Perfluoroalkylation of heterocumulenes with trimethyl(perfluoroalkyl)silanes in the presence of fluoride ions: Synthesis of perfluoroalkanesulfinyl amides from N-organylsulfinyl amines

Article abstract of DOI:10.1016/S0040-4039(02)00367-2

Trimethyl(perfluoroalkyl)silanes react in the presence of fluoride ions with N-organylsulfinylamines under mild conditions to give the corresponding perfluoroalkanesulfinyl amides in high yields.

Full text of DOI:10.1016/S0040-4039(02)00367-2

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 43 (2002) 3029–3031
Perfluoroalkylation of heterocumulenes with
trimethyl(perfluoroalkyl)silanes in the presence of fluoride ions:
synthesis of perfluoroalkanesulfinyl amides from
N-organylsulfinyl amines
Yurii L. Yagupolskii,a,* Nataliya V. Kirij,a Aleksey V. Shevchenko,a Wieland Tyrrab and
Dieter Naumannb
aInstitute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Murmanskaya St., UA-02094 Kiev 94, Ukraine
bInstitut fu¨r Anorganische Chemie, Universita¨t zu Ko¨ln, Greinstr. 6, D-50939 Cologne, Germany
Received 18 February 2002; accepted 22 February 2002
Abstract—Trimethyl(perfluoroalkyl)silanes react in the presence of fluoride ions with N-organylsulfinylamines under mild
conditions to give the corresponding perfluoroalkanesulfinyl amides in high yields. © 2002 Elsevier Science Ltd. All rights
reserved.
Trimethyl(trifluoromethyl)silane, Me3SiCF3, in the
presence of fluoride ion represents a source of tri-
fluoromethyl nucleophiles which recently enabled the
easy and convenient preparations of a variety of tri-
fluoromethyl-containing compounds and to synthesise
new fluorinated molecules.1–3 Its use in heterocumulene
transformations, namely isocyanates and isothio-
cyanates trifluoromethylation to give the corresponding
trifluoroacetamides and trifluorothioacetamides, was
recently demonstrated.4
with Me3SiRf (Rf=CF3, C2F5) in the presence of tetra-
methylammonium and cesium fluorides.
It must be mentioned that nucleophilic addition of
organometallic compounds (magnesium and lithium) to
ꢀNꢁSꢁO bonds was investigated comprehensively5
whereas, to the best of our knowledge, the interaction
of perfluoroalkylating reagents with this functional
group has not yet been investigated.
Perfluoroalkanesulfinyl amides are rarely documented
in literature; few compounds (mainly trifluoromethane-
sulfinyl amides) were obtained from reactions of amines
with corresponding sulfinyl chlorides.6 The latter are
difficult to obtain and, if commercially available, are
very expensive and therefore less suitable as starting
materials. Recently, solutions of sodium tri-
fluoromethanesulfinate and phosphoryl chloride were
In extension of our systematic studies on reactions of
perfluoroalkyl and pentafluorophenyl anions generated
from the corresponding fluor-containing tetra-
organosilanes in the presence of fluoride ions with
heterocumulenes of the type RꢀXꢁYꢁZ, with X=N, S;
Y=C, S; Z=O, S in different combinations, we now
report on the reactions of N-alkyl(aryl)sulfinylamines
Scheme 1.
Keywords: sulfinyl amines; perfluoroalkylsulfinyl amides; trifluoromethylation.
* Corresponding author. Fax: +38 044 5732643; e-mail: yurii@fluor-ukr.kiev.ua
0040-4039/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(02)00367-2

3030
Y. L. Yagupolskii et al. / Tetrahedron Letters 43 (2002) 3029–3031
used to prepare trifluoromethanesulfinyl amides from
higher perfluoroalkanesulfinic acids, we investigated the
principal possibility to synthesise so far unknown
amides of pentafluoroethanesulfinic acid. We found
that N-phenylsulfinyl amine 1d reacts with
trimethyl(pentafluoroethyl)silane in the presence of tet-
ramethylammonium fluoride under above mentioned
conditions to form N-phenylpentafluoroethanesulfinyl
amide 5d in 80% yield (Scheme 4).10
amines.7
We found that reactions of N-alkyl(aryl)sulfinyl amines
1a–f with Me3SiCF3 in the presence of tetra-
methylammonium fluoride in THF or monoglyme at
−60 to −50°C, followed by protolysis with aqueous
ammonium chloride, give the corresponding N-substi-
tuted trifluoromethanesulfinyl amides 2a–f in 75–85%
yield (Scheme 1).7
Besides tetramethylammonium fluoride, dry cesium
fluoride can also be used as a fluoride source in these
reactions that are best performed in propionitrile. In
contrast to ethers, temperature of the reaction mixture
had to be held at approximately −5°C for 6 hours as
demonstrated in the conversion of 1d into N-phenyl-
trifluoromethylsulfinyl amide 2d (80% yield).
Reaction intermediates in all cases are tetra-
methylammonium salts of the N-substituted tri-
fluoromethanesulfinyl amides which are directly formed
as colourless precipitates after mixing of the reagents.
These salts appear to be unstable but we succeeded in
the isolation and characterisation of the N-t-butyl sub-
stituted salt 3a (Scheme 2).9
Reaction conditions, yields and physical data of 2a–f
are summarised in Table 1. Analytic data of new or so
far not fully characterised compounds are given in Ref.
8.
The intermediate formation of salts such as 3a opens an
easy and convenient route to one-pot syntheses of
N,N-disubstituted trifluoromethanesulfinyl amides.
Methylation of the salt formed from phenylsulfinyl
amine with iodomethane gave N-phenyl-N-methyltri-
fluoromethanesulfinyl amide in 87% yield (Scheme 3).
Spectroscopic and analytical data are in good agree-
ment with reported ones.7
In summary, a concise and convenient method for the
synthesis of perfluoroalkanesulfinyl amides has been
developed starting from easily available substances such
as sulfinylamines via direct trifluoromethylation using
Me3SiRf (Rf=CF3, C2F5) in the presence of fluoride
sources.
In order to extend these reactions to derivatives of
Scheme 2.
Scheme 3.
Scheme 4.

Y. L. Yagupolskii et al. / Tetrahedron Letters 43 (2002) 3029–3031
3031
Table 1. Reactions of N-alkyl- and N-arylsulfinyl amines with Me3SiCF3 and [Me4N]F in glyme or THF
R
Reagents (mmol)
Solvent (mL)
Mopa
Yield (%)
Mp (°C),
RNSO
[Me4N]F
Me3SiCF3
bp (°C/Torr)
2a
2b
2c
2d
2e
2f
t-Bu
2.60
1.79
2.92
2.57
2.67
3.18
2.60
1.79
2.92
2.57
2.67
3.18
2.86
1.97
3.21
2.83
2.94
3.50
5
5
4
5
4
6
v.d.
s.
v.d.
s.
s.
s.
85
78
75
85
75
80
85/10
PhCHMe
c-C6H11
Ph
3-FC6H4
3-CF3C6H4
56 (oil7)
51–52/0.03
64 (647)
55
72
a Mop: method of purification; vacuum distillation (v.d.), sublimation (s.).
Acknowledgements
19F NMR (282.4 MHz, CD3CN): l −78.1 (s, 3F). Anal.
calcd for C7H12F3NOS: C, 39.06; H, 5.62; N, 6.51; F,
1
26.48. Found: C, 39.15; H, 5.60; N, 6.72; F, 26.41. 2e: H
Generous financial support of this work by the DFG
(grant 436 UKR 113) is gratefully acknowledged.
NMR (299.95 MHz, CDCl3): l 6.74–6.83 (m, 3H, ꢀAr
and 1H, ꢀNH), 7.19–7.28 (m, 1H, ꢀAr); 19F NMR (282.4
MHz, CDCl3): l −78.3 (s, 3F), −110.8 (broad s, 1F).
Anal. calcd for C7H5F4NOS: C, 37.01; H, 2.22; N, 6.17;
F, 33.45. Found: C, 37.34; H, 2.09; N, 6.41; F, 33.67. 2f:
1H NMR (299.95 MHz, CDCl3): l 6.75 (broad s, 1H,
ꢀNH), 7.27–7.34 (m, 2H, ꢀAr), 7.42–7.52 (m, 2H, ꢀAr);
References
1. Singh, R. P.; Shreeve, J. M. Tetrahedron 2000, 56, 7613–
7632.
2. Prakash, G. K. S.; Yudin, A. K. Chem. Rev. 1997, 97,
757–786.
3. (a) Furin, G. G. Zh. Org. Chem. 1997, 33, 1287–1319; (b)
Furin, G. G. Russ. J. Org. Chem. 1997, 33, 1209–1242.
4. Kirij, N. V.; Yagupolskii, Yu. L.; Petukh, N. V.; Tyrra,
W.; Naumann, D. Tetrahedron Lett. 2001, 42, 8181–8183.
5. Krauthausen, E. In Houben-Weyl Methoden der organis-
chen Chemie; Band E – 11/ Teil 1; Thieme: Stuttgart,
1985; pp. 658–659.
6. Roesky, H. W.; Tutkunkardes, S. Chem. Ber. 1974, 107,
508–517.
7. Billard, T.; Greiner, A.; Langlois, B. R. Tetrahedron
1999, 55, 7243–7250.
8. General procedure: To a solution of the appropriate N-
organylsulfinyl amine in monoglyme (or THF) at −60°C,
tetramethylammonium fluoride and trimethyl(trifluoro-
methyl)silane were added. The mixture was stirred for 2 h
at −50°C and for 1 h at room temperature. A 10%
aqueous solution of NH4Cl was added and the product
was extracted with diethyl ether. The extract was washed
with water, dried (MgSO4), and purified by vacuum
distillation or sublimation.
19F NMR (282.4 MHz, CD3CN):
l −62.6 (s, 3F,
ꢀCF3C6H4), −77.0 (s, 3F). Anal. calcd for C8H5F6NOS:
C, 34.66; H, 1.82; N, 5.05; F, 41.13. Found: C, 34.80; H,
1.98; N, 5.16; F, 41.32.
9. 3a: To a solution of 3.1 mmol N-t-butylsulfinylamine in
7 mL THF at −80°C, 3.1 mmol tetramethylammonium
fluoride and 3.41 mmol trimethyl(trifluoromethyl)silane
were added. The mixtures was stirred for 2 h at −45°C
and for 1 h at room temperature. The solvent was
evaporated, the residue was dried in vacuum. Yield 93%,
1
mp 65°C (decomp). H NMR (299.95 MHz, DMSO-d6):
l 1.04 (s, 9H, ꢀt-Bu), 3.10 (s, 12H, Me4N); 19F NMR
(282.4 MHz, DMSO-d6): l −80.46 (s, 3F). Anal. calcd for
C9H21F3N2OS: C, 41.20; H, 8.07; N, 10.68; F, 21.73; S,
12.22. Found: C, 41.37; H, 8.30; N, 10.55; F, 21.87; S,
12.16.
10. 5d: To a solution of 2.54 mmol N-phenylsulfinylamine in
5 mL THF at −80°C, 2.54 mmol tetramethylammonium
fluoride and 2.79 mmol trimethyl(pentafluoroethyl)silane
were added. The mixture was stirred for 2 h at −60°C. A
10% aqueous solution of NH4Cl was added at −30°C and
the product was extracted with diethyl ether. The extract
was washed with water, dried (MgSO4), and purified by
sublimation. Yield 80%, mp 38°C. 1H NMR (299.95
MHz, CDCl3): l 7.07 (m, 2H), l 7.18 (m, 1H), 7.34 (m,
2H), 6.50 (broad s, 1H, ꢀNH); 19F NMR (282.4 MHz,
CDCl3): l −79.8 (s, 3F), −121.5 and −125 (AB system,
2JFF=245.4 Hz). Anal. calcd for C8H6F5NOS: C, 37.07;
H, 2.33; N, 5.40; F, 36.65. Found: C, 36.89; H, 2.15; N,
5.26; F, 36.77.
All compounds were characterised on the basis of analyt-
1
ical and spectroscopic data. Selected data: 2a: H NMR
(299.95 MHz, CD3CN): l 1.35 (s, 9H, ꢀt-Bu), 5.48
(broad s, 1H, ꢀNH); 19F NMR (282.4 MHz, diethyl
ether): l −79.8 (s, 3F). Anal. calcd for C5H10F3NOS: C,
31.74; H, 5.33; N, 7.40; F, 30.13. Found: C, 32.01; H,
5.65; N, 7.62; F, 30.27. 2c: 1H NMR (299.95 MHz,
CD3CN): l 1.35 (s, 9H, ꢀt-Bu), 5.48 (broad s, 1H, ꢀNH);