Synthesis of trans-A2B2-porphyrins bearing phenylethynyl substituents

Article abstract of DOI:10.1021/jo1025578

Efficient and convenient conditions for the preparation of trans-A ₂B₂-porphyrins bearing two phenylethynyl moieties directly from phenylpropargyl aldehydes and dipyrromethanes of diversified lipophilicity and reactivity have been de

Full text of DOI:10.1021/jo1025578

ARTICLE
pubs.acs.org/joc
Synthesis of trans-A2B2-Porphyrins Bearing Phenylethynyl
Substituents
Agnieszka Nowak-Krꢀol,† Beata Koszarna,† Su Yeon Yoo,‡ Jan Chromiꢀnski,† Marek K. We-czawski,†
Chang-Hee Lee,‡ and Daniel T. Gryko*,†
†Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
‡Department of Chemistry, Kangwon National University, Chun-Cheon 200-701, Korea
S Supporting Information
b
ABSTRACT: Efficient and convenient conditions for the pre-
paration of trans-A2B2-porphyrins bearing two phenylethynyl
moieties directly from phenylpropargyl aldehydes and dipyrro-
methanes of diversified lipophilicity and reactivity have been
developed. This new procedure allows the preparation of a library
of porphyrins of this architecture with a wide range of substitu-
ents. Thanks to the identification of the reagent solubility as one
of the key factors influencing the yield of the porphyrinogens, we
were able to improve yields to ca. 30%. The scope and limitations of two sets of conditions have been explored. The methodological
advantage of this approach is its straightforward access to building blocks and the formation of the porphyrin core in the last step
without the need for deprotection of the triple bond or bromination and consecutive coupling reaction, which often demands
copper salts to proceed smoothly, especially with electron-deficient alkyne partners. Therefore, it prevents undesired copper
porphyrin formation, as well as the need for utilizing expensive alkynes. A two-step method for the preparation of phenylpropargyl
aldehydes has also been refined.
’ INTRODUCTION
phenylpropargyl aldehydes is the least explored. To the best of our
knowledge, there are only a few publications reporting this route. The
first report presented the reaction of propargyl aldehydes with
dipyrromethanes prepared from phenylpropargyl aldehyde.12 There
are also some interesting reports regarding the synthesis of trans-
A2B2-porphyrins from trimethylsilylpropynal7,11,13 and triisopropyl-
silylpropynal,13 but the reaction outcomes were very sensitive to the
applied conditions and the target porphyrins were usually accom-
panied by undesired rearrangement products (scrambling). In an-
other case, the reaction of triisopropylsilylpropynal with a bulky
dipyrromethane unexpectedly furnished [1.0.1.0.1.0]hexaphyrin,
which significantly exceeded the amount of the target porphyrin.14
When triisopropylsilylpropynal was replaced with phenylpropynal,
the modified reaction conditions then suppressed the acid-catalyzed
rearrangement process.13
Milgrom first reported the synthesis of A4-porphyrins bearing four
ethynyl linkages via direct condensation of substituted phenylpro-
pargyl aldehydes with pyrrole, affording the final porphyrins in
moderate yields.1b Higher yields (20ꢀ27%) were achieved when
TIPS-propynal and 4-n-butylphenylpropynal were used as
substrates.5b,13 For other silyl-protected propynals, yields were rather
moderate,7,13 perhaps reflecting the occurrence of conjugate addition
rather than attack at the carbonyl group. The elegant solution
developed by Milgrom15 was based on temporary masking of the
meso-Arylethynylporphyrins have received considerable atten-
tion in the field of materials chemistry due to their potential
application in optoelectronic devices.1 They have emerged as
promising candidates for optical limiters,2ꢀ4 two-photon absorp-
tion (2PA) sensitizers for near-infrared (NIR) photorefractive
composites,2 reverse saturable absorbers,5 materials for second-
harmonic generation,1g and dye-sensitized solar cells (DSSCs).6
Arylethynylporphyrins have a significantly altered electronic
structure. Incorporation of two ethynyl moieties elongates the
π-conjugation pathway and improves the communication/elec-
tronic interactions between the phenyl substituents and the
porphyrin core owing to the rigid two-dimensional structures,
which results in enhancement of 2PA values2 and bathochroma-
tically shifted absorption.1b,3,7 They also display large first-order
hyperpolarizabilities1g,8 and high thermal stability.1g
Several methods have been employed for the preparation of meso-
arylethynyl trans-A2B2-porphyrins. Typically they are synthesized via
preparation of trans-A2-porphyrins unsubstituted at two meso-posi-
tions, followed by bromination and Sonogashira coupling.1g,2,5a,9 This
route was intensively explored by Anderson and co-workers.10 An
alternative route starts with the reaction of silyl-protected propargyl
aldehydes with dipyrromethanes, followed by deprotection and
Sonogashira coupling with various halogenoarenes.11 These two
methods are versatile, usually offer overall high yields, and have been
employed to construct complex porphyrin structures. The third
possible approach to such trans-A2B2-porphyrins starting from
Received: December 23, 2010
Published: March 16, 2011
r
2011 American Chemical Society
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Scheme 1. Synthesis of Phenylpropargyl Aldehydes
Scheme 2. Synthesis of Trialkylated Dipyrromethanes 15
and 16
Scheme 3. Synthesis of 5-(4-Octadecyloxyphe-
nyl)dipyrromethane (18)
triple bond by dicobalt octacarbonyl. This method improved the
yields to 35%. Satisfactory yields of the desired A4-porphyrins were
also obtained in the reactions between 3,4-diethylpyrrole or isoindole
derivatives and phenylpropargyl aldehyde.16
Although all the existing methodologies serve the synthetic
community rather well, further development is still necessary. In
this regard, the pathway based on direct condensation of
dipyrromethanes and aldehydes has great potential in arylethy-
nylporphyrins synthesis. Diminishing the occurrence of scram-
bling and of the Michael addition are obvious challenges in this
regard. Thus, we were prompted to elaborate an efficient,
nonscrambling, and straightforward route to porphyrins of the
title architecture utilizing a [2 þ 2] condensation approach.
literature consists of two steps, which involve efficient Sonogashira
coupling of propargyl alcohol with aryl iodides or bromides, followed
by oxidation of the resulting phenylpropargyl alcohols to the
corresponding aldehydes. The Sonogashira coupling of aryl iodides
1ꢀ3 was carried out under general and efficient conditions, affording
alcohols 5ꢀ7 in 55ꢀ95% yields (Scheme 1). Subsequently, the
propargyl alcohols were submitted to the oxidation reaction. Numer-
ous conditions have been developed for the selective oxidation of
primary alcohols to aldehydes, and we applied some of them to the
preparation of phenylpropargyl aldehydes. Most of these methods,
however, including those which utilized PCC17 and TiCl4,18 did not
provide satisfactory results (PCC) or afforded only traces of the
desired products (PCC and TiCl4). The only successful exception
was the procedure employing DessꢀMartin periodinate19 as a mild
and effective oxidizing agent. In this particular case, we obtained high
yields of over 80% for aldehydes 8ꢀ10. Unfortunately, this reagent is
’ RESULTS AND DISCUSSION
Preparation of Building Blocks. Since the aim of our investiga-
tion was to develop broadly applicable conditions for the preparation
of meso-arylethynyl porphyrins, we designed three substituted deri-
vatives 8ꢀ10 (Scheme 1) in addition to the parent phenylpropynal.
Two of the phenylpropargyl aldehydes possessed electron-withdraw-
ing substituents (CN, NO2), while the third one contained an
electron-donating substituent (OMe). As counterparts, we planned
to use a diverse set of aryldipyrromethanes.
At the beginning of our survey, we faced a problem with the
propynal synthesis. The most versatile pathway reported in the
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Table 1. The Synthesis of trans-A2B2-Porphyrins from Arylpropynals and Aryldipyrromethanes
a Method A: (1) aldehyde (0.01 M), dipyrromethane (0.01 M), BF3 Et2O (0.001 M), NH4Cl (0.1 M), MeCN, 0 °C, 4.5 h; (2) DDQ (0.02 mmol), rt, 1
3
h. b Method B: (1) aldehyde (0.01 M), dipyrromethane (0.01 M), BF3 Et2O (0.002 M), toluene, rt, 3 h; (2) DDQ (0.02 mmol), rt, 1 h. c The time of first
3
step was prolonged to 16.5 h. d BF3 Et2O (0.004 M) and the time of the first step was prolonged to 22 h.
3
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not only very expensive but also difficult to handle due to its low
stability upon exposure to air. Therefore, we sought alternative
methods that would be easier to handle and would minimize the
cost of the synthesis. We tested various conditions, including
2-iodoxybenzoic acid (IBX) in DMSO, IBX in DCM, [bis(acetoxy)-
iodo]benzene (BAIB) with 2,2,6,6-tetramethylpiperidine 1-oxyl
(TEMPO),20 MnO2,21 and [bis(trifluoroacetoxy)iodo]benzene
(PIFA) with TEMPO. All the methods afforded good to high yields
of aldehydes 8ꢀ10. In the selection of the oxidizing agent for
preparative scale, we took into consideration various factors, such
as stability, availability, and price of the oxidizing agent, as well as the
time and the yield of the reaction. Finally, we decided on the clean and
efficient method utilizing BAIB and TEMPO, which afforded
aldehydes in very high yields ranging from 81% to 95% on ca. 18
mmol scale (Scheme 1).
Table 2. Optimization of the Reaction of (4-Cyanophenyl)-
propynal (8) with 5-(4-Octadecyloxyphenyl)dipyrromethane
(18)a
concn (M)
entry BF3 Et2O Ph4BNH4 Temp. (°C) yield of porphyrin 27b (%)
3
1
2
3
4
0.001
0.001
0.002
0.002
0.1
0.1
0.1
0
0
20
20
20
6
6
12c
14c
a All reactions were performed under the following constant conditions:
[aldehyde 8] = 0.01 M, [dipyrromethane 18] = 0.01 M, 3 h. b Isolated
yields. c Minimal scrambling was observed.
For the purpose of this study, we also synthesized a set of
dipyrromethanes 15, 16, 18ꢀ20. The ester-functionalized ben-
zaldehyde 13 was obtained in the reaction of 3,4,5-trihydroxy-
benzaldehyde (12) with tert-butyl chloroacetate, while related
aldehyde 14 was prepared from 12 by a classical alkylation
procedure (Scheme 2).22
Both unknown dipyrromethanes 15 and 16 (Scheme 2), as
well as dipyrromethane 18 (Scheme 3), were prepared using
Lindsey’s general conditions.23
Synthesis of trans-A2B2-Porphyrin with Two Arylethynyl
Moieties. Having in hand all necessary building blocks, we focused
on the porphyrin-formation step. There are numerous methods for
the preparation of trans-A2B2 porphyrins, but the vast majority of
them apply to the sterically hindered dipyrromethanes,24,25 which
are less prone to acid-catalyzed scrambling. As a model system for
optimization studies we chose the reaction of aldehyde 8 with
dipyrromethane 15 leading to porphyrin 21 (Table 1). In the first
phase of searching for suitable conditions, we observed that all the
methods employing trifluoroacetic acid as a catalyst led to such
extensive scrambling that in some cases the amount of rearrange-
ment products exceeded the amount of target porphyrins.
Searching for a suitable alternative, we took advantage of the
to develop a more versatile methodology, we searched for alternative
conditions that were suitable for these types of substrates. Initially,
we changed the solvent as well as the salt, replacing polar MeCN
with nonpolar toluene and NH4Cl with polar but more lipophilic
Ph4BNH4. We carried out the reaction of aldehyde 8 with dipyrro-
methane 18 at 0 °C for 3 h in dry and degassed toluene (entry 1,
Table 2), followed by oxidation. These conditions resulted in a low
(6%) yield of 27, but the reaction was very clean and no scrambling
was observed. Further variations in the concentration of the acid, the
presence of Ph4BNH4, and the temperature (see Table 2) led to
optimization of these conditions.
Ultimately, we had to compromise between the yield and the
formation of troublesome side products. Taking into account the
time required for the preparation of some building blocks and the
overall cost of their synthesis, as well as the price of borate salt, we
decided on the method employing a higher concentration of acid,
without an addition of salt, which provided high amounts of the
final compounds, but with minimal scrambling.
From our study of the model condensation, we identified the
following reaction conditions: (1) aldehyde (0.01 M), dipyrro-
methane (0.01 M) in dry toluene predegassed (Ar, 35 min,
sonicator), BF3 Et2O (0.002 M), rt, 3 h; (2) DDQ (0.02 mmol),
3
known procedure (BF3 Et2O, NH4Cl, MeCN, 0 °C, 4.5 h)
3
rt, 1 h. The conditions optimized for lipophilic dipyrromethanes were
subsequently applied to the preparation of porphyrins 29 and 30 from
dipyrromethane 16 possessing three alkoxy groups and aldehydes 8
and 10 with satisfactory yields of 12% in each case (Table 1).
We also investigated whether the conditions optimized for the
reaction between 5-(4-octadecyloxyphenyl)dipyrromethane (18)
and 3-(4-cyanophenyl)propynal (8) could be applied to other
building blocks. The system of our first choice was quite demanding
and involved 5-[3,4,5-tris((tert-butoxycarbonyl)methyloxy)phe-
nyl]dipyrromethane (15) and moderately reactive 3-phenylpropy-
nal (11). The reaction in toluene afforded the corresponding
porphyrin 23 in 5% yield (Table 1). These results were in line with
our expectations, since for quite hydrophilic dipyrromethane the
polar MeCN method seemed to be preferable. Subsequently, to
compare the influence of reactivity and lipophilicity of dipyrro-
methanes on the reaction course, we performed the reaction
between other aldehydes and dipyrromethanes (Table 1).
developed by Lindsey and co-workers for unhindered
dipyrromethanes25 and slightly modified it. We have noted that a
prolonged time of degassing the solvent with a stream of argon by
sonication significantly raised the yield of the porphyrin 22.
Additionally, we wanted to avoid residual chlorin, so instead of a
two-step oxidation (as originally proposed by authors), we doubled
the amount of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). In
contrast to the report of Lindsey and co-workers, the increased
amount of oxidant used to our specific case was sufficient to ensure
complete oxidation of chlorin to porphyrin, which can be rationa-
lized by lower steric hindrance and lower oxidation potential. The
modified procedure was subsequently applied to a series of dipyr-
romethanes (both hindered and unhindered) and phenylpropargyl
aldehydes 8ꢀ11, affording trans-A2B2 porphyrins 21ꢀ26 and 29 in
satisfactory yields reaching 30% in some cases (Table 1).
The biggest drawback of this method was performing the reaction
in MeCN, a polar solvent that is inappropriate for more lipophilic
building blocks, e.g., those possessing long alkyl chains like 5-(4-
octadecyloxyphenyl)dipyrromethane (18). With this substrate,
reactions with both 3-(4-cyanophenyl)propynal (8) and 3-phenyl-
propynal (11) gave no porphyrin. The predominant products after
addition of DDQ were dipyrrines. This outcome could be explained
by low solubility of the lipophilic substrate and intermediates formed
during the course of the reaction in this reaction medium. Desiring
’ CONCLUSIONS
We have performed a detailed study of the direct [2 þ 2]
condensation of phenylpropargyl aldehydes with dipyrro-
methanes leading to trans-A2B2-porphyrins, and we have defined
two sets of conditions that apply to reagents with greater or lesser
lipophilicity. By identifying the issue of solubility of the substrates and
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the intermediates in the reaction medium and by tailoring reaction
conditions accordingly, we have achieved reasonable yields of a broad
range of porphyrins. The most notable findings are as follows: (1)
For less lipophilic reagents, the modified procedure in MeCN
reported initially by Lindsey and co-workers is superior. We noticed
that a prolonged time of degassing the solvent by sonication plays a
crucial role and substantially increases the yield of the porphyrin
formation. The reaction in MeCN does not work for highly lipophilic
dipyrromethanes, probably due to the low solubility of substrates and
intermediates formed during the course of the reaction. (2) For more
lipophilic reagents, another set of conditions in toluene with no or
minimal scrambling has been developed, providing satisfactory yields
for reactive lipophilic dipyrromethanes and electron-deficient alde-
hydes. Addition of the lipophilic salt Ph4BNH4 limits the scrambling
to some extent, probably due to decreasing the activation energies of
the desired reactions through lowering the energies of the polar
transition states. Decreasing the reaction temperature also reduced
the amount of ring-rearrangement products, but it also lowers the
yields significantly due to the extremely slow reaction rate.
These results are not only of theoretical significance in that
they provide new insights into factors influencing the course of
reactions of pyrrole derivatives with aldehydes leading to macro-
cyclic structures, but they also provide a complementary method
to two established alternative approaches leading to this type of
π-expanded porphyrins. The current methodology compares
favorably with the existing procedures, especially for electron-
deficient arylethynyl substituents where Sonogashira coupling of
meso-Br-porphyrins with alkynes leads to inferior results.
stirred solution of propargyl alcohol (2.9 mL, 0.05 mol), 1-iodo-4-
methoxybenzene (11.47 g, 49 mmol), piperidine (9.88 mL, 0.1 mol),
and copper(I) iodide (30 mg, 0.16 mmol) in dry toluene (100 mL)
under an argon atmosphere. The mixture was stirred at 35 °C for 24 h
and then filtered through silica gel (silica, hexanes/CH2Cl2 2:3 then
CH2Cl2). The solvent was distilled off and the residue was crystallized
(AcOEt/hexanes) to afford pure product (4.37 g, 55%): mp =
63.1ꢀ63.5 °C (AcOEt/hexanes) (lit.17 mp = 62.5ꢀ64.5 °C);
1H NMR (500 MHz, CDCl3) δ 1.77 (br s, 1H), 3.81 (s, 3H), 4.48
(s, 2H), 6.84 (m, 2H), 7.37 (m, 2H). Other spectral and physical
properties concur with published data.17
3-(4-Nitrophenyl)prop-2-yn-1-ol (7). Bis(triphenylphosphine)palla-
dium(II) dichloride (120 mg, 0.171 mmol) was added to a stirred solution of
propargyl alcohol (5.77 mL, 0.1 mol), 1-iodo-4-nitrobenzene (24.5 g, 98
mmol), piperidine (19.76 mL, 0.2 mol), and copper(I) iodide (60 mg, 0.32
mmol) in dry toluene (100 mL) under an argon atmosphere. The mixture
was stirred at 35 °C for 2 h and then filtered through silica gel. The solvent was
distilled off and the residue was chromatographed (silica, toluene/CH2Cl2
1:1) followed by crystallization (CHCl3) to afford pure solid (5.5 g). The
filtrate containing the contaminated product was rechromatographed (silica,
CH2Cl2) and crystallized, yielding an additional 7.1 g of the pure compound 7
(12.6 g, total yield, 73%): mp = 98.7ꢀ99.9 °C (CHCl3) (lit.26 mp =
97ꢀ98 °C); 1H NMR (500 MHz, CDCl3) δ 1.84 (br s, 1H), 4.55 (s, 2H),
7.58 (m, 2H), 8.19 (m, 2H). Other spectral and physical properties concur
with published data.26
General Procedure for the Oxidation of Propargyl Alco-
hols to Propargyl Aldehydes. To the solution of TEMPO (269 mg,
1.7 mmol) and alcohol (17.6 mmol) in DCM (17.7 mL) was added
bisacetoxyiodobenzene (6.28 g, 19.5 mmol). The reaction mixture was
stirred for 1.5 h. Then the organic layer was washed with aqueous
solution of Na2S2O3. The water layer was extracted with methylene
chloride, and then combined organic extracts were washed with aqueous
solution of NaHCO3 to pH 7, dried (Na2SO4), filtered, and evaporated.
Further purification details are described for each case as follows.
(4-Cyanophenyl)propynal (8). The crude product was chroma-
tographed (silica, hexanes/CH2Cl2 3:2) followed by crystallization
(CH2Cl2/hexanes) to afford pure aldehyde 8 as colorless crystals. The
filtrate was rechromatographed (silica, hexanes/CH2Cl2 3:2) and crys-
tallized, providing additional portion of pure product 8 (2.31 g, total
yield 84%): mp = 100.9ꢀ101.7 °C (CH2Cl2/hexane); 1H NMR (500
MHz, CDCl3) δ 7.70 (m, 4H), 9.45 (s, 1H); 13C NMR (125 MHz,
CDCl3) δ 90.3, 91.2, 114.6, 117.7, 124.2, 132.3, 133.4, 176.1; HR MS
(EI) calcd for C10H5NO 155.0371, found 155.0374. Anal. Calcd for
C10H5NO: C, 77.41; H, 3.25; N, 9.03. Found: C, 77.17; H, 3.23; N, 9.12.
(4-Methoxyphenyl)propynal (9). The crude product was chro-
matographed (silica, hexanes/CH2Cl2 3:2) followed by crystallization
(CH2Cl2/hexanes) to afford pure aldehyde 9 as colorless crystals
(2.69 g, 95%): mp = 45.4ꢀ45.8 °C (CH2Cl2/hexane) (lit.17 mp =
47ꢀ48.5 °C); 1H NMR (500 MHz, CDCl3) δ 3.85 (s, 3H), 6.91 (m,
2H), 7.56 (m, 2H), 9.40 (s, 1H). Other spectral and physical properties
concur with published data.17
’ EXPERIMENTAL SECTION
All chemicals were used as received unless otherwise noted. Reagent
grade solvents (CH2Cl2, hexanes) were distilled prior to use. All
1
reported H NMR and 13C NMR spectra were collected using 600,
500, 400, or 200 MHz spectrometers. Chemical shifts (δ ppm) were
determined with TMS as the internal reference or acetone as the external
reference; J values are given in Hz. The UV/vis absorption spectra were
recorded in CH2Cl2 or TFA. The absorption wavelengths are reported
in nm with the extinction coefficient in Mꢀ1 cmꢀ1 in brackets. Melting
points of aldehydes were determined using a capillary type apparatus or a
Boetius-type apparatus. Chromatography was performed on silica
(230ꢀ400 mesh) or neutral alumina (activity I). Dry column vacuum
chromatography (DCVC) was performed on preparative thin-layer
chromatography silica. Preparative scale size exclusion chromatography
(SEC) was carried out using BioRad Bio-Beads SX-1 with THF as an
eluent. The mass spectra were obtained via field desorption MS (FD-
MS), electrospray ionization (ESI-MS), and electron impact MS (EI-
MS). Aldehydes 14 and 17 and dipyrromethanes 19 and 20 were
prepared according to the literature procedures.21,22,25
3-(4-Cyanophenyl)prop-2-yn-1-ol (5). Bis(triphenylphosphine)-
palladium(II) dichloride (60 mg, 0.085 mmol) was added to a stirred
solution of propargyl alcohol (2.89 mL, 0.05 mol), 4-iodobenzonitrile (11.2
g, 49 mmol), piperidine (9.88 mL, 0.1 mol), and copper(I) iodide (30 mg,
0.16 mmol) in dry toluene (100 mL) under an argon atmosphere. The
mixture was stirred at 35 °C for 2 h and then filtered through silica gel. The
solvent was distilled off and the residue was chromatographed (silica,
hexanes/CH2Cl2 1:1 then 2:3) followed by crystallization (AcOEt/
hexanes) to afford pure product (7.43 g, 96%): mp = 85.7ꢀ86.3 °C
(AcOEt/hexanes) (lit.26 mp = 87.5ꢀ88 °C); 1H NMR (500 MHz, CDCl3)
δ 1.88 (br s, 1H), 4.53 (s, 2H), 7.51 (m, 2H), 7.60 (m, 2H). Other spectral
and physical properties concur with published data.26
(4-Nitrophenyl)propynal (10). The crude product was chroma-
tographed (silica, hexanes/CH2Cl2 2:3) and crystallized (CH2Cl2/
hexane) to afford the title compound (2.16 g, 81%) as colorless crystals:
mp = 120.2ꢀ120.7 °C (CH2Cl2/hexane) [lit.27 mp = 123.0ꢀ123.5 °C
(petroleum ether)]; 1H NMR (500 MHz, CDCl3) δ 7.78 (m, 2H), 8.28
(m, 2H), 9.47 (s, 1H). Other spectral and physical properties concur
with published data.27
3,4,5-Tris[(tert-butoxycarbonyl)methyloxy)]benzaldehyde-
(13). 3,4,5-Trihydroxybenzaldehyde (12) (1.50 g, 8.7 mmol) was
dissolved in MeCN (100 mL), and tert-butyl chloroacetate (5 mL,
35 mmol), K2CO3 (3.3 g, 24 mmol) were added, followed by KI (3.32 g,
20 mmol). The reaction mixture was refluxed for 8 h. In the meantime, an
additional portion of K2CO3 (3.0 g, 22 mmol) was added. Then the
3-(4-Methoxyphenyl)prop-2-yn-1-ol (6). Bis(triphenylphosp-
hine)palladium(II) dichloride (60 mg, 0.085 mmol) was added to a
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ARTICLE
mixture was cooled down and filtered. The filtrate was evaporated and
chromatographed (silica, hexanes/CH2Cl2 3:2 to give oil, which slowly
solidified. The solid was recrystallized (hexane/AcOEt) to obtain colorless
crystals (3.83 g, 88%): mp = 76.9ꢀ77.3 °C (hexane/AcOEt); 1H NMR
(500 MHz, CDCl3) δ 1.47 (s, 9H), 1.48 (s, 18H), 4.64 (s, 4H), 4.82 (s,
2H), 7.07 (s, 2H), 9.79 (s, 1H); 13C NMR (125 MHz, CDCl3) δ 28.0,
28.1, 66.9, 69.8, 81.8, 82.6, 109.6, 131.1, 143.2, 151.4, 167.4, 168.0, 190.3;
HR MS (ESI) calcd for C25H36O10Na 519.2201, found 519.2224. Anal.
Calcd for C25H36O10: C, 60.47; H, 7.31. Found: C, 60.43; H, 7.55.
5-[3,4,5-Tris((tert-butoxycarbonyl)methyloxy)phenyl]dipyrr-
omethane (15). The solution of aldehyde 13 (622 mg, 1.25 mmol) and
pyrrole (4.34 mL, 63 mmol) was degassed with a stream of argon for 10 min.
InCl3 (27.8 mg, 0.13 mmol) was added, and the mixture was stirred under
argon at room temperature for 2 h. The pyrrole was recovered and the crude
product obtained upon removal of pyrrole was chromatographed (silica,
CH2Cl2 then CH2Cl2/acetone 50:1). Crystallization from cyclohexane
afforded the title compound (223 mg, 29%): mp = 112.3ꢀ113.4 °C
(cyclohexane); 1H NMR (500 MHz, CDCl3) δ 1.42 (s, 18H), 1.48
(s, 9H), 4.50 (s, 4H), 4.62 (s, 2H), 5.33 (s, 1H), 5.88 (m, 2H), 6.11 (m,
2H), 6.65 (m, 2H), 7.97 (br s, 2H); 13C NMR (125 MHz, CDCl3) δ 28.0,
28.1, 43.8, 66.8, 70.1, 81.4, 82.2, 107.2, 108.4, 108.8, 117.2, 131.8, 136.7,
137.5, 151.3, 167.9, 168.4; HR MS (ESI) calcd for C33H44N2O9Na
635.2939, found 635.2962. Anal. Calcd for C33H44N2O9: C, 64.69; H,
7.24; N, 4.57. Found: C, 64.54; H, 7.15; N, 4.61.
5-(3,4,5-Trisdecyloxyphenyl)dipyrromethane (16). The so-
lution of aldehyde 14 (2.56 g, 4.45 mmol) and pyrrole (16 mL, 231 mmol)
was degassed with a stream of argon for 15 min. InCl3 (130 mg, 0.59 mmol)
wasadded, andthemixture wasstirred under argon at room temperature for
3 h. Then ground NaOH (583 mg, 14.58 mmol) was added, the reaction
mixture was stirred for a further 0.5 h and filtered through a pad of Celite.
The pyrrole was recovered and the crude solid obtained upon removal of
pyrrole was chromatographed (silica, hexanes/CH2Cl2 1:1). Then the solid
was rechromatographed in order to remove N-confused dipyrromethane
(silica, CH2Cl2/AcOEt/hexanes 3:1:16) to afford pure product 16 (2.899 g,
94%): mp = 31.5ꢀ32.6 °C; 1H NMR (200 MHz, CDCl3) δ 0.88 (m, 9H),
1.17ꢀ1.45 (m, 42 H), 1.64ꢀ1.77 (m, 6H), 3.84ꢀ3.96 (m, 6H), 5.38
(s, 1H), 5.96 (m, 2H), 6.16 (m, 2H), 6.40 (s, 2H), 6.70 (m, 2H), 7.92 (br s,
2H); 13C NMR (50 MHz, CDCl3) δ 14.1, 22.7, 26.1, 29.4, 29.4, 29.4, 29.6,
29.7, 29.8, 30.3, 31.9, 44.1, 69.0, 73.4, 106.9, 107.1, 108.4, 117.0, 132.4,
136.9, 137.0, 153.1; HR MS (ESI) calcd for C45H74N2O3Na 713.5592,
found 713.5619. Anal. Calcd for C45H74N2O3: C, 78.21; H, 10.79; N, 4.05.
Found: C, 78.19; H, 10.48; N, 3.89.
suspension was cooled down under Ar to 0 °C, and samples of aldehyde
(0.4 mmol) and dipyrromethane (0.4 mmol) were added, followed by
BF3 Et2O (5 μL, 0.04 mmol). After 4.5 h, DDQ (180 mg, 0.8 mmol) was
3
added, and the reaction mixture was stirred at rt for an additional 1 h. The
purification details are described for each case as follows.
5,15-Bis(4-cyanophenylethynyl)-10,20-bis[tris((tert-butoxy-
carbonyl)methyloxy)phenyl]porphyrin (21).The reaction mixture
was passed through a short pad of alumina (alumina, CH2Cl2), and all
fractions containing porphyrin 21 were combined, evaporated to dryness,
and chromatographed (silica, hexanes/acetone 4:1) to obtain pure por-
phyrin 21 (83.5 mg, 28%) which was crystallized (acetone/hexane),
affording green crystals: Rf = 0.53 (hexane/acetone 1:1); UV/vis
(CH2Cl2) λ (ε) = 446 (433 000), 603 (58 900), 691 (32 700), 293
(19300), 559 (8800), 520 nm (5200); 1H NMR (500 MHz, CDCl3) δ
ꢀ2.08 (s, 2H), 1.39 (s, 36 H), 1.63 (s, 18 H), 4.75 (s, 8H), 5.02 (s, 4H),
7.36 (s, 4H), 7.88 (d, J = 8.2 Hz, 4H), 8.10 (d, J = 8.2 Hz, 4H), 8.91 (d, J =
4.7 Hz, 4H), 9.60 (d, J = 4.7 Hz, 4H); 13C NMR (125 MHz, CDCl3) δ
28.0, 28.3, 66.9, 70.5, 81.7, 82.3, 95.7, 96.1, 100.1, 111.9, 115.4, 118.6, 121.6,
128.5, 132.1, 132.5, 135.9, 138.1, 149.7, 167.7, 168.6; HR MS (ESI) calcd
for C86H88N6O18Na2 769.2970, found 769.2957; isotope profiles match.
5,15-Bis(4-nitrophenylethynyl)-10,20-bis[tris((tert-butoxy-
carbonyl)methyloxy)phenyl]porphyrin (22). The reaction mix-
ture was passed through a short pad of alumina (alumina, CH2Cl2) to
give almost pure product. Subsequent crystallization (CH2Cl2/hexane)
afforded porphyrin 22 (110 mg, 36%) in the form of green crystals: Rf =
0.58 (hexane/acetone 1:1); UV/vis (CH2Cl2) λ (ε) = 453 (405 000),
608 (93 900), 694 nm (68 800); 1H NMR (600 MHz, CDCl3) δ ꢀ2.08
(s, 2H), 1.40 (s, 36H), 1.64 (s, 18H), 4.78 (s, 8H), 5.04 (s, 4H), 7.39 (s,
4H), 8.04 (m, 4H), 8.33 (m, 4H), 8.94 (d, J = 4.6 Hz, 4H), 9.61 (d, J = 4.6
Hz, 4H); 13C NMR (150 MHz, CDCl3) δ 28.0, 28.3, 66.9, 70.5, 81.7,
82.3, 95.6, 97.1, 100.1, 115.4, 121.7, 124.0, 130.4, 132.1, 135.9, 138.1,
147.1, 149.8, 167.7, 168.6; HR MS (ESI) calcd for C84H89N6O22
1533.6025, found 1533.6042; isotope profiles match.
5,15-Bis(phenylethynyl)-10,20-bis[tris((tert-butoxycarbonyl)-
methyloxy)phenyl]porphyrin (23). The reaction mixture was passed
through a short pad of alumina (alumina, CH2Cl2), and all fractions
containing porphyrin 23 were combined, evaporated to dryness, and
chromatographed (silica, CHCl3/MeOH 189:1 to 49:1) to obtain pure
porphyrin 23 (60 mg, 21%) which was crystallized (acetone/hexane),
affording green crystals: Rf = 0.55 (hexane/acetone 1:1); UV/vis
(CH2Cl2) λ (ε) = 443 (394 000), 599 (52 400), 689 (24 400), 298
(22 700), 555 (10 000), 517 nm (6000); 1H NMR (500 MHz, CDCl3) δ
ꢀ2.04 (s, 2H), 1.38 (s, 36H), 1.62 (s, 18H), 4.74 (s, 8H), 5.02 (s, 4H),
7.36 (s, 4H), 7.53 (m, 2H), 7.60 (m, 4H), 8.04 (m, 4H), 8.87 (d, J = 4.5
Hz, 4H), 9.65 (d, J = 4.7 Hz, 4H); 13C NMR (125 MHz, CDCl3) δ 28.0,
28.3, 66.8, 70.5, 81.6, 82.3, 91.7, 97.4, 101.3, 115.1, 120.9, 123.8, 128.8,
128.8, 131.7, 136.3, 137.9, 149.7, 167.7, 168.6; HR MS (FD) calcd for
C84H90N4O18 1442.6250, found 1442.6232; isotope profiles match.
5,15-Dimesityl-10,20-bis(4-cyanophenylethynyl)porphyrin
(24). The reaction mixture was passed through a short pad of alumina
(alumina, hexane/acetone 4:1) to give pure product and a contaminated
fraction, which was rechromatographed (silica, CHCl3/toluene 1:3) to
give pure porphyrin 24. Both fractions were combined (28 mg, 18%)
and crystallized from hot CHCl3/hexanes to afford green crystals, which
were washed with hexanes, followed by CH2Cl2: Rf = 0.37
(CHCl3/toluene 1:1); UV/vis (CH2Cl2) λ (ε) = 445 (461 000), 602
(63 600), 692 (42 300), 257 (29 200), 294 (22 500), 558 (9800),
519 nm (6900); 1H NMR (500 MHz, TFAꢀCDCl3) δ 1.90 (s, 12H),
2.69 (s, 6H), 7.43 (s, 4H), 8.00 (d, J = 8.2 Hz, 4H), 8.20 (d, J = 8.5 Hz,
4H), 8.76 (d, J = 4.7 Hz, 4H), 9.52 (d, J = 4.7 Hz, 4H); 13C NMR (125
MHz, TFAꢀCDCl3) δ 20.6, 21.2, 91.5, 102.5, 112.0, 123.8, 127.4, 128.9,
129.2, 129.9, 132.8, 132.9, 134.1, 139.8, 141.5, 145.3, 145.8; HR MS
(FD) calcd for C56H40N6 796.3314, found 796.3324; isotope
profiles match.
5-(4-Octadecyloxyphenyl)dipyrromethane (18). The mix-
ture of aldehyde 17 (1.87 g, 4.99 mmol) and pyrrole (35 mL, 506 mmol)
was heated to 50 °C in order to dissolve aldehyde. To the homogeneous
solution was added a portion of InCl3 (111 mg, 0.50 mmol) and the
reaction mixture was stirred at rt for 2 h. Then an additional portion of
InCl3 (111 mg, 0.50 mmol) was added due to the incomplete conversion
of the aldehyde, and stirring was continued for the next 2 h. When the
conversion was full, ground NaOH (1.2 g, 30 mmol) was added. After
1 h the suspension was filtered through a pad of Celite and evaporated to
dryness, providing a brownish residue, which was crystallized from hot
MeOH to afford 18 as off-white crystals (2.109 g, 86%): mp =
1
75.7ꢀ77.8 °C (MeOH); H NMR (400 MHz, CDCl3) δ 0.88 (m,
3H), 1.20ꢀ1.35 (m, 28H), 1.44 (m, 2H), 1.76 (m, 2H), 3.92 (t, J = 6.5
Hz, 2H), 5.42 (s, 1H), 5.91 (m, 2H), 6.15 (m, 2H), 6.68 (m, 2H), 6.84
(m, 2H), 7.11 (m, 2H), 7.90 (br s, 2H); 13C NMR (100 MHz, CDCl3) δ
14.1, 22.7, 26.0, 29.3, 29.3, 29.4, 29.6, 29.6, 29.6, 29.7, 31.9, 43.1, 68.0,
107.0, 108.4, 114.6, 117.0, 129.3, 132.9, 133.9, 158.1; HR MS (EI) calcd
for C33H50N2O 490.3923, found 490.3918. Anal. Calcd for C33H50N2O:
C, 80.76; H, 10.27; N, 5.71. Found: C, 80.89; H, 10.21; N, 5.56.
General Procedure for the Preparation of trans-A2B2-
Porphyrins in MeCN. NH4Cl (214 mg, 4 mmol) was added to MeCN
(40 mL) degassed with a stream of Ar by sonication for 20 min. Then the
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ARTICLE
5,15-Dimesityl-10,20-bis(4-methoxyphenylethynyl)porphyrin
(25). The reaction mixture was passed through a short pad of alumina
(alumina, CH2Cl2). Subsequent chromatography (silica, hexanes/
CH2Cl2 1:1) afforded pure porphyrin 25 (14 mg, 9%): Rf = 0.46
(CH2Cl2/hexane 3:2); UV/vis (CH2Cl2) λ (ε) = 447 (387 000), 605
(53 900), 696 (30 800), 311 (23 300), 366 (16 600), 521 nm (5800); 1H
NMR (500 MHz, CDCl3) δ ꢀ1.76 (s, 2H), 1.87 (s, 12H), 2.65 (s, 6H),
3.94 (s, 6H), 7.09 (m, 4H), 7.30 (s, 4H), 7.93 (m, 4H), 8.65 (d, J = 4.7
Hz, 4H), 9.59 (d, J = 4.5 Hz, 4H); 13C NMR (125 MHz, CDCl3) δ 21.5,
21.5, 55.5, 90.5, 97.2, 101.0, 114.4, 116.0, 120.0, 127.8, 133.2, 137.7,
137.9, 139.2, 160.1; HR MS (FD) calcd for C56H46N4O2 806.3621,
found 806.3594; isotope profiles match.
5,15-Bis(4-cyanophenylethynyl)-10,20-bis(pentafluorophenyl)-
porphyrin (26). The reaction mixture was passed through a short pad of
alumina (alumina, CH2Cl2/hexanes 1:1). All fractions containing por-
phyrin were not evaporated due to the poor solubility of the product.
The porphyrin slowly crystallized from the solution. Then the crystals
were centrifuged, the supernatant was removed, and the solid was
washed with hexanes to give pure product 26 as green crystals (14.3
mg, 4%): Rf = 0.53 (DMF/CCl4 1:12); UV/vis (TFA) λ (ε) = 457
(265 000), 344 (21 400), 671 nm (1800); 1H NMR (500 MHz, TFA) δ
7.47 (d, J = 8.2 Hz, 4H), 7.72 (d, J = 8.2 Hz, 4H), 8.43 (d, J = 4.9 Hz, 4H),
9.15 (d, J = 4.9 Hz, 4H); 13C NMR (125 MHz, TFA) δ 89.3, 103.6,
104.2, 107.1, 111.4, 126.5, 128.7, 129.3, 132.0, 132.0, 144.0, 146.6; HR
MS (FD) calcd for C50H19F10N6 892.1433, found 892.1450; isotope
profiles match.
(ε) = 445 (442 000), 604 (62 800), 694 (40 500), 384 (26 900), 562
1
(10 800), 521 nm (6800); H NMR (500 MHz, CDCl3) δ ꢀ2.02 (s,
2H), 0.88 (m, 6H), 1.27ꢀ1.54 (m, 56H), 1.65 (m, 4H), 2.01 (m, 4H),
4.28 (t, J = 6.5 Hz, 4H), 7.32 (d, J = 8.6 Hz, 4H), 7.80 (d, J = 8.4 Hz, 4H),
7.99 (d, J = 8.4 Hz, 4H), 8.08 (d, J = 8.4 Hz, 4H), 8.88 (d, J = 4.7 Hz, 4H),
9.55 (d, J = 4.7 Hz, 4H); 13C NMR (125 MHz, CDCl3) δ 14.1, 22.7,
26.3, 29.4, 29.5, 29.6, 29.7, 29.7, 29.7, 29.7, 29.7, 29.8, 31.9, 68.4, 95.4,
96.3, 99.8, 111.6, 113.1, 118.6, 122.5, 128.5, 131.9, 132.3, 133.1, 135.6,
159.4; HR MS (FD) calcd for C86H100N6O2 1248.7908, found
1248.7883; isotope profiles match.
5,15-Bis(4-cyanophenylethynyl)-10,20-bis(3,4,5-trisdecyloxy-
phenyl)porphyrin (29). The reaction mixture was passed through a short
pad of alumina (alumina, CH2Cl2). Subsequent chromatography (silica,
CH2Cl2/hexanes 1:3 to 3:2) afforded pure product which was crystallized
from hot acetone to give 29 (36 mg) as green crystals. The filtrate containing
contaminated product was rechromatographed (DCVC, AcOEt/hexanes 3:7
to 1:1) and the solid was crystallized, yielding additional 4.5 mg of the pure
compound 29 (40.5 mg, total yield, 12%). Spectroscopic data were identical
to those reported for the method in MeCN.
5,15-Bis(3,4,5-trisdecyloxyphenyl)-10,20-bis(4-nitrophenyleth-
ynyl)porphyrin (30). The reaction mixture was passed through a short
pad of silica (silica, CH2Cl2/hexanes 1:3 to 3:2), followed by DCVC
(CH2Cl2/hexanes 1:3 to 2:3). SEC (THF) afforded pure solid which
was crystallized from hot acetone to give pure porphyrin 30 (41 mg,
12%) as green crystals: Rf = 0.37 (CH2Cl2/hexane 1:1); UV/vis
(CH2Cl2) λ (ε) = 455 (332 000), 609 (61 600), 696 (42 200), 384
1
(28 300), 523 nm (6700); H NMR (500 MHz, CHCl3) δ ꢀ1.98 (s,
5,15-Bis(4-cyanophenylethynyl)-10,20-bis(3,4,5-trisdecy-
loxyphenyl)porphyrin (29). The reaction mixture was passed
through a short pad of alumina (alumina, CH2Cl2). All fractions
containing porphyrin were combined, evaporated, and rechromato-
graphed (silica, hexanes/CH2Cl2 3:1 to 2:3). Then the solid was
suspended in hexanes and filtered to give the title porphyrin (23 mg,
7%) as green crystals: Rf = 0.59 (CH2Cl2/hexane 7:3); UV/vis
(CH2Cl2) λ (ε) = 448 (429 000), 604 (62 100), 693 (37 400), 560
2H), 0.83 (m, 12H), 0.92 (m, 6H), 1.22ꢀ1.54 (m, 80H), 1.69 (m, 4H),
1.90 (m, 8H), 2.00 (m, 4H), 4.13 (t, J = 6.4 Hz, 8H), 4.33 (t, J = 6.4 Hz,
4H), 7.42 (s, 4H), 8.12 (d, J = 8.9 Hz, 4H), 8.42 (d, J = 8.5 Hz, 4H), 9.00
(d, J = 4.6 Hz, 4H), 9.65 (d, J = 4.6 Hz, 4H); 13C NMR (125 MHz,
CDCl3) δ 14.1, 14.2, 22.7, 22.8, 26.2, 26.3, 29.3, 29.5, 29.5, 29.6, 29.6,
29.8, 29.9, 30.6, 31.9, 32.0, 69.5, 73.8, 95.5, 97.3, 99.9, 114.4, 122.9,
124.1, 130.6, 132.2, 135.8, 138.4, 147.2, 151.5; HR MS (FD) calcd for
C108H148N6O10 1689.1257, found 1689.1228; isotope profiles match.
Procedures for the Preparation of 25 and 28. 5,15-Dimesi-
tyl-10,20-bis(4-methoxyphenylethynyl)porphyrin (25). Aldehyde 9
(64 mg, 0.4 mmol) and dipyrromethane 19 (106 mg, 0.4 mmol) were
addedtodrytoluene(40mL) degassedwithastreamofArbysonicationfor
1
(10 500), 521 nm (6400); H NMR (500 MHz, CDCl3) δ ꢀ2.00 (s,
2H), 0.83 (m, 12H), 0.92 (m, 6H), 1.22ꢀ1.54 (m, 80H), 1.69 (m, 4H),
1.89 (m, 8H), 1.99 (m, 4H), 4.13 (t, J = 6.4 Hz, 8H), 4.32 (m, 4H), 7.41
(s, 4H), 7.86 (d, J = 8.2 Hz, 4H), 8.10 (d, J = 8.2 Hz, 4H), 8.98 (d, J = 4.6
Hz, 4H), 9.63 (d, J = 4.6 Hz, 4H); 13C NMR (125 MHz, CDCl3) δ 14.1,
14.2, 22.7, 22.8, 26.2, 26.3, 29.3, 29.5, 29.5, 29.5, 29.6, 29.6, 29.8, 29.8,
29.9, 30.6, 31.9, 32.0, 69.5, 73.8, 95.6, 96.3, 100.0, 111.9, 114.4, 122.8,
128.6, 132.1, 132.5, 135.9, 138.4, 151.5; HR MS (FD) calcd for
C110H148N6O6 1649.1460, found 1649.1483; isotope profiles match.
General Procedure for the Preparation of trans-A2B2-Porphyrins
in Toluene. Samples of aldehyde (0.4 mmol) and dipyrromethane
(0.4 mmol) were added to dry toluene (40 mL) degassed with a stream
35 min. Then BF3 Et2O (10 μL, 0.08 mmol) was added and the reaction
3
mixture was stirred at rt for 16.5 h. After this time, DDQ (140 mg, 0.62
mmol) was added, and the reaction mixture was stirred at rt for an additional
1 h. Then the reaction mixture was passed through a short pad of silica
(silica, CH2Cl2/hexanes 7:13 to 1:1). The solid was suspended in hexanes
and centrifuged to give pure porphyrin 25 (16 mg, 10%). Spectroscopic data
were identical to those reported for the method in MeCN.
of Ar by sonication for 35 min. Then BF3 Et2O (10 μL, 0.08 mmol) was
5,15-Bis(4-octadecyloxyphenyl)-10,20-bis(phenylethynyl)porphyrin
(28). Aldehyde 11 (50 μL, 0.4 mmol) and dipyrromethane 18 (200 mg,
0.4 mmol) were added to dry toluene (40 mL) degassed with a stream of
3
added and the reaction mixture was stirred at rt for 3 h. After this time,
DDQ (180 mg, 0.8 mmol) was added, and the reaction mixture was
stirred at rt for an additional 1 h. The purification details are described
for each case as follows.
Ar by sonication for 35 min. Then BF3 Et2O (20 μL, 0.16 mmol) was
3
added and the reaction mixture was stirred at rt for 22 h. After this time,
DDQ (180 mg, 0.8 mmol) was added, and the reaction mixture was
stirred at rt for an additional 1 h. Then the reaction mixture was passed
through a short pad of silica (silica, CH2Cl2/hexanes 1:1). Subsequent
chromatography (silica, CH2Cl2/hexanes 1:1 to 3:2) afforded pure
porphyrin 28 (7 mg, 3%), which was suspended in acetone and
centrifuged to give 28 in form of green crystals: Rf = 0.49 (hexane/
CH2Cl2 3:2); UV/vis (CH2Cl2) λ (ε) = 442 (364 000), 601 (50 500),
692 (27 200), 556 (9800), 517 nm (6100); 1H NMR (500 MHz,
CDCl3) δ ꢀ1.95 (s, 2H), 0.88 (m, 6H), 1.26ꢀ1.53 (m, 56H), 1.64
(m, 4H), 2.00 (m, 4H), 4.27 (t, J = 6.4 Hz, 4H), 7.31 (d, J = 8.5 Hz, 4H),
7.49ꢀ7.52 (m, 2H), 7.56ꢀ7.59 (m, 4H), 8.02ꢀ8.03 (m, 4H), 8.09 (d,
J = 8.5 Hz, 4H), 8.87 (d, J = 4.6 Hz, 4H), 9.67 (d, J = 4.6 Hz, 4H); 13C
NMR (125 MHz, CDCl3) δ 14.1, 22.7, 26.3, 29.4, 29.5, 29.6, 29.7, 29.7,
5,15-Bis(phenylethynyl)-10,20-bis[tris((tert-butoxycarbonyl)-
methyloxy)phenyl]porphyrin (23). The reaction mixture was passed
through a short pad of alumina (alumina, acetone/hexanes 1:4). All fractions
containing porphyrin were combined and rechromatographed (silica,
AcOEt/hexanes 1:3) to give pure porphyrin 23, which was suspended in
hexanes and centrifuged, affording green crystals (14 mg, 5%). Spectroscopic
data were identical to those reported for the method in MeCN.
5,15-Bis(4-cyanophenylethynyl)-10,20-bis(4-octadecyloxyphe-
nyl)porphyrin (27). The reaction mixture was passed through a short
pad of alumina (alumina, CH2Cl2). Subsequent chromatography (silica,
CH2Cl2/hexanes 1:4 to 2:3) afforded pure porphyrin 27 (35 mg, 14%),
which was crystallized from CH2Cl2/hexane to give 27 in the form of
green crystals: Rf = 0.30 (CH2Cl2/hexane 3:2); UV/vis (CH2Cl2) λ
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The Journal of Organic Chemistry
ARTICLE
29.7, 29.7, 31.9, 68.4, 92.0, 97.2, 101.0, 113.0, 121.8, 123.9, 128.7, 131.7,
133.5, 135.6, 159.2; HR MS (FD) calcd for C84H102N4O2 1198.8003,
found 1198.7974; isotope profiles match.
(9) LeCours, S. M.; DiMagno, S. G.; Therien, M. J. J. Am. Chem. Soc.
1996, 118, 11854–11864.
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Ispasoiu, R.; Goodson, T.; Martin, S. J.; Bradley, D. D. C.; Anderson,
H. L. J. Mater. Chem. 2001, 11, 312–320. (b) Anderson, H. L. Chem.
Commun. 1999, 2323–2330. (c) Taylor, P. N.; Wylie, A. P.; Huuskonen,
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Kuebler, S. M.; Denning, R. G.; Anderson, H. L. J. Am. Chem. Soc. 2000,
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(12) Milgrom, L. R.; Yahioglu, G. Tetrahedron Lett. 1996,
37, 4069–4072.
’ ASSOCIATED CONTENT
Supporting Information. 1H NMR spectra of com-
S
b
pounds 5ꢀ10, 13, 15, 16, 18, 21ꢀ30 and 13C NMR spectra of
compounds 8, 13, 15, 16, 18, 21ꢀ30. This material is available
free of charge via the Internet at http://pubs.acs.org.
(13) Plater, M. J.; Aiken, S.; Bourhill, G. Tetrahedron 2002,
58, 2415–2422.
(14) Krivokapic, A.; Anderson, H. L. Org. Biomol. Chem. 2003,
1, 3639–3641.
’ AUTHOR INFORMATION
Corresponding Author
daniel@icho.edu.pl
(15) Milgrom, L. R.; Rees, R. D.; Yahioglu, G. Tetrahedron Lett.
1997, 38, 4905–4908.
(16) Shen, Z.; Uno, H.; Shimizu, Y.; Ono, N. Org. Biomol. Chem.
2004, 2, 3442–3447.
(17) Wadsworth, D. H.; Geer, S. M.; Detty, M. R. J. Org. Chem. 1987,
52, 3662–3668.
’ ACKNOWLEDGMENT
This work was supported by the Ministry of Science and
Higher Education (Contract N204 123837).
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