G Model
FLUOR-8119; No. of Pages 4
O. Mah e´ et al. / Journal of Fluorine Chemistry xxx (2013) xxx–xxx
3
Table 3
added dichloromethane (558 mL) followed by boron trifluoride
tetrahydrofuran complex (69 mL, 0.63 mol) dropwise over 1 h
keeping the temperature below 25 8C. The suspension was stirred
an additional 60 min, then filtered under a blanket of nitrogen. The
solid material was rinsed with diethyl ether (3 Â 150 mL), then
dried under vacuum to provide pyrrolidinodifluorosulfinium
tetrafluoroborate (121 g, 85%) as beige crystals: m.p. 105–
Deoxofluorination of a ketone, 1,4-dioxaspiro[4.5]decan-8-one (12).
1
7
4
13 8C; IR (ATR, ZnSe)
n
= 1459, 1269, 1216, 1019, 822,
À1
1
55 cm
;
H NMR (CD
3
CN) d 4.10–3.98 (m, 4H), 2.19–2.12 (m,
1
3
19
H); C NMR (CD CN) 53.1, 25.9; F NMR (CD
3
d
3
CN)
d
H
12.09 (q, 2F,
.
*+
J = 7.6 Hz), À151.26 (s, 4F); HRMS-ESI calcd for C
4
8 2
NSF [M]
a
a
Entry
Reagent
Yield of 13 (%)
Yield of 14 (%)
1
40.0346, found 140.0340.
1
1
2
3
4
5
XtalFluor-E
57
8
11
12
<3
9
1
b
XtalFluor-M
66 (76)
3.1.2. Preparation of N-methyl-N-phenylaminodifluorosulfinium
1
2
3
60
45
58
tetrafluoroborate salt (2)
To a stirring solution of N-methylaniline (80 g, 0.75 mol) in
diethyl ether (600 mL) cooled at À78 8C was added n-butyllithium
a
19
1
Determined by F and/or H NMR analysis of the crude mixture using 2-fluoro-
-nitrotoluene as an internal standard.
(
2.4 M in hexane; 342 mL, 0.82 mol) keeping the temperature
4
b
below À60 8C. The resulting slurry was stirred for 1 h then
chlorotrimethylsilane (114 mL, 0.90 mol) was added while keep-
ing the temperature below À70 8C. The reaction was allowed to
warm to room temperature overnight then filtered to remove the
precipitated white solid. The filtrates were concentrated in vacuo
then distilled under high vacuum to yield the N-trimethylsilyl-N-
Isolated yield under slightly different conditions with no elimination observed,
see Ref. [15].
results showed that subtle modification of the structure of the N,N-
disubstituted aminodifluorosulfinium tetrafluoroborate salts can
modify their reactivity and selectivity in deoxofluorination
reactions of alcohol (primary and secondary) or ketones. However,
while the new derivatives proved not to be superior to XtalFluor-
methylaniline [19] (126 g, 94%) as a colorless/straw colored liquid.
b.p. 48 8C/0.6 mmHg; H NMR (CDCl
1
3
)
d
7.27 (t, 2H, J = 9 Hz), 6.94
1
1
E
and XtalFluor-M in terms of deoxofluorinating capability,
(d, 2H, J = 8 Hz), 6.85 (t, 1H, J = 7 Hz,), 2.95 (s, 3H), 0.33 (s, 9H). To a
5 L flange necked flask fitted with magnetic stirrer, temp probe,
bubbler and nitrogen inlet was added dichloromethane (150 mL)
and then cooled to À78 8C. Sulfur tetrafluoride (57.1 g, 0.53 mol)
was sub-surfaced while keeping the temperature below À65 8C. To
the resulting solution was added dropwise a solution of N-
trimethylsilyl-N-methylaniline (91.2 g, 0.51 mol) in dichloro-
methane (42 mL) while keeping the temperature below À70 8C.
The resulting solution was allowed to slowly warm to room
temperature and stirred overnight. To the resulting solution was
added dichloromethane (558 mL) followed by boron trifluoride
tetrahydrofuran complex (56 mL, 0.51 mol) dropwise over 70 min
keeping the temperature below 25 8C. The suspension was stirred
an additional 60 min, then filtered under a blanket of nitrogen. The
solid material was rinsed with diethyl ether (3 Â 150 mL), then
dried under vacuum to provide N-methyl-N-phenylaminodifluor-
osulfinium tetrafluoroborate salt (124 g, 93%) as dark-gray
reagent 2, N-methyl-N-phenylaminodifluorosulfinium tetrafluor-
oborate salt, showed promising results for reducing the elimina-
tion side-reaction with secondary alcohols and ketones.
3
. Experimental
All reactions were carried out under an argon atmosphere with
1
13
19
dry solvents under anhydrous conditions. H, C and F spectra
were recorded on a VARIAN Inova 400 or a BRUKER Advance 300 in
3 3
CDCl or CD CN at ambient temperature. Infrared spectra were
recorded on a Thermo Scientific Nicolet 380 FT-IR spectrometer.
High-resolution mass spectra were obtained on a LC/MS-TOF
1
Agilent 6210 using electrospray ionization (ESI) [23]. XtalFluor-E
1
and Xtalfluor-M were obtained from Aldrich. The N,N-disub-
stitutedaminodifluorosulfinium tetrafluoroborate salts 1–3 were
synthesized by Manchester Organics Limited (UK).
crystals: m.p. 144–150 8C; IR (ATR, ZnSe)
n
= 1287, 1004, 964,
7.71–7.47 (m, 5H), 3.79 (t,
132.8, 131.5, 128.0, 122.7, 43.8;
14.33 (s, 2F), À150.41 (s, 4F); HRMS-ESI calcd
+
À1
1
3.1. Preparation of the N,N-disubstitutedaminodifluorosulfinium
836, 764, 692 cm ; H NMR (CD CN) d
3
1
3
tetrafluoroborate salts
3
J = 7.6 Hz, 1H); C NMR (CD CN) d
1
9
F NMR (CD
3
CN) d
*
3
.1.1. Preparation of pyrrolidinodifluorosulfinium tetrafluoroborate
salt (1)
To an ice-cold solution of pyrrolidine (167 mL, 2.00 mol) in
for C NSF [M] 176.0346, found 176.0342.
7
H
8
2
3.1.3. Preparation of N-methyl-N-(2-pyridyl)aminodifluorosulfinium
diethyl ether (500 mL) was added a solution of chlorotrimethylsi-
lane (127 mL, 1.00 mol) in diethyl ether (100 mL) over 1 h. The
solid was removed by filtration and washed with diethyl ether
tetrafluoroborate salt (3)
To
a stirring solution of 2-methylaminopyridine (19.5 g,
0.18 mol) in diethyl ether (120 mL) cooled at À78 8C was added
n-butyllithium (2.4 M in hexane; 85 mL, 0.20 mol) keeping the
temperature below À70 8C. The resulting slurry was stirred for 1 h
then chlorotrimethylsilane (28.2 mL, 0.22 mol) was added while
keeping the temperature below À70 8C. The reaction was allowed
to warm to room temperature overnight then filtered to remove
the precipitated white solid. The filtrates were concentrated in
vacuo then distilled under high vacuum to yield the N-trimethyl-
(100 mL). The filtrates were concentrated in vacuo then distilled at
atmospheric pressure to give N-trimethylsilylpyrrolidine [17]
1
(
d
2
3
104 g, 73%) as a colorless liquid. b.p. 139–140 8C; H NMR (CDCl )
13
2.91 (m, 4H), 1.74 (m, 4H), 0.09 (s, 9H); C NMR (CDCl
8.26, 3.50. To a 5 L flange necked flask fitted with magnetic stirrer,
3
) d 48.33,
temp probe, bubbler and nitrogen inlet was added dichloro-
methane (150 mL) and then cooled to À78 8C. Sulfur tetrafluoride
(70.6 g, 0.65 mol) was sub-surfaced while keeping the temperature
silyl-N-methyl-2-aminopyridine (31.9 g, 96%) as a colorless liquid.
1
below À65 8C. To the resulting solution was added dropwise a
solution of N-trimethylsilylpyrrolidine (90 g, 0.62 mol) in dichlor-
omethane (42 mL) while keeping the temperature below À60 8C.
The resulting solution was allowed to slowly warm to room
temperature and stirred overnight. To the resulting solution was
b.p. 50 8C/0.5 mmHg; H NMR (CDCl
3
)
d
8.12 (m, 1H), 7.49 (m, 1H),
13
6.62 (m, 1H), 6.51 (t, J = 8 Hz, 1H), 2.86 (s, 3H), 0.33 (s, 9H);
C
NMR (CDCl 160.74, 145.94, 136.05, 111.38, 105.03, 30.91, 0.00.
3
) d
To a 5 L flange necked flask fitted with magnetic stirrer, temp
probe, bubbler and nitrogen inlet was added dichloromethane