Russian Chemical Bulletin, International Edition, Vol. 66, No.11, pp. 2131—2135, November, 2017 2131
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2131—2135, November, 2017.
10665285/17/66112131 © 2017 Springer Science+Business Media, Inc.
Asymmetrically substituted tetra(mesoaryl)porphyrins bearing
peripheral 2,6diisobornylphenol and 2,6ditertbutylphenol moieties
D. V. Belykh,
T. K. Rocheva, E. V. Buravlev, I. Yu. Chukicheva, and A. V. Kutchin
Institute of Chemistry, Komi Scientific Center, Ural Branch of the Russian Academy of Sciences,
48 ul. Pervomaiskaya, 167982 Syktyvkar, Russian Federation.
Fax: +7 (821) 221 8477. Email: firstname.lastname@example.org
Asymmetrically substituted tetra(mesoaryl)porphyrins bearing peripheral diisobornyl
phenol and ditertbutylphenol moieties were synthesized by a mixed aldehyde condensation.
Key words: mixed aldehyde condensation, tetra(mesoaryl)porphyrins, 2,6diisobornyl
4methylphenol, 2,6ditertbutylphenol, hybrid antioxidants.
It is known that antioxidant activity of synthetic phe
nolic compounds often exceeds those of natural antioxi
It has been found that phenolic compounds re
duce the rate of lipid and protein peroxidation and are
promising candidates for treatment of free radicalinduced
They show antihypoxic, hemorheological,
and other important biological activities.
antioxidant activity (AOA) of 2,6ditertbutyl4meth
ylphenol and 2,6diisobornyl4methylphenol is attrib
utable to the presence in their structures of the bulky
substituents positioned ortho with respect to the hydroxy
Lipophilic porphyrin free bases and their metal
complexes are capable of incorporating into the lipid bi
layer of the cell membranes
and inactivating the free
These properties form the basis for the use of
porphyrin scaffolds in treatment of the diseases mediated
by oxidative stress and make the studies in this field very
Introduction of the fragments of the mole
cules having their own AOA into the porphyrin periphery
noticeably affects the antioxidant activity of these conju
gates. Thus, it has been found earlier
metrically substituted tetra(mesoaryl)porphyrins bearing
peripheral diisobornylphenol and ditertbutylphenol
moieties possess antioxidant and antiradical activities.
Moreover, porphyrin macrocycle is able to modify the
overall biological activity of the molecule not only by
changing the reactivity of the phenolic moiety but also by
changing the body distribution of the antioxidant.
It is interesting to vary the number of terpenephenolic
substituents appended to the porphyrin framework be
cause it gives possibility to examine the impact of these
fragments into overall AOA of the compound. Conse
quently, the synthesis of asymmetrically substituted por
phyrins bearing different number of terpenephenolic sub
stituents is actual. In the present work, we studied a mixed
aldehyde condensation of either 4hydroxy3,5di(1,7,7
trimethylbicyclo[2.2.1]heptexo2yl)benzaldehyde (1) or
3,5ditertbutyl4hydroxybenzaldehyde (2) with benz
aldehyde (3) (4methoxybenzaldehyde (8)) and pyrrole
to synthesize asymmetrically substituted tetra(meso
aryl)porphyrins bearing one diisobornylphenol or ditert
butylphenol group (Scheme 1 and 2).
Results and Discussion
It is known
that a mixed aldehyde condensation of
pyrrole and two different aldehydes gives, in principal,
a set of six porphyrins. By using the excess of one of
aldehyde, the significant simplification of the reaction
mixture is possible. In this case, two porphyrins are pre
dominantly formed, i.e., a symmetrically substituted por
phyrin derived from the excess aldehyde and an asym
metrically substituted porphyrin bearing one substituent
derived from the limiting aldehyde. In most cases, the
separation of the mixture of formed porphyrins could be
accomplished. Thus, mixed aldehyde condensation is an
expedient approach to achieve our goals.
Condensation of pyrrole, aldehyde 1, and fourfold
excess of benzaldehyde 3 (with respect to aldehyde 1)
affords a mixture of porphyrins 4—7 (Scheme 1). Un
fortunately, we failed to separate this mixture due to close
polarity of the formed porphyrins.
Thin layer chromatography indicates that the reac
tion produces a mixture of four porphyrins. The compo
sition of the mixture was examined by electrospray ion
ization mass spectrometry,
H NMR spectroscopy, and
UV spectroscopy. Mass spectrum of the obtained mixture
shows the peaks of the protonated molecular ions of por
phyrins 4—7. The UV spectrum contains the Soret band
and the bands characteristic of the tetramesosubstituted
H NMR spectrum exhibits
signals characteristic of the porphyrin framework at