Microwave-enhanced Ferrier reaction: A facile synthesis of 2,3-unsaturated-O-glycosides under solvent-free conditions

Article abstract of DOI:10.1080/00397910600634415

A variety of 2,3-unsaturated- O -glycosides have been prepared by the Ferrier rearrangement of acetyl protected glycals under microwave irradiation using silica gel as an acid catalyst. Environmental friendliness, high yields, and short reaction times are the key features of this method. Furthermore, the method was applicable not only to the Ferrier reaction of 3,4,6-tri- O -acetyl glucal and 3,4,6-tri- O -acetyl galactal but also to the Ferrier reaction of 3,4-di- O -acetyl arabinal. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910600634415

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Microwave‐Enhanced Ferrier
Reaction: A Facile Synthesis of
2,3‐Unsaturated‐O‐Glycosides Under
Solvent‐Free Conditions
a
a
Wenting Du & Yongzhou Hu
a
Zhejiang University‐Ecole Normale Supérieure Joint Laboratory of
Medicinal Chemistry , School of Pharmaceutical Sciences, Zhejiang
University , Hangzhou, China
Published online: 20 Aug 2006.
To cite this article: Wenting Du & Yongzhou Hu (2006) Microwave‐Enhanced Ferrier Reaction: A Facile
Synthesis of 2,3‐Unsaturated‐O‐Glycosides Under Solvent‐Free Conditions, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 36:14, 2035-2046, DOI:
10.1080/00397910600634415
To link to this article: http://dx.doi.org/10.1080/00397910600634415
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Synthetic Communications , 36: 2035–2046, 2006
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910600634415
Microwave-Enhanced Ferrier Reaction: A
Facile Synthesis of 2,3-Unsaturated-O-
Glycosides Under Solvent-Free Conditions
Wenting Du and Yongzhou Hu
Zhejiang University-Ecole Normale Sup e´ rieure Joint Laboratory of
Medicinal Chemistry, School of Pharmaceutical Sciences,
Zhejiang University, Hangzhou, China
Abstract: A variety of 2,3-unsaturated-O-glycosides have been prepared by the Ferrier
rearrangement of acetyl protected glycals under microwave irradiation using silica gel
as an acid catalyst. Environmental friendliness, high yields, and short reaction times are
the key features of this method. Furthermore, the method was applicable not only to the
Ferrier reaction of 3,4,6-tri-O-acetyl glucal and 3,4,6-tri-O-acetyl galactal but also to
the Ferrier reaction of 3,4-di-O-acetyl arabinal.
Keywords: Ferrier rearrangement, glycosylation, microwave, 2,3-unsaturated-O-
glycosides
2
,3-Unsaturated-O-glycosides or pseudoglycals obtained by Ferrier rearrange-
ment represent versatile chiral intermediates toward the synthesis of bio-
logically active compounds such as glycopeptide building blocks,
oligosaccharides, and modified carbohydrates. They have also been
employed in the synthesis of some important antibiotics and nucleosides.
Since Ferrier discovered that 2,3-unsaturated-O-glycosides 3 could be
obtained from the reaction of corresponding glycal derivatives 1 with
.
various alcohols 2 in the presence of BF Et O in 1969, a number of Lewis
3
2
[
acids such as BF3 Et O, ZnEt2, FeCl3, Sc(OTf)3, LiBF4, InCl3,
1]
[2]
[3]
[4]
[5]
[6]
.
2
Received in Japan October 23, 2005
Address correspondence to Yongzhou Hu, ZJU-ENS Joint Laboratory of Medicinal
Chemistry, School of Pharmaceutical Sciences, Zhejiang University, Hubin Campus,
Hangzhou 310031, P. R. China. E-mail: huyz@zjuem.zju.edu.cn
2
035

2
036
W. Du and Y. Hu
[
7]
[8]
[9]
[10]
[11]
Yb(OTf)3,
.
montmorillonite K10,
12]
BiCl3,
InBr3,
Dy(OTf)3,
[
[13]
[14]
CeCl3 7H O,
ZnCl2,
Other catalysts used for this include iodonium dicollidinium perchlorate,
and ZrCl4
were employed in this reaction.
[15]
2
[
16]
[17]
[18]
.
Bi(NO3)3 5H O, and Ce(NH ) (NO ) .
2 4 2 3 6
DDQ,
Very recently, HClO SiO2 was found to be effective for the Ferrier
Ce(NH ) (NO ) ,
.
4
2
3 6
4
[
19]
rearrangement.
Despite their usefulness, many of these methods require
harsh reaction conditions, such as strong acidity, longer reaction times,
higher temperature, unsatisfactory yields, and low stereoselectivity.
Another common method for the Ferrier reaction is microwave irradiation
[8]
using montmorillonite K10 as a catalyst, but a great quantity of the catalyst
and chlorobenzene as a solvent are required in the procedure, both of which
are dangerous and pollute the environment. Hotha also reported the Ferrier
reaction under microwave irradiation, but still a metal catalyst NbCl was
5
[
20]
necessary.
and green method to yield 2,3-unsaturated-O-glycosides.
In the view of this, there is a need to develop an economical
Herein we report a method for the synthesis of 2,3-unsaturated-O-glyco-
sides under solvent-free and microwave irradiation conditions using silica gel
as a catalyst which is environment-friendly than any of the previous catalysts
used for Ferrier rearrangement.
RESULTS AND DISCUSSION
The method reported in this article allows the reaction of several alcohols,
including primary, secondary, allylic, benzylic, and monosaccharide alcohols,
with three kinds of glycals to yield the corresponding 2,3-unsaturated-O-glyco-
sides in high yields with good to high a-selectivity. Thiol was successfully
used instead of alcohols to give 2,3-unsaturated thioglycosides (Scheme 1).
Scheme 1.

Microwave-Enhanced Ferrier Reaction
2037
The application of microwave irradiation and silica gel as a catalyst
improved the safety aspects, avoided poisonous solvents, and made the
reaction times much shorter. Also it was more environmentally friendly
than previous methods. The silica gel catalyst could be removed from the
reaction mixture by simple filtration and recycled. The drawback of our
method was that a large excess of alcohols 2 was needed to dissolve
glycals, but they could be reclaimed according to the procedure.
In the first set of experiments, 3,4,6-tri-O-acetyl glucal was treated with a
batch of alcohols in the presence of silica gel under microwave irradiation to
afford the corresponding 2,3-unsaturated-O-glycosides in high yields. All the
reactions were complete in less than 10min. In addition, in the case of 3,4,6-
tri-O-acetyl galactal and 3,4-di-O-acetyl arabinal, the reactions went smoothly
under these conditions. Though the yields were a bit inferior to its glucal counter-
part, the a-selectivity increased remarkably (entries m–s, Table 1). A limitation
of the procedure was that a-selectivity of some 2,3-unsaturated-O-glycosides
[8]
was not higher than that in the previous study. We are unable to explain this
lack of stereoselectivity at present; such results may have arisen from the
different reaction conditions such as catalyst, microwave power, and solvent.
We also investigated the influence of microwave power on these reactions
and found that a power of 650 W was most appropriate. When the microwave
power was dropped, the reaction times were prolonged and the yields were
decreased. But interestingly, the a-selectivity increased moderately (entries
t–v, Table 1). Reactions were not processed if the microwave power was
less than 260 W.
Untill now, not many methods are available for the Ferrier reaction of
,4,6-tri-O-acetyl galactal and as far as we know, nobody has reported the
3
Ferrier reaction of 3,4-di-O-acetyl arabinal. To extend the type of reaction,
we developed our approach for the glycosidation of 3,4,6-tri-O-acetyl
galactal and 3,4-di-O-acetyl arabinal. The result revealed that the method was
applicable not only to hexose but also to pentaose.
A mixture of two anomers of 2,3-unsaturated-O-glycosides (a and b)
were obtained, the ratio of which was determined by comparing the inte-
1
gration values of the peaks in H NMR analysis (Table 1). The a-configuration
of the major product was confirmed from the positions of the anomeric protons
[19,21]
For further con-
1
in the H NMR data, compared with the literature data.
firmation of a-configuration, NOE analysis was carried out for the major
products, in which NOE was observed between H-1 and H-4 in all 2,3-unsa-
turated-O-glucosides and no nuclear overhauser effect (NOE) was observed
between H-1 and H-4 of 2,3-unsaturated-O-galactosides and arabinosides.
From the NOE analysis, a conclusion could be drawn that in the case of
2
,3-unsaturated-O-glucosides, H-1 and H-4 are on the same side, and in the
case of 2,3-unsaturated-O-galactosides and arabinosides, H-1 and H-4 are
on the opposite side, which is possible only in the case of a-configuration.
In conclusion, we explored a simple, economical, rapid, green method for
the synthesis of 2,3-unsaturated-O-glycosides by the Ferrier reaction in high

Table 1. Synthesis of 2,3-unsaturated-O-glycosides by the Ferrier reaction
Time
(min)
Yield
a
(%)
Power
(W)
b
Entry
Glycals (1)
Acceptors (2)
Products (3)
a/b
a
b
c
d
e
f
5
5
87
25
91
82
71
85
81
3/1
5/1
4/1
5/1
5/1
3/1
4/1
650
650
650
650
650
650
650
8
8
8
8
g
10

h
10
92
5/1
650
i
10
10
91
93
6/1
5/1
650
650
j
k
8
90
63
3/1
2/1
650
l
10
650
(
continued)

Table 1. Continued
Time
(min)
Yield
a
(%)
Power
(W)
b
Entry
Glycals (1)
Acceptors (2)
Products (3)
a/b
m
10
10
78
87
11/1
14/1
650
650
n
o
8
80
60
.20/1
5/1
650
650
p
10
q
10
70
9/1
650

r
10
64
8/1
650
s
t
8
71
74
.20/1
5/1
650
280
10
u
v
25
55
70
63
6/1
3/1
280
280
a
b
All yields are isolated yields after column chromatography.
The a/b ratio were determined by comparing the integration values of the peaks in H NMR analysis.
1

2
042
W. Du and Y. Hu
yields with good to high a selectivity. Furthermore, the method was applicable
not only to the Ferrier reaction of 3,4,6-tri-O-acetyl glucal and 3,4,6-tri-O-
acetyl galactal but also to the Ferrier reaction of 3,4-di-O-acetyl arabinal.
EXPERIMENTAL
The Ferrier reactions were carried out using microcomputer microwave reactor
LWMC 201. The silica gel (200–300 mesh, reagent grade) was obtained com-
mercially (Qingdao, China) and was not pretreated. Infrared spectra were
recorded on a Bruck Vector 200 spectrophotometer. NMR spectra were
recorded on a Brucker Advance DMX 400-MHz spectrometer with TMS as
the internal standard. Chemical shifts are expressed in parts per million
(
ppm). Elemental analysis was carried out on Carlo ERBA-1108 analyzer.
General Procedure for the Preparation of 2,3-Unsaturated-O-
Glycosides (3)
All reactions were carried out in an open vessel, sealed with a piece of film.
Silica gel (100 mg) was added to a mixture of glycal (1 mmol) and alcohol
(
8–10 mmol). The mixture was irradated with microwaves for the specified
period of time. The process was monitored by TLC. After completion of the
reaction, the excessive alcohol was recycled. The reaction mixture was
diluted with ethanol and filtered. The combined organic extract was concen-
trated under vacuum. All the products were purified by column chromato-
graphy over silica gel (using different ratios of ethyl acetate and petroleum
ether as eluent according to different products).
All known compounds gave NMR spectra that matched data reported in the
cited references. New compounds are characterized according to identity and
purity. Spectral data of products that are not reported are listed next.
Data
Cyclohexyl 4,6-di-O-acetyl-2,3-dideoxy-erythro-hex-2-eno-D-glucopyra-
noside (3 g): Colorless oil. IR (neat): 2933, 2858, 1744, 1450, 1370, 1231,
2
1
1
1
038, 911, 734 cm
m, 2 H, H-2, H-3), 5.29 (d, 0.80 H, J ¼ 9.6 Hz, H-4), 5.17 (s, 0.80 H, H-1),
.24–3.97 (m, 3 H, a, H-5, H-6), 3.70–3.59 (m, 1 H, OCH) 2.09, 2.08
2 Â s, 6 H, 2 Â COCH ), 1.56–1.18 (m, 10 H, cyclohexanol-H); b-configur-
; H NMR (CDCl ) a-configuration. d 5.92–5.80
3
(
4
(
3
ation. d 5.92–5.80 (m, 2 H, H-2, H-3), 5.25 (br s, 0.20 H, H-4), 5.21 (br s,
0.20 H, H-1), 4.24–3.97 (m, 3 H, a, H-5, H-6), 3.70-3.59 (m, 1 H, OCH)
2
.09, 2.08 (2 Â s, 6 H, 2 Â COCH ), 1.56–1.18 (m, 10 H, cyclohexanol-H);
3
1
3
C NMR (CDCl ): d 170.66 (C, CO), 170.20 (C, CO), 128.67 (C, Gly-C),
3
1
28.50 (C, Gly-C), 92.80 (C, Gly-C), 72.60 (C, Gly-C), 66.70 (C, Gly-C),

Microwave-Enhanced Ferrier Reaction
2043
6
2
5.39 (C, Gly-C), 63.10 (C, cyclohexanol-C), 33.60 (2 C, cyclohexanol-C),
9.60 (C, cyclohexanol-C), 25.51 (2 C, cyclohexanol-C) 24.31
(
C, CH3CO), 20.91 (C, CH CO). Anal. calcd. for C H O (312): C,
3
16 24 6
6
1.52; H, 7.74. Found: C, 61.77; H, 7.98.
Ethyl 4,6-di-O-acetyl-2,3-dideoxy-threo-hex-2-eno-D-galactopyranoside
(3 m): Colorless oil. IR (neat): 2926, 1741, 1370, 1230, 1104, 1049cm ; H
21 1
NMR (CDCl ) a-configuration. d 6.11 (dd, 1 H, J ¼ 10.0, 5.6 Hz, H-3), 6.04
3
(
dd, 0.92H, J ¼ 10.0, 3.2 Hz, H-2), 5.12–5.02 (m, 2 H, H-4, H-1), 4.39–4.36
(m, 1 H, H-5), 4.25–4.22 (m, 2 H, H-6), 3.86–3.81 (m, 0.92H, OCH CH ),
2
3
3
.63–3.56 (m, 1 H, OCH CH ), 2.08, 2.07 (2 Â s, 6 H, 2 Â COCH ), 1.25
2 3
2
3
3
(
t, 3 H, OCH CH ); b-configuration. d 6.11 (dd, 1 H, J ¼ 10.0, 5.6 Hz, H-3),
5
.97 (d, 0.09H, J ¼ 10.0Hz, H-2), 5.12–5.02 (m, 2 H, H-4, H-1), 4.39–4.36
2 3
(
m, 1 H, H-5), 4.25–4.22 (m, 2 H, H-6), 3.97–3.90 (m, 0.08H, OCH CH ),
.63–3.56 (m, 1 H, OCH CH ), 2.08, 2.07 (2 Â s, 6 H, 2 Â COCH ), 1.25
2 3 3
3
2
3
3
1
t, 3 H, OCH CH ); C NMR (CDCl ): d 170.43 (C, CO), 170.19 (C, CO),
3
(
1
6
1
30.55 (C, Gly-C), 124.92 (C, Gly-C), 93.56 (C, Gly-C), 70.70 (C, Gly-C),
6.48 (C, Gly-C), 63.77 (C, Gly-C), 62.66 (C, OCH ), 20.59 (2C, CH CO),
2
3
5.05 (C, OCH CH ). Anal. calcd. for C H O (258): C, 55.81; H, 7.02.
12 18 6
2
3
Found: C, 56.02; H, 7.28.
para-t-Butylbenzyl 4,6-Di-O-acetyl-2,3-dideoxy-threo-hex-2-eno-1-thio-
a-D-galactopyranoside (3o): Colorless oil. IR (neat): 2960, 1741, 1515,
2
1 1
1
6
368, 1231, 1052, 665 cm ; H NMR (CDCl ) d 7.34–7.27 (m, 4 H, Ar-H),
3
.13–6.10 (m, 1 H, H-3), 5.99 (dd, 1 H, J ¼ 9.6, 1.2 Hz, H-2), 5.19 (d, 1 H,
J ¼ 1.2 Hz, H-1), 5.10–5.08 (m, 1 H, H-4), 4.28–4.26 (m, 2 H, H-6), 3.99–
3
.95 (m, 2 H, H-5, PhCH ), 3.77 (d, 1 H, J ¼ 13.2Hz, PhCH ), 2.16, 2.09
3 3 3
2
2
1
3
(
2 Â s, 6 H, 2 Â COCH ), 1.31–1.26 (m, 9 H, CH ); C NMR (CDCl ): d
1
1
7
3
70.40 (2 C, CO), 149.94 (C, Ar-C), 134.22 (C, Ar-C), 133.03 (2 C, Ar-C),
28.64 (C, Gly-C), 125.27 (2 C, Ar-C), 124.66 (C, Gly-C), 77.63 (C, Gly-C),
3.79 (C, Gly-C), 63.24 (C, Gly-C), 62.88 (C, Gly-C), 34.31 (C, PhCH2),
2.73 [C, C(CH ) ], 31.14 [3 C, C(CH ) ], 20.70 (2 C, CH3CO). Anal. calcd.
3
3
3 3
for C H O S (392): C, 64.26; H, 7.19. Found: C, 64.49; H, 7.38.
1 28 5
2
Ethyl 4-O-acetyl-2,3-dideoxy-threo-hex-2-eno-L-arabinopyranoside (3p):
21 1
Colorless oil. IR (neat): 2977, 1736, 1372, 1237, 1053, 959 cm ; H NMR
(
(
CDCl ) a-configuration. d 6.05–6.01 (m, 1.68 H, H-2, H-3), 5.01
3
d, 0.84 H, J ¼ 2.4 Hz, H-1), 4.96–4.94 (m, 0.84 H, H-4), 4.17 (dd, 1 H,
J ¼ 13.2, 2.8 Hz, H-5), 3.85–3.81 (m, 2 H, H-5, OCH CH ), 3.59–3.52
2
3
(m, 1 H, OCH CH ), 2.08 (s, 3 H, COCH ), 1.24 (t, 3 H, OCH CH ); b-con-
2 3 3 2 3
figuration. d 5.96–5.85 (m, 0.32 H, H-2, H-3), 5.29–5.26 (m, 0.16 H, H-4),
.95 (br s, 0.16 H, H-1), 3.87–3.81 (m, 3 H, H-5, OCH ), 3.57–3.52
4
2
1
3
(
(
(
m, 1 H, OCH ), 2.08 (s, 3 H, COCH ), 1.24 (t, 3 H, OCH CH ); C NMR
2 3 2 3
CDCl ): d 170.43 (C, CO), 170.19 (C, CO), 130.55 (C, Gly-C), 124.92
3
C, Gly-C), 93.56 (C, Gly-C), 70.70 (C, Gly-C), 66.48 (C, Gly-C), 63.77

2
044
W. Du and Y. Hu
(C, Gly-C), 62.66 (C, OCH ), 20.59 (2 C, CH CO), 15.05 (C, OCH CH ).
Anal. calcd. for C H O (186): C, 58.05; H, 7.58. Found: C, 58.31; H, 7.79.
2
3
2
3
9
14 4
Benzyl
(
9
4-O-acetyl-2,3-dideoxy-threo-hex-2-eno-L-arabinopyranoside
3q): Colorless oil. IR (neat): 3032, 2924, 1739, 1455, 1371, 1235, 1041,
2
58, 911, 733, 698 cm ; H NMR (CDCl ) a-configuration. d 7.36–7.29
1 1
3
(
m, 5 H, Ar-H), 6.07–5.86 (m, 2 H, H-2, H-3), 5.09 (d, 0.90 H, J ¼ 2.8 Hz,
H-1), 4.96–4.95 (m, 0.90 H, H-4), 4.78 (d, 0.90 H, J ¼ 12.0 Hz, PhCH ),
2
4
.58 (d, 1 H, J ¼ 12.0 Hz, PhCH ), 3.89–3.85 (m, 2 H, H-5), 2.07 (s, 3 H,
2
COCH ); b-configuration. d 7.36–7.29 (m, 5 H, Ar-H), 6.07–5.86 (m, 2 H,
3
H-2, H-3), 5.33–5.30 (m, 0.10 H, H-4), 5.04 (br s, 0.10 H, H-1), 4.82
(
d, 0.10 H, J ¼ 12.0 Hz, PhCH ), 4.58 (d, 1 H, J ¼ 12.0 Hz, PhCH ), 3.89–
2
2
1
3
3
.85 (m, 2 H, H-5), 2.07 (s, 3 H, COCH ); C NMR (CDCl ): d 169.44
3 3
(
C, CO), 136.56 (C, Ar-C), 129.02–126.64 (5 C, Ar-C), 127.98 (C, Gly-C),
1
5
27.33 (C, Gly-C), 92.17 (C, Gly-C), 68.95 (C, Gly-C), 63.94 (C, Gly-C),
9.00 (C, PhCH ), 19.88 (2 C, CH CO). Anal. calcd. for C H O (248):
2
3
14 16 4
C, 67.73; H, 6.50. Found: C, 67.52; H, 6.21.
para-Chlorobenzyl 4-O-acetyl-2,3-dideoxy-threo-hex-D-eno-L-arabino-
pyranoside (3r): Colorless oil. IR (neat): 2884, 2361, 1738, 1492, 1371,
2
236, 1038, 960, 895, 744, 608 cm ; H NMR (CDCl ) a-configuration. d
.33–7.27 (m, 4 H, Ar-H), 6.09–6.02 (m, 1.78 H, H-2, H-3), 5.07
1 1
1
7
3
(
d, 0.89 H, J ¼ 3.2 Hz, H-1), 4.97–4.95 (m, 0.89 H, H-4), 4.74 (d, 0.89 H,
2 2
J ¼ 12.0 Hz, PhCH ), 4.55 (d, 0.89 H, J ¼ 12.0 Hz, PhCH ), 3.88–3.79
(
m, 2 H, H-5), 2.09–2.07 (m, 3 H, COCH ); b-configuration. d 7.33–7.27
3
(
m, 4 H, Ar-H), 5.9–5.85 (m, 0.22 H, H-2, H-3), 5.33–5.28 (m, 0.11 H,
H-4), 5.02 (s, 0.11 H, H-1), 4.77 (d, 0.11 H, J ¼ 12.0 Hz, PhCH ), 4.54
2
(
d, 0.11 H, J ¼ 12.0 Hz, PhCH ), 3.88–3.79 (m, 2 H, H-5), 2.09–2.07
2
1
3
(
m, 3 H, COCH ); C NMR (CDCl ): d 170.48 (C, CO), 136.22 (C, Ar-C),
3 3
133.52 (C, Ar-C), 129.30–128.86 (4 C, Ar-C), 129.28 (C, Gly-C), 128.57
(
C, Gly-C), 93.39 (C, Gly-C), 69.22 (C, Gly-C), 64.59 (C, Gly-C), 60.13
C, PhCH ), 20.95 (2 C, CH CO). Anal. calcd. for C H ClO (283): C,
(
2
3
14 15
4
59.48; H, 5.35. Found: C, 59.73; H, 5.58.
para-t-Butylbenzyl 4-O-acetyl-2,3-dideoxy-threo-hex-2-eno-1-thio-a-L-
arabinopyranoside (3s): Colorless oil. IR (neat): 2962, 1738, 1513, 1369,
2
234, 1058, 956, 842, 790 cm ; H NMR (CDCl ) d 7.33–7.23 (m, 4 H,
1 1
1
3
Ar-H), 5.97–5.82 (m, 2 H, H-2, H-3), 5.39 (d, 1 H, J ¼ 2.4 Hz, H-1), 5.38–
4
1
.96 (m, 1 H, H-4), 4.01–3.66 (m, 4 H, H-5, PhCH ), 2.06 (s, 3 H, COCH ),
2 3
1
.29–1.26 (m, 9 H, CH3); C NMR (CDCl ): d 170.39 (C, CO), 149.87
3
3
(
C, Ar-C), 134.78 (C, Ar-C), 129.69 (2 C, Gly-C), 128.59 (2 C, Ar-C),
1
3
25.40 (2 C, Ar-C), 77.82 (C, Gly-C), 64.88 (C, Gly-C), 60.16 (C, Gly-C),
4.62 (C, PhCH ), 34.40 (C, C(CH ) ), 31.27 [3 C, C(CH ) ], 20.88
2
3 3
3 3
(C, CH CO). Anal. calcd. for C H O S (320): C, 67.47; H, 7.55. Found:
3 18 24 3
C, 67.71; H, 7.80.

Microwave-Enhanced Ferrier Reaction
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