Fluorofluorescent Perylene Bisimides

Article abstract of DOI:10.1055/s-0037-1610224

Perfluorinated liquids can exhibit immiscibility with organic solvents and water, and provide orthogonal opportunities in chemistry. Examples of emissive dyes that display only fluorous phase solubility are limited, despite the many potential applications. Perylene bisimides are among the most versatile dyes and are known for their outstanding stability and high quantum yields. Herein, we report the synthesis of two new fluorofluorescent perylene bisimide dyes, designed to be soluble in the fluorous phases. These two dyes possess unique photophysical properties, including dramatic increases in fluorescence quantum yields when treated with Bronsted acids as well as aggregation in the fluorous phase.

Full text of DOI:10.1055/s-0037-1610224

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© Georg Thieme Verlag Stuttgart · New York
2018, 29, A–F
cluster
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K. Yoshinaga, T. M. Swager
Cluster
Synlett
Fluorofluorescent Perylene Bisimides
Kosuke Yoshinaga
Timothy M. Swager*
Department of Chemistry, Massachusetts Institute of Technolo-
gy, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
tswager@mit.edu
Published as part of the Cluster Synthesis of Materials
Received: 09.06.2018
Accepted after revision: 05.07.2018
Fluorous solubility depends mainly on the fluorine con-
tent of the molecule, typically requiring >50 weight percent
fluorine (wt% F) and extended perfluoroalkyl chains.1 Ex-
amples of dyes that exhibit fluorous solubility are extreme-
ly limited.10 To address this shortage, our group has previ-
ously synthesized fluorous soluble conjugated polymers,11
as well as an array of “fluorofluorophores”, in which “fluo-
ro” refers to both fluorescence and fluorination.12 However,
to date only a small parameter space has been explored and
there are vast uncharted territories of electronic molecules
to be discovered.
We targeted perylene bisimides (PBIs) as a result of
their wide utility as organic semiconductors,13 supramolec-
ular building blocks,14 and fluorophores.15 Previous exam-
ples to incorporate fluorinated groups in PBIs have been
demonstrated to show utility as air-stable n-type semicon-
ductors;6c–d,16 however, the fluorine content of these exam-
ples were <50 wt% F. Examples of PBIs with higher wt% F
have been reported to self-assemble into ordering struc-
tures.17 However, their fluorous solubilities as well as pho-
tophysical properties of the fluorinated molecules were not
studied in detail.
Herein, we disclose two synthetic approaches to obtain
fluorofluorescent PBI dyes FF-PBI-1 and FF-PBI-2, both re-
quiring only four facile steps from a common starting mate-
rial (Figure 1). FF-PBI-1, which possesses 54 wt% F, initially
shows moderate solubility in both organic and fluorous sol-
vents, but the solubility in fluorous solvents is improved
upon addition of a Brønsted acid. On the other hand, FF-
PBI-2, which possesses 56 wt% F, shows good solubility in
both organic and fluorous solvents. The photophysical
properties of the two FF-PBIs are also distinctly unique; FF-
PBI-1 shows a response to acidity, whereas FF-PBI-2 shows
concentration dependence.
Published online: 31.07.2018
DOI: 10.1055/s-0037-1610224; Art ID: st-2018-r0553-c
Abstract Perfluorinated liquids can exhibit immiscibility with organic
solvents and water, and provide orthogonal opportunities in chemistry.
Examples of emissive dyes that display only fluorous phase solubility are
limited, despite the many potential applications. Perylene bisimides are
among the most versatile dyes and are known for their outstanding sta-
bility and high quantum yields. Herein, we report the synthesis of two
new “fluorofluorescent” perylene bisimide dyes, designed to be soluble
in the fluorous phases. These two dyes possess unique photophysical
properties, including dramatic increases in fluorescence quantum yields
when treated with Brønsted acids as well as aggregation in the fluorous
phase.
Key words perylene bisimides, fluorines, Heck reaction, fluorescence,
aggregation
The “fluorous” phase, which consists of perfluorinated
alkanes, ethers, or amines, has found unique opportunities
in chemistry as a result of the ability to phase-separate
from polar and nonpolar phases.1 The term “fluorous” was
coined by Horváth and Rábai in 1994, when they demon-
strated the utility of fluorous biphasic catalysis.2 Fluorous
molecules tend to exhibit improved photochemical, ther-
mal, and chemical stability than their hydrocarbon coun-
terpart.3 Fluorous compounds have deserved popularity in
applications4 such as in coating materials,5 organic elec-
tronics,6 perfluorocarbon nanoemulsions for in vivo drug
delivery7 and cell tracking,8 and fluorescent recognition in
the fluorous phase.9 These examples represent only a few
unique highlights of the fluorous phase and new discover-
ies will be enabled by access to an expanded portfolio of
fluorous materials.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

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K. Yoshinaga, T. M. Swager
Cluster
Synlett
F17C8
C8F17
F17C8
C8F17
O
N
O
O
N
O
F17C8
N
N
C8F17
F
F
O
O
O
O
C8F17
C8F17
O
O
O
O
17C8
17C8
F17C8
N
N
C8F17
O
N
O
O
N
O
F17C8
C8F17
F17C8
C8F17
FF-PBI-1
54 wt% F
FF-PBI-2
56 wt% F
Figure 1 Chemical structures of fluorofluorescent PBIs in this report
The synthesis of FF-PBI-1 is shown in Scheme 1. Fluoro-
alkylated aminophenol 1, compound 3, and compound 4
were prepared according to previous reports.12,17b,18 An SNAr
reaction of 4 and 1 produced the target perylene bisimide
FF-PBI-1 in 25% isolated yield.19 The product was purified
by chromatography on silica gel, but its poor solubility in
most solvents presumably led to the low yield.19,20 FF-PBI-1
1
was fully characterized by H, 19F nuclear magnetic reso-
nance (NMR) spectroscopy, matrix-assisted laser desorp-
tion/ionization time-of-flight mass spectrometry (MALDI
TOF-MS), and elemental analysis.
We sought to gain a better understanding of the solubil-
ity of FF-PBI-1, which showed moderate solubility (~1.0 mg
mL–1; ~2.1×102 M) in organic solvents such as dichloro-
methane (CH2Cl2) (Figure 2, a), toluene, chloroform, ace-
tone, and ethyl acetate. Interestingly, when C6F14 was added
to a solution of FF-PBI-1 in CH2Cl2, we visually observed the
partition of FF-PBI-1 in both CH2Cl2 and C6F14 layers (Figure
2, a, b). Despite the high wt% F, FF-PBI-1 was insoluble in
pure fluorous solvents such as perfluorohexanes (C6F14)
(Figure 2, d), as well as perfluorodecalin.
Figure 2 Demonstration of solubility of FF-PBI-1 and its response to TFA
under ambient light (left) and UV light (right, ex = 365 nm). (a) Photo-
graphs of FF-PBI-1 (0.5 mg) in CH2Cl2 (0.5 mL), (b) after adding C6F14
(0.5 mL), and (c) after adding TFA. (d) Photographs of the heterogeneous
mixture of FF-PBI-1 (1.0 mg) and C6F14 (1.0 mL) and (e) the sample af-
ter adding TFA
F17C8
C8F17
HO
C8F17
N
O
O
O
O
O
O
O
N
O
O
N
O
NH2
F17C8
N
N
C8F17
C8F17
1
ClSO3H
I2
K2CO3
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
O
O
O
O
DMF
120 °C, 24 h
25% yield
65 °C, 20 h
98% yield
EtCO2H
reflux, 24 h
69% yield
F17C8
N
N
C8F17
O
O
2
O
O
O
3
O
O
N
4
O
O
N
O
F17C8
C8F17
FF-PBI-1
54 wt% F
Scheme 1 Synthesis of FF-PBI-1
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

C
K. Yoshinaga, T. M. Swager
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To our surprise, we found that addition of a Brønsted
acid improved the solubility of FF-PBI-1 in fluorous sol-
vents. For instance, when trifluoroacetic acid (TFA) was
added to the solution of FF-PBI-1 in a CH2Cl2/C6F14 mixture,
the color of the CH2Cl2 layer turns from turbid purple to col-
orless transparent, while that of the C6F14 layer turns from
turbid purple to a brilliant fluorescent red (Figure 2, c).
When TFA was added to the heterogeneous mixture of FF-
PBI-1 (1.0 mg) and C6F14 (1.0 mL), the mixture became ho-
mogeneously red and fluorescent, thereby confirming that
this effect is not dependent on the organic solvent (Figure 2,
d, e). Other Brønsted acids such as hydrochloric acid and
perfluorononanoic acid also showed a similar phenome-
non. FF-PBI-1’s fluorescence was also increased upon pro-
tonation with these other acids and it also exhibits prefer-
ential solubility for fluorous solvents over organic solvents
under acidic conditions.
hanced intensity (Figure 3, b). The concentration of TFA
plotted against the fluorescence intensity at 584 nm (Figure
3, b, inset) gives a sigmoidal shape. We observe a saturation
of fluorescence intensity when the concentration of TFA
was increased to ~9 mM. The quantum yield of FF-PBI-1 in
CH2Cl2 increased from 6.1 to 54% upon excess addition of
TFA (Table 1). The quantum yield of FF-PBI-1 in C6F14 with
excess TFA was 76%. The red-shifted spectra and higher
quantum yields in fluorous phases confirm the benefits of
the fluorous environments (also see Figure S1 in the Sup-
porting Information).
Table 1 Photophysical Properties of FF-PBI-1 in CH2Cl2 and C6F14 (+
TFA)
Solvent
max(Abs) (nm)
max(Em) (nm)
ΦF (%)
CH2Cl2
584
549
562
616b
584c
594c
6.1
54
76
We further investigated the photophysical properties of
FF-PBI-1 in CH2Cl2 (2.1 M) by monitoring the absorbance
and fluorescence and the changes upon addition of TFA. The
absorbance spectra showed a gradual hypsochromic shift
(Figure 3, a), and the fluorescence spectra showed an en-
CH2Cl2 + TFAa
C6F14 + TFAa
a Excess TFA was added to the sample.
b ex = 570 nm.
c ex = 500 nm.
We attribute the initial fluorescence quenching of FF-
PBI-1 to photo-induced electron transfer (PET) from the pe-
ripheral lone pairs of the nitrogen on the aminophenolic
groups.21 Upon addition of acid, PET is attenuated as a result
of protonation of the aminophenolic group. This protona-
tion also likely causes the absorbance to shift to a shorter
wavelength, because the HOMO of FF-PBI-1 is also lowered
with the decreased electron donation by the protonated
pendant aminophenolic groups. The proton-induced photo-
physical change in FF-PBI-1 is also reversible. Addition of
triethylamine to the acidic sample reestablishes the original
absorbance and fluorescence spectra (Figure S2).
Although the protonation of FF-PBI-1 led to interesting
properties such as improved fluorous solubility and fluo-
rescence, we also embarked on the study of alternative
structures of PBIs with high wt% F and that lack basic nitro-
gens. Beginning with intermediate 4, we synthesized octa-
brominated PBI 5 via an SNAr reaction with 3,5-dibro-
mophenol in 68% yield (Scheme 2). We targeted compound
5 as a useful intermediate for subsequent metal-catalyzed
cross-coupling reactions. Indeed, compound 5 successfully
underwent an eight-fold Herrmann’s palladacycle-cata-
lyzed Heck reaction22 between 1H,1H,2H-perfluoro-1-de-
cene to smoothly provide the desired product FF-PBI-2 in
43% yield.23,24 FF-PBI-2 was fully characterized by 1H, COSY,
19F NMR spectroscopy, MALDI TOF-MS, and elemental anal-
ysis. This efficient eight-fold reaction produces only the
trans-alkene product, which is readily isolated in pure form.
In contrast to FF-PBI-1, FF-PBI-2 showed good solubili-
ty (>1.0 mg mL–1; >2.2×102 M) in common organic sol-
vents such as CH2Cl2, toluene, chloroform, acetone, and ethyl
Figure 3 Photophysical properties of FF-PBI-1. (a) Absorbance spectra
and (b) relative fluorescence spectra (ex = 500 nm) of FF-PBI-1 in CH2Cl2
at different concentrations of TFA. Inset: Fluorescence intensity at
584 nm at different concentrations of TFA. Black arrows indicate spec-
tral change with increasing concentration of TFA.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

D
K. Yoshinaga, T. M. Swager
Cluster
Synlett
Br
O
N
O
F17C8
C8F17
O
N
O
Br
Br
HO
O
N
O
C8F17
NaOAc
Br
K2CO3
NMP
Pd cat.
Br
Br
O
O
O
O
Br
Br
Cl
Cl
Cl
Cl
O
O
O
O
C8F17
C8F17
17
17
8
8
DMF
125 °C, 24 h
43% yield
100 °C, 7 h
68% yield
Br
Br
O
N
5
O
Pd cat.:
O
N
4
O
O
N
O
F17C8
C8F17
O
O
P
P
Pd
Pd
FF-PBI-2
56 wt% F
O
O
Scheme 2 Synthesis of FF-PBI-2
acetate. Intriguingly, FF-PBI-2 also showed good solubility
in perfluoroalkanes such as C6F14 and perfluorodecalin.
When C6F14 was added to a solution of FF-PBI-2 in CH2Cl2,
we observed the extraction of FF-PBI-2 into the C6F14 layer
(Figure 4). This result illustrates that FF-PBI-2 has a higher
preference towards fluorous solvents over organic solvents.
ure 5, c). In the fluorescence spectra, the peak at 595 nm
simply gradually enhanced in intensity (Figure 5, d). This
suggests that the aggregation is exclusively observed in flu-
orous solvents. Recently, Cao and Sletten reported the first
cyanine dye showing aggregation in the fluorous phase;26
however, they utilize 1% CH2Cl2 and a mixture of methoxy-
and ethoxynonafluorobutane as their solvent system.
Therefore, FF-PBI-2 presents a unique entry of aggregation
in pure perfluorinated solvents.
Figure 4 Photographs of FF-PBI-2 under ambient light (left) and UV
light (right, ex = 365 nm). (a) Photographs of FF-PBI-2 (0.5 mg) in CH2-
Cl2 (0.5 mL). (b) Photographs of the sample after adding C6F14 (0.5 mL)
FF-PBI-2 exhibited concentration-dependent photo-
physical properties in C6F14. Figure 5, a shows the absor-
bance spectra of FF-PBI-2 at different concentrations. A
peak at 525 nm was observed in the dilute solution. Howev-
er, a large bathochromic peak at 567 nm develops in con-
centrated solutions, which is characteristic of J-aggregate
formation.25 In the fluorescence spectra, in addition to the
peak at 558 nm, a large bathochromic peak at 595 nm was
observed when the concentration of the solution was in-
creased (Figure 5, b). The quantum yields of FF-PBI-2 in
C6F14 at different concentrations were maintained near 75%
(Figure S3). The red-shifted spectra, increase in the molar
absorptivity, and the increased quantum yield for emission
all support a J-aggregate formation. Similar measurements
of FF-PBI-2 in CH2Cl2 showed a completely different trend.
In the absorbance spectra, no new peaks were observed
when the concentration of the solution was increased (Fig-
Figure 5 Photophysical properties of FF-PBI-2 in C6F14 and CH2Cl2. (a)
Absorbance spectra and (b) relative fluorescence spectra (ex = 500 nm)
of samples at different concentrations in C6F14. (c) Absorbance spectra
and (d) relative fluorescence spectra (ex = 500 nm) of samples at differ-
ent concentrations in CH2Cl2. Black arrows indicate spectral change
with increasing concentration.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

E
K. Yoshinaga, T. M. Swager
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In conclusion, we have disclosed two synthetic methods
to obtain fluorofluorescent perylene bisimides. FF-PBI-1
only showed moderate solubility in both organic and fluo-
rous solvents, but the solubility could be improved upon
addition of Brønsted acid. On the other hand, FF-PBI-2
showed useful solubility in both organic and fluorous sol-
vents. Titration measurements of FF-PBI-1 and concentra-
tion-dependent measurements of FF-PBI-2 demonstrate
the interesting and potentially useful photophysical prop-
erties of the fluorofluorescent PBIs. We envision these
properties will provide promising applications in the fluo-
rous phase, including the incorporation of fluorofluorescent
PBIs in the fluorous phase of dynamic complex emulsions.27
(10) Kim, S. H. Functional Dyes; Elsevier: Amsterdam, 2006.
(11) (a) Lim, J.; Swager, T. M. Angew. Chem. Int. Ed. 2010, 49, 7486. (b)
Takeda, Y.; Andrew, T. L.; Lobez, J. M.; Mork, A. J.; Swager, T. M.
Angew. Chem. Int. Ed. 2012, 51, 9042.
(12) Sletten, E. M.; Swager, T. M. J. Am. Chem. Soc. 2014, 136, 13574.
(13) Feng, J.; Jiang, W.; Wang, Z. Chem. Asian J. 2018, 13, 20.
(14) Würthner, F.; Saha-Möller, C. R.; Fimmel, B.; Ogi, S.;
Leowanawat, P.; Schmidt, D. Chem. Rev. 2016, 116, 962.
(15) Chen, L.; Li, C.; Müllen, K. J. Mater. Chem. C 2014, 2, 1938.
(16) (a) Würthner, F.; Osswald, P.; Schmidt, R.; Kaiser, T. E.;
Mansikkamäki, H.; Könemann, M. Org. Lett. 2006, 8, 3765. (b) Li,
Y.; Tan, L.; Wang, Z.; Qian, H.; Shi, Y.; Hu, W. Org. Lett. 2008, 10,
529. (c) Yuan, Z.; Li, J.; Xiao, Y.; Li, Z.; Qian, X. J. Org. Chem. 2010,
75, 3007. (d) Ren, H.; Li, J.; Wang, R.; Wang, Q.; Liu, D. Synth.
Commun. 2010, 40, 759.
(17) (a) De Luca, G.; Liscio, A.; Melucci, M.; Schnitzler, T.; Pisula, W.;
Clark, C. G.; Scolaro, L. M.; Palermo, V.; Müllen, K.; Samorì, P.
J. Mater. Chem. 2010, 20, 71. (b) Partridge, B. E.; Leowanawat, P.;
Aqad, E.; Imam, M. R.; Sun, H. J.; Peterca, M.; Heiney, P. A.; Graf,
R.; Spiess, H. W.; Zeng, X.; Ungar, G.; Percec, V. J. Am. Chem. Soc.
2015, 137, 5210.
Funding Information
Financial support from the Air Force Office of Scientific Research is
greatly appreciated. K.Y. thanks Funai Overseas Scholarship for finan-
cial support.
)(
(18) Qian, H.; Liu, C.; Wang, Z.; Zhu, D. Chem. Commun. 2006, 4587.
(19) Synthesis of FF-PBI-1
A mixture of compound 4 (0.150 g, 0.176 mmol), compound 1
(1.04 g, 1.01 mmol), and anhydrous K2CO3 (0.123 g, 0.892
mmol) in anhydrous N,N-dimethylformamide (DMF) (6 mL) was
stirred at 120 °C under Ar for 24 h. Then, the reaction was
cooled to r.t. The precipitated product was filtered under suc-
tion, washed with water (3×100 mL), and dried under vacuum.
The residue was chromatographed on silica gel by using hex-
anes/CH2Cl2 (2:1 v/v) as an eluent, and the fraction containing
FF-PBI-1 (Rf = 0.50) was collected and evaporated to dryness to
provide a purple solid (0.212 g, 0.0440 mmol, 25%). 1H NMR
(500 MHz, CD2Cl2, 25 °C):  = 8.20 (s, 4 H), 7.46 (t, J = 7.5 Hz, 2 H),
7.29 (d, J = 8.0 Hz, 4 H), 7.17 (t, J = 8.0 Hz, 4 H), 6.47 (d, J = 8.0 Hz,
4 H), 6.39 (d, J = 8.0 Hz, 4 H), 6.33 (s, 4 H), 3.21 (d, J = 6.5 Hz, 16
H), 2.67 (sept, J = 7.0 Hz, 4 H), 1.96–2.10 (m, 16 H), 1.72–1.83
(m, 16 H), 1.06 (d, J = 6.5 Hz, 24 H) ppm. 19F NMR (470 MHz,
CD2Cl2, 25 °C):  = –82.00 (t, 9.4 Hz, 24 F), –114.84 (br, 16 F),
–122.84 (br, 16 F), –123.02 (br, 32 F), –123.81 (br, 16 F), –124.47
(br, 16 F), –127.24 (br, 16 F) ppm. MALDI-TOF MS: m/z calcd for
Acknowledgment
We thank Dr. Maggie He and Dr. Che-Jen Lin for helpful discussions
while preparing this manuscript.
Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/s-0037-1610224.
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References and Notes
(1) Gladysz, J. A.; Curran, D. P.; Horváth, I. T. Handbook of Fluorous
Chemistry; Wiley-VCH: Weinheim, 2004.
(2) Horváth, I. T.; Rábai, R. Science 1994, 266, 72.
(3) Sun, H.; Putta, A.; Kloster, J. P.; Tottempudi, U. K. Chem.
Commun. 2012, 48, 12085.
C
160H102F136N6O8 [M + H]+: 4819.5678; found: 4819.80. Anal.
(4) Vincent, J. M. Chem. Commun. 2012, 48, 11382.
(5) Anton, D. Adv. Mater. 1998, 10, 1197.
Calcd for C160H102F136N6O8: C, 39.87; H, 2.13; N, 1.74. Found: C,
39.35; H, 2.08; N, 1.65.
(6) (a) Chikamatsu, M.; Itakura, A.; Yoshida, Y.; Azumi, R.; Yase, K.
Chem. Mater. 2008, 20, 7365. (b) Lee, J.-K.; Fong, H. H.; Zakhidov,
A. A.; McCluskey, G. E.; Taylor, P. G.; Santiago-Berrios, M.;
Abruña, H. D.; Holmes, A. B.; Malliaras, G. G.; Ober, C. K. Macro-
molecules 2010, 43, 1195. (c) Schmidt, R.; Ling, M. M.; Oh, J. H.;
Winkler, M.; Konemann, M.; Bao, Z.; Würthner, F. Adv. Mater.
2007, 19, 3692. (d) Schmidt, R.; Oh, J. H.; Sun, Y.-S.; Deppisch,
M.; Krause, A.-M.; Radacki, K.; Braunschweig, H.; Könemann,
M.; Erk, P.; Bao, Z.; Würthner, F. J. Am. Chem. Soc. 2009, 131,
6215.
(20) The yield may be further improved through the use of fluorous
silica gel. Curran, D. P. Synlett 2001, 1488.
(21) (a) Van, P. S.; Hammond, G. S. J. Am. Chem. Soc. 1978, 100, 3895.
(b) Che, Y.; Yang, X.; Loser, S.; Zang, L. Nano Lett. 2008, 8, 2219.
(c) Che, Y.; Zang, L. Chem. Commun. 2009, 5106. (d) Liu, Y.;
Wang, K. R.; Guo, D. S.; Jiang, B. P. Adv. Funct. Mater. 2009, 19,
2230. (e) Peng, H.; Ding, L.; Liu, T.; Chen, X.; Li, L.; Yin, S.; Fang,
Y. Chem. Asian J. 2012, 7, 1576. (f) Sriramulu, D.; Valiyaveettil, S.
Dyes Pigm. 2016, 134, 306.
(22) Herrmann, W. A.; Brossmer, C.; Reisinger, C. P.; Riermeier, T. H.;
Ofele, K.; Beller, M. Chem. Eur. J. 1997, 3, 1357.
(23) Chen, W.; Xu, L.; Hu, Y.; Osuna, A. M. B.; Xiao, J. Tetrahedron
2002, 58, 3889.
(7) Zhang, T.; Zhang, Q.; Tian, J.-H.; Xing, J.-F.; Guo, W.; Liang, X.-J.
MRS Commun. 2018, 8, 303.
(8) Janjic, J. M.; Ahrens, E. T. WIREs Nanomed. Nanobiotechnol. 2009,
1, 492.
(24) Synthesis of FF-PBI-2
(9) (a) El Bakkari, M.; Fronton, B.; Luguya, R.; Vincent, J.-M. J. Fluo-
rine Chem. 2006, 127, 558. (b) Wang, C.; Wu, E.; Wu, X.; Xu, X.;
Zhang, G.; Pu, L. J. Am. Chem. Soc. 2015, 137, 3747. (c) Shi, D.;
Wang, X.; Yu, S.; Zhao, F.; Wang, Y.; Tian, J.; Hu, L.; Yu, X.; Pu, L.
Eur. J. Org. Chem. 2018, 1053.
A mixture of compound 5 (0.439 g, 0.257 mmol), 1H,1H,2H-per-
fluoro-1-decene (1.44 g, 3.23 mmol), NaOAc (0.256 g, 3.04
mmol), and anhydrous DMF (5 mL) was treated with three
freeze-pump-thaw cycles. Then, Herrmann’s catalyst (50.2 mg,
0.0535 mmol) was added to the mixture and it was stirred for
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F

F
K. Yoshinaga, T. M. Swager
Cluster
Synlett
24 h at 125 °C. Upon cooling the reaction mixture to r.t., the
residue was dissolved in AcOEt (100 mL) and HCl (1 M, 100 mL).
The organic layer was separated, washed with water (3×100 mL)
and brine (100 mL), dried with MgSO4, and evaporated to
dryness under reduced pressure. The residue was chromato-
graphed on silica gel by using CHCl3 as an eluent, and the frac-
tion containing FF-PBI-2 (Rf = 0.50) was collected and evapo-
rated to dryness to provide a pink-red solid (0.517 g, 0.112
mmol, 43%). 1H NMR (500 MHz, CD2Cl2, 25 °C):  = 8.31 (s, 4 H),
7.47 (t, J = 7.5 Hz, 2 H), 7.30–7.31 (m, 8 H), 7.03–7.06 (m, 16 H),
5.98–6.06 (m, 8 H), 2.67 (sept, 7.0 Hz, 4 H), 1.07 (d, 7.0 Hz, 24 H)
ppm. 19F NMR (470 MHz, CD2Cl2, 25 °C, ,,-trifluorotoluene
was added as an internal standard and was referenced to –63.72
ppm):  = –81.98 (t, 9.9 Hz, 24 F), –112.78 (br, 16 F), –122.52 (br,
16 F), –22.99 (br, 32 F), –123.80 (br, 16 F), –123.96 (br, 16 F),
–127.22 (br, 16 F) ppm. MALDI-TOF MS: m/z calcd for
C
C
152H66F136N2O8: 4630.2648; found: 4630.13. Anal. Calcd for
152H66F136N2O8: C, 39.41; H, 1.44; N, 0.60. Found: C, 39.40; H,
1.33; N, 0.60.
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© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–F