A rapid synthesis of new benzene-centered porphyrin trimers

Article abstract of DOI:10.1002/jhet.5570440515

(Chemical Equation Presented) In connection with our study of the capability of forming ordered self-assembled monolayers on gold substrates, we described the full details concerning the rapid synthesis of two rigid, star-shaped D3-symmetric arrays with a benzene core attached to three identical metalloporphyrins containing either ethyldisulfide functions or thienyl groups.

Full text of DOI:10.1002/jhet.5570440515

Sep-Oct 2007
1071
A Rapid Synthesis of New Benzene-centered Porphyrin Trimers
Cyril A. Papamicaël, a* Olivier Monginb and Albert Gossauerc
a: UMR 6014 IRCOF, CNRS, Université et INSA de Rouen, B.P. 08, 76131 Mont-Saint-Aignan Cédex, France.
Fax: (33)2 35 52 29 62, E-mail: cyril.papamicael@insa-rouen.fr
b: Synthèse et ElectroSynthèse Organiques (CNRS, UMR 6510), Université de Rennes 1, Institut de Chimie,
Campus Scientifique de Beaulieu, Bât 10A, F-35042 Rennes Cedex, France
c: Institut für Organische Chemie der Universität, Chemin du Musée 9, CH-1700 Fribourg, Switzerland.
Received November 3, 2006
SSEt
SSEt
S
N
N
N
S
S
S
N
N
NZn
ZnN
N
N
N
N
S
N
NZn
N
ZnN
N
S
N N
NZnN
S
NZnN
N N
S
S
EtSS
In connection with our study of the capability of forming ordered self-assembled monolayers on gold
substrates, we described the full details concerning the rapid synthesis of two rigid, star-shaped D3-
symmetric arrays with a benzene core attached to three identical metalloporphyrins containing either
ethyldisulfide functions or thienyl groups.
J. Heterocyclic Chem., 44, 1071 (2007).
INTRODUCTION
RESULTS AND DISCUSSION
In order to obtain a porphyrin trimer with ethyldisulfide
functions 1b, we synthesized the precursor 5b via cross-
coupling methodology. Starting from 3-iodoaniline (Scheme
I), a one-pot reaction [13] afforded 3-iodobenzenethiol 3b.
This compound was cleanly reacted with N-ethylthio-
phtalimide [14] to lead to the disulfide derivative 3c. Its
reaction with trimethylsilylacetylene using palladium(II) as
a catalyst afforded, after cleavage of the trimethylsilyl
protecting groups, ethyl-(3-ethynylphenyl)disulfide 4b
which was used in a coupling reaction with porphyrin 5a
[12] (Scheme II). Reaction of 1,3,5-triethynylbenzene with
5b in the presence of triphenylarsine as the ligand of the
palladium catalyst [12] led to the porphyrin trimer 1b.
To synthesize the porphyrin trimer 2, the precursor 7c
was needed. We first tried to react 4-iodobenzaldehyde, 2-
thiophenecarboxaldehyde and pyrrole with a catalytic
amount of trifluoroacetic acid [15] for 1 hour at 20°C.
But, only an inseparable mixture of iodinated compounds
was obtained after treatment with DDQ. An inseparable
mixture was also obtained by reaction of dipyrromethane
6, prepared by condensation of pyrrole and 2-thiophene-
carboxaldehyde, with 1 equivalent of 4-iodobenzaldehyde
under boron trifluoride ethyl etherate catalysis [15] for 30
min at 20°C. Then, 4-acetamidobenzaldehyde was used
With the increasing demand for the ability to sculpt
matter into precise functioning devices of nanoscale
dimensions, the molecular level design of functional
materials is an overarching theme in much of the synthetic
materials literature [1]. Molecular engineering of
porphyrin has become of great interest for use in
molecular electronics [2a,b], nonlinear optics [2c],
information storage [2d,e], molecular sensors [2f,g],
electrochromic devices [2h]. Thus, the synthesis of
multiporphyrin arrays is an area of active interest [3]. The
formation of self-assembled monolayers occurs readily
upon exposure of thiol-derivatized porphyrins to a gold
substrate. A variety of porphyrin-containing compounds
bearing free thiols [4-6], S-acetylthio esters [5-10] or
disulfides [10,11] have been prepared. In a previous paper,
we reported the synthesis of some porphyrin trimers
bearing meta-thioanisole units at the apical positions like
compound 1a [12]. In connection with our study of the
capability of forming ordered self-assembled monolayers
on gold substrates, we have synthesized porphyrin trimers
containing either ethyldisulfide functions or thienyl
groups. The aim of this paper is to provide full details
concerning the synthesis leading to compounds 1b and 2
(Figure I).

1072
C. A. Papamicaël, O. Mongin, A. Gossauer
Vol 43
SR
SR
N
N
S
N
N
S
Zn
Zn
N
N
S
N
N
Scheme IV
N
S
N
Zn
N
N
N
Zn
N
N
N
S
S
2
1a : R = Me
1b : R = SEt
N
N
N
Zn
N
N
N
N
N
S
Zn
S
Reagents, conditions and yields. (a) Zn(OAc)2, CHCl3, MeOH, reflux, 1h
S
(94%); (b) 1,3,5-triethynylbenzene, Pd(PPh3)4, DMF, Et3N, 45°C, 16h
(84%).
RS
Figure 1
instead of 4-iodobenzaldehyde in a reaction with 2-thio-
phenecarboxaldehyde and pyrrole using either trifluor-
acetic acid or boron trifluoride ethyl etherate as a catalyst.
But, these reactions failed. Finally, by using a substituent
scrambling [16] strategy (Scheme III), the porphyrin 7a
was synthesized after condensation of dipyrromethane 6
and 4-acetamidobenzaldehyde under boron trifluoride
ethyl etherate catalysis.
Hydrolysis of 7a with 20 % aqueous hydrochloric acid
afforded amine 7b (Scheme IV). Thus, the amino group
was reacted with isoamylnitrite and then potassium iodide
to lead to a mixture of 4-iodophenylporphine 7c and deio-
dinated compound. The porphyrin 7c was transformed in
94 % yield into the corresponding zinc chelate 7d under
standard conditions with zinc acetate and thereafter
Scheme II
I
N
N
N
N
Zn
S
Et
S
5a
I
a
Scheme 1
I
R'
N
N
N
N
Zn
5b
R
SEt
3a : R = NH2
3b : R = SH
3c : R = S-SEt
b
a
b
S
c
4a : R' = SiMe3
4b : R' = H
d
I
Reagents, conditions and yields. (a) NaNO2, HCl, 0°C; C2H5CSSK,
H2O, 40°C, 30 min; KOH, EtOH, reflux, 6h; H2SO4 then PPh3, MeOH,
20°C, 15h (21%); (b) N-(ethylthio)phtalimide, benzene, reflux, 15h
(100%); (c) HCꢀCSiMe3 (excess), Pd(PPh3)2Cl2, CuI, Toluene, Et3N,
40°C, 4h (84%); (d) TBAF on silica gel, CHCl3, 20°C, 7 min (86%).
1b
Reagents, conditions and yields. (a) 4b, Pd2dba3, AsPh3, CuI, DMF, Et3N,
75°C, 3h (22%); (b) 1,3,5-triethynylbenzene, Pd2dba3, AsPh3, DMF,
Et3N, 50°C, 4h (24%).

Sep-Oct 2007
A Rapid Synthesis of New Benzene-centered Porphyrin Trimers
1073
Scheme III
Scheme IV
I
S
a
S
O
2 x
S
+
NH
NH HN
6
N
N
N
N
S
a
b
7c
2
Zn
S
b
NH
N
R
S
N
HN
7d
S
7a: R = NHAc
7b: R = NH2
7c: R = I
c
d
Reagents, conditions and yields. (a) Zn(OAc)2, CHCl3, MeOH, reflux,
S
1h (94%); (b) 1,3,5-triethynylbenzene, Pd(PPh3)4, DMF, Et3N, 45°C,
16h (84%).
Reagents, conditions and yields. (a) BF3.O(Et)2, 20°C, 20 min; (b) 4-
acetamidobenzaldehyde, BF3.O(Et)2, CHCl3, 20°C, 1h then DDQ, 20°C,
1h (7%); (c) HCl 20%, reflux, 5h (65%); (d) isoamylnitrite, CHCl3,
CH3COOH, 0°C, 15 min then KI, 0°C to 45°C, 30 min (38%).
phosphine)palladium, tris(dibenzylideneacetone)dipalladium
(Pd2dba3), triphenylarsine and tetrabutylammonium fluoride
(TBAF) were purchased from Aldrich Chemie (CH-9471
Buchs); dimethylformamide (DMF), tetrahydrofuran (THF),
trimethylsilylacetylene (TMSA), and other reagents from Fluka
Chemie AG (CH-9471 Buchs). Experiments using DMF, AsPh3
or Pd2dba3 should be done with caution. Indeed, DMF is a
potential cancer hazard and may cause liver and kidney damage.
This substance has caused adverse reproductive and fetal effects
in animals. Concerning Pd2dba3, it may cause cardiac
disturbances, central nervous system effects and kidney damage.
Finally, for AsPh3, the toxicological properties of this material
have not been fully investigated but it is very toxic to aquatic
organisms and may cause long-term adverse effects in the
aquatic environment.
reacted with 1,3,5-triethynylbenzene in the presence of
palladium(0) as a catalyst to give the porphyrin trimer 2.
However, it is noteworthy to specify that porphyrins 7c
and 7d were obtained pure with difficulty due to the
presence of the corresponding deiodinated porphyrins.
In conclusion, new star-shaped D3-symmetric arrays
containing sulfur atoms were synthesized. Their capability
of forming ordered self-assembled monolayers on gold
surface are beyond the scope of this paper and will be
described later.
Triporphyrin (1b). Air was removed from a soln. of 5b
(8.5 mg, 7.8 mmol) and 1,3,5-triethynylbenzene [12] (0.295
mg, 1.96 mmol) in 4 mL of DMF/Et3N (5:1) by blowing argon
for 20 min. Then Pd2dba3 (0.54 mg, 0.59 mmol) and AsPh3
(1.44 mg, 4.7 mmol) were added, and deaeration was
continued for 10 min. Thereafter, the mixture was heated at
50°C for 4 h. The solvent was removed under reduced
pressure and the crude product was purified by two successive
CC (CHCl3/hexane: gradient from 1:1 to 7:3) to yield 1.4 mg
(24%) of 1b. UV/VIS (CH2Cl2) 292 (5.18), 424 (6.11), 550
EXPERIMENTAL
General Data. All air- or water-sensitive reactions were
carried out under argon. Solvents were generally dried and
distilled prior to use. Reactions were monitored by thin-layer
chromatography (TLC) on E. Merck silica gel 60F254 (0.2 mm)
precoated aluminium foils. Column chromatography (CC): E.
Merck silica gel 60 (230-400 mesh). Melting points (mp) were
determined with a hot stage apparatus (Thermovar, C. Reichert
AG, Vienna) equipped with a digital thermometer. UV/VIS
spectra were recorded on a Hewlett-Packard-8452A diode-array
spectrophotometer; ꢀmax (log ꢁ) in nm. NMR: Varian Gemini 200
(1H, 200.00 MHz; 13C: 50.30 MHz), Bruker-AM 360 (1H, 360.14
MHz), or Bruker Avance DRX 500 (1H: 500.13 MHz, 13C:
125.76 MHz) in CDCl3 solutions unless otherwise stated; 1H and
13C chemical shifts (ꢂ) are given in ppm relative to Me4Si as
internal standard, J values in Hz. Mass spectra: Vacuum
Generators Micromass 7070E instrument equipped with a data
system DS 11-250, EI (electron ionization): acceleration voltage
70 eV, CI (chemical ionization) with methane as ionization gas,
FAB (fast atom bombardment): in 2-nitrobenzyl alcohol with Ar
at 8 kV; FT/ICR mass spectrometer Bruker 4.7T BioAPEX II,
ES+ (electrospray ionization, positive mode). Tetrakis(triphenyl-
1
(4.85), 590 (4.28). H NMR (360.14 MHz) ꢂ 1.38 (t, J = 7.3,
9H, CH3CH2), 1.85 (s, 36H, o-CH3 mesityl), 2.64 (s, 18H, p-
CH3 mesityl), 2.84 (q, J = 7.3, 6H, CH3CH2), 7.30 (s, 12H, H-
mesityl), 7.38 (t, J = 7.8, 3H, H-5 ethyldisulfanylphenyl),
7.52 (d, J = 7.7, 3H, H-6 ethyldisulfanylphenyl), 7.56 (d, J =
7.7, 3H, H-4 ethyldisulfanylphenyl), 7.86 (m, 3H, H-2
ethyldisulfanylphenyl), 7.93 and 8.25 (AA'XX', 2 x apparent
d, J = 8.0, 12H, H-outside phenylene on porphine), 8.02 and
8.31 (AA'XX', 2 x apparent d, J = 8.3, 12H, H-inside
phenylene on porphine), 8.03 (s, 3H, H-benzenetriyl), 8.81
and 8.90 (2 x d, J = 4.7, 12H, ꢃꢄꢅ on porphine outside), 8.83
and 8.95 (2 x d, J = 4.6, 12H, ꢃꢄꢅ on porphine inside). ES+-
MS m/z: (in CHCl3/MeOH/ HCOOH) 1410.0 ([M-
3Zn+8H]2+), 940.2 ([M-3Zn+9H]3+) (calc. avg. mass for
C192H144N12S6Zn3: 3007.83).

1074
C. A. Papamicaël, O. Mongin, A. Gossauer
Vol 43
Triporphyrin (2). Air was removed from a soln. of 7d (5.9
1
32.7 (CH2), 94.7 (C-3), 126.1 (C-6), 130.3 (C-5), 135.2, 135.4
(C-2, C-4), 140.1 (C-1). Anal. Calcd for C8H9IS2 (296.18): C,
32.44; H, 3.06. Found: C, 32.30; H, 3.27. EI-MS: 296 (M+, 100
%), 108 ([M-I-SEt]+, 43 %).
mg, 7.2 mmol; determined by H-NMR from an inseparable
mixture with the deiodinated corresponding compound) and
1,3,5-triethynylbenzene (0.297 mg, 2.0 mmol) in 2 mL of
DMF/Et3N (5:1) by blowing argon for 20 min. Then Pd(PPh3)4
(1.6 mg, 1.4 mmol) was added, and deaeration was continued for
10 min. Thereafter, the mixture was heated at 45°C for 16 h. The
solvent was removed under reduced pressure and the crude
product was purified by CC (CHCl3/hexane: gradient from 4:1 to
17:3) to yield 3.7 mg (84%) of 2. UV/VIS (CH2Cl2) 298 (4.95),
[(3-Ethyldisulfanylphenyl)ethynyl]trimethylsilane (4a). Air
was removed from a solution of 3c (318 mg, 1.07 mmol) in 15
mL of toluene/Et3N (5:1) by blowing argon for 30 min. Then
Pd(PPh3)2Cl2 (17.5 mg, 0.025 mmol), CuI (9.5 mg, 0.05 mmol)
and TMSA (0.15 mL, 10.8 mmol) were added. Thereafter the
mixture was stirred at 40°C for 4 h. The solvent was removed
under reduced pressure and the crude product was purified by
CC (gradient from hexane to CH2Cl2/hexane 1:19) to yield 240
1
426 (6.02), 554 (4.76), 592 (4.19), 598 (4.16). H NMR (500.13
MHz) ꢀ 7.51 (dd, J = 5.4, 3.4, 3H, H-4 thienyl), 7.52 (dd, J =
5.4, 3.4, 6H, H-4 thienyl), 7.85 (dd, J = 5.4, 1.3, 3H, H-5
thienyl), 7.86 (dd, J = 5.4, 1.3, 6H, H-5 thienyl), 7.93 (dd, J =
3.4, 1.3, 3H, H-3 thienyl), 7.94 (dd, J = 3.4, 1.3, 6H, H-3
thienyl), 8.04 and 8.28 (AA'XX', 2 x apparent d, J = 8.3, 12H,
H-phenylene), 8.05 (s, 3H, H-benzenetriyl), 9.00 and 9.20 (2 x
d, J = 4.7, 12H, ꢁ-H on porphine inside), 9.16 and 9.18 (2 x d, J
= 4.7, 12H, ꢁꢂꢃ on porphine outside). ES+-MS m/z: (in CHCl3/
HCOOH) 2043.5 ([M-3Zn+7H]+), 1022.4 ([M-3Zn+8H]2+),
681.7 ([M-3Zn+9H]3+); (in CHCl3/MeOH) 1116.5 ([M+2H]2+),
744.3 ([M+3H] 3+) (calc. avg. mass for C126H66N12S9Zn3:
2232.67).
1
mg (84%) of 4a as a pale yellow oil. H NMR (200.00 MHz) ꢀ
0.26 (s, 9H, SiMe3), 1.31 (t, J = 7.3, 3H, CH3), 2.75 (q, J = 7.3,
2H, CH2), 7.24 (t, J = 7.3, 1H, H-5), 7.32 (ddd, J = 7.6, 1.8, 1.4,
1H, H-6), 7.49 (ddd, J = 7.3, 1.8, 1.4, 1H, H-4), 7.64 (m, 1H, H-
2). 13C NMR (50.30 MHz) ꢀ 0.4 (SiMe3), 14.6 (CH3), 33.2
(CH2), 95.3 (CꢄC-Si), 104.8 (CꢄC-Si), 124.4 (C-1), 127.8 (C-4),
129.2 (C-5), 130.7 and 130.9 (C-2, C-6), 138.5 (C-3). Anal.
Calcd for C13H18S2Si (266.49): C, 58.59; H, 6.81. Found: C,
58.48; H, 6.97. EI-MS: 266 (M+, 83 %), 251 ([M-CH3]+, 100 %),
222 (31 %), 190 (39 %).
Ethyl-(3-ethynylphenyl)disulfide (4b). To TBAF on silica gel
(345 mg, 0.38 mmol) under an atmosphere of argon was added a
solution of 4a (95 mg, 0.36 mmol) in 5.5 mL of CHCl3. The
mixture was stirred at 20°C for 7 min. A few grains of CaCl2 were
added and the solution was filtered through a column of silica gel
(CH2Cl2/ hexane 1:9) to yield 60 mg (87%) of 4b as a pale yellow
oil. 1H NMR (360.14 MHz) ꢀ 1.31 (t, J = 7.4, 3H, CH3), 2.75 (q, J
= 7.4, 2H, CH2), 3.10 (s, 1H, CꢄCH), 7.27 (t, J = 7.7, 1H, H-5),
7.33 (ddd, J = 7.7, 1.9, 1.4, 1H, H-4), 7.51 (ddd, J = 7.7, 1.9, 1.4,
1H, H-6), 7.66 (t, J = 1.9, 1H, H-2). 13C NMR (50.30 MHz) ꢀ 14.1
(CH3), 32.7 (CH2), 77.8 (CꢄC-H), 82.9 (CꢄC-H), 122.9 (C-3),
127.4 (C-6), 128.7 (C-5), 130.2 and 130.3 (C-2, C-4), 138.1 (C-1).
Anal. Calcd for C10H10S2 (194.31): C, 61.81; H, 5.19. Found: C,
62.12; H, 4.96. CI-MS: 194 (MH+, 15 %).
[5-[4-[[3-(Ethyldisulfanyl)phenyl]ethynyl]phenyl]-15-(4-
iodophenyl)-10,20-bis(mesityl)porphinato(2-)]zinc (5b). Air
was removed from a soln. of 5a [12] (77 mg, 75.9 mmol) and 4b
(19 mg, 98.3 mmol) in 13 mL of DMF/Et3N (5:1) by blowing
argon for 20 min. Then Pd2(dba)3 (5.2 mg, 5.7 mmol), AsPh3 (14
mg, 45.7 mmol) and CuI (2.2 mg, 11.6 mmol) were added, and
deaeration was continued for 10 min. Thereafter, the mixture
was heated at 75°C for 3 h. The solvent was removed under
reduced pressure and the crude product was purified by CC
(CH2Cl2/hexane: gradient from 2:23 to 1:4) to yield 17.7 mg
(22%) of 5b. UV/VIS (CH2Cl2) 292 (4.53), 421 (5.65), 549
(4.33), 589 (3.75). 1H NMR (360.14 MHz) ꢀ 1.37 (t, J = 7.3, 3H,
CH2CH3), 1.82 (s, 12H, o-CH3 mesityl), 2.63 (s, 6H, p-CH3
mesityl), 2.82 (q, J = 7.3, 2H, CH2CH3), 7.28 (s, 4H, H-mesityl),
7.38 (t, J = 7.8, 1H, H-5 ethyldisulfanylphenyl), 7.51 (dt, J =
7.8, 1.0, 1H, H-6 ethyldisulfanylphenyl), 7.55 (ddd, J = 7.8, 1.9,
1.0, 1H, H-4 ethyldisulfanylphenyl), 7.85 (t, J = 1.9, 1H, H-2
ethyldisulfanylphenyl), 7.92 and 8.23 (AA'XX', 2 x apparent d, J
= 8.3, 4H, H-ethynylphenyl), 7.96 and 8.07 (AA'XX', 2 x
apparent d, J = 8.1, 4H, H-iodophenyl), 8.78 and 8.86 (2 x d, J =
4.7, 4H, ꢁꢂꢃ on porphine H-12, H-13, H-17, H-18), 8.79 and
8.89 (2 x d, J = 4.7, 4H, ꢁꢂꢃ on porphine H-2, H-3, H-7, H-8).
FAB-MS: 1081.2 (calc. avg. mass for C60H47IN4S2Zn: 1080.46).
meso-(Thien-2-yl)dipyrromethane (6). A soln. of 2-thio-
phenecarboxaldehyde (0.93 mL, 10 mmol) and pyrrole (28 mL,
3-Iodobenzenethiol (3b). 4-Iodoaniline (5.0 g, 22.8 mmol)
was added to a mixture of concd. HCl (4.6 mL) and crushed ice
(4.6 g). After cooling to 0°C, a cold soln. of sodium nitrite (1.67
g, 24.2 mmol) in water (4 mL) was added, the temperature being
kept below 4°C. The cold diazonium soln. was then slowly
added to a mixture of potassium ethyl xanthate (4.26 g, 26.6
mmol) in water (5.5 mL) at 40°C. The mixture was stirred at this
temperature for 30 min, then cooled to 20°C. It was extracted
with Et2O, the combined organic layers were washed with 10%
aq. NaOH, then with water and dried (Na2SO4). The solvent was
removed under reduced pressure. The residue was dissolved in
95% ethanol and solid KOH (8 g) was added. The mixture was
refluxed for 6 h then EtOH was evaporated and water was
added. The aq. layer was washed with Et2O, then acidified with
60 mL H2SO4 (6 N) and extracted with CH2Cl2. After drying
(Na2SO4), the solvent was evaporated. The residue was poured
into a soln. of triphenylphosphine (3.0 g, 11.4 mmol) in MeOH
(66 mL) and water (15 mL). After stirring at 20°C under argon
for 15 h, the mixture was extracted with CH2Cl2 and the
combined organic layers were dried (Na2SO4). The solvent was
removed under reduced pressure and the crude product was
purified by CC (hexane) to yield 1.74 g (32%) of 3b as an oil. 1H
NMR (200.00 MHz) ꢀ 3.44 (s, 1H, SH), 6.94 (t, J = 7.8, 1H, H-
5), 7.21 (dt, J = 7.8, 1.7, 1H, H-6), 7.47 (dt, J = 7.8, 1.7, 1H, H-
4), 7.62 (t, J = 1.7, 1H, H-2). 13C NMR (50.30 MHz) ꢀ 94.6 (C-
3), 128.3 (C-6), 130.4 (C-5), 133.2 (C-1), 134.6 (C-4), 137.4 (C-
2). Anal. Calcd for C6H5IS (236.07): C, 30.53; H, 2.13. Found:
C, 30.80; H, 1.97. EI-MS: 236 (M+, 100 %), 109 ([M-I]+, 97 %).
Ethyl-(3-iodophenyl)disulfide (3c). A soln. of 3b (500 mg,
2.12 mmol) and N-(ethylthio)phtalimide [14] (658 mg, 3.18
mmol) in benzene (25 mL) was refluxed under argon for 15 h.
After cooling to 5°C, phthalimide was removed by filtration, the
filtrate was evaporated under reduced pressure and the residue
was purified by CC (CH2Cl2/hexane 1:9) to yield 621 mg (99%)
1
of 3c as an oil. H NMR (200.00 MHz) ꢀ 1.32 (t, J = 7.3, 3H,
CH3), 2.76 (q, J = 7.3, 2H, CH2), 7.04 (t, J = 7.8, 1H, H-5), 7.49
(ddd, J = 7.8, 1.8, 1.2, 1H, H-6), 7.54 (dt, J = 7.8, 1.2, 1H, H-4),
7.89 (t, J = 1.8, 1H, H-2). 13C NMR (50.30 MHz) ꢀ 14.2 (CH3),

Sep-Oct 2007
A Rapid Synthesis of New Benzene-centered Porphyrin Trimers
1075
404 mmol) was degassed for 30 min with argon. Then,
BF3.O(Et)2 (0.37 mL, 3.0 mmol) was injected. The mixture was
stirred for 30 min at 20°C, then diluted with CH2Cl2 and
immediately washed with 0.1 N aq. NaOH (~50 mL). The
organic layer was washed with water and dried (Na2SO4).
Evaporation of the solvent under reduced pressure resulted in a
brown oil. Unreacted pyrrole was removed by vacuum
distillation at 20°C, yielding a tacky solid with light brown
splotches. This solid was washed with 500 mL of hexane and
collected by filtration. The crude product was purified by CC
(CH2Cl2/hexane/Et3N 10:10:0.1) to yield 1.39 g (61%) of 6 as a
crude product was purified by CC (CH2Cl2/hexane 7:13) to yield
1
to 8.9 mg of a mixture of 7c (5.3 mg, 38%; determined by H-
NMR) and the corresponding deiodinated compound (3.6 mg;
1
determined by H-NMR). Purification of a small amount of the
mixture by using a Lobar® (310-25) Lichroprep Si60 (40-63
mm) Merck, provided pure 7c for analysis. UV/VIS (CH2Cl2)
308 (4.19), 424 (5.55), 520 (4.20), 560 (3.89), 592 (3.73), 598
1
(3.73). H NMR (360.14 MHz) ꢀ -2.70 (s, 2H, NH), 7.51 (dd, J
= 5.2, 3.3, 3H, H-4 thienyl), 7.86 (dd, J = 5.2, 1.1, 3H, H-5
thienyl), 7.92 (dd, J = 3.3, 1.1, 3H, H-3 thienyl), 7.93 and 8.10
(AA'XX', 2 x apparent d, J = 8.4, 4H, H-phenylene), 8.80 (d, J =
4.8, 2H, ꢁꢂꢃ on porphine), 9.00-9.08 (m, 6H, ꢁꢂꢃ on porphine).
FAB-MS: 759.5 (calc. avg. mass for C38H23IN4S3: 758.71).
[5-(4-Iodophenyl)-10,15,20-tris(thien-2-yl)porphinato(2-)]-
zinc (7d). To a soln. of 11.4 mg of a mixture made up 7c (6.8
1
white solid. Mp 112-113°C. H NMR (360.14 MHz) ꢀ 5.75 (s,
1H, meso-H), 6.04 (m, 2H, H-3 pyrrole), 6.16 (dd, J = 6.1, 2.8,
2H, H-4 pyrrole), 6.70 (m, 2H, H-5 pyrrole), 6.89 (m, 1H, H-3'),
6.95 (dd, J = 5.0, 3.7, 1H, H-4'), 7.21 (dd, J = 5.0, 1.2, 1H, H-5'),
7.98 (s, 2H, NH). 13C NMR (50.30 MHz) ꢀ 39.1, 107.0, 108.5,
117.4, 124.6, 125.5, 126.7, 131.9, 145.6. Anal. Calcd for
C13H12N2S (228.31): C, 68.39; H, 5.30; N, 12.27. Found: C,
68.68; H, 5.01; N, 12.01. EI-MS: 228 (M+, 100 %), 173 (49 %).
N-[4-[10,15,20-Tris(thien-2-yl)-porphin-5-yl]phenyl]-
acetamide (7a). A soln. of 6 (80.2 mg, 0.35 mmol) and 4-
acetamidobenzaldehyde (57.6 mg, 0.35 mmol) in 35 mL CHCl3
was purged with argon for 30 min, then BF3.O(Et)2 (14.9 mL,
0.12 mmol) was added. The solution was stirred for 1 h at 20°C
then DDQ (60.8 mg, 0.27 mmol) was added. The mixture was
stirred at 20°C for an additional 1 h and then 0.5 mL Et3N were
added. The solvent was evaporated and the residue was purified
by CC (CH2Cl2/AcOEt 9:1) to yield 8.7 mg (7%) of 7a. UV/VIS
(CH2Cl2) 308 (4.22), 424 (5.43), 522 (4.18), 560 (3.98), 596
1
mg, 9.0 mmol; determined by H-NMR) and the corresponding
1
deiodinated compound (4.6 mg; determined by H-NMR) in 1.6
mL of CHCl3/MeOH (9:1), zinc acetate monohydrate (90 mg,
0.45 mmol) was added and the mixture was refluxed for 1 h.
Thereafter, the solvent was removed and the residue was
purified by CC (CHCl3/hexane 3:2) to yield 11.6 mg of a
1
mixture of 7d (6.9 mg, 94%; determined by H-NMR) and the
corresponding deiodinated compound (4.7 mg; determined by
1H-NMR). A small amount of pure 7c was used to provide pure
7d for analysis. UV/VIS (CH2Cl2) 312 (3.92), 352 (3.84), 424
1
(5.54), 554 (4.24), 590 (3.68), 596 (3.70). H NMR (360.14
MHz) ꢀ 7.49 (dd, J = 5.1, 3.3, 3H, H-4 thienyl), 7.83 (m, 3H, H-
5 thienyl), 7.89 (m, 3H, H-3 thienyl), 7.92 and 8.08 (AA'XX', 2
x apparent d, J = 8.1, 4H, H-phenylene), 8.87 and 9.10 (2 x d, J
= 4.1, 4H, ꢁꢂꢃ on porphine), 9.11 (s, 4H, ꢁꢂꢃ on porphine).
FAB-MS: 822.3 (calc. avg. mass for C38H21IN4S3Zn: 822.08).
1
(3.86). H NMR (360.14 MHz) ꢀ -2.67 (s, 2H, NH porphine),
2.37 (s, 3H, CH3), 7.50 (dd, J = 5.5, 3.5, 2H, H-4 thienyl), 7.51
(dd, J = 5.2, 3.7, 1H, H-4 thienyl), 7.85 (m, 3H, H-5 thienyl),
7.89 and 8.15 (AA'XX', 2 x apparent d, J = 8.5, 4H, H-
phenylene), 7.91 (m, 3H, H-3 thienyl), 8.92 (d, J = 4.8, 2H, ꢁꢂꢃ
on porphine), 9.00-9.08 (m, 7H, ꢁꢂꢃ on porphine and NHAc).
FAB-MS: 690.3 (calc. avg. mass for C40H27N5OS3: 689.87).
4-[10,15,20-Tris(thien-2-yl)-porphin-5-yl]benzenamine (7b).
A suspension of 7a (28.3 mg, 41.0 mmol) was refluxed for 5 h
in 20% HCl (16 mL). The solution was cooled and neutralized
by adding 10% KOH solution. The neutralized solution was
extracted 3 times with CHCl3. The combined organic layers
were dried (MgSO4), the solvent evaporated and the residue was
purified by CC (CHCl3) to yield 17.2 mg (65%) of 7b. UV/VIS
(CH2Cl2) 308 (4.18), 426 (5.44), 524 (4.16), 560 (3.98), 592
Acknowledgments. This work was supported in part by the
Swiss National Science Foundation. NMR spectra were recorded
on a Bruker Avance DRX 500 instrument by F. Fehr; mass
spectra were recorded by F. Nydegger and I. Müller.
REFERENCES
[1] (a) Alivisatos, A. P.; Barbara, P. F.; Castleman, A. W.;
Chang, J.; Dixon, D. A.; Klein, M. L.; McLendon, G. L.; Miller, J. S.;
Ratner, M. A.; Rossky, P. J.; Stupp, S. I.; Thompson, M. E. Adv. Mater.
1998, 10, 1297. (b) Aviram, A.; Ratner, M. Ann. N.Y. Acad. Sci. 1998,
852, 1. (c) Lehn, J.-M. Angew. Chem. Int. Ed. Engl. 1990, 29, 1304. (d)
Stang, P. J.; Olenyuk, B. Acc. Chem. Res. 1997, 30, 502. (e) Lindsey, J.
S. New J. Chem. 1991, 15, 153. (f) Fujita, M. Structure and Bonding
(Springer, New York), ed. 2000. (g) Reed, M. A. MRS Bull. 2001, 26,
113.
[2] See for example (a) Reimers, J. R.; Lü, T. X.; Crossley, M.
J.; Hush, N. S. Nanotechnology 1996, 7, 424. (b) Kuciaukas, D.; Liddell
P. A.; Moore, A. L.; Moore, T. A., Gust, D. J. Am. Chem. Soc. 1998,
120, 10880. (c) Nalwa, H. S. Adv. Mater. 1993, 5, 341. (d) Balakumar,
A.; Lysenko, A. B.; Carcel, C.; Malinovskii, V. L.; Gryko, D. T. ;
Schweikart, K.-H.; Loewe, R. S.; Yasseri, A. A.; Liu, Z.; Bocian, D. F.;
Lindsey, J. S. J. Org. Chem. 2004, 69, 1435. (e) Wei, L.; Padmaja, K.;
Youngblood, W. J.; Lysenko, A. B.; Lindsey, J. S.; Bocian, D. F. J. Org.
Chem. 2004, 69, 1461. (f) Konishi, K.; Kimata, S.; Yoshida, K.; Tanaka,
M.; Aida, T. Angew. Chem. Int. Ed. Engl. 1996, 35, 2823. (g) Mines, G.
A.; Tzeng, B.-C.; Stevenson, K. J.; Li, J.; Hupp, J. T. Angew. Chem. Int.
Ed. Engl. 2002, 41, 154. (h) Mortimer, R. J. Chem. Soc. Rev. 1997, 26,
147.
1
(3.77), 598 (3.77). H NMR (360.14 MHz) ꢀ -2.64 (s, 2H, NH),
4.05 (s, 2H, NH2), 7.07 and 7.98 (AA'XX', 2 x apparent d, J =
8.5, 4H, H-phenylene), 7.50 (dd, J = 5.3, 3.5, 3H, H-4 thienyl),
7.85 (dd, J = 5.3, 1.1, 3H, H-5 thienyl), 7.92 (dd, J = 3.5, 1.1,
3H, H-3 thienyl), 8.92 (d, J = 4.4, 2H, ꢁꢂꢃ on porphine), 9.00-
9.05 (m, 6H, ꢁꢂꢃ on porphine). FAB-MS: 648.3 (calc. avg.
mass for C38H25N5S3: 647.83).
5-(4-Iodophenyl)-10,15,20-tris(thien-2-yl)porphine (7c). To
a solution cooled to 0-5°C of 7b (11.8 mg, 18.2 mmol) in 4 mL
CHCl3/CH3COOH (2:5) were added dropwise with stirring 27.4
mL (0.20 mmol) isoamylnitrite in 0.19 mL CHCl3. After 15 min,
a solution of 77 mg (0.464 mmol) KI in 0.15 mL water was
added at once. The mixture was allowed to warm up to 20°C and
then was heated to 45°C for 30 min. It was cooled, diluted with
water and extracted with CHCl3. The combined organic layers
were washed with saturated Na2CO3 solution and saturated aq.
Na2S2O3 and dried over MgSO4. After removal of solvent, the
[3] Burrell, A. K.; Officer, D. L.; Plieger, P. G.; Reid, D. C. W.
Chem. Rev. 2001, 101, 2751.

1076
C. A. Papamicaël, O. Mongin, A. Gossauer
Vol 43
[4] See for example (a) Postlethwaite, T. A.; Hutchison, J. E.;
Yao, Y.; Jagessar, R. C.; Dirk, S. M.; Price, D. W.; Reed, M. A.; Zhou,
C.-W.; Chen, J.; Wang, W.; Campbell, I. Chem. Eur. J. 2001, 7, 5118.
(f) Gryko, D.; Li, J.; Diers, J. R.; Roth, K. M.; Bocian, D. F.; Kuhr, W.
G.; Lindsey, J. S. J. Mater. Chem. 2001, 11, 1162. (g) Schweikart, K.-
H.; Malinovskii, V. L.; Diers, J. R.; Yasseri, A. A.; Bocian, D. F.; Kuhr,
W. G.; Lindsey, J. S. J. Mater. Chem. 2002, 12, 808.
Hathcock, K. W.; Murray, R. W. Langmuir 1995, 11, 4109. (b) Kondo,
T.; Ito, T.; Nomura, S.; Uosaki, K. Thin Solid Films 1996, 284-285, 652.
(c) Shimazu, K.; Takechi, M.; Fujii, H.; Suzuki, M.; Saiki, H.;
Yoshimura, T.; Uosaki, K. Thin Solid Films 1996, 273, 250. (d) Yuan,
H.; Woo, L. K. J. Porphyrins Phthalocyanines 1997, 1, 189. (e) Wen, L.;
Li, M.; Schlenoff, J. B. J. Am. Chem. Soc. 1997, 119, 7726. (f) Uosaki,
K.; Kondo, T.; Zhang, X.-Q.; Yanagida, M. J. Am. Chem. Soc. 1997,
119, 8367. (g) Hutchison, J. E.; Postlethwaite, T. A.; Chen, C.-H.;
Hathcock, K. W.; Ingram, R. S.; Ou, W.; Linton, R. W.; Murray, R. W.;
Tyvoll, D. A.; Chng, L. L.; Collman, J. P. Langmuir 1997, 13, 2143. (h)
Yanagida, M.; Kanai, T.; Zhang, X.-Q.; Kondo, T.; Uosaki, K. Bull.
Chem. Soc. Jpn. 1998, 71, 2555. (i) Kondo, T.; Kanai, T.; Iso-o, K.;
Uosaki, K. Z. Phys. Chem. 1999, 212, 23. (j) Boeckl, M. S.; Bramblett,
A. L.; Hauch, K. D.; Sasaki, T.; Ratner, B. D.; Rogers, J. W., Jr.
Langmuir 2000, 16, 5644. (k) Abdelrazzaq, F. B.; Kwong, R. C.;
Thompson, M. E. J. Am. Chem. Soc. 2002, 124, 4769.
[5] (a) Guo, L.-H.; McLendon, G.; Razafitrimo, H.; Gao, Y. J.
Mater. Chem. 1996, 6, 369. (b) Nishimura, N.; Ooi, M.; Shimazu, K.;
Fujii, H.; Uosaki, K. J. Electroanal. Chem. 1999, 473, 75.
[6] Gryko, D. T.; Clausen, C.; Lindsey, J. S. J. Org. Chem. 1999,
64, 8635.
[7] See for example (a) Kuroda, Y.; Hiroshige, T.; Sera, T.;
Shiroiwa, Y.; Tanaka, H.; Ogoshi, H. J. Am. Chem. Soc. 1989, 111,
1912. (b) Jagessar, R. C.; Tour, J. M. Org. Lett. 2000, 2, 111. (c) Gryko,
D. T.; Zhao, F.; Yasseri, A. A.; Roth, K. M.; Bocian, D. F.; Kuhr, W. G.;
Lindsey, J. S. J. Org. Chem. 2000, 65, 7356. (d) Li, J.; Gryko, D.;
Dabke, R. B.; Diers, J. R.; Bocian, D. F.; Kuhr, W. G.; Lindsey, J. S. J.
Org. Chem. 2000, 65, 7379. (e) Tour, J. M.; Rawlett, A. M.; Kozaki, M.;
[8] Gryko, D. T.; Clausen, C.; Roth, K. M.; Dontha, N.; Bocian,
D. F.; Kuhr, W. G.; Lindsey, J. S. J. Org. Chem. 2000, 65, 7345.
[9] Clausen, C.; Gryko, D. T.; Dabke, R. B.; Dontha, N.; Bocian,
D. F.; Kuhr, W. G.; Lindsey, J. S. J. Org. Chem. 2000, 65, 7363.
[10] Clausen, C.; Gryko, D. T.; Yasseri, A. A.; Diers, J. R.;
Bocian, D. F.; Kuhr, W. G.; Lindsey, J. S. J. Org. Chem. 2000, 65, 7371.
[11] See for example (a) Ishida, A.; Majima, T. Chem. Commun.
1999 1299. (b) Redman, J. E.; Sanders, J. K. M. Org. Lett. 2000, 2,
4141. (c) Imahori, H.; Norieda, H.; Nishimura, Y.; Yamazaki, I.;
Higuchi, K.; Kato, N.; Motohiro, T.; Yamada, H.; Tamaki, K.; Arimura,
M.; Sakata, Y. J. Phys. Chem. B 2000, 104, 1253. (d) Imahori, H.;
Hasobe, T.; Yamada, H.; Nishimura, Y.; Yamazaki, I.; Fukuzumi, S.
Langmuir 2001, 17, 4925. (e) Paolesse, R.; Monti, D.; La Monica, L.;
Venanzi, M.; Froiio, A.; Nardis, S.; Di Natale, C.; Martinelli, E.;
D'Amico, A. Chem. Eur. J. 2002, 8, 2476.
[12] Mongin, O.; Papamicaël, C.; Hoyler, N.; Gossauer, A. J. Org.
Chem. 1998, 63, 5568.
[13] Tarbell, D.S.; Fukushima, D.K. Org. Synth; Wiley: New
York, 1955; Collect. Vol. 3, p 809.
[14] Behforouz, M.; Kerwood, J. E. J. Org. Chem. 1969, 34, 51.
[15] Lee, C.-H; Lindsey, J.S. Tetrahedron 1994, 50, 11427.
[16] Littler, B. J.; Ciringh, Y.; Lindsey, J. S. J. Org. Chem. 1999,
64, 2864.