REACTION OF N-PHENYLTRIFLUOROMETHANESULFONAMIDE WITH CARBODIIMIDES
397
metrical carbodiimide 5 was not detected in the reac-
tion mixture, presumably because of its low concen-
tration and the lack of characteristic signals.
of 1, 0.41 g (2 mmol) of 2, and 5–10 mol % of CuCl in
2 mL of methylene chloride was stirred for 5 days
at room temperature. Trifluoromethanesulfonamide,
0.30 g (2 mmol), was added to the resulting solution,
and the mixture was stirred for 6 days and evaporated
under reduced pressure. The residue (1.15 g) was
subjected to vacuum sublimation (0.08 mm Hg) on
a boiling water bath to isolate 0.26 g a mixture of 4
and 1 at a ratio of 1.3:1 (19F NMR). The unsublimed
material was purified by column chromatography
(hexane–ethyl acetate, 5:1). Yield of 6 0.50 g (72%),
white powder, mp 96°C. IR spectrum, ν, cm–1: 3333,
3251, 2934, 2858, 1594, 1572, 1364, 1312, 1206,
N-Phenyltrifluoromethanesulfonamide 1 failed to
react with N,N′-diphenylcarbodiimide (3) regardless of
the solvent nature. When the reaction was carried out
in acetonitrile, we isolated the hydrolysis product of 3,
N,N′-diphenylurea, whereas N-trifluoromethanesul-
fonyl-N′,N″-diphenylguanidine was isolated from the
reaction mixture in methylene chloride after addition
of trifluoromethanesulfonamide. It should be noted
that N-trifluoromethanesulfonyl-N′,N″-diphenylguani-
dine was not formed in the reaction of N,N′-diphenyl-
carbodiimide with trifluoromethanesulfonamide [1].
1
1112, 1065, 603. H NMR spectrum, δ, ppm: 8.81 br.s
(1H, NHPh), 7.55–7.46 m (3H, Ph), 7.27–7.25 m (2H,
Ph), 5.01 br.s (1H, NHCy), 3.95 br.s (1H, NCH), 1.97–
1.95 m (2H, CH2), 1.67–1.63 m (3H, CH2), 1.42–
1.39 m (3H, CH2), 1.18–1.13 m (2H, CH2). 13C NMR
spectrum, δC, ppm: 154.87 (C=N), 133.82, 130.52,
128.69, 126.21, 120.16 q (CF3, J = 322.5 Hz),
50.78, 32.43, 24.97, 24.32. 19F NMR spectrum:
δF –78.53 ppm. Found, %: C 48.85; H 5.47; F 15.84;
N 12.07; S 10.03. C14H18F3N3O2S. Calculated, %:
C 48.13; H 5.19; F 16.31; N 12.03; S 9.18.
Reaction of N-phenyltrifluoromethanesulfon-
amide (1) with N,N′-dicyclohexylcarbodiimide (2)
in acetonitrile. A mixture of 0.45 g (2 mmol) of 1,
0.40 g (2 mmol) of 2, and 5–10 mol % of CuCl in
4 mL of acetonitrile was stirred for 3 h at room tem-
perature and left overnight. The precipitate of dimer 7,
0.22 g (25%) was filtered off, and the filtrate was
evaporated under reduced pressure (water-jet pump).
The residue was 0.56 g of a mixture of 1, 4, and 5. The
yield of 7 in the absence of CuCl was 22%. When the
reactant ratio 1:2 was 1:3 [0.1 g (0.5 mmol) of 1 and
0.30 g (1.5 mmol) of 2 in 2 mL of MeCN], the yield
of 7 was 0.23 g (77%). Colorless crystals, mp 115–
120°C; published data [18]: mp 115–118°C.
Thus, we have revealed a substituent exchange
reaction between N,N′-dicyclohexylcarbodiimide and
N-phenyltrifluoromethanesulfonamide in methylene
chloride with the formation of N-cyclohexyltrifluoro-
methanesulfonamide and N-cyclohexyl-N′-phenyl-
carbodiimide. Addition of the latter to trifluoro-
methanesulfonamide gives unsymmetrical N-cyclo-
hexyl-N′-phenyl-N″-trifluoromethanesulfonylguani-
dine. The main direction of the reaction of N,N′-dicy-
clohexylcarbodiimide with N-phenyltrifluoromethane-
sulfonamide in acetonitrile is dimerization of the
former, whereas substituent exchange is a minor
pathway.
Reaction of N-phenyltrifluoromethanesulfon-
amide (1) with N,N′-dicyclohexylcarbodiimide (2)
in methylene chloride. A mixture of 0.45 g (2 mmol)
of 1, 0.41 g (2 mmol) of 2, and 5–10 mol % of CuCl in
2 mL of methylene chloride was stirred for 5 days at
room temperature. The precipitate of CuCl was filtered
off, and the filtrate was evaporated. According to the
19F NMR data, the yield of 4 was 77%. The yield of 4
increased to 86% when the reaction mixture was
subjected to microwave irradiation for 3 min. Vacuum
sublimation of the residue at 100°C (0.08 mm Hg)
gave 0.46 g of a mixture of 4 and 1 at a ratio of 8:1.
The unsublimed residue containing compound 5
(0.31 g) was used to obtain guanidine 6.
The IR spectra were recorded on a Bruker Vertex
70 spectrometer. The NMR spectra were recorded on
a Bruker DPX-400 spectrometer at 400 (1H), 100 (13C),
or 376 MHz (19F) from solutions in CDCl3; the
chemical shifts were measured relative to the residual
proton and carbon signals of the solvent or CCl3F
(19F). The progress of reactions was monitored by TLC
on Silufol UV 254 plates.
N-Cyclohexyltrifluoromethanesulfonamide (4).
Yield 100%, colorless crystals, mp 49–50°C. The
1H and 13C NMR spectra coincided with those given in
[10]. 19F NMR spectrum: δF –77.94 ppm.
N-Cyclohexyl-N′-phenylcarbodiimide (5). Yield
ACKNOWLEDGMENTS
1
95%, colorless viscous material. The IR and H and
13C NMR spectra coincided with those given in [11].
This study was performed using the facilities of the
Baikal Joint Analytical Center (Siberian Branch,
Russian Academy of Sciences).
N-Cyclohexyl-N′-phenyl-N″-trifluoromethane-
sulfonylguanidine (6). A mixture of 0.45 g (2 mmol)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 55 No. 3 2019