Reaction of N-phenyltriflamide with 1,2-dibromoethane and propargyl bromide. Unexpected cleavage of С–С and С–N bonds

Article abstract of DOI:10.1134/S1070428016080030

Reaction of N-phenyltriflamide with 1,2-dibromoethane under basic conditions in DMSO unexpectedly results in N-methyl-N-phenyltriflamide and 1,3-diphenylurea. The presumed reaction mechanism includes the formation of unstable intermediate disubstitution product TfN(Ph)CH₂CH2N(Ph)Tf that suffers the the С–С bond cleavage resulting in TfN(Me)Ph and N,N′-methanediylbis(N-phenyltriflamide). The latter reacts with K₂CO₃releasing two molecules of potassium triflinate and after hydrolysis of diphenylcarbodiimide PhN=C=NPh gives 1,3-diphenylurea. With propargyl bromide, N-phenyltriflamide affords N-propargyl-Nphenyltriflamide in high yield. The bromination of the latter results in a mixture of Z,E-isomers of N-(2,3-dibromoprop-2-en-1-yl)-N-phenyltriflamide which undergo dehydrobromination giving first N-(3-bromopropanedienyl)-N-phenyltriflamide and then the products of the C–N bond cleavage: N-phenyltriflamide and 3,3-dimethoxyprop-1-yne.

Full text of DOI:10.1134/S1070428016080030

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2016, Vol. 52, No. 8, pp. 1112–1117. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © B.A. Shainyan, Yu.S. Danilevich, 2016, published in Zhurnal Organicheskoi Khimii, 2016, Vol. 52, No. 8, pp. 1122–1127.
Reaction of N-Phenyltriflamide with 1,2-Dibromoethane
and Propargyl Bromide. Unexpected Cleavage
of С–С and С–N Bonds
B. A. Shainyan* and Yu. S. Danilevich
Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
*е-mail: bagrat@irioch.irk.ru
Received March 28, 2016
Abstract—Reaction of N-phenyltriflamide with 1,2-dibromoethane under basic conditions in DMSO
unexpectedly results in N-methyl-N-phenyltriflamide and 1,3-diphenylurea. The presumed reaction mechanism
includes the formation of unstable intermediate disubstitution product TfN(Ph)CH2CH2N(Ph)Tf that suffers the
the С–С bond cleavage resulting in TfN(Me)Ph and N,N'-methanediylbis(N-phenyltriflamide). The latter reacts
with K2CO3 releasing two molecules of potassium triflinate and after hydrolysis of diphenylcarbodiimide
PhN=C=NPh gives 1,3-diphenylurea. With propargyl bromide, N-phenyltriflamide affords N-propargyl-N-
phenyltriflamide in high yield. The bromination of the latter results in a mixture of Z,E-isomers of N-(2,3-
dibromoprop-2-en-1-yl)-N-phenyltriflamide which undergo dehydrobromination giving first N-(3-bromopro-
panedienyl)-N-phenyltriflamide and then the products of the C–N bond cleavage: N-phenyltriflamide and 3,3-
dimethoxyprop-1-yne.
DOI: 10.1134/S1070428016080030
Unsaturated derivatives of triflamide of general
formula TfNНR (Tf = CF3SO2) with substitutent R
containing one or more multiple bonds are interesting
both from the point of view of their synthetic potential,
and of possible tautomerism in these compounds. Until
recently, the family of triflamide derivatives and other
perfluoralkanesulfonamides was small and consisted
mostly of imines of the type RFSO2N=CHAr [1–5].
After unsuccessful attempt to obtain first vinyl
triflamide derivative by dehydro-bromination of
TfNHCH2CHBrPh that resulted in a substituted
piperazine [6], we were able to synthesize (E)-TfN
(Me)CH=CHPh from its methyl analog [7]. In
subsequent studies we synthesized a series of N-vinyl
[8, 9], N-allyl [10, 11], N-allenyl [12], N-propargyl
[13], and other highly unsaturated derivatives of
triflamide [14–17].
Aiming to extend the series of unsaturated
derivatives of triflamide we investigated in the present
study the reaction of N-phenyltriflamide with 1,2-
dibromoethane expecting to synthesize N,N'-ethane-1,2
-diylbis(N-phenyltriflamide) TfN(Ph)CH2CH2N(Ph)Tf
and to transform it into unsaturated derivatives TfN
(Ph)CH=CHN(Ph)Tf and/or TfN(Ph)C≡CN(Ph)Tf by
subsequent bromination–dehydrobromination. We also
investigated the reaction of N-phenyltriflamide with
propargyl bromide and explored the bromination–
dehydrobromination of the formed N-propargyl-N-
phenyltriflamide TfN(Ph)CH2C≡CH.
First we carried out the reaction of triflamide 1 with
1,2-dibromoethane 2 in DMSO in the presence of equi-
molar amount of KHCO3. However only intractable
mixture of compounds was obtained, in its 19F NMR
spectrum up to eight signals were present. We assumed
that the reason of complicated course of the reaction
was the presence of a free NH proton in the forming
salt CF3SO2NHK, so we replaced triflamide with its N-
phenyl-substituted analog 3 obtained by the reaction of
triflic anhydride with aniline, using the latter both as
the reactant and the solvent. The reaction of N-
As for disubstituted linear unsaturated derivatives of
triflamide, except for the synthesis of N,N'-hexa-2,4-diyne-
1,6-diylbis(triflamide) TfNHCH2C≡C–C≡CCH2NHTf
[14], we know only one study, in which the isomers of
N,N'-but-2-en-1,4-diylbis(triflamide) TfNHCH2CH=·
=CHCH2NHTf have been described [18].
1112

REACTION OF N-PHENYLTRIFLAMIDE WITH 1,2-DIBROMOETHANE AND PROPARGYL
1113
Scheme 1.
Me
O
K2CO3
_2KBr
2CF3SO2K
BrCH2CH2Br
H2O
CF3SO2NPh
3 CF3SO2NHPh
PhNHCNHPh
+
+
+
+
3
2
6
4
5
Scheme 2.
Ph
Ph
Ph
K2CO3
TfNKPh
_KBr
+
CF3SO2NCH2
CF3SO2NHPh
BrCH2CH2Br
CF3SO2NCH2CH2Br
CH2NSO2CF3
_KBr
3
2
7
8
Ph
Ph
_
CF3SO2NPh
2 K2CO3
H2O
5
PhN
C
NPh
CF3SO2NCH2NSO2CF3
4
+
_2CF3SO2K
[H+]
10
9
phenyltriflamide 3 with 1,2-dibromo-ethane 2 in
DMSO in the presence of K2CO3 proceeds smoothly
but with completely unexpected result. Two products
of the reaction were isolated: N-methyl-N-
phenyltriflamide 4 and 1,3-diphenylurea 5. As shown
in Scheme 1, the reaction may be equated assuming
that two molecules of N-phenyltriflamide potassium
salt react with one molecule of 1,2-dibromoethane, and
the third molecule is reduced to salt 6.
1Н NMR spectrum of the reaction mixture before
separation contains two triplet signals at 3.5 and
4.3 ppm with a spin-spin coupling constant of 6.6 Hz,
evidencing the formation of monosubstituted compound
7 (Scheme 2). Its further reaction with potassium salt
of amide 3 gives the product of disubstitution 8 that
decomposes under the action of the third molecule of
salt TfNKPh as shows the presence of a methyl group
in the spectrum of the reaction product 4. Further
elimination of two molecules of trifluormethanesul-
finic acid CF3SO2H from compound 9 in the form of
potassium triflinate results in diphenylcarbodiimide 10
that hydrolyses giving the final product, 1,3-diphenyl-
urea 5. Due to the presence of two triflamide residues
in molecule 9 the CH2 group becomes more acidic
which favors the elimination. The triflinate anion may
be oxidized to triflate under the action of the solvent
(DMSO). The formation of 1,3-diphenylurea 5 is
1
13
confirmed by the identity of its IR, H, and C NMR
spectra with the spectra of an authentic sample.
We tried to perform the reaction of N-phenyltrifla-
mide 3 with 1,2-dichloroethane in similar conditions,
however the reaction did not occur even at 10-hour
heating at 80°С: only the initial substrate 3 was recove-
red. Obviously it is the result of the lower nucleo-
fugality of the chlorine atom compared to bromine.
Unlike the reaction with 1,2-dibromoethane 2, N-
phenyltriflamide 3 is alkylated easily and in high
yields with propargyl bromide 11 in the presence of
potassium carbonate at room temperature providing a
new highly unsaturated derivative of triflamide, N-
propargyl-N-phenyltriflamide 12 (Scheme 3).
The bromination of alkyne 12 gives a mixture of Z-
and E-isomers of N-(2,3-dibromoprop-2-en-1-yl)-N-
Scheme 3.
Ph
K2CO3
CF3SO2N
12
CF3SO2NHPh HC
+
CCH2Br
11
_KBr
CH2C
CH
3
Scheme 4.
CF3SO2N(Ph)CH2
CF3SO2N(Ph)CH2
Br
H
Br2
12
C
C
C
C
+
CCl4, 70oC
Br
13-E
Br
13-Z
H
Br
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 8 2016

SHAINYAN, DANILEVICH
1114
Scheme 5.
_Br2
Br2
Br2
Br2
CF3SO2N(Ph)CH2CBr2CHBr2
12
Z-14
E-13
_Br2
14
Scheme 6.
MeONa
CF3SO2N(Ph)CH
_NaBr, MeOH
15
CF3SO2N(Ph)CH2
CBr
CHBr
C
CHBr
(Z+E)-13
H
OMe
CH
MeONa
MeOCH
C
CHBr
_
+
CF3SO2NHPh
CHBr
CF3SO2N
C
3
MeO
Ph
OMe
H
_
CH
_
C
CH
C
C
C
Br
MeO
_Br
H
OMe
MeO
16
phenyltriflamide TfN(Ph)CH2CBr=CHBr 13. No
diadduct is formed (Scheme 4).
while the Z-isomer is, probably, formed by debromina-
tion of the intermediate unstable adduct 14 (Scheme 5).
We previously demonstrated that the bromination
of N-propargyltriflamide gave a mixture of Z- and Е-
isomers of monoadduct in a ratio 24 : 76; the product
of dibromoination did not form even at excess of
bromine [16]. The formation of two isomers was
proved by the presence of two sets of signals from the
fragment СН2СBr=СHBr in 13C NMR spectrum and
two close lying signals of CF3 groups in 13C and 19F
spectra. The assignment of the signals to the Z- and Е-
isomers was performed by measuring the coupling
constants 3JC–H in the allyl fragment С–С=С–H (3.1 Hz
in Z- and 6.9 Hz in E-isomer).
Consequently, E-isomer is a kinetically controlled
reaction product, while Z-isomer is more stable
thermodynamically. The initial formation of E-isomer
is consistent with the rule of trans-addition, whereas
the higher stability of Z-isomer is not so obvious.
Quantum-chemical calculations by DFT/B3LYP/6-
311G(d,p) and MP2/6-311G(d,p) methods showed the
energy preference of Z-13-isomer compared to E-13-
isomer by 1.03 (DFT) and 1.17 kcal mol–1 (MP2). The
good consistency of the calculation results both with
each other, and with experimentally observed
prevalence of Z-isomer confirms the suggested
mechanism. The calculations also confirm the
instability of diadduct 14: although a local minimum
on the potential energy surface corresponds to
molecule 14, its formation from Z-isomer and bromine
molecule is endothermic by 11.8 kcal mol–1, while the
formation of Z-isomer itself from compound 12 and
bromine molecule is exothermic by 34.8 kcal mol–1.
Interesting results were obtained by monitoring the
isomeric composition at varying the reaction conditions.
With the deficiency of bromine, when conversion of
compound 12 did not exceed 30%, the ratio Z-13/E-13
1
measured with Н NMR method was 7 : 93. Adding
bromine and increasing the conversion to 85% this
ratio increases to 21 : 79, and the ratio attains 35 : 65 at
the full conversion. Further heating with bromine
excess changes this ratio in favor of Z-isomer till Z-13/
E-13 = 55 : 45 that then remains constant, showing the
reached equalibrium. Hence it may be concluded that
isomers Z-13 and E-13 are formed in different ways: the
E-isomer is formed by bromination of compound 12,
A higher stability of the Z-13 versus E-13 isomer is,
apparently, due to strong electron acceptor character of
the CF3SO2 group, since the MP2/6-311G calculated
for comparison energy difference between the Z- and Е-
isomers of N-(2,3-dibromoprop-2-en-1-yl)-N-me-
thylaniline МеN(Ph)CH2CBr=CHBr is as low as
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 8 2016

REACTION OF N-PHENYLTRIFLAMIDE WITH 1,2-DIBROMOETHANE AND PROPARGYL
1115
0.13 kcal mol–1, which is much smaller than the above
triflamides TfN(R)CH2CBr=CHR' is quite sensitive even
value of 1.17 kcal mol–1 for the isomers of compound 13.
to small structural variations. So, the reaction of N-ben-
zyl-N-(2-bromoallyl)triflamide TfN(Bn)CH2CBr=CH2
with 10-fold excess of sodium methylate ends at the
stage of formation of the corresponding allene TfN(Bn)·
CH=C=CH2 [11]. Unlike this, the reaction of compound
13 which with the deficiency of sodium methylate
gives similar allenyl product, in the presence of only
25% excess of the base goes further resulting in the
products of the N–C bond rupture 3 and 16. Evidently,
the effect of electronegative groups (Ph comparing to
Bn, and Br comparing to H) is small, but enough to
provide the bond rupture, especially in combination
with the subsequent substitution of the bromine atom.
The dehydrobromination of monoadducts Z-13 and
E-13 may result in either allenyl product TfN(Ph)·
CH=C=CHBr, or propargyl product TfN(Ph)CH2·
C≡CBr that are easy to distinguish by 1Н and 13С NMR
spectra, or to its mixture (Scheme 6). Actually, at
performing the reaction with a deficiency of sodium
methyloxide (about 1/3 of stoichiometric amount),
allene 15 was detected by the presence of two doublets
1
in H NMR spectrum at 7.06 (=CHBr) and 6.25 ppm
4
(NCH=), J 5.1 Hz. However at a small excess of
sodium methyloxide instead of elimination product of
allenyl or propargyl type unexpectedly products were
obtained of the rupture of the N–C bond: N-
phenyltriflamide 3 and 3,3-dimethoxyprop-1-yne 16.
These results may be explained in the framework of a
reaction mechanism including an intermediate
formation of 3-bromopropadienyl derivative 15 and its
subsequent fragmentation and bromine substitution
with the transition of the reaction center. The attack of
the methoxide ion in the last stage on the position 3 of
intermediate 1-bromo-3-methoxypropadiene is assisted
by the conjugation of the double С=С bond with
methoxy substituent that polarizes it in the direction
from the oxygen atom to the bromine atom. The last
stage as evident from Scheme 6 is similar to the well-
known mechanism of nucleophilic substitution SN2'.
Hence, an unusual direction of reaction of N-
phenyltriflamide with 1,2-dibromoethane resulting in
the rupture of C–C bond in the latter and in the
formation of N-methyl-N-phenyltriflamide and 1,3-
diphenylurea was discovered. A reaction mechanism
was suggested including the formation of unstable
disubstitution product TfN(Ph)CH2CH2N(Ph)Tf, its
decomposition under the action of salt molecule
TfNKPh, release of two molecules of trifluormethane-
sulfine acid as potassium salt from the formed N,N'-
methanediylbis(N-phenyltriflamide), and the final
stage of hydrolysis of diphenylcarbodiimide. The
reaction of N-phenyltriflamide with propargyl bromide
gives new unsaturated derivative of triflamide, N-
propargyl-N-phenyltriflamide that undergoes bromina-
tion giving a mixture of isomeric monoadducts which
are kinetically and thermodynamically controlled
products formed in different ways.
The formation of N-phenyltriflamide is confirmed
by practically full coincidence of 13C NMR spectrum
of reaction product formed by Scheme 6 with the
spectrum of authentic sample 3. The structure of 3,3-
13
13
dimethoxyprop-1-yne 16 is proved by 1H, C, and C
{1H} NMR spectra. The proton spectrum of compound
16 contains a singlet of two methoxy groups at 3.42
ppm (6H) and two doublets of one-proton intensity
each at 2.57 and 5.19 ppm (J 1.8 Hz), fully consistent
EXPERIMENTAL
IR spectra were recorded on a spectrophotometer
Bruker Vertex 70. 1H, 13C, and 19F NMR spectra were re-
gistered on a spectrometer Bruker DPX 400 at working
frequencies 400 (1Н), 100 (13С), and 376 (19F) MHz in
CDCl3 (if not indicated otherwise). Chemical shifts in
1H and 13C NMR spectra are reported with respect to
TMS, in 19F NMR spectra, with respect to with CFCl3.
Solvents were dried and purified before use by
standard methods.
13
with the published data [19]. C{1H} NMR spectrum
contains signals of methyl groups (d.d, 53.54 ppm,
J 143.5, 5.1 Hz), of the terminal acetylene carbon atom
(d, 74.50 ppm, J 252.8 Hz), another acetylene carbon
atom (s, 77.60 ppm), and of acetal methine carbon
atom (d.q, 92.67 ppm, J 169.6, 4.5 Hz) also in good
agreement with the published data [19] that
unambiguously proves the assumed structure and the
reaction mechanism.
Quantum-chemical calculations were performed
applying the software package GAUSSIAN09 [20]
by B3LYP or MР2 methods using the basis set
6-311G(d,p) with full optimization of geometry.
Considering the results of our previous inves-
tigations it may be concluded that the direction of
dehydrobromination of N-substituted N-(2-bromoallyl)-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 8 2016

SHAINYAN, DANILEVICH
1116
1
Reaction of triflamide with 1,2-dibromoethane.
1210, 1143, 1009, 951, 752, 695. Н NMR spectrum,
δ, ppm: 2.67 s (3H, CH3), 7.21–7.28 m (3H, Hm+p),
7.29–7.35 m (2H, Ho). 13С NMR spectrum (DMSO-
d6), δ, ppm: 39.87 (CH3), 119.92 q (CF3, J 323.1 Hz),
123.10 (Сm), 126.76 (Сp), 129.35 (Сo), 134.58 (Ci). 19F
NMR spectrum: δ –75.32 ppm. Found, %: С 40.43; H
3.20; F 23.65; N 5.70; S 13.09. C8H8F3NO2S.
Calculated, %: C 40.17; H 3.37; F 23.83; N 5.86; S
13.40.
To a solution of 0.5 g of triflamide in 10 mL of water
was added while stirring a solution of 0.3 g of K2CO3
in 10 mL of water, the mixture was stirred for 30 min,
evaporated at a reduced pressure, the residue was dried
in a vacuum. To the obtained salt TfNHK was added
20 mL of DMSO and 0.31 g (0.14 mL) of 1,2-dibro-
moethane, the reaction mixture was stirred for 6 h,
washed with water to remove DMSO, extracted with
chloroform. The extract was dried with MgSO4,
evaporated in a vacuum, the residue was analyzed by
N-Propargyl-N-phenyltriflamide (11). To 20 mL
of DMSO was added 3.73 g of N-phenyltriflamide and
1.97 g (1.5 mL) of propargyl bromide. After the
dissolution of N-phenyltriflamide 4 g of K2CO3 was
added, the formed suspension was stirred for 6 h at
room temperature, poured in water, extracted with
chloroform, the extract was washed with water, dried
with MgSO4, evaporated, the residue was distilled in a
vacuum. Yield 3.86 g (88%), boiling point 74°С
(0.6 mm Hg). IR spectrum (thin layer), ν, cm–1: 3298
(≡C–H), 3069, 3045, 2985, 2931 (C–H), 2131 (C≡C),
1593 (arom), 1492, 1396, 1311, 1196, 1146, 1076,
1032, 881, 770. 1Н NMR spectrum, δ, ppm: 2.41 t (1H,
≡CH, J 2.2 Hz), 4.54 d (2H, CH2, J 2.2 Hz), 7.46 s
(5H, Ph). 13С NMR spectrum, δ, ppm: 43.83 (NCH2),
75.45 (CH≡), 77.02 (–C≡), 120.53 q (CF3, J 322.4 Hz),
129.67 (Сo), 130.09 (Сm), 130.22 (Сp), 137.32 (Ci). 19F
NMR spectrum: δ –74.06 ppm. Found, %: С 45.43; H
2.97; F 22.02; N 5.60; S 11.81. C10H8F3NO2S.
Calculated, %: C 45.63; H 3.06; F 21.65; N 5.32; S
12.18.
1
the NMR method. In H NMR spectrum several
signals of NH groups are present in the region of 7.8–
13
8.7 ppm and a broad signal at 3.3–3.9 ppm, C NMR
spectrum contains 5–6 signals in the region of 40–
54 ppm and few quartets of CF3 groups at 120 ppm,
and 19F NMR spectrum contains 7–8 signals in the
region of –78 to –73 ppm. It was impossible to isolate
individual compounds by column chromatography.
Reaction of N-phenyltriflamide with 1,2-dibro-
moethane. To 15 mL of aniline while stirring was
added dropwise 4 g (2,4 mL) of trifluoromethane-
sulfonic anhydride, the mixture was stirred for 30 min,
acidified with 10% HCl, the precipitate was filtered
off, washed with water, dried and sublimated in a
vacuum to get 2.9 g (90%) of N-phenyltriflamide 3 as
a white powder (δF –75.30 ppm).
Compound 3 was dissolved in 20 mL of DMSO,
1.2 g (0.55 mL) of 1,2-dibromoethane and 4 g of freshly
calcined K2CO3 was added, the reaction mixture was
stirred for 6 h, then poured in water. The obtained
compound after filtering and drying was identified as
1,3-diphenylurea (5), mp 240°C. IR spectrum (KBr),
ν, cm–1: 3327, 3287 (NH), 3035–3194 (CH), 1648,
1596, 1555 (arom.), 1497, 1445, 1314, 1298, 1233,
894, 755, 699. 1Н NMR spectrum (DMSO-d6), δ, ppm:
6.97 t (1H, Hp, J 7.0 Hz), 7.28 d (2H, Hm, J 7.4 Hz),
7.46 d (2H, Ho, J 7.7 Hz), 8.65 s (1H, NH). 13С NMR
spectrum (DMSO-d6), δ, ppm: 118.40 (Сo), 121.97
(Сp), 128.82 (Сm), 139.71 (Ci), 152.69 (C=O). All
spectra are identical to the spectra of an authentic
sample.
N-(2,3-dibromoprop-2-en-1-yl)-N-phenyltrifluo-
romethanesulfonamide (13). To 0.5 g (1.9 mmol) of
reagent 11 in 20 mL of anhydrous CCl4 was added
0.31 g (0.19 mmol) of bromine, and the mixture was
stirred for 8 h at 70°С, then more 0.05 mL of bromine
was added and the stirring while heating was continued
for 6 h more. The solvent was removed in a vacuum.
The residue contained the mixture of isomers Z,Е-13.
Found, %: C 27.83; H 1.75; (Br+S) 45.46; F 14.08; N
3.17. C10H8Br2F3NO2S. Calculated, %: C 28.39; H
1.91; Br 37.78; F 13.47; N 3.31; S 7.58.
1
Z-13-Isomer. Н NMR spectrum, δ, ppm: 4.67 s
The mother liquor was extracted with chloroform,
the extract was washed with water to remove the
remnants of DMSO, dried with MgSO4, evaporated,
the residue was distilled to give N-methyl-N-
phenyltriflamide (4). Yield 0.5 g (50%), boiling point
63°С (0.8 mm Hg). IR spectrum (thin layer), ν, cm–1:
3100–2740 (CH), 1599 (arom), 1496, 1436, 1379,
(2Н, СН2), 6.73 s (1Н, =СНBr), 7.40–7.45 m (5Н, Ph).
13С NMR spectrum, δ, ppm: 60.35 t.d (NCH2, J 145.9,
3.1 Hz), 113.87 d.t (=CHBr, J 194.1, 5.4 Hz), 118.77 d
(CBr=, J 22.1 Hz), 120.27 q (СF3, JСF 324.0 Hz),
129.10 d (Сm, J 162.9 Hz), 129.49 d (Сp, J 165.1 Hz),
129.83 d (Сo, J 162.9 Hz), 135.92 (Сi). 19F NMR
spectrum: δ –73.25 ppm.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 8 2016

REACTION OF N-PHENYLTRIFLAMIDE WITH 1,2-DIBROMOETHANE AND PROPARGYL
1117
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E-13-Isomer. Н NMR spectrum, δ, ppm: 4.87 s
(2Н, СН2), 6.56 s (1Н, =СНBr), 7.40–7.45 m (5Н, Ph).
13С NMR spectrum, δ, ppm: 55.85 t.d (NСН2, J 145.5,
6.9 Hz), 109.31 d.t (=СНBr, J 202.6, 3.9 Hz), 120.33 q
(СF3, JСF 323.8 Hz), 125.81 d (CBr=, J 13.3 Hz),
129.05 d (Сm, J 160.0 Hz), 129.44 d (Сp, J 163.3 Hz),
129.75 d (Сo, J 162.9 Hz), 135.48 (Сi). 19F NMR
spectrum: δ –73.20 ppm.
Dehydrobromination of the mixture of Z- and E-
isomers (13). a. With a deficit of sodium methylate. To
solution of 0.3 g (0.7 mmol) of compound 13 in 10 mL
of methanol was added 10 mg (0.18 mmol) of sodium
methylate, the mixture was stirred for 4 h at 40°C,
filtered, the solvent was removed, the residue was
analyzed by NMR method.
b. With excess of sodium methylate. To a solution of
2.5 g (5.9 mmol) of compound 13 in 30 mL of
methanol was added 0.4 g (7.4 mmol) of sodium
methylate, the mixture was stirred for 4 h at 40°C,
filtered, the solvent was evaporated, the residue was
dissolved in water and extracted with chloroform. The
extract was dried with MgSO4, the solvent was
removed, the residue was analyzed by NMR method.
ACKNOWLEDGMENTS
The authors are grateful to Candidate of Chemical
Science I.A. Ushakov for assistance in interpreting the
NMR spectra.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 8 2016