Ku¨tt et al.
5
5
o-CF3, 6F); 13C NMR (100.6 MHz, CDCl3) δ: 134.5 (qm, 2JC-F
)
) 17.2 Hz, p-CF3, 3F), -53.25 (qq, JF-F ) 17.2, JF-F ) 17.2
Hz, m-CF3, 6F), -58.89 (q, 5JF-F ) 17.2 Hz, o-CF3, 6F); 13C NMR
(90.5 MHz, CDCl3) δ: 148.3 (s, i-CAr), 136.8 (qm, 2JC-F ) 32 Hz,
m-CAr), 122.2 (q, 1JC-F ) 168 Hz, m-CF3), 121.3 (q, 1JC-F ) 262.7
2
35.6 Hz, o- or m-CAr), 134.4 (qm, JC-F ) 37.1 Hz, o- or m-CAr),
3
134.0 (m, p-CAr), 131.1 (sept, JC-F ) 6.4 Hz, i-CAr), 121.3 (q,
1
1JC-F ) 276.2 Hz, o-CF3), 121.2 (q, JC-F ) 278.0 Hz, p-CF3),
1
2
120.9 (q, JC-F ) 277.6 Hz, m-CF3); EIMS (% relative intensity,
Hz, p-CF3), 119.6 (qm, JC-F ) 34 Hz, p- or o-CAr), 118.3 (qm,
ion) m/z: 418 (24%, M+), 399 (75%, M+ - F), 394 (100%, M+ -
CF3), 330 (15%, M+ - CF3 - F), 299 (8%, M+ - CF3 - CF2),
280 (12%, M+ - 2CF3).
2JC-F ) 39 Hz, p- or o-CAr), 118.1 (q, JC-F ) 272 Hz, o-CF3);
1
EIMS m/z (% relative intensity, ion): 433 (100%, M+), 414 (95%,
M+ - F), 394 (20%, M+ - 2F), 324 (85%, M+ - CF3); HRMS-
EI m/z: M+ calcd for C11H2NF15, 432.99417; found, 432.99501.
Pentakis(trifluoromethyl)chlorobenzene (4). Method A. For
pregeneration of CF3Cu, CuBr (0.16 mol, 23.5 g), CF3SiMe3 (0.14
mol, 20 mL), KF (0.14 mol, 8.0 g), and DMF (100 mL) were mixed
as described in general procedure. For stabilization of CF3Cu NMP
(20 mL) was applied. To the pregenerated CF3Cu species were
consequently added pentaiodochlorobenzene (0.021 mol, 15.9 g)
(for synthesis see Supporting Information) and NMP (80 mL). The
mixture was stirred at 0-20 °C for 24 h. The solvents with volatile
4 were distilled and the distillate was diluted with water (120 mL)
and extracted with pentane (3 × 200 mL). The pentane phase was
washed with water (3 × 100 mL), and dried over MgSO4. After
removal of pentane in vacuo at room temperature, the raw product
was recrystallized from pentane or methanol to give 4. Yield 81%
(17.5 mmol, 7.9 g), mp 146-148 °C.
Method B. Compound 1 (0.68 mmol, 0.30 g), POCl3 (1.5 mL),
PCl5 (ca 50 mg) and dry pyridine (0.3 mL) were mixed under
nitrogen. After stirring for 2 h at 80 °C, volatiles were removed in
vacuo at room temperature and the residue was extracted several
times with pentane (25 mL). Pentane was removed in vacuo to get
4 as white solid. Yield 84% (0.57 mmol, 0.26 g), mp 131-133 °C.
19F NMR (188.3 MHz, CDCl3) δ: -51.64 (sept, 5JF-F ) 17.2 Hz,
It is known49 that reaction of (CF3)3C6 with liquid ammonia leads
to conversion of CF3 group into CN groups. Apparently, this
transformation accounts for reduced yield of 5. The compound 5
is easily separated from less volatile cyano-derivatives by sublima-
tion.
Pentakis(trifluoromethyl)toluene (6). For pregeneration of CF3-
Cu according to general procedure, CuBr (93.4 mmol,13.4 g), CF3-
SiMe3 (70.3 mmol, 10 mL), KF (70.6 mmol, 4.1 g), DMF (45 mL)
and NMP (6 mL) were mixed. Pentaiodotoluene (11.8 mmol, 8.5
g) and NMP (40 mL) were added to the solution of pregenerated
CF3Cu, and the reaction mixture was stirred at 65-70 °C for 14 h.
After cooling to 0 °C the colorless crystals of the product were
filtered and washed with methanol to remove Cu-salts. Yield 41%
(4.9 mmol, 2.1 g), mp 166-167 °C; 1H NMR (400.1 MHz, CDCl3)
δ: 2.74 (sept, JH-F ) 3.3 Hz, CH3, 3H); 19F NMR (188.3 MHz,
5
DMSO-d6) δ: -52.35 (sept, 5JF-F ) 17.6 Hz, p-CF3, 3F), -53.51
(qq, 5JF-F ) 17.6, 5JF-F ) 17.6 Hz, m-CF3, 6F), -55.46 (qq, 5JF-F
) 17.6, 5JH-F ) 3.3 Hz, o-CF3, 6F); 13C NMR (100.6 MHz, CDCl3)
2
δ: 145.7 (m, i-CAr); 135.5 (qm, JC-F ) 33.1 Hz, o- or m-CAr),
2
2
134.6 (qm, JC-F ) 36.0 Hz, o- or m-CAr), 131.3 (qm, JC-F
)
5
5
p-CF3, 3F), -52.93 (qq, JF-F ) 17.2, JF-F ) 17.2 Hz, m-CF3,
1
36.8 Hz, p-CAr), 122.0 (q, JC-F ) 277.9 Hz, o- or m-CF3), 121.6
6F), -57.34 (q, 5JF-F ) 17.2 Hz, o-CF3, 6F); 13C NMR (90.5 MHz,
1
1
(q, JC-F ) 276.9 Hz, p-CF3), 121.3 (q, JC-F ) 277.7 Hz, o- or
2
CDCl3) δ: 140.2 (s, i-CAr), 135.7 (qm, JC-F ) 82 Hz, m-CAr),
4
m-CF3), 20.4 (hept, JC-F ) 5.0 Hz, CH3); EIMS m/z (% relative
2
2
135.0 (qm, JC-F ) 52 Hz, o-CAr), 131.5 (qm, JC-F ) 82 Hz,
intensity, ion): 432 (31%, M+), 413 (100%, M+ - F), 363 (93%,
M+ - CF3); HRMS-EI m/z: M+ calcd for C12H3F15, 431.99893;
found, 432.00033.
1
1
p-CAr), 121.4 (q, JC-F ) 306 Hz, p-CF3), 121.1 (q, JC-F ) 272
Hz, o-CF3), 120.7 (q, 1JCF ) 263 Hz, m-CF3); EIMS m/z: 452 (57%,
M+), 433 (54%, M+ - F), 417 (12%, M+ - Cl), 398 (13%, M+ -
F - Cl), 383 (100%, M+ - CF3), 367 (11%, M+ - Cl - CF2),
349 (20%, M+ - Cl - CF3), 333 (14%, M+ - CF3 - CF2), 314
(9%, M+ - 2CF3); HRMS-EI m/z: M+ calcd for C11F15Cl,
451.94430; found, 451.94430.
Tetraethylammonium Dicyano[pentakis(trifluoromethyl)-
phenyl]methanide (7a‚Et4N+). A magnetically stirred solution of
(1.5 mmol, 0.1 g) of malononitrile in of dry THF (1 mL) kept at
-78 °C was consequently treated with NaH (2.5 mmol, 0.06 g) in
dry THF (5 mL) and 4 (1.1 mmol, 0.5 g, dissolved in 1 mL of dry
THF). The mixture turned yellow. After warming up to room
temperature the mixture turned dark red. The solution was ad-
ditionally stirred for additional 4 h. 19F NMR spectra indicated the
formation of the sodium salt 7a‚Na+. The solution was filtrated to
remove NaCl. From filtrate all the volatiles were removed in vacuo.
The residue was dissolved in water and Et4NCl (1.1 mmol, 0.18 g)
was added to the solution. A dark oily substance formed, which
turned solid after cooling the solution to 0 °C. Removing of water
via filtration followed by recrystallization from EtOH/water mixture
(1:7) afforeded the target product 7a‚Et4N+. Yield: 67% (0.65
Hydrolysis of 4. Compound 4 (0.3 g, 0.66 mmol) was dissolved
in dimethoxyethane (DME, 7.5 mL) and water (ca 1.5 mL) was
added under stirring. At 0 °C NaOH solution (0.66 mmol, 0.8 mL;
containing 0.2 g NaOH in 6 mL 1:1 mixture of DME/water) was
added. The solution became yellowish and 19F NMR spectrum
showed besides the starting 4 and 1a‚Na+ a lot of minor peaks.
The mixture was stirred at room temperature for 2 days, and then
the same NaOH solution (0.8 mL) was added. The solvents were
removed in vacuo and the dry residue (0.3 g) was extracted twice
with petrol ether to remove the unreacted 4. The washed residue
was dissolved in diethyl ether and transferred to the sublimator.
Ether was removed in vacuo and the residue was sublimed in static
vacuum from concd H2SO4 (1 mL) to obtain 1. Yield: 38% (0.23
mmol, 0.10 g). The data of product corresponds to the data of 1
obtained from trifluoromethylation of C6I6 described in general
procedure.
1
mmol, 0.40 g), mp 90-93 °C, H NMR (400.1 MHz, acetone-d6)
3
3
δ: 3.50 (q, JH-H ) 7.3 Hz, CH2, 8H), 1.40 (qt, JH-H ) 7.3 Hz,
3JH-14N ) 1.8 Hz, CH3, 12H); 19F NMR (188.3 MHz, CD3CN) δ:
5
5
-47.59 (sept, JF-F ) 16.6 Hz, p-CF3, 3F), -49.30 (q, JF-F
)
5
5
16.6 Hz, o-CF3, 6F), -51.89 (qq, JF-F ) 16.6, JF-F ) 16.6 Hz,
m-CF3, 6F); 13C NMR (100.6 MHz, acetone-d6) δ: 152.0 (m, i-CAr),
131.6 (qm, 2JC-F ) 34.9 Hz, m-CAr), 125.0 (q, 1JC-F ) 271.1 Hz,
Pentakis(trifluoromethyl)aniline (5). A solution of 4 (1.80
mmol, 0.78 g) in 20 mL of dichloromethane was placed in a
pressure tube with Teflon stopcock and cooled with liquid nitrogen
and filled on a vacuum line with ca. 5 mL of ammonia. The
resulting solution was kept at -30 to -40 °C for 24 h and then
stirred at room temperature for 40 h. The 19F NMR spectra of the
solution indicated presence of 5, a small amount of 4 and some
impurities. The solution was filtered to remove ammonium chloride
(NH4Cl). The solvent was distilled off in vacuum from a cooled
flask (-20 °C, to prevent sublimation of 5) to afford the target
product (0.46 mmol, 0.20 g) as a yellow solid. Yield 28%, mp 93-
95 °C (lit.12 115 °C). 1H NMR (200.1 MHz, CDCl3) δ: 5.61 (br s,
1
1
p-CF3), 123.5 (q, JC-F ) 275.9 Hz, m-CF3), 122.9 (q, JC-F
)
2
273.5 Hz, o-CF3), 116.6 (s, CN), 107.3 (qm, JC-F ) 36.7 Hz,
p-CAr), 105.4 (qm, 2JC-F ) 35.9 Hz, o-CAr), 69.6 (s, C(CN)2), 53.1
(t, 1JC-14N ) 3.0 Hz, CH2), 7.7 (s, CH3); HRMS-ESI m/z: M- calcd
for C14N2F15, 480.98270; found, 480.98264; Et4N+ calcd for
C8H20N, 130.15902; found, 130.15968.
Attempts to obtain the free acid 7 by sublimation of 7a‚Et4N+
from concd H2SO4 were unsuccessful. GC-MS measurement of the
(49) Yagupolskii, L. M.; Lukmanov, V. G.; Boiko, V. O.; Alekseeva,
L. A. Zh. Org. Khim. 1977, 11, 2388-2391.
5
NH2, 2H); 19F NMR (188.3 MHz, CDCl3) δ: -50.98 (sept, JF-F
2618 J. Org. Chem., Vol. 73, No. 7, 2008