Synthetic Applications of the Carbanion with a Fluoroalkyl Group Generated by Palladium(0) Catalyst under Neutral Conditions

Article abstract of DOI:10.1021/jo990463r

The generation and synthetic application of stable carbanions situated in the β position from fluorine atom(s) are described. Palladium(0)-catalyzed allylation reactions under neutral conditions proceeded smoothly in the system where a methylene group is activated by fluoroalkyl and carbonyl groups. In the above systems, the 2,2,2-trifluoroethyl moiety has been introduced onto the allylic position without the release of fluoride. Further, palladium(0)-catalyzed heterocyclization was achieved from the reaction of vinyl epoxide with 2-(trifluoromethyl)acrylate and/or 2,3,3,3-tetrafluoropropionate.

Full text of DOI:10.1021/jo990463r

J . Org. Chem. 1999, 64, 8369-8374
8369
Syn th etic Ap p lica tion s of th e Ca r ba n ion w ith a F lu or oa lk yl Gr ou p
Gen er a ted by P a lla d iu m (0) Ca ta lyst u n d er Neu tr a l Con d ition s
Yuzo Komatsu, Toru Sakamoto, and Tomoya Kitazume*
Department of Bioengineering, Tokyo Institute of Technology, Nagatsuta, Midori-ku,
Yokohama 226-8501, J apan
Received March 15, 1999
The generation and synthetic application of stable carbanions situated in the â position from fluorine
atom(s) are described. Palladium(0)-catalyzed allylation reactions under neutral conditions
proceeded smoothly in the system where a methylene group is activated by fluoroalkyl and carbonyl
groups. In the above systems, the 2,2,2-trifluoroethyl moiety has been introduced onto the allylic
position without the release of fluoride. Further, palladium(0)-catalyzed heterocyclization was
achieved from the reaction of vinyl epoxide with 2-(trifluoromethyl)acrylate and/or 2,3,3,3-
tetrafluoropropionate.
The chemistry of â-fluorocarbanions, which do not
undergo elimination to form fluoroolefins, has not been
studied in detail.1 The synthesis and chemical reactivity
of such carbanions are of considerable interest. The
generation and synthetic applications of these carbanions
have been based on several methods: (1) use of nitrotri-
fluoroethane and n-BuLi,2 (2) employment of dimethyl
2-trifluoromethyl malonate and/or dialkyl 2-bromo-2-
difluoromethyl malonate,3 (3) application of R-CF3-silyl-
enol ether and Reformatsky-type reactions of bromotri-
fluoropropionate,4 (4) use of 2,3,3,3-tetrafluoropropionate
and 2,3,3,3- tetrafluoropropionamide,5 and (5) indium-
mediated allylation using 1,1,1-trifluoro-4-bromo-2-butene.6
In these reports, the only electrophiles utilized were
acetals, acid chlorides, and aldehydes, and to our knowl-
edge no other electrophiles have been successfully uti-
lized. Moreover, in the cases of (1) and (4), employment
of alkyl halides instead of aldehydes accelerated the
release of fluoride ion to furnish the olefin. Obviously,
practical generation for â-fluorocarbanions remains an
important synthetic challenge. Although palladium-
catalyzed allylation reactions under neutral condition
have been recognized to be useful for organic synthesis,7
their synthetic value in fluorine chemistry still appears
to be grossly underestimated.8
In this paper, we describe the generation and synthetic
applications of â-fluorocarbanions derived from a meth-
ylene group activated with fluoroalkyl and carbonyl
groups.
Resu lts a n d Discu ssion
Allyla tion Rea ction . Pd(PPh3)4 was used under neu-
tral conditions in the reaction of ethyl 3,3,3-trifluoropro-
pionate with cinnamyl carbonate in tetrahydrofuran to
obtain ethyl 2-trifluoromethyl-5-phenyl-4-pentenoate in
29% yield with SN2 regioselectivity. Moreover, this
Pd(0)-catalyzed allylation reaction did not proceed under
basic conditions. In this reaction type, an important factor
is to find a match between the Pd(0) catalyst and
additives to increase the chemical yield. Therefore,
we examined several palladium(0) catalysts and the
effect of additives. The Pd(dba)2‚CHCl3-2dppe system
increased the chemical yield to 50%, and bisallylation
product decreased to 13% yield. However, there are
numerous disadvantages associated with the above
approach, e.g., the yield is not high and bisallylated
product is a major byproduct. To obviate these disadvan-
tages, molecular sieves (5A) and binap were substituted
for dppe (entry 4, Table 1, Scheme 1); the chemical yield
increased to 61% while bisallylation product decreased
to 8% yield.
(1) (a) Filler, R.; Kobayashi, Y. Biomedicinal Aspects of Fluorine
Chemistry; Kodansha & Elsevier Biomedical: Tokyo, 1982. (b) Kita-
zume, T.; Yamazaki, T. Experimental Methods in Organic Fluorine
Chemistry; Kodansha & Gordon and Breach Science: Tokyo, 1998. (c)
Hudlicky, M.; Pavlath, A. E. Chemistry of Organic Fluorine Compounds
II: a Critical Review; American Chemical Society: Washington, DC,
1995.
(2) Seebach, D.; Beck, A. K.; Renaud, P. Angew. Chem., Int. Ed. Engl.
1986, 25, 98.
(3) (a) Ishikawa, N.; Yokozawa, T. Bull. Chem. Soc. J pn. 1983, 56,
724. (b) Everett, T. S.; Purrington, S. T.; Bumgardner, C. L. J . Org.
Chem. 1984, 49, 3702.
(4) (a) Yokozawa, T.; Yamaguchi, M.; Nakai, T.; Ishikawa, N. Nippon
Kagaku Kaishi 1985, 2202. (b) Yokozawa, T.; Nakai, T.; Ishikawa, N.
Tetrahedron Lett. 1984, 25, 3987. (c) Yokozawa, T.; Nakai, T.; Ishikawa,
N. Tetrahedron Lett. 1984, 25, 3991.
(5) (a) Kuroboshi, M.; Ishihara, T. Bull. Chem. Soc. J pn. 1990, 63,
1191. (b) Ishihara, T.; Kuroboshi, M.; Yamaguchi, K. Chem. Lett. 1990,
211. (c) Qian, C.-P.; Nakai, T. Tetrahedron Lett. 1990, 31, 7043.
(6) Loh, T.-P.; Li, X.-R. Tetrahedron Lett. 1997, 38, 869.
(7) (a) Lipshutz, B. H.; Sengupta, S. Organic Reactions; Paquette,
L. A., Ed.; J ohn Wiley & Sons: New York, 1992; Vol. 41, p 135. (b)
Tsuji, J . Palladium Reagents and Catalysts; J ohn Wiley & Sons: New
York, 1996.
Molecular sieves (5A) are acceptable to trap ethanol
generated from the carbonate group via the η3-allyl
system. The cis and/or trans stereochemistry was con-
1
firmed using H NMR coupling constants. The reaction
is effective with both primary and secondary allylic
carbonates. In the case of secondary carbonate PhCH-
(OCO2Et)CHdCH2 (entry 5), the allylation reaction pro-
ceeded to afford the SN2′ allylation product in 66% yield.
Regioisomeric carbonates produce only 3 (see entries 4
and 6-8).
Furthermore, in entries 9-20 (Table 2, Scheme 2),
2-fluoro-, 2-methyl, and/or 2-benzyloxy-3,3,3-trifluoro-
(8) (a) Fuchikami, T.; Yatabe, M.; Ojima, I. Synthesis 1981, 365. (b)
Fuchikami, T.; Ohishi, K.; Ojima, I. J . Org. Chem. 1983, 48, 3803. (c)
Heimze, P. L.; Burton, D. J . J . Org. Chem. 1988, 53, 2714. (d)
Fuchikami, T.; Shibata, Y.; Urata, H. Chem. Lett. 1987, 521.
10.1021/jo990463r CCC: $18.00 © 1999 American Chemical Society
Published on Web 10/01/1999

8370 J . Org. Chem., Vol. 64, No. 22, 1999
Komatsu et al.
Sch em e 1a
a
a ) Pd2(dba)3CHCl3-2 binap (5 mol %), MS-5A, THF, 50 °C.
Ta ble 1. P a lla d iu m (0)-Ca ta lyzed Allyla tion Rea ction
allylcarbonates
yield (%)
F igu r e 1. Pd(0)-catalyzed reaction system.
reaction
time (h)
entry
R1 R2
3 (E:Z ratio)
4
Sch em e 3. Syn th etic Rou te to Dien e
1
2
3
4
5
6
7
8
H
H
H
Me
H
Ph
H
6
10
20
6
6
8
70 (3a )a
6 (4a )
(9)b
0
Me
Me
Ph
H
51 (3b) (96:4)
17 (3c) [63:37]c
61 (3d ) (100:0) 8 (4d )
66 (3d ) (100:0) 13 (4d )
67 (3e) (100:0)
66 (3e) (100:0)
61 (3f) (100:0)
Pre
Prf
0
H
8
8
0
PhCH2CH2
H
26d
a
Compound number. b SN2′ allylation product. c Diastereomeric
d
ratio in the parenthesis. PhCH2CHdCH2 was obtained in 26%
yield. e (E) isomer. f (Z) isomer.
Sch em e 2a
a
a ) Pd(dppe)2 (5 mol %), MS-5A, THF, 50 °C.
Ta ble 2. P a lla d iu m (0)-Ca ta lyzed Allyla tion Rea ction
carbonates
R1 R2
yield
reaction
time (h)
entry
R
5 (E:Z ratio)
6
9
10
11
12
13
14
15
16
17
18
19
20
H
H
H
Me
H
H
H
Me
H
H
H
F
F
F
F
Me
Me
Me
Me
OBn
OBn
OBn
OBn
3
4
7
3
7
12
24
8
3
4
94 (5a )a
0
Me
Me
Ph
H
Me
Me
Ph
H
74 (5b) (85:15)
73 (5c) [51:49]c
98 (5d ) (100:0)
79 (5e)
29 (5f) (100:0)
21 (5g) (57:43)c
75 (5h ) (100:0)
97 (5i)
(26)b
0
0
0
(16)b
0
0
Et. Finally, reductive elimination from In t-B produces
the SN2 allylation product as the main product.
In the case of the cyclohexane system shown in Scheme
3, the formation of diene 10 can be rationalized via
stereospecific anti elimination of the elements LnPd(X)-H
from an intermediate such as In t-D. However, the anti
elimination of the Pd complex from In t-C is not reason-
able, probably because of the steric repulsion between
Pd-metal and the cyclohexane ring to produce the diene
8. On the basis of these considerations, the allylation
product 7 was obtained as the main one from In t-C, and
the diene 10 was produced from In t-D.
Elim in a tion Rea ction . In the case of the Pd(0)-
catalyzed reaction of 2-substituted 3,3-difluoropropi-
onates 11(Table 3, Scheme 4), release of fluoride ion
instead of the allylation reaction was observed to produce
(E)-3-fluoro-2-substituted-2-alkenoic acid esters as single
stereoisomers.9 The difference in stability between the
carbanion attached with CF3 and that with the CHF2
group may be due to the fact that the C-F bond length
Me
Me
Ph
80 (5j) (85:15)
54 (5k ) [57:43]c
98 (5l) (100:0)
Me
H
8
3
a
b
Compound number. Yield of SN2' allylation product. c Dias-
tereomeric ratio in the parenthesis.
propionates in the presence of Pd(dppe)2-MS-5A without
binap reacted smoothly to produce the corresponding
allylic product in this system.
The mechanism of the above palladium(0)-catalyzed
allylation reaction is explained as follows. In the case of
neutral conditions, alkoxide anion in the possible inter-
mediate In t-A reacts with the activated methylene group
in substrate (RCH(RF)CO2Et), resulting in the formation
of intermediate In t-B (Figure 1). In this reaction step, it
appears that free â-carbanion with a fluoromethyl group,
-
such as CR(RF)CO2Et, is not generated and that the EtO
ligand on the palladium atom is replaced by CR(RF)CO2-

Synthetic Applications of â-Fluorocarbanions
J . Org. Chem., Vol. 64, No. 22, 1999 8371
Sch em e 4. Ster eoselective Syn th esis of
Tr isu bstitu ted Alk en es
Sch em e 5. Cycliza tion Rea ction w ith P d (0)
Ca ta lyst
Ta ble 3. Syn th esis of F lu or in a ted Alk en es
reaction
entry compd no.
X
R
time (h) yield (%)
22
23
24
12a
12b
12b
Me
OBn
OBn
CH2CH2Ph
Et
Et
10
6
10
71
83
64
Pd(dppe)2, reacts with the activated methylene group in
the substrate (CHF2CH(R)CO2Et′), resulting in the for-
mation of intermediate In t-E. The release of fluoride
from In t-E leads to the formation of (E)-3-fluoro-2-
substituted-2-alkenoic acid esters. Finally, the active
ethoxide ion was regenerated when diethyl carbonate is
attacked by fluoride ion. Obviously, in this process,
molecular sieves (5A) are acceptable to trap the ethanol
generated from the carbonate group.
F igu r e 2. Reaction mechanism of the present elimination
reaction.
The stereoselective synthesis of alkenes described
above was thus attributed to the bulkiness of substituent
groups and the anti elimination reaction process via
TS-E. As depicted in the several types of combinations
shown in Table 3, we have found that this process
provides a convienient synthetic route to fluorinated
trisubstituted alkenes.
in the CHF2 group is longer than that of CF3 group.10
The stereochemistry of the product was confirmed by the
chemical shift of the olefinic proton (CHFdC(R)CO2R′),
because the signal from the olefinic proton in the (Z)
isomer occurs in the region δ ) 5.50-6.00 ppm, and that
of the (E) isomer is at δ ) 6.80-7.50.11 On the basis of
the chemical shift (δ ) 7.20-7.50) and coupling constant
(J H-F ≈ 70-80 Hz), the product was identified as the (E)
isomer. When the reaction was attempted in the presence
of other bases (lithium or Grignard reagents), the target
olefins did not form. Moreover, this Pd(0)-catalyzed olefin
synthesis also failed to proceed under basic conditions.
To clarify the reaction mechanism of this palladium(0)-
catalyzed olefin synthesis, we have examined the reaction
system using substrate 11 (1 equiv), a catalytic amount
of allyl carbonate (0.1 equiv), and Pd(dppe)2 (0.05 equiv)
in the presence of diethyl carbonate (1.2 equiv). A
proposed mechanism for the eliminated reaction is shown
in Figure 2. Under neutral conditions, ethoxide anion,
generated from the reaction of allyl carbonate and
Cycliza tion Rea ction . It is well established that
fluoride ion is eliminated from the carbanion generated
by nucleophilic attack on the substituted 2-(trifluoro-
methyl)-acrylate 13 to form the difluoroolefin. Therefore,
we examined the intramolecular cyclization reaction of
the generated carbanion as an activated reaction inter-
mediate (Scheme 5). After forming the π-allylpalladium
complex of vinyl epoxide 14, Pd-complex-O nucleophile
attacked the carbon-carbon double bond of 13 to gener-
ate the corresponding â-fluoro carbanion. Pd-catalyzed
intramolecular allylation of the carbanion gave the five-
membered heterocyclic compound 15. Further, in the case
of the π-allylpalladium complex of vinyl epoxide 14, ethyl
2,3,3,3-tetrafluoropropionate formed the cyclic compound
17 via nucleophilic attack and intramolecular cyclization
of trifluoroolefin 16, generated by the release of fluoride
from the â-fluorocarbanion.
(9) (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. (c) Tozer, M. J .; Herpin, T. F.
Tetrahedron 1996, 52, 8619. (d) Ctemenceau, D.; Cousseau, J . Tetra-
hedron Lett. 1993, 34, 6903. (e) Ishihara, T.; Kuroboshi, M. Chem. Lett.
1987, 1145. (f) Burton, D. J .; Yang, Z.-Y.; Morken, P. A. Tetrahedron
1994, 50, 2993 and references cited. (g) Kawasaki, T.; Ichige, T.;
Kitazume, T. J . Org. Chem. 1998, 63, 7525 and references therein.
(10) Wiberg, K. B.; Rablen, P. R. J . Am. Chem. Soc. 1993, 115, 614.
(11) Silverstein, R. M.; Bassler, G. C. Spectrometric Identification
of Organic Compounds; J ohn Wiley & Sons: New York, 1967.
In conclusion, we have described methods for the
generation of stable carbanions in the â-position to a
trifluoromethyl group by palladium(0)-catalyzed allyla-
tion reactions. 3,3,3-Trifluoropropionate esters were used
as the nucleophile with allyl carbonates as the electro-
phile, or 2-(trifluoromethyl)acrylate served as the elec-

8372 J . Org. Chem., Vol. 64, No. 22, 1999
Komatsu et al.
E t h yl 5-P h en yl-2-t r iflu or om et h yl-4-p en t en oa t e (3d ).
1H NMR (CDCl3): δ 1.25 (3 H, t, J ) 7.08 Hz), 2.71 (1 H, dddd,
J ) 1.46, 4.88, 6.84, 14.2 Hz), 2.81 (1 H, dddd, J ) 1.22, 7.56,
8.06, 10.0 Hz), 3.26 (1 H, ddq, J ) 4.86, 10.0, 14.4 Hz), 4.222
(1 H, q, 7.08 Hz), 4.224 (1 H, q, 7.08 Hz), 6.09 (1 H, dt, J )
trophile with vinyl epoxide as the nucleophile. Good
yields of the desired products were isolated.
Exp er im en ta l Section
15.6, 7.33 Hz), 6.51 (1 H, d, J ) 15.9), 7.34-7.22 (5 H, m).13
C
Gen er a l. All commercially available reagents were used
without further purification. Chemical shifts of 1H (500 MHz)
and 13C NMR (50 MHz) spectra were recorded in ppm (δ)
downfield from an internal standard (Me4Si, δ 0.00). The 19F
(470 MHz) NMR spectra were recorded in ppm downfield from
internal standard C6F6 in CDCl3 using a VXR 500 instrument.
Gas-liquid chromatography (GLC) was performed using
Silicone GE XE-60 or ULBON HR-20M on Chromosorb W,
30 m × 3 mm. Optical purities of materials were determined
by GLC.
NMR (CDCl3): δ 14.60, 30.28 (q, J ) 2.5 Hz), 51.05 (q, J )
27.10), 62.39,124.24, 126.80 (2C), 128.13, 125.03 (q, J ) 280
Hz), 129.14 (2C), 134.25, 137.23, 167.43 (q, J ) 3.1 Hz). 19F
NMR (CDCl3): δ -69.25 (d, J ) 9.17 Hz). IR: ν 2380, 1746
(CdO) cm-1. Anal. Calcd for C14H15F3O2: C, 61.67; H, 5.55.
Found: C, 61.63; H, 5.57.
Eth yl 2-Cin n a m yl-5-p h en yl-2-tr iflu or om eth yl-4-p en -
1
ten oa te (4d ). H NMR (CDCl3): δ 1.30 (3 H, t, J ) 7.08 Hz),
2.80 (4 H, d, J ) 7.57 Hz), 4.27 (2 H, q, 7.08 Hz), 6.16 (2 H, dt,
J ) 15.4, 7.81 Hz), 6.50 (2 H, d, J ) 15.6 Hz), 7.23-7.35 (10
H, m). 13C NMR (CDCl3): δ 14.66, 36.12 (2 C, q, J ) 2 Hz),
56.89, (q, J ) 23 Hz), 62.40, 124.55 (q, J ) 284.8 Hz), 123.64
(2 C), 126.81 (4 C), 128.12 (2 C), 129.12 (4C), 135.13 (2 C),
137.48 (2 C), 169.05 (q, J ) 1.8 Hz). 19F NMR (CDCl3): δ
-69.38 (s).
P a lla d iu m (0)-Ca ta lyzed Allyla tion Rea ction u n d er
Neu tr a l Con d ition s. A mixture of ethyl 3,3,3-trifluoropro-
pionate (156 mg, 1.00 mmol) and (E)-cinnnamyl ethyl carbon-
ate (247 mg, 1.20 mmol) was added to a solution of Pd2(dba)3‚
CHCl3 (26 mg, 0.025 mmol), binap (62 mg, 0.10 mmol), and
MS-5A (500 mg) in THF (5 mL) under an argon atmosphere.
After the reaction mixture was stirred for 6 h at 50 °C, the
mixture was diluted with diethyl ether and then passed though
a pad of Celite. On removal of the solvent, the residue was
purified by column chromatography on silica gel, eluting with
a mixture solution of hexanes-ether (50:1) to give ethyl
5-phenyl-2-trifluoromethyl-4-pentenoate (0.161 g) in 61% yield.
Eth yl 2-Tr iflu or om eth yl-4-p en ten oa te (3a ). 1H NMR
(CDCl3): δ 1.28 (3 H, t, J ) 7.08 Hz), 2.61-2.52 (1 H, m), 2.61-
2.69 (1 H, m), 3.19 (1 H, ddq, J ) 4.64, 10.0, 8.30 Hz), 4.23 (2
H, q, 7.08 Hz), 5.12 (1 H, ddd, J ) 1.22, 2.44, 10.3 Hz), 5.17 (1
H, ddd, J ) 1.47, 2.93, 17.1 Hz), 5.67-5.78 (1 H, m). 13C NMR
(CDCl3): δ 14.55, 30.91 (q, J ) 2.5 Hz), 50.73 (q, J ) 27.1
Hz), 62.32, 119.06, 125.05 (q, J ) 280 Hz), 133.00, 167.45 (q,
J ) 3.2 Hz). 19F NMR (CDCl3): δ -69.40 (d, J ) 9.16 Hz). IR
E t h yl 2-Tr iflu or om et h yl-4-oct en oa t e (3e). 1H NMR
(CDCl3): δ 0.87 (3 H, t, J ) 7.57), 1.28 (3 H, t, J ) 7.08 Hz),
1.35 (2 H, q, J ) 7.41 Hz), 1.96 (2 H, q, J ) 6.84 Hz), 2.49 (1
H, ddd, J ) 5.13, 6.35, 14.4 Hz), 2.58 (1 H, ddd, J ) 8.79, 10.0,
14.4 Hz), 3.13 (1 H, ddq, J ) 5.13, 10.0, 8.30 Hz), 4.21 (1 H, q,
J ) 7.08 Hz), 4.22 (1 H, q, J ) 7.08 Hz), 5.31 (1 H, dt, J )
15.1, 7.08 Hz), 5.56, (1 H, dt, J ) 15.1, 6.84 Hz). 13C NMR
(CDCl3): δ 14.03, 14.58, 22.86, 29.95 (q, J ) 2.5 Hz), 35.03,
51.30 (q, J ) 27.2 Hz), 62.18, 124.36, 125.10 (q, J ) 280 Hz),
135.37, 167.65 (q, J ) 3.2 Hz). 19F NMR (CDCl3): δ -69.39
(d, J ) 9.16 Hz). IR (neat): ν 1270, 1749 cm-1
.
Eth yl 2-Tr iflu or om eth yl-7-p h en yl-4-h ep ten oa te (3f).
1H NMR: δ 1.27 (3 H, t, J ) 7.33 Hz), 2.31 (2 H, q, J ) 7.57
Hz), 2.48 (1 H, dt, J ) 14.16, 4.88 Hz), 2.59 (1 H, dddd, J )
0.97, 7.57, 10.01, 14.40 Hz), 2.65 (2 H, dd, J ) 7.56, 8.06 Hz),
3.11 (1 H, ddq, J ) 4.64, 10.01, 8.30 Hz), 4.20 (1 H, q, 7.33
Hz), 4.21 (1 H, q, 7.33 Hz), 5.36 (1 H, dt, J ) 15.38, 6.84 Hz),
5.61, (1 H, dtt, J ) 15.39, 1.22, 6.49 Hz), 7.15-7.20 (2 H, m),
7.26-7.30 (3 H, m). 13C NMR: δ 14.56, 29.84 (q, J ) 2.5 Hz),
34.72, 36.18, 51.16 (q, J ) 26.8 Hz), 62.17, 124.99, 125.07 (q,
J ) 280.2 Hz), 126.40, 128.85 (2 C), 128.91 (2 C), 134.41,
142.13, 167.50 (q, J ) 3.2 Hz). 19F NMR: δ -69.35 (d, J ) 7.63
Hz). IR (neat): ν 1270, 1603, 1747 (CdO) cm-1. Anal. Calcd
for C16H19F3O2: C, 63.99; H, 6.38. Found: C, 63.66; H, 6.15.
Eth yl 2-F lu or o-2-tr iflu or om eth yl-4-p en ten oa te (5a ). 1H
NMR (CDCl3): δ 1.33 (3 H, t, J ) 7.08 Hz), 2.79-3.00 (2 H,
m), 4.34 (2 H, q, J ) 7.08 Hz), 5.24-5.26 (1 H, m), 5.27-5.30
(1 H, m) 5.73 (1 H, dddd, J ) 6.84, 7.57, 9.77, 14.2 Hz). 13C
NMR (CDCl3): δ 14.34, 36.46 (d, J ) 21.6 Hz), 63.49, 92.63
(dq, J ) 202, 31.2 Hz), 121.93 (dq, J ) 28.4, 285 Hz), 122.22,
127.84 (d, J ) 3.0 Hz), 164.36 (d, J ) 24.9 Hz). 19F NMR
(CDCl3): δ -79.15 (3 F, d, J ) 7.63 Hz), -178.18 (1 F, dquint,
(neat): ν 1270, 1647, 1748 (CdO) cm-1
.
Eth yl 2-Allyl-2-tr iflu or om eth yl-4-p en ten oa te (4a ). 1H
NMR (CDCl3): δ 1.29 (3 H, t, J ) 7.08 Hz), 2.60 (4 H, dd, J )
7.57, 13.9 Hz), 4.23 (2 H, q, J ) 7.08 Hz), 5.13 (2 H, ddd, J )
1.01, 1.71, 7.33 Hz), 5.16 (2 H, dd, J ) 1.45, 14.7 Hz), 5.72-
5.80 (2 H, m). 13C NMR (CDCl3): δ 14.48, 36.68 (2 C, q, J )
1.8 Hz), 56.25 (q, J ) 23.4 Hz), 62.29, 120.02 (2 C), 126.47 (q,
J ) 285 Hz), 132.22 (2 C), 168.97 (q, J ) 1.7 Hz). 19F NMR
(CDCl3): δ -69.47 (s). IR (neat): ν 1217, 1643, 1743 (CdO)
cm-1
.
Eth yl 2-Tr iflu or om eth yl-4-h exen oa te (3b). 1H NMR
(CDCl3): δ 1.28 (3 H, t, J ) 7.08 Hz), 1.65 (3 H, ddd, J ) 1.22,
2.68, 6.35 Hz), 2.44-2.50 (1 H, m), 2.53-2.61 (1 H, m), 3.12
(1 H, ddq, J ) 4.64, 13.19, 8.30 Hz), 4.224 (1 H, q, J ) 7.08
Hz), 4.225 (1 H, q, J ) 7.08 Hz), 5.34 (1 H, dt, J ) 15.4, 6.11
Hz), 5.58, (1 H, dtq, J ) 15.1, 1.46, 6.35 Hz). 13C NMR
(CDCl3): δ 14.60, 18.35, 29.93 (q, J ) 2.5 Hz), 51.27 (q, J )
27.2 Hz), 62.17, 125.09 (q, J ) 280 Hz), 125.42, 129.98, 167.65
(q, J ) 3.2 Hz). 19F NMR (CDCl3): δ -69.38 (d, J ) 9.14 Hz).
IR (neat): ν 1263, 1749 cm-1. Anal. Calcd for C9H13F3O2: C,
51.43; H, 6.23. Found: C, 51.82; H, 6.26.
J ) 39.7, 7.63 Hz). IR (neat): ν 1318, 1647, 1770 (CdO) cm-1
.
Eth yl 2-F lu or o-2-tr iflu or om eth yl-4-h exen oa te (5b). 1H
NMR (CDCl3): δ 1.32 (3 H, t, J ) 7.08 Hz), 1.68 (3 H, dd, J )
1.22, 6.59 Hz), 2.70-3.07 (2 H, m), 4.33 (2 H, q, J ) 7.08 Hz),
5.13-5.24 (1 H, m), 5.30-5.36 (1 H, m) 5.67 (1 H, dq, J ) 15.1,
6.35 Hz). 13C NMR (CDCl3): δ 14.53, 18.52, 35.13 (d, J ) 21.1
Hz), 63.48, 93.97 (dq, J ) 201, 31.0 Hz), 121.93 (dq, J ) 28.4,
285.4 Hz), 120.23(d, J ) 1.8 Hz), 133.37, 164.62 (d, J ) 25.9
Hz). 19F NMR (CDCl3): δ -79.11 (3 F, d, J ) 7.62 Hz), -178.30
(1 F, ddq, J ) 21.4, 33.6, 7.63 Hz). IR (neat): ν 1266, 1771
(CdO) cm-1. Anal. Calcd for C9H12F4O2: C, 47.37; H, 5.30.
Found: C, 47.19; H, 5.27.
E t h yl 3-Met h yl-2-t r iflu or om et h yl-4-h exen oa t e (3c).
Diastereomeric ratio, 63:17. IR (neat): ν 1261, 1672, 1742
(CdO) cm-1. Ma jor isom er . 1H NMR (CDCl3): δ 1.06 (3 H, d,
J ) 6.83 Hz), 1.25 (3 H, t, J ) 7.08 Hz), 1.63 (3 H, dd, J )
1.46, 6.35 Hz), 2.98 (1 H, sep, J ) 8.79 Hz), 4.17 (1 H, q, J )
7.08 Hz), 4.19 (1 H, q, J ) 7.08 Hz), 5.25-5.36 (1 H, m), 5.52,
(1 H, ddd, J ) 0.73, 6.59, 15.1 Hz). 13C NMR (CDCl3): δ 14.82,
18.31, 19.46, 36.54 (q, J ) 1.8 Hz), 56.79 (q, J ) 26.2 Hz),
61.91, 125.16 (q, J ) 281 Hz), 127.57, 132.09, 168.12 (q, J )
3.8 Hz). 19F NMR (CDCl3): δ -65.49 (d, J ) 7.63 Hz). Min or
isom er . 1H NMR (CDCl3): δ 1.15 (3 H, dd, J ) 1.22, 6.84 Hz),
1.30 (3 H, t, J ) 7.08 Hz), 1.67 (3 H, dd, J ) 1.46, 6.35 Hz),
2.80 (1 H, sep, J ) 6.59 Hz), 4.231 (1 H, q, J ) 7.08 Hz), 4.237
(1 H, q, J ) 7.08 Hz), 5.25-5.36 (1 H, m), 5.53, (1 H, ddd, J )
0.73, 6.59, 14.4 Hz). 13C NMR (CDCl3): δ 14.65, 18.31, 19.10,
36.22 (q, J ) 1.8 Hz), 56.65 (q, J ) 26.2 Hz), 62.08, 125.03 (q,
J ) 281 Hz), 127.00, 132.45, 167.73 (q, J ) 3.5 Hz). 19F NMR
(CDCl3): δ -65.68 (d, J ) 9.15 Hz).
Eth yl 2-Flu or o-3-m eth yl-2-tr iflu or om eth yl-4-h exen oate
(5c). Diastereomeric ratio, 51:49. IR (neat): ν 1272, 1772 cm-1
.
13C NMR (CDCl3): δ 14.47, 14.73, 15.73, 19.33, 40.36 (d, J )
20.1 Hz), 40.74 (d, J ) 20.1 Hz), 95.84 (dq, J ) 205, 30.6 Hz),
96.00 (dq, J ) 200, 34.4 Hz), 121.85 (dq, J ) 29.3, 286 Hz),
122.26 (dq, J ) 286, 28.9 Hz), 127.56, 127.61, 128.14, 128.19,
129.46, 129.99, 165.08 (dq, J ) 0.2, 25.6 Hz), 165.29 (dq, J )
2.2, 25.0 Hz). Anal. Calcd for C10H14F4O2: C, 49.59; H, 5.83.
Found: C, 49.50; H, 5.87. Ma jor isom er . 1H NMR (CDCl3):
δ 1.08 (3 H, d, J ) 7.08 Hz), 1.35 (3 H, t, J ) 7.08 Hz), 1.65 (3

Synthetic Applications of â-Fluorocarbanions
J . Org. Chem., Vol. 64, No. 22, 1999 8373
H, dd, J ) 1.69, 6.59 Hz), 2.90-3.05 (1 H, m), 4.34 (1 H, q, J
) 7.08 Hz), 4.36 (1 H, q, J ) 7.08 Hz), 5.35 (1 H, ddd, J )
1.71, 9.28, 15.4 Hz), 5.63 (1 H, dd, J ) 6.59, 15.4 Hz). 19F NMR
(CDCl3): δ -74.82 (3 F, d, J ) 6.10 Hz), -187.04 (1 F, dq, J
83.42 (q, J ) 26.7 Hz), 120.17, 124.45 (q, J ) 289 Hz), 128.19
(2 C), 128.35, 128.83 (2 C), 130.75, 138.02, 167.17. 19F NMR
(CDCl3): δ -72.04 (s). IR (neat): ν 1262, 1643, 1751 (CdO)
cm-1. Anal. Calcd for C15H17F3O3: C, 59.60; H, 5.67. Found:
C, 59.38; H, 5.60.
1
) 27.5, 6.10 Hz). Min or isom er . H NMR (CDCl3): δ 1.18 (3
H, d, J ) 6.84 Hz), 1.31 (3 H, t, J ) 7.08 Hz), 1.69 (3 H, dd, J
) 1.71, 6.59 Hz), 2.90-3.05 (1 H, m), 4.29 (1 H, q, J ) 7.08
Hz), 4.30 (1 H, q, J ) 7.08 Hz), 5.40 (1 H, dd, J ) 9.03, 15.4
Hz), 5.58 (1 H, dd, J ) 6.59, 15.1 Hz). 19F NMR (CDCl3): δ
-74.56 (3 F, d, J ) 6.10 Hz), -187.68 (1 F, dq, J ) 27.5, 6.10
Hz).
Eth yl 2-Ben zyloxy-2-tr iflu or om eth yl-4-h exen oate (5j).1H
NMR (CDCl3): δ 1.31 (3 H, t, J ) 7.08 Hz), 1.66 (3 H, dd, J )
1.22, 6.10 Hz), 2.72 (2 H, d, J ) 6.59 Hz), 4.30 (2 H, q, J )
7.08 Hz), 4.66 (1 H, d, J ) 10.7 Hz), 4.81 (1 H, d, J ) 10.7 Hz),
5.43-5.50 (1 H, m), 5.57 (1 H, ddt, J ) 6.34, 15.1, 1.22 Hz),
7.30-7.45 (5 H, m). 13C NMR (CDCl3): δ 14.66, 18.53, 37.69
(q, J ) 1.8 Hz), 62.62 (q, J ) 1.6 Hz), 83.70 (q, J ) 26.3 Hz),
123.08, 124.69 (q, J ) 273 Hz), 128.17 (2 C), 128.34, 128.87
(2 C), 131.10, 138.19, 167.40. 19F NMR (CDCl3): δ -72.06 (s).
IR (neat): ν 1251, 1752 cm-1. Anal. Calcd for C16H19F3O3: C,
60.75; H, 6.05. Found: C, 60.83; H, 5.90.
Eth yl 2-Ben zyloxy-3-m eth yl-2-tr iflu or om eth yl-4-h ex-
en oa te (5k ). Diastereomeric ratio, 52:48. IR (neat): ν 1247,
1753 cm-1. Anal. Calcd for C17H21F3O3: C, 61.81; H, 6.41.
Found: C, 61.60; H, 6.41. Ma jor isom er . 1H NMR (CDCl3):
δ 1.06 (3 H, d, J ) 7.08 Hz), 1.33 (3 H, t, J ) 7.08 Hz), 1.65 (3
H, d, J ) 5.13 Hz), 2.90 (1 H, quint, J ) 7.57 Hz), 4.314 (1 H,
q, 7.08 Hz), 4.312 (1 H, d, J ) 7.08 Hz), 4.61 (1 H, d, J ) 10.7
Hz), 5.45-5.57 (2 H, m), 7.30-7.45 (5 H, m). 13C NMR
(CDCl3): δ 14.62, 16.71, 43.56 (q, J ) 1.8 Hz), 62.50, 69.47,
86.25 (q, J ) 24.9 Hz), 124.61 (q, J ) 291 Hz), 127.99, 130.17,
138.66, 168.02. 19F NMR (CDCl3): δ -66.90 (s). Min or
isom er . 1H NMR (CDCl3): δ 1.14 (3 H, dd, J ) 0.98, 6.84 Hz),
1.29 (3 H, t, J ) 7.08 Hz), 1.63 (3 H, d, J ) 4.64 Hz), 2.90 (1
H, quint, J ) 7.57 Hz), 4.246 (1 H, q, J ) 7.08 Hz), 4.244 (1 H,
d, J ) 7.08 Hz), 4.61 (1 H, d, J ) 10.7 Hz), 4.99 (1 H, d, J )
10.74 Hz), 5.45-5.57 (2 H, m), 7.30-7.45 (5 H, m). 13C NMR
(CDCl3): δ 14.62, 15.64, 43.49 (q, J ) 1.8 Hz), 62.30, 69.38,
86.07 (q, J ) 25.1 Hz), 124.65 (q, J ) 292 Hz), 128.11, 130.85,
138.88, 167.88. 19F NMR (CDCl3): δ -66.65 (s).
Eth yl 2-Ben zyloxy-5-p h en yl-2-tr iflu or om eth yl-4-p en -
ten oa te (5l).1H NMR (CDCl3): δ 1.29 (3 H, t, J ) 7.08 Hz),
2.94 (2 H, d, J ) 6.82 Hz), 4.29 (2 H, q, J ) 7.08 Hz), 4.70 (1
H, d, J ) 10.8 Hz), 4.85 (1 H, d, J ) 10.8 Hz), 6.21 (1 H, dt, J
) 7.09, 15.9 Hz), 6.48 (1 H, d, J ) 15.9 Hz), 7.24-7.42 (10 H,
m). 13C NMR (CDCl3): δ 14.53, 37.09 (q, J ) 2.0 Hz), 61.75
(q, J ) 1.5 Hz), 68.72 (q, J ) 1.5 Hz), 82.67 (q, J ) 26.5 Hz),
123.49 (q, J ) 290 Hz), 125.83 (2 C), 127.12, 127.23 (2 C),
127.40, 127.88 (2 C), 128.06 (2 C), 134.10, 136.42, 137.01,
166.21. 19F NMR (CDCl3): δ -71.97 (s). IR (neat): ν 1249,
1600, 1749 cm-1. Anal. Calcd for C21H21F3O3: C, 66.66; H, 5.59.
Found: C, 66.53; H, 5.87.
Eth yl 5-Cycloh exyl-2-tr iflu or om eth yl-4-pen ten oate (7).
A mixture of ethyl 3,3,3-trifluoropropionate (343 mg, 2.2 mmol)
and γ-cyclohexyl allyl carbonate (424 mg, 2.0 mmol) was added
to a solution of Pd2(dba)3‚CHCl3 (51 mg, 0.05 mmol) and
diphenyldiphosphinoethane (dppe) (79 mg, 0.10 mmol) in THF
(10 mL) under an argon atmosphere. After the reaction
mixture was stirred for 10 h at 60 °C, the mixture was diluted
with diethyl ether and then passed though a pad of Celite.
On removal of the solvent, the residue was purified by column
chromatography on silica gel, eluting with a mixture solution
of hexanes-ether (25:1) to give ethyl 5-cyclohexyl-2-trifluo-
romethyl-4-pentenoate 7 (389 mg) in 70% yield. 1H NMR
(CDCl3): δ 0.98-1.05 (1 H, m), 1.11-1.16 (1 H, m), 1.21 (3 H,
t, J ) 7.08 Hz), 1.26-1.29 (4 H, m), 1.62-1.71 (4 H, m), 1.85-
1.90 (1 H, m), 2.45-2.49 (1 H, m), 2.52-2.58 (1 H, m), 3.12 (1
H, dqd, J ) 10.0, 8.30, 4.88 Hz), 4.21 (2 H, qd, J ) 7.32, 2.19
Hz), 5.26 (1 H, dt, J ) 15.4, 7.08 Hz), 5.51 (1 H, dd, J ) 15.1,
6.59 Hz).13C NMR (CDCl3): δ 14.6 (s), 26.5 (s), 26.6 (s), 30.0
(q, J ) 2.40 Hz), 33.3 (s), 41.1 (s), 51.3 (q, J ) 26.8 Hz), 62.1
(s), 121.6 (s), 125.0 (q, J ) 280 Hz), 141.4 (s), 167.6 (s). 19F
Eth yl 2-Flu or o-5-ph en yl-2-tr iflu or om eth yl-4-pen ten oate
(5d ). 1H NMR (CDCl3): δ 1.29 (3 H, t, J ) 7.08 Hz), 2.99 (1 H,
ddd, J ) 1.46, 6.35, 14.9 Hz), 3.01 (1 H, dd, J ) 8.30, 27.2
Hz), 4.32 (2 H, q, J ) 7.08 Hz), 6.08 (1 H, ddd, J ) 6.59, 8.06,
15.9 Hz), 6.57 (1 H, d, J ) 15.9 Hz), 7.22-7.35 (5 H, m). 13C
NMR (CDCl3): δ 14.50, 35.49 (d, J ) 19.8 Hz), 63.64, 93.89
(dq, J ) 31.1, 202 Hz), 122.10 (dq, J ) 28.4, 285 Hz), 118.85
(d, J ) 2.3 Hz), 126.95 (2 C), 128.58, 129.16 (2C), 136.83,
137.04, 164.51 (d, J ) 24.8 Hz). 19F NMR (CDCl3): δ -78.98
(3 F, q, J ) 7.63 Hz), -177.79 (1 F, ddq, J ) 15.3, 32.1, 7.63
Hz). IR (neat): ν 1313, 1767 (CdO) cm-1. Anal. Calcd for
C
14H14F4O2: C, 57.93; H, 4.86. Found: C, 57.62; H, 4.92.
E t h yl 2-F lu or o-2-t r iflu or om et h yl-4-p en t en oa t e (5e).
1H NMR (CDCl3): δ 1.33 (3 H, t, J ) 7.08 Hz), 2.79-3.00 (2
H, m), 4.34 (2 H, q, J ) 7.08 Hz), 5.24-5.26 (1 H, m), 5.27-
5.30 (1 H, m) 5.73 (1 H, dddd, J ) 6.84, 7.57, 9.77, 14.2 Hz).
13C NMR (CDCl3): δ 14.34, 36.46 (d, J ) 21.6 Hz), 63.49, 92.63
(dq, J ) 202, 31.2 Hz), 121.93 (dq, J ) 28.4, 285 Hz), 122.22,
127.84 (d, J ) 3.0 Hz), 164.36 (d, J ) 24.9 Hz). 19F NMR
(CDCl3): δ -79.15 (3 F, d, J ) 7.63 Hz), -178.18 (1 F, dquint,
J ) 39.7, 7.63 Hz). IR (neat): ν 1318, 1647, 1770 (CdO) cm-1
.
Eth yl 2-Meth yl-2-tr iflu or om eth yl-4-h exen oa te (5f).1H
NMR (CDCl3): δ 1.21 (3 H, t, J ) 7.08 Hz), 1.27 (3H, s), 1.59
(3 H, dd, J ) 1.22, 6.59 Hz), 2.23 (1 H, dd, J ) 8.78, 13.9 Hz),
2.61 (1 H, dd, J ) 6.84, 13.7 Hz), 4.15 (2 H, q, J ) 7.08 Hz),
5.21 (1 H, dt, J ) 14.9, 7.08 Hz), 5.49, (1 H, dtq, J ) 15.1,
1.22, 6.59 Hz). 13C NMR (CDCl3): δ 14.43, 16.82, 18.34, 36.79
(q, J ) 2.2 Hz), 52.85 (q, J ) 24.5 Hz), 62.19, 124.08, 126.08
(q, J ) 290 Hz), 131.08, 169.83. 19F NMR (CDCl3): δ -74.13
(s). IR (neat): ν 1261, 1672, 1742 (CdO) cm-1
.
Eth yl 2,3-Dim eth yl-2-tr iflu or om eth yl-4-h exen oate (5g).
Diastereomeric ratio, 57:43. IR (neat): ν 1265, 1744 (CdO)
cm-1. Ma jor isom er . 1H NMR (CDCl3): δ 0.87 (3 H, d, J )
7.08 Hz), 1.22 (3 H, t, J ) 7.08 Hz), 1.60 (3 H, dd, J ) 1.71,
6.60 Hz), 2.82-2.93 (1 H, m), 4.162 (1 H, q, J ) 7.08 Hz), 4.154
(1 H, d, J ) 7.08 Hz), 5.28 (1 H, dd, J ) 8.55, 15.1 Hz), 5.47
(1 H, dq, J ) 15.1, 6.35 Hz). 13C NMR (CDCl3): δ 12.90, 14.55,
16.79, 18.52, 39.99, 56.85 (q, J ) 23.4 Hz), 62.25, 126.87 (q, J
) 285 Hz), 127.97, 130.65, 170.43 (q, J ) 2.2 Hz). 19F NMR
(CDCl3): δ -70.12 (s). Min or isom er . 1H NMR (CDCl3): δ
1.00 (3 H, dd, J ) 0.97, 7.08 Hz), 1.20 (3 H, t, J ) 7.08 Hz),
1.56 (3 H, dd, J ) 1.71, 6.34 Hz), 2.82-2.93 (1 H, m), 4.104 (1
H, q, J ) 7.08 Hz), 4.119 (1 H, d, J ) 7.08 Hz), 5.16 (1 H, dd,
J ) 8.76, 15.1 Hz), 5.42 (1 H, dq, J ) 15.1, 6.59 Hz). 13C NMR
(CDCl3): δ 12.36, 14.55, 16.11, 18.48, 40.17, 56.75 (q, J ) 23.7
Hz), 62.13, 126.92 (q, J ) 285 Hz), 128.31, 130.79, 170.35 (q,
J ) 2.2 Hz). 19F NMR (CDCl3): δ -69.73 (s).
Eth yl 2-Meth yl-5-ph en yl-2-tr iflu or om eth yl-4-pen ten oate
(5h ).1H NMR (CDCl3): δ 1.28 (3 H, t, J ) 7.08 Hz), 1.42 (3 H,
s) 2.55 (1 H, ddd, J ) 1.22, 8.06, 13.9 Hz), 2.91 (1 H, ddd, J )
1.22, 7.08, 13.9 Hz), 4.241 (1 H, q, J ) 7.08 Hz), 4.240 (1 H, q,
J ) 7.08 Hz), 6.05 (1 H, dt, J ) 15.6, 7.33 Hz), 6.48 (1 H, d, J
) 15.6 Hz), 7.34-7.22 (5 H, m). 13C NMR (CDCl3): δ 14.53,
17.21 (q, J ) 2.4 Hz), 37.32 (q, J ) 2.2 Hz), 53.06 (q, J ) 24.6
Hz), 62.39, 124.24, 126.75 (q, J ) 284 Hz), 126.79 (2 C), 128.15,
129.09 (2 C), 135.36, 137.36, 169.70. 19F NMR (CDCl3):
δ
-73.99 (s). IR (neat): ν 1271, 1740 cm-1. Anal. Calcd
forC15H17F3O2: C, 62.93; H, 5.98. Found: C, 63.36; H, 5.98.
Eth yl 2-Ben zyloxy-2-tr iflu or om eth yl-4-pen ten oate (5i).
1H NMR (CDCl3): δ 1.32 (3 H, t, J ) 7.08 Hz), 2.78 (2 H, d, J
) 7.08 Hz), 4.31 (2 H, q, J ) 7.08 Hz), 4.66 (1 H, d, J ) 10.7
Hz), 4.81 (1 H, d, J ) 10.7 Hz), 5.14-5.20 (1 H, m), 5.86 (1 H,
ddt, J ) 10.1, 17.9, 7.33 Hz), 7.30-7.42 (5 H, m). 13C NMR
(CDCl3): δ 14.54, 38.75 (q, J ) 1.9 Hz), 69.55 (q, J ) 1.7 Hz),
NMR (CDCl3): δ -69.35 (d, J ) 9.15 Hz). IR: 1748 (CdO) cm-1
.
Anal. Calcd for C14H21F3O2: C, 60.42; H, 7.61. Found: C, 60.69;
H, 7.88.
1-Vin yl-1-cycloh exen e (10). In the above reaction, [(ethox-
ycarbonyl)oxymethyl]-methylene-cyclohexane (343 mg, 2.2
mmol) was used and worked up similarly. After stirring for 3
h at 60 °C, the mixture was diluted with diethyl ether and
then passed though a pad of Celite. On removal of the solvent,

8374 J . Org. Chem., Vol. 64, No. 22, 1999
Komatsu et al.
1
the residue was purified by column chromatography on silica
gel, eluting with a mixture solution of hexanes-ether (25:1)
to give 1-vinyl-1-cyclohexene 10 in 86% yield. 1H NMR
(CDCl3): δ 1.58-1.63 (2 H, m), 2.11-2.15 (4 H, m), 4.89 (1 H,
d, J ) 10.5 Hz), 5.06 (1 H, dm, J ) 17.4 Hz), 5.76 (1 H, m),
6.35 (1 H, dd, J ) 10.7, 17.6 Hz).
(5 H, m). 19F NMR (CDCl3): δ -71.80 (s). Min or isom er . H
NMR (CDCl3): δ 2.99 (1 H, t, J ) 6.84 Hz), 3.39-3.44 (1 H,
m), 3.66-3.70 (1 H, m), 4.04 (1 H, t, J ) 7.82 Hz), 4.31-4.26
(1 H, m), 4.14 (1 H, d, J ) 10.3 Hz), 4.438 (1 H, t, J ) 7.08
Hz), 4.441 (1 H, t, J ) 7.08 Hz), 5.16 (1 H, dt, J ) 17.1, 1.22
Hz), 5.19 (1 H, d, J ) 12.0 Hz), 5.78-5.86 (1 H, m), 7.33-7.21
(5 H, m). 19F NMR (CDCl3): δ -65.93 (s).
2-P h en yleth yl 3-Flu or o-2-m eth ylacr ylate (12a). 1H NMR
(CDCl3): δ 1.80 (3 H, dd, J ) 1.46, 3.66 Hz), 2.97 (2 H, t, J )
6.83 Hz), 4.37 (2 H, t, J ) 6.84 Hz), 7.20-7.46 (5 H, m), 7.49
(1 H, dq, J ) 8.18, 1.47 Hz). 13C NMR (CDCl3): δ 9.03 (d, J )
4.0 Hz), 35.57, 65.64, 114.55 (d, J ) 10.9 Hz), 127.09, 129.09
(2 C), 129.35 (2 C), 138.23, 158.49 (d, J ) 276 Hz), 167.32 (d,
J ) 18.5 Hz). 19F NMR (CDCl3): δ -117.19 (dq, J ) 80.9, 3.05
Hz). IR (neat): ν 1277, 1663, 1721 (CdO) cm-1. Anal. Calcd
forC12H13FO2: C, 69.22; H, 6.29. Found: C, 68.91; H, 6.27.
E t h yl 2-Ben zyloxy-3-flu or oa cr yla t e (12b ). 1H NMR
(CDCl3): δ 1.30 (3 H, t, J ) 7.08 Hz), 4.25 (2 H, q, J ) 7.08
Hz), 5.03 (2H, s), 7.36 (1 H, d, J ) 75.0 Hz), 7.28-7.44 (5 H,
m). 13C NMR (CDCl3): δ 14.71, 61.75, 75.13 (d, J ) 4.3 Hz),
128.88 (2 C), 128.97 (2 C), 134.41, 136.96, 149.25 (d, J ) 275
Hz), 164.08 (d, J ) 4.2 Hz). 19F NMR (CDCl3): δ -103.95 (d,
J ) 74.8 Hz). IR (neat): ν 1275, 1663, 1742 (CdO) cm-1. Anal.
Calcd for C12H13FO3: C, 64.28; H, 5.84. Found: C, 64.28; H,
5.69.
4-Eth en yl-3-eth oxyca r bon yl-2,2,3-tr iflu or oxola n e (17).
Diastereomeric ratio, 65:35. Ma jor isom er . 1H NMR
(CDCl3): δ 1.36 (3 H, t, J ) 7.08 Hz), 3.50-3.59 (1H, m), 4.30-
4.39 (2 H, m), 4.36 (1 H, q, J ) 7.08 Hz), 4.37 (1 H, q, J ) 7.08
Hz), 0.5.33 (1 H, d, J ) 7.08 Hz), 5.39 (1 H, d, J ) 13.9 Hz),
5.69 (1 H, ddd, J ) 7.82, 10.3, 17.1 Hz). 13C NMR (CDCl3): δ
14.51, 47.83 (d, J ) 18.4 Hz), 63.68, 71.71, 96.36 (ddd, J )
23.5, 39.5, 208 Hz), 123.22, 127.49 (ddd, J ) 25.2, 261, 266
Hz), 127.51 (d, J ) 6.9 Hz), 164.02 (d, J ) 25.5 Hz). 19F NMR
(CDCl3): δ -70.84 (1 F, ddd, J ) 7.63, 12.2, 140 Hz), -87.17
(1 F, ddd, J ) 3.05, 7.63, 140 Hz), -174.32 (1 F, ddd, J ) 7.63,
12.2, 21.4 Hz). IR (neat): ν 1267, 1647, 1768 (CdO) cm-1
.
Min or isom er . 1H NMR (CDCl3): δ 1.35 (3 H, t, J ) 7.08
Hz), 3.76-3.88 (1H, m), 4.18 (1 H, ddd, J ) 6.38, 8.54, 10.5
Hz), 4.31-4.40 (1 H, m), 4.36 (1 H, q, J ) 7.08 Hz), 4.38 (1 H,
q, J ) 7.08 Hz), 0.5.36 (1 H, dd, J ) 0.49, 10.3 Hz), 5.37 (1 H,
d, J ) 17.3 Hz), 5.74 (1 H, ddd, J ) 8.34, 10.3, 17.3 Hz). 13C
NMR (CDCl3): δ 14.56, 49.53 (dt, J ) 1.6, 21.9 Hz), 63.41,
70.68, 97.36 (ddd, J ) 26.6, 31.6, 220 Hz), 123.32, 126.69 (ddd,
J ) 22.5, 258, 269 Hz), 128.72, 164.33 (dd, J ) 2.1, 26.3 Hz).
19F NMR (CDCl3): δ -70.77 (1 F, ddd, J ) 3.05, 7.63, 145 Hz),
-90.29 (1 F, ddd, J ) 4.58, 13.7, 145 Hz), -184.82 (1 F, dd, J
4-Eth en yl-3-(2-p h en yleth oxyca r bon yl)-3-tr iflu or om e-
th yloxola n e (15). Diastereomeric ratio, 65:35. IR (neat): ν
1254, 1643, 1741 (CdO) cm-1 13C NMR (CDCl3): δ 35.29,
.
49.89, 50.73, 62.53 (q, J ) 24.4 Hz), 63.13 (q, J ) 25.2 Hz),
67.17, 67.40, 72.57 (q, J ) 2.4 Hz), 72.92 (q, J ) 1.8 Hz), 73.03,
120.05, 120.95, 125.61 (q, J ) 283 Hz), 126.34 (q, J ) 289 Hz),
127.31, 129.08, 129.44, 131.61, 131.74, 137.60, 137.79, 167.68
(q, J ) 1.6 Hz), 168.60 (q, J ) 2.5 Hz). Ma jor isom er . 1H
NMR (CDCl3): δ 2.98 (1 H, t, J ) 6.83 Hz), 3.20 (1 H, q, 8.06
Hz), 3.66 (1 H, t, J ) 9.03 Hz), 4.08 (1 H, t, J ) 8.07 Hz),
4.31-4.26 (1 H, m), 4.21 (1 H, d, J ) 10.0 Hz), 4.38 (2 H, t, J
) 7.08 Hz), 5.07 (1 H, d, J ) 10.3 Hz), 5.12 (1 H, dt, J ) 17.0,
0.98 Hz), 5.44 (1 H, ddd, J ) 8.32, 10.3, 17.1 Hz), 7.33-7.21
) 13.7, 29.0 Hz). IR (neat): ν 1275, 1646, 1757 (CdO) cm-1
.
Su p p or tin g In for m a tion Ava ila ble: Copies of 1H, 13C,
and 19F NMR spectra. This material is available free of charge
via the Internet at http://pubs.acs.org.
J O990463R