Reaction of perfluoro-1-ethylindan with SiO2/SbF5 and skeletal transformations of perfluoro-3-ethylindan-1-one under the action of SbF5 and SiO2/SbF5

Article abstract of DOI:10.1016/j.jfluchem.2007.05.021

Perfluoro-1-ethylindan heated with excess of SiO₂ in an SbF₅ medium at 75 °C and then treated with water, gives 4-carboxy-perfluoro-3-methylisochromen-1-one. Perfluoro-3-ethylindan-1-one is converted, under the action of SbF₅ at 70 °C, to perfluoro-2-(but-2-en-2-yl)benzoic acid as a mixture of E- and Z-isomers. When the reaction temperature is raised to 125 °C, a solution of salts of perfluoro-3,4-dimethyl-1H-isochromen-1-yl and perfluoro-4-ethyl-1H-isochromen-1-yl cations is obtained. Increase in the reaction time lowers the content of a salt of the latter cation in the solution. Hydrolysis of the solution of the salts gives perfluoro-3,4-dimethylisochromen-1-one and perfluoro-4-ethylisochromen-1-one.

Full text of DOI:10.1016/j.jfluchem.2007.05.021

Journal of Fluorine Chemistry 128 (2007) 1065–1073
www.elsevier.com/locate/fluor
Reaction of perfluoro-1-ethylindan with SiO2/SbF5 and skeletal
transformations of perfluoro-3-ethylindan-1-one under
the action of SbF5 and SiO2/SbF5
*
Yaroslav V. Zonov, Victor M. Karpov , Vyacheslav E. Platonov
N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Novosibirsk 630090, Russia
Received 10 April 2007; received in revised form 23 May 2007; accepted 29 May 2007
Available online 3 June 2007
Dedicated to the Centenary of Academician, Professor N.N. Vorozhtsov, Jr.
Abstract
Perfluoro-1-ethylindan heated with excess of SiO2 in an SbF5 medium at 75 8C and then treated with water, gives 4-carboxy-perfluoro-3-
methylisochromen-1-one. Perfluoro-3-ethylindan-1-one is converted, under the action of SbF5 at 70 8C, to perfluoro-2-(but-2-en-2-yl)benzoic acid
as a mixture of E- and Z-isomers. When the reaction temperature is raised to 125 8C, a solution of salts of perfluoro-3,4-dimethyl-1H-isochromen-
1-yl and perfluoro-4-ethyl-1H-isochromen-1-yl cations is obtained. Increase in the reaction time lowers the content of a salt of the latter cation in
the solution. Hydrolysis of the solution of the salts gives perfluoro-3,4-dimethylisochromen-1-one and perfluoro-4-ethylisochromen-1-one.
# 2007 Elsevier B.V. All rights reserved.
Keywords: Skeletal transformations; Perfluoro-1-ethylindan; Perfluoro-3-ethylindan-1-one; Silicon dioxide; Antimony pentafluoride; NMR spectroscopy
1. Introduction
under the action of SbF5 undergoes five-membered ring
cleavage to form perfluoro-2-ethylbenzoic acid [7].
Perfluorinated benzocyclobutene, indan, tetralin and their
perfluoroalkyl and perfluoroaryl derivatives when heated with
antimony pentafluoride undergo skeletal transformations to
give products of cleavage, expansion or contraction of the
alicyclic ring of benzocycloalkenes [1–4] (see also references
[1–7] cited in article [2]). Thus, perfluoro-1-ethylindan (1)
isomerizes into perfluoro-1,1-dimethylindan and perfluoro-2-
(but-2-en-2-yl)toluene; the latter cyclizes to perfluoro-1,2-
dimethylindan [5]. Perfluoro-1-methylindan, when heated with
SbF5 in a nickel bomb, is transformed to perfluoro-2-
isopropyltoluene [1], and when heated with SbF5 in a glass
ampoule, it reacts with glass as a source of inorganic oxides to
give perfluoro-4-methyl-1H-isochromene [6] (Scheme 1).
Apparently, the reaction with glass proceeds via inter-
mediate formation of perfluoro-3-methylindan-1-one. On the
other hand, we have found that perfluoroindan reacts with SiO2/
SbF5 to give perfluoroindan-1-one in a good yield. The latter
In this connection it was worthwhile to study the reaction of a
number of perfluoroalkylindanes with silica in the presence of
SbF5 and the behaviour of their carbonyl derivatives under the
action of antimony pentafluoride with the aim to study the
possibility of their cationoid skeletal transformations. This work
describes the reactions of ethylindan 1 with SiO2/SbF5 and with
glass in an SbF5 medium and transformations of perfluoro-3-
ethylindan-1-one (2) under the action of antimony pentafluoride.
2. Results and discussion
It has been shown that reaction of ethylindan 1 with
SiO2 (0.6 mol per 1 mol of compound 1) in the presence of
SbF5 at 70 8C gives, after treatment of the reaction mixture with
water, indanone 2 together with 4-fluorocarbonyl-perfluoro-3-
methylisochromen-1-one (3), 4-carboxy-perfluoro-3-methyli-
sochromen-1-one (4) and 5,6,7,8-tetrafluoro-3-hydroxy-3-tri-
fluoromethyl-3,4-dihydroisochromen-1-one (5). The reaction
mixture also contains unchanged compound 1 (Scheme 2).
Reaction of indan 1 with excess of SiO2 in an SbF5 medium at
* Corresponding author. Fax: +7 3832 34 4752.
E-mail address: karpov@nioch.nsc.ru (V.M. Karpov).
0022-1139/$ – see front matter # 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2007.05.021

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(12) and perfluoro-4-ethyl-1H-isochromen-1-yl cations (13) is
obtained. Hydrolysis of the solution of the salts gives
compound 9 and perfluoro-4-ethyl-isochromen-1-one (14).
The reaction mixture also contains acid 8 and 5,6,7,8-
tetrafluoro-3-hydroxy-3,4-bis(trifluoromethyl)-3,4-dihydroiso-
chromen-1-one (15) (Scheme 4). Formation of the latter from
compound 9 will be discussed below (Scheme 6).
Scheme 1.
75 8C forms a solution of a salt of 4-fluorocarbonyl-perfluoro-
3-methyl-1H-isochromen-1-yl cation (6). Hydrolysis of the
latter gives acid 4. The reaction of indan 1 with excess of SiO2/
SbF5 at 130 8C forms compound 4 together with tetrafluor-
ophthalic acid (7) (Scheme 2).
These data indicate that ketone 2 undergoes further
transformations under the reaction conditions of ethylindan 1
with SiO2/SbF5. Apparently, it may be connected with skeletal
transformations of compound 2 in the presence of antimony
pentafluoride. Ketone 2 was synthesized under milder
conditions by reaction of ethylindan 1 with CF3COOH in
the presence of SbF5 at room temperature [9] and behaviour of
ketone 2 in an SbF5 medium was investigated.
Heating ketone 2 with SbF5 at 70 8C (7 h) gives, after
treatment of the reaction mixture with water, perfluoro-2-(but-
2-en-2-yl)benzoic acid (8) as a mixture of E- and Z-isomers
together with small amounts of perfluoro-3,4-dimethylisochro-
men-1-one (9). The reaction mixture also contains unchanged
compound 2 (Scheme 3).
Transformation of indanone 2 in the presence of SbF5 to the
acid 8 may be represented by Scheme 3. At first, compound 2
with SbF5 seems to generate the cation 2c. The five-membered
ring of the latter may undergo ring opening to yield the benzoyl
type ion 10, which undergoes isomerization with removal of the
double bond inside the chain to form fluoroanhydride 11.
Hydrolysis of the latter gives acid 8. This scheme is analogous
to that for five-membered ring opening of ethylindan 1 under
the action of antimony pentafluoride [5].
The probable mechanism for the transformation of indanone
2 in the presence of SbF5 to salts of cations 12 and 13 can be
formulated as shown in Scheme 4. At first ketone 2 isomerizes
into fluoroanhydride 11 (Scheme 3). Then an allyl type cation
16 is generated from compound 11 under the action of
antimony pentafluoride. An intramolecular attack of one or
another positively charged carbon atom of the allyl system of
cation 16 at the fluorocarbonyl oxygen atom gives cations 17
and 18. These ions undergo isomerization with removal of the
double bond inside the cycle to form cations 12 and 13.
The mixture of compounds 9 and 14, obtained in the reaction
of ketone 2 with SbF5 at 125 8C (7 h), apparently, is a result of
kinetic control of the reaction. Indeed, increase in the reaction
time (130 8C, 57 h) led, after treatment of the reaction mixture
with water, to the formation of the mixture, which did not
contain compound 14 (Scheme 4). It may be explained in the
following way. The isomerization of cations 12 and 13 one to
another seems to be reversible, with the equilibrium shifted
towards the thermodynamically more stable cation 12, that
makes it possible to convert cation 13 to cation 12.
Consider possible routes of reaction between ethylindan 1
and SiO2/SbF5 (Scheme 5). At first cation 1c is generated from
indan 1 and SbF5. Then cation 1c reacts with SiO2 to form
indanon 2 analogously to the formation of perfluoroindan-1-
one in the reaction of perfluoroindan with SiO2/SbF5 [7].
The interaction of ketone 2 with SbF5 generates cation 16
(its formation was discussed above, Scheme 4), which reacts
with SiO2 to give cation 19. Intramolecular cyclization of the
latter forms cation 20, which isomerizes to produce cation 6.
When the reaction temperature is raised to 125 8C (7 h), a
solution of salts of perfluoro-3,4-dimethyl-1H-isochromen-1-yl
Scheme 2.

Y.V. Zonov et al. / Journal of Fluorine Chemistry 128 (2007) 1065–1073
1067
Scheme 3.
Scheme 4.
Scheme 5.

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Y.V. Zonov et al. / Journal of Fluorine Chemistry 128 (2007) 1065–1073
Scheme 6.
Hydrolysis of the latter gives compound 3. It has been shown in
a separate experiment that compound 3 is not the product of the
reaction of a salt of cation 6 with SiO2/SbF5.
of the latter with oleum forms 5,6,7,8-tetrafluoro-3-trifluor-
omethylisochromen-1-one (22).
Compound 15 under the action of NaHCO3 in two-phase
system H2O–CHCl3 gives a mixture of compounds 3, 5 and
perfluoro-4-acetylisochromen-1-one (23). The probable routes
for these transformations and for the reaction of compound 9
with K2CO3 can be formulated as shown in Scheme 6. At first
both compounds 9 and 15 form acid 24. The latter is
transformed to acid 21, which gives compound 5. On the other
hand, one fluorine atom of CF2 group of acid 24 is substituted
by OH to give finally compound 25a, which produces
delocalised anion 26. An intramolecular attack of one or
another negatively charged oxygen atom of conjugated system
of anion 26 at the carbon atom of the carboxyl group gives
compounds 3 and 23. It is also possible that anion 27 generated
in the reaction with NaHCO3 from acid 24 undergoes
intramolecular cyclization to form compound 23. Also that
dehydration of compound 25 under the reaction conditions
gives product 3, cannot be excluded.
The alternative mechanism for the transformation of
indanone 2 to a salt of 6 under the action of SiO2/SbF5, which
includes interaction of products of cyclization of cation 16
(Scheme 4) with SiO2, seems unlikely, because the reaction of
compound 1 with SiO2/SbF5 proceeds at 70 8C, while the
reaction of ketone 2 with SbF5 leading to the formation of a salt
of cation 12 (Scheme 4) at this temperature proceeds very
slowly. In addition, it was shown that a salt of cation 12
practically does not react with SiO2 even at 125 8C.
Some amounts of compound 15 were obtained in the
reaction of ethylindanone 2 with SbF5 (Scheme 4). It has been
shown by a separate experiment that compound 15 is formed in
the reaction of compound 9 with water in an acidic medium.
Compound 9, when treated with aqueous solution of potassium
carbonate, is transformed to compound 5. The latter is also
formed in the reaction of acid 4 with water in an alkaline
medium as well as in an acidic (Scheme 6).
Consider the reaction of ethylindan 1 with a glass in an SbF5
medium. Heating compound 1 with antimony pentafluoride at
130 8C in a sealed ampoule with further treatment of the
reaction mixture with water leads to compounds 3, 4, 5, 9, 15.
Apparently, the reaction of acid 4 with water proceeds via
intermediate formation of b-keto acid 21 that is decarboxylated
to give compound 5 (at the bottom of Scheme 6). Dehydration

Y.V. Zonov et al. / Journal of Fluorine Chemistry 128 (2007) 1065–1073
1069
Scheme 7.
The mixture also contains perfluoro-1,1-dimethylindan (28),
Signals at 5.20 ppm (OH, 1H NMR) and at 97.6 ppm (C-3, 13
C
NMR) testify that compound 5 in CDCl3 solution has cyclic
structure. 1H NMR spectrum of compound 15 (CDCl3) contains
two signals of groups OH at 4.72 and at 5.15 ppm relating to
two isomers of cyclic form of compound 15 (E:Z ꢀ 65:35).
According to the 19F NMR spectra, ether solution of compound
5 contains cyclic 5 and open-chain 5a forms in the ratio 80:20,
respectively. In the case of ether solution of compound 15
(E:Z ꢀ 70:30) the content of open-chain form 15a is not more
than 2%.
perfluoro-3,3-dimethylindan-1-one (29) and perfluoro-2,3-
dimethyl-4,5,6,7-tetrahydro-1H-indene (30) (Scheme 7).
The probable routes for the transformations of ethylindan 1
under the action of glass/SbF5 can be formulated as shown in
Scheme 7. On heating with SbF5 at 130 8C in a nickel bomb,
ethylindan 1 gives compounds 28, 30, 31 and 32 [5]. One can
assume that compounds 1, 28, 31 and 32 react with glass/SbF5,
similar to the reaction of ethylindan 1 with SiO2/SbF5, to
produce carbonyl derivatives 2, 29, 11. Ethylindanone 2, as well
as compound 11 under the action of antimony pentafluoride
forms a salt of cation 12. Moreover, compound 11 under the
action of glass/SbF5 produces a salt of cation 6. As it was
mentioned above, hydrolysis of salts of cations 6 and 12 gives
compounds 3, 4, 5, 9 and 15.
The structures of E- and Z-isomers of acid 8 were defined on
the base of the JCF ðaÞꢁCF ðbÞ values, which is equal to 11 Hz for
3
3
E-isomer and less than 2 Hz for Z-isomer [8]. The structures of
E- and Z-isomers of compound 15 were defined on the base of
the JCF ð3ÞꢁCF ð4Þ values, which is equal to 10 Hz for E-isomer
3
3
Formally, compounds 5 and 15 could exist as cyclic 5 and 15
or/and open-chain 5a and 15a forms, respectively (Scheme 8).
and less than 2 Hz for Z-isomer.
3. Experimental
IR spectra were taken on a Bruker Vector 22 IR spectro-
photometer. UV spectra were measured on a Hewlett Packard
1
8453 UV spectrophotometer. 19F NMR and H spectra were
recorded on a Bruker WP-200 SY and AC-200 instrument
(188.3 and 200 MHz, respectively) whereas 13C NMR
spectrum of the compound 5 was recorded on a Bruker AM-
400 instrument (100.6 MHz). Chemical shifts are given in d
ppm from CCl3F (19F) and TMS (1H and 13C), J values in Hz;
C6F6 and SO2ClF (ꢁ162.9 and 99.9 ppm from CCl3F),
(Me3Si)2O, CHCl3 (0.04 and 7.24 ppm from TMS) and CDCl3
(76.9 from TMS) were used as internal standards. The
molecular masses of the compounds were determined by
Scheme 8.

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Y.V. Zonov et al. / Journal of Fluorine Chemistry 128 (2007) 1065–1073
high-resolution spectrometry on a Finnigan Mat 8200 instru-
ment (EI 70 eV). Contents (yields) of products in the reaction
mixtures were established by 19F NMR spectroscopic data.
The structures of the compounds were established by
elemental analysis, HRMS and spectral characteristics. Assign-
ment of signals in the 19F NMR spectra of the compounds and
cations 6, 12 and 13 was made on the basis of chemical shifts of
the signals, their fine structure and integral intensities.
Compounds 2, 29 [9], 28, 30 [5] were identified by comparison
of the 19F NMR data with data for authentic samples.
Antimony pentafluoride was obtained commercially, SiO2
was prepared by heating of commercial silica gel at 400–
450 8C, ethylindan 1 was obtained according to reference [10].
The reactions were carried out in glassware, unless otherwise
specified.
F-6), ꢁ150.1 (1F, F-7); J5,6 = 20, J5,7 = 5, J5,8 = 14,
J6,7 = 20, J6,8 = 12, J7,8 = 20. Anal. Calcd for C11HF7O4:
C, 40.0; H, 0.3; F, 40.3. Found: C, 39.8; H, 0.2; F, 40.7%.
3. A mixture of compound 1 (0.61 g), SiO2 (0.08 g) and SbF5
(3.35 g) (molar ratio, 1:0.9:10) was stirred at 100 8C (1.5 h)
and then at 115 8C (3 h). SO2ClF was added to the resulting
mixture at ꢁ15 8C and 19F NMR spectrum of the solution
was measured at +20 8C. The spectrum contained signals of
cation 6. The solution was poured into 5% hydrochloric acid
and extracted with ether. The extract was dried over MgSO4.
The solvent was distilled off and the residue was sublimed
(160 8C, 1 Torr) to give 0.43 g (yield 85%) of acid 4.
4-Fluorocarbonyl-perfluoro-3-methyl-1H-isochromen-1-
yl cation (6): 19F NMR (SbF5–SO2FCl): d 60.2 (1F, COF),
ꢁ7.3 (1F, F-1), ꢁ63.6 (3F, s, CF3), ꢁ100.1 (1F, F-6), ꢁ107.8
(1F, F-8), ꢁ125.5 (1F, F-5), ꢁ129.4 (1F, F-7); J1,5 = 4,
3.1. Reaction of perfluoro-1-ethylindan (1) with SiO2/SbF5
J
J
1,6 = 9, J1,8 = 81, JCOF–F(5) = 12, J5,6 = 19, J5,7 = 13,
5,8 = 12, J6,7 = 20, J6,8 = 31, J7,8 = 18.
1. A mixture of compound 1 (1.50 g), SiO2 (0.14 g) and SbF5
(1.24 g) (molar ratio, 1:0.6:1.5) was stirred at 70 8C for 5 h.
The mixture was poured into 5% hydrochloric acid and
extracted with CH2Cl2. The extract was dried over MgSO4.
The solvent was distilled off to give 1.20 g of mixture, which
contained 40% of 1, 24% (yield 21%) of 2, 29% (25%) of 3,
3% (2%) of 4 and 4% (3%) of 5. The mixture was
spontaneously evaporated in the air to dryness to give 0.39 g
of a mixture of compounds 3, 4 and 5, which was dissolved in
CH2Cl2 and washed with aqueous solution of NaHCO3 and
dried over MgSO4. The solvent was distilled off to give
0.22 g of compound 3. An analytical sample of compound 3
was prepared by crystallization.
4. A mixture of compound 1 (0.65 g), SiO2 (0.15 g) and SbF5
(3.56 g) (molar ratio, 1:1.5:10) was stirred at 75–80 8C for
7 h. SO2ClF was added to the mixture at ꢁ15 8C and 19F
NMR spectrum of the solution was measured at +20 8C. The
spectrum contained poorly-resolved signals of cation 6.
Then compound 3 (0.07 g) was added to the solution. 19F
NMR spectrum of the resulting solution contained some
extra signals as compared with the previous spectrum. The
solution was poured into 5% hydrochloric acid and extracted
with ether. The extract was dried over MgSO4. The solvent
was distilled off and the residue was sublimed (160 8C,
1 Torr) to give 0.52 g (yield 85%) of acid 4.
5. A mixture of compound 1 (0.71 g), SiO2 (0.32 g) and SbF5
(3.87 g) (molar ratio, 1:3:10) was stirred at 90 8C (2 h) and
then at 130 8C (11 h). The mixture was treated with 5%
hydrochloric acid and extracted with ether. The extract was
dried over MgSO4. The ether was distilled off and the residue
was sublimed (160 8C, 2 Torr) to give 0.38 g of a mixture,
which contained compounds 4 and 7 in the ratio 52:48 (yield
39 and 36%, respectively).
4-Fluorocarbonyl-perfluoro-3-methylisochromen-1-one
(3): mp 86.5–87.5 8C (hexane–CH2Cl2). UV (hexane) lmax
,
nm (lg e): 226 (4.36), 267 (3.76), 310 (3.60). IR (CCl4) n,
cmꢁ1: 1854, 1797 (C O); 1519, 1492 [fluorinated aromatic
ring (FAR)]. 19F NMR (CH2Cl2): d 56.5 (1F, COF), ꢁ68.3
(3F, s, CF3), ꢁ129.1 (1F, F-8), ꢁ137.3 (1F, F-5), ꢁ139.5 (1F,
F-6), ꢁ146.2 (1F, F-7); JCOF–F(5) = 12, J5,6 = 20, J5,7 = 6,
J5,8 = 14, J6,7 = 20, J6,8 = 14, J7,8 = 20. HRMS m/z,
331.9719 (M+). Calcd for C11F8O3 = 331.9720.
3.2. Reaction of perfluoro-1-ethylindan (1) with glass in
the presence of SbF5 at 130 8C
2. Analogously to the previous procedure, a mixture of
ethylindan 1 (1.29 g), SiO2 (0.39 g) and SbF5 (2.46 g)
(molar ratio, 1:2:3.5) was heated at 75 8C (6.5 h). The
mixture was treated with 5% hydrochloric acid and extracted
with ether. The extract was dried over MgSO4. The ether
solution contained compounds 3, 4 and 5 in the ratio 6:90:4.
The solvent was distilled off and the residue was sublimed
(140 8C, 1 Torr) to give 0.87 g of mixture, which contained
compounds 4, 5 and 22 in the ratio 87:5:8 (yield 71, 4 and
6%, respectively). An analytical sample of acid 4 was
prepared by crystallization.
A mixture of compound 1 (1.35 g) and SbF5 (3.67 g) (molar
ratio, 1:5) in a sealed ampoule was heated at 130 8C for 49 h.
The mixture was treated with 5% hydrochloric acid and
extracted with CHCl3 and then with ether. The extracts were
dried over MgSO4. The ether solution contained compounds 4
and 5 in the ratio 66:34 and the chloroform solution contained
compounds 3, 4, 5, 9, 15, 28, 29 and 30 in the ratio
12:11:4:22:14:9:11:17, respectively. The CHCl3 extract was
washed with aqueous solution of NaHCO3 and dried over
MgSO4. The solvent was distilled off to give 0.84 g of mixture,
which contained 18% (yield 12%) of 3, 29% (19%) of 9, 6%
(4%) of 23, 11% (7%) of 28, 15% (10%) of 29 and 21% (14%)
of 30. The aqueous solution was acidified with HCl, extracted
with ether and dried over MgSO4. The solution contained
compounds 4 and 5 in the ratio 27:73. Then it was combined
4-Carboxy-perfluoro-3-methylisochromen-1-one (4): mp
192.5–194.5 8C (CCl4). UV (hexane) lmax, nm (lg e): 220
(4.33), 317 (3.64). IR (KBr) n, cmꢁ1: 3501, 3208 (OH);
1762, 1743 (C O); 1520, 1492 (FAR). 1H NMR [(CD3)CO–
CCl4]: d 11.05 (s, OH). 19F NMR [(CD3)CO–CCl4]: d ꢁ68.5
(3F, s, CF3), ꢁ131.8 (1F, F-8), ꢁ138.4 (1F, F-5), ꢁ143.5 (1F,

Y.V. Zonov et al. / Journal of Fluorine Chemistry 128 (2007) 1065–1073
1071
with the previous ether extract, the solvent was distilled off and
the residue was sublimed (190 8C, 2 Torr) to give 0.24 g of
mixture, which contained compounds 4, 5 and 22 in the ratio
38:42:20 (yield 9, 10 and 5%, respectively).
Perfluoro-4-ethyl-1H-isochromen-1-yl cation (13): 19F
NMR (SbF5–SO2ClF): d –14.5 (1F, F-1), ꢁ60.9 (1F, F-3),
ꢁ82.0 (3F, CF3), ꢁ97.6 (1F, F-6), ꢁ104.5 (2F, CF2), ꢁ109.8
(1F, F-8), ꢁ119.6 (1F, F-5), ꢁ136.3 (1F, F-7); J1,3 = 10,
J
1,5 = 4, J1,6 = 10, J1,8 = 94, JCF ꢁFð3Þ ¼ 6, JCF ꢁFð5Þ ¼ 23,
3
3
3.3. Reaction of perfluoro-3-ethylindan-1-one (2) with
SbF5
JCF ꢁFð3Þ ¼ 41, JCF ꢁFð5Þ ¼ 75, J3,7 = 6, J5,6 = 20, J5,7 = 12,
2
2
J
5,8 = 12, J6,7 = 20, J6,8 = 30, J7,8 = 19.
Perfluoro-4-ethylisochromen-1-one (14): mixture with
1. A mixture of compound 2 (0.33 g) and SbF5 (1.14 g) (molar
ratio, 1:6) was heated at 70 8C for 7 h. Then C6F6 (0.6 ml)
was added and the mixture was poured into 5% hydrochloric
acid and extracted with CH2Cl2. The extract was dried over
MgSO4. The solvent and C6F6 were distilled off to give
0.21 g of mixture, which contained 2% of 2, 75% (yield
48%) of Z-8, 21% (13%) of E-8, and 2% (1%) of 9.
Sublimation (120 8C, 20 Torr) of the mixture gave 0.05 g of
liquid products and 0.16 g of solid products. From the latter
fraction 0.08 g of acid 8 (E:Z ꢀ 9:91) was obtained by the
single crystallization from hexane.
isomer 9, ratio 9:14 ꢀ 84:16: IR (CCl4) n, cmꢁ1: 1799
(C O); 1518, 1485 (FAR). Compound 14: 19F NMR
(CH2Cl2): d ꢁ66.1 (1F, F-3), ꢁ83.8 (3F, CF3), ꢁ105.6
(2F, CF2), ꢁ130.9 (1F, F-8), ꢁ131.9 (1F, F-5), ꢁ139.3 (1F,
F-6), ꢁ152.6 (1F, F-7); JCF ꢁCF ¼ 2, JCF ꢁFð3Þ ¼ 10,
3
2
3
JCF ꢁFð5Þ ¼ 24, JCF ꢁFð3Þ ¼ 38, JCF ꢁFð5Þ ¼ 72, J3,5 = 5,
3
2
2
J
J
3,6 = 2, J3,7 = 5, J3,8 = 3, J5,6 = 19, J5,7 = 5, J5,8 = 13,
6,7 = 21, J6,8 = 14, J7,8 = 21. HRMS (mixture of 9 and
14) m/z, 353.9745 (M+). Calcd for C11F10O2 = 353.9739.
3. Analogously to the previous experiments, a solution of
compound 2 (0.13 g) in SbF5 (0.74 g) (molar ratio, 1:10) was
prepared and heated at 125 8C. In 35 h the solution contained
(19F NMR) cations 6, 12 and 13 in the ratio 8:80:12 and in
70 h the ratio of the cations became 8:90:2, respectively.
Then 0.03 g of SiO2 was added to the solution and the
mixture was heated at 125 8C for 16 h. 19F NMR spectrum of
the mixture was measured at +20 8C. The spectrum mainly
contained ill-resolved signals of cation 12. The mixture was
treated with 5% hydrochloric acid and extracted with
CH2Cl2. The extract was dried over MgSO4. The solvent was
distilled off to give 0.08 g of mixture, which contained
compounds 4 and 9 in the ratio 13:87 (yield 9 and 58%,
respectively).
Perfluoro-2-(but-2-ene-2-yl)benzoic acid (8): mixture of
two isomers, ratio E:Z ꢀ 9:91: mp 70–82 8C (hexane). UV
(hexane) lmax, nm (lg e): 211 (3.95), 224 (3.88), 277 (3.38).
IR (CCl4) n, cmꢁ1: 3505, 3054 (OH), 1752, 1717 (C O);
1
1523, 1481 (FAR). H NMR (CCl4): d 11.42 (s, OH). E-
isomer: 19F NMR (CCl4): d ꢁ58.9 (3F, CF3-a), ꢁ69.7 (3F,
CF3-b), ꢁ107.2 (1F, F-b), ꢁ131.3 (1F, F-6), ꢁ135.5 (1F, F-
3), ꢁ145.9 (1F, F-4), ꢁ149.1 (1F, F-5); JFðbÞꢁCF ðbÞ ¼ 7,
3
JFðbÞꢁCF ðaÞ ¼ 11,
JF(b)–F(3) = 3,
JCF ðaÞꢁFð3Þ ¼ 3, J3,4 = 22, J3,5 = 6, J3,6 = 12, J4,5 = 20,
JCF ðbÞꢁCF ðaÞ ¼ 11,
3
3
3
3
J
4,6 = 10, J5,6 = 21.
Z-isomer: 19F NMR (CCl4): d ꢁ62.4 (3F, CF3-a), ꢁ70.5
(3F, CF3-b), ꢁ110.1 (1F, F-b), ꢁ131.4 (1F, F-6), ꢁ134.9 (1F,
4. A mixture of compound 2 (1.03 g) and SbF5 (5.93 g)
(molar ratio, 1:10) was heated in a nickel bomb at 130 8C
for 57 h. The mixture was poured into 5% hydrochloric
acid and extracted with CHCl3. The extract was dried over
MgSO4. The solution contained compounds 3, 4, 5, 9 and
15 in the ratio 3:4:2:61:30. The extract was washed with
aqueous solution of NaHCO3 and dried over MgSO4.
The solvent was distilled off and the residue was sublimed
(100 8C, 5 Torr) to give 0.56 g of mixture, which
contained compounds 3, 9 and 23 in the ratio 8:75:17
(yield 5, 44 and 10%, respectively). An analytical
sample of compound 9 was prepared by crystallization.
The aqueous solution was acidified with HCl, extracted
with ether and dried over MgSO4. The solvent was
distilled off to give 0.13 g of mixture, which contained
compounds 4 and 5 in the ratio 18:82 (yield 3 and 13%,
respectively).
F-3), ꢁ146.0 (1F, F-4), ꢁ148.3 (1F, F-5); JFðbÞꢁCF ðbÞ ¼ 8,
3
JFðbÞꢁCF ðaÞ ¼ 18, JF(b)–F(3) = 3, JCF ðaÞꢁFð3Þ ¼ 2, J3,4 = 22,
3
3
J3,5 = 6, J3,6 = 12, J4,5 = 20, J4,6 = 10, J5,6 = 21. HRMS
(mixture of E and Z-isomers) m/z, 373.9799 (M+). Calcd
for C11HF11O2 = 373.9801.
2. A mixture of compound 2 (0.21 g) and SbF5 (0.94 g) (molar
ratio, 1:7.8) in an ampoule with TeflonTM FEP inliner for
recording of NMR spectra was heated at 125 8C for 7 h. Then
SO2ClF (0.20 g) was added to the mixture at ꢁ15 8C and 19
F
NMR spectrum of the solution was measured at +20 8C. The
spectrum contained signals of cations 12 and 13 in the ratio
82:18. The solution was poured into 5% hydrochloric acid
and extracted with CH2Cl2. The extract was dried over
MgSO4. The solution contained compounds 8, 9, 14 and 15
in the ratio 10:62:13:15. The extract was washed with
aqueous solution of NaHCO3 and dried over MgSO4. The
solvent was distilled off and the residue was sublimed
(100 8C, 2 Torr) to give 0.12 g (yield 61%) of mixture, which
contained compounds 9 and 14 in the ratio 84:16.
Perfluoro-3,4-dimethylisochromen-1-one (9): mp 97–
98 8C (hexane–CH2Cl2). UV (hexane) lmax, nm (lg e):
225 (4.34), 266 (3.78), 309 (3.59). IR (CCl4) n, cmꢁ1: 1799
(C O); 1518, 1485 (FAR). 19F NMR (CH2Cl2): d ꢁ57.1 (3F,
CF3-4), ꢁ65.2 (3F, CF3-3), ꢁ130.5 (1F, F-5), ꢁ131.2 (1F, F-
8), ꢁ139.7 (1F, F-6), ꢁ147.5 (1F, F-7); JCF ð3ÞꢁCF ð4Þ ¼ 14,
Perfluoro-3,4-dimethyl-1H-isochromen-1-yl cation (12):
19F NMR (SbF5–SO2ClF): d ꢁ9.3 (1F, F-1), ꢁ55.3 (3F, CF3-
4), ꢁ60.2 (3F, CF3-3), ꢁ99.3 (1F, F-6), ꢁ108.2 (1F, F-8),
ꢁ116.7 (1F, F-5), ꢁ130.9 (1F, F-7); J1,5 = 4, J1,6 = 9,
3
3
JCF ð4ÞꢁFð5Þ ¼ 42, J5,6 = 19, J5,7 = 8, J5,8 = 13, J6,7 = 21,
3
J
J
1,8 = 92, JCF ð3ÞꢁCF ð4Þ ¼ 14, JCF ð4ÞꢁFð5Þ ¼ 46, J5,6 = 20,
J
6,8 = 13, J7,8 = 21. HRMS m/z, 353.9735 (M+). Calcd for
C11F10O2 = 353.9739.
3
3
3
5,7 = 16, J5,8 = 11, J6,7 = 20, J6,8 = 31, J7,8 = 20.

1072
Y.V. Zonov et al. / Journal of Fluorine Chemistry 128 (2007) 1065–1073
3.4. Hydrolysis of 4-carboxy-perfluoro-3-
methylisochromen-1-one (4) and perfluoro-3,4-
dimethylisochromen-1-one (9)
2,3,4,5-Tetrafluoro-6-(3,3,3-trifluoro-2-oxopropyl)ben-
zoic acid (5a): 19F NMR (ether), mixture with cyclic form 5,
ratio 5:5a ꢀ 80:20: d ꢁ85.8 (3F, CF3), ꢁ135.6 (1F, F-5),
ꢁ138.4 (1F, F-2), ꢁ153.8 (1F, F-4), ꢁ157.6 (1F, F-3);
JCH ꢁFð5Þ ¼ 2, JCF ꢁFð5Þ ¼ 1, J2,3 = 22, J2,4 = 5, J2,5 = 12,
1. To a solution of acid 4 (0.19 g) in 5 ml of ether 5 ml of 5%
hydrochloric acid was added and the mixture was stirred at
20 8C for 26 days. Ether solution was separated and dried over
MgSO4. Thesolventwasdistilledofftogive 0.16 gofmixture,
which contained 66% of 4 and 34% (yield 29%) of 5.
2. Analogously to procedure (1), from 0.12 g of compound 9
(20 8C, 4 d) 0.11 g of compound 15 (E:Z ꢀ 65:35) was
obtained (yield 87%).
2
3
J
3,4 = 20, J3,5 = 4, J4,5 = 21.
4. Analogously to the previous procedure, from compound 9
(0.06 g) and K2CO3 (0.09 g) (molar ratio, 1:3.8) stirred with
2 ml of H2O and 15 drops of ether (16 8C, 21 h) 0.05 g of
compound 5 was obtained (yield 97%).
3.5. Perfluoro-4-acetylisochromen-1-one (23)
5,6,7,8-Tetrafluoro-3-hydroxy-3,4-bis(trifluoromethyl)-
3,4-dihydroisochromen-1-one (15): mixture of two isomers,
ratio E:Z ꢀ 65:35: mp 133–139 8C (CH2Cl2). UV (hexane)
A solution of compound 15 (0.34 g) in 10 ml of CHCl3 was
washed with aqueous solution of NaHCO3 and dried over
MgSO4. The solution contained compound 3 and 23 in the ratio
12:88. The solvent was distilled off and the residue was
sublimed (110 8C, 10 Torr) to give 0.16 g (yield 50%) of
mixture, which contained 26% of 3 and 74% of 23. The aqueous
solution was acidified with HCl and extracted with ether. The
extract was dried over MgSO4. The solvent was distilled off to
give 0.11 g (yield 37%) of compound 5.
lmax, nm (lg e): 212 (4.00), 230 (3.82), 284 (3.52), 316
(2.93). IR (CCl4) n, cmꢁ1: 3388 (OH); 1770 (C O); 1523,
1
1502 (FAR). E-isomer: H NMR (CDCl3): d 4.72 (1H, s,
OH), 4.38 (1H, q, JH(4)–CF3(4) = 7, H-4). 19F NMR (CDCl3): d
ꢁ67.6 (3F, CF3-4), ꢁ83.3 (3F, CF3-3), ꢁ132.6 (1F, F-8),
ꢁ139.5 (1F, F-5), ꢁ142.6 (1F, F-6), ꢁ150.4 (1F, F-7);
JCF ð3ÞꢁCF ð4Þ ¼ 10, JCF ð4ÞꢁHð4Þ ¼ 7, JCF ð4ÞꢁFð5Þ ¼ 8, JF(5)–
3
3
3
3
H(4) = 1, J5,6 = 20, J5,7 = 5, J5,8 = 14, J6,7 = 20, J6,8 = 12,
Perfluoro-4-acetylisochromen-1-one (23): mixture with
isomer 3, ratio 3:23 ꢀ 26:74: IR (CCl4) n, cmꢁ1: 1854,
1815, 1800, 1760 (C O); 1515, 1494 (FAR). Compound 23:
19F NMR (CH2Cl2): d ꢁ71.7 (1F, F-3), ꢁ77.8 (3F, CF3),
ꢁ130.7 (1F, F-8), ꢁ137.7 (1F, F-5), ꢁ139.9 (1F, F-6), ꢁ152.4
(1F, F-7); JCF ꢁFð3Þ ¼ 8, JCF ꢁFð5Þ ¼ 8, J3,5 = 3, J3,6 = 2,
J
7,8 = 20.
Z-isomer: H NMR (CDCl3): d 5.15 (1H, s, OH), 4.44
1
(1H, q, JH(4)–CF3(4) = 7, H-4). 19F NMR (CDCl3): d ꢁ65.4
(3F, CF3-4), ꢁ83.8 (3F, c, CF3-3), ꢁ132.3 (1F, F-8),ꢁ139.0
(1F, F-5), ꢁ142.1 (1F, F-6), ꢁ149.1 (1F, F-7);
JCF ð4ÞꢁHð4Þ ¼ 7, JCF ð4ÞꢁFð5Þ ¼ 7, JF(5)–H(4) = 1, J5,6 = 20,
3
3
J
J
3,7 = 5, J3,8 = 3, J5,6 = 20, J5,7 = 5, J5,8 = 13, J6,7 = 20,
6,8 = 14, J7,8 = 20. HRMS (mixture of 3 and 23) m/z,
3
3
J
5,7 = 6, J5,8 = 14, J6,7 = 20, J6,8 = 12, J7,8 = 20. HRMS
(mixture of E and Z-isomers) m/z, 371.9815 (M+). Calcd for
C11H2F10O3 = 371.9844.
331.9719 (M+). Calcd for C11F8O3 = 331.9719.
3. A mixture of acid 4 (0.63 g) and K2CO3 (0.54 g) (molar
ratio, 1:2.05) was dissolved in 5 ml of H2O and heated at
45 8C for 4 h. The aqueous solution was acidified with HCl
and extracted with ether. The extract was dried over MgSO4.
The solvent was distilled off to give 0.57 g (yield 98%) of
compound 5. An analytical sample of product 5 was prepared
by sublimation (100 8C, 2 Torr) and then crystallization.
5,6,7,8-Tetrafluoro-3-hydroxy-3-trifluoromethyl-3,4-
3.6. 5,6,7,8-Tetrafluoro-3-trifluoromethylisochromen-1-one
(22)
A solution of compound 5 (0.31 g) in 1 ml of 9% oleum was
kept at room temperature for 4 days. Then the solution was
poured into water, extracted with CH2Cl2, washed with
aqueous solution of NaHCO3 and dried over MgSO4. The
solvent was distilled off to give 0.27 g (yield 93%) of
compound 22. An analytical sample of product 22 was
prepared by crystallization.
dihydroisochromen-1-one (5): mp 108–109 8C (hexane–
CH2Cl2). UV (heptane) lmax, nm (lg e): 230 (4.09), 255
(3.29), 261 (3.25), 282 (3.33). IR (CCl4) n, cmꢁ1: 3563, 3314
(OH); 1778, 1750 (C O); 1518, 1499 (FAR). 1H NMR
(CDCl3): d 5.20 (1H, s, OH), 3.48 (1H, d, JA,B = 17, HA-4) 4
3.23 (1H, dd, JA,B = 17, JH(B)–F(7) = 2, HB-4). 13C NMR
(CDCl3, 1H decoupled): d 156.2 (s, C-1), 149.3 (dd,
1JCF = 271, 2JCF = 12) and 144.5 (dd, 1JCF = 251, 2JCF = 11,
C-5andC-8), 144.9(ddd, 1JCF = 266, 2JCF = 16, 13)and140.6
5,6,7,8-Tetrafluoro-3-trifluoromethylisochromen-1-one
(22): mp 102.5–103 8C (CH2Cl2). UV (hexane) lmax, nm (lg e):
224 (4.38), 236 (4.07), 243 (4.04), 255 (3.83), 264 (3.82), 313
(3.62). IR (CCl4) n, cmꢁ1: 3119 (C–H), 1782 (C O); 1516,
1495 (FAR). 1H NMR (CCl4): d 7.07 (d, JH(4)–F(8) = 2, H-4). 19
F
NMR (CH2Cl2): d ꢁ73.0 (3F, s, CF3), ꢁ131.2 (1F, F-8), ꢁ143.6
(1F, F-6), ꢁ145.1 (1F, F-5), ꢁ147.5 (1F, F-7); JF(8)–H(4) = 2,
1
2
(ddd, JCF = 257, JCF = 16, 12, C-6 and C-7), 120.9 (q,
1JCF = 285, CF3), 119.0 (d, 2JCF = 16) and 107.7 (m, C-4a and
J5,6 = 20, J5,7 = 3, J5,8 = 15, J6,7 = 20, J6,8 = 12, J7,8 = 20.
HRMS m/z, 285.9850 (M+). Calcd for C10HF7O2 = 285.9865.
2
C-8a), 97.6 (q, JCF = 35, C-3), 24.4 (s, C-4). 19F NMR
(CDCl3): d ꢁ86.7 (3F, s, CF3), ꢁ133.3 (1F, F-8), ꢁ142.7 (1F,
Acknowledgement
F-5), ꢁ143.7 (1F, F-6), ꢁ154.9 (1F, F-7); JFð5ÞꢁCH2 ¼ 1,
JF(7)–H(B) = 2, J5,6 = 21, J5,7 = 3, J5,8 = 14, J6,7 = 20, J6,8 = 12,
7,8 = 20. HRMS m/z, 303.9975 (M+). Calcd for
We gratefully acknowledge the Russian Foundation for
Basic Researches (project no. 06-03-32170) for financial
support.
J
C10H3F7O3 = 303.9970.

Y.V. Zonov et al. / Journal of Fluorine Chemistry 128 (2007) 1065–1073
1073
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Nauk SSSR Ser. Khim. (1991) 745–746;
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