Synthesis and transformations of triphenylpropargylphosphonium bromide

Article abstract of DOI:10.1134/S1070363208060133

A method of the synthesis of triphenylpropargylphosphonium bromide is developed. Its isomerization and hydration in various solvents are studied, and reactions with secondary amines, triethylamine, and triphenylphosphine are carried out. It is established that secondary amines add to the intermediate allene isomer with subsequent migration of the formed double bond to the phosphorus atom. The reaction of triethylamine with triphenylpropargyl and triphenylethynyl bromides occurs similarly to alkaline hydrolysis involving attack of the amine on the phosphorus atom. Triphenylphosphine forms with triphenylpropargylphosphonium bromide a bis-salt with a terminal methylene group. Experimental evidence is obtained showing that for phosphoxazole derivatives to form from oximes derived from triphenyl(oxomethyl)phosphonium salts that latter should bear an aryl substituent at the keto group.

Full text of DOI:10.1134/S1070363208060133

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 6, pp. 1177–1183. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © G.B. Bagdasaryan, P.S. Pogosyan, G.A. Panosyan, M.G. Indzhikyan, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78,
No. 6, pp. 950–955.
Synthesis and Transformations
of Triphenylpropargylphosphonium Bromide
G. B. Bagdasaryana, P. S. Pogosyana, G. A. Panosyanb, and M. G. Indzhikyana
aInstitute of Organic Chemistry, National Academy of Sciences of Armenia,
ul. Z. Kanakertsi 167A, Erevan, 375091 Armenia
bMolecular Structure Research Center, National Academy of Sciences of Armenia, Erevan, Armenia
Received November 9, 2007
Abstract—A method of the synthesis of triphenylpropargylphosphonium bromide is developed. Its
isomerization and hydration in various solvents are studied, and reactions with secondary amines,
triethylamine, and triphenylphosphine are carried out. It is established that secondary amines add to the
intermediate allene isomer with subsequent migration of the formed double bond to the phosphorus atom. The
reaction of triethylamine with triphenylpropargyl and triphenylethynyl bromides occurs similarly to alkaline
hydrolysis involving attack of the amine on the phosphorus atom. Triphenylphosphine forms with
triphenylpropargylphosphonium bromide a bis-salt with a terminal methylene group. Experimental evidence is
obtained showing that for phosphoxazole derivatives to form from oximes derived from triphenyl-
(oxomethyl)phosphonium salts that latter should bear an aryl substituent at the keto group.
DOI: 10.1134/S1070363208060133
Reactions of unsaturated phosphonium salts with
nucleophilic reagents hold a special place among
transformations of organophosphorus compounds. A
great number of works have been devoted to reactions
of NH-, CH-, OH-, SH-, and PH-nucleophiles with
phosphonium salts containing α- and β-acetylene
(vinylacetylene) and α-allene (enallene) groups.
Schweitzer, Koff, and Murray [3] obtained decisive
evidence to show that the reaction of triphenylpro-
pargylphosphonium bromide with methanol involves
an allenic intermediate. The authors showed that the
reaction easily proceeds under reflux for 24 h to form
an adduct by the β,γ-unsaturated group. The latter
transforms into an α,β isomer upon addition of
catalytic quantities of a base. The reaction with
deuteromethanol leads to a β,γ isomer completely
deuterated into the α and β positions. However,
treatment of the β,γ isomer with deuteromethanol does
not lead to the above-mentioned deuterated product.
Hence, the authors fairly conclude that deuteration
occurs in the intermediately formed allenic salts.
In these reactions, triphenylethynylphosphonium
bromide and triphenylpropargylphosphonium bromide
and its tautomers prepared from phenylpropargyl
bromide: triphenylpropargyl-, triphenylpropadienyl-,
and triphenyl(prop-1-ynyll)phosphonium bromides,
were best studied.
The present work is devoted to the development of
a procedure for synthesis of triphenylpropargyl-
phosphonium bromide (I) and to the study of its
reaction with certain P- and N-nucleophiles.
Goffmann and Forster [1] examined reactions of
nucleophiles with propargylphosphonium salts. They
established that the latter give the same products as
their isomeric α-acetylenic salts. An essential
difference consists in the fact that in the first case the
reactions proceeds easier, since they involve, in the
authors’ opinion, the intermediate active allenic
intermediates. Thus, the propargyl group is equivalent
to prop-1-ynyl and, at the same time, reacts more
effectively, which makes application of propargyl salts
preferable.
Some authors [7–9] reported the synthesis of
triphenylpropargylphosphonium bromide (I) by
reacting the components in dioxane in the presence of
HBr. Conditions applied by different authors differed
only by the concentration of HBr which was probably
added to prevent prototropic isomerization, and by the
solvent for recrystallization. In all the cases, the
1177

1178
BAGDASARYAN et al.
postreaction mixture was heated at 100ºC for 5–10 min
and the salt was filtered off and recrystallized from
ethanol or isopropanol. The yields varied in the range
13–75 %. The melting points of the prepared salt
varied from work to work.
We failed to obtain salt I in a satisfactory yield by
any of these methods. In all the cases, the isomeric
allenic salt II and the hydration product, acetonyltri-
phenylphosphonium bromide (yields 23–45%) formed
along with salt I.
CH2
C
CH
(C6H5)3P + Br
aqueous HBr
+
+
+
(C6H5)3P CH2
C
CH + (C6H5)3P CH
C
CH2 + (C6H5)3P CH2
C
O
CH3
to, 5_10 min
_
Br
_
Br
_
Br
III
I
II
The yield of salt I in mixture with the allenic
isomer was no higher than did not exceed 16%. The
resulting data can be explained by transformations of
salt I during heating with HBr and recrystallization.
Actually, we managed to obtain a pure salt I in a yield
of 75% by performing the reaction at room tem-
perature and without subsequent recrystallization.
It is interesting that the reaction of salt I with HBr
mixed with ethanol under heating for 1 h gave (2-
bromoprop-2-enyl)triphenylphosphonium bromide (IV)
in a yield of 38%. Compound IV could be formed ex-
clusively by hydrobromination of the allenic isomer,
involving nucleophilic attack of the bromide ion on
the sp2-carbon atom.
aqueous HBr
to, C2H5OH
+
+
(C6H5)3P CH2
C
CH2
(C6H5)3P CH2
C
CH
_
Br
_
Br
Br
IV
I
Along with ¹H and ¹³C NMR, the structure of
mination to triphenyl(prop-1-ynyl)phosphonium bro-
compound IV was established by its dehydrobro-
mide (V) under the action of triethylamine.
(C2H5)3N
_
+
+
+
C
C
CH3 + (C2H5)3NH Br + (C6H5)3P
O
(C6H5)3P CH2
C
CH2
(C6H5)3P
_
_
Br
Br
Br
IV
V
Attempted preparation of salt I by the reaction of
the components in absolute ether at a room temperature
gave [2-(triphenylphosphonio)prop-2-enyl]triphenylphos-
phonium dibromide (VI) in a yield of 44%. The same
result was obtained when the reaction was carried out
in absolute benzene.
Apparently, the reaction scheme involves formation
of salt I followed by allene formation and triphenyl-
phosphine addition.
+
+
(C6H5)3P + Br
CH2
C
CH
(C6H5)3P CH2
C
CH
(C6H5)3P CH
C
CH2
_
_
Br
Br
I
II
_
(C6H5)3P
+
salt I or II
+
(C6H5)3P CH
C
CH2
(C6H5)3P CH2
C
CH2
_
Br
_
Br
_
+P(C6H5)3
Br +P(C6H5)3
VI
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SYNTHESIS AND TRANSFORMATIONS OF TRIPHENYLPROPARGYLPHOSPHONIUM
1179
As would be expected, compound VI was also
obtained by the reaction of salt I with triphenyl-
phosphine in acetonitrile. The different behavior of
triphenylphosphine toward propargyl bromide in the
presence and in the absence of HBr is most likely
explained by the prototropic isomerization of salts I
into the allenic isomer in the second case. The latter
reacts with triphenylphosphine by the nucleophilic
addition scheme.
We studied reactions of salt I with such N-
nucleophiles as diethylamine, piperidine, and
triethylamine. In the first two cases, addition products
were obtained according to the following scheme:
+
+
(C6H5)3P CH
C
CH2
(C6H5)3P CH2
C
CH + R2NH
_
_
Br
Br
II
I
R2NH
+
+
(C6H5)3P CH2
C
CH2
(C6H5)3P CH
C
CH3
_
_
Br
Br
NR2
NR2
R2 = (C2H5)2, (CH2)5.
In the reaction with diethylamine, the product of
addition across the triple bond and subsequent
prototropic isomerization was isolated. The reaction
with piperidine resulted in isolation of a 9 : 1 mixture
of a similar adduct and piperidine hydrobromide. The
reaction of salt I with triethylamine took an interesting
pathway leading to triphenylphosphine oxide and
triethylamine hydrobromide in yields of 70 and 84.5%,
respectively. These products are likely to be formed by
a scheme similar to that of alkaline hydrolysis of
phosphonium salts, that involves nucleophilic attack
on the phosphorus atom.
+
(C6H5)3P
CH2 C CH
CH2 CH2
_
(C6H5)3P CH2
C
CH + (C2H5)3N
_
Br
(C2H5)2N+
H
I
_
Br
: N(C2H5)3
+
(C6H5)3P + CH2 CH2 + (C2H5)3NH + CH2
C
CH
_
Br
+N(C2H5)2
H2O
(C6H5)3P
O + (C2H5)2NH HBr
(C2H5)3N
+ CH3
C
CH
(C2H5)3N
(C2H5)3N HBr + (C2H5)2NH
The same reaction pathway with triethylamine was
observed in going from salt I to triphenyl(phenyl-
ethynyl)phosphonium bromide.
Previously we established that unsaturated phos-
phonium salts undergo a facile prototropic isomeriza-
tion in various solvents. The isomerization involves
shifts of the multiple bond from the β,γ into α,β
position to phosphorus and back. In particular, it was
found phenylpropargyl bromide reacts with
triphenylphosphine in ether, benzene, or acetonitrile to
+
(C6H5)3_P
Br
C
C
Ph
(C6H5)3P O + (C2H5)3N HBr
form
triphenyl(3-phenylpropadienyl)phosphonium
We reported earlier [6] a similar reaction pathway
with the attack of amine on the phosphorus atom.
bromide. The same reaction in chloroform results in a
pure salt with a phenylpropargyl group. Regularities of
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1180
BAGDASARYAN et al.
1
interconversions of these isomeric phosphonium salts
were revealed [10]. Proceeding with this research, we
established that salt I on boiling in water gives a
mixture of acetonyl and prop-1-ynyl salts III and V, in
acetonitrile, a mixture of prop-1-ynyl and starting salts
V and I, and in chloroform, a mixture of prop-1-ynyl
and propadienyl salts V and II.
1720 (C=О ). H NMR spectrum (СDСl3), δ, ppm, (J,
2
4
Hz): 6.02 d (2Н, JPH 11.4, РСН2), 2.59 d (3Н, J 2.6,
СН3), 7.5–8.1 m (15 Н, С6Н5). 13С NMR spectrum
3
(СDСl3), δ, ppm, 32.78 d (СН3, JPС 6.5), 40.89 d
1
1
(СН2, JPС 58.4), 118.79 d (3Сipso, JPС 89.2), 130.24 d
(6С, 2JPС 13.0), 134.04 d (6С, 3JPС 10.7), 134.81 d (3С,
4JPС 3.0), 200.98 d (СО, JPС 6.8). 31Р NMR spectrum
2
(СDСl3), δ, ppm: 21.8. Found, %: Br 20.60.
С21Н20ВrОР. Calculated, %: Вr 20.05. mp 223–224°С.
The product gave no melting point depression in a
mixture with an authentic sample.
H2O
V + III
CH3CN
I
V + I
b. A mixture of 9.55 g of triphenylphosphine and
17.5 ml of dry 1,4-dioxane was stirred for 40 min at
room temperature, after which 5.8 g of 42% HBr was
added dropwise, and the mixture was stirred until
homogeneous (50 min). A solution of 4.34 g of
propargyl bromide in 5 ml of dioxane was added
dropwise to the resulting solution. At the next day the
precipitate that formed was filtered off, washed with
absolute ether and benzene, and dried under a vacuum
to obtain 10.5 g (75.6%) of triphenylpropargyl-phos-
phonium bromide, mp 168–169ºC. The IR, 1H, and 31P
NMR spectra were coincident with those of salt I
obtained in the previous experiment. Found, %: Br
20.8, C21H20BrP. Calculated, %: Br 20.99.
CHCl3
V + II
According to published data and our results
triphenylphosphonium salts containing an aroylmethyl
group undergo a facile heterocyclization under action
of 10 N alkali both at low and at room temperatures to
form phosphoxazole derivatives. We failed to carry out
a similar reaction with oxime derived from salt III:
The oxime was always recovered unchanged.
Apparently, for heterocyclization to occur an aryl-
substituted keto group is necessary.
EXPERIMENTAL
The NMR spectra are recorded on a Varian
Mercury 300 spectrometer at 300.08, 121.75 and 75.46
Alkaline hydrolysis of triphenylpropargyl-
phosphonium bromide (I). To a solution of 1.2 g of
salt I in 26 ml of water, 13.1 ml of 10% NaOH was
added, and the mixture was refluxed for 4 h. The
aquoeus layer was decanted. The precipitate was
washed with ether several times. The ethereal extracts
were reduced by distillation, and the residual substance
and the powder at the bottom of the flask were washed
with absolute acetone and dried to obtain 0.81 g
(97.1%) of triphenylphosphine oxide, mp 152–153ºC.
The product gave no melting point depression in a
mixture with an authentic sample.
1
31
13
MHz for H, P, and C and 2D-COSY, respectively,
at 303K. The chemical shifts were measured against
internal TMS (1H and 13C) and external
orthophosphoric acid (31P). The IR spectra were
recorded on UR-20 and Specord IR-75 instruments.
Reaction of triphenylphosphine with propargyl
bromide. a. A replica of the experiment in [7, 9] was
made. A mixture, 5.8 g (16.6%), of triphenylpropar-
gylphosphonium bromide (I) and propadienyltri-
phenylphosphonium bromide (II) and 16.7 g (45.5%)
of acetonyltriphenylphosphonium bromide (III) was
prepared from 24 g of triphenylphosphine, 45 ml of
dry 1,4-dioxane, 10 ml of 52% HBr, and 11.3 g pro-
pargyl bromide. Salt I. IR spectrum of salt I, ν, cm–1:
2100 (–C≡CН), 3140 (≡CН). 1H NMR spectrum
Reaction of triphenylpropargylphosphonium bro-
mide (I) with 42% HBr. Hydrobromic acid, 1.1 ml,
was added dropwise to 1.2 g of salt I in 10 ml of
ethanol, and the mixture was refluxed for 1 h. The
alcohol was removed by distillation. The residual
white precipitate was washed with several portions of
distilled water and then with ether, and dried to obtain
5.5 g of a mixture of (2-bromoprop-2-enyl)triphenyl-
phosphonium bromide (IV) and acetonyltriphenyl-
phosphonium bromide (III) in a 95 : 5. Salt IV. IR
4
4
(DMSO), δ, ppm, (J, Hz): 3.02 d.t (1Н, JPH 6.9, JНH
2
2.7, –C≡CН), 5.19 d.d (2Н, 2JPH 16.6, JНH 2.7, РСН2),
7.7–7.95 m (15Н, С6Н5). 31Р NMR spectrum (DMSO),
δ, ppm: 27.7. Salt II. IR spectrum, ν, cm-1: 1960
(СН=С=СН2). 1H NMR spectrum (DMSО), δ, ppm, (J,
Hz): 5.49 d.d (2Н, 4JPH 13.1, 4JНH 6.5, =СН2), 7.7–7.93
m (16Н, С6Н5 and Р+СН=). 31Р NMR spectrum
(DМSО), δ, ppm: 23.95. Salt III. IR spectrum, ν, cm–1:
1
spectrum, ν, cm–1: 1620 (С=СН2). H NMR spectrum
2
(DMSO), δ, ppm, (J, Hz): 5.49 d (2Н, JРH 15.5,
4
2
РСН2), 5.70 d.d (1Н, JРH 4.3, JНH 1.9, С=СН2), 6.26
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 6 2008

SYNTHESIS AND TRANSFORMATIONS OF TRIPHENYLPROPARGYLPHOSPHONIUM
1181
d.d (1Н, 4JРH 5.0, 2JНH 1.9, С=СН2), 7.65–7.98 m (15Н,
Reaction triphenylpropargylphosphonium bro-
mide (I) with triphenylphosphine. Dry acetonitrile,
10 ml, and 0.68 g of triphenylphosphine were added to
1 g of salt I. At the next day, the precipitate that
formed was filtered off, washed with several portions
of absolute ether, and dried to obtain 0.6 g (31.5%) of
salt VI, mp 275ºC. The product gave no melting point
depression in a mixture with an authentic sample. The
IR, 1H, 13C, and 31P spectra were coincident with those
of the sample obtained in the previous experiment.
С6Н5). 31Р NMR spectrum (DМSО), δ, ppm: 26.95.
Salt III. IR spectrum, ν, cm–1: 1720 (C=О). 1H NMR spec-
2
trum (DМSО), δ, ppm, (J, Hz): 6.03 d (2Н, JPH 12.2,
4
РСН2), 2.44 d (3Н, JPH 2.6, СН3), 7.5–8.1 m (15Н,
С6Н5). 31Р NMR spectrum (DМSО), δ, ppm: 25.32.
Reaction of (2-bromoprop-2-enyl)triphenylphos-
phonium bromide (IV) with triethylamine. To a
heterogeneous mixture of 0.5 g of salt IV and 8 ml of
dry acetonitrile, 0.11 g of triethylamine was added, and
the resulting mixture was refluxed for 1 h. After
removal of the solvent, the residue was washed with a
water–chloroform mixture. From the aquoeous layer,
0.15 g (82.4%) of triethylamine hydrobromide was
isolated, mp 245ºC. The product gave no melting point
depression in a mixture with an authentic sample
Found, %: Br 43.3. C6H16BrN. Calculated, %: Br 43.9.
From the chloroform layer, 0.2 g of a mixture (1H and
31P NMR spectra) of triphenyl(prop-1-ynyl)phos-
phonium bromide (V) and triphenylphosphine oxide
was isolated in a 1 : 1 ratio. Salt V. IR spectrum, ν,
Alkaline hydrolysis of bis-salt VI. To a solution of
1 g of salt VI in 22 ml of water, 11 ml of 10% NaOH
was added. The mixture was refluxed for 6 h with
stirring. The aqueous layer was decanted; the solid
residue was washed with several portions of ether and
dried under in a vacuum to obtain 0.35 g (46.0%) of
triphenylphosphine oxide, mp 152–153ºC. The product
gave no melting point depression in a mixture with an
authentic sample.
Reaction of triphenylpropargylphosphonium
bromide (I) with diethylamine. To 1.0 g of salt I in
11 ml of dry acetonitrile, 0.21 g of diethylamine was
added dropwise. The mixture was refluxed for 1.5 h.
At the next day, acetonitrile was removed under a
vacuum. The solid residue was washed in succession
with several portions of absolute ether, absolute
benzene, and absolute ether, and dried to obtain 0.9 g
(76.1%) of (2-diethylaminoprop-1-enyl)triphenyl phos-
phonium bromide, mp 95–96ºC. IR spectrum, ν, cm–1:
1
сm–1: 2220 (−C ≡C−). H NMR spectrum (DМSО), δ,
ppm, (J, Hz): 2.59 d (3Н, 4J РH 4.7, СН3), 7.42−7.98 m
(15Н, С6Н5 of salt and 15Н, С6Н5 of oxide). 31Р NMR
spectrum (DМSО), δ, ppm: 10.5 (salt) and 30.7
(oxide).
Reaction of triphenylphosphine with propargyl
bromide in ether. Propargyl bromide, 3 g, was added
dropwise to a solution of 6.6 g of triphenylphosphine
in 30 ml of absolute ether under nitrogen. At the next
day, the precipitate was filtered off, washed in
succession with several portions of absolute ether, a
minimum of dry acetonitrile, and ether and dried under
a vacuum to obtain 4.0 g (44.0%) of [2-(triphenyl-
phosphonio)prop-2-enyl]triphenylphosphonium dibro-
mide (VI), mp 275ºC. IR spectrum, ν, cm–1: 1620,
1
1615 (Р+–CН=С). H NMR spectrum (DМSО), δ,
3
ppm, (J, Hz): 1.27 t (6Н, JНH 7.1, СН3), 1.87 s (3Н,
3
2
СН3), 3.53 q (4Н, JНH 7.1, NСН2), 3.96 d (1Н, JРH
13.9, РСН), 7.66–7.82 m (15Н, С6Н5). 31Р NMR
spectrum (DМSО), δ, ppm: 21.5. Found, %: Br 18.16.
С25Н29ВrNР . Calculated, %: Вr 17.62.
1
(C=СН2). H NMR spectrum (DМSО), δ, ppm, (J,
Reaction of triphenylpropargylphosphonium
bromide (I) with piperidine. Piperidine, 0.4 g, was
added to 1.6 g of salt I and 10 ml of dry acetonitrile.
At the next day, acetonitrile was removed under a
vacuum. The precipitate was washed with absolute
ether and dried to obtain 1.2 g of a mixture of triphenyl
(2-piperidinoprop-1-enyl)phosphonium bromide and
piperidine hydrobromide in a 9 : 1. IR spectrum of the
mixture, ν, сm–1: 1610 (Р+–CН=С ). 1H NMR spectrum
of the salt (DМSО), δ, ppm, (J, Hz): 1.65–1.75 m (6Н,
СН2) and 3.58 m (4Н, NСН2 of piperidine), 1.88 s
2
3
Hz): 5.14 d.d (2Н, JPH 15.4, JPH 9.7, РСН2), 6.41 d.t
(1Н, 3JPH 22.1, 2JНH = 4JPH = 3.1, С=СН2), 6.58 d.t (1Н,
2
4
3JPH 46.2, JНH = JPH = 3.1, C=СН2), 7.61−7.96 m
(30Н, С6Н5). 13С NMR spectrum (DМSО), δ, ppm,
1
2
23.8 d.d (СН2, JPС 49.0, JPС 12.8), 119.2 d.d (=С,
2
1
1JPС 78.5, JPС 7.0), 146.8 (=СН2), 115.4 d (Сipso, JPС
88.1), 117.1 d (Сipso, JPС 86.0), 130.4 d (2JPС 12.8),
1
130.4 d (2JPС 12.8), 133.9 d (3JPС 10.6), 134.7 d (3JPС
10.5), 135.4 d (4JPС 2.9), 135.6 d (3JPС 2.9). 31Р NMR
spectrum (DМSО), δ, ppm: 28.5 d (3JPР 24.3), 32.5 d
(3JPР 24.3). Found, %: Br 21.5. С39Н34Вr2Р2. Cal-
culated, % : Вr 22.1. A similar result was obtained in
the reaction in absolute benzene.
2
(3Н, СН3), 4.20 d (1Н, JРH 14.1, РСН), 7.66–7.82 m
(15Н, С6Н5). 31Р NMR spectrum (DМSО), δ, ppm:
22.8 . 1H NMR spectrum of piperidine hydrobromide
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BAGDASARYAN et al.
(DМSO), δ, ppm, (J, Hz): 1.80–1.85 m (6Н, СН2) and
3.0–3.1 t (4Н, NСН2), 9.1 w (2Н, NН2).
b. In dry acetonitrile. Salt I, 1 g, was refluxed in
15 ml of acetonitrile for 17 h. The solvent was
removed under a vacuum. The residue was washed
with absolute ether and dried to obtain 0.9 g of a
mixture of salts V and I. IR spectrum of the mixture, ν,
сm–1: 2200 (–C≡C–) and 2100 (–C≡CН), 3150 (≡CН ).
+
Reaction of triphenylpropargylphosphonium
bromide (I) with triethylamine. A heterogeneous
mixture of 1 g of salt I, 0.3 g of triethylamine, and 10 ml
of acetonitrile was allowed to stand at room
temperature for 24 h. Acetonitrile was removed under
a vacuum. The precipitate was washed with several
portions of absolute ether and dried to obtain 0.95 g of
c. In chloroform. : Salt I, 1 g, was refluxed in 8 ml
of chloroform for 21 h and then treated as above to
obtain 1 g of a mixture of salts V and II. IR spectrum
of the mixture, ν, сm–1: 2200 (–C≡C–) and 1940
(allene).
a
mixture of triphenylphosphine oxide and
1
triethylamine hydrobromide. H NMR spectrum of the
mixture (СDСl3), δ, ppm, (J, Hz): 1.42 t (9Н,
NСН2СН3), 3.19 m (6Н, NСН2), 7.41–7.88 m (15Н,
С6Н5 of oxide), 11.25 br (1Н, N+Н). 31Р NMR
spectrum (СDСl3), δ, ppm: 33.2 (oxide). Chloroform
and water were added to the mixture, and the layers
were separated. Triethylamine hydrobromide, 0.23 g
(48.9%), mp 245°С, was isolated from the aqueous
layer after evaporation on a water bath. The product
gave no melting point depression in a mixture with an
authentic sample. From the chloroform layer, 0.4 g
(55.5 %) of triphenylphosphine oxide was isolated, mp
152–154°С. The product gave no melting point
depression in a mixture with an authentic sample.
[2-(Hydroxylimino)propyl]triphenylacetonyl-
phosphonium bromide. A mixture of 2 g of salt III,
0.7 g of hydroxylamine hydrochloride, 4.1 ml of
ethanol, and 4.0 g of pyridine was heated on a water
bath with stirring for 2 h. Water was partially removed
by distillation, the residue was filtered off, and dried to
obtain 1.78 g (85.9%) of the oxime as a mixture of two
stereoisomers, mp 177–179°С. IR spectrum, ν, сm–1:
1
1670 (С=N). H NMR spectrum (DМSО), δ, ppm, (J,
2
Hz): 1.96 s (3Н, СН3), 4.88 d (2Н, JPH 16.9, РСН2)
2
and 5.08 d (2Н, JPH 14.2, РСН2), 7.3–7.95 m (15Н,
С6Н5), 10.87 s (1Н, ОН) and 11.19 s (1Н, ОН). Found,
Reaction of triphenyl(phenylethynyl)phospho-
nium bromide with triethylamine. Triethylamine,
0.34 g, was added dropwise to a solution of 1.5 g of
the salt in 7 ml of acetonitrile. After 2 h, crystal
formation was observed. At the next day, the solvent
was removed by vacuum distillation. The precipitate
was washed with several portions of absolute ether and
dried to obtain 0.9 g of a mixture of the starting salt
and triethylamine hydrobromide in a 44.5 : 55.5 (1H
NMR spectrum). IR spectrum of the mixture, ν, cm–1:
%: Br 19.88, С21Н21ВrNОР. Calculated, %: Вr 19.32.
Attempted cyclization of [2-(hydroxylimino)-
propyl]triphenylacetonylphosphonium
bromide.
According to [11], a mixture of 1.3 g of the oxime in a
minimum of methanol and 3.6 ml of 1 N aqueous
NaOH was allowed to stand at room temperature to
obatin 0.8 g (95.9%) of triphenylphosphine oxide, mp
150–152ºC. The product gave no melting point
depression in a mixture with an authentic sample.
1
2200 (–С≡C–). H NMR spectrum of the mixture
(СDСl3), δ, ppm, (J, Hz): 1.42 t (9Н, NСН2СН3), 3.21
m (6Н, NСН2), 7.41–7.65 m (5Н, Р+–С≡C–С6Н5 ),
7.8–7.98 m (15Н, С6Н5), 10.4 br (1Н, N+Н). 31Р
spectrum (СDСl3), δ, ppm: 11.9 (salt). Triphenyl-
phosphine oxide, 0.37 g (40%), was also obtained, mp
154ºC. The product gave no melting point depression
in a mixture with an authentic sample. 31Р NMR
spectrum (СDСl3), δ, ppm: 33.3.
REFERENCES
1. Hoffmann, H. and Dichr, H.J., Chem. Ber., 1965, vol. 98,
p. 363.
2. Hoffmann, H. and Foerster, H., Tetrahedron Lett., 1964,
vols. 17–18, p. 983.
3. Schweiser, E.E., De Voc Coff, S., and Murray, W.P.,
J. Org. Chem., 1977, vol. 42, no. 2, p. 200.
Isomerization of triphenylpropargylphospho-
nium bromide (I) in various solvents. a. In water.
Salt I, 1 g, was refluxed in 15 ml of water for 5 h. The
solvent was removed by distillation. The residue was
washed with benzene and ether and dried to obtain 1 g
of a mixture of salts V and III. IR spectrum of the
mixture, ν, сm–1: 2215 (–C≡C–) and 1700 (С=О).
4. Aklyan, Zh.А. and Khаchаtryan, R.А., Arm. Khim. Zh.,
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1965, vol. 682, p. 62.
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