Reaction of carbonyl compounds with xenon difluoride in the presence of silicon tetrafluoride

Article abstract of DOI:10.1016/j.jfluchem.2003.11.019

Reaction of various carbonyl compounds with xenon difluoride in the presence of silicon tetrafluoride was investigated. Aromatic aldehyde, ketones, and α-ketoester react with xenon difluoride to give α,α-difluoroalkyl phenyl ethers. However, acid fluoride, ester, acid cyanide, α-ketocarboxylic acid, or thioester do not afford the corresponding products. In the case of cinnamaldehyde, fluorination was accompanied by intramolecular cyclization to afford fluorinated epoxide.

Full text of DOI:10.1016/j.jfluchem.2003.11.019

Journal of Fluorine Chemistry 125 (2004) 705–709
Reaction of carbonyl compounds with xenon difluoride in the
presence of silicon tetrafluoride
Masanori Tamura*, Yasuhisa Matsukawa, Heng-dao Quan,
Junji Mizukado, Akira Sekiya
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
Received 25 September 2003; received in revised form 19 November 2003; accepted 28 November 2003
Available online 13 January 2004
Abstract
Reaction of various carbonyl compounds with xenon difluoride in the presence of silicon tetrafluoride was investigated. Aromatic aldehyde,
ketones, and a-ketoester react with xenon difluoride to give a,a-difluoroalkyl phenyl ethers. However, acid fluoride, ester, acid cyanide,
a-ketocarboxylic acid, or thioester do not afford the corresponding products. In the case of cinnamaldehyde, fluorination was accompanied by
intramolecular cyclization to afford fluorinated epoxide.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Carbonyl compound; Cinnamaldehyde; Fluorination; Rearrangement; Cyclization; Xenon difluoride; Silicon tetrafluoride
1. Introduction
aromatic aldehyde and ketones, give a,a-difluoroalkyl phe-
nyl ethers. We also found that unprecedented epoxide for-
mation proceeds in the reaction of cinnamaldehydes.
Xenon difluoride (XeF2) is well known as a useful reagent
for electrophilic fluorinations. A variety of fluorination reac-
tions, such as fluorination to aromatic ring and to unsaturated
compound, fluorodeiodination, fluorodecarboxylation, etc.
have been developed and applied to prepare organic fluorine
compounds [1]. As one of these reactions, fluorination
reaction of aromatic aldehydes or ketones with XeF2 was
reported [2,3]. When aromatic aldehydes or ketones react
with XeF2 in the presence of hydrogen fluoride (HF),
fluorination is accompanied by skeletal rearrangement,
and a,a-difluoroalkyl aryl ethers are obtained. However,
the reaction of the other carbonyl compounds with XeF2
had not been reported.
We have been studying fluorination with XeF2 using
silicon tetrafluoride (SiF4) as a promoter. It was reported
that XeF2 are activated by acidic catalyst, such as HF,
boron trifluoride etherate (BF3OEt2), etc [4]. And we had
demonstrated that SiF4 also activates XeF2 and enhances
vic-difluorination of phenylalkenes or fluoroalkenes and
reaction of benzaldehydes [5,6].
2. Results and discussion
Initially, the reaction of aromatic ketones (1, R2 ¼ CH3,
C2H5, Ph) with XeF2 in the presence of SiF4 was investigated
(Scheme 1), and the results are summarized in Table 1. a,a-
Difluoroalkyl phenyl ethers (2) were obtained, and the result
was influenced by substituents on the benzene ring. In the
case of substrates substituted by an electron-withdrawing
group, the product was obtained in relatively high yield
(entry 1, 2), but the yield was relatively low (entry 4) when
an electron donating group is substituted on the benzene
ring. Especially, in the case of p-methoxyacetophenone,
which has a strong electron donating methoxy group, tarry
material was obtained (entry 5). The effect of substituent
would be explained by the concept that the more the benzene
ring is electron-rich, the more side-reactions such as fluori-
nation on the benzene ring proceed, which is similar to the
reaction of benzaldehydes with XeF2 [2,5].
In the course of this study, we investigated the reaction of
various kinds of carbonyl compounds with XeF2 in the
presence of SiF4, and found that a-ketoester, as well as
The reaction was examined using various aromatic
carbonyl compounds, and the results are summarized in
Table 2. In the case of acid fluoride, ester, and acid cyanide,
the corresponding a,a-difluoroalkyl phenyl ethers were not
obtained, although only fluorination to the benzene ring
* Corresponding author. Tel.: þ81-29-861-4771; fax: þ81-29-861-4771.
E-mail address: m-tamura@aist.go.jp (M. Tamura).
0022-1139/$ – see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2003.11.019

706
M. Tamura et al. / Journal of Fluorine Chemistry 125 (2004) 705–709
Table 2
The reaction of aromatic carbonyl compoundsa
O
C
XeF2, SiF4
CH2Cl2
OCF2R2
R2
R1
R1
Entry
Substrate
Yield of PhOCF2R (%)b
1
2
1c
2d
3e
4f
5g
6h
7i
C6H5C(O)CH3
C6H5C(O)H
C6H5C(O)F
40
57
0
R1 = H, p-NO2, p-Cl, p-CH3, p-CH3O
R2 = CH3, C2H5, Ph, H, F, OC2H5, CN, COOCH3, SC2H5, COOH
C6H5C(O)OC2H5
C6H5C(O)CN
0
Scheme 1. Reaction of aromatic carbonyl compounds with XeF2 in the
presence of SiF4.
0
C6H5C(O)COOC2H5
C6H5C(O)COOH
C6H5C(O)SC2H5
43
0
8j
0
Table 1
The reaction of aromatic ketonesa
a Substrate (1 mmol), XeF2 (1.2 mmol), SiF4 (0.5 mmol), and dichlor-
omethane (3 ml) were placed in a reactor (10 ml) and agitated at room
temperature for 16 h to 2.5 days.
Entry
Substrate
Yield of the
product (%)b
Recovery of the
substrate (%)b
b Determined by 19F NMR of the crude product (C6H5CF3 was used as
an internal standard).
1c
2
3
4
5
6
7
p-NO2C6H4C(O)CH3
p-ClC6H4C(O)CH3
C6H5C(O)CH3
91
53
40
18
3
21
23
34
42
38
31
c Recovery of the substrate was 23% (data from Table1, entry 3).
d 9 mmol of SiF4 was used (data from [5]).
e No reaction.
f Fluorination to benzene ring proceeded in 10%.
g Fluorination to benzene ring proceeded in 6%.
h Recovery of the substrate was 31%.
i C6H5C(O)F was obtained in 73%.
j C6H5C(O)F was obtained in 79%.
p-CH3C6H4C(O)CH3
p-CH3OC6H4C(O)CH3
C6H5C(O)C2H5
d
–
27
20
C6H5C(O)C6H5
a Substrate (1 mmol), XeF2 (1.2 mmol), SiF4 (0.5 mmol), and dichlor-
omethane (3 ml) were placed in a reactor (10 ml) and agitated at room
temperature for 2–2.5 days.
Next, the reaction of non-aromatic carbonyl compounds
was attempted. The reaction of aliphatic carbonyl compounds
afforded tarry matters. However, in the case of cinnamalde-
hyde, fluorination and intramolecular cyclization proceeds to
afford fluorinated epoxide (Scheme 3).
b Determined by 1H and 19F NMR of the crude product (C6H5CF3 was
used as an internal standard).
c 8 mmol of SiF4 was used.
d Tarry material was obtained.
This reaction was significantly influenced by the catalyst.
As shown in Table 3, the reaction was very slow without a
catalyst. When HF or BF3OEt2, which are representative
catalysts in fluorination with XeF2 [4], were used as cata-
lysts, the yield of fluoroepoxide (5) was low. On the other
hand, 5 was obtained in much higher yield with SiF4.
Probably, further undesirable reactions of 5, such as ring
opening, origomerization, etc., would proceed by HF and
BF3OEt2, however, SiF4 afforded good result because not
only does it have catalytic activity for XeF2 [5], but also
acidity of SiF4 is so weak that 5 was obtained without further
reaction [9].
occurred in the case of ester and acid cyanide (entries 3–5).
On the other hand, the reaction of a-ketoester proceeded and
afforded the corresponding a,a-difluoroalkyl phenyl ether
(entry 6). In the case of a-ketoacid, fluorodecarboxylation
[7] proceeded and afforded acid fluoride (entry 7). The
reaction of thioester with XeF2 also afforded acid fluoride
by desulfurization-fluorination [8] (entry 8).
The mechanism of this reaction from aromatic carbonyl
compounds 1 to a,a-difluoroalkyl phenyl ethers 2 has been
proposed as shown in Scheme 2 [1c,2,5]. XeF2 would be
activated by SiF4 and react with 1 to form alkoxyxenon
intermediate (3). Migration of the phenyl group to the
oxygen atom proceeds with loss of xenon and attack of
fluoride anion to afford 2.
The reactions of several a,b-unsaturated aldehydes are
summarized in Table 4. The reaction of b-phenyl cinnamal-
dehyde was accompanied by vic-difluorination to the double
δ
δ+
Xe
-
F
F
SiF4
R2
XeF
R2
F
O
XeF
O
O
R2
+
+
F-
+
Xe
R2
O
C
+
F-
+
F
R1
R1
R1
R1
3
1
R1= H, alkyl, alkoxycarbonyl
O
CF2R2
R1
2
Scheme 2. Postulated mechanism of transformation of aromatic carbonyl compounds to a,a-difluoroalkyl aryl ethers.

M. Tamura et al. / Journal of Fluorine Chemistry 125 (2004) 705–709
707
Table 3
Effect of catalyst on the reaction of cinnamaldehydea
Entry
Catalyst
Amount of catalyst
(mmol)
Time (h)
Yield (%)b
Recovery of the
substrates (%)b
1
2
3
4
5
–
SiF4
36
16
18
1.5
2
3
60
3
82
6
0.5
0.3
4
HF
88
10
1
HF
38
2
BF3O(C2H5)2
0.1
a Substrate (1 mmol), XeF2 (1.2 mmol), catalyst and dichloromethane (3 ml) were placed in a reactor (10 ml) and agitated at room temperature.
b Determined by 1H and 19F NMR of the crude product (C6H5CF3 was used as an internal standard).
R2
O
F
bond and elimination of HF [5,10] to give a-fluoro-b-phenyl
cinnamaldehyde. In the case of 3-(p-nitorophenyl)propenal,
formation of difluoromethoxy ether (p-NO2C6H5CH¼-
CHOCHF2) proceeded competitively and its fluorination
product (p-NO2C6H5CHFCHFOCHF2), was also obtained.
The formation of epoxide 5 would be explained by the
reaction mechanism as follows (Scheme 4). By the reaction
of 4 with XeF2 in the presence of SiF4, alkoxyfluoroxenon
species (6) is formed similarly to the above-mentioned
reaction of aromatic carbonyl compounds with XeF2. Intra-
molecular cyclization of 6 proceeds to form intermediate
cation (7) followed by transformation to 5 by the attack of
fluoride anion. In the case of 3-(p-nitorophenyl)propenal, it
is assumed that ether type cation intermediate (8) is formed
by C–C bond cleavage to give difluoromethoxy ether (9).
Probably, the nitro group on the benzene ring would desta-
bilize the cation 7 by its electron withdrawing effect, which
drives rearrangement from 7 to 8.
XeF2, SiF4
CH2Cl2
O
R1
R1
H
R2
F
5
4
a: R1 = Ph, R2 = H
b: R1 = R2 = Ph
c: R1 = p-NO2C6H4, R2 = H
Scheme 3. Reaction of cinnamaldehydes with XeF2 in the presence of
SiF4.
Table 4
The reaction of a,b-unsaturated aldehydesa
Entry
Substrate
Yield of 5 (%)b
1c
2d
3e
C6H5CH¼CHCHO
60
44
26
(C6H5)2C¼CHCHO
p-NO2C6H5CH¼CHCHO
a Substrate (1 mmol), XeF2 (1.2 mmol), SiF4 (0.5 mmol), and dichlor-
omethane (3 ml) were placed in a reactor (10 ml) and agitated at room
temperature for 16 h.
3. Conclusion
b Determined by 19F NMR of the crude product (C6H5CF3 was used as
an internal standard).
c The substrate was recovered in 6% (data from Table 3, entry 2).
d Byproducts, such as (C6H5)2C¼CFCHO (11%), (C6H5)2CFCHFCHO
(4%) etc., was obtained, and the substrate was recovered in 8%.
e The products by skeletal rearrangement, p-NO2C6H5CH¼CHOCHF2
and p-NO2C6H5CHFCHFOCHF2 were obtained in 17 and 9%, respec-
tively.
We have disclosed the reaction of various carbonyl com-
pounds with XeF2. In the presence of SiF4, a,a-difluoroalkyl
aryl ethers were obtained by the reaction of aromatic
aldehyde, ketones, or a-ketoester via fluorination accom-
panied by skeletal rearrangement. However, in the case of
aryl acid fluoride, ester, acid cyanide, a-ketocarboxylic acid
or thioester, the skeletal rearrangement does not proceed.
And especially, a-ketocarboxylic acid or thioester afforded
the corresponding acid fluoride.
On the other hand, we have found that fluorination and
intramolecular cyclization proceed by the reaction of cin-
namaldehyde with XeF2 in the presence of SiF4 to give novel
fluorinated epoxide.
XeF
O
O
XeF2, SiF4
- Xe, F-
Ar
H
Ar
F
6
4
O
O
Ar
Ar
CHF
F
F
4. Experimental details
7
8
F-
F
F-
4.1. General
O
All the reagents are commercially available. Reagents
and solvents employed were purified prior to use except for
XeF2 and SiF4. IR spectra were measured with FT-IR 8900
O
Ar
CHF2
Ar
9
5
(Japan Spectroscopic). H and 19F NMR were measured
1
Scheme 4. Postulated mechanism of the reaction of cinnamaldehydes.

708
M. Tamura et al. / Journal of Fluorine Chemistry 125 (2004) 705–709
with JNM-EX270 (JEOL, 270 MHz) using TMS and CFCl3
as internal standards and CDCl3 as a solvent.
the epoxide ring, m), 7.4 (5H aromatic, m); 19F(CFCl3) d
ꢀ155.2 (CHF on the epoxide ring, dd, J2 ¼ 85:1, 1.5 Hz),
ꢀ186.9 (PhCHF, dd, J2 ¼ 46:4, 15.9 Hz); 5-B: 1H d 3.5 (CH
on the epoxide ring, dm, J2 ¼ 2:6 Hz), 5.44–5.48 (PhCHF,
m), 5.54 (CHF on the epoxide ring, m), 7.4 (5H aromatic,
m); 19F d ꢀ155.4 (CHF on the epoxide ring, ddd, J2 ¼ 85:5,
3.1, 1.8 Hz), ꢀ187.3 (PhCHF, dd, J2 ¼ 47:6, 16.5 Hz); 5-C:
1H d 3.2 (CH on the epoxide ring, ddm, J2 ¼ 8:3, 2.0 Hz),
5.44–5.48 (PhCHF, m), 5.59 (CHF on the epoxide ring, dm,
J2 ¼ 2:0 Hz), 7.4 (5H aromatic, m); 19F d ꢀ161.5 (CHF on
the epoxide ring, ddd, J2 ¼ 86:1, 2.4, 1,8 Hz), ꢀ187.2
(PhCHF, ddd, J2 ¼ 47:6, 7.3, 4.3 Hz); 5-D: 1H d 3.18
(CH on the epoxide ring, ddm, J2 ¼ 7:5, 1.4 Hz), 5.36–
5.4 (PhCHF, m), 5.69 (CHF on the epoxide ring, dm,
J2 ¼ 1:4 Hz), 7.4 (5H aromatic, m); 19F d ꢀ163.7 (CHF
on the epoxide ring, ddd, J2 ¼ 86:7, 2.4, 1,8 Hz), ꢀ183.9
(PhCHF, ddd, J2 ¼ 45:8, 1.8, 1.8 Hz); IR (KBr, cmꢀ1) 3038,
1455, 1124, 1047, 757; MS calcd 170.0543, obsd 170.0522.
4.2. A typical experimental procedure for the reaction
Substrate (1.0 mmol) dissolved in CH2Cl2 (3 ml) and
XeF2 (1.2 mmol) were placed in a stainless-steel reactor
equipped with a stop valve (volume, 10 ml). SiF4 (0.5 mmol)
was introduced into the reactor at ꢀ196 8C from a vacuum
line. The reactor was warmed up to ambient temperature and
shakenvigorouslyfortheindicatedtime. Thereactionmixture
was poured into aqueous saturated NaHCO3. The aqueous
phase was extracted with CH2Cl2 and the combined organic
phasewasdriedwithMgSO4.Afterevaporationofthesolvent,
the crude product was analyzed by 1H and 19F NMR spectro-
scopy to determine the yield of the product. The product was
purified by preparative thin layer chromatography.
All the compounds were characterized by NMR, IR, and/
or high-resolution MS analysis. Representative data are as
follows.
1
1,3-Difluoro-3,3-diphenyl-1,2-epoxypropane: H d 3.91
(CH, dd, J2 ¼ 17:7, 1.8 Hz), 5.55 (CHF, d, J2 ¼ 86:0 Hz),
7.4 (5H aromatic, m); 19F d ꢀ153.2 (CF, d, J2 ¼ 17:7 Hz),
ꢀ155.6 (CHF, d, J2 ¼ 86:0 Hz); IR (KBr, cmꢀ1) 3063,
1450, 1259, 1126, 1048, 973, 925, 746, 698; MS calcd
246.0856, obsd 246.0864.
1-(1,1-Difluoroethoxy)-4-nitrobenzene: 1H d 1.99 (3H,
CH3, t, J3 ¼ 13:4 Hz), 7.3 (2H aromatic, m), 8.2 (2H aro-
matic, m); 19F d ꢀ66.1 (q, J4 ¼ 13:4 Hz); IR (KBr, cmꢀ1
)
1596, 1526, 1494, 1404, 1349, 1270, 1187, 1160, 980, 930,
867, 843, 750; MS calcd 203.03934, obsd 203.0379.
1,3-Difluoro-3-(4-nitrophenyl)-1,2-epoxypropane, which
consisted of four isomers, 5-E, 5-F, 5-G, 5-H
1
1-Chloro-4-(1,1-difluoroethoxy)benzene: H d 1.91 (3H,
1
CH3, t, J3 ¼ 13:4 Hz), 7.1 (2H aromatic, m), 7.3 (2H aro-
(ratio ¼ 24:42:18:16). 5-E: H d 3.56 (CH on the epoxide
matic, m); 19F d ꢀ65.4 (q, J4 ¼ 13:4 Hz); IR (KBr, cmꢀ1
)
1489, 1404, 1278, 1186, 1151, 1091, 1016, 977, 925; MS
ring, ddd, J2 ¼ 18:9, 3.4, 2.0 Hz), 5.63 (CHF on the epoxide
ring, d, J2 ¼ 84:8 Hz), 5.66 (NO2C6H4CHF, dd, J2 ¼ 45:8,
3.4 Hz), 7.6 (2H aromatic, m), 8.3 (2H aromatic, m); 19F d
ꢀ154.8 (CHF on the epoxide ring, d, J2¼84.8 Hz), ꢀ192.3
calcd 192.0153, obsd 192.0161.
(1,1-Difluoroethoxy)benzene: 1H d 1.91 (3H, CH3, t,
J3 ¼ 13:3 Hz), 7.1–7.3 (5H aromatic, m); 19F d ꢀ64.9 (q,
J4 ¼ 13:3 Hz); IR (KBr, cmꢀ1) 1506, 1403, 1276, 1183,
978, 924, 736, which correspond to the authentic sample [3].
1-(1,1-Difluoroethoxy)-4-methylbenzene: 1H d 1.90 (3H,
CH3, t, J3 ¼ 13:3 Hz), 7.1 (4H aromatic, m); 19F d ꢀ64.9 (q,
J4 ¼ 13:3 Hz); IR (KBr, cmꢀ1) 1510, 1401, 1280, 1184,
1150, 980, 924; MS calcd 172.0699, obsd 192.0702.
1
(NO2C6H4CHF, dd, J2 ¼ 45:8, 18.9 Hz); 5-F: H d 3.53
(CH on the epoxide ring, ddd, J2 ¼ 14:4, 3.2, 2.0 Hz), 5.54
(CHF on the epoxide ring, d, J2 ¼ 83:6 Hz), 5.6 (NO2-
C6H4CHF, m), 7.6 (2H aromatic, m), 8.3 (2H aromatic,
m); 19F d ꢀ155.2 (CHF on the epoxide ring, d, J2 ¼
83:6 Hz), ꢀ190.7 (NO2C6H4CHF, dd, J2 ¼ 47:0,
1
14.4 Hz); 5-G: H d 3.2 (CH on the epoxide ring, m), 5.6
1
(1,1-Difluoropropoxy)benzene: H d 1.16 (3H, CH3, t,
(NO2C6H4CHF, m), 5.69 (CHF on the epoxide ring, ddd,
J2 ¼ 86:1, 4.6, 2.0 Hz), 7.6 (2H aromatic, m), 8.3 (2H
aromatic, m); 19F d ꢀ160.9 (CHF on the epoxide ring, d,
J2 ¼ 86:1 Hz), ꢀ190.5 (NO2C6H4CHF, ddd, J2 ¼ 42:1, 7.9,
J3 ¼ 7:5 Hz), 2.15 (2H, CH2, tq, J3 ¼ 11:1 Hz,
J4 ¼ 7:5 Hz), 7.1–7.4 (5H aromatic, m); 19F d ꢀ73.2 (t,
J3 ¼ 11:1 Hz); IR (KBr, cmꢀ1) 2992, 2953, 1592, 1506,
1493, 1470, 1372, 1293, 1255, 1161, 1044, 1015, 974, 752,
693; MS calcd 172.0699, obsd 192.0723.
1
5.5 Hz); 5-H: H d 3.2 (CH on the epoxide ring, m), 5.5
(NO2C6H4CHF, dd, J2 ¼ 45:2, 8.3 Hz), 5.8 (CHF on the
epoxide ring, ddd, J2 ¼ 86:7, 2.0, 2.0), 7.6 (2H aromatic, m),
8.3 (2H aromatic, m); 19F d ꢀ163.3 (CHF on the epoxide
ring, dd, J2 ¼ 86:7, 3.1 Hz), ꢀ189.2 (NO2C6H4CHF, dd,
J2 ¼ 45:2, 3.1 Hz); IR (KBr, cmꢀ1) 1527, 1457, 1124, 1043,
944, 857, 833, 716; MS calcd 215.0393, obsd 215.0381.
(Difluorophenoxymethyl)benzene: 1H d 7.2–7.5 (8H aro-
matic, m), 7.7–7.8 (2H aromatic, m); 19F d ꢀ65.9 (s); IR
(KBr, cmꢀ1) 1505, 1492, 1455, 1321, 1200, 1144, 1046, 764,
695, which correspond to the authentic sample [3].
1
Methyl difluorophenoxyacetate: H d 3.94 (3H, CH3, s),
7.2–7.3 (3H aromatic, m), 7.3–7.4 (2H aromatic, m); 19F d
ꢀ76.6(s);IR(KBr,cmꢀ1)1783,1505,1492,1358,1206,1138,
738, 690, which correspond to the authentic sample [11].
1,3-Difluoro-3-phenyl-1,2-epoxypropane, which consis-
ted of four isomers, 5-A, 5-B, 5-C, 5-D (ratio ¼
References
[1] (a) R. Filler, Israel J. Chem. 17 (1978) 71–79;
(b) M. Zupan, Chemistry of Functional Groups, suppl. D, Wiley,
New York, 1983 (Chapter 15).;
1
41:25:24:10). 5-A: H(TMS) d 3.55 (CH on the epoxide
ring, dm, J2 ¼ 4:2 Hz), 5.36–5.4 (PhCHF, m), 5.54 (CHF on
(c) M.A. Tius, Tetrahedron 51 (1995) 6605–6634.

M. Tamura et al. / Journal of Fluorine Chemistry 125 (2004) 705–709
709
[2] S. Stavber, Z. Koren, M. Zupan, Synletter (1994) 265–266.
[3] B. Zajac, M. Zupan, J. Org. Chem. 55 (1990) 1099–1102.
[4] A. Gregorcic, M. Zupan, Bull. Chem. Soc. Jpn. 53 (1980) 1085–
1088.
example, see:M. Zupan, Z. Bregar, Tetrahedron Lett. 31 (1990)
3357–3358;
M. Kuroboshi, K. Suzuki, T. Hiyama, Tetrahedron Lett. 33 (1992)
4173–4176;
[5] M. Tamura, T. Takagi, H. Quan, A. Sekiya, J. Fluorine Chem. 98
(1999) 163–166.
M. Kuroboshi, T. Hiyama, Tetrahedron Lett. 33 (1992) 4177–4178;
R.D. Chambers, G. Sandford, M. Atherton, J. Chem. Soc. Chem.
Commun. (1995) 177–177.
[6] M. Tamura, H. Quan, A. Sekiya, Eur. J. Org. Chem. (1999) 3151–
3153.
[9] It was reported that ring opening of epoxide proceeds with SiF4, but
it requires a Lewis base, such as amine or water, see:M. Shimizu, H.
Yoshioka, Tetrahedron Lett. 29 (1988) 4101–4104.
[10] S. Stavber, T. Sotler, M. Zupan, J. Org. Chem. 59 (1994) 5891–5894,
and references cited therein.
[7] (a) T.B. Patrick, K.K. Johri, D.H. White, J. Org. Chem. 48 (1983)
4158–4159;
(b) T.B. Patrick, K.K. Johri, D.H. White, W.S. Bertrand, R. Mokhtar,
M.R. Kilbourn, M.J. Welch, Can. J. Chem. 64 (1986) 138–141.
[8] Conversions of C–S bond to C–F bond by oxidative desulfurization-
fluorinations with XeF2 or the other reagents were reported. For
[11] L.M. Yagupol’skii, V.A. Korin’ko, J. Gen. Chem. USSR 39 (1969)
1711–1714.