A novel synthetic approach to fluorine-containing acetylenic compounds based on Nicholas reaction

Article abstract of DOI:10.1016/j.jfluchem.2005.11.009

The fluorine-containing dicobalthexacarbonyl complex, prepared readily from γ-fluoroalkylated propargyl acetates and Co₂(CO)₈, reacted smoothly with various nucleophiles at the propargylic position, followed by oxidative decomplexation under the influence of Fe(NO₃)₃, to afford fluoroalkylated alkynes bearing various types of alkyl side chains in good to high yields.

Full text of DOI:10.1016/j.jfluchem.2005.11.009

Journal of Fluorine Chemistry 127 (2006) 510–518
www.elsevier.com/locate/fluor
A novel synthetic approach to fluorine-containing acetylenic
compounds based on Nicholas reaction
*
Tsutomu Konno , Go Nagai, Takashi Ishihara
Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki,
Sakyo-ku, Kyoto 606-8585, Japan
Received 15 November 2005; accepted 21 November 2005
Available online 18 January 2006
Abstract
The fluorine-containing dicobalthexacarbonyl complex, prepared readily from g-fluoroalkylated propargyl acetates and Co2(CO)8, reacted
smoothly with various nucleophiles at the propargylic position, followed by oxidative decomplexation under the influence of Fe(NO3)3, to afford
fluoroalkylated alkynes bearing various types of alkyl side chains in good to high yields.
# 2005 Elsevier B.V. All rights reserved.
Keywords: Fluorine-containing alkynes; Propargyl acetates; Dicobaltoctacarbonyl; Nicholas reaction
1. Introduction
corresponding fluoroalkylated metal acetylides with various
aryl or alkenyl halides (Fig. 2) [6]. Additionally, g-
fluoroalkylated propargylic alcohols 1C can also be synthe-
sized by the nucleophilic addition reaction of fluoroalkylated
metal acetylides with various carbonyl compounds [7]. In sharp
contrast, there have been quite limited studies on the
preparation of the fluorine-containing alkynes 1D having an
aliphatic side chain as R. The only reported synthetic method
for 1D is that via b-elimination of vinyl halides 2 which can be
prepared by the radical addition reaction of RfI into the
corresponding terminal alkynes [6a,8]. However, this method
sometimes suffers from HF-elimination from 2 followed by
further reactions of the resultant fluorinated compounds,
leading to the formation of the desired acetylenes 1D in very
low yields.
Fluorine-containing compounds are of current interest in the
research areas of polymer, pharmaceutical, and agricultural
chemistry due to the unique properties of fluorine atom(s), such
as the highest electronegativity, the relatively close size to a
hydrogen atom, the increase in oxidative, hydrolytic, and
thermal stability [1]. Consequently, much effort has been
devoted to developing novel synthetic methods for various
types of fluorinated substances [2].
Out of such compounds, fluoroalkylated acetylenic com-
pounds 1 (Fig. 1) are recognized as one of the most valuable
synthetic intermediates in fluorine chemistry, as described in
the precedent studies on their synthetic applications, such as the
regio- and stereo-selective synthesis of various types of
fluoroalkylated alkenes via the hydrometallation and carbo-
metallation reactions of 1 [3], the one-pot synthesis of
fluoroalkylated heterocyclic compounds (indoles, benzofurans,
and isoquinolines) via the carbopalladation reactions of 1 [4],
and so on [5].
In this article, we wish to disclose a new, efficient access to
such types of acetylenic compounds 1D through the cobalt-
mediated nucleophilic substitution reaction of g-fluoroalky-
lated propargylic alcohol derivatives with hydride (n-Bu3SnH)
or various carbon nucleophiles, such as silyl enol ethers,
enamine, and so on.
The fluoroalkylated acetylenic compounds 1A or 1B having
an aromatic or alkenyl side chain as R in 1 can easily be
prepared via the palladium-catalyzed coupling reaction of the
2. Results and discussion
Generally, acetylenic compounds readily react with dico-
baltoctacarbonyl (Co2(CO)8) to form the corresponding alkyne-
dicobalthexacarbonyl (Co2(CO)6) complexes quantitatively, in
* Corresponding author.
E-mail address: konno@chem.kit.ac.jp (T. Konno).
0022-1139/$ – see front matter # 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2005.11.009

T. Konno et al. / Journal of Fluorine Chemistry 127 (2006) 510–518
511
Fig. 1. Fluoroalkylated acetylenic compounds and their synthetic applications.
Fig. 2. Various acetylenic compounds and their synthetic methods.
which a Co2(CO)6 group effectively stabilizes a propargyl
cation (Fig. 3). These cobalt complexes can react with a wide
variety of nucleophiles, followed by oxidative demetallation, to
yield the corresponding internal alkynes [9]. This reaction
sequence, commonly referred to as the Nicholas reaction, has
recently been used for the synthesis of intricate biologically
active compounds [10].
Then, the Nicholas reaction of trifluoromethylated pro-
pargylic alcohol derivatives 3a (Rf = CF3, R1 = p-MeOC6H4,
R2 = H) with n-Bu3SnH was chosen for our initial investigation
for the synthesis of the fluorine-containing acetylenic
compounds 1 having an alkyl side chain (Scheme 1). Thus,
the treatment of 3a with 1.5 equiv. of Co2(CO)8 in CH2Cl2 at
room temperature for 5 h gave the corresponding cobalt
complex 4a quantitatively, as a dark-purple liquid. Subse-
quently, 4a was subjected to the Nicholas reaction conditions,
such as 4.0 equiv. of TMSOTf and 1.5 equiv. of n-Bu3SnH in
CH2Cl2 at 0 8C for 5 h, to afford the corresponding substitution
product 5a. After flash column chromatography, 5a was
allowed to decomplex under the influence of Fe(NO3)3 in
CH2Cl2 at room temperature for 10 h, the corresponding
Fig. 3. Stabilization of the propargylic cation.

512
T. Konno et al. / Journal of Fluorine Chemistry 127 (2006) 510–518
Scheme 1. The Nicholas reaction.
fluoroalkylated internal alkyne 1a having an alkyl side chain
being obtained in 89% overall yield. These reaction conditions
were next applied for various types of fluoroalkylated
propargylic alcohol derivatives 3b–m, as shown in Table 1.
As shown in entries 1–3, a p-MeOC6H4 substituent was
found to be very effective, the desired reduction products 1a–c
being provided in excellent yields without any influence of a
fluoroalkyl group. However, the position of a MeO group on the
aromatic ring significantly affected the efficiency of the
reaction and, 1d and 1e were given in only 52% and 51% yields,
respectively, (entries 4 and 5). The use of the alkynes having an
aromatic ring substituted by a Me or Cl group at the para
position resulted in a slight increase of the yield, compared with
those of 1d and 1e (entries 6 and 7). The substrate 3i bearing a
2-furyl group did not give any desired compound at all, the
cobalt complex 4i being obtained in almost quantitative yield
(entry 9). Additionally, the reactions of 3j–l carrying a 2-thienyl
or alkyl group as R2 proceeded somewhat sluggishly to afford
the corresponding products in moderate yields (entries 10–12).
Interestingly, the substrate 3m having two alkyl groups as R1
and R2 led to the enyne product 6m in 44% yield, and any
Scheme 2. The reaction mechanism.
substitution product 1m could not be detected at all (entry 13).
This may be explained by preferential b-elimination on Int-A
rather than nucleophilic attack to the sterically hindered tertiary
carbon (Scheme 2).
We next investigated the Nicholas reaction of 3a with
various types of carbon nucleophiles, as summarized in
Table 2. As shown in entries 1–3, methallylstannane,
allylstannane, and allylsilane were found to be less nucleo-
philic, so that the coupling products 1aA, 1aB were given in
moderate yields (49–63%). Particularly, the reaction of 3a with
methallylstannane gave an isomeric mixture of 1aA1 and 1aA2
in a ratio of 3:1. In contrast, more nucleophilic silyl enol ethers
derived from ketones, such as acetophenone, pinacolone, and
cyclohexanone, underwent the smooth Nicholas reaction,
1aC–1aE being afforded in excellent yields (entries 4, 6, and
7). Enamine and silyl ketene acetal could also participate very
well in the present reaction, leading to high yields of the
coupling products 1aC and 1aF (entries 5 and 8). It should be
noted that a fluoroalkyl group in the substrate 3 did not affect
the Nicholas reaction at all. The reactions of 3b (Rf = CHF2)
and 3c (Rf = HCF2CF2CF2) with silyl enol ether took place
efficiently to give rise to the corresponding coupling products
1bC and 1cC in 96% and 87% yields, respectively, (entries 9
and 10).
Table 1
The Nicholas reaction of propargylic alcohol derivatives 3 using n-Bu3SnH as a
nucleophile (Nu = H)
Entry
Rf
R1
R2
Yielda/% of 1
1
2
CF3
H
H
H
H
H
H
H
H
H
H
H
H
Me
p-MeOC6H4 (a)
p-MeOC6H4 (b)
p-MeOC6H4 (c)
m-MeOC6H4 (d)
o-MeOC6H4 (e)
p-MeC6H4 (f)
p-CIC6H4 (g)
1-Naphthyl (h)
2-Furyl (i)
2-Thienyl (j)
89
97
99
52
51
64
63
78
0
CHF2
HCF2CF2CF2
CF3
3
4
5
CF3
6
CF3
7
CF3
8
CF3
9
CF3
3. Conclusion
10
11
12
13
CF3
47
41
54
44b
CF3
PhCH2CH2 (k)
PhCH(CH3) (l)
PhCH2CH2 (m)
In summary, we have developed a novel method for the
preparation of various types of fluorine-containing alkynes
bearing an alkyl side chain via the Nicholas reaction. Various
fluorine-containing propargyl acetates underwent the smooth
CF3
CF3
a
Isolated yields.
b
The isomerization product 6m was obtained in 44% yield.

T. Konno et al. / Journal of Fluorine Chemistry 127 (2006) 510–518
513
Table 2
The Nicholas reaction with various carbon nucleophiles
Entry
Rf
Nucleophile
Product
Yielda/% of 1
1
CF3
49 (1aA1:1aA2 = 3:1)
2
3
CF3
CF3
63
59
4
5
6
CF3
CF3
CF3
88
89
99
7
CF3
88b
8
CF3
96

514
T. Konno et al. / Journal of Fluorine Chemistry 127 (2006) 510–518
Table 2 (Continued )
Entry
Rf
Nucleophile
Product
Yielda/% of 1
9
CHF2
96
10
CHF2(CF2)2
87
a
Isolated yields.
b
1:1 Diastereomer mixture.
Nicholas reaction with n-Bu3SnH, leading to the reduction
products. Additionally, various carbon nucleophiles, such as
allylstannane, allylsilane, silyl enol ethers, silyl ketene acetals,
enamine, and so on, could participate nicely in the Nicholas
reaction, the desired alkynes being obtained in good to
excellent yields.
12 mmol) and pyridine (1.0 mL, 12 mmol) at 0 8C and
the mixture was allowed to warm to room temperature,
and then stirred for 12 h. The reaction was quenched
with NH4Cl aqueous solution and the resulting mixture
was extracted three times with CH2Cl2. The combined
organic layers were dried over anhydrous Na2SO4, filtered,
and concentrated in vacuo. The residue was chromatogra-
phed on silica gel to afford the corresponding acetate
3 (35–95% yield).
4. Experimental
4.1. General methods
4.2.1. 4,4,4-Trifluoro-1-(4-methoxyphenyl)-2-butynyl
acetate (3a)
1H NMR spectra were measured with a Bruker DRX
(500.13 MHz) spectrometer in a chloroform-d (CDCl3)
solution with Me4Si as an internal reference. 13C NMR spectra
were recorded on a Bruker DRX (125.77 MHz) spectrometer. A
JEOL JNM-EX90 (84.21 MHz, FT) spectrometer was used for
determining NMR yields by the use of internal C6F6. 19F NMR
spectra were determined with a JEOL JNM-EX90 spectrometer
in a CDCl3 solution with internal CFCl3. Infrared spectra (IR)
were recorded on a Shimadzu FTIR-8200A (PC) spectro-
photometer. Mass spectra (MS) were taken on a JEOL JMS-700
instrument.
Yield 79%; 1H NMR d (ppm) 2.11 (3H, s), 3.82 (3H, s), 6.47
(1H, q, J = 2.88 Hz), 6.92–6.94 (2H, m), 7.40–7.43 (2H, m);
13C NMR d (ppm) 20.8, 55.3, 63.9, 73.3 (q, J = 53.2 Hz), 83.3
(q, J = 6.5 Hz), 113.9 (q, J = 257.8 Hz), 114.3, 126.7, 129.4,
160.6, 169.3; 19F NMR d (ppm) À54.7 (3F, s); IR (neat) 2914,
2841, 2272, 1749, 1612, 1516 cmÀ1; HRMS (FAB) calcd. for
(M+) C13H11F3O3 272.0660, found 272.0660.
4.2.2. 4,4-Difluoro-1-(4-methoxyphenyl)-2-butynyl acetate
(3b)
Dicobaltoctacarbonyl was purchased from Kanto Chemical
Co. Inc., CH2Cl2 was freshly distilled from calcium hydride.
All chemicals were of reagent grade and, if necessary, were
purified in the usual manner prior to use. Thin layer
chromatography was done with Merck silica gel 60 F254 plates
and column chromatography was carried out with Wako gel C-
200. All propargyl alcohols were prepared according to the
literature procedure [7].
Yield 45%; 1H NMR d (ppm) 2.69 (3H, s), 3.80 (3H, s), 6.24
(1H, dt, J = 1.00, 54.42 Hz), 6.46 (1H, t, J = 4.27 Hz), 6.90–
7.44 (4H, m); 13C NMR d (ppm) 20.8, 55.3, 64.3, 77.5 (t,
J = 34.6 Hz), 85.5 (t, J = 7.2 Hz), 103.5 (t, J = 233.2 Hz),
114.2, 127.4, 129.3, 160.4, 169.4; 19F NMR d (ppm) À107.3
(2F, d, J = 56.5 Hz); IR (neat) 2939, 2841, 2312, 2257, 1747,
1612 cmÀ1; HRMS (FAB) calcd. for (M+ matrix-m-NBA)
C13H12F2O3 254.0755, found 254.0762.
4.2. General procedure for the synthesis of fluoroalkylated
propargyl acetate 3
4.2.3. 4,4,5,5,6,6-Hexafluoro-1-(4-methoxyphenyl)-2-
hexynyl acetate (3c)
Yield 54%; 1H NMR d (ppm) 2.10 (3H, s), 3.82 (3H, s), 6.02
(1H, tt, J = 5.35, 52.10 Hz), 6.47 (1H, t, J = 4.25 Hz), 6.93 (2H,
d, J = 8.72 Hz), 7.42 (2H, d, J = 8.71 Hz); 13C NMR d (ppm)
To a solution of the corresponding propargyl alcohol
(10 mmol) in CH2Cl2 (15 mL) was added Ac2O (1.2 mL,

T. Konno et al. / Journal of Fluorine Chemistry 127 (2006) 510–518
515
20.7, 55.3, 64.2, 72.8 (t, J = 36.9 Hz), 89.3 (t, J = 6.4 Hz), 107.7
(tt, J = 31.4, 253.3 Hz), 104.9–110.8 (m), 114.3, 126.6, 129.4,
160.7, 169.4; 19F NMR d (ppm) À137.1 (2F, dquint., J = 8.5,
50.8 Hz), À130.9 (2F, m), À100.9 (2F, m); IR (neat) 2941,
2843, 2266, 1749, 1715 cmÀ1; HRMS (FAB) calcd. for (M+)
C15H12F6O3 354.0691, found 354.0691.
129.8, 130.2, 130.8, 134.0, 169.3; 19F NMR d (ppm) À51.2
HRMS (FAB) calcd. for (M+) C16H11F3O2 292.0711, found
292.0701.
(3F, s); IR (KBr) 3070, 2962, 2272, 1744, 1601 cmÀ1
;
4.2.9. 4,4,4-Trifluoro-1-(2-furyl)-2-butynyl acetate (3i)
1
Yield 95%; H NMR d (ppm) 2.12 (3H, s), 6.40 (1H, dd,
4.2.4. 4,4,4-Trifluoro-1-(3-methoxyphenyl)-2-butynyl
acetate (3d)
J = 1.44, 3.31 Hz), 6.56 (1H, d, J = 3.33 Hz), 6.58 (1H, q,
J = 2.84 Hz), 7.46 (1H, d, J = 1.28 Hz); 13C NMR d (ppm)
20.4, 57.2, 72.8 (q, J = 53.4 Hz), 81.1 (q, J = 7.3 Hz), 110.8,
111.2, 113.7 (q, J = 258.3 Hz), 144.3, 146.7, 169.1; 19F NMR d
(ppm) À51.5 (3F, s); IR (neat) 2277, 1760, 1500, 1373,
Yield 72%; 1H NMR d (ppm) 2.14 (3H, s), 3.83 (3H, s), 6.49
(1H, q, J = 2.82 Hz), 6.94–7.07 (3H, m), 7.34 (1H, t,
J = 7.90 Hz); 13C NMR d (ppm) 20.7, 55.3, 64.0, 73.5 (q,
J = 53.6 Hz), 83.5 (q, J = 6.4 Hz), 113.3, 113.8 (q,
J = 258.3 Hz), 115.1, 119.8, 130.1, 135.9, 159.94, 169.2; 19F
NMR d (ppm) À53.0 (3F, s); IR (neat) 2943, 2841, 2272, 1755,
1605, 1493, 1458 cmÀ1; HRMS (FAB) calcd. for (M+)
C13H11F3O3 272.0660, found 272.0669.
1279 cmÀ1
.
4.2.10. 4,4,4-Trifluoro-1-(2-thienyl)-2-butynyl acetate (3j)
1
Yield 35%; H NMR d (ppm) 2.12 (3H, s), 6.77 (1H, q,
J = 2.78 Hz), 7.01–7.03 (1H, m), 7.26–7.27 (1H, m), 7.39 (1H,
dd, J = 1.15, 5.11 Hz); 13C NMR d (ppm) 20.5, 59.3, 73.0 (q,
J = 53.4 Hz), 82.7 (q, J = 6.4 Hz), 113.8 (q, J = 258.3 Hz),
126.9, 127.9, 128.5, 136.6, 169.0; 19F NMR d (ppm) À51.5 (3F,
s); IR (neat) 2936, 2279, 1755, 1433, 1371, 1279 cmÀ1; HRMS
(FAB) calcd. for (M+) C10H7F3O232S 248.0119, found
248.0104.
4.2.5. 4,4,4-Trifluoro-1-(2-methoxyphenyl)-2-butynyl
acetate (3e)
Yield 77%; 1H NMR d (ppm) 2.12 (3H, s), 3.85 (3H, s), 6.86
(1H, q, J = 2.92 Hz), 6.92 (1H, q, J = 8.15 Hz), 7.02 (1H, dt,
J = 0.79, 7.56 Hz), 7.38 (1H, dt, J = 1.66, 7.88 Hz), 7.54 (1H,
dd, J = 1.58, 7.61 Hz); 13C NMR d (ppm) 20.7, 55.6, 59.2, 72.5
(q, J = 53.0 Hz), 84.0 (q, J = 6.5 Hz), 111.00, 113.9 (q,
J = 258.0 Hz), 120.8, 122.7, 128.6, 131.0, 156.6, 169.2; 19F
NMR d (ppm) À53.8 (3F, s); IR (neat) 2945, 2843, 2270, 1755,
1716, 1605 cmÀ1; HRMS (FAB) calcd. for (M+) C13H11F3O3
272.0660, found 272.0666.
4.2.11. 4,4,4-Trifluoro-1-(2-phenylethyl)-2-butynyl acetate
(3k)
1
Yield 56%; H NMR d (ppm) 2.11 (3H, s), 2.13–2.22 (2H,
m), 2.78 (2H, t, J = 7.81 Hz), 5.14 (1H, oct., J = 2.90 Hz), 7.18–
7.33 (5H, m); 13C NMR d (ppm) 20.6, 31.0, 35.2, 61.9, 72.5 (q,
J = 53.2 Hz), 84.3 (q, J = 6.4 Hz), 113.8 (q, J = 261.4 Hz),
126.5, 128.3, 128.6, 139.7, 169.4; 19F NMR d (ppm) À54.5
4.2.6. 4,4,4-Trifluoro-1-(4-methylphenyl)-2-butynyl acetate
(3f)
Yield 82%; 1H NMR d (ppm) 2.13 (3H, s), 2.39 (3H, s), 6.51
(1H, br q, J = 2.65 Hz), 7.24 (2H, d, J = 7.84 Hz), 7.40 (2H, d,
J = 7.87 Hz); 13C NMR d (ppm) 20.7, 21.2, 64.1, 73.3 (q,
J = 53.2 Hz), 83.8 (q, J = 6.5 Hz), 113.9 (q, J = 257.8 Hz),
127.7, 129.6, 131.6, 139.8, 169.2; 19F NMR d (ppm) À51.2
(3F, s); IR (neat) 3030, 2936, 2868, 2274, 1751 cmÀ1
;
HRMS (CI) calcd. for (M + H) C14H14F3O2 271.0946, found
271.0945.
4.2.12. 4,4,4-Trifluoro-1-(1-phenylethyl)-2-butynyl acetate
(3l)
Yield 70%; 1H NMR d (ppm) 1.44 (3H, d, J = 7.09 Hz), 2.10
(3H, s), 3.23 (1H, quint., J = 6.94 Hz), 5.53 (1H, sex.,
J = 2.96 Hz), 7.24–7.36 (5H, m); 13C NMR d (ppm) 16.2,
20.6, 43.1, 66.8, 73.2 (q, J = 53.2 Hz), 83.6 (q, J = 6.5 Hz),
(3F, s); IR (neat) 2930, 2870, 2270, 1751, 1616, 1516 cmÀ1
;
HRMS (FAB) calcd. for (M+) C13H11F3O2 256.0711, found
256.0706.
4.2.7. 1-(4-Chlorophenyl)-4,4,4-trifluoro-2-butynyl acetate
(3g)
113.7 (q, J = 257.6 Hz), 127.6, 128.0, 128.5, 140.0, 169.4; 19
NMR d (ppm) À53.4 (3F, s); IR (neat) 3034, 2980, 2939, 2883,
2272, 1753 cmÀ1
HRMS (FAB) calcd. for (M + Na)
F
1
Yield 63%; H NMR d (ppm) 2.14 (3H, s), 6.48 (1H, q,
J = 2.83 Hz), 7.39–7.44 (4H, m); 13C NMR d (ppm) 20.7, 63.5,
73.8 (q, J = 53.3 Hz), 83.0 (q, J = 6.5 Hz), 113.8 (q,
J = 258.4 Hz), 129.1, 129.3, 133.1, 135.8, 169.1; 19F NMR d
(ppm) À52.6 (3F, s); IR (neat) 2939, 2272, 1751, 1599,
1491 cmÀ1; HRMS (EI) calcd. for (M+) C12H835ClF3 276.0165,
found 276.0167.
;
C14H13F3NaO2 293.0765, found 293.0760.
4.2.13. 3-(6,6,6-Trifluoro-3-methyl-1-phenyl-4-hexynyl)
acetate (3m)
1
Yield 69%; H NMR d (ppm) 1.76 (3H, s), 2.05 (3H, s),
4.2.8. 4,4,4-Trifluoro-1-(1-naphthyl)-2-butynyl acetate
(3h)
2.14–2.20 (1H, m), 2.25–2.31 (1H, m), 2.74–2.86 (2H, m),
7.20–7.32 (5H, m); 13C NMR d (ppm) 21.4, 25.6, 30.3, 42.4,
72.7 (q, J = 52.7 Hz), 73.0, 86.8 (q, J = 6.6 Hz), 114.1 (q,
J = 257.7 Hz), 126.2, 128.4, 128.5, 140.5, 168.9; 19F NMR d
(ppm) À52.8 (3F, s); IR (neat) 3065, 3030, 2932, 2868, 2278,
1
Yield 49%; mp 72–74 8C; H NMR d (ppm) 2.17 (3H, s),
7.21 (1H, q, J = 2.90 Hz), 7.51–8.15 (7H, m); 13C NMR d (ppm)
20.6, 62.6, 74.0 (q, J = 53.2 Hz), 83.6 (q, J = 6.4 Hz), 113.9
(q, J = 257.9 Hz), 123.0, 125.1, 126.3, 126.9, 127.1, 129.0,
1751 cmÀ1
.

516
T. Konno et al. / Journal of Fluorine Chemistry 127 (2006) 510–518
4.3. General procedure for the Nicholas reaction with n-
Bu3SnH
4.3.4. 1,1,1-Trifluoro-4-(3-methoxyphenyl)-2-butyne (1d)
Yield 52%; 1H NMR d (ppm) 3.69 (2H, q, J = 3.67 Hz), 3.81
(3H, s), 6.82–6.89 (3H, m), 7.26 (1H, t, J = 7.87 Hz); 13C NMR
d (ppm) 24.4, 55.2, 70.1 (q, J = 52.2 Hz), 86.4 (q, J = 6.4 Hz),
112.7, 114.1 (q, J = 256.6 Hz), 113.7, 120.2, 129.9, 134.8,
160.0; 19F NMR d (ppm) À52.2 (3F, s); IR (neat) 2928, 2841,
2262, 1603 cmÀ1; HRMS (FAB) calcd. for (M+) C11H9F3O
214.0605, found 214.0607.
Co2(CO)8 (0.51 g, 1.5 mmol) was added to a solution of
acetate 3 (1.0 mmol) in CH2Cl2 (5.0 mL) at room tempera-
ture. After stirring for 5 h, the reaction mixture was filtered
and the filtrate was concentrated in vacuo. The residue was
passed through a silica gel column to give a crude complex 4
which was used for the next reaction without further
purification.
4.3.5. 1,1,1-Trifluoro-4-(2-methoxyphenyl)-2-butyne (1e)
Yield 51%; 1H NMR d (ppm) 3.72 (2H, q, J = 3.72 Hz), 3.88
(3H, s), 6.92 (1H, d, J = 8.21 Hz), 7.02 (1H, d, J = 7.48 Hz),
7.33 (1H, t, J = 7.86 Hz), 7.41 (1H, d, J = 7.44 Hz); 13C NMR d
(ppm) 19.0, 55.3, 69.6 (q, J = 52.1 Hz), 87.1 (q, J = 6.4 Hz),
110.3, 114.3 (q, J = 256.4 Hz), 120.7, 121.9, 128.7, 128.8,
156.7; 19F NMR d (ppm) À54.2 (3F, s); IR (neat) 2943, 2841,
2260, 1603, 1495 cmÀ1; HRMS (FAB) calcd. for (M À H)
C11H8F3O 213.0527, found 213.0518.
To a solution of the crude cobalt complex 4 in CH2Cl2
(15 mL) was added TMSOTf (0.89 g, 4.0 mmol) and n-Bu3SnH
(0.44 g, 1.5 mmol) at 0 8C, and the whole was stirred for 5 h.
The reaction was quenched with NaHCO3 aqueous solution and
the resultant mixture was extracted three times with ethyl
acetate. The combined organic layers were dried over
anhydrous Na2SO4 and concentrated in vacuo. The residue
was passed through a short silica gel column to afford the crude
product 5.
A solid of Fe(NO3)3Á9H2O (1.62 g, 4 mmol) was added to
the crude cobalt complex 5 in CH2Cl2 (10 mL) and the whole
was stirred until a red color of the reaction mixture disappeared
(ꢀ10 h). The reaction mixture was filtered and the filtrate was
concentrated in vacuo. The residue was purified by silica gel
column chromatography to give the corresponding fluoroalky-
lated acetylene derivative 1.
4.3.6. 1,1,1-Trifluoro-4-(4-methylphenyl)-2-butyne (1f)
1
Yield 64%; H NMR d (ppm) 2.36 (3H, s), 3.68 (2H, q,
J = 3.69 Hz), 7.16–7.21 (4H, m); 13C NMR d (ppm) 21.0, 24.1,
69.9 (q, J = 52.1 Hz), 86.9 (q, J = 6.4 Hz), 114.2 (q,
J = 256.4 Hz), 127.8, 129.6, 130.3, 137.1; 19F NMR d (ppm)
À50.2 (3F, s); IR (neat) 2928, 2858, 2260, 1705, 1605 cmÀ1
;
HRMS (EI) calcd. for (M+) C11H9F3 198.0656, found 198.0650.
4.3.1. 1,1,1-Trifluoro-4-(4-methoxyphenyl)-2-butyne (1a)
Yield 89%; 1H NMR d (ppm) 3.66 (2H, q, J = 3.66 Hz), 3.81
(3H, s), 6.89 (2H, d, J = 8.62 Hz), 7.21 (2H, d, J = 8.54 Hz);
13C NMR d (ppm) 23.6, 55.3, 69.8 (q, J = 52.4 Hz), 87.0 (q,
J = 6.2 Hz), 114.2 (q, J = 255.1 Hz), 114.3, 125.3, 129.0,
158.9; 19F NMR d (ppm) À53.6 (3F, s); IR (neat) 2916, 2841,
2260, 1610 cmÀ1; HRMS (FAB) calcd. for (M À H) C11H8F3O
213.0527, found 213.0528.
4.3.7. 4-(4-Chlorophenyl)-1,1,1-trifluoro-2-butyne (1g)
Yield 63%; 1H NMR d (ppm) 3.69 (2H, q, J = 3.64 Hz), 7.24
(2H, d, J = 8.50 Hz), 7.33 (2H, d, J = 8.44 Hz); 13C NMR d
(ppm) 23.9, 70.4 (q, J = 52.5 Hz), 85.9 (q, J = 6.4 Hz), 114.0 (q,
J = 256.6 Hz), 129.0, 129.2, 131.8, 133.4; 19F NMR d (ppm)
À52.1 (3F, s); IR (neat) 2930, 2856, 2262, 1682, 1591 cmÀ1
;
HRMS (FAB) calcd. for (M À H) C11H535ClF3 217.0032, found
217.0031.
4.3.2. 1,1-Difluoro-4-(4-methoxyphenyl)-2-butyne (1b)
Yield 97%; 1H NMR d (ppm) 3.62 (2H, t, J = 5.61 Hz), 3.78
(3H, s), 6.20 (1H, t, J = 55.28 Hz), 6.84–7.25 (4H, m); 13C
NMR d (ppm) 23.8 (t, J = 2.6 Hz), 55.2, 73.7 (t, J = 33.8 Hz),
88.5 (t, J = 7.2 Hz), 103.9 (t, J = 231.5 Hz), 114.1, 126.4,
128.9, 158.7; 19F NMR d (ppm) À105.0 (2F, dt, J = 5.7,
56.5 Hz); IR (neat) 2910, 2839, 2324, 2255, 1612, 1587,
1514 cmÀ1; HRMS (FAB) calcd. for (M+) C11H10F2O
196.0700, found 196.0697.
4.3.8. 1,1,1-Trifluoro-4-(1-naphthyl)-2-butyne (1h)
1
Yield 78%; mp 32–34 8C; H NMR d (ppm) 4.10 (2H, q,
J = 3.66 Hz), 7.48–7.95 (7H, m); 13C NMR d (ppm) 22.3, 70.8
(q, J = 52.3 Hz), 86.3 (q, J = 6.3 Hz), 114.2 (q, J = 256.5 Hz),
122.8, 125.5, 126.0, 126.1, 126.6, 128.4, 128.9, 129.2, 131.1,
133.8; 19F NMR d (ppm) À50.2 (3F, s); IR (KBr) 3068, 2303,
2262, 1599 cmÀ1; HRMS (EI) calcd. for (M+) C14H9F3
234.0656, found 234.0666.
4.3.9. 1,1,1-Trifluoro-4-(2-thienyl)-2-butyne (1j)
1
4.3.3. 4,4,5,5,6,6-Hexafluoro-1-(4-methoxyphenyl)-2-
hexyne (1c)
Yield 47%; H NMR d (ppm) 3.90 (2H, q, J = 3.36 Hz),
6.97–6.98 (2H, m), 7.23 (1H, dd, J = 1.38, 4.90 Hz); 13C NMR
d (ppm) 19.4, 69.8 (q, J = 52.4 Hz), 85.4 (q, J = 6.4 Hz), 114.0
(q, J = 256.9 Hz), 125.0, 126.1, 127.1, 135.1; 19F NMR d (ppm)
Yield 99%; 1H NMR d (ppm) 3.66 (2H, t, J = 5.54 Hz), 3.77
(3H, s), 5.99 (1H, tt, J = 5.45, 52.25 Hz), 6.87 (2H, d,
J = 8.57 Hz), 7.19 (2H, d, J = 8.49 Hz); 13C NMR d (ppm) 23.9,
55.2, 69.1 (t, J = 36.1 Hz), 92.7 (t, J = 6.4 Hz), 107.9 (tt,
J = 31.4, 253.3 Hz), 105.2–110.2 (m), 114.3, 125.3, 128.9,
159.0; 19F NMR d (ppm) À137.1 (2F, dquint., J = 8.5, 50.8 Hz),
À131.1 (2F, m), À98.9 (2F, m); IR (neat) 2912, 2841, 2264,
1612, 1587, 1514 cmÀ1; HRMS (FAB) calcd. for (M+)
C13H10F6O 296.0636, found 296.0641.
À50.5 (3F, s); IR (neat) 2928, 2260, 1715, 1439, 1416 cmÀ1
;
HRMS (EI) calcd. for (M+) C8H5F332S 190.0064, found
190.0067.
4.3.10. 1,1,1-Trifluoro-6-phenyl-2-hexyne (1k)
Yield 41%; 1H NMR d (ppm) 1.92 (2H, quint., J = 7.53 Hz),
2.32 (2H, oct., J = 3.70 Hz), 7.18–7.33 (5H, m); 13C NMR d

T. Konno et al. / Journal of Fluorine Chemistry 127 (2006) 510–518
517
(ppm) 17.4, 28.7, 34.5, 68.8 (q, J = 52.2 Hz), 88.8 (q,
4.4.3. 7,7,7-Trifluoro-4-(4-methoxyphenyl)-1-hepten-5-yne
(1aB)
J = 6.2 Hz), 114.1 (q, J = 256.0 Hz), 126.2, 128.46, 128.52,
140.6; 19F NMR d (ppm) À54.1 (3F, s); IR (neat) 2932, 2864,
2264, 1716 cmÀ1; HRMS (EI) calcd. for (M+) C12H11F3
212.0813, found 212.0810.
Yield 63%; 1H NMR d (ppm) 2.52–2.56 (2H, m), 3.75 (1H,
oct., J = 3.54 Hz), 3.81 (3H, s), 5.08–5.12 (2H, m), 5.73–5.81
(1H, m), 6.88–6.90 (2H, m), 7.20–7.26 (2H, m); 13C NMR d
(ppm) 36.5, 41.4, 55.3, 70.9 (q, J = 52.2 Hz), 89.9 (q,
J = 6.5 Hz), 114.2, 114.3 (q, J = 256.6 Hz), 118.2, 128.4,
130.3, 133.9, 158.9; 19F NMR d (ppm) À51.9 (3F, s); IR
(neat) 3082, 2914, 2839, 2264, 1612, 1514 cmÀ1; HRMS
(FAB) calcd. for (M À H) C14H12F3O 253.0840, found
253.0845.
4.3.11. 1,1,1-Trifluoro-5-phenyl-2-hexyne (1l)
1
Yield 54%; H NMR d (ppm) 1.40 (3H, d, J = 7.01 Hz),
2.48–2.62 (2H, m), 3.05 (1H, sex., J = 7.03 Hz), 7.21–7.26 (3H,
m), 7.31–7.34 (2H, m); 13C NMR d (ppm) 20.6, 27.3, 38.1,
69.6 (q, J = 51.9 Hz), 87.7 (q, J = 6.4 Hz), 114.1 (q, J =
256.5 Hz), 126.7, 126.9, 128.6, 144.4; 19F NMR d (ppm) À51.7
(3F, s); IR (neat) 2968, 2932, 2856, 2258, 1495 cmÀ1
;
4.4.4. 6,6,6-Trifluoro-3-(4-methoxyphenyl)-1-phenyl-4-
hexyn-1-one (1aC)
HRMS (CI) calcd. for (M+) C12H11F3 212.0813, found
212.0808.
Yield 63%; 1H NMR d (ppm) 3.44 (1H, q, J = 6.60,
17.46 Hz), 3.58 (1H, q, J = 7.27, 17.45 Hz), 3.80 (3H, s),
4.52 (1H, oct., J = 3.40 Hz), 6.88–7.93 (9H, m); 13C NMR d
(ppm) 31.3, 46.0, 55.3, 70.1 (q, J = 52.6 Hz), 89.9
(q, J = 6.3 Hz), 114.0 (q, J = 256.9 Hz), 114.4, 128.1, 128.6,
128.7, 130.3, 133.6, 136.2, 159.1, 195.7; 19F NMR d (ppm)
4.3.12. 6,6,6-Trifluoro-3-methyl-1-phenyl-2-hexen-4-yne
(6m)
1
Yield 44%; H NMR d (ppm) 1.95 (3H, s), 3.50 (2H, d,
J = 7.64 Hz), 6.34 (1H, t, J = 7.56 Hz), 7.15–7.33 (5H, m); 13
C
À50.1 (3F, s); IR (neat) 2912, 2839, 2264, 1688 cmÀ1
;
NMR d (ppm) 16.1, 34.7, 72.9 (q, J = 52.1 Hz), 89.2 (q,
J = 6.4 Hz), 114.9 (q, J = 256.4 Hz), 115.21, 115.23,
126.6, 128.4, 128.7, 138.5, 142.68, 142.70; 19F NMR d
(ppm) À51.9 (3F, s); IR (neat) 3030, 2962, 2928, 2239,
1605 cmÀ1; HRMS (EI) calcd. for (M+) C13H11F3 224.0813,
found 224.0813.
HRMS (FAB) calcd. for (M+) C19H15F3O2 332.1024, found
332.1027.
4.4.5. 8,8,8-Trifluoro-5-(4-methoxyphenyl)-2,2-dimethyl-6-
octyn-3-one (1aD)
1
Yield 99%; H NMR d (ppm) 1.06 (9H, s), 2.90 (1H, q,
J = 6.87, 17.16 Hz), 3.07 (1H, q, J = 7.39, 17.19 Hz), 3.79
(3H, s), 4.35 (1H, m), 6.87 (2H, d, J = 8.56 Hz), 7.24 (2H, d,
J = 8.54 Hz); 13C NMR d (ppm) 25.7, 31.4, 43.9, 44.4,
55.2, 69.8 (q, J = 52.3 Hz), 90.0 (q, J = 6.6 Hz), 114.1
(q, J = 256.5 Hz), 114.3, 128.5, 130.2, 159.0, 211.3; 19F
NMR d (ppm) À50.2 (3F, s); IR (neat) 2972, 2839, 2264,
4.4. General procedure for the Nicholas reaction with
various carbon nucleophiles
The reaction was carried out according to the same
procedure as described for the Nicholas reaction with n-
Bu3SnH by using the corresponding carbon nucleophiles
(1.5 equiv.) in place of n-Bu3SnH.
1711, 1612, 1585, 1514, 1466, 1445 cmÀ1
;
HRMS
(FAB) calcd. for (M + H) C17H20F3O2 313.1415, found
313.1415.
4.4.1. 7,7,7-Trifluoro-4-(4-methoxyphenyl)-2-methyl-1-
hepten-5-yne (1aA1)
4.4.6. 2-[4,4,4-Trifluoro-1-(4-methoxyphenyl)-2-butynyl]-
cyclohexanone (1aE)
1
Yield 49%; H NMR d (ppm) 1.79 (3H, s), 2.49 (1H, q,
J = 6.40, 13.91 Hz), 2.58 (1H, q, J = 8.80, 13.93 Hz), 3.85 (3H,
s), 3.87 (1H, m), 4.80 (1H, s), 4.90 (1H, s), 6.92–6.95 (2H, m),
7.26–7.30 (2H, m); 13C NMR d (ppm) 22.3, 24.3, 35.3, 45.6,
70.7 (q, J = 52.1 Hz), 90.2 (q, J = 6.5 Hz), 114.3 (q,
J = 256.3 Hz); 19F NMR d (ppm) À51.7 (3F, s); IR (neat)
2926, 2841, 2257, 1610 cmÀ1; HRMS (FAB) calcd. for (M+)
C15H15F3O 268.1075, found 268.1078.
Combined yield 88%; Diastereomeric ratio = 1:1.
Diastereomer 1: 1H NMR d (ppm) 1.56–2.59 (9H, m), 3.79
(3H, s), 4.48 (1H, m), 6.87 (2H, d, J = 8.49 Hz), 7.22 (2H, d,
J = 8.46 Hz); 13C NMR d (ppm) 24.8, 27.3, 29.4, 35.2, 42.0,
55.2, 56.2, 71.8 (q, J = 52.1 Hz), 88.5 (q, J = 6.6 Hz), 114.08,
114.13 (q, J = 256.7 Hz), 128.9, 129.5, 158.9, 208.9; 19F NMR
d (ppm) À49.9 (3F, s); IR (neat) 2939, 2866, 2258, 1715 cmÀ1
;
HRMS (FAB) calcd. for (M+) C17H17F3O2 310.1181, found
310.1180.
4.4.2. 7,7,7-Trifluoro-4-(4-methoxyphenyl)-2-methyl-2-
hepten-5-yne (1aA2)
Diastereomer 2: 1H NMR d (ppm) 0.87–2.81 (9H, m), 3.80
(3H, s), 4.16 (1H, m), 6.86 (2H, d, J = 8.29 Hz), 7.22 (2H, d,
J = 8.28 Hz); 13C NMR d (ppm) 25.0, 27.7, 31.3, 35.4, 42.2,
55.2, 56.0, 69.6 (q, J = 52.1 Hz), 90.4 (q, J = 6.3 Hz), 114.0,
114.2 (q, J = 256.5 Hz), 128.1, 129.7, 159.0, 209.2; 19F NMR d
Yield 49%; 1H NMR d (ppm) 1.81 (6H, s), 3.84 (3H, s), 4.66
(1H, m), 5.30 (1H, dm, J = 9.12 Hz), 6.92–6.95 (2H, m), 7.26–
7.30 (2H, m); 13C NMR d (ppm) 18.1, 25.6, 34.7, 55.3, 69.8 (q,
J = 52.2 Hz), 89.5 (q, J = 6.5 Hz), 114.4 (q, J = 256.6 Hz); 19
F
NMR d (ppm) À51.9 (3F, s); IR (neat) 2926, 2841, 2257,
1610 cmÀ1; HRMS (FAB) calcd. for (M+) C15H15F3O
268.1075, found 268.1078.
(ppm) À49.9 (3F, s); IR (neat) 2939, 2866, 2255, 1713 cmÀ1
;
HRMS (FAB) calcd. for (M+) C17H17F3O2 310.1181, found
310.1180.

518
T. Konno et al. / Journal of Fluorine Chemistry 127 (2006) 510–518
[3] (a) T. Konno, J. Chae, T. Tanaka, T. Ishihara, H. Yamanaka, J. Fluorine
Chem. 127 (2006) 36.
4.4.7. Methyl 6,6,6-trifluoro-3-(4-methoxyphenyl)-2,
2-dimethyl-4-hexynoate (1aF)
(b) T. Konno, T. Daitoh, A. Noiri, J. Chae, T. Ishihara, H. Yamanaka,
Tetrahedron 61 (2005) 9391;
Yield 96%; 1H NMR d (ppm) 1.15 (3H, s), 1.33 (3H, s), 3.66
(3H, s), 3.79 (3H, s), 4.21 (1H, q, J = 3.60 Hz), 6.86 (2H, d,
J = 8.64 Hz), 7.17 (2H, d, J = 8.63 Hz); 13C NMR d (ppm) 21.5,
23.2, 44.6, 47.4, 52.0, 55.2, 71.7 (q, J = 52.3 Hz), 88.3 (q,
J = 6.4 Hz), 113.7, 114.1 (q, J = 256.8 Hz), 126.6, 130.3, 159.3,
175.8; 19F NMR d (ppm) À50.0 (3F, s); IR (neat) 2955, 2841,
2260, 1734 cmÀ1; HRMS (FAB) calcd. for (M+) C16H17F3O3
314.1130, found 314.1133.
(c) T. Konno, T. Daitoh, A. Noiri, J. Chae, T. Ishihara, H. Yamanaka, Org.
Lett. 6 (2004) 933;
(d) T. Konno, J. Chae, T. Tanaka, T. Ishihara, H. Yamanaka, Chem.
Commun. (2004) 690;
(e) T. Konno, T. Takehana, J. Chae, T. Ishihara, H. Yamanaka, J. Org.
Chem. 69 (2004) 2188;
(f) J. Chae, T. Konno, M. Kanda, T. Ishihara, H. Yamanaka, J. Fluorine
Chem. 120 (2003) 185.
[4] (a) T. Konno, J. Chae, T. Miyabe, T. Ishihara, J. Org. Chem. 74 (2005)
10172.
4.4.8. 6,6-Difluoro-3-(4-methoxyphenyl)-1-phenyl-4-
hexyn-1-one (1bC)
(b) T. Konno, J. Chae, T. Ishihara, H. Yamanaka, Tetrahedron 60 (2004)
11695;
Yield 96%; 1H NMR d (ppm) 3.39 (1H, q, J = 6.44,
17.34 Hz), 3.56 (1H, q, J = 7.46, 17.36 Hz), 3.77 (3H, s), 4.48
(1H, quint., J = 6.13 Hz), 6.17 (1H, t, J = 55.21 Hz), 6.86–7.92
(9H, m); 13C NMR d (ppm) 31.6, 46.3, 55.2, 74.1 (t,
J = 33.9 Hz), 91.4 (t, J = 7.1 Hz), 103.8 (t, J = 231.8 Hz),
114.2, 128.0, 128.5, 128.6, 131.1, 133.4, 136.3, 158.9, 196.1;
19F NMR d (ppm) À105.3 (2F, d, J = 53.7 Hz); IR (neat) 2839,
2251, 1688, 1612 cmÀ1; HRMS (FAB) calcd. for (M+)
C19H16F2O2 314.1118, found 314.1127.
(c) T. Konno, J. Chae, T. Ishihara, H. Yamanaka, J. Org. Chem. 69 (2004)
8258;
(d) J. Chae, T. Konno, T. Ishihara, H. Yamanaka, Chem. Lett. 33 (2004)
314;
(e) F.-L. Qing, W.-Z. Gao, J. Ying, J. Org. Chem. 65 (2000) 2003;
(f) F.-L. Qing, W.-Z. Gao, Tetrahedron Lett. 41 (2000) 7727;
(g) K. Tamura, T. Ishihara, H. Yamanaka, J. Fluorine Chem. 68 (1994)
25.
[5] (a) T. Hanamoto, Y. Hakoshima, M. Egashira, Tetrahedron Lett. 45
(2004) 7573;
(b) P.L. Porta, L. Capuzzi, F. Bettarini, Synthesis (1994) 287;
(c) H. Yamanaka, K. Tamura, K. Funabiki, K. Fukunishi, T. Ishihara, J.
Fluorine Chem. 57 (1992) 177;
4.4.9. 6,6,7,7,8,8-Hexafluoro-3-(4-methoxyphenyl)-1-
phenyl-4-octyn-1-one (1cC)
(d) G. Meazza, G. Zanardi, J. Fluorine Chem. 55 (1991) 199;
(e) T. Hiyama, K. Sato, Chem. Lett. (1990) 53;
(f) A.D. Allen, G. Angelini, C. Paradisi, A. Stevenson, T.T. Tidwell,
Tetrahedron Lett. 30 (1989) 1315;
Yield 87%; 1H NMR d (ppm) 3.44 (1H, q, J = 6.32,
17.43 Hz), 3.58 (1H, q, J = 7.68, 17.46 Hz), 3.80 (3H, s), 4.54
(1H, quint., J = 6.43 Hz), 6.04 (1H, tt, J = 5.54, 52.18 Hz),
6.88–7.93 (9H, m); 13C NMR d (ppm) 31.8, 46.1, 55.3, 69.6 (t,
J = 36.7 Hz), 95.7 (t, J = 6.6 Hz), 107.8 (tt, J = 31.2, 253.2 Hz),
107.1–110.1 (m), 114.4, 128.0, 128.5, 128.7, 130.1, 133.6,
136.2, 159.1, 195.8; 19F NMR d (ppm) À137.2 (2F, dquint.,
J = 8.5, 50.8 Hz), À131.6 (2F, m), À99.6 (2F, m); IR (neat)
2912, 2839, 2257, 1688, 1612 cmÀ1; HRMS (FAB) calcd. for
(M+) C21H16F6O2 414.1054, found 414.1057.
(g) M. Kuwabara, K. Fukunishi, M. Nomura, H. Yamanaka, J. Fluorine
Chem. 41 (1988) 227.
[6] (a) T. Konno, J. Chae, M. Kanda, G. Nagai, K. Tamura, T. Ishihara, H.
Yamanaka, Tetrahedron 59 (2003) 7571;
(b) N. Yoneda, S. Matsuoka, N. Miyaura, T. Fukuhara, A. Suzuki, Bull.
Chem. Soc. Jpn. 63 (1990) 2124;
Another methods for the preparation of the fluorine-containing alkynes
having an aromatic side chain are as follows
(c) J.E. Bunch, C.L. Bumgardner, J. Fluorine Chem. 36 (1987) 317;
(d) T. Hiyama, K. Sato, M. Fujita, Bull. Chem. Soc. Jpn. 62 (1989) 1352;
(e) G. Maezza, L. Capuzzi, P. Piccardi, Synthesis (1989) 331;
(f) Y. Kobayashi, T. Yamashita, K. Takahashi, H. Kuroda, I. Kumadaki,
Tetrahedron Lett. 23 (1982) 343.
References
[1] For reviews, see
[7] (a) A.K. Brindon, I.R. Crossley, Chem. Commun. (2002) 2420;
(b) T. Yamazaki, K. Mizutani, T. Kitazume, J. Org. Chem. 60 (1995)
6046.
(a) J.T. Welch, S. Eswarakrishnan, Fluorine in Bioorganic Chemistry,
John Wiley and Sons, New York, 1991;
(b) R. Filler, Y. Kobayashi (Eds.), Biomedicinal Aspects of Fluorine
Chemistry, Kodansha Limited/Elsevier Biomedical Press, Tokyo/New
York, 1982.
[8] M.P. Jennings, E.A. Cork, P.V. Ramachandran, J. Org. Chem. 65 (2000)
8763.
[9] For reviews, see
[2] For reviews, see
(a) B.J. Teobald, Tetrahedron 58 (2002) 4133;
(b) A.J. Fletcher, S.D.R. Christie, J. Chem. Soc., Perkin Trans. 1 (2000)
1657;
(a) K. Mikami, Y. Itoh, M. Yamanaka, Chem. Rev. 104 (2004) 1;
(b) X.-L. Qiu, W.-D. Meng, F.-L. Qing, Tetrahedron 60 (2004) 6711;
(c) R. Dave, B. Badet, P. Meffre, Amino Acids 24 (2003) 245;
(d) J.H.V. Steenis, A.V.D. Gen, J. Chem. Soc., Perkin Trans. 1 (2002)
2117;
(c) K.M. Nicholas, Acc. Chem. Res. 20 (1987) 207.
´ ´ ´
[10] (a) J.M. Betancort, T. Martın, J.M. Palazon, V.S. Martın, J. Org. Chem. 68
(2003) 3216;
(e) R.P. Singh, J.M. Shreeve, Tetrahedron 56 (2000) 7613;
(f) G.K.S. Prakach, A.K. Yudin, Chem. Rev. 97 (1997) 757;
(g) M.A. McClinton, D.A. McClinton, Tetrahedron 32 (1992) 6555.
(b) P. Magnus, R. Carter, M. Davies, J. Elliott, T. Pitterna, Tetrahedron 52
(1996) 6283;
(c) P. Magnus, R. Fairhurst, J. Chem. Soc., Chem. Commun. (1994) 1541.