Reaction of triphenyl(phenylethynyl)phosphonium bromide with α-aminoethers, dipiperidinomethane, and secondary amines

Article abstract of DOI:10.1134/S1070363207050088

The reactions of triphenyl(phenylethynyl)phosphonium bromide with α-aminoethers lead to formation of triphenyl(2-amino-2-phenylvinyl) phosphonium bromides. In the case of acyclic aminoethers, this reaction is accompanied by the formation of the corresponding amine hydrobromide and triphenylphosphine oxide by a scheme analogous to that of alkaline hydrolysis of phosphonium salts and involving attack of the amine on the phosphorus atom. The reaction of the same salt with diethyl-or dipropylamine affords hydrobromides of the latter, while with piperidine, together with salts, its adduct by the triple bond is formed. Piperidinomethane with the same salt forms triphenylphosphonium (2-phenyl-2-piperidinovinyl)phosphonium bromide. Nauka/Interperiodica 2007.

Full text of DOI:10.1134/S1070363207050088

ISSN 1070-3632, Russian Journal of General Chemistry, 2007, Vol. 77, No. 5, pp. 866 870.
Pleiades Publishing, Ltd., 2007.
Original Russian Text G.B. Bagdasaryan, P.S. Pogosyan, G.A. Panosyan, M.G. Indzhikyan, 2007, published in Zhurnal Obshchei Khimii, 2007,
Vol. 77, No. 5, pp. 769 773.
Reaction of Triphenyl(phenylethynyl)phosphonium Bromide
with -Aminoethers, Dipiperidinomethane,
and Secondary Amines
G. B. Bagdasaryana, P. S. Pogosyana, G. A. Panosyanb, and M. G. Indzhikyana
a Institute of Organic Chemistry, National Academy of Sciences of Armenia,
ul. Z. Kanakertsi 167a, Erevan, 375091 Armenia
b Center for Molecular Research, National Academy of Sciences of Armenia, Erevan, Armenia
Received February 1, 2007
Abstract The reactions of triphenyl(phenylethynyl)phosphonium bromide with -aminoethers lead to
formation of triphenyl(2-amino-2-phenylvinyl)phosphonium bromides. In the case of acyclic aminoethers, this
reaction is accompanied by the formation of the corresponding amine hydrobromide and triphenylphosphine
oxide by a scheme analogous to that of alkaline hydrolysis of phosphonium salts and involving attack of the
amine on the phosphorus atom. The reaction of the same salt with diethyl- or dipropylamine affords hydro-
bromides of the latter, while with piperidine, together with salts, its adduct by the triple bond is formed.
Piperidinomethane with the same salt forms triphenylphosphonium (2-phenyl-2-piperidinovinyl)phosphonium
bromide.
DOI: 10.1134/S1070363207050088
According to published data, triphenyl(phenyl-
ethynyl)phosphonium bromide (I) reacts with primary
amines and azoles, affording vinyl-containing adducts
[1 4]. Similar pathways are characteristic of the reac-
tions of I with phenylhydrazine, hydroxylamine, and
dialkyl phosphates, with the only difference that in
these cases the resulting adducts enter further trans-
formations: The adducts of phenylhydrazine and hyd-
roxylamine undergo tautomerization into hydrazones
and oximes, those of hydrazine hydrate undergo al-
kaline hydrolysis, and those of dialkyl phosphates are
converted into O-betaines with the positively charged
phosphonium center [5, 6].
We studied the reactions of salt I with -amino-
ethers II V and dipiperidinomethane (VI).
The presence of two centers of nucleophilic attack
in compounds II V did not allow us to predict the
actual reaction pathway. It might be assumed that the
greater mesomeric effect of the nitrogen atom can
direct this reaction to the side of oxygen with a weak
C O bond.
The resulting data were rather unexpected. The re-
actions of compounds II IV with salt I gave triphe-
nyl[2-phenyl-2-(dialkylamino)vinyl]phosphonium
bromides IIa IVa.
We suggest that this reaction proceeds by the fol-
lowing scheme:
+
+
Ph3P C C Ph + R2NCH2OCH2CH3
Ph3P C=C Ph
Br
H2C >H
Br
>
NR2
I
II IV
H2C<
O
CH2
+
Ph3P C=C Ph + CH2=CH2+ CH2O
Br
H
+
HBr, H2O
NR2
Ph3P CH2 C Ph
Br
O
IIa IVa
VII
R2 = (C2H5)2 (II, IIa), (C3H7)2 (III, IIIa), (CH2)5 (IV, IVa).
866

REACTION OF TRIPHENYL(PHENYLETHYNYL)PHOSPHONIUM BROMIDE
867
As seen, the ylide formed by the attack of the
aminoether nitrogen on the triple bond is stabilized
via elimination of ethylene and formaldehyde. For-
maldehyde, indeed, was detected among the reaction
products.
similar way. In this case, the intermediate ylide is
most probably stabilized by a scheme involving eli-
mination of a proton from the methoxy group, expul-
sion of formaldehyde, and elimination of a methylene
group as a carbene which then converts into poly-
methylene. Analogous behavior of methylammonium
ylides has been described earlier [7].
Diethyl(methoxymethyl)amine (V) reacted in a
+
+
+
Ph3P C=C Ph + (CH2)n
I + (C2H5)2NCH2OCH3
Ph3P C=C Ph
Ph3P C=C Ph
CH2O
+
H
Br
+
H
<
>
V
H
N(C2H5)2
N(C2H5)2
N(C2H5)2
Br
IIa
H2C<
H2C
CH2
O
The structure of the obtained adducts was estab-
lished by their acid hydrolysis into phenacyltriphenyl-
phosphonium bromide (VII) and by NMR spectro-
Furthermore, in the 13C NMR spectrum of com-
pound IIa, the signal of the -carbon atom appears
fairly upfield (
59.9 ppm), which is absolutely
C
scopy. The H and 13C NMR spectra of these com-
atypical of sp2-carbon atoms. At the same time, the
signal of the -carbon atom is shifted downfield to
164.4 ppm. The difference of the chemical shifts
oCf more than 100 ppm provides evidence showing
that the C=C bond in these compounds is strongly
polarized.
1
pounds show that two alkyl groups at the nitrogen
atom are nonequivalent, implying a high barrier to
rotation about the C N bond, and, consequently, a
considerable shift of the the nitrogen lone electron
pair toward the C=C bond.
+
-------
The reaction of salt I with dipiperidinomethane
(VI) gave adduct IVa by the following scheme:
P C=C N
+
+
Ph3P C=C
Ph3P C=C Ph + CH2=CH(CH2)3N=CH2
Br
I +
N CH2 N
+
N
H
H^
Br
>
VI
N
CH2
N
IVa
Conclusive evidence for the structure of the pro-
ducts was provided by the results of the reactions of
salt I with diethylmine, dipropylamine, and piperidine
under the same conditions as in the reactions with
aminoethers. In the two first cases we unexpectedly
isolated the corresponding amine hydrobromides, and
in the third case we obtained a mixture of adduct IVa
and piperidine hydrobromide. We suggest that the
hydrobromide is formed by a scheme analogous to
alkaline hydrolysis or the so-called paraffin cleavage
of phosphonium salts.
+
R2NH
R2NH
Ph3P C C Ph
Br
R2NH HBr + Ph3P C C Ph
Ph3P C C Ph
<
R2+NH
Br
R2N:
+
H2O
Ph3P=O + R2NH + HC C Ph
Ph3P=NR2 + C C Ph
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 5 2007

868
BAGDASARYAN et al.
The possibility of such cleavage was established
ethers II, III, and V. These reactions are likely to
proceed by a scheme analogous to shown above, but
the intermediate phosphinoammonium compound is
stabilized by nucleophlic substitution at the oxygen
atom, anionization of the phenylethynyl goup, and
alkylation with the liberated alkyl halide.
earlier in our study of the reaction of a phosphonium
salt containing a 3,4-dichlorobut-2-enyl group with
hydrazine [8].
Note that the formation of amine hydrohalides was
also observed in the reactions of salt I with amino-
Br
Ph3P C C Ph
:NR2
I + II, III, V
Ph3P C C Ph
CH2O,
R1Br
R1
R2+N
CH2
O
R1Br, H2O
+
Ph3P=NR2 + C C Ph
Ph3P=O + R2NH HBr + R1 C C Ph,
R = R1 = C2H5 (II); R = C3H7, R1 = C2H5 (III); R = C2H5, R1 = CH3 (V).
EXPERIMENTAL
NMR spectrum of diethylamine hydrobromide
(DMSO-d6/CCl4, 1:3), , ppm, (J, Hz): 1.3 t (6H,
The NMR spectra were registered on a Varian
Mercury-300 spectrometer at 300.08 (1H), 121.75
(31P), and 75.46 MHz (13C), respectively, at 303 K.
The chemical shifts were measured relative to internal
TMS (1H, 13C) and external H3PO4 (31P). The DEPT
procedure was used for assignment of the 13C NMR
spectra. The IR spectra are registered on UR-20 and
Specord IR-75 instruments.
CH3), 2.95 q (4H, NCH2), 8.85 br (2H, +NH2).
After washing with water and drying, 2.4 g
(68.65%) of mixture IIa was obtained. Found, %: Br
16.2. C30H31BrNP. Calculated, %: Br 15.50.
(2) Acid hydrolysis of [2-(diethylamino)-2-phe-
nylvinyl] triphenylphosphonium bromide (IIa). To
a solution of 0.75 g of salt IIa in 7.0 ml of alcohol,
0.5 ml of 40.5% HBr was added dropwise with stir-
ring. The mixture was refluxed for 1 h with stirring.
The precipitate formed after most alcohol had been
removed by distillation was washed with water and
dried to obtain 0.35 g (54.28%) of phenacyltriphenyl-
phosphonium bromide (VII), mp 272 273 C, which
showed no melting point depression in mixture with
(1) Reaction of triphenyl(phenylethynyl)phos-
phonium bromide (I) with (ethoxymethyl)diethyl-
amine (II). A solution of 3.0 g of salt I and 0.88 g of
aminoether II in 13 ml of anhydrous acetonitrile was
heated on a water bath at 80 C for 16 h. After cooling,
acetonitrile was removed in a vacuum, the precipitate
formed was washed with absolute benzene and ab-
solute ether, and dried to obtain 2.64 g of a mixture
of [2-(diethylamino)-2-phenylvinyl]triphenylphos-
phonium bromide (IIa) and diethylamine hydrobro-
1
an authentic sample. IR spectrum, , cm : 1673
(PhC=O). 1HNMR spectrum (CDCl3), , ppm, (J, Hz):
6.4 d (2H, CH2, 2JPH 11.3), 7.4 8.0 m (15H, PPh3 and
1
3H, meta,para PhC=O), 8.35 8.45 m (2H, ortho,ortho
mide in a 4.6:1 ratio (by H NMR). IR spectrum of
1
1
PhC=O). 31P NMR spectrum (CDCl3):
22.55 ppm.
the mixture, , cm : 1635 (P+ CH=C). H NMR
P
Found, %: Br 16.45. C26H22BrOP. Calculated, %:
Br 17.35.
spectrum of salt IIa (DMSO-d6/CCl4, 1:3), , ppm
3
(J, Hz): 0.99 t (3H, JHH 7.1 Hz, CH3), 1.51 t (3H,
3
3JHH 7.1 Hz, CH3), 2.97 q (2H, JHH 7.1, NCH2),
Acid hydrolysis of compounds IIIa IVa was per-
formed similarly.
3
2
3.82 q (2H, JHH 7.1, NCH2), 4.50 d (1H, JPH 12.5,
PCH), 6.71 m (2H, ortho-HPh), 6.90 m (2H, meta-
(3) Reaction of salt I with (ethoxymethyl)dipro-
pylamine (III). A mixture of 0.8 g of salt I and
0.34 g of compound III in acetonitrile was heated for
20 h and then treated as in the preceeding experiment
to obtain 0.5 g of a mixture of triphenyl[2-(dipropyl-
amino)-2-phenylvinyl]phosphonium bromide (IIIa)
and dipropylamine hydrobromide in a 1:2 ratio (by
1H NMR) as an oily substance. IR spectrum of the
3
4
HPh), 7.14 t.t (1H, JHH 7.6, JHH 1.4 para-HPh),
7.42 7.70 m (15H, PPh3). 13C NMR spectrum
(DMSO-d6/CCl4, 1:3), C, ppm: 10.9 (CH3), 13.8
(CH3), 43.5 (NCH2), 45.4 (NCH2), 59.9 d (1JPC 123.0,
1
PCH), 123.4 d (3C, JPC 90.6, Cipso, PPh3), 129.1 d
2
3
(6C, JPC 12.1, PPh3), 132.0 d (6C, JPC 10.6, PPh3),
132.8 d (3C, JPC 2.7, PPh3), 166.4 d (2JPC 15.1,
4
N=C). 31P NMR spectrum (CDCl3):
22.2 ppm. H
mixture, , cm : 1635 (P+ CH=C). H NMR spec-
1
1
1
P
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 77 No. 5 2007

REACTION OF TRIPHENYL(PHENYLETHYNYL)PHOSPHONIUM BROMIDE
869
trum of salt IIIa (DMSO-d6/CCl4, 1:3), , ppm, (J,
Hz): 0.61 t (3H, JHH 7.2, CH3), 1.10 t (3H, JHH 7.2,
nitrile and then treated with absolute benzene and ab-
3
3
solute ether to obtain 1.5 g of a mixture of IIa and
1
diethylamine hydrobromide (by H NMR). The mix-
CH3), 1.45 m (2H, CH2), 1.93 m (2H, CH2), 2.94 br
2
ture was washed with water to isolate 1.25 g (53.3%)
(2H, NCH2), 3.68 br (2H, NCH2), 4.71 d (1H, JPH
1
of compound IIa. The IR and H NMR spectra coin-
11.8, PCH), 6.71 m (2H, ortho-HPh), 6.88 m (2H,
3
4
cide with those in exp. no. 1. Found, %: Br 16.05.
C30H31BrNP. Calculated, %: Br 15.5.
meta-HPh), 7.13 t.t (1H, JHH 7.5, JHH 1.1, para-
HPh), 7.45 7.72 m (15H, PPh3). 31P NMR spectrum
(DMSO-d6/CCl4, 1:3), P, ppm: 19.4. H NMR spec-
1
(8) Reaction of salt I with dipiperidinomethane
(VI). A mixture of 1.4 g of salt I and 0.57 g of com-
pound VI was heated for 16 h at 80 C in 25 ml of
anhydrous acetonitrile and then treated with absolute
ether and benzene to obtain 1.2 g (72.2%) of mixture
trum of dipropylamine hydrobromide (DMSO-d6/CCl4,
1:3), , ppm, (J, Hz): 1.02 t (6H, CH3), 1.79 m (4H,
CH2), 2.82 t (4H, NCH2), 8.87 br (2H, +NH2).
(4) Acid hydrolysis of triphenyl[2-dipropyl-2-
(phenylamino)vinyl]phosphonium bromide (IIIa).
From 1.5 g of compound IIIa under conditions of
exp. no. 2 we obtained 0.66 g (53.22%) of ketophos-
phonium salt VII, mp 272 273 C, which showed no
melting point depression in mixture with an authentic
1
IVa. The IR and H and 31P NMR spectra coincide
with those in exp. no. 5. Found, %: Br 15.09.
C31H31BrNP. Calculated, %: Br 15.15.
(9) Reaction of salt I with piperidine. A mixture
of 0.8 g of salt I and 0.18 g of piperidine was heated
for 9.5 h in acetonitrile to obtain 0.5 g of mixture IVa
1
sample. The IR and H and 31P NMR spectra coincide
1
with those in exp. no. 2. Found, %: Br 16.95.
C26H22BrOP. Calculated, %: Br 17.35.
and piperidine hydrobromide (by H NMR) and then
trated with water, absolute ether, and absolute benzene
to isolate 0.3 g (31.5%) of phosphonium salt IVa, mp
120 121 C, which showed no melting point depres-
sion in mixture with an authentic sample.
(5) Reaction of salt I with 1-(ethoxymethyl)pi-
peridine (IV). A mixture of 3.5 g of salt I and 1.13 g
of compound IV was heated for 18 h in acetonitrile
and then treated with a minimum quantity of water
followed by absolute benzene and absolute ether to
obtain 3.0 g (70.88%) of triphenyl(2-phenyl-2-piperi-
dinovinyl)phosphonium bromide (IVa), mp 119
121 C, which showed no melting point depression in
(10) Reaction of salt I with diethylamine. A mix-
ture of 0.7 g of salt I and 0.14 g of diethylamine was
heated for 17 h in anhydrous acetonitrile and then
treated with absolute ether and recrystallized (absolute
benzene:absolute alcohol, 5:1) to obtain 0.164 g
(67.08%) of diethylamine hydrobromide, mp 210
210.5 C, which showed no melting point depression
in mixture with an authentic sample. Found, %: Br
52.6. C4H12BrN. Calculated, %: Br 51.94.
mixture with an authentic sample. IR spectrum,
,
1
1
cm : 1640 (P+ CH=C). H NMR spectrum (DMSO-
d6), , ppm, (J, Hz): 1.62 1.86 m (6H, CH2) and
2
2.84 3.0 m (4H, NCH2 piperidine), 5.0 d (1H, JPH
12.3, PCH), 6.75 7.15 m (5H, PhC=C), 7.5 7.77 m
(15H, PPh3). 31P NMR spectra (DMSO-d6), , ppm:
19.64. Found, %: Br 15.35. C31H31BrNP. Calculated,
%: Br 15.15.
After removal of the solvent from the ethereal ex-
tracts we isolated 0.154 g (35.2%) triphenylphosphine
oxide, mp 153 154 C, which showed no melting
point depression in mixture with an authentic sample.
Formaldehyde, 0.057 g (24%), was also isolated.
Its 2,4-dinitrophenylhydrazone melted at 166 C and
showed no melting point depression in mixture with
an authentic sample.
(11) Reaction of of salt I with dipropylamine.
From 0.45 g of salt I and 0.12 g of dipropylamine
under conditions of exp. no. 10 we obtained 0.0673 g
(37%) of dipropylamine hydrobromide, mp 268 C,
which showed no melting point depression in mixture
with an authentic sample. Found, %: Br 43.8.
C6H15BrN. Calculated, %: Br 43.95. Triphenyl-
phosphine oxide, 0.1158 g (41.65%), was also ob-
tained.
(6) Acid hydrolysis of triphenyl(2-phenyl-2-pi-
peridinovinyl)phosphonium bromide (IVa). By
heating 1.8 g of compound IVa under conditions of
exp. no. 2 we obtained 0.8 g (50%) of ketophospho-
nium salt VII, mp 272 273 C, which showed no
melting point depression in mixture with an authentic
1
sample. The IR and H and 31P NMR spectra coincide
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