Triphenylphosphanodefluorination of fluoranil and its derivatives

Article abstract of DOI:10.1016/j.jfluchem.2015.08.018

The reaction of 2-X-trifluoro-1,4-benzoquinones (X = F, Cl, Me, OMe) with triphenylphosphane in various solvents (C₆H₆, Et₂O, THF, dioxane, MeOH, aq. dioxane and Me₂SO) has been investigated. It was shown that: (1) the quinones react with PPh₃ at an oxygen atom and at a carbon atom with formation of products of reduction and of triphenylphosphanodefluorination, accordingly; (2) the use of more polar solvents, such as MeOH, aq. dioxane and Me₂SO, leads to an increase in products of phosphanodefluorination; (3) triphenylphosphanodefluorination of 2-X-trifluoro-1,4-benzoquinones (X = Cl, Me, OMe) takes place at positions 5 and 6 to X in ratios depending on the nature of the substituent X. Possible reasons for obtained results are discussed in detail. The entry of solvent molecule into products of phosphanodefluorination of fluoranil was observed in MeOH. The triphenyl(3,4,6,6-tetrafluoro-2-oxido-5-oxocyclohexa-1,3-dien-1-yl)phosphanium and its analogs serves as starting material for a new type of nitrogen-containing phosphorus compounds. The structures of isolated betaines were proved by the XRD and the ¹⁹F, ³¹P{¹H} and ¹³C{¹H} NMR data.

Full text of DOI:10.1016/j.jfluchem.2015.08.018

Journal of Fluorine Chemistry 180 (2015) 21–32
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Triphenylphosphanodefluorination of fluoranil and its derivatives
S.I. Zhivetyeva a, G.A. Selivanova a, , L.I. Goryunov a,1, I.Yu. Bagryanskaya a,b
V.D. Shteingarts a,1
,
*
a Institute of Organic Chemistry, Russian Academy of Sciences, 630090 Novosibirsk, Russia
b National Research University – Novosibirsk State University, 630090 Novosibirsk, Russia
A R T I C L E I N F O
A B S T R A C T
Article history:
The reaction of 2-X-trifluoro-1,4-benzoquinones (X = F, Cl, Me, OMe) with triphenylphosphane in
various solvents (C6H6, Et2O, THF, dioxane, MeOH, aq. dioxane and Me2SO) has been investigated. It was
shown that: (1) the quinones react with PPh3 at an oxygen atom and at a carbon atom with formation of
products of reduction and of triphenylphosphanodefluorination, accordingly; (2) the use of more polar
solvents, such as MeOH, aq. dioxane and Me2SO, leads to an increase in products of phosphanode-
fluorination; (3) triphenylphosphanodefluorination of 2-X-trifluoro-1,4-benzoquinones (X = Cl, Me,
OMe) takes place at positions 5 and 6 to X in ratios depending on the nature of the substituent X. Possible
reasons for obtained results are discussed in detail. The entry of solvent molecule into products of
phosphanodefluorination of fluoranil was observed in MeOH. The triphenyl(3,4,6,6-tetrafluoro-2-oxido-
5-oxocyclohexa-1,3-dien-1-yl)phosphanium and its analogs serves as starting material for a new type of
nitrogen-containing phosphorus compounds. The structures of isolated betaines were proved by the
XRD and the 19F, 31P{1H} and 13C{1H} NMR data.
Received 18 June 2015
Accepted 11 August 2015
Available online 28 August 2015
Keywords:
Fluorinated 1,4-benzoquinones
Triphenylphosphane
Triphenylphosphanodefluorination
Phosphanium betaines
ß 2015 Elsevier B.V. All rights reserved.
1. Introduction
The reactions of chloranil, its less halogenated derivatives and
bromanil with phosphanes led to betaines of type 2, if they are
Many found in nature [1] and synthesized 1,4-benzoquinone
derivatives exhibit high and various biological activity [2a–d].
1,4-Naphthoquinone derivatives showed antioxidant and
anti-malarial properties [3a,b]. Polyfluorinated functionalized
1,4-naphthoquinones can be inhibitors of cancer cells growth
[4a–f]. As recently reported reactions hexa- and 2,5,6,7,8-
pentafluorophenyl 1,4-naphthoquinone with phosphanes PPh2R
(R = Me, Ph, 2,5-F2C6H3) lead to the betaines with phosphanium
structure 1 (Chart 1) [5], which exhibit similar biological activity
[6]. The similar reactions of polyfluorinated benzoquinones were
not reported so far. The interaction of polyhaloquinones with
phosphanes and phosphites has been attracting the attention of
researchers for a long time [7]. It is, in particular, due to that this
reaction, being carried out in the presence of water or alcohol,
leads to phosphanium betaines 2 (Chart), which are of interest
from the point of view of their electronic structure in terms of
resonance of ketophosphorane 2A, ylide 2B and quinonebetaine
structures 2C, 2D.
formed, as minor products but mainly phosphaniumphenolates 3
(Chart) formed by reduction of quinones [8–10]. Thus, chloranil was
reported to react with PPh3 [8] and P(NEt2)3 [9] to give only the
corresponding phenolates 3 or their disproportion equivalents – the
adducts of the respective triphenyl(4-[(triphenylphosphaniumy-
l)oxy]phenoxy)phosphanium and benzene-1,4-bis(olate) [8].
In reactions of chloranil with PEt2Ph [10] and bromanil with
P(NEt2)2X (X = NEt2, OEt) [9], alongside with prevailing reduction
of quinones, phosphanodehalogenation and the subsequent
hydrolysis of a primary reduction product occur to eventually
lead to the corresponding betaines 2. However, the mechanism of
the reaction of quinones with organophosphorus compounds and
structure of products, particularly in the case of preparing the
compounds are internal salts such as betaines 2C, 2D and ylides 2B,
which are very sensitive to the polarity of the medium, can not be
discussed without taking into account the influence of solvents.
The nature of the solvent as a factor influencing the conversion
halogenanils by the action of phosphorus compounds was not
discussed.
In view of the above, in the present work the interaction of
fluoranil 4 with PPh3 in various solvents was studied and, unlike
not only reduction [8–10], but also triphenylphosphanodefluor-
ination was found to occur thus allowing (after hydrolysis of the
*
Corresponding author.
E-mail address: galseliv@nioch.nsc.ru (G.A. Selivanova).
1
Deceased.
http://dx.doi.org/10.1016/j.jfluchem.2015.08.018
0022-1139/ß 2015 Elsevier B.V. All rights reserved.

22
S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
O
PRPh2
F
R = Ph, 2,5-F2C6H3, Me
O
O
1
-
O
O
-
O
O
+
+
+
PR1R2R3
O
Y
X
PR1R2R3
-
PR1R2R3
Y
X
PR1R2R3
O
Y
X
Y
X
O
O
O
2A
O
2B
O
2C
O
+
2D
OPR3
Xn
X = Cl, Br
-
O
3
Chart 1. Structure 1–3.
highly moisture-sensitive primary product registered by the 19F
and 31P{1H} NMR spectra) to prepare the corresponding (4,5-
difluoro-2-oxido-3,6-dioxocyclohexa-1,4-dien-1-yl)triphenylpho-
sphanium 5. Analogous reaction for 2-X-trifluoro-1,4-benzoqui-
nones (X = Cl, Me, OMe) were revealed. Besides, the possibility
involving the primary triphenylphosphanodefluorination products
in situ in the reactions with nucleophiles (aromatic amines)
was demonstrated to give highly functionalized derivatives of
benzoquinone.
structure of the putative betaine 8 alongside with the signals
belonging to triphenyldifluorophosphorane 10. Thus, in the NMR
19F spectrum (see ESI2 Supporting Chart) of betaine 8 displayed
three multiplets at dF ꢁ74.3 ppm (ddd, 2F, 3JFP, 4JFF ꢀ7, 5JFF = 3 Hz;
CF2), that is in line with data [11a,b] reported for
a,a-
4
3
difluoroketones, ꢁ125.0 ppm (ddt, 1F, JFP = 13, JFF = 10 and
3
4
5JFF = 3 Hz; F3) and ꢁ154.1 ppm (dt, 1F, JFF ꢀ10, JFF ꢀ7 Hz; F4).
The phosphorane 10 resonance was observed at dF ꢁ39.1 ppm (d,
1F, 1JFP = 665 Hz). In the 31P{1H} NMR spectrum of the solution the
4
3
5
signals at dP 15.9 ppm (dtd, 1P, JPF ꢀ13, JPF ꢀ7, JPF ꢀ2 Hz) and
1
ꢁ54.5 ppm (t, 1P, JPF = 665.0 Hz) belonged to compounds 8 and
2. Results and discussion
10, respectively. The observed phosphorane 10 NMR character-
istics correspond to [12]. The signals of betaine 5 were observed
along with the signals of 8 that testified the latter was undergone
extremely easy hydrolysis (Scheme 1) with atmospheric moisture
without the addition of water.
2.1. Reaction of fluoranil with PPh3
By analogy with the literature data reactions were carried out in
C6H6 [8–10] and more polar solvents too (anhydrous ethers, Et2O,
THF, dioxane, as well as MeOH, aq. dioxane and Me2SO). The product
distributions and structures were inferred from NMR (ESI2
Supporting Table 1 and Table 2) and XRD data (ESI2 Supporting
Table 3).
According to Scheme 1, formation of 10 (as well as 6) can testify
for the reduction of quinone 4 by PPh3 to compete with its
phosphanodefluorination which is suggested, by analogy with
rationale of the similar chloranil transformation [8], to lead to
phosphanium–zwitterion 11 or its disproportionation derivative
11a. Thus two equivalents of fluoride anion are needed for
formation of one equivalent 10, but only the salt 7 being its source.
Accordingly, two equivalents of the cation of this salt should bind
with one equivalent of the tetrafluorohydroquinone dianion
13. Since there were no signals in the NMR spectra of the solution
which could be assigned to any adduct formed by these species, it
was reasonably expected to be contained in the precipitate formed
in the reaction.
2.1.1. Reaction in C6H6
The interaction of quinone 4 with PPh3 (1:1) resulted after
quenching by water in the solution and the precipitate. According
to the 19F and 31P{1H} NMR spectra, the solution contained (4,5-
difluoro-2-oxido-3,6-dioxocyclohexa-1,4-dien-1-yl)triphenylpho-
sphanium 5(discussion of its structure in terms of the 2A–D resonance
see below Section 2.3) (ꢀ30% NMR yield, 19% isolated yield, here and
hereinafter, per initial quinone 4) and triphenylphosphaneoxide 6
(ꢀ50% NMR yield) (Scheme 1). The structure of betaine 5 was proved
by the XRD analysis (see ESI2 Supporting Figure 1).
The formation of betaine 5 is reasonably explained by the
primarily occurring phosphanodefluorination of quinone 4 to give
salt 7 which can reversibly turn into triphenyl(3,4,6,6-tetrafluoro-
2-oxido-5-oxocyclohexa-1,3-dien-1-yl)phosphanium 8 and qui-
none 9, and the subsequent hydrolysis of compounds 7–9
(compare [8–10]). The regioselectivity of hydrolysis reflected by
structure of 5 is believed to be caused by the resonance charge
distribution in the cation of salt 7, through intermediacy of which
hydrolysis of 8 and 9 can proceed also.
The ratio of compound 5 to the sum 6 and 10 determines the
contribution of phosphanodefluorination and reduction.
According to the NMR data the benzene solution contained 5
(27% NMR yield) and 6 (25% NMR yield).
The amount of precipitate was ꢀ55% from the initial
compounds, what could point to a significant contribution of
the reaction of reduction quinone 4. The 19F and 31P{1H} NMR
spectra of the precipitate solution in Me2SO displayed the presence
of a small amount of betaine 5 (ꢀ1% yield per initial quinone 4), 6
(ꢀ1% yield per initial PPh3) and not identified products. Thus, the
total yields of betaine 5 and 6 were 28% and 26% respectively.
Along with this in the 19F NMR spectrum the unresolved signal was
observed at ꢁ163.7 to ꢁ156.0 ppm which is expected for
tetrafluorohydroquinone 14 (ꢁ164.7 ppm [13]) or some of its
derivatives. The above data testifies that in the reaction with PPh3
To experimentally prove this reaction pathway, the reaction of
4 with PPh3 was carried out in carefully dried C6H6 in an
atmosphere of dry argon and right after reagents mixing the
signals were found out in the 19F and 31P{1H} NMR spectra of a
solution thus formed which are fairly compatible with the
quinone
4 undergoes triphenylphosphanodefluorination and
reduction in a ꢀ1:1 ratio.
2
An addition of a 0.6-equivalent of aniline 15 to a solution
prepared by reaction of quinone 4 and PPh3 gave an additional
Electronic Supplementary Information (ESI) available: See http://dx.doi.org/10.
1016/j.jfluchem.2015.08.018.

S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
23
Scheme 1. Reaction of 4 with PPh3.
evidence for formation of the betaine 8; according to NMR data [4-
fluoro-2-oxido-5-oxo-3-(phenylamino)-6-(phenylimino)cyclo-
hexa-1,3-dien-1-yl]triphenylphosphanium 16 was formed (29%
isolated yield) (Scheme 2).
the solutions contained betaines 8 and 5 (1.0:1.3, in Et2O; and
1.0:0.1–1.0, in THF and dioxane), as well as 10 in a (0.5–1.0)-fold
amount with respect to the sum of betaines. In the 19F NMR spectra
the signal was observed belonging with a high probability to
hydrogen fluoride (singlet at dF ꢁ186.6 ppm in Et2O, ꢁ193.5 ppm
in THF, and ꢁ192.3 ppm in dioxane) (cf. dF ꢁ26.9 ppm reported for
Keeping of the benzene solution of fluoranil 4 and PPh3 for 3 h
with following treatment by a 2.0 fold excess of aniline 15 resulted
in the formation of betaine – [4-fluoro-2-oxido-3,6-dioxo-5-
(phenylamino)cyclohexa-1,4-dien-1-yl]triphenylphosphanium
17 (27% isolated yield) (Scheme 2), which is product of the
reaction between aniline 15 and betaine 5, the latter is formed,
apparently, as a result of hydrolysis of 7–9 by atmospheric moisture
or including residual moisture in aniline. The structures of betaines
16 and 17 were solved by XRD analysis (see ESI2 Supporting
Figure 2).
liquid HF with C6F6 as external standard,
respect to CFCl3 [14]).
d
F = ꢁ162.9 ppm with
In all cases the amount of precipitates were ꢀ30% from
the initial compounds, which is two times less in comparison
with the reaction in anhydrous C6H6. The NMR data of the
precipitate solutions in Me2SO displayed the presence of not
identified products, possibly, the derivatives of tetrafluorohy-
droquinone.
It is possible that the betaine 5 partly formed due to the
interaction of the salt 7 with ethers as O-centered nucleophile,
followed by cleavage of C–O bonds of –O+Alk2 fragment of adduct
by fluoride ion. The probability of such transformations is high due
to the similar reactions of hexafluoro-1,4-naphthoquinone with
PPh3 in MeOH [5]. However, in general, betaine 5, apparently
is formed by the hydrolysis of compounds 7–9, the moisture is
penetrated into solution with the addition of PPh3 to 4. This is
evidenced by the fact that, according to 19F NMR data in carefully
dried dioxane in dry-box, contained betaine 8 with a small trace of
betaine 5 (ꢀ10%).
2.1.2. Reactions in anhydrous ethers (Et2O, THF, dioxane) and aq.
dioxane
The reaction of 4 with PPh3 (1:1) under dried argon gives a
solution and a precipitate in all ethers. According to 19F NMR data,
In order to determine the sequence in which fragments of
aniline 15 included in the structure of betaine 16, to a mixture of
compounds 8 and 5 in dioxane (ꢀ1.3:1.0, according to 19F NMR
spectrum) was added 0.2 equivalent of aniline 15. In addition to
signals of betaine 5 the spectrum contained two equal intensity
4
3
multiplets at dF ꢁ132.1 ppm (dd, 1F, JFP ꢀ13, JFF ꢀ10 Hz) and
3
ꢁ151.5 ppm (d, 1F, JFF ꢀ10 Hz). In the 31P{1H} NMR spectrum
4
signal at dP 13.2 ppm (d, JPF ꢀ13 Hz) was observed. This NMR
characteristics are consistent with the presented structure of
betaine – [3,4-difluoro-2-oxido-5-oxo-6-(phenylimino)cyclohexa-
1,3-dien-1-yl]triphenylphosphanium 18. At the same time, there
Scheme 2. Reaction of 4 with PPh3 and following treatment of the benzene solution
with aniline 15.

24
S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
Scheme 3. Reaction of 4 with PPh3 and following treatment with anilines 15 and 19 in dioxane.
was no signal of betaine 8 with the doubled intensity in the range
from ꢁ75.0 to ꢁ74.0 ppm (see ESI2 Supporting Chart).
phosphanodefluorination is carried out at the position of –CF55CF–
bond, which associates with more acceptor of the two carbonyl
groups of salt 7, due to the fact that in the meta-position to it stands
cationic substituent Ph3P+.
The attempt to isolate betaine 18 is failed, but the addition of
an excess of 4-phenoxyaniline 19 to the reaction mixture gives a
new compounds – {4-fluoro-2-oxido-5-oxo-3-[(4-phenoxyphe-
nyl)amino]-6-(phenylimino)cyclohexa-1,3-dien-1-yl}triphenyl-
2.1.3. Reactions in Me2SO
phosphanium 20
and {4-fluoro-2-oxido-3,6-dioxo-5-[(4-
Initially in the NMR 19F spectrum of a solution of quinone 4 in
Me2SO there are along with singlet at dF ꢁ143.9 ppm, which belong
to 4, two multiplets at ꢁ161.1 and ꢁ136.5 ppm. The location and
structure of these signals correspond to those of fluorine atoms F2,6
phenoxyphenyl)amino]cyclohexa-1,4-dien-1-yl}triphenylpho-
sphanium 21. Betaines 20 and 21 were isolated with 18% and 26%
yields respectively by TLC (Scheme 3). The structure of 21 is
established by the XRD analysis (see ESI2 Supporting Figure 3).
Conducting the reaction in aq. dioxane leads to a noticeable
increase in output of products of phosphanodefluorination,
apparently, in consequence of increasing contribution of this
direction of reaction in the total result of the interaction in
comparison to reduction. The interaction of 4 with PPh3 (1:1) in
aq. dioxane (ꢀ1:20) system resulted in solution and precipitate.
According to the NMR data the solution contained compounds 5
and 6 (ꢀ60% and ꢀ24%). Betaine 5 was isolated with 24% yield
that currently makes conducting the reaction in these conditions
the most convenient method of synthesis this compound. The
resulting precipitate (the amount of precipitate was ꢀ13% from
the initial compounds) contained, as described previously [15]
pure betaine – [2,4-dioxido-3,6-dioxo-5-(triphenylphosphaniu-
myl)cyclohexa-1,4-dien-1-yl]triphenylphosphanium 22 (9% iso-
lated) (Scheme 4). In the same solvent with a molar ratio of 4
with PPh3 = 1.0:3.0, betaine 22 was isolated with 53% yield. In
the reaction of betaine 5 with PPh3 (1.0:2.5) in dioxane, betaine
22 was isolated with 51% yield (Scheme 4). This testifies that
betaine 5 is a precursor of bis-betaine 22.
and F3,5
, respectively. According to data of polyfluorinated
cyclohexa-2,5-dien-1-ones [16] we suggest formation of cyclo-
hexadienone 24 – the product of addition Me2SO to the carbonyl
group quinone 4 (Scheme 5), the ratio of 4 and supposed 24 is ꢀ3:1.
In this regard, we can not exclude that the salt 7 is formed only (or
not so much) directly from the quinone 4, but in a roundabout way
– through its reversible transformation into cyclohexadienone 24
and triphenylphosphanodefluorination last (Scheme 5).
The interaction of 4 with PPh3 (1:1) in Me2SO resulted after
quenching water in the solution. A precipitate was not formed.
According to the NMR data this solution contained betaines 5, 22, 25
(ꢀ40%, 2% and 20%, respectively) and 6 (ꢀ10%). The ratio of
triphenylphosphanodefluorination/reduction of 4 is ꢀ6:1 ratio. The
interaction of 4 with 6 equivalent of PPh3 in Me2SO under dried
argon gave
a mixture, from which known [15] betaine –
triphenyl[2,4,6-trioxido-3,5-bis(triphenylphosphaniumyl)phenyl]-
phosphanium 25 was isolated with 21% yield. A probable path of his
formation, as shown in Scheme 5, involves the accession of PPh3 to
the bis-betaine 22 at a more acceptor of its two carbonyl groups and
subsequent deoxygenation of arising betaine – [2,2,2-triphenyl-
1,2l5-oxaphosphirane (4,8-dioxido-6-oxo-2,2,2-triphenyl-7-(tri-
phenylphosphaniumyl)-1-oxa-2l5-phosphaspiro[2.5]octa-4,7-dien-
5-yl]triphenylphosphanium) 26. The role of oxygen-centered
nucleophile, possibly, executes a solvent (Scheme 5).
However, there cannot be discarded the path including
phosphanodefluorination salt 7 with the formation of salt 23
and its following hydrolysis. The obtained result means that during
phosphanodefluorination of 7, nucleophilic attack was not aimed
at neighboring position of Ph3P+ group but at a fragment of –
CF55CF– bond. Given that during the reaction the reagent enters the
cationic state, such a change of orientation could be due to steric
and electrostatic hindrances of Ph3P+ group, which prevent the
attack at neighboring position by bulky PPh3 reagent. Thus,
2.1.4. Reactions in MeOH
As described above for solution in Me2SO, in the NMR 19F
spectrum of 4 in MeOH along with singlet at dF ꢁ143.9 ppm, which
belong to 4, there are two multiplets at ꢁ157.7 and ꢁ136.9 ppm of
Scheme 4. Reaction of 4 with PPh3 in dioxane – H2O.

S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
25
at 100 8C resulted to 28 [17]. It is similar to the above reaction in
Me2SO. The equilibrium between 4 and 27 has uncertainty in the
transition from 4 to the product of its nucleophilic defluorination,
in this case the quinone 28 (Scheme 6).
The interaction of 4 with PPh3 (1:1) in MeOH at room
temperature 1 h, according to the NMR data resulted in the
mixture of mono-, di- and trisubstituted products. The precipitate
was not formed. Reaction mixture contained betaine – (4-fluoro-
5-methoxy-2-oxido-3,6-dioxocyclohexa-1,4-dien-1-yl)triphe-
nylphosphanium 29, betaines 22 and 25 (ꢀ35%, 18% and 7%,
respectively). The fluoranil 4 and 6 (ꢀ10% and 30%, respectively) were
present too. Quinone 4 with PPh3 undergoes triphenylphosphanode-
fluorination and reduction in aꢀ2:1 ratio. In similar experiment with a
larger scale the reaction of 4 with PPh3 (1:1) gave a precipitate, which
was a pure betaine 29 with 49% yield. The structure of betaine 29 was
proved by the XRD analysis (see ESI2 Supporting Figure 4).
Formally, obtained result does not provide the information
about the sequence of phosphano- and methoxydefluorination on
the path from 4 to 29. However, because 4 practically does not
undergo methoxydefluorination over time 1 h at the room
temperature, in the presence of PPh3 it is completely converted
into betaine 29 and other di- and trisubstituted products. It can
be concluded that first occur phosphanodefluorination of 4
(or its adduct 27 with MeOH) with the formation of salt
7. Methoxydefluorination of this salt (or it adduct with MeOH)
gives the quinone 30, which undergoes methoxydefluorination
and demethylation (the sequence of these transformations is
unclear) (Scheme 6).
Scheme 5. Reaction of fluoranil 4 with PPh3 in Me2SO.
The 19F NMR data indicate on a high probability of the
cyclohexadienones formation as a result of addition of solvent
(Me2SO, MeOH) to the carbonyl group quinone 4. There are two
possible ways of realization of nucleophilic dehalogenation of 4:
either directly in the quinone or in the cyclohexadienone, which is
in the equilibrium with 4 with the subsequent regeneration of the
quinone structure. Polyfluorinated cyclohexadienones very easily
undergo nucleophilic defluorination [19]. It is possible that
cyclohexadienone even more active than quinone to nucleophile
addition to carbon–carbon double bond, as in this case the
quinone lost its conjugation with two carbonyl groups, and in case
of cyclohexadienone – with only one. In each case the question of
which way proceeds a reaction of nucleophilic substitution in
quinone, requires special investigation.
Fluoranil 4 with PPh3 in various solvents undergoes phospha-
nodefluorination and reduction unlike chloranil, which undergoes
only reduction [8–10]. The absence of phosphanodefluorination for
chloranil was explained by steric hindrance of the nucleophilic
attack on –CCl55CCl– bond and high oxidation potential of chloranil
[8]. In the case of fluoranil 4 along with reduction is implemented
cyclohexadienone 27, which is the product of MeOH conjunction to
the carbonyl group of 4 (Scheme 6). After exposure of the solution
1 h, quinone 4 was returned quantitatively. In a concentration
range of 0.12–1.04 mol/l the ratio of compounds 4 and 27 is about
ꢀ7:1 and remaining constant over 14 days, up to ꢀ40% conversion
of quinone 4 into 2-methoxy-trifluoro-1,4-benzoquinones 28
(infrared spectrometry data and NMR 19F characteristics corre-
spond to [13,17]).
Previously [18] it was reported that 4 reacts with MeOH at room
temperature for a long time (strictly not specified) with formation
of 2,5-dimethoxy-3,6-difluoro-1,4-benzoquinone. Regioselectivity
of fluoride substitution could be reasonable explain to the
deactivation of position 3 in the primary product of methoxyde-
fluorination 28 due to p-donor effect of 2-MeO-group. The latter, in
addition, reduces electron-acceptor effect of conjugated with her
4-C55O group, resulting what secondary substitution take place at
the 5 position of the fragment –CF55CF–, which paired with more
acceptor 1-C55O group. The interaction of 4 with MeOH for 30 min
Scheme 6. Reaction of 4 with PPh3 in MeOH.

26
S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
Scheme 7. Formation of CTC in reaction of 4 with PPh3.
phosphanodefluorination, suggests that from these two reasons,
the first is more important, besides this is supplemented by a
greater electrophilicity of the carbon atom of C–F bond compared
to C–Cl bond. The role of oxidation potential of the quinone
detected by comparing the presented above yield of betaine 5 with
almost quantitative yield of its analog in the reaction of
hexafluoro-1,4-naphthoquinone with PPh3 [5].
products of phosphanodefluorination of quinone 32 – isomeric
betaines (3-chloro-4,6,6-trifluoro-2-oxido-5-oxocyclohexa-1,3-
dien-1-yl)triphenylphosphanium 33, (4-chloro-3,6,6-trifluoro-2-
oxido-5-oxocyclohexa-1,3-dien-1-yl)triphenylphosphanium 34
respectively, and the product of chlorine substitution – betaine
8 (Scheme 8). Besides initial quinone 32 and 10 (14% and ꢀ77%,
respectively) (Scheme 8) and corresponding to the hydrolysis
The comparison of the results of the interaction of quinone 4
with PPh3 in C6H6 and aq. dioxane indicates the tendency for
increment of phosphanodefluorination in its competition with the
reduction with an increase in the polarity of the medium. This
effect corresponds to the fact that the system undergoes a larger
polarization during phosphanodefluorination than during reduc-
tion. Previously two points of view on the mechanism of reduction
of halogenated quinones with PPh3 were expressed. Firstly, it is a
direct nucleophilic attack at oxygen atom with the formation of
betaine 11 or 11a [8]. However, the reported effect of solvent
polarity does not correspond to this conception, because during the
formation of betaine 11 system undergoes, as it can be assumed,
the greater polarization than during the nucleophilic attack on the
carbon–carbon double bond with the formation of intermediate 31
(Scheme 7). By analogy with the mechanism of interaction of
chloranil with trialkylphosphite [20] we assume that the first
and common intermediate for the both competing reaction is a
complex with charge transfer (CTC) between the quinone 4 and
PPh3. The decrease in products of reduction with increasing
polarity of the solvent can be explained by the fact that
during this transformation the transition from CTC to radical-
anion is accompanied by delocalization of the negative charge,
while the transition from the CTC to the intermediate of
phosphanodefluorination 31 is accompanied by its localization
(Scheme 7).
betaines – (5-chloro-4-fluoro-2-oxido-3,6-dioxocyclohexa-1,4-
dien-1-yl)triphenylphosphanium 35 and (4-chloro-5-fluoro-2-
oxido-3,6-dioxocyclohexa-1,4-dien-1-yl)triphenylphosphanium
36 and 5 present in the reaction mixture too. The ratio of isomeric
betaines is (33 + 35):(34 + 36):(8 + 5) = 12:1:3, which are deter-
mined by the attack of PPh3 at positions 6, 5 and 2 and show a
much higher activity of positions 6 and 2 compared to position
5 in regard to attack of nucleophile. Quinone 32 with PPh3
undergoes triphenylphosphanodefluorination and reduction in
a (33 + 34 + 35 + 36 + 8 + 5):(10) = ꢀ1:10 ratio.
In the NMR 19F spectrum betaines 33 and 34 displayed two
multiplets each with 2:1 intensity ratio at dF ꢁ73.5 ppm (dd, 2F,
4JFF
,
3JFP ꢀ7 Hz, CF2), ꢁ122.5 ppm (t, 1F, 4JFF ꢀ7 Hz, F4) for betaine
33 and at dF ꢁ71.9 ppm (d, 2F, 3JFP ꢀ7 Hz, CF2), ꢁ100.7 ppm (d, 1F,
4JFP ꢀ14 Hz, F3) for betaine 34. In the 31P{1H}NMR spectrum of the
benzene solution the signals belonged to betaines 33 and 34 were
3
5
at
d
P 16.0 (dt, JPF ꢀ7, JPF ꢀ 1 Hz) and 14.0 ppm (dt, 4JPF ꢀ14, 3JPF
ꢀ7 Hz) respectively. The 19F and 31P{1H} NMR spectra of solution
after 24 h without isolation from moisture in the air displayed only
the presence of betaines 35, 36, 5 and compound 6 (ꢀ5%, 1%, 1% and
77% yields, respectively). Betaine 35 was isolated with 3% yield.
The structure of betaine 35 was proved by the XRD analysis (see
ESI2 Supporting Figure 4).
The amount of precipitate was ꢀ33% from the initial
compounds, which is less in comparison with the reaction of
fluoranil 4 in anhydrous C6H6. The 19F and 31P{1H} NMR spectra of
the precipitate solution in Me2SO displayed the presence of a small
amount of betaine 35 (ꢀ1% yield per initial quinone 32), 6 (ꢀ1%
yield per initial PPh3) and not identified products.
According to the 19F and 31P{1H} NMR spectra of benzene
solution and precipitate dissolved in Me2SO a total yields of 35, 36,
5 and 6 are 6%, 1%, 1% and 78% respectively. The above data testifies
that in the reaction with PPh3 quinone 32 undergoes triphenylpho-
sphanodefluorination and reduction in a ꢀ1:10 ratio.
In addition, the effect of medium polarity on competition of the
two submitted transformations are not in consistent with the
views of the authors [10] on a smaller division of charges of
opposite sign in the transition state of phosphanodefluorination
compared to the transition state of reduction.
2.2. Interaction of 2-X-trifluoro-1,4-benzoquinones (X = Cl, Me, OMe)
with PPh3 in anhydrous C6H6 and dioxane
The interaction of all indicated quinones with PPh3 gave a
solution and a precipitate, which, similar to those obtained from
the fluoranil 4, supposed to contain the products of reduction,
particularly in the form of adducts, with products of triphenylpho-
sphanodefluorination. A common feature of these reactions is
triphenylphosphanodefluorination at positions 5 and 6 in depend-
ing on the nature of the substituent X.
The interaction of 2-chloro-trifluoro-1,4-benzoquinone 32 with
PPh3 (1:1) in carefully dried C6H6 in an atmosphere of dry argon at
the room temperature gave a solution and a precipitate. According
to the NMR data solution contained analogs of betaine 8, the
The interaction of quinone 32 with PPh3 (1:1) in dried dioxane
in dry-box under dried argon gave a solution and a precipitate. The
ratio of isomeric betaines, which are determined by the attack of
PPh3 at 6, 5 and 2 positions, is (33 + 35):(34 + 36):(8 + 5) = 10:1:6
and also show a much higher activity of positions 6 and
2 compared to position 5 of quinone 32. In the reaction mixture
were present phosphorane 10 and initial quinone 32 (ꢀ63% and
16% yields, respectively) (Scheme 8). Quinone 32 with PPh3
undergoes triphenylphosphanodefluorination and reduction in a
(33 + 34 + 35 + 36 + 8 + 5):(10) = 1:2 ratio. Betaine 35 was isolat-
ed with 14% yield. In the NMR 19F spectrum betaine 36 displayed

S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
27
Scheme 8. Reactions of quinones 32 and 37 with PPh3.
one singlet signal at dF ꢁ117.1 ppm (F5), and in the 31P{1H} NMR
spectrum – singlet at dP 15.1. Also the signal was observed
belonging with a high probability to hydrogen fluoride (singlet at
dF ꢁ189.6 ppm).
quinone 37 in regard to attack of nucleophile, obviously, for the
reason similar to that discussed above for the quinone 32. The ratio
of triphenylphosphanodefluorination (38 + 39 + 40 + 41) and re-
duction (10) is ꢀ1:1. Also phosphorane 10 and initial quinone 37
were present (ꢀ40% and 8%, respectively) (Scheme 8).
The amount of precipitate in that reaction was ꢀ14% from the
initial compounds. The 19F and 31P{1H} NMR spectra of the
precipitate solution in Me2SO displayed the presence of a small
amount of 35 (ꢀ1% yield per initial quinone 32), 6 (ꢀ1% yield per
initial PPh3) and not identified products.
In the 19F NMR spectra the signal was observed belonging with
a high probability to hydrogen fluoride (singlet at dF ꢁ183.9 ppm).
In the NMR 19F spectrum betaines 38 and 39 displayed two
multiplets each with 2:1 intensity ratio at dF ꢁ74.6 ppm (br. s, 2F,
CF2), ꢁ130.7 ppm (br. s, 1F, F4) for betaine 38 and at dF ꢁ74.8 ppm
According to the 19F and 31P{1H} NMR spectra of dioxane
solution and precipitate dissolved in Me2SO a total yields of
betaines 35, 36 and 5are 21%, 2% and 11% respectively. The above
data testifies that in the reaction with PPh3 quinone 32
undergoes triphenylphosphanodefluorination and reduction in
a ꢀ1:2 ratio.
4
(br. s, 2F, CF2), ꢁ103.9 ppm (dm, 1F, JFP ꢀ15 Hz, F3) for betaine
39. In the 31P{1H} NMR spectrum of the dioxane solution the
signals at
d
P 14.8 (br. s) and 15.4 ppm (dm, 4JPF ꢀ15 Hz) belonged to
betaines 38 and 39 respectively. In the NMR data of the dioxane
solution betaine 41 displayed multiplet at dF ꢁ110.9 ppm (dq,
Product ratios of reaction quinone 4 with PPh3 suggests that the
replacement of the fluorine atom with a chlorine at the transition
from quinone 4 to quinone 32 appreciably discriminates the
position 5 in competition with position 6 in regard to attack of
nucleophile. The obvious reason for this is a weaker electron-donor
resonance effect of chlorine atom in comparison with the fluorine
atom, that makes 4-C55O group a stronger acceptor compared to 1-
C55O group. The presence of 10 and, correspondingly, isolation the
product of its hydrolysis – 6, indicate a significant contribution
the process of reduction of initial quinone in the total result of the
interaction.
The interaction of 2-methyl-trifluoro-1,4-benzoquinone 37
with PPh3 (1:1) in dried dioxane in dry-box under dried argon
gave a solution and a precipitate. According to NMR data the
solution contained betaines triphenyl(4,6,6-trifluoro-3-methyl-2-
oxido-5-oxocyclohexa-1,3-dien-1-yl)phosphanium 38 and triphe-
nyl(3,6,6-trifluoro-4-methyl-2-oxido-5-oxocyclohexa-1,3-dien-1-
yl)phosphanium 39 (2.0:1.0 respectively) and also, the products of
their hydrolysis – (4-fluoro-5-methyl-2-oxido-3,6-dioxocyclo-
hexa-1,4-dien-1-yl)triphenylphosphanium 40 and (5-fluoro-4-
methyl-2-oxido-3,6-dioxocyclohexa-1,4-dien-1-yl)triphenylpho-
sphanium 41 (21:1). The ratio (38 + 40):(39 + 41) = 13:1 indicate a
much higher activity of position 2 compared to position 3 of
4JFP = 16.0 Hz, 4JFH = 3.1 Hz, F5), and multiplet at
dP 15.4 ppm (dm,
4JPF = 16.0 Hz) (NMR data of 40 see Supporting Table 1).
The 19F and 31P{1H} NMR spectra of solution after 24 h without
isolation from moisture in the air displayed only the presence of
betaines 40, 41 and 6 (ꢀ43%, 3% and 40%, respectively). After
chromatography of solution on silica gel by a mixture of acetone –
hexane (1:1) and then after second chromatography in ethyl
acetate had been isolated betaine 40 and [4-fluoro-3-hydroxy-5-
methyl-2-oxido-6-oxo-3-(2-oxopropyl)cyclohexa-1,4-dien-1-
yl]triphenylphosphanium 42 with ꢀ9% yield each. Apparently,
betaine 42 is formed from 40 as a result of the addition one
molecule of acetone. This is confirmed by the fact that betaine 40
(5% yield) was only obtained after chromatography of solution on
silica gel by chloroform. Thus, the total yield of betaine 40 was 14%.
The structure of betaines 40 and 42 was proved by the XRD analysis
(see ESI2 Supporting Figure 5).
The amount of precipitate in that reaction was ꢀ24% from the
initial compounds. The NMR data of the precipitate solution in
Me2SO displayed the presence of a small amount of betaine 40
(ꢀ4% yield per initial quinone 37) and 6 (ꢀ7% yield per initial PPh3).
According to the 19F and 31P{1H} NMR spectra of dioxane solution
and precipitate dissolved in Me2SO a total yields of betaines 40, 41
and 6 are 47%, 3% and 47% respectively. The data testifies that

28
S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
Scheme 10. Reaction of 28 with PPh3 and following treatment of the benzene
solution with aniline 15.
The interaction of quinone 28 with PPh3 (1:1) in dried dioxane
in dry-box under dried argon gave a solution and a precipitate.
According to NMR data the solution contained betaines 43 and
44 (2:1) and also, the products of their hydrolysis – betaines 45
and 29 (4:1) (Scheme 10). The ratio (43 + 45):(44 + 29) is 3:1.
In the 19F NMR spectra the signal was observed belonging with
Scheme 9. Reactions of 28 with PPh3 in C6H6 and dioxane.
a
high probability to hydrogen fluoride (singlet at dF
quinone 37 with PPh3 undergoes triphenylphosphanodefluorina-
tion and reduction in a ꢀ1:1 ratio.
ꢁ187.6 ppm) [14]. The ratio of triphenylphosphanodefluorina-
tion (29 + 45 + 43 + 44) and reduction (10) of 28 is 3:1.
The NMR data of solution after 24 h without isolation from
moisture in the air displayed only the presence of betaines 45, 29
and oxide 6 (ꢀ50%, 16% and 27%, respectively). The attempts to
isolate individual betaines 45 and 29 by TLC failed, but after
addition to a reaction mixture of an excess of aniline 15 were
obtained betaine 47 and other not identified products.
The amount of precipitate in that reaction was ꢀ18% from the
initial compounds. The NMR data of the precipitate solution in
Me2SO displayed the presence of a small amount 6 (ꢀ3% yield per
initial PPh3) and not identified products.
According to the NMR data of dioxane solution and precipitate
dissolved in Me2SO total yields of betaines 45, 29 and 6 are 50%,
16% and 30% respectively. The above data testifies that quinone 28
with PPh3 undergoes triphenylphosphanodefluorination and
reduction in a ꢀ2:1 ratio.
The interaction of 2-methoxy-trifluoro-1,4-benzoquinone 28
with PPh3 (1:1) in dried C6H6 in dry-box under dried argon also led
to a precipitate formation. According to NMR data the solution
contained triphenyl(3,6,6-trifluoro-4-methoxy-2-oxido-5-oxocy-
clohexa-1,3-dien-1-yl)phosphanium 43 and triphenyl(4,6,6-tri-
fluoro-3-methoxy-2-oxido-5-oxocyclohexa-1,3-dien-1-yl)pho-
sphanium 44 (4.0:1.0) and also, the products of their hydrolysis –
(5-fluoro-4-methoxy-2-oxido-3,6-dioxocyclohexa-1,4-dien-1-
yl)triphenylphosphanium 45 and 29 (17:1) (Scheme 9).
In the NMR 19F spectrum betaines 43 and 44 displayed two
multiplets each with 2:1 intensity ratio at dF ꢁ74.5 ppm (dd, 2F,
3JFP ꢀ7, 5JFF ꢀ3 Hz, CF2), ꢁ125.7 ppm (dm, 1F, 4JFP ꢀ14, 5JFH ꢀ4, 5JFF
4
ꢀ3 Hz, F3) for betaine 43 and at dF ꢁ74.7 ppm (dd, 2F, JFF
,
3JFP
4
ꢀ7 Hz, CF2), ꢁ159.1 ppm (m, 1F, JFF ꢀ7 Hz; F4) for betaine 44. In
the 31P{1H} NMR spectrum of the benzene solution the signals at dP
15.8 (dt, 4JPF ꢀ14, 3JPF ꢀ7 Hz) and 15.7 ppm (t, 3JPF ꢀ7 Hz) belonged
to betaines 43 and 44 respectively. In the NMR 19F spectrum of the
C6H6 solution betaine 45 displayed multiplet at dF ꢁ132.9 ppm (dq,
4JFP = 14.0, 5JFH = 2.4 Hz, F5), and in the 31P{1H} NMR spectrum – the
2.3. The NMR spectra and structures of betaines
NMR spectral characteristics of the synthesized compounds in
this work are presented in Supporting Table 1 and Table 2 and fully
meet their structures. Bis-betaine 22 and tris-betaine 25 were
synthesized previously by other methods [15], and their 13C{1H}
and 31P{1H} NMR data in the cited paper, fully correspond to those
samples produced by us. The structure of betaines 5, 16, 17, 20–22,
25, 29, 35, 40, 42, 46, 47 were solved by XRD analysis.
It is of interest to analyze the NMR data with the aim to shed a
light on the structure of betaines 5, 16, 17, 20–22, 25, 29, 35, 40, 42,
46, 47 in the context of canonical resonance structures 2A–2D
(R1–3 = Ph). Previously the authors [15] made a conclusion about
the prevalence of quinone-betaine resonance structure 2C for
22. This conclusion was based on the fact, that in the NMR 13C{1H}
spectrum of bis-betaine 22 the ‘‘carbonyl’’ atoms C3,6 have
downfield shifts to the signals of ‘‘enolate’’ atoms C2,4. However,
the assignment of signals does not seem to be a definite. Thus, a
4
signal at dP 14.5 ppm (d, JPF = 14.0 Hz) (NMR data for betaine 29
see Supporting Table 2).
The ratio (43 + 45):(44 + 29) = 4:1 and (29 + 43 + 44 +
45):(10) = 4:1 differs significantly from mentioned above for
quinones 4 and 37 and indicates in this case on a considerable
predominance of phosphanodefluorination over the reduction.
The probable reason for this change in the ratio of competing
paths is the electron-donor effect of the methoxy group. The
replacement of the fluorine atom with a methoxy group at the
transition from quinone 4 to quinone 28, appreciably reduces
the tendency of the quinone to reduction but to a lesser extent
discriminates the attack of nucleophile, at least to position 3, that
conjugate with the most acceptor from two carbonyl groups of the
quinone 28.
After the addition of an excess of aniline 15 to a reaction
mixture were obtained new compounds – [4-methoxy-2-oxido-
5-oxo-3-(phenylamino)-6-(phenylimino)cyclohexa-1,3-dien-
1-yl]triphenylphosphanium 46 and [4-methoxy-2-oxido-3,6-
dioxo-5-(phenylamino)cyclohexa-1,4-dien-1-yl]triphenylphospha-
nium 47 (ꢀ7:1) (Scheme 10). Betaines 46 and 47 were isolated by
TLC with 43% and 7% yields respectively and characterized. The
structures of betaines 46 and 47 were established by XRD analysis
(see ESI2 Supporting Figure 6).
signal at dC 186.9 ppm was qualified as a triplet with a JCP = 5.3 Hz
coupling constant and by combination of these characteristics was
assigned to C6. But, in our case in the NMR 13C{1H} spectrum bis-
2
4
betaine 22 displayed a triplet signal with the similar JCP ꢀ JCP
5.1 Hz coupling constants, and on this basis shall be assigned to
C2,4. In work [15] a triplet signal at
dC 184.4 ppm with JCP = 14.5 Hz
coupling constant and a singlet signal at 175.2 ppm were assigned
to C3 and C2,4, respectively. But, in our case in the NMR 13C{1H}

S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
29
We have also studied the effect of solvents (C6H6, Et2O, THF,
dioxane, MeOH, aq. dioxane and Me2SO) on the competition of
these transformations. It is shown that the use of more polar
solvents, such as MeOH, aq. dioxane and Me2SO, leads to an
increase in products of phosphanodefluorination. The entry of
solvent molecule into products of phosphanodefluorination of
fluoranil was observed in MeOH.
The possibility of further nucleophilic modifications was
demonstrated on the primary triphenylphosphanodefluorination
products in the reactions with aniline and 4-phenoxyaniline to give
highly functionalized benzoquinone derivatives.
Scheme 11. The structures of ylides 48–51.
4. Experimental
spectrum of bis-betaine 22 a triplet signals at dC 184.3 and
2
3
175.1 ppm with JCP = 14.3 and JCP = 1.6 Hz coupling constants
were assigned to C6 and C3, respectively. Downfield location of
signals at dC 186.9 and 184.3 ppm may be due to a significant
contribution of ortho-quinoid resonance structure 2D, the assign-
ment of the latter to C6 based on the high value of coupling
constant 2JCP 14.3 Hz (cf. 2JCP 12.7 Hz for C6 in case of betaine 5). In
The NMR spectra were recorded with a Bruker AV 300 (1H:
300.13 MHz, 13C{1H}: 75.47 MHz, 19F: 282.36 MHz, 31P{1H}:
121.49 MHz)
and
AV-400
(1H:
400.13 MHz,
13C{1H}:
100.61 MHz) spectrometers in the respective deuterated solvents
relative to the residual proton chemical shifts of acetone (dH
2.07 ppm,
and Me2SO-d6 (
NMR spectra, external C6F6 (
and H3PO4 in 31P{1H} spectra. High-resolution mass spectra
(HRMS) were measured with a DFS Thermo scientific instrument
(EI, 70 eV). The melting points were determined on an FP
900 Thermosystem microscope melting point apparatus (Met-
tler-Toledo International Inc., Zu¨rich, Switzerland).
dC 29.80 ppm), chloroform (dH 7.25 ppm, dC 77.00 ppm)
the 31P{1H} NMR spectrum there is a singlet signal at
d
P 13.4 ppm
d
H 2.50 ppm) in 1H NMR spectra, Me4Si in 13C{1H}
(cf. dP 13.8 ppm in [15]).
d
F = ꢁ162.9 ppm) in 19F NMR spectra,
The structure of betaine 25 was justified by the 13C{1H} and
31P{1H} NMR data that is in line with data reported in [15]. Thus, a
singlet signal at dC 184.1 ppm (cf. dC 184.4 ppm in [15]) was
assigned to C2,4,6. A signal at
d
C 74.4 ppm, dm, 1JCP 118.0 Hz (cf. at dP
1
4
74.4 ppm, dt, JCP 116.0 and JCP 9.9 Hz in [15]) was assigned to
C1,3,5. In the 31P{1H} NMR spectrum there is a singlet signal at dP
13.4 ppm (cf. dP 13.7 ppm in [15]).
XRD data were obtained on a Bruker Kappa Apex II CCD
diffractometer using
w, v scans of narrow (0.58) frames with Mo Ka
˚
In this regard, to determine the electronic structure of the
synthesized compounds in terms of resonance 2! $ 2B $ 2C, 2D
seems more rational to consider the NMR characteristics of the
fragments C–P. For ylides Alk3P+–CꢁHR (Alk = Me, Et; R = H, Me)
radiation ( = 0.71073 A) and a graphite monochromator. The
l
structures were solved by direct methods and refined by full-
matrix least-squares method against all F2 in anisotropic
approximation using the SHELX-97 programs set [23]. The H
atoms positions were calculated with the riding model. Absorption
corrections were applied empirically using SADABS programs
[24]. Compound 5 crystallizes with a solvating ½ C6H6 per unit. The
structures of 17, 35, 40 and 47 are formed by two crystallographi-
cally independent molecules, one of which is shown on Supporting
Figures 2, 4, 5 and 6 respectively. The structure of 35 was refined as
a 0.68:0.32(1) racemic twin. In the structure 47 one of phenyl ring
is disordered over two positions with occupancy ratio of
0.528:0.472(6).
the signals are located in the range
but with decreasing of -delocalization of the negative charge on
the ylide C-atom, the signals shifts downfield (at C 53.3 for 48 and
70.9 ppm for enol 49 [22]). The chemical shifts of the ylide C-atom
approaches the values at C 78.3 ppm for 50 and C 117–119 ppm
d
C from ꢁ14.0 to ꢁ2.0 ppm [21],
p
d
d
d
range for ipso-C-atom of phenyl ring of triphenylphosphanium
cation Ph3P+CH2X (X = H, Me, Ph, OMe, Cl, etc.) [22] (Scheme 11).
The chemical shifts of the C–P bond associated with triphe-
nylphosphanium group are in the range dC from 74.2 to 84.0 ppm
in the series of isolated compounds (betaines 5, 16, 17, 20–22, 25,
29, 35, 40, 42, 46, 47). That allows you to believe that their
electronic structure is characterized by a predominant contribu-
tion of betaine resonance structures such as 2C and 2D.
That conclusion is in apparent contradiction with the location in
the significantly strong field of analogous signals of structurally
CCDC 1406288 (for 5), 1406289 (for 16), 1406290 (for 17),
1406291 (for 21), 1406292 (for 29), 1406293 (for 35), 1406294 (for
40), 1406295 (for 42), 1406296 (for 46), and 1406297 (for 47)
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
similar compounds 51 (at dC 29–33 ppm [22]). But can be rationally
explained by the fact that in this case the electron-donor effect of
alkoxy-group reduces the contribution of betaine structure 51A in
favor of structure 51B (Scheme 11).
The obtained crystal structures were analyzed for short
contacts between non-bonded atoms using the PLATON program
[25].
This conclusion is consistent with the change of values of
coupling constant JCP in the series of compounds, which
characterized by a gradual decrease in the negative charge on the
‘‘ylide’’ carbon atom: 48 – 128.7 Hz, 50 – 113.1 Hz [22], 5, 16, 17, 20–
22, 25, 29, 35, 40, 42, 46, 47 – 103.4–118.0 Hz, 49 – 99.2 Hz [22].
Fluoranil 4 was crystallized from CH2Cl2, 2-chloro-trifluoro-1,4-
benzoquinone 32 and 2-methyl-trifluoro-1,4-benzoquinone 37
was crystallized from CCl4. 2-Methoxy-trifluoro-1,4-benzoqui-
none 28 was prepared according to [17]. PPh3 was crystallized
from Et2O. Aniline 15 and solvents were dried over CaH2 and
purified by high-vacuum distillation (0.09 kPa). 4-Phenoxyaniline
19 was crystallized from CH2Cl2-hexane (1:2).
1
3. Conclusions
4.1.1. (4,5-Difluoro-2-oxido-3,6-dioxocyclohexa-1,4-dien-1-
The reactions of fluoranil 4 and its polyfluorinated analogs – 2-
X-trifluoro-1,4-benzoquinones (X = Cl, Me, OMe) with PPh3 were
studied and, unlike the mentioned above for chloranil [8], not only
reduction, but also triphenylphosphanodefluorination were found
to occur.
yl)triphenylphosphanium 5
4.1.1.1. Method A
PPh3 (0.728 g, 2.777 mmol) in C6H6 (3 mL) was added slowly to
a stirred solution of fluoranil 4 (0.500 g, 2.777 mmol) in C6H6

30
S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
(8 mL) at room temperature (Scheme 1). A green precipitate
immediately separated. After 1 h the mixture was treated with
water (3 mL), stirred for 4 h and was allowed to stand overnight.
The mixture was centrifuged off from precipitate. A residue was
treated with C6H6 (16 mL) and CH2Cl2 (20 mL), and was filtered
from 0.675 g of insoluble material. The combined C6H6 and CH2Cl2
solutions afforded after double recrystallization betaine 5 (0.224 g,
19%) from C6H6 as bright yellow crystals. Crystals suitable for XRD
analysis were grown from C6H6.
and then acetone–hexane, 1:2, Rf = 0.2, 2 times) to yield betaine 17
with admixture 50% 6. After double recrystallization from
methylene chloride/diethyl ether (1:8), betaine 17 was obtained
as red oil (0.015 g, 27%). Crystals suitable for XRD analysis were
grown from CHCl3/hexane (1:20).
4.1.5. Reactions of 4 with PPh3 in anhydrous Et2O, THF and dioxane
PPh3 (0.029 g, 0. 111 mmol) in anhydrous solvent (0.4–1.0 mL)
was added slowly to a stirred solution of fluoranil 4 (0.020 g, 0.
111 mmol) in anhydrous solvent (1.0–2.0 mL) at room tempera-
ture under dried argon. A precipitate immediately separated. After
30 min the mixture was centrifuged off from precipitate and the
NMR spectra of solution were recorded under dried argon. A
precipitate was dissolved in Me2SO and the NMR spectra of
solution were recorded under dried argon with C6F6 as internal
standard.
4.1.1.2. Method B
PPh3 (0.437 g, 1.666 mmol) in dioxane (10 mL) was added
slowly to a stirred solution of fluoranil 4 (0.300 g, 1.666 mmol) in
dioxane (10 mL) and water (1 mL) at room temperature. After 48 h,
a
precipitate was centrifuged off, dried on air and after
recrystallization betaine 22 was obtained from C6H6 as bright
orange crystals (0.099 g, 9%). Dioxane solution was distilled off, the
residue afforded after double recrystallization from C6H6 betaine 5
(0.171 g, 24%) as bright yellow crystals.
4.1.6. {4-Fluoro-2-oxido-5-oxo-3-[(4-phenoxyphenyl)amino]-6-
(phenylimino)cyclohexa-1,3-dien-1-yl}triphenylphosphanium 20 and
{4-fluoro-2-oxido-3,6-dioxo-5-[(4-phenoxyphenyl)amino]cyclohexa-
1,4-dien-1-yl}triphenylphosphanium 21
4.1.2. Reaction between quinone 4 and PPh3 in anhydrous C6H6 and
fixing the formation of betaine 8
PPh3 (0.437 g, 1.666 mmol) in anhydrous C6H6 (3 mL) was
PPh3 (0.728 g, 2.777 mmol) in anhydrous dioxane (1.0 mL) was
added slowly to
a
stirred solution of fluoranil
4
(0.300 g,
added slowly to a stirred solution of fluoranil 4 (0.500 g,
1.666 mmol) in anhydrous C6H6 (5 mL) at room temperature
under dried argon. A green precipitate immediately separated.
After 30 min, the mixture was centrifuged off and the NMR spectra
of green solution (0.329 g) were recorded under dried argon (see
Scheme 1 see ESI2 Supporting Chart 1). A green precipitate
(0.408 g) was dissolved in Me2SO and the NMR spectra of solution
were recorded under dried argon with C6F6 (0.022 g, 0.118 mmol)
as internal standard.
2.777 mmol) in anhydrous dioxane (2.0 mL) at room temperature
in dry-box under dried argon. A brown precipitate immediately
separated. After 1 h the mixture was centrifuged off from
precipitate and the NMR spectra of solution were recorded under
dried argon (Scheme 3). Aniline 15 (0.056 g, 0.600 mmol) in
anhydrous dioxane (0.3 mL) was added slowly to dioxane solution
under dried argon. The resulting solution was stirred for 1 h and
then 4-phenoxyaniline 19 (0.500 g, 2.700 mmol) in anhydrous
dioxane (5 mL) was quickly added. After 1 h the NMR spectra of
solution were recorded under dried argon. The solvent was
distilled off, the residue was separated by TLC (Sorbfil, ethyl
acetate, Rf = 0.8–1.0, 1 time and then methylene chloride–hexane,
1:1, 1 time) to yield 21 (Rf = 0.4, with admixture 10% 6) and betaine
20 (Rf = 0.9).
4.1.3. [4-Fluoro-2-oxido-5-oxo-3-(phenylamino)-6-
(phenylimino)cyclohexa-1,3-dien-1-yl]triphenylphosphanium 16
PPh3 (0.029 g, 0. 111 mmol) in anhydrous C6H6 (0.4 mL) was
added slowly to a stirred solution of fluoranil 4 (0.020 g, 0.
111 mmol) in anhydrous C6H6 (0.4 mL) at room temperature under
dried argon. A green precipitate immediately separated. After 1 h,
the mixture was centrifuged off from precipitate. To benzene
solution was slowly added 0.6 equivalent of aniline 15 (0.006 g,
0.067 mmol) in anhydrous C6H6 (0.5 mL) under dried argon. After
1 h, the NMR spectra of mixture were recorded under dried argon
(Scheme 2). The solvent was distilled off, the residue was purified
by TLC (Sorbfil, diethyl ether, Rf = 0.4–1.0, 1 time and then
chloroform–hexane, 6:1, Rf = 0.5, 4 times) to yield betaine 16
(0.018 g, 29%) as red crystals. Crystals suitable for XRD analysis
were grown from methylene chloride/diethyl ether/hexane
(1:10:4).
Betaine 20 was obtained as red oil (0.336 g, 18%).
Betaine 21 was obtained after reprecipitation fraction (Rf = 0.4)
from chloroform/diethyl ether (1:4), as red oil (0.417 g, 26%). Red
crystals suitable for XRD analysis were grown from acetone/
hexane (1:3).
4.1.7. [2,4-Dioxido-3,6-dioxo-5-
(triphenylphosphaniumyl)cyclohexa-1,4-dien-1-
yl]triphenylphosphanium 22
4.1.7.1. Method A
PPh3 (0.146 g, 0.555 mmol) in dioxane (1.0 mL) was added
slowly to a stirred solution of fluoranil 4 (0.050 g, 0.277 mmol) in
dioxane (1.0 mL) and H2O (0.5 mL) at room temperature (Scheme
4). After 30 min the solution of PPh3 (0.073 g, 0.277 mmol) in
dioxane (1.0 mL) was added slowly and stirred for 24 h (Scheme 4).
Water (3.0 mL) was added, a precipitate was centrifuged off,
washed with water (2.0 mL), dried on air and purified by TLC
(Whatman, chloroform, Rf = 0.1, 5 times and then acetone, Rf = 0.1,
5 times). After double TLC under the same conditions and
recrystallization from CHCl3/hexane (1:4) betaine 22 was obtained
as a complex with one molecule of CHCl3, bright orange crystals
(0.098 g, 53%).
4.1.4. [4-Fluoro-2-oxido-3,6-dioxo-5-(phenylamino)cyclohexa-1,4-
dien-1-yl]triphenyl-phosphanium 17
PPh3 (0.029 g, 0. 111 mmol) in anhydrous C6H6 (0.4 mL) was
added slowly to a stirred solution of fluoranil 4 (0.020 g, 0.
111 mmol) in anhydrous C6H6 (0.4 mL) at room temperature under
dried argon. A green precipitate immediately separated. After 1 h
the mixture was centrifuged off from precipitate and the NMR
spectra of solution were recorded under dried argon (Scheme 2). To
benzene solution was quickly added 2.0 equivalent of aniline 15
(0.021 g, 0.222 mmol) in anhydrous C6H6 (0.6 mL) under dried
argon. The resulting solution was stirred for 1 h and the NMR
spectra were recorded under dried argon. The solvent was distilled
off, the residue was purified by TLC (Sorbfil, CH2Cl2, Rf = 0.1, 1 time
4.1.7.2. Method B
PPh3 (0.078 g, 0.298 mmol) in dioxane (1.0 mL) was added
slowly to a stirred solution of betaine 5 (0.050 g, 0.119 mmol) in

S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
31
dioxane (2.0 mL) at room temperature. A mixture was stirred at
room temperature for 10 d. Water (0.2 mL) was added and the
mixture was stirred for another 48 h (Scheme 4). The mixture was
extracted with chloroform. The solvent was distilled off, the
residue was purified by TLC (Whatman, acetone, Rf = 0.1, 4 times).
After double TLC under the same conditions betaine 22 was
obtained as a complex with one molecule of CHCl3, bright orange
crystals (0.040 g, 51%).
1.527 mmol) in anhydrous C6H6 (3.0 mL) at room temperature
under dried argon. A brown precipitate immediately separated.
After 30 min the mixture was centrifuged off from precipitate and
the NMR spectra of solution were recorded under dried argon
(Scheme 8). After 48 h the NMR spectra of solution were recorded
over again under dried argon. The solvent was distilled off, a
residue was purified by TLC (Sorbfil, chloroform, Rf = 0.3, 2 times)
to yield betaine 35 as orange oil, (0.021 g, 3%).
A brown precipitate (0.228 g) was dissolved in Me2SO and the
NMR spectra of solution were recorded under dried argon with
C6F6 (0.027 g, 0.145 mmol) as internal standard.
4.1.8. Reaction between 4 and Me2SO
A solution of quinone 4 (0.010 g, 0.056 mmol) in Me2SO
(0.5 mL) was prepared and then was keep at room temperature
while periodically recording NMR spectra (Scheme 5).
4.1.14.2. Method B
PPh3 (0.667 g, 2.544 mmol) in anhydrous dioxane (1.0 mL) was
added slowly to a stirred solution of quinone 32 (0.500 g,
2.544 mmol) in anhydrous dioxane (1.5 mL) at room temperature
in dry-box under dried argon. A yellow precipitate immediately
separated. After 1 h, the mixture was centrifuged off from
precipitate and the NMR spectra of solution were recorded under
dried argon (Scheme 8). After 96 h the NMR spectra of solution
were recorded over again under dried argon. The solvent was
distilled off, the residue was purified by TLC (Sorbfil, chloroform,
Rf = 0.3, 2 times) to yield betaine 35 as orange oil, (1.240 g, 14%).
Crystals suitable for XRD analysis were grown from acetone/
hexane (1:5).
4.1.9. Triphenyl[2,4,6-trioxido-3,5-
bis(triphenylphosphaniumyl)phenyl]phosphanium 25
A mixture of fluoranil 4 (0.050 g, 0.277 mmol), PPh3 (0.437 g,
1.666 mmol) and Me2SO (5.0 mL) was stirred at room temperature
under dried argon for 12 d. Water (0.4 mL) was added and the
mixture was stirred for another 48 h (Scheme 5). Water (20.0 mL)
was added, a precipitate was centrifuged off, washed with water
(20.0 mL), dried on air and purified by TLC (Whatman, chloroform–
hexane, 1:2, Rf = 0.8–1.0, 2 times and then diethyl ether, Rf = 0.1–
0.2, 3 times). Betaine 25 was obtained as a complex with one
molecule of CHCl3, orange crystals (0.053 g, 21%).
A yellow precipitate (0.163 g) was dissolved in Me2SO and the
NMR spectra of solution were recorded under dried argon with
C6F6 (0.022 g, 0.118 mmol) as internal standard.
4.1.10. Reaction of 4 with PPh3 in Me2SO
4.1.15. (4-Fluoro-5-methyl-2-oxido-3,6-dioxocyclohexa-1,4-dien-1-
yl)triphenylphosphanium 40 and [4-fluoro-3-hydroxy-5-methyl-2-
oxido-6-oxo-3-(2-oxopropyl)cyclohexa-1,4-dien-1-
yl]triphenylphosphanium 42
PPh3 (0.029 g, 0.111 mmol) in Me2SO (0.36 mL) was added
slowly to a stirred solution of fluoranil 4 (0.020 g, 0.111 mmol) in
Me2SO (0.32 mL) at room temperature under dried argon and
stirred for 1 h. Water (30.0 mL) was added, a precipitate was
centrifuged off, washed with water (10.0 mL) and dried on air. The
NMR spectra of precipitate were recorded in CHCl3 (Scheme 5).
PPh3 (0.596 g, 2.271 mmol) in anhydrous dioxane (1.0 mL) was
added slowly to a stirred solution of quinone 37 (0.400 g,
2.271 mmol) in anhydrous dioxane (1.5 mL) at room temperature
in dry-box under dried argon. A black precipitate immediately
separated. After 1 h, the mixture was centrifuged off from
precipitate and the NMR spectra of solution were recorded under
dried argon (Scheme 8). After 24 h the NMR spectra of solution
were recorded over again under dried argon. The solvent was
distilled off, the first part of the residue was purified by TLC (Sorbfil,
acetone–hexane, 1:1, Rf = 0.5, 1 time) to yield a mixture of betaines
40 and 42 in (1:1) ratio. The mixture was separated by TLC (Sorbfil,
ethyl acetate, 1 time) to yield:
Betaine 40 (Rf = 0.8, 0.087 g, 9%), orange oil. Orange crystals
suitable for XRD analysis were grown from acetone/hexane (1:4).
Betaine 42 (Rf = 0.6, 0.099 g, 9%), yellow oil. Yellow crystals
suitable for XRD analysis were grown from acetone/hexane (1:4).
The second part of the residue was purified by double TLC
(Sorbfil, chloroform, Rf = 0.1, 1 time) to yield an additional amount of
betaine 40 (0.047 g, 5%), an overall yield of 40 being (0.134 g, 14%).
A black precipitate (0.239 g) was dissolved in Me2SO and the
NMR spectra of solution were recorded under dried argon with
C6F6 (0.028 g, 0.150 mmol) as internal standard.
4.1.11. Reaction between 4 and MeOH
A solutions of quinone 4 with different concentrations (0.12–
1.04 mol/l) in MeOH were prepared and then were keep at room
temperature while periodically recording NMR spectra (Scheme 6).
4.1.12. Reaction of 4 with PPh3 in MeOH
PPh3 (0.029 g, 0.111 mmol) in MeOH (1.0 mL) was quickly
added to a stirred solution of fluoranil 4 (0.020 g, 0.111 mmol) in
MeOH (0.32 mL) at room temperature. After 1 h the NMR spectra of
solution were recorded (Scheme 6).
4.1.13. (4-Fluoro-5-methoxy-2-oxido-3,6-dioxocyclohexa-1,4-dien-
1-yl)triphenylphosphanium 29
PPh3 (0.073 g, 0.278 mmol) in MeOH (3.2 mL) was quickly
added to a stirred solution of fluoranil 4 (0.050 g, 0.278 mmol) in
methanol (0.8 mL) at room temperature (Scheme 6). After 72 h, a
precipitate was centrifuged off, dried on air and betaine 29 was
obtained as bright orange crystals (0.059 g, 49%). Crystals suitable
for XRD analysis were grown from CHCl3.
4.1.16. [4-Methoxy-2-oxido-5-oxo-3-(phenylamino)-6-
(phenylimino)cyclohexa-1,3-dien-1-yl]triphenylphosphanium 46 and
[4-methoxy-2-oxido-3,6-dioxo-5-(phenylamino)cyclohexa-1,4-dien-
1-yl]triphenylphosphanium 47
4.1.14. (5-Chloro-4-fluoro-2-oxido-3,6-dioxocyclohexa-1,4-dien-1-
yl)triphenylphosphanium 35
PPh3 (0.375 g, 1.430 mmol) in anhydrous C6H6 (1.0 mL) was
added slowly to a stirred solution of quinone 28 (0.275 g,
1.430 mmol) in anhydrous C6H6 (4.0 mL) at room temperature
in dry-box under dried argon. A black precipitate immediately
4.1.14.1. Method A
PPh3 (0.400 g, 1.527 mmol) in anhydrous C6H6 (1.0 mL) was
added slowly to a stirred solution of quinone 32 (0.300 g,

32
S.I. Zhivetyeva et al. / Journal of Fluorine Chemistry 180 (2015) 21–32
separated. After 1 h, the mixture was centrifuged off from
precipitate and the NMR spectra of solution were recorded under
dried argon (Scheme 10). To benzene solution was quickly added
3.0 equivalent of aniline 15 (0.400 g, 4.290 mmol) in anhydrous
C6H6 (1.0 mL) under dried argon. The resulting solution was stirred
for 1 h and the NMR spectra were recorded under dried argon. The
solvent was distilled off, the residue was separated by TLC (Sorbfil,
CHCl3, 3 times) to yield:
Betaine 46 (Rf = 0.4, 0.354 g, 43%), as red oil. Crystals suitable for
XRD analysis were grown from CHCl3/Et2O/hexane (1:2:1).
Betaine 47 (Rf = 0.1, with admixture of 10% 6). After double TLC
(Sorbfil, acetone–hexane, 2:1, Rf = 0.4) betaine 47 was obtained as
red oil, (0.052 g, 7%). Crystals suitable for XRD analysis were grown
from acetone/hexane (1:3).
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Acknowledgements
The authors wish to thank to Researcher of the Scientific Center
of chemical informatics and employees of the Center for collective
using (CCU) at the Institute of Organic Chemistry of Siberian
Branch of Russian Academy of Sciences.
This work was financially supported by the Russian Foundation
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Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.jfluchem.2015.
08.018.
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