Transformations of meso-Iminofunctionalized Pd(II) and Ni(II)-Complexes of β-Alkylsubstituted Porphyrins

Article abstract of DOI:10.1002/ejoc.201801659

The meso-imino derivatives of the palladium (II) and nickel (II) complexes of coproporphyrins I and II and β-octaethylporphyrin were obtained by the Vilsmeier formylation followed by interaction with amines. The metal complexes of the azomethines obtained were transformed to the corresponding complexes of cyclopentane and cyclopentane-pyrrolidone fused porphyrin derivatives by thermolysis. The plausible mechanism of such transformations was suggested and substantiated with quantum chemical calculations. Meso-cyano-, meso-hydroxy-, and meso-aminocarbonyl derivatives of β-octaethylporphyrin were obtained by treatment of the corresponding meso-imino derivatives with bases. Demetalation of the nickel complex of the meso- hydroxy-β-octaethylporphyrin led to formation of the free base derivative. The structures of new types of the porphyrin derivatives were determined via X-ray powder diffraction analysis. The obtained types of porphyrins are promising candidates to use as photosensitizers in medicine applications due to their longer wave absorption combined with high stability.

Full text of DOI:10.1002/ejoc.201801659

A Journal of
Accepted Article
Title: Transformations of meso-iminofunctionalized Pd(II) and Ni(II)-
complexes of β-alkylsubstituted porphyrins
Authors: Dina R. Erzina, Ilya A. Zamilatskov, Nadezhda M.
Stanetskaya, Vladimir S. Tyurin, Grigory L. Kozhemyakin,
Gelii V. Ponomarev, Vladimir V. Chernyshev, and Andrew N.
Fitch
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content of this Accepted Article.
To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201801659
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
PER
rmations of meso-iminofunctionalized Pd(II) and Ni(II)-
xes of β-alkylsubstituted porphyrins
na,[a] Ilya A. Zamilatskov, *[a] Nadezhda M. Stanetskaya,[a] Vladimir S.Tyurin,[a] Grigory L.
n,[a] Gelii V. Ponomarev,[b] Vladimir V. Chernyshev,[a,c] and Andrew N. Fitch.[d]
meso-imino derivatives of the palladium (II) and
plexes of coproporphyrins and II and β-
were obtained by the Vilsmeier formylation
directions of modification of porphyrins and their derivatives is
the formyl group insertion into various positions of the
macrocycle. The carbonyl function of the formyl group serves as
I
n
raction with amines. The metal complexes of the
tained were transformed to the corresponding
yclopentane and cyclopentane-pyrrolidone fused
tives by thermolysis. The plausible mechanism of
ations was suggested and substantiated with
cal calculations. Meso-cyano-, meso-hydroxy- and
onyl derivatives of β-octaethylporphyrin were
tment of the corresponding meso-imino derivatives
metalation of the nickel complex of the meso-
hylporphyrin led to formation of the free base
tructures of new types of the porphyrin derivatives
via X-ray powder diffraction analysis. The obtained
hyrins are promising candidates to use as
in medicine applications due to their longer wave
ned with high stability.
a modification center for the preparation of compounds
containing various groups: vinyl, carboxyl, hydroxyl, etc[15]. There
are a large number of examples of the utilization of the formyl
group as a precursor for further modifications using following
reactions: Wittig[16–20], Grignard[119,21], McMurry[22], Schiff bases
formation[23–26], Knoevenagel[27] etc.
Synthesis of Schiff bases of meso-formylpophyrins is a particular
promising direction of research. Meso-iminoporphyrins were
applied as oxygen/pH multisensors[28]. Azomethine bridge in
bisporphyrins and porphyrin conjugates was shown to provide
rapid and efficient excited-state energy transfer while
maintaining weak ground state electronic interactions[29–31]
. A
huge variety of the conjugates of tetrapyrrolic compounds,
including those with improved photophysical characteristics can
potentially be obtained using imine formation as a bridging
tool[32]. Further transformation of the imino-group to other
functional groups provides an additional tool for the porphyrin
structure and properties tuning.
n
The investigation of methods of synthesis and applications of
meso-formyl and meso-imino porphyrin derivatives has been
conducted in our research group[333,34]. There are two approaches
to the synthesis of Schiff bases: the reaction of formylporphyrin
with amines and the interaction of the so called "phosphorus
complex" with amines. The classical reaction of amines with the
aldehyde derivatives of porphyrins was studied on the example
of synthesis of oximes, which were obtained with high yields by
boiling of the formyl derivatives of porphyrins with hydroxylamine
for several hours in aqueous pyridine[19,23,35–37]. Oximes are of
interest as precursors for obtaining cyanoporphyrins with the aim
of transformation of the latter to carboxy substituted porphyrins
and also as starting materials for further synthesis of products of
d
their derivatives are the key compounds
nergetics of the biosphere. In particular, metal
orphyrins form the basis of the photosynthetic
r
oxygen (hemoglobin), catalyze oxidative
part of enzymes (cytochromes). The unique
e tetrapyrrolic compounds are associated with
ectron
aromatic
system.
Photophysical
of porphyrins and their analogues allow to
se these dyes as fluorescent/phosphorescent
nalysis[1–6], photosensitizers in photovoltaics[7,8]
,
10]
and photodynamic therapy of tumors[2,4] and
acne, psoriasis, atherosclerosis)[11,12]
.
intramolecular cyclization[37]
The reaction of the "phosphorus complex" with amines has
become more widespread[23,38]]
Azomethine derivatives of
.
rious groups into the tetrapyrrolic macrocycle
tions to obtain new derivatives with improved
characteristics[13,14]. One of the most important
.
formylporphyrins were obtained by direct interaction of the
"phosphorus complex" with amines. This method is used in the
synthesis of Schiff bases with not only aliphatic amines, but also
with hydroxylamine, hydrazine, some amino acids, excluding
amino acids which don’t react due to sterical hindrance.
The study of mass spectra of Schiff bases is of particular interest.
For the first time mass spectrometric study of meso-substituted
porphyrins was performed by P. Clezy[39], who demonstrated
that all meso-substituted derivatives of -octaethylporphyrin
(OEP) gave OEP cation in the mass spectra, i.e. meso-
substituent elimination occurs in the ion source of mass
spectrometer with intermolecular hydrogen addition [23,39]. For
this reason P. Clezy concluded that it was impossible to study
of New Physicochemical Problems
n Institute of Physical chemistry and Electrochemistry
ky prospect, Moscow, 119071 Russia
@mail.ru
of Synthesis of Physiolological Active Compounds
iomedical Chemistry
inskaya street, 119121, Moscow, Russia
of Chemistry
osov Moscow State University
ie Gory, Moscow, 119991, Russia
ynchrotron Radiation Facility
8043 Grenoble Cedex, France
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
PER
ds by mass spectrometry due to their thermal Results and Discussion
udzikiewicz encountered a similar problem during
arge number of mass spectra of porphyrins and
suggested that the fragmentation was associated
earrangement processes, but didn’t support the
experimental investigations. The first substantial
mass spectra of the Schiff bases of meso-
s was held by G. Ponomarev[41]. He found that all
ed ions [M – NR]+ and [M - RNH2]+, and the
atter was maximal. Since it was hard to imagine
lar ion of the Schiff base disintegrated loosing
with the simultaneous transfer of two hydrogen
e porphyrin cycle to the amine nitrogen atom,
earrangements were suggested to occur in two
t stage of fragmentation was the intramolecular
of the molecular ion into cyclic compounds,
1. Preparation of azomethine derivatives of Pd(II) and Ni(II)
complexes of coproporphyrins
I
and II and -
octaethylporphyrin using electrophilic substitution reaction.
Azomethine derivatives of a number of metal porphyrins (Pd(II)
and Ni(II) complexes of tetraethyl ester of coproporphyrin I,
tetramethyl ester of coproporphyrin II, and -octaethylporphyrin)
were obtained by the reaction of amines (methylamine and
benzylamine) with the so called "phosphorus complexes". The
latter were obtained by the treatment of the metal porphyrin
complexes with the Vilsmeier reagent obtained in situ by the
interaction of N,N-dimethylformamide and phosphorus(V)
oxochloride.
Pd(II) and Ni(II) complexes of tetraethyl ester of coproporphyrin I,
tetramethyl ester of coproporphyrin II, and -octaethylporphyrin
to ions [M – NR]+ and [M - RNH2]+[23]
.
were prepared according to the procedure reported [44,45]
.
ves of etioporphyrin the presence of ions with
490 and 488 corresponding to [M – NR]+ and [M -
d the thermal decomposition of Schiff bases in
of the mass spectrometer with the formation of
s containing five-membered exocycle[23]. Thus,
led analysis of mass spectra of the Schiff bases,
of the transformation of meso-imino-substituted
yclopentaneporphyrins has been discovered. It is
rivatives of porphyrins and chlorins containing
yclic fragments possess unusual photophysical
Steric distortion of the tetrapyrrolic macrocycle
mation of additional exocycles leads to a change
Azomethine derivatives of Pd(II) and Ni(II) complexes of
tetraethyl ester of coproporphyrin I with methylamine, and
benzylamine (5-8), were synthesized as reported [33] (Scheme 1).
O
O
EtO
O
EtO
EtO
O
OEt
OEt
O
OEt
DMF/POCl3
N
N
N
N
N
N
N
N
N
N
NMe2
RNH2
O
M
M
M
O
N
R
O
C2H4Cl2
O
CH2Cl2
OPOCl2
N
N
EtO
EtO
EtO
(5) M = Pd, R = Me
6
(
) M = Pd, R = Bn
1
(
) M = Pd
3
(
) M = Pd
(4) M = Ni
OEt
7
(
) M = Ni, R = Me
OEt
OEt
O
O
O
(2) M = Ni
(8) M = Ni, R = Bn
Scheme 1. Preparation of azomethine derivatives of Pd(II) and Ni(II)
y
of the electron transition S0S1 and,
complexes of tetraethyl ester of coprroporphyrin
benzylamine.
I with methylamine and
o a bathochromic shift of the maximum of Q
s. Modification of porphyrins leading to their new
longer wave absorption would give us new
possessing useful properties for the application
ances for the treatment and diagnosis of cancer,
highly sensitive phosphorescent labels for
Reactions proceeded with high yields, formation of by-products
was negligible. However, in the case of the Ni(II) complex
interaction with the Vilsmeier reagent proceeded for 30 minutes
at 45 °C, in contrast to the palladium complex, for which the
similar reaction took 18 hours at 79 °C. The structure of the
compound (8) was studied by X-ray powder diffraction analysis
(XRPD) (Figure 1). In the complex (8) the Ni atom is located in
the plane of the molecular skeleton. The lengths of the Ni–N
bonds are: 2.037, 2.112, 1.946, 1.956 Å. The double C=N bond
has E-configuration and is orthogonal to the porphyrin core π-
system, which excludes π conjugation between them (Figure 1,
A).
The crystal packing of the compound (8) has a characteristic
feature manifested in short unit cell parameter (Figure 1, B). This
means that there must be strong interactions between the
molecules related by the translation along this parameter that
bind them into stacks. The distance between the root-mean-
square planes of porphyrin macrocycles in the stacks is 3.63 Å.
ned porphyrins were found in fossils and were
petroporphyrins (geoporphyrins, sedimentary
hey were derived from naturally occurring
insertion of the exocyclic ring to porphyrins was
umerous works, but multiple synthetic steps are
d. Among various petroporphyrins synthesis of
sed porphyrins proved to be mostly difficult[43]
.
the exocycles of the porphyrins are often
teric factors, as the peripheral substituents in the
ositions of the tetrapyrrolic compounds located
o each other. This fact allows not only to perform
ation reactions, but also to rearrange the
the periphery of the macrocycle. Thus, the
new methods of porphyrins modification would
new useful tetrapyrrolic compounds, thereby
panding their structural diversity, as well as to
r knowledge about the mechanisms of chemical
of the entire class of tetrapyrrole compounds.
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
FULL PAPER
Target Schiff bases have the similar polarity with the compound
(21), so their chromatographic separation was failed. For this
reason, isolation of azomethine derivatives (17), (18) and
compound (21) was based on the ability of Schiff bases to
interact reversibly with alkyl halides with the formation of
corresponding iminium salts. The latter were obtained by
addition of iodomethane to the mixtures of products (17) + (21)
and (18) + (21). The resulting salts were more polar relative to
the product (21), which didn’t form
a
salt, so the
chromatographic separation was easy. The reverse formation of
Schiff bases from their salts proceeded rapidly by the addition of
the corresponding amine in dichloromethane.
Formation of the product (21) resulted, apparently, via a number
of transformations occurred under the conditions of the
Vilsmeier-Haack reaction. The possible pathway of the formation
of this compound is shown at Scheme 4. The Vilsmeier reagent
is not only a formylating but also a chlorinating agent, therefore,
the chlorination of the ethyl group with the formation of a
monochlorinated derivative presumably took place at the first
stage. Following dehydrohalogenation led to formation of a vinyl
group, which was subjected to formylation in the next step
(Scheme 4).
gure 1. Molecular structure (A) and crystal packing (B) of the Schiff base (8)
stablished by XRPD.
sing similar procedures, azomethine derivatives of Pd(II) and
i(II) complexes of tetramethyl ester of coproporphyrin II with
[34,46]
ethylamine and benzylamine (11-14) were obtained
Scheme 2).
O
O
O
O
O
O
OMe
OMe
OMe
O
MeO
MeO
1.
DMF/POCl3
C2H4Cl2
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
M
M
M
RNH
2
Pd
2.
CH2Cl2
Pd
Pd
Pd
N R
N
N
N
N
Cl
N
O
(15)
(22)
(23)
(21)
R
OMe
MeO
OMe
OMe
) M = Pd, R = Me
O
eO
MeO
11
O
O
O
O O
(13) M = Pd, R = Me
(14) M = Ni, R = Bn
9
(
(
) M = Pd
) M = Ni
(12) M = Ni, R = Bn
10
(
Scheme 4. A possible pathway of formattion of the compound (21).
cheme 2. Preparation of azomethine derivatives of Pd(II) and Ni(II)
omplexes of tetramethyl ether of coproporphyrin II with methylamine and
enzylamine.
2. Synthesis of cyclopentane derivatives of β-
alkylporphyrins by thermolysis.
The reaction of intramolecular cyclization of azomethine
derivatives of porphyrins was first discovered by Ponomarev
during the study of mass spectra of azomethine derivatives of
porphyrins and chlorins. Later Ponomarev reproduced the
reaction in a laboratory synthesis at low pressure and high
temperature.[35,47] In the present work we investigated this
process and developed an optimized procedure for the
preparation of the cyclopentane fused porphyrin derivatives.
The thermolysis reaction was carried out for Pd(II) and Ni(II)
complexes of azomethine derivatives of tetraethyl ester of
coproporphyrin I (5, 7, 8). In heating at low pressure, a boiling
melt was formed, which solidified upon cooling. Formation of
target compounds was observed after 10 minutes. After 5
minutes the yield of the target products was maximal and the tar
was formed in insignificant amount.
Pd(II) complex gave yields: 13% of the cyclopentaneporphyrin
(24) and 19% of the lactam (26). In this case, the main part of
the reaction mixture was the initial azomethine derivative, which
could be isolated and re-used in the thermolysis reaction.
Cyclization products from the Pd(II) complex of azomethine
derivative of the tetraethyl ester of coproporphyrin I with
benzylamine weren’t formed during thermolysis under various
chiff bases of meso-formyl derivatives of the Pd(II) and Ni(II)
omplexes of -octaethylporphyrin with methylamine and
enzylamine (17-20) were obtained by the same procedure
Scheme 3). In the case of the Ni(II) complex, the target
roducts (19) and (20) were obtained. Pd(II) complex of -
ctaethylporphyrin complex gave byproduct (21) with 30% yield
addition to the target Schiff base [34]
.
1. POCl3
DMF
C2H4Cl2
N
N
N
N
N
N
N
N
N
N
N
N
R
N
M
M
+
Pd
2.
RNH2
CH2Cl2
O
21
( )
(15) M = Pd
(16) M = Ni
(17) M = Pd, R = Me
18
(
(
) M = Pd, R = Bn
) M = Ni, R = Me
19
(20) M = Ni, R = Bn
cheme 3. Preparation of azomethine derivatives of Pd(II) -
ctaethylporphyrin complexes with methylamine and benzylamine.
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
FULL PAPER
onditions. Absorption spectra of the reaction mixture contained
ands of chlorins, but isolation of the chlorins was failed.
he cyclopentaneporphyrin (25) with 17% yield and the cyclic
ctams (27), (28) with 32% and 30% yields respectively were
btained from the azomethine derivatives of Ni(II) complexes of
traethyl esters of coproporphyrin I (7) and (8) (Scheme 5). In
ddition to thermolysis products, the initial azomethine
erivatives and meso-methyl derivatives were found in the
eaction mixture in small amounts. Crystal structures of
ompounds (25) and (27) were determined by XRPD (Figure 2).
was shown that the root-mean-square planes of the lactam
ycle and the porphyrin ring in the compound (27) were inclined
each other at an angle of 73(1)o (Figure 2, B), while the
yclopentane fragment of the compound (25) lied in the plane of
e porphyrin ring (Figure 2, A).
possessing useful photophysical properties such as
bathochromically shifted UV-Vis absorption spectra.
O
O
O
O
OMe
OMe
MeO
MeO
N
N
N
N
N
vacuuum
250oC
R
M
M
N
N
N
N
OMe
OMe
MeO
MeO
O
O
O
O
29
30
(
(11) M = Pd, R = Me
12
(
) M = PPd
) M = NNi
(
) M = Ni, R = Bn
Scheme 6. Synthesis of the cyclopentaneporphyrins (29), (30).
O
O
O
OEt
OEt
OEt
3. Plausible mechanisms of the thermolysis reaction
We suggested two possible pathways of the formation of the
exocyclic porphyrins: ionic and radical. The ionic pathway is
shown on the example of compound (5) at Scheme 7.
EtO
O
O
EtO
O
N
N
N
N
N
N
N
N
N
N
R
N
N
N
R
N
vacuum
250 o
M
M
M
+
C
O
O
O
OEt
OEt
(26) M = Pd, RR = Me
(27) M = Ni, RR = Me
(5) M = Pd, R = Me
(7) M = Ni, R = Me
O
O
O
EtO
EtO
EtO
(24) M = Pd
(25) M = Ni
O
O
O
O
OEt
OEt
CCH
28
8
(
) M = Ni, RR = Bn
H
OEt
(
) M = Ni, R = Bn
CCH
OEt
H
C
N
N
N
N
N
N
N
N
N
N
O
C
H
N
Me ~H+
N
CCH
N
H
Pd
Pd
Pd
Me
N
Pd
Pd
C
H
NH
Me
-EtOH
Me
H
Me
cheme 5. Synthesis of cyclopentaneporphyrins (24-25), and lactams (26-28)
y thermolysis.
(5)
(31)
(32)
(26)
COOEt
COOEtt
COOEt
COOEt
COOEt
~H+
OEt
O
OEt
O
OEt
OEt
O
O
H
N
HHN Me
H
N
N
N
N
N
HH
Me
N
H
NH
Me
Pd
Pd
Pd
Pd
-CH3NH2
N
N
CCH2
CH2
CCH2
(33)
(34)
(35)
COOEt
COOEt
COOEt
COOEtt
[Pd]
CH3NH2
OEt
H
-
O
H
NH
H
N
N
NH
H
Pd
(24)
COOEt
Scheme 7. Plausible ionic mechanism off the thermolysis reaction.
The first stage involved the proton transfer from the -carbon of
the β-substituent to the nitrogen atom of the azomethine group
to form intermediates (31) and (33). The negatively charged -
carbon atom of the substituent at the β-position of the porphyrin
attacked the electrophilic carbon atom of the iminium group to
form the cyclopentane ring. Further development depends on
what type of the substituent was deprotonated. In the case of
deprotonation of the terminal methylene carbon of the ethyl
propanoate group leading to intermediate (31), after the
formation of the cyclopentane (33) newly formed amino group
interacted with the neighboring ester group with the formation of
the lactam cycle (26). If -methyl group had been deprotonated
forming the intermediate (33), then the cyclopentane
intermediate (34) was formed, which was unstable under the
reaction conditions and transformed to the product (24). This
process can proceed either as a reductive elimination of the
methyleneimine from the compound (34) or as a two-stage
gure 2. Molecular structures of cyclopentaneporphyrin (25) (A) and lactam
7) (B) determined by XRPD.
the case of the thermolysis of Pd(II) and Ni(II) complexes of
tramethyl ester of coproporphyrin II (11, 12), as expected, only
yclopentaneporphyrins (29, 30) (Scheme 6) were formed with
4% and 44% yields respectively. The conversion of Pd complex
1) was negligible and most of the reaction mixture was the
arting material. Pd(II) complexes of the methylamine and
enzylamine azomethine derivatives of -octaethylporphyrin (17,
8) couldn’t be thermolysed because they sublimated bypassing
e molten state.
vestigated thermolysis reactions provide the short and simple
ethod of the synthesis of 5-member ring fused porphyrins
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
PER
ng the elimination of the methylamine to form
hydrogen donors and the presence of benzylamine in higher
amount leads to the catalytic reduction of thermolysis products
to various chlorins to a larger extent compared to methylamine
derivatives.
In order to clarify the mechanism of the thermolysis
transformation quantum chemical calculations of the
intermediates were carried out by DFT methods. To simplify the
calculations, first we constructed a rough model compound 5-
((N-methylimino)methyl)-3,7-dimethylporphyrin A (Scheme 9).
quent catalytic hydrogenation of the double bond
(Scheme 7). The latter process is quite possible
action conditions. Catalytic hydrogenation of
amines as hydrogen donors was reported in
Nickel and palladium metals were able to be
ed due to some extent of destruction of metal
porphyrins at high temperature of reaction
ese metals are well-known hydrogenation
er yields of exocyclic porphyrin derivatives with
es can partially be explained by their lower
thermolysis compared to palladium complexes,
sequences of which is higher release of nickel
g the hydrogenation process. This hypothesis is
H
H
H
H
N
H
H
N
N
N
HN
N
HN
N
HN
N
N
22.2 kcal/mol
12.5 kcal/mol
N
NH
NH
NH
by the formation of
a number of other
C
A
B
byproducts including chlorins, which were
visible absorption spectra of the reaction mixture.
metals in the transformations was clearly
e fact that thermolysis of free base porphyrins
Scheme 9. Heterolytic vs. homolytic pathhways.
f
The geometries were optimized and the energies of the model
compound and primary intermediates of homo- and heterolytic
pathways of the reaction were calculated by the B3LYP/3-21G
method both in vacuum and in nitrobenzene solution at +250 °C.
The nitrobenzene was used to model the molten reaction
mixture as it fairly close in polarity to the investigated compound.
The key stage of the process was the hydrogen transfer from the
-carbon of the β-substituent to the nitrogen atom of the imino
group. The hydrogen can pass with or without electrons leading
to the biradical or betaine intermediate correspondingly. The
choice of the type was based on the relative energies of the
corresponding intermediates. The Gibbs free energy change of
the reaction A  B was 12.5 kcal/mol and that of A  C was
22.2 kcal/mol (Scheme 9). The betaine intermediate B was by
almost 10 kcal/mol lower in energy than the biradical C at both
+250 °C and standard conditions. The energy difference was
slightly less in vacuum compared to nitrobenzene solution.
Next we designed a closer model compound Ni(II) complex of 5-
((N-methylimino)methyl)-3-(2-(methyloxycarbonyl)ethyl)-7-
methylporphyrin D. The geometries and the energies of the
starting compound D, product I and all intermediates of the
reaction were calculated by the B3LYP/6-31G(d,p) method in
vacuum. Changes of Gibbs free energies for all suggested
stages of the thermolysis are given at Scheme 10. Betaine
intermediate is about 3 kcal/mol more stable compared to the
biradical. The energy difference between homolytic and
heterolytic pathways is less for the Ni complex model than the
free base model. The cyclization process from the starting
compound D to the intermediate G is energetically favored
(change of Gibbs free energy of the cyclization reaction amounts
to -6.6 kcal/mol). Subsequent methyleneimine loss is also
favorable (G = -1.6 kcal/mol). However, the direct elimination
is unlikely, instead at high temperature the endothermic
methylamine elimination (5.5 kcal/mol) can occur and
subsequent exothermic hydrogenation (-7.1 kcal/mol) provides
overall energetic profit.
OEt
O
OEt
O
O
H
N
H
OEt
N
N
H
N
N
N
N
N
N
O
C
H
~H
N
N
Pd
Pd
Pd
NH
Me
Me
-EtOH
Me
Me
H
H
CH3
CH3
(36)
OEt
(37)
(32)
(26)
COOEt
COOEt
COOEt
COOOEt
~H
OEt
O
OEt
O
O
H
N
N
H
N
H
C
N
NH
Me
Pd
Pd
Me
-CH3NH2
N
N
N
CH2
CH2
(38)
(35)
(34)
COOEt
COOEEt
COOEt
[Pd]
CH3NHH2
OEt
H
-
O
H
NH
H
N
NH
H
Pd
N
(24)
COOEt
e radical mechanism of the thermolysis reaction.
he radical mechanism, a homolytic break of the
ine C=N bond of the compound (5) occurs under
mperature leading to formation of the biradical
8). Then, the nitrogen atom takes the hydrogen
-carbon of the β-substituent to form more stable
cals (37) and (38). Subsequent intramolecular
f radicals leads to the formation of cyclopentane
ransformations proceed as in the previously
scheme (Scheme 7). Both mechanisms can
mation of chlorins in the thermolysis reaction of
lex of the benzylamine azomethine derivative of
ether of coproporphyrin I. The benzylamine
significantly heavier than methylamine, and
ss volatile and is removed from the reaction
slower and to a lesser extent. Amines are
Thus the quantum chemical calculations supported the
suggested mechanism of the transformation observed at
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
PER
e calculations revealed that at first stage the
CHH
was slightly more favorable than the homolytic
rogen atom. Expected larger difference in the
CH2
N
HC
N
N
N
N
N
H+
B
-BH+
Pd
Pd
Pd
e
corresponding transition states supported
Me
NN Me
N
Me
N
of the heterolytic pathway, although some part of
uld proceed by the homolytic pathway as the
ce wasn’t significant taking into account relatively
e +250 °C.
(17)
(39)
(40)
H
HC
H
H
N
N
N
N
N
N
N
N
N
N
N
N
N
N
25.7 kcal/mol
28.6 kcal/mol
N
Pd
Pd
Pd
Ni
D
Ni
F
-NH2Me
O
O
HN Me
N
O
l
o
m
O
/
l
a
c
k
l
2
.
5
(41)
(422)
(43)
3
-
Scheme 11. Suggested mechanism of interaction of bases (B) with
azomethine derivatives of palladium commplex of -octaethylporphyrin.
N
N
N
N
N
N
5.5 kcal/mol
-CH3NH2
Ni
N
H
O
O
O
H
O
CH3NH2
[Ni]
CH2NH
-7.1 kcal/mol
Experiments were carried out with different bases: t-BuOK, t-
BuOLi, Bu4NOH, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).
DMF and 1,4-dioxane were used as solvents. The reaction was
carried out by heating to 100 oC for a one minute, then
neutralization of the base and isolation of the products were
immediately carried out. The reaction didn’t proceed with t-
BuOLi and DBU due to their low basicity and t-BuOK and
Bu4NOH worked well.
-1.6 kcal/mol
-CH2NH
N
N
N
N
Ni
O
O
I
me of the transformations suggested at thermolysis.
Two products were formed after the interaction of Pd (II)
complexes of azomethine derivatives of OEP, regardless of the
substituents at the nitrogen atom (methylamine or benzylamine)
(Scheme 12).
of azomethine derivatives of porphyrins with
ionic type of the mechanism of the thermolysis
mpted to synthesize cyclization products through
of azomethine derivatives with various bases.
rivatives of Pd(II) and Ni(II) complexes of -
rin with methylamine and benzylamine were
compounds.
N
N
N
N
N
N
N
N
N
N
N
N
N
R
tBuOK
100 o
DMF
N
OH
+
Pd
PPd
Pd
C
that the strong base would abstract the proton
rbon of the β-alkyl group (39). Then the
banion would attack electrophilic carbon atom of
(17) R = Me
(18) R = Bn
(444)
(45)
e
fragment to form a cyclopentane ring.
Scheme 12. Interaction of Pd(II) compplexes of azomethine derivatives (17)
and (18) with a strong base.
tonation of the nitrogen anion would lead to the
Further elimination of methylamine would lead
ene derivative which would transform to the less
hylene cyclopentane (Scheme 11).
The structure of the compound (45) was determined by the
XRPD and also confirmed using IR, UV-Vis spectroscopy, and
MALDI-TOF mass spectrometry. Almost all non-hydrogen atoms
of the compound (45), excluding methyl atoms, lie in the same
plane (Figure 3). Due to the extremely low solubility of the
compound (45) in all available deuterated solvents, its NMR
spectrum could not be obtained. In this regard, it was decided to
repeat the experiments with Ni complexes, as they have greater
solubility in most cases.
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
FULL PAPER
(20) led to the compound (50) with an unsubstituted amide
group at meso-position (Scheme 15).
N
N
N
N
N
N
N
N
OH
Ni
N
Ni
N
N
N
N
(47)
N
tBuOK
DMF
(46)
+
Ni
gure 3. The molecular structure of the compound (45) determined by XRPD.
N
N
N
N
NH2
20
(
)
Ni
he interaction of Ni(II) complex (19) with t-BuOK, as well as in
e case of Pd(II) complex, resulted in two expected products
46) and (47). A peculiarity of the interaction of the Ni complex
9) with the base was the formation of a third reaction product -
olar porphyrin with an amide substituent (48) (Scheme 13).
O
(50)
Scheme 15. Treatment of the benzylamine azomethine derivative of the Ni(II)
complex -octaethylporphyrin (48) with aa strong base.
In order to prove the participation of air oxygen in the reactions
of azomethine porphyrin derivatives with strong bases, all
reactions were reproduced in dry oxygen free solvents in the
argon atmosphere. As a result, nitriles (44), (46) were obtained
as main products and the initial meso-unsubstituted Pd(II) and
Ni(II) complexes in small amounts (Scheme 16). Thus, the
compounds (45), (49), (48) and (50) were the products of the
interaction with air oxygen.
N
N
N
N
N
N
N
N
N
OH
Ni
Ni
N
N
N
N
Me
N
tBuOK
DMF
46
(
)
(47)
Ni
N
N
N
N
Me
HN
O
(19)
Ni
48
(
)
cheme 13. Interaction of the Ni (II) complex of azomethine derivative of -
ctaethylporphyrin with methylamine (44) with a strong base.
N
N
N
N
NN
NN
N
N
N
N
N
N
RR
N
tBuOK
DMF
N
+
M
M
M
ompound (48) was characterized with UV-Vis, NMR
pectroscopy and MALDI-TOF mass spectrometry. The solubility
f the compound (47) was slightly increased compared to (45),
ut still insufficient to obtain solution NMR spectrum.
(17) M = Pd, R = Me
(18) M = Pd, R = Bn
(19) M = Ni, R = Me
(20) M = Ni, R = Bn
(444) M = Pd
(466) M = Ni
(15) M = Pd
(16) M = Ni
fter determination of the structure of amide (48), it became
ear that the reaction involved not only the base, but also
robably air oxygen, causing formation of the oxidation products.
was suggested that the first step was formation of oxaziridine
ycle, which rearranged to the amide (48) by a radical reaction
ith participation of oxygen (Scheme 14).
Scheme 16. Interaction of -octaethylpoorphyrin azomethine derivatives with a
strong base in dry DMF in an inert atmossphere.
NH HN
HN
N
N
N
N
H2SO4
TFA
O
OH
Ni
N
47
)
51
( )
(
O2
N
N
N
N
N
N
N
N
N
N
N
N
O
N
Me
tBuOK
O
Ni
Ni
Ni
DMF
N
Me
HN Me
Scheme 17. Demetalation of the Ni compplex of meso-hydroxyporphyrin (47).
(49)
(19)
(48)
cheme 14. A possible pathway of formation of the compound (48).
Complexes of meso-hydroxyporphyrins (45) and (47) were
demetalated with sulfuric acid (Scheme 17). The Pd complex
(45) was partially destroyed and nothing was isolated. The less
stable Ni complex (47) was easily demetalated with a solution of
contrast to the methylamine derivative (19), treatment of the
enzylamine azomethine derivative of the Ni(II) complex of OEP
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
FULL PAPER
ulfuric acid in trifluoroacetic acid, resulting in formation of Experimental Details
eso-oxophlorin (51) with a quantitative yield.
General Methods. 1Н and 13С NMR spectra were recorded with a Bruker
Avance III 600 MHz spectrometer at room temperature. Chemical shifts
are reported relative to signals of residual protons of solvents ([D6]DMSO
– 2.50 ppm, CDCl3 – 7.26 ppm). Mass spectra were recorded with
UltrafleXtreme mass spectrometer (Bruker Daltonics) in a positive-ion
mode using reflection mode with 20 MV voltage without matrix. Electronic
absorption spectra were recorded with U-2900 (Hitachi) and UV-4
(Unicam) spectrophotometers in quartz rectangular cells of 10 mm path
length.
V-Vis absorption spectra of all the meso-hydroxyporphyrin
erivatives are markedly different (Figure 4). Spectra of (45) and
47) are typical for the metal complexes of meso-
ydroxyporphyrins: two Q bands are observed at the region 500-
00 nm. After removing the metal, a dramatic bathochromic shift
f absorption bands occurred to the long-wave region by 94 nm
hich was a consequence of the tautomerization from the
orphyrin to the phlorin with highly disturbed electron structure.
hus a novel robust method of the meso-functionalization of
orphyrins was developed leading to the corresponding cyano,
mido and hydroxy substituted porphyrins. The meso-
nctionalization expectedly resulted in the red shift of the UV-
X-ray diffraction study. Single crystals of the compounds (8), (25), (27)
и
(45) were failed to be grown and there were obtained their
polycrystalline samples suitable for the determination of crystal structures
by X-ray powder diffraction analysis (XRPD)[50–54]. All powder diffraction
measurements were carried out at the ID22 high-resolution station at the
European synchrotron radiation facility ESRF (Grenoble, France) at 250
s
absorption spectra[49] which could be useful for the
hotosensitizing applications.
K. The station is equipped with
a cooled dual silicon Si 111
monochromator and Si 111 analyzer[[55]. The powder was poured into a
thin-walled borosilicate capillary with a diameter of 1 mm, which during
the measurements was rotated at a speed of 1200 rpm to achieve better
counting statistics. Calibration of the goniometer and refinement of the X-
ray wavelength were performed on a standard silicon sample NIST Si
640c. Indexing was performed using the programs TREOR90[56], ITO[57]
and AUTOX[58]. Preliminary refinement by Pawley method[59] confirmed
the correctness of the unit cell dimensions and space groups. The crystal
structures were solved by simulated annealing technique[60] following the
methodology described by us earlier[661,62]. The solutions found were then
refined by the Rietveld method with the MRIA program[63], the peak
profiles were described by the modified Voight function[64]
. The
contribution of the texture effect was taken into account by the March-
Dollase approach[65]. The anisotropy of the broadening of the diffraction
peaks were estimated by the N. Popa model[66]. In the process of
refinement, restrictions were imposed on the permissible deviations of
interatomic distances in the molecule and on the planarity of individual
fragments of the molecule as described in[61,62]. After several cycles of
refinement, maps of the differential electron density were analyzed, and if
free-standing maxima were found, then an oxygen atom was placed in
this position, for which, along with the coordinates, the occupancy factor
was refined to find possible residues of solvent molecules. After finding
all non-hydrogen atoms and specifyiing their positions, the positions of
hydrogen atoms were calculated, in which they were placed and were not
further refined. The crystal data, data collection and refinement
parameters for (8), (25), (27) и (45) are given in Table 1. The geometric
parameters of all molecules have normal values comparable to those
found in the Cambridge Structural Database [67] for related compounds. In
non-symmetrical complexes (25), (27) и (45) the M(II) cation (M = Ni, Pd) is
situated on the center of pseudo symmetry, as was recently observed in
the single-crystal structure of Pd(II) complex of 2,3,7,8,12,13,17,18-
gure 4. UV-Vis absorption spectra of meso-hydroxyporphyrins (45), (47),
1) in dichloromethane.
Conclusions
he new types of the porphyrin transformation and
nctionalization were developed which open up simple
ossibilities for obtaining easily accessible diverse porphyrin
erivatives. Cyclopentane fused porphyrins were obtained
rough the heating iminoporphyrins. Transformations of the
eso-iminoporphyrins to the corresponding cyano, amido and
ydroxy derivatives have been discovered using interaction with
ases. The useful outcome of such functionalization is the
nger wave absorption. Such porphyrins with the absorption
aximum being around 700 nm are promising candidates to use
s photosensitizers in medicine applications (photodynamic
erapy etc). Now applied longer wave absorption dyes are
sually chlorins. They are not as stable as porphyrins and easily
usceptible to oxidation. Therefore, the easy access to the
able porphyrins with photosensitizer ability comparable to
hlorins is hard to overestimate.
octaethyl-5-((methylimino)methyl) porphyrin[46]
. The locations of some
fragments in the molecules in the crystal structures (25) (cyclopentane)
and (27) (lactam and etoxycarbonylethyl) are disordered with equal
occupancies (0.5/0.5) over two positions related by crystallographic
center of symmetry, thus, showing once again that disorder is an
essential feature that greatly affects the formation of the crystal[68,69]
.
Slightly more complex nature of disorder in (45), where hydroxy oxygen
is also disordered over two independent positions with occupancies
refined to 0.359(17) and 0.141(17), respectively, leads to the crystal
packing close to that in triclinic B polymorph of 2,3,7,8,12,13,17,18-
octaethylporphinato-nickel(ii)[70]
.
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
phic data for compounds (8), (25), (27) and (45).
(8)
(25)
(27)
(45)
C52H60N5NiO8
•CH4O C45H52N4NiO8
C44H49N5NiO7
C36H44N4OPd
973.80
Triclinic
P1
835.62
818.59
655.18
Triclinic
P-1
Monoclinic
P21/c
Monoclinic
P21/c
14.9403(12)
17.8956(15)
4.8834(7)
95.387(11)
94.915(13)
76.879(9)
1263.2(4)
1
4.8770(7)
30.2813(19)
14.2376(11)
90
15.2160(11)
4.8716(8)
26.8336(18)
90
13.3198(12)
13.4374(12)
4.7959(8)
91.921(14)
93.592(12)
113.199(17)
785.84(16)
1
98.944(8)
90
101.918(15)
90
2077.1(4)
2
1946.2(4)
2
ID22, ESRF
0.399996(4)
ID22, ESRF
0.399996(4)
ID22, ESRF
0.399996(4)
ID22, ESRF
0.399962(4)
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
1.280
0.087
1.336
0.103
1.397
0.109
1.384
0.123
0.501 – 20.001, 0.003 0.501 – 20.001, 0.003 0.999 – 20.001, 0.003 1.500 – 20.000, 0.002
rs / 258/193 153/105 167/132 151/97
0.0363/0.0522/0.0125 0.0317/0.0415/0.0182 0.0387/0.0505/0.0179 0.0354/0.0483/0.0190
4.177
2.285
2.817
2.536
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
PER
cal calculations
([M+H]+) 665.2472; UV-Vis (CH2Cl2), λmax, nm (Arel.): 415 (1.00), 517
al calculations of geometry and electronic structure
(0.07), 539 (0.09), 557 (0.09), 578 (0.28).
the framework of the density functional theory (DFT)
culations used the hybrid functional B3LYP with the
e functional[71] and the correlation functional of Lee,
For all atoms, a full-electron basis sets 3-21G and 6-
ddition of polarization d, f-orbitals, and p-orbitals for
were used. The geometry of all studied molecules was
he absence of imaginary frequencies confirmed their
er. The software package Gaussian 03 was used for
After the procedure of optimization of geometrical
function stability tests were carried out then calculation
cal parameters was performed. Calculations in
tion were carried out by the same methods using the
um (PCM) model. The energies of the calculated
corrected for zero vibrational energy (ZPVE) and with
ns to enthalpy and free energy were calculated at the
s (523.15 K, 1 atm.)
Pd(II) сomplex of 5-(N-benzyliminomethyl)-2,3,7,8,12,13,17,18-
octaethylporphyrin (18): was obtained by the same procedure as for
compound (17) but with benzylamine. Yield of (18) was 35.9 mg (61%).
NMR 1Н (600 MHz, CDCl3), δ, ppm: 1.59 (6H, t, CH2-CH3), 1.88 (6H, t,
CH2-CH3)1.91-1.94 (12Н, m, CH2-CH33), 3.46 (2Н, s, CH2Bn), 3.74 (4Н, q,
CH2-CH3), 4.01-4.05 (12Н, m, CH2-CH3), 7.36-7.39 (1Н, m, C part of
AA′BB′C spin system of Ph), 7.44-7.47 (2Н, m, BB′ part of AA′BB′C spin
system of Ph), 7.65-7.67 (2Н, m, AA′ part of AA′BB′C spin system of Ph),
10.02 (1H, s, meso-Н), 10.06 (2H, s, meso-Н), 10.99-11.0 (1Н, broad m,
СН=NBn). HRMS, m/z: 756.3267. Calcd. for С44H52N5Pd ([M+H]+)
756,3258. UV-Vis (CH2Cl2), λmax, nm (Arel.): 399 (1.00), 521 (0.03), 553
(0.13).
Ni(II) сomplex of 5-(N-methyliminomethyl)-2,3,7,8,12,13,17,18-
octaethylporphyrin (19) was obtained by the same procedure as for
compound (17). Yield of (19) was 43.6 mg (82%): NMR 1Н (600 MHz,
CDCl3), δ, ppm: 1.61 (3H, t, CH2-CH3), 1.77-1.84 (18H, m, CH2-CH3),
3.70 (4H, q, CH2-CH3), 3.84 (3H, d, СН=N-CH3), 3.85-3.89 (12H, m, CH2-
CH3) , 9.541 (1H, s, meso-H), 9.543 (2H, s, meso-H), 10,77 (1H, d,
СН=NCH3). MS (MALDI-TOF), m/z: 632,5369. Calcd. for С38H47N5Ni
([M+H]+) 633,5282. UV-Vis (CH2Cl2), λmax, nm (log ε): 401 (1,00), 530
(0,05), 565 (0,09).
ures
, (5-8), (9-10), (11-14) were synthesized according to
es [33,34,46]. Compounds (15), (16) were obtained from
ces. Products (25), (27), (28), (30), (51) had NMR
ent with published data [23,35,47,74]
.
methines: The Vilsmeier reagent, in situ formed from 1
POCl3 and 1 ml (0.013 mol) of DMF, was added to a
(0.078 mmol) of Pd(II) complex of -octaethylporphyrin
dry 1,2-dichloroethane at 76 oC. The resulting mixture
hours at the same temperature and the reaction was
with the eluent CH2Cl2/EtOH 100:4. After the reaction
olvent was evaporated in vacuum and 25 ml of distilled
to the residue. The organic phase was extracted with
and dried over anhydrous sodium sulphate. After
poration of the solvent, the residue was dissolved in
(30 ml) and methylamine (5 ml of 33% solution in
ed to the solution at room temperature. The reaction
y TLC with the eluent CH2Cl2/EtOH 100:1. After the
Ni(II) сomplex of 5-(N-benzyliminomethyl)-2,3,7,8,12,13,17,18-
octaethylporphyrin (20): was obtained by the same procedure as for
compound (17) but with benzylamine. Yield of (20) was 48.2 mg (81%).
NMR 1Н (600 MHz, CDCl3), δ, ppm: 1.60 (6H, t, CH2-CH3), 1.77 (6H, t,
CH2-CH3), 1.80-1.85 (12Н, m, CH2-CH3), 3.6 (4Н, q, CH2-CH3), 3.84-3.90
(12Н, m, CH2-CH3), 4.18 (2Н, s, CH2Bn), 7.29-7.31 (1Н, m, C part of
AA′BB′C spin system of Ph), 7.35-7.37 (2Н, m, BB′ part of AA′BB′C spin
system of Ph), 7.42-7.44 (2Н, m, AA′ part of AA′BB′C spin system of Ph),
9.53 (3H, s, meso-Н), 10.78 (1Н, s, СН=NBn). HRMS, m/z: 708.2335.
Calcd. for С44H52N5Ni ([M+H]+) 709.2167. UV-Vis (CH2Cl2), λmax, nm
(Arel.): 401(1.00), 531 (0.04), 576 (0.08).
on,
a
mixture of azomethine derivative (17) and
Thermolysis procedure: Azomethine derivative of complexes (5), (11)
or (12) (0.25 mmol) was heated at 250 °C in vacuum (0.05 mm Hg) for 3
minutes. The products were isolated by preparative TLC with eluents
CH2Cl2/EtOH 100:1 and 100:4.
as isolated by flash chromatography in dichloromethane.
roducts, 5 ml of methyl iodide was added to the mixture
solution was heated at 40 oC for 5 hours until complete
the Schiff base (17) to the salt (TLC monitoring). After
was evaporated in vacuum, and the compound (21) was
chromatography in dichloromethane, then the Schiff
shed off the silica with ethanol. Ethanol was evaporated
esidue was dissolved in dichloromethane (10 ml) and
ml of 33% solution in ethanol) was added. After 1 hour
on was washed with an aqueous solution of citric acid to
ss amine, dried with Na2SO4 and evaporated in vacuum
6%) of the product (17).
Compound (24): Thermolysis of (5) yielded yielded 29 mg (13%) of (24).
NMR 1Н (600 MHz, CDCl3), δ, ppm: 1.23-1.26 (6Н, m, СН2-СН3), 1.31-
1.34 (6Н, m, СН2-СН3), 2.80 (2Н, t, СН2), 3.02 (2Н, m, СН2), 3.22 (6Н,
m, β-CH2, CH2), 3.39 (3H, s, β-СН3), 3.47 (3H, s, β-СН3), 3.52 (3H, s, β-
СН3), 3.79 (2H, m, CH2), 3.86 (2H, m, CH2), 4.05 (t, 171-СН2), 4.26-4.29
(12Н, m, СН2), 4.33 (2H, m, 151-СН2), 9.37 (1Н, s, meso-Н), 9.62 (1Н, s,
meso-Н), 9.71, (1Н, s, meso-Н). HRMS, m/z: 884.2904. Calcd. for
С45H53N4O8Pd: ([M+H]+) 883.2898. UV-Vis (CH2Cl2), λmax, nm (Arel.): 396
(1.00), 517 (0.07), 548 (0.17).
of 5-(N-methyliminomethyl)-2,3,7,8,12,13,17,18-
rin (17): NMR 1Н (600 MHz, CDCl3), δ, ppm: 1.90-1.95
3), 4.04-4.08 (19H, m, CH2-CH3 and СН=N-CH3), 10.06
10.09 (2H, s, meso-H), 10,94 (1H, d, СН=NCH3). MS
z: 680.3. Calcd. for С38H48N5Pd ([M+H]+) 680,295. UV-
nm (log ε): 397 (5.03), 515 (3.94), 550 (4.30).
Compound (26): Thermolisys of (5) yielded yielded 40 mg (19%) of (26).
NMR 1Н (600 MHz, CDCl3), δ, ppm: 1.17-1.26 (9H, m, СН2-СН3), 2.62
(3H, s, NСН3), 3.19-3.16 (6H, m, СН2-СН3), 3.29-3.42 (2H, m, CH2-
lactam cycle), 3.32 (3H, s, β-СН3), 3.42 (3H, s, β-СН3), 3.44 (3H, s, β-
СН3), 3.53 (3H, s, β-СН3), 4.17-4.32 (12H, m, СН2СН2СО), 4.78 (1H, m,
СН), 7.13 (1H, d, CH), 9.70 (1Н, s, meso-Н), 9.71 (1Н, s, meso-Н), 9.76
(1Н, s, meso-Н). HRMS, m/z: 866.2737. Calcd. for С44H50N5O7Pd
([M+H]+) 866.2745. UV-Vis (CH2Cl2), λmax, nm (Arel.): 395 (1.00), 519
(0.05), 549 (0.17).
ex
of
2-(3-oxo-1-propenyl)-3,7,8,12,13,17,18-
yrin (21): NMR 1Н (600 MHz, CDCl3), δ, ppm: 1.88-
2-CH3), 4.05-3.92 (16Н, m, CH2-CH3), 7.37-7.33 (1Н, dd,
4 (1Н, d, β-СН), 9.92 (1H, s, meso-Н), 9.98 (1H, s,
H, s, meso-Н), 10.02 (1H, s, meso-Н) 10.17 (1Н, d,
LDI-TOF), m/z: 665.2479. Calcd. for С37H43N4OPd
Compound (29): Thermolisys of (11) yielded 29 mg (14%) of (29).
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10.1002/ejoc.201801659
European Journal of Organic Chemistry
PER
NMR 1Н (600 MHz, CDCl3), δ, ppm: 1.64 (6H, t, CH2-CH3), 1.79-1.82
(18H, m, CH2-CH3), 3.86-3.93 (16Н, m, CH2-CH3), 5.76 (1Н, bs, NH),
6.36 (1Н, bs, NH), 9.58 (1H, s, meso-Н), 9.63 (2H, s, meso-H).
HRMS, m/z: 635.3069. Calcd. for С37H46N5NiO ([M+H]+) 634.3056.
UV-Vis (CH2Cl2), λmax, nm (Arel.): 394 (1.00), 519 (0.05), 553 (0.13).
z, CDCl3), δ, ppm: 3.11 (7H, s, CH2, β-СН3), 3.21-3.24
8 (2H, m, 131-СН2), 3.53 (6H, s, β-СН3), 3.70 (3H, s,
s, ОCH3), 3.74 (3H, s, ОCH3), 3.79 (3H, s, ОCH3), 3.97
(2H, m, СН2), 4.23-4.26 (4Н, m, СН2), 4.56 (2H, m,
Н, s, meso-H), 9.66 (1Н, s, meso-H), 9.79, (1Н, s,
m/z: 827.2264. Calcd. for С41H45N4O8Pd ([M+H]+)
(CH2Cl2), λmax, nm (Arel.): 397 (1.00), 514 (0.06), 549
5-oxo-2,3,7,8,12,13,17,18-octaethylphlorin (51): A solution of 38 mg
(0.063 mmol) of Ni (II) complex of 5-hydroxy-2,3,7,8,12,13,17,18-
octaethylporphyrin (47) in a mixture of trifluoroacetic acid (10 ml) and
concentrated sulfuric acid (1 ml) was stirred at room temperature for 2
minutes, then 50 ml of cold water was added. The resulting mixture was
extracted with dichloroethane (3 x 50 ml). The organic fraction was
evaporated in vacuum. The product was isolated using a preparative TLC
with the eluent CH2Cl2/EtOH 100:1 yielding 29.8 mg (86%) of (51).
HRMS, m/z: 551.3766. Calcd. for С36H47N4O: ([M+H]+) 551.3750. UV-Vis
(CH2Cl2), λmax, nm (Arel.): 407 (1.00), 550 (0.03) 598 (0.05), 652 (0.10),
705 (0.18).
Thermolisys of (12) yielded 26 mg (18%) of (30).
z, CDCl3), δ, ppm: 9.75 (1Н, s, meso-Н), 9.74 (1Н, s,
Н, s, meso-Н), 4.90 (2H, m, 101-CH2), 4.27-4.15 (8H, m,
2H, t, 121-CH2), 3.78 (3H, s, CH3), 3.73 (3H, s, CH3),
3.70 (3H, s, OCH3), 3.51 (3H, s, OCH3), 3.50 (3H, s,
s, OCH3), 3.26-3.13 (8H, m, СН2СН2СО). HRMS, m/z:
for С41H45N4O8Ni ([M+H]+) 779.2591.
omethine derivatives of porphyrins with bases: A
mg (0.04 mmol) of Pd(II) complex of 5-(N-
l)-2,3,7,8,12,13,17,18-octaethylporphyrin (18) in 10 ml
to 100 oC and 124 mg (1.1 mmol) of potassium tert-
d. The reaction mixture was stirred for 5 seconds, then
stopped and 25 ml of cold water was added to the
ting mixture was extracted with dichloroethane (3 x 50
fraction was dried over Na2SO4 and evaporated in
roducts were isolated with preparative TLC in
yielding 13 mg (49%) of Pd(II) complex of 5-cyano-
8-octaethylporphyrin (44) and 8.9 mg (34%) of Pd(II)
-hydroxy-2,3,7,8,12,13,17,18-octaethylporphyrin (45).
(47), (48) were obtained from the corresponding Ni(II)
20) by the same procedure as for 44, 45.
of 5-cyano-2,3,7,8,12,13,17,18-octaethylporphyrin
0 MHz, CDCl3), δ, ppm: 1.86 (16Н, t, CH2-CH3), 1.93
3.91-4.00 (12Н, m, CH2-CH3), 4.30 (4Н, m, CH2-CH3),
so-Н), 9.90 (2H, s, meso-Н). HRMS, m/z: 664.2629.
N5Pd: ([M+H]+) 664.2632. UV-Vis (CH2Cl2), λmax, nm
544 (0.05), 575 (0.21).
of 5-hydroxy-2,3,7,8,12,13,17,18-octaethylporphyrin
655.2637. Calcd. for С36H45N4OPd ([M+H]+) 655.2628.
λmax, nm (Arel.):403 (1.00), 517 (0.09), 550 (0.07).
of 5-cyano-2,3,7,8,12,13,17,18-octaethylporphyrin
00 MHz, CDCl3), δ, ppm: 1.80 (16Н, t, CH2-CH3), 1.87
3.82-3.89 (12Н, m, CH2-CH3), 4.19 (4Н, q, CH2-CH3),
so-H), 9.57 (2H, s, meso-H). HRMS, m/z: 616.2961.
N5Ni ([M+H]+) 616.2950. UV-Vis (CH2Cl2), λmax, nm
540 (0.05), 589 (0.7).
of 5-hydroxy-2,3,7,8,12,13,17,18-octaethylporphyrin
607.2935. Calcd. for С36H45N4ONi ([M+H]+) 607.2947.
λmax, nm (Arel.): 413 (1.00), 564 (0.03), 616 (0.02).
of 5-(N-methylaminocarbonyl)-2,3,7,8,12,13,17,18-
rin (48): NMR 1Н (600 MHz, CDCl3), δ, ppm: 1.80-1.82
3), 3.30 (3Н, d, NCH3), 3.86-3.90 (16Н, m, CH2-CH3),
, 9.60 (1H, s, meso-H), 9.64 (2H, s, meso-H). HRMS,
Calcd. for С38H48N5NiO ([M+H]+) 648.3212. UV-Vis
(Arel.): 395 (0.89), 549 (0.06), 556 (0.11).
ex
of
5-(aminocarbonyl)-2,3,7,8,12,13,17,18-
rin (50).
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201801659
European Journal of Organic Chemistry
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