Synthesis of 2,5-disubstituted 1,3,4-oxadiazine and 1,3,4-thiadiazine from substituted acetophenones and acid hydrazides using [Hydroxyl(tosyloxy)iodo] benzene

Article abstract of DOI:10.1080/00397910802654716

A novel and direct method for the efficient synthesis of 2,5-disubstituted 1,3,4-oxadiazines from the reactions of [hydroxy(tosyloxy)iodo]benzene with substituted acetophenones, followed by the treatment with acid hydrazide and K2CO3, is reported. The met

Full text of DOI:10.1080/00397910802654716

This article was downloaded by: [University of Otago]
On: 11 September 2014, At: 16:52
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954
Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,
UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic
Organic Chemistry
Publication details, including instructions for
authors and subscription information:
http://www.tandfonline.com/loi/lsyc20
Synthesis of 2,5-Disubstituted
1,3,4-Oxadiazine and
1,3,4-Thiadiazine from
Substituted Acetophenones
and Acid Hydrazides Using
[Hydroxyl(tosyloxy)iodo]benzene
Nandkishor N. Karade a , Jeevan M. Kondre a
,
Sumeet V. Gampawar a & Sandeep V. Shinde a
a School of Chemical Sciences , Swami Ramanand
Teerth Marathwada University , Nanded,
Maharashtra, India
Published online: 01 Jun 2009.
To cite this article: Nandkishor N. Karade , Jeevan M. Kondre , Sumeet V. Gampawar
& Sandeep V. Shinde (2009) Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazine and
1,3,4-Thiadiazine from Substituted Acetophenones and Acid Hydrazides Using
[Hydroxyl(tosyloxy)iodo]benzene, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 39:13, 2279-2287, DOI:
10.1080/00397910802654716
To link to this article: http://dx.doi.org/10.1080/00397910802654716
PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the
information (the “Content”) contained in the publications on our platform.
However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness,
or suitability for any purpose of the Content. Any opinions and views
expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the
Content should not be relied upon and should be independently verified with
primary sources of information. Taylor and Francis shall not be liable for any
losses, actions, claims, proceedings, demands, costs, expenses, damages,
and other liabilities whatsoever or howsoever caused arising directly or
indirectly in connection with, in relation to or arising out of the use of the
Content.
This article may be used for research, teaching, and private study purposes.
Any substantial or systematic reproduction, redistribution, reselling, loan,
sub-licensing, systematic supply, or distribution in any form to anyone is
expressly forbidden. Terms & Conditions of access and use can be found at
http://www.tandfonline.com/page/terms-and-conditions

Synthetic Communications1, 39: 2279–2287, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802654716
Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazine
and 1,3,4-Thiadiazine from Substituted
Acetophenones and Acid Hydrazides Using
[Hydroxyl(tosyloxy)iodo]benzene
Nandkishor N. Karade, Jeevan M. Kondre, Sumeet V. Gampawar,
and Sandeep V. Shinde
School of Chemical Sciences, Swami Ramanand Teerth Marathwada
University, Nanded, Maharashtra, India
Abstract: A novel and direct method for the efficient synthesis of 2,5-
disubstituted 1,3,4-oxadiazines from the reactions of [hydroxy(tosyloxy)iodo]-
benzene with substituted acetophenones, followed by the treatment with acid
hydrazide and K2CO3, is reported. The methodology is also extended to the
synthesis of 5-aryl-6H-1,3,4-thiadiazin-2-amine by using thiosemicarbazide under
similar experimental conditions.
Keywords: Hydrazide, hypervalent iodine, 1,3,4-oxadiazine, a-tosyloxylation
INTRODUCTION
The 1,3,4-oxadiazines and 1,3,4-thiadiazine scaffolds play an important
role as a component of antihypertensive, anticholesteremic, antibacterial,
and antiviral agents.[1] They are also used in polycarbonate foams, hair
shampoos, and skin cosmetics.[2] There are a limited number of literature
reports for the general synthesis of 1,3,4-oxadiazines derivatives. The
cathodic reduction of semicarbazones of phenacyl bromides using
LiClO4–dimethylformamide (DMF) system is demonstrated for the
Received August 18, 2008.
Address correspondence to Dr. Nandkishor N. Karade, School of Chemical
Sciences, Swami Ramanad Teerth Marathwada University, Nanded 431606,
Maharashtra, India. E-mail: nnkarade@gmail.com
2279

2280
N. N. Karade et al.
Scheme 1. Synthesis of 2,5-disubstituted 1,3,4-oxadiazine.
synthesis of fused 1,3,4-oxadiazines.[3] Another report involves the
reaction of an excess of trifluoroacetic anhydride with arylaldehyde
dimethylhydrazone to form 3,4-dihydro-2H-1,3,4-oxadiazines.[4] 2-Aryl-
4H-1,3,4-oxadiazin-5(6H)-ones, which are known for the inhibition of
monoamine oxidase, are synthesized from the reaction of 1-aroyl-2,2-
bis(2-cyanoethyl)hydrazine with a-chloroacyl chloride.[5] Aromatic and
heteroaromatic acid hydrazides reacted with oxalyl chloride in benzene
or chloroform to give 2-aryl(hetaryl)-4H-1,3,4-oxadiazine-5,6-diones.[6]
Recently, the reaction of cyanoacetylhydrazine with a-bromoacetophe-
none has been reported for the synthesis of 5-phenyl-2-acetonitrilo-
1,3,4-oxadiazine.[7]
[Hydroxyl(tosyloxy)iodo]benzene (HTIB) is a versatile hypervalent
iodine(III) reagent useful for a-tosyloxylation of enolizable ketones.[8]
The resulting a-tosyloxyketone is known as an environmentally benign
alternative to the toxic and lachrymatory a-haloketones. Because it is
generally not necessary to isolate a-tosyloxyketone, it is utilized in situ
as a strategic precursor for the one-pot synthesis of a wide range of
Scheme 2.

2,5-Disubstituted 1,3,4-Oxadiazine
2281
heterocycles such as thiazoles, selenazoles, oxazoles, imidazoles, pyra-
zoles, and benzofurans.[9] The application of HTIB has been hitherto
unknown for the synthesis of 1,3,4-oxadiazines. In continuation of
our interest in hypervalent iodine reagents,[10] herein we report a
novel one-pot synthesis of 2,5-diaryl-6H-1,3,4-oxadiazine from various
acetophenones and acid hydrazides using HTIB as the key reagent
(Schemes 1 and 2).
RESULTS AND DISCUSSION
Initially, the reaction of acetophenone with HTIB followed by treatment
with benzoic hydrazide was carried out as a model reaction. In a typical
experimental procedure, a mixture of acetophenone (2 mmol) and HTIB
(2.2 mmol) was refluxed in CH3CN (15 mL) for 1 h. After the formation
of a-tosyloxyacetophenone as ascertained by thin-layer chromatography
(TLC), benzoic hydrazide (2 mmol) and K2CO3 (2 mmol) were added to
the reaction mixture and continued to reflux for an additional 6 h. The
progress of the reaction was again monitored by TLC and after the usual
workup procedure, the formation of 2,5-diphenyl-6H-1,3,4-oxadiazine in
74% yield was realized. The addition of K2CO3 in the latter stage of the
Table 1. Synthesis of 2,5-diaryl-6H-1,3,4-oxadiazine from substituted acetophe-
nones and acid hydrazides using HTIB and K2CO3 in CH3CN
Entry
R1
C6H5-
4-CH3C6H4- C6H5-
4-MeOC6H4- C6H5-
4-BrC6H4- C6H5-
4-ClC6H4- C6H5-
4-NO2C6H4- C6H5-
4-BrC6H4-
C6H5-
4-CH3C6H4- NH2
4-ClC6H4-
4-BrC6H4
R2
Z
Product Reaction time (h) Yield (%)
1
2
3
4
5
6
7
8
9
C6H5-
O
O
O
O
O
O
O
S
4a
4b
4c
4d
4e
4f
5
5
5
6
5
7
5
7
8
8
7
64
58
63
71
64
58
68
61
65
63
62
4-BrC6H4-
NH2
4g
4h
4i
S
S
S
10
11
NH2
NH2
4j
4k

2282
N. N. Karade et al.
Scheme 3.
reaction was necessary for the requisite cyclization reaction of acid
hydrazone of a-tosyloxyacetophenone to form 1,3,4-oxadiazine.
To demonstrate the generality of this method, we investigated the
scope of this reaction under the optimized conditions, and the results
are summarized in Table 1. As shown in Table 1, this method is equally
effective for a wide range of acetophenones with both electron-donating
and electron-withdrawing substituents.
The methodology was also extended to the synthesis of 5-aryl-6H-
1,3,4-thiadiazin-2-amine from the reactions of substituted acetophenones
with thiosemicarbazides using HTIB under similar experimental condi-
tions (Scheme 3). In these cases (Table 1), the formation of 5-aryl-6H-
1,3,4-thiadiazin-2-amine again took place in good to excellent yields. This
method is more superior and flexible than the literature report of the het-
erocyclization of thiosemicarbazide with a-haloketone, which is a poten-
tially toxic and lachrymatory compound.[11]
CONCLUSION
In summary, we have developed a general and direct method for an
expeditious, one-pot synthesis of 2,5-diaryl-6H-1,3,4-oxadiazine and
5-aryl-6H-1,3,4-thiadiazin-2-amine from readily available substituted
acetophenones and acid hydrazides using HTIB as the key oxidant. This
method does not involves the use of any lachrymatory compounds, which
are otherwise commonly reported in the literature for the synthesis of
1,3,4-oxadiazine and 1,3,4-thiadiazine derivatives.
EXPERIMENTAL
The required chemicals were purchased from commercial sources and
were used without further purification. HTIB was prepared according
to the literature procedure starting from (diacetoxyiodo)benzene.[12] 1
H
and 13C NMR spectra were recorded on a Bruker 400-MHz instrument
using tetramethylsilane (TMS) as an internal standard in CDCl3. Infrared

2,5-Disubstituted 1,3,4-Oxadiazine
2283
(IR) spectra were recorded on a Shimadzu Fourier transform (FT)–IR
spectrophotometer.
General Procedure for the Synthesis of 2,5-Diaryl-6H-1,3,4-Oxadiazine
A mixture of the appropriate acetophenone (3 mmol) and HTIB (3 mmol)
in CH3CN (10 mL) was refluxed for 1–2 h. After the formation of
a-tosyloxyketone as ascertained by thin-layer chromatograpy (TLC), a
mixture of benzoic hydrazide (3 mmol) and K2CO3 (3 mmol) was added
to the reaction mixture, which continued to reflux for an additional
6–8 h. The progress of the reaction was again monitored by TLC. After
completion of the reaction, the mixture was diluted with water and
extracted with CHCl3 (3 ꢀ 15 mL). The combined organic layers were
dried over Na2SO4 and concentrated under reduced pressure to obtain
the crude products, which were purified by column chromatography.
General Procedure for the Synthesis of 5-Aryl-6H-1,3,4-thiadiazin-
2-Amine
The experimental procedure for the synthesis of 5-aryl-6H-1,3,4-thiadia-
zin-2-amine is identical as mentioned previously for the synthesis of 2,5-
diaryl-6H-1,3,4-oxadiazine except that the use of thiosemicarbazide in
place of benzoic hydrazide is required.
Characterization of the Products
2,5-Diphenyl-6H-1,3,4-oxadiazine (4a)
1H NMR (400 MHz, CDCl3): d ¼ 5.59 (s, 2H, OCH2), 7.46–7.53 (m, 4H,
ArH), 7.58–7.65 (m, 2H, ArH), 7.97 (d, 2H, J ¼ 9.6 Hz, ArH), 8.15 (d,
2H, J ¼ 8 Hz, ArH). 13C NMR (CDCl3): d ¼ 66.52, 127.87, 128.50,
128.94, 129.42, 130.01, 133.41, 133.97, 134.28, 166.09, 192.15. IR (KBr,
cmꢁ1): 3020, 2934, 1600, 1573, 1215, 792. Anal. calcd. for C15H12N2O:
C, 76.25; H, 5.12; N, 11.86. Found: C, 76.28; H, 5.13; N, 11.83.
2-Phenyl-5-p-tolyl-6H-1,3,4-oxadiazine (4b)
1H NMR (CDCl3): d ¼ 2.42 (s, 3H, ArCH3), 5.54 (s, 2H, OCH2), 7.26 (t,
1H, J ¼ 10.4 Hz, ArH), 7.45 (t, 2H, J ¼ 10.4 Hz, ArH), 7.57 (m, 2H,

2284
N. N. Karade et al.
J ¼ 8 Hz, ArH), 7.84 (d, 2H, J ¼ 10.8 Hz, ArH), 8.12 (d, 2H, J ¼ 10.4 Hz,
ArH). 13C NMR (CDCl3): d ¼ 191.71, 166.10, 144.90, 133.35, 131.78,
130.14, 129.59, 129.47, 128.46, 127.95, 66.44, 21.81. IR (KBr, cmꢁ1):
3020, 2983, 1607, 1559, 1476, 1215, 793. Anal. calcd. for C16H14N2O:
C, 76.78; H, 5.64; N, 11.19. Found: C, 76.79; H, 5.67; N, 11.17.
5-(4-Methoxyphenyl)2-phenyl-6H-1,3,4-oxadiazine (4c)
1H NMR (CDCl3): d ¼ 3.87 (s, 3H, OCH3), 5.52 (s, 2H, OCH2), 6.94 (d,
2H, J ¼ 11.6 Hz, ArH), 7.42–7.57 (m, 3H, ArH), 7.93 (d, 2H, J ¼ 11.6 Hz,
ArH), 8.12 (d, 2H, J ¼ 9.2 Hz, ArH). 13C NMR (CDCl3): d ¼ 55.57,
66.27, 114.10, 127.29, 128.47, 128.93, 129.50, 130.18, 133.35, 164.07,
166.14, 190.59. IR (KBr, cmꢁ1): 3019, 2937, 1602, 1514, 1452, 1215,
797. Anal. calcd. for C16H14N2O2: C, 72.16; H, 5.30; N, 10.52. Found:
C, 72.13; H, 5.27; N, 10.57.
5-(4-Bromophenyl)2-phenyl-6H-1,3,4-oxadiazine (4d)
1H NMR (CDCl3): d ¼ 5.51 (s, 2H, OCH2), 7.47 (t, 2H, J ¼ 9.6 Hz, ArH),
7.58–7.65 (m, 3H, ArH), 7.81 (d, 2H, J ¼ 10.8 Hz, ArH), 8.11 (d, 2H,
J ¼ 10.4 Hz, ArH). IR (KBr, cmꢁ1): 3019, 2931, 1587, 1215, 1125, 799.
Anal. calcd. for C15H11BrN2O: C, 57.16; H, 3.52; N, 8.89. Found: C,
57.14; H, 3.51; N, 8.93.
5-(4-Chlorophenyl)2-phenyl-6H-1,3,4-oxadiazine (4e)
1H NMR (400 MHz, CDCl3): d ¼ 5.54 (s, 2H, OCH2), 7.46–7.54 (m, 4H,
ArH), 7.59–7.61 (m, 1H, J ¼ 12 Hz, ArH), 7.91–7.93 (m, 2H, ArH), 8.10–
8.15 (m, 2H, ArH). IR (KBr, cmꢁ1): 3019, 1593, 1559, 1423, 1215, 793.
Anal. calcd. for C15H11ClN2O: C, 66.55; H, 4.10; N, 10.35. Found: C,
66.52; H, 4.11; N, 10.33.
5-(4-Nitrophenyl)2-phenyl-6H-1,3,4-oxadiazine (4f)
1H NMR (CDCl3): d ¼ 5.58 (s, 2H, OCH2), 7.49 (t, 2H, J ¼ 7.6 Hz, ArH),
7.61 (t, 1H, J ¼ 7.4 Hz, ArH), 8.12–8.15 (m, 4H, ArH), 8.38 (d, 2H,
J ¼ 8.8 Hz, ArH). 13C NMR (CDCl3): d ¼ 66.56, 123.71, 127.74, 128.60,
129.04, 130.01, 133.69, 138.72, 150.74, 165.94, 191.12. IR (KBr, cmꢁ1):
3019, 1599, 1559, 1530, 1459, 1216, 793. Anal. calcd. for C15H11N3O3:
C, 64.05; H, 3.94; N, 14.94. Found: C, 64.08; H, 3.89; N, 14.91.

2,5-Disubstituted 1,3,4-Oxadiazine
2285
2,5-Bis(4-bromophenyl)-6H-1,3,4-oxadiazine (4g)
1H NMR (CDCl3): d ¼ 5.53 (s, 2H, OCH2), 7.98 (d, 2H, J ¼ 8.56 Hz,
ArH), 7.65 (d, 2H, J ¼ 8.08 Hz, ArH), 7.83 (d, 2H, J ¼ 8.92 Hz, ArH),
7.66 (d, 2H, J ¼ 9.24 Hz, ArH). 13C NMR (CDCl3): d ¼ 65.94, 127.59,
127.97, 128.59, 128.74, 130.83, 131.24, 131.67, 132.19, 164.57, 190.51.
IR (KBr, cmꢁ1): 3020, 2943, 1384, 1590, 1216, 796. Anal. calcd. for
C15H10Br2N2O: C, 45.72; H, 2.56; N, 7.11. Found: C, 45.71; H, 2.59;
N, 7.09.
5-Phenyl-6H-1,3,4-thiadiazin-2-amine (4h)
1H NMR (CDCl3): d ¼ 1.61 (br. s, 2H, NH2), 2.30 (s, 2H, SCH2), 7.29
(m, 2H, ArH), 7.42 (m, 2H, ArH), 7.78 (m, 1H, ArH). IR (KBr, cmꢁ1):
3422, 3241, 3149, 2957, 2925, 1585, 1506, 1280, 1095, 840, 762.
5-p-Tolyl-6H-1,3,4-thiadiazin-2-amine (4i)
1H NMR (CDCl3): d ¼ 1.59 (br. s, 2H, NH2), 2.32 (s, 2H, SCH2), 2.41
(s, 3H, ArCH3), 7.29 (d, 2H, J ¼ 8.16Hz, ArH), 7.57 (d, 2H, J ¼ 8.14 Hz,
ArH).
5-(4-Chlorophenyl-6H-1,3,4-thiadiazin-2-amine (4j)
1H NMR (CDCl3): d ¼ 1.57 (br. s, 2H, NH2), 2.31 (s, 2H, SCH2), 7.29
(d, 2H, J ¼ 8.52 Hz, ArH), 7.63 (d, 2H, J ¼ 8.61 Hz, ArH).
5-(4-Bromophenyl-6H-1,3,4-thiadiazin-2-amine (4k)
1H NMR (CDCl3): d ¼ 1.69 (br. s, 2H, NH2), 2.34 (s, 2H, SCH2), 7.33
(d, 2H, J ¼ 9.02 Hz, ArH), 7.59 (d, 2H, J ¼ 9.02 Hz, ArH). IR (KBr,
cmꢁ1): 3419, 2956, 2925, 1590, 1480, 1403, 1095, 825, 757.
ACKNOWLEDGMENTS
The authors are thankful to the Department of Science and Technology
(No. SR=FTP=CS-77=2005) and the University Grants Commission,
New Delhi, India (No. MRP 32-245=2006 SR) for the financial support.

2286
N. N. Karade et al.
REFERENCES
1. (a) Mikhailov, I.; Gagov, I.; Toshkov, A. Antiviral effect of 1,3,4-oxadiazine
compounds on the reproduction of influenza virus type A in vitro. Acta
Microbiol. Bulg. 1984, 14, 120; (b) Mikhailov, I.; Gagov, I.; Toshkov, A.
Antiviral effect of the compounds of 1,3,4-oxadiazine on the reproduction
of influenza viruses type A in vivo on white mice. Acta Microbiol. Bulg.
1984, 14, 124; (c) Miteui Toateu Chemicals, Inc., Jpn. Kokai Tokk Koho
JP Patent 5,962,578 8462, 5781 (C1. C07D273=04), 1984.
2. (a) Lang, G.; Forestier, S.; Oreal, S. A. UK Pat. Appl. 6B 2,077,589 (Cl.
C07C127=15); (b) Fr. Demande FR Patent 2,483,777 (Cl. A61K7=00),
1980; (c) Allen, R.; Avakian R. W. (General Electric Co.) US Patent
4,544,677 (521–91COSJ9=10), 1985.
3. Barba, F.; Batanero, B. A novel and convenient electrochemical synthesis of
3,7-diaryl-2H-imidazo[2,1-b][1,3,4]oxadiazines. J. Org. Chem. 1993, 58, 6889.
4. Kamitori, Y.; Hojo, M.; Masuda, R.; Kawamura, Y.; Kawasaki, K.; Ida, J.
A
new facile synthesis of 5-aryl-4-trifluoroacetyl-6-trifluoromethyl-3,4-
dihydro-2H-1,3,4-oxadia zines from arylaldehydes. Tetrahedron Lett. 1990,
31, 1183.
5. Mazouz, F.; Lebreton, L.; Milcent, R.; Burstein, C. Inhibition of monoamine
oxidase types A and B by 2-aryl-4H-1,3,4-oxadiazin-5(6H)-one derivatives.
Eur. J. Med. Chem. 1988, 23, 441.
6. Kuz’mich, N. N.; Lalaev, B. Y.; Yakovlev, I. P.; Petina, O. A.; Strelkova, L.
F.; Zakhs, V. E. Synthesis of 2-aryl(hetaryl)-4H-1,3,4-oxadiazine-5,6-diones.
Russ. J. Gen. Chem. 2007, 77, 1100.
7. Mohareba, R. M.; Ibrahima, R. A.; Hob, J. Z. The reaction of cyanoacetyl-
hydrazine with a-bromoacetophenone: Novel synthesis of 1,3,4-oxadiazine,
pyridazine, and coumarin derivatives. J. Chil. Chem. Soc. 2007, 52, 1073.
8. Koser, G. F.; Relenyi, A. G.; Kalos, A. N.; Rebrovic, L.; Wettach, R. H.
One-step a-tosyloxylation of ketones with [hydroxy(tosyloxy)iodo]benzene.
J. Org. Chem. 1982, 47, 2487.
9. (a) Moriarty, R. M.; Vaid, R. K.; Hopkins, T. E.; Vaid, B. K.; Prakash, O.
Hypervalent iodine oxidation of 5-keto acids and 4,6-diketo acids with
[hydroxy(tosyloxy)iodo]benzene: Synthesis of keto-c-lactones and diketo-d-
lactones. Tetrahedron Lett. 1990, 31, 201; (b) Prakash, O.; Goyal, S. A new
synthesis of 2-aroylcoumaran-3-ones by hypervalent iodine oxidation of 2-
acetyl-phenyl benzoates using [hydroxy(tosyloxy)iodo]benzene. Synthesis
1992, 629; (c) Prakash, O.; Rani, N.; Goyal, S. Hypervalent iodine in the
synthesis of bridgehead heterocycles: Novel and facile syntheses of 3-substi-
tuted-5,6-dihydroimidazo[2,1-b]thiazoles and 3-phenylthiazolo[3,2-a]benzimi-
dazole from acetophenones using [hydroxy(tosyloxy)iodo]benzene. J. Chem.
Soc., Perkin Trans. 1 1992, 707; (d) Prakash, O.; Saini, N.; Sharma, P. K.
[Hydroxy(tosyloxy)iodo]benzene: A useful hypervalent iodine reagent for
the synthesis of heterocyclic compounds. Heterocycles 1994, 38, 409; (e)
Uneno, M.; Togo, H. Environmentally benign preparation of heteroaro-
matics from ketones or alcohols, with macroporous polystyrenesulfonic

2,5-Disubstituted 1,3,4-Oxadiazine
2287
acid and (diacetoxyiodo)benzene, followed by thioamide, amidine, and
2-aminopyridine. Synthesis 2004, 16, 2673.
10. Karade, N. N.; Gampawar, S. V.; Kondre, J. M.; Shinde, S. V. A novel
one-pot synthesis of 3-carbomethoxy-4-arylfuran-2-(5H)-ones from ketones
using [hydroxy(tosyloxy)iodo]benzene. Tetrahedron Lett. 2008, 49, 4402; (b)
Karade, N. N.; Tiwari, G. B.; Huple, D. B. Molecular iodine as efficient coca-
talyst for facile oxidation of alcohols with hypervalent(III) iodine. Synlett
2005, 2039; (c) Karade, N. N.; Gampawar, S. V.; Kondre, J. M.; Shinde
S. V. An efficient combination of Dess–Martin periodinane with molecular
iodine or KBr for the facile oxidative aromatization of Hantzsch 1,4-
dihydropyridines. Arkivoc 2008, 1, 9.
11. Tomita, Y.; Kabashima, S.; Okawara, T.; Yamasaki, T.; Furakawa, M.
Heterocyclization of 2,4-disubstituted thiosemicarbazides with a-haloketones.
J. Heterocyclic Chem. 1990, 27, 707.
12. Wirth, T.; Yusubov, M. Solvent-free reactions with hypervalent iodine
reagents. Org. Lett. 2005, 3, 519.