Practical Preparation of Octa- and Tetrabromoperylene Diimides and Derivatives Thereof

Article abstract of DOI:10.1055/s-0036-1589088

A mild synthesis of fully brominated perylene dianhydride and diimides in one step from easily available unsubstituted precursors is presented. The partial reduction of ortho -bromo substituents with hydrazine hydrate allowed for a gram-scale synthesis of a valuable intermediate, 1,6,7,12-tetrabromoperylene diimide. Several new twisted fully core-substituted perylene diimide derivatives having sulfur, nitrogen, or oxygen substituents were synthesized using regioselective nucleophilic substitution reactions.

Full text of DOI:10.1055/s-0036-1589088

SYNTHESIS
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
© Georg Thieme Verlag Stuttgart · New York
2017, 49, A–G
paper
A
en
A. Jozeliūnaitė et al.
Paper
Synthesis
Practical Preparation of Octa- and Tetrabromoperylene Diimides
and Derivatives Thereof
Augustina Jozeliūnaitėa
Romualdas Strielab
Linas Labanauskasb
Br
Br
Br
Br
O
X
O
X
O
X
O
NBS
(10 equiv)
Edvinas Orentas*a
0
0
0
0
0-
0
0
2
7-
2
5
7
5-
6
3
4
Br
O
O
Br
Br
O
X
Nu–
Br
Br
Br
O
X
a Department of Organic Chemistry, Faculty of Chemistry
and Geosciences, Vilnius University, Naugarduko 24,
03225 Vilnius, Lithuania
b Center for Physical Sciences and Technology, Akademijos
7, 08412 Vilnius, Lithuania
Br
Br
Br
NH2NH2
1. NBS (6 equiv)
2. NH2NH2
O
O
O
X
Br
O
edvinas.orentas@chf.vu.lt
X = O, NR
X
O
X
O
Dedicated to Prof. V. Snieckus on the occasion of his 80th
birthday
O
O
Br
Br
Received: 30.05.2017
Accepted after revision: 04.07.2017
Published online: 02.08.2017
methods securing straightforward access to these com-
pounds are of high importance and not surprisingly, have
been extensively addressed by many research groups over
the years.1
DOI: 10.1055/s-0036-1589088; Art ID: ss-2017-z0366-op
Abstract A mild synthesis of fully brominated perylene dianhydride
and diimides in one step from easily available unsubstituted precursors
is presented. The partial reduction of ortho-bromo substituents with
hydrazine hydrate allowed for a gram-scale synthesis of a valuable inter-
mediate, 1,6,7,12-tetrabromoperylene diimide. Several new twisted
fully core-substituted perylene diimide derivatives having sulfur, nitro-
gen, or oxygen substituents were synthesized using regioselective nuc-
leophilic substitution reactions.
To introduce substituents of different electronic nature
into PDI’s aromatic rings, the direct aromatic nucleophilic
substitution using halogenated derivatives as starting ma-
terials proved to be the simplest and most efficient derivat-
ization method.6 The required core-halogenated com-
pounds are directly obtained by halogenation of either PDIs
or the corresponding dianhydrides, typically using harsh
conditions such as elemental Cl2 or Br2 in strongly acidic
medium at elevated temperature.7 The particular condi-
tions are highly dependent on the number of halogen atoms
to be introduced; more extensive halogenation requires
more forcing conditions. Up to four halogen atoms are rou-
tinely introduced using these methods, whereas derivatives
containing eight halogens are less explored. It should be
stressed, however, that the main limiting factor in all prepa-
rations remains the notoriously tedious and time-consum-
ing separation of the desired product due to the extensive
aggregation of both, the product itself and more detrimen-
tally, the product with by-products. Therefore, simple, high
yielding, and clean methods to access halogenated PDIs are
highly desired.
In our research, we became interested in utilizing the
regioselective functionalization of fully halogenated PDIs to
obtain a new family of twisted chromophores. Perhaloge-
nated PDIs, such as Cl8PDI3a,7e and Br4Cl4PDI7c,d are described
in literature and are synthesized by halogenation of unsub-
stituted PDI or Cl4PDIs, respectively, under forcing condi-
tions. Likewise, Br8PDIs8 are also synthesized from bay-
tetrabrominated precursors, which are, in turn, obtained in
a separate synthetic step. Alternatively, these compounds
are also accessible directly from the corresponding anhy-
dride, however, using the expensive dibromoisocyanuric
Key words octabromoperylene diimide, tetrabromoperylene diimide,
anion radical, core-twisted perylene diimides, chromophores
Perylene-3,4,9,10-tetracarboxylic
acid
diimide
(perylene diimide, PDI) and its derivatives represent one of
the most useful and stable polyaromatic pigments and dyes
with multiple applications both on industrial scale and in
academic research.1 The extended π-system of PDIs in con-
jugation with carbonyl groups of the imide moiety results
in the strong absorption in the visible region and often,
high quantum yield of fluorescence. Moreover, the easy
tuning of HOMO-LUMO energies, the absorption maxi-
mum, and thus the color of PDIs by simple core substitution
renders them especially attractive for applications in organ-
ic electronic devices, such as solar cells or field-effect tran-
sistors.2,3 The large surface of the π-system of PDIs is also
responsible for an efficient aggregation of these compounds
via π–π stacking, the extent of which can be modulated to
some degree by controlling the twisting of the aromatic
core caused by the substituents at the so-called bay (or
1,6,7,12) positions. The unique self-assembly properties
and the intrinsic chirality of this type of compounds recent-
ly have been elegantly explored in supramolecular chemis-
try context4 and anion-π catalysis.5 Due to the great utility
of the core-substituted PDIs in the above applications, the
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–G

B
A. Jozeliūnaitė et al.
Paper
Synthesis
acid and oleum as a solvent.9 We sought to develop a much
milder one-step synthesis of Br8PDIs using unsubstituted
PDIs as cheap and affordable starting materials. After
screening several bromination conditions for N,N′-dibutyl-
perylene-3,4,9,10-tetracarboxylic acid diimide (2) as a
model PDI, we were delighted to find that the convenient
brominating agent N-bromosucinimide (NBS) in concen-
trated sulfuric acid provided high yield (>90%) of NMR pure
product by simple precipitation (Scheme 1). We found that
only slight excess (1.25 equiv per C–H bond) of NBS was re-
quired and the reaction proceeded under mild conditions.
Thus, the procedure involved the portionwise addition of
the first 8 equivalents of NBS to a solution of the starting
material in concentrated H2SO4 at ambient temperature in 1
hour and then heating the mixture at 70 °C for 2 hours.
Then, another equivalent of NBS was added followed by the
last equivalent of NBS after 2 hours. Stirring the mixture at
room temperature overnight provided Br8PDI, however, in
few runs, a small amount of Br7PDI was also detected.
Therefore, the mixture was heated overnight at 70 °C before
the workup with ice. The precipitate formed contained vir-
tually pure Br8PDI (NMR) that could be utilized for the next
steps without further purification. The synthesis was rou-
tinely performed on 3.0 g scale, but also worked equally
well for >19.0 g of Br8PDI. On a sub-gram scale, the required
amount of NBS can be added all at once. The starting N,N′-
dibutylperylene-3,4,9,10-tetracarboxylic acid diimide (2)
was synthesized from anhydride 1 by applying known pro-
cedure and was further used without any purification. The
overall method with two consecutive precipitations of the
products enabled the synthesis of Br8PDI (3a) in two steps
from perylene dianhydride in >90% yield on a gram scale.
PDIs where the presence of aromatic substituent makes the
selective bromination of less reactive PDI core impossible.
Indeed, the application of the same bromination protocol
for 1 furnished 3b in 89% yield in a single step and in high
purity on a gram scale (Scheme 1).
Further, N,N′-dibutyl-perbrominated PDI 3a was used as
a representative starting compound to obtain several core-
substituted derivatives via SNAr substitution reaction with
N, O, and S-nucleophiles (Scheme 2). Due to a much higher
reactivity of ortho-bromine atoms located in a vicinity to
imide functionality compared to the bromine atoms at the
bay positions, the highly regioselective substitution is pos-
sible. Thus, treatment of 3a with an excess of n-butylamine
in THF at ambient temperature afforded the corresponding
tetra-substituted blue-colored product 4 in 92% yield.11
Likewise, the analogous transformation with less nucleo-
philic 4-n-butylaniline required reflux of the mixture and
provided the desired product 5 in excellent 95% yield. Reac-
tion of 3a with sodium methoxide yielded tetramethoxy-
PDI derivative 6 in 72% yield, whereas the substitution with
thiophenol resulted in magenta-colored 7 in 80% yield. At
this point, it should be noted that the success of the nucleo-
philic substitution reaction depends crucially on the ability
of the nucleophile to act as an electron donor. For instance,
the use of more electron-rich thiophenols or alkyl thiols to
obtain the analogues of 7 was much less effective due to a
competing formation of the radical anion of 3a. Increasing
the reducing power of nucleophile even more, as in the case
of hydrazine hydrate, resulted in further selective debromi-
nation reaction that smoothly afforded tetrabromo deriva-
tive 8 in good yield, free of any other brominated impuri-
ties. Interestingly, the methoxy substituents in 6 also
served as leaving groups and afforded the same compound
8 under identical reaction conditions, albeit in an unsatis-
factory yield of <20% (Scheme 2). Taken together, the appli-
cation of octabrominated PDI for core-functionalization of-
fers a direct method to this class of compounds without re-
sorting to mixed halogenated PDIs, such as Br4Cl4PDI to
achieve the desired regioselectivity.7d
Given the importance of redox-mediated modulation of
the HOMO/LUMO levels of the PDI chromophores12 contain-
ing aryl/alkylthio substituents, we sought to develop a con-
venient method to overcome the detrimental formation of a
radical anion when using electron rich thiols. As a plausible
alternative, we utilized an umpolung logic to synthesize the
otherwise not accessible analogues of 7 (Scheme 3). Com-
pound 3a was first converted into benzenesulfonothioate 9
in THF using the readily available PhSO2SNa salt.13 The
product 9 was found to be sensitive to aqueous workup,
therefore, in order to remove the excess of PhSO2SNa and
NaBr, the solid residue obtained after evaporation of solvent
was extracted with dichloromethane. Compound 9 ob-
tained in this way was then subjected to Grignard reagent.
As exemplified with the reaction with 4-methoxyphenyl-
magnesium bromide, this procedure allowed the formation
Bu
O
O
O
O
N
O
O
X
O
Br
Br
Br
Br
NBS
BuNH2
NMP
H2SO4
70 °C to r.t.
Br
Br
Br
>90%
two steps
Br
O
O
O
O
N
O
O
X
O
1
2
Bu
3a X = NBu
3b X = O
NBS
H2SO4
70 °C to r.t.
89%
Scheme 1 Bromination of perylene dianhydride and N,N′-dibutyldiim-
ide
To extend the scope of the practical utility of this bro-
mination protocol, we also attempted to apply it for
perylene dianhydride (1) to obtain the corresponding per-
brominated dianhydride 3b. With compound 3b in hand,
the larger variety of perbrominated PDIs would be accessi-
ble using well established imidization methods for similar
compounds.8,10 This is particularly important for N-aryl
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–G

C
A. Jozeliūnaitė et al.
Paper
Synthesis
of the desired product in 80% overall yield. The proposed
transformation may find use in the synthesis of thiolated
derivatives beyond the PDI core and could potentially be
applied to other electron-deficient systems, such as naph-
thalene diimides.
Considering the unexpected formation of tetrabromo
PDI 8 by treating 3a with hydrazine hydrate (Scheme 2), the
reaction most likely proceeds via formation of intermediate
radical anion 3a•–. Despite the large core twisting, 3a with
its low-lying LUMO (–4.23 eV)8 remains a very powerful
electron acceptor.
The radical anion initially formed then undergoes bro-
mide elimination and subsequent hydrogen transfer, and
release of the proton completes the reductive dehalogena-
tion (Scheme 4, a, steps 1–3). The same sequence of trans-
formations, after repeating three more times, ultimately
leads to the product 8. The proposed mechanism involving
radical species is in line with recently discovered SRN1 reac-
tivity of brominated PDIs towards sterically hindered phe-
nols.14 Both, hydrazine hydrate and its oxidized form, diim-
ide, are strong reductants capable of transferring electron
to 3a. The formation of the gas was observed during the re-
action that points toward the formation of nitrogen as the
terminal oxidized form of hydrazine. Due to the very high
rate of the reaction, tracing the formation of the intermedi-
ate radical anion by UV/Vis spectroscopy proved to be diffi-
cult. Immediately after mixing 3a with hydrazine hydrate in
THF, the formation of radical anion having absorption max-
imum at 775 nm was observed (Scheme 4, b). In another
few minutes, the hypsochromic shift by 16 nm occurred
and no further changes with time were observed. By using
the control sample of hydrazine hydrate and 8, we con-
firmed that the final spectrum corresponds to the radical
anion of the product 8 whereas the initial spectrum might
be assigned to radical anion 3a•– or any of the intermediate
partially debrominated radical anions or their mixture.15
Lacking additional information, however, we cannot fully
rule out the involvement of the dianion 3a2– as an interme-
diate species.
The above reduction reaction was very clean and no
other brominated products besides 8 were observed. The
purification of 8 was easily done by simply passing the
crude mixture through a silica gel plug. Usually, the tetra-
bromo PDIs are prepared by direct bromination of the cor-
responding unsubstituted PDIs, however, the precise reac-
tion control is often difficult and the separation from other
brominated by-products is tedious. We decided to further
optimize the synthesis of 8 by reducing the redundant
amount of NBS used in the bromination step. We found that
6.0 equivalents of NBS were enough to obtain a mixture of
brominated products, free of tribromo derivative (Scheme
4, c). The crude mixture was then treated with hydrazine
BuHN
Br
Br
NHBu
O
O
BuNH2
THF
N Bu
O
Bu
N
O
Br
Br
NHBu
NHR
4
BuHN
Br
Br
92%
Bu
N
O
O
RHN
O
N
O
O
4-BuC6H4NH2
THF
Br
Br
Br
Br
N Bu
Bu
O
95%
Br
NHR
Br
Br
5
RHN
Br
R = 4-BuC6H4
Br
Br
NaOMe
MeO
MeO
Br
THF–MeOH
Br
OMe
O
O
N
O
O
Bu
3a
N Bu
Bu
NH2NH2
N
O
O
Br
OMe
PhSH
K2CO3
THF
Br
6
Br
THF
72%
THF
MeOH
NH2NH2
Br
82%
PhS
Br
SPh
Br
O
O
O
O
N Bu
N Bu
O
Bu
N
O
Bu
N
O
O
Br
Br
7
SPh
8
PhS
Br
Br
<20%
80%
Scheme 2 Core-substitution reactions of octabromoperylene diimide
with various nucleophiles
Bu
N
Bu
N
Bu
N
O
O
O
O
O
O
PhO2SS
ArS
Br
SSO2Ph
SAr
Br
Br
Br
Br
Br
PhSO2SNa
THF
ArMgBr
83%
Br
Br
Br
Br
Br
Br
Br
Br
Br
PhO2SS
SSO2Ph
ArS
SAr
Br
O
N
O
O
N
O
O
N
O
Bu
Bu
Bu
3a
9
10
Ar = 4-MeOC6H4
Scheme 3 The application of thiosulfinate for introducing aryl sulfides into PDI core
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–G

D
A. Jozeliūnaitė et al.
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Synthesis
Scheme 4 (a) Possible mechanism of the reduction of 3a with hydrazine. (b) Overlay of UV/Vis absorption spectra of a mixture of 3a and hydrazine
hydrate (20 equiv) and radical anion of 8 [8 + hydrazine hydrate (20 equiv)] in THF. (c) Synthesis of N,N′-dibutyltetrabromoperylene diimide 8; (d)
Synthesis of N,N′-dibenzyltetrabromoperylene diimide 11.
hydrate to afford compound 8 in 68% overall yield on a gram
scale. As an useful extension, this reduction procedure was
also applied to N,N′-dibenzyl PDI, which was obtained from
the corresponding mixture of brominated dianhydrides us-
ing benzylamine and then, PBr3 as dehydrating agent
(Scheme 4, d). The reduction of so-obtained diimide with
hydrazine hydrate furnished 11 in 40% combined yield over
three steps.
In conclusion, we have developed a mild and scalable
procedure for the synthesis of octabromoperylene diimides
and dianhydride. We have demonstrated practical utility of
these starting materials in obtaining different core persub-
stituted perylene diimide derivatives, covering a range of
colors. The newly discovered regioselective partial debro-
mination of octabromoperylene diimides with hydrazine
hydrate provides a convenient method to access syntheti-
cally valuable tetrabrominated derivatives in high purity.
All reagents were obtained from commercial sources and were used
without further purification. N,N′-dibutyl-3,4,9,10-tetracarboxylic
acid diimide (2) was prepared according to a previously reported pro-
cedure.16 THF was distilled from Na/benzophenone under argon at-
mosphere. CH2Cl2 was distilled from CaH2. Petroleum ether (PE) refers
to a 40–60 °C boiling fraction. The NMR spectra were recorded at r.t.
on a Bruker Ascend spectrometer (400 MHz and 100 MHz for 1H and
13C, respectively) using residual solvent signals as internal standards.
The absorption spectra were recorded with a PerkinElmer Lambda 35
in THF. Mass spectra were recorded with a Bruker Daltonics micrO-
TOF II spectrometer. IR spectra were recorded on a PerkinElmer Spec-
trum BX FTIR system. Melting points were measured with a Gallen-
kamp apparatus and are uncorrected. Silica gel TLC was performed
using silica gel 60 F254 aluminum sheets (Merck). Flash chromatogra-
phy was performed using silica gel 60 (0.040–0.063 mm, Merck).
N,N′-Dibutyloctabromoperylene-3,4,9,10-tetracarboxylic Acid
Diimide (3a)
To a suspension of perylene-3,4,9,10-tetracarboxylic acid dianhydride
(1; 5.0 g, 12.8 mmol, 1.0 equiv) in NMP (100 mL) was added BuNH2
(12.6 mL, 0.128 mol, 10 equiv). The reaction mixture was heated to
reflux under argon for 24 h, cooled to r.t., poured into 10% aq HCl (v/v)
carefully, filtered, and washed with H2O, MeOH, and Et2O. The dark
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–G

E
A. Jozeliūnaitė et al.
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Synthesis
red solid obtained was dried under reduced pressure and used in the
next step without further purification; yield: 6.14 g (95%). The above
crude N,N′-dibutylperylene-3,4,9,10-tetracarboxylic acid diimide (2;
3.0 g, 5.97 mmol, 1.0 equiv) was dissolved in concd H2SO4 (100 mL) at
r.t. with stirring. To the dark red-blue solution was added NBS (8.5 g,
47.8 mmol, 8.0 equiv) in 3 equal portions during 1 h. The mixture was
stirred at 70 °C for 2 h and then an additional amount of NBS (1.1 g,
0.59 mmol, 1.0 equiv) was added, followed by the last equivalent of
NBS (1.1 g, 0.59 mmol, 1.0 equiv) after 2 h. The mixture was heated at
70 °C overnight (16 h), poured onto ice (0.4 kg), and filtered. The pre-
cipitate was washed with copious amount of H2O and dried at 80 °C;
yield: 6.44 g (95%); red solid; mp 256 °C.
N,N′-Dibutyl-1,6,7,12-tetrabromo-2,5,8,11-tetramethoxyper-
ylene-3,4,9,10-tetracarboxylic Acid Diimide (6)
To a solution of 3a (74 mg, 0.065 mmol, 1.0 equiv) in THF–MeOH mix-
ture (15 mL/5.0 mL) was added NaOMe (70 mg, 1.31 mmol, 20 equiv).
The mixture was stirred at r.t. overnight, diluted with 10% aq HCl
(v/v), and filtered. The solid was purified by flash chromatography
(CH2Cl2, Rf = 0.16) to afford 6; yield: 44 mg (72%); orange-red solid;
mp 220 °C.
IR (neat): 1699 (C=O), 1657 cm–1 (C=O).
1H NMR (400 MHz, CDCl3): δ = 4.37–4.21 (m, 4 H, NCH2), 4.20 (s, 12 H,
OCH3), 1.83–1.71 (m, 4 H, CH2), 1.56–1.45 (m, 4 H, CH2), 1.02 (t, J = 7.5
Hz, 6 H, CH3).
13C NMR (100 MHz, CDCl3): δ = 161.1, 160.5, 133.9, 126.8, 124.0,
123.8, 113.5, 62.8, 40.7, 30.2, 20.5, 13.9.
Spectral and analytical data were in agreement with literature val-
ues.8
HRMS (ESI): m/z [M + H]+ calcd for C36H30Br4N2O8: 938.8773; found:
938.8775.
Octabromoperylene-3,4,9,10-tetracarboxylic Acid Dianhydride
(3b)
To a stirred suspension of 1 (3.0 g, 7.65 mmol) in concd H2SO4 (100
mL) was added NBS (13.6 g, 76.5 mmol 10 equiv) in 3 equal portions
at r.t. over 1 h. The reaction mixture was heated at 70 °C overnight (16
h) in a stoppered flask. A red clear solution was obtained in the first
few hours and then, a red precipitate started to form. After cooling to
r.t., the mixture was poured onto ice (0.5 kg) and the precipitate
formed was filtered and washed with H2O. The solid was dried first in
air at 90 °C for 6 h and then under reduced pressure to a constant
mass; yield: 6.96 g (89%); red solid; mp >300 °C.
UV/Vis (THF): λmax (ε) = 485 (2.9·104), 520 nm (3.0·104 M–1 cm–1).
N,N′-Dibutyl-1,6,7,12-tetrabromo-2,5,8,11-tetrathiophenyl-
perylene-3,4,9,10-tetracarboxylic Acid Diimide (7)
To a solution of 3a (100 mg, 0.09 mmol, 1.0 equiv) in THF (25 mL)
were added K2CO3 (243 mg, 1.76 mmol, 20 equiv) and thiophenol
(0.18 mL, 1.76 mmol, 20 equiv). The mixture was stirred for 2 h at r.t.,
diluted with H2O, and extracted with CH2Cl2. The organic phase was
dried (Na2SO4), filtered, and evaporated to dryness. The residue was
purified by flash chromatography [CH2Cl2–PE, 1:2, Rf = 0.24 (CH2Cl2)]
to afford 7; yield: 88 mg (80%); violet solid; mp 285 °C.
Spectral and analytical data were in agreement with literature val-
ues.8
IR (neat): 1695 (C=O), 1660 cm–1 (C=O).
N,N′-Dibutyl-1,6,7,12-tetrabromo-2,5,8,11-tetrabutylamino-
perylene-3,4,9,10-tetracarboxylic Acid Diimide (4)
1H NMR (400 MHz, CDCl3): δ = 7.30–7.26 (m, 16 H, ArH), 7.26–7.19
(m, 4 H, ArH), 3.76–3.65 (m, 2 H, NCH2), 3.34–3.24 (m, 2 H, NCH2),
1.18–1.09 (m, 4 H, CH2), 1.18–1.09 (m, 6 H, CH2), 0.98–0.87 (m, 2 H,
CH2), 0.84 (t, J = 7.1 Hz, 6 H, CH3).
13C NMR (100 MHz, CDCl3): δ = 160.5, 145.8, 136.7, 132.7, 132.0,
129.6, 129.4, 128.2, 127.6, 126.1, 122.5, 41.6, 29.5, 20.2, 13.6.
HRMS (ESI): m/z [M + H]+ calcd for C56H38Br4N2O4S4: 1250.8488;
found: 1250.8482.
UV/Vis (THF): λmax (ε) = 490 (1.6·104), 566 nm (2.4·104 M–1 cm–1).
To a solution of 3a (300 mg, 0.26 mmol, 1.0 equiv) in THF (50 mL) was
added BuNH2 (780 mg, 10.7 mmol, 40 equiv). The mixture was stirred
at r.t. for 2 h and evaporated to dryness under reduced pressure. The
residue was purified by flash chromatography (CHCl3, Rf = 0.39) to af-
ford 4; yield: 270 mg (92%); blue solid; mp >250 °C.
Spectral and analytical data were in agreement with literature val-
ues.8
N,N′-Dibutyl-1,6,7,12-tetrabromo-2,5,8,11-tetra(4-butylphenyl-
amino)perylene-3,4,9,10-tetracarboxylic Acid Diimide (5)
N,N′-Dibutyl-1,6,7,12-tetrabromoperylene-3,4,9,10-tetracarboxyl-
ic Acid Diimide (8)
To a solution of 3a (100 mg, 0.09 mmol, 1.0 equiv) in THF (50 mL) was
added n-butylaniline (0.56 mL, 3.53 mmol, 40 equiv). The mixture
was heated at 80 °C for 24 h, cooled to r.t. and evaporated to dryness
under reduced pressure. The residue was purified by flash chroma-
tography (CHCl3–PE, 1:1, Rf = 0.87) to afford 5; yield: 120 mg (95%);
blue solid; mp 282 °C.
Method A: To a solution of 3a (63 mg, 0.055 mmol. 1.0 equiv) in THF–
MeOH (15 mL/10 mL) was added hydrazine hydrate (56 mg, 1.11
mmol, 20 equiv). The mixture was stirred at r.t. for 1.5 h. The solvent
was evaporated and the residue was purified by flash chromatogra-
phy (CH2Cl2, Rf = 0.74) to afford 8; yield: 37 mg (82%).
IR (neat): 3171 (NH), 1645 (C=O), 1623 cm–1 (C=O).
Spectral and analytical data were in agreement with literature val-
ues.17
1H NMR (400 MHz, CDCl3): δ = 11.72 (s, 4 H, NH), 7.12 (d, J = 8.4 Hz, 8
H, ArH), 7.02 (d, J = 8.4 Hz, 8 H, ArH), 4.27–4.12 (m, 4 H, NCH2), 2.62 (t,
J = 7.6 Hz, 8 H, ArCH2), 1.75–1.59 (m, 8 H, CH2), 1.47–1.34 (m, 8 H,
CH2), 0.98 (2 t overlapped, 18 H, CH3).
13C NMR (100 MHz, CDCl3): δ = 165.0, 149.6, 139.6, 139.0, 136.8,
128.7, 128.5, 122.2, 119.4, 115.5, 105.6, 40.7, 35.1, 33.8, 30.0, 22.4,
20.5, 14.0, 13.8.
HRMS (ESI): m/z [M + H]+ calcd for C72H74Br4N6O4: 1407.2537; found:
1407.2553.
UV/Vis (THF): λmax (ε) = 392 (3.0·104), 624 nm (3.5·104 M–1 cm–1).
Method B: To a solution of N,N′-dibutylperylene-3,4,9,10-tetracarbox-
ylic acid diimide (2; 1.9 g, 3.78 mmol, 1.0 equiv) in concd H2SO4 (60
mL) was added NBS (4.1 g, 22.7 mmol, 6.0 equiv) in 3 equal portions
during 2 h. After stirring at r.t. for an additional 2 h, the mixture was
heated at 70 °C overnight, poured onto ice (0.4 kg), and filtered. The
precipitate was washed with copious amount of H2O and dried at 80
°C. The above crude mixture of brominated products was dissolved in
THF (60 mL) and hydrazine hydrate (3.78 g, 20 equiv) was added. The
mixture was stirred at r.t. for 1.5 h and diluted with 10% aq HCl (v/v)
solution. THF was removed under reduced pressure, the dark red-
black precipitate was filtered, and washed with H2O. After drying un-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–G

F
A. Jozeliūnaitė et al.
Paper
Synthesis
der reduced pressure, the solid was filtered through a short column of
silica gel and washed with CHCl3 (Rf = 0.76); yield: 0.93 g [68% (78%
for 0.5 g scale)]; red solid; mp 0,>300 °C.
HRMS (ESI): m/z [M + H]+ calcd for C38H18Br4N2O4: 886.8036; found:
886.8040.
Spectral and analytical data were in agreement with literature val-
ues.17
Supporting Information
Supporting information for this article is available online at
N,N′-Dibutyl-1,6,7,12-tetrabromo-2,5,8,11-tetra(4-methoxythio-
phenyl)perylene-3,4,9,10-tetracarboxylic Acid Diimide (10)
https://doi.org/10.1055/s-0036-1589088.
S
u
p
p
ortiInfogrmoaitn
S
u
p
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o
nrtogI
f
rmoaitn
To a solution of 3a (30 mg, 0.027 mmol, 1.0 equiv) in anhyd THF (5.0
mL) was added PhSO2SNa (51.9 mg, 0.27 mmol, 10 equiv) under ar-
gon. The mixture was stirred overnight at r.t. The solvent was evapo-
rated and the residue was suspended in CH2Cl2 and filtered. The fil-
trate was evaporated under reduced pressure and the residue (41 mg)
was re-dissolved in anhyd THF (4.0 mL). The resulting magenta solu-
tion was cooled to –30 °C and 4-methoxyphenylmagnesium bromide
(0.5 M in THF, 0.33 mL, 0.163 mmol, 6.0 equiv) was added. After 2 h,
the mixture was warmed to r.t., stirred overnight, and quenched with
H2O. The mixture was extracted with CH2Cl2. The organic phase was
washed with H2O and dried (Na2SO4). After filtration, the solvent was
removed under reduced pressure and the residue was purified by
flash chromatography [CH2Cl2 (Rf = 0.52) to CH2Cl2–MeOH, 50:1] to af-
ford 10.
References
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Note: Although TLC indicated an Rf value of 0.52 for 10, using CH2Cl2
as an eluent, the majority of the compound stuck to SiO2 in the col-
umn for unknown reasons and much more polar solvent system
(CH2Cl2–MeOH, 50:1) was necessary to wash it out; yield: 30 mg (83%
over two steps); violet solid; mp 207 °C.
IR (neat): 1697 (C=O), 1660 cm–1 (C=O).
1H NMR (400 MHz, CDCl3): δ = 7.29–7.19 (m, 20 H), 3.75–3.67 (m, 2
H), 3.33–3.24 (m, 2 H), 1.25–1.08 (m, 8 H), 0.86–0.80 (m, 6 H).
13C NMR (100 MHz, CDCl3): δ = 160.5, 159.5, 147.55, 132.5, 132.2,
131.0, 127.7, 127.2, 126.3, 121.6, 115.0, 55.3, 41.5, 29.7, 20.2, 13.5.
HRMS (ESI): m/z [M + H]+ calcd for C60H46Br4N2O8S4: 1371.8990;
found: 1371.8988.
UV/Vis (THF): λmax (ε) = 508 (1.6·104), 558 nm (3.3·104 M–1 cm–1).
N,N′-Dibenzyl-1,6,7,12-tetrabromoperylene-3,4,9,10-tetracarbox-
ylic Acid Diimide (11)
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To a suspension of perylene-3,4,9,10-tetracarboxylic acid dianhydride
(1; 146 mg, 0.37 mmol, 1.0 equiv) in concd H2SO4 (25 mL) was added
NBS (397 mg, 2.23 mmol, 6.0 equiv) in 3 equal portions over 1 h. The
mixture was stirred at 70 °C overnight, poured onto ice, and filtered.
After drying at 80 °C, the crude product was dissolved in anhyd CH2-
Cl2 (3.0 mL) followed by the addition of benzylamine (80 mg, 0.74
mmol). The mixture was refluxed overnight, then PBr3 (80 mg, 0.29
mmol) was added and the reflux was continued for 1.5 h. The mixture
was diluted with H2O and extracted with CH2Cl2. After evaporation of
the solvent, the crude product was purified by flash chromatography
(nonpolar red spots on TLC with Rf >0.5). Next, the mixture obtained
was dissolved in THF and hydrazine hydrate (0.119 g, 2.37 mmol) was
added. After 1.5 h, the reaction mixture was evaporated and the resi-
due was purified by flash chromatography (CH2Cl2, Rf = 0.72) to afford
11; yield: 132 mg (40%); red solid; mp >300 °C.
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IR (neat): 1701 (C=O), 1656 cm–1 (C=O).
1H NMR (400 MHz, CDCl3): δ = 8.86 (s, 4 H), 7.61–7.55 (m, 4 H), 7.38–
7.30 (m, 6 H), 5.43 (s, 4 H, CH2Ph).
13C NMR (100 MHz, CDCl3): δ = 162.2, 136.6, 136.3, 131.8, 131.4,
129.2, 128.6, 127.9, 124.0, 123.96, 122.6, 44.0.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–G

G
A. Jozeliūnaitė et al.
Paper
Synthesis
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–G