Corroles bearing diverse coumarin units - Synthesis and optical properties

Article abstract of DOI:10.1142/S1088424611003926

Two strategies were shown to be efficient in the construction of corroles with appended coumarin units. Direct condensation of formyl-coumarins with dipyrromethanes leads to a diverse range of trans-A₂B-corroles in moderate yields. We showed th

Full text of DOI:10.1142/S1088424611003926

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2011; 15: 1011–1023
DOI: 10.1142/S1088424611003926
Published at http://www.worldscinet.com/jpp/
Corroles bearing diverse coumarin units — synthesis and
optical properties
Mariusz Tasiora, Roman Voloshchuka, Yevgen M. Poronika, Tomasz Rowickib and
Daniel T. Gryko*a,b
a Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
b Warsaw University of Technology, Faculty of Chemistry, Noakowskiego, 00-664 Warsaw, Poland
Dedicated to Professor Karl M. Kadish on the occasion of his 65th birthday
Received 5 May 2011
Accepted 30 June 2011
ABSTRACT: Two strategies were shown to be efficient in the construction of corroles with appended
coumarin units. Direct condensation of formyl-coumarins with dipyrromethanes leads to a diverse range
of trans-A2B-corroles in moderate yields. We showed that the strategy consisting of synthesis of various
hydroxycoumarins followed by nucleophilic aromatic substitution with pentafluorobenzaldehyde and
subsequent condensation of the resulting coumarin-aldehyde with dipyrromethanes is the most general
methodology for the preparation of such dyads. The second, more demanding but also more efficient
approach is based on Sonogashira coupling of ethynylphenylcorroles with suitably functionalized
bromocoumarins. A broad range of structurally diverse coumarins were employed with absorption
ranging from 300 to 460 nm. Spectroscopic properties of all eight dyads studied suggest that the linker
components are weakly electronically coupled.
KEYWORDS: corroles, coumarin, synthesis, fluorescence, dipyrromethanes.
recently begun to emerge [6]. Their coordination chem-
INTRODUCTION
istry, ring-functionalization and biomedical applications
Corroles, one carbon shorter analogs of porphyrins,
have been the most active areas of research in recent years
emerged a few years ago as an independent area of
[7–9]. In spite of these new applications, corroles con-
research [1]. First reported in 1965 [2], they possess the
tinue to be a synthetic challenge. Although in many cases
skeleton of corrin (macrocycle found in vitamin B12) with
three meso-carbons between the four pyrrole rings. Recent
both the synthesis of meso-substituted corroles, as well
as their derivatisation have been developed to a useful
synthetic breakthroughs have made these macrocycles
level, more complex cases are still problematic. In par-
readily available [3]. When compared with porphyrins,
ticular, in [2+1] condensation between dipyrromethanes
these tribasic aromatic macrocycles exhibit interest-
and aldehydes, more complex structures have proven
ing properties including lower oxidation potentials [4],
to be difficult to assemble due to the specific reactivity
higher fluorescence quantum yields, larger Stokes shift,
and/or poor solubility of these building blocks [10]. Still,
and more intense absorption of red light [5]. Although
this methodology is undoubtedly the most general one to
less stable compared to analogous porphyrins, assemblies
prepare a variety of complex corroles [6]. As a part of a
of appropriately functionalised corroles with other redox-
broader program in the chemistry of corrole-containing
and photo-active moieties for different applications have
assemblies, we aimed to synthesize a library of cova-
lently linked corrole-coumarin dyads. Coumarins as the
counterpart were chosen due to their excellent and well-
SPP full member in good standing
documented photochemical and photophysical behavior
[11]. Coumarin dyes, owing to their intense fluorescence,
*Correspondence to: Daniel T. Gryko, email: daniel.gryko@
icho.edu.pl, tel: +48 (22)-3433063, fax: +48 (22)-6326681
Copyright © 2011 World Scientific Publishing Company

1012 M. TaSIOr et al.
have attracted considerable interest as laser dyes [12], as
emitter layers in OLEDs [13], and as optical brighten-
ers [14]. The structure-property relationship of coumarin
derivatives has recently been studied in detail [15–17], but
only few reports have been published on the photophysi-
cal properties of coumarin-porphyrinoid conjugates [18].
The idea of combining corroles and coumarins in one
molecule is very attractive, and our previous report on
this topic demonstrated that efficient energy transfer
occurred between coumarin and corroles in such dyads
[19]. Further progress in this area has been hindered
due to increasing difficulties associated with the synthe-
sis of such compounds. In this manuscript, we present
recent advances and new strategies for the synthesis of
coumarin-corroles with variable structure.
for laborious functionalization) and (b) corroles bearing
tetrafluoroalkoxysubstituent at the meso-position should
have higher oxidation potential, hence greater stability
against light and oxygen.
Attempts to synthesize coumarin-derived aldehydes
and transform them into corroles were initiated by the
preparation of benzo[c]coumarin 1 synthesized using
the Hurtley methodology [21], which was subsequently
transformed into an aldehyde using conditions developed
by us for selective nucleophilic substitution of pentafluo-
robenzaldehyde (2) by phenols [26]. The reaction went
smoothly under standard conditions affording aldehyde
3 in 86% yield (Scheme 1). Reaction of this aldehyde
with 5-(pentafluorophenyl)dipyrromethane (4) under
conditions previously optimized for electron-deficient
dipyrromethanes [27] afforded corrole 5 (Scheme 1). The
yield was disappointingly low (6%) in spite of the fact
that coumarin 3 does not possess a reactive, polarized
carbon–carbon double bond which could act as a Michael
RESULTS AND DISCUSSION
Design and synthesis
CHO
Trans-A2B-corroles bearing
a coumarin moiety
F
F
F
F
attached to the meso-10-position of corrole were cho-
sen for our studies. This suitable structure benefits from
efficient, general synthetic procedures developed in the
last 10 years. We focused our investigation mainly on
π-expanded coumarins which are able to absorb green
light. Two pentafluorophenyl units were intended to be
introduced at positions 5 and 15 since they secure good
photostability of the corrole core for photophysical char-
acterization [6]. The pentafluorophenyl group appeared to
be the best choice due to the strong electron-withdrawing
effect, imparting high solubility, lack of interference
with spectroscopic properties and susceptibility to fur-
ther transformations. Among many ways to achieve
π-expansion of coumarin’s chromophore, we focused on
selected types which in our opinion provide compounds
possessing interesting photophysical properties. Several
issues merit particular consideration when contemplating
the synthesis of complex corroles. From the standpoint
of synthetic efficiency, in analogy to porphyrins, two
general strategies are possible. The first starts with the
synthesis of the corrole followed by modifications of the
peripheral substituents. The second strategy starts with
the preparation of an elaborated aldehyde which can then
be used in the corrole-forming reaction. Given the moder-
ate stability of corroles, it is desirable to gain significant
relief from corrole manipulations. During the attempts to
synthesize these bichromophoric systems, we followed
both approaches.
+
HO
O
O
F
1
2
CsF, 86%
F
OHC
F
F
O
O
O
F
3
F
F
F
F
F
1. TFA, CH2Cl2
2. DDQ, 6%
NH HN
4
O
O
O
F
F
F
F
One of the strategies which we planned to investigate
was the synthesis of modified coumarin possessing a
phenol unit followed by nucleophilic aromatic substitu-
tion of one fluorine atom in pentafluorobenzaldehyde.
The potential advantages of this approach would be as
follows: (a) von Pechmann-type condensation typically
gives rise directly to hydroxycoumarins (without the need
F
F
F
F
F
F
F
NH
N
F
F
NHHN
F
5
Scheme 1.
Copyright © 2011 World Scientific Publishing Company
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COrrOleS bearIng DIverSe COuMarIn unITS — SynTheSIS anD OPTICal PrOPerTIeS 1013
O
O
acceptor in possible side-reactions with the electron-rich
pyrrole moiety.
CN
The main effort of our investigation was focused on
push-pull type structures with strong electron-donating
groups at position 7 and a strong electron-withdrawing
group at position 3. This type of coumarin architecture
usually results in a bathochromic shift of absorption, a
significant Stokes shift, strong fluorescence, and also
the presence of a highly reactive α,β-unsaturated sys-
tem (which can interfere with the Friedel-Crafts reac-
tion of aldehydes with pyrrole derivatives). Coumarin
structures have been modified/expanded to achieve
absorption of blue-green light, which is advantageous
in terms of further utilization models for energy transfer
studies.
6
1. methyl bromoacetate
2. HCl
O
O
O
CO2CH3
7
CHO
OH
pyrrolidine, MeOH
reflux, 60%
Along these lines, our next goal was to synthesize
push-pull formyl-coumarin 10 (Scheme 2). The synthesis
of compound 10 started with the Blaise reaction [28] as
a key step (Scheme 2). The resulting β-ketoester 7 was
subjected to the Knoevenagel reaction with aldehyde 8
which led to closing the ring and the formation of keto-
coumarin 9. The removal of the protecting group, fol-
lowed by condensation with dipyrromethane 4, afforded
corrole 11 in 9% yield (Scheme 2). The presence of a
second reactive carbonyl group in the structure of alde-
hyde 10 probably contributed to this result. This low
yield achieved when the corrole-forming step was per-
formed via condensation of coumarin-derived aldehydes
prompted us to seek alternative ideas for the preparation
of even more complex coumarin-corroles. In order to
avoid this problem, we decided to synthesize coumarins
suitable for Sonogashira coupling. We expected this
strategy to be more flexible and efficient. We designed
two bromocoumarins 13 and 17 as suitable models. Cou-
marin 13 was prepared from aldehyde 12 [23] via a clas-
sical approach (Scheme 3). The synthesis of derivative
17 required the condensation of β-ketoester 16 [24] with
5-bromosalicylaldehyde (Scheme 4). Easily available
corrole 14 [19] was coupled with both bromo-coumarins
13 and 17 under copper-free conditions [29] in order to
prevent metallation of the macrocycle ring. The expected
bichromophoric systems were prepared in yields of 52%
and 55%, respectively (Schemes 3 and 4).
NEt2
8
O
O
O
Et2N
O
O
9
TFA, H2SO4, H2O,
CH2Cl2, 98%
O
Et2N
O
O
CHO
10
1. 4, TFA, DCM
2. DDQ, 9%
NEt2
O
O
O
Another paradigm for π-expansion of coumarins was
based on conjugating another aromatic unit via the carbon–
carbon double bond at position 4. One of the advan-
tages of this strategy is good availability of the required
building blocks (i.e., coumarins bearing a methyl group
at position 4) via the von Pechmann reaction. This, in
turn, combined with access to an almost unlimited num-
ber of aromatic aldehydes, allowed for modular design
of the final compounds. Based on a slightly modified
procedure developed by Tkach et al. [25] for condensa-
tion of aldehydes with 4-methylcoumarins, we prepared
aldehyde 22 which was subsequently condensed with
pentafluorophenyldipyrromethane affording corrole 24
in 17% yield (Scheme 5). The isolated dyad was stable
NH
N
C6F5
C6F5
NHHN
11
Scheme 2.
and easy to purify. Encouraged by this result, we decided
to change the distance between the corrole and coumarin
by introducing an additional phenylene linker. While
the synthesis of analog 23 was quite straightforward, its
Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 1013–1023

1014 M. TaSIOr et al.
CHO
O
O
OH
CO2CH3
Br
Et2N
O
NEt2
16
12
dimethyl malonate
pyrrolidine acetate,
MeOH, reflux, 90%
5-bromosalicaldehyde,
pyrrolidine acetate, MeOH,
reflux, 80%
Br
Et2N
CO2CH3
O
O
O
Br
13
+
Et2N
O
O
O O
17
14, Pd(OAc)2, PPh3
Cs2CO3, DMSO, 55%
NH
N
NEt2
C6F5
C6F5
NHHN
O
O
14
O
Pd(OAc)2, PPh3
Cs2CO3, DMSO, 52%
O
O
O
CO2CH3
O
Et2N
F
F
F
F
F
F
F
NH
N
NH
N
F
F
C6F5
C6F5
NHHN
NHHN
F
18
15
Scheme 4.
Scheme 3.
O
O
NEt2
CHO
CHO
n
1. 4, TFA, DCM
2. DDQ
n
n = 0,1
1. t-BuOK, DMSO
2. AcOH, H2O
+
Et2N
O
O
19
CHO
Et2N
O
O
20: n = 0
21: n = 1
NH
N
22: n = 0, 20%
23: n = 1, 27%
C6F5
C6F5
NHHN
24: n = 0, 17%
25: n = 1, 1.2%
Scheme 5.
Copyright © 2011 World Scientific Publishing Company
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COrrOleS bearIng DIverSe COuMarIn unITS — SynTheSIS anD OPTICal PrOPerTIeS 1015
CF3
compounds are synthesized by the reaction of the appro-
priate aldehyde with coumarinyl-4-acetic acids. We
decided to study ifTkach’s procedure could be applied to
4-methylumbelliferone (26) as well. To our delight, the
reaction with 4-trifluoromethylbenzaldehyde (27) gave
the expected product 28 in moderate yield (Scheme 6).
The resulting phenol 28 was transformed into an alde-
hyde by the reaction with pentafluorobenzaldehyde (2)
in the presence of cesium fluoride at a slightly elevated
+
HO
O
O
CHO
26
27
1. t-BuOK, DMSO
2. AcOH, H2O, 39%
CF3
O
OH
OEt
+
HO
O
O
NEt2
31
32
∆, 55%
HO
O
O
28
NEt2
2, CsF, DMF,
60 °C, 79%
CF3
O
O
O
CF3
HO
O
33
F
OHC
F
2, CsF, DMF
68%
F
O
O
O
F
NEt2
29
O
O
O
F
F
F
F
O
O
O
F
F
F
F
1. 4, TFA, DCM
2. DDQ, 5%
O
O
O
NH
N
34
C6F5
C6F5
NHHN
1. 4, TFA
2. DDQ, 10%
30
O
O
O
NEt2
Scheme 6.
O
condensation with dipyrromethane 4 gave the required
corrole 25 in a yield of only 1.2%.
This inclined us to think about an alternative way to
link such π-expanded coumarins to the corrole core. We
reasoned that if coumarins possess a free OH group, the
nucleophilic substitution with C6F5CHO [26] can lead
to better results. It has been noted by Tkach that only
electron-poor aldehydes react with 4-methylcoumarins
to give styril coumarins in good yields. Indeed, the con-
densation of coumarin 19 with p-hydroxybenzaldehyde
did not lead to the expected product. Since the reaction
of coumarin 19 and pentafluorobenzaldehyde under
t-BuOK/DMSO conditions gave a mixture of tarry prod-
ucts, we turned our attention to styrilcoumarins derived
from 4-methylumbelliferone (26). Typically, such
O
F
F
F
F
NH
N
C6F5
C6F5
NHHN
35
Scheme 7.
Copyright © 2011 World Scientific Publishing Company
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1016 M. TaSIOr et al.
Table 1. Spectroscopic data for coumarins and coumarin-
corroles
temperature. Subsequent condensation with dipyr-
romethane 4, followed by oxidation with DDQ gave, in
13% yield, corrole-coumarin dyad 30 of a completely
different architecture compared to compounds 24
and 25.
Compound Solvent
λ
abs, nm
CH2Cl2 301
CH2Cl2 301, 408, 562, 604 145.4
ε × 10-3 a λem, nm
3
18.0
380
645
480
656
518
658
655
nde
Recently, Högberg et al. [30], and Kovtun and
coworkers [31] discovered two routes to a unique type
of π-expanded coumarins (Scheme 7). These com-
pounds are comprised of two coumarin units annelated
with C3–C4 bonds. The resulting dyes strongly absorb
blue-green light and have intense fluorescence. Using
the general approach developed by Kovtun et al.,
we synthesized new biscoumarin 33, possessing a
hydroxyl group, which underwent a reaction with pen-
tafluobenzaldehyde resulting in the formation of alde-
hyde 34. This aldehyde reacted with dipyrromethane
4 under typical conditions to give corrole 35 in 10%
yield (Scheme 7).
The survey of various strategies leading to dyads
comprised of coumarin and corrole units clearly proves
that even complex formyl-coumarins react with dipyr-
romethanes in [2+1] condensation; however, the yield
of macrocyclic products rarely exceeds 10%. On the
other hand, Sonogashira coupling of ethynylcorroles
with halogenocoumarins is a more efficient approach
and can give consistently higher yields of the desired
products.
The spectroscopic properties of the prepared com-
pounds are collected in Table 1. The absorption of
π-expanded coumarins is very strong, especially for
compounds 9, 23 and 33 (ε > 30000, Fig. 1). The absorp-
tion of coumarins 22 and 23, although very intense, was
not so bathochromically shifted as that of coumarins
17, 29 and 33 (Table 1). The influence of the presence
of coumarin units on the absorption spectra of dyads
depended on the type of linkage, as well as on the
absorption maximum of the coumarin counterpart. For
corroles 5, 30 and 35, where both units are not directly
linked but are separated by a moderately flexible linker,
the influence was not so pronounced. Still, there was a
characteristic hipsochromic shift in the Soret band in the
absorption spectra all these corroles (λmax = 408 nm),
which originated from the overlap of the spectra of the
corrole and coumarin units (Fig. 1, Table 1). The analy-
sis of the spectra of corroles 11, 15, 18, 24 and 25, where
modified coumarins were directly attached to the meso-
10-position of the corrole core, confirmed the previous
observation that due to substantial steric hindrance, there
is no direct electronic communication between both
units. The comparison of the absorption maxima with
the spectra of corrole 14 or 5,15-bis(pentafluorophenyl)-
10-(4-methylphenyl)corrole [5a] showed that the only
difference resulted from the partial overlap of the Soret
band with the absorption of coumarins in the violet-
blue region (Table 1, Fig. 1). In the absorption of dyad
18, one can easily see the broadening of the Soret band
5
9
CH2Cl2 426
35.0
13.1
2.2
11
13
14b
15
17
18
19c
22d
23
24
25
26
28
29
30
33
34
CH2Cl2 298, 421, 563, 612
CH2Cl2 397
Toluene 421, 564, 615, 641 103
CH2Cl2 292, 422, 563, 614 140
CH2Cl2 430
58
143.6
9.9
8
CH2Cl2 426, 563, 612
CH2Cl2 363
655
433
494
THF
CH2Cl2 341
CH2Cl2 305, 413, 563, 612 417
400
41.9 430, 550
658
573
574
491
457
645
508
527
646
CH2Cl2 413, 652, 613
THF 475
35
32
22
CH3CN 308
DMSO 432
2.5
CH2Cl2 308, 408, 562, 604 123
CH3CN 367, 444
CH3CN 342, 455
32.7
32.1
35
CH2Cl2 408, 459, 562, 604 983.1
a
b
For corroles ε refers to intensity of Soret band. Data from
Ref. 19. c Data from Ref. 32. d Data from Ref. 25. e Not detectable.
(which for typical meso-substituted corroles ends up at
~460 nm) which originated from the strong absorption
of the keto-bis-coumarin unit (Fig. 2).
The novel annelated biscoumarin 33 displayed intrigu-
ing spectroscopic properties, since the addition of the
auxochrome group (OH) resulted in a hipsochromic
rather than a bathochromic shift of absorption (λmax of
the analogous biscoumarin lacking a hydroxyl group was
around 455 nm) [31]. In a way, these compounds behaved
like a push-pull system. Replacing the strongly electron-
donating hydroxyl group with a OHCC6F4O group (33 →
34) resulted in a 11 nm bathochromic shift of absorption
and emission which further confirmed this conclusion
(Table 1). Strong absorption of coumarin 34 in the blue
region was also clearly visible on the spectrum of dyad
35 (Table 1).
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COrrOleS bearIng DIverSe COuMarIn unITS — SynTheSIS anD OPTICal PrOPerTIeS 1017
was performed using BioRad Bio-Beads
SX-1 with THF as the eluent. Mass spec-
tra were obtained on AMD-604 (AMD
Intectra GmbH), compounds 3, 9, 10,
13, 17, 23, 28, 29, 33 and 34; Mariner
(Perseptive Biosystems, Inc.), compounds
5, 18, 24 and 30; 4000 Q-TRAP (Applied
Biosystems), compounds 11 and 35; GCT
Premier (Waters), compounds 15 and 25.
The following compounds were prepared
as described in the literature: 1 [21],
4 [22], 12 [23], 14 [19], 16 [24], 22 [25].
APerkin-ElmerLambda25UV-visspec-
trophotometer and a Hitashi F7000 spectro-
fluorimeter were used to acquire absorption
and emission spectra. Spectrophotometric
grade solvents were used without further
purification.
Fig. 1. Absorption spectra of coumarins at room temperature: 3 (solid line),
9 (short dash), 23 (dotted line) and 33 (dashed line)
Synthesis
Preparation of 2,3,5,6-tetrafluoro-4-
((6-oxo-6H-benzo[c]chromen-3-yl)oxy)-
benzaldehyde (3). 3-hydroxy-6H-benzo[c]
chromen-6-one (1, 1.06 g, 5 mmol) was
dissolved in DMF (10 mL). Then cesium
fluoride (1.52 g, 10 mmol) was added, fol-
lowed by pentafluorobenzaldehyde 2 (0.62
mL, 5 mmol). A white precipitate was
formed immediately after the aldehyde
addition. The reaction was stirred for 2 h,
diluted with water and stirred for further 30
min. The obtained precipitate was filtered
off, washed thoroughly with water and air-
dried. Crystallization from glacial acetic
acid yielded compound 3 (1.67 g, 86%) as
an off-white solid; Rf 0.6 (chloroform), mp
227–228 °C. Anal. calcd. for C20H8F4O4:
C, 61.87; H, 2.08; F, 19.57%. Found: C,
61.98; H, 2.28; F, 19.57. UV-vis (CH2Cl2):
max, nm (ε × 10-4) 263 (1.9), 273 (2.2), 301 (1.8). 1H NMR
Fig. 2. Absorption and emission spectra of coumarin-corrole 18
λ
(500 MHz; DMSO-d6; Me4Si): δH, ppm 7.32 (1H, dd,
J3 = 8.8 Hz, J4 = 2.6 Hz, coum), 7.37 (1H, d, J = 2.6 Hz,
coum), 7.69 (1H, m, coum), 7.97 (1H, m, coum), 8.25
(1H, m, coum), 8.43 (2H, m, coum), 10.24 (1H, s, CHO).
13C NMR (125 MHz; DMSO-d6; Me4Si): δC, ppm 104.9,
112.4, 113.2, 114.9, 120.4, 123.1, 126.1, 129.2, 130.2,
134.4, 135.9, 137.1, 141.4 (dm, J = 235 Hz), 147.7 (dm,
J = 250 Hz), 152.4, 157.9, 160.5, 183.9. HRMS (EI): m/z
388.0363 (calcd. for [M]·+ 388.0359).
Preparation of 5,15-bis(pentafluorophenyl)-10-(4-
((6-oxo-6H-benzo[c]chromen-3-yl)oxy)-2,3,5,6-tetra-
fluorophen-1-yl)corrole (5). Aldehyde 3 (970 mg,
2.5 mmol) and 5-(pentafluorophenyl)dipyrromethane
(4, 1.56 g, 5 mmol) were suspended in dichloromethane
(37 mL). Then the pre-prepared solution of TFA (410 μL,
TFA/dichloromethane 1:10) was added while stirring to
EXPERIMENTAL
General
All chemicals were used as received unless otherwise
noted. Reagent grade solvents (MeCN, CH2Cl2, hexanes,
toluene) were distilled prior to use. All reported NMR
spectra were recorded on a 400 MHz or 500 MHz spec-
trometer unless otherwise noted. Chemical shifts (δ, ppm)
were determined with TMS as the internal reference;
J values are given in Hz. UV-vis absorption spectra were
recorded in THF. Chromatography was performed on sil-
ica (Kieselgel 60, 200–400 mesh) and dry column vacuum
chromatography (DCVC) [20] was performed on prepar-
ative thin layer chromatography silica (Merck 107747).
Preparative scale size exclusion chromatography (SEC)
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1018 M. TaSIOr et al.
achieve a TFA concentration of 13.5 μM. The reaction
was stirred at rt for 40 min and monitored by TLC (alde-
hyde consumption). After that, triethylamine (70 μL, 0.5
μmol) was added to quench the reaction. The resulting
solution was diluted to 150 mL with dichloromethane
and oxidised with DDQ (1.48 g, 6.5 mmol; dissolved in a
minimal amount of toluene). After 2 h, the reaction mix-
ture was filtered through a silica pad, corrole containing
fractions were collected and evaporated with celite and
then chromatographed on a 15 cm column, eluting with
dichloromethane/hexanes (increasing polarity gradually
from hexanes to dichloromethane/hexanes 1:1; when the
red fluorescent product was close to the bottom of a col-
umn, 0.2% of methanol was added to the eluent). Crystal-
line sample was obtained by boiling collected product in a
small amount of dichloromethane and filtering off precipi-
tate after cooling the mixture, Rf 0.6 (dichloromethane/
calcd. for C26H29NO5: C, 71.70; H, 6.71; N, 3.22%.
Found: C, 71.75; H, 6.82; N, 3.04. IR (KBr): ν, cm-1 782,
1098, 1234, 1350, 1510, 1579, 1620, 1639, 1718, 1918.
UV-vis (CH2Cl2): λmax, nm (ε × 10-4) 253 (1.6), 426 (3.5).
1H NMR (500 MHz, CDCl3): δH, ppm 0.81 (3H, s, CH3),
1.24 (6H, t, J = 7.1 Hz, 2 × CH2CH3), 1.29 (3H, s, CH3),
3.45 (4H, q, J = 7.1 Hz, 2 × CH2CH3), 3.67 (2H, d, J = 11
Hz, CH2O), 3.79 (2H, d, J = 11 Hz, CH2O), 5.44 (1H, s,
CH acetal), 6.50 (1H, d, J = 2.4 Hz, Ar), 6.61 (1H, dd, J3 =
8.9 Hz, J4 = 2.4 Hz, Ar), 7.32 (1H, d, J = 8.9 Hz, Ar),
7.59, 7.82 (2 × 2H, AA′BB′, J = 8.3 Hz, C6H4), 8.01 (1H,
s, CH). 13C NMR (125 MHz, CDCl3): δC, ppm 12.4, 21.8,
23.0, 30.2, 45.1, 77.6, 97.0, 100.9, 107.7, 109.6, 117.7,
126.0, 129.4, 130.9, 138.2, 142.6, 147.8, 152.6, 158.2,
159.4, 192.2. HRMS (EI): m/z 435.2035 (calcd. for [M]·+
435.2046).
Preparation of 3-(4-formylbenzoyl)-7-diethylamino-
2-oxo-2H-chromen (10). Acetal 9 (1.0 g, 2.3 mmol) was
dissolved in CH2Cl2 (10 mL), TFA (5 mL) was slowly
added, followed by H2O (1 mL) and the resulting mixture
was vigorously stirred for 48 h. Subsequently, the acid
was neutralised with NaHCO3 aq, the resulting suspen-
sion was extracted three times with CH2Cl2, the com-
bined organic phases were washed with H2O and dried
(Na2SO4). The solvent was removed and the residue was
crystallised from MeOH to afford 789 mg (98%) of cou-
marin 10. An analytically pure sample was obtained by
chromatography (SiO2, CH2Cl2/acetone, 95:5). mp 123–
124 °C. Anal. calcd. for C21H19NO4: C, 72.19; H, 5.48; N,
4.01%. Found: C, 71.79; H, 5.35; N, 4.12. IR (KBr): ν,
cm-1 1231, 1352, 1511, 1579, 1619, 1706. UV-vis (tolu-
ene): λmax, nm 432. 1H NMR (500 MHz, CDCl3): δH, ppm
1.26 (6H, t, J = 7.1 Hz, 2 × CH2CH3), 3.47 (4H, q, J =
7.1 Hz, 2 × CH2CH3), 6.51 (1H, d, J = 2.4 Hz, Ar), 6.65
(1H, dd, J3 = 9 Hz, J4 = 2.4 Hz, Ar), 7.40 (1H, d, J = 9 Hz,
Ar), 7.90, 7.97 (2 × 2H, AA′BB′, J = 8.4 Hz, C6H4), 8.23
(1H, s, CH), 10.09 (1H, s, CHO). 13C NMR (125 MHz,
CDCl3): δC, ppm 12.4, 45.2, 97.0, 108.1, 109.9, 116.6,
129.3, 129.4, 131.5, 138.4, 143.3, 148.7, 153.1, 158.7,
159.8, 191.7, 192.1. HRMS (EI): m/z 349.1325 (calcd.
for [M]·+ 349.1314).
hexanes 2:1). Yield 150 mg (6%). UV-vis (CH2Cl2): λmax
,
nm (ε × 10-4) 274 (3.7), 301 (3.1), 408 (14.5), 562 (2.3),
1
604 (1.3). H NMR (400 MHz; CDCl3; Me4Si): δH, ppm
7.35 (1H, dd, J3 = 8.4 Hz, J4 = 2.4 Hz, coum), 7.62 (1H,
m, coum), 7.88 (1H, m, coum), 8.13 (1H, d, J = 8.4 Hz,
coum), 8.20 (1H, d, J = 9.2 Hz, coum), 8.43 (1H, m,
coum), 8.59 (2H, m, β-H-pyrrole), 8.69 (2H, d, J = 4.4
Hz, β-H-pyrrole), 8.82 (2H, d, J = 4.4 Hz, β-H-pyrrole),
9.12 (2H, d, J = 4.4 Hz, β-H-pyrrole); one signal from the
coumarin moiety is hidden under the solvent peak. HRMS
(ESI): m/z 989.1226 (calcd. for [M + H]+ 989.1228).
Preparation of methyl 4′-(5,5-dimethyl-1,3-dioxan-
2-yl)benzoylacetate (7). Activated zinc (13.08 g, 0.2
mol) was suspended in anh. boiling THF (120 mL). A few
drops of methyl bromoacetate were added while reflux
was maintained, followed by acetal 6 (8.68 g, 40 mmol).
Subsequently, methyl bromoacetate was added (15 mL,
160 mmol, dropwise, over 30 min) and heating was con-
tinued for additional 15 min. Then, the reaction mixture
was cooled to rt and HCl aq (10%, 40 mL) was slowly
added. The resulting mixture was extracted a few times
with CH2Cl2, and the organic extracts were washed with
H2O, dried with Na2SO4 and chromatographed (SiO2,
CH2Cl2, then CH2Cl2/acetone, 98:2, 95:5) to afford the
expected ester 7 contaminated with small amounts of an
unidentified compound that could not be removed by fur-
ther chromatography. This material was used in the next
step without any further purification.
Preparation of 3-[4-(5,5-dimethyl-1,3-dioxan-2-yl)-
benzoyl]-7-diethylamino-2-oxo-2H-chromen (9). Ester
7 (1.5 g, 5 mmol, crude), 4-diethylamino-2-hydroxyben-
zaldehyde (8, 965 mg, 5 mmol) and pyrrolidine (200 μL,
2.4 mmol) were dissolved in MeOH (200 mL) and the
resulting mixture was refluxed for 6 h. Subsequently,
the reaction mixture was cooled to 4 °C, and the pre-
cipitate was filtered off and washed with cold MeOH to
afford 1.07 g of the expected product. The supernatant
was evaporated and chromatographed (SiO2, CH2Cl2/
acetone, 95:5) giving an additional 237 mg of coumarin 9.
The total yield was 1.31 g (60%). mp 175–176 °C. Anal.
Preparation of corrole 11. 5-(pentafluorophenyl)-
dipyrromethane (4, 625 mg, 2 mmol) and coumarin 10
(349 mg, 1 mmol) were dissolved in CH2Cl2 (60 mL) and
TFA (230 μL, 3 mmol) was slowly added. After stirring
at rt for 1 h, Et3N (416 μL, 3 mmol) was added. DDQ
(1590 mg, 2.6 mmol) was dissolved in toluene/CH2Cl2
(1:5, 60 mL) and both solutions were added simultane-
ously via syringes to vigorously stirred CH2Cl2 (50 mL).
After 15 min, the reaction mixture was concentrated to
one quarter of the initial volume and filtered through a
short (5 cm) silica pad (CH2Cl2, then CH2Cl2/acetone,
98:2). The fluorescent band was collected, evaporated and
rechromatographed (DCVC, SiO2, CH2Cl2, then CH2Cl2/
acetone, 98:2). Crystallization from CHCl3/hexane gave
88 mg (9%) of corrole 11. Rf 0.42 (CH2Cl2/acetone,
98:2). Anal. calcd. for C51H28F10N5O3: C, 64.49; H, 3.08;
Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 1018–1023

COrrOleS bearIng DIverSe COuMarIn unITS — SynTheSIS anD OPTICal PrOPerTIeS 1019
N, 7.37%. Found: C, 64.65; H, 2.79; N, 7.15. UV-vis
(50 μL, 0.6 mmol) and AcOH (35 μL, 0.6 mmol) were
dissolved in hot MeOH (50 mL) and the resulting mix-
ture was heated under reflux for 6 h. Subsequently, the
reaction mixture was cooled to 4 °C, and the precipitate
was filtered off and washed with cold MeOH to afford
188 mg of 17 (80%). mp 268–269 °C. Anal. calcd. for
C23H18NO5Br: C, 58.99; H, 3.87; N, 2.99%. Found: C,
58.86; H, 3.99; N, 3.04. IR (KBr): ν, cm-1 1505, 1572,
1608, 1711, 1730. UV-vis (CH2Cl2): λmax, nm (ε × 10-4)
430 (5.8). 1H NMR (500 MHz, DMSO-d6): δH, ppm 1.16
(6H, t, J = 6.9 Hz, 2 × CH2CH3), 3.28 (4H, q, J = 6.9
Hz, 2 × CH2CH3), 6.63 (1H, d, J = 2.1 Hz, Ar), 6.85
(1H, dd, J3 = 9.0 Hz, J4 = 2.1 Hz, Ar), 7.47 (1H, d, J =
8.8 Hz, Ar), 7.72 (1H, d, J = 9.0 Hz, Ar), 7.87 (1H, dd,
J3 = 8.8 Hz, J4 = 2.3 Hz, Ar), 8.13 (1H, d, J = 2.3 Hz, Ar),
8.27 (1H, s, CH), 8.57 (1H, s, CH). 13C NMR (125 MHz,
DMSO-d6): δC, ppm 12.3, 44.5, 96.2, 107.7, 110.4, 115.1,
116.4, 118.5, 120.3, 130.2, 131.5, 132.6, 135.4, 141.0,
147.7, 152.7, 153.3, 157.8, 158.2, 159.8, 186.6. HRMS
(EI): m/z 467.0360 (calcd. for [M]·+ 467.0368).
(CH2Cl2): λmax, nm (ε × 10-4) 298 (2.1), 421 (13.1), 563
1
(1.6), 612 (1.3). H NMR (500 MHz, CDCl3): δH, ppm
(-5)-(-1) (3H, br s), 1.27 (6H, t, J = 7.1 Hz, 2 × CH2CH3),
3.48 (4H, q, J = 7.1 Hz, 2 × CH2CH3), 6.56 (1H, d, J =
2.3 Hz, Ar), 6.65 (1H, dd, J3 = 9 Hz, J4 = 2.3 Hz, Ar),
7.47 (1H, d, J = 9 Hz, Ar), 8.20, 8.27 (2 × 2H, AA′BB′,
J = 8.4 Hz, C6H4), 8.3 (1H, s, CH), 8.57 (2H, br s, β-H),
8.72 (2H, d, J = 4.6 Hz, β-H), 8.75 (2H, d, J = 4.6 Hz,
β-H), 9.11 (2H, d, J = 4.1 Hz, β-H). MS (ESI): m/z 950.4
(calcd. for [M + H]+ 950.2).
Preparation of 6-bromo-7-diethylamino-3-meth-
oxycarbonyl-2-oxo-2H-chromen (13). Aldehyde 12
(1.48 g, 5.4 mmol), dimethyl malonate (621 μL, 5.4
mmol), pyrrolidine (40 μL, 0.48 mmol) andAcOH (30 μL,
0.48 mmol) were dissolved in hot MeOH (10 mL) and
the resulting mixture was heated under reflux for 6 h.
Subsequently, the reaction mixture was cooled to 4 °C,
and the precipitate was filtered off and washed with
cold MeOH to afford 1.74 g (90%) of yellow crystals.
mp 99–100 °C. Anal. calcd. for C15H16NO4Br: C, 50.86;
H, 4.55; N, 3.95%. Found: C, 51.03; H, 4.46; N, 3.68.
IR (KBr): ν, cm-1 793, 1218, 1598, 1691, 1708, 1747.
UV-vis (CH2Cl2): λmax, nm (ε × 10-4) 397 (2.2). 1H NMR
(500 MHz, CDCl3): δH, ppm 1.15 (6H, t, J = 7.0 Hz, 2 ×
CH2CH3), 3.32 (4H, q, J = 7.0 Hz, 2 × CH2CH3), 3.94
(3H, s, CO2CH3), 6.88 (1H, s, Ar), 7.75 (1H, s, Ar), 8.42
(1H, s, CH). 13C NMR (125 MHz, CDCl3): δC, ppm 12.3,
46.0, 52.7, 108.7, 112.9, 113.6, 114.3, 134.4, 148.0,
155.3, 155.6, 156.8, 163.9. HRMS (EI): m/z 353.0269
(calcd. for [M]·+ 353.0263).
Preparation of corrole 15. Corrole 14 (48 mg,
65 μmol), coumarin 13 (23 mg, 65 μmol), Cs2CO3 (23 mg,
70 μmol), Pd(OAc)2 (0.67 mg, 3.3 μmol) and PPh3 (3.1
mg, 13.2 μmol) were placed in a Schlenk tube and anh.
DMSO (2 mL) was added under an argon atmosphere.
After heating at 80 °C for 24 h, the solvent was removed
under reduced pressure and the residue was chromato-
graphed (SiO2, CH2Cl2, then CH2Cl2/acetone 98:2). Frac-
tions containing the expected product were collected,
evaporated and further purified using SEC (THF). Crys-
tallisation from CHCl3/hexanes gave 31 mg of corrole 15
(52%). Rf 0.27 (CH2Cl2/acetone 98:2). Anal. calcd. for
C54H31F10N5O4 × 2H2O: C, 62.37; H, 3.39; N, 6.73%.
Preparation of corrole 18. Corrole 14 (72 mg, 100
μmol), coumarin 17 (56 mg, 120 μmol), Cs2CO3 (27.6
mg, 104 μmol), Pd(OAc)2 (5.0 mg, 25 μmol) and PPh3
(24 mg, 100 μmol) were placed in Schlenk tube and anh.
DMSO (2 mL) was added under an argon atmosphere.
After heating at 80 °C for 24 h, the solvent was removed
under reduced pressure and the residue was chromato-
graphed (SiO2, CH2Cl2, then CH2Cl2/acetone 98:2). Frac-
tions containing the expected product were collected,
evaporated and further purified using SEC (THF). Crys-
tallization from CHCl3/hexanes gave 62 mg of corrole 18
(55%). Rf 0.45 (CH2Cl2). UV-vis (CH2Cl2): λmax, nm (ε ×
10-4) 289 (5.3), 413 (14.5), 426 (14.5), 563 (2.0), 612
1
(1.2). H NMR (500 MHz, CDCl3): δH, ppm (-4)-(-1.5)
(3H, br s, NH), 1.25 (6H, t, J = 7.1 Hz, 2 × CH2CH3), 3.48
(4H, q, J = 7.1 Hz, 2 × CH2CH3), 6.49 (1H, d, J = 2.2 Hz,
Ar), 6.63 (1H, dd, J3 = 9 Hz, J4 = 2.2 Hz, Ar), 7.42 (1H, d,
J = 8.5 Hz, Ar), 7.43 (1H, d, J = 9 Hz, Ar), 7.85 (1H, dd,
J3 = 8.5 Hz, J4 = 1.9 Hz, Ar), 7.88 (1H, d, J = 1.9 Hz, Ar),
7.98, 8.21 (2 × 2H, AA′BB′, J = 7.8 Hz, C6H4), 8.02 (1H,
s, Ar), 8.34 (1H, s, CH), 8.59 (2H, br s, β-H), 8.75 (4H, br
s, β-H), 9.12 (2H, br d, J = 3.2 Hz, β-H). MS (ESI): m/z
1118.2 (calcd. for [M + H]+ 1118.2).
Preparation of 4-[(4′-formylbiphenyl-4)-ethenyl]-
7-diethylamino-2-oxo-2H-chromen (23). A mixture
of coumarin 19 (925 mg, 4 mmol) and tert-BuOK
(449 mg, 4 mmol) in DMSO (10 mL) was stirred for
10 min. Aldehyde 21 (1.11 g, 5 mmol) was added and the
resulting mixture was stirred at rt for 5 h. Subsequently,
AcOH (1.5 mL) was added, followed by water (90 mL).
A yellow-red precipitate appeared, which was filtered
off, washed with water and air dried. Chromatography
on silica (CH2Cl2, then CH2Cl2/acetone 95:5) followed
by crystallization from EtOH afforded 461 mg (27%) of
23 (contaminated with some unidentified species) as red
crystals. mp 180 °C (dec.). Anal. calcd. for C28H25NO3:
C, 79.41; H, 5.95; N, 3.31%. Found: C, 79.22; H, 5.73;
Found: C, 62.09; H, 3.29; N, 6.43. UV-vis (CH2Cl2): λmax
,
nm (ε × 10-4) 292 (3.4), 422 (14), 563 (1.5), 614 (1.3). 1H
NMR (500 MHz, CDCl3): δH, ppm (-4)-(-1.5) (3H, br s,
NH), 1.44 (6H, t, J = 7.0 Hz, 2 × CH2CH3), 3.82 (4H, q,
J = 7.0 Hz, 2 × CH2CH3), 3.93 (3H, s, CO2CH3), 6.70
(1H, s, Ar), 7.81 (1H, s, Ar), 7.90, 8.21 (2 × 2H, AA’BB’,
J = 7.9 Hz, C6H4), 8.47 (1H, s, CH). 8.58 (2H, br s, β-H),
8.73 (4H, br s, β-H), 9.12 (2H, br s, β-H). MS (FD): m/z
1003.2 (calcd. for [M]·+ 1003.2).
Preparation of 6-bromo-3-[(7-diethylamino-2-oxo-
2H-chromen-3-yl)carbonyl]-4a,8a-dihydro-2H-
chromen-2-on (17). 5-bromosalicylaldehyde (100 mg,
0.5 mmol), ester 16 (159 mg, 0.5 mmol), pyrrolidine
Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 1019–1023

1020 M. TaSIOr et al.
N, 3.28. IR (KBr): ν, cm-1 813, 1138, 1412, 1520, 1604,
1696. UV-vis (CH2Cl2): λmax, nm (ε × 10-4) 341 (4.2). 1H
NMR (500 MHz, CDCl3): δH, ppm 1.15 (6H, t, J = 7.1
Hz, 2 × CH2CH3), 3.46 (4H, q, J = 7.1 Hz, 2 × CH2CH3),
6.39 (1H, s, CH), 6.56 (1H, d, J = 2.6 Hz, Ar), 6.72 (1H,
dd, J3 = 9.0 Hz, J4 = 2.6 Hz, Ar), 7.65 (1H, d, J = 16 Hz,
CH=CH), 7.72 (1H, d, J = 16 Hz, CH=CH), 7.87 (1H, d,
J = 9 Hz, Ar), 7.93–8.03 (8H, m, biphenyl), 10.07 (1H, s,
CHO). 13C NMR (125 MHz, CDCl3): δC, ppm 12.8, 44.4,
97.6, 102.4, 107.3, 109.0, 121.8, 126.8, 127.7, 127.9,
128.4, 129.1, 130.6, 135.7, 136.7, 139.6, 145.5, 150.4,
150.9, 156.6, 161.6, 193.152. HRMS (EI): 423.1853
(calcd. for [M]·+ 423.1834).
Preparation of corrole 24. 5-(pentafluorophenyl)-
dipyrromethane (4, 250 mg, 0.8 mmol) and coumarin 22
(139 mg, 0.4 mmol) were dissolved in CH2Cl2 (24 mL)
and TFA (96 μL, 1.2 mmol) was slowly added. After stir-
ring at rt for 1 h, Et3N (166 μL, 1.2 mmol) was added and
the reaction mixture was diluted by adding of 600 mL
of CH2Cl2. Subsequently, DDQ (236 mg, 1.04 mmol) in
THF (1.5 mL) was added with vigorous stirring. After 15
min, the reaction mixture was concentrated to 50 mL and
filtered through a short (5 cm) silica pad (CH2Cl2, then
CH2Cl2/acetone, 95:5). The fluorescent band was col-
lected, evaporated and rechromatographed (DCVC, SiO2,
CH2Cl2, then CH2Cl2/acetone, 95:5). Crystallization from
CHCl3/hexanes gave 63 mg (17%) of corrole 24. Rf 0.64
(CH2Cl2/acetone, 95:5). Anal. calcd. for C52H31F10N5O2:
C, 65.89; H, 3.30; N, 7.39%. Found: C, 65.98; H, 3.13; N,
7.29. UV-vis (CH2Cl2): λmax, nm (ε × 10-4) 305 (3.7), 413
(41.7), 563 (2.2), 612 (1.3). 1H NMR (500 MHz, CDCl3):
δH, ppm (-4)-(-1.5) (3H, br s, NH), 1.25 (6H, t, J = 7.1
Hz, 2 × CH2CH3), 3.45 (4H, q, 7.1 Hz, 2 × CH2CH3), 6.38
(1H, s, CH), 6.57 (1H, d, J = 2.6 Hz, Ar), 6.66 (1H, dd, J3
= 9.0 Hz, J4 = 2.6 Hz, Ar), 7.60 (2H, br s, CH=CH), 7.71
(1H, d, J = 9 Hz, Ar), 7.97, 8.24 (2 × 2H, AA′BB′, J = 7.9
Hz, C6H4), 8.58 (2H, br d, J = 2.6 Hz, β-H), 8.74 (4H, br
s, β-H), 9.12 (2H, d, J = 4.1 Hz, β-H). HRMS (ESI): m/z
948.2421 (calcd. for [M + H]+ 948.2391).
(4H, q, 7.2 Hz, 2 × CH2CH3), 6.32 (1H, s, CH), 6.57 (1H,
d, J = 2.6 Hz, Ar), 6.65 (1H, dd, J3 = 9.0 Hz, J4 = 2.6 Hz,
Ar), 7.43 (2H, br s, CH=CH), 7.65 (1H, d, J = 9 Hz, Ar),
7.79, 7.97 (2 × 2H, AA′BB′, J = 8.4 Hz, C6H4), 8.04, 8.29
(2 × 2H, AA′BB′, J = 8.0 Hz, C6H4), 8.59 (2H, d, J = 4.2
Hz, β-H), 8.74 (2H, d, J = 4.6 Hz, β-H), 8.80 (2H, d, J =
4.6 Hz, β-H), 9.13 (2H, d, J = 4.2 Hz, β-H). MS (FD): m/z
1023.2 (calcd. for [M]·+ 1023.3).
Preparation of 4-[(4-trifluoromethylphenyl)-ethenyl]-
7-hydroxy-2-oxo-2H-chromen (28). A mixture of
coumarin 26 (3.52 g, 20 mmol) and tert-BuOK (4.49 g,
40 mmol) in DMSO (80 mL) was stirred for 10 min.
Aldehyde 27 (4.1 mL, 30 mmol) was added and
the resulting mixture was stirred at rt for 5 h. Subse-
quently, AcOH (10 mL) was added, followed by water
(400 mL). A yellow-red precipitate appeared, which was
filtered off, washed with water and air dried. Crystalliza-
tion from EtOH afforded 2.6 g (39%) of 28 as yellowish
crystals. mp 259–261 °C. Anal. calcd. for C18H11O3F3: C,
65.06; H, 3.34%. Found: C, 64.83; H, 3.16. IR (KBr):
δ, cm-1 842, 1066, 1321, 1386, 1677, 3103. UV-vis
1
(CH3CN): λmax, nm (ε × 10-4) 308 (2.2). H NMR (500
MHz, DMSO-d6): δH, ppm 6.57 (1H, s, CH), 6.74 (1H,
d, J = 2.3 Hz, Ar), 6.82 (1H, dd, J3 = 8.7 Hz, J4 = 2.5 Hz,
Ar), 7.66 (1H, d, J = 16 Hz, CH=CH), 7.76–7.80 (3H,
m, CH=CH + C6H4), 8.00 (2H, d, J = 7.8 Hz, C6H4), 8.02
(1H, d, J = 9 Hz, Ar), 10.59 (1H, s, OH). 13C NMR (125
MHz, DMSO-d6): δC, ppm 103.0, 106.2, 111.0, 113.4,
123.9, 126.0 (q, J = 2.7 Hz), 127.2, 128.9, 129.4 (q, J =
38 Hz), 136.3, 140.30, 14.31, 150.2, 155.8, 161.1, 161.8.
HRMS (EI): m/z 332.0667 (calcd. for [M]·+ 332.0660).
Preparation of aldehyde 29. A mixture of coumarin
28 (664 mg, 2 mmol), aldehyde 2 (248 µL, 2 mmol) and
CsF (608 mg, 4 mmol) in DMF (10 mL) was stirred at
65 °C for 1 h. Subsequently, water was added and the
resulting mixture was extracted with CH2Cl2. The organic
solvent was removed under reduced pressure and the res-
idue was crystallized from EtOH to afford 800 mg (79%)
of 29 as off-white crystals. mp 236–239 °C. Anal. calcd.
for C25H11O4F7: C, 59.07; H, 2.18%. Found: C, 59.08;
H, 1.96. IR (KBr): ν, cm-1 841, 1114, 1327, 1489, 1613,
1698. UV-vis (DMSO): λmax, nm (ε × 10-4) 315 (2.5). 1H
NMR (500 MHz, DMSO-d6): δH, ppm 6.82 (1H, s, CH),
7.32 (1H, dd, J3 = 9.0 Hz, J4 = 2.8 Hz, Ar), 7.37 (1H,
d, J = 2.8 Hz, Ar), 7.75 (1H, d, J = 16 Hz, CH=CH),
7.82, 8.05 (2 × 2H, AA′BB′, J = 8.2 Hz, C6H4), 7.87 (1H,
d, J = 16 Hz, CH=CH), 8.31 (1H, d, J = 9.0 Hz, Ar),
10.24 (1H, s, CHO). 13C NMR (125 MHz, DMSO-d6):
δC, ppm 104.3, 109.3, 112.7 (m), 113.0, 1115.4, 123.4,
123.5, 126.1 (q, J = 3.9 Hz), 127.9, 128.0, 129.0, 129.7
(q, J = 38 Hz), 137.0 (m), 140.2 (m), 146.6 (m), 148.7
(m), 149.6, 155.3, 159.0, 160.4, 183.9. HRMS (EI): m/z
508.0539 (calcd. for [M]·+ 508.0546).
Preparation of corrole 25. 5-(pentafluorophenyl)-
dipyrromethane (4, 500 mg, 1.6 mmol) and coumarin 23
(339mg, 0.8mmol)weredissolvedinCH2Cl2 (48mL)and
TFA (192 μL, 2.4 mmol) was slowly added. After stirring
at rt for 1 h, Et3N (332 μL, 2.4 mmol) was added. DDQ
(472 mg, 2.08 mmol) was dissolved in toluene/CH2Cl2
(1:2, 48 mL) and both solutions were added simultane-
ously via syringes to vigorously stirred CH2Cl2 (50 mL).
After 15 min, the reaction mixture was concentrated to
one quarter of the initial volume and filtered through a
short (10 cm) silica pad (CH2Cl2, then CH2Cl2/acetone,
99:1). The fluorescent band was collected, evaporated and
loaded on SEC (THF). Fractions containing the desired
product were evaporated to afford 10 mg (1.2%) of cor-
role 25. Rf 0.59 (CH2Cl2/acetone, 95:5). UV-vis (CH2Cl2):
Preparation of corrole (30). 5-(pentafluorophenyl)-
dipyrromethane (4, 375 mg, 1.2 mmol) and coumarin 29
(306 mg, 0.6 mmol) were dissolved in CH2Cl2 (18 mL)
and TFA (18 µL, 0.23 mmol) was slowly added. After
λ
max, nm (ε × 10-4) 347 (3.8), 413 (11.2), 562 (1.6), 613
1
(0.9). H NMR (500 MHz, CDCl3): δH, ppm (-4)-(-1.5)
(3H, br s, NH), 1.25 (6H, t, J = 7.2 Hz, 2 × CH2CH3), 3.45
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COrrOleS bearIng DIverSe COuMarIn unITS — SynTheSIS anD OPTICal PrOPerTIeS 1021
stirring at rt for 1 h (coumarin slowly dissolved), Et3N
column eluting with 1% methanol in dichloromethane; Rf
0.45 (dichloromethane/methanol 95:5). The product-con-
taining fractions were collected, dried and crystallized
from chloroform/hexane, yielding the title compound
(895 mg, 68%) as a yellow solid; mp 240–241 °C. UV-
vis (CH2Cl2): λmax, nm (ε × 10-4) 291 (2.7), 345 (1.5),
460 (3.2). 1H NMR (400 MHz; CDCl3; Me4Si): δH, ppm
1.28 (6H, t, J = 7.2 Hz, CH3), 3.50 (4H, q, J = 7.2 Hz,
CH2), 6.52 (1H, d, J = 2.7 Hz, Ar), 6.71 (1H, dd, J3 = 9.4
Hz, J4 = 2.7 Hz, Ar), 6.94 (1H, d, J = 2.7 Hz, Ar), 7.05
(1H, dd, J3 = 9.1 Hz, J4 = 2.7 Hz, Ar), 8.00 (1H, d, J =
9.4 Hz, Ar), 8.26 (1H, d, J = 9.1 Hz, Ar), 10.34 (1H, s,
formyl). 13C NMR (100 MHz; CDCl3; Me4Si): δC, ppm
12.7, 45.4, 98.0, 99.3, 104.1, 104.8, 110.1, 112.5, 112.9,
130.1, 131.0, 151.8, 153.2, 156.4, 156.8, 157.2, 158.5,
160.1, 181.9. HRMS (EI): m/z 527.0985 (calcd. for [M]·+
527.0992).
(33 μL, 0.23 mmol) was added. DDQ (354 mg, 1.56
mmol) was dissolved in toluene/CH2Cl2 (1:2, 18 mL) and
both solutions were added simultaneously via syringes
to vigorously stirred CH2Cl2 (40 mL). After 15 min, the
reaction mixture was concentrated to one quarter of the
initial volume and filtered through a short (10 cm) silica
pad (CH2Cl2/hexanes, 1:1). The fluorescent band was
collected, evaporated and loaded on SEC (THF). Frac-
tions containing the desired product were evaporated to
afford 33 mg (5%) of corrole 30. Rf 0.33 (CH2Cl2/hexane,
3:1). UV-vis (CH2Cl2): λmax, nm (ε × 10-4) 308 (4.2), 408
(12.3), 562 (2.0), 604 (1.1). 1H NMR (500 MHz, CDCl3):
δH, ppm (-4)-(-1.5) (3H, br s, NH), 6.59 (1H, s, CH), 7.24
(1H, d, J = 2.0 Hz, Ar), 7.33 (1H, dd, J3 = 9.0 Hz, J4 = 2.0
Hz, Ar), 7.38 (1H, d, J = 16 Hz, CH=CH), 7.46 (1H, d,
J = 16 Hz, CH=CH), 7.72 (4H, br s, C6H4), 7.92 (1H, d,
J = 9 Hz, Ar), 8.04, 8.29 (2 × 2H, AA′BB′, J = 8.0 Hz,
C6H4), 8.54 (2H, br s, β-H), 8.70 (2H, d, J = 4.5 Hz, β-H),
8.82 (2H, d, J = 4.5 Hz, β-H), 9.08 (2H, br s, β-H). HRMS
(ESI): m/z 1109.1372 (calcd. for [M + H]+ 1109.1415).
Preparation of 3-(diethylamino)-10-hydroxychro-
meno[3,4-c]chromene-6,7-dione (33). 7-hydroxycou-
marin-3-carboxylic acid ethyl ester (31, 2.34 g, 10 mmol)
was heated together with m-diethylaminophenole (32,
1.65 g, 10 mmol) at 140 °C for 6 h. After cooling, the
reaction mixture was triturated with diethyl ether to wash
out unreacted material and other contaminants, after
which dark orange crystals appeared. Precipitate was
collected by filtration and the crude product was boiled
in isopropanol, then filtered after cooling and air-dried.
Yield 965 mg (55%); mp 281–283 °C. Rf 0.5 (dichlo-
romethane/acetone 7:3). UV-vis (CH2Cl2): λmax, nm (ε ×
10-4) 283 (1.7), 371 (1.7), 444 (3.2). 1H NMR (600 MHz;
DMSO-d6; Me4Si): δH, ppm 1.17 (6H, t, J = 6.9 Hz, CH3),
3.50 (4H, q, J = 7.0 Hz, CH2), 6.55 (1H, d, J = 3.0 Hz,
Ar), 6.72 (1H, d, J = 3.0 Hz, Ar), 6.80 (1H, dd, J3 = 9.6
Hz, J4 = 2.4 Hz, Ar), 6.89 (1H, dd, J3 = 9.3 Hz, J4 = 2.7
Hz, Ar), 8.07 (1H, d, J = 9.6 Hz, Ar), 8.15 (1H, d, J =
9.0 Hz, Ar), 11.07 (1H, br s, hydroxyl). 13C NMR (150
MHz; DMSO-d6; Me4Si): δC, ppm 12.8, 44.7, 97.0, 97.2,
103.2, 103.7, 108.0, 110.2, 114.0, 130.9, 131.4, 152.3,
152.8, 156.4, 156.7, 157.0, 157.9, 163.8. HRMS (EI):
m/z 351.1096 (calcd. for [M]·+ 351.1107).
Preparation of 5,15-bis(pentafluorophenyl)-10-(4-
((10-(diethylamino)-6,7-dioxo-6,7-dihydrochro-
meno[3,4-c]chromen-3-yl)oxy)-2,3,5,6-tetrafluoro-
phen-1-yl)corrole (35). Aldehyde 34 (370 mg, 0.7 mmol)
and 5-(pentafluorophenyl)dipyrromethane (4, 440 mg,
1.4 mmol) were suspended in dichloromethane (10 mL).
A pre-prepared solution of TFA in CH2Cl2 (230 μL, TFA/
CH2Cl2 1:10) was added to this suspension to achieve a
final TFA concentration ca. 2.7 μM. The progress of the
reaction was monitored by TLC (aldehyde consumption);
during the reaction, substrates gradually dissolved. After
stirring the reaction for 40 min it was quenched by the
addition of triethylamine (40 μL, 0.287 μmol). The result-
ing solution was diluted to 100 mL with dichloromethane
and oxidized with DDQ (413 mg, 1.82 mmol; dissolved
in minimal amount of toluene prior addition). After 2 h,
the reaction mixture was filtered through a silica pad,
evaporated with celite and chromatographed eluting with
toluene/acetone 4:1; Rf 0.42. Yield 76 mg (10%). UV-vis
(CH2Cl2): λmax, nm (ε × 10-4) 291 (2.4), 408 (10.5), 459
1
(2.0), 562 (1.6), 604 (0.9). H NMR (400 MHz; CDCl3;
Me4Si): δH, ppm 1.30 (6H, t, J = 7.1 Hz, CH3), 3.51 (4H,
q, J = 7.1 Hz, CH2), 6.57 (1H, d, J = 2.6 Hz, coum), 6.75
(1H, dd, J3 = 9.4 Hz, J4 = 2.6 Hz, coum), 7.22 (1H, d,
J = 1.1 Hz, coum), 7.37 (1H, dd, J3 = 9.1 Hz, J4 = 2.5 Hz,
coum), 8.11 (1H, d, J = 4.7 Hz, coum), 8.40 (1H, d, J =
4.5 Hz, coum), 8.59 (2H, br s, β-H-pyrrole), 8.69 (2H, d,
J = 2.1 Hz, β-H-pyrrole), 8.83 (2H, d, J = 2.1 Hz, β-H-
pyrrole), 9.12 (2H, d, J = 2 Hz, β-H-pyrrole). MS (ESI):
m/z 1150.3 (calcd. for [M + Na]+ 1150.2).
Preparation of 4-((10-(diethylamino)-6,7-dioxo-6,
7-dihydrochromeno[3,4-c]chromen-3-yl)oxy)-2,3,5,6-
tetrafluorobenzaldehyde (34). Compound 33 (878 mg,
2.5 mmol) was dissolved in DMF (5 mL). Then cesium
fluoride (760 mg, 5 mmol) was added, followed by penta-
fluorobenzaldehyde (2, 310 μL, 2.5 mmol). After stirring
for 2 h, the reaction mixture was diluted with water and
stirring was continued for a further 30 min. After that, the
reaction mixture was extracted with dichloromethane.
The organic fractions were combined, washed with
water, brine and dried over MgSO4. After filtration, celite
was added and the solvent was removed under reduced
pressure. The product was chromatographed on a short
CONCLUSION
Our studies have clearly documented the ability of a
[2+1] strategy to assemble meso-linked corrole-coumarin
dyads. The target compounds were obtained either in a
one-pot synthesis from dipyrromethanes and formyl-cou-
marins or via Sonogashira coupling of ethynylcorroles
with halogenocoumarins. The competitive Michael addi-
tion of dipyrromethanes to the α,β-unsaturated system of
Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 1021–1023

1022 M. TaSIOr et al.
coumarin most probably diminished the yield of corroles.
Copper-free Sonogashira coupling can be used for the
construction of bis-coumarin-corrole dyads. The spec-
troscopic properties of all dyads studied suggest that the
components are weakly electronically coupled.
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Acknowledgements
This work was funded by the Foundation for Polish
Science (TEAM-2009-4/3).
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