Formylation reaction in series of meso-tetraaryl substituted porphyrins and chlorins

Article abstract of DOI:10.1023/B:RUBI.0000030133.22914.8c

The formylation of nickel complexes of meso-tetraaryl substituted porphyrins and chlorins was studied. An obvious regioselectivity was observed for the introduction of the first and subsequent formyl groups into chlorins.

Full text of DOI:10.1023/B:RUBI.0000030133.22914.8c

Russian Journal of Bioorganic Chemistry, Vol. 30, No. 3, 2004, pp. 261–267. Translated from Bioorganicheskaya Khimiya, Vol. 30, No. 3, 2004, pp. 293–300.
Original Russian Text Copyright © 2004 by Mironov, Moskalchuk, Shashkov.
Formylation Reaction in Series of meso-Tetraaryl Substituted
Porphyrins and Chlorins
1
A. F. Mironov*, T. V. Moskalchuk*, and A. S. Shashkov**
*Lomonosov State Academy of Fine Chemical Technology, pr. Vernadskogo 86, Moscow, 119571 Russia
**Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii pr. 47, Moscow, 119992 Russia
Received March 21, 2003; in final form, March 31, 2003
Abstract—The formylation of nickel complexes of meso-tetraaryl substituted porphyrins and chlorins was
studied. An obvious regioselectivity was observed for the introduction of the first and subsequent formyl groups
into chlorins.
Key words: formylation, meso-tetraarylporphyrins, meso-tetraarylchlorins
1
INTRODUCTION
chlorin metallocomplexes exhibits no regiospecificity
[21–23].
Tetraarylporphyrins are a widely distributed and
sufficiently available porphyrins, which determines
their extensive use in various areas of science and tech-
nology [1–5].
The goal of this work was studying the formylation
regiospecificity in the series of meso-tetraaryl substi-
tuted porphyrins and chlorins. We paid a particular
attention to the positions of both the first and the next
formyl groups introduced in the macrocycles of por-
phyrins and chlorins.
Chemical transformations of the porphyrins with no
additional functional groups in their macrocycles are
usually achieved using the electrophylic substitution, in
particular, formylation. Introduction of the first formyl
group in the β-position of porphyrin macrocycle is usu-
ally achieved according to theVilsmeier reaction and its
modifications are widely discussed in numerous publi-
cations [6–12]. However, far fewer papers are devoted
to the introduction of the second formyl group in the
macrocycle. It was shown that the electrophylic attack
can proceed both upon the position neighboring to the
already formylated and the opposite pyrrole ring of the
macrocycle [13–15].
RESULTS AND DISCUSSION
We chose the nickel complexes of meso-tetrakis(p-
methoxyphenyl)porphyrin (Ib) and its dihydro deriv-
ative, chlorin (IIb) as the subjects of this study
(Scheme 1).
A diformyl derivative of the porphyrin may be
obtained by two ways. According to the first way,
monoformylporphyrin (III) is initially synthesized, and
the second formyl group is introduced further. The sec-
ond procedure implies a one-step process when the
starting porphyrin (Ib) is heated for a long time with a
large excess of DMF and POCl3. In the first case, the
total yield of diformylporphyrin was 70%, whereas the
yield did not exceed 5–10% in the second. Therefore,
we preferred the first procedure.
An analysis of the reaction mixture allowed us to
establish that two isomeric diformylporphyrins were
formed when the second formyl group was introduced.
A thorough separation by TLC led to two substances.
The less mobile product (Rf 0.70) had red color, and the
more mobile one (Rf 0.72) was green-colored, which is
unusual for porphyrins. The green color is known to be
characteristic of natural chlorophylls [24] and synthetic
chlorins [2]. Such a color might result from an intramo-
This reaction is of a special interest in the series of
reduced meso-tetraarylporphyrins, chlorins, because
these could be used as the potential photosensitizers
and models of biological systems [16–18]. Unlike the
natural chlorins, in which the reaction of electrophylic
substitution preferentially proceeds at the meso-posi-
tion neighboring to the reduced pyrrole ring [19, 20],
the regiospecificity of the substitution in meso-tet-
raarylchlorins is poorly studied. For example, it is
known that, in the case of meso-tetraarylchlorins in the
form of free bases, the electrophylic substitution (bro-
mination and nitration) takes place at the pyrrole ring
opposite to the reduced ring, whereas the reaction of the
1
Corresponding author; phone: +7 (095) 434-8678; e-mail:
httos.mitht@g23.relcom.ru
1068-1620/04/3003-0261 © 2004 MAIK “Nauka /Interperiodica”

262
MIRONOV et al.
Ar
M
Ar
M
H2
C
CH2
B
C
A
N
N
N
N
N
N
N
N
i
Ar
Ar
Ar
Ar
D
Ar
Ar
(I‡, Ib)
M = 2H (a), Ni (b)
(II‡, IIb)
ii
ii
Ar
Ar
H2
C
CH2
N
N
N
N
N
N
N
iii
Ni
Ar
Ar
Ni
Ar
Ar
N
CHO
CHO
Ar
(IV)
Ar
Ar
(III)
ii
ii
ii
Ar
Ni
H2
OHC
OHC
C
CH2
N
N
N
N
N
N
N
N
iii
Ni
Ar
Ar
Ar
Ar
CHO
CHO
Ar
Ar
(V)
(VII)
+
+
Ar
Ar
H2
C
CH2
N
N
N
N
N
N
N
iii
Ni
Ar
Ar
Ni
Ar
Ar
N
OHC
CHO
OHC
CHO
2'
3'
Ar
(VIII)
Ar
(VI)
1'
4'
Ar =
OCH3
6'
5'
Scheme 1. The synthesis of mono- and diformyl substituted meso-tetrakis(p-methoxyphenyl)porphyrins and chlorins. Reagents and
reaction conditions: i, p-CH C H SO NHNH /K CO , pyridine; ii, POCl –DMF/CHCl ; iii, 2,3-dichloro-5,6-dicyanobenzo-
3
6
4
2
2
2
3
3
3
quinone-1,4/CHCl .
3
lecular cyclization of one of formyl groups with a which occurs in chlorin systems. A similar cycliza-
neighboring phenyl ring, which led to the formation tion had been described for monoformyl-meso-tet-
of an additional six-membered ring and a partial dis- raarylporphyrins under their treatment with strong
turbance in the macrocycle conjugation system, acids [10, 25–27]. In our case, phosphorous oxychlo-
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 30 No. 3 2004

FORMYLATION REACTION IN SERIES
263
mer exhibit one 13C signal with the chemical shift of
187.84 ppm, whereas two protons of these substituents
and two neighboring β-protons in the H NMR spec-
ride or the products of its decomposition might be
such a reagent.
1
OCH3
trum display four closely located singlets in the 9.30–
9.27 ppm region. The other four β-protons in the unsub-
stituted pyrrole rings resonate at 8.73–8.70 ppm, the
13C nuclei of the β-carbons have the chemical shifts of
136.36 and 136.12 ppm in the substituted and 133.39
and 133.29 ppm in unsubstituted pyrroles. These results
indicate a high symmetry of the green isomer and con-
firm the localization of its formyl groups in the opposite
pyrrole rings.
O
N
N
N
N
Ni
H3CO
OCH3
The formyl groups of (VI) exhibit 13C NMR signals
at 187.88, 187.69, and 187.59 ppm and the correspond-
ing proton signals at 9.29, 9.27, and 9.11 ppm. Two β-
protons neighboring with the formyl groups resonate in
the same range at 9.32, 9.30, 9.26, and 9.25 ppm,
whereas four protons in the unsubstituted pyrrole rings
exhibits a group of signals in a stronger field at 8.75–
8.66 ppm. The 13C NMR signals of the β-carbon atoms
in the pyrroles with formyl groups are observed at
136.45 and 135.72 ppm. Formyl groups exert a strong
influence on the chemical shifts of 13C nuclei in the
meso-bridges. The adjacent atoms exhibit three signals
at 126.68, 121.51, and 120.95 ppm, whereas the more
distant atoms also exert three peaks but in a stronger
field (119.69, 119.36, and 118.20 ppm).
OCH3
(IX)
Therefore, we needed to establish whether the green
substance has the structure (IX) or it was a diformyl
substituted porphyrin.
The measurement of HRMS allowed us to reject
structure (IX) and unequivocally confirm the presence
of two formyl groups in the macrocycle of green com-
pound. The found m/z value for its molecular ion
(846.1984) was close to the calculated molecular mass
of diformylporphyrin (846.1988). The red-colored sub-
stance was also diformylporphyrin according to
HRMS.
Two formyl groups in the resulting porphyrins could
be situated either in one or in the opposite pyrrole rings
as shown in (V). It is also possible that they are in the
neighboring cycles as in (VI). In the first case, the pres-
ence of two isomers very close in their properties is
possible, whereas three isomers were possible in the
second case; however, TLC did not help detect them.
Thus, we showed that the formyl group of nickel
complex of 2-formyl-5,10,15,20-tetrakis(p-methoxy-
phenyl)porphyrin exerts no substantial effect on the
position of introduction of the second formyl group:
isomers (VI) and (V) are formed at the approximate
ratio of 2 : 1. Such an isomer distribution is explained
by the fact that, in the case of formation of isomer (VI),
the electrophylic attack may occur at two pyrrole rings
adjacent with the aldehyde group.
The course of formylation reaction of tetraarylchlo-
rins was studied on the nickel complex of meso-tet-
rakis(p-methoxyphenyl)chlorin (IIb), which was
A
preliminary assignment of the isomeric obtained by a standard procedure of the meso-tetraphe-
diformylporphyrins of green and red color to the struc- nylporphyrin reduction. Namely, meso-tetrakis(p-
tures (V) and (VI) was made on the basis of 1H NMR
spectra. The characteristic signals from 12 protons of
four methoxy groups in the green isomer were repre-
sented by two six-proton singlets at 4.04 and 4.06 ppm.
The red isomer exhibits five overlapping singlets in this
area. These results allowed the conclusion that the
methoxyphenyl)porphyrin (Ia) was treated with p-tolu-
enesulfonylhydrazine in pyridine in the presence of
potassium carbonate in argon atmosphere [28]. The
product, meso-tetrakis(p-methoxyphenyl)chlorin (IIa),
was isolated by chromatography on silica gel 40/100 in
benzene and recrystallization from benzene in 70%
1
green isomer has a more symmetric structure, which yield. A four-proton singlet was observed in its H
indicates the location of formyl groups in the opposite NMR at 4.21 ppm, which corresponded to protons of
pyrrole rings as shown in formula (V). The structure the reduced pyrrole ring. Two two-proton doublets at
(VI) with the neighboring location of formyl groups 8.57 and 8.17 ppm and a two-proton singlet at 8.42 ppm
was ascribed to the second isomer.
were observed in the region of the β-proton signals.
A more reliable proof of the location of formyl
groups in the isomers was obtained from their 13C NMR
spectra and the spectra of heteronuclear resonance
Next, we treated (IIa) with nickel chloride in DMF
at 115°C for 1 h in argon atmosphere. The green reac-
tion mixture was cooled and diluted with acetone, and
using the 1H and 13C nuclei. The results can be summa- the precipitated crystals were filtered. The yield of (IIb)
rized as follows. Two formyl groups of the green iso- was 90%. Its electronic spectrum was typical of chlorin
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 30 No. 3 2004

264
MIRONOV et al.
8.15 ppm. The protons of methoxy groups resonated at
(V)
Ar
Ni
(VI)
Ar
4.04 and 3.97 ppm and had equal 6 H intensities. In the
electronic absorption spectrum, α-band was shifted to
the long-wave area (679 nm).
Unlike the above-described (VII), chlorin (VIII)
had more complex 1H NMR spectrum, which indicated
its less symmetry. So, a multiplet of the general inten-
sity of 4 H at 8.88–8.58 ppm (two protons of formyl
groups and two adjacent β-protons) and two groups of
multiplets at 7.93–7.89 and 8.30–8.23 ppm with the
intensities of 1 H each (β-protons of the unsubstituted
pyrrole ring) are exhibited. The α-band of its electronic
spectrum was exhibited at 639 nm.
NC
CN
CN
N
N
N
N
N
N
N
N
Ni
Ar
Ar
Ar
Ar
NC
Ar
Ar
Molecular peaks with m/z values 848.2140 and
848.2153 were present in the high resolution mass
spectra of (VII) and (VIII), which also confirmed the
presence of two formyl groups in the chlorins (calcu-
lated mass 848.2144).
(X)
(XI)
Scheme 2. The synthesis of dicyano substituted meso-tet-
rakis(p-methoxyphenyl)porphyrins. Reagents and reaction
conditions: NH OH · HCl, pyridine, 60°C; acetic anhy-
2
dride, reflux.
Structures of the resulting compounds (IV), (VII),
and (VIII) were proved by their oxidation to the corre-
sponding porphyrins by means of DDQ (2,3-dichloro-
5,6-dicyanobenzoquinone-1,4). The chromatographic
mobilities and electronic absorption spectra of the
resulting compounds were identical to those of the pre-
viously obtained porphyrins (III), (V), and (VI).
As mentioned above, the porphyrin with formyl
groups in the opposite pyrrole rings acquires an unusual
green color. To reveal whether this regularity is com-
mon for the meso-tetraarylporphyrins with other elec-
tronoacceptor groups, we undertook the synthesis of
dicyanoporphyrins (X) and (XI) (Scheme 2).
metallocomplexes [29] and included an intensive α-
band at 617 nm.
The subsequent formylation of chlorin (IIb) was
carried out under various conditions. Its treatment with
the Vilsmeier complex for 25 min led to 40% yield of
the product, which, according to HRMS, was the nickel
complex of monoformyl-meso-tetrakis(p-methoxyphe-
nyl)chlorin (IV). The position of formyl group in the
product was proved by 1H NMR spectroscopy.
Four singlets at 9.01, 8.92, 8.84, and 8.61 ppm with
the general intensity of two protons were assigned to
the formyl group and the adjacent β-proton. The inten-
sities of each singlet were approximately 0.5 H, which
indicates the presence of two regioisomers of formyl
group relative to the reduced pyrrole ring. The form of
signals of β-protons in the unsubstituted pyrrole rings
in the 1H NMR spectrum (eight doublets with the gen-
eral intensity of 4 H) also pointed out to the existence
of two isomers.
To this end, (V) and (VI) were treated with hydrox-
ylamine in pyridine and, then, refluxed in acetic anhy-
dride. Nickel complexes of β,β'-dicyano-meso-tet-
rakis(p-methoxyphenyl)porphyrins (X) and (XI)
resulted.
1
Their structures were confirmed by H NMR, UV,
and IR spectroscopy and HRMS. The signals of formyl
1
protons were absent from their H NMR spectra, and
the signals of β-protons were shifted downfield. Their
IR spectra exhibited the characteristic absorption bands
of CN groups at 2229 and 2221 cm–1. The compound
(X) had the green color, and (XI) was red.
Our results obtained in this work allow the follow-
ing conclusions about the character of formylation of
nickel complexes of tetraarylporphyrins and chlorins:
These results allowed the conclusion that the first
formyl group is introduced into the pyrrole ring of (IIb)
adjacent to the reduced pyrrole ring and leads to (IV).
A longer heating (2 h) led to the following com-
pounds: the nickel complex of the β,β'-diformylated
meso-tetrakis(p-methoxyphenyl)chlorin (VII) with the
opposite position of formyl groups in approximately
4% yield and the compound (VIII) with formyl groups
in the neighboring pyrrole rings, whose yield was 36%.
The structures of these chlorins were established by
means of 1H NMR and UV spectroscopy and high res-
olution mass spectrometry.
(1) The introduction of the first and, in particular,
the second formyl group is substantially facilitated by
the presence of a partially reduced pyrrole ring in mac-
rocycle. For porphyrins, it is rational to preliminarily
obtain monoformyl derivative, whereas the two formyl
groups can directly be introduced into dihydroporphy-
rin.
Two singlets at 8.92 and 8.87 ppm with the intensi-
ties of 2 H each were observed in the 1H NMR spectrum
of (VII); they were assigned to the protons of two
(2) The presence of the first formyl group in porphy-
formyl groups and the adjacent β-protons. The singlet rin has a little effect on the direction of further electro-
of β-H of the unsubstituted pyrrole ring resonated at phylic substitution of macrocycle, and the isomeric
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 30 No. 3 2004

FORMYLATION REACTION IN SERIES
265
A,C- and C,D-diformyl substituted porphyrins are mmol) in chloroform (15 ml). The reaction mixture was
formed in the approximate ratio of 1 : 2.
refluxed for 3 h and treated as described for the prepa-
ration of (III). The total yield of (V) and (VI) was 44
mg (70%). Pure compounds (V) and (VI) were
obtained by a thorough separation by TLC in chloro-
form.
(3) Chlorins demonstrate a substantially clear
regiospecificity in the introduction of formyl groups:
the first formyl enters into the pyrrole ring adjacent to
the partially hydrogenated cycle, whereas the subse-
quent formylation is preferably directed into the pyrrole
opposite to the hydrogenated cycle, which leads to the
formation of C,D-diformylchlorin.
(V); Rf 0.72; electronic spectrum, λmax, nm (relative
intensity): 443 (1), 520 (0.01), 559 (0.013), 605 (0.10);
IR spectrum: 1669, 1720 cm–1; 1H NMR: 9.30 and 9.28
(2 H, two s, CHO), 9.29 and 9.28 (2 H, two s, β-H adja-
cent to CHO), 8.73–8.70 (4 H, m, β-H), 7.92–7.87 (8 H,
m, H2' and H6' of Ph), 7.24–7.22 (8 H, m, H3' and H5'
of Ph), 4.06 and 4.04 (6 H each, two s, OCH3); 13C
NMR: 187.8, 159.8, 145.4, 145.3, 144.3, 144.1, 142.3,
142.1, 141.9, 140.7, 140.4, 136.4, 136.1, 135.1, 135.0,
134.9, 133.5, 133.4, 133.3, 132.8, 131.8, 122.0, 121.6,
118.6, 118.2, 113.2, 112.8, 55.57, and 55.54; MS, m/z:
846.1984 [M]+. Calculated for C50H36N4O658Ni: å
846.1988.
(VI); Rf 0.70; electronic spectrum, λmax, nm (relative
intensity): 449 (1), 558 (0.10), 605sh (0.02); IR spec-
trum: 1667 cm–1; 1H NMR: 9.29, 9.27, and 9.11 (2 H,
three s, CHO), 9.32, 9.30, 9.26, and 9.25 (2 H, m, β-H
in C and D pyrrole rings), 8.75–8.66 (4 H, m, β-H in A
and B pyrrole rings), 7.96–7.86 (8 H, m, H2' and H6' of
Ph), 7.24–7.21 (8 H, m, H3' and H5' of Ph), 4.06–4.04
(12 H, m, éëç3); 13C NMR: 187.9, 187.7, 187.6,
161.1, 160.5, 160.3, 159.8, 159.6, 145.6, 145.4, 145.1,
144.2, 143.7, 142.8, 142.3, 142.0, 141.2, 140.9, 140.6,
136.5, 135.7, 135.9, 135.1, 135.07, 135.0, 134.9, 134.8,
133.7, 133.5, 133.4, 133.3, 133.1, 133.0, 132.8, 132.5,
132.5, 132.1, 131.7, 121.7, 121.5, 120.9, 119.7, 119.4,
118.2, 113.7, 113.2, 112.8, 112.7, and 55.56; MS, m/z:
846.1950 [M]+. Calculated for C50H36N4O658Ni: å
846.1988.
EXPERIMENTAL
1
The H NMR spectra were obtained on a Bruker
MSL-200 or a Bruker DRX-500 instrument for the
solutions in CDCl3; Me4Si was used as an internal stan-
dard. Chemical shifts are given in ppm, and spin–spin
coupling constants in Hz. The two-dimensional hetero-
nuclear spectra HSQC and HMBC and standard soft-
ware from Bruker were applied for assigning 13C NMR
spectra. The HMBC experiment was minimized for the
spin–spin coupling constant 1ç/13ë of 8 Hz. Electronic
spectra were measured on a Jasco 7800 spectrophoto-
meter in chloroform. High resolution mass spectra were
obtained on a Micromass Avtospec instrument (EI,
70 eV, 200°C). IR spectra were registered on a FT Nico-
let Magna-750 spectrometer in KBr pellets at a resolu-
tion of 2 cm–1. Precoated HPTLC Kieselgel 60F254
(Merck) and a 80 : 1 chloroform–methanol system were
used for TLC.
2-Formyl-5,10,15,20-tetrakis(p-methoxyphenyl)-
porphyrin nickel complex (III). A Vilsmeier complex
prepared from DMF (6 ml, 78 mmol) and POCl3
(7.2 ml, 79 mmol) at cooling was added to a solution of
5,10,15,20-tetrakis(p-methoxyphenyl)porphyrin nickel
complex (Ib) (219 mg, 0.28 mmol) in chloroform
(160 ml). The reaction mixture was refluxed for 4 h,
cooled, and poured into cold water. After the adjust-
ment to pH 9–10, the product was extracted with chlo-
roform. The organic layer was several times washed
with water to neutral pH and evaporated. The residue
was twice recrystallized from a chloroform–petroleum
ether to get (III); yield 207 mg (92%); electronic spec-
trum, λmax, nm (ε × 10–3): 435 (210), 510sh (6), 544 (14),
585 (10); lit.: 434 (215), 510sh (6), 544 (14), 582 (11)
[10]; IR spectrum: 1667 cm–1; 1H NMR: 9.33 (1 H, s, β-
5,10,15,20-Tetrakis(p-methoxyphenyl)chlorin (IIa).
Potassium carbonate (2.5 g) and p-toluenesulfonylhy-
drazide (1.28 g, 7 mmol) were added to a solution of
5,10,15,20-tetrakis(p-methoxyphenyl)porphyrin (Ia)
(1.3 g, 1.78 mmol) in anhydrous pyridine (100 ml). The
mixture was heated at 105°ë in argon atmosphere for
2 h at stirring, cooled, diluted with benzene (250 ml)
and water (150 ml), and refluxed for 40 min. The ben-
zene layer was separated, washed with 6 N HCl, water,
NaHCO3 solution, water again, and evaporated in a vac-
H), 9.29 (1 H, s, CHO), 8.78–8.70 (6 H, m, β-H), 7.93– uum. The product (IIa) was isolated by chromatogra-
7.88 (8 H, m, H2' and H6' of Ph), 7.23–7.21 (8 H, m, H' phy on a silica gel 40/100 column (30 × 60 mm) eluted
and H5' of Ph), 4.05 and 4.04 (9 H and 3 H, two s, with benzene and recrystallized from benzene; yield
OCH3); 13C NMR: 188.4, 159.6, 135.6, 135.0, 134.4, 0.91 g (70%); electronic spectrum, λmax, nm (ε × 10–3):
1
133.0, 132.9, 132.7, 132.6, 132.4, 113.0, 112.7, 112.6,
and 55.5.
421 (196), 521 (14), 550 (10), 597 (4), 651 (19); H
NMR: 8.57 (2 H, d, J 4.9, β-H), 8.42 (2 H, s, β-H), 8.17
(2 H, d, J 4.9, β-H), 7.93–7.88 (8 H, m, H2' and H6' of
Ph), 7.22–7.16 (8 H, m, H' and H5' of Ph), 4.13 (4 H, br.
s, ëç2–ëç2), 4.04 and 4.00 (2 × 6 ç, two s, éëç3),
−1.46 (2 H, br. s, NH).
Formylation of 2-formyl-5,10,15,20-tetrakis(p-
methoxyphenyl)porphyrin nickel complex. A Vils-
meier complex prepared from DMF (4 ml, 52 mmol)
and POCl3 (4.8 ml, 53 mmol) at cooling was added to a
solution of 2-formyl-5,10,15,20-tetrakis(p-methox-
5,10,15,20-Tetrakis(p-methoxyphenyl)chlorin ni-
yphenyl)porphyrin nickel complex (III) (61 mg, 0.074 ckel complex (IIb). Nickel(II) chloride (500 mg,
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 30 No. 3 2004

266
MIRONOV et al.
2.1 mmol) was added to a solution of (IIa) (120 mg, vacuum to a minimal volume. Then, it was filtered
0.163 mmol) in DMF (30 ml). The reaction mixture through a layer of silica gel 5/40 using chloroform as
was heated at 115°ë in argon atmosphere for 1 h, eluent.
cooled, diluted with acetone, the precipitated crystals
Chlorins (IV), (VII), and (VIII) yielded compounds
were filtered, washed with water, and dried to give
that were identical according to their electronic spectra
and chromatographic mobility to (III), (V), and (VI),
respectively.
(IIb); yield 116 mg (90%); electronic spectrum, λmax
,
nm (ε × 10−3): 419 (129), 525 (7), 617 (18).
b,b'-Dicyano-5,10,15,20-tetrakis(p-methoxyphe-
nyl)porphyrin nickel complex (X). A solution of (V)
(10 mg, 0.012 mmol) and hydroxylamine hydrochlo-
ride (70 mg) in pyridine (5 ml) was heated for 1 h at
60°ë; diluted with chloroform; washed with water
adjusted to pH 4–5, aqueous solution of NaHCO3, and
water again; and evaporated in a vacuum. The residue
was refluxed with acetic anhydride (4 ml) for 90 min
and poured into water. Acetic anhydride was decom-
posed with aqueous solution of NaHCO3, and the
resulting precipitate was dissolved in chloroform,
washed with water, and evaporated. The product (X)
was recrystallized from a chloroform–methanol mix-
ture; yield 8.2 mg (83%); electronic spectrum, λmax, nm
(relative intensity): 434 (1), 513 (0.035), 551 (0.051),
b-Formyl-5,10,15,20-Tetrakis(p-methoxyphenyl)-
chlorin nickel complex (IV). A Vilsmeier complex
prepared from DMF (2 ml) and POCl3 (2.4 ml) at cool-
ing was added to a solution of (IIb) (100 mg,
0.125 mmol) in chloroform (15 ml). The reaction mix-
ture was kept for 3 h at 60°ë in argon atmosphere and
treated as described for the preparation of (III). The
product (IV) was isolated by TLC in chloroform; yield
41 mg (40%); electronic spectrum, λmax, nm (relative
intensity): 434 (1), 520 (0.10), 568 (0.13), 611 (0.19),
647 (0.21); 1H NMR: 9.01, 8.92, 8.84, and 8.61 (4 × 0.5
H, four s, CHO and the adjacent β-H), 8.29–7.84 (4 H,
m, β-H), 7.72–7.37 (8 H, m, H2' and H6' of Ph), 7.13–
7.03 (8 H, m, H' and H5' of Ph), 3.97–3.90 (12 H, m,
OCH3), 3.76–3.67 (4 H, m, CH2–CH2); MS, m/z:
1
592 (0.074); IR spectrum: 2229 cm–1 (CN); H NMR:
820.2197 [M]+, calculated for C49H38N4O558Ni: M
820.2196.
9.26 and 9.24 (2 H, s, β-H adjacent to CN), 8.75–8.66
(4 H, m, β-H), 7.85–7.77 (8 H, m, H2' and H6' of Ph),
7.23 and 7.19 (8 H, two s, H3' and H5' of Ph), 4.02
(12 H, s, OCH3); MS, m/z: 840.2003 [M]+, calculated
Formylation of 5,10,15,20-tetrakis(p-methoxy-
phenyl)chlorin nickel complex. A Vilsmeier complex
prepared from DMF (2 ml) and POCl3 (2.4 ml) at cool-
ing was added to a solution of (IIb) (50 mg,
0.0625 mmol) in chloroform (10 ml). The reaction mix-
ture was kept for 2 h at 60°ë in argon atmosphere and
treated as described for the preparation of (V) and (VI)
to give (VII) and (VIII).
for C50H34N6O458Ni: M 840.1995.
b,b'-Dicyano-5,10,15,20-tetrakis(p-methoxyphe-
nyl)porphyrin nickel complex (XI) was obtained sim-
ilarly to (X) from (VI) (10 mg, 0.012 mmol); yield
7.6 mg (77%); electronic spectrum, λmax, nm (relative
intensity): 439 (1), 548 (0.091), 591sh (0.03); IR spec-
trum: 2221 cm–1 (CN); 1H NMR: 9.23–9.09 (2 H, s, β-
H adjacent to CN), 8.75–8.66 (4 H, m, β-H), 7.88–7.71
(8 H, m, H2' and H6' of Ph), 7.22–7.16 (8 H, m, H3' and
H5' of Ph), 4.02 (12 H, s, éëç3); MS, m/z: 840.1988
Compound (VII); yield 2 mg (4%); electronic spec-
trum, λmax, nm (relative intensity): 436 (1), 585sh
1
(0.17), 633sh (0.20), 674.2 (0.45); H NMR: 8.92 and
8.87 (2 H, s, CHO and 2 H, s, adjacent β-H), 8.15 (2 H,
s, β-H), 7.72–7.37 (8 H, m, H2' and H6' of Ph), 7.24–
7.04 (8 H, m, H' and H5' of Ph), 3.97 and 3.91 (6 H
each, two s, OCH3), 3.81 (4 H, s, CH2–CH2); MS, m/z:
[M]+, calculated for C50H34N6O458Ni: M 840.1995.
848.2140 [M]+, calculated for C50H38N4O658Ni:
M 848.2145.
ACKNOWLEDGMENTS
This work was supported by the grant of the Minis-
try of Education of RF Basic Studies in the Area of
Technological Sciences TO2-09.1-874 and the grant of
Support of the Leading Scientific Schools of RF
no. 00-15-97866.
Compound (VIII); yield 18 mg (36%); electronic
spectrum, λmax, nm (relative intensity): 454 (1), 537
1
(0.14), 591 (0.14), 640 (0.24); H NMR: 8.99–8.57
(4 H, m, 2 CHO and 2 adjacent β-H), 8.30–7.89 (2 H,
m, β-H), 7.70–7.45 (8 H, m, H2' and H6' of Ph), 7.12–
7.03 (8 H, m, H' and H5' of Ph), 3.96–3.90 (12 H, m,
OCH3), 3.71 (4 H, br. s, CH2–CH2); MS, m/z: 848.2153
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