Organometallics
Article
°C. After the mixture was stirred for a further 30 min at −78 °C, 2,2,2-
trifluoro-N,N-dimethylacetamide (7.2 mL, 64.0 mmol) was slowly
added over 1 min at −78 °C. The mixture was cooled to below −80
°C, and then the reaction mixture was warmed to room temperature.
The reaction mixture was quenched with H2O (75 mL) and then
extracted with AcOEt (150 mL × 5). The organic fractions were
combined and dried over Na2SO4. The solvent was removed under
reduced pressure. The crude product was purified by Kugelrohr
distillation (120 °C, 140 Pa). The target product was obtained as a
brownish white powder in 54% yield. The product was contaminated
Kugelrohr distillation (240 °C, 170 Pa). The desired product was
obtained as a yellow powder in 43% yield. The product was
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contaminated with traces of an unknown impurity. H NMR (400
MHz, CDCl3): δ (ppm) 1.42 (s, 9H), 2.06 (s, 6H), 2.08 (s, 3H), 6.56
(s, 2H), 6.76 (d, 1H, 3JHH = 7.4 Hz), 7.30 (m, 1H), 7.52 (t, 1H, 3JHH
=
8.1 Hz), 7.82 (m, 1H), 8.21 (d, 1H, 3JHH = 7.9 Hz), 8.40 (d, 1H, 3JHH
= 7.9 Hz), 8.64 (m, 1H). 13C{1H} NMR (100 MHz, CDCl3): δ (ppm)
18.39, 20.72, 29.13, 40.52, 119.69, 121.17, 121.55, 123.89, 125.48,
128.26, 131.60, 136.30, 137.10, 149.18, 155.93, 156.09 (two signals of
aromatic carbons were not assignable due to coincident signals). GC-
MS (EI): 300 (100).
1
with traces of an unknown impurity. H NMR (400 MHz, CDCl3): δ
(ppm) 7.38 (m, 1H), 7.87 (qd, 1H, 5JHF = 1.6 and 3JHH = 7.8 Hz), 8.05
(t, 1H, 3JHH = 7.8 Hz), 8.17 (dd, 1H, 3JHH = 0.9 and 7.8 Hz), 8.54 (bd,
N-(2,2,2-Trifluoro-[2,2′-bipyridin-6-yl]ethylidene)-2,4,6-tri-
methylbenzenamine (7). The compound was prepared according to
the published procedure with some modifications.21 A mixture of
2,4,6-trimethylaniline (0.43 mL, 3.03 mmol), 3 (0.64 g, 2.53 mmol),
and p-toluenesulfonic acid monohydrate (14.6 mg, 0.08 mmol) in
toluene (6.4 mL) was heated to reflux temperature (Dean−Stark trap).
After the mixture was cooled to room temperature, the solvent was
removed under reduced pressure. The resulting oil was purified by
Kugelrohr distillation (200 °C, 200 Pa). The desired product was
obtained as a yellow powder in 79% yield. 1H NMR (400 MHz,
CDCl3): δ (ppm) 1.98 (s, 6H), 2.21 (s, 3H), 6.76 (s, 2H), 7.12 (d, 1H,
1H, 3JHH = 7.8 Hz), 8.71 (bt, 1H, 3JHH = 5.8 Hz), 8.77 (dd, 1H, 3JHH
=
0.7 and 8.2 Hz). 13C{1H} NMR (100 MHz, CDCl3): δ (ppm) 92.20
2
(q, JCF = 32.59 Hz), 121.66, 124.72, 124.77, 125.98, 137.39, 138.28,
2
147.92, 149.31, 154.56, 156.22, 180.78 (q, JCF = 34.05 Hz). GC-MS
(EI): 252 (36), 183 (20), 155 (100).
2,2-Dimethyl-1-[2,2′-bipyridin-6-yl]-1-propanone (4). The
compound was prepared according to the published procedure with
some modifications.20 To a suspension of sodium hydride (7.80 g, 195
mmol) in THF (550 mL) below 0 °C was added a solution of 2 (4.29
g, 21.7 mmol) in THF (43.0 mL) dropwise. The reaction mixture was
warmed to room temperature and stirred for 3 h before recooling to 0
°C. Iodomethane (13.5 mL, 217 mmol) was added dropwise, and the
reaction mixture was stirred at room temperature overnight. Excess
sodium hydride was quenched with H2O (70.0 mL) and AcOEt (70.0
mL). The organic fraction was collected and dried over Na2SO4. The
solvent was removed under reduced pressure. NMR examination of
the crude product showed that it was a mixture of tri- and dialkylated
ketones. This crude material was resubjected to the initial reaction
conditions, first by dropwise addition to a suspension of sodium
hydride (7.80 g, 195 mmol) in THF (550 mL) below 0 °C and then,
after stirring at room temperature, iodomethane (13.5 mL, 217 mmol)
was added and stirring was continued overnight. The reaction mixture
was quenched following the workup described above, to furnish the
trialkylated ketone. The crude product was purified by Kugelrohr
distillation (150 °C, 180 Pa). The target product was obtained as a
yellow oil in 79% yield. The product was contaminated with traces of
an unknown impurity. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.55 (s,
3
3JHH = 7.6 Hz), 7.31 (m, 1H), 7.74 (m, 2H), 8.07 (d, 1H, JHH = 8.1
Hz), 8.40 (d, 1H, 3JHH = 8.0 Hz), 8.63 (br, 1H). 13C{1H} NMR (100
MHz, CDCl3): δ (ppm) 17.91, 20.82, 121.28, 121.77, 122.20, 123.10,
124.32, 124.48, 128.84, 133.61, 137.07, 137.49, 143.48, 147.92, 149.14,
155.18, 156.17 (One signal was not assignable due to coincident
signal). Anal. Calcd for C21H18F3N3: C, 68.28; H, 4.91; N, 11.38.
Found: C, 68.16; H, 5.00; N, 11.42. GC-MS (EI): 349 (37), 329 (18),
310 (16), 300 (100).
N-(1-[2,2′-Bipyridin-6-yl]ethylidene)-2,6-diisopropylbenzen-
amine (8). The compound was prepared according to the published
procedure with some modifications.19 A mixture of 2,6-diisopropylani-
line (2.11 mL, 10.1 mmol), 2 (2.00 g, 10.1 mmol), and formic acid (5
drops) in MeOH (20.0 mL) was heated to reflux temperature. After
the mixture was cooled to room temperature, the yellow solid was
collected by filtration and washed with MeOH (10.0 mL × 2). The
target product was obtained as a yellow powder in 88% yield. 1H NMR
3
(400 MHz, CDCl3): δ (ppm) 1.16 (d, 12H, JHH = 6.8 Hz), 2.33 (s,
3H), 2.79 (sept, 2H, 3JHH = 6.6 Hz), 7.11 (m, 1H), 7.18 (m, 2H), 7.34
(m, 1H), 7.85 (m, 1H), 7.95 (t, 1H, 3JHH = 7.9 Hz), 8.40 (bd, 1H, 3JHH
= 7.3 Hz), 8.55 (bt, 2H, 3JHH = 7.9 Hz), 8.71 (bd, 1H, 3JHH = 4.4 Hz).
13C{1H} NMR (100.4 MHz, CDCl3): δ (ppm) 17.67, 23.07, 23.36,
3
9H), 7.34 (dd, 1H, JHH = 4.9 and 7.3 Hz), 7.86 (m, 1H), 7.93 (m,
3
3
2H), 8.41 (d, 1H, JHH = 8.2 Hz), 8.56 (dd, 1H, JHH = 2.8 and 6.4
Hz), 8.69 (d, 1H, 3JHH = 5.1 Hz). 13C{1H} NMR (100 MHz, CDCl3):
δ (ppm) 27.83, 40.29, 121.17, 123.31, 123.83, 124.10, 137.16, 137.92,
28.42, 121.22, 121.32, 122.07, 123.67, 123.94, 135.97, 137.02, 137.54,
146.69, 149.33, 155.04, 155.80, 156.21, 167.19. Anal. Calcd for
C24H27N3: C, 80.63; H, 7.61; N, 11.75. Found: C, 81.02; H, 7.70; N,
11.71. GC-MS (EI): 357 (20), 342 (67), 300 (19), 202 (72), 183 (27),
170 (22), 157 (100).
2
149.36, 149.17, 153.94, 154.41, 155.81 (q, JCF = 34.05 Hz). GC-MS
(EI): 212 (17), 197 (9), 156 (100).
N-(1-[2,2′-Bipyridin-6-yl]ethylidene)-2,4,6-trimethylbenzen-
amine (5). The compound was prepared according to the published
procedure with some modifications.19 A mixture of 2,4,6-trimethylani-
line (1.45 mL, 10.1 mmol), 2 (2.00 g, 10.1 mmol), and formic acid (5
drops) in MeOH (20.0 mL) was heated to reflux temperature. After
the mixture was cooled to room temperature, the solvent was removed
under reduced pressure. The resulting oil was purified by Kugelrohr
distillation (240 °C, 140 Pa). The desired product was obtained as a
yellow oil in 71% yield. The product was contaminated with traces of
an unknown impurity. 1H NMR (400 MHz, CDCl3): δ (ppm) 2.04 (s,
6H), 2.31 (s, 6H), 6.92 (s, 2H), 7.33 (m, 1H), 7.84 (m, 1H), 7.94 (t,
N-(2,2,2-Trifluoro-[2,2′-bipyridin-6-yl]ethylidene)-2,6-diiso-
propylbenzenamine (9). The compound was prepared according to
the published procedure with some modifications.21 A mixture of 2,6-
diisopropylaniline (0.85 mL, 4.03 mmol), 3 (1.02 g, 4.03 mmol), and
p-toluenesulfonic acid monohydrate (23.3 mg, 0.12 mmol) in toluene
(10.2 mL) was heated to reflux temperature (Dean−Stark trap). After
the mixture was cooled to room temperature, the solvent was removed
under reduced pressure. The resulting oil was purified by Kugelrohr
distillation (210 °C, 140 Pa). The desired product was obtained as a
yellow oil in 55% yield. The product was contaminated with traces of
an unknown impurity. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.18 (d,
3
3
3
1H, JHH = 7.8 Hz), 8.42 (d, 1H, JHH = 7.8 Hz), 8.55 (t, 2H, JHH
=
8.2 Hz), 8.71 (m, 1H). 13C{1H} NMR (100.4 MHz, CDCl3): δ (ppm)
16.58, 17.98, 20.84, 121.16, 121.26, 122.02, 123.88, 125.38, 128.66,
132.25, 136.96, 137.45, 146.42, 149.27, 154.94, 155.87, 156.15, 167.61.
GC-MS (EI): 315 (33), 300 (100).
3
3
12H, JHH = 6.8 Hz), 2.78 (sept, 2H, JHH3 = 6.4 Hz), 7.10 (m, 3H),
7.17 (d, 1H, 3JHH = 6.7 Hz), 7.29 (t, 1H, JHH = 6.2 Hz), 7.72 (t, 2H,
3JHH = 6.7 Hz), 7.87 (d, 1H, JHH = 7.1 Hz), 8.40 (d, 1H, JHH = 7.6
Hz), 8.62 (br, 1H). 13C{1H} NMR (100 MHz, CDCl3): δ (ppm)
22.36, 28.45, 121.92, 122.31, 123.43, 123.78, 124.33, 124.77, 134.57,
3
3
N-(2,2-Dimethyl-[2,2′-bipyridin-6-yl]propylidene)-2,4,6-tri-
methylbenzenamine (6). The compound was prepared according to
the published procedure with some modifications.20 A mixture of
2,4,6-trimethylaniline (0.89 mL, 6.24 mmol), 4 (1.00 g, 4.16 mmol),
and p-toluenesulfonic acid monohydrate (41.0 mg, 0.21 mmol) in
toluene (20.0 mL) was heated to reflux temperature (Dean−Stark
trap). Afterthe mixture was cooled to room temperature, the solvent
was removed under reduced pressure. The resulting oil was purified by
2
137.00, 137.46, 143.73, 147.06, 149.09, 153.45 (q, JCF = 33.01 Hz),
155.08, 156.06 (one signal was not assignable due to coincident
signal). GC-MS (EI): 411 (11), 368 (10), 342 (100).
N-(1-[2,2′-Bipyridin-6-yl]ethylidene)-2,4,6-trimethylbenzen-
amine Iron(II) Bromide ((HBPIMes,Me)FeBr2). FeBr2 (anhydrous)
(1.98 g, 6.26 mmol) was added to a solution of 5 (1.38 g, 6.26 mmol)
G
Organometallics XXXX, XXX, XXX−XXX