A new entry for the oxidation of fluoroalkyl-substituted methanol derivatives: Scope and limitation of the organoiodine(V) reagent-catalyzed oxidation

Article abstract of DOI:10.1016/j.jfluchem.2012.03.002

Oxidation of various fluoroalkyl-substituted methanol derivatives under the influence of a catalytic amount of sodium 2-iodobenzenesulfonate and Oxone in CH₃CN or CH₃NO₂ was investigated in detail. The efficiency of the newly developed oxidation was also evaluated by comparison to other oxidations, such as Dess-Martin, PDC, and Swern oxidation.

Full text of DOI:10.1016/j.jfluchem.2012.03.002

Journal of Fluorine Chemistry 137 (2012) 99–104
Contents lists available at SciVerse ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
A new entry for the oxidation of fluoroalkyl-substituted methanol derivatives:
Scope and limitation of the organoiodine(V) reagent-catalyzed oxidation
*
Yusuke Tanaka, Takashi Ishihara, Tsutomu Konno
Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-0962, Japan
A R T I C L E I N F O
A B S T R A C T
Article history:
Oxidation of various fluoroalkyl-substituted methanol derivatives under the influence of a catalytic
amount of sodium 2-iodobenzenesulfonate and Oxone1 in CH3CN or CH3NO2 was investigated in detail.
The efficiency of the newly developed oxidation was also evaluated by comparison to other oxidations,
such as Dess–Martin, PDC, and Swern oxidation.
Received 3 February 2012
Received in revised form 28 February 2012
Accepted 5 March 2012
Available online 16 March 2012
ß 2012 Elsevier B.V. All rights reserved.
Keywords:
Fluoroalkyl-substituted methanols
Sodium 2-iodobenzenesulfonate
Oxone1
Hypervalent iodine(V)
1. Introduction
significantly resistant to be oxidized due to a strongly electron-
withdrawing effect of a fluoroalkyl group [26,27].
Incorporation of fluorine atom(s) into organic molecules often
changes their structure, stability, reactivity, and biological activity,
and thereby frequently leads to the discovery of novel and potent
applications in various domains from liquid crystalline materials to
biologically active substances, peptide isosteres or enzyme
inhibitors [1–7]. Consequently, the development of novel and
convenient synthetic methods for the preparation of fluorine-
containing materials has been becoming more and more important
in fluorine chemistry [8–14].
Among various types of fluoroorganic molecules, fluoroalky-
lated ketones 1 have been well known as one of the most
fundamental and valuable synthetic fluorinated units because of
their great utility as an electrophile, and considerable studies on
the preparation of 1 have been reported thus far [15–17].
The oxidation of fluoroalkyl-substituted methanol derivatives 2
to the corresponding ketones 1 would be one of the most attractive
transformations in fluorine chemistry because the alcohols 2 can
be easily prepared from numerous methods, such as the reductive
coupling of commercially available fluoroalkyl halides 3 and
various aldehydes [18,19], fluoride-catalyzed nucleophilic addi-
tion of RfSiMe3 4 with various aldehydes [20–22], and so on [23–
25] (Fig. 1). However, it has been well recognized that the
oxidation of the alcohols 2 is not trivial because they are
Therefore, very powerful oxidizing reagents, such as Dess–
Martin periodinane 5 [28] or chromium reagents 6 and 7 [29], can
be generally employed for the oxidation of such molecules in
fluorine chemistry [30–33] (Fig. 2). From the viewpoint of safety,
environmental load, and cost, however, more efficient as well as
more practical oxidation methods have been highly required.
In this article we wish to disclose our recent studies on the
hypervalent iodine-catalyzed oxidation [34–38] of fluorinated
alcohols by using sodium 2-iodobenzenesulfonate (8) and Oxone1
(2KHSO5ÁKHSO4ÁK2SO4), especially emphasizing scope and limita-
tion of this oxidation, compared with other oxidation systems,
such as Dess–Martin, PDC, and Swern oxidations.
2. Results and discussion
Initial studies focused on the oxidation of 2,2,2-trifluorophe-
nethyl alcohol (2a: R = Ph) under the influence of a catalytic
amount of sodium 2-iodobenzenesulfonate (8) and Oxone1
(2KHSO5ÁKHSO4ÁK2SO4). Thus, treatment of 2a with 0.6 equiv. of
Oxone1 in the presence of 1 mol% of 8 in CH3CN at 70 8C for 3 h
gave the corresponding ketone 1a in 39%, together with 55%
recovery of the starting material (Table 1, entry 1). Prolonged
reaction time resulted in the increase of the yield up to 54% (entry
3). The increase of the catalysis loading (entry 4) and higher
temperature (entry 5) led to satisfactory results, the ketone 1a
being obtained in up to 68% yield. Additionally, a significant
improvement of the yield was observed when 0.9 equiv. of Oxone1
was employed (entry 6). Further investigation on the catalysis
* Corresponding author.
E-mail address: konno@chem.kit.ac.jp (T. Konno).
0022-1139/$ – see front matter ß 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2012.03.002

100
Y. Tanaka et al. / Journal of Fluorine Chemistry 137 (2012) 99–104
Rf-X
cases due to the high volatility of the products. In the oxidation of
the alcohols 2i having a nitro group on the benzene ring, only the
desired ketone 1i could be easily isolated in high yield by silica gel
column chromatography though 19F NMR analysis of the reaction
mixture revealed that the ketone 1i as well as the corresponding
hydrate 9i were formed in a ratio of 1:1 (entry 8). Additionally, the
position of the substituent on the benzene ring did not influence
the reaction at all as described in entries 2–4 and entries 5–7. The
trifluoromethylated allylic alcohol 2l and propargylic alcohols 2m
and 2n could be oxidized very smoothly to afford the correspond-
ing ketones 1l, 1m, and 1n in high to excellent yields (entries 11–
13). As also described in Table 1, the trifluoromethylated alcohols
2b, 2o-r, having an aliphatic side chain, underwent a very smooth
oxidation under the severe reaction conditions, such as 10 mol% of
8/CH3NO2/110 8C/24 h, compared with that for 2,2,2-trifluorophe-
nethyl alcohol derivatives (entries 14–18).
3
X = Halide
Reductive coupling
O
Oxidation
OH
O
or
+
Rf
R
Rf
R
H
R
1
2
Rf-SiMe3
4
Fig. 1. Retrosynthesis of fluoroalkylated ketones 1.
loading (entry 7) as well as the reaction time (entry 8) enabled us to
afford the ketone 1a in 97% yield.
This result encouraged us to investigate the oxidation of 1,1,1-
trifluoroundecan-2-ol (2b: R = n-C9H19) under the same reaction
conditions as described in entry 8. Unfortunately, the desired
ketone 1b was obtained in only 38% yield, and the starting alcohol
was recovered in 48% yield (entry 9). Then, we reinvestigated the
reaction conditions for the substrate 2b. While the prolonged
reaction time did not lead to a dramatic change in the yield (entry
10), changing the solvent from CH3CN to CH3NO2 appreciably
affected the yield (entry 11). Finally, the reaction at 110 8C
proceeded very smoothly to give the desired ketone 1b in excellent
yield (entries 12 and 13). With the optimum reaction conditions in
hand, we next examined the oxidation of various types of
fluorinated alcohols. The results are collected in Table 2.
We also investigated the oxidation of the alcohols having various
fluoroalkyl groups. As shown in entries 19–26, changing the
fluoroalkyl group from trifluoromethyl group to nonafluorobutyl,
pentafluoroethyl, and difluoromethyl groups did not cause a
significant influence in the reaction, the desired ketones 1s-z being
obtained in excellent yields. Additionally,
a,a,-difluoro-b-hydro-
xyesters 2aa and 2ab could also participate in the oxidation very well
to give the corresponding 1,3-dicarbonyl compounds 1aa and 1ab
(entries27 and 28). Similarly, the oxidation of 2,2,3,3-tetrafluoro-1,4-
diol derivative 2ac took place very smoothly to afford the
corresponding 1,4-dicarbonyl compound 1ac in high yield (entry29).
In this way, the newly developed oxidation was found to be
much more effective for various types of fluorinated alcohols.
As shown in entries 1, 2, 5, 8, 10, the alcohols having an
electron-donating group (MeO) as well as an electron-withdraw-
ing group (Cl, NO2, CF3) on the benzene ring could participate very
well in the oxidation, though isolated yields are very low in several
I
OAc
AcO
OAc
I
+
SO3Na
2
-
CrO3/H2SO4/Acetone
O
Cr2O7
N
8
+
H
2
O
Oxone®
(2KHSO5•KHSO4•K2SO4)
6 : PDC
7 : Jones reagent
5 : Dess-Martin periodinane
Fig. 2. Various oxidizing reagents.
Table 1
Investigation of the reaction conditions.
I
8 (X mol%)
OH
O
Oxone® (Y eq.)
Unidentified
Products
+
SO3Na
Solvent, Temp., Time
F3C
R
F3C
R
8
2
1
Oxone® : 2KHSO5•KHSO4•K2SO4
.
Entry
R
8
Oxone1 Y/eq.
Solvent
Temp.a/8C
Time/h
Yield of 1b/%
Recovery
of 2b/%
Unidentified
productsb/%
X/mol%
1
2
3
4
5
6
7
8
Ph (a)
Ph (a)
Ph (a)
Ph (a)
Ph (a)
Ph (a)
Ph (a)
Ph (a)
1
1
1
2
2
2
5
5
0.6
0.6
0.6
0.6
0.6
0.9
0.9
0.9
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
70
70
70
70
90
90
90
90
3
12
24
24
12
12
12
18
39
55
43
43
33
28
10
2
2
2
3
3
2
3
3
2
52
54
61
68
86
94
97 (40)c
0
9
10
11
12
13
n-C9H19 (b)
n-C9H19 (b)
n-C9H19 (b)
n-C9H19 (b)
n-C9H19 (b)
5
5
0.9
0.9
0.9
0.9
0.9
CH3CN
90
90
18
24
24
24
24
38
48
52
17
2
6
2
2
6
7
CH3CN
42
5
CH3NO2
CH3NO2
CH3NO2
90
75
5
110
110
90
92 (68)c
10
0
a
Bath temperature.
b
c
Determined by 19F NMR. Values in parentheses are of isolated yield.
Low yields were due to the high volatility of the products.

Y. Tanaka et al. / Journal of Fluorine Chemistry 137 (2012) 99–104
101
Table 2
The oxidation of various types of fluorinated alcohols.
O
F2
C
8 (5 mol%), Oxone® (0.9 eq.), CH3CN, 90 °C, 18 h (Method A)
HO OH
Rf
OH
O
Ph
+
Ph
C
or
F2
R
Rf
R
Rf
R
8 (10 mol%), Oxone® (0.9 eq.), CH3NO2, 110 °C, 24 h (Method B)
O
2
1
9
1ac
.
Entry
Rf
R
Method
Yielda/% of 1
Yielda/% of 9
Recoverya/% of 2
Referencesb
1
2
CF3
Ph
(a)
(c)
(d)
(e)
(f)
A
A
A
A
A
A
A
A
B
A
A
A
B
B
B
B
B
B
A
A
A
A
A
A
A
A
A
B
97 (40)c
99 (83)
97 (83)
96 (80)
89 (83)
97 (59)
98 (48)c
47 (83)d
Quant. (97)
59 (44)c,e,f
75 (52)e
86 (62)
93 (80)
92 (68)
90
0
0
0
0
0
0
0
0
0
0
0
0
0
0
7
0
0
0
15
0
0
0
0
0
0
0
0
0
0
[39]
[40]
[40]
[40]
[41]
[42]
[43]
[41]
[44]
[15]
[41]
[39]
[45]
[39]
[13]
[46]
CF3
p-MeOC6H4
m-MeOC6H4
o-MeOC6H4
p-ClC6H4
m-ClC6H4
o-ClC6H4
p-O2NC6H4
o-O2NC6H4
p-F3CC6H4
(E)-PhCH5CH
PhCBB C
Trace
3
CF3
3
4
CF3
4
5
CF3
8
6
CF3
(g)
(h)
(i)
3
7
CF3
3
8
CF3
49
9
CF3
(j)
0
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
CF3
(k)
(l)
40
CF3
6
CF3
(m)
(n)
(b)
(o)
(p)
(q)
(r)
3
CF3
n-C6H13CBB C
n-C9H19
0
CF3
0
CF3
PhCH2CH2
PhCH(Me)
p-(t-Bu)C6H4CH2CH(Me)
CH25CH–(CH2)8
Ph
Trace
CF3
92
Trace
CF3
92 (86)
84
0
0
0
0
0
0
0
0
0
0
3
0
New compound
CF3
[47]
n-C4F9
n-C4F9
n-C4F9
n-C4F9
n-C4F9
n-C4F9
C2F5
CHF2
CF2CO2Et
CF2CO2Et
(s)
94 (76)e
98 (90)e
97 (89)e
93 (89)e
96 (80)e
88 (72)e
94e
[48]
p-MeC6H4
p-MeOC6H4
p-ClC6H4
o-ClC6H4
(E)-PhCH5CH
Ph
(t)
[49]
(u)
(v)
(w)
(x)
(y)
(z)
(aa)
(ab)
New compound
New compound
New compound
[50]
[18]
[51]
[39]
[52]
Ph
93e
Ph
97 (83)
Quant. (83)
n-C9H19
29
(ac)
A
98 (71)g,h
0
0
[53]
OH
F2
C
Ph
OH
Ph
C
F2
2ac
a
Determined by 19F NMR. Values in parentheses are of isolated yield.
The references for known compounds are listed.
b
c
Low yields were due to the high volatility of the products.
The reason that the isolated yield was higher than the one determined by 19F NMR is because the hydrate was converted into the ketone during the silica gel column
d
chromatography.
e
The reaction was carried out for 24 h.
f
Ten mol% of pre-IBS was used.
g
The product, 1ac was obtained.
The reaction was carried out using 20 mol% of pre-IBS and 1.8 equiv. of Oxone1
h
.
According to the literature, oxidation of 2a, 2b, 2m, and 2aa under
the influence of 3.7 equiv. of Dess–Martin periodinane 5 in CH2Cl2
at room temperature for 3 h gives the corresponding ketones 1a,
1b, 1m, and 1aa in 76%, 93%, 90%, and 85%, respectively (Scheme 1,
Eqs. (1)–(4)) [39]. These facts indicate that the present oxidation is
comparable to Dess–Martin oxidation.
In order to prove the great utility of the present oxidation, we
also examined PDC or Swern oxidation for some of fluorinated
alcohols [54a–d] (Table 3).
In the case of the oxidation of the alcohols having an aryl group
as R, both PDC as well as Swern oxidation proceeded very smoothly
to give the corresponding ketone 1 as well as hydrate 9 in high to
OH
Ph
O
OH
n-C9H19
O
5 (3.7 eq.)
5 (3.7 eq.)
(eq. 1)
(eq. 3)
(eq. 2)
(eq. 4)
CH2Cl2, r.t., 3 h
CH2Cl2, r.t., 3 h
F3C
F3C
F3C
F3C
Ph
F3C
Ph
F3C
n-C9H19
76%
93%
2a
1a
2b
1b
OH
O
OH
O
O
O
5 (3.7 eq.)
5 (3.7 eq.)
CH2Cl2, r.t., 3 h
C
OEt CH2Cl2, r.t., 3 h Ph
85%
C
OEt
F2
F2
1aa
Ph
Ph
90%
2m
2aa
1m
Scheme 1. Oxidation of various fluorinated alcohols with Dess–Martin periodinane 5.

102
Y. Tanaka et al. / Journal of Fluorine Chemistry 137 (2012) 99–104
Table 3
PDC and Swern oxidation of various types of fluorinated alcohols.
PDC (1.2 eq.), CH Cl , reflux, 24 h
OH
O
PDC Oxidation :
HO OH
Rf
2
2
+
(COCl)2 (2.0 eq.), DMSO (4.0 eq.), Et N (6.0 eq.), CH2Cl2, -60 °C, 3 h
Swern Oxidation :
R
Rf
R
3
Rf
R
2
9
1
.
Entry
Rf
R
PDC oxidation
Swern oxidation
Yielda/% of 1
Yielda/% of 9
Recoverya/% of 2
Yielda/% of 1
Yielda/% of 9
Recoverya/% of 2
1
2
CF3
Ph
(a)
(c)
62
29
0
–
5
0
0
0
0
0
0
0
3
0
93
7
0
CF3
p-MeOC6H4
p-ClC6H4
p-O2NC6H4
p-F3CC6H4
(E)-PhCH5CH
PhCBB C
Quant.
–
Quant.
97
0
0
3
CF3
(f)
–
2
0
4
CF3
(i)
90
2
31
46
18
4
5
CF3
(k)
(l)
Quant.
41
0
85
10
6
CF3
0
95
3
0
7
CF3
(m)
(n)
(b)
(aa)
(ab)
0
0
87
0
0
8
CF3
n-C6H13CBB C
n-C9H19
Ph
7
0
Complex mixture
9
CF3
61
34
0
17
91
46
0
0
0
32
0
10
11
CF2CO2Et
CF2CO2Et
94
n-C9H19
58
40
0
a
Determined by 19F NMR.
excellent yields (entries 1–5, 10). On the other hand, PDC oxidation
of the allylic alcohol 2l and the propargylic alcohols 2m, 2n took
place very sluggishly to give the desired ketones 1l, 1m, and 1n in
very low yields (entries 6–8). In these cases, not only the
corresponding hydrates were not obtained, but also the starting
alcohols were not recovered at all. In sharp contrast to the PDC
oxidation, Swern oxidation of 2l and 2m afforded the corresponding
ketones in excellent yields (entries 6 and 7), while 2n did not lead to
the satisfactory result (entry 8). Furthermore, the fluorinated
alcohols having an alkyl group as R were found to be less reactive
under the PDC as well as Swern oxidation conditions, the starting
alcohols being recovered in 30–40% (entries 9 and 11).
Finally, we attempted the hypervalent iodine(V)-catalyzed
oxidation in a large scale (Scheme 2). Thus, 5.16 g of 1-(4-
methoxyphenyl)-2,2,2-trifluoroethanol (2c, 25.1 mmol), 13.8 g of
Oxone1 (22.5 mmol), and 0.41 g of 8 (1.25 mmol) were dissolved in
CH3CN, and the wholewas heated at90 8C for18 h. Afterthe reaction
mixture was allowed to cool to room temperature, the whole was
filtered and the filtrate was concentrated in vacuo. The residue was
purified by silica gel column chromatography to give 4.61 g
(22.6 mmol) of the corresponding ketone 1c in 90% yield. In this
way, the scale-up did not influence for the reaction efficiency at all.
In summary, we have demonstrated the hypervalent iodine(V)-
catalyzed oxidation for various types of fluoroalkylated alcohols,
compared with Dess–Martin, PDC and Swern oxidation. As a result,
it was revealed that the newly developed oxidation could be
applied for almost all types of fluorinated alcohols, and it was
comparable to Dess–Martin oxidation, while PDC and Swern
oxidation could not be employed for allylic, propargylic alcohols as
well as the alcohols having an aliphatic side chain as R.
Additionally, the present oxidation could be applied for a large-
scale reaction without any decrease of the reaction efficiency.
The present oxidation also has much more advantages, like
safety, environmental load-reducing and inexpensive system, very
mild reaction conditions, easy workup, commercial availability of
the reagents, and so on.
In this way, we have established very efficient and practical
oxidation method for various types of fluorinated alcohols, which
may be employed in a laboratory as well as an industry.
3. Experimental
1H and 13C NMR spectra were measured with a JEOL JNM-AL400
(399.65 MHz for 1H and 100.40 MHz for 13C) spectrometer in a
chloroform-d (CDCl3) solution with tetramethylsilane as an
internal reference. A JEOL JNM-AL400 (376.05 MHz) was used to
measure 19F NMR spectra in CDCl3 using CFCl3 as an internal
standard. Infrared spectra (IR) were taken on a Jasco FT/IR-
4100type A spectrometer as film on a NaCl plate. High resolution
mass spectra were taken with a JEOL JMS-700 MS spectrometer.
Column chromatography was carried out on silica gel (Wako gel C-
200) and TLC analysis was performed on silica gel TLC plates
(Merck, Silica gel 60 F254).
All reactions were carried out under an atmosphere of argon.
Anhydrous tetrahydrofuran (THF) were purchased from Wako
Pure Chemical Industries, Ltd. All chemicals were of reagent grade
and, if necessary, were purified in the usual manner prior to use.
3.1. Preparation of sodium 2-iodobenzenesulfonate (8)
To a stirred suspension of 2-aminobenzenesulfonic acid (5.0 g,
28.9 mmol) and crushed-ice (20 g) in concentrated HCl (10 mL)
was added NaNO2 (2.09 g, 30.3 mmol) in water (20 mL) slowly at
0 8C, and the whole was stirred for 20–30 min at below 5 8C.
(Immediate precipitation of the diazonium salt was observed.) A
solution of NaI (4.76 g, 31.8 mmol) in water (20 mL) was then
added slowly with stirring at 0 8C. After the addition was complete,
stirring was continued at 0 8C for 1 h, at room temperature for 1 h,
and at 50 8C for 12 h to remove all N2. The mixture was cooled to
room temperature, then concentrated in vacuo. The residue was
recrystallized by distilled water, and thus obtained solid was
washed with cold EtOH and Et2O to afford the desired sodium 2-
iodobenzenesulfonateÁH2O (6.10 g, 18.8 mmol, 65%).
I
8 (0.41 g, 1.25 mmol)
SO3Na
Oxone® (13.8 g, 22.5 mmol)
OH
O
F3C
F3C
CH3CN, 90 °C, 18 h
OMe
OMe
3.2. Preparation of the fluorinated alcohols 2
2c
(5.16 g, 25.1 mmol)
1c
90% isolated yield
(4.61 g, 22.6 mmol)
Typical procedure:
a mixture of 10-undecenal (1.68 g,
10 mmol) and CF3SiMe3 (1.71 g, 1.9 mL, 12 mmol) in 15 mL of
Scheme 2. A catalytic oxidation in a large scale.
THF, which was cooled to 0 8C, was treated with 1 M THF solution

Y. Tanaka et al. / Journal of Fluorine Chemistry 137 (2012) 99–104
103
of TBAF (15 mol%, 15 mL, 1.5 mmol). The reaction mixture was
brought to room temperature and stirred for 3 h. The resulting
silyloxy compound was then hydrolyzed with aqueous HCl. Then,
the mixture was extracted with ether (15 mL Â 3), dried over
anhydrous Na2SO4, and concentrated in vacuo. The residue was
purified by silica gel column chromatography (eluent: hexane/
EtOAc = 7/1) to give 1,1,1-trifluoro-11-dodecen-2-ol (2r) (1.77 g,
7.43 mmol, 74%).
1H), 3.32 (m, 1H), 7.15 (d, J = 8.39 Hz, 2H), 7.38 (d, J = 8.39 Hz, 2H);
19F NMR (CDCl3, CCl3F)
d
À78.35 (s, 3F); 13C NMR (CDCl3)
d 16.11,
31.65, 34.75, 37.89, 43.17, 116.12 (q, J = 292.87 Hz), 120.49,
125.84, 135.18, 150.01, 195.13 (q, J = 33.60 Hz); IR (neat) 2965,
2871, 1759, 1518, 1462, 1365, 1290, 1268, 1203, 1153, 1109 cmÀ1
;
HRMS (FAB+) Calcd for C15H19F3O (M+): 272.1388, Found
272.1378.
2r: 1H NMR (CDCl3)
d
1.30–1.38 (m, 12H), 1.53–1.71 (m, 2H),
3.6. 2,2,3,3,4,4,5,5,5-Nonafluoro-1-(4-methoxyphenyl)-1-pentanone
2.04 (q, J = 7.10 Hz, 2H), 2.32 (br s, 1H), 3.84–3.94 (m, 1H), 4.93
(dm, J = 9.99 Hz, 1H), 4.99 (ddt, J = 16.78, 1.40, 1.40 Hz, 1H), 5.81
(1u)
(ddt, J = 16.78, 9.99, 6.39 Hz, 1H); 13C NMR (CDCl3)
d
25.23, 29.22,
29.40, 29.52, 29.67, 29.68, 29.90, 70.86 (q, J = 30.86 Hz), 114.48,
125.56 (q, J = 281.02 Hz), 126.96, 139.53; 19F NMR (CDCl3, CFCl3)
Yield: 89%; 1H NMR (CDCl3)
d 3.90 (s, 3H), 6.98 (d, J = 8.19 Hz,
2H), 8.06 (d, J = 8.19 Hz, 2H); 19F NMR (CDCl3, CFCl3)
d
À125.63 (s,
d
2F), À122.34 (s, 2F), À113.02 (s, 2F), À81.44 (d, J = 9.78 Hz, 3F); 13
C
À80.55 (d, J = 7.10 Hz, 3F); IR (neat) 3376, 3078, 2928, 2857, 1641,
1466, 1392, 1279, 1172, 994, 910, 847, 723, 695 cmÀ1; HRMS (EI)
Calcd for (M+) C12H21F3O 238.1544, Found 238.1544.
NMR (CDCl3) d 55.96, 105.84–114.39 (m, 3C), 114.71, 117.75 (qt,
J = 285.70, 33.08 Hz), 124.75 (t, J = 2.06 Hz), 133.33, 165.80, 181.70
(t, J = 25.20 Hz); IR (neat) 3016, 2975, 2943, 2848, 1697, 1603,
1514, 1465, 1428, 1356, 1317, 1237, 1137 cmÀ1; HRMS (FAB+)
Calcd for C12H7F9O2 (M+): 354.0302, Found 354.0302.
3.3. 1,1,1-Trifluoro-4-(4-tert-butylphenyl)-3-methylbutan-2-ol (2q)
Yield: 95% (d.r. ca. 56:44) 1H NMR
d
0.85 and 0.92 (d, J = 6.79 and
3.7. 2,2,3,3,4,4,5,5,5-Nonafluoro-1-(4-chlorophenyl)-1-pentanone
d, J = 6.79 Hz, 3H), 1.20 (s, 9H), 2.00–2.15 (m, 1H), 2.25–2.95 (m,
3H), 3.62–3.77 (m, 1H), 6.99 and 7.01 (d, J = 2.40 Hz and d,
J = 2.60 Hz, 2H), 7.20 and 7.22 (d, J = 2.40 Hz and d, J = 2.60 Hz, 2H);
(1v)
Yield: 89%; 1H NMR (CDCl3)
J = 8.99 Hz, 2H); 19F NMR
À125.71 to À125.63 (m, 2F), À122.24 to
À122.33 (m, 2F), À113.48 (t, J = 24.07 Hz, 2F), À81.40 (t,
J = 19.55 Hz, 3F); 13C NMR
105.81–114.25 (m, 3C), 117.63 (qt,
J = 287.65, 33.03 Hz), 129.87, 130.17 (t, J = 2.51 Hz), 131.94,
142.84, 182.52 (t, J = 26.05 Hz); IR (neat) 1713, 1590, 1491,
1407, 1356, 1237, 1138 cmÀ1; the molecular ion peak was not
detected in HRMS.
d 7.52 (d, J = 8.99 Hz, 2H), 8.01 (d,
19F NMR (CDCl3, CCl3F)
J = 4.14 Hz, 3F); 13C NMR(CDCl3)
d
À76.33 and À75.55 (d, J = 4.14 Hz, and d,
13.24 and 15.62, 31.69 and
d
d
31.70, 34.70 and 36.42, 35.17 and 37.46, 39.75, 71.68 and 74.15 (q,
J = 29.48 Hz and q, J = 29.22 Hz), 125.63 and 125.82, 125.85 and
125.87 (q, J = 282.96 Hz and q, J = 282.96 Hz), 129.07 and 129.37,
136.69 and 136.74, 149.41 and 149.64; IR (neat) 3348, 2964, 2871,
1911, 1800, 1710, 1662, 1516, 1464, 1364, 1271, 1166 cmÀ1; HRMS
(FAB+), Calcd for C15H21F3O (M+): 274.1544, Found 274.1552.
d
3.8. 2,2,3,3,4,4,5,5,5-Nonafluoro-1-(2-chlorophenyl)-1-pentanone
3.4. Typical procedure for the hypervalent iodine(V)-catalyzed
oxidation
(1w)
Yield: 80%; 1H NMR (CDCl3)
3H); 19F NMR
d 7.35–7.43 (m, 1H), 7.48–7.58 (m,
Method A: a mixture of 2,2,2-trifluoro-1-(4-methoxypheny-
l)ethanol (2c) (0.206 g, 1.0 mmol) and sodium 2-iodobenzene-
sulfonate (8) (as monohydrate, 0.016 g, 0.05 mmol, 5 mol%),
powdered Oxone1 (0.554 g, 0.9 mmol) in CH3CN (5 mL) was
stirred at 90 8C under the atmosphere of air. After stirring for
18 h, the reaction mixture was allowed to cool to room
temperature. The reaction mixture was filtered, being succes-
sively washed with ethyl acetate. The combined filtrates were
washed with water (3Â 10 mL), dried over anhydrous Na2SO4,
and concentrated in vacuo. The residue was purified by silica gel
column chromatography (eluent: hexane/EtOAc = 10/1) to give
2,2,2-trifluoro-1-(4-methoxyphenyl)-1-ethanone (1c) (0.165 g,
0.81 mmol, 81% yield).
d
À125.87 to À125.82 (m, 2F), À122.30 (s, 2F),
À115.54 to À115.45 (m, 2F), À81.45 to À81.43 (m, 3F); 13C NMR
d
106.08–113.24 (m, 3C), 117.62 (qt, J = 287.30, 32.90 Hz), 127.09,
129.31 (t, J = 3.75 Hz), 131.42, 133.05, 133.16, 133.86, 182.25 (t,
J = 28.00 Hz); IR (neat) 1767, 1591, 1438, 1356, 1238, 1138 cmÀ1
;
the molecular ion peak was not detected in HRMS.
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