13.9, 14.0 (2C), 15.4, 15.7, 22.1, 22.5, 23.0, 23.3, 23.5, 26.6, 27.3, 28.6, 28.7,
30.0, 31.4, 33.1 (2C), 37.7, 119.6, 126.8, 128.8, 129.0, 130.6, 132.1, 134.8, 137.2, 137.7, 144.0, 169.4;
HRMS (FAB) calcd for C54H75NO2: 769.5798. Found: 769.5794.

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Preparation of 1,4,6,13-Tetrabutyl-8,9,10,11-tetraethyl-5,14-dihydro-(N-2-ethylhexyl)-pentacene-
2,3-dicarboxylic Imide (9lp) from 7l.
The title compound was prepared in 92% isolated yield from 7l as a yellow solid by the same way as
described for 9lo.
9lp: 1H NMR (CDCl3, Me4Si) δ: 0.86 (t, J = 6.9 Hz, 3 H), 0.90 (t, J = 7.2 Hz, 3 H), 1.06 (t, J = 7.2 Hz, 6
H), 1.11 (t, J = 7.2 Hz, 6 H), 1.30 (t, J = 7.5 Hz, 12 H), 1.43 (t, J = 7.5 Hz, 8 H), 1.62-1.72 (m, 12 H),
1.74-1.86 (m, 5 H), 2.91 (q, J = 7.2 Hz, 4 H), 3.29 (q, J = 7.5 Hz, 4 H), 3.36-3.41 (m, 8 H), 3.53 (d, J =
13
7.2 Hz, 2 H), 4.20 (s, 4 H), 8.79 (s, 2 H); C NMR (CDCl3, Me4Si) δ: 10.6, 13.9, 14.0, 14.1, 15.4, 15.7,
22.1, 23.0, 23.1, 23.2, 23.5, 24.0, 27.3, 28.5, 28.7, 30.0, 30.6, 33.1, 33.1, 38.3, 41.6, 119.6, 126.7, 128.8,
129.0, 130.6, 132.1, 134.7, 137.2, 137.2, 144.0, 169.6; HRMS (EI) calcd for C56H79O2N: 797.6111.
Found: 797.6093.
Preparation
of
1,4,6,13-Tetrabutyl-8,9,10,11-tetraethyl-(N-n-hexyl)pentacene-2,3-dicarboxylic
Imide (10lo) from 9lo.
The title compound was prepared in 76% yield from 9lo as blue solid by the same way as described for 8l.
1
10lo: H NMR (CDCl3, 323 K, Me4Si) δ: 0.90 (t, J = 6.9 Hz, 3 H), 1.08 (t, J = 7.2 Hz, 6 H), 1.13 (t, J =
7.2 Hz, 6 H), 1.33 (t, J = 7.2 Hz, 12 H), 1.48-1.53 (m, 6 H), 1.62-1.79 (m, 10 H), 1.82-1.92 (m, 4 H),
1.97-2.07 (m, 4 H), 2.92 (q, J = 7.5 Hz, 4 H), 3.33 (q, J = 7.5 Hz, 4 H), 3.71-3.81 (m, 6 H), 3.96 (m, 4 H),
13
9.16 (s, 2 H), 9.29 (s, 2 H); C NMR (CDCl3, 323 K, Me4Si) δ: 14.0, 14.1 (2C), 15.3, 15.8, 22.1, 22.6,
23.1, 23.5, 23.7, 26.8, 26.8, 28.5, 28.8, 31.5, 33.3, 34.1, 38.1, 120.3, 121.2, 124.5, 127.5, 128.1, 129.6,
129.9, 134.7, 134.7, 138.0, 142.0, 168.4; HRMS (FAB) calcd for C54H73NO2: 767.5641. Found:
767.5635.
Preparation of 1,4,6,13-Tetrabutyl-8,9,10,11-tetraethyl-(N-2-ethylhexyl)pentacene-2,3-dicarboxylic
Imide (10lp) from 9lp.
The title compound was prepared in 68% isolated yield from 9lp as blue solid by the same way as
described for 8l.
1
10lp: H NMR (CDCl3, 323 K, Me4Si) δ: 0.91 (t, J = 6.9 Hz, 3 H), 0.98 (t, J = 7.2 Hz, 3 H), 1.08 (t, J =
7.2 Hz, 6 H), 1.15 (t, J = 7.2 Hz, 6 H), 1.34 (t, J = 7.2 Hz, 6 H), 1.52 (t, J = 7.2 Hz, 6 H), 1.30-1.44 (m, 9
H), 1.65-1.80 (m, 8 H), 1.84-1.95 (m, 4 H), 2.00-2.10 (m, 4 H), 2.94 (q, J = 7.5 Hz, 4 H), 3.34 (q, J = 7.5
Hz, 4 H), 3.66 (d, J = 6.9 Hz, 2 H), 3.79-3.84 (m, 4 H), 3.96-4.01 (m, 4 H), 9.17 (s, 2 H), 9.32 (s, 2 H);
13C NMR (CDCl3, 323 K, Me4Si) δ: 10.7, 14.0, 14.1 (2C), 15.3, 15.7, 22.1, 23.1, 23.2, 23.5, 23.7, 24.4,
26.8, 28.7, 28.8, 30.9, 33.4, 34.1, 38.3, 42.1, 120.3, 121.4, 124.6, 127.7, 128.2, 130.1, 130.1, 134.7, 134.8,
138.1, 142.0, 168.6; HRMS (FAB) calcd for C56H77NO2: 795.5954. Found: 795.5950.

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HETEROCYCLES, Vol. 73, 2007
Preparation of 5,7,12,14-Tetrahydropentacene-2,3-dicarboxylic Acid (11m) from 1m.
The title compound was prepared in 96% yield from diester 1m as a gray white solid by the same way as
described for 7a.
1
11m: H NMR (DMSO-d6, Me4Si) δ: 3.88 (s, 4 H), 3.96 (s, 4 H), 7.16-7.18 (m, 2 H), 7.26 (s, 2 H),
7.30-7.32 (m, 2 H), 7.62 (s, 2 H), 12.96 (brs, 2 H); 13C NMR (DMSO-d6, Me4Si) δ: 34.6, 35.0, 125.9
126.1, 127.2, 127.3, 130.7, 133.1, 134.4, 136.7, 139.8, 168.8; HRMS (FAB) calcd for C24H18O4Na
(M+Na+): 393.1103. Found: 393.1099.
Preparation of 5,7,12,14-Tetrahydropentacene-2,3-dicarboxylic Anhydride (7m) from 11m.
5,7,12,14-Tetrahydropentacene-2,3-dicarboxylic acid 11m (370 mg, 1.0 mmol) in 5 mL Ac2O was
refluxed for 2 h. After evaporation of the solvent, 345 mg of title compound was obtained as a white
solid in 98% isolated yield.
1
7m: H NMR (DMSO-d6, Me4Si) δ: 3.87 (s, 4 H), 3.94 (s, 4 H), 7.14-7.17 (m, 2 H), 7.26 (s, 2 H),
7.29-7.32 (m, 2 H), 8.11 (s, 2 H); 13C NMR (DMSO-d6, Me4Si) δ: 34.5, 35.0, 125.9, 126.2, 127.2, 131.6,
132.8, 133.5, 134.3, 136.8, 139.0, 168.0; HRMS (ESI) calcd for C24H16O3: 352.1099. Found: 352.1099.
Preparation of N-2-Ethylhexyl-5,7,12,14-tetrahydropentacene-2,3-dicarboxylic Imide (9mp) from
7m.
The title compound was prepared in 91% isolated yield from 7m by the same way as described for 9lo.
9mp: 1H NMR (CDCl3, Me4Si) δ: 0.87 (t, J = 6.9 Hz, 3 H), 0.90 (t, J = 7.2 Hz, 3 H), 1.26-1.36 (m, 8 H),
1.78-1.86 (m, 1 H), 3.55 (d, J = 7.2 Hz, 2 H), 3.93 (s, 4 H), 4.03 (s, 4 H), 7.17-7.21 (m, 2 H), 7.25 (s, 2 H),
13
7.27-7.30 (m, 2 H), 7.73 (s, 2 H); C NMR (CDCl3, Me4Si) δ: 10.4, 14.0, 22.9, 23.8, 28.4, 30.4, 35.7,
36.4, 38.2, 41.8, 122.1, 126.1, 126.2, 127.3, 130.2, 132.6, 135.1, 136.5, 143.8, 168.8; HRMS (EI) calcd
for C32H33O2N: 463.2511. Found: 463.2505.
Preparation of N-n-Octyl-5,7,12,14-tetrahydropentacene-2,3-dicarboxylic Imide (9mq) from 7m.
The title compound was prepared in 90% isolated yield from 7m by the same way as described for 9lo.
9mq: 1H NMR (CDCl3, Me4Si) δ: 0.86 (t, J = 6.9 Hz, 3 H), 1.25-1.31 (m, 10 H), 1.63-1.68 (m, 2 H), 3.65
(t, J = 7.2 Hz, 2 H), 3.94 (s, 4 H), 4.04 (s, 4 H), 7.17-7.22 (m, 2 H), 7.26 (s, 2 H), 7.28-7.31 (m, 2 H), 7.73
(s, 2 H); 13C NMR (CDCl3, Me4Si) δ: 14.1, 22.6, 26.9, 28.6, 29.1 (2C), 31.7, 35.8, 36.5, 38.1, 122.2,
126.1, 126.3, 127.4, 130.4, 132.7, 135.3, 136.6, 143.9, 168.7; HRMS (EI) calcd for C32H33O2N: 463.2511.
Found: 463.2512.
Preparation of N-n-Octadecyl-5,7,12,14-tetrahydropentacene-2,3-dicarboxylic Imide (9mr) from

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7m.
The title compound was prepared in 94% isolated yield from 7m by the same way as described for 9lo.
9mr: 1H NMR (CDCl3, Me4Si) δ: 0.88 (t, J = 6.9 Hz, 3 H), 1.23-1.31 (m, 30 H), 1.60-1.67 (m, 2 H), 3.64
(t, J = 7.2 Hz, 2 H), 3.92 (s, 4 H), 4.02 (s, 4 H), 7.17-7.21 (m, 2 H), 7.24 (s, 2 H), 7.27-7.30 (m, 2 H), 7.71
(s, 2 H); 13C NMR (CDCl3, Me4Si) δ: 14.1, 22.7, 26.9, 28.6, 29.2, 29.3, 29.5, 29.6, 29.6, 29.7 (7C), 31.9,
35.8, 36.5, 38.0, 122.1, 126.1, 126.3, 127.4, 130.4, 132.7, 135.2, 136.5, 143.8, 168.7; HRMS (EI) calcd
for C42H53O2N: 603.4076. Found: 603.4088.
Preparation of N-2-Ethylhexylpentacene-2,3-dicarboxylic Imide (10mp) from 9mp.
The title compound was prepared in 91% isolated yield from 10mp as a blue solid by the same way as
described for 8a. Due to its low solubility, NMR measurements were failed.
10mp: HRMS (EI) calcd for C32H29NO2: 459.2198. Found: 459.2198.
Preparation of N-n-Octylpentacene-2,3-dicarboxylic Imide (10mq) from 9mq.
The title compound was prepared in 90% isolated yield from 9mq as a blue solid by the same way as
described for 8a. Due to its low solubility, NMR measurements were failed.
10mq: HRMS (EI) calcd for C32H29NO2: 459.2198. Found: 459.2199.
Preparation of N-n-Octadecylpentacene-2,3-dicarboxylic Imide (10mr) from 9mr.
The title compound was prepared in 90% isolated yield from 9mr as a blue solid by the same way as
described for 8a.
10mr: HRMS (EI) calcd for C42H49NO2: 599.3763. Found: 599.3770.
Preparation of 1,4-Bis(trimethylsilyl)-5,7,12,14-tetrahydropentacene-2,3-dicarboxylic Anhydride
(7n) from 1n.
The title compound was prepared in 79% yield from 1n by the same way as described for 7a.
7n: 1H NMR (CDCl3, Me4Si) δ: 0.57 (s, 18 H), 3.94 (s, 4 H), 4.15 (s, 4 H), 7.17-7.21 (m, 2 H), 7.25 (s, 2
13
H), 7.27-7.30 (m, 2 H); C NMR (CDCl3, Me4Si) δ: 2.1, 35.9, 38.6, 125.6, 126.2, 127.3, 134.0, 134.9,
135.6, 136.5, 141.2, 152.5, 164.2; HRMS (FAB) calcd for C30H32O3Si2Na (M+Na+): 519.1788. Found:
519.1788.
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