Pentafluorophenylation of perfluorinated benzocyclobutene, indan, and tetralin by reaction with pentafluorobenzene in SbF5

Article abstract of DOI:10.1023/A:1020901526459

The reactivity of perfluorinated benzocyclobutene, indan, and tetralin in reaction with pentafluorobenzene in SbF₅ medium, and also the relative stability of generated therewith perfluoro-1-phenylbenzocycloalkenyl cations decrease with increasing alicyclic fragment in the benzocycloalkene. Treating the solutions of salts of the above cations with anhydrous HF results in the corresponding perfluoro-1-phenyl-benzocycloalkenes, and the hydrolysis of salts furnishes their 1-hydroxy derivatives. In a reaction of 1-hydroxyperfluoro-1-phenylbenzocyclobutene, -indan, and -tetralin with SOCl₂ the hydroxy group is replaced by chlorine. Besides with indan and tetralin derivatives form respectively 7-pentafluorophenyl-octafluoro-3-chlorobicyclo[4.3.0]hepta-1,4,6-triene and 7-pentafluorophenyldecafluoro-3-chlorobicyclo-[4.4.0]octa-1,4,6-triene.

Full text of DOI:10.1023/A:1020901526459

Russian Journal of Organic Chemistry, Vol. 38, No. 8, 2002, pp. 1158 1165. From Zhurnal Organicheskoi Khimii, Vol. 38, No. 8, 2002,
pp. 1210 1217.
Original English Text Copyright
2002 by Karpov, Mezhenkova, Platonov, Sinyakov, Shchegoleva.
Pentafluorophenylation of Perfluorinated Benzocyclobutene,
Indan, and Tetralin by Reaction with Pentafluorobenzene
*
in SbF5
V. M. Karpov, T. V. Mezhenkova, V. E. Platonov, V. R. Sinyakov,
and L. N. Shchegoleva
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Department, Russian Academy of Sciences,
Novosibirsk, 630090 Russia
Received December 10, 2001
Abstract The reactivity of perfluorinated benzocyclobutene, indan, and tetralin in reaction with penta-
fluorobenzene in SbF5 medium, and also the relative stability of generated therewith perfluoro-1-phenyl-
benzocycloalkenyl cations decrease with increasing alicyclic fragment in the benzocycloalkene. Treating the
solutions of salts of the above cations with anhydrous HF results in the corresponding perfluoro-1-phenyl-
benzocycloalkenes, and the hydrolysis of salts furnishes their 1-hydroxy derivatives. In a reaction of
1-hydroxyperfluoro-1-phenylbenzocyclobutene, -indan, and -tetralin with SOCl2 the hydroxy group is
replaced by chlorine. Besides with indan and tetralin derivatives form respectively 7-pentafluorophenyl-
octafluoro-3-chlorobicyclo[4.3.0]hepta-1,4,6-triene and 7-pentafluorophenyldecafluoro-3-chlorobicyclo-
[4.4.0]octa-1,4,6-triene.
We formerly investigated cationoid rearrangements
of perfluorinated benzocyclobutene (I), indan (II),
and tetralin (III) and their perfluoroalkyl derivatives
effected by Lewis acids [1 4]. Recently by an
example of reaction between perfluoro-1-phenylindan
(IV) we discovered skeletal rearrangements of per-
fluoro-1-arylbenzocycloalkenes [5]. To reveal the
general rules governing cationoid transformations in
this kind of compounds it would be desirable to study
also the reaction between antimony pentafluoride and
pentafluoro-1-phenylbenzocyclobutene (V) and per-
fluoro-1-phenyltetralin (VI). However the latter
compounds were not described. At the same time
reactions of fluoroindan (II) [5] and perfluoroalkyl-
benzenes [6] with pentafluorobenzene in the presence
of SbF5 resulting in the corresponding pentafluoro-
phenyl derivatives are known.
In this connection in the present study the pos-
sibility of formation of phenylbenzocycloalkenes
V, VI in reaction of compounds I and III with
pentafluorobenzene in the presence of SbF5 was
investigated and relative reactivity of benzocyclo-
alkenes I III in this process was established.
Scheme 1.
We demonstrated that compounds II [5], I, and III
reacted with equimolar amount of pentafluorobenzene
in the presence of SbF5 to furnish after successive
treatment with anhydrous HF and water the cor-
responding pentafluorophenyl derivatives IV V.
Besides from compounds I and II formed respectively
1-hydroxyperfluoro-1-phenylbenzocyclobutene (VII)
(at VII:V ratio 1: 1) and 1-hydroxyperfluoro-1-
phenylindan (VIII) (at VIII:IV ratio 1: 5 [5]).
Compound VI after the above treatment was isolated
without admixture of 1-hydroxyperfluoro-1-phenyl-
tetralin (IX). The hydrolysis of reaction mixtures
without preliminary treatment with HF afforded
hydroxy derivatives VII IX (Scheme 1).
n = 0 (I, V, VII, XI), 1 (II, IV, VIII, X), 2 (III, VI,
IX, XII).
*
The study was carried out under financial support of the Rus-
sian Foundation for Basic Research (grant no. 99-03-32876)
and of Siberian Division of the Russian Academy of Sciences
(grant IG SO RAN-00-N47).
1070-4280/02/3808-1158$27.00 2002 MAIK Nauka/Interperiodica

PENTAFLUOROPHENYLATION OF PERFLUORINATED BENZOCYCLOBUTENE
1159
Scheme 2.
n = 0 (VII, XI, XIII), 1 (VIII, X, XIV, XV), 2 (IX, XII, XVI, XVII).
The reaction of compounds II [5] and I with penta-
fluorobenzene goes to completion at 20 25 C in the
presence of 3 mol of SbF5 per 1 mol of substrate, but
compound III under these conditions reacts only
partially. A complete conversion of the latter is
attained at 50 55 C in the presence of 5 mol of SbF5.
At the use of 1.2 mol of SbF5 per 1 mol of compound
I the reaction does not go to completion even when
the temperature is raised to 50 C.
to a solution of cation X salt in SbF5 SO2ClF ion X
transforms into its precursor IV, and ion XI is
generated from compound V. Similarly was
demonstrated the greater relative stability of cation X
than that of ion XII.
The experimental data obtained in solution are in
agreement with the calculated by MNDO method
relative stability of cations X XII in the gas phase. It
turned out that the calculated relative stability of
phenylindanyl (X) and phenyltetralinyl (XII) cations
was lower than that of phenylbenzocyclobutenyl
By concurrent reactions method we revealed that
the rate of reaction with pentafluorobenzene in the
SbF5 medium is higher for fluorobenzocyclobutene
(I) than for fluoroindan (II). Thus the relative
reactivity of benzocycloalkenes toward pentafluoro-
benzene depends on the size of the alicyclic fragment
in the substrate and decreases in going from fluoro-
cyclobutene (I) to indan (II) and tetralin (III),
I> II> III, in agreement with the reactivity of these
compounds in reactions with fluoroolefins [7, 8].
1
cation (XI) by 1.4 and 11.6 kcal mol respectively.
The different relative stability of cations X XII
apparently governs the amount of hydroxy derivatives
VII IX arising on treating the products of reaction
between compounds I III and fluorobenzene first
with anhydrous HF and then with water (Scheme 1).
Actually, the lower the cation stability, the more the
equilibrium is shifted by HF toward the cation pre-
cursor IV VI, and the less hydroxy derivative forms
at the subsequent treatment with water.
Perfluoro-1-phenylbenzocycloalkenes IV VI in
the antimony pentafluoride medium exist as salts of
perfluoro-1-phenylindanyl (X) [5], perfluoro-1-phenyl-
benzobutenyl (XI), and perfluoro-1-phenyltetralinyl
(XII) cations respectively. Actually, on pentafluoro-
benzene addition to the solution of compound I or III
in excess SbF5 cations XI and XII are generated
(Scheme 1). These ions also arise on dissolving com-
pounds V, VI in a system SbF5 SO2ClF.
In reaction of hydroxy derivatives VII IX with
thionyl chloride the process direction depends on the
size of the alicycle in the substrate. Thus hydroxy-
benzocyclobutene VII reacted partially with SOCl2
yielding 1-chloroperfluoroalkene XIII already at
room temperature. Compound XIII was obtained in
high yield at boiling compound VII with excess
SOCl2 in CCl4 (Scheme 2).
It was shown that the relative stability of phenyl-
benzocycloalkenyl cations decreased in the series
XI > X > XII. For instance, on adding compound V
Hydroxyindan VIII under similar conditions forms
a mixture of 1-pentafluorophenyloctafluoro-1-chloro-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 8 2002

1160
KARPOV et al.
Table 1. Calculated (MNDO) total (qctot) and -charges (qc ) on carbon atoms of cations X XII (notation of atoms
as in Table 2)
qctot (qc )
Cation
no.
C1
C2
C3
C4
C5
C2
C6
C3
C5
C4
Xa
0.284
0.382
0.070
0.327
(0.170)
0.264
(0.095)
0.354
0.215
(0.009)
0.236
(0.013)
0.190
0.231
(0.018)
0.281
(0.085)
0.222
0.254
(0.042)
0.297
(0.106)
0.238
0.120
0.115
0.249
(0.390) (0.198) ( 0.116)
0.242 0.358 0.095
(0.360) (0.148) ( 0.094)
0.280 0.378 0.059
(0.398) (0.215) ( 0.120)
( 0.079) ( 0.080) (0.061)
0.083 0.080 0.308
( 0.109) ( 0.110) (0.129)
0.130 0.129 0.229
( 0.069) ( 0.071) (0.037)
XIb
XIIc
(0.201)
(0.003)
(0.005)
(0.020)
a
b
c
C1 , 0.237 ( 0.262); C1a, 0.163 ( 0.156); C5a, 0.096 ( 0.021); C6, 0.450 (0.297); C7, 0.381 (0.294).
C1 , 0.195 ( 0.227); C1a, 0.189 ( 0.162); C5a, 0.129 ( 0.049); C6, 0.508 (0.303).
C1 , 0.270 ( 0.287); C1a, 0.126 ( 0.149); C5a, 0.062 ( 0.000); C6, 0.428 (0.297); C7, 0.371 (0.291) ; C8, 0.384 (0.295).
indan (XIV) and 7-pentafluorophenyloctafluoro-3-
chlorobicyclo[4.3.0]hepta-1,4,6-triene (XV), the
latter prevailing. The reaction carried out at more
stringent conditions (90 C) with no solvent gives rise
predominantly chloroindan XIV with some triene XV
that at longer process isomerizes into chloroindan
XIV. Chloro derivatives XIII and XIV heated with
cesium fluoride in acetonitrile transform into the cor-
addition to the benzyl position of the cation
(resonance structure A) decreases in the series XI<
X < XII because of growing sterical hindrances.
Actually, the angle of pentafluorophenyl group tor-
sion relative to the plane of the other aromatic ring
(where are also situated the cationic center and the
atoms attached thereto) attains 23, 64 and 85 deg
in compounds XI, X, and XII respectively accord-
ing to MNDO calculations. In this ion series also
grows the possibility of Cl addition to the carbon
atom in the para-position with respect to benzyl
atom (resonance structure B). Indeed, the sterical
accessibility of this cationic center in cations X XII
should be relatively similar, and the positive charge
thereon grows in the series XI< X< XII (Table 1).
responding perfluoro derivatives
(Scheme 2).
V
and IV
The treatment of hydroxytetralin IX under condi-
tions of hydroxyindan VIII reaction with SOCl2 in
CCl4 gave rise only to small amount of 7-pentafluoro-
phenyldecafluoro-3-chlorobicyclo[4.4.0]octa-1,4,6-
triene (XVI), and only a prolonged process furnished
a mixture of triene XVI and 1-pentafluorophenyldeca-
fluoro-1-chlorotetralin (XVII) with residual initial
compound IX. The heating of hydroxytetralin (IX)
with SOCl2 to 100 C without solvent in a sealed
ampule also provided a mixture of compounds XVI
and XVII. Therewith with growing conversion the
relative amount of chlorotetralin XVII increased, and
that of triene XVI decreased. At long heating (100 C,
3 weeks) the mixture formed contained no triene
XVI, but only chlorotetralin XVII with unidentified
impurities.
The results of quantum-chemical calculations of
the geometrical and electronic stricture of ions X XII
are consistent with the data obtained by analysis of
their 19F NMR spectra.
Thus in the spectra of cations X XII (Table 2) the
signals from aromatic fluorine atoms are shifted
downfield with respect to the analogous signals in the
spectra of their precursors IV VI. Therewith the
strongest shift with respect to precursor ( F) suffer
the signals from fluorine atoms in both aromatic rings
located in the para- and ortho-positions to carboca-
tion center. The values J2,4 and J2 (6 ),4 of fluorine
atoms in the resonance (charged) positions of the
cations increased as compared with the analogous
constants in the precursors IV VI. These features of
spectra for cations X XII, cations of benzyl type, are
in agreement with those of perfluoro-1-benzocyclo-
butenyl [10], octafluoro-1-chloro-1-indanyl [11], and
polyfluorinated benzyl cations [12] where the values
Dissimilar directions in reactions of hydroxy
derivatives VII IX with SOCl2 may be apparently
rationalized within a framework of the currently
assumed mechanism of hydroxy group substitution by
chlorine [9] taking into account the specific geo-
metrical and electronic structures of cations X XII.
Thus, it is presumable that in the intermediately
formed ion pairs of cations X XII with the chloride
anion (Scheme 2) the probability of chloride ion
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 8 2002

PENTAFLUOROPHENYLATION OF PERFLUORINATED BENZOCYCLOBUTENE
1161
Table 2. Chemical shifts of signals and their deviation from those in precursors in 19F NMR spectra of cations X XII
(notation of atoms does not correspond to nomenclature rules)
n = O (X), 1 (XI), 2 (XII)
Cation
no.
F, ppm from C6F6
F5
(
F, ppm from precursor)
F2 ,6
F2
F3
F4
F3 ,5
F4
Xa
69.7
29.8
81.1
37.4
56.0
14.0
69.7
(45.7)
(11.1)
(62.9)
(13.4)
(32.0)
(11.5)
(55.4)
XIb
XIId
67.1
(36.3)
35.6
(15.3)
75.3
(55.5)
35.3
(8.0)
59.9 (38.0)
12.8 (10.6)
12.4 (10.2)
71.3
(57.0)
58.9 (37.0)c
71.6
(42.9)
28.5
(10.8)
86.3
(69.3)
46.9
(19.3)
52.0 (26.7) or
51.1 (25.8)
13.8 (12.0)
13.8 (10.2)
65.7
(51.3)
a
b
c
d
59.0 and 56.0 ppm (2F6, 2F7), J2,4 47, J3,4 J4,5 20 [5]; J2(6 )4 29, J3(5 )4 21 Hz.
84.9 ppm (2F6); J2,4 38, J3,4 J4,5 19, J2 (6 )4 31, J3 (5 )4 21 Hz.
F6 , J2,6 165, J2,2 < 5 Hz.
58.5, 51.1 or 52.0 (2F6, 2F8), 32.7 ppm (2F7); J2,4 55, J3,4 J4,5 20, J2(6 )4 27, J3(5 )4 21 Hz.
and J are believed to be connected with direct
participation of fluorine atoms in charge distribution
and conjugation [12].
The composition and structure of compounds were
established from elemental analyses and spectral
characteristics.
F
In going from phenylbenzocyclobutenyl cation XI
to phenylindanyl X and phenyltetralinyl XII ones the
values
The assignment of signals in the 19F NMR spectra
was carried out basing on the chemical shifts of the
signals, their fine structure, and integral intensity
(Table 3). The rules governing the spectra of poly-
fluorophenylbenzocycloalkenes are consistent with
those previously established for polyfluorinated
benzocyclobutenes [7 10], indans [2, 3, 7, 8], and
tetralins [4, 7] with no pentafluorophenyl group.
In the 19F NMR spectra of phenyltetralins VI, IX,
XVII at room temperature two signals correspond to
ortho and meta fluorine atoms in the pentafluoro-
phenyl group, apparently due to very slow (in the
NMR time scale) rotation of this group around an
ordinary C C bond. In the indan (IV, VIII, XIV) and
benzocyclobutene (V, VII, XIII) derivatives the
rotation of pentafluorophenyl group occurs apparently
easier than in analogous tetralin compounds. As a
result in their 19F NMR spectra the ortho and meta
fluorine atoms of the pentafluorophenyl group appear
each as one broadened signal, and in the spectra of
chloro derivatives XIII, XIV the signals of ortho
fluorine atoms are not seen.
(F4) and J2,4 grow, and
(F4 ) and
J2 (6 ),4 decrease evidencing apparently the increase
in the torsion angle of pentafluorophenyl group with
respect to the ion plane in the series XI < X < XII
and the reduced participation of the pentafluorophenyl
group in the charge delocalization along the series
XI > X > XII. Besides unlike the spectra of cations
X and XII in the 19F NMR spectrum of ion XI the F2
and F6 atoms appear as two signal, i.e. they are
nonequivalent. Therewith a large coupling constant
J2,6 165 Hz (J2,2
<
5 Hz) indicates the spacial
proximity of the interacting nuclei, in the other
words, the small torsional angle of the pentafluoro-
phenyl group in cation XI.
It should be noted that due to the change in the
closest neighborhood of atoms F2,2 ,6 the values
(F2) and
(F2 ,6 ) in going from neutral com-
pounds IV VI to ions X XII cannot characterize the
charge distribution in the ions as it do
(F4) and
(F4 ) in the neutral compounds.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 8 2002

1162
KARPOV et al.
Table 3. 19F NMR spectra of compounds IV IX, XIII, XIV, XVIIa,b and trienes XV, XVI (notation of atoms does not
correspond to nomenclature rules)
c
, ppm from C6F6
F7
JAB, Hz
Compd.
no.
F2
F3
F4
F5
F6
F8
F2,6 F3 ,5
F4
AB
A B
(A B )
A
B
A
B
A
B
IV
V
24
18.7 18.2
24
62.8 51.0 43.8 33.6
24
2.5 14.3
260
200
292
240
30.8 20.3 19.8 27.3 67.6 58.3
21.9 2.2 14.3
VId
28.7 17.7 17.0 27.6 61.4 50.2 32.8 22.4 41.2 29.5 25.2e 1.8 14.4
25.4 3.6
275
(282)
VII
VIII
IXf
28.9 19.2 16.6 26.5 65.7 55.8
23.0 17.3 14.6 22.0 64.8 50.4 45.0 32.5
27.9 16.6 13.8 26.2 67.4 46.6 37.4 20.4 45.1 27.3 27.1 2.4 12.8
17.8 2.8
20.3 1.4 11.5
22.7 2.2 12.5
198
260
290
235
275
(280)
XIII
XIV
XVII
29.6 20.4 17.9 26.8 69.1 62.6
25.4 18.0 15.4 22.7 61.5 52.5 49.1 43.3
26.8 17.1 14.4 26.6 63.1 48.9 39.3 23.7 48.4 37.9 32.7, 1.4, 14.0
1.9 12.6
2.1 13.8
188
262
290
232
260
or
26.6
11.1
or
26.8
32.4 3.5
26 2.4 14.6
(270)
XV
26 57.3 41.8 49.0 48.0 53.6 52.1
259
263
XVI
17.9 21.8 52.8 54.9 47
50
24.2 47
50
24.2 2.0 13.7
25.0
a
b
c
d
e
f
J2,4 6 9, J3,5 7 9, J2,3 19 21, J3,4 17 21, J4,5 19 21, J2(6),4 4 6, J3(5),4 21 Hz.
J2,5 23 24 (V, VII, XIII), 16 17 (IV, VIII, XIV), 10 12 Hz (VI, IX, XVII).
1: 19.3 (IV), 32.8 (V), 12.5 ppm (VI).
F
J5,6A 10, J5,6B 35 Hz.
F 6 , J1,6 72 Hz.
J5,6A 6, J5,6B 42 Hz.
In the 19F NMR spectra of trienes XV, XVI the
internal reference C6F6. Elemental composition of
compounds was determined from high resolution
mass spectra measured on Finnigan MAT 8200 instru-
ment. GLC analysis was carried out on chromato-
graph LKhM-72 [oven programmed from 50 to
270 C, column 4000 4 mm, stationary phase
SKTFT-50 on Chromosorb W, 12(25): 100. carrier
signal of CFCl group appears as a triplet with a char-
acteristic coupling constant J3,4 J4,5 27 Hz. The
analogous coupling constant in the spectrum of
7-methylperfluorobicyclo[4.3.0]hepta-1,4,6-triene is
22 Hz [13].
1
EXPERIMENTAL
gas helium, flow rate 60 ml min ]. Elemental
analyses of compounds V VII, IX, XIII XVII are
given in Table 4.
19F NMR spectra of reaction mixtures and in-
dividual compounds in CHCl3 solution of concentra-
tion below 10 mol% were registered on spectrometer
Bruker WP-200SY at operating frequency 199.3MHz,
Reaction of perfluorobenzocyclobytene (I) with
C6F5H in SbF5 medium. (a) To a stirred mixture of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 8 2002

PENTAFLUOROPHENYLATION OF PERFLUORINATED BENZOCYCLOBUTENE
1163
compound I (5.31 g, 21.4 mmol), SbF5 (13.92 g,
64.2 mmol), and C6F6 (15 ml) was added C6F5H
(3.96 g, 23.6 mmol) within 10 min at 23 C. The mix-
ture was stirred at the same temperature for 4 h, then
it was treated with water at 0 10 C, the organic layer
was separated, dried with MgSO4, C6F6 and excess
C6F5H were distilled off. We obtained 8.15 g (97%)
of compound VII ( 19F NMR spectrum). Analytical
sample (viscous fluid) was obtained by sublimation
in a vacuum (130 C, 5 mm Hg).
Table 4. Elemental analyses of compounds V VII, IX,
XIII XVII
Found, %
Calcd., %
Compd.
no.
Formula
C (H) F (Cl)
C (H) F (Cl)
VI
IX
38.77 61.27 C16F16
39.19 57.76 C16HF15O
(0.17)
38.71 61.29
38.87 57.69
(0.20)
XVI+XVII 37.47 (6.95) C16ClF15
37.48 (6.92)
(395.9808)
(393.9851)
(411.9513)
(461.9481)
(461.9481)
(b) Similarly to the preceding experiment from
compound I (1.58 g, 6.4 mmol), C6F5H (1.18 g,
7.0 mmol), SbF5 (1.66 g, 7.7 mmol) in C6F6 (6 ml)
was obtained after 10 h at 50 C and 15 h at 20 C a
mixture containing compounds VII, I, and C6F5H in
a ratio 1: 1.5 : 1.6 (by 19F NMR spectrum). On distil-
ling off C6F6 and unreacted initial compounds 0.98 g
of product VII (by 19F NMR spectrum) was obtained.
Va
(395.9811) C14F12
VIIa
XIIIa
XIVa
XV
(393.9848) C14HF11O
(411.9506) C14ClF11
(461.9473) C15ClF13
(461.9469) C15ClF13
a
Molecular weight is given.
(c) To a stirred mixture of compound I (2.82 g,
11.4 mmol), SbF5 (7.4 g, 34.1 mmol) and C6F6
(3.5 ml) was added 2.1 g (12.5 mmol) of C6F5H
within 5 min at 20 C. The mixture was stirred for 4 h
at 20 C, then it was treated with anhydrous HF and
poured on ice. The organic layer was separated,
washed with water, dried with MgSO4, C6F6 and
excess C6F5H were distilled off. We obtained 3.6 g
(yield 80%) of a mixture of compounds V and VII in
a ratio 1: 1 (by 19F NMR spectrum). By column
chromatography on silica gel (eluent CHCl3) was
isolated 1.6 g of phenylbenzocyclobutene V, mp
54.5 55 C (from hexane), and 1.3 g of compound
VII.
(b) A mixture of compound III (1.68g, 4.8 mmol),
C6F5H (0.9 g, 5.4 mmol), and SbF5 (5.27 g,
24.3 mmol) was stirred for 6 h at 50 55 C, then was
added C6F6 (2.5 ml), the reaction products were
treated with water at 0 10 C, then extracted with
CHCl3, the extract was dried on MgSO4, C6F6 and
CHCl3 were distilled off. We obtained 1.91 g of
crude hydroxyphenyltetralin IX (96% according to
GLC and 19F NMR spectrum). By purification by
column chromatography on silica gel (eluent CHCl3)
was separated 1.73 g (yield 73%) of compound IX,
mp 58 99 C (from hexane).
(c) To a stirred mixture of compound III (1.51 g,
4.3 mmol), SbF5 (2.38 g, 11.0 mmol) in C6F6
(1.5 ml) was added C6F5H (0.8 g, 4.8 mmol) at 20 C.
The mixture was stirred for 4.5 h at 25 C, treated
with water at 0 10 C, the organic layer was
separated, and dried with MgSO4. According to
19F NMR data the mixture contained compounds IX,
III, and C6F5H a at ratio 1.5 : 1: 1.2. On distilling
off the solvent and initial compounds we obtained
1.16 g of compound IX.
(d) Similarly to the run (a) from compounds I
(0.48 g, 1.9 mmol) and II (0.58 g, 1.9 mmol), C6F5H
(0.32 g, 1.9 mmol), SbF5 (2.53 g, 11.7 mmol) in
C6F6 (2 ml) was obtained (28 C, 3 h) a mixture that
after removing of C6F6 and compound II furnished
0.57 g of product containing compounds VII and
VIII in 13: 1 ratio (according to 19F NMR spectrum).
Reaction of perfluorotetralin (III) with C6F5H in
SbF5 medium. (a) A mixture of compound III
(2.67 g, 7.7 mmol), C6F5H (1.42 g, 8.5 mmol),
SbF5 (8.3 g, 38.3 mmol), and C6F6 (4 ml) was stirred
for 6 h at 50 55 C, treated with anhydrous HF
(18 ml), and then poured on ice. The organic layer
was separated, washed with water, dried with
MgSO4, C6F6 and excess C6F5H were distilled off.
We obtained 3.21 g of crude phenyltetralin VI (97%
according to GLC and 19F NMR spectrum). By
purification by column chromatography on silica gel
(eluent CCl4) was separated 3.11 g (yield 82%) of
compound VI, mp 68 69 C (from hexane).
1-Pentafuorophenylhexafluoro-1-chlorobenzo-
cyclobutene (XIII). (a) To a mixture of compound
VII (1.84 g, 4.7 mmol) and SOCl2 (1.09g, 9.2 mmol)
in CCl4 (10 ml) was added 3 drops of DMF, and the
mixture was stirred for 5.5 h at 23 C. According to
19F NMR spectrum the mixture contained compounds
VII and XIII in a ratio 2.6 : 1. Then the mixture was
stirred at heating to 75 C for 7 h, CCl4 and excess
SOCl2 were distilled off, the residue was washed with
water, then extracted with CHCl3. The extract was
dried with MgSO4, the solvent was removed to
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 8 2002

1164
KARPOV et al.
furnish 1.8 g (yield 94%) of compound XIII (by
(b) Compound IX (0.62 g, 1.3 mmol), SOCl2
(1.01 g, 8.5 mmol), and DMF (4 drops) were heated
in a sealed ampule to 100 C. According to 19F NMR
spectrum the mixture after 147 h contained com-
pounds IX, XVI, and XVII in a ratio 1: 4,5 : 8, in
300 h compounds XVI and XVII in a ratio 1:$, and
in 470 h phenyltetralin XVII did not contain triene
XVI. Excess SOCl2 was distilled off, the residue was
dissolved in CHCl3, the solution was washed with
water and dried with MgSO4. Then the solvent was
distilled off to furnish 0.61 g of a mixture containing
according to GLC and 19F NMR spectrum 64% of
phenyltetralin XVII alongside unidentified impurities
(apparently tetralin derivatives containing 2 3
chlorine atoms). By column chromatography on silica
gel (eluent hexane) a substance was separated contain-
ing 90% of phenyltetralin XVII.
19F NMR spectrum).
(b) To a mixture of compound VII (0.36 g,
0.9 mmol) and SOCl2 (1.08 g, 9.0 mmol) in CCl4
(2 ml) was added 2 drops of DMF, the mixture was
stirred for 11 h at 75 C, worked up as in the preced-
ing run. We obtained 0.33 g (yield 96%) of com-
pound XIII.
7-Pentafluorophenyloctafluoro-3-chlorobicyclo-
[4.3.0]hepta-1,4,6-triene (XV). (a) Similarly to the
preceding experiment from compound VIII (0.4 g,
0.9 mmol), SOCl2 (1.08 g, 9.0 mmol), DMF (2
drops) in CCl4 (2 ml) was obtained (75 C, 11 h)
0.4 g of a mixture of compounds XIV and XV in
1: 2.4 ratio (according to 19F NMR spectrum).
Triene XV was isolated as individual compound by
column chromatography on silica gel (eluent hexane)
from a mixture that contained the products of several
similar experiments.
Reaction of 1-pentafuorophenylhexafluoro-1-
chlorobenzocyclobutene (XIII) with CsF. Com-
pound XIII (0.5 g, 1.2 mmol), CsF (0.96 g,
6.3 mmol), and CH3CN (0.5 ml) were heated in a
sealed ampule to 100 C for 15 h. Then the reaction
mixture was treated with water, extracted with CCl4,
the extract was dried on MgSO4, and on removing
the solvent we obtained 0.46 g (yield 96%) of phenyl-
benzocyclobutene V (19F NMR data).
1-Pentafluorophenyloctafluoro-1-chloroindan
(XIV). Compound VIII (0.5 g 1.1 mmol), SOCl2
(0.66 g, 5.5 mmol) and DMF (2 drops) was heated
to 90 C in a sealed ampule for 20 h. According to
19F NMR spectrum the resulting products mixture
contained compounds XIV and XV in a ratio 2.5 : 1.
More SOCl2 was added (0.17 g, 1.4 mmol), and
heating to 90 C was continued for 20 h. Then the
products were treated with water, extracted into
CHCl3, and the extract was dried on MgSO4. On
removing the solvent 0.53 g of crude phenylindan
XIV (91% according to GLC and 19F NMR spec-
trum) was obtained, yield 93%. Compound XIV was
isolated in individual state by column chromato-
graphy on silica gel (eluent hexane).
Reaction of 1-pentafluorophenyloctafluoro-1-
chloroindan (XIV) with CsF. In the same way as in
the preceding experiment from compound XIV
(0.53 g, 1.1 mmol) and CsF (0.9 g, 5.9 mmol) in
CH3CN (0.5 ml) was obtained (100 C, 14 h) 0.5 g of
substance containing a lot of tar. It was subjected to
steam distillation to afford 0.41 g of compound that
according to GLC and 19F NMR data contained 90%
of phenylindan IV, yield 72%.
7-Pentafluorophenyldecafluoro-3-chlorobicyclo-
[4.4.0]octa-1,4,6-triene (XVI) and 1-pentafluoro-
phenyldecafluoro-1-chlorotetralin (XVII). (a) Com-
pound IX (0.45 g, 0.9 mmol), SOCl2 (1.08 g,
9 mmol), and DMF (2 drops) in CCl4 (2 ml) were
stirred at 75 C for 11 h. According to 19F NMR
spectrum the mixture contained compounds IX, XVI
in a ratio 8: 1, and no phenyltetralin XVII. The stir-
ring at 75 C was continued for 67 h more, and then
the reaction mixture was subjected to the same
workup as in the previous run. We obtained 0.38 g of
a mixture containing compounds IX, XVI, and XVII
in a ratio 1.1 : 1.8 : 1 (19F NMR data). By column
chromatography on silica gel (eluent hexane) a mix-
ture of triene XVI and phenyltetralin XVII was
separated with the ratio of compounds XVI:XVII
1.5 : 1 (19F NMR spectrum).
Perfluoro-1-phenyl-1-benzocyclobutenyl cation
(XI). (a) Compound I (0.2 g, 0.8 mmol) was dis-
solved in SbF5 (1.07 g, 4.9 mmol), then C6F5H
(0.15 g, 0.9 mmol) was added at 20 C, the mixture
was stirred, and the solution was maintained at this
temperature for 3 h. The formation of cation XI was
proved by 19F NMR spectrum. Then the mixture was
poured on ice, extracted with CH2Cl2, the extract was
dried on MgSO4, the solvent was distilled off, and the
remaining 0.23 g of substance contained compounds
V and VII in a ratio 1: 10 (19F NMR spectrum).
(b) Phenylbenzocyclobutene V (0.2 g, 0.5 mmol)
was dissolved in SbF5 (0.77 g, 3.5 mmol) and
SO2ClF (0.2 ml). According to 19F NMR spectrum
the solution contained only cation XI salt and no
precursor V.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 8 2002

PENTAFLUOROPHENYLATION OF PERFLUORINATED BENZOCYCLOBUTENE
1165
(c) Phenylindan IV (0.12 g, 0.3 mmol) was added
to solution of SbF5 (0.09 g, 0.4 mmol) in SO2ClF
(0.5 ml) at 10 C, and the mixture was stirred.
According to 19F NMR spectrum the solution contain-
ed cation X salt and phenylindan IV in a ratio 1: 0.7.
Then phenylbenzocyclobutene V (0.11 g, 0.3 mmol),
SbF5 (0.04 g, 0.2 mmol), and SO2ClF (0.2 ml) were
added, the mixture was stirred to form a hetero-
geneous system. In the 19F NMR spectrum of the
mixture at 10 C were observed signals of cation XI
and phenylindan IV in a ratio 1: 3.5. The mixture
was treated with water, extracted with dichloro-
methane, the extract was dried with MgSO4, the
solvent was removed. The mixture of compounds
obtained (0.2 g) contained substances IV, V, and VII
in a ratio 11: 1: 9 as shown by 19F NMR spectrum.
NMR spectrum compounds IV (4%), VI (44%), IX
(11%), and VIII (39%).
REFERENCES
1. Karpov, V.M., Mezhenkova, T.V., Platonov, V.E.,
and Yakobson, G.G., J. Fluorine Chem., 1985,
vol. 28, no. 1, pp. 115 120; Karpov, V.M., Mezhe-
nkova, T.V., Platonov, V.E., and Yakobson, G.G.,
Bull. Soc. Chim., 1986, no. 6, pp. 980 985; Kar-
pov, V.M., Mezhenkova, T.V., and Platonov, V.E.,
Izv. Akad. Nauk, Ser. Khim., 1992, no. 6, pp. 1419
1424; Karpov, V.M., Mezhenkova, T.V., and Pla-
tonov, V.E., J. Fluorine. Chem., 1996, vol. 77,
no. 1, pp. 101 103.
2. Karpov, V.M., Mezhenkova, T.V., and Plato-
nov, V.E., Izv. Akad. Nauk SSSR, Ser. Khim., 1990,
no. 3, pp. 645 652.
3. Karpov, V.M., Mezhenkova, T.V., Platonov, V.E.,
and Yakobson, G.G., Izv. Akad. Nauk SSSR, Ser.
Khim., 1990, no. 5, pp. 1114 1120.
4. Karpov, V.M., Mezhenkova, T.V., and Plato-
nov, V.E., Zh. Org. Khim., 1997, vol. 33, no. 5,
pp. 755 761.
5. Karpov, V.M., Mezhenkova, T.V., Platonov, V.E.,
and Sinyakov, V.R., J. FluorineChem., 2001, vol. 107,
no. 1, pp. 53 57.
6. Pozdnyakovich, Yu.V. and Shteingarts, V.D., J. Fluor-
ine Chem., 1974, vol. 4, pp. 297 316.
7. Karpov, V.M., Mezhenkova, T.V., Platonov, V.E.,
and Yakobson, G.G., J. Fluorine Chem., 1985,
vol. 28, no. 1, pp. 121 137.
Perfluoro-1-phenyl-1-tetralinyl cation (XII). (a)
Compound III (0.24 g, 0.7 mmol) was dissolved in
SbF5 (0.9 g, 4.2 mmol), then C6F5H (0.13 g,
0.76 mmol) was added, the mixture was stirred,
heated to 50 C for 2.5 h to obtain a solution of cation
XII as seen from 19F NMR spectrum. Then the
mixture was poured on ice, extracted with CH2Cl2,
the extract was dried on MgSO4, the solvent was
distilled off. We obtained 0.28 g of mixture contain-
ing according to GLC and 19F NMR data compounds
VI (44%) and IX (45%).
(b) Phenyltetralin VI (0.24 g, 0.5 mmol) was
added to a solution of SbF5 (0.72 g, 3.3 mmol) in
SO2ClF (0.2 ml), and the mixture was stirred. As
shown by 19F NMR spectrum, the solution contained
cation XII salt and no precursor V.
8. Karpov, V.M., Mezhenkova, T.V., Platonov, V.E.,
and Yakobson, G.G., Izv. Akad. Nauk SSSR, Ser.
Khim., 1987, no. 6, pp. 1361 1368.
9. Schreiner, P.R., Schleyer, P.R., and Hill, R.K.,
J. Org. Chem., 1993, vol. 58. N. 10, pp. 2822 2829.
10. Karpov, V.M., Mezhenkova, T.V., Platonov, V.E.,
and Yakobson, G.G., Izv. Akad. Nauk SSSR, Ser.
Khim., 1985, no. 10, pp. 2315 2323.
(c) Phenyltetralin VI (0.09 g, 0.18 mmol) was
added to a solution of SbF5 (0.11 g, 0.5 mmol) in
SO2ClF (0.5 ml) at 10C, and the mixture was
stirred. As shown by 19F NMR spectrum, the solu-
tion contained cation XII salt and no precursor V.
Then was added phenylindan IV (0.09 g, 0.2 mmol),
and the mixture was stirred at 10 C. According to
19F NMR spectrum the solution contained salts of
cations XII, X, and phenyltetralin VI in a ratio
1: 3: 2. The mixture was treated with water,
extracted with dichloromethane, the extract was dried
with MgSO4, the solvent was removed. The residue
weighing 0.15 g contained according to GLC and 19F
11. Karpov, V.M. and Platonov, V.E., Zh. Org. Khim.,
1994, vol. 30, no. 5, p. 789.
12. Pozdnyakovich, Yu.V. and Shteingarts, V.D., J.
Fluorine Chem., 1974, vol. 4, pp. 283 296.
13. Dvornikova, K.V., Platonov, V.E., and Yakob-
son, G.G., Izv. Akad. Nauk, Ser. Khim., 1993,
no. 10, pp. 1767 1770.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 8 2002