An efficient stereoselective synthesis of fluorinated trisubstituted alkenes

Full text of DOI:10.1021/jo9807159

J . Org. Chem. 1998, 63, 7525-7528
7525
Lapworth have been reported the synthesis of ethyl
R-methylcinnamate from the reaction of benzylideneac-
etophenone and diethyl methylmalonate in the system
of powdered sodium-benzene under reflux.12 However,
no other examples have been reported to our knowledge.
To use the above system as a selective synthetic method
for trisubstituted alkenes, we have modified the starting
substrates and reaction conditions.
An Efficien t Ster eoselective Syn th esis of
F lu or in a ted Tr isu bstitu ted Alk en es
Tomoko Kawasaki, Tatsuro Ichige, and
Tomoya Kitazume*
Department of Bioengineering,
Tokyo Institute of Technology, Nagatsuta, Midori-ku,
Yokohama 226-8501, J apan
In the present reaction, when the reaction was at-
tempted at room temperature, the Michael addition
reaction proceeded except for entries 7, 9, and 10;
however, under refluxing the reaction pathway changed
from a Michael addition to a domino reaction to produce
the stereocontrolled alkenes. Table 1 summarized the
reaction of various types of donors with R,â-unsaturated
carbonyl compounds.
Received April 17, 1998
Several highly selective synthetic methods have been
developed which allow the preparation of various types
of materials with excellent regio-, stereo-, and chemose-
lectivity. In general, the usual synthetic procedure for
the target materials is the stepwise formation of the
individual bonds. While sequential syntheses (domino
reactions) that could form several bonds in one sequence
without isolating the intermediates, changing the reac-
tion conditions, or adding reagents have been recognized
as being useful in organic synthesis,1 their synthetic
value for alkenes2,3 and fluorinated alkenes still appears
to be grossly underestimated. In nonfluorinated chem-
istry, the Wittig-Horner reactions and/or tandem vicinal
difunctionalization reactions of alkynes are well-known
as stereoselective synthetic methods for tri- and tetra-
substituted alkenes.4 Further, fluorinated alkenes are
prepared from the Horner-Wadsworth-Emmons reac-
tion,5 addition-elimination of polyfluoroethenes,6 chlo-
rofluorocarbene,7 ethyl phenylsulfinylfluoroacetate,8
diethyl 2-oxo-3-fluorobutan-1,4-dioate,9 and organometal-
lics.10 Obviously, practical synthetic methods for stereo-
selective fluorinated alkenes remain an important syn-
thetic challenge.
The stereochemistry of products 2 was confirmed by
1H NMR coupling constants (J H-F) and chemical shifts
of the olefinic protons. It is well-known that the coupling
constant (J H-F) of the Z-isomer is 25-45 Hz and that J H-F
of the E-isomer is 10-20 Hz.13 Further, the signal of the
olefinic proton for the case of the carbonyl group in the
cis position is present in the area δ 6-7 ppm and that
for the trans position is present at δ 5.5-6 ppm.14 On
the basis of the coupling constant (J H-F ) ∼35 Hz) and
chemical shift of produced materials, the stereochemistry
of the obtained materials is that of the Z-isomer. In the
case of ethyl 3-fluoroalkyl-2-propenoates, the stereochem-
istry is that of the E-isomer on the basis of the signal
area (δ 6-7 ppm) of the olefinic proton.
Furthermore, this stereoselective synthesis of alkenes
was observed when R,â-unsaturated ketones and esters
were employed as acceptors (entries 16-21). For ex-
ample, in the case of R1 being Me (entries 16-18), the
influence of the substitution pattern of the Y group (from
methyl and phenyl to methoxy) directly appeared on the
reaction pathway. In sharp contrast to the present case,
it is interesting to note that the methyl substitutent
(entry 16) proceeds as the normal Michael addition
reaction in 59% yield. However, employment of the
phenyl substituent (R ) Ph, entry 19) and/or phenyl or
methoxy instead of methyl group (R1) turned out to
completely accelerate the desired reaction pathway to
furnish the alkene (entries 17-21). In the cases of
2-alkylmalonates (entries 24 and 25), the starting mate-
rial (2-alkylmalonate; 50% recovered in entry 24 and 53%
recovered in entry 25) was recovered after quenching the
reaction. From the above result, it seems that the
Michael addition reaction as a first step in this system
is not easy in entries 24 and 25. However, as the
carbon-carbon double bond modified by the fluoroalkyl
group is revealed to have a significantly lower LUMO
energy level than the corresponding nonfluorinated
In this article, we describe the domino reaction to open
a new avenue for the stereoselective construction of
fluorinated trisubstituted alkenes. The present domino
reaction summarized in Table 1 is the same as the
“abnormal” Michael reaction.11 In 1931, Holden and
(1) (a) Tietze, L. F. Chem. Rev. 1996, 96, 115.
(2) Maryanoff, B. E.; Reitz, A. B. Chem. Rev. 1989, 89, 863.
(3) (a) Zweifel, G.; Miller, J . A. Organic Reactions; J ohn Wiley &
Sons: New York, 1984; Vol. 32. (b) Etemad-Moghadam, G.; Seyden-
Penne, J . Tetrahedron 1984, 40, 5153. (c) Sreekumar, C.; Darst, K. P.;
Still, W. C. J . Org. Chem. 1980, 45, 4262.
(4) (a) Trost, B. M., Fleming, I., Semmelhack, M. F., Eds.; Compre-
hensive Organic Synthesis; Pergamon Press: Oxford, U.K., 1991; Vol.
1. (b) Normant, J .-F.; Alexakis, A. Synthesis 1981, 841. (c) Negishi,
E.; van Horn, D. E.; Yoshida, T.; Rand, C. L. Organometallics 1983, 2,
563. (d) Satoh, Y.; Serizawa, H.; Miyaura, N.; Hara, S.; Suzuki, A.
Tetrahedron Lett. 1988, 29, 1811.
(5) (a) Burton, D. J .; Yang, Z.-Y.; Qiu, W. Chem. Rev. 1996, 96, 1641
and references cited therein. (b) Tsai, H.-J .; Thenappan, A.; Burton,
D. J . J . Org. Chem. 1994, 59, 7085.
(6) (a) Martinet, P.; Sauvetre, R.; Normant, J .-F. Bull. Soc. Chim.
Fr. 1990, 127, 86. (b) Tozer, M. J .; Herpin, T. F. Tertahedron 1996,
52, 8619.
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1984, 40, 2871. (b) Bessiere, Y.; Savary, D. H.; Schlosser, M. Helv.
Chim. Acta 1977, 60, 1739.
(8) Allmendinger, T. Tetrahedron 1991, 47, 4905.
(11) Michael, A.; Ross, J . J . Am. Chem. Soc. 1930, 52, 4598.
(12) Holden, N. E.; Lapworth, A. J . Chem. Soc. 1931, 2368.
(13) (a) Gillet, J . P.; Sauveˆtre, R.; Normant, J .-F. Synthesis 1982,
297. (b) Xiao, L.; Kitazume, T. J . Fluorine Chem. 1997, 86, 99.
(14) (a) Pascual, C.; Meier, J .; Simon, W. Helv. Chim. Acta 1966,
49, 164. (b) Mori, K.; Matsui, M. Tetrahedron 1970, 26, 2801. (c)
Wadsworth, W. S.; Emmons, W. D. J . Am. Chem. Soc. 1961, 83, 1733.
(d) Instle, T. H.; Mandanas, B. Y. J . Chem. Soc., Chem. Commun. 1968,
1699.
(9) Ctemenceau, D.; Cousseau, J . Tetrahedron Lett. 1993, 34, 6903.
(10) (a) Ishihara, T.; Kuroboshi, M. Chem. Lett. 1987, 1145. (b)
Kuroboshi, M.; Yamada, N.; Takebe, Y.; Hiyama, T. Tetrahedron Lett.
1995, 36, 6271. (c) Burton, D. J .; Yang, Z.-Y.; Morken, P. A. Tetrahedron
1994, 50, 2993 and references cited. (d) Matthews, D. P.; Miller, S. C.;
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Fr. 1985, 448.
S0022-3263(98)00715-4 CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/01/1998

7526 J . Org. Chem., Vol. 63, No. 21, 1998
Ta ble 1. Ster eoselective Syn th esis of Tr isu bstitu ted Alk en es
Notes
product
no.
yield
(%)
E:Z
ratio
entry
R1
R2
R
X
Y
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
2a
2b
2c
2d
2e
2f
Me
Et
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Me
Me
H
H
H
H
H
H
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Et
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
Me
Me
Et
Me
Et
Me
Et
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
Me
30
71
68
63
38
0:100
2:98
0:100
3:97
0:100
0:100
0:100
0:100
0:100
0:100
0:100
9:91
n-Pr
i-Pr
n-Bu
t-Bu
n-Pent
n-Pent
Ph
29
2g
26a
9
2h
60a
46a
30
Ph
Ph
2i
2j
2k
2l
2a
CH3CH(OTBS)
CH3CH(OMOM)
CH3CH(Ph)
CH3CH(OTBS)CH2
Me
Me
Me
Ph
Ph
Ph
Ph
Ph
Ph
Ph
CF3
CF3
CHF2
CHF2
58
62
94
5:95
3:97
0:100
93
(59)d
50
Ph
OMe
Me
0:100
0:100
0:100
0:100
0:100
57
73
73
82
2h
Ph
OMe
t-Bu
t-Bu
Ph
2m
2n
2o
2h
2p
2q
2r
NRe
NRe
30f
13g
64b
55b
53c
51c
Et
Et
Et
Et
Et
Et
0:100
0:100
100:0
100:0
100:0
100:0
Ph
OEt
OEt
OEt
OEt
2s
a
Reactions were carried out under reflux except for entries 7, 9, and 10. Entries 7 and 9 were carried out at 0 °C, and entry 10 was
reacted at rt. Entries 26 and 27 were carried out at -40 °C. c Entries 28 and 29 were reacted at 0 °C at rt. Yield of the normal Michael
b
d
addition reaction. e Recovered the starting material. f Recovered starting material: 50%. Recovered starting material: 53%.
g
Sch em e 1. Rea ction Mech a n ism of th e P r esen t
materials, which demonstrates the higher electrophile
Dom in o Rea ction
reactivity,15 employment of 3-fluoromethyl-2-propenoates
accelerated the Michael addition reaction pathway to
furnish the desired alkenes (entries 26-29).
When we examined the above reaction using NCCH2-
CO2Et or CH2(CO2Et)2 as a donor, the target alkene was
not obtained, and (Z)-olefin MeCH(OTBS)CHdCHCO2-
Me as an acceptor was recovered. Further, entries 22
and 23 suggest that this synthetic process did not work
for the preparation of tetrasubstituted alkene.
In the next stage, we tried to reveal the reaction
pathway (Scheme 1). In this system, it is important to
note that two kinds of products, such as fluorinated R,â-
unsaturated esters 2 and â-keto esters, are obtained.
Further, diethyl malonate as the donor only produced a
Michael addition product, and this observation might be
explained by the formation of a stable intermediate by
the proton transfer of malonate (proton transfer from
In t-A to In t-E) to produced a Michael addtion product
3, which led us to conclude that 2-substituted malonates
were required as a donor in the present domino reaction.
Moreover, to make clear the conversion to In t-C by the
elimination of RONa from In t-B, ethyl R-methyl cin-
namate as an acceptor to deter the path c only produced
methyl (Z)-3-phenyl-2-fluoropropenoate (2h ). From the
above results, the mechanism of the present reaction was
explained as follows. The path a was one possible route
for conversion to compound 4 by the elimination of
the ketone carbonyl group of cyclobutanone 4, accelerat-
ing the C-C bond dissociation of cyclobutanone to furnish
In t-D (TS-A). The other route was path b which involved
conversion directly from In t-B to In t-D.
MeONa from In t-B and then alkoxide anion attack on
(15) Shinohara, N.; Haga, J .; Yamazaki, T.; Kitazume, T. J . Org.
Chem. 1995, 60, 4363.

Notes
The stereoselective synthesis of alkenes described
above was thus attributed to the bulkiness of substituent
groups and the anti elimination reaction process via TS-
A.
J . Org. Chem., Vol. 63, No. 21, 1998 7527
NMR: δ 36.1 (d, J ) 35.1 Hz). 13C NMR: δ 52.4 (s), 117.6 (d, J
) 4.60 Hz), 127.9 (s), 128.7 (s), 129.6 (d, J ) 2.80 Hz), 130.2 (d,
J ) 8.10 Hz), 130.9 (d, J ) 4.30 Hz), 146.6 (d, J ) 267 Hz),
161.7 (d, J ) 34.5 Hz). Anal. Calcd for C10H9FO2: C, 66.66; H,
5.03. Found: C, 66.78; H, 5.25.
As depicted in the several types of combinations shown
in Table 1, we have found that this process was a
convienient synthetic procedure for production of fluori-
nated trisubstituted alkenes.
Meth yl 2-F lu or o-4-[(ter t-bu tyld im eth ylsilyl)oxy]-2-p en -
ten oa te (2i). 1H NMR: δ 0.05 (s), 0.07 (s), 0.88 (s), 1.29 (3 H,
d, J ) 6.00 Hz), 3.84 (s), 4.81 (1 H, qd, J ) 8.00, 1.50 Hz), 6.13
(dd, J ) 33.5, 8.50 Hz). 19F NMR: Z-isomer, δ 32.8 (d, J ) 33.4
Hz); E-isomer, 36.5 (d, J ) 19.7 Hz). 13C NMR: δ -5.09 (s),
-4.94 (s), 18.0 (s), 25.7 (s), 26.0 (s × 3), 52.4 (s), 62.4 (d, J )
3.10 Hz), 124.9 (d, J ) 9.50 Hz), 145.3 (d, J ) 257 Hz), 161.1 (d,
J ) 36.0 Hz). Anal. Calcd for C13H23FO3Si: C, 54.93; H, 8.83.
Found: C, 54.67; H, 8.98.
Meth yl 2-Flu or o-4-[(1-m eth oxym eth yl)oxy]-2-pen ten oate
(2j). 1H NMR: Z-isomer, δ 1.33 (3 H, d, J ) 6.59 Hz), 3.37 (3 H,
s), 3.83 (3 H, s), 4.59 (1 H, d, J ) 6.84 Hz), 4.62 (1 H, dd, J )
6.83, 0.49 Hz), 4.73 (1 H, quint d, J ) 6.59, 0.98 Hz), 6.10 (1 H,
dd, J ) 33.2, 8.54 Hz). 19F NMR: Z-isomer, δ 34.6 (d, J ) 32.0
Hz); E-isomer, 40.4 (d, J ) 19.8 Hz). 13C NMR: Z-isomer, δ
20.5 (d, J ) 1.90 Hz), 55.2 (s), 65.5 (s), 94.5 (s), 121.8 (d, J )
9.80 Hz), 147.2 (d, J ) 260 Hz), 160.7 (d, J ) 35.7 Hz). Anal.
Calcd for C8H13FO4: C, 50.00; H, 6.82. Found: C, 50.09; H, 6.78.
Meth yl 2-F lu or o-4-p h en yl-2-p en ten oa te (2k ).10e 1H NMR:
Z-isomer, δ 1.44 (3 H, d, J ) 6.84 Hz), 3.81 (3 H, s), 4.04 (1 H,
dq, J ) 10.8, 7.08 Hz), 6.27 (1 H, dd, J ) 32.5, 10.3 Hz), 7.29 (5
H, m). 19F NMR: Z-isomer, δ 31.0 (d, J ) 33.6 Hz); E-isomer,
δ 38.1 (d, J ) 21.4 Hz). 13C NMR: Z-isomer, δ 20.8 (s), 34.9 (s),
52.3 (s), 124.9 (d, J ) 10.9 Hz), 126.7 (s), 126.8 (s), 128.7 (s),
143.3 (s), 146.3 (d, J ) 256 Hz), 161.2 (d, J ) 35.7 Hz). Anal.
Calcd for C11H13FO2: C, 67.33; H, 6.68. Found: C, 67.71; H,
6.38.
Exp er im en ta l Section
Gen er a l Meth od s. All commercially available reagents were
used without further purification. Chemical shifts of 1H (500
MHz and/or 300 MHz) and 13C NMR (50 MHz) spectra were
recorded in ppm (δ) downfield from the internal standard of Me4-
Si, δ 0.00, in CDCl3. The 19F (470 or 280 MHz) NMR spectra
were recorded in ppm downfield from internal standard of C6F6
in CDCl3 using a VXR 500 or a VXR 300 instrument.
Meth yl (Z)-3-Su bstitu ted 2-flu or o-2-p r op en oa te (2). To
a solution of NaH (0.08 g, 2 mmol) and THF (2 mL), dimethyl
2-fluoromalonate (0.30 g, 2 mmol) in dried THF (2 mL) was
added at 0 °C under a nitrogen atmosphere, and then the
mixture was stirred for 30 min at that temperature. To the
above solution, R,â-unsaturated tert-butyl ketone (2 mmol) was
added, and the whole batch was refluxed for 4 h under a nitrogen
atmosphere. After the reaction was quenched with ice water,
oily materials were extracted with diethyl ether (3 × 15 mL),
and the ethereal extract was washed with brine (3 × 10 mL)
and dried over MgSO4. On removal of the solvent, the yield was
determined by the 19F NMR integral intensities using hexafluo-
robenzene as an internal stadard. The resultant crude product
was purified by chromatography on silica gel.
Meth yl (Z)-2-F lu or o-5-[(ter t-bu tyld im eth ylsilyl)oxy]-2-
h ep ten oa te (2l). 1H NMR: δ 0.04 (3 H, s), 0.05 (3H, s), 0.88 (9
H, s), 1.16 (3 H, d, J ) 6.10 Hz), 2.36 (2 H, dt, J ) 7.81, 1.96
Hz), 3.82 (s), 3.93 (1 H, sex., J ) 5.86 Hz), 4.18 (2 H, q), 6.21 (1
Meth yl (Z)-2-F lu or o-2-bu ten oa te (2a ).9 1H NMR: δ 1.80
(3 H, dd, J ) 7.50, 3.00 Hz), 3.82 (3 H, s), 6.18 (1 H, dq, J )
33.0, 7.25 Hz). 19F NMR: δ 30.0 (dq, J ) 32.0, 3.06 Hz). 13C
NMR: δ 9.47 (d, J ) 4.20 Hz), 52.1 (s), 148.5 (d, J ) 255 Hz),
161.0 (d, J ) 35.5 Hz).
H, dt, J ) 32.1, 7.81 Hz). 19F NMR: δ 30.2 (d, J ) 32.1 Hz). 13
C
NMR: δ -5.06 (s), -4.71 (s), 17.9 (s), 23.5 (s), 25.6 (s × 3), 34.2
(s), 53.4 (s), 67.2 (s), 117.6 (d, J ) 11.5 Hz), 148.3 (d, J ) 252
Hz), 161.0 (d, J ) 35.7 Hz). Anal. Calcd for C14H25FO3Si: C,
56.49; H, 9.12. Found: C, 56.31; H 8.83.
Meth yl (Z)-2-F lu or o-2-p en ten oa te (2b).9 1H NMR: δ 1.07
(3 H, t, J ) 7.57 Hz), 2.27 (2 H, dquint, J ) 7.57, 2.20 Hz), 3.82
(3 H, s), 6.13 (1 H, dt, J ) 33.5, 7.82 Hz). 19F NMR: δ 30.1 (d,
J ) 33.6 Hz). 13C NMR: δ 17.7 (d, J ) 3.30 Hz), 26.0 (d, J )
2.60 Hz), 52.2 (s), 122.4 (d, J ) 11.7 Hz), 147.3 (d, J ) 254 Hz),
161.3 (d, J ) 35.4 Hz).
Eth yl (E)-3-(Tr iflu or om eth yl)-2-m eth yl-2-pr open oate (2p).
To a solution of NaH (0.08 g, 2 mmol) and THF (2 mL), diethyl
2-methylmalonate (2 mmol) in dried THF (2 mL) was added at
0 °C under a nitrogen atmosphere, and then the mixture was
stirred for 30 min at that temperature. To the above solution,
ethyl 3-(trifluoromethyl)-2-propenoate (4 mmol) was added, and
the whole batch was stirred at -78 to -40 °C for 4 h under a
nitrogen atmosphere. After quenching with ice water, oily
materials were extracted with diethyl ether (3 × 15 mL) and
the ethereal extract was washed with brine (3 × 10 mL) and
dried over MgSO4. On removal of the solvent, the yield was
determined by the 19F NMR integral intensities using hexafluo-
robenzene as an internal stadard. The resultant crude product
was purified by chromatograph on silica gel. 1H NMR: δ 1.33
(3 H, t, J ) 7.14 Hz), 2.10 (3 H, dq, J ) 2.50, 1.65 Hz), 4.27 (2
H, q, J ) 7.14 Hz), 6.68 (1 H, qq, J ) 8.24, 1.65 Hz). 19F NMR:
δ 102.4 (dq, J ) 8.60, 2.60 Hz). 13C NMR: δ 13.4 (s), 13.9 (s),
61.8 (s), 122.9 (q, J ) 267 Hz), 125.8 (q, J ) 34.8 Hz), 139.7 (q,
J ) 5.40 Hz), 165.9 (s). Anal. Calcd for C7H9F3O2: C, 46.16;
H, 9.82. Found: C, 45.94; H, 4.82.
Eth yl (E)-3-(Tr iflu or om eth yl)-2-eth yl-2-p r op en oa te (2q).
1H NMR: δ 1.10 (3 H, t, J ) 7.42 Hz), 1.34 (3 H, t, J ) 7.14 Hz),
2.53 (2 H, qq, J ) 7.42, 1.37 Hz), 4.27 (2 H, q, J ) 7.14 Hz), 6.61
(1 H, q, J ) 8.51 Hz). 19F NMR: δ 102.9 (dt, J ) 8.62, 1.73 Hz).
13C NMR: δ 13.4 (s), 13.9 (s), 21.3 (s), 61.7 (s), 122.9 (q, J ) 272
Hz), 125.2 (q, J ) 35.1 Hz), 145.6 (t, J ) 4.60 Hz), 165.6 (s).
Anal. Calcd for C8H11F3O2: C, 48.98; H, 5.65. Found: C, 48.59;
H, 5.73.
Eth yl (E)-3-(Diflu or om eth yl)-2-m eth yl-2-pr open oate (2r ).
1H NMR: δ 1.15 (3 H, t, J ) 7.14 Hz), 1.82 (3 H, dt, J ) 1.65,
1.37 Hz), 4.07 (2 H, q, J ) 7.14 Hz), 6.25 (1 H, dt, J ) 54.9, 6.32
Hz), 6.49 (1 H, qdt, J ) 8.24, 4.95, 1.37 Hz). 19F NMR: δ 48.5
(ddq, J ) 55.2, 9.47, 2.59 Hz). 13C NMR: δ 12.9 (s), 13.9 (s),
61.4 (s), 111.9 (t, J ) 233 Hz), 130.3 (t, J ) 26.4 Hz), 136.5 (t,
J ) 11.2 Hz), 166.3 (s). Anal. Calcd for C7H10F2O2: C, 51.22;
H, 6.14. Found: C, 51.54; H, 6.49.
Meth yl (Z)-2-F lu or o-2-h exen oa te (2c).10a 1H NMR: δ 0.95
(3 H, t, J ) 7.50 Hz), 1.48 (2 H, sex., J ) 7.00 Hz), 2.23 (2 H, dq,
J ) 7.50, 2.00 Hz), 3.82 (3 H, s), 6.13 (1 H, dt, J ) 33.5, 8.00
Hz,). 19F NMR: δ 30.5 (d, J ) 33.6 Hz). 13C NMR: δ 13.4 (s),
26.0 (d, J ) 2.60 Hz), 52.1 (s), 120.6 (d, J ) 11.6 Hz), 147.7 (d,
J ) 254 Hz), 161.1 (d, J ) 35.4 Hz).
Meth yl (Z)-2-F lu or o-4-m eth yl-2-p en ten oa te (2d ).10a 1H
NMR: δ 1.06 (3 H, s), 1.07 (3 H, s), 2.86 (1 H, dsept, J ) 6.83,
0.97 Hz), 3.81 (3 H, s), 5.99 (1 H, dd, J ) 33.7, 9.77 Hz). 19F
NMR: δ 29.9 (d, J ) 33.6 Hz). 13C NMR: δ 21.7 (s), 24.3 (d, J )
2.10 Hz), 52.0 (s), 127.1 (d, J ) 11.1 Hz), 140.1 (d, J ) 254 Hz),
161.2 (d, J ) 35.8 Hz).
Meth yl (Z)-2-F lu or o-2-h ep ten oa te (2e).9 1H NMR: δ 0.92
(3 H, t, J ) 7.50 Hz), 1.36 (2 H, m), 1.43 (2 H, m), 2.25 (2 H, qd,
J ) 7.50, 2.00 Hz), 3.82 (3 H, s), 6.13 (1 H, dt, J ) 33.5, 7.50
Hz). 19F NMR: δ 30.4 (d, J ) 33.4 Hz). 13C NMR: δ 13.7 (s),
22.2 (s), 23.9 (d, J ) 2.70 Hz), 30.4 (s), 52.3 (s), 121.1 (d, J )
11.9 Hz), 147.7 (d, J ) 255 Hz), 161.3 (d, J ) 35.7 Hz).
Meth yl (Z)-2-F lu or o-4,4-d im eth yl-2-p en ten oa te (2f).10a
1H NMR: δ 1.19 (9 H, d, J ) 0.94 Hz), 3.80 (s), 6.07 (d, J ) 38.5
Hz). 19F NMR: δ 32.8 (d, J ) 38.1 Hz). 13C NMR: δ 29.5 (d, J
) 3.4 Hz), 32.1 (d, J ) 1.9 Hz), 52.2 (s), 129.2 (d, J ) 6.7 Hz),
146.3 (d, J ) 256 Hz), 161.8 (d, J ) 35.8 Hz).
Meth yl (Z)-2-F lu or o-2-octen oa te (2g).8 1H NMR: δ 0.89
(3 H, t, J ) 7.00 Hz), 1.31 (4 H, m), 1.44 (2 H, quint, J ) 7.00
Hz), 2.24 (2 H, qd, J ) 7.50, 2.50 Hz), 3.81 (3 H, s), 6.12 (1 H,
dt, J ) 33.5, 8.00 Hz). 19F NMR: Z-isomer, δ 28.6 (d, J ) 30.1
Hz); E-isomer, δ 36.2 (d, J ) 19.7 Hz). 13C NMR: δ 13.8 (s),
22.2 (s), 24.1 (d, J ) 2.70 Hz), 27.9 (s), 31.2 (s), 52.1 (s), 121.0
(d, J ) 11.7 Hz), 147.6 (d, J ) 255 Hz), 161.2 (d, J ) 35.5 Hz).
Meth yl (Z)-2-F lu or ocin n a m a te (2h ).10a 1H NMR: δ 3.83
(3 H, s), 6.86 (1 H, d, J ) 35.2 Hz), 7.32-7.58 (5 H, m). 19F

7528 J . Org. Chem., Vol. 63, No. 21, 1998
Notes
Eth yl (E)-3-(Diflu or om eth yl)-2-eth yl-2-p r op en oa te (2s).
1H NMR: δ 1.10 (3 H, t, J ) 7.69 Hz), 1.33 (3 H, t, J ) 7.15 Hz),
2.43 (2 H, qt, J ) 7.42, 1.65 Hz), 4.26 (2 H, q, J ) 7.14 Hz), 6.43
Su p p or tin g In for m a tion Ava ila ble: NMR spectra (6
pages). This material is contained in libraries on microfiche,
immediately follows this article in the microfilm version of the
journal, and can be ordered from the ACS; see any current
masthead page for ordering information.
(1 H, td, J ) 55.2, 6.32 Hz), 6.61 (1 H, td, J ) 9.34, 6.32 Hz). 19
F
NMR: δ 49.4 (ddt, J ) 54.3, 10.3, 1.72 Hz). 13C NMR: δ 12.9 (s),
14.0 (s), 20.8 (s), 61.3 (s), 111.7 (t, J ) 233 Hz), 129.8 (t, J )
26.6 Hz), 142.6 (t, J ) 11.7 Hz), 166.0 (s). Anal. Calcd for
C8H12F2O2: C, 53.93; H, 6.79. Found: C, 53.95; H, 6.48.
J O9807159