Reaction of perfluorobenzocycloalkenes with SiO2-SbF5 and skeleton transformations of their carbonyl derivatives in SbF5 medium

Article abstract of DOI:10.1134/s107042800802005x

The reaction of perfluorinated benzocyclobutene and tetraline with SiO ₂-SbF₅ led to the formation in a high yield of their mono- and further dicarbonyl derivatives. The monocarbonyl derivatives on heating with SbF₅ underwent disproportionation into the corresponding perfluorobenzocycloalkenes and diketones. Both mono- and diketones in the SbF₅ medium are liable to suffer skeleton rearrangements yielding five- and six-membered oxygen-containing heterocycles and/or products of the opening of the alicyclic fragment of the substrate, and from the perfluorobenzocyclobutenone compounds were also obtained with a number of carbon atoms greater than that of the initial ketone.

Full text of DOI:10.1134/s107042800802005x

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 2, pp. 202−217. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © Ya.V. Zonov, V.M. Karpov, V.E. Platonov, Yu.V. Gatilov, 2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 2,
pp. 212−226.
Reaction of Perfluorobenzocycloalkenes with SiO2−SbF5
and Skeleton Transformations of Their Carbonyl Derivatives
in SbF5 Medium
Ya. V. Zonov, V. M. Karpov, V. E. Platonov, and Yu. V. Gatilov
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
Novosibirsk, 630090 Russia
e-mail: karpov@nioch.nsc.ru
Received March 29, 2007
Abstract—The reaction of perfluorinated benzocyclobutene and tetraline with SiO2–SbF5 led to the formation in
a high yield of their mono- and further dicarbonyl derivatives. The monocarbonyl derivatives on heating with
SbF5 underwent disproportionation into the corresponding perfluorobenzocycloalkenes and diketones. Both mono-
and diketones in the SbF5 medium are liable to suffer skeleton rearrangements yielding five- and six-membered
oxygen-containing heterocycles and/or products of the opening of the alicyclic fragment of the substrate, and
from the perfluorobenzocyclobutenone compounds were also obtained with a number of carbon atoms greater
than that of the initial ketone.
DOI: 10.1134/S107042800802005X
We recently found that the reaction of perfluoroindan
(I) with SiO2–SbF5 cleanly led to perfluoroindan- 1-one
(II). Therewith ketone II and perfluoroindan-1,3-dione
III were shown to be able to suffer skeleton
rearrangements effected by antimony pentafluoride [1].
Similar reactions were unknown for the other perfluoro-
benzocycloalkenes and their carbonyl derivatives.
(Scheme 1). The formation of compounds II, III, VI–
IX can evidently be represented by a scheme involving
the reaction of primarily generated perfluorobenzocyclo-
alken-1-yl A and perfluorobenzocycloalkenon-1-yl B
cations with SiO2 (Scheme 1).
The considerable prevalence among the reaction
products of benzocycloalkenes I, IV, and V with SiO2–
SbF5 of their monocarbonyl derivatives II, VI, and VIII
compared to diketones III, VII, and IX may be due to
the fact that ketones II, VI, and VIII form with antimony
pentafluoride complexes X [1], XI, and XII (Scheme 1).
As a result the reaction of compounds II, VI, and VIII
should occur with greater difficulty than the reaction of
the corresponding benzocycloalkenes I, IV, and V.
Besides the complexing reduces the amount of “free”
SbF5 that should also decelerate the reaction.
Aiming at establishing the general rules of such
transformations of perfluorobenzocycloalkenes and their
carbonyl derivatives and also at revealing the effect of
the size of the alicyclic fragment in the substrate on the
course of the process we investigated the reactions of
perfluorobenzocyclobutene (IV) and perfluoro tetralin
(V) with SiO2–SbF5 and ascertained the relative reactivity
in this process of benzocycloalkenes I, IV, and V. Besides
we studied the behavior of perfluorinated
benzocyclobutenone (VI), benzocyclobutenedione (VII),
tetralin-1-one (VIII), and tetralin-1,4-dione (IX) in SbF5
medium.
The application of the concurrent reactions method
revealed that the reactivity of the perfluorinated benzo-
cycloalkenes toward SiO2–SbF5 depended on the size
of the alicyclic fragment of the substrate and decreased
in going from benzocyclobutene IV to indan I and tetralin
V. This sequence is consistent with the series of the
decreasing relative stability of the corresponding
perfluorobenzocycloalken-1-yl cations A [2].
It was shown that in reaction of compounds I [1], IV,
and V with SiO2 in SbF5 medium (molar ratio benzo-
cycloalkene:SiO2:SbF5 = 1:0.9:1.5) at 70°C formed
predominantly ketones II, VI, and VIII alongside
a small amount of diketones III, VII, and IX respectively
202

REACTION OF PERFLUOROBENZOCYCLOALKENES WITH SIO2−SBF5
203
Scheme 1.
O
O
_
SiO2 SbF5
70oC
+
F
F (CF2)n
F
F
(CF2)n
F
(CF2)n
III, VII, IX
I, IV, V
II, VI, VIII
_F _
O
F _
F OSiO
_[SiOF2]
SbF5
F _
_F _
_[SiOF2]
O
SbF5
+
O
F
+
SiO2
SiO2
F
(CF2)n
F
(CF2)n
F
F
(CF2)n
F
(CF2)n
F
+
+
F
F OSiO
A
B
+
O
_
O
SbF5_
.
O SbF5
(CF2)n
SbF5
+
F
(CF2)n
F
F
F
F
F
(CF2)n
X_XII
n = 0 (IV, VI, VII, XI), 1 (I–III, X), 2 (V, VIII, IX, XII).
C(O)–C(O) bond in diketone VII effected by the anti-
mony pentafluoride with the formation of acid difluoride
C. The hydrolysis of the latter yielded acid XIV
(Scheme 3). The cleavage of the four-membered ring of
compound VII occurred also at its heating with bromine
at 130°C. As a result diketone VII turned into 3,3-di-
bromo-4,5,6,7-tetrafluorophthalide (XV). This com-
pound is a tautomer of acid dibromide D and on
hydrolysis gives tetrafluorophthalic anhydride (XVI) and
acid XIV (Scheme 3).
In the reaction of compound V with excess SiO2–SbF5
at 120°C the only reaction product was diketone IX
(Scheme 2). Indan I under these conditions yielded
perfluoro-3-methylphthalide (XIII) [1]. The reaction of
benzocyclobutene IV with excess SiO2–SbF5 readily
proceeded even at 70°C to give on hydrolysis of the
reaction mixture compound VII alongside with a small
amount of tetrafluorophthalic acid XIV (Scheme 2).
Acid XIV formed in the reaction of compound IV
with SiO2–SbF5 evidently is the product of diketone VII
conversion under the action of SbF5. Actually, a special
experiment showed that the treatment of compound VII
with antimony pentafluoride at 130°C followed by
hydrolysis gave acid XIV (Scheme 3).
The five-membered ring of indanone II under
treatment with SbF5 at 130°C suffered the opening with
the formation of 6-pentafluoroethyl-2,3,4,5-tetra-
fluoro-benzoic acid (XVII). Concurrent with the latter
process compound II underwent disproportionation
into perfluoroindan (I) and diketone III that under the
The transformation of compound VII into acid XIV
evidently occurred through a stage of cleavage of the
Scheme 2.
O
F
F CF3
_
_
SiO2 SbF5
SiO2 SbF5
F
F
F
F
F
O
F
120oC
130oC
O
O
V
IX
I
XIII
_
(1) SiO2 SbF5, 70oC
(2) H2O
O
COOH
F
F
+
F
F
COOH
O
XIV
VII
IV
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 2 2008

ZONOV et al.
204
Scheme 3.
O
A
COOH
COOH
COF
F
SbF5, 130oC
_SbF3
H2O
F
F
COF
VII
Br2 130oC
COBr
C
XIV
H2O
O
Br Br
H2O
F
O
F
O
F
COBr
D
O
O
XV
XVI
yields acid XIV. The likely disproportionation route of
ketones II, VI, and VIII into the corresponding perfluoro-
benzocycloalkene and diketone is presented in
Scheme 5.
reaction conditions was converted into phthalide
XIII [1].
After heating ketone VI in the medium of SbF5 at
120°C the hydrolysis of the reaction mixture led to the
formation of compounds IV and XIV alongside with 6-
trifluoromethyl-2,3,4,5-tetrafluorobenzoic acid (XVIII).
The reaction mixture contained also perfluorinated
hydroxy-1-(2-ethylphenyl)benzocyclobutene (XIX),
2-acetyl-2'-methylbenzophenone (XX), [1-(2-methyl-
phenyl)benzocyclobuten-1-yl]-2-methylbenzo-ate (XXI),
[1-(2-ethylphenyl)benzocyclobuten-1-yl]-2-methylbenzo-
ate (XXII), and unreacted compound VI (Scheme 4).
Besides in the reaction a small amount was obtained of
5,6-dihydro-7-oxadibenzo[a,h]azulen-8-one (XXIII) that
contained by one carbon more than two molecules of
initial compound VI.
It is presumable that acid XVIII forms in the reaction
of ketone VI with SbF5 through the rupture of the C(O)–
CF2 bond in ketone VI under the action of the antimony
pentafluoride similarly to the conversion of compound
VII into acid XIV (Scheme 3). It was however
demonstrated that ketone VI in contrast to diketone VII
did not react with bromine at 130°C. Therefore it cannot
be excluded that the formation of acid XVIII in the
reaction of ketone VI with SbF5 results from the
transformation of products generated by the opening of
the four-membered ring of compound VII under the
reaction conditions (Scheme 6).
The formation of reaction products IV and XIV may
be ascribed to the dispropotionation of ketone VI into
compound IV and diketone VII that as already mentioned
Thus, first arising acid difluoride C can exist in a tauto-
meric form E [3]. The replacement in the latter of
a carbonyl by a difluoromethylene group under the action,
Scheme 4.
F
C2F5
OH
(1) SbF5, 120oC
(2) H2O
O
CF3
COOH
+
F
F
+
+
F
F
F
F
F
F
COOH
XVIII
COOH
VI
IV
XIV
XIX
3
3''
4''
2
4
5''
2''RF
F
F
5'
CF3
O
1
O
CF3
5
1''
4'
3'
6'
1'
6''
12
6
2
2'
F
F
1
1'
1
6a
6
3'
4'
11
10
3
4
5
4
O
+
+
F
+
F
O
F
F
F
2'
7
6
2
O
6'
2a
8
F3C
5
3
5'
9
O
XX
XXI, XXII
RF = CF3 (XXI), C2F5 (XXII).
XXIII
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 2 2008

REACTION OF PERFLUOROBENZOCYCLOALKENES WITH SIO2−SBF5
205
for instance, of initial ketone VI or/and the formed
compound IV results in perfluorophthalane XXIV. The
latter transformation involving oxygen transfer from one
perfluorinated compound to another is essentially similar
to the disproportionation process of ketones II, VI, and
VIII (Scheme 5). Further compound XXIV under the
action of SbF5 is converted into acid fluoride F.
Therewith the possibility of formation of the latter by
replacement of an oxygen by a fluorine directly in acid
difluoride C is not excluded. Hydrolysis of acid fluoride
Ε provides acid XVIII (Scheme 6).
This interpretation does not contradict the fact that
on addition to the reaction products of diketone VII with
SbF5 of perfluorotoluene as fluorine donor and oxygen
acceptor followed by heating the mixture at 130°C the
subsequent hydrolysis of the reaction mixture yields
a mixture of acids XIV and XVIII. Besides a special
experiment showed that phthalane XXIV on dissolution
in antimony pentafluoride followed by hydrolysis was
converted into acid XVIII (Scheme 6).
Compounds XIX–XXIII likely formed in the reaction
of ketone VI with antimony pentafluoride by binding
several molecules of compounds IV and VI followed by
skeleton rearrangements in thus obtained products. Some
among the probable routes of these transformations are
presented in Scheme 7. For instance, the reaction of com-
pound IV with cation G after the addition–elimination
of the fluoride ion provides cation H whose hydrolysis
leads to the formation of alcohol XIX [4, 5]. In the course
of hydrolysis of the reaction mixture occurs presumably
the reaction of alcohol XIX with cation I or/and with
acid fluoride F resulting in ester XXII. The route of com-
pound XXII formation by reaction of cation H with acid
XVIII obtained by hydrolysis also cannot be ruled out.
It is presumable that the reaction of ketone VI with
ion G gives cation J that undergoes decarbonylation and
after the addition–elimination of the fluoride ion provides
cation K. The latter during the hydrolysis of the reaction
mixture transforms into ester XXI analogously to the
conversion of cation H into compound XXII.
Scheme 5.
F
F
F
(CF2)n
F
F
F
F
+
(CF2)n
F
F
F
(CF2)n
F (CF2)n
F
F
F
(CF2)n
F
F
(CF2)n
+
F _
± F_
F
I, IV, V
O
O
SbF5
_F_
+
+
O
O
+
O
O
F
F
+
+
(CF2)n
(CF2)n
F
(CF2)n
O
F
F
(CF2)n
(CF2)n
F (CF2)n
O
O
O
O
O
III, VII, IX
II, VI, VIII
n = 0 (IV, VI, VII), 1 (I–III), 2 (V, VIII, IX).
Scheme 6.
F F
F F
CF3
COF
COF
SbF5
SbF5
VI
_VII
XXIV
F
F
O
F
O
F
COF
F F
O
C
E
XXIV
F
VI
_SbF3
H2O
SbF5
_VII
(1) SbF5, 130oC
(2) C6F5CF3, 130oC
(3) H2O
O
COOH
COOH
CF3
F
+
F
F
COOH
XVIII
O
XIV
VII
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 2 2008

ZONOV et al.
206
The addition of a fluoride ion to cation H gives
transforms into compound XX. Besides the transforma-
tion of one difluoromethylene group of compound L into
a carbonyl followed by the conversion of the result-ing
product into compound XX also cannot be ruled out.
compound L that under the action of SbF5 suffers the
opening of the four-membered ring [4] resulting in
diarylmethane M. The latter under the reaction conditions
Scheme 7.
+
F
CF2CO
F
CF3
(1) _CO
(2) ±F
_
G
VI
XXI
F
F
F
F
J
K
XVIII
_H+
O
C2F5
F
C2F5
OH
F
1. G
2. ±F_
I
H2O
XXII
+
IV
_H+
F
F
F
F
XIX
H
_
F
_HF
F
N
C2F5
F
CF3CF2
F
F
CF3
CF2
SbF5
XX
F
F
F
CF2
+CF2
F
F
O
O
M
L
F _
F
F
(1) G
(1) G
F
F
(2) ±F_
(2) F_
F
F
F
F
CF2
CF2
+
F
F
F
F
F
F
F
O
O
Q
P
O
_R
(1)
_
(2) _F
F
F
F
F
F _
F
F
H2O
_[2F], _F_
F
XXIII
O
F
O
F
O
+
F
+
CF2
F
U
T
S
F
CF3
CF3
+
CO
+
+
.
+CF2
R =
F =
,
G =
N =
,
F
,
I =
,
F
F
F
F
F
F
F
COF
O
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 2 2008

REACTION OF PERFLUOROBENZOCYCLOALKENES WITH SIO2−SBF5
207
The reaction of benzocyclobutene IV with cation N
gives intermediate O that undergoes cyclization into
compound P. Two consecutive attacks of cation G convert
compound P into ion Q that decomposes into cation R
and a compound being a precursor of cation S. The
cyclization of ion S leads to compound T that suffers
defluorination by some polyfluorinated compound [6],
eliminates a fluoride ion, and forms cation U. The
hydrolysis of the latter provides compound XXIII
(Scheme 7).
fluoropropyl-2,3,4,5-tetrafluorobenzoic acid (XXVIII),
phthalides XXV and XXVI, and acid XIV (Scheme 8).
One of the possible routes of diketone IX trans-
formations effected by SbF5 into compounds XXV and
XXVI is presented in Scheme 8. First from compound
IX cation V is generated that suffers ring opening to form
ion W. The latter after adding a fluoride ion is fluorinated
to give a compound from which cation X is generated.
The intramolecular cyclization of X followed by
a fluoride ion addition results in phthalide XXVI whose
hydrolysis leads to the formation of hydroxyphthalide
XXV. Besides another route to compound XXVI should
not be ruled out where first cyclization of cation W occurs
and then the fluorination of the double bond in the
product obtained. The formation of acid XXVIII in the
reaction of compound IX with SbF5 evidently results
from the transformations of phthalide XXVI by a scheme
similar to that of transformation of compound E into acid
XVIII (Scheme 6).
Tetralone VIII at heating with SbF5 at 130°C
disproportionated into a mixture of tetralin V and
diketone IX containing also the initial compound.
Besides the mixture contained small amounts of 3-hy-
droxyperfluoro-3-ethylphthalide (XXV) and perfluoro-
3-ethylphthalide (XXVI) (Scheme 8). Diketone IX in
its turn under similar conditions yielded not only
ethylphthalides XXV and XXVI but also compounds V
and VIII along with methylphthalide XIII and 3-hy-
droxyperfluoro-3-methylphthalide (XXVII). Yet the
heating of compound IX solution in antimony
pentafluoride at 180°C with subsequent hydrolysis of
the reaction mixture resulted in a mixture of 6-hepta-
Raising the reaction temperature of tetralone VIII
with antimony pentafluoride to 180°C results in the
formation of a complex mixture containing alongside
compounds V, XVII, XVIII, XXV, XXVI, and XXVIII
Scheme 8.
O
F
(1) SbF5, 130oC
(2) H2O
HO C2F5
F C2F5
+
+
+
+
F
IX
F
F
F
O
O
F
O
O
VIII
V
XXV
XXVI
HO CF3
(1) SbF5, 130oC
(2) H2O
F
O
V
VIII
XIII
XIV
XXV
XXVI
+
+
+
+
+
O
XXVII
H2O
O
γ
α
β
(1) SbF5, 180oC
(2) H2O
5
CF2CF2CF3
6
4
3
F
F
+
+
F
XXV
XXVI
XIV
+
1
COOH
2
O
IX
XXVIII
F_
_F_
O
O
O
C2F5
+
SbF5
+
CF CF2
C2F5
F
F
F
O
F
F
+
+
CO
CO
O
O
W
X
V
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 2 2008

ZONOV et al.
208
perfluorinated 3,3-dimethylphthalide XXIX, 3-hydroxy-
3-methyl-3,4-dihydroisochromen-1-one (XXX),
3-methyl-3,4-dihydroisochromen-1-one (XXXI),
3-methylisochromen-1-one (XXXII), and 6-hepta-
fluoroisopropyl-2,3,4,5-tetrafluorobenzoic acid
(XXXIII) (Scheme 9).
said acid fluoride. The cyclization and subsequent
hydrolysis of cation Z results in the formation of
phthalide XXIX. The possibility of this cyclization to
occur is proved by the formation of compound XXIX at
heating to 180°C of a mixture obtained by reacting
isopropyltoluene XXXIV with SiO2–SbF5 at 70°C
(Scheme 10).
Reaction products XXIX and XXXIII likely form in
reaction of compound VIII with SbF5 as a result of
transformation of tetralin V under the reaction conditions.
These transformations may be described by Scheme 10.
First compound V under the action of SbF5 forms
perfluoro-2-isopropyltoluene (XXXIV) [5] that further
reacts with oxygen-containing compounds present in the
mixture to give acid fluoride Y. The hydrolysis of the
latter leads to acid XXXIII, and by the action of the
antimony pentafluoride cation Z is generated from the
Compounds XXVIII and XXX–XXXII obtained in
the reaction of tetralone VIII with antimony
pentafluoride are evidently the products of skeleton rear-
rangements of ketone VIII itself and not of its dispropor-
tionation products. Some probable pathways of the
occurring transformations are presented in Scheme 11.
First by the action of SbF5 cation Z1 is generated from
compound VIII where a ring opening takes place leading
after addition–elimination of a fluoride ion to cation Z2.
Scheme 9.
O
F
(1) SbF5, 180oC
(2) H2O
HO C2F5
F C2F5
F3C CF3
+
+
+
O
O
O
O
F
O
O
F
F
F
F
F
VIII
V
XXVI
XXV
XXIX
RF
F
OH
F
5
4
CF3
3
6
CF3
CF3
F
F
F
F
F
+
+
+
F
+
O
O
O 2
7
1
COOH
8
O
O
O
XXX
XXXI
XXXII
XXVIII, XXXIII
XVII, XVIII,
(1) Glass_SbF5, 180oC
(2) H2O
XXIX_XXXIII
+
+
V
XIV
+
XXV
XXVI
RF = CF3 (XVIII), CF2CF3 (XVII), CF2CF2CF3 (XXVIII), CF(CF3)2 (XXXIII).
Scheme 10.
F3C CF3
F
F3C CF3
F
F3C CF3
F
RR'C=O
SbF5
180oC
H2O
F
F
F
F
F
_
RR'CF2
CF3
XXXIV
COF
COOH
XXXIII
SiO2 SbF5, 70oC
V
Y
_
180oC
SbF5
F3C CF3
F3C CF3
F3C CF3
XXXIV
C
+
H2O
F
O
O
F
O
+
F
COF
F
Z
XXIX
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 2 2008

REACTION OF PERFLUOROBENZOCYCLOALKENES WITH SIO2−SBF5
209
The latter is an ion of allyl type whose cyclization might
occur involving both charge centers. One of cyclization
routes results in intermediate A1 that through the
fluorination of the double bond followed by the opening
of the five-membered ring and by fluoride ion addition
is converted into 6-heptafluoropropyl-2,3,4,5-tetrafluoro-
benzoyl fluoride (XXXV) whose hydrolysis gives acid
XXVIII. It cannot be ruled out that compound XXXV
forms also by fluorination of compound B1.
with small amounts of compounds XXIX–XXXIII
(Scheme 9).
The composition and structure of new compounds
were established from elemental analysis and spectral
characteristics. Besides compound XXIII was subjected
to X-ray diffraction analysis on a single crystal, and the
refining of the structure resulted in a high value of the
factor R1 (0.15). The data obtained made it possible to
unambiguously establish the molecular structure (see the
figure), but its detailed discussion is superfluous because
of large inaccuracy. Note however that the molecule is
essentially nonplanar, and the angle between the planes
of the indenyl and benzene fragments equals 47.6(3)°
for both molecules contained in the independent part of
the cell.
The assignment of signals in the 19F NMR spectra of
compounds was performed based on the values of the
chemical shifts of the signals, their fine structure and
integral intensity. The assignment of signals for
complexes XI and XII (poorly resolved signals) was done
by analogy with complex X [1] and 1-hydroxyper-
fluorobenzocycloalken-1-yl cations [3].
The other cyclization pathway of cation Z2 after
addition–elimination of a fluoride ion produces cation
C1 that through the contraction of the seven-membered
ring followed by transition of the cation center transforms
into tricyclic intermediate D1. The opening of the
cyclopropane ring in the latter and addition of a fluoride
ion to the arising cation results in compound E1. Besides
it might be that compound E1 formed by electrocyclic
reaction from acid fluoride B1. Then compound E1 in
the presence of antimony pentafluoride serves as a source
for generating cation F1 whose hydrolysis yields com-
pound XXXII. Moreover, compound E1 can undergo
fluorination giving reaction product G1. The latter
eliminating a fluoride ion provides cation H1 that con-
verts on hydrolysis into compound XXXI. The formation
of compound G1 by alternative route, cyclization of acid
fluoride XXXV, is hardly possible for the heating of the
latter with antimony pentafluoride at 180°C with the
subsequent hydrolysis of the reaction mixture does not
lead to the formation of compounds XXX and XXXI.
The coupling constants JA,B 199 and J3,6 23 Hz
characteristic of polyfluorobenzocyclobutenes [4]
belonging to the fluorine atoms of the CF22 group and to
fluorine atoms in the para-position with respect to each
other observed in the 19F NMR spectrum of compounds
XXI and XXII indicate the presence in their structure
of a polyfluorobenzocyclobutene moiety. The 19F NMR
spectrum of compound XXIII contained large coupling
constants J1,12 46 and J4,5B 95 Hz (J4,5A < 5 Hz) due to
the spatial proximity of the coupled nuclei [7].According
to the X-ray diffraction study the corresponding distances
are: F1–F12 2.64(1), F4–F5B 2.46(1), F4–F5A 3.92(1) Å.
A special experiment demonstrated that the hydrolysis
of compound XXXI in acid medium provided compound
XXX. Compound XXXII practically did not change
under these conditions, whereas under the treatment with
a water solution of NaHCO3 it was converted into 3-hy-
droxy-3-trifluoromethyl-4,5,6,7,8-pentafluoro-3,4-di-
hydroisochromen-1-one XXXVI (Scheme 11).
Compounds XXV, XXX, and XXXVI can formally
exist as 6-(pentafluoropropanoyl)-2,3,4,5-tetrafluoro-
benzoic (XXXVII), 6-(2-oxopentafluoropropyl)-2,3,4,5-
benzoic (XXXVIII), and 6-(2-oxo-1,3,3,3-tetrafluoro-
propyl)-2,3,4,5-tetra-fluorobenzoic (XXXIX) acids
respectively (Scheme 12).
We formerly showed that perfluoroindan (I) in the
presence of SbF5 reacted with glass as a source of
inorganic oxides giving ketone II that under the reaction
conditions suffered further transformations; therewith
a ratio of reaction products differed considerably from
that obtained by heating individual compound II with
SbF5 [1].
The existence of compounds XXV and XXX in CDCl3
solution in the cyclic form is confirmed by the presence
in their 1H NMR spectra of signals at 4.82 and 5.19 ppm
(OH) respectively, and also the nonequivalence of the
fluorine atoms of the CF2 groups in the 19F NMR spectra.
In contrast to phthalide XXV compound XXX in ether
solution is present both in the cyclic form XXX and as
acid XXXVIII in a ratio 45:55. In the 1H and 19F NMR
In this connection we studied the reaction of tetralin
V with glass in the presence of antimony pentafluoride.
For instance, the heating of tetralin V with SbF5 in
a glass ampule at 180°C followed by the hydrolysis of
the reaction mixture provided a mixture containing
prevailingly compounds XIV, XXV, and XXVI along
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 2 2008

ZONOV et al.
210
Scheme 11.
+
CF2
CF
CF2
CF2
± F_
+
SbF5
_F_
CF
CF
F
F
F
F
F
F
+
CO
COF
O
O
VIII
Z1
Z2
F _
F CF CF2
SbF5
F C2F5
F _
CF2CF2CF3
COF
CF CFCF3
SbF5
_SbF3
Z2
F
F
F
O
F
O
+
+
C O
F
F
F
À1
XXXV
B1
H2O
± F _
F
+
CF2
XXVIII
± F_
+
F
F
F
F
F
F
F
F
F
O
O
O
O
O
+
B1
D1
_
F
F
CF3
CF3
OH
CF3
CF3
SbF5
F
F
F
F
F1
H2O
_F_
_SbF3
O
_F_
O
O
+
F
+
H1
G1
E1
H2O
F
F
H
NaHCO3,
H2O
OH
CF3
CF3
CF3
H2O,H+
CF3
F
F
F
F
F
F
O
O
O
XXX
XXXI
XXXII
XXXVI
O
O
O
O
spectra of compound XXXVI solution in CDCl3 two sets
of signals are observed with close values of the chemical
shifts belonging to two spatial isomers of the cyclic form
XXXVI in a ratio 94:6. At the same time in the 19F NMR
spectrum of the ether solution of compound XXXVI also
two groups of signals are present but with essentially
different chemical shifts. Consequently, in the ether
solution compound XXXVI exists as an equilibrium
mixture of one cyclic isomer XXXVI and acid XXXIX
in a ratio 80:20.
Compounds IV–VIII, XIII, XIV, XVI–XIX, XXVII,
and XXXIII were identified by comparison of their 19F
NMR spectra with those of the corresponding authentic
samples.
Structure of one of the two crystallographically independent
molecules of perfluoro-5,6-dihydro-7-oxadibenzo[a,h]azulen-
8-one (XXIII).
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REACTION OF PERFLUOROBENZOCYCLOALKENES WITH SIO2−SBF5
211
Scheme 12.
F
O
R
F
R
HO C2F5
OH
CF3
CF3
C2F5
COOH
XXXVII
EXPERIMENTAL
F
F
O
O
F
F
O
O
COOH
O
XXXVIII, XXXIX
XXV
XXX, XXXVI
parameters: wR2 0.4698, S 2.593 (for all 5360 reflec-
tions), R1 0.1489 [for 4096 reflections with I ≥ 2σ(I)].
All calculations were carried out with the use of SHELX
software. It should be noted that the crystals were of poor
quality (peaks width 2–4°), probably, because of tendency
to twinning up to the formation of pseudomonoclinic
crystal system. In the crystal under study the twinning
contribution was 5.7%.
IR spectra were recorded on a spectrophotometer
Bruker Vector 22. UV spectra were measured on a spec-
trophotometer Hewlett Packard 8453. 1H and 19F NMR
spectra were registered on spectrometers BrukerAC-200
and Bruker WP-200 SY (200 and 188.3 MHz respec-
tively), 13C NMR spectrum of the mixture of compounds
XXI and XXII was taken on Bruker AV-300 instrument
(75.5 MHz). As internal references served HMDS
(0.04 ppm from TMS), CHCl3 (7.24 ppm from TMS),
C6F6, SO2ClF (262.8 ppm from C6F6), CDCl3 (76.9 ppm
from TMS). Elemental composition of compounds was
established by means of high resolution mass
spectrometry on Finnigan MAT 8200 instrument. GLC
analysis was performed on a chromatograph LKhM-72
(50–270°C, column 4000×4 mm, stationary phase BC-1,
SKTF-50 or Ε-301 on Chromosorb W, 15:100, carrier
gas helium, 60 ml/min). GC-MS analysis was carried
out on a Hewlett-Packard G1081A instrument equipped
with a gas chromatograph HP 5890 of II series and
a mass-selective detector HP 5971 (electron impact,
70 eV), capillary column HP 5 (5% diphenyl, 95%
dimethylsiloxane) 30 m×0.25 mm×0.25 μm, carrier gas
helium, 1 ml/min.
Reaction of perfluorobenzocyclobutene (IV) with
SiO2–SbF5. a. A mixture of 1.91 g (7.7 mmol) of
compound IV, 0.41 g (6.82 mmol) of SiO2 (silica gel
calcined at 400–450°C), and 2.51 g (11.58 mmol) of SbF5
was stirred for 5 h at 70°C, then treated with 5% HCl,
extracted with CH2Cl2, the extract was dried with
MgSO4, and the solvent was distilled off in a vacuum.
We obtained 1.53 g of a mixture containing according to
19F NMR spectrum and GLC 86% of ketone VI (yield
76%), 9% of diketone VII (yield 8%), and 5% of
unreacted compound IV.
b. Analogously to the previous run from 2 g
(8.06 mmol) of compound IV, 0.27 g (4.49 mmol) of
SiO2, and 3.5 g (16.14 mmol) of SbF5 (70°C, 6.5 h) we
obtained 1.6 g of a mixture containing according to
19F NMR spectrum compounds VI and VII in a ratio
80:20, yields 72 and 18% respectively.
c. A mixture of 2.13 g (8.59 mmol) of compound IV,
0.77 g (12.81 mmol) of SiO2, and 5.58 g (25.74 mmol)
of SbF5 was stirred for 5 h at 70°C, then treated with 5%
HCl, extracted with CH2Cl2, then with ether, and the
extracts were dried with MgSO4. On distilling off in
a vacuum the solvent from the dichloromethane extract
we obtained 1.51 g (86%) of diketone VII, and on remov-
ing solvent from the ether extract we obtained after
sublimation at 150°C (2 mm Hg) 0.14 g (7%) of acid XIV.
X-ray diffraction analysis was performed with the use
of diffractometer Bruker P4 [graphite monochromator,
λ(MoKα) 0.71073 Å, θ/2θ-scanning, 2θ < 50°]. Single
crystals of compound XXIII were grown by slow
evaporation of the solvent from its solutions in a mixture
hexane–CH2Cl2. Crystallographic data of compound
XXIII: crystals triclinic, space group P-1, a 6.343(4),
b8.582(5), c28.215(16) Å, α92.01(5),β91.12(5),γ 94.62(5)°,
V 1530(2) Å3, C17F12O2, Z 4, dcalc 2.016 g/cm3,
μ 0.230 cm–1. The extinction was accounted for using
experimental curves of azimuthal scanning (Tmin/Tmax
0.45/0.79). The structure was solved by the direct
method. The positions and temperature factors of the
atoms were refined in an anisotropic approximation by
full-matrix least-mean-square procedure. Refinement
Reaction of perfluorotetralin (V) with SiO2–SbF5.
a. Analogously to the experiment a with compound IV
from 1.18 g (3.39 mmol) of compound V, 0.18 g (3 mmol)
of SiO2, and 1.1 g (5.07 mmol) of SbF5 (70°C, 4 h) we
obtained 0.96 g of a mixture containing according to
19F NMR spectrum and GLC 87% of ketone VIII (yield
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ZONOV et al.
212
76%), 9% of diketone IX (yield 8%), and 4% of unreact-
ed compound V.
b. Asolution of 0.17 g (0.83 mmol) of compound VII
in 4.22 g (19.37 mmol) of SbF5 was heated for 4.5 h at
130°C, then 1 g (4.24 mmol) of perfluorotoluene was
added, and the mixture was again heated for 9 h at 130°C.
The mixture was treated with 5% HCl, extracted with
ether, the extract was dried with MgSO4. We obtained
a solution containing according to 19F NMR spectrum
compounds XIV and XVIII in a ratio 85:15 along with
perfluorinated toluene and benzoic acid. The solution
was transferred to a watch glass, the solvent was
evaporated, the crystalline residue was sublimed at 120°C
(2 mm Hg). We obtained 0.44 g of a mixture containing
according to 19F NMR spectrum 28% of acid XIV (yield
66%), 5% of compound XVIII (yield 12%), and 67% of
pentafluorobenzoic acid.
b. Analogously to the experiment a with compound
IV from 1.48 g (4.25 mmol) of compound V, 0.19 g
(3.16 mmol) of SiO2, and 1.85 g (8.53 mmol) of SbF5
(70°C, 4.5 h) we obtained 1.11 g of a mixture containing
according to 19F NMR spectrum and GLC 89% of ketone
VII (yield 71%), 5% of compound IX (yield 4%), and
6% of initial tetralin V.
c. A mixture of 1.28 g (3.68 mmol) of compound V,
0.24 g (4 mmol) of SiO2, and 3.18 g (14.67 mmol) of
SbF5 was stirred for 3.5 h gradually raising the tempera-
ture from 75 to 120°C, then the reaction mixture was
treated with 5% HCl, extracted with ether, and the solvent
was removed in a vacuum. The residue was dissolved in
CH2Cl2, dried on MgSO4, and placed on a watch glass.
We obtained 0.92 g (82%) of tetralinedione IX, the
sample for analysis was prepared by sublimation at 60°C
Reaction of perfluorobenzocyclobutenedione (VII)
with Br2. a. A mixture of 0.08 g (0.39 mmol) of
compound VII and 0.6 g (3.75 mmol) of Br2 was heated
for 17.5 h at 130°C, washed with water solution of
Na2SO3, acidified with HCl, extracted with ether, the
extract was dried with MgSO4. We obtained a solution
containing compounds XIV, XV, and XVI in a ratio
35:53:12 (according to 19F NMR spectrum). To the
solution 2 ml of 10% HCl was added, and the mixture
was left standing for 5 days, then the ether layer was
separated, dried with MgSO4, transferred to a watch
glass, the solvent was evaporated, and we obtained
0.08 g (86%) of acid XIV.
(20 mm Hg), mp 86–87°C. UV spectrum (hexane), λmax
,
nm (log ε): 228 (4.32), 254 (3.94), 263 (3.94), 308 (3.50),
318 (3.51). IR spectrum (CCl4), ν, cm–1: 1748 (C=O),
1513, 1482 (fluorinated aromatic ring). 19F NMR
spectrum (CH2Cl2), δ, ppm: 36.5 s (4F, 2CF2), 31.2 m
(2F, F5,8), 24.6 m (2F, F6,7). Found [M]+ 303.9769.
C10F8O2. Calculated M 303.9771.
Concurrent reactions of perfluorinated benzo-
cyclobutene IV, indan I, and tetralin V with SiO2–
SbF5. a. A mixture of 0.65 g (2.18 mmol) of indan I,
0.54 g (2.18 mmol) of compound IV, 0.04 g (0.67 mmol)
of SiO2, and 1.5 g (6.91 mmol) of SbF5 was stirred for
5 h at 70°C, then treated with 5% HCl, extracted with
CH2Cl2, the extract was dried with MgSO4, and the
solvent was distilled off in a vacuum. We obtained
1.53 g (83%) of a mixture containing according to
19F NMR spectrum compounds I, II, IV, and VI in
a ratio 51:2:15:32.
b. A mixture of 0.2 g (0.98 mmol) of compound VII
and 0.6 g (3.75 mmol) Br2 was heated for 21 h at 130°C,
the excess Br2 was flushed away, and we obtained
0.34 g of a mixture of compounds XV and XVI (accord-
ing to 19F NMR spectrum) in a ratio 93:7 (yields 91 and
7% respectively). Analytical sample of compound XV
(fluid) we obtained by “sublimation” at 100°C (2 mm Hg).
IR spectrum (CCl4), ν, cm–1: 1831 (C=O), 1522, 1466
(fluorinated aromatic ring). 19F NMR spectrum (CH2Cl2),
δ, ppm: 27.0 (1F, F7), 25.3 (1F, F4), 24.0 (1F, F5), 16.2
(1F, F6); J(FF), Hz: J4,5 20, J4,6 7, J4,7 18, J5,6 18,
J5,7 11, J6,7 21. Found [M – Br]+ 282.9031. C8BrF4O2.
Calculated [M – Br] 282.9010.
b. Similarly to the previous run from 0.59 (1.98 mmol)
of indan I, 0.69 g (1.98 mmol) of tetralin V, 0.04
(0.67 mmol) of SiO2, and 1.73 g (7.98 mmol) of SbF5
(70°C, 6 h) we obtained 1.06 g (85%) of a mixture
containing according to 19F NMR spectrum compounds
I, II, V, and VIII in a ratio 12:37:47:4.
Reaction of perfluorobenzocyclobutenone (VI)
with SbF5. a. Into an NMR tube a mixture of 1.34 g (6.2
mmol) of SbF5 and 0.19 g (0.82 mmol) of compound VI
was placed, the mixture was dissolved, SO2ClF was
added, and 19F NMR spectrum was registered containing
signals from complex XI. 19F NMR spectrum (SbF5–
SO2ClF), δ (Δδ), ppm: 80.0 (13.9) (2F, CF2), 62.6 (33.6)
(1F, F4), 57.3 (20.3) (1F, F6), 36.5 (7.0) (1F, F3), 33.7
Reaction of perfluorobenzocyclobutenedione (VII)
with SbF5. a. A solution of 1.04 g (5.1 mmol) of
compound VII in 3.32 g (15.31 mmol) of SbF5 was heated
for 4.5 h at 130°C, then the reaction mixture was treated
with 5% HCl, extracted with ether, the extract was dried
with MgSO4, transferred to a watch glass, the solvent
was evaporated, and the residue was sublimed at 150°C
(2 mm Hg). We obtained 0.85 g (70%) of acid XIV.
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REACTION OF PERFLUOROBENZOCYCLOALKENES WITH SIO2−SBF5
213
(11.6) (1F, F5). The solution was treated with 5% HCl,
extracted with CH2Cl2, the extract was dried with
MgSO4, the solvent was distilled off in a vacuum to give
0.13 g of a mixture of compounds VI and VII in a ratio
82:18 (according to 19F NMR spectrum) (yield 48 and
11% respectively).
[M – F]+ 470.9727. C16F14O2. Calculated, %: C 39.21;
F 54.26. [M – F] 470.9691.
A mixture of compounds XXI and XXII. IR spec-
trum (CCl4), ν, cm–1: 1776 (C=O), 1527, 1522, 1488,
1471 (fluorinated aromatic ring). 19F NMR spectrum
(CH2Cl2), δ, ppm, compound XXI: 106.2 (3F, CF23'', 105.5
(3F, CF23'), 70.4 (1F, FA) and 62.4 (1F, FB, CF22), 38.0 (1F,
F6), 29.7 (1F, F3''), 29.1 (1F, F6''), 27.2 (1F, F3'), 25.4 (1F,
b. A solution of 1.35 g (5.98 mmol) of compound VI
in 4.89 g (22.41 mmol) of SbF5 was heated for 6.5 h at
120°C, then treated with 5% HCl, extracted with CH2Cl2,
then with ether, and the extracts were dried with MgSO4.
The ether extract was transferred to a watch glass, the
solvent was evaporated, and the residue was sublimed at
170°C (2 mm Hg) to provide 0.35 g (25%) of acid XIV.
Dichloromethane extract containing according to
19F NMR spectrum compounds IV, VI, XVIII, XIX, XX,
XXI, XXII, and XXIII in a ratio 5:15:44:2:24:3:6:1
was washed with water solution of NaHCO3. The water
layer was acidified with HCl, extracted with ether, the
extract was dried with MgSO4, transferred to a watch
glass, the solvent was evaporated to give 0.28 g (18%)
of acid XVIII. From the solution in CH2Cl2 the solvent
was distilled off in a vacuum, the mixture obtained
(0.67 g) was placed on a watch glass. On removal of the
volatile components and sublimation of the residue at
130°C, (2 mm Hg) we obtained 0.54 g of a mixture of
products. From 0.38 g we separated by column chromato-
graphy on silica gel (eluent CCl4) 0.11 g (11%) of a mix-
ture of compounds XXI and XXII, 0.01 g of compound
XXIII, then (eluent CHCl3) a fraction (0.19 g) containing
according to 19F NMR spectrum compounds XIX and
XX in a ratio 12:88. Analytical sample of the mixture of
compounds XXI and XXII in a ratio 40:60 (19F NMR
spectrum) was prepared by repeated column chromato-
graphy on silica gel (eluent a mixture CCl4–hexane,
2:5 v/v) and by sublimation at 140°C (2 mm Hg).
Analytical sample of compound XXIII was obtained by
sublimation at 120°C (2 mm Hg) and by recrystallization.
From the fraction containing compound XX we obtained
by repeated column chromatography on silica gel (eluent
CHCl3) 0.16 g (16%) of compound XX (fluid). UV
spectrum (hexane), λmax, nm (log ε): 211 (4.19), 254
(4.01). IR spectrum (CCl4), ν, cm–1: 1764, 1690 (C=O),
1530, 1519, 1477 (fluorinated aromatic ring). 19F NMR
spectrum (CH2Cl2), δ, ppm: 107.1 (3F, CF32'), 85.0 (3F,
F3), 24.4 (1F, F6 ), 20.2 (1F, F5), 18.9 (1F, F4), 17.1 (1F,
'
F4''), 16.2 (1F, F4'), 15.0 (1F, F5''), 15.0 (1F, F5'); J(FF),
Hz: JA,B 199, JA,3 3, JA,2'' 7, JB,3 3, JB,2'' 25, J3,4 20, J3,5 7,
J3,6 23, J4,5 18, J4,6 10, J5'6 18, J6,6'' 43, J2',3' 19, J3',4' 21,
J3',5' 9, J3',6' 11, J4',5' 21, J4',6' 9, J5',6' 21, J6',2'' 8, J2'',3'' 23,
J3'',4'' 21, J3'',5'' 7, J3'',6'' 9, J4'',5'' 20, J4'',6'' 9, J5'',6'' 21; compound
2'
2''
XXII: 105.9 (3F, CF3 ), 80.8 (3F, CF3 ), 72.2 (1F, FA)
2
and 61.9 (1F, FB, CF2 ), 59.5 (1F, FA) and 51.9 (1F, FB,
CF22''), 37.9 (1F, F6), 34.1 (1F, F3''), 30.6 (1F, F6''), 27.4
(1F, F3 ), 25.8 (1F, F6'), 25.0 (1F, F3), 19.6 (1F, F5), 18.7
'
(1F, F4), 17.5 (1F, F4'), 16.9 (1F, F4''), 15.6 (1F, F5''), 15.4
(1F, F5'); J(FF), Hz: JA,B 199, JA,3 3, JA,B'' 16, JB,3 3, JB,A''
14, JB,B'' 74, J3,4 20, J3,5 7, J3,6 23, J4,5 18, J4,6 10, J5,6 18,
J6,6'' 46, J2',3' 21, J3',4' 21, J3',5' 10, J3',6' 11, J4',5' 21, J4',6' 10,
J5',6' 22, J(F6', CF23''') 9, J(CF23'', F3') 25, JA'',B'' 288, JA'',3''
43, JB'',3'' 7, J3'',4'' 21, J3'',5'' 7, J3'',6'' 9, J4'',5'' 20, J4'',6'' 9, J5'',6''
21. 13C NMR spectrum (CDCl3), δ, ppm, compound XXI:
157.9 s (CO), 148.2–139.8 (C3,3',3'',4,4',4'',5,5',5'',6,6',6''), 120.7
1
q (1JCF 275 Hz) and 120.6 q (CF32',2'', JCF 275 Hz), 123.0–
1
112.4 (C1',1'',2a,2',2'',6a), 114.2 t (CF22, JCF 292 Hz), 87.6
d.d (C1, 2JCF 30, 22 Hz); compound XXII: 157.6 s (CO),
148.2–139.8 (C3,3',3'',4,4',4'',5,5',5'',6,6',6''), 120.6 q (CF32', 1JCF
275 Hz), 118.6 q.t (CF32'', 1JCF 288, 2JCF 37 Hz), 123.0–
112.4 (C1',1'',2a,2',2'',6a), 114.4 t (CF22, 1JCF 293 Hz), 112.0
t.q (CF22'', 1JCF 262, 2JCF 41 Hz), 88.3 d.d (C1, 2JCF 30,
22 Hz). Found, %: C 40.11. M 704 (CHCl3, vapor phase
osmometry). A mixture of C23F20O2 (40 mol%) +
C24F22O2 (60 mol%). Calculated, %: C 39.49. M 718.
Perfluoro-5,6-dihydro-7-oxodibenzo[a,h]-azulen-
8-one (XXIII). mp 144.5–146°C (from hexane–CH2Cl2).
UV spectrum (hexane), λmax, nm (log ε): 239 (4.29), 253
(4.06), 261 (4.05), 285 (3.68), 333 (3.49), 400 (2.94). IR
spectrum (KBr), ν, cm–1: 1745 (C=O), 1526, 1510, 1488
(fluorinated aromatic ring). 19F NMR spectrum (CH2Cl2),
δ, ppm: 90.2 (1F, FA) and 85.5 (1F, FB, CF26), 59.0 (1F,
FA) and 44.3 (1F, FB, CF25), 34.1 d.m (1F, F1), 28.2 (1F,
F9), 25.8 d.m (1F, F4), 22.3 (1F, F12), 20.0 (1F, F11), 15.9
CF3 ), 29.9 (1F, F6), 27.5 (1F, F3'), 26.3 (1F, F3), 24.1
2
m (2F, F2 3), 11.3 (1F, F10); J(FF), Hz: J1,12 46, J4,5B 95,
(1F, F4), 22.4 (1F, F6'), 17.3 (1F, F5'), 16.0 (1F, F5), 14.7
(1F, F4'); J(FF), Hz: J2,2' 2, J2,3 5, J2,6' 3, J2',3' 17, J3,4 22,
J3,5 7, J3,6 12, J4,5 19, J4,6 12, J5,6 22, J3',4' 21, J3',5' 9, J3',6'
11, J4',5' 20, J4',6' 6, J5',6' 22. Found, %: C 39.90; F 53.96.
'
J5A,5B 282, J5A,6A 20, J5A,6B 14, J5B,6A 11, J5B,6B 15, J6A,6B
152, J9,10 21, J9,11 11, J9,12 13, J10,11 16, J10,12 5, J11,12 20.
Found:[M]+ 463.9700. C17F12O2. Calculated: M 463.9707.
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ZONOV et al.
214
Reaction of perfluorophthalane (XXIV) with SbF5.
Perfluoro-3-ethylphthalide (XXVI). mp 29–31°C
(from hexane). UV spectrum (hexane), λmax, nm (log ε):
231 (3.80), 283 (3.35). IR spectrum (CCl4), ν, cm–1: 1846
(C=O), 1522, 1507 (fluorinated aromatic ring). 19F NMR
spectrum (CH2Cl2), δ, ppm: 82.4 (3F, CF3), 40.1 (1F,
F3), 39.2 (1F, FA) and 37.5 (1F, FB, CF2), 30.4 (1F, F4),
29.0 (1F, F7), 25.2 (1F, F5), 20.3 (1F, F6); J(FF), Hz: JA,B
287, JA,3 3, JB,3 11, JA,4 13, JB,4 37, J(CF3, F3) 9, J3,4 4,
J3,6 4, J4,5 20, J4,6 9, J4,7 18, J5,6 18, J5,7 12, J6,7 20. Found:
[M]+ 341.9747. C10F10O2. Calculated: M 341.9739.
A mixture of 0.32 g (1.19 mmol) of compound XXIV
and 1.5 g (6.93 mmol) of SbF5 was stirred for 2 h at
20°C, then treated with 5% HCl, extracted with CH2Cl2,
the extract was dried with MgSO4, transferred to a watch
glass; we obtained 0.22 g (70%) of 6-trifluoromethyl-
2,3,4,5-tetrafluorobenzoic acid (XVIII).
Reaction of perfluorotetralin-1,4-dione (IX) with
SbF5. a. A solution of 0.76 g (2.5 mmol) of compound
IX in 3.3 g (15.24 mmol) of SbF5 was heated for 20 h at
130°C, then treated with 5% HCl, extracted with ether,
the solvent was distilled off in a vacuum, the residue
was dissolved in CH2Cl2 and dried with MgSO4. On
removing solvent in a vacuum we obtained 0.77 g (96%)
of a mixture containing according to 19F NMR spectrum
compounds V, VIII, XIII, XIV, XXV, XXVI, and XXVII
in a ratio 10:19:8:4:26:12:21.
3-Hydroxyperfluoro-3-ethylphthalide (XXV). To
a solution of 0.5 g (1.46 mmol) of compound XXVI in
5 ml of ether was added 5 ml of 5% HCl, and the mixture
was left standing for 13 days. The ether layer was dried
with MgSO4, transferred to a watch glass, and solvent
was removed. Yield 0.41 g (82%), mp 130.5–131°C (from
hexane–ether). UV spectrum (hexane), λmax, nm (log ε):
228 (3.88), 280 (3.29). IR spectrum (KBr), ν, cm–1: 3342
(OH), 1795, 1773 (C=O), 1522, 1510 (fluorinated
b. A solution of 1 g (3.29 mmol) of compound IX in
4.04 g (18.63 mmol) of SbF5 was heated for 18 h at
180°C, then treated with 5% HCl, extracted with CH2Cl2,
then with ether, and the extracts were dried with MgSO4.
The ether extract was transferred to a watch glass, the
solvent was evaporated, and the residue was sublimed at
130°C (3 mm Hg) to yield 0.07 g (9%) of tetrafluoro-
phthalic acid (XIV). Dichloromethane extract contain-
ing compounds XXV, XXVI, and XXVIII in a ratio
18:68:14 (according to 19F NMR spectrum) was washed
with water solution of NaHCO3, and on distilling off the
solvent in a vacuum we obtained 0.59 g (52%) of
phthalide XXVI, whose analytical sample was prepared
by sublimation at 90°C (30 mm Hg) and recrystallization.
The water layer was acidified with HCl, extracted with
CH2Cl2, the extract was dried with MgSO4, transferred
to a watch glass, the solvent was evaporated to give
0.26 g of a mixture containing compounds XXV and
XXVIII in a ratio 53 : 4 7 (yields 11 and 12%
respectively). By sublimation at 80°C (20 mm Hg) and
recrystallization from hexane we isolated in an individual
state 0.05 g of acid XXVIII, mp 81.5–82.5°C. UV
spectrum (hexane), λmax, nm (log ε): 213 (3.75), 270
(3.30). IR spectrum (CCl4), ν, Cm–1: 3503, 3036 (OH),
1774, 1733 (C=O), 1529, 1483 (fluorinated aromatic
1
aromatic ring). H NMR spectrum (CDCl3), δ, ppm: 4.82
br.s (OH). 19F NMR spectrum (CDCl3), δ, ppm: 82.5 s
(3F, CF3), 39.1 (1F, FA) and 37.7 (1F, FB, CF2), 27.0 (1F,
F4), 26.1 (1F, F7), 21.8 (1F, F5), 16.5 (1F, F6); J(FF), Hz:
JA,B 278, JA,4 14, JB,4 28, J4,5 20, J4,6 7, J4,7 19, J5,6 18,
J5,7 10, J6,7 20. Found: [M]+ 339.9772. C10HF9O3.
Calculated: M 339.9782.
Reaction of perfluorotetralin-1-one (VIII) with
SbF5. a. Into an NMR tube a mixture of 1.18 g
(5.45 mmol) of SbF5 and 0.22 g (0.67 mmol) of com-
pound VIII was placed, SO2ClF was added, and 19F NMR
spectrum was registered containing signals of complex
XII. 19F NMR spectrum (SbF5–SO2ClF), δ (Δδ), ppm:
61.4 (31.2) (1F, F8), 58.2 (33.0) (1F, F6), 57.3 (1.2) (2F,
CF24), 44.9 (9.6) (2F, CF22), 39.5 (10.6) (1F, F5), 31.6 (2.4)
(2F, CF23), 25.1 (6.2) (1F, F7). The solution was treated
with 5% HCl, extracted with CH2Cl2, the extract was
dried with MgSO4, 0.2 g (90%) of tetralone VIII.
b. A solution of 0.97 g (2.96 mmol) of ketone VIII in
2.52 g (11.64 mmol) of SbF5 was heated for 3 h at 130°C,
then it was treated with 5% HCl, extracted with CH2Cl2,
the solvent was distilled off in a vacuum to provide 0.8 g
(82%) of a mixture containing compounds V, VIII, IX,
XXV, and XXVI in a ratio 16:69:8:4:3 (according to 19F
NMR spectrum).
1
ring). H (CCl4), δ, ppm: 10.78 br.s (OH). 19F NMR
spectrum (CCl4), δ, ppm: 81.1 (3F, CF3), 56.2 (2F, CF2α),
36.8 (2F, CF2β), 29.6 (1F, F5), 23.8 (1F, F2), 17.0 (1F, F3),
12.9 (1F, F4); J(FF), Hz: J(CF3, CF2α) 10, J(CF2α, CFβ)
c. A solution of 1.22 g (3.74 mmol) of ketone VIII in
4.25 g (19.6 mmol) of SbF5 was heated for 19 h at 180°C,
then it was treated with 5% HCl and extracted with
CH2Cl2. The extract was washed with water solution of
NaHCO3, and we obtained a solution containing com-
11, J(CF2α, F5) 22, J(CFβ, F5) 22, J2,3 22, J2,4 6, J2,5 121,
2
J3,4 20, J3,5 10, J4,5 20. Found: [M]+ 361.9801.
C10HF11O2. Calculated: M 361.9801.
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REACTION OF PERFLUOROBENZOCYCLOALKENES WITH SIO2−SBF5
215
pounds V, XXVI, XXIX, XXXI, and XXXII in a ratio
39:19:2:29:11 (according to 19F NMR spectrum). The
water layer was acidified with HCl, extracted with
CH2Cl2, the extract was dried with MgSO4,and on
removing the solvent in a vacuum we obtained 0.3 g
(24%) of a mixture containing compounds XVII, XVIII,
XXV, XXVIII, XXX, and XXXIII in a ratio 15:
13:23:29:19:1 (according to 19F NMR spectrum). From
the solution containing non-acid products CH2Cl2 was
distilled off, the residue was dissolved in 7 ml of ether
and hydrolyzed for 10 days by adding 7 ml of 10% HCl.
The ether layer was separated, the solvent was distilled
off in a vacuum, the residue was dissolved in CH2Cl2,
the solution was washed with water solution of NaHCO3,
dried with MgSO4, the solvent was distilled off in
a vacuum, and we obtained 0.26 g (21%) of a mixture
containing compounds V, XXIX, and XXXII in a ratio
74:4:22 (according to 19F NMR spectrum). The water
layer was acidified with HCl, extracted with ether, the
extract was dried with MgSO4, transferred to a watch
glass, and we obtained 0.24 g (19%) of a mixture
containing compounds XXV and XXX in a ratio 40:60
(according to 19F NMR spectrum). The mixture was
additionally sublimed at 110°C (2 mm Hg) and
recrystallized from CCl4.
XVII, XVIII, XXV, XXVIII, XXX, and XXXIII in
a ratio 18 : 13 : 1: 60:3:5 (according to 19F NMR
spectrum) after extraction of the water layer acidified
with HCl.
Reaction of perfluorotetralin (V) with glass in the
presence of SbF5. A mixture of 1.11 g (3.19 mmol) of
tetralin V and 4.83 g (22.28 mmol) of SbF5 was heated
for 31 h at 180°C in a sealed ampule, then it was treated
with 5% HCl, extracted first with CH2Cl2, then with ether,
and the extracts were dried with MgSO4. The ether
extract was transferred to a watch glass, the residue was
sublimed at 130°C (2 mm Hg) to give 0.18 g (24%) of
acid XIV. Dichloromethane extract containing
compounds XXV, XXVI, XXIX, XXX, XXXI, XXXII,
and XXXIII in a ratio 20:40:12:5:9:12:2 (according to
19F NMR spectrum) was dried with MgSO4, the solvent
was distilled off in a vacuum, the residue was dissolved
in 7 ml of ether and hydrolyzed for 10 days by adding 8
ml of 10% HCl. The ether layer was separated, the solvent
was distilled off in a vacuum, the residue was dissolved
in CH2Cl2, the solution was washed with water solution
of NaHCO3, dried with MgSO4, the solvent was distilled
off in a vacuum, and the residue was sublimed at 100°C
(10 mm Hg) to yield 0.07 g (7%) of a mixture containing
compounds XXIX and XXXII in a ratio 53:47 (according
to 19F NMR spectrum). Individual compounds XXIX and
XXXII were isolated by column chromatography on
silica gel (eluent first CCl4, then CHCl3) from the mixture
obtained in several similar runs. The water layer was
acidified with HCl, extracted with ether, the extract was
dried with MgSO4, transferred to a watch glass,
evaporated, and we obtained 0.43 g (40%) of a mixture
containing compounds XXV, XXX, and XXXIII in
a ratio 80:18:2 (according to 19F NMR spectrum).
Perfluoro-3-hydroxy-3-methyl-3,4-dihydroiso-
chromen-1-one (XXX). 1H NMR spectrum (CDCl3), δ,
ppm (for the mixture XXV + XXX): 5.19 br.s (OH).
19F NMR spectrum (CH2Cl2), δ, ppm (for the mixture
XXV + XXX): 82.6 (3F, CF3), 62.3 (1F, FA) and 43.4
(1F, FB, CF2), 31.4 (1F, F8), 25.5 (1F, F5), 22.5 (1F, F6),
16.6 (1F, F7); J(FF), Hz: JA,B 281, J(FA, CF3) 13, J(FB,
CF3) 9, JA,5 7, JB,5 50, JA,6 1, JB,6 1, JA,7 4, JB,8 4, J5,6 21,
J5,7 8, J5,8 13, J6,7 20, J6,8 13, J7,8 20. Found: [M]+ 339.9776.
(XXV + XXX). C10HF9O3. Calculated: M 339.9782.
Perfluoro-3,3-dimethylphthalide (XXIX). mp 57.5–
59°C (from hexane, in a sealed capillary). UV spectrum
(hexane), λmax, nm (log ε): 205 (3.87), 227 (3.96), 233
(3.95), 279 (3.38). IR spectrum (CCl4), ν, cm–1: 1840
(C=O), 1522, 1506 (fluorinated aromatic ring). 19F NMR
spectrum (hexane), δ, ppm: 88.1 (6F, 2CF3), 29.4 (1F,
F4), 28.0 (1F, F7), 23.0 (1F, F5), 17.9 (1F, F6); J(FF), Hz:
J(CF3, F4) 14, J4,5 20, J4,6 8, J4,7 19, J5,6 17, J5,7 11,
J6,7 20. Found: [M]+ 341.9744. C10F10O2. Calculated:
M 341.9739.
6-(2-Oxopentafluoropropyl)-2,3,4,5-tetrabenzoic
acid (XXXVIII). 19F NMR spectrum (for the mixture
XXV+XXX+XXXVIII in ether), δ, ppm: 82.3 (3F, CF3),
61.6 (2F, CF2) 32.6 (1F, F5), 22.8 (1F, F2), 12.1 (1F, F3),
10.1 (1F, F4); J(FF), Hz: J(CF3, CF2) 12, J(CF2, F5) 28,
J
2,3 22, J2,4 5, J2,5 12, J3,4 20, J3,5 8, J4,5 20.
d. Similarly to the previous run from 0.96 g
(2.94 mmol) of tetralone VIII and 5.13 g (23.66 mmol)
of SbF5 (180°C, 80 h) after distilling off the solvent from
dichloromethane extract washed with water solution of
NaHCO3 we obtained 0.4 g (40%) of a mixture containing
compounds V, XXVI, XXIX, XXXI, and XXXII in
a ratio 7:10:9:59:15 (according to 19F NMR spectrum),
and 0.32 g (32%) of a mixture containing compounds
Perfluoro-3-methylisochromen-1-one (XXXII). mp
149–150°C (from hexane). UV spectrum (hexane), λmax
,
nm (log ε): 227 (4.30), 241 (4.03), 248 (4.04), 260 (3.78),
269 (3.77) , 280 (3.59) , 317 (3.56). IR spectrum (CCl4),
ν, Cm–1: 1786 (C=O), 1520, 1495 (fluorinated aromatic
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 2 2008

ZONOV et al.
216
ring). 19F NMR spectrum (CH2Cl2), δ, ppm: 96.1 d [3F,
CF3, J(F4, CF3) 22 Hz], 31.8 m (1F, F8), 22.7–22.1 m
(2F, F5'6), 16.0 m (1F, F7), 9.4 m (1F, F4). Found: [M]+
303.9774. C10F8O2. Calculated: M 303.9771.
3-Hydroxy-3-trifluoromethyl-4,5,6,7,8-penta-
fluoro-3,4-dihydroisochromen-1-one (XXXVI).Amix-
ture of 0.04 g (0.13 mmol) of compound XXXII, 0.1 g
(1.19 mmol) of NaHCO3, 1.5 ml of water, and 5 drops of
ether was stirred for 2 days, acidified with HCl, extracted
with ether, the extract was dried with MgSO4, transferred
to a watch glass, the solvent was evaporated to yield
0.03 g (71%) of compound XXXVI, mp 150–150.5°C
(from hexane). IR spectrum (KBr), ν, cm–1: 3300 (OH),
1766, 1753 (C=O), 1523, 1505 (fluorinated aromatic
ring). Found: [M]+ 321.9888. C10H2F8O3. Calculated:
M 321.9876. 1H NMR spectrum (CDCl3), δ, ppm, isomer
1 (94%): 5.93 d.d [1H, H4, J(H4, F4) 49, J(H4, F8) 2 Hz],
5.38 br.s (1H, OH); isomer 2 (6%): 6.00 d 1H, H4, J(H4,
F4) 48 Hz]. 19F NMR spectrum (CH2Cl2), δ, ppm, isomer
1 (94%): 80.3 (3F, CF3), 30.7 (1F, F8), 21.0 (1F, F5), 20.1
(1F, F6), 14.2 (1F, F7), –18.0 (1F, F4); J(FF), Hz: J(CF3,
F4) 14, J4,5 2, J4,6 2, J4,7 8, J4,8 3, J5,6 21, J5,7 6, J5,8 14,
Reaction of perfluoro-2-isopropyltoluene (XXXIV)
with SiO2–SbF5. A mixture of 0.85 g (2.2 mmol) of
compound XXXIV, 0.07 g (1.16 mmol) of SiO2, and
5.59 g (25.7 mmol) of SbF5 was stirred for 5.5 h at 70°C.
A part of the mixture (25%) was treated with 5% HCl,
extracted with ether, the extract was dried with MgSO4,
transferred to a watch glass, the solvent was evaporated,
and the residue was sublimed at 110°C (5 mm Hg) to
obtain 0.12 g (60%) of acid XXXIII. The remaining
mixture (75%) was heated for 21.5 h at 180°C, then
treated with 5% HCl, extracted with ether, the extract
was dried with MgSO4. Thus we obtained a solution
containing compounds XXIX and XXXIII in a ratio 4:96
(according to 19F NMR spectrum). The solution was
washed with water solution of NaHCO3, transferred to
a watch glass, the residue was sublimed at 110°C (5 mm
Hg) to get 0.52 g (87%) of acid XXXIII.
J
6,7 20, J6,8 12, J7,8 20, J(F4, H4) 49, J(F8, H4) 2; isomer 2
(6%): 81.3 d [3F, CF3, J(CF3, F4) 5 Hz], 30.5 (1F, F8),
22.1 (1F, F5), 20.4 (1F, F6), 14.8 (1F, F7), –25.2 d [1F, F4,
J(F4, H4) 48 Hz]. 19F NMR spectrum (ether), δ, ppm (in
solution isomer 1 + acid XXXIX), acid XXXIX: 79.3 d
[3F, CF3, J(CF3, Fα) 11 Hz], 28.6 m (1F, F5), 23.2 m (1F,
F2), 8.8 m (1F) and 8.5 m (1F, F3'4), –33.7 d.m [1F, Fα,
J(Fα, Hα) 45 Hz].
6-Heptafluoropropyl-2,3,4,5-tetrafluorobenzoyl
fluoride (XXXV). A mixture of 1.03 g (2.85 mmol) of
acid XXVIII, 1 ml (13.9 mmol) of SOCl2, and 2 drops
of DMF was stirred for 17 h at 80OC (bath temperature).
The vacuum distillation gave 0.91 g of acid chloride [bp
92–94°C (20 mm Hg)] that was heated with CsF (2.05 g,
13.49 mmol) for 10.5 h at 205°C. We isolated by
distillation 0.78 g (75%) of acid fluoride XXXV (fluid).
UV spectrum (hexane), λmax, nm (log ε): 211 (3.73), 271
(3.30). IR spectrum (CCl4), ν, cm–1: 1861, 1847 (C=O),
1528, 1484 (fluorinated aromatic ring). 19F NMR
spectrum (CCl4), δ, ppm: 220.0 (1F, COF), 81.4 (3F, CF3),
56.3 (2F, CF2α), 36.6 (2F, CF2β), 30.9 (1F, F5), 26.2 (1F,
F2), 18.2 (1F, F3), 15.7 (1F, F4); J(FF), Hz: J(COF, CF2α)
4, J(COF, CF2β) 9, J(COF, F2) 9, J(CF3, CF2α) 10, J(CF2α,
CF2β) 11, J(CF2α, F5) 22, J(CF2β, F5) 22, J2,3 21, J2,4 7,
J2,5 11, J3,4 20, J3,5 10, J4,5 20. Found: [M]+ 363.9763.
C10F12O. Calculated: M 363.9757.
Perfluoro-3-methyl-3,4-dihydroisochromen-1-one
(XXXI). To 0.5 g (1.47 mmol) of a mixture of
compounds XXV and XXX in a ratio 47:53 was added
0.87 g (7.28 mmol) of SOCl2 and 2 drops of DMF, the
mixture was stirred for 20 h at 80°C (bath temperature).
Excess SOCl2 was distilled off in a vacuum, the residue
(0.5 g) was dissolved in 4.54 g (20.94 mmol) of SbF5
and was heated for 42 h at 70–75°C. Then to the mixture
1.2 ml of CF3COOH was added, the reaction mixture
was treated with 5% HCl, extracted with CHCl3, the
extract was washed with water solution of NaHCO3 and
dried with MgSO4, the solvent was distilled off in a
vacuum, and the residue was sublimed at 80°C (30 mm
Hg) to obtain 0.39 g (77%) of a mixture of compounds
XXVI and XXXI in a ratio 57:43 (according to the data
of GC-MS and 19F NMR spectrum). 19F NMR spectrum
(CH2Cl2), δ, ppm (a mixture of XXVI + XXXI): 83.1
(3F, CF3), 64.9 (1F, FA) and 41.3 (1F, FB, CF2), 37.2 (1F,
F3), 33.4 (1F, F8), 26.9 (1F, F5), 24.6 (1F, F6), 18.5 (1F,
F7); J(FF), Hz: JA,B 289, JA,3 15, JB,3 14, J(FA, CF3) 12,
J(FB, CF3) 10, JA,5 4, JB,5 50, JA,6 1, JB,6 1, JA,7 5, JB,8 4,
J(F3, CF3) 3, J5,6 21, J5,7 9, J5,8 13, J6,7 20, J6,8 14, J7,8 20.
Reaction of 6-heptafluoropropyl-2,3,4,5-tetra-
fluorobenzoyl fluoride (XXXV) with SbF5. A mixture
of 0.68 g (1.87 mmol) of compound XXXV and 6.68 g
(30.81 mmol) of SbF5 was heated for 31 h at 180°C,
then treated with 5% HCl, extracted with a mixture
CHCl3–ether, 3:1, the extract was dried with MgSO4,
transferred to a watch glass, the solvent was evaporated,
and we obtained 0.62 g (61%) of a mixture containing
compounds XXV, XXVI, and XXVIII in a ratio
4:6:90 (according to 19F NMR spectrum).
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REACTION OF PERFLUOROBENZOCYCLOALKENES WITH SIO2−SBF5
217
Found: [M]+ 341.9741 (XXVI + XXXI). C10F10O2.
Calculated: M 341.9739.
Yakobson, G.G., J. Fluor. Chem., 1985, vol. 28, p. 121.
3. Zonov, Ya.V., Karpov, V.M., Platonov, V.E., Rybalova, T.V.,
and Gatilov, Yu.V., J. Fluor. Chem., 2006, vol. 127, p. 1574.
4. Karpov, V.M., Mezhenkova, T.V., Platonov, V.E., and
Sinyakov, V.R., J. Fluor. Chem., 2002, vol. 117, p. 73.
5. Karpov, V.M., Mezhenkova, T.V., Platonov, V.E., and
Yakobson, G.G., Bull. Soc. Shim., 1986, p. 980.
6. Karpov, V.M., Mezhenkova, T.V., and Platonov, V.E., Izv.
Akad. Nauk, Ser. Khim., 1992, p. 1419.
The study was carried out under a financial support
of the Russian Foundation for Basic Research (grant no.
06-03-32170).
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1. Zonov, Ya.V., Karpov, V.M., and Platonov, V.E., J. Fluor.
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7. Ng, S. and Sederholm, C.H., J. Chem. Phys., 1964, vol. 40,
p. 2090.
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