Insights into the Synthesis and the Solution Behavior of meso-Aryloxy- and Alkoxy-Substituted Porphyrins

Article abstract of DOI:10.1002/ejoc.201500628

meso-RO-appended (R = alkyl, aryl) porphyrins bearing one or two OR substituents at the tetrapyrrolic macrocycle were synthesized in good yields from 5,15-dibromo-10,20-diphenylporphyrins 2H(Br₂DPP), Ni(Br₂DPP) and Zn(Br₂DPP) using an S_NAr reaction. By varying the solvent, the base, the temperature, and the time of the reaction, the optimum conditions were established, and the selective introduction of one or two meso-RO substituents at the periphery of the macrocycle was achieved. Moreover, monofunctionalization of Ni(Br₂DPP) according to an S_NAr reaction was used as a key step for the synthesis of rarely explored unsymmetrical porphyrinyl alkyl ethers. ¹H NMR studies of these ethers in CDCl₃ revealed concentration-dependent aggregation of the zinc derivative through coordination of the central metal ion of one molecule to the peripheral oxygen atom of a second tetrapyrrolic macrocycle.

Full text of DOI:10.1002/ejoc.201500628

FULL PAPER
DOI: 10.1002/ejoc.201500628
Insights into the Synthesis and the Solution Behavior of meso-Aryloxy- and
Alkoxy-Substituted Porphyrins
Kirill P. Birin,*[a] Yulia G. Gorbunova,[a,b] Aslan Yu. Tsivadze,[a,b] Alla G. Bessmertnykh-
Lemeune,[c] and Roger Guilard*[c]
Keywords: Nucleophilic substitution / Homogeneous catalysis / Self-assembly / Porphyrinoids / Alcohols
meso-RO-appended (R = alkyl, aryl) porphyrins bearing one
or two OR substituents at the tetrapyrrolic macrocycle were
synthesized in good yields from 5,15-dibromo-10,20-di-
phenylporphyrins 2H(Br2DPP), Ni(Br2DPP) and Zn(Br2DPP)
using an SNAr reaction. By varying the solvent, the base, the
temperature, and the time of the reaction, the optimum con-
ditions were established, and the selective introduction of
one or two meso-RO substituents at the periphery of the
macrocycle was achieved. Moreover, monofunctionalization
of Ni(Br2DPP) according to an SNAr reaction was used as a
key step for the synthesis of rarely explored unsymmetrical
porphyrinyl alkyl ethers. 1H NMR studies of these ethers in
CDCl3 revealed concentration-dependent aggregation of the
zinc derivative through coordination of the central metal ion
of one molecule to the peripheral oxygen atom of a second
tetrapyrrolic macrocycle.
formyl-substituted derivatives. Depending on the structural
parameters of the porphyrins, both electrophilic and nucle-
ophilic aromatic substitution reactions can be applied for
the synthesis of target molecules.[10] However, nucleophilic
aromatic substitution (SNAr) reactions usually require dras-
tic conditions to proceed.[13–21] Therefore, transition-metal-
catalyzed reactions were developed as an alternative route
to carry out the reactions of haloporphyrins with nucleo-
philes[11,12,22–28] but these reactions also suffer serious draw-
backs such as a limited substrate tolerance, the need for
specific and expensive ligands, high catalyst loading and
time-consuming optimization of experimental conditions;
furthermore, difficulties are encountered in reproduction
and upscale experiments, and because of contamination of
products by toxic metals. For these reasons, it is perhaps
not surprising that SNAr reactions as a tool for the prepara-
tion of C-, O-, S- and N-substituted porphyrins have re-
cently been revisited.[1–8,29–33] However, most of these SNAr
reactions involve NiII porphyrinates or amines as nucleo-
philes. It is well known that NiII porphyrinates afford func-
tionalized compounds that do not tolerate the drastic con-
ditions of a demetallation reaction and, consequently, are
not very useful for the preparation of various porphyrin
complexes that are needed for the myriad practical applica-
tions. Thus, SNAr reactions still require further develop-
ment before they can be used for efficient functionalization
of porphyrins.
Introduction
Tetrapyrrolic ligands are widely used in Nature and, in
the last century, there has been impressive developments in
this field, with porphyrin complexes now being considered
as potential candidates for practical use in solar energy
transformations, medicinal chemistry, photocatalysis and so
forth.[1–8] To answer increasing demands of physicists,
biologists, and engineers, efficient synthetic approaches for
the functionalization of the macrocyclic periphery of por-
phyrins is required because it was recognized that this is
one of the simplest and most efficient ways to modulate the
properties of metalloporphyrinates and to elaborate multi-
porphyrinic arrays or supramolecular assemblies. Consider-
able efforts have therefore been devoted to the synthesis of
such structures and these have revealed the key role of post-
functionalization strategies for the preparation of por-
phyrins.[9–12] This approach relies on the rich and unique
chemistry of tetrapyrrolic macrocycles, which can be easily
transformed into useful synthons such as halo-, nitro- and
[a] A. N. Frumkin Institute of Physical Chemistry and
Electrochemistry RAS,
Leninsky prosp. 31, bldg. 4, Moscow 119071, Russia
E-mail: kirill.birin@gmail.com
http://eng.phyche.ac.ru/
[b] N. S. Kurnakov Institute of General and Inorganic Chemistry
RAS,
Leninsky prosp. 31, Moscow 119991, Russia
[c] Institut de Chimie Moleculaire de l’Université de Bourgogne,
Université de Bourgogne, UMR CNRS 6302,
9, avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France
E-mail: Roger.Guilard@u-bourgogne.fr
In parallel with other groups,[9–12,29,32,34] in this work, we
have investigated the use of catalyst-free C–O bond-forming
reactions to prepare rarely studied but useful[10,28,35] meso-
RO-substituted (R = alkyl, aryl) porphyrins. To expand the
scope of the nucleophilic substitution reaction for the syn-
thesis of porphyrins, we studied the reaction of
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meso-Aryloxy- and Alkoxy-Substituted Porphyrins
2H(Br2DPP), Zn(Br2DPP) and Ni(Br2DPP) (M-1, M = 2H, porphyrinyl alkyl ethers form supramolecular assemblies re-
Zn and Ni), which are readily available[36,37] and can afford sulting from axial binding of the oxygen atom of the alkoxy
mono- or di-OR-substituted porphyrins M-2 and M-3 upon group from one porphyrin molecule to the metal center of
reaction with alcohols (Scheme 1).
a second molecule. This coordination-driven self-assembly
is of interest for crystal engineering and material chemistry.
Results and Discussion
To access the potential of the SNAr reaction for 5,15-
dibromoporphyrins M-1, we first investigated the reaction
of NiII complex Ni-1 with phenols and primary alcohols
(Scheme 2); the results are summarized in Table 1.
Scheme 1. SNAr reactions of M(Br2DPP).
Table 1. SNAr reaction of Ni-1 with O-nucleophiles.[a]
However, achieving selectivity is challenging for both
transformations. Indeed, the first selective substitution of
the bromine atom leading to M-2 is limited because of the
drastic conditions required for the reaction. Furthermore,
the second substitution reaction, affording M-3, is hindered
by the strong electron-donating alkoxy substituent. To our
knowledge, only one example of the catalyst-free double nu-
cleophilic substitution is described for 5,15-dibromopor-
phyrins, namely the reaction of Zn-1 (Ar = 3,5-di-tBu-
C6H3) with morpholine.[20,21] In the context of our project
on metal-organic materials, we were interested in por-
phyrins decorated by aryloxy and long-chain alkoxy groups.
The primary alcohols react with difficulty with aromatic
halides according to transition-metal-catalyzed reactions,
and sophisticated ligands are needed to obtain these com-
pounds in moderate to good yields.[11,12,22–28] Therefore, the
development of catalyst-free conditions were of particular
interest for these reactions.
ROH [equiv.]
Solvent
T
t
Yield [%][b]
[°C] [h] Ni-1 Ni-2 Ni-3
1
2
3
4
5
6
7
8
9
PhOH (15)
2,6-Me2C6H3OH (15)
2,6-iPr2C6H3OH (15)
DMA 120
DMA 120
DMA 120
1
1
6
6
6
6
3
3
1
6
0
0
0
0
0
0
13
0
0
0
0
0
42
50
72
77
17[c]
0
62
0
0
0
0
0
2,6-tBu2-4-Me-C6H2OH (15) DMA 120
BnOH (80)
HexOH (66)
HexOH (66)
HexOH (66)
HexOH (66)
DMA 120
DMA 120
DMA 120
diglyme 120
diglyme 170
diglyme 145
33[d] 66[d]
36[d] 46[d,e]
10 HexOH (66)
6
57
[a] Reaction conditions: suspension of Ni-1 (50 mg, 0.074 mmol),
an excess of alcohol and Cs2CO3 (72 mg, 3 equiv.), solvent
(9.4 mL), heated under Ar. [b] Isolated yield. [c] Isolated as a mix-
ture with 2,6-iPr2C6H3OH (1:1). The yield was determined by
NMR spectroscopic analysis. [d] Determined by MALDI-TOF MS
analysis. [e] Ni-4f (18%) was also observed by MALDI-TOF MS
analysis.
Here, we report the optimum conditions that were devel-
oped to obtain mono- and di-OR-substituted porphyrins
The catalyst-free nucleophilic substitution of a bromine
from 5,15-dibromoporphyrins M-1. Moreover, we demon- atom by phenol was described for activated aromatic com-
strate that mono-substituted derivatives M-2, bearing a pounds[38] and for nickel(II) 5-bromoporphyrinates while
bromine substituent, are convenient precursors for Pd-cata- our work was in progress.[29] Ni-1 also reacted smoothly
lyzed cross-coupling reactions leading to a series of little- with an excess (15 equiv.) of phenol in the presence of
studied porphyrinyl alkyl ethers. Our preliminary studies on Cs2CO3 (3 equiv.) in DMA at 120 °C and afforded di-OR-
1
the solution aggregation of ethers M-2 by using H NMR substituted porphyrin Ni-3a in 72% yield (100% conver-
spectroscopy, are also described. These data indicate that sion) after 1 h (Table 1, entry 1). Under these conditions,
Scheme 2. SNAr reactions of Ni-1 with phenols and primary alcohols.
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2,6-dimethylphenol gave diether Ni-3b in 77% yield (en- hexanol also serves as a reducing agent, as in the case of
try 2). However, the same reaction using more sterically early reported reductions of aryl halides with alcohols in
hindered phenols was inhibited. 2,6-Diisopropylphenol af- the presence of transition-metal catalysts[39–41] and under
forded Ni-3c in only 17% yield after 6 h [20% conversion catalyst-free conditions.[39] When Ni-1 was treated with 1-
according to MALDI-TOF mass spectrometry (MS)] (en- hexanol at 145 °C, the side reaction was suppressed, and
try 3) and no reaction occurred with 2,6-di-tert-butyl-4- preparative chromatography of the reaction mixture gave
methylphenol (entry 4). It should be noted that monosub- Ni-2f in 57% yield (entry 10).
stituted products Ni-2a–d were never observed in these re-
actions.
Ni-2f can be used as a convenient precursor for various
nonsymmetrical meso-alkoxyporphyrins due to the presence
The reaction of Ni-1 with benzyl alcohol under analo- of reactive bromine in this molecule.[10] In this work, we
gous reaction conditions also gave only diether Ni-3e after investigated Pd-catalyzed cross-coupling reactions, which
6 h (entry 5). Despite full consumption of the starting por- are summarized in Scheme 3.
phyrin, Ni-3e was isolated in only 62% yield because the
Coupling of Ni-2f with (4-formylphenyl)pinacolborane
compound was unstable under the reaction conditions.
or (trimethylsilyl)acetylene, according to Suzuki–Myaura or
The reaction of Ni-1 with less acidic 1-hexanol and Sonogashira reactions, afforded Ni-5f and Ni-6f in 62 and
Cs2CO3 (3 equiv.) in DMA proceeded more slowly than 63% yield, respectively. Pd-catalyzed C–N bond-forming re-
with phenols. For example, when Ni-1 was treated with 1- actions seem to be more difficult because of the strong elec-
hexanol (66 equiv.), complete conversion was reached after tron-donating character of the alkoxy substituent. However,
6 h and a selective substitution of one bromine atom was the reaction with morpholine proceeded even in the pres-
observed according to MALDI-TOF MS (entry 6). Selec- ence of a typical Pd2dba3-BINAP precatalyst and Cs2CO3,
tive substitution of a bromine atom by O-nucleophiles in affording Ni-7f in 25% yield.
5,15-dibromoporphyrins is unusual but it was previously
These examples demonstrate that SNAr reactions of
observed in the reaction of nickel(II) 5,15-dibromopor- Ni(Br2DPP) are of interest for the preparation of por-
phyrinates with phenols in the presence of Ni-catalysts.[27] phyrinyl ethers, including unsymmetrical derivatives, which
Despite full conversion of Ni-1, ether Ni-2f was isolated in have attracted significant attention in the field of porphyrin
only 42% yield, indicating concomitant degradation of the science.[10,42] However, their application as a tool for por-
porphyrin macrocycle under the reaction conditions. A phyrin synthesis is limited by the drastic conditions re-
slightly higher yield of Ni-2f (50%) with 87% conversion quired for demetallation that needs to be performed prior
of Ni-1 was obtained when heating was stopped after 3 h to the preparation of various complexes. Indeed, the de-
(entry 7). Our attempts to optimize the product yield by metallation of NiII porphyrinates is only observed in the
using different solvents (N,N-dimethylformamide (DMF), presence of strong acids[43] and our numerous attempts to
o-dichlorobenzene, nitrobenzene, diglyme) and varying the obtain free-base porphyrins from Ni-2f and Ni-3a–c with-
temperature gave only moderate success. The best results out degradation of the porphyrin macrocycle were unsuc-
were obtained in diglyme after careful optimization of the cessful. For example, no demetallation reaction occurred
reaction temperature. In this solvent, at 120 °C, the reaction when Ni-2f was treated with trifluoroacetic acid (TFA) in
was slower than in DMA (entries 7 and 8). When the tem- chloroform, but the reaction with H2SO4 in CH2Cl2 led to
perature was increased to 170 °C the selectivity was lost and the hydrodebromination of Ni-2f and afforded Ni-4f ac-
a mixture of Ni-2f and Ni-4f was obtained even after 1 h, cording to MALDI-TOF MS analysis.
when complete conversion of Ni-1 was not yet reached (en-
Consequently, to obtain metal complexes of meso-alk-
try 9). It seems that, under these reaction conditions, 1- oxyporphyrins, the reactions of ZnII complexes
Scheme 3. Pd-catalyzed cross-coupling reactions of Ni-2f.
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meso-Aryloxy- and Alkoxy-Substituted Porphyrins
Zn(Br2DPP) (Zn-1) and free-base 2H(Br2DPP) (2H-1) with Table 3. SNAr reaction of 2H-1 with 1-hexanol.[a]
alcohols were studied (see Tables 2 and 3, Schemes 4 and
5). A significant difference in the reactivity of these com-
pounds and Ni(Br2DPP) was observed when these com-
pounds were treated with 1-hexanol, which was taken as a
model alcohol.
Entry Base [equiv.]
T [°C] t [h] Yield [%][b]
2H-1
2H-2f
2H-3f 2H-4f
1
2
3
Cs2CO3 (1)
Cs2CO3 (1)
Na2CO3 (3)
Cs2CO3 (3)
Na2CO3 (30)
Na2CO3 (30)
145
170
170
170
170
135
7
50
0
0
0
0
50
0
100 (64)
0
0
0
0
0
24
24
1
24
24
16
0
84
0
4[c]
5[d]
6
90 (86) 10 (9)
Table 2. SNAr reaction of Zn-1 with 1-hexanol.[a]
0
0
0
0
100
Base [equiv.] Solvent
T
t
Yield [%][b]
[°C] [h] Zn-1 Zn-2f Zn-3f Zn-4f Zn-8
[a] Reaction conditions: 2H-1 (20 mg, 0.03 mmol), the base heated
in 1-hexanol (4 mL) under Ar. [b] Determined by MALDI-TOF
MS analysis. Isolated yields are given in parentheses. [c] Upscale
to 50 mg (0.81 mmol) of 2H-1. [d] Complete decomposition of the
starting material.
1
2
3
Cs2CO3 (3)
Cs2CO3 (3)
Cs2CO3 (1)
diglyme 145
6
diglyme 170 1.5
diglyme 170 3.5
0
0
0
0
26
0
0
10
50[c]
0
0
0
50[c]
56[c]
48[e]
44[c]
0
4[d] Cs2CO3 (3)
DMA 120
6
0
0
24
8
19[e]
0
5
Cs2CO3 (3)
6[d] HexOLi (100) HexOH 170
HexOLi (10) HexOH 170
DMA 100 15 40[e] 49[e]
0
28
17
1
3
0
0
0
0
42
57
7
[a] Reaction conditions: Zn-1 (20 mg, 0.03 mmol), 1-hexanol
(0.25 mL, 66 equiv.), base, solvent (3.75 mL), heated under Ar.
[b] Determined by 1H NMR spectroscopic analysis. [c] Determined
by MALDI-TOF MS analysis. [d] Upscale to 50 mg (0.074 mmol)
of Zn-1. [e] Isolated yield.
Zn-1 reacted with 1-hexanol at higher temperature com-
pared with Ni-1, affording the desired product in low yields
because of a competing hydrodebromination reaction and
considerable degradation of the porphyrins (Scheme 4 and
Table 2).
The structure of the side products and their amount was
dependent on the reaction temperature, the nature of the
base and the solvent, as well as on the amount of base that
was introduced into the reaction. Under the optimal condi-
tions used for the preparation of Ni-2f (Cs2CO3, diglyme,
145 °C), the reaction of Zn-1 afforded an inseparable mix-
Scheme 4. Synthesis of Zn-2f and 2H-2f using SNAr reaction of
Zn-1 with 1-hexanol.
Upon increase of the temperature to 170 °C, the hydro-
ture of Zn-2f and Zn-4f (2:1 ratio) in 36% yield (Table 2, debromination reaction was favored (entry 2). Hydrode-
entry 1).
bromination was also observed when the amount of
Scheme 5. SNAr reaction of 2H-1 and 2H-8 with alcohols.
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Cs2CO3 was decreased, indicating the importance of For example, when 5-bromo-10,20-diphenylporphyrin (2H-
alcohol deprotonation for successful SNAr reaction. For ex- 8) was treated with 1-hexanol in the presence of Cs2CO3
ample, when Cs2CO3 (1 equiv.) was used in diglyme at (3 equiv.) at 170 °C, ether 2H-4f was obtained in 52% yield
170 °C, the side hydrodebromination of Zn-1 gave zinc(II) (Scheme 5).
5-bromo-10,20-diphenylporphyrinate (Zn-8), which did not
Free-base porphyrinyl alkyl ethers and their complexes
react with 1-hexanol under these conditions (entry 3). have seldom been studied but they are of interest for investi-
Higher selectivity of the SNAr reaction was achieved when gation of the structural and electronic influence of individ-
diglyme was replaced by DMA and the reaction was carried ual substituents on the properties of tetrapyrrolic macro-
out at lower temperature. In this solvent, a mixture of Zn-2f cycles. In a continuation of our project aimed at the study
and Zn-4f was still formed at 120 °C (entry 4) but a selective of porphyrin assemblies formed through weak coordination
substitution reaction was observed at 100 °C, affording the bonds,[44–48] we investigated the solution behavior of ether
target compound Zn-2f after 15 h in 49% yield with 40% Zn-2f. Aromatic ethers easily form complexes with transi-
recovery of the starting porphyrin (entry 5). Our attempts tion-metal ions and we expected to observe a coordination-
to replace both bromine atoms by using a stronger nucleo- driven self-assembly of alkoxy-substituted metalloporphyr-
phile such as lithium hexanolate in hexanol at 170 °C gave inates due to the axial coordination of the oxygen atom of
the target product Zn-3f in low yields, along with the prod- the alkoxy group to the central metal cation of a second
ucts of the hydrodebromination reaction (entries 6 and 7).
Surprisingly, the demetallation of Zn-2f with TFA in
chloroform gave a mixture of the target compound 2H-2f
and 5-bromo-10,20-diphenylporphyrin (2H-8) in a 9:1 ratio
(Scheme 4). The separation of products by column
chromatography was difficult and the structure of the side
porphyrin macrocycle, as shown in Scheme 6.
1
product was determined by comparison of the H NMR
spectroscopic data of this mixture with those of an authen-
tic sample of 2H-8, and was confirmed by MALDI-TOF
MS analysis. Thus, to obtain free-base porphyrin deriva-
tives, SNAr reaction of 2H-1 with 1-hexanol was studied
(Scheme 5).
Once again, the hydrodebromination reaction was ob-
served and a careful optimization was needed to prepare
the target products in good yields (Table 3). When the reac-
tion was carried out using Cs2CO3 (1 equiv.) in 1-hexanol,
selective mono-substitution was observed but the reaction
proceeded slowly and only approximately 50% conversion
was obtained even after 7 h (entry 1). Prolonged heating led
to an increase in the amount of hydrodebromination prod-
uct (entry 2). Higher yields of the target 2H-2f were ob-
Scheme 6. Schematic representation of Zn-2f self-assemblies.
To gain initial insight into the self-assembly of por-
1
tained by using a weaker base, sodium carbonate, taken in phyrinyl alkyl ethers, H NMR spectra of Zn-2f were re-
excess. The reaction with Na2CO3 (3 equiv.) gave porphyrin corded at a range of concentrations in CDCl3 and com-
2H-2f in 64% yield, which was only hindered by the com- pared with those of Ni-2f, which is not able to form supra-
peting degradation reaction (entry 3). Interestingly, selective molecular complexes under the experimental conditions
dietherification reaction was observed when sodium carb- studied (Figure 1A and B). As expected, negligible changes
onate was replaced by Cs2CO3 and the target porphyrin in the spectrum of Ni-2f were observed when the concentra-
2H-3f was isolated in 86%. In contrast, an increase in the tion of the complex was increased from 10–4 to 10–2 m (Fig-
amount of sodium carbonate was inappropriate for the syn- ure 1B). In contrast, for complex Zn-2f, a set of sharp sig-
thesis of diether 2H-3f (entries 4 and 5).
nals was observed at 10–4 m, which gradually broadened
The higher homologues of 1-hexanol also reacted with and shifted upfield upon increase of the concentration up
2H-1 under the catalyst-free conditions described above. to 6ϫ10–3 m (Figure 1A). Further increase of the concen-
For example, the reaction of 2H-1 with 1-hexadecanol and tration to 10–2 m led to a gradual upshift of narrowing pro-
Cs2CO3 (3 equiv.) at 170 °C afforded a mixture of 2H-3g ton resonances. The concentration-induced shift was dif-
and 2H-2g in 11:1 molar ratio in 88% yield. However, sepa- ferent for each of the β-protons, which were unambiguously
ration of these compounds was challenging, and metalla- assigned by using COSY and through-space NOE between
tion with Zn(OAc)2 was needed to obtain pure Zn-3g.
H2-H3 and H1-CH2O protons (Figures S38–S40). These
Thus, careful optimization of catalyst-free reactions of shifts decreased along the sequence H1 Ͼ H2 ≈ H3 ≈ H4,
2H-1 with primary alcohols allowed the selective mono- and only signals of H1 protons significantly shifted at
and dietherification of the porphyrin macrocycle to be higher concentrations of the complex (Figure 1C). It is im-
achieved. It is also of interest that these conditions can be portant to note that the signals corresponding to meso-aryl
used for functionalization of other meso-bromoporphyrins. substituents were almost identical in all spectra.
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meso-Aryloxy- and Alkoxy-Substituted Porphyrins
Figure 1. Partial 1H NMR spectra of Zn-2f (A) and Ni-2f (B) in CDCl3. Concentration dependence of the chemical shifts of the β-pyrrol
protons of Zn-2f (C).
The spectral difference observed for Zn-2f and Ni-2f can
be explained by considering that Zn-2f can form supra-
Conclusions
molecular assemblies, as shown in Scheme 6. Moreover,
A series of RO-appended porphyrins was synthesized in
these data indicate that co-facial dimer II is not a major good yields from 5,15-dibromoporphyrins M(Br2DPP) by
species present in the studied solutions of Zn-2f, because a using SNAr reactions. Although this reaction often proceeds
strong upfield shift of resonances of β-pyrrol and meso-aryl in parallel with various side processes, the selectivity can be
substituent protons should be observed for dimer II due to increased by varying the nature of the base and its amount,
ring current effects of the tetrapyrrolic macrocycles.[24,45]
the solvent, the temperature, and the reaction time. More-
The above conclusion is also supported by a comparison over, the SNAr reaction can be directed to the synthesis of
of structural parameters obtained for Zn-2f using DFT cal- meso-substituted porphyrin decorated by one or two RO
culations with those of zinc(II) complexes bearing coordi- groups. This reaction is a convenient alternative to transi-
nated anisol fragment and deposited at the Cambridge tion-metal-catalyzed C–O bond-forming reactions. Al-
Crystallographic Data Centre. Indeed, according to the though SNAr reactions of 5,15-dibromoporphyrins M-1
geometry optimization of dimer II performed with the ap- with alcohols demand time-consuming optimization, they
plication of SPARTAN’14 software at the B3LYP/6-31G* are less expensive, free of toxic metals, and gave, in some
level, the distance between macrocycles should be approxi- cases, better yields and higher selectivity than transition-
mately 3.16 Å. This value is in the range of typical π–π metal-catalyzed coupling reactions. Monofunctionalization
stacking interaction values (3.4–3.6 Å).[49] However, an of 5,15-dibromoporphyrins M-1 through SNAr reaction is
average Zn···O distance for zinc(II) complexes with ligands a useful tool for the preparation of porphyrinyl ethers,
bearing an anisol fragment is much smaller (2.37Ϯ0.11 Å). which have seldom been explored but which are potentially
Accordingly, the co-facial arrangement of porphyrin macro- interesting derivatives, since the conjugation of the oxygen
cycles should prohibit efficient binding of the donor oxygen atom should induce new electronic properties. Besides being
atom by the metal ion of another porphyrin molecule.
suitable starting materials for new representatives of por-
It is difficult to determine whether only dimer I or oligo- phyrinyl alkyl and porphyrinyl aryl series, these compounds
mers III are observed in 6ϫ10–3 m solution of Zn-2f in are of interest in their own right. They allow an investiga-
CDCl3. However, taking into account that supramolecular tion of the structural and electronic influence of individual
assemblies were detected only at the millimolar concentra- substituents on the tetrapyrrole macrocycle properties and
tion of the complex, it appears that the association constant are useful building blocks for crystal engineering. Our pre-
is low and that dimer I is a predominant species in the liminary studies of the solution behavior of Zn-2f in chlor-
studied solutions. Unfortunately, our attempts to grow sin- inated solvents testify to their ability to form supramolec-
gle crystals of Zn-2f were unsuccessful.
ular assemblies. We expect that these compounds will be
Eur. J. Org. Chem. 2015, 5610–5619
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5615

K. P. Birin, R. Guilard et al.
FULL PAPER
3
3
H, m+p-Ph), 7.19 (dd, JH,H = 8.6, JH,H = 7.6 Hz, 4 H, m-PhO),
also of interest for the preparation of push–pull porphyrins
and organized thin-film materials.
3
3
6.96 (t, JH,H = 7.4 Hz, 2 H, p-PhO), 6.86 (d, JH,H = 8.2 Hz, 4 H,
o-PhO) ppm. UV/Vis (CHCl3): λ = 417, 529, 560 (sh) nm. HRMS
(ESI): m/z calcd. for C44H28N4NiO2 [M]+ 702.15603; found
702.15817.
Experimental Section
[5,15-Bis(2,6-dimethylphenoxy)-10,20-diphenylporphyrinato]nickel-
(II) (Ni-3b): (Table 1, entry 2): Prepared by following the general
procedure from Ni-1 and 2,6-dimethylphenol (135 mg, 1.11 mmol,
15 equiv.) in DMA, yield 77 %; red solid. 1H NMR (300 MHz,
CDCl3, 25 °C): δ = 8.96 (d, 3JH,H = 5.0 Hz, 4 H, Hβ), 8.52 (d, 3JH,H
= 5.0 Hz, 4 H, Hβ), 7.91–7.86 (m, 4 H, o-Ph), 7.64–7.56 (m, 6 H,
m+p-Ph), 7.09–7.03 (m, 6 H, OAr), 1.98 (s, 12 H, Me) ppm. UV/
Vis (CHCl3): λ = 424, 544, 589 nm. MS (MALDI-TOF): m/z calcd.
for C48H36N4NiO2 [M]+ 758.22; found 758.64.
General: Unless otherwise noted, all chemicals and starting materi-
als were obtained from Acros or Aldrich, and were used without
further purification. The starting porphyrins 2H-1,[36] Zn-1,[36] Ni-
1[37] and 2H-8[37,50,51] were prepared according to published pro-
cedures. Phenol (Sigma–Aldrich, 99%), 2,6-dimethylphenol (Ald-
rich, 99%), 2,6-diisopropylphenol (Aldrich, 97%), 2,6-di-tert-butyl-
4-methylphenol (Aldrich, 99%), benzyl alcohol (Aldrich, 99%),
and DMA (Aldrich, 99.5%) were used as obtained. 1-Hexyl alcohol
(Aldrich, 98%) was distilled from sodium and stored under argon.
Diglyme (Aldrich, 99%) was distilled from NaOH and stored under
argon. Chloroform and hexane (reagent grade) were dried with an-
hydrous CaCl2 and distilled from CaH2.
[5,15-Bis(2,6-diisopropylphenoxy)-10,20-diphenylporphyrinato]-
nickel(II) (Ni-3c): (Table 1, entry 3): Prepared by following the ge-
neral procedure from Ni-1 and 2,6-diisopropylphenol (197 mg,
205 μL, 1.11 mmol, 15 equiv.) in DMA, yield 17%; red solid. 1H
All reactions were performed in oven-dried glassware under a slight
positive pressure of argon. Analytical thin-layer chromatography
(TLC) was carried out with Merck silica gel 60 plates (precoated
sheets, 0.2 mm thick, with fluorescence indicator F254), preparative
thin-layer chromatography (PLC) was carried out with Merck silica
gel 60 (precoated glass plates, 2 mm thick). Column chromatog-
raphy purification was carried out with silica gel (Silica 60, 60–
200 μm, Macherey–Nagel) and neutral alumina (50–200 μm, Ma-
cherey–Nagel).
3
NMR (300 MHz, CDCl3, 25 °C): δ = 8.81 (d, JH,H = 5.1 Hz, 4 H,
3
Hβ), 8.47 (d, JH,H = 5.1 Hz, 4 H, Hβ), 7.93–7.83 (m, 4 H, o-Ph),
7.68–7.54 (m, 6 H, m+p-Ph), 7.31 (br. s, 6 H, OAr), 3.20 (sept,
3JH,H = 6.9 Hz, 4 H, CH), 0.99 (d, 3JH,H = 6.9 Hz, 24 H, Me) ppm.
UV/Vis (CHCl3): λ = 418, 542, 572 (sh) nm. MS (MALDI-TOF):
m/z calcd. for C56H52N4NiO2 [M]+ 870.34; found 870.54. HRMS
(ESI): m/z calcd. for C56H52N4NiO2 [M]+ 870.34491; found
870.34383.
[5,15-Bis(benzyloxy)-10,20-diphenylporphyrinato]nickel(II) (Ni-3e):
(Table 1, entry 5): Prepared by following the general procedure
from Ni-1 and benzyl alcohol (640 mg, 610 μL, 5.92 mmol,
80 equiv.) in DMA, yield 62 %; red solid. 1H NMR (600 MHz,
CDCl3, 25 °C): δ = 9.29 (d, 3JH,H = 4.8 Hz, 4 H, Hβ), 8.71 (d, 3JH,H
NMR spectra were acquired with a Bruker Avance III 600.13 MHz
and a Bruker Avance II 300.21 MHz and referenced to residual
solvent protons. The unambiguous assignment of signals in the 1H
NMR spectra was performed by using gradient-enhanced COSY
and NOESY correlation experiments. UV/Vis spectra were ob-
tained with a Unicam UV-4 spectrophotometer in CHCl3 in rectan-
gular quartz cells with 1 cm optical path. MALDI-TOF mass-spec-
tra were obtained with a Bruker Ultraflex mass-spectrometer in
positive ion mode without application of matrix, otherwise another
conditions are stated. Accurate mass measurements (HRMS) were
made at the “Pôle Chimie Moléculaire”, the technological platform
for chemical analysis and molecular synthesis (http://www.wpcm.fr)
which relies on the Institute of Molecular Chemistry of the Univer-
sity of Burgundy and WelienceTM, a Burgundy University private
subsidiary. Solutions in CHCl3/methanol (1:1) were used for analy-
sis.
3
4
= 4.8 Hz, 4 H, Hβ), 7.98 (dd, JH,H = 7.8, JH,H = 1.5 Hz, 4 H, o-
3
Ph), 7.71–7.65 (m, 6 H, m+p-Ph), 7.62 (d, JH,H = 7.8 Hz, 4 H, o-
3
3
Bn), 7.43 (t, JH,H = 7.5 Hz, 4 H, m-Bn), 7.38 (t, JH,H = 7.5 Hz, 2
H, p-Bn), 5.66 (s, 4 H, OCH2-Ph) ppm. UV/Vis (CHCl3): λ = 416,
529, 561 (sh) nm. HRMS (ESI): m/z calcd. for C46H32N4NaNiO2
[M + Na]+ 753.17710; found 753.17891.
(5-Bromo-15-hexyloxy-10,20-diphenylporphyrinato)nickel(II) (Ni-
2f): (Table 1, entry 10): Prepared by following the general pro-
cedure from Ni-1 and hexyl alcohol (498 mg, 612 μL, 4.88 mmol,
66 equiv.) in diglyme, yield 57%; red solid. 1H NMR (600 MHz,
CDCl3, 25 °C): δ = 9.40 (d, 3JH,H = 5.0 Hz, 2 H, Hβ), 9.29 (d, 3JH,H
3
= 4.9 Hz, 2 H, Hβ), 8.70 (d, JH,H = 5.0 Hz, 2 H, Hβ), 8.68 (d,
3JH,H = 4.9 Hz, 2 H, Hβ), 7.93–7.96 (m, 4 H, o-Ph), 7.72–7.64 (m,
SNAr Reactions of Ni(Br2DPP) and Zn(Br2DPP) with Phenols and
Alcohols
3
3
6 H, m+p-Ph), 4.58 (t, JH,H = 6.5 Hz, 2 H, CH2), 2.04 (tt, JH,H
3
3
= 7.9, JH,H = 6.5 Hz, 2 H, CH2), 1.67 (quint, JH,H = 7.9 Hz, 2
H, CH2), 1.33–1.42 (m, 4 H, CH2), 0.91 (t, JH,H = 7.1 Hz, 3 H,
Nickel(II) OR-Substituted Porphyrins. General Procedure: A 25 mL
flask containing Ni-1 (50 mg, 0.074 mmol) and Cs2CO3 (72 mg,
0.222 mmol) was evacuated and backfilled with argon three times.
The solvent (9.4 mL) and the indicated amount of phenol or
alcohol (Table 1) were added and the mixture was heated under
argon for the time indicated (Table 1). The reaction mixture was
then diluted with CHCl3 (50 mL) and washed with H2O (50 mL).
The organic layer was separated, dried with Na2SO4, and evapo-
rated under reduced pressure at 60 °C. The residue was purified
by chromatography on silica gel (CHCl3/hexane, 0Ǟ100%). The
product was purified by preparative TLC (hexane/acetone, 4:1).
3
CH3) ppm. UV/Vis (CHCl3): λ = 418, 532, 565 (sh) nm. HRMS
(ESI): m/z calcd. for C38H32BrN4NiO [M + H]+ 696.10292; found
696.10488.
Demetallation of Ni-2f; Route 1: Ni-2f (5 mg, 7 μmol) was dissolved
in CH2Cl2 (5 mL) and H2SO4 (50 μL) was added upon vigorous
stirring (the mixture became green). After stirring at ambient tem-
perature for 15 min, water (5 mL) was added and the reaction mix-
ture was neutralized (pH 7) by using saturated aqueous NaHCO3.
The organic layer was separated and analyzed by MALDI-TOF
MS. A mixture of 2H-2f (m/z 641.35) and 2H-4f (m/z 563.18) in a
1:1 ratio was obtained. The products were not separated.
[5,15-Diphenoxy-10,20-diphenylporphyrinato]nickel(II)
(Ni-3a):
(Table 1, entry 1): Prepared by following the general procedure
from Ni-1 and phenol (104 mg, 1.11 mmol, 15 equiv.) in DMA,
Route 2: Ni-2f (5 mg, 7 μmol) was dissolved in CHCl3 (5 mL) and
yield 72%; red solid. 1H NMR (600 MHz, CDCl3, 25 °C): δ = 9.16 TFA (100 μL) was added upon stirring. The progress of the reac-
3
3
(d, JH,H = 5.0 Hz, 4 H, Hβ), 8.69 (d, JH,H = 4.9 Hz, 4 H, Hβ),
tion was monitored by UV/Vis and MALDI-TOF MS. No conver-
3
4
7.97 (dd, JH,H = 8.0, JH,H = 1.4 Hz, 4 H, o-Ph), 7.69–7.63 (m, 6 sion of the starting material was detected after 5 h.
5616
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© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 5610–5619

meso-Aryloxy- and Alkoxy-Substituted Porphyrins
[5-Bromo-15-hexyloxy-10,20-diphenylporphyrinato]zinc(II) (Zn-2f):
tained as a mixture and separated by preparative TLC (hexane/
(Table 2, entry 5): A 10 mL flask containing the starting Zn-1 acetone, 4:1), yields: 86% (2H-3f) and 9% (2H-4f); violet solids.
(20 mg, 0.03 mmol) and Cs2CO3 (29 mg, 0.09 mmol) was evacuated
The spectroscopic data of 2H-3f were in good agreement with re-
and backfilled with argon three times. DMA (3.75 mL) and hexa-
ported data.[26]
nol (0.25 mL, 66 equiv.) were then added and the mixture was
1
Compound 2H-4f: H NMR (600 MHz, CDCl3, 25 °C): δ = 10.05
heated under argon for 15 h. After cooling to room temperature,
3
3
(s, 1 H, Hmeso), 9.55 (d, JH,H = 4.6 Hz, 2 H, Hβ), 9.24 (d, JH,H
=
the reaction mixture was diluted with CHCl3 (10 mL), filtered, and
the solvents were evaporated under reduced pressure at 60 °C. The
residue was purified by chromatography on silica gel (CHCl3/hex-
ane, 0Ǟ50%). The product was purified by using preparative TLC
on silica gel (hexane/acetone, 4:1), yield 49%; violet solid. 1H NMR
3
3
4.6 Hz, 2 H, Hβ), 8.96 (d, JH,H = 4.6 Hz, 2 H, Hβ), 8.91 (d, JH,H
= 4.6 Hz, 2 H, Hβ), 8.22 (m, 4 H, o-Ph), 7.80–7.75 (m, 6 H, m+p-
Ph), 5.04 (t, JH,H = 6.6 Hz, 2 H, CH2O), 2.39 (m, 2 H, CH2), 1.91
3
(m, 2 H, CH2), 1.56 (m, 2 H, CH2), 1.50 (m, 2 H, CH2), 0.99 (t,
3JH,H = 7.2 Hz, 3 H, CH3), –2.80 (s, 2 H, NH) ppm. UV/Vis
(CHCl3): λ = 413, 510, 546, 586, 641 nm. HRMS (ESI): m/z calcd.
for C38H35N4O [M + H]+ 563.28054; found 563.28004.
3
(300 MHz, CDCl3, 25 °C): δ = 9.62 (d, JH,H = 4.8 Hz, 2 H, Hβ),
3
3
9.30 (d, JH,H = 4.8 Hz, 2 H, Hβ), 8.89 (d, JH,H = 4.7 Hz, 2 H,
3
Hβ), 8.84 (d, JH,H = 4.5 Hz, 2 H, Hβ), 8.12 (m, 4 H, o-Ph), 7.77
(t, 3JH,H = 7.3 Hz, 2 H, p-Ph), 7.73 (t, JH,H = 7.3 Hz, 4 H, m-Ph),
3
The reaction was also performed using Na2CO3 as a base under
similar conditions. The reagent amounts, the temperature, and the
reaction times are reported in Table 3 (entries 5 and 6). The reac-
tions were monitored by MALDI-TOF MS and did not afford the
target product.
3
4.80 (t, JH,H = 6.9 Hz, 2 H, CH2), 2.21 (m, 2 H, CH2), 1.78 (m, 2
H, CH2), 1.52–1.43 (m, 4 H, CH2), 0.97 (t, JH,H = 7.2 Hz, 3 H,
3
Me) ppm. UV/Vis (CHCl3): λ = 425, 556, 602 nm. HRMS (ESI):
m/z calcd. for C38H31BrN4OZn [M]+ 702.09672; found 702.09865.
5-Bromo-15-hexyloxy-10,20-diphenylporphyrinate (2H-2f): (Table 3,
entry 3). 2H-1 (50 mg, 0.080 mmol) and Na2CO3 (61 mg,
0.240 mmol) were heated in 1-hexanol (10 mL) at 170 °C under dry
argon for 24 h. After cooling to room temperature, the reaction
mixture was filtered through a short pad of neutral alumina using
CHCl3 as eluent. The solvent was evaporated and the product was
purified by column chromatography on silica gel (CHCl3/hexane,
0Ǟ50%; the fraction containing 2H-2f was collected at 25Ǟ50%
The reaction conditions were optimized in a series of experiments
reported in Table 2 (entries 1–5). All reactions were performed ac-
cording to this procedure and monitored by NMR spectroscopy or
by MALDI-TOF MS.
[5,15-Bis(hexyloxy)-10,20-diphenylporphyrinato]zinc(II) (Zn-3f):
(Table 2, entry 6): A 25 mL flask containing Zn-1 (50 mg,
0.074 mmol) was evacuated and backfilled with argon three times.
Hexanol (10 mL) and MeOLi (2 m in hexanol, 3.7 mL, 100 equiv.)
were added and the mixture was heated to reflux for 1 h. After
cooling to room temperature, the mixture was diluted with CHCl3
(10 mL) and quenched with water (10 mL). The organic layer was
separated and the solvents evaporated under reduced pressure at
60 °C. The residue was separated by column chromatography on
silica gel (CHCl3/hexane 0Ǟ50%), yields: 24% (Zn-3f) and 42%
(Zn-4f); violet solids.
1
CHCl3/hexane), yield 64%. H NMR (600 MHz, CDCl3, 25 °C): δ
3
3
= 9.59 (d, JH,H = 4.8 Hz, 2 H, Hβ), 9.44 (d, JH,H = 4.6 Hz, 2 H,
3
3
Hβ), 8.84 (d, JH,H = 4.8 Hz, 2 H, Hβ), 8.80 (d, JH,H = 4.6 Hz, 2
H, Hβ), 8.17 (m, 4 H, o-Ph), 7.81–7.73 (m, 6 H, m+p-Ph), 5.00 (t,
3JH,H = 6.6 Hz, 2 H, CH2), 2.35 (m, 2 H, CH2), 1.88 (m, 2 H,
3
CH2), 1.57–1.44 (m, 4 H, CH2), 0.99 (t, JH,H = 7.2 Hz, 3 H, Me),
–2.63 (s, 2 H, NH) ppm. UV/Vis (CHCl3): λ = 420, 520, 557, 600,
657 nm. MS (MALDI-TOF): m/z calcd. for C38H34BrN4O [M]+
641.19; found 641.26.
The reaction was also performed using 10 equiv. of MeOLi
(Table 2, entry 7). However, the target product Zn-3f was obtained
in low yield (8%) along with porphyrins Zn-4f and Zn-8.
The reaction conditions were optimized in a series of experiments
reported in Table 3 (entries 1–3). All reactions were performed ac-
cording to this procedure and monitored by MALDI-TOF MS.
The spectroscopic data of Zn-3f and Zn-8 were in good agreement
with reported data.[26]
5,15-Bis(hexadecyloxy)-10,20-diphenylporphyrinate (2H-3g) and 5-
Bromo-15-hexadecyloxy-10,20-diphenylporphyrinate (2H-2g) Mix-
ture (11:1): A 25 mL flask charged with 2H-1 (50 mg, 0.080 mmol),
Cs2CO3 (79 mg, 0.240 mmol) and hexadecanol (8.25 g) was evacu-
ated and backfilled with argon three times and the mixture was
heated at 170 °C for 1 h. After cooling to room temperature, the
reaction mixture was filtered through a short pad of neutral alu-
mina using CHCl3 as an eluent. The eluent (ca. 50 mL) was evapo-
rated and the product was purified by column chromatography on
silica gel (CHCl3/hexane, 0Ǟ50%). The fraction containing a mix-
ture of porphyrins 2H-2g and 2H-3g (1:11) and hexadecyl alcohol
was collected with a binary solvent mixture containing 25–50% of
CHCl3, yield 88%.
Compound Zn-4f: 1H NMR (300 MHz, CDCl3, 25 °C): δ = 10.06
3
3
(s, 1 H, Hmeso), 9.54 (d, JH,H = 4.5 Hz, 2 H, Hβ), 9.28 (d, JH,H
=
3
3
4.5 Hz, 2 H, Hβ), 9.01 (d, JH,H = 4.4 Hz, 2 H, Hβ), 8.97 (d, JH,H
= 4.5 Hz, 2 H, Hβ), 8.20 (m, 4 H, o-Ph), 7.80–7.73 (m, 6 H, m+p-
Ph), 5.00 (t, JH,H = 6.6 Hz, 2 H, CH2O), 2.35 (m, 2 H, CH2), 1.88
3
(m, 2 H, CH2), 1.55 (m, 2 H, CH2), 1.49 (m, 2 H, CH2), 0.99 (t,
3JH,H = 7.2 Hz, 3 H, CH3) ppm. UV/Vis (CHCl3): λ = 415, 544,
585 nm. MS (MALDI-TOF): m/z calcd. for C38H34N4OZn [M]+
624.19; found 624.60. HRMS (ESI): m/z calcd. for C38H34N4OZn
[M]+ 624.18621; found 624.18581.
SNAr Reactions of Free-Base Porphyrin 2H-1 and 2H-8 with
Alcohols
Compound 2H-3g: Obtained as a mixture with 2H-2g and hexa-
decyl alcohol. 1H NMR (600 MHz, CDCl3, 25 °C): δ = 9.45 (d,
5,15-Bis(hexyloxy)-10,20-diphenylporphyrin (2H-3f): (Table 3, en-
try 4): A 25 mL flask, charged with 2H-1 (50 mg, 0.08 mmol) and
Cs2CO3 (79 mg, 0.24 mmol) was evacuated and backfilled with ar-
gon three times. 1-Hexanol (10 mL) was added and the mixture
was heated under argon for 1 h. After cooling to room temperature,
the reaction mixture was filtered through a short pad of neutral
alumina using CHCl3 as an eluent. The eluent was evaporated and
the product was purified by column chromatography on silica gel
(CHCl3/hexane, 0Ǟ50%). Porphyrins 2H-3f and 2H-4f were ob-
3
3JH,H = 4.6 Hz, 4 H, Hβ), 8.83 (d, JH,H = 4.6 Hz, 4 H, Hβ), 8.17
3
(d, JH,H = 6.7 Hz, 4 H, o-Ph), 7.81–7.73 (m, 6 H, m+p-Ph), 5.03
3
(t, JH,H = 6.7 Hz, 4 H, CH2O) ppm. Other aliphatic resonances
overlapped with the signals of hexadecyl alcohol protons.
A mixture of 2H-2g and 2H-3g was inseparable by chromatography
on silica gel or alumina. The pure products were obtained after
the metallation/demetallation of the porphyrins according to the
following procedure:
Eur. J. Org. Chem. 2015, 5610–5619
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5617

K. P. Birin, R. Guilard et al.
FULL PAPER
The mixture of 2H-2g and 2H-3g was dissolved in CHCl3/MeOH
(1:1, 5 mL) and solid Zn(OAc)2 (29 mg, 0.16 mmol) was added to
this solution. The reaction mixture was stirred at room temperature
until complete conversion of the free-base porphyrins according to
UV/Vis spectroscopy was observed (ca. 30 min). The reaction mix-
ture was evaporated under reduced pressure and the product was
purified by preparative TLC (hexane/acetone, 4:1), yields: 82 %
(Zn-3g) and 6% (Zn-2g); violet solids.
and heated to reflux for 19 h and then cooled to room temperature.
After evaporation under reduced pressure, the residue was purified
by chromatography on silica gel (CH2Cl2/heptane, 0Ǟ100%), yield
1
62%; red solid. H NMR (300 MHz. CDCl3, 25 °C): δ = 10.27 (s,
3
3
1 H, CHO), 9.37 (d, JH,H = 4.9 Hz, 2 H, Hβ), 8.76 (d, JH,H
=
3
3
4.9 Hz, 2 H, Hβ), 8.70 (d, JH,H = 5.0 Hz, 2 H, Hβ), 8.57 (d, JH,H
= 5.0 Hz, 2 H, Hβ), 8.14 (s, 4 H, Ar), 8.02–7.95 (m, 4 H, o-Ph),
3
7.71–7.62 (m, 6 H, m+p-Ph), 4.64 (t, JH,H = 6.7 Hz, 2 H, CH2O),
3
3
2.08 (tt, JH,H = 7.6, JH,H = 6.7 Hz, 2 H, CH2), 1.77–1.60 (m, 4
To obtain free-base porphyrin 2H-2g, Zn-2g was demetallated ac-
cording to the following procedure. Complex Zn-2g was dissolved
in 1% TFA in CHCl3 (5 mL) and stirred at room temperature for
15 min. Water (5 mL) was then added to the green solution and the
obtained biphasic mixture was neutralized to pH 7 by dropwise
addition of saturated aqueous NaHCO3. The organic layer was sep-
arated, dried with Na2SO4, and evaporated under reduced pressure
to give free-base porphyrin 2H-2g, yield 99%.
3
H, 2CH2), 1.45–1.37 (m, 2 H, CH2), 0.93 (t, JH,H = 7.0 Hz, 3 H,
CH3) ppm. UV/Vis (CHCl3): λ = 417, 530 nm. MS (MALDI-TOF):
m/z calcd. for C45H36N4NiO2 [M]+ 722.22; found 722.08. HRMS
(ESI): m/z calcd. for C45H36N4NiO2 [M]+ 722.21973; found
722.21863.
[5-Hexyloxy-15-(2-trimethylsilylacetylenyl)-10,20-diphenylpor-
phyrinato]nickel(II) (Ni-6f): A 10 mL flask charged with Ni-2f
(28 mg, 0.04 mmol), Pd(PPh3)2Cl2 (3.4 mg, 12 mol-%), and CuI
(1 mg, 13 mol-%) was evacuated and backfilled with N2 three times.
Toluene (1.7 mL), Et3N (0.3 mL), and trimethylsilylacetylene
(0.18 mL, 0.79 mmol) were then added by using syringes and the
mixture was heated to reflux for 15 h, cooled to room temperature,
evaporated under reduced pressure and purified by column
chromatography on silica gel (CH2Cl2/heptane, 0Ǟ50 %), yield:
63%; deep-red solid. Nickel(II) 5,15-diphenyl-10,20-bis(2-trimeth-
ylsilylacetilenyl)porphyrinate (Ni-9) was also isolated as a deep-red
solid (13% yield).
Compound Zn-2g: 1H NMR (300 MHz, CDCl3, 25 °C): δ = 9.67
3
3
(d, JH,H = 4.4 Hz, 2 H, Hβ), 9.45 (d, JH,H = 4.3 Hz, 2 H, Hβ),
3
3
8.92 (d, JH,H = 4.4 Hz, 2 H, Hβ), 8.88 (d, JH,H = 4.3 Hz, 2 H,
Hβ), 8.21–8.13 (m, 4 H, o-Ph), 7.81–7.71 (m, 6 H, m+p-Ph), 4.94
3
(t, JH,H = 6.2 Hz, 2 H, CH2O), 2.31 (m, 2 H, CH2), 1.84 (m, 2 H,
CH2), 1.53 (m, 2 H, CH2), 1.43 (m, 2 H, CH2), 1.38–1.18 (m, 20
H, CH2), 0.85 (t, 3JH,H = 7.1 Hz, 3 H, CH3) ppm. UV/Vis (CHCl3):
λ = 426, 561, 602 nm. MS (MALDI-TOF): m/z calcd. for
C
48H51BrN4OZn [M]+ 842.25; found 842.21. HRMS (ESI): m/z
calcd. for C48H51BrN4OZn [M]+ 842.25322; found 842.25471.
Compound Zn-3g: 1H NMR (600 MHz, CDCl3, 25 °C): δ = 9.48
1
Compound Ni-6f: H NMR (300 MHz, CDCl3, 25 °C): δ = 9.42 (d,
3
3
3JH,H = 4.9 Hz, 2 H, Hβ), 9.28 (d, JH,H = 4.9 Hz, 2 H, Hβ), 8.71
3
(d, JH,H = 4.6 Hz, 4 H, Hβ), 8.90 (d, JH,H = 4.6 Hz, 4 H, Hβ),
3
3
3
8.18 (m, 4 H, o-Ph), 7.79–7.71 (m, 6 H, m+p-Ph), 4.97 (t, JH,H
=
(d, JH,H = 4.9 Hz, 2 H, Hβ), 8.65 (d, JH,H = 4.9 Hz, 2 H, Hβ),
8.00–7.93 (m, 4 H, o-Ph), 7.72–7.63 (m, 6 H, m+p-Ph), 4.62 (t,
6.6 Hz, 2 H, CH2O), 2.35 (m, 2 H, CH2), 1.87 (m, 2 H, CH2), 1.55
(m, 2 H, CH2), 1.44 (m, 2 H, CH2), 1.36 (m, 2 H, CH2), 1.33–1.19
3JH,H = 6.7 Hz, 2 H, CH2O), 2.07 (tt, JH,H = 7.6, JH,H = 6.7 Hz,
3
3
3
(m, 18 H, CH2), 0.85 (t, JH,H = 7.0 Hz, 3 H, CH3) ppm. UV/Vis
2 H, CH2), 1.69 (m, 2 H, CH2), 1.45–1.36 (m, 4 H, 2 CH2), 0.92
(t, JH,H = 6.9 Hz, 3 H, CH3), 0.527 (s, 9 H, Me3Si) ppm. UV/Vis
(CHCl3): λ = 425, 540, 566 (sh) nm. MS (MALDI-TOF): m/z calcd.
for C43H40N4NiOSi [M]+ 714.23; found 713.88. HRMS (ESI): m/z
calcd. for C43H40N4NiOSi [M]+ 714.23271; found 714.23194.
3
(CHCl3): λ = 426, 561, 602 nm. MS (MALDI-TOF): m/z calcd. for
C64H84N4O2Zn [M]+ 1004.59; found 1004.57.
Compound 2H-2g: 1H NMR (600 MHz, CDCl3, 25 °C): δ = 9.59
3
3
(d, JH,H = 4.7 Hz, 2 H, Hβ), 9.44 (d, JH,H = 4.6 Hz, 2 H, Hβ),
3
3
8.84 (d, JH,H = 4.7 Hz, 2 H, Hβ), 8.79 (d, JH,H = 4.6 Hz, 2 H,
Hβ), 8.20–8.15 (m, 4 H, o-Ph), 7.80–7.73 (m, 6 H, m+p-Ph), 4.99
1
Compound Ni-9: H NMR (300 MHz, CDCl3, 25 °C): δ = 9.43 (d,
3JH,H = 4.9 Hz, 4 H, Hβ), 8.69 (d, JH,H = 4.9 Hz, 4 H, Hβ), 7.99–
3
3
(t, JH,H = 6.6 Hz, 2 H, CH2O), 2.35 (m, 2 H, CH2), 1.86 (m, 2 H,
7.92 (m, 4 H, o-Ph), 7.72–7.65 (m, 6 H, m+p-Ph), 0.51 (s, 18 H,
2 ϫ Me3Si) ppm. UV/Vis (CHCl3): λ = 432, 554, 590 nm. MS
(MALDI-TOF): m/z calcd. for C42H36N4NiSi2 710.18; found
709.90. HRMS (ESI): m/z calcd. for C42H36N4NiSi2 710.18347;
found 709.18265.
CH2), 1.54 (m, 2 H, CH2), 1.44 (m, 2 H, CH2), 1.36 (m, 2 H, CH2),
1.32–1.19 (m, 18 H, CH2), 0.85 (t, 3JH,H = 7.0 Hz, 3 H, CH3), –2.65
(s, 2 H, NH) ppm. UV/Vis (CHCl3): λ = 420, 520, 557, 600, 657 nm.
HRMS (ESI): m/z calcd. for C48H54BrN4O [M + H]+ 781.34755;
found 781.34817.
[5-Hexyloxy-15-morpholino-10,20-diphenylporphyrinato]nickel(II)
(Ni-7f): A 10 mL flask charged with Ni-2f (28 mg, 0.04 mmol),
Pd2dba3 (1.8 mg, 5 mol-%), BINAP (5.3 mg, 20 mol-%), and
Cs2CO3 (45 mg, 0.14 mmol) were evacuated and backfilled with N2
three times, then toluene (2 mL) and morpholine (35 μL, 0.4 mmol)
were added by using syringes. The mixture was heated to reflux for
18 h, then cooled to ambient temperature, evaporated under re-
duced pressure and applied to silica column (CH2Cl2/heptane,
0Ǟ100% and MeOH/CH2Cl2, 0Ǟ2%), yield 25% (ca. 90% pu-
5-Hexyloxy-10,20-diphenylporphyrin (2H-4f): Compound 2H-8
(29 mg, 0.054 mmol) and Cs2CO3 (53 mg, 0.162 mmol) were heated
in 1-hexanol (7.4 mL) at 170 °C for 1.5 h under dry argon. After
cooling to room temperature, the reaction mixture was filtered
through a short pad of neutral alumina using CHCl3 as eluent. The
eluent was concentrated under reduced pressure and purified by
chromatography on silica gel (CHCl3/hexane, 0Ǟ50%; the fraction
containing 2H-4f was collected at 25Ǟ50 % of CHCl3/hexane),
yield 52%; violet solid. The spectroscopic data of 2H-4f were in
good agreement with the data described above.
1
rity); red solid. H NMR (300 MHz, CDCl3, 25 °C): δ = 9.39 (d,
3
3JH,H = 5.0 Hz, 2 H, Hβ), 9.29 (d, JH,H = 5.0 Hz, 2 H, Hβ), 8.70
Pd-Catalyzed Cross-Coupling Reactions of Ni-2f
3
3
(d, JH,H = 5.0 Hz, 2 H, Hβ), 8.69 (d, JH,H = 5.0 Hz, 2 H, Hβ),
7.99–7.94 (m, 4 H, o-Ph), 7.71–7.65 (m, 6 H, m+p-Ph), 4.58 (t,
[5-Hexyloxy-15-(4-formylphenyl)-10,20-diphenylporphyrinato]-
nickel(II) (Ni-5f): A 10 mL flask containing Ni-2f (28 mg,
0.04 mmol), 4-pinacolborane-benzaldehyde (19 mg, 0.08 mmol),
Pd(PPh3)4 (10 mg, 20 mol-%) and Cs2CO3 (26 mg, 0.08 mmol) was
evacuated and backfilled with N2 three times. Toluene (2 mL) was
then added by using a syringe and the reaction mixture was stirred
3JH,H = 6.6 Hz, 2 H, CH2O), 4.22 (br. t, JH,H = 4.4 Hz, 4 H,
3
3
3
CH2N), 4.04 (br. t, JH,H = 4.4 Hz, 4 H, CH2N), 2.03 (tt, JH,H
=
3
7.6, JH,H = 6.7 Hz, 2 H, CH2), 1.67 (m, 2 H, CH2), 1.38 (m, 4 H,
3
2ϫ CH2), 0.90 (t, JH,H = 6.9 Hz, 3 H, CH3) ppm. MS (MALDI-
TOF): m/z calcd. for C42H39N5NiO2 [M]+ 703.25; found 702.83.
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© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 5610–5619

meso-Aryloxy- and Alkoxy-Substituted Porphyrins
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This work was performed within the framework of the French–
Russian Associated Laboratory “LAMREM” supported by the
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Received: May 14, 2015
Published Online: July 28, 2015
Eur. J. Org. Chem. 2015, 5610–5619
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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