Perfluoroacetylenephosphonates in Diels-Alder reactions: Synthesis of perfluoroalkylated heterocyclic and carbocyclic phosphonates

Article abstract of DOI:10.1016/j.jfluchem.2008.02.009

Diethyl 3,3,3-trifluoroprop-1-ynylphosphonate and diethyl 3,3,4,4,4-pentafluorobut-1-ynylphosphonate are obtained by the dehydration of the corresponding enols using P₂O₅-Et₃N system as a dehydrating agent, affording acetylenes in 50-60% yield. By the reaction of these perfluoroacetylenephosphonates with acyclic and cyclic 1,3-dienes or diene-like heteroaromatic and aromatic compounds corresponding Diels-Alder cyclo- and bicycloadducts were prepared in good yields (65-90%). The reactivity of the dienes and acetylenes which depends on their structure, as well as the regioselectivity of the reaction are established.

Full text of DOI:10.1016/j.jfluchem.2008.02.009

Journal of Fluorine Chemistry 129 (2008) 478–485
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Perfluoroacetylenephosphonates in Diels–Alder reactions: Synthesis of
perfluoroalkylated heterocyclic and carbocyclic phosphonates
b
b,**
Sergey N. Tverdomed a, , Gerd-Volker Roeschenthaler
*
, Nataliya Kalinovich ,
Enno Lork b, Alla V. Dogadina a, Boris I. Ionin a
a Department of Organic Chemistry, St. Petersburg State Institute of Technology (Technical University), Moskovskii pr. 26, St. Petersburg 190013, Russia
b Institute for Inorganic and Physical Chemistry, The University of Bremen, Leobener Str, Bremen D-28334, Germany
A R T I C L E I N F O
A B S T R A C T
Article history:
Diethyl 3,3,3-trifluoroprop-1-ynylphosphonate and diethyl 3,3,4,4,4-pentafluorobut-1-ynylphospho-
nate are obtained by the dehydration of the corresponding enols using P2O5–Et3N system as a
dehydrating agent, affording acetylenes in 50–60% yield. By the reaction of these perfluoroacetylenepho-
sphonates with acyclic and cyclic 1,3-dienes or diene-like heteroaromatic and aromatic compounds
corresponding Diels–Alder cyclo- and bicycloadducts were prepared in good yields (65–90%). The
reactivity of the dienes and acetylenes which depends on their structure, as well as the regioselectivity of
the reaction are established.
Received 28 January 2008
Received in revised form 19 February 2008
Accepted 20 February 2008
Available online 4 March 2008
Keywords:
Diels–Alder condensation
Perfluoroacetylenephosphonates
Dienes
ß 2008 Elsevier B.V. All rights reserved.
Diels–Alder adducts
NMR spectroscopy
Mass spectrometry
1. Introduction
vinylphosphonates is the Diels–Alder reaction of 1,3-dienes with
substituted acetylenes. However, there are only few examples of
For many years, the extensive involvement of phosphoric acid
derivatives in living systems has been known [1]. These
compounds have found important applications in medicine [2],
agriculture [3], industry [4], and as reagents in organic synthesis
[5]. The incorporation of a fluorine-containing group into such
molecules alters dramatically their physical, chemical and
biological properties [6–8]. Recently, the regioselective synthesis
of fluorinated vinylphosphonates has become significant task in
synthetic chemistry [9].
Themethodsforthepreparationoffluorine-containingvinylpho-
sphonates are rather limited [9–15], including Horner–Emmons
condensation [10], reactions of fluorinated acid chlorides with
phosphites [11,12], or sequential transformations of bisphospho-
nates [13,14]. The other approach for the synthesis of functionalized
reactions with acetylenes containing perfluoroalkyl groups [16–19]
or dialkylphosphonate functions [20–29]. In some cases these
reactions were accompanied by spontaneous aromatization of
primarilyformed bicyclicadductswithelimination oflow molecular
weight compounds, such as: CO [17], C2H4 [20] or CO2 [22,23].
Dienophiles, possessing both the dialkylphosphonate and perfluor-
oalkyl substituents have been first synthesized in 1985 by Shen’s
group [30] and used as reagents in dipolar 1,3- [31–33] and 1,2-
cycloadditions [34]. However, no example for the application of
these compounds in Diels–Alder reactions has been found.
2. Results and discussion
The perfluoroacetylenephosphonates: diethyl 3,3,3-trifluoro-
prop-1-ynylphosphonate (3a) and diethyl 3,3,4,4,4-pentafluoro-
but-1-ynylphosphonate (3b), were prepared according to the
known procedure [35]. However, we introduce some improve-
ments which resulted in better yields (87–90%) and purity of the
desired acetylenes. Compounds (3a and b) can be also successfully
prepared in 50–60% yield, by the dehydration of the corresponding
* Corresponding author.
** Corresponding author. Tel.: +49 421 218 2493; fax: +49 421 218 4267.
E-mail addresses: tverd1975@mail.ru (S.N. Tverdomed),
gvr@chemie.uni-bremen.de (G.-V. Roeschenthaler).
0022-1139/$ – see front matter ß 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2008.02.009

S.N. Tverdomed et al. / Journal of Fluorine Chemistry 129 (2008) 478–485
479
Scheme 1.
enols (2a and b) [36] using the P2O5–Et3N system in methylene
chloride at ꢀ20 8C (Scheme 1).
nic control of the reaction was noticed by the predominate
formation of isomers (7a and b) in line with the polarization of the
parent compounds [38]. In the case of Rf = CF3, the (7a:8a) ratio of
isomers, according to 31P, 19F and 1H NMR analysis, was
(61:29 mol%) and for Rf = C2F5 (7b:8b) = (56:44 mol%), respec-
tively. Structures of isomers (7a and b) and (8a and b) were
established by the 13C NMR analysis. The signals of the carbon
atoms C(3) and C(6), C(4) and C(5) of the isomers (7a and b) and (8a
and b) can be assigned, when a set of related compounds is
considered. In the case of 1-substituted unsymmetrical 1,3-
alkadiene, e.g., piperylene, we confirmed the known regioselec-
tivity of Diels–Alder reaction [39]; only one isomer which responds
to the electronic control of reaction has been found (Scheme 2).
The stability of the prepared carbocyclic and bicyclic com-
pounds (4a and b–9a and b; 10a) greatly depends on both: the Rf
nature and the presence of substituents in 3 and 6 positions of the
formed cyclohexadiene ring. Generally, the carbocyclic and
bicyclic adducts containing C2F5 substituent at 3 and 6 positions
are formed with lower yields and are less thermally stable when
compared with related carbocycles having CF3 substituent at 4 and
Perfluoroacetylenephosphonates (3a and b) are versatile and
active dienophiles in the diene synthesis with classical donor 1,3-
alkadienes, such as isoprene and 2,3-dimethyl-1,3-butadiene. The
reaction occurs even at room temperature, affording carbocyclic
Diels–Alder adducts (4a and b, 7a and b, 8a and b). However,
complete conversion of the parent tetramethyl acetylene bipho-
sphonate was achieved after 2–3 h of heating at 80 8C (Table 1). The
reaction was carried out in a sealed ampoule under dry argon
atmosphere with an excess of 1,3-diene using anhydrous benzene
as a solvent and a catalytic amount of 1,4-hydroquinone (5 mol%)
as a polymerization inhibitor (Scheme 2). With 1-substituted 1,3-
dienes such as penta-1,3-diene and hexa-2,4-diene the reaction
proceeded smoothly at rather rigid conditions (Table 1) and yields
of the targeted carbocyclic perfluorophosphonates (9a and b, 10a)
were noticeably lower, probably due to the restricted trans,trans–
cis,cis inversion of the parent 1,3-dienes [37]. With cyclic 1,3-
dienes, possessing fixed cis-configuration, such as cyclohexa-1,3-
diene, cyclopenta-1,3-diene (generated in situ upon heating to
190 8C the commercially available bicyclopenta-1,3-diene), the
diene synthesis proceeded readily (Table 1) and yields of adducts
(5a and b, 6a and b) were satisfactory (Scheme 2).
5
positions (Table 1). Thus, the diene synthesis with 1,4-
disubstituted diene, e.g., hexa-2,4-diene, requires rather harsh
conditions; while the cycloadduct (10a) was prepared with an
appropriate yield (65%). The same reaction with acetylene (3b)
(Rf = C2F5) failed even upon 10–12 h of heating at 200 8C, indicating
the extreme instability of the expected cycloadduct. Another
example of thermal instability of C2F5-substituted adducts is
With diethyl 3,3,3-trifluoroprop-1-ynylphosphonate (3a) and
diethyl 3,3,4,4,4-pentafluorobut-1-ynylphosphonate (3b) as
examples, we were able to trace the reaction regioselectivity with
an unsymmetrical 2-substituted 1,3-diene (isoprene). The electro-
Table 1
Reaction conditions of 1,4-cycloaddition of conjugated dienes, aromatic and heteroaromatic compounds to perfluoroacetylenephosphonates (3a and b)
No.
Dienophile
Cycloadduct(s)
(ratio of regioisomers, mol%)a
Reaction conditions
Yield of isolated Diels–
Alder product (%)
Other
products
Temperature
Duration
Solvent
Ratio of reagents (mol)
diene:dienophile
(8C)
(h)
1
3a
3b
3a
3b
3a
3b
3a
3b
3a
3b
3a
3a
3b
3a
3b
3a
3b
4a
80
80
2
2
2
3
4
6
3
Benzene
Benzene
Benzene
Benzene
Benzene
Benzene
Benzene
Benzene
1,3-Diene
1,3-Diene
Benzene
Furan
1.5:1
2:1
85
82
80
73
66
70
88
78
74
67
65
90
81
82
76
81
73
2
4b
3
5a
70
1.5:1
1.5:1
1:1
4
5b
75
15bb
5
6a
195
195
80
6
6b
1.1:1
1.5:1
2:1
7
7a + 8a (61:39)
8
7b + 8b (56:44)
9a
80
3.5
9
100
120
180
80
12
15
12
5
20:1
25:1
2:1
16a, 17ac
16b, 17bc
10
11
12
13
14
15
16
17
9b
10a
11a
15:1
20:1
1.1:1
1.5:1
3:1
11b
85
6
Furan
3bd
12a
80
10
15
12
15
THF
12b
85
THF
13a + 14a (66:34)
13b + 14b (86:14)
80
Benzene
Benzene
3ad
3bd
85
5:1
By analysis of the ratio of integral intensity of 31P, 19F and 1H NMR signals.
a
b
c
ꢁ5 mol% in the main compound after distillation.
ꢁ3% and 2% mol of isomeric cyclohexadienes (31P NMR, d ꢁ 14.7 and d ꢁ 14.9–15.1 ppm) in the main product after distillation.
ꢁ2–5 mol% in the main compound after distillation, determined by analysis of integral intensities of 31P, 19F NMR signals.
d

480
S.N. Tverdomed et al. / Journal of Fluorine Chemistry 129 (2008) 478–485
Scheme 2.
compound (5b), which upon the distillation shows retro-Diels–
Alder reaction with ethylene elimination and formation of the
aromatic compound, diethyl 2-(pentafluoroethyl)phenylphospho-
nate (15b) as an admixture (ꢁ5 mol%). The formation of the
compound (15b) was confirmed by the methods 31P, 19F, and 1H
NMR spectroscopy. During the distillation of carbocyclic com-
pounds (9a and b) (31P, 19F NMR spectroscopy), the C(4) = C(5)
double bond migration has been observed and expected product
was obtained with traces of isomeric cyclohexa-2,4- (16a and b,
ꢁ3 mol%) and -2,6-dienylperfluoroalkylphosphonates (17a and b,
ꢁ2 mol%) (Scheme 2).
Compounds (4a and b–9a and b; 10a) are colorless liquids.
Their structures were established using 1H, 31P, 19F and 13C NMR
spectroscopy. In the 1H NMR spectra the characteristic signals are
those of methylene protons in the region of d 1.1–1.6 ppm and of
vinyl protons at d 5.0–7.0 ppm. The 13C NMR spectra of compounds
(4a and b–9a and b; 10a) are characterized by quadruplet(triplet)–
doublet and doublet–quadruplet(triplet) signals of carbon nuclei
C(2) and C(1), respectively, in the region of d 157–131 ppm with
the coupling constants JCP ꢁ 180 Hz, JCF ꢁ 280 Hz, JCF ꢁ 40 Hz,
2JCP ꢁ 4–10 Hz, and by typical doublet signals of carbon nuclei C(4),
C(5) and C(3), C(6) at d 115–143 ppm (3JCP ꢁ 4–6 Hz) and at d 57–
1
1
2
Scheme 3.

S.N. Tverdomed et al. / Journal of Fluorine Chemistry 129 (2008) 478–485
481
28 ppm (2JCP ꢁ 6–11 Hz). The 31P NMR spectra contain character-
istic signals in the region of d ꢁ 9–15 ppm, the 19F NMR spectra
show signals at d ꢁ ꢀ54 to ꢀ64 (ꢁꢀ83, ꢀ112) ppm.
Perfluoroacetylenephosphonates (3a and b) readily undergo
Diels–Alder reaction with furan, anthracene and 2-methylfuran,
forming corresponding carbocyclic and (hetero)bicyclic perfluor-
oalkylphosphonates (11a and b–14a and b) in good yields (90–
73%). The reactions were conducted by heating in a sealed ampoule
with a catalytic amount of 1,4-hydroquinone (5 mol%) as a
polymerization inhibitor (Scheme 3), in an appropriate solvent
(Table 1) or in an excess of a diene. The reaction conditions, reagent
ratio and yields of products are given in Table 1.
The reactivity of 2-methylfuran does not differ from that of
unsubstituted furan, contrasting to 1-substituted 1,3-dienes
(penta-1,3-diene, hexa-2,4-diene) and unsubstituted 1,3-buta-
diene (Table 1). This fact could be probably explained by the fixed
cis-configuration of the diene system in furans; the role of a methyl
group is limited to its electron-donor effect. The similar reactivity
was observed when anthracene was used as a diene (Table 1).
The stability of carbocyclic and (hetero)bicyclic adducts (11a
and b–14a and b) depends mainly on the type of perfluoroalkyl
group and on the presence of substituents at the 3 and 6 positions.
Compounds (13a and b–14a and b) even at heating to 85–90 8C
undergo retro-Diels–Alder reaction forming starting reagents: 2-
methylfuran and a perfluoroacetylenephosphonate (3a and b),
which in small amounts (2–5%) were identified by 31P, 19F NMR
spectroscopy. The most remarkable are traces (5%) of acetylene
(3b) during the distillation of the mixture of regioisomers
(13b + 14b) with Rf = C2F5. At 180–200 8C the retro-Diels–Alder
reaction of compounds (13a and b–14a and b) proceeds
quantitatively within a few minutes. The bicyclic adducts (11a
and 11b) show much higher thermal stability; compound (11a)
remains intact at short time heating to 200 8C and even at longer
heating at 90–100 8C. The distillation of perfluoroalkylpho-
sphonate (11b) with Rf = C2F5 afford insignificant amount of
the alkyne (3b) (1–2%). Bicyclic compounds (12a, 12b) show
higher thermal stability and compound (12a) is resistant to the
prolonged heating at 130–150 8C. Only at 170–200 8C compounds
(12b, 12a) decompose slowly into substrates: alkynes (3a and b)
and anthracene.
With symmetrical dienes (furan and anthracene) the reaction is
regioselective and affords only one regioisomer (11a and b–12a
and b). In the case of 2-methylfuran the reaction is not
regioselective, forming a mixture of regioisomers: (13a + 14a),
(13b + 14b) and 6-Me-substituted isomers (13a and 13b) pre-
dominantly. With the alkyne (3b) the regioselectivity of the
reaction is noticeably higher than with (3a), giving 86%:14% for the
(13b:14b) and 66%:34% for (13a:14a). Structures of the regioi-
somers (13b, 14b) and (13a, 14a) were unequivocally determined
by 13C NMR spectra. Chemical shifts and spin–spin coupling
constants of carbon nuclei C(3) and C(6), C(4) and C(5) of the
isomers (13b, 14b) and (13a, 14a) are quite characteristic and
allowed easy identification of these compounds.
Fig. 1. Molecular structure of compound 12a; bond length in pm, bond angle in
8[P(1)-O(1) 146.8(3); P(1)-O(2) 158.1(4); P(1)-O(3) 154.7(3); O(2)-C(18) 143.2(10);
O(3)-C(20) 143.3(7); C(18)-C(19) 114.9(14); C(20)-C(21) 144.3(11); P(1)-C(1)
179.2(3); C(1)-C(2) 133.8(5); C(2)-C(7) 150.9(5); F(1)-C(7) 133.3(6); C(2)-C(3)
153.6(4); C(3)-C(4) 153.0(4); C(4)-C(5) 139.5(4); C(3)-C(8) 152.3(4); C(6)-C(13)
151.2(5); C(8)-C(9) 139.0(5); C(9)-C(10) 140.1(5); C(10)-C(11) 139.2(6); O(1)-P(1)-
O(3) 117.2(2); O(1)-P(1)-O(2) 115.4(2); O(3)-P(1)-O(2) 98.8(3); O(1)-P(1)-C(1)
117.45(18); O(3)-P(1)-C(1) 102.18(19); O(2)-P(1)-C(1) 103.12(18); C(2)-C(1)-C(6)
112.1(3); C(2)-C(1)-P(1) 132.0(3); C(6)-C(1)-P(1) 115.9(2); C(1)-C(2)-C(7) 127.8(3);
C(1)-C(2)-C(3) 114.9(3); C(7)-C(2)-C(3) 117.3(3); C(8)-C(3)-C(4) 105.3(2); C(8)-
C(3)-C(2) 105.8(3); C(4)-C(3)-C(2) 105.0(3); C(11)-C(10)-C(9) 121.6(4); C(8)-C(13)-
C(12) 120.4(3); F(3)-C(7)-F(2) 118.6(6); F(3)-C(7)-F(1) 100.6(7); F(3)-C(7)-C(2)
114.6(4).
1
1
with coupling constants JCP ꢁ 185–203 Hz, JCF ꢁ 270–290 Hz,
2
2JCF ꢁ 26–37 Hz and JCP ꢁ 7–11 Hz, and characteristic signals of
C(4), C(5) and C(3), C(6) nuclei at d 143–147 ppm and d 84–94 ppm.
In the 31P spectra the characteristic signals are those at d ꢁ9–
13 ppm, in 19F NMR spectra the signals at dꢁ ꢀ62 to ꢀ64 (ꢁꢀ84,
ꢀ113) ppm.
In conclusion, we demonstrated a new methodology for the
synthesis of carbocyclic, carbobicyclic and carbo(hetero)bicyclic
1,2-perfluoroalkyl vinylphosphonates, based on the Diels–Alder
reaction of perfluoroacetylenephosphonates (3a and b) with
classical donor acyclic and cyclic 1,3-alkadienes and some
aromatic and heteroaromatic compounds.
3. Experimental
All reagents from commercial suppliers, were used without
further purification. All solvents were freshly distilled before use
from appropriate drying agents THF was distilled from sodium/
benzophenone and used immediately. All other reagents were
recrystallized or distilled when necessary. Reactions were
performed under atmosphere of dry nitrogen. Analytical TLCs
were performed with Merck silica gel 60 F254 plates. Visualization
was accomplished by UV light or spraying by Ce(SO4)2 solution in
5% H2SO4. Column chromatography was carried out using Merck
silica gel 60 (230–400 mesh ASTM). Melting points were
determined with an Electrothermal IA9100 Digital Melting Point
Apparatus without correction. All boiling points are uncorrected.
NMR spectra were obtained on a Bruker DPX-200 spectrometer
operating at 200.13 MHz for 1H (TMS), 188.31 MHz for 19F
(CFC13), 80.99 MHz for 31P (H3PO4) and 50.32 MHz for 13C
(TMS). MS and HRMS spectra were obtained on a Varian MAT
CH7A instrument at 70 eV.
Compounds (11a and b–14a and b) are colorless liquids stable
under ambient conditions. The cycloadduct (12a) is a colorless
crystalline substance. Structures of these compounds were
established using 1H, 31P, 19F, and 13C NMR spectroscopy and
mass-spectrometry. Structure of compound (12a) is confirmed by
X-ray structural analysis (Fig. 1).
The 1H NMR spectra are characterized by the resonance signals
of the methylene groups protons at d 5.5–5.9 ppm, the methyl
groups at d ꢂ 1.8–1.9 ppm and vinyl protons at d 5.5–7.5 ppm. The
13C NMR spectra of compounds (11a and b–14a and b) contain
quadruplet(triplet)–doublet and doublet–quadruplet(triplet) sig-
nals of C(2) and C(1) nuclei at d 152–157 ppm and d 145–154 ppm

482
S.N. Tverdomed et al. / Journal of Fluorine Chemistry 129 (2008) 478–485
3.1. Synthesis of perfluoroalkylacetylene phosphonates (3a and b)
(general procedure)
Diethyl
4,5-dimethyl-2-(trifluoromethyl)cyclohexa-1,4-dien-1-
ylphosphonate (4a). Bp: 85–87 8C (0.1 mm Hg). Yield: 85%. 31P
NMR(CDCl3) d: 14.67 (q, 4JPF 3.5 Hz). 19F NMR(CDCl3) d: ꢀ63.46 (d,
4
2
2
Method A. To a solution of 69 mmol of corresponding ketone–
enol mixture (1a and b) or (2a and b) in 100 ml of anhydrous
methylene chloride cooled to ꢀ40 8C under dry nitrogen atmo-
sphere at vigorous stirring was quickly added diisopropylmethy-
lamine 32.1 g (248 mmol). The solution was stirred for 10 min at
this temperature and then trifluoromethanesulfonic acid anhy-
dride 23.4 g (83 mmol) was added dropwise keeping the mixture
below ꢀ30 8C. The suspension was kept for 3 h at ꢀ30 8C and then
for 3 h at 5–7 8C. The reaction mixture was diluted with anhydrous
ether (1000 ml) and left overnight at ꢀ30 8C. The suspension was
filtered, the solid was washed with cold ether (3ꢃ 50 ml). The
filtrate was washed with water (2ꢃ 250 ml) and 3% hydrochloric
acid (2ꢃ 320 ml) and dried over MgSO4. The solvents were
evaporated at a reduced pressure and residue was distilled in a
vacuum with a 20 cm Vigreux column.
3F, JFP 3.4 Hz). 13C NMR(CDCl3) d: 136.77 (qd, C-2, JCF 32.9, JCP
3.7 Hz), 131.30 (dq, C-1, 1JCP 178.3, 3JCF 3.1 Hz), 122.74 (qd, C-7, 1JCF
3
3
275.1, JCP 10.2 Hz), 122.29 (d, C-5, JCP 10.2 Hz), 120.90 (s, C-4),
62.67 (d, C-i, 2JCP 6.2 Hz), 37.00 (d, C-6, 2JCP 7.8 Hz), 33.56 (dq, C-3,
3JCP 13.0, 3JCF 2.8 Hz), 18.01 (s, C-8), 17.94 (s, C-9), 16.49 (d, C-j, 3JCP
6.5 Hz). 1H NMR(CDCl3) d: 4.05 (dq, 4H, 3JHH 7.7, 3JHP 8.4 Hz), 2.94
3
3
(m, 2H), 2.82 (d, 2H, JHP 8.8 Hz), 1.58 (s, 6H), 1.25 (t, 6H, JHH
7.0 Hz). MS (EI) m/e = 311 ([M–H]+, 55%), 291(70), 255(20),
235(100), 215(93), 201(12), 187(5), 155(40); HRMS m/e ([M–
H]+) calculated for C13H19F3O3P 311.10239, found 311.10175.
Diethyl 4,5-dimethyl-2-(pentafluoroethyl)cyclohexa-1,4-dien-1-
ylphosphonate (4b). Bp: 90–92 8C (0.1 mm Hg). Yield: 82%. 31P
NMR(CDCl3) d: 15.00 (t, JPF 4.0 Hz). 19F NMR(CDCl3) d: ꢀ82.33 (t,
4
3F, 3JFF 2.2 Hz), ꢀ111.19 (m, 2F). 13C NMR(CDCl3) d: 135.16 (td, C-2,
2JCF 22.5, JCP 3.7, JCF 0.8 Hz), 134.78 (dt, C-1, JCP 179.6, JCF
3.1 Hz), 122.54 (d, C-5, 3JCP 9.2 Hz), 121.20 (m, C-4), 119.43 (qt, C-8,
1JCF 287.8, 2JCF 38.2, 4JCP 1.7 Hz), 113.41 (tq, C-7, 1JCF 256.3, 2JCF 38.9,
2
3
1
3
Method B. To a suspension of phosphorus pentoxide 10.79 g
(76 mmol) in 50 ml of anhydrous methylene chloride cooled to
ꢀ20 to ꢀ25 8C under dry nitrogen atmosphere with vigorous
stirring was added dropwise a solution of 69 mmol of the
corresponding ketone–enol mixture (1a and b) or (2a and b)
and triethylamine 27.93 g (276 mmol) in 70 ml of anhydrous
methylene chloride, maintaining the reaction mixture tempera-
ture below ꢀ20 8C. The suspension was stirred for 3 h at this
temperature and then for 4 h at 5–7 8C. Then the reaction mixture
was diluted with anhydrous ether (1000 ml) and left overnight at
ꢀ30 8C. The product was isolated as presented in the Method A.
Diethyl 3,3,3-trifluoroprop-1-ynylphosphonate (3a). Bp: 81–85 8C
(12 mm Hg). Yield: 90% (Method A), 50% (Method B). 31P
3JCP 1.7 Hz), 62.66 (d, C-i, JCP 6.5 Hz), 38.20 (d, C-6, JCP 8.5 Hz),
2
2
33.84 (dt, C-3, 3JCP 12.9, 3JCF 2.0 Hz), 18.11 (d, C-9, 4JCP 0.9 Hz), 18.00
5
3
(d, C-10, JCP 0.7 Hz), 16.56 (d, C-j, JCP 6.5 Hz). 1H NMR(CDCl3) d:
3
3
3
4.10 (dq, 4H, JHH 7.3, JHP 8.8 Hz), 3.02 (m, 2H), 2.83 (d, 2H, JHP
7.3 Hz), 1.62 (s, 6H), 1.29 (t, 6H, JHH 7.1 Hz). MS (EI) m/e = 361
([M–H]+, 100%), 341(85), 333(20), 313(20), 305(30), 285(85),
265(8), 215(30); HRMS m/e ([M–H]+) calculated for C14H19F5O3P
361.09920, found 361.09922.
3
Diethyl 3-(trifluoromethyl)bicyclo[2.2.2]octa-2,5-dien-2-ylpho-
sphonate (5a). Bp: 82–84 8C (0.1 mm Hg). Yield: 80%. 31P
NMR(CDCl3) d: 12.80 (q, JPF 4.0 Hz). 19F NMR(CDCl3) d: ꢀ62.89
4
4
NMR(CDCl3) d: ꢀ10.19 (q, JPF 4.0 Hz). 19F NMR(CDCl3) d: ꢀ53.87
(d, 3F, 4JFP 4.0 Hz). 13C NMR(CDCl3) d: 146.62 (qd, C-2, 2JCF 33.9, 2JCP
6.4 Hz), 139.78 (dq, C-1, 1JCP 185.1, 3JCF 4.2 Hz), 134.45 (d, C-5, 3JCP
4.2 Hz), 133.28 (d, C-4, 4JCP 2.1 Hz), 122.45 (qd, C-7, 1JCF 272.7, 3JCP
7.1 Hz), 62.58 (d, C-i, 2JCP 5.7 Hz), 41.34 (d, C-6, 2JCP 8.5 Hz), 38.59
(dq, C-3, 3JCP 9.9, 3JCF 2.8 Hz), 24.68 (d, C-8, 3JCP 2.1 Hz), 24.22 (s, C-
4
1
(d, 3F, JFP 4.0 Hz). 13C NMR(CDCl3) d: 113.29 (qd, C-3, JCF 260.5,
3JCP 6.1 Hz), 82.38 (dq, C-2, JCP 52.9, JCF 53.9 Hz), 77.58 (dq, C-1,
2
2
1JCP 275.9, 3JCF 6.1 Hz), 64.87 (d, C-i, 2JCP 5.8 Hz), 16.23 (d, C-j, 3JCP
6.7 Hz). 1H NMR(CDCl3) d: 4.17 (dq, 4H, JHH 7.3, JHP 8.8 Hz),
3
3
1.33(td, 3H, JHH 7.2, JHP 0.7 Hz). MS (EI) m/e = 229 ([M–H]+, 2%),
215(5), 203(42), 201(14), 182(40), 175(100), 157(44); HRMS m/e
([M–H]+) calculated for C7H9O3F3P 229.02414, found 229.02366.
Diethyl 3,3,4,4,4-pentafluorobut-1-ynylphosphonate (3b). Bp:
105–107 8C (12 mm Hg). Yield: 87% (Method A), 60% (Method B).
31P NMR(CDCl3) d: ꢀ10.58 (t, 4JPF 6.0 Hz). 19F NMR(CDCl3) d: ꢀ86.47
(t, 3F, 3JFF 2.6 Hz), ꢀ106.05 (m, 2F). 13C NMR(CDCl3) d: 117.69 (qt, C-
9), 16.50 (d, C-j, JCP 6.4 Hz). 1H NMR(CDCl3) d: 6.29 (m, 2H), 4.26
3
4
3
(m, 2H), 3.98 (m, 4H, 3JHP 7.1 Hz), 1.32 (s, 4H), 1.22 (td, 6H, 3JHH 7.2,
4JHP 2.1 Hz). MS (EI) m/e = 310 ([M]+, 22%), 290(17), 281(20),
255(35), 227(38), 213(100), 207(30), 172(38), 162(36), 153(18);
HRMS m/e ([M]+) calculated for C13H18F3O3P 310.09457, found
310.09436.
Diethyl 3-(pentafluoroethyl)bicyclo[2.2.2]octa-2,5-dien-2-ylpho-
sphonate (5b). Bp: 86–88 8C (0.1 mm Hg). Yield: 73%. 31P NMR
spectrum, d, ppm (CDCl3): 12.86 (t, 4JPF 5.45 Hz). 19F NMR(CDCl3) d:
1
2
4
1
2
4, JCF 285.3, JCF 35.1, JCP 1.2 Hz), 104.53 (tq, C-3, JCF 249.0, JCF
43.4, 3JCP 5.0 Hz), 82.61 (dt, C-1, 1JCP 272.6, 3JCF 6.2 Hz), 81.69 (dt, C-
2, 2JCP 46.5, 2JCF 36.9 Hz), 64.93 (d, C-i, 2JCP 5.9 Hz), 16.17 (d, C-j, 3JCP
6.5 Hz). 1H NMR(CDCl3) d: 4.18 (dq, 4H, 3JHH 7.1, 3JHP 8.1 Hz), 1.34
(td, 3H, JHH 6.9, JHP 0.7 Hz). MS (EI) m/e = 279 ([M–H]+, 20%),
253(57), 237(20), 225(100), 207(18), 183(21), 157(7); HRMS m/e
([M–H]+) calculated for C8H9O3F5P 279.02095, found 279.02190.
ꢀ84.02 (t, 3F, JFF 3.0 Hz), ꢀ112.56 (m, 2F). 13C NMR(CDCl3) d:
3
145.27 (td, C-2, 2JCF 23.1, 2JCP 6.1 Hz), 143.26 (dt, C-1, 1JCP 186.2, 3JCF
3
4
3
4
3.6 Hz), 134.53 (d, C-5, JCP 3.9 Hz), 133.42 (d, C-4, JCP 1.9 Hz),
119.26 (qt, C-8, 1JCF 287.5, 2JCF 39.9, 4JCP 1.6 Hz), 112.83 (tq, C-7, 1JCF
254.0, 2JCF 39.1, 3JCP 5.6 Hz), 62.49 (d, C-i, 2JCP 5.7 Hz), 42.12 (d, C-6,
2JCP 8.5 Hz), 39.28 (dt, C-3, JCP 9.6, JCF 4.5 Hz), 24.34 (d, C-9, JCP
3
3
4
1.2 Hz), 24.11 (s, C-10), 16.41 (d, C-j, 3JCP 6.4 Hz). 1H NMR(CDCl3) d:
3.2. Diels–Alder reaction (typical procedure)
3
6.26 (m, 2H), 4.30 (m, 2H), 3.95 (m, 4H, JHP 6.9 Hz), 1.28 (s, 4H),
1.18 (td, 6H, JHH 7.3, JHP 2.7 Hz). MS (EI) m/e = 360 ([M]+, 25%),
331(30), 305(38), 277(60), 260(35), 222(25), 213(100), 189(37);
HRMS m/e ([M]+) calculated for C14H18F5O3P 360.09137, found
360.09153.
3
4
To a preliminary cooled 50 ml ampoule (ꢀ30 8C) was placed
5 mmol of corresponding diethyl perfluoroacetylenephosphonate
(3a and b) in 5 ml of appropriate solvent (see Table 1), then
required 1,3-diene cooled to 0 8C in amount listed in Table 1 was
added and the ampoule was sealed. The mixture was heated at the
temperature from 70 to 195 8C for 2–12 h (Table 1). The reaction
proceeding was monitored by means of 31P and 19F NMR
spectroscopy and it was carried out after complete consumption
of the parent alkynephosphonate. Then solvent and 1,3-diene
excess were removed in a vacuum and crude product was purified
by distillation in a high vacuum, or by crystallization, or by column
chromatography.
Diethyl 3-(trifluoromethyl)bicyclo[2.2.1]hepta-2,5-dien-2-ylpho-
sphonate (6a). Bp: 81–82 8C (0.1 mm Hg). Yield: 66%. 31P
NMR(CDCl3) d: 12.26 (q, JPF 4.5 Hz). 19F NMR(CDCl3) d: ꢀ63.52
4
(d, 3F, 4JFP 4.3 Hz). 13C NMR(CDCl3) d: 156.44 (qd, C-2, 2JCF 35.9, 2JCP
1
3
10.0 Hz), 148.61 (dq, C-1, JCP 197.3, JCF 4.6 Hz), 142.96 (dq, C-5,
5
4
4
3JCP 3.3, JCP 1.5 Hz), 142.05 (dq, C-4, JCP 2.7, JCF 0.6 Hz), 122.85
(qd, C-7, 1JCF 270.9, 3JCP 4.6 Hz), 73.73 (dq, C-8, 3JCP 5.6, 4JCF 0.8 Hz),
62.60 (d, C-i, 2JCP 6.3 Hz), 56.45 (d, C-6, 2JCP 10.4 Hz), 53.59 (dq, C-3,

S.N. Tverdomed et al. / Journal of Fluorine Chemistry 129 (2008) 478–485
483
3
3
3JCP 13.0, JCF 2.1 Hz), 16.50 (d, C-j, JCP 6.5 Hz). 1H NMR(CDCl3) d:
141(38); HRMS m/e ([M–H]+) calculated for C13H17F5O3P
347.08355, found 347.08418.
6.81 (m, 2H), 4.04 (m, 1H), 3.97 (dq, 4H, 3JHP 8.1, 3JHH 3.2 Hz), 3.84
2
3
3
(m, 1H), 2.04 (dd, 2H, JHH 36.0, JHH 6.9 Hz), 1.22 (t, 6H, JHH
7.1 Hz). MS (EI) m/e = 296 ([M]+, 15%), 267(5), 252(8), 247(10),
227(100), 200(30), 175(45), 159(18), 140(18), 109(25); HRMS m/e
([M]+) calculated for C12H16F3O3P 296.07892, found 296.07845.
Diethyl
5-methyl-2-(pentafluoroethyl)cyclohexa-1,4-dien-1-
ylphosphonate (8b). Bp: 81–82 8C (0.1 mm Hg). Yield: 78% (together
with isomer 7b). Content in the mixture 44 mol%. 31P NMR(CDCl3)
d: 15.00 (q, 4JPF 4.0 Hz). 19F NMR(CDCl3) d: ꢀ82.30 (t, 3F, 3JFF 2.2 Hz),
ꢀ111.00 (m, 2F). 13C NMR(CDCl3) d: 135.08 (td, C-2, 2JCF 22.2, 2JCP
3.6, 3JCF 1.1 Hz), 134.46 (dt, C-1, 1JCP 179.8, 3JCF 3.3 Hz), 130.54 (d, C-
5, 3JCP 9.1 Hz), 129.26 (qd, C-4, 4JCF 1.6, 4JCP 1.1 Hz), 119.63 (qt, C-8,
1JCF 288.5, 2JCF 38.6, 4JCP 2.0 Hz), 113.53 (tq, C-7, 1JCF 255.8, 2JCF 39.0,
Diethyl
3-(pentafluoroethyl)bicyclo[2.2.1]hepta-2,5-dien-2-
ylphosphonate (6b). Bp: 84–85 8C (0.1 mm Hg). Yield: 70%. 31P
NMR(CDCl3) d: 12.20 (t, JPF 5.2 Hz). 19F NMR(CDCl3) d: ꢀ84.39 (t,
4
3F, 3JFF 3.0 Hz), ꢀ113.58 (m, 2F). 13C NMR(CDCl3) d: 155.07 (td, C-2,
2
1
3
2
2
2JCF 25.0, JCP 10.2 Hz), 151.99 (dt, C-1, JCP 198.2, JCF 3.1 Hz),
3JCP 7.6 Hz), 62.69 (d, C-i, JCP 6.4 Hz), 36.08 (d, C-6, JCP 8.0 Hz),
3
1
3
3
4
142.91 (m, C-4), 141.99 (d, C-5, JCP 2.6 Hz), 119.35 (qt, C-8, JCF
286.1, 2JCF 39.9, 4JCP 2.0 Hz), 113.09 (tq, C-7, 1JCF 253.9, 2JCF 39.9, 3JCP
3.7 Hz), 73.55 (d, C-9, 3JCP 5.6 Hz), 62.52 (d, C-i, 2JCP 6.1 Hz), 57.04
(dq, C-6, 2JCP 10.1, 4JCF 0.9 Hz), 54.37 (d, C-3, 3JCP 13.3 Hz), 16.45 (d,
C-j, JCP 6.5 Hz). 1H NMR(CDCl3) d: 6.78 (dd, 1H, JHH 4.7, JHH
3.2 Hz), 6.76 (dd, 1H, 3JHH 4.7, 3JHH 2.9 Hz), 4.06 (m, 1H), 3.96 (dq,
4H, 3JHP 8.3, 3JHH 3.7 Hz), 3.82 (m, 1H), 2.02 (dd, 2H, 2JHH 34.7, 3JHH
6.9 Hz), 1.21 (t, 6H, JHH 6.9 Hz). MS (EI) m/e = 346 ([M]+, 15%),
302(17), 269(25), 250(63), 227(100), 209(8), 189(6), 171(18);
HRMS m/e ([M]+) calculated for C13H16F5O3P 346.07572, found
346.07541.
28.29 (dq, C-3, JCP 13.0, JCF 2.2 Hz), 22.48 (d, C-9, JCP 1.1 Hz),
16.50 (d, C-j, 3JCP 6.7 Hz). 1H NMR(CDCl3) d: 5.32(m, 1H), 4.06 (dq,
4H, 3JHH 7.1, 3JHP 9.5 Hz), 2.79 (d, 2H, 3JHP 8.3 Hz), 2.73 (m, 2H), 1.66
(s, 3H), 1.28 (t, 6H, 3JHH 7.1 Hz). MS (EI) m/e = 347 ([M–H]+, 100%),
327(45), 319(20), 299(10), 291(55), 271(58), 251(5), 201(23),
191(22), 141(38); HRMS m/e ([M–H]+) calculated for C13H17F5O3P
347.08355, found 347.08418.
3
3
3
3
Diethyl 6-methyl-2-(trifluoromethyl)cyclohexa-1,4-dien-1-ylpho-
sphonate (9a). Bp: 64–66 8C (0.1 mm Hg). Yield: 74%. 31P
4
NMR(CDCl3) d: 15.24 (q, JPF 3.0 Hz). 19F NMR(CDCl3) d: ꢀ63.97
(d, 3F, 4JFP 3.0 Hz). 13C NMR(CDCl3) d: 156.42 (qd, C-2, 2JCF 35.9, 2JCP
10.1 Hz), 148.52 (dq, C-1, 1JCP 197.1, 3JCF 4.4 Hz), 142.93 (d, C-5, 3JCP
6.4 Hz), 142.03 (m, C-4, 4JCP 2.5 Hz), 122.77 (qd, C-7, 1JCF 270.8, 3JCP
Diethyl 4-methyl-2-(trifluoromethyl)cyclohexa-1,4-dien-1-ylpho-
sphonate (7a). Bp: 71–72 8C (0.1 mm Hg). Yield: 88% (together with
isomer 8a). Content in the mixture 61 mol%. 31P NMR(CDCl3) d:
14.90 (q, 4JPF 3.5 Hz). 19F NMR(CDCl3) d: ꢀ63.62 (d, 3F, 4JFP 2.9 Hz).
3
3
2
4.6 Hz), 73.71 (dq, C-3, JCP 5.6, JCF 1.0 Hz), 62.58 (d, C-i, JCP
3
2
4
6.2 Hz), 56.41 (d, C-8, JCP 10.4 Hz), 53.56 (dq, C-6, JCP 13.1, JCF
1.9 Hz), 16.47 (d, C-j, JCP 6.6 Hz). 1H NMR(CDCl3) d: 5.67 (m, 1H),
13C NMR(CDCl3) d: 136.36 (qd, C-2, JCF 31.6, JCP 4.7 Hz), 131.29
2
2
3
1
3
1
3
3
3
3
(dq, C-1, JCP 178.1, JCF 3.3 Hz), 122.73 (qd, C-7, JCF 275.7, JCP
10.6 Hz), 117.20 (d, C-5, 3JCP 10.2 Hz), 115.82 (m, C-4), 62.63 (d, C-i,
2JCP 6.4 Hz), 31.43 (dq, C-3, 3JCP 13.0, 3JCF 3.1 Hz), 31.42 (d, C-6, 2JCP
8.5 Hz), 22.48 (s, C-8), 16.43 (d, C-j, 3JCP 6.5 Hz). 1H NMR(CDCl3) d:
5.26 (m, 1H), 3.98 (dq, 4H, 3JHH 7.1, 3JHP 8.6 Hz), 2.94 (m, 2H), 2.85
5.59(m, 1H), 4.03 (dq, 4H, JHH 7.1, JHP 7.3 Hz), 3.32 (dd, 2H, JHH
9.3, 4JHP 5.4 Hz), 2.82 (m, 1H), 1.23 (t, 6H, 3JHH 6.9 Hz) 1.10 (d, 3H,
3JHH 6.9 Hz). MS (EI) m/e = 297 ([M–H]+, 90%), 277(100), 269(20),
249(23), 241(80), 221(85), 201(63), 187(22), 173(15), 141(60);
HRMS m/e ([M–H]+) calculated for C12H17F3O3P 297.08674, found
297.08679.
3
(m, 2H), 1.56 (s, 3H), 1.19 (t, 6H, JHH 7.1 Hz). MS (EI) m/e = 297
([M–H]+, 85%), 277(62), 269(10), 249(20), 241(30), 221(100),
201(80), 141(55); HRMS m/e ([M–H]+) calculated for C12H17F3O3P
297.08674, found 297.08685.
Diethyl 5-methyl-2-(trifluoromethyl)cyclohexa-1,4-dien-1-ylpho-
sphonate (8a). Bp: 71–72 8C (0.1 mm Hg). Yield: 88% (together
with isomer 7a). Content in the mixture 39 mol%. 31P NMR(CDCl3)
Diethyl
6-methyl-2-(pentafluoroethyl)cyclohexa-1,4-dien-1-
ylphosphonate (9b). Bp: 68–70 8C (0.1 mm Hg). Yield: 67%. 31P
NMR(CDCl3) d: 15.42 (q, 4JPF 4.0 Hz). 19F NMR(CDCl3) d: ꢀ81.95 (t,
3F, 3JFF 2.2 Hz), ꢀ110.82 (m, 2F). 13C NMR(CDCl3) d: 140.74 (dt, C-1,
1JCP 178.2, 3JCF 3.4 Hz), 135.92 (td, C-2, 2JCF 22.5, 2JCP 4.8 Hz), 131.13
(d, C-5, 3JCP 9.5 Hz), 121.08 (m, C-4), 119.34 (qt, C-8, 1JCF 288.4, 2JCF
37.7, 4JCP 1.6 Hz), 113.52 (tq, C-7, 1JCF 259.6, 2JCF 38.5, 3JCP 7.4 Hz),
62.65 (d, C-i, 2JCP 5.6 Hz), 35.97 (d, C-6, 2JCP 8.3 Hz), 27.29 (dq, C-3,
4
4
d: 14.67 (q, JPF 3.2 Hz). 19F NMR(CDCl3) d: ꢀ63.33 (d, 3F, JFP
2.0 Hz). 13C NMR(CDCl3) d: 136.67 (qd, C-2, JCF 31.5, JCP 3.7 Hz),
131.09 (dq, C-1, 1JCP 178.0, 3JCF 3.3 Hz), 130.20 (d, C-5, 3JCP 9.5 Hz),
128.89 (m, C-4), 122.86 (qd, C-7, 1JCF 275.7, 3JCP 10.5 Hz), 62.66 (d,
2
2
3JCP 11.9, 3JCF 2.6 Hz), 21.46 (m, C-9), 16.53 (d, C-j, 3JCP 6.7 Hz). 1
H
NMR(CDCl3) d: 5.80 (m, 1H), 5.65 (m, 1H), 4.09 (dq, 4H, 3JHH 7.3, 3JHP
7.1 Hz), 3.45 (d, 2H, 3JHH 10.1 Hz), 2.86 (m, 1H, 3JHP 3.7 Hz), 1.27 (t,
2
2
3
C-i, JCP 6.4 Hz), 34.77 (d, C-6, JCP 8.1 Hz), 28.06 (dq, C-3, JCP
3
4
3
3
12.9, JCF 3.4 Hz), 22.47 (d, C-8, JCP 2.5 Hz), 16.43 (d, C-j,
3JCP 6.5 Hz). 1H NMR(CDCl3) d: 5.23 (m, 1H), 4.02 (dq, 4H,
6H, JHH 7.1 Hz) 1.14 (d, 3H, JHH 6.6 Hz). MS (EI) m/e = 347 ([M–
H]+, 100%), 327(71), 319(30), 291(80), 271(68), 251(17), 201(21),
191(36), 173(15), 141(42); HRMS m/e ([M–H]+) calculated for
3JHH 6.9, JHP 8.3 Hz), 2.73 (d, 2H, JHP 8.6 Hz), 2.67 (m, 2H), 1.56
3
3
(s, 3H), 1.20 (t, 6H, JHH 7.1 Hz). MS (EI) m/e = 297 ([M–H]+, 85%),
C
13H17F5O3P 347.08355, found 347.08413.
3
277(62), 269(10), 249(20), 241(30), 221(100), 201(80), 141(55);
HRMS m/e ([M–H]+) calculated for C12H17F3O3P 297.08674, found
297.08685.
Diethyl 3,6-dimethyl-2-(trifluoromethyl)cyclohexa-1,4-dien-1-
ylphosphonate (10a). Bp: 74–75 8C (0.1 mm Hg). Yield: 65%. 31P
NMR(CDCl3) d: 15.22 (q, 4JPF 3.0 Hz). 19F NMR(CDCl3) d: ꢀ60.98 (d,
4
2
2
Diethyl
4-methyl-2-(pentafluoroethyl)cyclohexa-1,4-dien-1-
3F, JFP 3.0 Hz). 13C NMR(CDCl3) d: 142.84 (qd, C-2, JCF 29.6, JCP
ylphosphonate (7b). Bp: 81–82 8C (0.1 mm Hg). Yield: 78% (together
with isomer 8b). Content in the mixture 56 mol%. 31P NMR(CDCl3)
d: 15.21 (q, 4JPF 4.0 Hz). 19F NMR(CDCl3) d: ꢀ82.26 (t, 3F, 3JFF 2.2 Hz),
ꢀ111.28 (m, 2F). 13C NMR(CDCl3) d: 134.76 (td, C-2, 2JCF 22.3, 2JCP
4.2, 3JCF 0.6 Hz), 134.53 (dt, C-1, 1JCP 180.0, 3JCF 3.3 Hz), 119.64 (qt,
2.6 Hz), 138.49 (dq, C-1, 1JCP 173.5, 3JCF 3.6 Hz), 130.01 (d, C-5, 3JCP
9.8 Hz), 128.73(dq, C-4, JCP 1.9, JCF 0.8 Hz), 123.07 (qd, C-7, JCF
4
4
1
3
2
2
277.0, JCP 10.1 Hz), 62.60 (d, C-i, JCP 6.4 Hz), 35.54 (d, C-6, JCP
9.0 Hz), 33.10 (dq, C-3 3JCP 12.3, 3JCF 3.0 Hz), 24.01 (m, C-9), 23.25
(d, C-8, JCP 3.3 Hz), 16.51 (d, C-j, JCP 6.7 Hz). 1H NMR(CDCl3) d:
3
3
1
2
4
3
C-8, JCF 288.4, JCF 38.6, JCP 2.0 Hz), 117.36 (d, C-5, JCP 10.1 Hz),
115.96 (qd, C-4, 4JCP 1.7, 3JCP 1.2 Hz), 113.51 (tq, C-7, 1JCF 255.9, 2JCF
5.71 (m, 1H), 5.67 (m, 1H), 4.05 (dq, 4H, 3JHH 7.6, 3JHP 7.1 Hz), 3.29
3
3
(m, 1H), 3.05 (m, 1H), 1.26 (t, 6H, JHH 7.1 Hz), 1.21 (d, 3H, JHH
7.3 Hz), 1.17 (d, 3H, 3JHH 7.1 Hz). MS (EI) m/e = 311 ([M–H]+, 10%),
297(100), 277(7), 241(10), 221(75), 201(70), 173(6), 155(22);
HRMS m/e ([M–H]+) calculated for C13H19F3O3P 311.10239, found
311.10240.
3
2
2
38.9, JCP 7.6 Hz), 62.67 (d, C-i, JCP 6.4 Hz), 33.63 (d, C-6, JCP
3
3
9.2 Hz), 31.76 (dq, C-3, JCP 13.0, JCF 2.2 Hz), 22.45 (s, C-9), 16.53
(d, C-j, JCP 6.7 Hz). 1H NMR(CDCl3) d: 5.36 (m, 1H), 4.10 (dq, 4H,
3
3JHH 7.1, 3JHP 10.3 Hz), 3.08 (m, 2H), 2.97 (m, 2H), 1.65 (s, 3H), 1.27
(t, 6H, JHH 7.1 Hz). MS (EI) m/e = 347 ([M–H]+, 100%), 327(45),
Diethyl 3-(trifluoromethyl)-7-oxabicyclo[2.2.1]hepta-2,5-dien-2-
ylphosphonate (11a). Bp: 74–75 8C (0.1 mm Hg). Yield: 90%. 31P
3
319(20), 299(10), 291(55), 271(58), 251(5), 201(23), 191(22),

484
S.N. Tverdomed et al. / Journal of Fluorine Chemistry 129 (2008) 478–485
4
NMR(CDCl3) d: 8.98 (q, JPF 4.2 Hz). 19F NMR(CDCl3) d: ꢀ63.66 (d,
0.8 Hz), 144.23 (d, C-5, 3JCP 3.0 Hz), 122.25 (qd, C-7, 1JCF 270.1, 3JCP
3.7 Hz), 96.72 (d C-6, JCP 14.0 Hz), 83.27 (dq, C-3, JCP 12.6, JCF
2.6 Hz), 62.98 (d, C-i, 2JCP 5.9 Hz), 16.51 (d, C-j, 3JCP 6.5 Hz), 16.44 (d,
3F, JFP 4.2 Hz). 13C NMR(CDCl3) d: 156.42 (qd, C-2, JCF 36.0, JCP
10.7 Hz), 150.45 (dq, C-1, JCP 203.2, JCF 4.6 Hz), 144.25 (m, C-4),
143.04(d, C-5, 3JCP 2.3 Hz), 122.21 (qd, C-7, 1JCF 268.4, 3JCP 4.6 Hz),
87.63 (d, C-6, JCP 13.8 Hz), 84.29 (dq, C-3, JCP 12.3, JCF 2.3 Hz),
63.13 (d, C-i, 2JCP 5.4 Hz), 16.46 (d, C-j, 3JCP 6.9 Hz). 1H NMR(CDCl3)
d: 7.07 (m, 2H), 5.67 (m, 1H), 5.52 (dd, 1H, 3JHH 3.7, 3JHP 3.4 Hz), 3.98
(dq, 4H, JHP 7.3, JHH 2.7 Hz), 1.95 (t, 6H, JHH 7.3 Hz). MS (EI) m/
e = 298 ([M]+, 2%), 272(5), 242(6), 229(25), 194(18), 189(20),
175(17), 157(5), 81(10), 68(100); HRMS m/e ([M]+) calculated for
4
2
2
2
3
4
1
3
3
3
C-8, JCP 6.5 Hz). 1H NMR(CDCl3) d: 7.07 (m, 1H), 6.89 (d, 1H, JHH
2
3
3
3
5.1 Hz), 5.46 (m, 1H), 4.06 (m, 4H), 1.85 (s, 3H), 1.25 (t, 6H, JHH
7.3 Hz). MS (ESI) m/e = 311 ([M–H]+, 8%), 263(5), 243(4), 221(2),
201(100), 173(4), 113(7), 93(2), 69(1); Anal. calculated for
3
3
3
C12H16F3O4P (312.23): C, 46.16; H, 5.17. Found: C, 46.05; H, 5.09%.
Diethyl 4-methyl-3-(trifluoromethyl)-7-oxabicyclo[2.2.1]hepta-
2,5-dien-2-ylphosphonate (14a). Bp: 69–70 8C (0.1 mm Hg). Yield:
82% (together with isomer 13a). Content in the mixture 34 mol%.
31P NMR(CDCl3) d: 9.30 (q, 4JPF 4.5 Hz). 19F NMR(CDCl3) d: ꢀ63.54
(d, 3F, 4JFP 4.6 Hz). 13C NMR(CDCl3) d: 156.90 (qd, C-2, 2JCF 35.4, 2JCP
8.2 Hz), 151.89 (dq, C-1, 1JCP 201.1, 3JCF 4.5 Hz), 146.21 (d, C-5, 3JCP
2.5 Hz), 145.56(d, C-4, 4JCP 0.7 Hz), 122.40 (qd, C-7, 1JCF 270.1, 3JCP
C
11H14F3O4P 298.05818, found 298.05679.
Diethyl 3-(pentafluoroethyl)-7-oxabicyclo[2.2.1]hepta-2,5-dien-
2-ylphosphonate (11b). Bp: 78–80 8C (0.1 mm Hg). Yield: 81%.
31P NMR(CDCl3) d: 9.10 (t, 4JPF 5.0 Hz). 19F NMR(CDCl3) d: ꢀ84.45 (t,
3F, 3JFF 3.0 Hz), ꢀ114.38 (m, 2F). 13C NMR(CDCl3) d: 155.34 (td, C-2,
2JCF 25.9, 2JCP 9.2 Hz), 153.77 (dt, C-1, 1JCP 203.1, 3JCF 3.4 Hz), 144.17
(m, C-4), 143.05 (d, C-5, 3JCP 1.6 Hz), 118.95 (qt, C-8, 1JCF 288.6, 2JCF
37.4, 4JCP 1.7 Hz), 112.74 (tq, C-7, 1JCF 252.8, 2JCF 41.4, 3JCP 3.6 Hz),
88.07 (d, C-6, JCP 14.1 Hz), 84.94 (dq, C-3, JCP 12.4, JCF 2.8 Hz),
63.12 (d, C-i, 2JCP 5.7 Hz), 16.48 (d, C-j, 3JCP 6.2 Hz). 1H NMR(CDCl3)
d: 7.15 (dd, 1H, JHH 5.1, JHH 2.2 Hz), 7.07 (dd, 1H, JHH 5.4, JHH
2.0 Hz), 5.75 (m, 1H), 5.57 (dd, 1H, JHH 3.7, JHP 2.5 Hz), 4.05 (dq,
4H, 3JHP 8.3, 3JHH 2.2 Hz), 1.26 (t, 6H, 3JHH 6.9 Hz). MS (EI) m/e = 348
([M]+, 1%), 320(10), 300(20), 272(5), 253(32), 225(58), 207(10),
183(8), 68(100); HRMS m/e ([M]+) calculated for C12H14F5O4P
348.05499, found 348.05560.
3
3
2
5.0 Hz), 93.82 (dq, C-3, JCP 12.9, JCF 1.4 Hz), 86.55 (dq, C-6, JCP
12.7, 4JCF 0.6 Hz), 63.05 (d, C-i, 2JCP 5.7 Hz), 16.72 (s, C-8), 16.50 (d,
C-j, JCP 6.5 Hz). 1H NMR(CDCl3) d: 7.10 (m, 1H), 6.86 (d, 1H, JHH
6.0 Hz), 5.61(m, 1H), 4.01 (m, 4H), 1.75 (s, 3H), 1.24 (t, 6H, JHH
7.3 Hz). MS (ESI) m/e = 311 ([M–H]+, 8%), 263(5), 243(4), 221(2),
3
3
2
3
3
3
3
3
3
3
201(100), 173(4), 113(7), 93(2), 69(1); Anal. calculated for
3
3
C12H16F3O4P (312.23): C, 46.16; H, 5.17. Found: C, 46.05; H, 5.09%.
Diethyl 1-methyl-3-(pentafluoroethyl)-7-oxabicyclo[2.2.1]hepta-
2,5-dien-2-ylphosphonate (13b). Bp: 79–80 8C (0.1 mm Hg). Yield:
73% (together with isomer 14b). Content in the mixture 86 mol%.
31P NMR(CDCl3) d: 9.43 (t, 4JPF 4.9 Hz). 19F NMR(CDCl3) d: ꢀ84.30 (t,
3F, 3JFF 3.0 Hz), ꢀ112.92 (m, 2F). 13C NMR(CDCl3) d: 157.19 (td, C-2,
Diethyl
12-(trifluoromethyl)-9,10-dihydro-9,10-ethenoanthra-
2
1
3
cen-11-ylphosphonate (12a). Crude product was purified by
2JCF 25.9, JCP 10.4 Hz), 154.53 (dt, C-1, JCP 201.6, JCF 3.1 Hz),
3
1
recrystallization from benzene/hexane 1:4, colorless crystals
147.19 (m, C-4), 144.21 (d, C-5, JCP 2.2 Hz), 118.83 (qt, C-8, JCF
286.9, 2JCF 36.1, 4JCP 2.3 Hz), 112.61 (tq, C-7, 1JCF 253.4, 2JCF 39.4, 3JCP
4.0 Hz), 97.06 (d, C-6, 2JCP 14.9 Hz), 83.80 (m, C-3), 16.50 (d, C-j, 3JCP
6.4 Hz), 16.45 (d, C-9, 3JCP 6.5 Hz). 1H NMR(CDCl3) d: 7.03 (m, 1H),
6.90 (d, 1H, JHH 5.6 Hz), 5.45 (m, 1H), 4.11 (m, 4H), 1.88 (s, 3H),
1.27 (t, 6H, 3JHH 7.3 Hz). MS (ESI) m/e = 361 ([M–H]+, 10%), 339(8),
(Yield: 82%, mp 54 8C). 31P NMR(CDCl3) d: 12.44 (q, JPF 4.5 Hz).
4
19F NMR(CDCl3) d: ꢀ62.74 (d, 3F, JFP 4.3 Hz). 13C NMR(CDCl3) d:
4
2
2
1
151.68 (qd, C-2, JCF 35.4, JCP 7.1 Hz), 145.00 (dq, C-1, JCP 185.9,
3JCF 4.3 Hz), 144.03 (m, C-4,40), 144.32(d, C-5,50, 3JCP 2.6 Hz), 128.80
3
4
(s, C-8,80), 126.10 (d, C-11,110, JCP 4.2 Hz), 124.38(s, C-10,100),
124.17(s, C-9,90), 123.16(qd, C-7, 1JCF 272.6, 3JCP 6.7 Hz), 63.10 (d, C-
i, 2JCP 5.8 Hz), 55.13 (d, C-6, 2JCP 8.7 Hz), 52.49 (dq, C-3, 3JCP 10.0, 3JCF
311(6), 251(100), 201(4), 141(3), 119(5), 87(3); Anal. calculated for
C13H16F5O4P (362.24): C, 43.11; H, 4.45. Found: C, 43.01; H, 4.28%.
2.8 Hz), 16.50 (d, C-j, JCP 6.8 Hz). 1H NMR(CDCl3) d: 7.46 (m, 4H),
Diethyl 4-methyl-3-(pentafluoroethyl)-7-oxabicyclo[2.2.1]hepta-
3
7.07 (m, 4H), 5.87 (d, 1H, 3JHP 9.2 Hz), 5.52 (d, 1H, 4JHP 4.9 Hz), 4.01
2,5-dien-2-ylphosphonate (14b). Bp: 79–80 8C (0.1 mm Hg). Yield:
73% (together with isomer 14a). Content in the mixture 14 mol%.
31P NMR(CDCl3) d: 9.32 (t, 4JPF 4.0 Hz). 19F NMR(CDCl3) d: ꢀ83.79 (t,
3F, 3JFF 3.5 Hz), ꢀ111.24 (m, 2F). 13C NMR(CDCl3) d: 157.15 (td, C-2,
3
3
3
(dq, 4H, JHP 6.6, JHH 2.6 Hz), 1.24 (t, 6H, JHH 7.0 Hz). MS (EI) m/
e = 408 ([M]+, 70%), 388(65), 340(7), 270(62), 251(64), 202(44),
178(100), 152(3), 126(2), 109(8); HRMS m/e ([M]+) calculated for
21H20F3O3P 408.11022, found 408.11138.
Diethyl 12-(pentafluoroethyl)-9,10-dihydro-9,10-ethenoanthra-
2
1
3
C
2JCF 25.7, JCP 10.1 Hz), 154.27 (dt, C-1, JCP 199.1, JCF 3.1 Hz),
3
1
146.40 (d, C-5, JCP 1.9 Hz), 145.29 (m, C-4), 118.71 (qt, C-8, JCF
287.6, 2JCF 36.7, 4JCP 2.0 Hz), 112.73 (tq, C-7, 1JCF 254.3, 2JCF 40.3, 3JCP
3.9 Hz), 95.05 (dt, C-3, JCP 12.6, JCF 4.5 Hz), 86.77 (dt, C-6, JCP
12.6, 4JCF 1.1 Hz), 63.07 (d, C-i, 2JCP 5.3 Hz), 16.84 (s, C-9), 16.52 (d,
C-j, JCP 6.4 Hz). 1H NMR(CDCl3) d: 7.11 (m, 1H), 6.84 (d, 1H, JHH
cen-11-ylphosphonate (12b). Crude compound was purified by
flash column chromatography (EtOAc/hexane 1:6 as eluent),
colorless oil (Yield: 76%). Rf (EtOAc/hexane 1:6) 0.38. 31P
3
3
2
NMR(CDCl3) d: 12.34 (t, JPF 4.5 Hz). 19F NMR(CDCl3) d: ꢀ83.65
4
3
3
(t, 3F, 3JFF 2.6 Hz), ꢀ112.77 (m, 2F). 13C NMR(CDCl3) d: 150.59 (td, C-
5.6 Hz), 5.62 (m, 1H), 4.04 (m, 4H), 1.76 (s, 3H), 1.27 (t, 6H, JHH
7.3 Hz). MS (ESI) m/e = 361 ([M–H]+, 10%), 339(8), 311(6),
3
2
2
1
3
2, JCF 24.8, JCP 7.4 Hz), 148.57 (dt, C-1, JCP 186.7, JCF 3.7 Hz),
144.01 (m, C-4,40), 143.17 (d, C-5,50, 3JCP 2.5 Hz), 126.14 (s, C-9,90),
124.27 (m, C-12,120), 124.16 (m, C-10,100, 11,110), 119.16 (qt, C-8,
251(100), 201(4), 141(3), 119(5), 87(3); Anal. calculated for
C13H16F5O4P (362.24): C, 43.11; H, 4.45. Found: C, 43.01; H, 4.28%.
1JCF 287.8, JCF 38.6 Hz), 113.47 (tq, C-7, JCF 254.8, JCF 39.5, JCP
2
1
2
3
4.3 Hz), 63.07 (d, C-i, 2JCP 6.5 Hz), 55.94 (d, C-6, 2JCP 8.2 Hz), 53.20
3.3. X-ray structural determination of 12a
(dq, C-3, JCP 10.6, JCF 5.6 Hz), 16.45 (d, C-j, JCP 6.4 Hz). 1H
NMR(CDCl3) d: 7.41 (m, 4H), 7.04 (m, 4H), 5.92 (d, 1H, 3JHP 9.8 Hz),
5.51 (d, 1H, 4JHP 5.4 Hz), 4.00 (dq, 4H, 3JHP 7.8, 3JHH 2.5 Hz), 1.22 (t,
3
3
3
The single crystals (colorless prisms) of 12a suitable for X-ray
analysis were obtained from benzene/hexane; C21H20F3O3PC6H6,
Mr = 486.45, crystal size 1.0 mm ꢃ 0.9 mm ꢃ 0.8 mm, triclinic P1
with a = 996.70(10), b = 997.70(10), c = 1399.50(2) pm, a =
89.380(10), b = 75.650(10), d = 66.530(10)8; V = 1.2306(2) nm3,
Z = 2, Dcalc = 1.313 Mg/m3, mꢀ=30.161 mmꢀ1, difference electron
6H, JHH 7.3 Hz). MS (EI) m/e = 458 ([M]+, 38%), 438(10), 347(22),
3
320(17), 291(21), 251(15), 202(19), 178(100), 141(12); HRMS m/e
([M]+) calculated for C22H20F5O3P 458.10702, found 458.10808.
Diethyl 1-methyl-3-(trifluoromethyl)-7-oxabicyclo[2.2.1]hepta-
2,5-dien-2-ylphosphonate (13a). Bp: 69–70 8C (0.1 mm Hg). Yield:
82% (together with isomer 14a). Content in the mixture 66 mol%.
31P NMR(CDCl3) d: 9.45 (q, 4JPF 4.0 Hz). 19F NMR(CDCl3) d: ꢀ62.13
(d, 3F, 4JFP 4.0 Hz). 13C NMR(CDCl3) d: 158.67 (qd, C-2, 2JCF 37.7, 2JCP
9.3 Hz), 151.35 (dq, C-1, 1JCP 198.0, 3JCF 5.0 Hz), 147.32(d, C-4, 4JCP
˚
density 0.384 and ꢀ0.390 e A was performed at 203(2) K on a
Siemens P4 diffractometer using graphite monochromated Mo Ka
radiation (l = 71:073 pm) and a the low temperature device LT2,
index range ꢀ12 ꢄ h ꢄ 12; ꢀ12 ꢄ k ꢄ 12; ꢀ17 ꢄ l ꢄ 18, 2u-range
2.57–27.508, reflections measured 11260, unique reflections 5627

S.N. Tverdomed et al. / Journal of Fluorine Chemistry 129 (2008) 478–485
485
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Acknowledgements
The authors thank the Deutschen Forschungsgemeinschaft
(DFG Ro 362/33-1) for financial support of this work. We also
express our gratitude to Dr. T. Duelcks (University of Bremen) and
D. Kemken (University of Bremen) for recording the MS- and
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