1,1-Bis(trifluoromethyl)butadiene-1,3-A new fluorinated building block

Article abstract of DOI:10.1016/j.jfluchem.2005.11.017

Although 1,1-bis(trifluoromethyl)butadiene-1,3 (1) reacts with dimethylamine with selective formation of 1,4-adduct [trans-(CF₃)₂CHCH{double bond, long}CHCH₂N(CH₃)₂], halogenation of 1 proceeds with predominant formation (>92%) of 1,2-adducts (CF₃)₂C{double bond, long}CHCHXCH₂X (X = Cl or Br). Electrophilic conjugated addition of "ClF" or "BrF" to 1 proceeds exclusively with the formation of 1,2-adducts (CF₃)₂C{double bond, long}CHCHFCH₂X (major) and (CF₃)₂C{double bond, long}CHCHXCH₂F (X = Cl or Br). Difluorocarbene adds selectively to {single bond}CH{double bond, long}CH₂ moiety of 1 forming thermally stable vinylcyclopropane. In Diels-Alder reaction with linear or cyclic dienes (butadienes, cyclopentadiene, cyclohexadiene-1,3) and quadricyclane compound 1 behaves as dienophile providing for the reaction electron-deficient {single bond}CH{double bond, long}CH₂ bond. The relative rate of cycloaddition of 1 and other fluoroolefins to quadricyclane, measured by high temperature NMR, indicates that (CF₃)₂C{double bond, long}CH{single bond} acts as very strong electron-withdrawing substituent. Synthetic utility of products based on 1 was also demonstrated.

Full text of DOI:10.1016/j.jfluchem.2005.11.017

Journal of Fluorine Chemistry 127 (2006) 529–538
www.elsevier.com/locate/fluor
1,1-Bis(trifluoromethyl)butadiene-1,3—A new
fluorinated building block
*
Viacheslav A. Petrov
DuPont Central Research and Development,1 Experimental Station, P.O. Box 80328, Wilmington, DE 19880-0328, USA
Received 27 November 2005; accepted 28 November 2005
Available online 19 January 2006
Abstract
Although 1,1-bis(trifluoromethyl)butadiene-1,3 (1) reacts with dimethylamine with selective formation of 1,4-adduct [trans-
(CF3)2CHCH CHCH2N(CH3)2], halogenation of 1 proceeds with predominant formation (>92%) of 1,2-adducts (CF3)2C CHCHXCH2X
(X = Cl or Br). Electrophilic conjugated addition of ‘‘ClF’’ or ‘‘BrF’’ to 1 proceeds exclusively with the formation of 1,2-adducts
(CF3)2C CHCHFCH2X (major) and (CF3)2C CHCHXCH2F (X = Cl or Br). Difluorocarbene adds selectively to –CH CH2 moiety of 1
forming thermally stable vinylcyclopropane. In Diels-Alder reaction with linear or cyclic dienes (butadienes, cyclopentadiene, cyclohexadiene-
1,3) and quadricyclane compound 1 behaves as dienophile providing for the reaction electron-deficient –CH CH2 bond. The relative rate of
cycloaddition of 1 and other fluoroolefins to quadricyclane, measured by high temperature NMR, indicates that (CF3)2C CH– acts as very strong
electron-withdrawing substituent. Synthetic utility of products based on 1 was also demonstrated.
# 2006 Elsevier B.V. All rights reserved.
Keywords: 1,1-Bis(trifluoromethyl)butadiene-1,3; Chlorination; Bromination; Electrophilic chlorofluorination; Bromofluorination; Reaction with difluorocarbene;
Cycloaddition to butadienes; Diels-Alder reactions
1. Introduction
adducts in ratio 56:41 along with smaller amount of other
byproducts [2]. Interestingly, the [4 + 2] process proceeds as a
Diels-Alder cycloaddition with the reverse electronic demand
resulting in formation of vinylcyclohexene, containing a
fluorinated double bond in the cycle [2].
At present the chemistry of polyfluorinated dienes is
represented mostly by transformations of hexafluorobuta-
diene-1,3 (HFB). The regiochemistry of the reactions of
HFB with nucleophilic, electrophilic and radical agents is well
studied and in most cases reactions proceed with the formation
of 1,4-adducts. For example, the bromination of HFB in the
dark (in sulfolane as solvent, 30 8C, 120 h) was reported to give
exclusively 1,4-adduct in 96% yield [1]. Similarly, the
conjugated addition of ‘‘ClF’’ or ‘‘BrF’’ [N-chlorosuccinimide
(NCS) or N-bromosuccinimide (NBS)/anhydrous HF system]
to 2-chloropentafluorobutadiene-1,3 (CPB) results in the
exclusive formation of the corresponding 1,4-adducts.
The reliable synthesis of 1,1-bis(trifluoromethyl)butadiene-
1,3 (1) was reported in 1970 [4]. It is based on the dehydration
of CH2 CHC(CF3)2OH by H2SO4. Despite the fact that 1 has
been known for over 30 years, its chemistry is limited to only a
few transformations, including radical [5,6] and anionic [7–9]
polymerization; hydrogenation and the reaction with butyl
lithium [4].
The presence of two electron-withdrawing trifluoromethyl
groups should significantly affect the reactivity of 1,1-
bis(trifluoromethyl)-butadiene-1,3 (1), thus creating a positive
charge on the CH2 end of the molecule. On the other hand, two
bulky groups (the CF3-substituent has been estimated to be
approximately the same size as a sec-butyl group [3])
connected to the terminal carbon should also significantly
distort the cisoid conformation of diene, due to the repulsion
between CF3- and H-substituents connected to C-1 and C-4, and
affect the ability of 1 to participate as diene in Diels-Alder
reactions.
Cycloaddition reactions of HFB are less definitive, since it
can participate in both [4 + 2] and [2 + 2] processes. For
example, the thermal reaction of HFB with butadiene (125 8C,
8 h) was reported to produce a mixture of 2 + 2 and 4 + 2
* Tel.: +1 302 695 1958; fax: +1 302 695 8281.
E-mail address: viacheslav.a.petrov@usa.dupont.com.
1
Publication No. 8686.
0022-1139/$ – see front matter # 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2005.11.017

530
V.A. Petrov / Journal of Fluorine Chemistry 127 (2006) 529–538
The present study is the first attempt of the systematic
investigation of the chemical behavior of 1 in nucleophilic,
radical, electrophilic and cycloaddition reactions.
amount of the tetrachloride 4c (see Table 2). Pure 4a (>99%)
was isolated in 68% yield by simple distillation, due to sub-
stantial difference in boiling points of 4a and 4c.
It should be pointed out that the radical halogenation of HFB
proceeds with preferential formation of 1,4-adducts (ratio 1,4-/
1,2-adducts: Cl2—58:42, Br2—78:28) [11]. The regiochemistry
of the radical halogenation of 1 correlates surprisingly well with
the regioselectivity of the radical polymerization, reported to
proceed mostly as 1,2-addition and involving nonfluorinated
double bond of 1 [4]. On the other hand, the radical poly-
merization of HFB proceeds mostly as a 1,4-addition [1].
2. Results and discussion
2.1. Reactions with nucleophiles
Similar to butyllithium [4], dimethylamine (DMA) attacks
1,1-bis(trifluoromethyl)butadiene-1,3 (1) regioselectively on
the CH2-group giving exclusively the 1,4-adduct 2.
2.2.2. Conjugate electrophilic halofluorination
The solution of N-halogen compounds in anhydrous HF is
known to be an effective reagent for electrophilic conjugate
halofluorination of polyfluorinated olefins and dienes [12–14].
For example, the halofluorination of 2-chloropentafluorobuta-
diene-1,3 (CPB) using the solution of N-chlorosuccinimides or
N-bromosuccinimides in HF, results in conjugated addition of
‘‘ClF’’ or ‘‘BrF’’, with exclusive formation of 1,4-adducts [15].
These results are also in a good agreement with the
regiochemistry of electrophilic halogenation of HFB, which
predominantly produces 1,4-adducts [11].
(1)
The reaction of 1 and DMA was very fast even at 0 8C (100%
conversion of 1 in 15 min), leading to selective, high yield
formation of the trans-isomer of 2. The regioselectivity of the
addition is similar to that observed in the reaction of hexa-
fluorobutadiene (HFB), which predominantly gives 1,4-adducts
in its reaction with HN(C2H5)3 and alcohols/N(C2H5)3 [10].
The electrophilic halofluorination of 1 was found to be
highly regioselective. The regioselectivity of this process,
however, was opposite to that observed in reactions of CPB and
HFB. The reaction of 1 with NCS in anhydrous HF led to the
selective formation of the 1,2-adduct—5a,b, along with a small
amount of the dichloride 4a
2.2. Halogenation reactions
2.2.1. Chlorination and bromination
Bromination of 1 rapidly proceeds without irradiation upon
the addition of bromine to 1, but in sharp contrast to the reaction
with nucleophiles, only a 1,2-adduct 3 forms in this reaction.
25 ꢂC;12 h
1 þ NCS ꢀ! ðCF3Þ2C¼CHCHFCH2Cl
HF
5a
exothermic
1 þ Br2 ꢀ! ðCF3Þ2C¼CHCHBrCH2Br
þ ðCF3Þ2C¼CHCHClCH2F þ4a;
(2)
5b
3;68%
ratio 5a : 5b : 4aꢀꢀ86:7 : 8:0 : 5:3; yield 5a; 5bꢀꢀ48% (4)
When the reaction was carried out under irradiation (sun
lamp), it resulted in the same product, isolated in 75% yield.
It should be pointed out that the isomeric 1,4-adduct –
(CF3)2CBrCH CHCH2Br – was not detected (NMR) in either
reaction.
Similarly, the interaction of 1 with NBS/HF mixture results in
exclusive formation of two isomeric 1,2-adducts 6a,b.
ꢂ
1 þ NBS25ꢀC!;12 h ðCF3Þ C¼CHCHFCH2Br
2
HF
6a
The reaction of 1 with Cl2 in a closed system (Hastelloy
reactor, acetonitrile as solvent, 16 h, 20 8C) resulted in the
recovery ꢁ60% of starting diene. Under UV irradiation,
however, the chlorination rapidly proceeds under mild
conditions with predominant formation of 1,2-aduct (4a),
along with a smaller amount of the 1,4-adduct (4b) (ratio
4a:4b—92:8 at 90% conversion of 1, after 15 min of irradiation
at 25–30 8C).
þ ðCF3Þ2C¼CHCHBrCH2F; ratio 6a : 6bꢀꢀ90 : 10;
6b
yield 6a; 6bꢀꢀ75%
(5)
It should be pointed out that in both reactions involving diene 1
the corresponding 1,4-adducts were not detectable in the crude
product (NMR). The formation of two isomers in both reactions
is the likely result of a ring opening reaction of the intermediate
halonium cation A by a counter anion (Scheme 1).
The difference in the regiochemistry of electrophilic
halofluorination of 1 versus HFB or CPB can be explained
in terms of the relative stability of the intermediates—allylic (B
and C) versus halonium (A and D) cations (Scheme 2).
The presence of two electron-withdrawing CF3-groups
connected to the carbon of allylic system bearing positive
charge leads to significant destabilization of cation B compared
to the halonium cation A (Scheme 1). The steric shielding of the
hn
1 þ Cl225ꢀꢀ!30 ꢂC ðCF3Þ2C¼CHCHClCH2Cl
4a
þ trans-ðCF3Þ2CClCH¼CHCH2Cl þ C6H4Cl4F6;
4c
4b
ratio 4a : 4b : 4cꢀꢀ82:5 : 1:5 : 16;
isolated yield of 4aꢀꢀ68%
Interestingly, the final product isolated after 2 h of irradiation
(3)
contained only a trace (1.5%) of 4b, along with a substantial

V.A. Petrov / Journal of Fluorine Chemistry 127 (2006) 529–538
531
Scheme 1.
carbon by bulky CF3-groups also may hinder the addition of the
counter anion on this end of cation A. On the other hand, in
electrophilic reactions of HFB and CPB intermediate C should
be more stable compared to halonium cation D, due to
pronounced ability of fluorine substituents adjacent to carbons
of allylic system bearing positive charge (C-1 and C-3) to
stabilize carbocationic center by back-donation of unshared
electron pare [13,16].
Scheme 2.
pentenes, since thermally less stable vinylcyclopropanes
undergo isomerization under the reaction conditions [19,20].
The unusually high thermal stability of 7 is the likely result
of unfavorable steric repulsions between the cyclopropane
ring and the CF3-group in intermediate radicals E or F, which
in turn inhibits the ring expansion process to form cyclo-
pentenes 7a,b under the reaction conditions (Scheme 3).
Significantly slower thermal isomerization of Z- versus E-1-
propenylpentafluoro-cyclopropanes (t1/2 = 3.6 h and 38 min at
110 8C, respectively) was explained as the result of repulsion
between syn-methyl group and cyclopropane ring in the
corresponding radical intermediate derived from the Z-isomer
[19].
2.3. Cycloaddition reactions
2.3.1. Reaction with difluorocarbene
The reaction of 1 and hexafluoropropene oxide (HFPO) as a
difluorocarbene source rapidly proceeds at 200 8C, thus leading
to the selective formation of vinylcyclopropane 7.
2.3.2. Diels-Alder reactions
Although 1,1-bis(trifluoromethyl)-3-methylbutadiene-1,3
has been reported to produce 1-methyl-3,3-bis(trifluoro-
methyl)cyclohexene-1 in reaction with ethylene at 275 8C
[22], the corresponding cycloadduct of diene 1 and ethylene
was not detected after heating the mixture for 16 h at 250 8C
(NMR).
(6)
Interestingly, in reaction with electron-rich dienes, com-
pound 1 behaves as an activated dienophile, providing electron-
deficient, unsubstituted double bond for the reaction. The Diels-
Alder reaction of 1 with butadiene-1,3 (8) or 2,3-dimethylbu-
tadiene (9) proceeds under relatively mild conditions (100–
120 8C, 16 h), resulting in the formation of the corresponding
[2 + 4] cycloadducts 10 or 11 (Scheme 4).
Compound 7, which was contaminated by a trace of a bypro-
duct (ꢁ2%, possibly, the product of double addition of CF2 to 1)
was isolated in 69% yield through distillation. Despite of high
reaction temperatures, products of ring expansion of 7 –
cyclopentenes 7a or 7b – were not detected (NMR) in the
crude reaction product.
It should pointed out that the introduction of fluorine into
cyclopropane rings effectively reduces thermal stability of vinyl
cyclopropanes [17–19]. This is the reason why the addition of
difluorocarbene at elevated temperature to CF2 CFCF CF2
[20], CF2 CFCCl CF2 and CF3CF CFCF CF2 [21] results in
high yield formation of the corresponding fluorinated cyclo-
Scheme 3.

532
V.A. Petrov / Journal of Fluorine Chemistry 127 (2006) 529–538
Scheme 5.
Table 1
Rate constants and relative reactivities for the cycloaddition of selected
fluoroolefins [23] and 1a to 18 at 109 8Cb
Scheme 4.
Fluoroolefin
Pseudo-first-order
rate constant (hꢀ1
Relative reactivity
)
Danishefsky’s diene (12), which is activated by two electron
CF3CF CF2
0.021 ꢄ 0.003
0.026 ꢄ 0.003
0.039 ꢄ 0.003
0.085 ꢄ 0.003
0.27 ꢄ 0.01
1
1.2
1.9
4.0
13
donating groups, reacts with 1 at ambient temperature,
selectively affording adduct 13a,b as a mixture of trans-/cis-
isomers, with significant predominance of one of them,
probably the trans-isomer.
cis-CF3CF CFCF3
trans-CF3CF CFCF3
(CF3)2C C(CF3)2
(CF3)2C CH2
Freshly prepared cyclopentadiene (14) also reacts with 1 at
ambient temperature to afford a mixture of two isomeric
norbornenes 15a,b (Scheme 5).
(CF3)2C CHCH CH2 (1)
(CF3)2C CFCF2CF3
0.60 ꢄ 0.01
29
2.94 ꢄ 0.01
138
a
This work.
0.15 mol Lꢀ1 in neat quadricyclane.
b
The interaction of 1 with cyclohexadiene-1,3 (16) at high
temperature leads to the mixture of two isomeric cycloadducts
17a,b. Quadricyclane (18) reacts with diene 1 at high
temperature forming a mixture of isomeric tricyclononenes
19a,b. Interestingly, the reaction of 18 with (CF3)2CFCH CH2
under similar conditions (110 8C, 20 h) is significantly slower,
thus resulting in the formation of only trace of the
corresponding cycloadduct. An amazingly high reactivity of
1 towards 18 was confirmed by measuring the relative rate of
this cycloaddition in a high temperature kinetic NMR
experiment [23]. It was found that the rate of addition of 1
to 18 was 29 and 2 times higher compared to that of
hexafluoropropene and CH2 C(CF3)2, respectively. Relative
rates of cycloaddition to 18 of selected olefins [23] and 1
(measured in this work2) are given in Table 1.
2.4. Synthetic utility of products based on 1
Compounds containing the –CH C(CF3)2 fragment are
relatively rare materials, due to the absence of general method
of preparation. Most synthesis are based either on dehydration
of (CF3)2C(OH)R [25], CF3C½ðC R02ÞOHꢃ¼CF2 [26], or on
Wittig reactions, of either (CF3)2C PR3 with hydrocarbon
carbonyl compounds [27–29] or nonfluorinated phosphorous
ylides with hexafluoroacetone [22,29,30].
The ability of diene 1 to participate in halogenation and
cycloaddition reactions with the conservation of a fluorinated
double bond makes it an interesting fluorinated building block
and offers an alternative methodology for the introduction of
the –CH C(CF3)2 fragment into organic molecules. Materials
synthesized using 1 are valuable intermediates for the
synthesis of other products. For example, dehydrohalogena-
tion of olefins 3 and 6a,b results in the formation of the
corresponding dienes 20 and 21.
Judging from the relative rates of cycloaddition to 18, the
(CF3)2C CH– substituent in diene 1 acts as an extremely
strong electron-withdrawing group, actually more powerful
than the (CF3)2CF—or even two CF3 substituents.
The fact that diene 1 participates in Diels-Alder reactions
as dienophile rather than as diene, is likely to be the result of
the destabilization of the cisoid conformation of 1 due to
repulsion between bulky CF3- and CH2-groups in s-cis-
conformation. This argument was previously used to explain
the formation of ene—rather than the expected Diels-Alder
adduct in the reaction of 2,5-dimethylhexadiene-1,3 with
benzyne [24].
(7)
Being reactive towards nucleophiles, diene 1 can be
oxidized by sodium hypochlorite. The reaction of diene 1
with NaOCl proceeds at elevated temperature resulting in
2
The measurement was carried out by A. Marchione.

V.A. Petrov / Journal of Fluorine Chemistry 127 (2006) 529–538
533
formation of bis-epoxide 22 along with small amount of mono-
epoxide 22a.
converted into the corresponding epoxides. For example, the
oxidation of olefins 7 and 19a,b carried out at ambient tem-
perature resulted in formation of epoxides 26 and 27a,b,
respectively.
(8)
(11)
In contrast to the epoxidation of CH2 C(CF3)2 [31], which
rapidly proceeds at 0–5 8C and pH 14, the oxidation of 1 seems
to be sensitive to both the temperature and the pH of the
reaction medium. At ambient temperature, oxidation was
slow, but compound 22 was prepared in moderate yield at
elevated temperature. The oxidation at pH 14 (freshly pre-
pared NaOCl) was found to be very slow at 25 8C. However,
when it was carried out at pH 11–12 (commercially available
NaOCl, Aldrich) and elevated temperature, the reaction
resulted in a moderate yield of 22 along with byproduct
22a. The formation of 22a seems to be the result of an
independent rather than a subsequent reaction. However,
mechanistic studies and yield optimization were not carried
out in this study. Pure 22 was isolated as a mixture of two
diastereomers after removal of byproduct 22a by fractionation
(see Section 3.6.1). Since unambiguous assignment of the
structure could not be made based on the data of NMR
spectroscopy, additional proof of the correctness of the struc-
ture was obtained through conversion of 22 into the known diol
23 [32] by reaction with LiAlH4
3. Experimental
1H, 13C and 19F NMR spectra were recorded on a Bruker
DRX 400 (400.5524, 100.8642 and 376.8485 MHz) using
internal CFCl3, TMS as standards and CDCl3 as a lock solvent.
IR spectra were recorded on a Perkin-Elmer 1600 FT
spectrometer as liquid films (KCl plates). Moisture sensitive
materials were handled in a glove box. GC and GC/MS analysis
were carried out on HP-6890 instrument, using HP FFAP
capillary column and either TCD (GC) or mass selective
detector (GS/MS), respectively.
Dimethylamine, NCS, NBS, dienes 8, 9, 12, 16 (Aldrich),
the solution of NaOCl (12% of active chlorine, Aldrich), HF,
HFPO, CH2 CHCH2C(CF3)2OH (DuPont) were used without
further purification. Quadricyclane (18) was prepared by
photochemical isomerization of norbornadiene [35] using t-
butyl methyl ether as a solvent. Compound 1 was prepared
according literature procedure [4]. All other chemicals and
solvents were obtained commercially and used as received.
Oxidation of olefins and dienes using NaOCl was carried out
using published procedure [31]. Compound 23 [32] was
identified by comparison with authentic sample (NMR,GC).
Caution: Anhydrous HF is toxic and corrosive material that
should be handled properly and by trained personnel only.
Despite the fact that sodium hypochlorite is a stable material at
pH 14, its stability is limited at lower pH. In reactions using
sodium hypochlorite the pH should be monitored during the
process to avoid rapid decomposition of NaOCl.
0ꢀ10 ꢂ
THF
C
22 þ LiAlH4 ꢀ! ðCF3Þ2CðOHÞCH2CHðOHÞCH3
(9)
23;75%
Bis-epoxide 22 is the second known example of polyfluorinated
oxides of conjugated dienes. The first representative of diep-
oxide of perfluoro-3,4-dimethylhexadiene-2,4 was reported in
1995 by Chambers et al. [33,34].
Interestingly, the oxidation of dienes containing a halogen
substituent in adjacent to C-3 results in selective oxidation of
the (CF3)2C CH– fragment.
3.1. Halogenation of 1
(a) Bromine (10 g, 0.056 mol) was slowly added with stirring
to 10 g (0.05 mol) of 1 at a rate that allowed to maintain the
internal reaction temperature <35 8C. The reaction mixture
was stirred for 1 h at ambient temperature, washed with the
solution of sodium thiosulfate; the organic layer was
separated, dried over MgSO4 and distilled. It was isolated
12.5 (68%) of 3, bp 82 8C/46 mmHg.
(10)
Using a recently developed procedure for the oxidation of
polyfluorinated 1,1-dihydro-olefins by NaOCl under phase-
transfer catalysis conditions [31], materials containing a moiety
that is reactive towards nucleophiles (CF3)2C CH– were
(b) The same reaction was carried on 0.3 mol scale out
under irradiation with a sun lamp at 25–35 8C. Compound 3

Table 2
Reaction conditions, yields, IR and MS data for new compounds
Reactants (mol)
Temperature (8C)
(time, h)
Product
bp (8C/mmHg)
Puritya
99.8
IR (cmꢀ1 b
)
MS (m/z)c
(yield, %)
DMA (0.15), 1 (0.1)
0 (0.5)
2 (95)
43/15
2950, 2780, 1462, 1358, 1271, 1142,
1094, 979, 956, 912, 860, 788,
730, 678
236[(M + 1), C8H12F6N+], 235
(M+, C8H11F6N+), 166 [(M-CF3)+,
C7H11F3N+]
1 (0.3), Br2 (0.32)d
1 (0.05), Cl2 (0.08)d
25–30 (2)
25–30 (2)
3 (75)
82/46
>99
1680, 1398, 1356, 1298, 1246, 1181,
1152, 1026, 948, 925, 664, 723
1685, 1396, 1355, 1302, 1242, 1172,
1099, 1046, 954, 925, 727, 706
–
269 (M-Br, C6H4BrF6+, 100%)
260 (M+, C6H4Cl2F6
260 (M+, C6H4Cl2F6
)
+
4a,b (68)
134–136
99.5
4be
5a,bf (48)
–
–
+
)
–
–
246, 244 (M+, C6H4ClF7
)
+
1 (0.05), NCS (0.06), HF (5)
25 (12)
106–108
95
1689, 1396, 1360, 1294, 1236, 1179,
1105, 1045, 946, 718, 665
6a,bg (49)
7 (69)
127–128
105–108
>99
1689, 1395, 1358, 1288, 1236, 1170,
1104, 1028, 1007, 941, 718, 696
1677, 1474, 1414, 1380, 1327, 1296,
1250, 1167, 1073, 1017, 969, 904,
849, 717
288, 290 (M+, C6H4BrF7
)
+
1 (0.18), NCS (0.2), HF (7.5)
1 (0.15), HFPO (0.21)
25 (12)
98h
240 (M+, C7H4F8
)
+
200 (12)
>99i
>99
>99
3033, 2922, 2845, 1676 (1645 sh),
1401, 1372, 1327, 1235, 1155, 11.02,
1094, 957, 745, 710
244 (M+, C10H10F6
272 (M+, C12H14F6
)
)
+
1 (0.1), 8 (0.2)
1 (0.1), 9 (0.22)
1 (0.03), 9 (0.03)
150 (20)
150 (20)
25 (2d)
10 (41)
57–58.5/26
84–85/18
65–67/02
+
11 (68)
2917, 1675 (1640 sh), 1401, 1328,
1289, 1235, 1165, 1094, 1052, 958,
715, 663
13a,bj (63)
2959, 1723 (sh), 1696 (sh),
1678, 1399,
273 [(M-C3H10OSi)+,
C11H11F6O+]
1338, 1150, 1094, 960, 925, 846
3050, 2946, 2871, 1669, 1398, 1360,
1286, 1243, 1154, 1111, 956, 933, 705
3050, 2946, 2871, 1669, 1398, 1360,
1286, 1243, 1154, 1111, 956, 933, 705
2971, 1667, 1403, 1297, 1243,
1215, 1157, 1111, 973, 948, 698
1670, 1619, 1392, 1256, 1254, 11159,
1000, 939, 915, 740
+
1 (0.1), 14 (0.1)
25 (5d)
190 (16)
190 (16)
25 (16)
25 (12)
15a,bk (69)l
17a,b (63)
19a,b (81)
20 (75)
60–68/27
80–82/0.26
98–102/23
102–104
76–82
95
>99m
>99n
99
256 (M+, C11H10F6
270 (M+, C12H12F6
282 (M+, C13H12F6
)
)
)
+
+
1 (0.13), 14 (0.18)
1 (0.13), 14 (0.18)
268, 270 (M+, C6H3BrF6
+
)
3 (0.05), N(C2H5)3 (0.1),
ether 100 mL
+
6a,b (0.09), N(C2H5)3 (0.1),
ether 100 mL
21o (49)p
75
1666, 1622, 1404, 1367, 1325,
1289, 1274,
208 (M+, C6H3F7
)
1227, 1165, 978, 923, 888, 731, 655
1492 (sh), 1467, 1357, 1305, 1202,
1118, 1007, 952, 835, 758, 716, 656
1661 (w), 1457 (?)
+
223 (M + 1, C6H5F6O2 )
1 (0.1), NaOCl (200 mL),
25–35 (12)
–
22q (41)
22ar
54–55/100
–
>99
–
(C4H9)4N+ HSO4 (0.2 g)
ꢀ
–
205 (M-1+, C6H3F6O+),
137 (M-CF3+, 100%)
284, 286 (M+, C6H3BrF6O+)
s
20 (0.02), NaOCl (80 mL),
25–35 (6)
0–25 (20)
24 (50)p
25 (68)p
–
>95
75
1643, 1440, 1359, 1200, 1102, 1105,
959, 936, 872
(C4H9)4N+ HSO4 (0.2 g)
ꢀ
s
21 (0.05), NaOCl (150 mL),
–
1687, 1451, 1359, 1317, 1112–1170,
1108, 1005, 969, 934, 882, 723, 651
224 (M+, C6H3F7O+)
(C4H9)4N+ HSO4 (0.2 g)
ꢀ

7 (0.03), NaOCl (100 mL),
20 (16)
20 (16)
0–10 (2)
26 (64)q
27a,b (72)
23 (75)
40–41.5/270
49/0.1
98
1491, 1453, 1368, 1330, 1300, 1204,
1120, 1089, 1025, 999, 964, 908,
879, 758, 730, 706, 661
–
240 [(M+-O), C7H4F8+)]
282 (M+-O, C13H12F6)
(C4H9)4N+ HSO4 (0.1 g)
ꢀ
19a,b (0.04), NaOCl (250 mL),
>99
ether 30, (C4H9)4N+ HSO4
(0.1 g)
ꢀ
t
22 (0.01) LiAlH4
a
GC or NMR.
b
KCl, liquid, major peaks.
c
GC/MS; electron ionization.
Under UV irradiation.
d
e
f
In mixture with 4a, ratio 4a:4b 92:8 at 90% conversion of 1.
Mixture of 5a,b and 4a, ratio 86.7:8.0:5.3.
Mixture of 6a and 6b, ratio 90:10.
Isolated material contained trace (ꢁ2%) of impurity, possibly the product of double addition of CF2.
Calc.: C, 49.19; H, 4.13; F, 46.68. C10H10F6. Found: C, 49.46; H, 4.18; F, 46.84.
Mixture of trans- and cis-isomers, ratio 86:14.
g
h
i
j
k
l
Purity 95%, the remainder is dimer of cyclopentadiene; mixture of two isomers, ratio 67:33.
Calculated yield on pure 15a,b.
m
n
o
p
q
r
Mixture of isomers, ratio 70:30; Calc.: C, 53.34; H, 4.48; F, 42.19. C12H12F6. Found: C, 53.33; H, 4.62; F, 42.02.
Mixture of isomers, ratio 57:43; Calc.: C, 55.32; H, 4.29; F, 40.39. C13H12F6. Found: C, 55.10; H, 4.51; F, 39.88.
Isolated product contained 25% ether.
Calculated yield.
Mixture of diastereomers, ꢁ1:1.
Isolated by distillation as the mixture with 22, ratio 22a:22—40:60.
Isolated by vacuum transfer into cold (ꢀ78 8C) trap.
1 M solution in THF.
s
t

Table 3
NMR spectra of new materials
Compound no.
1H NMRa (d, ppm; J, Hz)
19F NMRa (d, ppm; J, Hz)
ꢀ68.00 (d, J = 8.0)
13C NMRb,c (d, ppm; J, Hz)
2
2.4 (6H, s), 2.9 (2H, dd, J = 6.4, 1.5), 3.5
(1H, sept. J = 9.5), 5.5 (1H, ddt, J = 15.6, 9.5, 1.5),
6.0 (1H, dt, J = 15.1, 6.4)
44.9, 52.3 (sept., J = 30), 61.4, 117.2,
123.6 (q, J = 280), 141.7
3
3.63 (1H, t, J = 10.4), 3.88 (1H, dd, J = 10.4, 4.5),
5.15 (1H, td, J = 11.3, 4.5), 6.70 (1H, dm, J = 11.3, 1.2)
3.75 (1H, dd, J = 11.6, 8.2), 3.93 (1H, dd, J = 11.6, 4.2),
5.12 (1H, ddd, J = 10.7, 8.2, 4.6), 6.72
(1H, dm, J = 10.7, 1.2)
ꢀ58.92 (3F, q, J = 6.9), ꢀ65.27 (3F, q, J = 6.9)
ꢀ58.71 (3F, q, J = 6.7), ꢀ65.40 (3F, q, J = 6.7)
4a
4b
5a
5b
6a
6b
7
4.24 (2H, dd, J = 6.1, 1.8), 6.10 (1H, dm, J = 15.0),
6.63 (1H, dt, J = 15.0, 6.1)
ꢀ73.30 (s)
3.75 (2H, m, 5.12 (1H, ddd, J = 10.7, 8.2, 4.6)), 5.68
(1H, dm, J = 47.2), 6.83 (1H, dd, J = 14.6, 7.6)
3.70 (2H), 4.60 (1H, dm, J = 46.6), 4.96 (1H, m),
6.75 (1H, d, J = 10.0)
ꢀ59.10 (3F, quint., J = 7.3), ꢀ65.43 (3F, q, J = 7.3),
ꢀ179.88 (1F, dm, J = 47.2)
ꢀ58.60 (3F, q, J = 7.2), ꢀ65.30 (3F, q, J = 7.2),
ꢀ219.79 (1F, tdq, J = 46.6, 14.4, 1.8)
3.55 (1H, m), 3.63 (1H, m), 5.70 (1H, d, J = 47.9),
6.85 (1H, dd, J = 14.0, 7.6)
ꢀ59.12 (3F, quint., J = 6.0), ꢀ65.30 (3F, q, J = 6.9),
ꢀ175.55 (1F, dm, J = 47.9)
4.60 (1H, ddd, J = 47.3, 10.0, 7.3), 4.70 (1H, ddd,
J = 47.3, 10.0, 4.0), 5.1 (1H, m), 6.85 (1H)
1.7 (1H, m), 2.1 (1H, m), 2.8 (1H, m),
6.4 (1H, d, J = 9.9)
ꢀ58.88 (3F, q, J = 6.9), ꢀ65.28 (3F, q, J = 6.9),
ꢀ210.40 (1F, tdq, J = 47.3, 13.2, 1.5)
ꢀ59.28 (3F, q, J = 6.8), ꢀ64.93 (3F, q, J = 6.8),
ꢀ128.0 (1F, dtd, J = 159.9, 11.2, 4.4), ꢀ139.1
(1F, dddd, J = 159.9, 13.1, 5.9, 1.2)
19.0 (t, J = 11.0), 21.64 (tq, J = 13.1,
1.9), 112.3 (t, 285.0), 120.50 (qq, J =
270.3, 1.9), 120.90 (q, J = 273.2),
123.30 (sept., J = 32.9), 139.64 (m)
23.40, 27.64, 29.94, 33.75,
10
1.45 (1H, m), 1.70 (1H, m), 1.65 (1H, s),
1.85 (1H, m), 2.10 (2H, m), 2.93 (1H, m),
5.60 (1H, m), 5.68 (1H, m), 6.56
ꢀ58.50 (3F, q, J = 7.2), ꢀ64.75 (3F, q, J = 7.2)
121.47 (qq, J = 272.0, 2.9), 121.47
(sept., J = 31.0), 121.58 Z(q, J = 274.0),
124.15, 127.00, 151.10 (m)
(1H, dm, J = 11.2, 1.3)
11
1.47 (1H, m), 1.65 (1H, s), 1.7–2.2 (3H, m), 2.93
(1H, q, J = 11.3), 6.60 (1H, d, J = 11.3)
ꢀ58.40 (3F, q, J = 7.5), ꢀ64.73 (3F, qt, J = 7.5, 1.3)
20.77, 20.91, 30.48, 32.04, 36.60,
38.32, 123.22 (q, J = 272.0), 123.29
(sept, J = 32.0), 123.34 (q, J = 274.0),
124.92, 127.59, 153.22 (m)
13a,bd
0.26 (s), 1.7 (m), 2.0 (m), 2.98 (t, J = 10.5),
3.06 (m), 3.33 (m), 3.80 (t, t, J = 4.4), 5.01
(dt, 3.4, J = 1.3), 5.13
Major: ꢀ58.45 (3F, q, J = 7.3), ꢀ64.65 (3F, q, J = 7.3);
minor: ꢀ58.70 (3F, q, J = 7.3), ꢀ64.80 (3F, q, J = 7.3)
(dt, J = 4.8, 1.3),
6.70 (1H, d, J = 10.9), 7.05 (dm, J = 10.7, 1.3)
0.8–2.8 (7.4H), 3.6 (0.6H), 5.96 (2H, m), 6.93
(0.6H, d, J = 8.0), 6.98 (0.4H, d, J = 10.7)
1.0–2.0 (6H), 2.4–3.0 (3H), 5.6–6.9 (3H)
0.8–2.8 (7.4H), 3.6 (0.6H, t), 5.96 (2H, m), 6.93
(0.6H, d, J = 8.0), 6.98 (0.4H, d, J = 10.7)
5.94 (1H, dd, J = 2.8, 1.2), 6.02 (1H, t, J = 1.2),
7.07 (1H, m)
15a,be
Major: ꢀ58.80 (3F, dq, J = 6.9, 2.3), ꢀ64.35 (3F, qt,
J = 6.9, 1.7); minor: ꢀ58.75 (3F, m), ꢀ64.56 (3F, m)
ꢀ58.3 (m), ꢀ64.6 (m)
17a,be
19a,be
Major: ꢀ59.80 (3F, qd, J = 6.9, 2.3), ꢀ64.35 (3F, qt,
J = 6.9, 1.7); minor: ꢀ58.72 (3F, m), ꢀ64.53 (3F, m)
ꢀ58.41 (3F, q, J = 6.9), ꢀ65.27 (3F, qd, J = 6.9, 1.5)
20
21
116.91, 119.53 (q, J = 273.2), 119.90
(q, J = 273.2), 122.25 (sept., J = 31.0),
122.59, 139.67 (m)
5.10 (1H, dd, J = 42.7, 3.0), 5.25 (1H, dd,
J = 13.7, 3.0), 6.27 (1H, dq, J = 25.9, 1.5)
ꢀ58.35 (3F, dq, J = 31.6, 7.5), ꢀ65.10 (3F, q,
J = 7.5), ꢀ105.53 (1F, m)
107.20 (d, J = 20.3), 120.30 (q, J =
274.2), 121.02 (sept., m, J = 34.9, 3.9),
121.1 (q, J = 271.3), 132.40 (dm, J =
26.2), 157.05 (d, J = 258.7)

V.A. Petrov / Journal of Fluorine Chemistry 127 (2006) 529–538
537
was isolated in 75% yield. Reaction conditions, reagents
ratio and spectroscopic data of 3 are given in Tables 2
and 3.
(c) A solution of 10 g of 1 in 100 mL of acetonitrile was loaded
in a 240 mL Hastelloy reactor. It was cooled down,
evacuated and charged with 10 g of chlorine gas. The
reaction mixture was stirred for 16 h at ambient tempera-
ture, the reactor was unloaded and the mixture was worked
up as in example (a). Six grams of 1 were recovered.
(d) Chlorine gas (6 g, 0.08 mol) was slowly introduced and
irradiated with a sun lamp into a three-neck round bottom
flask equipped with a dry-ice condenser and containing
10 g (0.05 mol) of 1 at a rate that allowed to maintain the
internal temperature <35 8C. In the sample of crude
reaction mixture taken ꢁ15 min after beginning of chlorine
addition it was found by NMR that conversion of 1 was
90% and the reaction mixture contained a mixture of 4a and
4b in the ratio 92:8, along with a trace of 4c. The reaction
mixture was stirred under irradiation for 2 h and was
worked up as in example (a). Reaction conditions, ratio
reagents and spectroscopic data of 4a,b are given in
Tables 2 and 3.
3.2. Halofluorination reactions
A mixture of N-halosuccinimide, diene 1 and HF was
stirred in 400 mL Hastelloy reactor at ambient temperature.
Water (100 mL) was injected into the reactor and it was
unloaded. The organic layer was separated, washed with
water, dried over MgSO4 and distilled. Reaction conditions,
reagents ratio and spectroscopic data of the products are given
in Tables 2 and 3.
3.3. Reaction with HFPO
A mixture of 28 g (0.15 mol) of 1 and 35 g (0.21 mol) of
HFPO was stirred in a Hastelloy reactor for 12 h at 200 8C. The
reactor was unloaded and the product was distilled to give 25 g
(69%) of compound 7, bp 105–108 8C. The spectroscopic data
of 7 are given in Tables 2 and 3.
3.4. Cycloaddition reactions
3.4.1. Compounds 8, 9, 16 and 18
A mixture of 1 and the corresponding diene was stirred in a
Hastelloy reactor for 12–16 h at ambient temperature. The
reactor was unloaded and the product was distilled. Reaction
conditions, ratio of reagents and spectroscopic data of the
products are given in Tables 2 and 3.
3.4.2. Compounds 12 and 14
A mixture of 1 and the corresponding diene was stirred in
round bottom flask equipped with water condenser and
thermocouple for 2–5 days at ambient temperature. The reactor
was unloaded and the product was distilled. Reaction
conditions, ratio of reagents and spectroscopic data of products
are given in Tables 2 and 3.

538
V.A. Petrov / Journal of Fluorine Chemistry 127 (2006) 529–538
[5] V.A. Pattison, Hooker Chemicals and Plastics Corp., US Patent 3,949,112
3.5. Preparation of dienes 20 and 21
(1973).
[6] V.A. Pattison, Hooker Chemicals and Plastics Corp., US Patent 4,041,229
(1976).
To a solution of triethylamine in dry ether, compounds 3 or
6a,b were added and the reaction mixture was stirred at ambient
temperature for 12–16 h. It was washed with water; the organic
layer was dried over MgSO4 and distilled. Reaction conditions,
ratio of reagents and spectroscopic data of products are given in
Tables 2 and 3.
[7] M.H. Kaufman, J. Polym. Sci. Polym. Chem. Ed. 10 (1972) 455.
[8] M.H. Kaufman, United States Department of the Navy, US Patent
3,671,609 (1972).
[9] H.P. Smith, United States Department of the Army, US Patent 3,607,850
(1971).
[10] I.L. Knunyants, B.L. Dyatkin, L.S. German, Dokl. Akad. Nauk 124 (1959)
1065.
3.6. Oxidation using NaOCl
[11] D.F. Shellhamer, D.C. Gleason, G.G. Vaughan, A.J. Ryan, P.K. Titter-
ington, V.L. Heasley, J.J. Lehman, J. Fluorine Chem. 123 (2003) 171.
[12] L.S. Boguslavskaya, N.N. Chuvatkin, in: L. Geman, S. Zemskov (Eds.),
New Fluorinating Agents in Organic Synthesis, Springer-Verlag, New
York, 1989, p. 140.
3.6.1. Oxidation of 1 (typical procedure)
Diene 1 (19 g, 0.1 mol) was added at 0 8C to an stirred
mixture of 200 mL of sodium hypochlorite and 0.2 g of
[13] V.A. Petrov, V.V. Bardin, Top. Curr. Chem. 192 (1997) 39.
[14] V.A. Petrov, C.G. Krespan, E.I. Du Pont de Nemours & Co., USA, US
Patent 5,481,028 (1996).
(C4H9)4N+ HSO4 and the mixture was allowed to warm up
ꢀ
slowly; the temperature of the exothermic reaction was kept at
ꢁ35 8C with a cooling bath. The mixture was stirred overnight,
diluted with water (500 mL), the organic layer was separated,
dried over MgSO4, the crude material was vacuum-transferred
into a cold trap to separate the product from catalyst and
distilled at reduced pressure to give 5 g of mixture 22 and 22a
(bp 50–54/100 mmHg; ratio 60:40, respectively) and 9.1 g
(41%) pure 22, bp 54–55/100 mmHg, as a mixture of two
diastereomers. Spectroscopic data of the products are given in
Tables 2 and 3.
[15] S.D. Chepick, G.G. Belen’kii, V.A. Petrov, L.S. German, J. Fluorine
Chem. 65 (1993) 223.
[16] V.I. Bakhmutov, M.V. Galakhov, Usp. Khim. 57 (1988) 1467.
[17] F. Tian, M.D. Bartberger, W.R. Dolbier Jr., J. Org. Chem. 64 (1999) 540.
[18] W.R. Dolbier Jr., S.F. Sellers, J. Am. Chem. Soc. 104 (1982) 2494.
[19] B.E. Smart, P.J. Krusic, D.C. Roe, Z.-Y. Yang, J. Fluorine Chem. 117
(2002) 199.
[20] R.A. Mitsch, E.W. Neuvar, J. Phys. Chem. 70 (1966) 546.
[21] V.A. Petrov, S.D. Chepik, G.G. Belen’kii, L.S. German, Izv. Akad. Nauk
Ser. Khim. (1990) 1430.
[22] H. Abele, A. Haas, M. Lieb, J. Zwingenberger, Chem. Ber. 127 (1994)
145.
The oxidation of compounds 7, 19a,b, 20 and 21 was carried
out similarly, but at ambient temperature; ether was used as
solvent for the oxidation of 19a,b.
[23] V.A. Petrov, F. Davidson, P.J. Krusic, A.A. Marchione, W.J. Marshall, J.
Fluorine Chem. 126 (2005) 601.
[24] E.M. Arnett, J. Org. Chem. 25 (1960) 324.
[25] R.E.A. Dear, E.E. Gilbert, J.J. Murray, Tetrahedron 27 (1971) 3345.
[26] H. Lu, D.J. Burton, Tetrahedron Lett. 36 (1995) 3973.
[27] M. Hanack, C. Korhummel, Synthesis (1987) 944.
[28] D.J. Burton, Y. Inouye, Tetrahedron Lett. (1979) 3397.
[29] A. Haas, M. Lieb, J. Zwingenberger, Liebigs Ann. Chem. (1995)
2027.
Acknowledgements
Author thanks A. Marchione for measuring the rate of the
cycloaddition of 1 and 18 and R. Smith Jr. for technical
assistance.
[30] H. Abele, A. Haas, M. Lieb, Chem. Ber. 119 (1986) 3502.
[31] V.A. Petrov, W.J. Marshall, C.G. Krespan, V.F. Cherstkov, E.A. Avetisian,
J. Fluorine Chem. 125 (2004) 99.
References
[32] V.V. Grushin, W.J. Marshall, G.A. Halliday, F. Davidson, V.A. Petrov, J.
Fluorine Chem. 117 (2002) 121.
[1] R.D. Chambers, S. Nishimura, G. Sandford, J. Fluorine Chem. 96 (1999)
187.
[33] R.D. Chambers, J.F.S. Vaughan, S.J. Mullins, J. Chem. Soc. Chem.
Commun. (1995) 629.
[2] F.J. Weigert, J. Fluorine Chem. 52 (1991) 125.
[3] T. Hiyama, Organofluorine Compounds. Chemistry and Applications,
Springer, New York, 2000, p. 3.
[34] R.D. Chambers, J.F.S. Vaughan, S.J. Mullins, Res. Chem. Intermed. 22
(1996) 703.
[35] C.D. Smith, Org. Synth. 51 (1971) 133.
[4] V.A. Pattison, J. Org. Chem. 35 (1970) 2096.