Reactions of 2,2-dihydropolyfluoroalkylaldehydes with amines: A facile synthetic method for fluoroalkyl enaminoketones

Article abstract of DOI:10.1016/j.jfluchem.2003.11.005

Reactions of 2,2-dihydropolyfluoroalkylaldehydes (1) with amines (2) were studied. Both aliphatic amines and electron-deficient aromatic amines readily reacted with 1 in acetonitrile and water under reflux to give fluoroalkyl enaminoketones (3) in high yields, while no condensed products were obtained by reactions of 1 with electron-rich aromatic amines under similar conditions. In the presence of triethylamine, however, the reaction of 1 with electron-rich aromatic amines at room temperature gave 3 in low yields.

Full text of DOI:10.1016/j.jfluchem.2003.11.005

Journal of Fluorine Chemistry 125 (2004) 415–419
Reactions of 2,2-dihydropolyfluoroalkylaldehydes with amines:
a facile synthetic method for fluoroalkyl enaminoketones
Xian-Jin Yang, Jin-Tao Liu*, Fu-Lu Zhao
Lab. of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Road, Shanghai 200032, China
Received 8 June 2003; received in revised form 10 September 2003; accepted 10 November 2003
Abstract
Reactions of 2,2-dihydropolyfluoroalkylaldehydes (1) with amines (2) were studied. Both aliphatic amines and electron-deficient aromatic
amines readily reacted with 1 in acetonitrile and water under reflux to give fluoroalkyl enaminoketones (3) in high yields, while no condensed
products were obtained by reactions of 1 with electron-rich aromatic amines under similar conditions. In the presence of triethylamine,
however, the reaction of 1 with electron-rich aromatic amines at room temperature gave 3 in low yields.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Fluoroalkylaldehydes; Amines; Nucleophilic addition; Elimination; Hydrolysis; Fluoroalkyl enaminoketones; Steric effect; Electronic effect
1. Introduction
ods provided 3 only in low yield and needed expensive
catalyst. Herein, we report a simple and facile synthetic
method for compound 3 from 2,2-dihydropolyfluoroalkyl
aldehydes which are applied to various fluoroalkyl groups.
Introduction of fluorine atoms and fluorinated groups into
organic molecules often results in significant and useful
changes on their chemical and physical properties. There-
fore, the development of synthetic methods for fluorinated
compounds has been of great interest for synthetic and
medicinal chemists [1,2]. Fluoroalkyl enaminoketones (3)
are versatile fluorinated intermediates and widely used as
precursors for the synthesis of fluorine-containing hetero-
cyclic compounds, dyes and drugs as well as reagents for the
protection of amino group in peptide synthesis [3–7], and
much attention has been paid to the development of new
methodologies for their synthesis in recent years [8–14].
Trifluoroacetylation of ethyl vinyl ether with trifluoroacetic
anhydride and the following addition of amines is commonly
used method for the preparation of trifluoromethyl enam-
inoketones, however, it is difficult to be extended to the
synthesis of enaminoketones with other fluoroalkyl substi-
tuents. In 1977, Le Blanc et al. synthesized 3 using perfluoro-
alkynes as starting materials [10], but it is difficult to obtain
perfluoroalkynes. Huang and Zhou recently reported the
synthesis of 3 from perfluoroalkyl iodides using Pd(PPh3)4
or Ni(PPh3)4 as catalyst [13], however, these reaction meth-
2. Results and discussion
2,2-Dihydropolyfluoroalkyl aldehydes (1) were easily
prepared in high yields by the reaction of ethyl vinyl ether
and per(poly)fluoroalkyl iodides initiated with Na2S2O4
under mild conditions [15]. In the presence of a small
amount of water, 1 readily reacted with various amines
(2) in acetonitrile under reflux to give the correspond-
ing fluoroalkyl substituted enaminoketones, RFCOCH¼
CHNR1R2 (3), as final products. The results are summarized
in Table 1.
It is considered that the reaction proceeded via two steps
as shown in Scheme 1. In the first step, nucleophilic attack
of 2 on 1 followed by the elimination of H2O to give
the corresponding fluoroalkylated enamines, RFCF2CH¼
CHNR1R2. Then the CF2 group next to the double bond
in the enamines was hydrolyzed under basic conditions to
provide the final products. Thus, water was essential for the
reaction of 1 with 2: in the case of dimethylamine, commer-
cially available 33% aqueous solution was used, while a
mixture of acetonitrile and water (20:1) was used as a
solvent in the case of other amines. It was reported that
* Corresponding author. Tel.: þ86-21-64163300;
fax: þ86-21-64166128.
E-mail address: jtliu@pub.sioc.ac.cn (J.-T. Liu).
0022-1139/$ – see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2003.11.005

416
X.-J. Yang et al. / Journal of Fluorine Chemistry 125 (2004) 415–419
Table 1
The reaction of 1 with amines
Entry
Substrate
Amines
Conditions
Product
Yielda (%)
E or Z (J)
1
2
1a
1a
1a
1b
1c
1b
1b
1b
1b
1c
1d
1b
1c
1d
Me2NH (2m)
Et2NH (2n)
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, reflux, 2h
MeCN/H2O, Et3N, r.t., 4h
MeCN/H2O, Et3N, r.t., 4h
MeCN/H2O, Et3N, r.t., 4h
3am
3an
3ao
3bn
3cm
3bp
3bq
3br
3bs
3cs
95
98
87
97
97
76
74
71
83
85
81
28
34
33
E (12.3)
E (12.3)
E (12.0)
E (12.3)
E (12.3)
Z (7.2)
Z (6.9)
Z (2.4)
Z (6.6)
Z (8.1)
Z (8.1)
Z (6.9)
Z (7.2)
Z (7.5)
3
Pyrrolidine (2o)
Et2NH (2n)
Me2NH (2m)
4
5
6
MeNH2 (2p)
7
n-C3H7NH2 (2q)
n-C5H11NH2 (2r)
p-NO2C6H4NH2 (2s)
p-NO2C6H4NH2 (2s)
p-NO2C6H4NH2 (2s)
p-MeOC6H4NH2 (2t)
p-MeOC6H4NH2 (2t)
p-MeOC6H4NH2 (2t)
8
9
10
11
12
13
14
3ds
3bt
3ct
3dt
a Determined by 19F NMR spectra based on 1.
R2R1N
R1R2NH (2)
H2O
R2R1N
CHCF2RF
H
RFCF2CH2CHO
CHCORF
H
- 2HF
1
3
RF = a, CF3; b, CF2Cl; c, C3F7; d, C3F6Cl
Scheme 1.
aldehydes RFCF¼CHCHO formed as by-products accom-
panying with enaminoketones RFCOCH¼CHNR1R2 when
enamines RFCF2CH¼CHNR1R2 were hydrolyzed in acidic
conditions [12,13]. To avoid this side reaction, excess 2 were
used to keep reaction media slightly basic.
Configurations of compound 3 against the double bond
were determined by the coupling constants of the two
olefinic hydrogens in 1H NMR spectra. In the tertiary
enaminoketones obtained from secondary amines, big cou-
pling constants indicated E-configuration, which were steri-
cally predominant. On the other hand, other enaminoketones
preferred Z-configuration because of the existence of
NÀH Á Á Á O intramolecular hydrogen bonding. This was also
confirmed by the crystal structure of compound 3bs (Fig. 1)
As shown in Table 1, variation of RF did not affect on the
yields of 3, but variation of amines distinctly affected on
them. Both aliphatic amines and electron-deficient aromatic
amines reacted with 1 to give 3, which were obtained in
higher yields by the reaction of 1 with aliphatic secondary
amines (Table 1, entries 1–5). In the case of electron-rich
aromatic amines, no fluoroalkyl enaminoketones were
obtained under reflux. All tries to make fluoroalkyl enam-
inoketones from electron-rich aromatic amines gave no
satisfactory results: a reaction of 1 with an equal molar of
p-methoxyaniline in the presence of triethylamine at room
temperature gave the corresponding enaminoketones (3bt,
3ct, 3dt) only in 28–34% yields (Table 1, entries 12–14).
˚
˚
and the hydrogen bonding data: H Á Á Á A < r (A) þ 2.000 (A)
and ffDHA: 1108, D–H: N2–H7, A: O3, d ðDÀHÞ ¼ 0:860
˚
˚
˚
(A), d H Á Á Á A ¼ 2:112 (A), d ðD Á Á Á AÞ ¼ 2:736 (A),
ffDHA ¼ 129:068 (Table 2).
In the 1H NMR spectra of several products obtained from
the reaction of 1 with primary amines, a doublet of doublet
(dd) pattern for the methylene proton next to amino group
such as 3bp, 3ct and 3dt was observed, which was con-
tributed to the coupling with another methylene proton and
Fig. 1. Crystal structure of compound 3bs.

X.-J. Yang et al. / Journal of Fluorine Chemistry 125 (2004) 415–419
417
Table 2
mixture was extracted with ethyl acetate (3 ꢀ 20 ml). The
combined organic layer was washed with water (2 ꢀ 10 ml)
and dried over anhydrous Na2SO4. After removal of the
solvent, the crude product was purified by recrystallization
in hexane or column chromatography (ethyl acetate and light
petroleum) to give 3.
Crystal data
Emperical formula
C10H7N2O3F2Cl
M
276.63
293 (2) K
T
Crystal
Wavelength
Monoclinic P2(1)/c
˚
0.71073 A
Unit cell dimension
˚
3.2.1. (E)-4-(Dimethylamino)-1,1,1-trifluoro-3-buten-2-
one (3am) [14]
White solid. 19F NMR (282 MHz, CDCl3): d À 77:5 (3F,
s, CF3). 1H NMR (300 MHz, CDCl3): d 7.88 (1H, d,
J ¼ 12:3, CH¼), 5.28 (1H, d, J ¼ 12:3, CH¼), 3.21 (3H,
s, CH3), 2.95 (3H, s, CH3).
a (A)
6.3161 (17)
5.1815 (14)
34.852 (9)
90
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Volume (A)
Z
d (mg mÀ3
93.357 (5)
90
3
˚
1138.6 (5)
4
3.2.2. (E)-4-(Diethylamino)-1,1,1-trifluoro-3-buten-2-one
(3an) [14]
)
1.614
Absorption coefficient
m (mmÀ1
White solid. 19F NMR (282 MHz, CDCl3): d À 77:4 (3F,
s, CF3). 1H NMR (300 MHz, CDCl3): d 7.89 (1H, d,
J ¼ 12:3, CH¼), 5.33 (1H, d, J ¼ 12:3, CH¼), 3.42 (4H,
m, 2 ꢀ CH2), 1.29 (6H, m, 2 ꢀ CH3).
)
0.364
Crystal size (mm)
Hydrogen bonds
0.653 ꢀ 0.188 ꢀ 0.167
˚
˚
H Á Á Á A < r (A) þ 2.000 (A)
and ffDHA ¼ 1108
D–H
N2–H7
0.860
2.112
129.06
2.736
O3
d (D–H)
d (H Á Á Á A)
ffDHA (8)
d (D Á Á Á A)
A
3.2.3. (E)-4-(1-Pyrrolidinyl)-1,1,1-trifluoro-3-buten-2-one
(3ao) [14]
White solid. 19F NMR (282 MHz, CDCl3): d À 77:4 (3F,
s, CF3). 1H NMR (300 MHz, CDCl3): d 8.08 (1H, d,
J ¼ 12:0, CH¼), 5.24 (1H, d, J ¼ 12:0, CH¼), 3.63 (4H,
m, 2 ꢀ CH2), 2.11 (4H, m, 2 ꢀ CH2).
nitrogen proton (N–H). It was confirmed by the D2O
exchange experiment: after D2O exchange, the peak of
nitrogen proton (N–H) disappeared and the dd peak of
the methylene proton was changed to a double peak.
3.2.4. (E)-4-(Diethylamino)-1,1-difluoro-1-chloro-3-
buten-2-one (3bn)
White solid; mp: 28–30 8C. IR: vmax (cmÀ1) 2988, 1663,
1575, 1282, 1132, 1081, 957, 768. 19F NMR (282 MHz,
CDCl3): d À 64:9 (2F, s, CF2Cl). 1H NMR (300 MHz,
CDCl3): d 7.88 (1H, d, J ¼ 12:3, CH¼), 5.34 (1H, d,
J ¼ 12:3, CH¼), 3.44 (4H, m, 2 ꢀ CH2), 1.31 (6H, m,
2 ꢀ CH3). EIMS m/z (rel. int.): 213 [M þ 2]þ (9), 211
[M]þ (28), 126 [M–CF2Cl]þ (100). Analytically calculated
for C8H12ClF2NO: C, 45.40; H, 5.71; N, 6.62. Found: C,
45.41; H, 5.75; N, 6.65.
3. Experimental
3.1. General experimental procedures
Melting points were uncorrected. IR spectra were taken
1
on a Perkin-Elmer 983G IR spectrophotometer. H NMR
spectra were measured on a Bruker AM300 (300 MHz)
spectrometer using TMS as an internal standard. 19F
NMR spectra were taken on a Bruker AM300 (282 MHz)
3.2.5. (E)-1-(Dimethylamino)-4,4,5,5,6,6,6-heptafluoro-1-
hexen-3-one (3cm)
spectrometer; chemical shifts are reported as dCFCl
3
(dCFCl ¼dTFA À 76:8), negative for upfield shifts. Mass
White solid; mp: 50–52 8C. IR: vmax (cmÀ1) 3012, 1661,
1587, 1502, 1429, 1347, 1227, 1115, 867, 704. 19F NMR
(282 MHz, CDCl3): d À 80:9 (3F, s, CF3), À121.6 (2F, s,
3
spectra were obtained on a Finnigan GC–MS 4021 spectro-
meter. X-ray data were measured at 293 K on a Bruker
SMART CCD diffractomer with graphite monochromated
Mok\a radiation. Column chromatography was performed
using silica gel H, particle size 10–40 mm.
1
CF2), À127.2 (2F, s, CF2). H NMR (300 MHz, CDCl3): d
7.90 (1H, d, J ¼ 12:3, CH¼), 5.36 (1H, d, J ¼ 12:3, CH¼),
3.24 (3H, s, CH3), 2.98 (3H, s, CH3). EIMS m/z (rel. int.):
267 [M]þ (6), 248 [M–F]þ (2), 98 [M–C3F7]þ (100). Ana-
lytically calculated for C8H8F7NO: C, 35.97; H, 3.02; N,
5.24. Found: C, 35.77; H, 3.25; N, 5.15.
3.2. Typical procedure for the preparation of 3am to 3ds
A solution of amine (3 mmol) in 5 ml MeCN and 0.5 ml
water was added dropwise to a solution of 1 (1 mmol) in
MeCN (5 ml) under stirring. The resulting mixture was
stirred at room temperature for 10 min and then refluxed
for 2 h. After cooling, 10 ml water was added and the
3.2.6. (Z)-4-Methylamino-1,1-difluoro-1-chloro-3-buten-2-
one (3bp)
Colorless liquid. IR: vmax (cmÀ1) 3284, 3079, 2949, 2832,
1651, 1596, 1509, 1307, 1227, 1141, 1080, 929, 855. 19F

418
X.-J. Yang et al. / Journal of Fluorine Chemistry 125 (2004) 415–419
NMR (282 MHz, CDCl3): d À 64:7 (2F, s, CF2Cl). 1H NMR
(300 MHz, CDCl3): d 10.05 (1H, d, J ¼ 7:2, NH), 7.08 (1H,
dd, J ¼ 7:2, 7.2, CH¼), 5.33 (1H, d, J ¼ 7:2, CH¼), 3.13
(3H, s, CH3). EIMS m/z (rel. int.): 171 [M þ 2]þ (6), 169
[M]þ (18), 134 [M–Cl]þ (3), 84 [M–CF2Cl]þ (100). Analy-
tically calculated for C5H6ClF2NO: C, 35.42; H, 3.57; N,
8.26. Found: C, 35.49; H, 3.76; N, 8.31.
m, ArH), 5.87 (1H d, J ¼ 8:1, CH¼). EIMS m/z (rel. int.):
361 [M þ 1]þ (6), 360 [M]þ (47), 191 [M–C3F7]þ (79), 145
[M–C3F7–NO2]þ (100), 117 (52). EI-HRMS calculated for
C12H7F7N2O3: 360.03449. Found: 360.03443.
3.2.11. (Z)-1-[(4-Nitrophenyl)amino]-4,4,5,5,6,6-
heptafluoro-6-chloro-1-hexen-3-one (3ds)
Yellow solid; mp: 118–120 8C. IR: vmax (cmÀ1) 3250,
3105, 1649, 1571, 1490, 1303, 1187, 1114, 850, 747. 19F
NMR (282 MHz, CDCl3): d À 67:4 (2F, s, CF2), À119.8 (2F,
s, CF2), À120.8 (2F, s, CF2). 1H NMR (300 MHz, CDCl3): d
11.84 (1H, d, J ¼ 12:0, NH), 8.30 (2H, m, ArH), 7.70 (1H,
dd, J ¼ 12:0, 8.1, CH¼), 7.27 (2H, m, ArH), 5.88 (1H d,
J ¼ 8:1, CH¼). EIMS m/z (rel. int.): 378 [M þ 2]þ (15), 376
[M]þ (48), 341 [M–Cl]þ (21), 191 [M–C3F6Cl]þ (98), 145
[M–C3F6Cl–NO2]þ (100), 117 (44). Analytically calculated
for C12H7ClF6N2O3: C, 38.23; H, 1.87; N, 7.43. Found: C,
38.31; H, 1.88; N, 7.29.
3.2.7. (Z)-4-(Propylamino)-1,1-difluoro-1-chloro-3-buten-
2-one (3bq)
Colorless liquid. IR: vmax (cmÀ1) 3267, 2970, 2939, 2881,
1647, 1595, 1502, 1311, 1225, 1139, 1080, 936. 19F NMR
(282 MHz, CDCl3): d À 64:6 (2F, s, CF2Cl). 1H NMR
(300 MHz, CDCl3): d 10.15 (1H, d, J ¼ 7:2, NH,), 7.15
(1H, dd, J ¼ 6:9, 7.2, CH¼), 5.29 (1H, d, J ¼ 6:9, CH¼),
3.30 (2H, m, CH2), 1.66 (2H, m, CH2), 0.96 (3H, m, CH3).
EIMS m/z (rel. int.): 199 [M þ 2]þ (7), 197 [M]þ (20), 112
[M–CF2Cl]þ (100), 85 [CF2Cl]þ (6). Analytically calculated
for C7H10ClF2NO: C, 42.55; H, 5.10; N, 7.09. Found: C,
42.30; H, 5.20; N, 7.28.
3.3. Typical experimental procedure for the preparation
of 3bt to 3dt
3.2.8. (Z)-4-(Pentylamino)-1,1-difluoro-1-chloro-3-buten-
2-one (3br)
A solution of p-methoxyaniline (1 mmol) and Et3N
(3 mmol) in 1 ml MeCN and 0.5 ml water was added drop-
wise to a solution of 1 (1 mmol) in MeCN (5 ml) under
nitrogen. The resulting mixture was stirred at room tem-
perature for 4 h and worked up in a similar method to the
preparation of 3am to give 3bt to 3dt as yellow solid.
Colorless liquid. IR: vmax (cmÀ1) 3281, 2901, 2935, 2863,
2833, 1639, 1599, 1468, 1386, 1310, 1259, 1162, 1131,
1050, 941, 923, 747, 695. 19F NMR (282 MHz, CDCl3):
1
d À 69:7 (2F, s, CF2Cl). H NMR (300 MHz, CDCl3): d
10.48 (1H, br s, NH), 9.28 (1H, d, J ¼ 2:4, CH¼), 5.41 (1H,
d, J ¼ 2:4, CH¼), 3.44 (2H, m, CH2), 1.68 (2H, m, CH2),
1.42À1.23 (4H, m, 2 ꢀ CH2), 0.92 (3H, t, CH3). EIMS m/z
(rel. int.): 227 [M þ 2]þ (4), 225 [M]þ (13), 190 [M–Cl]þ
(17), 140 [M–CF2Cl]þ (100). Analytically calculated for
C9H14ClF2NO: C, 47.88; H, 6.24; N, 6.21. Found: C, 47.90;
H, 6.25; N, 5.96.
3.3.1. (Z)-4-[(4-Methoxyphenyl)amino]-1,1-difluoro-1-
chloro-3-buten-2-one (3bt)
Yellow solid; mp: 74–76 8C. IR: vmax (cmÀ1) 3240, 3011,
2959, 1620, 1589, 1513, 1408, 1253, 1184, 1128, 1035, 957,
826, 786, 740. 19F NMR (282 MHz, CDCl3): d À 65:2 (2F, s,
CF2). 1H NMR (300 MHz, CDCl3): d 11.76 (1H, d,
J ¼ 13:2, NH), 7.68 (1H, dd, J ¼ 6:9, 13.2, CH¼), 7.21
(2H, m, ArH), 6.88 (2H, m, ArH), 5.68 (1H, d, J ¼ 6:9,
CH¼), 3.83 (3H, s, CH3O). EIMS m/z (rel. int.): 263
[Mþ þ 2] (8), 261 [M]þ (45), 176 [M–CF2Cl]þ (100).
Analytically calculated for C11H10ClF2NO2: C, 50.49; H,
3.85; N, 5.35. Found: C, 50.85; H, 3.78; N, 5.12.
3.2.9. (Z)-4-[(4-Nitrophenyl)amino]-1,1-difluoro-1-chloro-
3-buten-2-one (3bs)
Yellow solid; mp: 104–106 8C. IR: vmax (cmÀ1) 3325,
3105, 1695, 1654, 1586, 1287, 1608, 856, 749, 695. 19F
NMR (282 MHz, CDCl3): d À 65:9 (2F, s, CF2Cl). 1H NMR
(300 MHz, CDCl3): d 11.51 (1H, d, J ¼ 12:9, NH), 8.30
(2H, m, ArH), 7.72 (1H, dd, J ¼ 12:9, 6.6, CH¼), 7.25 (2H,
m, ArH), 5.82 (1H d, J ¼ 6:6, CH¼). EIMS m/z (rel. int.):
278 [M þ 2]þ (6), 276 [M]þ (51), 191 [M–CF2Cl]þ (100),
117 (49). Analytically calculated for C10H7F2ClN2O3: C,
43.58; H, 2.56; N, 10.16. Found: C, 43.55; H, 2.45; N,
10.19.
3.3.2. (Z)-1-[(4-Methoxyphenyl)amino]-4,4,5,5,6,6,6-
heptafluoro-1-hexen-3-one (3ct)
Yellow solid; mp: 40–42 8C. IR: vmax (cmÀ1) 3259,
2970, 2941, 1642, 1565, 1495, 1302, 1182, 1119,1035,
888, 751. 19F NMR (282 MHz, CDCl3): d À 80:6 (3F, s,
1
CF3), À121.2 (2F, s, CF2), À126.9 (2F, s, CF2). H NMR
3.2.10. (Z)-1-[(4-Nitrophenyl)amino]-4,4,5,5,6,6,6-
heptafluoro-1-hexen-3-one (3cs)
(300 MHz, CDCl3): d 12.06 (1H, d, J ¼ 11:7, NH), 7.60
(1H, dd, J ¼ 11:7, 7.2, CH¼), 7.10 (2H, m, ArH), 6.93
(2H, m, ArH), 5.68 (1H, d, J ¼ 7:2, CH¼), 3.82 (3H, s,
CH3O). EIMS m/z (rel. int.): 346 [M þ 1]þ (10), 345 [M]þ
(69), 326 [M–F]þ (3), 176 [M–C3F7]þ (100), 133 [CH3-
OC6H4NC]þ (49). Analytically calculated for C13H10F7-
NO2: C, 45.23; H, 2.92; N, 4.05. Found: C, 45.43; H, 3.17;
N, 3.91.
Yellow solid; mp: 94–96 8C. IR: vmax (cmÀ1) 3268, 3250,
1649, 1618, 1571, 1536, 1489, 1345, 1232, 1299, 1118, 849,
858, 779, 749. 19F NMR (282 MHz, CDCl3): d À 80:4 (3F, s,
1
CF3), –121.3 (2F, s, CF2), –126.7 (2F, s, CF2). H NMR
(300 MHz, CDCl3): d 11.85 (1H, d, J ¼ 12:0, NH), 8.32
(2H, m, ArH), 7.70 (1H, dd, J ¼ 12:0, 8.1, CH¼), 7.27 (2H,

X.-J. Yang et al. / Journal of Fluorine Chemistry 125 (2004) 415–419
419
[2] I. Ojima, J.R. Mccarthy, J.T. Welch, Biomedical Frontiers of
Fluorine Chemistry, ACS Symposium Series, no. 639, Washington
DC, 1996.
3.3.3. (Z)-1-[(4-Methoxyphenyl)amino]-4,4,5,5,6,6-
hexafluoro-6-chloro-1-hexen-3-one (3dt)
Yellow solid; mp: 130–132 8C. IR: vmax (cmÀ1) 3235,
3041, 1624, 1587, 1518, 1411, 1182, 1113, 849. 19F NMR
(282 MHz, CDCl3): d À 68:8 (2F, s, CF2), À120.5 (2F, s,
[3] I.L. Baraznenok, V.G. Nenajdenko, E.S. Balenkova, Eur. J. Org.
Chem. (1999) 937–941
[4] I.I. Gerus, M.G. Gorbunova, S.I. Vdovenko, J. Org. Chem. USSR 26
(1990) 1623–1628.
1
CF2), À121.9 (2F, s, CF2). H NMR (300 MHz, CDCl3): d
[5] I.I. Gerus, L.M. Kacharova, S.I. Vdovenko, Synthesis (2001) 431–
436.
12.00 (1H, d, J ¼ 11:4, NH), 7.65 (1H, dd, J ¼ 11:4, 7.5,
CH¼), 7.11 (2H, m, ArH), 6.94 (2H, m, ArH), 5.68 (1H, d,
J ¼ 7:5, CH¼), 3.82 (3H, s, CH3O). EIMS m/z (rel. int.):
363 [M þ 2]þ (16), 361 [M]þ (46), 176 [M–C3F6Cl]þ (100),
133 [CH3OC6H4NC]þ (53), 107 [CH3OC6H4]þ (2). EI-
HRMS calculated for C13H10ClF6NO2: 361.03043. Found:
361.03195.
[6] R.J. Andrew, J.M. Meller, Tetrahedron 56 (2000) 7267–7272.
[7] R.J. Andrew, J.M. Meller, Tetrahedron 56 (2000) 7261–7266.
[8] A.V. Sanin, V.G. Nenajdenko, K.I. Smolko, D.I. Denisenko, E.S.
Balenkova, Synthesis (1998) 842–846.
[9] S.I. Vdovenko, I.I. Gerus, M.G. Gorbunova, J. Chem. Soc. Perkin
Trans. II (1993) 559–562.
[10] M. Le Blanc, G. Santiti, J. Gallucci, J.G. Riess, Tetrahedron 33
(1977) 1453–1456.
Acknowledgements
[11] Y.Z. Huang, Q.L. Zhou, Tetrahedron Lett. 27 (1986) 2397–2400.
[12] H. Masaru, M. Ryoichi, O. Etsuji, S. Syuhei, N. Hitoshi, M.
Katsushi, Tetrahedron Lett. 30 (1989) 6173–6176.
[13] Y.Z. Huang, Q.L. Zhou, J. Org. Chem. 52 (1987) 3552–3558.
[14] A.M. Platoshikin, Bull. Acad. Sci. USSR, Div. Chem. Sci. (1969)
98–105.
The authors thank the National Natural Science Founda-
tion of China for financial support (No. 20172065).
References
[15] W.Y. Huang, L. Lu, Chin. J. Chem. 9 (1991) 167–173.
[1] M. Hudlicky, Chemistry of Organic Fluorine Compounds, Ellis
Horwood Ltd., Chichester, 1992.