Journal of Fluorine Chemistry 84 (1997) 63–64
A new synthesis of thioesters and selenoesters of triflic acid under
oxidative conditions
Thierry Billard, Bernard R. Langlois U
Universite´ Claude Bernard-Lyon I, Laboratoire de Chimie Organique 3, associe´ au CNRS, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne, France
Received 30 November 1996; accepted 17 January 1997
Abstract
Trifluoromethanethio-(or seleno-)sulfonates (CF3SO2YR, YsS, Se) are easily obtained in one step at 0–20 8C from disulfides (or
diselenides), sodium trifluoromethanesulfinate and [bis-(trifluoroacetoxy)iodo]benzene (BTIB). q 1997 Elsevier Science S.A.
Keywords: Trifluoromethanethiosulfonates; Trifluoromethaneselenosulfonates; Thioesters; Sodium triflinate; Disulfides; Diselenides; [bis-(Trifluoro-
acetoxy)iodo]benzene
1. Introduction
2. Results and discussion
Indeed, when a suspension of diphenyl diselenide 4a and
5 (2 equivalents) in dichloromethane was treated with BTIB
(1 equivalent) at 0 8C then stirred at room temperature for 2
h, 2a was obtained in a good yield (82%), far better than the
yield previously obtained from 4a, 5 and bromine (55%)
[2]. It must be noted that a larger excess of 5 (4 equivalents,
according to the molar ratio given in the literature [4]) did
not modify the yield of 2a. This effect, which we did not
observe for the reaction of sodium benzenesulfinate with
diphenyl diselenide and BTIB (4 eq. PhSO2Na, yield 81%
[4]; 2 eq. PhSO2Na, yield 67%), was probably due to a
higher solubility of 5 compared with PhSO2Na.
Aryl selenosulfonates (ArSO2SeAr9) are very useful syn-
thetic tools since they are powerful electrophilic selenylating
agents and can undergo electrophilic or free radical additions
to unsaturated substrates [1]. Thiosulfonates are less decri-
bed since they are reported to be less reactive than the seleno
analogs [1]. The reactivity of thioesters and selenoesters of
triflic acid (CF3SO2SR 1, CF3SO2SeR 2) is presently under
study in our laboratory: these compounds are much more
potent electrophiles than the non-fluorinated analogs and can
undergo ‘thiosulfonation’ as well as ‘selenosulfonation’
processes under mild conditions. They are also valuable
sources of trifluoromethyl radicals (full papers in prepara-
tion). We have recently published a simple one-pot prepa-
ration of these reagents from disulfides 3 (or diselenides 4),
sodium trifluoromethanesulfinate5andbromine[2]. Though
very satisfactory with dialkyl dichalcogenides, thistechnique
delivers only medium yields with aromatic disulfides. Thus,
more efficient ways were needed to activate these latter sub-
strates towards 5. A few years ago, non-fluorinated seleno-
sulfonates were obtained from alkaline sulfinates and
selenenyl cations generated by oxidation of diselenides with
ammonium peroxydisulfate [3] or [bis-(trifluoroace-
toxy)iodo]benzene (BTIB) [4]. Owing to the fact that 5 is
oxidized to trifluoromethyl radical by peroxydisulfate anions
[5], the former technique should not be adapted to the prep-
aration of trifluoromethaneselenosulfonates2but thereaction
of 4, 5 and BTIB could constitute a good access to 2.
Moreover, the same method has been successfully
extended to the preparation of thiosulfonates from disulfides
3, BTIB and sulfinates (especially 5). All the results are
summarized in Table 1.
RyYyYyRq2R9SOy2 NaqqPhI(OCOCF3)2
3ay3f (Y'S)
4a (Y'Se)
2 eq
1 eq
BTIB
X
5 (R 'CF3)
X
6 (R 'Ph)
CH2Cl2
™
2R9SO2yYyR
X
0y20TC 1ay1f (R 'CF3, Y'S)
2a (R 'CF3, YR'SePh)
X
X
7a (R 'Ph, YR'SPh)
X
8a (R 'Ph, YR'SePh)
Thus the reaction of disulfides (or diselenides), sulfinates
and BTIB offers, on the laboratory scale, a very convenient
access to thiosulfonates and selenosulfonates, especially
when aromatic dichalcogenides are used. This process has
U Corresponding author.
0022-1139/97/$17.00 q 1997 Elsevier Science S.A. All rights reserved
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