Quadricyclane - Thermal cycloaddition to polyfluorinated carbonyl compounds: A simple synthesis of polyfuorinated 3-oxatricyclo[4.2.1.02,5]non-7-enes

Article abstract of DOI:10.1016/j.jfluchem.2004.06.011

Quadricyclane (1) readily undergoes [2+2+2] cycloaddition reactions with electron-deficient fluorinated carbonyl compounds to give polyfluorinated 3-oxatricyclo[4.2.1.0^2,5]non-7-enes in high yields. Hexfluoroacetone, trifluoroacetyl chloride, methyl trifluoropyruvate, α-(fluorosulfonyl)difluoroacetyl fluoride, and bis(trifluoromethyl)ketene all react rapidly with 1. Trifluoracetyl fluoride although less reactive, slowly interacts with 1 at ambient temperature. 1,1,1-Trifluoroacetone, trifluoroacetophenone, carbonyl fluoride, and CF₃C(O)OC₆F₅ require higher temperatures (60-90 °C) for reaction, and ethyl trifluoroacetate is unreactive at 90 °C. Heating 1 with the ethyl hemiacetal of trifluoroacetaldehyde gives the corresponding cycloadduct of CF₃C(O)H in 44% yield. The oxetane product from hexafluoroacetone is remarkably stable to both acids and bases, whereas the oxetanes with α-F or Cl leaving groups are sensitive to acid-catalyzed rearrangement.

Full text of DOI:10.1016/j.jfluchem.2004.06.011

Journal of Fluorine Chemistry 125 (2004) 1543–1552
www.elsevier.com/locate/fluor
Quadricyclane—thermal cycloaddition to polyfluorinated
carbonyl compounds
A simple synthesis of polyfluorinated
3-oxatricyclo[4.2.1.02,5]non-7-enes
*
Viacheslav A. Petrov , Frederic Davidson, Bruce E. Smart
DuPont Central Research and Development1, Experimental Station,
P.O. Box 80328, Wilmington, DE 19880-0328, USA
Received 5 April 2004; received in revised form 10 June 2004; accepted 15 June 2004
Available online 5 August 2004
Abstract
Quadricyclane (1) readily undergoes [2+2+2] cycloaddition reactions with electron-deficient fluorinated carbonyl compounds to give
polyfluorinated 3-oxatricyclo[4.2.1.02,5]non-7-enes in high yields. Hexfluoroacetone, trifluoroacetyl chloride, methyl trifluoropyruvate, a-
(fluorosulfonyl)difluoroacetyl fluoride, and bis(trifluoromethyl)ketene all react rapidly with 1. Trifluoracetyl fluoride although less reactive,
slowly interacts with 1 at ambient temperature. 1,1,1-Trifluoroacetone, trifluoroacetophenone, carbonyl fluoride, and CF3C(O)OC6F5 require
higher temperatures (60–90 8C) for reaction, and ethyl trifluoroacetate is unreactive at 90 8C. Heating 1 with the ethyl hemiacetal of
trifluoroacetaldehyde gives the corresponding cycloadduct of CF3C(O)H in 44% yield.
The oxetane product from hexafluoroacetone is remarkably stable to both acids and bases, whereas the oxetanes with a-F or Cl leaving
groups are sensitive to acid-catalyzed rearrangement.
# 2004 Elsevier B.V. All rights reserved.
Keywords: Quadricyclane; Thermal cycloaddition reactions; Hexafluoroacetone; Trifluoroacetyl fluoride; Carbonyl fluoride; Polyfluorinated carbonyl
compounds trifluoracetaldehyde hemiacetal
1. Introduction
ketones were also reported to give the corresponding
cycloadducts with 1 under high pressure [11,12]. In the
search of new monomers to prepare functional polymers for
next generation microlithography [13–15] we found that
perfluoroalkyl substituent has an unexpected and remarkable
activating effect on carbonyl group and polyfluorinated
carbonyl compounds are significantly more reactive towards
1 than any other reported carbonyl substrates.
Thermal [2+2+2] cycloaddition reactions of quadricy-
clane (1) and olefins provide a simple and useful method for
the synthesis of a variety of tricyclo[4.2.1.02,5]non-7-enes
[1–6]. However, the cycloaddition of 1 with carbonyl com-
pounds to form 3-oxa-tricyclo[4.2.1.02,5]non-7-enes is
usually carried out under UV-irradiation (e.g. [7]). Excep-
tional cases of thermal cycloadditions of 1 across C=O
bonds include the reactions with Moore’s ketene (t-butyl-
cyanoketene) [8] or diphenylketene [9], halogenated p-anils
[10] or highly electrophilic ketones, such as [CH3O(O)C]2-
C=O or C6H5C(O)C(O)C(O)OCH3 [11,12]. Some activated
2. Results and discussion
2.1. Reactions of 1 with carbonyl compounds
* Corresponding author. Tel.: +1-302-6951958; fax: +1-302-6958281.
In sharp contrast to acetone, which does not react with 1
under ambient conditions (25 8C, 48 h), hexafluoroacetone
E-mail address: viacheslav.a.petrov@usa.dupont.com (V.A. Petrov).
1
Publication No. 8449.
0022-1139/$ – see front matter # 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2004.06.011

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V.A. Petrov et al. / Journal of Fluorine Chemistry 125 (2004) 1543–1552
(2) reacts exothermally with 1 upon the addition of gaseous 2
into a solution of 1 in inert solvent (ether or dichloro-
methane) to give oxetane 3 in high yield (Eq. 1) [16]. In
fact, dilution of the reaction mixture and slow addition of 2
are required to control the heat evolved from this reaction.
Scheme 1.
Compared with reported reactions of 1 with acrylates,
which proceed only at elevated temperature and involve
exclusively the C=C bond of acrylate [17,18], bis(trifluoro-
methyl)ketene (4) reacts with 1 selectively producing oxe-
tane 5 (Eq. 2).
excellent example demonstrating the activation effect of a
CF3-substituent on the carbonyl group.
The formation of isomers in case of nonsymmetrical
carbonyl compounds is the result of syn- versus anti-orien-
tation of the two substituents relative to the methylene
bridge of the norbornene fragment. The oxetane ring in
each of the products is exclusively exo- within the limits of
detection (NMR, see also discussion below).
This reactivity of 4 is analogous to that reported for
bis(trifluoromethyl)thioketene which occurs regioselec-
tively across the thioketene C=S bond [19]. Notably, the
reactions of 1 with either 2 or 4 are both exceptionally clean
(NMR) and give only one product (3 or 5 respectively). Each
oxetane product is a single isomer and, it is assumed based
on literature data (e.g. [11]) that the oxetane rings in 3 and 5
have the exo-stereochemistry.
Althoughpolyfluorinated estersareless reactivetowards1,
a similar dependence of the reactivity of C=O and degree of
fluorination of the substrate is observed for esters of fluori-
nated acids. In contrast to the unreactivity of ethyltrifluor-
oacetate (14) at elevated temperature (90 8C, 36 h)
pentafluorophenyl trifluoroacetate (15) rapidly reacts with
1 under similar conditions to give in high yield cycloadducts
15a,b contaminated by small amount (5%) of isomeric
byproduct (Eq. 4). Combined NMR, IR and mass spectro-
scopy data are in a good agreement with the structure 15c
assigned to this product (see also reaction of 20 and 1 below).
Methyl trifluoropyruvate (6) is significantly more reac-
tive compared with CH3C(O)C(O)OC2H5 (reported to react
with 1 only at high pressure 800 MPa, 80 8C, 24 h [11]) and
reacts with quadricyclane (1) exothermally (Eq. 3).
Trifluoracetyl fluoride (16) is less active towards 1 than
hexafluoroacetone (Eq. 1). The reaction proceeds slowly at
ambient temperature to give cycloadduct 16a,b in moderate
yield (Eq. 5). More electrophilic a-(fluorosulfonyl)difluor-
oacetyl fluoride (17) reacts with 1 exothermally producing
adduct 17a,b in excellent yield.
Although two isomeric oxetanes 7a,b are formed in this
reaction, only the carbonyl group adjacent to CF3– is
involved but not the carbonyl of ester (NMR). The signifi-
cantly lower reactivity of the ester carbonyl is also consistent
with the observation that no detectable amount of cycload-
duct was observed in the reaction 1 and CF3C(O)OC2H5
after 36 h at 90 8C by NMR. The reactivity of the carbonyl
group varies significantly with the structure of fluorinated
carbonyl reactant. For example, the reaction of trifluorace-
tone (8) and 1 is slow at 90 8C, and gives a mixture of
oxetanes 9a,b in 22% yield (Scheme 1). However, the
replacement of the electron donating methyl group in 8
by –C6H5 (compound 10) or by –CH2Br (compound 12)
results in a shorter reaction time and higher yields of
cycloadducts, 11a,b and 13a,b respectively (Scheme 1).
The difference in the reactivity between 10 and hydro-
It should be pointed out that detailed NMR analysis of
materials isolated in reaction of 1 with 16 or 17 revealed the
presence in each cases of small amount (2–4%) of isomers of
16a,b or 17a,b respectively. Although the exact structure of
the byproducts was not established, the presence of a
norbornene fragment, –CFH-group (1H and 19F NMR)
and weak absorption in the carbonyl region (1778 and
1761 cmꢀ1 respectively) of both samples may be indicative
of the formation of small amounts of 2,2,2-trifluoro-1-(3-
carbon counterpart
– acetophenone – is amazing:
CH3C(O)C6H5 was reported to be completely inert towards
1 at elevated temperature and under high pressure – no
reaction after 24 h at 900 mp and 80 8C [11] and is an

V.A. Petrov et al. / Journal of Fluorine Chemistry 125 (2004) 1543–1552
1545
fluoro-bicyclo[2.2.1]hept-5-en-2-yl)-ethanone and 1,1-di-
fluoro-2-(3-fluorobicyclo[2.2.1]hept-5-en-2-yl)-2-oxoetha-
nesulfonyl fluoride respectively.
(ꢁ3%) of unknown material. The crude reaction mixture
was fractionated under vacuum and the fraction containing
78% of 22 was isolated. That allowed reliable characteriza-
tion of this material by NMR. The structure of exo-5-chloro-
exo-6-trifluoroacetylnorbonene-2 assigned to compound 22
In contrast to hexafluoroacetone, COF2 (18) is less
reactive, giving at ambient temperature only trace of
cycloadduct 19 (NMR). The yield of 19 although is sig-
nificantly higher when the reaction is carried out at elevated
temperature and autogenic pressure (Eq. 6).
1
is supported by the data of H, 19F, 13C NMR (see also
discussion below), IR spectroscopy and mass spectrometry.
Interestingly, the corresponding cycloadduct of
CF3C(O)H and quadricyclane was obtained in the direct
reaction of trifluoroacetaldehyde ethylhemiacetal (23) and 1
– refluxing the mixture of 23 and 1 led to the formation of
cycloadducts 23a,b.
The product isolated in this reaction contains a small
amount of isomer (ꢁ2%, endo-isomer (?); 19F NMR data see
Section 3), along with isomeric 28a,b (ꢁ1%, formed by
rearrangement of 19, see Eq. 13) and ꢁ1% of unidentified
compound (possibly, 3-fluoro-bicyclo[2.2.1]hept-5-ene-2-
carbonyl fluoride). Relatively pure 19 (98%) was isolated
by distillation under vacuum. 19 should be stored refriger-
ated, since its lifetime in glass vessel is limited to several
days at ambient temperature. The combination of relatively
low boiling point (see Table 1) and limited stability pre-
vented the obtaining of reliable elemental analysis for 19.
Moreover, the yield and the purity of 19 are greatly
affected by reaction temperature. The experiment carried
out at 100 8C in a Hastelloy reactor resulted in the formation
of significant amount (up to 50%) of byproducts.
The structure of 23a,b is in good agreement with 1H, 13C,
19F and mass spectrometry data, but unfortunately, we were
not able to obtain satisfactory elemental analysis.
With the exception of 19, all new norbornenoxetanes
are stable liquids at ambient temperature. The 19F NMR
spectrum of oxetane 19 exhibits two resonance of equal
intensity around ꢀ60 and ꢀ70 ppm (JAB = 112 Hz),
typical for polyfluorinated oxetanes [20,21]. 1H NMR
spectra of oxetanes 7a,b, 9a,b, 11a,b, 13a,b, 15a,b,
16a,b, 17a,b, 19, 21a,b, 23a,b along with required number
of resonances exhibit two signals of protons of the methy-
lene bridge (H-9 and H-90, see structure 9a) which are well
separated (D 0.2–0.9 ppm) and appear at 1.5–2.5 ppm as
Trifluoroacetyl chloride (20) reacts with 1 exothermally
giving a mixture of isomeric oxetanes 21a,b however, in
contrast to trifluoroacetyl fluoride (16) the major product in
this case is the compound 22 (Eq. 7).
AB type quartet with geminal coupling constant JAB
9–11 Hz.
=
It should be also pointed out that crude product along
with 21a,b, 22 was also contaminated by small amount
Table 1
Reactions of 1 with polyfluorinated carbonyl compounds
Entry number
Reagents (mol)
Method
Solvent (mL)
Temperature (8C), time (h)
Product(s), yield (%)
bp (8C)/mmHg
1
2
1(0.35); 2(.03)
B
B
B
C
C
B
C
B
B
A
B
B
CH2Cl2 (100)
Ether (100)
Ether (60)
10–25(2–4)
10–25(4)
10–30(4)
90(36)
3(95)
5(92)
67/21
98–99/19
119–121/19
72/14
1(0.33); 4(0.35)a
1(0.23); 6(0.17)
1(0.074); 8(0.07)
1(0.11); 10(0.1)
1(0.32); 12(0.31)a
1(0.03); 15(0.025)
1(0.31); 16(0.3)
1(0.3); 17(0.23)
1(0.35); 18(0.38)
1(0.23); 20(0.22)
1(0.11); 23(0.07)
3
7a,b(73b)
4
9a,b(22b)
5
100(18)
11a,b(57b)
13a,b(87b)
15a,b,c(76b)
16a,b(60b)
17a,b(92b)
19(48)
81–83/0.1
64–66/0.07
53–77/0.02
27–28/0.5
75–76/0.7
59–61/13
86–92/50
65–68/17
6
25–90(4 h)
105–100(9)
25(18)
7
8
9
15–30(6)
60(12)
10
11
12
a
Ether (100)
15–30(4)
85–90(18)
21a,b, 22(90b)
23a,b(44)
Delayed exothermic reaction; temperature risen from 25 to 90 8C over ꢁ1 h period.
b
Yield of the mixture of isomers.

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V.A. Petrov et al. / Journal of Fluorine Chemistry 125 (2004) 1543–1552
The resonance of the proton in the a-position to oxygen
reported that the carbonyl bond needs ‘‘drastic activation’’
by electron-withdrawing groups, and at least in the cases of
[CH3O(O)C]2C=O or C6H5C(O)C(O)C(O)OCH3, the reac-
tions are not concerted but most likely to involve radical–ion
pair intermediates. The observed qualitative order of reac-
tivity of our fluorinated carbonyl compounds toward quad-
ricyclane indeed increases with the electron deficiency of the
(H-2) appears at 4.3–4.9 ppm as a doublet (Jd = 4.0–
5.5 Hz) coupled to the proton in the b-position to oxygen
(H-5, at 2.4–2.6 ppm). All values are in good agreement
with reported values of chemical shifts and coupling
constants for nonfluorinated norbornenoxetanes [7,8,11].
It should be also pointed out that values of coupling
constants between vicinal protons H-2 and H-3 of norbor-
nenes 15c, 22, and 26 (see structure 9b) are slightly higher
(J = 7.2, 7.8 and 6.8 Hz, respectively), indicating cis-
relationship of two protons, since trans-coupling constant
is usually smaller (for example, values of coupling con-
stant H-2/H-3 reported for large number of exo, endo-
aryltiohalo-bicyclo[2.2.1]heptene-5-enes are in the range
between 2.1 and 3.5 Hz [22]).
carbonyl group: CF3C(O)CF3
CF3C(O)C6H5 CF3C(O)CH3 >> CF3C(O)OC2H5;
CF3C(O)OC6F5 >> CF3C(O)OC2H5; CF3C(O)CF3
>
CF3C(O)CH2Br
ꢂ
>
>
CF3C(O)F > FC(O)F. The fact that CF3C(O)Cl is more
reactive than CF3C(O)F and CF3C(O)CF3 > CF3C(O)F also
is consistent with their relative electron-acceptor capacities
[23]. Unfortunately, there are no experimental electron
affinity data for these compounds, except for a lower limit
value of 10.2 kcal/molꢀ1 for hexafluoroacetone [24]). The
relatively fast, room temperature reactions all develop a
transient yellow color upon mixing the quadricyclane and
fluorinated carbonyl compound, which suggests formation
of charge-transfer complexes [25] or radical–ion pairs [12],
but much more than this circumstantial evidence needs to be
adduced before a mechanism of cycloaddition can be estab-
lished. The formation of by products 15c and 22 in the
reactions of 1 with CF3C(O)OC6F5 and CF3C(O)Cl could be
a result of competitive polar addition of the reagent
CF3C(O)X to 1 through C–X bond (X = Cl or OC6F5).
The presence of two isomers in compounds 7a,b, 9a,b,
11a,b, 13a,b, 15a,b, 16a,b, 17a,b, 21a,b, 23a,b is the result
of different orientation of substituents at C-4 (structure 9a)
relative to the norbornene methylene bridge. It is reasonable
to postulate on steric grounds that the major isomer in all
these cases have the bulkiest substituent anti- to the nor-
bornene methylene bridge. The aproof of this statement was
obtained in 2D H-F HOESY (heteronuclear proton–fluorine
2D NOE) experiment carried out in case of compound
16a,b. In major isomer 16a an NOEs for F-4/H-90 and
CF3-4/H-5 were observed indicating syn-orientation of F-
4 in major isomer.
For minor isomer 16b the confirmation of anti-orienta-
tion of F-4 and H-90 was obtained, due to observed large
NOEs between H-90/CF3-4, F-4/H-5 and H-4/H-2 (see Sup-
plementary data for details). Therefore, the observed sub-
stantial four-bond coupling constant H-2/F-4 in 16a (J =
12.5 Hz; similarly JH2-F4 = 13.0 Hz in 17a) is the coupling
constant between anti-H-2 and syn-F-4 located on different
sides of oxetane ring.
2.2. Selected reaction of norbornenoxetanes
The oxetane fragment in compound 3 is surprisingly
stable. For example, Pd catalyzed addition of hydrogen
proceeds selectively across the C=C bond of norbornene,
but the strained oxetane fragment remains intact in this
reaction (Eq. 9).
Compound 3 does not react at ambient temperature with
potassium t-butoxide (DMF, 16 h), NaBH4, or NaB(Et)3H
(THF, reflux, 5 h). However, the reaction of 3 and C4H9Li
slowly proceeds at ambient temperature to give, after hydro-
lysis, a mixture of 25a and 25b (Eq. 11).
The ratio of isomers correlates well with the size of
substituents and ranges widely from 58:42 for 13a,b (con-
taining CF3- and CH2Br groups at C-4), for substituents of
similar size, to 88:12 for compounds 23a,b bearing CF3– and
H– at C-4. The IR spectra of all oxetanes exhibit a band at
1430–1460 cmꢀ1 of low or medium intensity, typical for
polyfluorinated oxetanes [20]. Mass spectra of oxetanes
9a,b, 19, 21a,b, 23a,b contain a parent ion of low intensity
along with high intensity masses 91 and 66, indicative of
retro Diels–Alder type fragmentation as the major decom-
position path.
Based on NMR data, compounds 25a and 25b form in
this reaction as a single isomer (possibly, having exo-, exo-
orientation of both substituents), but NMR data were not
sufficient to determine the exact position of butyl substituent
in compound 25a relative to the oxygen of oxetane ring.
The [2s+2s+2p] cycloadditions of quadricyclane with
C=C double bonds are typically one-step concerted, regio-
and stereospecific (exo) processes. For reactivity with C=O
bonds, however, Jenner and co-workers [11,12] have

V.A. Petrov et al. / Journal of Fluorine Chemistry 125 (2004) 1543–1552
1547
Compared with 3, the oxetane 13a,b is much more active
toward C4H9Li. The reaction between 13a,b and two equiva-
lents of C4H9Li rapidly proceeds at ꢀ60 to ꢀ40 8C to give
compound 26, in 65% isolated yield.
NMR and GC/MS analysis of the crude reaction mixture
revealed the presence of a small amount (ꢁ5%) of isomeric
byproducts (possibly, 3-fluoro-bicyclo[2.2.1]hept-5-ene-2-
exo-carbonyl fluoride). Compound 16a,b behaves similarly.
Although the reaction with 27 is not as exothermic it leads to
a mixture of nortricyclanes 29a,b (Eq. 13) contaminated by
small amount (ꢁ2%, NMR, GC/MS) of isomeric byproducts
[likely to be 2,2,2-trifluoro-1-(3-fluoro-bicyclo[2.2.1]hept-5-
en-2-yl)-ethanone].
The 19F NMR spectrum of 26 exhibits two doublets at
ꢀ89.80 and ꢀ91.41 ppm with a coupling constant of 58 Hz.
Chemical shifts and coupling constants of 26 are comparable
to the corresponding values for fluorine substituents in the
=CF2 group of hexafluoropropene (d = ꢀ82.8, ꢀ95.0, J =
1
3. Experimental
58.3 Hz) [26]. The H NMR spectrum of 26 although quite
complex exhibits resonance of two nonequivalent protons of
the methylene bridge at 1.63 and 1.84 ppm (AB quartet J =
9.0 Hz) and a proton adjacent to carbon bearing an –OH (H-2,
structure 9b), d 3.88 ppm, coupled to H-3(d 2.34, Jd = 6.8 Hz).
The value of the coupling constant suggests an endo–endo
orientation of these two protons and therefore exo–exo rela-
tionship of two substituents. The 13C {H} NMR spectrum
containstherequirednumberofsignals(14, seeSection3) and
four resonances of sp2 carbons: two singlets at 133.19,
140.90 ppm (C=C of norbornene) and two multiplets at
88.26 (dd, J = 17.4, 11.6 Hz) and 153.42 (dd, J = 282.0,
285.0 Hz) ppm, assigned to the exocyclic double bond. IR
spectrum exhibits an intensive band at 1735 cmꢀ1 typical for
fluorinated terminal double bond [27] and broad absorption of
–OH centered at 3436 cmꢀ1. All these data are in good agree-
ment with the structure 26. The formation of compound 26 as
a single isomerwith exo-orientation of both substituents is in a
good agreement with suggested exo-stereochemistry of 13a,b.
There is a clear correlation between the stability and the
structureofnorbornenoxetanes. Amongoxetanes3, 16a,band
19, compound 3 is the most stable – it can be stored for a long
time without any decomposition at ambient temperature;
distilled 16a,b stored in a glass bottle for several months at
ambient temperature turned dark brown, but the NMR spectra
remained unchanged. By contrast, compound 19 completely
decomposed over a oneweek period when kept in glass vessel
at ambient temperature. The stability also correlates with the
reactivity of all three toward acids. In sharp contrast to
compound 3, which is stable to the action of Lewis acids
[boron trifluoride etherate (27) or TaF5, 25 8C, 16 h) oxetanes
16a,b and 19 are quite sensitive. For example, the addition of
19 to the solution of 27 in CH2Cl2 results in an exothermic
rearrangement with the formation of a mixture of two iso-
meric nortricyclanes 28a,b (Eq. 13).
1H and 19F NMR spectra were recorded on Brucker DRX-
400 (400.5524 and 376.8485 MHz respectively) instruments
using CFCl3 as an internal standard and CDCl3 as a lock
solvent. 1H NMR spectra of compounds 3, 5, 16a,b, 17a,b,
19, 22, 23a,b and 26 were recorded on Brucker DRX-500
(499.87 MHz), values of major proton coupling constants
for compounds 3, 5, 16a,b, 17a,b, 19 were confirmed in
1
homonuclear H COSY experiments; for compounds 23a,b
and 26 – in 1H selective homodecoupling experiments.
Values of major (>5 Hz) proton–fluorine coupling constants
in compounds 16a,b and 17a,b were confirmed in 19F {H}
experiments. The 2D 19F-1H HOESY spectra (19F observed)
for mixture of compounds 16a,b was performed on a
400 MHz Varian Inova spectrometer where 19F appears at
376.284 MHz; more details and spectrum can be found in
Supplementary material (see Appendix A).
Separation isomers of compounds 7a,b, 9a,b, 11a,b,
13a,b, 15a,b, 16a,b, 17a,b, 21a,b, 23a,b was not attempted
in this study and they were characterized in mixtures by
NMR, which in some cases due to overlap of signals could
effect the accuracy of signal assignments and determination
of values of coupling constants. 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.
Compounds 2, 12, 15, 16 (Synquest), 17 (DuPont), 8, 10,
14, 18, 20, butyl lithium (2M solution in pentane) (Aldrich)
were purchased and used without further purification. Quad-
ricyclane (1) was prepared by photochemical isomerization
of norbornadiene [28] using t-butyl methyl ether as a
solvent. For all reactions quadricyclane of 90–95% purity
[remainder – norbornadiene (5–8%) and solvent (2–3%)]
was used. Molar ratio of reagent are calculated based on
100% 1 (Table 1). Compounds 4 [29] and 6 [30] was
prepared according literature procedures. All other chemi-
cals and solvents were obtained commercially and used as
received.

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V.A. Petrov et al. / Journal of Fluorine Chemistry 125 (2004) 1543–1552
Caution! Both hexafluoroacetone and carbonyl fluoride
3.1.5. 4-(2,2,2-Trifluoro-1-trifluoromethyl-ethylidene-3-
oxa-tricyclo[4.2.1.02,5]non-7-ene (5)
are toxic materials that should be handled properly and by
trained personnel only. We did not experience any problems
during this study, but some reactions of 1 with polyfluori-
nated carbonyl compounds are highly exothermic and
should be carried out under conditions allowing control
of the heat evolving during reaction.
Exo-isomer; 1H NMR (CDCl3): d 1.78(1H, d, J = 9.4 Hz),
1.92(1H, d, J = 9.4 Hz), 3.08(1H, s), 3.29(1H, s), 3.43(1H, d,
J = 4.5 Hz), 4.92(1H, d, J = 4.5 Hz), 6.02(1H, dd, J = 3.0,
5.7 Hz), 6.38(1H, dd, J = 3.0, 5.7). 13C(neat, {1H}): d 40.26,
41.59(s), 44.87, 47.56, 87.36, 92.63 (sept. J = 34.0 Hz),
122.62(q, J = 272.0 Hz), 123.3(q, J = 270.0 Hz), 131.72,
139.71, 175.86 (m). 19F NMR (CDCl3): d ꢀ58.07(3F, m),
ꢀ58.15(3F, m). IR: 1687(s), 1456 (w) cmꢀ1. Anal. calc. for
C11H8F6O: C, 48.9, H, 3.0, F, 42.2. Found: C, 48.6, H, 2.9, F,
42.6.
3.1. Reactions of 1 with polyfluorinated carbonyl
compounds
3.1.1. Method A
In a 400 mL Hastelloy shaker tube, the solution 35 g
(0.36 mol) of 1 in 100 mL of dry ether was added. The
reactor was cooled down, evacuated, charged with carbonyl
fluoride (25 g, 0.38 mol) was kept under autogenic pressure
at 60 8C for 12 h. The reaction vessel was unloaded. The
solvent was removed under vacuum and the liquid residue
was distilled under reduced pressure. The reaction condi-
tions and ratio of reactants are given in Table 1.
3.1.6. 4-Trifluoromethyl-3-oxa-tricyclo[4.2.1.02,5]non-7-
ene-4-carboxylic acid methyl ester (7a,b)
1
Mixture of two isomers, ratio 70:30. Major isomer: H
NMR (CDCl3): d 1.50(1H, d, J = 10.9 Hz), 1.83(1H, d, J =
10.9 Hz), 2.71(1H, m), 3.08(1H, s), 3.12(1H, s), 3.86(3H, s),
4.55(1H, m, Jd ꢁ5 Hz), 5.92(1H, dd, J = 3.4, 5.7 Hz),
6.22(1H, dd, J = 3.4, 5.7 Hz); 19F NMR (CDCl3): d
1
ꢀ80.00 (s); minor isomer: H NMR (CDCl3): d 1.50(1H,
3.1.2. Method B
d, J = 11.0 Hz), 2.43(1H, d, J = 11.0 Hz), 2.55(1H, d, J
ꢁ5 Hz), 3.17(1H, s), 3.22(1H, s), 3.87(3H, s), 4.63(1H, d, J
ꢁ5 Hz), 5.92(1H, dd, J = 3.4, 5.7 Hz), 6.30(1H, dd, J = 3.4,
5.7 Hz); 19F NMR (CDCl3): d ꢀ69.21 (s). IR (mixture of
isomers): 1754(s), 1436 (d, m) cmꢀ1. Anal. (mixture of
isomers) calc. for C11H11F3O3: C, 53.2, H, 4.5, F, 23.0.
Found: C, 53.0, H, 4.6, F, 23.0.
The carbonyl compound (0.1–0.3 mol) was slowly added
(either as a gas or liquid) to a well agitated solution of 1 (0.1–
0.3 mol) in CH2Cl2 or ether solvent, placed in a three-neck
round bottom flask equipped with dry-ice condenser, ther-
mometer and either inlet tube or additional funnel. The
addition was started at 10 8C and carried out with the rate
that allowed the internal temperature to be kept at 20–30 8C.
After the addition of carbonyl compound, the reaction
mixture was agitated at ambient temperature. the solvent
was removed under vacuum and the residue was distilled
under reduced pressure. The reaction conditions and ratio of
reactants are given in Table 1.
3.1.7. 4-Methyl-4-trifluoromethyl-3-oxa-
tricyclo[4.2.1.02,5]non-7-ene (9a,b)
Mixture of two isomers, ratio 63:37. Major isomer: H
1
NMR (CDCl3): d 1.39(3H, q, J = 1.1 Hz), 1.59(1H, d, J =
9.2 Hz), 2.25(1H, d, J = 9.4 Hz), 2.43(1H, d, J = 5.0 Hz),
2.91(1H, m), 3.10(1H,m) 4.59(1H, d pent., J = 5.0, 1.0 Hz),
5.90(1H, dd, J = 3.4, 5.7 Hz), 6.23(1H, dd, 3.0, 5.7 Hz); 19
F
3.1.3. Method C
A glass sample vial (20 mL) was charged with the
mixture of 1 (0.05–0.1 mol; 10–20% excess) and the corre-
sponding substrate (0.03–0.08 mol), sealed and kept at 80–
110 8C for the period of time indicated in Table 1. The
product was isolated by vacuum distillation of the crude
reaction mixture. The reaction conditions and ratio of reac-
tants are given in Table 1.
NMR (CDCl3): d ꢀ82.06(s). Minor isomer: 1H NMR
(CDCl3): d 1.50(1H, d, J = 9.4 Hz), 1.65(3H, q, J =
1.1 Hz), 2.18(1H, d, J = 5.0 Hz), 2.52(1H, d, J = 9.4 Hz),
3.00(2H, s), 4.53(1H, d, J = 5.0 Hz), 5.85(1H, dd, J = 3.4,
5.7 Hz), 6.27(1H,dd, J = 3.4, 5.7 Hz); 19F NMR (CDCl3): d
ꢀ72.33 (s). IR (mixture of isomers): 1457 (m) cmꢀ1. GC/
MS (m/e, major): 204(M+, C10H11F3O+), 91(C7H7 ), 66
+
+
(C5H5 ).
3.1.4. 4,4-Bis(trifluoromethyl)-3-oxa-
tricyclo[4.2.1.02,5]non-7-ene (3)
3.1.8. 4-Phenyl-4-trifluoromethyl-3-oxa-
tricyclo[4.2.1.02.5]non-7-ene (11a,b)
Mixture of two isomers, ratio 74:26. Major isomer: H
Exo-isomer; 1H NMR (CDCl3): d 1.53(1H, d, J = 9.6 Hz),
2.42(1H, d, J = 9.6 Hz), 2.60(1H, d pent., J = 4.9, 0.9 Hz),
3.21(1H, m), 3.24(1H, m), 4.75(1H, d, J = 4.9 Hz), 5.92(1H,
dd, J = 5.7, 3.4 Hz), 6.31(1H, dd, J = 5.7, 3.0 Hz); 13C(neat,
{H}): d 41.30(q, J = 4.0 Hz), 41.90, 42.20, 45.20, 80.50
(sept. J = 31.0 Hz), 83.84, 122.00(q, J = 286 Hz), 122.70(q, J
= 285 Hz), 132.30, 140.60. 19F NMR (CDCl3): d ꢀ69.12(3F,
q, J = 10.3 Hz), ꢀ78.63(3F, q, J = 10.3 Hz). IR: 1462 (w)
cmꢀ1. Anal. calc. for C10H8F6O: C, 46.5, H, 3.1, F, 44.2.
Found: C, 46.3, H, 3.0, F, 44.3.
1
NMR (CDCl3): d 1.19(1H, d, J = 9.4 Hz), 1.61(1H, d; J =
9.4 Hz), 2.80(1H, m), 2.85(1H, d, J = 4.9 Hz), 3.07(1H, m),
4.76(1H, d, J = 4.9 Hz), 5.93(1H, dd, J = 3.4, 5.7 Hz),
6.23(1H, dd, J = 3.4, 5.7 Hz), 7.37(5H, m); 19F NMR
(CDCl3): d ꢀ84.57(s). Minor isomer: 1.59(1H, d, J =
9.8 Hz), 2.51(1H, d; J = 4.9 Hz), 2.75(1H, d, J = 9.8 Hz),
3.19(1H, m), 3.33(1H, m), 4.72(1H, d, J = 4.9 Hz), 5.85(1H,
dd, J = 3.0, 5.7 Hz), 6.32(1H, dd, J = 3.0, 5.7 Hz), 7.37(3H,

V.A. Petrov et al. / Journal of Fluorine Chemistry 125 (2004) 1543–1552
1549
m), 7.62(2H, d, J = 7.6 Hz); 19F NMR (CDCl3): d ꢀ75.62 (s).
IR: 1498(w), 1450(m) cmꢀ1. Anal. (mixture of isomers)
calc. for C15H13F3O: C, 67.7; H, 4.9; F, 21.4. Found: C, 67.6;
H, 4.8; F, 21.3.
= 9.4, 1.8 Hz), 2.34(1H, d, J = 9.4 Hz), 2.92(1H, m),
3.21(1H, m), 3.25(1H, dd, J = 7.6, 2.3 Hz), 4.85(1H, dm,
J = 7.6, 0.8 Hz), 6.08(1H, dd, J = 3.0, 5.7 Hz), 6.30(1H, dd, J
= 3.0, 5.7 Hz); 19F NMR (CDCl3): d ꢀ79.51(3F, t, J =
4.5 Hz), ꢀ154.93(2F, dm, J = 22.6 Hz), ꢀ161.68(1F, tt, J
= 22.0, 1.9 Hz), ꢀ162.92(2F, m); IR (mixture of isomers):
1761 (w), 1518(s), 1468(s) cmꢀ1. Anal. (mixture of isomers)
calc. for C15H8F8O2: C, 48.4; H, 2.2; F, 40.8. Found: C, 48.7;
H, 2.0; F, 41.0.
3.1.9. 4-Bromomethyl-4-trifluoromethyl-3-oxa-
tricyclo[4.2.1.02,5]non-7-ene (13a,b)
Mixture of two isomers, ratio 58:42. Major isomer: H
1
NMR (CDCl3): d 1.66(1H, d, J = 9.4 Hz), 2.13(1H, d, J =
9.4 Hz), 2.51(1H, d m, J = 4.9, 1.9 Hz), 3.18(2H, m),
3.62(2H, s), 4.62(1H, d, J = 4.9 Hz), 5.93(1H, dd, J =
3.4, 5.7 Hz), 6.28(1H, dd, J = 3.0, 5.7 Hz). 19F NMR
(CDCl3): d ꢀ80.28 (s). Minor isomer: 1.54(1H, d, J =
9.8 Hz), 2.49(1H, d, J = 9.8 Hz), 2.51(1H, d, J = 4.9),
3.13(1H, m), 3.18(1H, m), 3.67(1H, dq, J = 11.3, 1.5 Hz),
3.80(1H, d, J = 11.3 Hz), 4.59(1H, dd, J = 4.9, 1.5 Hz),
5.90(1H, dd, J = 3.4, 5.7 Hz), 6.32(1H, dd, J = 3.0, 5.7 Hz).
19F NMR (CDCl3): d ꢀ69.17 (s). IR (mixture of isomers):
1430 (w), 1462(w) cmꢀ1. Anal. (mixture of isomers) calc.
for C10H10BrF3O: C, 42.4; H, 3.6; F, 20.1. Found: C, 41.9; H,
3.4; F, 20.0.
3.1.11. 4-Fluoro-4-trifluoromethyl-3-oxa-
tricyclo[4.2.1.02,5]non-7-ene (16a,b)
Mixture of isomers 16a,b, contaminated by small amount
of unidentified isomeric material (NMR, GC/MS, possibly
2,2,2-trifluoro-1-(3-fluoro-bicyclo[2.2.1]hept-5-en-2-yl)-
ethanone), ratio 74:24:2 respectively. 16a,b: major isomer:
1H NMR (CDCl3): d 1.61(1H, d, J = 10 Hz), 2.30(1H, d, J =
9.4 Hz), 2.78(1H, ddt, J = 7.9, 4.8, 1.5 Hz), 3.12(1H, m, J =
3.2 Hz), 3.20(1H, m, J = 3.4 Hz), 4.35(1H, ddt, J = 12.5, 4.8,
1.4 Hz), 5.97(1H, dd, J = 3.0, 5.7, Hz), 6.31(1H, dd, J = 3.4,
5.7, Hz); 19F NMR (CDCl3): d ꢀ87.64(3F,d; J = 3.2, Hz),
1
ꢀ126.61(1F, ddq; J = 12.5, 7.9, 3.2 Hz). Minor: H NMR
3.1.10. 4-Pentafluorophenoxy-4-trifluoromethyl-3-oxa-
tricyclo[4.2.1.02,5]non-7-ene (15a,b)
Crude reaction mixture (26 g) was subjected to distilla-
tion under reduced pressure (0.02 mmHg) using a 60 cm
long spinning band column. Seven fractions were collected
and analyzed by NMR:
(CDCl3): d 1.61(1H, d, J = 10.0 Hz), 2.25(1H, d, J =
10.0 Hz), 2.62(1H, ddt, J = 12.1, 4.1, 1.5 Hz), 3.12(1H,
m), 3.24(1H, m), 4.86(1H, d pent., J = 4.1, 1.1 Hz), 5.96(1H,
dd, J = 3.0, 5.7Hz), 6.36(1H, dd, J = 3.4, 5.7 Hz). 19F NMR
(CDCl3): d ꢀ80.10(3F, d, J = 1.1 Hz), ꢀ103.84(1F, dm, J =
12.1, 1.9 Hz). IR (mixture of isomers): 1768 (w), 1463(w)
cmꢀ1. Anal. (mixture of isomers) calc. for C9H8F4O: C,
51.93; H, 3.87; F, 36.51. Found: C, 51.64; H, 3.78; F, 36.35.
Fraction 1: 2.2 g; bp 53–58 8C, 15a, 62.4%, 15b; 33.3%,
15c, 4.3%;
Fraction 2: 5.3 g; bp 58–59 8C, 15a, 73.7%, 15b; 23.5%,
15c, 2.5%;
Fraction 3: 5.9 g; bp 59–60 8C, 15a, 82.6%, 15b; 13.2%,
15c, 4.2%;
3.1.12. Difluoro-(4-fluoro-3-oxa-tricyclo[4.2.1.02,5]non-7-
en-4-yl)-methanesulfonyl fluoride (17a,b)
Fraction 4: 1.4 g; bp 60–67 8C, 15a, 82.2%, 15b, 13.6%,
15c, 4.2%;
Fraction 5: 1.6 g; bp 67–68 8C, 15a, 89%, 15b, 5.4%,
15c, 5.1%;
Isolated mixture of 17a and 17b was contaminated by
unidentified isomeric material (ꢁ3%, NMR, GC/MS, pos-
sibly
1,1-difluoro-2-(3-fluoro-bicyclo[2.2.1]hept-5-en-2-
yl)-2-oxo-ethanesulfonyl fluoride), ratio 66:30:4. 17a,b
major: 1H NMR (CDCl3): d 1.66(1H, d, J = 10.2 Hz),
2.30(1H, d, J = 10.2 Hz), 2.95(1H, ddq, J = 8.0, 4.5,
1.1 Hz), 3.17(1H, m, J = 1.1 Hz), 3.25(1H, m, J =
1.5 Hz), 4.46(1H, ddt, J = 13.0, 4.5, 1.1 Hz), 5.95(1H, dd,
J = 3.4, 5.7Hz), 6.3(1H, dd, J = 3.0, 5.7, Hz); 19F NMR
(CDCl3): d 45.20(1F,dt, J = 11.4, 5.7 Hz), ꢀ111.15(1F,ddt, J
= 247.0, 6.5, 3.9 Hz), ꢀ113.50(1F, ddd, J = 247.0, 5.2,
3.9 Hz), ꢀ119.17(1F, qt, J = 13.0, 10.7 Hz). Minor isomer:
1H NMR (CDCl3): 1H NMR (CDCl3): 1.66(1H), 2.21(1H, d,
J = 10.2 Hz), 2.75(1H, ddt, J = 12.0, 4.2, 1.1 Hz), 3.20(1H,
s), 3.30(1H, m, J = 1.3 Hz), 4.96(1H, d pent., J = 4.1,
1.5 Hz), 5.95(1H, dd, J = 5.7, 3.0 Hz), 6.39(1H, dd, J =
5.7, 3.0 Hz). 19F NMR (CDCl3): d 43.11(1F, dt, 11.0,
4.7 Hz), ꢀ95.83(1F, t, J = 12.0 Hz), ꢀ104.6(1F, dd, J =
246.0, 5.2 Hz), ꢀ107.50(1F, dt, J = 246.0, 4.2 Hz). IR
(mixture of isomers): 1443(w) cmꢀ1. Anal. (mixture of
isomers) calc. for C9H8F4O3S: C, 39.7, H, 3.0;. Found: C,
39.5, H, 2.8.
Fraction 6: 1.9 g; bp 67–76 8C, 15a, 91%, 15b, 3.2%,
15c, 5.8%;
Fraction 7: 1.3 g; bp 76–77 8C, 15a, 91%, 15b, 1.0%,
15c, 8.0%;
Total, fractions 1–7: 19.6 g; yield of the mixture 76%.
1
Compounds 15a,b: major isomer: H NMR (CDCl3): d
1.58(1H, d, J = 9.8 Hz), 2.32(1H, d, J = 9.8 Hz), 2.73(1H, d J
= 4.5 Hz), 3.16(1H, m), 3.21(1H, m), 4.38(1H, d, J =
4.5 Hz), 5.89(1H, dd, J = 3.0, 5.7 Hz), 6.36(1H, dd, J =
3.0, 5.7 Hz); 19F NMR (CDCl3): d ꢀ77.48(3F, t, J = 5.8 Hz),
ꢀ151.27(2F,m),
ꢀ159.22(1F,t,
J
=
21.6 Hz),
ꢀ163.21(2F,m); minor isomer: 1H NMR (CDCl3): d
1.58(1H, d, J = 9.8 Hz), 2.45(1H, d, J = 9.8 Hz),
2.83(1H, dm, J = 4.9 Hz), 3.16(1H) 3.21(1H, m) 4.42(1H,
dm, J = 4.9 Hz), 5.98(1H, dd, J = 3.4, 5.7Hz), 6.32(1H, dd, J
= 3.0, 5.7 Hz). 19F NMR (CDCl3): d ꢀ82.89(3F, t,
J
=
7.1 Hz), ꢀ150.39(2F,m), ꢀ160.0(1F,t, 21.6 Hz),
1
ꢀ164.03(F, m). 15c: H NMR (CDCl3): d 1.83(1H, dm, J

1550
V.A. Petrov et al. / Journal of Fluorine Chemistry 125 (2004) 1543–1552
3.1.13. Exo-4,4-difluoro-3-oxa-tricyclo[4.2.1.02,5]non-7-
ene (19)
cmꢀ1; fraction 1: 1761 (m), 1457(m) cmꢀ1. GC/MS (m/e,
mixture of isomers): 224 (M+, C9H8ClF3O+).
Sample contained 2% of isomer [19F (CDCl3): d
ꢀ62.1(1F,dm; 152 Hz), ꢀ81.1(1F, dm; 152 Hz, endo-iso-
mer?] and ꢁ5% of two unidentified materials isomeric to 19
(GC/MS). 19: 1H NMR (CDCl3): d 1.63(1H, d, J = 9.8 Hz),
2.12(1H, d, J = 9.8 Hz), 2.90(1H, qt, J = 4.9, 1.5 Hz),
3.05(1H, m, J = 0.8 Hz), 3.21(1H, sept, J = 1.3 Hz),
4.35(1H, ddq, J = 12.8, 4.9, 1.5 Hz), 6.01(1H, dd, J =
3.0, 5.7 Hz), 6.31(1H, dd, J = 3.4, 5.7 Hz); 19F NMR
(CDCl3): d ꢀ61.11(1F,dd; 112.0, 5.0 Hz), ꢀ70.81(1F,
ddd, J = 112.0, 12.8, 2.9 Hz). 13C(neat, {1H}): d 38.49(d,
J = 5 Hz), 40.60(dd, J = 3.5, 1.5 Hz), 44.21(d, J = 4Hz),
48.40(dd, J = 26, 29 Hz), 74.30(dd, J = 5.0, 3.0 Hz),
3.1.15. 4-Trifluoromethyl-3-oxa-tricyclo[4.2.1.02,5]non-7-
ene (23a,b)
Mixture of two isomers, ratio 88:12. Major isomer: d
1.61(1H, d pent., J = 9.7, 1.4 Hz), 2.04(1H, dt, J = 9.7,
1.6 Hz), 2.48(1H, octet, J = 5.3, 3.4, 1.6 Hz), 2.84(1H, m),
3.04(1H, m), 4.07(1H, qd, J = 6.8, 3.4 Hz), 4.53(1H, d,
5.3 Hz), 5.8 (1H, dd, J = 5.7, 3.5Hz), 6.22(1H, dd, J = 5.7,
3.0 Hz); 19F NMR (CDCl3): d ꢀ81.24(3F, d, 6.8 Hz); 13C
{H}(neat): 38.22(m), 41.0, 41.55, 46.57, 75.76(q, 33 Hz),
84.17, 125.13 (q, 278 Hz), 131.61, 139.38; minor isomer d:
1.44(1H, d, J = 9.6 Hz), 2.38(1H, dm J = 9.6 Hz), 2.42(1H,
dd, 5.5, 6.2 Hz), 3.04(2H), 4.56(1H, d, 5.5 Hz), 4.82(1H, qd,
9.0, 6.2 Hz), 5.8(1H, dd, J = 5.7, 3.0 Hz), 6.28(1H, dd, J =
5.7, 3.0 Hz); 19F NMR (CDCl3): d ꢀ73.11(3F, d, 9.0 Hz);
13C {H}(neat): 39.50(m), 41.66, 45.83, 73.88(q, 35.0 Hz),
81.93, 124.90 (q, 281.0 Hz), 131.81, 140.97, 142.40. IR
(mixture of isomers): 1460(w) cmꢀ1; GC/MS (m/e, mixture
of isomers): 190 (M+, C9H9F3O+).
122.87(dd,
J = 384, 289 Hz), 132.56, 139.96. IR:
1837(w), 1439(w) cmꢀ1. GC/MS (m/e, major): 158 (M+,
+
+
C8H8F2O+), 129(C6H3F2O+), 109, 92(C7H8 ), 66(C5H5 ).
3.1.14. Reaction of 1 with 20
Gaseous 20 (36 g, 0.27 mol) was slowly added to 25 g of
1 (95%) placed in three-neck round bottomed flask equipped
with a thermometer, and dry ice condenser at 0–10 8C over a
30 min period. The reaction mixture was kept at 0–108 for
1 h after addition was finished, warmed up to ambient
temperature and left agitated overnight. The crude reaction
mixture was the subject of distillation under reduced pres-
sure (26 mmHg) using a 60 cm spinning band column. Five
fractions were collected and analyzed by NMR:
Fraction 1: 12.0 g; bp 53–54 8C, 21a, 55%, 21b, 15.9%,
22, 26.2%, unknown, 2.9%;
3.2. Reactions of norbonenoxetanes
3.2.1. Hydrogenation of 3
A 400 mL Hastelloy shaker tube was loaded with the
solution of 75 g (0.29 mol) of 3 in 100 mL of acetone and 1 g
of Pd on carbon (5 wt.%, Aldrich). The reaction vessel was
evacuated at ꢀ40 8C, and kept with agitation at ambient
temperature under constant pressure of hydrogen (300 psi)
for 12 h. The reactor was unloaded and the crude reaction
mixture was filtered through CeliteR. The solvent was
removed under vacuum and the product was distilled under
vacuum to give 68 g (90%) of 24, bp 64–65/2.5 mmHg. 1H
NMR (CDCl3): d 0.95(1H,t, J = 8.3 Hz), 1.1(1H, t, J =
8.3 Hz), 1.45(1H, d, J = 9.6 Hz), 1.60(2H, m), 2.38(1H, s),
2.48(1H, d, J = 9.6 Hz), 2.55(1H, s), 2.60(1H, d, J = 4.9 Hz),
4.91(1H, d, J = 4.9 Hz); 19F NMR (CDCl3): d ꢀ70.13(3F,q, J
= 9.6 Hz),ꢀ79.36(3F, q, J = 9.6 Hz). IR: 1484(w), 1456(w)
cmꢀ1. Anal. calc. for C10H10F6O: C, 46.2; H, 3.9; F, 43.8.
Found: C, 45.7; H, 3.7; F, 44.0.
Fraction 2: 17.0 g; bp 55–56 8C, 21a, 41.2%, 21b, 18.3%,
22, 37.5%, unknown, 3.0%;
Fraction 3: 6.8 g; bp 55–56 8C, 21a, 27.8%, 21b, 19.1%,
22, 50.2%, unknown, 2.9%;
Fraction 4: 5.0 g; bp 56–60 8C, 21a, 18.6%, 21b, 17.7%,
22; 60.6%, unknown, 2.7%;
Fraction 5: 8.0 g; bp 60–63 8C, 21a, 5.7%, 21b, 13%, 22,
78.3%, unknown, 3.0%;
Total, fractions 1–5: 48.8 g; yield of the mixture 80%.
21a,b, major isomer: 1H NMR (CDCl3): d 1.45(1H, d, J =
10.0 Hz), 2.28(1H, d, J = 10.0 Hz), 2.61(1H, dt, J = 4.6,
1.2 Hz) 2.86(1H, m), 2.93(1H, m), 4.32(1H,dt, J = 4.6,
1.4 Hz), 5.72(1H, dd, J = 3.2, 5.7 Hz), 6.05(1H, dd, J =
3.2, 5.7 Hz); 19F NMR (CDCl3): d ꢀ84.08 (s); minor isomer:
1H NMR (CDCl3): d 1.36(1H, d, J = 10.0 Hz), 2.08(1H, d, J
= 10.0 Hz), 2.62(1H, dt, J = 4.9, 1.2 Hz) 2.90(1H, m),
2.98(1H, m), 4.72(1H, dm, J = 4.9, 1.2 Hz), 5.72(1H, dd,
J = 3.2, 6.0 Hz), 6.05(1H, dd, J = 3.2, 6.0 Hz); 19F NMR
(CDCl3): d ꢀ76.00(s).
3.2.2. Reaction of 3 with butyl lithium
To the solution of 10 g (0.038 mol) of 3 in 50 mL of dry
THF 20 mL of a 2 M solution of butyl lithium in pentane was
slowly added at ꢀ40 8C. The reaction mixture was warm up
to ambient temperature and agitated for 2 days. The reaction
mixture was diluted with 200 mL of saturated solution of
NH4Cl, extracted with CH2Cl2, combined organic layer was
washed with water (200 mL ꢃ 2), dried over MgSO4,
solvent was removed under vacuum and crude product
was distilled under vacuum to give 6g (65%) of 25a,b, bp
92–92.5/0.65 mmHg (ratio 25a:25b – 13:87). 25a: 1H NMR
(CDCl3): d 0.75(3H, t), 1.10–1.20(9H, m), 1.49(1H),
2.14(1H, s), 2.36(1H, d, J = 11.5 Hz), 2.53(1H, s),
2.58(1H, d, J = 4.2 Hz), 4.85(1H, d, J = 4.2 Hz); 19F
22: d 1.62(1H, d pent., J = 9.6, 1.9 Hz), 2.08(1H, dm J =
9.6, 1.5 Hz), 2.87(1H, m), 2.91(1H, m), 2.94(1H, dd, 7.8,
1.8 Hz), 3.99(1H, ddd, J = 7.8, 1.8, 0.7 Hz), 5.99(1H, dd, J =
3.4, 5.7 Hz), 6.11(1H, dd, J = 3.4, 5.7 Hz); 19F NMR
(CDCl3): d ꢀ79.26 (s); 13C {H}(neat): d 43.00, 43.61,
49.46, 51.06, 56.54, 113.95 (q, 293 Hz), 134.69, 138.77,
189.19 (q, J = 34.9 Hz); IR (fraction 5): 1761 (s), 1457(m)

V.A. Petrov et al. / Journal of Fluorine Chemistry 125 (2004) 1543–1552
1551
NMR (CDCl3): d ꢀ70.20(3F, q, J = 10.0Hz), ꢀ79.25(3F, q, J
m/e, major): 158 (M+, C8H8F2O+), 138(C8H7FO+),
1
+
= 10.0 Hz). 25b: H NMR (CDCl3): d 0.75(3H, t), 1.10–
118(C8H6O+), 109(C6H2FO+), 99(C6H2O+), 91(C7H7 ).
1.20(9H, m), 1.40(1H, d, J = 11.0 Hz), 1.52(1H, t, J =
5.7 Hz), 1.65(1H, d, J = 11.0 Hz), 1.94(1H, m), 2.02(1H,
s), 2.90(1H, s); 19F NMR (CDCl3): d ꢀ73.90(3F, qd, J =
11.0, 2.6 Hz), ꢀ77.71(3F, qd, J = 11.0, 1.9 Hz). IR (mixture
3.2.5. Isomerization of 15a,b by action of 27
The reaction was carried under similar conditions using
0.5 g of 27(0.0035 mol) and 10 g (0.048 mol) of 15a,b and
30 mL of CH2Cl2. After vacuum distillation it was isolated
5.8 g (57%) of 29a,b (ratio 62:38), bp 67–69/14 mmHg,
contaminated with ꢁ2% of two unidentified materials iso-
meric to 29a,b (GC/MS).
isomers): 3567 (OH), 1467 cmꢀ1
. Anal. calc. for
C14H18F6O: C, 53.2; H, 5.7; F, 36.0. Found: C, 53.0; H,
5.4; F, 36.2.
29a,b: major isomer: 1H NMR (CDCl3): d 1.46(1H, tt, J =
9.9, 1.2 Hz), 1.58(2H, m), 1.65(1H, tm, J = 5.0, 1.1 Hz),
1.73(1H, m, J = 5.0 Hz), 1.83(1H, t, J = 5.0 Hz), 2.59(1H, s),
4.92(1H, dt, J = 57.8, 2 Hz); 19F NMR (CDCl3): d
3.2.3. Reaction of 13a,b with butyl lithium
To the solution of 13 g (0.068 mol) of 13a,b in 100 mL of
dry ether, 70 mL of a 2 M solution of butyl lithium in
pentane was added drop wise at ꢀ60 to ꢀ50 8C. The
reaction mixture was stirred at ꢀ50 8C for 1 h, brought to
ambient temperature and kept agitated for 3 h. It was poured
slowly into 500 mL of saturated solution of NH4Cl,
extracted with CH2Cl2, the combined organic layer was
washed with water (300 mL ꢃ 2), dried over MgSO4,
solvent was removed under vacuum and crude product
was distilled under vacuum to give 10.5 g (65%) of 26;
bp 92–93/0.65 mmHg. 1H NMR (CDCl3): d 0.87(3H, t, J =
6.6 Hz), 1.27(4H, m), 1.42(2H,m), 1.59(1H, d, J = 9.0 Hz),
1.70(1H, br. s), 1.84(1H, d, J = 9.0 Hz), 1.86(1H, m)
2.05(1H, m), 2.34(1H, dq, J = 6.8, 2.3Hz), 2.77(1H, m),
2.82(1H, m), 3.88(1H, dt, J = 6.8, 1.1 Hz), 6.00(1H, dd, J =
3.0, 5.7 Hz), 6.36(1H, J = 3.0, 5.7 Hz); 19F NMR (CDCl3): d
ꢀ89.80(1F, dq, J = 53.7; 2.6 Hz), ꢀ91.41(3F, d, J =
53.7 Hz). 13C {H} (neat): 21.80, 26.50, 27.57, 31.12,
39.87, 42.50, 43.46(d), 44.18, 48.46, 71.47, 88.26 (dd, J
= 17.4, 11.6 Hz), 133.19, 140.90, 153.42 (dd, J = 282.0,
285.0 Hz). IR: 3436(OH, m), 1735(s), 1462(w) cmꢀ1. GC/
MS (m/e, major): 242 (M+, C14H20F2O+), 176(C9H14F2O+),
120(C5H6F2O+).
1
ꢀ78.00(3F, s), ꢀ197.30(1F,d, 57.8 Hz); minor isomer: H
NMR (CDCl3): d 1.45(1H, dt, J = 11.0, 1.2 Hz), 1.58(3H, m),
2.03(1H, dq, J = 11.2, 1.2 Hz), 2.63(1H, s), 2.95(1H, s),
4.83(1H, dt, J = 56.7, 2.0 Hz); 19F NMR (CDCl3): d
ꢀ77.71(3F,s), ꢀ193.58(1F, d, J = 56.7Hz). IR (mixture of
isomers): 1757(s) cmꢀ1. GC/MS (mixture of isomers; m/e):
208 (M+, C9H8F4O+), 188(C9H7F3O+), 109(C6H2FO+),
+
91(C7H7 ).
Acknowledgement
VAP thanks the reviewer for a number of helpful sugges-
tions and R. Smith Jr. for technical assistance.
Appendix A. Supplementary material
Parameters of 2D H-F HOESY experiment for com-
pounds 16a,b can be found in the on-line version, at
doi:10.1016/j.jfluchem.2004.06.011.
3.2.4. Isomerization of 19 by action of 27
Compound 27 (0.5 g, 0.0035 mol) of was dissolved in
20 mL of CH2Cl2 and 7 g (0.044 mol) of 19 was added to
this solution with the rate varied to maintain the internal
temperature <30 8C (ꢁ30 min). The reaction mixture was
agitated at ambient temperature for 3 h, diluted with 300 mL
of water and extracted with 50 mL of CH2Cl2. Organic layer
was separated, dried over MgSO4, solvent was removed
under vacuum and the residue (6.8 g) distilled under vacuum
to give 3.5 g of liquid bp 73–74/10 mmHg 28a,b [ratio
60:40, containing ꢁ5% of two unidentified materials iso-
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