Cyclocondensation of [1-cyano-2-(methylsulfanyl)vinyl]triphenylphosphonium iodide with amidine nucleophiles

Article abstract of DOI:10.1007/s11176-005-0266-2

The substituted vinylphosphonium salt (E)-MeSCH=C(CN)P⁺Ph ₃I^- readily cyclizes under the action of benzamidine and 3-amino-s-triazole, but it does not enter cyclocondensation with 2-aminopyridine. The structure of the cycl

Full text of DOI:10.1007/s11176-005-0266-2

Russian Journal of General Chemistry, Vol. 75, No. 4, 2005, pp. 527 532. Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005,
pp. 565 570.
Original Russian Text Copyright
2005 by Smolii, Muzychka, Chernega, Drach.
Cyclocondensation
of [1-Cyano-2-(methylsulfanyl)vinyl]triphenylphosphonium
Iodide with Amidine Nucleophiles
O. B. Smolii, L. V. Muzychka, A. N. Chernega, and B. S. Drach
Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received November 12, 2003
Abstract The substituted vinylphosphonium salt (E)-MeSCH=C(CN)P+Ph3I readily cyclizes under the
action of benzamidine and 3-amino-s-triazole, but it does not enter cyclocondensation with 2-aminopyridine.
The structure of the cyclization product with 3-amino-s-triazole was confirmed by its transformation to 7-imino-
6-(triphenylphosphoranylidene)-6,7-dihydro-s-triazolo[1,5]pyrimidine which was identified by X-ray diffrac-
tion. This stabilized ylide and its analogs proved useful starting materials for regioselective syntheses of
2-R-4-alkyl-4,7-dihydro-s-triazolo[1,5-a]pyrimidin-7-ones.
Previously we developed a convenient method for
As would be expected, replacement of the 2-py-
ridyl fragment in III by p-tolyl does not change
significantly the chemical shift of the N H proton
preparing
(E)-[1-cyano-2-(methylsulfanyl)vinyl]tri-
phenylphosphonium iodide (I), a promising multi-
center electrophilic reagent for various cyclizations
[1]. The most thoroughly studied is its cyclocondensa-
tion with hydrazine and its derivatives [2]. In the
present work we have studied reactions of compound
I with a series of amidine nucleophilic substrates.
This process leads or may lead to compounds II X
(see scheme and Tables 1 and 2).
signal [
11.74 ppm for (1-cyano-2-p-toluidino-
NH
vinyl)triphenylphosphonium iodide XI].
These data allow us to exclude formation of isomer
XII in which the imino group cannot come in con-
jugation with the exocyclic
system and, what is
more, steric factors unfavor intramolecular hydrogen
bonding.
Treatment of reagent I with benzamidine evidently
leads to formation not only of (4-amino-2-phenylpyr-
imidin-5-yl)triphenylphosphonium iodide (II), but
also of some other compounds, which complicates
isolation of the major condensation product pure.
Nevertheless, after alkaline dephosphorylation we
could isolate about 60% of 4-amino-2-phenylpyrimi-
dine that was prepared previously by another proce-
dure [3], and thus obtained unambiguous evidence for
the structure of intermediate phosphonium salt II.
+
PPh3
I
H N
C N
XII
The signal of the imino proton of phosphonium salt
XII can not be observed near 12 ppm, since the
respective signal of related compounds IV and VIII
locates near 8 ppm (Table 1).
We expected that reagent I would similarly react
with 2-aminopyrimidine. However, we could only
obtain compound III arising from initial nucleophilic
substitution of the methylsulfanyl group. This product
underwent no cyclization in the presence of both acids
and bases. The structure of compound III was con-
Unlike 2-aminopyridine which does not enter
cyclocondensation with reagent I, 3-amino-s-triazole
and 3-amino-5-phenyl-s-triazole, that contains an
amidine residue, extremely easily convert into com-
pounds IV and VII (the latter are formed by HI
elimination from IV). The structure of one of the
stabilized ylides VIIa was reliably established by
X-ray diffraction analysis. The general view of mo-
lecule VIIa is given in the figure, principal bond
lengths and angles, in Table 3, and atomic coordi-
nates, in Table 4.
1
1
firmed by means of H NMR spectroscopy. In the H
NMR spectrum in DMSO-d6, the enamine N H
proton appears as a broad downfield singlet at
12.16 ppm, which may be explained by strong con-
jugation of the lone electron pair of the exocyclic
nitrogen atom with the electron-deficient acyclic
system.
1070-3632/05/7504-0527 2005 Pleiades Publishing, Inc.

528
SMOLII et al.
+
PPh3
I
N
H2N
NH
NH
H2N
MeS
C N
I
N
Ph
R
N
H2N
+
+
+
PPh3
I
PPh3
I
PPh3
I
NH
NH2
C N
HN
N
N
N
N
HN
N
N
Ph
R
II
III
IVa, IVb
NaOH
MeONa
+
PPh3
I
PPh3
NH2
NH
N
NH
N
N
N
N
N
N
Ph
N
R
V
VI
VIIa, VIIb
1) AlkHlg; 2) NaClO4
+
+
PPh3 An
NH
PPh3 ClO4
O
N
O
1) HCl. H2O;
2) NaClO4
Et3N, H2O
N
N
N
N
N
N
N
N
Alk
Alk
Alk
N
N
N
R
R
R
VIIIa VIIId
IXa IXd
Xa Xd
R = H (a, c, d), C6H5 (b); An = ClO4 (VIIIa, VIIIc, VIIId), I (VIIIb); Alk = CH3 (a, b), C2H5 (c), CH2=CH CH2 (d);
Hlg = Br, I.
Table 1. 1H NMR spectral data of the synthesized compounds
, ppm (DMSO-d6)
3
3
3
III
7.20 d.d (1H, CH arom., JHH 5.1, JHH 5.4 Hz), 7.41 d (1H, CH arom., JHH 8.1 Hz), 7.86 7.99 m (16H,
3
3
CH arom.), 8.18 d (1H, CH arom., JHH 3.6 Hz), 8.38 d (1H, CH, JHP 12 Hz), 12.16 s (1H, NH)
VIIa 6.85 s (1H, NH), 7.20 d (1H, C5H, JHH 8.1 Hz), 7.70 7.81 m (15H, 3C6H5), 8.10 s (1H, C2H)
VIIIa 3.69 (3H, CH3), 7.47 d (1H, C5H, 3JHP 12.3 Hz), 7.71 7.87 m (15H, 3C6H5), 8.38 s (1H, NH), 8.41 s (1H, C2H)
IXd 4.94 d (2H, CH2, 3JHH 1.5 Hz), 5.27 5.41 m (2H, CH2), 5.95 m (1H, CH=CH2), 7.79 7.91 m (16H, 3C6H5, C5H),
8.53 s (1H, C2H)
3
3
3
Xa
Xb
3.79 s (3H, CH3), 6.03 d (1H, C6H, JHH 7.8 Hz), 8.07 d (1H, C5H, JHH 8.1 Hz), 8.28 s (1H, C2H)
3.84 s (3H, CH3), 6.04 d (1H, C6H, JHH 7.8 Hz), 7.53 m (3H, CH arom.), 8.07 d (1H, C5H, JHH 7.8 Hz),
3
3
8.15 m (2H, 2CH arom.)
Xd
XI
4.83 d (2H, CH2, 3JHH 5.7 Hz), 5.29 m (2H, 2CH), 6.00 6.11 m (2H, C6H, CH), 8.09 d (1H, C5H, 3JHH 7.8 Hz),
8.27 s (1H, C2H)
3
3
2.62 s (3H, CH3), 7.12 d.d (4H, CH arom., JHH 8.4, JHH 8.4 Hz), 7.57 d (1H, CH, 3JHP 11.1 Hz), 7.83 7.97 m
(15H, 3C6H5), 11.74 s (1H, NH)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

CYCLOCONDENSATION OF [1-CYANO-2-(METHYLSULFANYL)VINYL]...
Table 2. Constants, yields, and elemental analyses of the synthesized compounds
Found, %
529
Calculated, %
(Cl) (I)
(23.79)
mp, C (solvent for
Formula
crystallization)
(Cl) (I)
(23.75)
N
P
N
P
III
73 224 22(acetone)
80 278 279(ethanol acetonitrile, 1: 1) (24.28) 13.41
55 182 184(ethanol)
87 249 251(acetonitrile)
78 289 291(ethanol acetonitrile, 1: 1)
65 171 173(ethanol)
90 294 296(ethanol acetonitrile, 2: 1) (20.71) 11.48
58 136 138(ethanol)
69 195 197(ethanol)
60 190 192(ethanol acetonitrile, 2: 1)
62 303 305(ethanol)
36 159 161(ethanol acetonitrile, 2: 1)
59 218 219(ethanol)
82 236 238(ethanol)
78 248 250(ethanol)
45 143 145(ethanol diethyl ether, 2: 1)
51 102 104(ethanol)
7.86
5.84 C26H21IN3P
5.94 C23H19IN5P
5.05 C29H23IN5P
7.91 C23H18N5P
6.60 C29H22N5Pa
6.12 C24H21ClN5O4P
5.11 C30H25IN5P
5.94 C25H23ClN5O4P
5.81 C26H23ClN5O4P
5.98 C24H20ClN4O5P
5.32 C30H24ClN4O5P
5.88 C25H22ClN4O5P
5.79 C26H22ClN4O5P
C6H6N4O
7.88 5.81
IVa
IVb
VIIa
VIIb
VIIIa
VIIIb
VIIIc
VIIId
IXa
IXb
IXc
IXd
Xa
(24.25) 13.38 5.92
(21.17) 11.68 5.17
17.71 7.83
(21.20) 11.53
17.77
14.92
13.80
14.85 6.57
13.74 6.07
6.96
6.95
(20.69) 11.42 5.05
6.73
6.68
6.98
6.12
6.79
6.59
13.39
13.00
10.85
9.49
10.70
10.40
37.37
24.82
34.20
31.84
5.10
6.77
6.62
6.94
6.04
6.75
6.60
13.37 5.91
13.07 5.78
10.97 6.06
9.55 5.28
10.67 5.90
10.44 5.77
37.32
Xb
Xc
Xd
C12H10N4Ob
C7H84O
C8H8N4O
24.76
34.13
31.80
XI
82 198 200(ethanol diethyl ether, 1: 1) (23.58)
5.35 C28H24IN2P
(23.23)
5.13 5.67
a
b
Found, %: C 73.89; H 4.74. Calculated, %: C 73.87; H 4.70. Found, %: C 63.74; H 4.43. Calculated, %: C 63.71; H 4.46.
The central bicyclic system N1 4C1 5 is practically
planar: The deviations of atoms from the mean plane
are no larger than 0.065 and 0.13 . The dihedral
angle between the six-membered ring N1N2C1 4 and
the five membered ring N2 4C3C5 is as small as 3.9%.
The geometric parameters of the bicyclic system
suggest significant delocalization of electron density
[4, 5]. The P1 and N5 atoms deviate from this plane
by 0.215 and 0.096 , respectively (the exocyclic
P1 C1 and N5 C4 bonds form angles of 4.9 and 2.7
with the bicyclic system). The P1 C1 distance is
1.756(3) , which allows compound VIIa to be
classed with superstabilized phosphonium ylides (cf.
[6, 7] ). Therefore, along with the nonpolar phosphino-
methylene structure depicted in the scheme, betaine
structures A D play an important role.
+
+
+
+
PPh3
PPh3
PPh3
PPh3
NH
N
NH
N
NH
N
NH
N
N
N
N
N
N
N
N
N
N
N
N
N
A
B
C
D
Inspite of their clearly defined mesomeric nature,
ylide betaines VII are quite selectively alkylated,
which has made possible the transformation sequence
VII VIII IX X. One of the final products of
these transformations, 4-methyl-4,7-dihydro-s-triazolo-
[1,5a]pyrimidin-7-one (Xa), was prepared previously
by an independent procedure [8].
O
N
OMe
N
175 180 C
N
N
N
N
+ Xa
N
N
Me
XIII
XIV
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

530
SMOLII et al.
Table 3. Principal bond lengths (d, ) and bond angles
( , deg) in molecule VIIa
hydro-s-triazolo[1,5-a]pyrimidin-7-ones X is of pre-
parative value. It is quite possible that this approach
can be extended to prepare such complex analogs of
compounds X as acylnucleosides.
Bond
d
Angle
P1 C1
P1 C6
P1 C12
P1 C18
N1 C2
N1 C3
N2 N4
N2 C3
N2 C4
N3 C3
N3 C5
N4 C5
N5 C4
C1 C2
C1 C4
N5 H5
1.756(3)
1.809(2)
1.802(2)
1.806(3)
1.328(3)
1.352(3)
1.371(3)
1.370(3)
1.408(3)
1.330(3)
1.355(4)
1.316(3)
1.280(3)
1.401(3)
1.439(3)
0.91(3)
C1P1C6
C1P1C12
C6P1C12
C1P1C18
C6P1C18
C12P1C18
C2N1C3
N4N2C3
C3N2C4
C3N3C5
N2N4C5
C4N5H5
C2C1C4
N1C2C1
N1C3N2
N2C3N3
N2C4C1
N3C5N4
111.19(12)
113.99(12)
109.63(12)
108.11(12)
109.43(12)
104.19(13)
113.9(2)
110.4(2)
125.4(2)
102.1(2)
100.5(2)
108.1(18)
120.1(2)
126.7(2)
123.1(2)
109.3(2)
EXPERIMENTAL
1
The H NMR spectra were obtained on a Varian
VXR-300 spectrometer for (CD3)2SO solutions
against internal TMS.
X-ray diffraction study of a single crystal (0.50
0.52 0.53 mm) of compound VIIa was carried out
at room temperature on an Enraft Nonius CAD-4
automatic four-curcle diffractometer (MoK radiation;
2 / 1.2;
27 ; index ranges 0 < h < 13, 0 < k <
19, and 17m<ax l < 17). A total of 2731 reflections was
collected, 2402 of which were unique (Rint 0.019).
Crystals of compound I are monoclinic, a 12.880(2),
3
b 9.344(5), c 16.478(14) , 96.24(6) , V 1971(2)
,
3
1
M 395.41, Z 4, dcalc 1.33 g cm , 1.53 cm , and
space group P21/c (no. 14). The structure was solved
by the direct method and refined by anisotropic least
squares using the CRYSTALS program package [9].
Absorption was included by means of azimuthal
scanning [10]. Refining was carried out by 1893 ref-
lections with I > 3 (I) (266 refined parameters, 7.1 re-
flections per one parameter). All hydrogen atoms were
obtained from difference synthesis and included in
the calculations with fixed positional and thermal
parameters (H5 was refined isotropically). The Che-
byshev weight scheme [11] with five parameters, 1.19,
0.77, 1.13, 0.26, and 0.32, was used the refinement.
The final values of divergence factors were R 0.033
and RW 0.035, GOF 1.153. The residual electron
110.5(2)
117.7(2)
The yield of compound Xa in that case did not
exceed 50%, and, moreover, the product should be
separated from isomer XIV by column chromato-
graphy. The application scope of the thermal rearran-
gement XIII
X cannot be wide, and, therefore, the
use of stabilized phosphonium ylide betaines VII for
regioselective synthesis 2-R-4-alkyl(alkenyl)-4,7-di-
C16
C15
density from the differential Fourier series is 0.15 and
3
C17
C10
0.20 e
.
C11
C14
[1-Cyano-2-(2-pyridylamino)vinyl]triphenyl-
phosphonium iodide III. A mixture of 0.01 mol of
phosphonium salt I and 0.01 mol of 2-aminopyridine
in 30 ml of acetonitrile was refluxed for 2 h, left for
1 h at 20 25 C, the solvent was removed in a vacuum,
and the residue was purified by crystallization.
C9
C21
C22
C20
C12
C19
C18
C13
C6
C8
N5
C23
P1
C7
C1
[2-R-7-Imino-4,7-dihydro-s-triazolo[1,5-a]pyr-
imidin-6-yl]triphenylphosphonium iodides IVa and
IVb. A mixture of 0.01 mol of phosphonium salt I
and 0.01 mol of amino-s-triazole or 3-amino-5-phe-
nyl-s-triazole in 40 ml of acetonitrile was refluxed for
5 h and left for 12 h at 20 25 C. The precipitate was
filtered off and purified by crystallization.
C4
C2
H5
N2
N1
N4
C3
N3
4-Amino-2-phenylpyridine (V). To a solution of
0.005 mol of phosphonium salt I in 30 ml of metha-
nol, 0.005 mol of benzamidine and a solution of
0.01 mol of sodium hydroxide in 5 ml of methanol
C5
General view of molecule VIIa.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

CYCLOCONDENSATION OF [1-CYANO-2-(METHYLSULFANYL)VINYL]...
531
was added. The resulting mixture was left for 10 days
at 20 25 C, the methanol was removed in a vacuum,
the residue was washed with 20 ml of water, and the
precipitate was purified by crystallization from
ethanol. Yield 60%, mp 134 136 C, what agrees with
data reported in [3].
Table 4. Atomic coordinates and equivalent isotropic
thermal parameters Ueq
(
2) in molecule VIIa
Atom
x
y
z
Ueq
P1
0.23578(4)
0.41912(15)
0.26635(14)
0.37557(18)
0.22170(17)
0.13657(17)
0.28188(17)
0.37756(18)
0.35851(18)
0.22092(18)
0.2908(2)
0.23297(17)
0.32072(18)
0.3235(2)
0.2397(2)
0.1517(2)
0.23950(6) 0.35316(4)
0.0357
N1
0.0217(2)
0.0313(2)
0.1269(2)
0.0086(2)
0.1980(3)
0.1359(2)
0.0637(3)
0.0403(3)
0.1281(2)
0.1023(3)
0.4275(2)
0.4847(3)
0.6298(3)
0.7157(3)
0.6589(3)
0.5153(3)
0.1853(2)
0.0722(3)
0.0343(3)
0.1091(4)
0.2190(3)
0.2560(3)
0.2124(2)
0.3101(3)
0.2849(3)
0.1648(3)
0.0631(4)
0.0868(3)
0.174(3)
0.23695(13) 0.0500
0.14596(11) 0.0426
0.10430(14) 0.0585
0.07000(12) 0.0553
0.17729(14) 0.0564
0.27572(14) 0.0377
0.28911(15) 0.0448
0.16546(15) 0.0444
0.19727(14) 0.0405
0.04993(16) 0.0608
0.32692(13) 0.0363
0.29639(15) 0.0449
0.27780(17) 0.0545
0.28912(17) 0.0547
0.31797(17) 0.0570
0.33699(15) 0.0470
0.37968(13) 0.0383
0.34082(15) 0.0509
0.36531(19) 0.0672
7-Imino-6-triphenylphosphoranylidene-6,7-di-
hydro-s-triazolo[1,5-a]pyrimidine (VIIa). To a sus-
pension of 0.01 mol of compound IVa or IVb in
30 ml of methanol, 0.01 mol of sodium methylate
was added. The resulting mixture was heated at 40
50 C to dissolve the precipitate, and the solution was
left for 1 h at 20 26 C. Water, 20 ml, was then added,
and the mixture was left for 1 h. A precipitate formed
and was filtered off and purified by crystallisation.
N2
N3
N4
N5
C1
C2
C3
C4
C5
7-Imino-2-phenyl-6-triphenylphosphoranyl-
idene-6,7-dihydro-s-triazolo[1,5-a]pyrimidine
(VIIb) was prepared analogously to compound VIIa,
but after heating at 40 50 C for 10 15 min and cool-
ing to 20 25 C, the precipitate was filtered off and
purified by crystallization.
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
H5
0.14788(18)
0.10949(17)
0.0543(2)
0.0418(2)
0.0821(2)
[7-Imino-4-methyl(ethyl)-4,7-dihydro-s-triazolo-
[1,5-a]pyrimidin-6-yl]triphenylphosphonium per-
chlorates VIIIa and VIIIc. A mixture of 0.01 mol
of compound VIIa and 10 ml of methyl or ethyl
iodide was left for 12 h at 20 25 C. Volatile sub-
stances were removed in a vacuum. The oily residue
was dissolved in 30 ml of ethanol, and 20 ml of the
saturated water solution of sodium perchlorate was
added. The precipitate was filtered off, washed with
water, and purified by crystallization.
0.4264(2)
0.0729
0.0268(2)
0.46573(17) 0.0640
0.44356(15) 0.0484
0.44578(13) 0.0391
0.47511(16) 0.0514
0.54865(17) 0.0602
0.59284(15) 0.0591
0.56201(19) 0.0807
0.48884(18) 0.0696
0.06935(18)
0.32218(17)
0.3966(2)
0.4564(2)
0.4433(2)
0.3721(3)
0.3118(2)
0.112(2)
[7-Imino-4-methyl-2-phenyl-4,7-dihydro-s-tri-
azolo[1,5-a]pyrimidin-6-yl]triphenylphosphonium
iodide (VIIIb) was prepared similarly to compounds
VIIIa and VIIIc, but the residue after removal of
methyl iodide was treated with 30 ml of ethanol, and
the precipitate was filtered off and purified by crystal-
lization.
0.1255(18)
0.071(9)
conc. HCl was heated for 5 h at 90 100 C and then
poured into an ice water. The precipitate was filtered
off and purified by crystallization.
[4-Allyl-7-imino-4,7-dihydro-s-triazolo[1,5-a]-
pyrimidin-6-yl]triphenylphosphonium perchlorate
(VIIId). To a solution of 0.01 mol of compound VIIa
in 30 ml of dichloromethane, 0.012 mol of allyl bro-
mide was added. The resulting mixture was left at 20
25 C for 12 h, the solvent was removed in a vacuum,
the residue was dissolved in 20 ml of ethanol, 20 ml
of saturated aqueous sodium perchlorate was added.
The precipitate was filtered off, washed with water,
and purified by crystallization.
[4-Methyl-7-oxo-2-phenyl-4,7-dihydro-s-triazolo-
[1,5-a]pyrimidin-6-yl]triphenylphosphonium per-
chlorate (IXb) was prepared similarly to compounds
IXa, IXc, and IXd, but after heating with HCl the
product was dissolved in 15 ml of acetonitrile, and
20 ml of saturated aqueous sodium perchlorate was
added. The precipitate was filtered off, washed
with water, and purified by crystallization.
4-Methyl-4,7-dihydro-s-triazolo[1,5-a]pyrimidin-
7-one (Xa). A mixture of 0.006 mol of compound
IXa, 20 ml of acetonitrile, 0.006 mol, and 1 ml of
water was refluxed for 4 5 h, the solvent was re-
moved in a vacuum, and the solid residue was treated
[4-Methyl(ethyl, allyl)-7-oxo-4,7-dihydro-s-tri-
azolo[1,5-a]pyrimidin-6-yl]triphenylphosphonium
perchlorates (IXa, IXc, IXd). A mixture of 0.05 mol
of compounds VIIIa, VIIIc, or VIIId and 25 ml of
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

532
SMOLII et al.
with 10 ml of ethanol. The precipitate was filtered off
and purified by crystallization.
3. Singh, B. and Lesher, G.Y., J. Heterocycl. Chem.,
1977, vol. 14, no. 8, p. 1413.
4. Burke-Laing, M. and Laing, M., Acta Crystallogr.,
Sect. B, 1976, vol. 32, no. 12, p. 3216.
4-Methyl-2-phenyl-4.7-dihydro-s-triazolo[1,5-a]-
pyrimidin-7-one (Xb) was prepared similarly to
compound Xa.
5. Allen, F.H., Kennard, O., Watson, D.G., Brammer, L.,
Orphen, A.G., and Tailor, R., J. Chem. Soc., Perkin
Trans. 2, 1986, no. 12, p. S1.
4-Ethyl(allyl)-4,7-dihydro-s-triazolo[1,5-a]pyri-
midin-7-ones Xc and Xd were prepared similarly to
compounds Xa and Xb but isolated by column chro-
matography on silica gel, eluent chloroform methanol,
100:2.
6. Naumov, V.A. and Vilkov, L.V., Molekulyarnye struk-
tury fosfororganicheskikh soedinenii (Molecular Struc-
tures of Organophosphorus Compounds), Moscow:
Nauka, 1986, p. 319.
(1-Cyano-2-p-toluidinovinyl)triphenylphospho-
nium iodide (XI). A mixture of 0.01 mol of phos-
phonium salt I and 0.01 mol of p-toluidine in 30 ml
of acetonitrile was refluxed for 2 h, left for 1 h at 20
25 C, and the precipitate was filtered off and purified
by crystallization.
7. Johnson, A.W., Ylides and Imines of Phosphorus,
New York: Wiley, 1993, p. 48.
8. Winkley, M.W., Judd, G.F., and Robins, R.K., J. Hete-
rocycl. Chem., 1971, vol. 8, no. 2, p. 237.
9. Watkin, D.J., Prout, C.K., Carruthers, J.R., and Bettee-
ridge P.W., Crystals, vol. 10, Chemical Crystallog-
raphy Laboratory, Univ. of Oxford, 1996.
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