Efficient access to β-vinylporphyrin derivatives via palladium cross coupling of β-bromoporphyrins with N-tosylhydrazones

Article abstract of DOI:10.3762/bjoc.13.22

This work describes a new approach to obtain new β-vinylporphyrin derivatives through palladium-catalyzed cross-coupling reaction of 2-bromo-5,10,15,20-tetraphenylporphyrinatozinc(II) with N-tosylhydrazones. This is the first report of the use of such synthetic methodology in porphyrin chemistry allowing the synthesis of new derivatives, containing β-arylvinyl substituents.

Full text of DOI:10.3762/bjoc.13.22

Efficient access to β-vinylporphyrin derivatives via palladium
cross coupling of β-bromoporphyrins with N-tosylhydrazones
Vinicius R. Campos1,2, Ana T. P. C. Gomes*2, Anna C. Cunha*1,
Maria da Graça P. M. S. Neves2, Vitor F. Ferreira1 and José A. S. Cavaleiro*2
Full Research Paper
Open Access
Address:
Beilstein J. Org. Chem. 2017, 13, 195–202.
1Departamento de Química Orgânica, Instituto de Química,
Universidade Federal Fluminense, 24020-150 Niterói, RJ, Brazil and
2QOPNA and Department of Chemistry, University of Aveiro,
3810-193 Aveiro, Portugal
doi:10.3762/bjoc.13.22
Received: 20 October 2016
Accepted: 11 January 2017
Published: 30 January 2017
Email:
Ana T. P. C. Gomes* - ana.peixoto@ua.pt; Anna C. Cunha* -
annac@vm.uff.br; José A. S. Cavaleiro* - jcavaleiro@ua.pt
Dedicated to the memory of Professor José Barluenga, OviedoUniversity,
Oviedo, Spain.
* Corresponding author
Associate Editor: B. Stoltz
Keywords:
© 2017 Campos et al.; licensee Beilstein-Institut.
License and terms: see end of document.
N-tosylhydrazones; Pd-catalyzed cross coupling; porphyrins
Abstract
This work describes a new approach to obtain new β-vinylporphyrin derivatives through palladium-catalyzed cross-coupling reac-
tion of 2-bromo-5,10,15,20-tetraphenylporphyrinatozinc(II) with N-tosylhydrazones. This is the first report of the use of such syn-
thetic methodology in porphyrin chemistry allowing the synthesis of new derivatives, containing β-arylvinyl substituents.
Introduction
Porphyrin-type heterocycles are well known for their special into the macrocycles, affording in such way important interme-
role in several scientific fields, including medicine [1-3] , supra- diates for different synthetic strategies [4,17,18].
molecular chemistry [4-6] and catalysis [7-10]; their functional-
ization became a target for several research groups [11-13]. In There are methods available allowing the insertion of alkenyl
particular, the insertion of functional groups into the macro- groups into porphyrin macrocycles (e.g., Heck reaction [4], me-
cyclic core merits considerable attention due to the diversity of tathesis [7,19-21], Wittig reaction [22,23]). However, palla-
structural features that can be induced in the porphyrin struc- dium-catalyzed cross-coupling reaction between N-tosylhydra-
ture [14-16].
zones and aryl halides seems to be a powerful method to
synthesize new alkene-type derivatives [24,25]. This methodol-
Alkenyl-type moieties are examples of versatile functional ogy allowed the development of novel protocols enabling trans-
groups which are present in several biologically active natural formations that are difficult to achieve with other reactions and
porphyrin derivatives or are substituents that can be introduced include other important features – stoichiometric organometal-
195

Beilstein J. Org. Chem. 2017, 13, 195–202.
lic reagents are not required for the coupling reaction and di- sible N-tosylhydrazones 2a–c (Scheme 3). Both substrates were
and trisubstituted olefins can be prepared with high stereoselec- prepared by following literature procedures; the halide partner
tivity. In fact, N-tosylhydrazones used in this methodology can by controlled bromination of 5,10,15,20-tetraphenylporphyrin
be easily prepared from carbonyl compounds (Scheme 1), as it (TPP) with N-bromosuccinimide followed by metallation with
has been well demonstrated by Barluenga and co-workers Zn(AcO)2 [31,32] and the tosylhydrazones 2a–c by reaction
[11,26,27].
of the adequate ketones with tosylhydrazines [33]. The use
of the porphyrin zinc complex avoids the complexation
of the tetrapyrrolic macrocycle with Pd(II) formed during
the catalytic cycle, and in this way prevents the loss of the cata-
lyst.
In the first experiments, the reactions between 2-bromo-
5,10,15,20-tetraphenylporphyrinatozinc(II) (1) and the N-tosyl-
hydrazone derivatives 2a–c were performed in the presence of
Pd(PPh3)4 as catalyst, KOt-Bu as base and 2-dicyclohexylphos-
phino-2’,4’,6’-triisopropylbiphenyl (Xphos) as ligand. All reac-
Scheme 1: Schematic representation of palladium-catalyzed cross-
coupling reaction between aryl halides and N-tosylhydrazones.
This methodology allowed the development of novel protocols tions were carried out in a sealed Schlenk tube in toluene and
enabling transformations that are difficult to achieve with other dioxane at 120 °C under conventional heating and anhydrous
reactions and include other important features as: stoichio- air-free conditions (Scheme 3) and stopped when the TLC
metric organometallic reagents are not required for the cou- controls showed no more evolution of the reaction progress.
pling reaction.
Having in mind the possible self-reaction of tosylhydrazone 2b,
a process competing with the required reaction of 2b with
Interestingly, this methodology has never been applied to the bromoporphyrin, it was decided to use an excess of the tosylhy-
synthesis of porphyrin derivatives containing alkenyl groups at drazone.
β-pyrrolic positions. Having this in mind and following our
interest in the development of synthetic approaches to prepare The results obtained after the work up and chromatographic
novel porphyrin derivatives [28-30], we decided to explore the purification are summarized in Scheme 3 and Table 1 (entries 1,
palladium-catalyzed cross-coupling reaction of meso- 2 and 3). Under these conditions, the expected β-substituted
tetraphenyl-β-bromoporphyrin using N-tosylhydrazone deriva- vinylporphyrin derivatives 3a–c were obtained in 22–25%
tives with different electronic features for the preparation of yields. No significant differences between the reactivity of the
new β-alkenyl-type porphyrin derivatives. This approach can used N-tosylhydrazones 2a–c were observed. The major com-
provide interesting compounds with potential biological proper- pounds isolated in these conditions were the starting porphyrin
ties or might become important templates for further functional- 1 and the zinc(II) complex of TPP (ZnTPP) resulting from the
ization procedures (Scheme 2).
debromination of porphyrin 1.
Results and Discussion
The reductive removal of the halo moiety has been already de-
For this work 2-bromo-5,10,15,20-tetraphenylporphyrinato- scribed in the literature for other palladium-catalyzed cross-cou-
zinc(II) (1) was used as the aryl halide and also the easily acces- pling reactions [34-36], namely in some reactions involving
Scheme 2: A retrosynthetic scheme for the synthesis of β-alkenyl-type porphyrin derivatives from the Zn(II) complex of β-bromo-meso-tetraphenylpor-
phyrin and N-tosylhydrazones.
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Beilstein J. Org. Chem. 2017, 13, 195–202.
Scheme 3: Palladium catalysed cross-coupling reactions between β-brominated porphyrin 1 and N-tosylhydrazones 2a–c.
halogenated porphyrin derivatives [37]. Presumably in this par- lyst to tris(dibenzylideneacetone)dipalladium(0), [Pd2(dba)3],
ticular case the lack of efficiency of the catalytic system is prob- and the base to lithium tert-butoxide, led to the same low effi-
ably responsible for this secondary reaction. Attempts to ciency. This fact prompted us to select the catalytic system de-
improve the efficiency of the process just by changing the cata- scribed by Wang et al. [38]. In their work the authors reported
Table 1: Results obtained in the palladium-catalyzed cross-coupling reactions between β-brominated porphyrin 1 with N-tosylhydrazones 2a–c.
Conventional heating
Entry
N-Tosyl-
hydrazone 2
Base
Co-catalyst
Solvent
Reaction
time
η 3 (%)
% 1 recov.
% ZnTPP
toluene/
dioxane
1
2
3
4
5
6
a
b
c
a
b
c
KOt-Bu
KOt-Bu
KOt-Bu
Cs2CO3
Cs2CO3
Cs2CO3
XPhos
XPhos
XPhos
Et4NBr
Et4NBr
Et4NBr
24 h
24 h
24 h
4 h
23
22
25
89
82
86
30
28
31
<1
10
9
35
30
32
–
toluene/
dioxane
toluene/
dioxane
toluene/
DMF
toluene/
DMF
4 h
–
toluene/
DMF
4 h
–
MW irradiation
Solvent
Entry
N-Tosyl-
hydrazone 2
Base
Co-catalyst
Reaction
time
η 3 (%)
% 1 recov.
% ZnTPP
toluene/
DMF
7
8
9
a
b
c
Cs2CO3
Cs2CO3
Cs2CO3
Et4NBr
Et4NBr
Et4NBr
5 min
5 min
5 min
69
59
64
15
22
18
–
–
–
toluene/
DMF
toluene/
DMF
197

Beilstein J. Org. Chem. 2017, 13, 195–202.
an efficient methodology for the palladium-catalyzed cross-cou- which is assigned to the resonance of five β-pyrrolic protons
pling reaction of electron-deficient aryl halides with aryl and an AB system at 8.81 and 8.60 ppm (J = 4.7 Hz) due to the
N-tosylhydrazones. In such a way, under these new conditions, β-pyrrolic protons H-12 and H-13. The resonances of the ortho
the reactions between β-bromonated porphyrin 1 and N-tosylhy- protons (H-o-Ph) and of the meta and para protons (H-m,p-Ph)
drazone derivatives 2a–c were performed in the presence of of the C5, C10 and C15 phenyl groups appear as two multiplets
Pd(PPh3)4 (5 mol %), 3 equivalents of Cs2CO3 and 20 mol % of at 7.79–7.67 ppm and 7.24–7.17 ppm, respectively. Due to the
Et4NBr as the co-catalyst, using as solvent a mixture of toluene lack of rotation of the phenyl group at the C20 position, its
and DMF at 120 °C (Table 1, entries 4, 5 and 6). The results H-o-Ph protons appear as a broad signal at 7.57 ppm. Through
show that under these conditions and after 4 h of reaction, the COSY correlations it is possible to identify the H-m-Ph of the
β-alkenylporphyrin derivatives 3a–c were obtained in remark- same group as a broad signal at 7.20 ppm and the H-p-Ph as a
able yields (86–89%). Under these conditions the desired prod- triplet at 7.49 ppm (J = 7.5 Hz). The resonances of the protons
ucts were obtained in much better yields and in shorter reaction H-4’, 5’, 7’, 8’ of the extra Ph group at the β-pyrrolic position
times. Additionally, the presence of ZnTPP was not detected in appear as a multiplet at 6.97–6.83 ppm. The correlation ob-
these circumstances and porphyrin 1 was recovered in low served in the COSY spectrum between this multiplet and the
amounts (between 0 and 10%). These results confirmed that the triplet at 7.07 ppm (J = 7.1 Hz) allowed to attribute unequivo-
improvement of the catalytic efficiency is responsible for cally this resonance to H-6’. Finally, the resonances of the two
diminishing the competitive process that induces the debromi- germinal protons H-2’ of the olefin unit appear as two doublets
nation of porphyrin 1.
(J = 1.3 Hz) at 5.81 and 5.56 ppm. The value of the coupling
constant and the unique correlation of these two protons with a
Still looking for lower reaction times, we decided to use the single carbon (115.5 ppm) observed in HSQC spectra corrobo-
latter reactional conditions but under microwave (MW) irradia- rates the proposed structure. The HRMS–ESI+ spectrum of de-
tion (Table 1, entries 7, 8 and 9). The reactions were carried out rivative 3a shows a molecular ion at the m/z value 779.2135
under 200 W for 5 minutes at 120 °C. The results obtained corresponding to [M + H]+ which confirms also the success of
show that, under MW radiation, β-alkenylporphyrin derivatives the palladium cross-coupling strategy.
3a–c were obtained in reasonable yields (between 59 and 69%)
and it was possible to recover ca. 20% of porphyrin 1. The use For derivative 3b and considering only the resonances due to
of MW irradiation did not bring any improvement in the present the extra group introduced at the β-pyrrolic position, the reso-
porphyrin derivatives syntheses.
nance of the two protons H-2’ appears as two doublets at 5.78
and 5.60 ppm (J = 0.9 Hz). Once again, the value of the cou-
We believe that the mechanism of the formation of the pling constant and the unique correlation of these protons with a
β-alkenylporphyrin derivatives 3a–c follows the one reported single carbon (115.9 ppm) observed in the HSQC spectra vali-
by Barluenga [13,39-42].
dates that H-2’ are geminal protons. The two doublets at 7.04
and 6.71 ppm (J = 8.8 Hz) are related to the resonance of
H-4’,8’ and H-5’,7’ of the bromophenyl group, respectively.
The same profile is observed in 1H NMR of derivative 3c,
Structural characterization of the new β-vinyl-
porphyrin derivatives 3a–c
The structures of the new β-vinylporphyrin derivatives 3a–c where the resonance of H-2’ appears as two doublets at 5.67
were assigned on the basis of their 1H and 13C NMR spectra and 5.45 ppm (J = 1.0 Hz) and H-4’,8’ and H-5’,7’ appear as
and their molecular formulae were confirmed by HRMS–ESI+. two doublets at 6.76 and 6.42 ppm (J = 8.9 Hz), respectively. It
2D NMR spectra [COSY, HMBC, HSQC] were also obtained is also possible to observe a singlet at 3.61 ppm related to the
to unequivocally identify proton and carbon resonances (see resonance of the protons of the methoxy group.
Supporting Information File 1).
The HRMS–ESI+ of β-vinylporphyrin derivatives 3b and 3c
The 1H NMR spectra of porphyrin derivatives 3a–c show the show molecular ions at the m/z values of 856.1160 and
same type of profile; the principal differences are seen in the 808.2174 (M+•) respectively, confirming the molecular formula
resonances of the protons and carbon centres of the aryl group of these derivatives.
inserted by the palladium-catalyzed coupling reaction.
All the new porphyrins 3a–c were also characterized by UV–vis
As a representative example, Figure 1 shows the 1H NMR spec- spectroscopy, showing the typical profile of the Zn(II) complex
trum of the β-vinylporphyrin 3a and the most important COSY of meso-tetraarylporphyrins, with a Soret band at ca. 420 nm
correlations. The spectrum is consistent with a β-substituted and two Q bands between 549 and 586 nm (See Supporting
porphyrin structure showing a multiplet between 8.98–8.90 ppm Information File 1).
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Beilstein J. Org. Chem. 2017, 13, 195–202.
Figure 1: 1H NMR of β-alkenylporphyrin derivative 3a. Green arrows illustrate principal COSY correlations.
Conclusion
literature procedures [15,16]. 1H and 13C NMR spectra were re-
In summary, we have reported the efficient synthesis of new corded on a Bruker Avance 300 spectrometer at 300.13 and
β-alkenyl-type porphyrin derivatives through Pd-catalyzed 75.47 MHz and on a Bruker Avance 500 spectrometer at 500.12
cross-coupling reaction of β-bromoporphyrinatozinc(II) com- and 125.77 MHz. CDCl3 was used as solvent and tetramethyl-
plex with N-tosylhydrazones. The best conditions for the reac- silane (TMS) as internal reference. Chemical shifts are
tion of 2-bromo-5,10,15,20-tetraphenylporphyrinatozinc(II) (1) expressed in δ (ppm) and the coupling constants (J) are
and N-tosylhydrazone derivatives 2a–c gave rise to the new expressed in Hertz. Mass spectra HRMS were recorded on a
β-alkenylporphyrin derivatives 3a–c in excellent yields (be- LTQ Orbitrap XL mass spectrometer (Thermo Fischer Scien-
tween 86–89%). This is the first report using this methodology tific) using CHCl3 as solvent. For the reactions under MW irra-
in the functionalization of tetrapyrrolic macrocycles. The new diation a CEM Microwave Synthesis System Discover SP was
compounds that can be achieved by this approach can be excel- used, under constant magnetic stirring (controlled by the micro-
lent templates for further functionalization and also might be- wave equipment) by employing an irradiation power of 200 W
came compounds with potential important biological activities. till the reaction temperature (120 °C) was achieved. The
This new methodology can be used to have access to a signifi- UV–vis spectra were recorded on an UV-2501 PC Shimadzu
cant number of new porphyrin derivatives and certainly future spectrophotometer using CHCl3 as solvent. Flash chromatogra-
work will demonstrate this fact.
phy was carried out using silica gel (230–400 mesh) and
preparative thin-layer chromatography was carried out
on 20 × 20 cm glass plates coated with silica gel (1 mm
thick). The reactions were routinely monitored by thin-
Experimental
Materials and methods
2-Bromo-5,10,15,20-tetraphenylporphyrinatozinc(II) (1) and layer chromatography (TLC) on silica gel precoated F254 Merck
N-tosylhydrazone derivatives 2a–c were prepared according to plates.
199

Beilstein J. Org. Chem. 2017, 13, 195–202.
General procedures for synthesis of β-alkenyl Structural characterization of β-alkenylpor-
porphyrin derivatives 3a–c
phyrin derivatives 3a–c
Using Pd(PPh3)4, XPhos and KOt-Bu as catalytic
2-(1-Phenylethenyl)-5,10,15,20-tetraphenylporphyri-
system under conventional heating
natozinc(II) (3a)
2-Bromo-5,10,15,20-tetraphenylporphyrinatozinc(II) (1, 20 mg,
26.4 µmol), Pd(PPh3)4 (2 mol %), XPhos ligand (10 mol %,
2.64 µmol, 1.2 mg), N-tosylhydrazones 2a–c (1 equiv,
26.4 µmol), KOt-Bu (2.5 equiv, 66 µmol, 7.4 mg) were placed
in a 50 mL Schlenk tube and dissolved in 5 mL of toluene and
5 mL of dioxane. The solvent was degassed by repeated sonica-
tion for 1–2 min under reduced pressure. The reaction mixture
was stirred during 24 h at 120 °C. After cooling, the reactions
were quenched with water, extracted with toluene and each
organic layer was washed with water, dried in Na2SO4 and
concentrated under reduced pressure. Each crude mixture was 1H NMR (300 MHz, CDCl3) δ 8.98–8.90 (m, 5H, β-H), 8.81
purified by preparative TLC using hexane/CH2Cl2 (1:1) as the and 8.60 (AB system, J = 4.7 Hz, 2H, H-12 and H-13),
eluent in each case.
8.29–8.16 (m, 6H, H-Ph-o-5,10,15), 7.79–7.67 (m, 9H, H-Ph-
m,p-5,10,15), 7.57 (bs, 2H, H-Ph-o-20), 7.49 (t, J = 7.5 Hz, 1H,
H-Ph-p-20), 7.20 (bs, 2H, H-Ph-m-20), 7.07 (t, J = 7.1Hz, 1H,
H-6’), 6.97–6.83 (m, 4H, H-4’,5’,7’,8’), 5.81 (d, J = 1.3 Hz, 1H,
Using Pd(PPh3)4, Et4NBr and Cs2CO3 as catalytic
system under conventional heating
In a two neck round-bottom flask under nitrogen H-2’), 5.56 (d, J = 1.3 Hz, 1H, H-2’); 13C NMR (126 MHz,
atmosphere were placed 2-bromo-5,10,15,20-tetraphenylpor- CDCl3) δ 151.4, 150.4, 150.3, 150.2, 150.2, 150.1, 150.0,
phyrinatozinc(II) (1, 20 mg, 26.4 µmol) and the N-tosylhydra- 148.1, 147.2, 146.2, 145.6, 142.9, 142.7, 141.2, 140.8, 136.1
zones 2a–c (2 equiv, 52.8 µmol). These solids were maintained (β-C), 135.5 (C-Ph-o-5,10,15), 134.5 (C-Ph-o-5,10,15), 134.46
under nitrogen flux during 5 minutes. Pd(PPh3)4 (5 mol %, (C-Ph-o-5,10,15), 134.41 (C-Ph-o-5,10,15), 132.7 (C-12 or
1.32 µmol, 1.5 mg), Cs2CO3 (3 equiv, 79.2 µmol, 27.9 mg) and C-13), 132.1 (β-C), 132.0 (β-C), 131.99 (β-C), 131.91 (β-C),
Et4NBr (20 mol %, 5.28 µmol, 1.10 mg) were then added and 131.4 (C-12 or C-13), 127.5, 127.5, 127.4, 127.1, 127.0, 126.6,
the obtained mixture in each case was dissolved in toluene 126.56, 126.1, 125.5 (C-Ph-m-20), 122.3, 121.4, 121.0, 120.4,
(1 mL) and DMF (0.5 mL). The reactions were maintained at 115.5 (C-2’); UV–vis (CH2Cl2) λmax (log ε): 422 (5.30) 549
120 °C for 4 h. After cooling, the reactions were quenched with (3.95) 586 (3.15) nm; HRMS–ESI: m/z: [M + H]+ calcd for
water, extracted with toluene and the organic layers were C52H35N4Zn+, 779.2147; found, 779.2135.
washed with water, dried in Na2SO4 and concentrated
under reduced pressure. The crude mixtures were 2-[1-(4-Bromophenyl)ethenyl]-5,10,15,20-tetra-
purified by preparative TLC hexane/CH2Cl2 (1:1) as the phenylporphyrinatozinc(II) (3b)
eluents.
Using Pd(PPh3)4, Et4NBr and Cs2CO3 as catalytic
system under MW irradiation
In a MW reactor were placed 2-bromo-5,10,15,20-tetraphenyl-
porphyrinatozinc(II) (1, 20 mg, 26.4 µmol), N-tosylhydrazones
2a–c (2 equiv, 52.8 µmol), Pd(PPh3)4 (5 mol %, 1.32 µmol,
1.5 mg), Cs2CO3 (3 equiv, 79.2 µmol, 27.9 mg) and Et4NBr
(20 mol %, 5.28 µmol, 1.10 mg). The obtained mixtures were
dissolved in toluene (1 mL) and DMF (0.5 mL). The reactions
were irradiated under MW radiation under 200 W for 5 minutes
at 120 °C. After cooling, the reactions were quenched with 1H NMR (300 MHz, CDCl3) δ 9.02–8.85 (m, 5H, β-H), 8.81
water, extracted with toluene and each organic layer was and 8.60 (AB system, J = 4.7 Hz, 2H, H-12 and H-13),
washed with water, dried in Na2SO4 and concentrated under 8.36–8.01 (m, 6H, H-Ph-o-5,10,15), 7.76–7.71 (m, 9H, H-Ph-
reduced pressure. The final reaction mixtures were purified by m,p-5,10,15), 7.51 (t, J = 7.6 Hz, 1H, H-Ph-p-20), 7.53–7.48
preparative TLC using hexane/CH2Cl2 (1:1) as the eluent in (m, 2H, H-Ph-o-20), 7.40–7.37 (m, 2H, H-Ph-m-20), 7.04 (d,
each case.
J = 8.8 Hz, 2H, H-4’,8’), 6.71 (d, J = 8.8 Hz, 2H, H-5’,7’), 5.78
200

Beilstein J. Org. Chem. 2017, 13, 195–202.
(s, 1H, H-2’), 5.60 (s, 1H, H-2’); 13C NMR (75 MHz, CDCl3) Acknowledgments
δ 151.4, 150.5, 150.3, 150.3, 150.25, 150.10, 147.9, 146.8, We would like to thank the University of Aveiro, the “Fundação
145.4, 144.8, 142.9, 142.8, 142.72, 141.2, 139.7, 136.1, 134.5 para a Ciência e a Tecnologia” (FCT), the European Union,
(C-Ph-o-5,10,15), 134.4 (C-Ph-o-5,10,15), 132.8 (C-Ph-o- QREN, FEDER and COMPETE for funding the QOPNA
5,10,15), 132.2 (C-Ph-o-5,10,15), 132.1 (C-12 or C-13), 132.0 research unit (project PEst-C/QUI/UI0062/2013) and the
(β-C), 131.9 (β-C), 131.5 (β-C), 131.2 (β-C), 130.5 (β-C), 129.8 Portuguese National NMR Network (RNRMN). A. T. P. C.
(C-12 or C-13), 131.4, 131.3, 131.2, 130.4 (C-4’,8’), 129.7, Gomes also thanks FCT for her research grant (SFRH/BPD/
129.4, 127.7 (C-5’,7’), 127.5, 127.2, 126.6, 126.7, 122.0, 121.5, 79521/2011). Thanks are also due to the “Universidade Federal
121.1, 121.0, 120.4, 116.0 (C-2’); UV–vis (CH2Cl2) λmax (log Fluminense”, (Niterói, RJ, Brazil) and the Brazilian agencies
ε): 422 (5.22) 549 (3.89) 586 (3.21) nm; HRMS–ESI: m/z: M+• CNPq, CAPES and FAPERJ for funding. V. R. Campos thanks
calcd for C52H33BrN4Zn, 856.1174; found, 856.1160.
CAPES for his research grant and for funding his research stay
at the University of Aveiro.
2-[1-(4-Methoxyphenyl)ethenyl]-5,10,15,20-tetra-
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1H NMR (300 MHz, CDCl3) δ 8.97–8.88 (m, 5H, β-H), 8.81
and 8.61 (AB system, J = 4.7 Hz, 2H, H-12 and H-13),
8.28–8.16 (m, 6H, H-Ph-o-5,10,15), 8.06 (bs, 2H, H-Ph-o-20)
7.78–7.67 (m, 11H, H-Ph-m,p-5,10,15 + H-Ph-m-20), 7.48 (t,
J = 7.5 Hz, 1H, H-Ph-p-20), 6.76 (d, J = 8.9 Hz, 2H, H-4’,8’),
6.42 (d, J = 8.9 Hz, 2H, H-5’,7’), 5.67 (d, J = 1.0 Hz, 1H, H-2’),
5.45 (d, J = 1.0 Hz, 1H, H-2’), 3.61 (s, 3H, OCH3); 13C NMR
(126 MHz, CDCl3) δ 158.9, 151.4, 150.39, 150.3, 150.2, 150.1,
149.9, 148.2, 147.3, 146.5, 145.0, 142.9, 142.8, 141.2, 135.9
(β-C), 134.5, 134.48, 134.43, 134.0, 132.7 (C-12 or C-13),
132.1 (β-C), 132.0 (β-C), 131.9 (β-C), 131.8 (β-C), 131.4 (C-12
or C-13), 127.53, 127.50 (C-4’,8’), 127.3, 127.0, 126.6, 126.5,
125.5, 122.3, 121.4, 121.0, 120.3, 113.8 (C-2’), 112.7 (C-5’,7’),
55.2 (OCH3); UV–vis (CH2Cl2) λmax (log ε): 421 (5.90) 550
(4.19) 587 (3.46) nm. HRMS–ESI: m/z: M+• calcd for
C53H36N4OZn, 808.2175; found, 808.2174.
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Supporting Information
Supporting Information File 1
Copies of NMR, HRMS(ESI) and UV–vis spectra of the
new derivatives.
[http://www.beilstein-journals.org/bjoc/content/
supplementary/1860-5397-13-22-S1.pdf]
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