Synthesis of fluorine-containing 1,4-dioxa-2-azaspiro-[4.5]deca-2,6,9- trienes by reaction of polyfluorinated cyclohexa-2,5-dienones with nitrile oxides

Article abstract of DOI:10.1134/S1070428012060061

4-Pentafluorophenoxy-, 4-nitro-, and 4-chloropentafluorocyclohexa-2,5-dien- 1-ones and 3,4,5-tris-(pentafluorophenoxy)trifluorocyclohexa-2,5-dien-1-one react with some benzonitrile and acetonitrile oxides exclusively at the carbonyl group, leading to the formation of mixtures of diastereoisomeric fluorinated 1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-trienes in good yield.

Full text of DOI:10.1134/S1070428012060061

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 6, pp. 783–787. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.N. Kovtonyuk, L.S. Kobrina, Yu.V. Gatilov, 2012, published in Zhurnal Organicheskoi Khimii, 2012, Vol. 48, No. 6, pp. 787–791.
Synthesis of Fluorine-Containing 1,4-Dioxa-2-azaspiro-
[4.5]deca-2,6,9-trienes by Reaction of Polyfluorinated
Cyclohexa-2,5-dienones with Nitrile Oxides
V. N. Kovtonyuk, L. S. Kobrina, and Yu. V. Gatilov
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 9, Novosibirsk, 630090 Russia
e-mail: kovtonuk@nioch.nsc.ru
Received January 30, 2012
Abstract—4-Pentafluorophenoxy-, 4-nitro-, and 4-chloropentafluorocyclohexa-2,5-dien-1-ones and 3,4,5-tris-
(pentafluorophenoxy)trifluorocyclohexa-2,5-dien-1-one react with some benzonitrile and acetonitrile oxides ex-
clusively at the carbonyl group, leading to the formation of mixtures of diastereoisomeric fluorinated 1,4-dioxa-
2-azaspiro[4.5]deca-2,6,9-trienes in good yield.
DOI: 10.1134/S1070428012060061
1,3-Dipolar cycloadditions of quinoid compounds
are widely used in the synthesis of various heterocyclic
compounds [1]. Fluorinated cyclohexadienones can be
used as starting materials for selective syntheses of
various fluorine-containing compounds [2]. We previ-
ously showed that 1,3-dipolar cycloadditions of poly-
fluorocyclohexa-2,4-dienones with diazomethane and
phenyldiazomethane involve the C=O and C=C bonds
of the dienone with formation of fluorinated spiro-
[indazole-7,2′-oxirane] derivatives or cyclopropanation
products at the C=C bond of cyclohexa-2,4-dienone,
polyfluorinated 7-phenylbicyclo[4.1.0]hept-4-en-2-
ones [3]. Diazomethane reacted with polyfluorocyclo-
hexa-2,5-dienones exclusively at the carbonyl group
with formation of mixtures of diastereoisomeric fluori-
nated 1-oxaspiro[2.5]octa-4,7-dienes [4].
hexa-2,5-dienones with some benzonitrile and aceto-
nitrile oxides. 4-Pentafluorophenoxy-, 4-nitro-, and
4-chloropentafluorocyclohexa-2,5-dien-1-ones I–III
reacted with substituted benzonitrile oxides and aceto-
nitrile oxide to give mixtures of diastereoisomeric
fluorinated 1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-trienes
IV–X in good yield (Scheme 1). The structure of com-
pounds IV–VI and VIII–X was assigned on the basis
1
19
of their elemental compositions and H and F NMR
spectra recorded for diastereoisomer mixtures. Dia-
stereoisomers VIIa/VIIb were not isolated, but their
19
formation was confirmed by analysis of the F NMR
spectrum of the reaction mixture. Isomer IVa was
isolated as individual substance, and its structure was
determined by X-ray analysis (see figure).
The Cambridge Structural Database lacks data on
compounds containing a 1,4-dioxa-2-azaspiro[4.5]-
deca-2,6,9-triene fragment. Among the examined com-
In the present article we report the results of our
study on 1,3-dipolar cycloaddition of polyfluorocyclo-
Scheme 1.
R
R
N
N
O
O
O
O
O
F
F
F
F
F
F
F
F
F
F
F
F
+
R–C
≡
N
O
+
F
X
F
X
F
X
I–III
IVa–Xa
IVb–Xb
I, IV–VIII, X = C6F5O; II, IX, X = O2N; III, X, X = Cl; IV, R = Ph; V, IX, X, R = 4-MeOC6H4; VI, R = 4-BrC6H4;
VII, R = 3-O2NC6H4; VIII, R = Me.
783

KOVTONYUK et al.
784
F7
C19
F6
O2
N2
O1
F1
C18
F8
C16
C15
F2
C20
C3
C6
C7
C11
C17
C5
O4
C21
C8
C12
C14
C10
C9
C22
F10
C13
F5
F4
F3
F9
Structure of the molecule of 6,7,8,9,10-pentafluoro-3-phenyl-8-pentafluorophenoxy-1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-triene (IVa)
according to the X-ray diffraction data.
pounds, the closest analog is 7-(tert-butyl-3,5′-bis(2,6-
dichlorophenyl)spiro[[1,2]benzoxazole-5,2′-[1,3,4]di-
oxazole]-4-one [5]. The five- and six-membered spiro-
fused rings in molecule IVa are planar: the mean-
square deviations of atoms are 0.029 and 0.051 Å,
respectively; the dihedral angle between the ring
planes is 89.4(2)°.
oxides with dienone I took ~3 days, whereas the
process in situ was accompanied by formation of by-
products.
The presence of two donor methoxy groups in
positions 3 and 5 of initial dienone I completely
prevents it from reacting with benzonitrile oxide,
whereas dienone XI having two pentafluorophenoxy
groups in the same positions reacted with benzonitrile
oxide under analogous conditions to afford diastereo-
isomer mixture XIIa/XIIb in good yield (Scheme 2).
The 19F NMR spectra of IV–X resemble those
reported previously for diastereoisomeric polyfluori-
nated 1-oxaspiro[2.5]octa-4,7-dienes [4]. Signals in the
1
19F and H NMR spectra were assigned to particular
The regioselectivity of the 1,3-dipolar cycloaddi-
tion of nitrile oxides to polyfluorinated dienones I–III
and XI is consistent with analogous reactions of
1,4-benzoquinones [6, 7]: polyhalogenated 1,4-benzo-
quinones react with aromatic nitrile oxides to give
cycloaddition products at one or both carbonyl groups
of the quinone [6]. Frontier orbital analysis showed [7]
that the addition at the C=O group is determined by the
interaction HOMO (nitrile oxide)–LUMO (quinone);
in other words, nitrile oxides act as electron donors,
isomers Va, VIa, VIIIa, Vb, VIb, and VIIIb assuming
that the major isomers have the structure analogous to
compound IVa.
Dienones I–III reacted fairly readily with benzo-
nitrile oxide, 4-methoxybenzonitrile oxide, and aceto-
nitrile oxide both in situ and generated preliminarily
from the corresponding N-hydroxyimidoyl chlorides
by the action of triethylamine or sodium hydroxide.
The reactions of 4-bromo- and 3-nitrobenzonitrile
Scheme 2.
Ph
N
O
O
O
F
F
F
F
NOH
Cl
Et3N
+
~80%
Ph
C6F5O
OC6F5
C6F5O
OC6F5
F
OC6F5
F
OC6F5
XI
XIIa, XIIb (55:45)
Scheme 3.
4-MeOC6H4
4-MeOC6H4
N
N
·
O
O
O
O
O
O
O
NO2
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
–NO2
–[4-MeOC6H4CNO]
·
F
NO2
F
F
IXa, IXb
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SYNTHESIS OF FLUORINE-CONTAINING 1,4-DIOXA-2-AZASPIRO[4.5]DECA-2,6,9-TRIENES
785
and polyhaloquinones, as acceptors. Presumably, this
is responsible for inhibition of the reactions with di-
methoxy-substituted dienone and bromo- and nitro-
substituted benzonitrile oxides. Examples of the addi-
tion of nitrile oxides at C=C bond of substituted cyclo-
hexa-2,5-dienones were also reported [8].
(83%) of a viscous material contaning diastereoiso-
mers IVa and IVb at a ratio of 57:43 (according to the
19F NMR data). Double recrystallization from ethanol
gave 0.51 g of crystalline mixture IVa/IVb at a ratio of
85:15. The mother liquor contained 0.29 g of IVa/IVb
1
at a ratio of 16:75. H NMR spectrum of IVa/IVb, δ,
ppm: 7.48–7.61 m (3H, Harom), 7.78–7.83 m (2H,
H
m-F), 6.1 t (1F, p-F), 8.0 m (2F, 6-F, 10-F), 8.2 m (2F,
7-F, 9-F), 10.4 m (2F, o-F), 41.4 m (1F, 8-F).
The reaction of dienone I with benzonitrile oxide is
irreversible, and the resulting spiro-dioxazole IVa is
stable up to 130°C, whereas compounds IXa and IXb
above 80°C undergo decomposition via elimination of
arom). 19F NMR spectrum of IVb, δF, ppm: 0.4 m (2F,
19
b. Triple recrystallization from petroleum ether
(40–70°C) of 0.61 g of a 57 :43 mixture IVa/IVb
prepared in a similar way gave 0.15 g of pure isomer
IVa with mp 101–103°C. 19F NMR spectrum, δF, ppm:
0.5 m (2F, m-F), 6.1 t (1F, p-F), 8.1 m (2F, 6-F, 10-F),
8.2 m (2F, 7-F, 9-F), 10.6 m (2F, o-F), 41.9 m (1F,
8-F). Found, %: C 46.80; H 0.73; F 39.04; N 3.09.
M 480. C19H5F10NO3. Calculated, %: C 47.03; H 1.04;
F 39.15; N 2.89. M 485.
nitrogen dioxide. According to the F NMR data, one
decomposition product is tetrafluoro-1,4-benzoquinone
which is likely to be formed according to Scheme 3.
Instability of polyfluorinated cyclohexadienes and
-dienones having a nitro group at the sp3-carbon atom
is known from the literature [9].
EXPERIMENTAL
1
The H and 19F NMR spectra were recorded on
6,7,8,9,10-Pentafluoro-3-(4-methoxyphenyl)-8-
pentafluorophenoxy-1,4-dioxa-2-azaspiro[4.5]deca-
2,6,9-triene (Va/Vb). Following an analogous proce-
dure, from 0.6 g (4 mmol) of 4-methoxybenzaldehyde
oxime, 0.65 g (6 mmol) of tert-butyl hypochlorite,
0.4 g (4 mmol) of triethylamine, and 0.73 g (2 mmol)
of dienone I in 20 ml of CCl4 we obtained 0.97 g
(94%) of a viscous material containing diastereo-
isomers Va and Vb at a ratio of 55:45 (19F NMR).
1H NMR spectrum, δ, ppm: Va: 3.90 s (3H, OCH3),
6.98 m (2H, Harom), 7.71 m (2H, Harom); Vb: 3.90 s
(3H, OCH3), 6.98 m (2H, Harom), 7.74 m (2H, Harom).
19F NMR spectrum, δF, ppm: Va: 0.4 m (2F, m-F), 6.0 t
(1F, p-F), 7.5 m (2F, 7-F, 9-F), 8.2 m (2F, 6-F, 10-F),
10.5 m (2F, o-F), 41.8 m (1F, 8-F); Vb: 0.3 m (2F,
m-F), 6.0 t (1F, p-F), 7.5 m (2F, 7-F, 9-F), 8.1 m (2F,
6-F, 10-F), 10.4 m (2F, o-F), 41.3 m (1F, 8-F). Double
crystallization from ethanol gave 0.72 g of crystalline
mixture Va/Vb at a ratio of 50:50. Found, %: C 46.78;
H 1.39; F 37.08; N 2.62. M 516. C20H7F10NO4. Cal-
culated, %: C 46.62; H 1.37; F 36.87; N 2.72. M 515.
a Bruker AV-300 spectrometer at 300.13 and
282.36 MHz, respectively, from solutions in CCl4 with
addition of DMSO-d6 (~5%); the latter was used as
internal reference for 1H (δ 2.54 ppm relative to TMS),
and C6F6 was used as internal reference for 19F. The
progress of reactions was monitored by TLC on Merck
60 F254 plates. Silica gel (0.063–0.200 mm; Merck)
was used for column chromatography. Polyfluorinated
cyclohexa-2,5-dienones I–III were synthesized
according to the procedures described in [10].
6,7,8,9,10-Pentafluoro-8-pentafluorophenoxy-
3-phenyl-1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-triene
(IVa/IVb). a. A solution of 0.48 g (4 mmol) of benz-
aldehyde oxime in 15 ml of methylene chloride was
cooled to 4°C, a solution of 0.65 g (6 mmol) of tert-
butyl hypochlorite in 5 ml of methylene chloride was
added dropwise under stirring, and the mixture was
stirred for 3 h at room temperature and evaporated
under reduced pressure (~20 mm). The residue was
dissolved in 10 ml of carbon tetrachloride, a solution
of 0.73 g (2 mmol) of pentafluoro-4-pentafluoro-
phenoxycyclohexa-2,5-dien-1-one (I) in 5 ml of
carbon tetrachloride was added, the mixture was
cooled to 4°C, and a solution of 0.4 g (4 mmol) of
triethylamine in 5 ml of carbon tetrachloride was
added dropwise under stirring. The mixture was stirred
for 2 h at room temperature, the precipitate was filtered
off and washed with ~10 ml of carbon tetrachloride,
the filtrate was evaporated, and the residue (~1.10 g)
was subjected to column chromatography on silica gel
using carbon tetrachloride as eluent to isolate 0.81 g
3-(4-Bromophenyl)-6,7,8,9,10-pentafluoro-8-
pentafluorophenoxy-1,4-dioxa-2-azaspiro[4.5]deca-
2,6,9-triene (VIa/VIb). A solution of N-hydroxy-4-
bromobenzimidoyl chloride, prepared from 0.80 g
(4 mmol) of 4-bromobenzaldehyde oxime and 0.64 g
(6 mmol) of tert-butyl hypochlorite in 15 ml of CCl4,
was cooled to –15°C, and a solution of 0.40 g
(4 mmol) of triethylamine in 5 ml of CCl4 was added
dropwise under stirring. After 5–10 min, the precipitate
was filtered off, a solution of 0.73 g (2 mmol) of
dienone I in 5 ml of CCl4 was added dropwise to the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 6 2012

KOVTONYUK et al.
786
filtrate, and the mixture was stirred for 3 days at room
temperature. According to the 19F NMR data, the
mixture contained ~51% of diastereoisomers VIa and
VIb at a ratio of 53:47 and ~30% of unreacted dienone
I. By column chromatography on silica gel using CCl4
as eluent we isolated 0.78 g of a viscous material
which was crystallized twice from ethanol to obtain
0.41 g (36%) of mixture VIa/VIb at a ratio of 71:29.
1H NMR spectrum: δ 7.63–7.77 ppm, m (4H, Harom).
19F NMR spectrum, δF, ppm: VIa: 0.5 m (2F, m-F),
6.2 t (1F, p-F), 7.6 m (2F, 6-F, 10-F), 8.5 m (2F, 7-F,
9-F), 10.3 m (2F, o-F), 41.2 m (1F, 8-F); VIb: 0.6 m
(2F, m-F), 6.2 t (1F, p-F), 7.9 m (2F, 6-F, 10-F), 8.5 m
(2F, 7-F, 9-F), 10.4 m (2F, o-F), 41.7 m (1F, 8-F).
Found, %: C 40.61; H 0.94; Br 14.43; F 33.74; N 2.20.
M 566. C19H4BrF10NO3. Calculated, %: C 40.45;
H 0.71; Br 14.16; F 33.68; N 2.48. M 564.
0.75 g (88%) of a colorless viscous liquid which con-
tained diastereoisomers VIIIa and VIIIb at a ratio of
1
55 : 45 (19F NMR). H NMR spectrum: VIIIa:
δ 2.21 ppm, s (3H, CH3); VIIIb: δ 2.23 ppm, s (3H,
19
CH3). F NMR spectrum, δF, ppm: VIIIa: 0.4 m (2F,
m-F), 6.1 t (1F, p-F), 7.6 m (4F, 6-F, 7-F, 9-F, 10-F),
10.5 m (2F, o-F), 41.9 m (1F, 8-F); VIIIb: 0.4 m (2F,
m-F), 6.0 t (1F, p-F), 7.6 m (4F, 6-F, 7-F, 9-F, 10-F),
10.3 m (2F, o-F), 41.6 m (1F, 8-F). Found, %: C 39.34;
H 0.64; F 44.82; N 2.83. M 426. C14H3F10NO3. Calcu-
lated, %: C 39.74; H 0.71; F 44.90; N 3.31. M 423.
6,7,8,9,10-Pentafluoro-3-(4-methoxyphenyl)-
8-nitro-1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-triene
(IXa/IXb). A solution of 1.26 g (12.5 mmol) of
triethylamine in 10 ml of CCl4 was added dropwise
under stirring at –18°C to a solution of N-hydroxy-4-
methoxybenzimidoyl chloride prepared from 1.8 g
(12.5 mmol) of 4-methoxybenzaldehyde oxime and
2.06 g (19 mmol) of tert-butyl hypochlorite in 40 ml of
CCl4. The mixture was stirred for 5–10 min, 1.39 g
(6 mmol) of pentafluoro-4-nitrocyclohexa-2,5-dien-1-
one (II) was added in small portions, and the mixture
was stirred for 16 h at –18°C. The precipitate was
filtered off and washed with ~10 ml of CCl4, the
filtrate was evaporated, and the residue (~3.51 g) was
subjected to column chromatography on silica gel
using CCl4 as eluent to isolate 1.19 g (52%) of a light
yellow viscous liquid containing isomers IXa and IXb
6,7,8,9,10-Pentafluoro-3-(3-nitrophenyl)-8-penta-
fluorophenoxy-1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-
triene (VIIa/VIIb). A solution of 1.80 g (4.9 mmol) of
dienone I in 5 ml of CH2Cl2 was added under stirring
to a solution of 1.01 g (6.2 mmol) of 3-nitrobenzo-
nitrile oxide (prepared as described in [11]) in 40 ml of
CH2Cl2, and the mixture was stirred for 3 days at room
temperature. According to the 19F NMR data, the mix-
ture contained ~75% of unreacted dienone I and ~25%
of diastereoisomers VIIa and VIIb. The mixture was
diluted with 40 ml of CCl4, methylene chloride was
distilled off, and the mixture was heated for 5 h at
80°C. According to the 19F NMR data, it contained
~70% of dienone I and ~26% of VIIa and VIIb at
1
at a ratio of 50:50 (19F NMR). H NMR spectrum, δ,
ppm: 3.90 s (6H, OCH3), 7.00 m (4H, Harom), 7.72 m
(2H, Harom), 7.76 m (2H, Harom). 19F NMR spectrum, δF,
ppm: 8.5 m and 8.6 m (2F each, 7-F, 9-F), 16.2 m (4F,
6-F, 10-F), 27.6 m and 27.8 m (1F each, 8-F). Found,
%: C 44.79; H 2.14; F 25.19; N 6.67. M 383.
C14H7F5N2O5. Calculated, %: C 44.46; H 1.87;
F 25.12; N 7.41. M 378.
19
a ratio of 50:50. F NMR spectrum of VIIa/VIIb, δF,
ppm: 0.6 m (4F, m-F), 6.3 t (2F, p-F), 7.5 m (4F, 6-F,
10-F), 9.4 m (4F, 7-F, 9-F), 10.4 m (4F, o-F), 41.4 m
and 41.0 m (1F each, 8-F).
6,7,8,9,10-Pentafluoro-3-methyl-8-pentafluoro-
phenoxy-1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-triene
(VIIIa/VIIIb). A solution of 0.36 g (6 mmol) of
acetaldehyde oxime in 15 ml of CCl4 was cooled to
4°C, a solution of 0.87 g (8 mmol) of tert-butyl
hypochlorite in 5 ml of CCl4 was added dropwise
under stirring, the mixture was stirred for 5 h at room
temperature and cooled to –18°C, a solution of 0.6 g
(6 mmol) of triethylamine in 5 ml CCl4 was added
dropwise, the mixture was stirred for 2–3 min, and
a solution of 0.73 g (2 mmol) of dienone I in 5 ml of
CCl4 was added. The mixture was stirred for 16 h at
–18°C, the precipitate was filtered off and washed with
~10 ml of CCl4, the filtrate was evaporated, and the
residue (1.18 g) was subjected to column chromatog-
raphy on silica gel using CCl4 as eluent to isolate
8-Chloro-6,7,8,9,10-pentafluoro-3-(4-methoxy-
phenyl)-1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-triene
(Xa/Xb). A solution of 0.8 g (8 mmol) of triethylamine
in 10 ml of CCl4 was added dropwise under stirring at
–16°C to a solution of N-hydroxy-4-methoxybenz-
imidoyl chloride [prepared from 1.2 g (8 mmol) of
4-methoxybenzaldehyde oxime and 1.2 g (11 mmol) of
tert-butyl hypochlorite] and 0.87 g (4 mmol) of
4-chloropentafluorocyclohexa-2,5-dien-1-one (III) in
30 ml of carbon tetrachloride, and the mixture was
stirred for 2 h at –16°C and for 16 h at room tempera-
ture. The precipitate was filtered off and washed with
~5 ml of CCl4. The filtrate was passed through
a column charged with silica gel using CCl4 as eluent
to isolate 0.75 g (51%) of a light yellow viscous liquid
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SYNTHESIS OF FLUORINE-CONTAINING 1,4-DIOXA-2-AZASPIRO[4.5]DECA-2,6,9-TRIENES
787
containing ~95% of diastereoisomers Xa and Xb at
a ratio of 52:48. H NMR spectrum, δ, ppm: 3.90 s
direct method and was refined by the full-matrix least-
1
squares procedure in anisotropic approximation for
non-hydrogen atoms using SHELX-97 software pack-
age. The positions of hydrogen atoms were refined
according to the riding model. The final divergence
factors were R1 = 0.0507, wR2 = 0.1256, goodness of
fit 1.061 [2126 reflections with I > 2σ(I)] and R1 =
0.0860, wR2 = 0.1581 (all reflections). The set of
crystallographic data for compound IVa was deposited
to the Cambridge Crystallographic Data Centre
(entry no. CCDC 860 196) and is available at
www.ccdc.cam.ac.uk/data_request/cif.
(3H, OCH3), 6.98 m (2H, Harom), 7.72 m (2H, Harom).
19F NMR spectrum, δF, ppm: 6.2 m (4F, 6-F, 10-F),
12.1 m (4F, 7-F, 9-F), 48.2 m and 48.3 m (1F each,
8-F). Found, %: C 45.21; H 1.93; F 25.55; N 3.70.
C14H7ClF5NO3. Calculated, %: C 45.74; H 1.92;
F 25.84; N 3.81.
6,8,10-Trifluoro-7,8,9-tris(pentafluorophenoxy)-
3-phenyl-1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-triene
(XIIa/XIIb). Sodium pentafluorophenoxide, 0.90 g
(4.0 mmol), was added in portions under stirring at
room temperature to a solution of 0.73 g (2.0 mmol) of
dienone I in 20 ml of acetone. The mixture was stirred
for 30 min and evaporated under reduced pressure
(20 mm, bath temperature ≤20°C; cf. [12]). Carbon
tetrachloride, 40 ml, was added to the residue,
N-hydroxybenzimidoyl chloride prepared from 0.48 g
(4 mmol) of benzaldehyde oxime and 0.65 g (6 mmol)
of tert-butyl hypochlorite was then added, the mixture
was cooled to 4°C, and a solution of 0.4 g (4 mmol) of
triethylamine in 5 ml of CCl4 was added dropwise
under stirring. The mixture was then treated as
described above for IVa/IVb to isolate 1.42 g of
a crystalline substance (87%) containing ~80% of
diastereoisomers XIIa and XIIb at a ratio of 55:45
(19F NMR). 19F NMR spectrum, δF, ppm: XIIa: –0.2 m
(2F, m-F), 0.5 m (4F, m-F), 3.4 t (2F, p-F), 5.2 t (1F,
p-F), 6.0 m (4F, o-F), 10.1 m (2F, 6-F, 10-F), 10.5 m
(2F, o-F), 46.2 m (1F, 8-F); XIIb: –0.1 m (2F, m-F),
0.5 m (4F, m-F), 3.3 t (2F, p-F), 5.2 t (1F, p-F), 6.0 m
(4F, o-F), 10.0 m (2F, 6-F, 10-F), 10.2 m (2F, o-F),
46.8 m (1F, 8-F). Triple recrystallization of mixture
XIIa/XIIb from petroleum ether (bp 40–70°C) gave
a sample (0.41 g) containing ~93% of XIIa and XIIb
at a ratio of 89:11. Found, %: C 46.05; H 0.68;
F 42.17; N 1.88. M 803. C31H5F18NO5. Calculated, %:
C 45.78; H 0.62; F 42.05; N 1.72. M 813.
REFERENCES
1. Finley, K.T., The Chemistry of the Quinonoid Com-
pounds, Patai, S. and Rappoport, Z., Eds., Chichester:
Wiley, 1988, vol. 2, part 1, chap. 11, p. 654.
2. Kobrina, L.S., Izv. Ross. Akad. Nauk, Ser. Khim., 2002,
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X-Ray analysis of 6,7,8,9,10-pentafluoro-8-penta-
fluorophenoxy-3-phenyl-1,4-dioxa-2-azaspiro[4.5]-
deca-2,6,9-triene (IVa). The X-ray diffraction data
were acquired at 297 K from a 0.16×0.34×0.6-mm
single crystal of IVa on a Bruker P4 diffractometer
(MoKα irradiation, graphite monochromator). No
correction for absorption was introduced (µ = 0.187).
Monoclinic crystal system, space group C2/c; unit cell
parameters: a = 23.298(2), b = 5.6272(4), c =
28.021(2) Å; β = 95.717(7)°; V = 3655.4(5) Å3;
C19H5F10NO3; Z = 8; dcalc = 1.763 g/cm3. Total of 3526
reflections were measured (2θ < 52°), 3472 of which
were independent. The structure was solved by the
11. Wiley, R.H. and Wakefield, B.J., J. Org. Chem., 1960,
vol. 25, p. 546.
12. Kovtonyuk, V.N. and Kobrina, L.S., Zh. Org. Khim.,
1991, vol. 27, p. 2289.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 6 2012