T. Katagiri et al. / Journal of Fluorine Chemistry 130 (2009) 714–717
717
under an argon atmosphere. Bromine (0.041 ml, 0.79 mmol) was
Acknowledgments
added dropwise and the reaction mixture was stirred for 1 min at
0 8C. Water bath was removed and then stirred for another 15 min
at room temperature. Then, triethylamine (0.14 ml, 1.0 mmol) was
added and stirred for 30 min at 0 8C. The reaction mixture was
filtered and concentrated under a reduced pressure. The crude
product was immediately purified by Kugelrohr distillation
apparatus at 100 8C/0.05 Torr. The orange oil of 2-bromo-2-
trifluoromethylketenimine (10) (0.082 g, 0.28 mmol, 70%) was
obtained.
We thank SC-NMR Laboratory of Okayama University for 19F
and 1H NMR analyses. We also thank Advanced Science Research
Center, Department of Instrumental Analysis of Okayama Uni-
versity for elemental analyses.
References
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d d 3.85 (s, 3H), 6.94 (d,
101.5 (s, 3F) ppm; 1H NMR
J = 9 Hz, 2H), 7.32 (d, J = 9 Hz, 2H) ppm; IR (neat) 2030 cmÀ1; MS m/
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4.8. Preparation of 2-trimethylsilyl-2-trifluoromethylketenimine
(Scheme 4, compound 11)
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Two necked round-bottomed flask was charged with trifluor-
omethylketenimine (4) (0.10 g, 0.47 mmol) in 0.5 ml of CH2Cl2.
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atmosphere and flask was cooled to À78 8C. Trimethylsilyl
trifluoromethanesulfonate (0.25 ml, 1.4 mmol) was added drop-
wise and the reaction mixture was stirred for 1 h at À78 8C. An
ethanol bath was put off and the reaction mixture was
continuously stirred for 5 h at room temperature. The reaction
mixture was concentrated under a reduced pressure. The crude
product was immediately purified by Kugelrohr distillation
apparatus at 100 8C/0.05 Torr. The colorless oil of 2-trimethylsi-
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19F NMR 113.3 (s, 3F) ppm; 1H NMR
d d 0.25 (s, 9H), 3.82 (s, 3H),
6.90 (d, J = 9 Hz, 2H), 7.20 (d, J = 9 Hz, 2H) ppm; IR (neat)
2040 cmÀ1; MS m/z (GC-EI) 287 (M+, 67), 272 (95), 176 (80), 77
(100); elemental analysis: Calcd for C13H16F3NOSi: C, 54.34; H,
5.61; N, 4.87. Found: C, 54.26; H, 5.68; N, 4.91.
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(3,3,3-trifluoro-1-(4-methoxyphenylamino)propylidene)malonate
(Scheme 5, compound 12)
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Two necked round-bottomed flask was charged with NaH (58%
in oil, 0.48 g, 1.16 mmol) in 2.0 ml of THF and cooled to À78 8C. To
the solution dimethyl malonate (0.136 g, 1.03 mmol) was added
and reaction mixture was stirred for 20 min at À78 8C, ketenimine
4 (0.147 g, 0.68 mmol) dissolved in 3 ml of THF were added
dropwise (30 min). The reaction mixture was stirred for 1 h at
À78 8C, then stirred 10 h at room temperature. Reaction mixture
was treated with silica gel. Short column chromatography gave
dimethyl 2-(3,3,3-trifluoro-1-(4-methoxyphenylamino)propylide-
ne)malonate 12 (0.133 g, 0.38 mmol, 59%) as a yellowish solid.
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9847.
19F NMR
d d 3.62 (q,
99.3 (t, J = 10 Hz, 3F) ppm; 1H NMR
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J = 10 Hz, 2H), 3.77 (s, 3H), 3.77 (s, 3H), 3.83 (s, 3H), 6.91 (d, J = 9 Hz,
2H), 7.06 (d, J = 9 Hz, 2H) ppm; IR (neat) 1700, 1600 cmÀ1; MS m/z
(GC-EI) 295 (M+, 70), 293 (68), 280 (10), 278 (8), 214 (100), 107
(25), 92 (68), 77 (88); elemental analysis: Calcd for C15H16F3NO5: C,
51.88; H, 4.64; N, 4.03. Found: C, 52.07; H, 4.55; N, 4.03.
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