Synthesis of 5,10,15,20-tetrakis(2-amino-5-methoxyphenyl)-porphyrin: A versatile building block for porphyrin face selection

Article abstract of DOI:10.1016/j.tetlet.2003.12.100

A new bis-faced substituted porphyrin has been prepared. The four hydroxyl groups on one side as well as the four amino functions on the other one allow at will, a different functionalization of each face of the macrocycle. The usefulness of this synthon is illustrated.

Full text of DOI:10.1016/j.tetlet.2003.12.100

Tetrahedron
Letters
Tetrahedron Letters 45 (2004) 1713–1716
Synthesis of 5,10,15,20-tetrakis(2-amino-5-methoxyphenyl)-
porphyrin: a versatile building block for porphyrin face selection
Christian Ruzi ꢀe , David Gueyrard and Bernard Boitrel*
Universit ꢀe de Rennes1, Institut de Chimie, UMR CNRS 6509, 35042 Rennes Cedex, France
Received 13 November 2003; revised 5 December 2003; accepted 17 December 2003
Abstract—A new bis-faced substituted porphyrin has been prepared. The four hydroxyl groups on one side as well as the four amino
functions on the other one allow at will, a different functionalization of each face of the macrocycle. The usefulness of this synthon is
illustrated.
Ó 2003 Elsevier Ltd. All rights reserved.
9
In Nature most hemoproteins take advantage of their
two different distal and proximal sides either to incor-
porate an exogenous molecule (gas binding, substrate
recognition) or to deliver an axial ligand (histidine,
and in the work of Nishino et al., the long dodecane
chain was included before the formation of the por-
phyrin itself. Thus, we report herein the synthesis,
atropisomerism and functionalization of a new versatile
porphyrin, namely the 5,10,15,20-tetrakis(2-amino-5-
methoxyphenyl)porphyrin (TAMPP) as an alternative.
1
cysteine, tyrosine) to the metal inside the porphyrin. To
mimic such properties, the chemist has been, for a long
time, tackling the recurrent problem of discrimination of
the two porphyrin faces in order to obtain different
According to Scheme 1, the benzaldehyde derivative 1,
bearing a nitro and methoxy group in positions 2 and 5,
respectively, was prepared according to a well-estab-
lished procedure, starting from 5-hydroxy-2-nitro-
benzaldehyde, which was synthesized on a multi-gram
2
functions on each. Some years ago, in the particular
case of a tetra-o-aminophenyl porphyrin, a successful
example of such a face selection was published with a
porphyrin bearing a protected amino group on one side
of the porphyrin, and three reactive amino functions on
10
11
scale as previously published. The usual Lindseyꢀs
method with a pyrrole concentration of 10 mol L
3
12
ꢀ2
ꢀ1
the other. But in order to increase the possibilities, the
synthesis of a new class of porphyrin delivering two
different functionalities with four identical functional
groups on each face is of great interest. For instance, an
octa-aminophenyl porphyrin possessing four reactive
groups on each porphyrinic side had been reported in
gave the tetraphenylporphyrin derivative 2 with four
nitro and four methoxy groups in moderate yield
(20%). At this stage, several washings of the crude solid
with methanol had to be carried out to remove poly-
mers. In contrast to tetra-o-nitrophenyl porphyrin,
ꢁ
1996 but no selectivity between the eight amino func-
4
tions was possible. The analogous compounds with
5
6
either alkoxy, oxycarbonyl, or bromomethyl substit-
7
uents are also known. To the best of our knowledge,
this problem has been clearly circumvented only with
particular substituents. Actually, in the report of Rose
and co-workers, the chlorine atom in position 5 of the
meso aromatic ring did not allow any further chemistry
ꢁ
To a degassed solution of 2-nitro-5-methoxybenzaldehyde 1 (3.62 g,
3
2
0 mmol) and pyrrole (1.4 cm , 20 mmol) in 2 L of CH
2
Cl
0.528 mL, 2 mmol) was added. The mixture was stirred 24 h and then
2
, BF
3
ÆOEt
2
(
8
2,3-dichloro-5,6-dicyanobenzoquinone (3.4 g, 15 mmol) was added.
After 2 h, triethylamine (1.4 mL, 10 mmol) was added and the
mixture was evaporated. The solid was washed with methanol then
with toluene, which partially dissolved the porphyrin material to give
0
.8 g of an atropisomeric mixture of 2. After evaporation of toluene,
the solid was chromatographed over silica gel eluting with CH Cl
2
2
.
Keywords: Porphyrin; Synthesis; Atropisomer.
*
Then the fast-eluting red bands were collected and evaporated to
yield 0.1 g of an atropisomeric mixture of 2. Finally, the fractions
were combined to afford 0.9 g of 2 (0.98 mmol, 20%).
Corresponding author. Tel.: +33-22-323-6372; fax: +33-22-323-5637;
e-mail: bernard.boitrel@univ-rennes1.fr
0
040-4039/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2003.12.100

1714
C. Ruzi ꢀe et al. / Tetrahedron Letters 45 (2004) 1713–1716
MeO
R
NO2
NO2
OH
OMe
R
pyrrole, BF ·Et O
3
2
NH
N
N
CHO
CHO
Cs CO3, MeI
2
DDQ
DMF, rt
CH Cl2, rt
2
HN
MeO
R
OMe
1
R
(
1) HCl, rt,
OMe
SnCl ·2H O
2
2
atropisomeric mixture of 3: R = NH2
atropisomeric mixture of 2: R = NO2
(
2) KOH
Scheme 1. Synthesis of 3.
1
3
15
which crystallizes out in boiling acetic acid, all the
atropisomers of 2 apart from the aabb one are soluble in
methylene chloride and could therefore be isolated by
merization. Thus, the desired atropisomer is selected
with a masked phenol, then the amino group can be
functionalized and the protective methoxy group
removed. Additionally, displacement of the natural
abundance of the aaaa atropisomer as described by
2 2
elution with CH Cl on silica gel chromatography,
although the atropisomeric mixture of 2 can be used
without further purification.
16
Lindsey for tetrakis-o-aminophenyl porphyrin (TAPP)
is also efficient for this new porphyrin. This method,
when applied to the mixture of atropisomers dissolved in
toluene, leads to the aaaa isomer in 57% yield. As
mentioned earlier, the goal of the synthesis is the prep-
aration of supramolecular systems in which the two
different faces of the macrocycle can be modified selec-
tively.
Accordingly, the four nitro groups of 2 were reduced by
SnCl
After neutralization and silica gel chromatography,
TAMPP 3 was eluted with CH Cl as a mixture of the
2
Æ2H
2
O in HCl at room temperature for 3 days.
2
2
ꢂ
four atropisomers with a global yield of 59%. The
effective ratio of abab:aabb:aaab:aaaa (13:24:56:7) is
slightly different from the statistical abundance
(12.5:25:50:12.5) effectively observed for the tetra-
o-aminophenyl porphyrin.
An illustration of this methodology is depicted in
Scheme 2. After purification of the desired atropisomer
(
the latter were acylated using 3-(chloromethyl)benzoyl
aaaa in our case) of TAMPP 3, the amino functions of
The advantage of our approach is twofold. Firstly, all
the atropisomers can be obtained at this stage, with both
amino and methoxy substituents. Indeed, it is worth
noting that atropisomer aaaa was not isolated by
thermal isomerization when the methoxy was replaced
§
chloride to afford porphyrin 4 in 85% yield. This par-
ticular bifunctional linker was chosen according to
previous papers in which it has been clearly established
that the residues attached via this linker were either
delivered close to the metal center of the porphyrin
14
by a OC H chain. Secondly, the methyl group pro-
25
12
tecting the phenol is known to be removable without the
elevated temperatures, which would induce atropiso-
§
A 100 mL three-neck round-bottom flask equipped with a stir bar
was charged with a,a,a,a-3 (100 mg, 0.13 mmol), dry THF (30 mL),
ꢂ
1
a,b,a,b-3: H NMR (500 MHz, CDCl
N-pyrrole), 3.31 (8H, s, NH ), 3.91 (12H, s, OCH
3
, 283 K) d )2.73 (2H, s,
), 7.08 (4H, d,
3
and Et N (0.3 mL, 2.08 mmol). After cooling in an ice bath,
2
3
3-(chloromethyl)benzoyl chloride (0.143 mL, 1.04 mmol) dissolved
in 5 mL of dry THF was added dropwise. The reaction mixture was
stirred for 10 h at room temperature. The solvent was finally removed
J ¼ 8:85 Hz, 3-Ph), 7.25 (4H, dd, J
1
¼ 8:85 Hz, J
2
¼ 2:83 Hz, 4-Ph),
1
7
.54 (4H, d, J ¼ 2:83 Hz, 6-Ph), 8.97 (8H, s, b-pyr); a,a,b,b-3:
H
NMR (500 MHz, CDCl
(8H, s, NH
3
, 273 K) d )2.77 (2H, s, N-pyrrole), 3.34
under vacuum. The resulting powder was dissolved in CH
directly loaded onto a silica gel chromatography column. The
expected compound eluted with 0.3% MeOH/CH Cl , was obtained
in 85% yield (150 mg); H NMR (500 MHz, CDCl , 298 K) d )2.55
(2H, s, N-pyrrole), 3.25 (8H, s, CH2 benz), 4.00 (12H, s, OCH ), 6.02
(4H, t, J ¼ 7:90 Hz, Haro), 6.41 (4H, d, J ¼ 7:40 Hz, Haro), 6.47 (4H,
d, J ¼ 7:90 Hz, Haro), 6.50 (4H, s), 7.48 (4H, dd, J ¼ 9:20 Hz,
¼ 2:60 Hz, Haro), 7.55 (4H, s, NH), 7.58 (4H, d, J ¼ 2:6 Hz, Haro),
8.69 (4H, d, J ¼ 9:2 Hz, Haro), 8.94 (8H, s, b-pyr); C NMR
(125 MHz, CDCl , 298 K): 44.3, 55.7, 115.0, 121.0, 123.1, 125.6,
2 2
Cl and
2
), 3.90 (12H, s, OCH
¼ 9:15 Hz, J
3
), 7.10 (4H, d, J ¼ 9:15 Hz, 3-Ph),
7
.25 (4H, dd, J
1
2
¼ 3:05 Hz, 4-Ph), 7.48 (4H, d,
2
2
1
1
J ¼ 3:05 Hz, 6-Ph), 8.96 (8H, s, b-pyr); a,a,a,b-3:
H
NMR
3
(
500 MHz, CDCl
NH ), 3.86 (3H, s, OCH
.08 (4H, m, 3-Ph), 7.23 (4H, m, 4-Ph), 7.47 (4H, m, 6-Ph), 8.93 (8H,
3
, 273 K) d 2.79 (2H, s, N-pyrrole), 3.32 (8H, s,
3
2
3
), 3.87 (3H, s, OCH ), 3.88 (6H, s, OCH ),
3
3
7
1
1
s, b-pyr); a,a,a,a-3: H NMR (500 MHz, CDCl
s, N-pyrrole), 3.27 (8H, s, NH ), 3.88 (12H, s, OCH
¼ 8:78 Hz, J ¼ 2:70 Hz, 4-Ph),
3
, 273 K) d 2.77 (2H,
J
2
13
2
3
), 7.07 (4H, d,
J ¼ 8:78 Hz, 3-Ph), 7.23 (4H, dd, J
1
2
3
7
.50 (4H, d, J ¼ 2:70 Hz, 6-Ph), 8.94 (8H, s, b-pyr); HR-MS (ESI-
126.1, 128.1, 130.5, 131.8; HR-MS (ESI-MS) m=z ¼ 1425:3351
þ
þ
ꢀ3
MS) m=z ¼ 795:3400 [M+H]
C
48
H
43
ꢀ1
N
8
O
4
requires 795.3407; UV–
[M+Na]
C
80
H
62
ꢀ1
N
8
O
8
ꢀ1
Cl
4
Na requires 1425.3342; UV–vis (CH
2
Cl
2
)
ꢀ3
ꢀ1
vis (CH
(
2
Cl
6.7), 589 (7.6), 646 (2.5).
2
) k nm (10 e, M cm ) 414 (351.4), 515 (26.0), 551
k nm (10 e, M cm ) 423 (351.2), 516 (24.4), 549 (4.1), 589 (5.3),
645 (1.5).

C. Ruzi ꢀe et al. / Tetrahedron Letters 45 (2004) 1713–1716
1715
Cl
Cl
Cl
Cl
MeO
NH2
NH2
O
NH2
O
NH
HN
MeO
N
OMe
OMe
H N
NH
OMe
O
NH
N
N
2
N
HN
NH
2
b
O
NH
MeO
N
a
NH
HN
OMe
HN
N
HN
H N
NH2
2
H N
MeO
OMe
2
3
(αααα)
MeO
4
OMe
OMe
3
(atropisomeric mixture)
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
O
O
O
O
c
NH
d
NH
HN
HN
O
O
O
NH
HO
O
NH
MeO
N
N
HN
OH
NH
HN
OMe
NH
HN
HN
N
N
5
HO
6
MeO
OH
OMe
Scheme 2. Reagents and conditions: (a) SiO
2
, toluene, 80 °C, 57%; (b) 3-(chloromethyl)benzoyl chloride, NEt
Cl , 78%.
, 0–40 °C, BBr
3
, THF, 0 °C to rt, 85%; (c) i. NaH,
pyrazole, THF, rt; ii. 4 in THF, 55 °C, 28%; (d) CH
2
2
3
1
7
||
itself or oriented inside the pocket formed by the
in 78% yield. The phenol functions could eventually be
converted into ether or ester groups by a conventional
method.
18
pickets. Pyrazole was then allowed to react on the ꢃU-
Shapedꢀ acceptor 4 according to a method reported by
Lam et al. to afford porphyrin 5 with a yield of 28%.
19
–
This moderate yield, lower than that obtained by
This particular 2,5 substitution pattern with the hydroxy
groups in the meta positions can be considered an
advantage as the influence of the latter is expected to be
negligible on the geometry of the superstructure on the
other face of the porphyrin. This property was probed
by a comparison of the chemical shifts of different
protons. For example, the protons of the pyrazolyl unit
in 6 lead to the following signals 7.24 (d), 6.64 (d), and
20
Naruta and Sasaki for a porphyrin bearing only three
pyrazolyl pickets, can be attributed to the steric hin-
drance induced by the four bulky pickets. The depro-
tection of the phenol groups was achieved by reaction
2 2
with boron tribromide in CH Cl to afford porphyrin 6
5.95 (t) instead of 7.05 (d), 6.53 (d), and 5.80 (t) in the
analogous compound without the hydroxyl group,
21
prepared from TAPP. This clearly means that the
–
A 50 mL three-neck round-bottom flask equipped with a stirrer bar
was charged with pyrazole (50 mg, 0.74 mmol) in 10 mL of THF then
NaH (20 mg, 0.82 mmol) was added. After 30 min, the mixture was
added to porphyrin 4 (130 mg, 0.093 mmol) dissolved in 20 mL of
THF. The resulting mixture was stirred at 55 °C for 24 h. THF was
finally removed under vacuum. The resulting powder was dissolved
|
|
To a stirred solution of porphyrin 5 (40 mg, 0.026 mmol) in 10 mL of
dry CH Cl , 20 lL (0.21 mmol) of BBr was added dropwise at 0 °C.
The reaction mixture was allowed to stir at reflux for 48 h and then
2
2
3
cooled to room temperature. Then ethyl acetate and ice were added.
After neutralization with K
with ethyl acetate. The organic layers were combined, dried over
MgSO and evaporated in vacuo. The crude product was purified by
flash chromatography and the desired compound, eluted with a
mixture of 6.4% MeOH/CHCl , was obtained in 78% yield (30 mg);
, 303 K) d )2.90 (2H, s, N-pyrrole),
4.77 (8H, s, CH2 benz), 5.86 (4H, s, Hpyr), 6.03 (4H, t, J ¼ 7:80 Hz,
2 3
CO , the reaction mixture was extracted
in CHCl
3
and directly loaded onto a silica gel chromatography
, was
, 298 K)
d )2.32 (2H, s, N-pyrrole), 2.44 (8H, s, CH2 benz), 4.04 (12H, s,
OCH
column. The expected compound eluted with 2% MeOH/CHCl
3
4
1
obtained in 28 % yield (40 mg); H NMR (500 MHz, CDCl
3
3
1
3
), 5.14 (4H, s, Haro), 5.88 (4H, d, J ¼ 7:70 Hz, Haro), 5.95 (4H,
H NMR (500 MHz, DMSO-d
6
t, J ¼ 1:93 Hz, Hpyr), 6.11 (4H, t, J ¼ 7:70 Hz, Haro), 6.64 (4H, d,
J ¼ 1:90 Hz, Hpyr), 6.81 (4H, d, J ¼ 7:64 Hz, Haro), 7.24 (4H, d,
H
aro), 6.24 (4H, d, J ¼ 7:43 Hz, Haro), 6.57 (4H, d, J ¼ 7:47 Hz, Haro),
J ¼ 1:43 Hz, Hpyr), 7.46 (4H, dd, J
1
¼ 2:86 Hz, J
2
¼ 8:90 Hz, Haro),
7.02 (4H, s, Haro), 7.12 (4H, s, Hpyr), 7.14 (4H, s, Haro), 7.24 (4H, d,
7
.75 (4H, d, J ¼ 2:86 Hz, Haro), 8.08 (4H, d, J ¼ 8:90 Hz, Haro), 8.19
4H, s, NH), 8.76 (8H, s, b-pyr); C NMR (125 MHz, CDCl , 298 K)
d 52.8, 56.1, 105.6, 115.2, 121.1, 124.5, 126.1, 127.5, 128.0, 129.1,
J ¼ 8:57 Hz, Haro), 7.27 (4H, s, Hpyr), 7.86 (4H, d, J ¼ 8:57 Hz, Haro),
13
13
(
3
6
8.88 (8H, s, Hpyr), 9.22 (4H, s, OH); C NMR (125 MHz, DMSO-d ,
303 K) d 54.2, 105.6, 116.5, 123.6, 125.5, 126.5, 127.5, 128.1, 129.9,
1
29.5, 131.4, 139.2, 156.5, 166.4; HR-MS (ESI-MS) m=z ¼ 1553:5787
130.1, 137.7, 139.4, 166.2; HR-MS (ESI-MS) m=z ¼ 1497:5140
þ
þ
[
M+Na]
C
92
H
74
ꢀ1
N
16
ꢀ1
O
8
Na requires 1553.5773; UV–vis (CH
2
Cl
2
)
[M+Na]
C
88
H
66
ꢀ3
N
16
O
8
Na requires 1497.5147; UV–vis (CHCl
ꢀ1
3
/10%
ꢀ3
ꢀ1
k nm (10 e, M cm ) 428 (370.3), 521 (33.8), 556 (6.9), 595 (6.7),
53 (3.1).
MeOH) k nm (10 e, M cm ) 428 (258.3), 521 (16.9), 557 (5.4), 594
6
(5.2), 653 (2.5).

1716
C. Ruzi ꢀe et al. / Tetrahedron Letters 45 (2004) 1713–1716
geometries observed in the case of TAPP derivatives should
be retained in compounds synthesized from TAMPP.
Ricard, D.; Didier, A.; LꢀHer, M.; Boitrel, B. Chembio-
chem 2001, 144–148.
. Collman, J. P.; Broring, M.; Fu, L.; Rapta, M.; Schwenn-
inger, R.; Straumanis, A. J. Org. Chem. 1998, 63, 8082–
3
4
5
As a possible use of this new starting material, we have
herein described the preparation of a bis-chelating
compound in the aaaa geometry where the four
hydroxyl groups could be employed, for instance, to
incorporate the molecule in a membrane. But another
advantage of this synthesis consists in the fact that all
the atropisomers can be obtained. Therefore, applica-
tions of the aabb or abab atropisomers in the devel-
opment of chiral and/or water-soluble molecules can be
foreseen.
8
083.
. Rose, E.; Kossanyi, A.; Quelquejeu, M.; Soleilhavoup, M.;
Duwavran, F.; Bernard, N.; Lecas, A. J. Am. Chem. Soc.
1
996, 118, 1567–1568.
. Foxon, S. P.; Lindsay, J. R.; OꢀBrien, P.; Reginato, G.
J. Chem. Soc., Perkin Trans. 2 2001, 1145–1153; Zhang,
J.-L.; Zhou, H.-B.; Huang, J.-S.; Che, C.-M. Chem. Eur.
J. 2002, 8, 1554–1562; Naruta, Y.; Goto, M.; Tawara, T.;
Tani, F. Chem. Lett. 2002, 663–664.
. Tsuchida, E.; Komatsu, T.; Arai, K.; Yamada, K. H.;
Nishide, H.; Boettscher, C.; Fuhrhop, J.-H. J. Chem. Soc.,
Chem. Commun. 1995, 1063–1064; Nakagawa, H.; Nag-
ano, T.; Higuchi, T. Org. Lett. 2001, 3, 1805–1807.
. Jux, N. Org. Lett. 2000, 2, 2129–2132.
6
In conclusion, we report the synthesis of a new bis-
functionalized porphyrin, for which a face selection can
be performed. We are currently using this methodology
for the design of new bi-chelating agents as well as
water-soluble dioxygen carriers. Therefore, different
supramolecular compounds should be developed in
7
8
. Lecas, A.; Boitrel, B.; Rose, E. Bull. Soc. Chim. Fr. 1991,
1
28, 407–413.
9. Nishino, N.; Mihara, H.; Kiyota, H.; Kobata, K.; Fuji-
moto, T. J. Chem. Soc., Chem. Commun. 1993, 162–163.
10. Iyobe, A.; Uchida, M.; Kamata, K.; Hotei, Y.; Kusama,
H.; Harada, H. Chem. Pharm. Bull. 2001, 49, 822–829.
11. Skiles, J. W.; Cava, M. P. J. Org. Chem. 1979, 44, 409–
22
widespread areas such as enzyme mimics, chiral
24
23
catalysis for oxidation, and cyclopropanation, or
molecular recognition.
25
4
12.
1
2. Lindsey, J. S.; Schreiman, I. C.; Hsu, H. C.; Kearney, P.
C.; Marguerettaz, A. M. J. Org. Chem. 1987, 52, 827–836.
3. Collman, J. P.; Gagne, R. R.; Reed, C. A.; Halbert, T. R.;
Lang, G.; Robinson, W. T. J. Am. Chem. Soc. 1975, 97,
1
Acknowledgements
1
427–1439.
14. Arai, T.; Tsukuni, A.; Kawazu, K.; Aoi, H.; Hamada, T.;
We thank R ꢀe gion Bretagne for a grant (C.R.) and the
Centre National de la Recherche Scientifique for finan-
cial support.
Nishino, N. J. Chem. Soc., Perkin Trans. 2 2000, 1381–
1
390.
5. Greene, T. W.; Wuts, P. G. M. Protective Groups in
Organic Synthesis, 3rd ed.; John Wiley & Sons: New York,
1
1
999.
16. Lindsey, J. J. Org. Chem. 1980, 45, 5215.
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