Synthesis of fluorinated N-arylpyrazoles with perfluoro-2-methyl-2-pentene and arylhydrazines

Article abstract of DOI:10.1016/S0022-1139(99)00079-2

Reactions of arylhydrazines (phenyl, 2-nitrophenyl, 4-nitrophenyl, 2,4-dinitrophenyl, pentafluorophenyl, 4-trifluoromethyl-2,3,5,6-tetrafluorophenylhydrazine or 4,4′-dihydrazinooctafluorobiphenyl) with perfluoro-2-methyl-2-pentene in the presence of triet

Full text of DOI:10.1016/S0022-1139(99)00079-2

Journal of Fluorine Chemistry 98 (1999) 29±36
Synthesis of ¯uorinated N-arylpyrazoles with
per¯uoro-2-methyl-2-pentene and arylhydrazines
Ki-Whan Chia, Sung-Jun Kima, Tae-Ho Parkb, Yurii V. Gatilova,
Irina Yu. Bagryanskayaa, Georgii G. Furinc,*
aDepartment of Chemistry, University of Ulsan, Ulsan 680-749, South Korea
bKorea Research Institute of Chemical Technology, Taejeon 305-606, South Korea
cInstitute of Organic Chemistry, Russian Academy of Sciences, 630090,
Novosibirsk, Russian Federation
Received 29 September 1998; accepted 31 March 1999
Abstract
Reactions of arylhydrazines (phenyl, 2-nitrophenyl, 4-nitrophenyl, 2,4-dinitrophenyl, penta¯uorophenyl, 4-tri¯uoromethyl-2,3,5,6-
tetra¯uorophenylhydrazine or 4,40-dihydrazinoocta¯uorobiphenyl) with per¯uoro-2-methyl-2-pentene in the presence of triethylamine have
effectively produced 1-aryl-per¯uoro-3-ethyl-4-methylpyrazole and 1-aryl-per¯uoro-5-ethyl-4-methylpyrazole in various ratios depending
on the reaction conditions and arylhydrazine used. Syn- and anti-aminoimines which might be the intermediates for pyrazoles have been
isolated under appropriate conditions. The routes of formation for these products and the role of triethylamine have been discussed. The
reaction of per¯uoro-2-methyl-2-pentene with phenylhydrazine has been investigated in detail. The structure of 3-¯uoro-5-penta¯uoroethyl-
1-phenyl-4-tri¯uoromethylpyrazole has been elucidated by X-ray crystallography. # 1999 Elsevier Science S.A. All rights reserved.
Keywords: Per¯uoro-2-methyl-2-pentene; Arylhydrazines; Pyrazoles; Fluorinated N-arylpyrazoles; Structure 3-¯uoro-5-penta¯uoroethyl-1-phenyl-4-
tri¯uoromethylpyrazole
1. Introduction
has led to the development of a few general, but somewhat
limited, methods for their synthesis.
The synthesis of heterocyclic compounds containing
¯uorine has become an important part of ¯uoroorganic
chemistry [1]. Among nitrogen containing heterocyclic
compounds, azoles take such a pivotal place due to their
biological activities that various azole derivatives have been
prepared for medicinal and agricultural applications. More-
over, an attachment of ¯uorine-containing substituents to an
azole generally considerably increases its biological activity
[2]. For example, the introduction of a poly¯uorinated
benzene ring to a pyrazole has resulted in a sharp increase
in biological activity and these compounds have been
applied for the synthesis of herbicides and plant growth
regulators [3]. Fluoroalkyl derivatives of pyrazole have
drawn much attention for use as biologically active sub-
stances: herbicides, fungicides, insecticides, analgesics,
antipyretics and anti-in¯ammatores [4,5]. This, therefore,
Among approaches to obtain heterocycles with both
¯uorine atoms and per¯uoroalkyl groups, intermolecular
nucleophilic cyclization between two molecules containing
a potentially nucleophilic center at the double bond is
important [6]. Internal per¯uoroole®ns appear to be inter-
esting precursors in the above sense, because the creation of
a heterocyclic system is possible by the treatment of an
internal ole®n with either mononucleophilic or binucleo-
philic reagents. The route of the intramolecular nucleophilic
cyclization is determined by the electronic and steric factors
of the nucleophile. The tautomeric process at a double bond,
especially in the presence of a fragment containing a N±H
bond, makes it possible to synthesize 7±9 membered hetero-
cycles. Thus, Saloutin et al. [7,8] applied that concept for the
reaction of per¯uoro-2-pentene with ethylenediamine. Ikeda
et al. [9,10] used a similar methodology for the reaction of
per¯uoro-2-methyl-2-pentene with amides or hydrazones. In
these cases the authors suppose the formation of an inter-
mediate with the conjugated system C=C±C=N followed by
cyclization via a secondary nucleophilic addition to the
*Corresponding author. Fax: +7-3832-34-47-52; e-mail:
furin@nioch.nsc.ru
0022-1139/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved.
PII: S 0 0 2 2 - 1 1 3 9 ( 9 9 ) 0 0 0 7 9 - 2

30
K.-W. Chi et al. / Journal of Fluorine Chemistry 98 (1999) 29±36
terminal double bond. The synthesis of pyrazole derivatives
has been conducted by using substituted hydrazines and
per¯uoroole®ns [11±15].
In the process of our research on synthesizing azoles with
poly¯uorinated benzene rings, per¯uoro-2-methyl-2-pen-
tene(1) has been focused as a potential precursor for the
synthesis of various ¯uorinated pyrazoles by reaction
with arylhydrazines. The main purpose of this work consists
in the investigation of an intramolecular cyclization
during the reaction between an internal alkene and aryl
hydrazines.
Fig. 1. The molecular geometry of the pyrazole 10 (ORTEP diagram).
2. Results and discussion
vibrations in the IR spectra of the compounds 9 and 10.
The absorption intensity of the isomer 10 between 1300 and
As hydrazine reactants, phenylhydrazine(2), penta¯uoro-
phenylhydrazine(3), 4-(tri¯uoromethyl)-2,3,5,6-tetra¯uoro-
phenylhydrazine(4), 4,40-dihydrazinoocta¯uoro biphenyl(5)
2-nitrophenylhydrazine(6), 4-nitrophenylhydrazine(7) and
2,4-dinitrophenylhydrazine(8) were used since a substantial
in¯uence on the nuclophilicity of nitrogen atoms in the
hydrazine moiety was expected from the introduction of
nitro groups or ¯uorine atoms into the benzene ring. Triethy-
lamine was used as a base and its function was carefully
scrutinized.
1
1600 cm signi®cantly exceeds the corresponding inten-
sity of the isomer 9: pyrazole 9 [wavenumber (intensity)]
1200(100), 1325(67), 1356(60), 1520(79), 1595(59); pyr-
azole 10 1207(100), 1325(83), 1346(83), 1527(100),
1579(82). The frequency and intensity of C±F absorption
are set as references. The explanation of this phenomenon
lies in the effective conjugation of the electron pair of
nitrogen with the ꢀ-system of C=C±C=N in pyrazole 10
because of the higher positive charge on the sp2-hybridized
carbon atom a to N±Ph. Alternatively, the less positive
charge on this a-carbon reduces such conjugation in the
isomer 9 due to the less electron-withdrawing effect of
Reaction of the internal alkene 1 with phenylhydrazine(2)
in the presence of 2 equivalents of Et3N gave a mixture of
the pyrazole 9 and 10 in a 4:1 ratio and the pyrazoline 11.
However, treatment of 1 and phenylhydrazine with more
than 3 equivalents of Et3N produce 9 and 11, in yields 71%
and 7% respectively.
¯uorine atom (ꢁp 0.02) in respect to C2F5 group (ꢁp
0.69) [17]. The structure of 10 is con®rmed by X-ray
diffraction. According to X-ray data (Fig. 1 and Tables 1
and 2), the pyrazole 10 is nonplanar and the dihedral angle
between the two ring planes is 78.08.
IR spectra of the pyrazoles 9 and 10 differ from each other
1
in the band intensities near 1300±1600 cm and by the
frequencies of the C=C vibration. The presence of the
conjugated C=C and C=N bonds in a pyrazole ring leads
to the appearance of two absorption bands at 1500±
1600 cm 1. The isomers 9 and 10 contain FC=CCF3 and
CF3C=CC2F5 respectively. It is known that the replacement
of per¯uoroalkyl group at a C=C double bond by ¯uorine
results in an increase of the frequency of the carbon±carbon
vibration [16]. Indeed, the corresponding values of the C=C
In the presence of Et3N, reactions of 1 with hydrazine 3 or
4 at 0Ä408C in THF produced per¯uoro-N-phenyl-3-ethyl-
4-methyl-pyrazole(12)/per¯uoro-N-phenyl-5-ethyl-4-
methylpyrazole(13) and per¯uoro-N-(4-methylphenyl)-3-
ethyl-4-methylpyrazole(14)/ per-¯uoro-N-(4-methylphe-
nyl)-5-ethyl-4-methylpyrazole(15) in 4:1 or 3:1 ratios
respectively. The compounds 12±15 were isolated and
puri®ed by preparative silica gel chromatography and all
structures were con®rmed by spectroscopy and mass data.
Reaction of 1 with 2-nitrophenylhydrazine(6) gave the
pyrazole isomers 16 and 17 in an 1:1 ratio. However,
treatment of the hydrazine 5 with ole®n 1 gave a complex
bond in isomer 9 are located at 1520 and 1595 cm 1 and for
1
isomer 10, they are observed at 1527 and 1579 cm
.
Moreover, there is a substantial difference in the inten-
sities of the stretching and in plane deformation C=C

K.-W. Chi et al. / Journal of Fluorine Chemistry 98 (1999) 29±36
31
Table 1
Atomic coordinates (Â104) and equivalent isotropic displacement
Table 2
Ê
Bond lengths [A] and angles [deg] for compound 10
3
Ê 2
parameters (A Â10 ) for compound 10 (U(eq) is defined as one third of
C(5)±N(1)
C(5)±C(7)
1.331(8)
C(5)±C(4)
1.388(9)
the trace of the orthogonalized Uij tensor)
1.507(10) C(4)±C(3)
1.487(11) C(3)±F(1)
1.323(10) C(9)±C(14)
1.362(12)
1.311(9)
1.357(11)
1.454(8)
1.327(12)
1.374(11)
1.401(9)
1.296(11)
1.341(10)
1.316(10)
1.356(8)
Atom
x
y
z
U(eq)
C(4)±C(6)
C(3)±N(2)
N(1)
N(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
F(1)
35(3)
1936(4)
2001(5)
2840(7)
3299(5)
2666(6)
4219(6)
2748(7)
3553(8)
1111(5)
22(5)
4656(10)
5720(11)
4921(15)
3417(13)
3256
72(1)
90(2)
90(2)
72(2)
74(2)
95(3)
88(2)
93(2)
67(2)
79(2)
90(2)
94(2)
96(2)
84(2)
143(3)
157(3)
119(2)
135(3)
104(2)
107(1)
149(3)
117(2)
129(2)
C(9)±C(10)
1.399(9)
C(9)±N(1)
649(4)
C(10)±C(11)
C(12)±C(13)
C(7)±F(6)
1.377(10) C(11)±C(12)
1.438(12) C(13)±C(14)
1.356(10) C(7)±F(5)
1.480(13) C(8)±F(9)
1.295(10) C(8)±F(7)
1.307(10) C(6)±F(3)
1.346(10) N(2)±N(1)
1101(4)
749(4)
3(4)
C(7)±C(8)
C(8)±F(8)
1118(5)
2213(14)
1806(12)
2227(13)
5244(11)
4442(12)
5082(13)
6398(14)
7225(13)
6614(13)
5625(14)
2947(15)
668(11)
646(5)
C(6)±F(4)
1357(6)
686(4)
C(6)±F(2)
N(1)±C(5)±C(4)
C(4)±C(5)±C(7)
C(3)±C(4)±C(6)
F(1)±C(3)±N(2)
N(2)±C(3)±C(4)
C(14)±C(9)±N(1)
C(11)±C(10)±C(9)
106.2(5)
N(1)±C(5)±C(7)
C(3)±C(4)±C(5)
C(5)±C(4)±C(6)
F(1)±C(3)±C(4)
C(14)±C(9)±C(10)
C(10)±C(9)±N(1)
125.3(6)
749(5)
128.5(6)
126.8(7)
118.1(9)
114.6(6)
119.6(6)
117.8(7)
103.8(6)
129.4(7)
127.4(8)
121.2(6)
119.1(6)
1345(5)
1863(6)
1792(5)
1194(5)
1825(3)
1817(4)
1390(4)
629(4)
805(6)
522(6)
641(7)
1428(7)
3130(5)
4678(6)
3822(5)
5139(5)
1603(4)
3109(5)
3491(7)
4646(5)
3236(6)
C(12)±C(11)±C(10) 122.8(7)
C(14)±C(13)±C(12) 118.8(8)
F(2)
C(11)±C(12)±C(13) 119.1(7)
F(3)
C(9)±C(14)±C(13)
F(6)±C(7)±C(8)
F(6)±C(7)±C(5)
C(8)±C(7)±C(5)
F(9)±C(8)±F(7)
F(9)±C(8)±C(7)
F(7)±C(8)±C(7)
F(4)±C(6)±F(2)
F(4)±C(6)±C(4)
F(2)±C(6)±C(4)
C(5)±N(1)±N(2)
N(2)±N(1)±C(9)
120.3(7)
109.1(7)
110.5(6)
114.1(7)
109.6(7)
111.4(7)
107.8(8)
105.7(7)
114.0(6)
109.9(8)
113.4(5)
115.5(6)
F(6)±C(7)±F(5)
F(5)±C(7)±C(8)
F(5)±C(7)±C(5)
F(9)±C(8)±F(8)
F(8)±C(8)±F(7)
F(8)±C(8)±C(7)
F(4)±C(6)±F(3)
F(3)±C(6)±F(2)
F(3)±C(6)±C(4)
C(3)±N(2)±N(1)
C(5)±N(1)±C(9)
104.1(7)
108.2(7)
110.3(6)
110.5(9)
108.9(7)
108.6(7)
107.8(8)
102.4(7)
116.0(6)
102.1(6)
131.1(6)
F(4)
F(5)
1911(14)
1420(9)
967(3)
F(6)
289(3)
258(8)
F(7)
F(8)
1904(4)
1080(4)
1723(3)
877(11)
2347(10)
3692(10)
F(9)
H(10)
H(11)
H(12)
H(13)
H(14)
396
238
1563
1073
850
3511
4567
6788
8153
7132
80
80
80
80
80
1391
2261
2149
1143
2185
mixture of products, from which the pyrazole derivatives
18a and 18b were separated and identi®ed.
When electron-withdrawing groups are attached to the
phenyl ring in a arylhydrazine, its nucleophilicity is
expected to decrease so that it would be reasonable to
increase the reactivity of the counter-electrophile for a
better reaction.
The salt 19 was prepared for this purpose from 1 and Et3N
[15]. The effectiveness of such approach was demonstrated
by Shi et al. [16] for the synthesis of N-substituted 4-
¯uoropyrazolines. However, the yield of N-phenyl-substi-
tuted-4-¯uoropyrazoline was only 10%. Reaction of the salt
19 with 4-nitrophenylhydrazine (7) smoothly produced
pyrazole 21 in 65% yield. However, reaction of 19 with
To increase the reaction rate of nucleophilic addition to the
double bond, an activation of the internal double bond has
been conducted by the preliminary substitution of the
¯uorine atom at the C=C bond with a quaternary ammonium
group.

32
K.-W. Chi et al. / Journal of Fluorine Chemistry 98 (1999) 29±36
2,4-dinitrophenylhydrazine(8) in the presence of Et3N gave
the pyrazole 20 and the unexpected aminoimines 22a,b.
Compounds 22a and 22b were found to be the main
products of the reaction between 1 and 8, which is attributed
to the decreased basicity of the nitrogen atom of the
arylamino group.
hydrogen ¯uoride in the presence of Et3N to form the
terminal ole®n 27. Intramolecular nucleophilic cyclization
of 27 produces pyrazole 29.
Route b: The ole®n 1 is isomerized to per¯uoro-2-methyl-
1-pentene which is considerably more reactive than the
internal per¯uoroole®n 1. Presence of secondary amines
and/or ¯uoride ions in the reaction accelerates the isomer-
ization. It is interesting to note that 2H-per¯uoro-2-methyl-
pentane was detected in some reactions. This indicates that
the formation of a corresponding carbanion which is respon-
sible for the isomerization. Nucleophilic addition of arylhy-
drazine to per¯uoro-2-methyl-1-pentene followed by
elimination of HF and intramolecular cyclization provides
the pyrazole 33.
These results clearly indicate that Et3N is crucial for the
formation of a terminal double bond from 25 which leads to
the isomer 9.
MeCN
!
1 ‡ 2PhNHNH2
9 ‡ 25a ‡ 25b
08C; 1 h
208C; 2 h
Since the catalytic effect of a dialkylamine for the iso-
merization of an internal ole®n into a terminal one is known
[6], production of the pyrazole 10 from 1 could be ratio-
nalized by the isomerization of 1 before the nucleophilic
addition. In other words, addition of hydrazine 2 occurs on
per¯uoro-2-methyl-1-pentene, not on 1 for the formation of
10. On the other hand, the presence of triethylamine evi-
dently facilitates the nucleophilic attack of arylhydrazines
by the formation of the salt 19 from 1. Also, triethylamine
acts as an acid scavenger to accelerate the irreversible
formation of a pyrazole ring and
In conclusion, reaction of the internal per¯uoroole®n 1
with arylhydrazine in the presence of triethylamine gives a
mixture of two isomeric pyrazoles 29 and 33. By using this
method, various ¯uorinated N-arylhydrazines can be
synthesized.
accordingly reduces the chances of isomerization of 1 to
per¯uoro-2-methyl-1-pentene. This explains the fact that
more of isomer 10 is produced from 1 and phenylhydrazine
if less of Et3N is used.
Thus, it is possible to assume plausible reaction routes
from 1 and arylhydrazine to the two pyrazole isomers.
Route a: An initial attack of arylhydrazine on the double
bond of 1 gives intermediate 26 followed by elimination of
3. Experimental
3.1. Instrumentation
19F NMR spectra were recorded at 282.2 MHz with a
Varian UNITY plus-300 spectrometer and obtained in the
presence of C6F6 as an internal standard; 13C and 1H NMR
spectra were recorded at 75.4 MHz and 300.1 MHz with a

K.-W. Chi et al. / Journal of Fluorine Chemistry 98 (1999) 29±36
33
Bruker AM 400 spectrometer in ppm w.r.t. tetramethylsilane
ꢀC8;1 JCF ˆ 286;2 JCF ˆ 36:4†,
110.2
254;2 JCF ˆ 40:2†, 97.0 (C4, JCF ˆ 35; HRMS found
ꢀC7;1 JCF
ˆ
2
(JCH not recorded). IR spectra were taken on a Mattson
5000 FTIR (NICAM) spectrometer (5% in CCl4). Mass
spectra were determined with a JEOL LMS-DX 303 spec-
trometer. All reactions were monitored routinely by
19F NMR spectroscopy. Column chromatography was con-
ducted with silica gel 60 (70-230 mest ASTM). GLC
analysis was on an LKM-72 chromatograph (50±2708C),
4000Â4 mm, SKTFW-803 on Chromosorb W. All the che-
micals were of analytical grade and used without further
puri®cation. Tetrahydrofuran was distilled from potassium
benzophenone ketyl.
348.0313 C12H5F9N2 calcd. 348.0309. Mass spectrum,
‡
‡
‡
m/e 348 [M] , 329 [M±F] , 279 [M±CF3] . 3-Fluoro-5-
penta¯uoroethyl-4-tri¯uoromethyl-1-phenylpyrazole (10)
(2.8 g, 16% yield); m.p. 63±648C (hexane); 1H NMR
(CDCl3) ꢃH 7.43 (H11, 2H, m), 7.39 (H10, 2H, m), 7.33
(H12, 1H, m); 19F NMR (CDCl3) ꢃF 102.2 (F6, 3F, dt,
JFFˆ14 and 11.3), 83.0 (F8, 3F, s), 55.8 (F7, 2F, q,
JFFˆ11.3), 37.8 (F3, 1F, q, JFFˆ14); 13C NMR (CDCl3)
ꢃC 159.1 ꢀC3;1 JCF ˆ 253;3 JCF ˆ 4:7†, 138.2 (C9), 130.5
(C11), 128.7 (C10), 128.6 (C12), 126.0 ꢀC5;2 JCF ˆ 11:4†,
120.2 ꢀC6;1 JCF ˆ 268;3 JCF ˆ 4:7†, 117.9 ꢀC8;1 JCF
ˆ 286;2 JCF ˆ 37:4†, 109.0 ꢀC7;1 JCF ˆ 259;2 JCF ˆ 41:9†,
99.2 ꢀC4;2 JCF ˆ 41:5;3 JCF ˆ 17:2†. HRMS calcd.
348.0309 for C12H5F9N2 found 348.0306. Mass spectrum,
X-ray structure analysis was carried out on a Syntex P21
diffractometer using Cu Ka radiation with a graphite mono-
chromator. X-ray structure data for 10 C12H5F9N2,
Mˆ348.18, orthorhombic, space group Pca21, aˆ
‡ ‡ ‡
Ê
Ê 3
15.965(3), bˆ11.109(3), cˆ7.519(2) A, Vˆ1333.5(6) A ,
m/e 348 [M] , 329 [M±F] , 279 [M±CF3] , 259 [M±CF3±
‡
3
‡
‡
‡
‡
Dcˆ1.734 gÁcm
,
Zˆ4, F(000)ˆ688, m(Cu Ka)ˆ
HF] , 119 [C2F5] , 105 [PhN2] , 92 [PhNH] , 69 [CF3] .
1.77 mm 1. 1293 intensities of independent re¯ections were
measured (ꢂ/2ꢂ-scan, 2ꢂ<1408) for a crystal sample sealed
in a polyethylene capillary. Evaporation (10% drop) and
empirical absorption (transmission 0.63±0.97) corrections
were applied. The structure was solved by direct methods
and re®ned in an anisotropic approximation using program
SHELXL-97. Riding model was used for hydrogen atoms
re®nements. The ®nal R-factors are wR2ˆ0.2161, Sˆ1.043
for all data (Rˆ0.0721 for 898 Fo>4ꢁ). Atomic coordinates,
bond lengths and bond angles have been deposited at the
Cambridge Crystallographic Data Center.
3.2.2. Synthesis of the pyrazole 9 and 5,5-difluoro-3-
pentafluoroethyl-4-trifluoromethyl-1-phenyl-4[H]-
pyrazoline (11)
To a solution of compound 1 (10 g, 0.033 mol) in THF
(40 ml) was added dropwise at 08C a mixture of phenylhy-
drazine (2) (3.6 g, 0.033 mol) and Et3N (10.1 g, 0.10 mol)
with stirring for 15 min. After addition, stirring was con-
tinued for 1 h at 08C and then for additional 1 h at room
temperature. The resulting solution was neutralized with 5%
aqueous H2SO4 and extracted with CH2Cl2 (3Â50 ml). The
concentrate was distilled under reduced pressure to give a
liquid, which was further puri®ed by column chromatogra-
phy (hexane). 5-Fluoro-3-penta-¯uoroethyl-; 4-tri¯uoro-
methyl-1-phenylpyrazole (9) (8.1 g, 71% yield). 5,5-
Di¯uoro-3-penta¯uoroethyl-; 4-tri¯uoromethyl-1-phenyl-
4[H]-pyrazoline (11) (0.8 g, 7% yield); b.p. 66±678C
3.2. Reaction compound 1 with arylhydrazines
3.2.1. Synthesis of 5-fluoro-3-pentafluoroethyl-4-
trifluoromethyl-1-phenyl pyrazole (9) and 3-fluoro-
5-pentafluoroethyl-4-trifluoromethyl-1-phenyl
pyrazole (10)
(1.5 Torr); H NMR (CDCl3) ꢃH 3.94 (H4, 1H, m), 7.07
1
A mixture of 1 (15.0 g, 0.050 mol) and Et3N (10.1 g,
0.10 mol) in MeCN (45 ml) was stirred at 458C for 2.5±
3.0 h. To the resulting solution was added dropwise at 08C
phenylhydrazine (2) (5.4 g, 0.050 mol) over 15 min. After
the addition, stirring was continued for 1 h at 08C and then
for an additional 2 h at room temperature. The reaction
mixture was diluted with water, and extracted with CH2Cl2.
The organic phase was concentrated and distilled under
reduced pressure to give a yellow liquid (14.5 g, 60±628C at
1.5 Torr). The distillate was further puri®ed by column
chromatography (hexane) to provide 9 and 10. 5-Fluoro-
3-penta¯uoroethyl-4-tri¯uoromethyl-1-phenylpyrazole (9)
(11.1 g, 64% yield); 60±628C (1.5 Torr); 1H NMR (CDCl3)
ꢃH 7.61 (H10, 2H, d, JHHˆ5.1), 7.55 (H12, 1H, t, JHHˆ4.5),
7.50 (H11, 2H, td, JHHˆ5.1 and 4.5); 19F NMR (CDCl3) ꢃF
41.7 (F5, 1F, q, JFFˆ15.3), 107.2 (F6, 3F, dt, JFFˆ15.3 and
9.2), 80.2 (F8, 3F, s), 52.2 (F7, 2F, q, JFFˆ9.2); 13C NMR
(H11, 2H, m), 6.78 (H10,12, 3H, m); 19F NMR ꢃF 100.2 (F6,
3F, m), 82.5 (F8, 3F, s), 49.3 (F5, 2F, m), 37.4 (F7, 2F, m);
HRMS calcd. 368.0371 for C12H6F10N2 found 368.0376.
3.2.3. Synthesis of perfluoro-3-ethyl-4-methyl-1-
phenylpyrazole (12) and perfluoro-5-ethyl-4-methyl-
1-phenylpyrazole (13)
To a solution of 1 (10.0 g, 0.033 mol) and Et3N (10.1 g,
0.10 mol) in THF (35 ml) at 08C was added dropwise
a solution of penta¯uorophenylhydrazine (3) (6.53 g,
0.033 mol) in THF (10 ml). The resulting solution was
stirred for 3 h at room temperature and then for 2 h at
458C. The reaction mixture was ®ltered and the ®ltrate
was washed with water (2Â50 ml) and dried (MgSO4).
Distillation of the crude product under reduced pressure
gave a colorless oil (b.p. 58±808C at 3 Torr) which was
puri®ed by column chromatography (hexane-CH2Cl2, 5:1).
Per¯uoro-3-ethyl-4-methyl-1-phenylpyrazole (12) (9.2 g,
63% yield); b.p. 58±598C (3 Torr); 19F NMR (CDCl3) ꢃF
107.8 (F6, 3F, s), 79.7 (F8, 3F, s), 52.2 (F7, 2F, s), 42.2 (F5,
5
(CDCl3) ꢃC 151.0, ꢀ C;1 JCF ˆ 294;3 JFF4:7†, 137.5
ꢀC3;2 JCF ˆ 32:2†, 135.5 (C9), 130.0 (C11), 129.7 (C12),
122.2 (C10), 120.4 ꢀC6;1 JCF ˆ 268;3 JCF ˆ 4:7†, 118.8

34
K.-W. Chi et al. / Journal of Fluorine Chemistry 98 (1999) 29±36
1F, m), 19.5 (F10, 2F, m), 15.3 (F12, 1F, m), 2.4 (F11, 2F, m);
JCF ˆ 32:3†, 120.5 ꢀC13;1 JCF ˆ 278†, 119.7 ꢀC6;1 JCF
ˆ
13C NMR (CDCl3) ꢃC 161.4 ꢀC5;1 JCF ˆ 258;3 JCF ˆ 4:4†,
264;3 JCF ˆ 5:4†, 118.1 ꢀC8;1 JCF ˆ 264;2 JCF ˆ 38:0†,
145.3 ꢀC10;1 JCF ˆ 256;2 JCF ˆ 30†, 144.6 ꢀC12;1 JCF
ˆ
117.4 ꢀC5;2 JCF ˆ 30:0†, 109.8 ꢀC7;1 JCF ˆ 254;2 JCF
ˆ
266;2 JCF ˆ 29:0†, 138.4 ꢀC3;2 JCF ˆ 30:3†, 134.1 ꢀC9;2
JCF ˆ 29:1†, 120.1 ꢀC6;1 JCF ˆ 268;3 JCF ˆ 4:5†, 118.4
ꢀC8;1 JCF ˆ 286;2 JCF ˆ 41:9†, 109.4 ꢀC7;1 JCF ˆ 259;2
JCF ˆ 42:2†, 103.8 ꢀC4;2 JCF ˆ 42:2;2 JCF ˆ 42:8†; IR
1596 (C=C), 1537 (C=N), 1523 (C=Car), 1350 (C±N),
1213±1116 (C±F) cm 1; HRMS calcd. 437.9838 for
C12F14N2 found 437.9833; Mass spectrum, m/e 438
40:5†, 96.4 ꢀC4;2 JCF ˆ 42:4†; IR 1658 (C=C), 1539
1
(C=N), 1510 (C=Car), 1352 (C±N), 1200±1170 (C±F) cm
.
3.2.5. Synthesis of 5-fluoro-1-(2-nitrophenyl)-3-
pentafluoroethyl-4-trifluoromethylpyrazole (16)
and 3-fluoro-1-(2-nitrophenyl)-5-pentafluoroethyl-
4-trifluoromethylpyrazole (17)
‡
‡
‡
‡
‡
[M] , 419 [M±F] , 369 [M±CF3] , 319 [M±C2F5] , 300
Reaction of 1 (15.0 g, 0.05 mol) with 2-nitrophenylhy-
drazine (6) (7.65 g, 0.05 mol) and Et3N (12.6 g, 0.12 mol) in
THF (40 ml) was conducted at 08C for 30 min and then for
6 h at 208C. Fractional distillation of the crude product
afforded 16 and 17 with an 1:1 ratio (by 19F NMR data) as a
colorless liquid (5.8 g, 30% yield); b.p. 127±1288C
(0.5 Torr); HRMS calcd. 393.0159 for C12H4F9N3O2 found
‡
[M±2CF3] . 281, 255, 69 [CF3] . Per¯uoro-5-ethyl-4-
methyl-1-phenylpyrazole (13) (2.3 g, 16% yield); b.p. 89±
908C (3 Torr); 19F NMR (CDCl3) ꢃF 107.0 (F6, 3F, s), 80.2
(F8, 3F, s), 51.9 (F7, 2F, s), 43.2 (F3, 1F, m), 18.3 (F10, 2F, m),
15.3 (F12, 1F, m), 3.2 (F11, 2F, m); 13C NMR (CDCl3) ꢃC
152.9 ꢀC3;1 JCF ˆ 296;3 JCF ˆ 5:4†, 144.8 ꢀC12;1 JCF
ˆ
‡ ‡
265;2 JCF ˆ 31:2†, 145.4 ꢀC10;1 JCF ˆ 267;2 JCF ˆ 29:8†,
393.0153; Mass spectrum, m/e [M] (100), 374 [M±F] ,
‡ ‡
346, 327, 324 [M±CF3] , 277, 169 [C3F7] , 150, 119
141.5 ꢀC9;2 JCF ˆ 28:4†, 138.1 ꢀC11;1 JCF ˆ 268;2 JCF
ˆ
‡
‡
‡
29:7†, 121.5 ꢀC6;1 JCF ˆ 268;3 JCF ˆ 5:4†, 118.5 ꢀC8;1 JCF
ˆ 286;2 JCF ˆ 41:9†, 109.7 ꢀC7;1 JCF ˆ 260;2 JCF ˆ 41:2†,
113.7 ꢀC5;2 JCF ˆ 29:0†, 94.0 ꢀC4;2 JCF ˆ 42:8†; IR 1600
[C2F5] , 100 [CF2=CF2] , 69 [CF3] . The distillate was
further puri®ed by column chromatography (hexane-
CH2Cl2, 5:2). 5-Fluoro-1-(2-nitrophenyl)-3-penta¯uoro-
ethyl-4-tri¯uoromethylpyrazole (16), 3.4 g; b.p. 127±
(C=C), 1540 (C=N), 1520 (C=Car), 1352 (C±N), 1200±
1
1
1170 (C±F) cm
.
1288C (0.5 Torr); H NMR (CDCl3) ꢃH 8.15, 7.74, 7.75;
19F NMR (CDCl3) ꢃF 107.2 (F6, 3F, s), 80.0 (F8, 3F, t,
JFFˆ9), 57.8 (F7, 2F, q, JFFˆ9), 42.5 (F5, 1F, m); 13C NMR
(CDCl3) ꢃC 159.4 ꢀC5;1 JCF ˆ 255†, 144.0 (C9), 138.1
ꢀC3;2 JCF ˆ 32:5†, 133.5 (C10), 131.3 (C11), 130.4 (C13),
127.8 (C12), 124.9 (C14), 119.3 ꢀC6;1 JCF ˆ 268†, 117.6
ꢀC8;1 JCF ˆ 286;2 JCF ˆ 36:2†, 109.0 ꢀC7;1 JCF ˆ 254;2
JCF ˆ 39:9†, 94.3 ꢀC4;2 JCF ˆ 42:3;2 JCF ˆ 9:1†; IR (5%
CCl4) 1610, 1590, 1545 (C=C±C=N), 1520, 1350 (NO2),
1270 (C±N), 1220±1150 (C±F) cm 1. 3-Fluoro-1-(2-nitro-
phenyl)-5-penta¯uoroethyl-4-tri¯uoromethylpyrazole (17),
1.5 g; b.p. 127±1288C (0.5 Torr); 1H NMR (CDCl3) ꢃH
8.05, 7.74, 7.60; 19F NMR (CDCl3) ꢃF 107.9 (F6, 3F, s),
80.0 (F8, 3F, t, JFFˆ9), 56.2 and 51.7 (F7, 2F, AB-system,
JFFˆ307), 39.6 (F5, 1F, m); 13C NMR (CDCl3) ꢃC 151.1
ꢀC5;1 JCF ˆ 293†, 143.4 (C9), 138.1 ꢀC3;2 JCF ˆ 32:5†,
133.3 (C10), 131.1 (C11), 129.3 (C13), 126.4 (C12), 124.8
3.2.4. Synthesis of perfluoro-3-ethyl-4-methyl-1-(4-
tolyl)pyrazole (14) and perfluoro-5-ethyl-4-methyl-
1(40-tolyl)pyrazole (15)
Reaction of 1 (10.0 g, 0.033 mol) with 4-(tri¯uoro-
methyl)-2,3,5,6-tetra¯uorophenylhydrazine (4) (8.18 g,
0.033 mol) and Et3N (10.1 g, 0.10 mol) was conducted by
the same procedure as for 12. Fractional distillation of the
crude product afforded a colorless liquid (b.p. 73±828C at
3 Torr), which was further puri®ed by column chromato-
graphy (hexane-CH2Cl2, 5:1). Per¯uoro-3-ethyl-4-methyl-
1-(4-tolyl)pyrazole (14) (9.0 g, 55% yield); b.p. 73±748C
(3 Torr); 19F NMR (CDCl3) ꢃF 107.8 (F13, 3F, s), 106.7 (F6,
3F, s), 79.7 (F8, 3F, s), 52.0 (F7, 2F, m), 42.8 (F5, 1F, m), 25.3
(F10, 2F, m), 21.6 (F11, 2F, m); 13C NMR (CDCl3) ꢃC 161.4
ꢀC5;1 JCF ˆ 259;3 JCF ˆ 5:4†, 144.7 ꢀC10;1 JCF ˆ 262†,
144.8 ꢀC11;1 JCF ˆ 256†, 133.4 ꢀC9;2 JCF ˆ 31:9†, 120.5
ꢀC13;1 JCF ˆ 278†, 119.6 ꢀC6;1 JCF ˆ 265;3 JCF ˆ 5:4†,
(C14), 119.2 ꢀC6;1 JCF ˆ 268†, 117.0 ꢀC8;1 JCF
ˆ
287;2 JCF ˆ 37:2†, 108.2 ꢀC7;1 JCF ˆ 253;2 JCF ˆ 44:4†,
100.8 ꢀC4;2 JCF ˆ 41:4;2 JCF ˆ 17:7†; IR (5% CCl4):
118.1 ꢀC8;1 JCF ˆ 287;2 JCF ˆ 37:0†, 114.4 ꢀC3;2 JCF
30:0†, 113.8 ꢀC12;2 JCF ˆ 35:8†, 109.1 ꢀC7;1 JCF
ˆ
ˆ
1615, 1545, 1590, 1520, 1320 (NO2), 1270 (C±N), 1220±
1150 (C±F) cm
1
259;2 JCF ˆ 42:2†, 103.8 ꢀC4;2 JCF ˆ 42:3†; IR 1593
(C=C), 1539 (C=N), 1510 (C=Car), 1352 (C±N), 1200±
1164 (C±F) cm 1; HRMS calcd. 487.9805 for C13F16N2
.
3.2.6. Synthesis of 4,40-bis(perfluoro-3-ethyl-40-
methylpyrazolyl-1)-octafluorobiphenyl (18a) and
4,40-bis(perfluoro-5-ethyl-4-methylpyrazolyl-1)-
octafluorobiphenyl (18b)
A reaction mixture of 1 (12.0 g, 0.040 mol), 4,40-dihy-
drazinoocta¯uorobiphenyl (5) (7.16 g, 0.020 mol) and Et3N
(12.1 g, 0.12 mol) in THF (45 ml) was stirred at room
temperature for 3 h and then for 2 h at 508C. Fractional
distillation of the crude product gave compounds 18a,b
(10.2 g, 61% yield) as a colorless liquid; b.p. 177±1798C
‡
found 487.9805; Mass spectrum, m/e 488 [M] , 469 [M±
‡
‡
‡
‡
‡
F] , 419 [M±CF3] , 369 [M±C2F5] , 319 [M±C3F7] , 281,
‡
274, 254, 217 [C6F4CF3] , 69 [CF3] . Per¯uoro-5-ethyl-4-
methyl-1(40-tolyl)pyrazole (15) (2.9 g, 18% yield); b.p. 80±
828C (3 Torr); 19F NMR (CDCl3) ꢃF 107.7 (F13, 3F, s),
106.7 (F6, 3F, s), 80.3 (F8, 3F, s), 51.9 (F7, 2F, m), 43.8
(F3, 1F, m), 26.0 (F10, 2F, m), 20.1 (F11, 2F, m); 13C NMR
(CDCl3) ꢃC 152.5 ꢀC3;1 JCF ˆ 298;3 JCF ˆ 5:4†, 145.2
ꢀC10;1 JCF ˆ 265†, 143.5 ꢀC11;1 JCF ˆ 257†, 141.9 ꢀC9;2

K.-W. Chi et al. / Journal of Fluorine Chemistry 98 (1999) 29±36
35
(0.2 Torr); elemental analysis calcd. C 34.37, F 58.95, N
6.68 for C12F13N2 found C 34.21, F 59.07, N 7.21%. The
distillate was further puri®ed by column chromatography
(hexane-CH2Cl2, 3:1). 4,40-Bis-(per¯uoro-3-ethyl-4-me-
thylpyrazolyl-1)-octa¯uorobiphenyl (18a) (6.4 g, 38%
yield); 19F NMR (CDCl3-acetone) ꢃF 107.2 (F6, 3F, s),
80.5 (F8, 3F, t, JFFˆ9), 52.3 (F7, 2F, q, JFFˆ9), 45.1 (F5,
1F, m), 28.1 (F10, 2F, m), 19.1 (F11, 2F, m); 13C NMR
(C11), 129.0 (C14), 119.7 ꢀC6;1 JCF ˆ 269;3 JCF ˆ 5:4†,
118.3 ꢀC8;1 JCF ˆ 286;2 JCF ˆ 35:9†, 109.6 ꢀC7;1 JCF
ˆ
254;2 JCF ˆ 40:2†, 96.6 ꢀC4;2 JCF ˆ 51:8†; IR 3117, 1626
1
(C=C), 1547 (C=N), 1352 (C±N), 1200±1170 (C±F) cm
HRMS calcd. 438.0008 for C13H3F9N4O4 found 437.9292;
;
‡
‡
Mass spectrum, m/e 438 [M] , 419 [M±HF] , 391 [M±
‡
NO2] .
(CDCl3) ꢃC 151.9 ꢀC5;1 JCF ˆ 297†, 143.8 ꢀC10;1 JCF
ˆ
3.2.8. Synthesis of 5-fluoro-3-pentafluoroethyl-4-
trifluoromethyl-1-(4-nitrophenyl)pyrazole (21)
251†, 142.4 ꢀC11;1 JCF ˆ 268†, 141.3 ꢀC9;2 JCF ˆ 28:0†,
132.3 ꢀC3;2 JCF ˆ 32:0†, 119.0 ꢀC6;1 JCF ˆ 268†, 117.6
ꢀC8;1 JCF ˆ 286;2 JCF ˆ 39:7†, 108.6 ꢀC7;1 JCF ˆ 260;2
JCF ˆ 30:8†, 108.5 ꢀC12;2 JCF ˆ 39:5†, 94.7 ꢀC4;2 JCF
ˆ 34:2†. 4,40-Bis-(per¯uoro-5-ethyl-4-methylpyrazolyl-1)-
octa¯uorobiphenyl (18b) 93.2 g, 19% yield); 19F NMR
(CDCl3-acetone) ꢃF 107.9 (F6, 3F, s), 79.7 (F8, 3F, t, JFFˆ9),
52.0 (F7, 2F, q, JFFˆ9), 42.4 (F3, 1F, m), 25.3 (F10, 2F, m),
20.2 (F11, 2F, m); 13C NMR (CDCl3) ꢃC 160.3
ꢀC3;1 JCF ˆ 260†, 143.8 ꢀC10;1 JCF ˆ 251†, 142.4 ꢀC11;1
Treatment of 4-nitrophenylhydrazine (7) (5.1 g,
0.033 mol) with 1 (10.0 g, 0.033 mol) and Et3N (10.1 g,
0.10 mol) in MeCN (65 ml) by the same procedure for 20
produced 5-¯uoro-3-penta¯uoroethyl-4-tri¯uoromethyl-1-
(4-nitrophenyl)pyrazole (21) as a yellow liquid (8.4 g,
65% yield); b.p. 66±678C (2.5 Torr); 1N NMR (CDCl3)
ꢃH 8.46 (H11, 2H, d, JHHˆ9.1), 8.08 (H10, 2H, d, JHHˆ9.1);
19F NMR (CDCl3) ꢃF 43.8 (F5, 1F, q, JFFˆ14.6), 106.7 (F6,
3F, qt, JFFˆ14.6 and 9.7), 79.3 (F8, 3F, s), 51.6 (F7, 2F, q, JFF
JCF ˆ 268†, 141.3 ꢀC9;2 JCF ˆ 28:0†, 132.3 ꢀC5;2 JCF
32:0†, 119.1 ꢀC6;1 JCF ˆ 268†, 117.5 ꢀC8;1 JCF
ˆ
ˆ
ˆ9.7); 13C NMR (CDCl3) ꢃC 152.3 ꢀC5;1 JCF
ˆ
296;3 JCF ˆ 4:7†, 148.6 (C9), 141 (C12), 140
ꢀC3;2 JCF ˆ 32:3†, 126.2 (C11), 123.4 (C10), 120.8
ꢀC6;1 JCF ˆ 268;3 JCF ˆ 4:7†, 119.4 ꢀC8;1 JCF ˆ 286;2
JCF ˆ 36:2†, 110.5 ꢀC7;1 JCF ˆ 254;2 JCF ˆ 32:5†, 97.5
ꢀC4;2 JCF ˆ 32:3†; IR 3115 (C±Har), 1622 (C=C), 1522
(C=N), 1350 (C±N), 1200±1150 (C±F) cm 1; HRMS calcd.
393.0159 for C12H4F9N3O2 found 393.0158; Mass spec-
286;2 JCF ˆ 39:7†, 108.4 ꢀC7;1 JCF ˆ 260;2 JCF ˆ 30:8†,
108.4 ꢀC12;2 JCF ˆ 39:5†, 94.6 ꢀC4;2 JCF ˆ 34:2†.
3.2.7. Synthesis of 1-(2,4-dinitrophenyl)-5- fluoro-3-
pentafluoroethyl-4-trifluoromethylpyrazole (20)
and N-2,4-dinitrophenyl-N-[3,3,3-trifluoro-1
‡ ‡ ‡
pentafluoroethyl-2-trifluoromethyl-
propylidene]hydrazines (22a,b)
trum, m/e 393 [M] , 374 [M±F] , 363 [M±NO] , 347 [M±
‡
‡
NO2] , 324 [M±CF3] .
A solution of 1 (15.1 g, 0.050 mol) and Et3N (10.1 g,
0.10 mol) in MeCN (40 ml) was stirred at 458C for 2±3 h. To
the resulting solution was added dropwise at 08C a mixture
of 2,4-dinitrophenylhydrazine (8) (6.6 g, 0.033 mol) and
Et3N (5.05 g, 0.050 mol) over 15 min. After the addition,
stirring was continued for 1 h at 08C and then for 2 h at room
temperature. The reaction mixture was diluted with water
and extracted with CH2Cl2. The organic phase was con-
centrated and distilled to give liquid products, which were
further separated by column chromatography with hexane-
CH2Cl2 (10:1). Syn- and anti-N-2,4-Dinitrophenyl-N-
[3,3,3-tri¯uoro-1(penta¯uoroethyl-2-tri¯uoromethylpropy-
lidene]hydrazine (22a,b) (2:1 ratio, 11.5 g, 48% yield); b.p.
102±1038C (1 Torr); 1H NMR (CDCl3) ꢃH 4.33 (H2, 1H, m),
8.40 (H11, 1H, m), 8.04 (H13,14, 2H, m), 12.36 (H8, 1H, s);
19F NMR (CDCl3) ꢃF 98.1 (F1,6, 6F, s), 79.9 (F5, 3F, s), 45.9
(F4, 2F, s); HRMS calcd. 478.0135 for C12H5F11N4J4 found
3.2.9. Synthesis of N-phenyl-N-[3,3,3-trifluoro-1-
pentafluoroethyl-2-trifluoromethylpropylidene]-
hydrazines (25a,b)
To a solution of 1 (30 g, 0.10 mol) in THF (30 ml) at 08C
was added dropwise phenylhydrazine (21.6 g, 0.20 mol) in
THF (20 ml) with stirring. After the addition, stirring was
continued for 1 h at 08C and then for 2 h at 208C. The
reaction mixture was ®ltered and the ®ltrate was distilled
under reduced pressure to give a yellow liquid (32 g), b.p.
64±658C at 0.3 Torr, which was a mixture of syn- and anti-
isomers N-phenyl-N0-[3,3,3-tri¯uoro-1-penta¯uoroethyl-2-
tri¯uoromethylpropylidene]hydrazine (25a and 25b) (3:2
ratio) and 9. The mixture 25a and 25b ± HRMS calcd.
388.0433 for C12H7F11N2 found 388.0432; Mass spectrum,
‡
‡
‡
‡
m/e 388 [M] , 369 [M±F] , 319 [M±CF3] , 119 [C2F5] ,
‡
‡
105 [PhN2] , 92, 77 [Ph] . 25a ± 1H NMR (CDCl3) ꢃH 3.83
(C±H, m), 8.73 (H±N, s), 7.08 (H11) and 6.90 (H10,12);
19F NMR (CDCl3) ꢃF 97.9 (F1,6, 6F, s), 79.3 (F5, 3F, s), 47.2
(F4, 2F, s); 13C NMR (CDCl3) ꢃC 141.1 (C9), 128.4 (C11),
122.9 (C12), 113.1 (C10), 118.0 ꢀC1;6;1 JCF ˆ 283†, 48.0
ꢀC2;2 JCF ˆ 30:5†, 118.4 ꢀC5;1 JCF ˆ 282;2 JCF ˆ 35:0†,
110.0 ꢀC4;1 JCF ˆ 264;2 JCF ˆ 35:0†. 25b ± 1H NMR
‡
478.0131; Mass spectrum, m/e 478 [M] , 393, 324, 259,
‡
168, 69 [CF3] . 1-(2,4-Dinitrophenyl)-5-¯uoro-3-penta-
¯uoroethyl-4-tri¯uoromethylpyrazole (20) ± a yellow solid
(5.22 g, 36% yield), m.p. 80±818C (hexane); 1H NMR
(CDCl3) ꢃH 9.05 (H11, 1H, s), 8.75 (H13, 1H, d, JHHˆ8.7),
8.03 (H14, 1H, d, JHHˆ8.7); 19F NMR (CDCl3) ꢃF 43.7 (F5,
q, JFFˆ14.6), 106.6 (F6, 3F, qt, JFFˆ16.6 and 9.8), 79.9 (F8,
3F, s), 51.4 (F7, 2F, q, JFFˆ9.8); 13C NMR (CDCl3) ꢃC 151.9
ꢀC5;1 JCF ˆ 299;3 JCF ˆ 5:4†, 148.9 (C9), 144.3 (C12),
140.7 ꢀC3;2 JCF ˆ 32:0†, 132.1 (C10), 132.2 (C13), 130.6
(CDCl3) ꢃH 4.07 (C±H, m), 8.57 (H±N, s), 7.24 (H10,12
)
and 7.36 (H11, m); 19F NMR (CDCl3) ꢃF 101.7 (F1,6, 6F, s),
82.5 (F5, 3F, s), 51.9 (F4, 2F, s); 13C NMR (CDCl3) ꢃC 141.4
(C9), 128.1 (C11), 122.7 (C12), 121.0 ꢀC1;6;1 JCF ˆ 321†,

36
K.-W. Chi et al. / Journal of Fluorine Chemistry 98 (1999) 29±36
113.1 (C10), 118.3 ꢀC5;1 JCF ˆ 285;2 JCF ˆ 34:5†, 48.6
ꢀC2;2 JCF ˆ 30:2†, 111.9 ꢀC4;1 JCF ˆ 264;2 JCF ˆ 37:1†,
134.6 ꢀC3;2 JCF ˆ 35:0†.
References
[1] R. Filler, Y. Kobayashi, L.M. Yagupolskii, Organofluorine Com-
pounds in Medicinal Chemistry and Biomedical Applications,
Elsevier, Amsterdam, 1993, p. 386.
3.2.10. Reaction of 25a and 25b with triethylamine
A mixture of Et3N (3.1 g, 0.030 mol) and the compounds
25a and 25b (3.88 g, 0.010 mol) in MeCN (20 ml) was
stirred at 208C for 3 h. The reaction mixture was diluted
with water (60 ml) and extracted with diethyl ether
(3Â50 ml). The combined extracts were dried (MgSO4)
and concentrated. The residual was distilled under reduced
pressure to give 9 as a yellow liquid (3.3 g, 95% yield), b.p.
60±628C at 1.5 Torr.
[2] S.K. Ritter, C. Washington, Chem. and Eng. News 73 (1995)
39.
[3] R. Gehring, O. Schallner, J. Steller, H.J. Santel, Ger. Offen DE
3603291 (1987), Chem. Abstr. 110 (1989) 135237.
[4] C.L. Bumgardner, J.C. Sloop, J. Fluorine Chem. 56 (1992) 141.
[5] M. Matsuo, K. Tsuji, N. Konishi, K. Nakamura, Eur. Pat. Appl. EP
418845 (1991), Chem. Anstr. 115 (1991) 71593z.
[6] G.G. Furin, Chemistry Rev. 20 (1996) 1.
[7] V.I. Saloutin, Z.E. Skryabina, Y.V. Burgart, J. Fluoirine Chem. 54
(1991) 297.
[8] V.I. Saloutin, Z.E. Skryabina, Y.V. Burgart, O.N. Chupakhin, M.
Font-Altabe, X. Solans, M. Font-Bardia, J. Fluorine Chem. 69 (1994)
25.
3.2.11. Reaction of 25a and 25b with K2CO3
A mixture of K2CO3 (5.5 g, 0.040 mol) and the com-
pounds 25a and 25b (5.87 g, 0.015 mol) in MeCN (80 ml)
was stirred at 208C for 3 h. The resulting solution was
diluted with water (100 ml) and extracted with diethyl ether
(3Â70 ml). The extracts were dried (MgSO4) and concen-
trated. The residual was distilled under reduced pressure to
give a yellow liquid (4.2 g), b.p. 60±658C at 1.5 Torr, which
consisted of 9 and 25b in a 9:1 ratio (by 19F NMR and GLC
analysis).
[9] I. Ikeda, M. Umio, M. Okahara, J. Org. Chem. 51 (1986) 569.
[10] I. Ikeda, Y. Kogame, M. Okahara, J. Org. Chem. 50 (1985) 3640.
[11] M.D. Bargamova, K. Karpavicins, A.M. Belostotskii, S. Mociskite,
I.L. Knunyants, USSR, SU 1456419 (1989), Chem. Abstr. 111
(1989) 97232y.
[12] M.D. Bargamova, S.M. Mociskite, I.L. Knunyants, USSR, SU
1456418, 1987.
[13] T. Ishihara, Jpn. Kokai Tokkyo Koho JP 01 22855 (1989), Chem.
Abstr. 111 (1989) 134144u.
[14] I. Ikeda, T. Tsukamoto, M. Okahara, Chem. Lett. 583 (1980).
[15] N. Ishikawa, T. Kitazume, K. Chino, El-S.M. Mustafa, J. Fluorine
Chem. 18 (1981) 447.
Acknowledgements
[16] X.F. Shi, T. Ishihara, H. Yamanaka, J.T. Gupton, Tetrahedron Lett. 36
(1995) 1527.
G.G. Furin is grateful to the Russian Fund Foundation
(project N 96-03-33047) and K.-W. Chi also thanks to
STEPI and Korea Research Foundation in Korea for their
®nancial supports for this work.
[17] L.J. Bellamy, The Infra-red Spectra of Complex Molecules, Wiley,
New York, 1954, pp. 54±65.