PAPER
A Convenient Synthesis of Ketenimines from Thioamides with Haloiminium Salts
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N-(2,2-Diphenylethenylidene)aniline (4a)
Mp 52-52.5 °C (from pentane) (Lit. : 55-56 °C).
IR (neat): nmax = 2012, 1597, 1493, 1453, 760, 694 cm .
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5
1
H NMR (CDCl ): d = 4.77 (s, 2H, CH ), 7.14-7.35 (m, 15H, ArH).
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2
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1
IR (KBr): nmax = 1995, 1589, 1485, 760, 696 cm .
13
C NMR (CDCl ): d = 56.9, 76.3, 125.9, 127.1, 127.7, 128.3, 128.5,
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1
H NMR (CDCl ): d = 7.20-7.40 (m, 15H, ArH).
128.7, 134.5, 136.7, 188.0.
3
1
3
C NMR (CDCl ): d = 78.0, 124.0, 126.5, 127.8, 128.9, 129.6,
HRMS: m/z Calcd. for C H N: 283.1361. Found: 283.1334.
3
21 17
1
34.0, 140.6, 190.6.
N-(2-Phenylethenylidene)aniline13c (4h)
IR (neat): nmax = 2016, 1591, 1487, 758, 693 cm .
Anal. Calcd. for C H N: C, 89.19; H, 5.61; N, 5.20. Found: C,
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20
15
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8.92; H, 5.45; N, 5.11.
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H NMR (CDCl ): d = 5.23 (s, 1H, CH=C), 7.05-7.38 (m, 10H,
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4
-Methyl-N-(2,2-diphenylethenylidene)aniline (4b)
ArH).
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6
Mp 44-44.5 °C (from pentane) (Lit. : 82-84 °C).
13
C NMR (CDCl ): d = 60.6, 123.7, 125.2, 125.5, 127.6, 128.8,
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1
IR (KBr): nmax = 1995, 1597, 1493, 1188, 820, 760, 694 cm .
129.4, 132.4, 140.4, 190.7.
1
H NMR (CDCl ): d = 2.38 (s, 3H, CH ), 7.22-7.37 (m, 14H, ArH).
HRMS: m/z Calcd. for C H N: 193.0891. Found: 193.0887.
3
3
14 11
Anal. Calcd. for C H N: C, 89.01; H, 6.05; N, 4.94. Found: C,
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4
-Methyl-N-(2-phenylethenylidene)aniline (4i)
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9.06; H, 6.02; N, 4.94.
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1
IR (neat): nmax = 2004, 1597, 1495, 822, 760, 691 cm .
1
4
-Methoxy-N-(2,2-diphenylethenylidene)aniline (4c)
H NMR (CDCl ): d = 2.36 (s, 3H, CH ), 5.23 (s, 1H, CH=C), 7.07-
3
3
1
6
Mp 81-83 °C (from hexane) (Lit. : 83-85 °C).
7.29 (m, 9H, ArH).
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1
13
IR (KBr): nmax = 1985, 1501, 1250, 1032, 839, 764, 694 cm .
C NMR (CDCl ): d = 21.0, 60.6, 123.6, 125.1, 125.4, 128.8, 130.0,
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1
132.7, 137.6, 137.7, 190.0.
H NMR (CDCl ): d = 3.81 (s, 3H, CH O), 6.90 (d, 2H, J = 8.8 Hz,
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3
ArH), 7.21-7.37 (m, 12H, ArH).
HRMS: m/z Calcd. for C H N: 207.1048. Found: 207.1074.
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5
13
N-(9H-Fluoren-9-ylidenemethylene)aniline (4d)
Mp 81-82 °C (from hexane) (Lit. : 85-85.5 °C).
4-Methoxy-N-(2-phenylethenylidene)aniline (4j)
IR (neat): nmax = 2004, 1601, 1458, 835, 762, 692 cm .
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a
-1
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1
IR (KBr): nmax = 2016, 1588, 1476, 1449, 760, 725 cm .
H NMR (CDCl ): d = 3.82 (s, 3H, CH O), 5.22 (s, 1H, CH=C), 6.89
3
3
1
(d, 2H, J = 9.1 Hz, ArH), 7.10-7.18 (m, 3H, ArH), 7.24-7.32 (m, 4H,
ArH).
H NMR (CDCl ): d = 7.32-7.44 (m, 9H, ArH), 7.59-7.62 (m, 2H,
3
ArH), 7.88-7.91 (m, 2H, ArH).
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3
C NMR (CDCl ): d = 55.5, 60.8, 114.6, 125.0, 125.1, 125.4, 128.8,
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32.8, 132.9, 159.2, 189.3.
4
-Methyl-N-(9H-fluoren-9-ylidenemethylene)aniline (4e)
3a
Oil (Lit. oil).
HRMS: m/z Calcd. for C H NO: 223.0997. Found: 223.0994.
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5
13
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IR (KBr): nmax = 2012, 1453, 820, 762, 727 cm .
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N-(Benzyl)-N-(2-phenylethenylidene)amine (4k)
IR (neat): nmax = 2022, 1597, 1453, 1331, 696 cm .
H NMR (CDCl ): d = 2.37(s, 3H, CH ), 7.21 (d, 2H, J = 8.8 Hz,
ArH), 7.31-7.33 (m, 6H, ArH), 7.57-7.61 (m, 2H, ArH), 7.87-7.91
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1
(
m, 2H).
H NMR (CDCl ): d = 4.71 (d, 2H, J = 2.2 Hz, CH ), 4.82 (t, 1H,
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2
1
3
J = 2.2 Hz, CH=C), 7.02-7.07 (m, 3H, ArH), 7.19-7.36 (m, 7H,
ArH).
C NMR (CDCl ): d = 21.2, 74.0, 120.5, 121.8, 124.5, 125.4,
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26.4, 130.3, 135.7, 135.8, 137.7, 139.0, 181.2.
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3
C NMR (CDCl ): d = 56.8, 58.6, 124.7, 125.1, 127.6, 128.0, 128.4,
3
HRMS: m/z Calcd. for C H N: 281.1204. Found: 281.1213.
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1
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1
28.7, 133.4, 136.9, 188.4.
HRMS: m/z Calcd. for C H N: 207.1048. Found: 207.1080.
4
-Methyl-N-(9H-xanthen-9-ylidenemethylene)aniline (4f)
15 13
Mp 120-121 °C (decomp.) (from hexane).
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1
IR (KBr): nmax = 1993, 1483, 1447, 1302, 1262, 822, 752 cm .
Acknowledgement
1
H NMR (CDCl ): d = 2.38 (s, 3H, CH ), 6.94-7.00 (m, 4H, ArH),
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3
2
-Chloro-1,3-dimethylimidazolinium chloride (DMC) was kindly
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.06-7.19 (m, 4H, ArH), 7.20 (d, 2H, J = 8.2 Hz, ArH), 7.29 (d, 2H,
supplied by Shiratori Pharmaceutical Co., Ltd.
J = 8.2 Hz, ArH).
Anal. Calcd. for C H NO: C, 84.82; H, 5.08; N, 4.71. Found: C,.
2
1
15
8
5.00; H, 4.99; N, 4.63.
References
(
(
1) Staudinger, H.; Meyer, J. Helv. Chim. Acta 1919, 2, 635.
2) (a) Krow, G. R. Angew. Chem. Int. Ed. Engl. 1971, 10, 435.
Syntheses of Ketenimines 4g-4k; General Procedure
To the solution of thioamide 3 (1 mmol) in CH Cl (10 mL), DMC
2
2
(
b) Barker, M. W.; McHenry, W. E. In The Chemistry of
(
2, 1.5 mmol) was added. The mixture was stirred for 30 min at 0 °C
Ketenes, Allenes, and Related Compounds; Patai, S., Ed.;
Interscience: Chichester, 1980; p 701.
under N , Et N (4 mmol) was added and the mixture was further
2
3
stirred for 3 h at 0 °C. The solvent was evaporated under reduced
pressure and hexane was added to the crude reaction products. The
(
3) For example: (a) Saito, T.; Oikawa, I.; Motoki, S. Bull. Chem.
Soc. Jpn. 1980, 53, 2582.
precipitated Et N·HCl and 1,3-dimethylimidazolidine-2-thione
3
(
1
(
1
(
1
b) Dondoni, A.; Battaglia, A.; Giorgianni, P. J. Org. Chem.
980, 45, 3766.
c) Goerdeler, J.; Lindner, Ch.; Zander, F. Chem. Ber. 1981,
14, 536.
d) Dondoni, A.; Battaglia, A.; Giorgianni, P. J. Org. Chem.
982, 47, 3998.
were filtered off, and filtrate was evaporated under reduced pres-
1
sure. The yield was determined by H NMR spectroscopy.
N-(Benzyl)-N-(2,2-diphenylethenylidene)amine (4g)
Oil (Lit.1 : oil).
3b
Synthesis 2000, No. 4, 517–520 ISSN 0039-7881 © Thieme Stuttgart · New York