Synthesis and cycloaddition reactions of polyfluorinated imines

Article abstract of DOI:10.1070/MC2006v016n03ABEH002296

Imines 3-6 containing fluorinated N-substituents were prepared by reactions of fluorinated sulfinylamines 1, 2 with hexafluoroacetone and ethyl trifluoropyruvate; trifluoromethylsulfonylimines 3, 5 exothermically reacted with dienes at -50°C to form cyclo

Full text of DOI:10.1070/MC2006v016n03ABEH002296

Mendeleev
Communications
Mendeleev Commun., 2006, 16(3), 184–186
Synthesis and cycloaddition reactions of polyfluorinated imines
Sergei V. Moiseev,a Valerii M. Goncharov,a Georgy V. Zatonsky,b Viktor F. Cherstkovc and Nikolai V. Vasil’ev*a
a Military Academy of Radiation, Chemical and Biological Defense, 105005 Moscow, Russian Federation.
E-mail: Nikolai-vasilev@mail.ru
b N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
E-mail: Zatonsk@ioc.ac.ru
c A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 495 135 5085; e-mail: SRS@ineos.ac.ru
DOI: 10.1070/MC2006v016n03ABEH002296
Imines 3–6 containing fluorinated N-substituents were prepared by reactions of fluorinated sulfinylamines 1, 2 with hexafluoro-
acetone and ethyl trifluoropyruvate; trifluoromethylsulfonylimines 3, 5 exothermically reacted with dienes at –50 °C to form
cycloaddition products 7, 9 and D-aminoalkylation products 8, 10.
Polyfluorinated imines are precursors for the preparation of
fluorinated nitrogen-containing heterocyclic compounds by cyclo-
addition reactions.1,2 However, methods for the synthesis of
imines with fluorinated N-substituents have been inadequately
developed and some of these compounds are preparatively
unavailable.2,3 In particular, highly electrophilic N-perfluoro-
alkylsulfonylimines of fluorinated ketones were obtained only
by the deoxygenation of corresponding oxaziridines.4
The aim of this study was to prepare imines with fluorinated
N-substituents. As parent compounds, we used available tri-
fluoromethylsulfonylsulfinylamine5 1 and pentafluorophenyl-
sulfinylamine6 2 because non-fluorinated sulfinylamines were
successfully used previously for the synthesis of hexafluoro-
acetone arylimines7 and 2-iminotrifluoropropionates.8 We believed
that the enhanced electrophilicity of these reagents will hinder
reactions with polyfluorinated carbonyl compounds. We found
that the reactions of compounds 1, 2 with ethyl trifluoropyruvate
occurred at 110 °C with the elimination of SO2 and the formation
of imines 3, 4 in 35 and 61% yields, respectively. Analogous
reactions with hexafluoroacetone did not occur even at higher
temperatures (to 200 °C). Imines 5, 6 were prepared in 69 and
11% yields, respectively, at 110 °C only under conditions of
CsF catalysis (Scheme 1).† In the latter case, the conversion
of reagents did not increase with temperature (»150 °C); this
fact is indicative of an equilibrium character of this process.
The reactions of sulfinylamines 1, 2 with trifluoroacetyl
chloride did not result in the formation of corresponding imidoyl
halides (Scheme 2) even with the use of CsF as a catalyst at
high temperatures.
Trifluoropyruvate N-trifluoromethylsulfonimine 3 is an
extremely electrophilic compound, which emits smoke in air
and exothermically reacts with donor dienes even at –40 °C.
184 Mendeleev Commun. 2006

Mendeleev Commun., 2006, 16(3), 184–186
CF3
CF3
CF3
R
CF3
R
110 °C
– SO2
CF3SO2N
+
RFN SO
O
RFN
O
5
1, 2
3 RF = CF3SO2, R = C(O)OEt
4 RF = C6F5, R = C(O)OEt
5 RF = CF3SO2, R = CF3
6 RF = C6F5, R = CF3
SO2CF3
CF3
CF3
NHSO2CF3
CF3
O
N
Scheme 1
CF3
8
7
However, these reactions gave ambiguous results. Imine 5 also
exoterically reacts with dienes at –50 °C.‡ The reaction of com-
pound 5 with cyclopentadiene occurred unambiguously with the
Scheme 3
formation of [4+2]-cycloaddition product, azabicycloheptene 7,
in 69% yield. In contrast, the interaction of compound 5 with
furan resulted in the release of only D-sulfoimidoalkylation pro-
duct 8 (Scheme 3).
It is of interest that the reaction of compound 5 with 2,3-di-
methylbutadiene occurred ambiguously with the simultaneous
formation of both cycloaddition product 9 and ene synthesis
product 10 (Scheme 4).
CF3
110–150 °C, CsF
CF3
Hal
+
RFN SO
O
RFN
Cl
1, 2
Scheme 2
†
1
The H and 19F NMR spectra were measured on a Bruker DRX-500
with operating frequencies of 500.1 and 470.6 MHz, respectively. The
chemical shifts (d/ppm) were measured using TMS (1H) and CFCl3 (19F)
as external standards. The mass spectra were measured on an HP 5890
II Series gas chromatograph with an HP 5972A MSD mass selective
detector. Commercial reagents and solvents were prepared in accordance
with well-known procedures.9
CF3
CF3SO2N
CF3
5
Synthesis of polyfluorinated ketone imines 3–6 (general procedure).
The mixture of a corresponding sulfinylamine (15.0 mmol) and ethyl
trifluoropyruvate (2.3 g, 15.5 mmol) for imines 3, 4 or hexafluoroacetone
(4.9 g, 29.5 mmol) and CsF (0.2 g) for imines 5, 6 was heated (a) (com-
pounds 3, 4) for 13 h at 110 °C and cooled to 20 °C; the reaction mixture
was fractionated in a vacuum or (b) (compounds 5, 6) for 20 h at 110 °C
in a sealed glass ampule and cooled to –78 °C; volatile components were
removed on heating to 20 °C, and the residue was fractionated.
For 3: yield, 35%; bp 38–39 °C (15 Torr); nD20 1.3763. 1H NMR, d:
1.45 (t, 3H, Me, J 7.0 Hz), 4.51 (q, 2H, CH2, J 7.0 Hz). 19F NMR, d:
–69.73 (br. s, 3F, CF3), –77.02 (s, 3F, CF3SO2). Found (%): C, 24.17;
H, 1.88; N, 4.87. Calc. for C6H5F6NO4S (%): C, 23.92; H, 1.66; N, 4.65.
For 4: yield, 61%; bp 79–81 °C (13 Torr); nD20 1.4189. 1H NMR, d:
1.37 (t, 3H, Me, J 7.0 Hz), 4.42 (q, 2H, CH2, J 7.0 Hz). 19F NMR, d:
–69.72 (s, 3F, CF3), –149.75 (d, 2F, C6F5, J 21.0 Hz), –156.84 (t, 1F,
C6F5, J 21.0 Hz), –161.85 (t, 2F, C6F5, J 21.0 Hz). Found (%): C, 39.94;
H, 1.63; N, 4.37. Calc. for C11H5F8NO2 (%): C, 39.40; H, 1.49; N, 4.18.
MS, m/z (%): 335 [M]+ (52), 262 (100), 193 (12), 69 (48).
SO2CF3
CF3
N
+
CH2CNHSO2CF3
CF3
CF3
CF3
9
10
Scheme 4
The reaction with norbornadiene gave a complex mixture
of products even at –40 °C. Compound 11 was identified by
chromato-mass spectrometry. This compound can result from
the oxidative dehydrogenation of diethyl ether (in which the
reaction was performed) followed by the [2+2]-cycloaddition of
vinyl ethyl ether (Scheme 5).
CF3
CF3
Et2O
For 5 (data for compound 5 are consistent with previously reported
data4): yield, 69%; bp 72–73 °C. nD20 1.3091. 19F NMR, d: –67.79 (br. s,
6F, CF3), –77.06 (s, 3F, CF3SO2). Found (%): C, 16.37; N, 4.82. Calc.
for C4F9NO2S (%): C, 16.16; N, 4.71.
+
EtOCH=CH2
CF3SO2NHCH
CF3
CF3SO2N
CF3
5
5
For 6: yield 11%; bp 32–33 °C (11 Torr). nD20 1.3789. 19F NMR, d:
–67.86 (s, 3F, CF3), –70.00 (s, 3F, CF3), –150.53 (d, 2F, C6F5, J 21.0 Hz),
–156.98 (t, 1F, C6F5, J 21.0 Hz), –161.56 (t, 2F, C6F5, J 21.0 Hz). Found
(%): C, 32.75; N, 4.37. Calc. for C9F11N (%): C, 32.62; N, 4.23.
H
H
EtO
H
N
CF3
CF3
‡
Reactions of imine 5 with dienes (general procedure). Imine 5 (0.8 g,
CF3O2S
2.7 mmol) was added to a solution (5.0 mmol) of a corresponding diene
in 5 ml of dry diethyl ether at –50 °C with stirring; next, the mixture was
slowly warmed to room temperature. The residue was fractionated in a
vacuum for compounds 7–12.
11
Scheme 5
For 7: yield, 69%; bp 100 °C (10 Torr); nD20 1.3948. 1H NMR, d: 1.68
and 3.01 (2H, CH2, AB-spectrum, JAB –9.0 Hz), 4.72 (s, 1H, CH), 4.89
(s, 1H, CH), 6.51 (br. s, 1H, CH), 6.82 (br. s, 1H, CH). 19F NMR, d:
–60.44 (br. s, 3F, CF3), –69.38 (br. s, 3F, CF3), –76.37 (q, 3F, CF3SO2,
J 6.0 Hz). Found (%): C, 29.91; H, 1.81; N, 3.94. Calc. for C9H6F9NO2S
(%): C, 29.75; H, 1.65; N, 3.85.
Thus, the method developed for the synthesis of imines with
fluorinated substituents at the nitrogen atom considerably improves
the availability of these compounds. Trifluoromethylsulfonyl-
imines 3, 5 exhibit extraordinary electrophilicity, which manifests
itself in reactions with dienes and diethyl ether. This was sup-
ported by extremely low LUMO and HOMO energies of imines 3
(–0.067 and –12.446 eV) and 5 (0.140 and –13.184 eV) ab initio
calculated using the 3–21G basis set.
For 8: yield, 41%; bp 88 °C (12 Torr); nD20 1.3801. H NMR, d: 6.01
1
(br. s, 1H, NH), 6.51 (s, 1H, CH), 6.85 (s, 1H, CH), 7.60 (s, 1H, CH).
19F NMR, d: –72.21 (m, 6F, CF3), –75.76 (m, 3F, CF3SO2). Found (%):
C, 26.49; H, 1.18; N, 3.99. Calc. for C8H4F9NO3S (%): C, 26.30; H, 1.09;
N, 3.83.
References
Mixture of 9 + 10, bp 58 °C (1 Torr).
1
1 D. L. Boger and S. M. Weinreb, Hetero Diels–Alder Methodology in
Organic Synthesis, Academic Press, San Diego, 1987.
2 A. V. Fokin, A. F. Kolomiets and N. V. Vasil’ev, Usp. Khim, 1984, 53,
398 (Russ. Chem. Rev., 1984, 53, 238).
3 S. N. Osipov, A. F. Kolomiets and A. V. Fokin, Usp. Khim., 1992, 61,
1457 (Russ. Chem. Rev., 1992, 61, 798).
For 9: H NMR, d: 1.83 (br. s, 6H, Me), 2.78 (br. s, 2H, CH2), 3.59
(br. s, 2H, CH2). 19F NMR, d: –66.08 (k, 3F, CF3, J 9.0 Hz), –66.80 (k,
3F, CF3, J 9.0 Hz), –76.45 (m, 3F, CF3SO2).
1
For 10: H NMR, d: 2.01 (s, 3H, Me), 3.23 (br. s, 2H, CH2), 5.14 (s,
1H, CH2), 5.19 (s, 1H, CH2), 5.32 (s, 1H, CH2), 5.53 (s, 1H, CH2), 5.89
(br. s, 1H, NH). 19F NMR, d: –70.22 (m, 6F, CF3), –74.23 (m, 3F,
CF3SO2).
4 V. A. Petrov, T. E. Mlsna and D. D. DesMarteau, J. Fluorine Chem.,
1994, 68, 277.
For 11: MS, m/z (%): 369 [M]+ (26), 324 (5), 300 (83), 69 (100).
Mendeleev Commun. 2006 185

Mendeleev Commun., 2006, 16(3), 184–186
5 H. W. Roesky, G. Holtschneider and H. H. Giere, Z. Naturforsch., 1970,
25B, 252.
6 O. Glemser, S. P. van Halasz and U. Biermann, Inorg. Chem. Lett., 1968,
4, 591.
8 A. S. Golubev, A. F. Kolomiets and A. V. Fokin, Izv. Akad. Nauk SSSR,
Ser. Khim., 1990, 2461 (Bull. Acad. Sci. USSR, Div. Chem. Sci., 1990,
39, 2234).
9
A. J. Gordon and R. A. Ford, The Chemist’s Companion, Wiley–Interscience
,
7 Yu. V. Zeifman, E. G. Ter-Gabrielyan, D. P. Del’tsova and N. P. Gambaryan,
Izv. Akad. Nauk SSSR, Ser. Khim., 1979, 396 (Bull. Acad. Sci. USSR, Div.
Chem. Sci., 1979, 28, 366).
New York–London–Sydney–Toronto, 1972.
Received: 23rd December 2005; Com. 05/2638
186 Mendeleev Commun. 2006