Synthesis of highly substituted oxazoles through iodine(III)-mediated reactions of ketones with nitriles

Article abstract of DOI:10.3390/molecules170911046

In the presence of trifluoromethanesulfonic acid (TfOH) or bis(trifluoromethanesulfonyl) imide (Tf₂NH), iodosobenzene (PhI=O) efficiently promoted the reactions of dicarbonyl compounds as well as monocarbonyl compounds with nitriles to give 2,4-disubstituted and 2,4,5-trisubstituted oxazole in a single step under the mild conditions.

Full text of DOI:10.3390/molecules170911046

Molecules 2012, 17, 11046-11055; doi:10.3390/molecules170911046
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Synthesis of Highly Substituted Oxazoles through
Iodine(III)-Mediated Reactions of Ketones with Nitriles
Akio Saito †,*, Nao Hyodo and Yuji Hanzawa *
Laboratory of Organic Reaction Chemistry, Showa Pharmaceutical University,
3-3165 Higashi-tamagawagakuen, Machida, Tokyo 194-8543, Japan; E-Mail: a06097@ug.shoyaku.ac.jp
†
Current address: Division of Applied Chemistry, Institute of Engineering, Tokyo University of
Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588, Japan.
* Authors to whom correspondence should be addressed; E-Mails: akio-sai@cc.tuat.ac.jp (A.S.);
hanzaway@ac.shoyaku.ac.jp (Y.H.); Tel./Fax: +81-42-721-1569 (Y.H.).
Received: 6 August 2012; in revised form: 29 August 2012 / Accepted: 10 September 2012 /
Published: 13 September 2012
Abstract: In the presence of trifluoromethanesulfonic acid (TfOH) or bis(trifluoromethane-
sulfonyl)imide (Tf2NH), iodosobenzene (PhI=O) efficiently promoted the reactions of
dicarbonyl compounds as well as monocarbonyl compounds with nitriles to give
2,4-disubstituted and 2,4,5-trisubstituted oxazole in a single step under the mild conditions.
Keywords: single-step synthesis; iodine(III); oxazole; ketone; nitrile
1. Introduction
The synthesis of oxazole compounds has attracted a great deal of attention due to the widespread
application of oxazole derivatives in biologically active compounds as well as versatile building blocks
in organic synthesis [1–3]. For the purpose of synthesizing highly substituted oxazole compounds, an
intramolecular reaction, the so-called Robinson-Gabriel cyclocondensation of -acylamino ketones in
the presence of dehydrating reagents [H2SO4, POCl3, (CF3SO2)2O, and so on] has been commonly
employed [4–6]. As for the intermolecular approaches to highly substituted oxazoles, -diazo
ketones [7–9], -halo ketones [10,11], -sulfonyloxy ketones [12], and iodonium ylides of ketones [13]
have been used as a reactive synthetic intermediate. The preparation of -acylamino ketones or these
intermediates, however, requires a multi-step synthesis and/or the harsh reaction conditions. Although

Molecules 2012, 17
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the direct synthesis of oxazoles from simple ketones and nitriles with oxidants based on Tl(III) [14],
Hg(II) [15], Fe(III) [16], or Cu(II) [17] have been developed as a convenient procedure, these
procedures have met with the drawbacks including the limitation of the substrates and/or the use of
toxic oxidants.
Hypervalent iodine(III) reagents have gained increasing popularity in organic syntheses due to their
low toxicity, mild reactivity, high stability, easy handling, and so on [18]. Among them, [hydroxyl-
(tosyloxy)iodo]benzene (Koser’s reagent) and related reagents have been reported to work well for the
-sulfoxylations of ketones [19,20]. [Hydroxy(2,4-dinitrobenzenesulfonyloxy)iodo]benzene (HDNIB)
has been used in the stepwise and one-pot synthesis of oxazoles via the formation of -sulfonyloxy
ketones as intermediate from simple ketones [21]. In addition, phenyliodine(III) diacetate (PIDA) with
trifluoromethanesulfonic acid (TfOH) [22] or the iodoarene-oxone-TfOH system [23] efficiently
promoted the direct synthesis of oxazoles from monocarbonyl compounds, such as alkyl aryl ketones
with nitriles. To the best of our knowledge, however, there is no report about the direct synthesis of
oxazoles from simple dicarbonyl compounds and nitriles [21,24,25]. As a part of our study on the
iodine(III)-mediated synthesis of heterocycles [26,27], we carried out research on iodine(III) reagents
for the direct synthesis of oxazoles from monocarbonyl or dicarbonyl compounds. In this article, we
describe a single-step synthesis of highly substituted oxazoles by the reaction of ketones with nitriles
in the presence of iodosobenzene (PhI=O) and a Brønsted acid.
2. Results and Discussion
2.1. Evaluation of Oxidants for the Direct Synthesis of Oxazole
At the outset, we focused on the investigation of reactive oxidants for the reaction of monocarbonyl
compounds with nitriles as shown in Table 1. In the presence of PIDA (1.2 equiv.) with TfOH (4.5 equiv.),
the reaction of acetophenone (1a) in acetonitrile (MeCN) afforded the oxazole 2a in 94% yield at
80 °C for 2 h (entry 1) [23], albeit low yield (22%) at ambient temperature for 3 h (entry 2). Exploring
milder conditions, we examined the oxidants which were prepared from miscellaneous Brønsted acids
(1.5–3.0 equiv.) and PhI=O (1.5 equiv.) [28,29], in the reaction of 1a in MeCN (entries 3–8). Although
the use of p-toluenesulfonic aicd (TsOH) gave -tosyloxy ketone 3 as a main product (entry 3), the other
acids led to the desired formation of oxazole compound 2a (entries 4–8). Thus, 3.0 equiv. TfOH
showed the similar results to entry 1 (entry 7) and 3.0 equiv. bis(trifluoromethane-sulfonyl)imide
(Tf2NH) produced a good yield of 2a (86%) after 3 h at ambient temperature (entry 9). It should be
mentioned that the use of 10 equiv. of MeCN in 1,2-dichloroethane instead of MeCN solvent
decreased the yield of 2a, even under the similar conditions mediated by PhI=O with TfOH or Tf2NH.
For the formation of oxazole 5a from -keto ester 4a in MeCN, PhI=O/Tf2NH system turned out to
display superior activity to iodine(III) reagents/TfOH (Table 2). Thus, PhI=O (1.5 equiv.) with Tf2NH
(3.0 equiv.) improved the yield of 5a to 51% at 80 °C for 16 h (entry 4), compared to the use of
1.5 equiv. PIDA or 1.5 equiv. PhI=O in the presence of TfOH (3.0–4.5 equiv.), in which 4a were
converted to 5a in only 4–7% yields even at 80 °C for 24–25 h (entries 1 and 2). In the case of the
extension of the reaction time (72 h) or the increase in the amount of Tf2NH (6.0 equiv.), 5a was
obtained in 79–81% yields (entries 5 and 6).

Molecules 2012, 17
Table 1. Evaluation of oxidants for the reaction of acetophenone (1a) in MeCN.
11048
Entry Oxidant (equiv)
Acid (equiv.)
TfOH (4.5)
TfOH (4.5)
TsOH (1.5)
HBF4/Et2O (1.5)
TfOH (1.5)
Tf2O (1.5)
Temp. (°C) Time (h) 2a (%) [a]
1 [b]
2
PIDA (1.2)
PIDA (1.2)
PhI=O (1.5)
PhI=O (1.5)
PhI=O (1.5)
PhI=O (1.5)
PhI=O (1.5)
PhI=O (1.5)
PhI=O (1.5)
80
rt
2
3
94
22
-
3
80
80
80
80
80
80
rt
18
18
18
18
3
(3 69)
4
54
69
21 [c]
94
40
86
5
6
7
TfOH (3.0)
Tf2NH (1.5)
8
3
(1a 16)
9
Tf2NH (3.0)
3
[a] Yields were determined by H-NMR analysis; [b] Ref. [21]; [c] 2,4-Dimethyl-6-phenylpyrimidine
1
was obtained in 38% yield.
Table 2. Evaluation of oxidants for the reaction of benzoylacetate 4a in MeCN.
Entry
Oxidant
PIDA
Acid
TfOH [b]
TfOH
Time (h)
5a (%) [a]
1
2
3
4
5
6
24
25
115
16
72
3
4
PhI=O
PhI=O
PhI=O
PhI=O
PhI=O
7
TfOH
41
51
79
81
Tf2NH
Tf2NH
Tf2NH [c]
[a] Yields were determined by 1H-NMR analysis; [b] TfOH: 4.5 equiv.; [c] TfOH: 6.0 equiv.
2.2. Scope of the Direct Synthesis of Oxazoles Using PhI=O with TfOH or Tf2NH
The scope of monocarbonyl compounds 1 and dicarbonyl compounds 4 by means of the PhI=O
(1.5 equiv.)-mediated procedure A (acid: 3.0 equiv. TfOH), B (acid: 3.0 equiv. Tf2NH), or C (acid:
6.0 equiv. Tf2NH) was shown in Tables 3 and 4 and Scheme 1. Procedure A could be applied to the
reactions of monocarbonyl compounds 1a–g in MeCN, and the corresponding oxazoles 2a–g were
obtained in 53–94% yields at 80 °C (Table 3, entries 1, 3–6, 8, and 9). Furthermore, procedure B
brought about the formation of 2a or 2e at ambient temperature (entries 2 and 7). In the case of
benzoylacetonitrile (1g), an increase in the amount of Tf2NH (procedure C) improved the yield of 5f
up to 69% at ambient temperature for 24 h (entry 11). Although the dicarbonyl compounds 4a,b
required the long time (72–139 h) to give good yields of products through procedure B (entries 12 and 14),
procedure C reduced the reaction times (3 h) giving rise to 5a–c in 67–83% yields (entries 13, 15 and
17). Bicyclic oxazole 5d could be formed by procedure C, albeit in only 40% yield after 167 h

Molecules 2012, 17
11049
(entry 18). Unfortunately, p-methoxyacetophenone and 4-phenyl-2-butanone did not give the desired
products with any of the procedures. By procedure A, the reaction of acetophenone (1a) in
propionitrile (EtCN) or benzonitrile (PhCN) instead of MeCN smoothly proceeded at 80 °C for 4 h to
yield the corresponding oxazole 6 or 7 in good yields (Scheme 1). The procedure C could be applied to
the reaction of dicarbonyl compounds 4a–c in EtCN or PhCN (Table 4).
Table 3. The reactions of 1 or 4 in MeCN by the means of procedures A, B, or C [a].
Entry
1
1 or 4
1a
1a
1b
1c
R1
R2
Procedure (°C)
(h)
3
2 or 5 Yield (%) [b]
Ph
H
A
B
A
A
A
A
B
A
A
B
C
B
C
B
C
B
C
C
80
rt
2a
2a
2b
2c
2d
2e
2e
2f
88
86
75
86
73
94
91
68
53
38
69
78
81
89
83
35
67
40
2
3
3
m-Me-C6H4
p-Cl-C6H4
p-NO2-C6H4
Ph
H
H
80
80
80
80
rt
3
4
3
5
1d
1e
H
3
6
Me
3
7
1e
2
8
1f
Ph
Ph
Cl
80
80
80
rt
49
20
20
24
72
3
9
1g
1g
1g
4a
4a
4b
4b
4c
CN
2g
2g
2g
5a
5a
5b
5b
5c
5c
5d
10
11
12
13
14
15
16
17
18
Ph
Ph
OEt
Ph
80
80
80
80
80
80
80
139
3
Me
Me
120
3
4c
4d
-(CH2)4-
167
[a] Procedure A: 3 equiv. TfOH was used as a Brønsted acid. Procedure B: 3 equiv. Tf2NH was used
as a Brønsted acid. Procedure C: 6 equiv. Tf2NH was used as a Brønsted acid; [b] Isolated yields.
Scheme 1. The reactions of 1a in EtCN or PhCN by the means of procedure A.

Molecules 2012, 17
Table 4. The reactions of 4a–c in EtCN or PhCN by the means of procedure C.
11050
Entry
4
R1
R2
R3
Et
(h)
2
2 or 5 Yield (%) [a]
1
2
3
4
5
6
4a
4a
4b
4b
4c
4c
Ph
OEt
8a
9a
8b
9b
8c
9c
83
72
89
67
56
60
Ph
Et
3
Ph
Ph
3
Ph
Et
3
Me
Me
20
Ph
20
[a] Isolated yields.
2.3. Mechanistic Considerations
Since it has been known that PhI=O reacts with two equiv. of TfOH in CH2Cl2 to produce to the
oxidant 10 [30], to better understand the present oxazole formation, we examined the reaction of
acetophenone (1a) with 10 (Scheme 2). Thus, under conditions similar to those of entry 7 in Table 1,
1a was treated with 10 (0.75 equiv.) instead of PhI=O (1.5 equiv.) and TfOH (3 equiv.) in MeCN to
give 2a in only 11% yield at 80 °C for 3 h. Therefore, 10 would not be considered to take part in the
present oxazole formation.
Scheme 2. Preparation of 10 and the reaction of 1a with 10.
On the basis of abovementioned observations and the previous reports about the iodine(III)-mediated
synthesis of oxazoles [21–23], the mechanism for the present oxazole formation from ketones 1 or 4
with nitriles as shown in Scheme 3 is proposed. That is, -iodanyl ketone Int-A, which is generated
from 1 or 4 with PhI=O and H-X (TfOH or Tf2NH), would be converted to Int-B by the Ritter-type
reaction with R3CN. Int-C generated by the reductive elimination of ArI might also be a possible
intermediate for the formation of Int-B, and the subsequent cyclization of Int-B gives oxazoles 2 or 5.
The formation of Int-A and/or Int-C is supported by the formation of -tosyloxy ketone 3 (69%) in
the case of TsOH as an acid (Table 1, entry 3) [19,23].

Molecules 2012, 17
Scheme 3. Proposed reaction mechanism of direct synthesis of oxazoles.
11051
3. Experimental
3.1. General
All starting materials and reagents were commercially available. Dried organic solvents were
purchased and used without further drying. Unless otherwise stated, all reactions were conducted under
an argon atmosphere. Melting points were measured on a Yanaco SP-M1 melting point apparatus
(Yanagimoto Co.) and were uncorrected. IR spectra were recorded on a HORIBA FT-710 FT-IR
1
13
spectrometer. H and C-NMR spectra were measured in CDCl3 with a Bruker AV300M FT NMR
spectrometer at 300 and 75 MHz, and the chemical shifts are given in ppm using CHCl3 (7.26 ppm) for
13
1H-NMR and CDCl3 (77.0 ppm) for C-NMR as an internal standard, respectively. Mass spectra and
HRMS were recorded by FAB method on a JMS-HX110 Mass spectrometer. Elemental analysis was
measured on a Perkin-Elmer 240B or Elemental Vavio EL. For the TLC analysis, Merck precoated
TLC plates (silica gel 60 F254) were used. Column chromatography was performed on Silica gel 60N
(63–200 m, Kanto Kagaku Co., Ltd.).
3.2. General Procedure for the Iodine(III)-Mediated Synthesis of Oxazoles
Ketone 1 or 4 (0.4 mmol) was added to a solution of iodosobenzene (132 mg, 0.6 mmol) and
trifluoromethanesulfonic acid (106 L, 1.2 mmol) or bis(trifluoromethanesulfonyl)imide (337 or
675 mg, 1.2 or 2.4 mmol), which were premixed in acetonitrile, propionitrile, or benzonitrile (2 mL) at
0 °C for 5 min, and the reaction mixture was stirred at ambient temperature or 80 °C until the
consumption of substrate by TLC analysis. The mixture was diluted with ether and filtered through a
short alumina column. After concentration of the filtrate to dryness, the subsequent purification gave
the corresponding oxazole 2 or 5. 2a [21], 2c [21], 2d [31], 2e [21], 6 [21], 7 [32], and 9a–c [33] were
identified by the comparison with 1H-NMR spectra reported in the appropriate literature.
2-Methyl-5-(3′-methylphenyl)oxazole (2b). Colorless oil. IR (neat)  cm−1; 3054, 2925, 2863, 1610,
1
1560, 1519, 784, 748. H-NMR (CDCl3)  2.38 (s, 3H), 2.51 (s, 3H), 7.02(d, J = 7.6 Hz, 1H), 7.18
(s, 1H), 7.28 (t, J = 7.6 Hz, 1H), 7.40 (d, J = 9.2 Hz, 2H). 13C-NMR (CDCl3)14.0, 21.4, 121.0,

Molecules 2012, 17
11052
121.6, 124.5, 128.0, 128.7, 128.9, 138.5, 151.2. FAB-LM m/z: 174.2 (M++H). FAB-HM Calcd for
C11H12NO: 174.0919, Found: 174.0906.
4-Chloro-2-methyl-5-phenyloxazole (2e). White solid. Mp 56 °C. IR (KBr)  cm−1; 3050, 3002, 2923,
2856, 1438, 1378. 1H-NMR (CDCl3)  2.50 (s, 3H), 7.30–7.36 (m, 1H), 7.41–7.46 (m, 2H), 7.83–7.84
13
(m, 2H). C-NMR (CDCl3)14.2, 124.8, 127.0, 128.7, 143.8, 159.4. FAB-LM m/z: 194.1 (M++H).
FAB-HM Calcd for C10H9ClNO: 194.0373, Found: 194.0383. Anal. Calcd for C10H8ClNO: C, 62.03;
H, 4.06; N, 7.23. Found: C, 62.21; H, 4.47; N, 7.23.
4-Cyano-2-methyl-5-phenyloxazole (2f). White solid. Mp 49 °C. IR (KBr)  cm−1; 3062, 2927, 2854,
2225. 1H-NMR (CDCl3)  2.56 (s, 3H), 7.48–7.50 (m, 3H), 7.89–7.92 (m, 2H). 13C-NMR (CDCl3)  13.9,
108.0, 113.8, 125.2, 125.5, 129.3, 130.9, 157.8, 161.1. FAB-LM m/z: 185.2 (M++H). Anal. Calcd for
C11H8N2O: C, 71.73; H, 4.38; N, 15.21. Found: C, 71.91; H, 4.39; N, 15.02.
4-Ethoxycarbonyl-2-methyl-5-phenyloxazole (5a). White solid. Mp 64 °C. IR (KBr)  cm−1; 3054,
3006, 2977, 2927, 2857, 1598, 1560, 1488. 1H-NMR (CDCl3)  1.38 (t, J = 7.1 Hz, 3H), 2.54 (s, 3H),
4.40 (q, J = 7.1 Hz, 2H), 7.43–7.45 (m, 3H), 8.02–8.05 (m, 2H). 13C-NMR (CDCl3) 13.9, 14.3, 61.3,
106.9, 127.1, 128.3, 128.3, 130.1, 155.3, 159.9, 162.2. FAB-LM m/z: 232.2 (M++H). FAB-HM Calcd
for C13H14NO3: 232.0974, Found: 232.0977. Anal. Calcd for C13H13NO3: C, 67.52; H, 5.67; N, 6.06.
Found: C, 67.80; H, 5.81; N, 5.89.
4-Benzoyl-2-methyl-5-phenyloxazole (5b). Colorless oil. IR (neat)  cm−1; 3031, 2965, 2927, 2927,
2856, 1710. 1H-NMR (CDCl3)  (s, 3H), 7.40–7.47 (m, 5H), 7.47–7.55 (m, 1H), 7.95–7.98 (m, 2H),
8.05–8.08 (m, 2H). 13C-NMR (CDCl3) ; 13.8, 127.3, 127.6, 128.1, 128.4, 130.0, 130.2, 132.9, 133.7,
137.5, 154.7, 159.0. FAB-LM m/z: 264.2 (M++H). FAB-HM Calcd for C18H14NO2: 264.1025, Found:
264.1014. Anal. Calcd for C17H13NO2: C, 77.55; H, 4.98; N, 5.32. Found: C, 77.38; H, 5.16; N, 5.40.
4-Acetyl-2,5-dimethyloxazole (5c). White solid. Mp 39 °C. IR (KBr)  cm−1; 1681. 1H-NMR (CDCl3) 
2.73 (s, 3H), 2.43 (s, 3H), 2.50 (s, 3H). 13C-NMR (CDCl3)  12.0, 13.6, 27.8, 134.5, 154.2, 158.4,
194.7. EI-LM m/z: 139.1 (M+). Anal. Calcd for C7H9NO2: C, 60.42; H, 6.52; N, 10.07. Found: C,
60.02; H, 6.16; N, 9.82.
6,7-Dihydro-2-methylbenzo[d]oxazole-4(5H)-one (5d). Colorless oil. IR (neat)  cm−1; 2952, 2927,
1
2854, 1682. H-NMR (CDCl3)  2.12–2.20 (m, 2H), 2.52 (s, 3H), 2.57 (t, J = 5.9 Hz, 2H), 2.81 (t,
J = 6.1 Hz, 2H). 13C-NMR (CDCl3)  14.4, 23.2, 23.8, 38.0, 144.2, 156.1, 165.9, 185.8. FAB-HM
Calcd for C8H10NO2: 152.0712, Found: 152.0697.
4-Ethoxycarbonyl-2-ethyl-5-phenyloxazole (8a). White solid. Mp 37 °C. IR (KBr)  cm−1; 3066, 2983,
2933, 2875, 1714, 1240, 1189. 1H-NMR (CDCl3)  1.38 (t, J = 7.1 Hz, 3H), 1.39 (t, J = 7.6 Hz, 3H), 2.88
(q, J = 7.6 Hz, 2H), 4.40 (q, J = 7.1 Hz, 2H), 7.42–7.47 (m, 3H), 8.01–8.04 (m, 2H). 13C-NMR
(CDCl3)  11.2, 14.3, 21.6, 61.3, 126.7, 127.1, 128.3, 130.0, 155.0, 162.2, 164.1. FAB-LM m/z: 264.2
(M++H). FAB-HM Calcd for C14H16NO3: 246.1130, Found: 246.1126. Anal. Calcd for C14H15NO3: C,
68.56; H, 6.16; N, 5.71. Found: C, 68.79; H, 6.06; N, 5.61.

Molecules 2012, 17
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4-Benzoyl-2-ethyl-5-phenyloxazole (8b). Colorless oil. IR (neat)  cm−1; 3064, 2981, 2937, 1656.
1H-NMR (CDCl3)  1.43 (t, J = 7.6 Hz, 3H), 2.92 (q, J = 7.6 Hz, 2H), 7.40–7.45 (m, 5H), 7.53–7.58
13
(m, 1H), 7.94–7.97 (m, 2H), 8.06–8.10 (m, 2H). C-NMR (CDCl3) 11.3, 21.7, 127.5, 127.7, 128.2,
128.5, 130.0, 130.4, 133.0, 133.7, 137.5, 154.5, 163.4. FAB-LM m/z: 278.2 (M++H). FAB-HM Calcd
for C18H16NO2: 278.1181, Found: 278.1177. Anal. Calcd for C18H15NO2: C, 77.96; H, 5.45; N, 5.05.
Found: C, 77.95; H,5.42; N,5.10.
1
4-Acetyl-2-ethyl-5-menyloxazole (8c). Colorless oil. IR (neat)  cm−1; 1685. H-NMR (CDCl3) 1.25
(t, J = 7.6 Hz, 3H), 2.42 (s, 3H), 2.50 (s, 3H), 2.68(q, J = 7.6 Hz, 2H). 13C-NMR (CDCl3) ; 11.1, 12.1,
21.4, 27.8, 134.4, 154.0, 162.7, 194.9. FAB-LM m/z: 154.1 (M++H). FAB-HM Calcd for C8H12NO2:
154.0868, Found: 154.0873.
3.3. Formation of -Tosyloxy Ketone 3 under the Iodine(III)-Mediated Conditions
Ketone 1a (47 L, 0.4 mmol) was added to a solution of iodosobenzene (132 mg, 0.6 mmol) and
p-toluenesulfonic acid monohydrate (114 mg, 0.6 mmol), which were premixed in MeCN (2 mL) at
0 °C for 5min, and the reaction mixture was stirred at 80 °C for 18 h. The mixture was diluted with
ether and filtered through a short alumina column. After concentration of the filtrate to dryness, the
subsequent purification gave 3 (73.2 mg, 0.25 mmol, 63%). Compound 3 was identified by the
comparison with the 1H-NMR spectrum reported in the literature [20].
4. Conclusions
We have demonstrated the single-step synthesis of highly substituted oxazoles from ketones and
nitriles by the use of iodosobenzene with trifluoromethanesulfonic acid or bis(trifluoromethane-
sulfonyl)imide. The present procedure could be applied not only to monocarbonyl compounds, but also
to dicarbonyl ones. In particular, we believe that the reactivity of iodosobenzene with bis(trifluoro-
methanesulfonyl)imide sheds light on a new possibility for the use of hypervalent iodine compounds in
organic synthesis.
Acknowledgments
This work was supported by Grant-in-Aid for Young Scientists (B), MEXT Japan (No 24790024).
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Sample Availability: Not available.
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