Generation of sulfenylnitrenes by N-sulfenylation of triphenyl-λ6-sulfanenitrile

Article abstract of DOI:10.1016/S0040-4039(02)01170-X

The sulfenylation of triphenyl-λ⁶-sulfanenitrile (1) with 2,4-dinitrobenzenesulfenyl chloride in the presence of alkenes affords aziridines together with triphenylsulfonium salt. The reaction of 1 with sulfur dichloride also generates ClSN whic

Full text of DOI:10.1016/S0040-4039(02)01170-X

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 43 (2002) 5841–5843
Generation of sulfenylnitrenes by N-sulfenylation of
triphenyl-l6-sulfanenitrile
Takayoshi Fujii, Taeko Kousaka and Toshiaki Yoshimura*
Department of Material Systems Engineering and Life Science, Faculty of Engineering, Toyama University, Gofuku,
Toyama 930-8555, Japan
Received 14 May 2002; revised 10 June 2002; accepted 14 June 2002
Abstract—The sulfenylation of triphenyl-l6-sulfanenitrile (1) with 2,4-dinitrobenzenesulfenyl chloride in the presence of alkenes
affords aziridines together with triphenylsulfonium salt. The reaction of 1 with sulfur dichloride also generates ClSN which is
trapped by 2,5-diphenylfuran to give 5-benzoylisothiazole. © 2002 Elsevier Science Ltd. All rights reserved.
The development of new methodologies for the genera-
tion of reactive species is an important goal in organic
chemistry. The highly reactive transient species,
sulfenylnitrenes, have received considerable interest
from the structural and synthetical points of view.1,2
Nitroarylsulfenylnitrenes generated from the oxidation
of the corresponding sulfenamides with lead tetra-
acetate were trapped by several alkenes to give N-
sulfenylaziridines.1c,d Thermolysis of N-arylsulfenyl-
imino-1,4-dihydronaphthalenes also gave the sulfenyl-
nitrenes, which were trapped by alkenes to give the
corresponding aziridines.1e
alkyl halides, tosyl chloride, acid anhydrides, NO2BF4,
to give the corresponding N-substituted iminosulfo-
nium salts.3 We have now examined N-sulfenylation of
1 with arenesulfenyl chloride. This work led us to the
finding that the resulting N-arylsulfenyliminosulfonium
chloride readily undergoes SVI–N cleavage to generate
the sulfenylnitrenes. In addition, we also found that the
reaction of 1 with sulfur dichloride generates ClSN,
which was confirmed by converting 2,5-diphenylfuran
into 5-benzoylisothiazole.
The reaction of triphenyl-l6-sulfanenitrile (1) with 2,4-
dinitrobenzenesulfenyl chloride4 was first examined.
When 1 equiv. of 2,4-dinitrobenzenesulfenyl chloride
was added to a solution of 1 in CD2Cl2 at −80°C in an
NMR tube, 1 immediately disappeared and the peaks
due to the N-(2,4-dinitrophenylsulfenyl)iminosulfonium
Recently, we prepared triphenyl-l6-sulfanenitrile (1)
bearing
a
sulfur–nitrogen triple bond from
fluorodiphenyl-l6-sulfanenitrile with phenyllithium and
found it easily reacts with several electrophiles such as
R1
R2
R3
SAr
3
Ph
S
Ph
S
Ph
S
R4
R3
R4
R1
R2
N
ArSCl
+
Ph
Ph
Ph
Ph
Ph
Cl-
CH2Cl2, -30 °C
Cl-
N
NSAr
Ph
1
2
4
5
3a: R1 = R2 = R3 = H, R4 = Ph
3b: R1 = Me, R2 = R3 = H, R4 = Ph
3c: R1 = H, R2 = Me, R3 = H, R4 = Ph
4a (15%a))
4b (71%a))
4c (7%a))
4d (61%a))
3d: R1 = R2 = H, R3 = Me, R4 = (Me)C=CH2
Scheme 1. Ar=2,4-dinitrophenyl; (a) isolated yield.
Keywords: l6-sulfanenitrile; sulfenylnitrene; aziridines; sulfenylation; thiazyl chloride.
* Corresponding author. Fax: +81-76-445-6850; e-mail: yosimura@eng.toyama-u.ac.jp
0040-4039/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(02)01170-X

5842
T. Fujii et al. / Tetrahedron Letters 43 (2002) 5841–5843
Cl
Ph
S
S
S
N
N
SCl2
5 (96%a))
+
1
Ph
Ph
ClSN
N
S Cl
CH2Cl2, -30 °C
Cl-
NSCl
Cl
6
Ph
Ph
O
reflux conditions
Ph
Ph
N
S
O
7 (69%a))
Scheme 2. (a) Isolated yield.
chloride 2 appeared.5 Up to −50°C, compound 2 gradu-
ally decomposed to triphenylsulfonium chloride (5)
along with some unidentified products. This result indi-
cates the SVI–N bond cleavage of 2, although 2 was not
isolated. We investigated the potential of 2 to act as a
source of sulfenylnitrene in trapping experiments with
alkenes. The reaction of 1 with 2,4-dinitrobenzene-
sulfenyl chloride in CH2Cl2 at −30°C was carried out in
the presence of alkenes 3a–d (10 equiv.) as a trapping
regent. The results are summarized in Scheme 1. From
alkenes 3a–c, N-(2,4-dinitrophenylsulfenyl)azridines
4a–c were obtained in 15, 71, and 7% respective yields,
and from 2,3-dimethyl-1,3-butadiene (3d), N-(2,4-dini-
trophenylsulfenyl)-2-isopropenyl-2-methylaziridine (4d)
was obtained in 61% yield.6–9 In all reactions, triphenyl-
sulfonium chloride (5) was produced almost quantita-
tively. Thus, the formation of 4 suggests the generation
of 2,4-dinitrophenylsulfenylnitrene in the course of the
reaction of 1 with 2,4-dinitrobenezenesulfenyl chloride.
Acknowledgements
This work was partially supported by a Grant-in-Aid
for Research on Priority Areas (A) (No. 14044032)
from the Ministry of Education, Culture, Sports, Sci-
ence and Technology.
References
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Further, the generation of thiazyl chloride2a (ClSN) by
the reaction of l6-sulfanenitrile 1 with sulfur dichloride
was examined (Scheme 2). ClSN is in thermal equi-
librium with its trimer (ClSN)3 and these species are
useful for the synthesis of heterocyclic compounds with
NꢀS, NꢀSꢀN, and SꢀNꢀS units.10 After the reaction of
1 with sulfur dichloride in CH2Cl2 at −30°C for 30 min,
5 equiv. of a trapping reagent, 2,5-diphenylfuran, was
added to the reaction mixture. On boiling this mixture
for 1 h, the expected 5-benzoyl-3-phenylisothiazole
(7)10b was obtained together with 5. This reaction is
assumed to involve the initial sulfenylation to provide
6, followed by fission of the SVIꢀN bond to afford ClSN
together with 5. Finally, this reactive species, its
monomer or trimer, will be converted 2,5-diphenylfuran
into isothiazole 7.10b,c
3. (a) Yoshimura, T.; Hamada, K.; Imado, M.; Hamata, K.;
Tomoda, K.; Fujii, T.; Morita, H.; Shimasaki, C.; Ono,
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4. The sulfenylation reagent used is 2,4-dinitrobenzene-
sulfenyl chlorides, which is relatively stable and commer-
cially available.
5. 1H NMR (400 MHz, CD2Cl2, −80°C) l 7.83–8.02 (m,
17H), 8.98 (s, 1H); 13C NMR (100 MHz, CD2Cl2, −80°C)
l 121.1, 124.7, 125.4, 127.6, 129.6, 131.3, 137.6, 140.4,
143.9, 148.9.
In summary, we have demonstrated the generation of a
reactive species with a sulfurꢀnitrogen bond through
the reaction of l6-sulfanenitrile 1 with arenesulfenyl
chloride and sulfur dichloride. Our current efforts
include elucidation of the mechanism for the fission of
the SVIꢀN bond and application of this reaction system
to the generation of other reactive species.
6. All aziridines gave satisfactory spectral data (NMR, IR,
and MS). The side products were mainly 2,4-dinitroben-
zenesulfenamide (5–18% yields) and a complex mixture
including some unidentified products.

T. Fujii et al. / Tetrahedron Letters 43 (2002) 5841–5843
5843
7. The aziridination of trans- and cis-1-phenylpropene (3b
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adduct, 1l4,2-thiazacyclohexa-1,4-diene from FSN
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1979, 35–36).
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