Use of [hydroxy(tosyloxy)iodo]benzene in a novel and facile synthesis of 1,4-diaryl-2-(arylamino)but-2-ene-1,4-diones

Article abstract of DOI:10.1016/j.tetlet.2005.02.129

The reaction of acetophenones 1 with [hydroxy(tosyloxy)iodo]benzene followed by treatment of the resulting α-tosyloxyacetophenones 2 thus formed with anilines 3 in the presence of sodium carbonate in ethanol provides a novel one-pot synthesis of 1,4-diary

Full text of DOI:10.1016/j.tetlet.2005.02.129

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Tetrahedron
Letters
Tetrahedron Letters 46 (2005) 2877–2878
Use of [hydroxy(tosyloxy)iodo]benzene in a novel and facile
synthesis of 1,4-diaryl-2-(arylamino)but-2-ene-1,4-diones
Om Prakash,* Anita Batra, Vishwas Chaudhri and Richa Prakash
Department of Chemistry, Kurukshetra University, Kurukshetra, India
Received 18 August 2004; revised 14 February 2005; accepted 21 February 2005
Abstract—The reaction of acetophenones 1 with [hydroxy(tosyloxy)iodo]benzene followed by treatment of the resulting a-tosyloxy-
acetophenones 2 thus formed with anilines 3 in the presence of sodium carbonate in ethanol provides a novel one-pot synthesis of
1,4-diaryl-2-(arylamino)but-2-ene-1,4-diones 4.
Ó 2005 Elsevier Ltd. All rights reserved.
1,4-Diaryl-2-(arylamino)but-2-ene-1,4-diones 4 are im-
portant precursors for the synthesis of heterocyclic com-
pounds.1,2 There are three methods reported in the
literature for their synthesis as outlined in Eqs. 1–3.2–5
The yields in the first two methods (Eqs. 1 and 2) are
not good, whereas the third method (Eq. 3) involves aryl
azides, which are highly toxic and explosive in nature.
products 4 and expected a-anilinoacetophenones pro-
ducts. This observation encouraged us to seek optimum
conditions for the synthesis of 1,4-diaryl-2-(aryla-
mino)but-2-ene-1,4-diones 4 and we report here a novel
and convenient synthesis of 4. In addition, a one-pot
procedure for the synthesis of 4 starting from acetophe-
nones 1 has been developed and is reported herein.
First, we carried out the reaction between a-tosyloxy-
acetophenone 2a and aniline 3a. We found that an equi-
molar mixture of 2a and aniline 3a in the presence of
sodium carbonate in ethanol under reflux for 12 h afford-
ed 4aa in 70% yield. The generality of this approach was
illustrated by reacting different a-tosyloxyacetophenones
(2a–e) and anilines (3a–e) under similar conditions. The
reactions afforded the desired products 4ac–ec in yields
ranging from 65% to 77% (Table 1, Scheme 1, Method
A).
i-PrOH or
i-PrOK/
+
Eq 1
Eq 2
Ar'NO2
ArCOCH3
DMSO / KOH
NHAr'
COAr
ArCO
H
˚
THF , 30 C
ArCOC CCOAr
+ Ar'NH2
C
C
-
4
Me2S
2 Me2S=CHCOAr + Ar'N3
Eq 3
-
N2
As part of our project6 directed towards the use of org-
ano-hypervalent iodine reagents7 such as iodobenzene
diacetate (IBD)8,9 and [hydroxy(tosyloxy)iodo]benzene
(HTIB, KoserÕs reagent)10,11 in organic synthesis, we
earlier reported a convenient synthesis of a-anilino-
acetophenones (ArCOCH2NHAr0).12 In an attempt to
synthesize a-anilinoacetophenones from a-tosyloxyaceto-
phenones 2 and anilines 3 in the presence of sodium
carbonate in ethanol, we found that instead the reaction
resulted in the formation of a mixture containing new
Based on our earlier success in the development of a one-
pot synthesis of a-anilinoacetophenones from acetophen-
ones,12 we attempted the synthesis of 4 by oxidation of
ArCOCH2OTs
2
Method A
(ii)
(i)
NHAr'
COAr
ArCO
H
Method B
Keywords: a-Tosyloxyacetophenones; Anilines; a-Anilinoacetophen-
ones; 1,4-Diaryl-2-(arylamino)but-2-ene-1,4-diones.
ArCOCH3
C C
(i), (ii)
*
Corresponding author. Tel.: +91 1744 234366; fax: +91 1744 238277;
e-mail addresses: oprakash11@yahoo.co.in; chem@granth.kuk.
ernet.in
1
4
(i)
,
, reflux (ii)
CH3CN
HTIB
Ar'NH2 3, Na2CO3, C2H5OH, reflux
0040-4039/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2005.02.129

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2878
O.Prakash et al./ Tetrahedron Letters 46 (2005) 2877–2878
prepared selectively by omitting the use of base such
as Na2CO3/K2CO3.12
Ar'
Ar'
3
a
b
c
Ar
4
aa
ac
Ar
1
a
C6H5
C6H5
C6H5
C6H5
p
p
-FC6H4
b
c
-
FC6H4
p
C6H5
C6H5
p
-MeC6H4
p
-MeOC6H4
p
-
-
p
MeC6H4
-
ad
ba
ca
MeC6H4
Acknowledgements
p
d
e
MeOC6H4
-O2NC6H4
C6H5
C6H5
C6H5
C6H5
d
e
p
-FC6H4
- MeOC6H4
p
p-
p
-
MeC6H4
BrC6H4
We wish to thank to DRDO (ERIP/ER/0103294/M/01)
(India) for financial assistance.
p
-MeOC6H4
da
ea
p-
BrC6H4
MeC6H4
BrC6H4
p
-O2NC6H4
p-
ce
ec
References and notes
p
p
-
- MeC6H4
1. Palmer, M. H. The Structure and Reactions of Heterocyclic
Compounds; Edward Arnold: London, 1967.
Scheme 1.
2. Cristina, P.; Maurizio, P.; Ugo, Q.; Gianfranco, S. J.Org.
Chem. 1981, 46, 5156–5159.
Table 1. Physical data of 1,4-diaryl-2-(arylamino)but-2-ene-1,4-diones
4 prepared according to Scheme 1
3. (a) Lutz, R. E.; Smithey, W. R. J.Org.Chem. 1951, 16,
51–56; (b) Barraclough, P.; Edwards, M.; Gilchrist, T. L.;
Harris, C. J. J.Chem.Soc., Perkin Trans.1 1976, 716–719;
(c) Lahiri, S.; Mahajan, P.; Prasad, R.; George, M. V.
Tetrahedron 1977, 33, 3159–3170.
Compound
Mp (°C)
Lit. mp (°C)
Yieldb,c (%)
4aa
4ac
4ad
4ba
4ca
4da
4ea
4ce
4ec
126–127
144–145
122–123
168–169
141–142
136–137
160–161
202–203
223–224
1282
70 (65)
71 (67)
70 (63)
76 (68)
65 (61)
67 (61)
72 (67)
65 (60)
77 (72)
1534
4. Hayashu, Y.; Watanabe, T.; Oda, R. Tetrahedron Lett.
1970, 11, 605–608.
121–12215
a
5. Moskalev, N. V.; Tartynova, M. I.; Ogorodnikov, V. D.;
Kadychagov, P. B. Zh.Org.Khim. 1994, 30, 740–743.
6. (a) Prakash, O.; Rani, N.; Sharma, P. K. Synlett 1994,
221–227; (b) Prakash, O. Aldrichim.Acta 1995, 28, 63–71;
(c) Prakash, O.; Kaur, H.; Batra, H.; Rani, N.; Singh, S. P.
1434
135–1362
169–1704
2044
a
J.Org.Chem.
2001, 66, 2019–2023; (d) Prakash, O.;
a New products and their structures were confirmed by their spectral
Pundeer, R.; Kaur, H. Synthesis 2003, 2768–2770.
7. (a) Varvoglis, A. Hypervalent Iodine in Organic Synthesis;
Academic: New York, 1996; (b) Ochiai, M. In Chemistry
of Hypervalent Compounds; Akiba, K., Ed.; VCH: Wein-
heim, 1999, Chapter 13, p 359; (c) Zhdankin, V. V.; Stang,
P. J. Chem.Rev. 2002, 102, 2523–2584.
8. (a) Varvoglis, A. Chem.Soc.Rev. 1981, 10, 377–407; (b)
Prakash, O.; Singh, S. P. Aldrichim.Acta 1994, 27, 15–
23.
1
(IR, H NMR, mass) and satisfactory elemental analyses (C, H, N).
b Yields of isolated compounds after recrystallization from ethanol
with respect to the quantity of pure a-tosyloxyacetophenone 2
starting material (Method A). Compound 2 used in this method were
prepared according to the literature procedure and were purified by
recrystallization from ethanol.10a
c Yields in parentheses are of pure products with respect to the
quantity of acetophenone starting material (by Method B) presuming
that 2 equiv of acetophenone produce 1 equiv of 4.
9. Varma, R. S.; Dahiya, R.; Saini, R. K. Tetrahedron Lett.
1997, 38, 7029–7032.
10. (a) Koser, G. F.; Relenyi, A. G.; Kalos, A. N.; Rebrovic,
L.; Wettach, R. H. J.Org.Chem. 1982, 47, 2487–2489; (b)
Moriarty, R. M.; Vaid, R. K.; Koser, G. F. Synlett 1990,
365–373; (c) Koser, G. F. Aldrichim.Acta 2001, 34, 89–
102.
acetophenones (1a–e) with HTIB (2a–e are generated in
situ) followed by reaction with anilines (3a–e) (Method
B).13 This method worked well for the synthesis of
4aa–ec and the physical data are given in Table 1.
11. Prakash, O.; Saini, N.; Sharma, P. K. Heterocycles 1994,
38, 409–430.
Although the mechanism for the reaction is not certain,
preliminary observations from the present study indicate
that the conversion 2!4 proceeds through the inter-
mediate a-anilinoacetophenones (ArCOCH2NHAr0),14
which probably undergoes oxidative dimerization in
aerobic conditions. Further studies concerning the full
scope of the reaction and its mechanism are in progress,
and will be published in the future. Finally, the present
study provides a novel application of KoserÕs reagent
for a direct one-pot synthesis of 1,4-diaryl-2-(arylamino)-
but-2-ene-1,4-diones 4 from acetophenones. The present
synthesis is superior to existing methods because of its
good yields and the simple experimental procedure
involved. The reaction conditions exclusively gave 4
and the intermediate a-anilinoacetophenone can be
12. Prakash, O.; Rani, N.; Goyal, S. Indian J.Chem. 1992,
31B, 349–350.
13. [Hydroxy(tosyloxy)iodo]benzene (10 mmol) was added to
a solution of an acetophenone (1, 10 mmol) in acetonitrile
(25 mL) and the mixture was refluxed for 1–2 h. The
solvent was evaporated in vacuo. Aniline/p-substituted
aniline (3, 10 mmol), sodium carbonate (10 mmol) and
ethanol (20 mL) were added and the mixture refluxed for a
further 6–12 h, then kept overnight. The solid, thus
separated, was filtered, washed with water, dried and
recrystallized from ethanol.
14. We were able to isolate the intermediate PhCOCH2NHPh
5aa under controlled conditions. In a separate experiment,
the intermediate 5aa was successfully converted into 4aa.
15. Van Loock, E.; Labbe, G.; Smets, G. Tetrahedron Lett.
1970, 11, 1693–1696.