Full text of DOI:10.1016/S0040-4020(01)01157-7

TETRAHEDRON
Pergamon
Tetrahedron 58 %2002) 265±270
Stereoselective synthesis of ꢀZ)-tri¯uoromethyl enamines and their
Lewis acid-mediated conversion into ꢀE)-isomers
Biao Jiang,p Fangjiang Zhang and Wennan Xiong
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Road, Shanghai 200032, People's Republic of China
Received 8 May 2001; revised 18 October 2001; accepted 15 November 2001
AbstractÐ%Z)-b-Tri¯uoromethyl enamines were prepared in high yield stereoselectively by reaction of 2-bromo-3,3,3-tri¯uoropropene
with N-alkyl toluenesulfonamides and potassium t-butoxide in one pot via Michael addition and elimination processes. The %Z)-b-tri¯uoro-
methyl enamines could be converted to the corresponding thermodynamically stable %E)-isomers promoted by Lewis acid catalysts at room
temperature or thermal isomerization. q 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
availability of the starting materials, low yields and poor
stereoselectivity. Therefore, it is of great value to develop
more facile and effective methods for preparing b-tri¯uoro-
methyl enamines.
Organo¯uorine compounds have found increasing use in the
area of agrochemicals, pharmaceuticals, polymers and new
materials.1 Fluorine-containing enamines are versatile
building blocks for the introduction of ¯uorinated groups
into various new ¯uorine-containing heterocyclic com-
pounds and natural products.2 A number of new methods
have been developed to prepare the a-¯uorine-containing
enamines in addition to classical methods based on the
reactions of per¯uoroalkenes3 or 1H-per¯uoroalkynes4
with amines. Recently, Portella and Iznaden obtained
per¯uorinated enaminoesters in good yields by the reaction
Herein we wish to introduce a convenient and stereo-
selective access to %Z)-b-tri¯uoropropenamines in one
pot from the readily available 2-bromo-tri¯uoropropene
%BrTFP, 1) in high yields. The %Z)-isomers were converted
to thermodynamically more stable %E)-isomers by heating or
Lewis acid catalysis.
of a-H-per¯uoroesters with secondary amines.5 Begue
prepared a-tri¯uoromethylated enamines %Z/E mixture) by
condensation of tri¯uoroacetamides with alkylidene phos-
phoranes.6 Bravo has reported the synthesis of a-%¯uoro-
alkyl)-a-sul®nyl enamines by aza-Wittig reaction of tri-
phenyliminophosphoranes with the corresponding a-¯uori-
nated-a0-sul®nyl ketones and their further applications.7
However, the synthesis of b-tri¯uoromethylated enamines
has, for a long time, been dif®cult because the a-CF3-
attached carbanion would lead to a de¯uorination process.
For example, Uneyama only obtained N-trimethylsilylated
b,b-di¯uoroenamines from tri¯uoromethyl imines by an
electrochemical reduction.8 To the best of our knowledge,
only Yamanaka synthesized b-tri¯uoromethyl enamines
through the reaction of N-%2,3,3,3-tetra¯uoro-1-propenyl)-
trimethyl ammonium iodide with secondary amines,9 but it
is far from ideal. The reported methods suffered from lack of
Â
Â
2. Results and discussion
It has been reported that BrTFP %1) reacted with thiophenol
to yield the corresponding tri¯uoromethyl vinyl sul®de10 or
with alcohols to give %Z)-3,3,3-tri¯uoropropenyl alkyl
ethers in excellent yields under alkaline conditions.11
Those results prompted us to investigate the preparation
of tri¯uoromethyl enamines from the readily available 1.
Initially, we attempted to prepare tri¯uoromethyl enamines
by the direct reaction of 1 with alkylamines and potassium
hydroxide in ethanol, but only 3,3,3-tri¯uoropropenyl ethyl
ether was obtained. It is obvious that ethanol participated in
the reaction was faster than the amine. After many trials,
we found that the potassium N-substituted p-toluenesul-
fonamides reacted with BrTFP %1) smoothly. As a model
reaction, N-propenyl p-toluenesulfonamide 2a was treated
with potassium t-butoxide in a mixture of dimethylsulfoxide
and t-butyl alcohol to give a solution of potassium N-pro-
penyl p-toluenesulfonamide at room temperature, to which
was added BrTFP %1) at 808C for 5 h to give a stable
a-tri¯uoromethyl enamine 3a in 82% yield as a single
product %Scheme 1). The reactions extended to various
Keywords: tri¯uoromethyl enamines; sulfonamide; stereoselective; isomeri-
zation.
p
Corresponding author. Tel.: 186-21-6416-3300; fax: 186-21-6416-
6128; e-mail: jiangb@pub.sioc.ac.cn
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020%01)01157-7

266
B. Jiang et al. / Tetrahedron 58 02002) 265±270
Scheme 1.
substrates of N-alkyl or N-aryl p-toluenesulfonamide are
summarized in Table 1. It was shown that most of the sul-
fonamides 2b±h reacted cleanly to afford the corresponding
%Z)-b-tri¯uoromethyl enamines 3b±h in high yields %entries
2±7). The steric hindrance of the N-a-methylbenzyl
p-toluenesulfonamide 2h %entry 8) gave a low yield %47%)
of 3h. All of the reactions gave %Z)-con®guration of the
enamines, which was assigned due to the cis-hydrogen-
coupling constant of the double bond %JH±Hˆ10.9 Hz).
delocalized by conjugated with aromatic p orbital with a
small contribution for secondary-orbital of the p0 ±ppCF3
interaction, the major product could be the normal thermo-
dynamically more stable %E)-isomer as major product. This
hypothesis was con®rmed when the reaction was carried out
with uracil %7) and thymine %8) to give Z/E-isomers ratios of
15:85 %65% yield) %Scheme 2).
It is well known that Z-double bonds can be easily iso-
merized into thermodynamically more stable isomers by
thermal isomerization or phtoisomerization via a free
radical mechanism. When %Z)-b-tri¯uoromehtylated
enamines were heated in decahydronaphthene at 1908C for
1 min, they were exclusively converted into the correspond-
ing %E)-isomers 4 %Table 1). It was reported that Lewis acid
could promote inversion of double bond while irradiating
with UV light.13 In the case of conversion of the cis-
enamines 3 to trans-enamines 4, we found that %Z)-b-
tri¯uoromethylenamines 3 were transferred into %E)-isomers
in excellent yield with catalytic amounts of BF3´Et2O in
toluene at room temperature without irradiating with UV
lamp. The conversion reaction was complete in less than
one hour %Scheme 3).
We hypothesized that the mechanism of this unusual reac-
tion would be Michael addition followed by elimination
%Scheme 2). The strong electron-withdrawing property of
the tri¯uoromethyl groupof BrTFP % 1) causes high electron
de®ciency of the double bond. The amide 2 underwent
Michael addition to give an adduct, con®rmed in one
example by quenched the reaction after 1 h at room
temperature. Thus, intermediate 5 was isolated, which had
a signal at dTFA 26.28 ppm. While 5 was treated with
t-BuOK in DMSO, the dTFA 26.28 ppm signal gradually
converted into 223 ppm indicating formation of 3a.
To account for the cis-preference of CF3 and sulfonamide on
the double bond under the kinetic control elimination of
hydrogen bromide can be rationalized in terms of stabilizing
p0-type orbital interactions between the CF3 and enamine
fragments as depicted in 6 %Scheme 2). Bumgardner has
rationalized the stereochemistry of substituted tri¯uoro-
methyl ethylene to the secondary orbital interaction of the
LUMO %ppCF3) and HOMO %p0) of vinyl fragment.12In 6
the enamine moiety is presented by the HOMO p0, and the
CF3 groupby its LUMO ppCF3. The p0 ±ppCF3 interaction
is expected to be more stabilizing for the cis than the trans
arrangement of CF3 and sulfonamide. It could be predicted
that if the reaction were carried out with the nitrogen atom
3. Conclusion
In summary, we have successfully developed a stereo-
selective method for the preparation %Z)-b-tri¯uoromethyl
enamines from the readily available 2-bromotri¯uoro-
propene in high yield. We found that BF3´Et2O could
promote the rearrangement of %Z)-b-tri¯uoromethyl
enamines into thermodynamically more stable E-isomers
at room temperature without irradiation with UV lamp or
by thermal isomerization in decahydronaphthene. The
reaction was processed under very mild conditions and
simple manipulations. The present reaction constitutes a
new facile route to %Z) or %E)-b-tri¯uoromethyl enamines
Table 1. Preparation of %Z)-b-tri¯uoromethyl enamines %3) and %E)-b-
tri¯uoromethyl enamines %4)
Entry
R in amide 2
Timea %h)
Yieldb,c %%)
%Z)-3
%E)-4
1
2
3
4
5
6
CH2vCH2CH2 %2a)
CH3CH2CH2 %2b)
CH3%CH2)4CH2 %2c)
Phenyl %2d)
Benzyl %2e)
CH3O%CH2)2CH2 %2f)
5
4
4
5
3
4
82 %3a)
82 %3b)
79 %3c)
80 %3d)
88 %3e)
92 %3f)
92 %4a)
96 %4b)
96 %4c)
95 %4d)
97 %4e)
97 %4f)
7
8
4
86 %3g)
47 %3h)
95 %4h)
8
a-Methylbenzyl %2h)
±
a
Reaction was carried out by treatment of BrTHF %1) %1.2 equiv.), t-BuOK
%1.4 equiv.) and toluene sulfonamide %0.8 equiv.) in DMSO/t-BuOH
%2:1).
Reaction was carried out by heating cis-3 in decahydronaphthene at
1908C for 1 h.
Isolated yield.
b
c
Scheme 2.

B. Jiang et al. / Tetrahedron 58 02002) 265±270
267
Scheme 3.
respectively, which are dif®cult to prepare by other
methods.
4.98 %1H, m, CF3CHvCH), 6.74 %1H, d, Jˆ10.8 Hz,
CF3CHvCH), 7.34 %2H, d, Jˆ8.36 Hz, 2£Ph-H), 7.68
%2H, d, Jˆ8.36 Hz, 2£Ph-H); m/z %EI) 307 %20, M1), 155
%100), 91 %93%).
4. Experimental
4.1.3. N-[ꢀE)-3,3,3-Tri¯uoropropenyl]-N-hexanyl-p-
toluenesulfonamide ꢀ3c). Colorless oil; %Found: C, 54.91;
1H NMR spectra were recorded on a VXL-300 instrument.
The chemical shifts are reported as d values in ppm relative
to tetramethylsilane as internal standard. 19F NMR spectra
were obtained on 56.4 MHz spectrometer with tri¯uoro-
acetic acid %d 0.00) as an external standard; down®eld shifts
were designated negative. IR spectra were recorded on
a Perkin±Elmer 983 FT-IR spectrometer. Mass spectral
measurements were performed on a Fining 4021 or Fining
MAT 8403 gas chromatography/mass spectrometer at
70 eV. Elemental analyses were carried out on a MOD-
1106 elemental analyzer.
H, 6.33; N, 4.12. C16H22F3NO2S requires C, 55.01; H, 6.30;
N, 4.01%); nmax %liquid ®lm) 1652, 1358, 1163, 1114 cm21
;
dF %56.4 MHz, CDCl3) 223.2 %CF3, d, Jˆ9.5 Hz); dH
%300 MHz, CDCl3) 0.86 %3H, t, Jˆ6.9 Hz, CH3), 1.19±
1.23 %6H, m, CH2), 1.59 %2H, m, CH2), 2.43 %3H, s, CH3),
3.45 %2H, t, Jˆ7.9 Hz, CH2), 4.91±4.99 %1H, m,
CF3CHvCH), 6.73 %1H, d, Jˆ10.8 Hz, CF3CHvCH),
7.33 %2H, d, Jˆ8.4 Hz, 2£Ph-H), 7.67 %2H, d, Jˆ8.4 Hz,
2£Ph-H); m/z %EI) 349 %5, M1), 265 %59.57), 155 %100),
91 %97%).
4.1.4. N-[ꢀZ)-3,3,3-Tri¯uoropropenyl]-N-phenyl-p-tolu-
enesulfonamide ꢀ3d). White solid; mp93 8C; %Found: C,
56.13; H, 3.92; N, 3.95. C16H14F3NO2S requires C, 56.30;
H, 4.11; N, 4.11%); nmax %Nujol) 1658, 1373, 1363, 1171,
1144 cm21; dF %56.4 MHz, CDCl3) 220.5 %CF3, d, Jˆ
9.8 Hz); dH %300 MHz, CD3COCD3) 2.40 %3H, s, CH3),
5.21±5.27 %1H, m, CF3CHvCH), 6.99 %2H, d, Jˆ7.5 Hz,
CF3CHvCH), 7.01±7.40 %5H, m, 5£Ph-H), 7.45 %2H, d,
Jˆ7.5 Hz, 2£Ph-H), 7.52 %2H, d, Jˆ7.5 Hz, 2£Ph-H); m/z
%EI) 341 %7, M1), 91 %100%).
4.1. General procedure for synthesis of N-[ꢀZ)-3,3,3-tri-
¯uoropropenyl]-N-alkyl-p-toluenesulfonamide ꢀ3)
N-Alkyl p-toluenesulfonamide %2) %8 mmol) in the mixture
solvent of DMSO %20 mL) and t-butyl alcohol %10 mL) was
added potassium t-butoxide %1.4 equiv.) at room tempera-
ture with stirring. When the reaction mixture was heated
to 808C, 2-bromotri¯uoropropene %1) %1.2 equiv.) was
added dropwise. The mixture was kept at 808C for 5 h.
After cooling to room temperature, the mixture was poured
into water %100 mL) and extracted with ethyl acetate
%3£50 mL). The combined extracts was washed with brine
and dried over Na2SO4. After removal of solvent under
reduced pressure, the residue was puri®ed on silica gel
column chromatography eluting with ethyl acetate and
petroleum ether %1:20) to afford 3.
4.1.5. N-[ꢀZ)-3,3,3-Tri¯uoropropenyl]-N-benzyl-p-tolu-
enesulfonamide ꢀ3e). White solid; mp80 8C; %Found: C,
57.41; H, 4.53; N, 4.05. C17H16F3NO2S requires C, 57.46;
H, 4.51; N, 3.94%); nmax %Nujol) 1681, 1363, 1167, 1145,
1115 cm21; dF %56.4 MHz, CDCl3) 222.5 %CF3, d, Jˆ
9.5 Hz); dH %300 MHz, CDCl3) 2.41 %3H, s, CH3), 4.71
%2H, s, CH2), 5.01±5.08 %1H, m, CF3CHvCH), 6.66 %1H,
d, Jˆ10.2 Hz, CF3CHvCH), 7.20±7.27 %5H, m, 5£Ph-H),
7.32 %2H, d, Jˆ7.5 Hz, 2£Ph-H), 7.62 %2H, d, Jˆ7.5 Hz,
2£Ph-H); m/z %EI) 355 %2, M1), 91 %100%).
4.1.1.
N-[ꢀZ)-3,3,3-Tri¯uoropropenyl]-N-propenyl-p-
toluenesulfonamide ꢀ3a). Colorless oil; %Found: C, 51.29;
H, 4.62; N, 4.60. C13H14F3NO2S requires C, 51.14; H, 4.59;
N, 4.59%); nmax %liquid ®lm) 1163, 1114, 1090 cm21; dF
%56.4 MHz, CDCl3) 223 %CF3, d, Jˆ9.5 Hz); dH %300
MHz, CDCl3) 2.44 %3H, s, CH3), 4.17 %2H, d, Jˆ7.7 Hz,
CH2CHvCH2), 4.93±5.03 %1H, m, CH2CHvCH2), 5.11±
5.19 %2H, m, CH2CHvCH2), 5.64±5.73 %1H, m,
CF3CHvCH), 6.73 %1H, d, Jˆ10.2 Hz, CF3CHvCH),
7.33 %2H, d, Jˆ8.4 Hz, 2£Ph-H), 7.70 %2H, d, Jˆ8.4 Hz,
2£Ph-H); m/z %EI) 305 %3, M1), 91 %100%).
4.1.6. N-[ꢀZ)-3,3,3-Tri¯uoropropenyl]-N-[ꢀ3-methoxy)-
propanyl]-p-toluenesulfonamide ꢀ3f). White solid;
%Found: C, 49.75; H, 5.35; N, 4.45. C14H18F3NO3S requires
C, 49.85; H, 5.34; N, 4.15%); nmax %Nujol) 1653, 1358,
1164, 1115 cm21; dF %56.4 MHz, CDCl3) 222.5 %CF3, d,
Jˆ9.5 Hz); dH %300 MHz, CDCl3) 1.85±1.90 %2H, m,
CH2), 2.43 %3H, s, CH3), 3.30 %3H, s, OCH3), 3.37 %2H, t,
Jˆ6.1 Hz, CH2N), 3.56 %2H, t, Jˆ7.5 Hz, CH2O), 4.98±
5.05 %1H, m, CF3CHvCH), 6.70 %1H, d, Jˆ10.6 Hz,
CF3CHvCH), 7.33 %2H, d, Jˆ8.1 Hz, 2£Ph-H), 7.68
%2H, d, Jˆ8.1 Hz, 2£Ph-H); m/z %EI) 337 %2, M1), 124
%100%).
4.1.2.
N-[ꢀZ)-3,3,3-Tri¯uoropropenyl]-N-propanyl-p-
toluenesulfonamide ꢀ3b). Colorless oil; %Found: C, 50.49;
H, 5.22; N, 4.58. C13H16F3NO2S requires C, 50.87; H, 5.21;
N, 4.56%); nmax %liquid ®lm) 1652, 1357, 1265, 1177, 1160,
1116 cm21; dF %56.4 MHz, CDCl3) 223 %CF3, d, Jˆ
9.5 Hz); dH %300 MHz, CDCl3) 0.85 %3H, t, Jˆ7.4 Hz,
CH2CH2 CH3), 1.57±1.67 %2H, m, CH2CH2 CH3), 2.44
%3H, s, CH3), 3.43 %2H, t, Jˆ7.9 Hz, CH2CH2 CH3), 4.92±
4.1.7. N-[ꢀZ)-3,3,3-Tri¯uoropropenyl]-N-[1-ꢀ3-morpho-
linyl)propanyl]-p-toluenesulfonamide ꢀ3g). %Found: C,

268
B. Jiang et al. / Tetrahedron 58 02002) 265±270
52.20; H, 5.87; N, 7.21. C17H23F3N2O3S requires C, 52.04;
H, 5.87; N, 7.14%); nmax %Nujol) 1681, 1164, 1144,
1113 cm21; dF %56.4 MHz, CDCl3) 223.0 %CF3, d, Jˆ
9.4 Hz); dH %300 MHz, CDCl3) 1.79±1.88 %2H, m, CH2),
2.31 %2H, t, Jˆ6.9 Hz, CH2), 2.38 %4H, t, Jˆ4.6 Hz, CH2),
2.44 %3H, s, CH3), 3.53 %2H, t, Jˆ7.8 Hz, CH2), 3.68 %4H, t,
Jˆ4.7 Hz, CH2), 4.96±5.01 %1H, m, CF3CHvCH), 6.76
%1H, d, Jˆ10.8 Hz, CF3CHvCH), 7.35 %2H, d, Jˆ8.1 Hz,
2£Ph-H), 7.68 %2H, d, Jˆ8.1 Hz, 2£Ph-H); m/z %EI) 392
%13, M1), 100 %100%).
7.96 %1H, s, thymine-H), 11.8 %1H, s, NH); m/z %EI) 221
%20, M111), 220 %61, M1), 80 %100%).
4.1.13. 2-Bromo-3,3,3-tri¯uoro-N-tosyl-N-2-propenyl-1-
propanamine ꢀ5). To a solution of N-propenyl p-toluene-
sulfonamide %2) %1.69 g, 8 mmol) and potassium t-butoxide
%1.24 g, 1.1 mmol) in DMSO %20 mL) and t-butyl alcohol
%10 mL) was added dropwise 2-bromotri¯uoropropene %1)
%2.1 g, 1.2 mmol.) at room temperature. When the reaction
mixture was stirred at room temperature for 1 h and then
poured into water %100 mL). The mixture was extracted with
ethyl acetate %3£50 mL). The combined extracts was
washed with brine and dried over Na2SO4. After removal
of solvent under reduced pressure, the residue was puri®ed
on silica gel column chromatography eluting with ethyl
acetate and petroleum ether %1:20) to afford 3a %1 g, 42%)
and 5 %1.2 g, 39%) as colorless oil. 5: %Found: C, 40.38; H,
3.54; N, 3.71. C13H15BrF3NO2S requires C, 40.43; H, 3.91;
N, 3.63%); nmax %Nujol) 3015, 1322, 1159, 1115 cm21; dF
%56.4 MHz, CDCl3) 26.28 %CF3, d, Jˆ7.65 Hz); dH %300
MHz, CDCl3) 2.45 %3H, s, CH3), 3.44 %1H, dd, Jˆ15.5,
9.01 Hz, CF3BrHCHaHb), 3.70 %1H, dd, Jˆ15.5, 4.78 Hz,
CF3BrHCHaHb), 3.85 %1H, dd, Jˆ15.6, 6.58 Hz,
CHaHbCHvCH2), 3.96 %1H, dd, Jˆ15.6, 6.72 Hz,
CHaHbCHvCH2), 5.14±5.21 %2H, m, CH2CHvCH2),
5.52±5.58 %1H, m, CF3CBrHCH2), 7.35 %2H, d, Jˆ
8.41 Hz, 2£Ph-H), 7.72 %2H, d, Jˆ8.41 Hz, 2£Ph-H); m/z
%EI) 385 %0.6, M1), 224 %100), 155 %51), 91 %64%).
4.1.8. N-[ꢀZ)-3,3,3-Tri¯uoropropenyl]-N-[ꢀ1R)-1-phenyl-
D
ethyl]-p-toluenesulfonamide ꢀ3h). Mp85 8C [a]20
ˆ
250.28 %c, 2.0, CHCl3); %Found: C, 58.18; H, 4.79; N,
3.66. C18H18F3NO2S requires C, 58.54; H, 4.88; N,
3.79%); nmax %Nujol) 1674, 1169, 1149, 1110 cm21; dF
%56.4 MHz, CDCl3) 218.5 %CF3, d, Jˆ7.9 Hz); dH %300
MHz, CDCl3) 1.50 %3H, d, Jˆ7.1 Hz, CHCH3), 2.43 %3H,
s, CH3), 5.16 %1H, q, Jˆ7.1 Hz, CHCH3), 5.53±5.59 %1H, m,
CF3CHvCH), 5.88 %1H, d, Jˆ9.0 Hz, CF3CHvCH), 7.03±
7.06 %2H, m, 2£Ph-H), 7.19±7.24 %3H, m, 3£Ph-H), 7.29
%2H, d, Jˆ8.1 Hz, 2£Ph-H), 7.61 %2H, d, Jˆ8.1 Hz,
2£Ph-H); m/z %EI) 369 %0.5, M1), 105 %100%).
4.1.9. 1-[ꢀZ)-3,3,3-Tri¯uoro-1-propenyl]-2,4ꢀ3H)-pyri-
midinedione ꢀ9a). Mp161 8C; %Found: C, 40.87; H, 2.29;
N, 13.39. C7H5F3N2O2 requires C, 40.78; H, 2.43; N,
13.59%); nmax %Nujol) 3026, 1737, 1699, 1 76, 1383,
1193, 1117 cm21; dF %56.4 MHz, Acetone-d6) 218.5 %CF3,
d, Jˆ9.0 Hz); dH %300 MHz, Acetone-d6) 5.80 %1H, d, Jˆ
8.1 Hz, pyrimidine-H), 6.00 %1H, dq, Jˆ9.7, 9.0 Hz,
CF3CHvCH), 7.18 %1H, d, Jˆ9.7 Hz, CF3CHvCH), 7.50
%1H, d, Jˆ8.1 Hz, pyrimidine-H), 10.50 %1H, s, NH); m/z
%EI) 206 %45, M1), 163 %100%).
4.2. General procedure for synthesis of ꢀE)-N-[ꢀZ)-3,3,3-
tri¯uoropropenyl]-N-alkyl-p-toluenesulfonamide ꢀ3)
Method A: %Z)-enamine 3 %0.5 mmol) in decahydro-
naphthene %2 mL) was heated at 1908C for 30 min,
monitored by 19F NMR. After the conversion was com-
pleted, decahydronaphthene was removed under reduced
pressure. The residue was subjected to ¯ash chroma-
tography on silica gel column eluting with ethyl acetate
and petroleum ether %1:15) to afford 4 as colorless oil.
4.1.10. 1-[ꢀE)-3,3,3-Tri¯uoro-1-propenyl]-2,4ꢀ3H)-pyri-
midinedione ꢀ9b). Mp157 8C; %Found: C, 41.05; H, 2.23;
N, 13.60. C7H5F3N2O2 requires C, 40.78; H, 2.43; N,
13.59%); nmax %Nujol) 3026, 1728, 1677, 1384, 1275,
1135, 1116 cm21; dF %56.4 MHz, CDCl3) 216.2 %CF3, d,
Jˆ9.2 Hz); dH %300 MHz, CDCl3) 5.81±5.91 %1H, m,
CF3CHvCH), 5.93 %1H, d, Jˆ8.2 Hz, pyrimidine-H), 7.40
%1H, d, Jˆ8.2 Hz, pyrimidine-H), 7.70 %1H, d, Jˆ14.7 Hz,
CF3CHvCH); m/z %EI) 206 %40, M1), 163 %100%).
Method B %for 4a±d): %Z)-enamine 3a±d %0.5 mmol) in tolu-
ene %2 mL) was treated with 40% BF3´OEt2 ether solution
%0.05 mmol) at room temperature for 1 h. The mixture was
poured into saturated NaHCO3 %10 mL) and extracted with
ethyl acetate %3£10 mL). After worked upas usual way, the
residue was The residue was subjected to ¯ash chroma-
tography on silica gel column eluting with ethyl acetate
and petroleum ether %1:15) to afford 4a±d.
4.1.11. 1-[ꢀZ)-3,3,3-Tri¯uoro-1-propenyl]-5-methyl-2,4
ꢀ3H)-pyrimidinedione ꢀ10a). Mp118 8C; %Found: C,
43.52; H, 2.93; N, 12.90. C8H7F3N2O2 requires C, 43.64;
H, 3.18; N, 12.73%); nmax %Nujol) 3181, 3032, 1728,
1674, 1209, 1148, 1109 cm21; dF %56.4 MHz, CD3COCD3)
218.5 %CF3, d, Jˆ9.1 Hz); dH %400 MHz, CD3COCD3) 1.89
%3H, s, CH3), 5.89±5.98 %1H, m, CF3CHvCH), 7.17 %1H, d,
Jˆ9.8 Hz, CF3CHvCH), 7.32 %1H, s, thymine-H); m/z %EI)
221 %20, M111), 220 %56, M1), 80 %100%).
4.2.1. N-[ꢀE)-3,3,3-Tri¯uoropropenyl]-N-propenyl-p-tol-
uenesulfonamide ꢀ4a). Colorless oil; %Found: C, 51.20; H,
4.68; N, 4.65. C13H14F3NO2S requires C, 51.14; H, 4.59; N,
4.59%); nmax %Nujol) 1688, 1365, 1272, 1169, 1115,
1092 cm21; dF %56.4 MHz, CDCl3) 217.8 %CF3, d, Jˆ
5.6 Hz); dH %300 MHz, CDCl3) 2.44 %3H, s, CH3), 4.01±
4.05 %2H, m, CH2CHvCH2), 4.60±4.92 %1H, m,
CH2CHvCH2), 5.14±5.21 %2H, m, CH2CHvCH2), 5.50±
5.61 %1H, m, CF3CHvCH), 7.34 %2H, d, Jˆ8.6 Hz, 2£Ph-
H), 7.57 %1H, d, Jˆ14.3 Hz, CF3CHvCH), 7.69 %2H, d,
Jˆ8.6 Hz, 2£Ph-H); m/z %EI) 305 %6, M1), 91 %100%).
4.1.12. 1-[ꢀE)-3,3,3-Tri¯uoro-1-propenyl]-5-methyl-2,4
ꢀ3H)-pyrimidinedione ꢀ10b). Mp182 8C; %Found: C,
43.80; H, 3.00; N, 12.66. C8H7F3N2O2 requires C, 43.64;
H, 3.18; N, 12.73%); nmax %Nujol) 3194, 3112, 3058,
1713, 1701, 1679, 1657, 1353, 1277, 1131, 1122 cm21; dF
%56.4 MHz, CDCl3) 216.5 %CF3, d, Jˆ9.0 Hz); dH %300
MHz, DMSO-d6) 1.83 %3H, s, CH3), 6.42 %1H, m,
CF3CHˆCH), 7.65 %1H, d, Jˆ14.8 Hz, CF3CHvCH),
4.2.2. N-[ꢀZ)-3,3,3-Tri¯uoropropenyl]-N-propanyl-p-tol-
uenesulfonamide ꢀ4b). Colorless oil; %Found: C, 51.04; H,

B. Jiang et al. / Tetrahedron 58 02002) 265±270
269
5.36; N, 4.58. C13H16F3NO2S requires C, 50.81; H, 5.21; N,
4.56%); nmax %Nujol) 1668, 1356, 1268, 1175, 1161, 1114,
1088 cm21; dF %56.4 MHz, CDCl3) 217.8 %CF3, d, Jˆ
6.0 Hz); dH %300 MHz, CDCl3) 0.90 %3H, t, Jˆ7.4 Hz,
CH3), 1.58±160 %2H, m, CH2), 2.44 %3H, s, CH3), 3.28
%2H, t, Jˆ7.7 Hz, CH2N), 4.80±4.85 %1H, m, CF3CHvCH),
7.34 %2H, dd, Jˆ8.5 Hz, Ph-H), 7.56 %1H, d, Jˆ14.2 Hz,
CF3CHvCH), 7.34 %2H, d, Jˆ8.5 Hz, Ph-H); m/z %EI) 307
%24, M1,), 287 %33), 155 %90), 91 %100%).
%CF3, d, Jˆ6.2 Hz); dH %300 MHz, CDCl3) 1.71±174 %2H,
m, CH2), 2.37 %2H, t, Jˆ6.5 Hz, CH2), 2.39 %4H, t, Jˆ
4.6 Hz, morpholinyl-H), 2.44 %3H, s, CH3), 3.41 %2H, t,
Jˆ7.4 Hz, CH2N), 3.68 %4H, t, Jˆ4.6 Hz, morpholinyl-H),
5.08±5.12 %1H, m, CF3CHvCH), 7.35 %2H, d, Jˆ8.4 Hz,
2£Ph-H), 7.55 %1H, d, Jˆ14.2, Hz, CF3CHvCH), 7.68 %2H,
d, Jˆ8.4 Hz, 2£Ph-H); m/z %EI) 392 %23, M1), 236 %29), 100
%100%).
4.2.3. N-[ꢀE)-3,3,3-Ti¯uoropropenyl]-N-hexanyl-p-tolu-
enesulfonamide ꢀ4c). Colorless oil; %Found: C, 54.89; H,
6.47; N, 4.11. C16H22F3NO2S requires C, 55.01; H, 6.31; N,
4.01%); nmax %Nujol) 1665, 1357, 1251, 1160, 1126, 1102
cm21; dF %56.4 MHz, CDCl3) 218.0 %CF3, d, Jˆ6.0 Hz); dH
%300 MHz, CDCl3) 0.87 %3H, t, Jˆ6.7 Hz, CH3), 1.25±1.29
%6H, m, 3£CH2), 1.51±1.57 %2H, m, CH2), 2.44 %3H, s,
CH3), 3.30 %2H, t, Jˆ7.7 Hz, CH2N), 4.77±4.85 %1H, m,
CF3CHvCH), 7.32 %2H, d, Jˆ7.9 Hz, 2£Ph-H), 7.54 %1H,
d, Jˆ15.0, CF3CHvCH), 7.67 %2H, d, Jˆ8.5 Hz, 2£Ph-H);
m/z %EI) 349 %3, M1), 265 %69), 155 %85), 91 %100%).
Acknowledgements
The research was supported by the Shanghai oversea
scholarshipand the national natural scienti®c foundation
of China.
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56.13; H, 3.92; N, 3.95. C16H14F3NO2S requires C, 56.30;
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1118 cm21; dF %56.4 MHz, CDCl3) 217.8 %CF3, d,
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6.1 Hz); dH %300 MHz, CD3COCD3) 2.43 %3H, s, CH3),
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H), 7.62 %1H, d, Jˆ14.2 Hz, CF3CHvCH), 7.69 %2H, d,
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propanyl]-p-toluenesulfonamide ꢀ4f). Colorless oil;
%Found: C, 49.98; H, 5.42; N, 4.03. C14H18F3NO3S requires
C, 49.85; H, 5.34; N, 4.15%); nmax %Nujol) 1666, 1359,
1266, 1168, 1116 cm21; dF %56.4 MHz, CDCl3) 218.0
%CF3, d, Jˆ6.2 Hz); dH %300 MHz, CDCl3) 1.81±1.89 %2H,
m, CH2), 2.44 %3H, s, CH3), 3.30 %3H, s, CH3O), 3.36 %2H, t,
Jˆ5.7 Hz, CH2), 3.43 %2H, t, Jˆ7.1 Hz, CH2), 5.00±5.04
%1H, m, CF3CHvCH), 7.34 %2H, d, Jˆ8.0 Hz, 2£Ph-H),
7.55 %1H, d, Jˆ14.3 Hz, CF3CHvCH), 7.68 %2H, d, Jˆ
8.0 Hz, 2£Ph-H); m/z %EI) 337 %2, M1), 182 %65), 124
%99), 100 %100%).
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linyl)propanyl]-p-toluenesulfonamide ꢀ4g). Colorless oil;
%Found: C, 52.11; H, 5.91; N, 7.40. C17H23F3N2O3S requires
C, 52.04; H, 5.87; N, 7.14%); nmax %Nujol) 1666, 1357,
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