Organic reactions in water: An efficient one-pot synthesis of acyloxiranes from Baylis-Hillman adducts using hypervalent iodine

Article abstract of DOI:10.1016/j.tetlet.2005.10.078

Treatment of Baylis-Hillman adducts with iodosobenzene (PhIO) in the presence of a catalytic amount of KBr in water at room temperature afforded the corresponding acyloxiranes in good yields.

Full text of DOI:10.1016/j.tetlet.2005.10.078

Tetrahedron
Letters
Tetrahedron Letters 46 (2005) 8895–8897
Organic reactions in water: an efficient one-pot synthesis
of acyloxiranes from Baylis–Hillman adducts
using hypervalent iodine
q
*
Biswanath Das, Harish Holla, Katta Venkateswarlu and Anjoy Majhi
Organic Chemistry Division-I, Indian Institute of Chemical Technology, Hyderabad 500 007, India
Received 28 June 2005; revised 5 October 2005; accepted 18 October 2005
Abstract—Treatment of Baylis–Hillman adducts with iodosobenzene (PhI@O) in the presence of a catalytic amount of KBr in water
at room temperature afforded the corresponding acyloxiranes in good yields.
ꢀ
2005 Elsevier Ltd. All rights reserved.
Hypervalent iodine reagents have attracted considerable
attention in organic synthesis due to their interesting
activity, ready availability and easy handling whilst
the reactions of these adducts we have observed that
treatment of these compounds 1 with iodosobenzene in
the presence of a catalytic amount of KBr in water at
room temperature produced the corresponding acyloxir-
anes 2 (Scheme 1).
1
organoiodine(III) reagents have been employed to carry
out useful transformations. We have recently applied
diacetoxyiodobenzene (DIB) to the preparation of isoxa-
zolines from activated alkenes by treatment with aldox-
It is known that, (i) iodosobenzene can oxidize second-
ary alcohols including allylic alcohols to the correspond-
2
imes. In continuation of our work on the application of
5
hypervalent iodine reagents to organic synthesis, we now
report the use of iodosobenzene (PhI@O) for the prepara-
tion of acyloxiranes from the Baylis–Hillman adducts 1.
ing keto compounds and, (ii) electron deficient enones
6
can undergo epoxidation with this reagent. Thus,
Baylis–Hillman adducts containing the necessary struc-
tural requirements, that is, an allylic hydroxyl group
and an electron-withdrawing group at the requisite posi-
tions were considered for single-step conversion into
their corresponding acyloxiranes.
Baylis–Hillman adducts, 3-hydroxy-2-methylene alkano-
ates and 3-hydroxy-2-methylene-alkanenitriles are use-
3
2a,4
ful precursors in synthesis. During our work
on
O
OH
PhI=O, cat.KBr
EWG
O
EWG
water
X
X
r.t., 5-8 h
1
2
EWG= -COOCH
3
, -CN
56–85%
X = -NO , -CF , -Cl, -OCH
2
3
3
Scheme 1.
Keywords: Baylis–Hillman adducts; Hypervalent iodine; PhI@O; Acyloxiranes; Aqueous medium.
q
Part 66 in the series, ÔStudies on Novel Synthetic MethodologiesÕ. IICT Communication No. 051003.
Corresponding author. Tel.: +91 4027173874; fax: +91 402716 05 12; e-mail: biswanathdas@yahoo.com
*
0040-4039/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2005.10.078

8896
B. Das et al. / Tetrahedron Letters 46 (2005) 8895–8897
a
Table 1. Preparation of acyloxiranes from Baylis–Hillman adducts using PhI@O activated by KBr
b
Entry
Reactant 1
Product 2
Time (h)
6
Isolated yield (%)
OH
O
O
COOCH3
COOCH3
a
81
O
Cl
Cl
Cl
OH
CN
CN
b
c
5
6
80
70
O
Cl
OH
O
O N
COOCH3
O
2
N
COOCH
3
2
O
OH
Cl
O
COOCH3
COOCH3
d
e
6
5
85
64
O
OH
Cl
O
COOCH3
COOCH3
O
Cl
Cl
Cl
Cl
OH
Cl
O
CN
CN
f
5
8
56
78
O
Cl
OH
O
COOCH3
COOCH3
g
O
O N
O N
2
2
OH
OH
O
O
CN
CN
h
i
6
65
72
O
MeO
MeO
F3C
COOCH3
F3C
COOCH
3
1.6
O
a
1
The structures of the products were established from their spectral ( H NMR and MS) data.
b
A minor amount (ꢁ5%) of the parent aldehydes from which the Baylis–Hillman adducts were prepared was also obtained.
7
A series of acyloxiranes was prepared from Baylis–
reagent in water its activity increased significantly and
Hillman adducts 1 with an ester or a nitrile substituent
the corresponding acyloxiranes 2 were formed.
(
Table 1). These adducts containing an electron-donat-
5
ing or electron-withdrawing group on the aromatic
ring underwent the conversion smoothly. The struc-
tures of the products were established from their spec-
tral ( H NMR and MS) data. Previously this
conversion has been carried out using NaOCl but this
method involves the possibilities of further oxidation of
the acyloxiranes to acids. In the present case, minor
amounts of the parent aldehyde (ꢀ5%) from which
the Baylis–Hillman adducts were prepared were also
obtained.
The mechanism of the reaction may involve depoly-
merization of iodosobenzene by the additon of KBr
to form the highly reactive intermediate A. This inter-
mediate reacts with the hydroxyl group of Baylis–
Hillman adduct 1 to form the enone B. Iodosobenzene
1
7
8
6
then attacks the enone B to produce the acyloxirane 2
(Scheme 2).
In conclusion, we have developed an efficient process for
the synthesis of acyloxiranes from Baylis–Hillman
adducts using iodosobenzene activated by a catalytic
amount of KBr in water at room temperature. Iodoso-
benzene has been utilized here for twofold oxidation
of a secondary alcohol of a Baylis–Hillman adduct
Initially, we used iodosobenzene by itself for oxidation
of the Baylis–Hillman adducts 1 but no products were
formed. However, when KBr or LiBr was added to this
5

B. Das et al. / Tetrahedron Letters 46 (2005) 8895–8897
8897
O
+
OK
KBr
[
I
O ] n
Ph
I
Br
A
Ph
OH
EWG
X
1
HBr
_
O O+
O
OK
Ph
I
KOH
PhI
EWG
O
H
EWG
X
B
.
X
PhI=O.
_
O
O
O
EWG
EWG
O
PhI
O
I
X
X
2
Ph
O+
Scheme 2.
followed by subsequent epoxidation of the generated
enone in the one-pot synthesis of an acyloxirane.
7. General procedure for the preparation of acyloxiranes: To a
stirred mixture of the Baylis–Hillman adduct (1 mmol) and
KBr (0.2 mmol) in water (2 ml), PhI@O (2.2 mmol) was
added at room temperature. Stirring was continued and the
reaction was monitored by TLC. After completion, the
reaction mixture was extracted with ethyl acetate (3 · 5 ml),
the combined organics washed with brine (3 · 5 ml) and then
Acknowledgements
The authors thank UGC and CSIR, New Delhi, for
financial assistance.
2 4
dried over anhydrous Na SO . The extract was filtered and
the filtrate was concentrated under vacuum. The residue was
purified by column chromatography over silica gel (EtOAc/
1
n-hexane) to afford the pure acyloxirane. The spectral ( H
References and notes
NMR and MS) and analytical data of new acyloxiranes are
8
given below. The remaining products are known.
1
1
. (a) Varvoglis, A. Hypervalent Iodine in Organic Synthesis;
Academic Press: New York, 1997; (b) Zhdankin, V. V.;
Stang, P. J. Chem. Res. 2002, 102, 2523–2584; (c) Wirth, T.
Hypervalent Iodine Chemistry: Modern Developments in
Organic Synthesis. In Topics in Current Chemistry;
Springer: Berlin, 2003; p 224.
. (a) Das, B.; Holla, H.; Mahender, G.; Banerjee, J.; Reddy,
M. Tetrahedron Lett. 2004, 45, 7347–7350; (b) Das, B.;
Holla, H.; Mahender, G.; Katta, V.; Bandgar, B. Synthesis
Compound 2c: H NMR (CDCl
, 200 MHz): d 8.82 (1H, d,
3
J = 2.0Hz), 8.46 (1H, dd, J = 8.0, 2.0 Hz), 8.31 (1H, dd,
J = 8.0, 2.0 Hz), 7.71 (1H, t, J = 8.0Hz), 3.83 (3H, s), 3.47
(1H, d, J = 6.0Hz), 3.22 (1H, d, J = 6.0Hz); EIMS: m/z 251
+
Å
(M ); Anal. Calcd for C11
H
NO
9
: C, 52.59; H, 3.59; N, 5.58.
6
Found: C, 52.74; H, 3.62; N, 5.53.
1
2
3
4
Compound 2e: H NMR (CDCl
3
, 200 MHz): d 7.73 (1H, d,
J = 8.0Hz), 7.48 (1H, d, J = 2.0Hz), 7.36 (1H, dd, J = 8.0,
2.0Hz), 3.82 (3H, s), 3.43 (1H, d, J = 6.0Hz), 3.12 (1H, d,
+
Å
2
005, 10, 1572–1574.
J = 6.0Hz); EIMS: m/z 278, 276, 274 (M ); Anal. Calcd for
Cl : C 48.00; H, 2.91. Found: C, 48.31; H, 2.84.
Compound 2f: H NMR (CDCl
7.33 (3H, m), 3.55 (1H, d, J = 6.0Hz), 3.21 (1H, d, J =
. (a) Hoffman, H. M. R.; Rabe, J. Angew. Chem., Int. Ed.
Engl. 1985, 24, 94–110; (b) Basavaiah, D.; Bakthadoss, M.;
Pandiaraju, S. J. Chem. Soc., Chem. Commun. 1998, 1639–
C
11
H
8
2 4
O
1
, 200 MHz): d 7.56–
3
+
Å
1
640.
6.0Hz): EIMS: m/z 245, 243, 241 (M ); Anal. Calcd for
Cl NO : C, 49.59; H, 2.07; N, 5.79. Found: C, 49.82;
. (a) Das, B.; Banerjee, J.; Ravindranath, N.; Venkataiah, B.
Tetrahedron Lett. 2004, 45, 6709–6710; (b) Das, B.; Banerjee,
J.; Ravindranath, N. Tetrahedron 2004, 60, 8357–8361; (c)
Das, B.; Banerjee, J.; Mahender, G.; Majhi, A. Org. Lett.
C
10
H
5
2
2
H, 2.11; N, 5.63.
1
Compound 2i: H NMR (CDCl
3
, 200 MHz): d 8.28 (1H, d,
J = 2.0Hz), 8.19 (1H, dd, J = 8.0, 2.0 Hz), 7.90 (1H, dd,
J = 8.0, 2.0 Hz), 7.64 (1H, t, J = 8.0Hz), 3.79 (3H, s), 3.40
(1H, d, J = 6.0Hz), 3.21 (1H, d, J = 6.0Hz); EIMS: m/z 274
2
004, 6, 3349–3352; (d) Das, B.; Banerjee, J.; Majhi, A.;
Mahender, G. Tetrahedron Lett. 2004, 45, 9225–9227.
. Hohma, H.; Takizawa, S.; Maegawa, T.; Kita, Y. Angew.
Chem., Int. Ed. 2000, 39, 1306–1308.
+
Å
5
6
(M ); Anal. Calcd for C12
Found: C, 52.76; H, 3.20.
9 3 4
H F O : C, 52.56; H, 3.29.
. McQuaid, K. M.; Pettus, T. R. R. Synlett 2004, 2403–2405.
8. Foucaud, A.; le Rouille, E. Synthesis 1990, 787–789.