Silicon-catalyzed conversion of nitro compounds into ketones and poly(1,3-diketones)

Article abstract of DOI:10.1055/s-2006-950225

The reaction of various secondary nitro compounds with 1.1 equivalents of potassium hydride in 1,4-dioxane and then with 0.10 equivalent of chlorotrimethylsilane gave the corresponding ketones in 62-90% yields. By a similar strategy, poly(1,3-diketones) were synthesized directly from nitroalkenes with sodium ethoxide, potassium hydride, and chlorotrimethylsilane in 1,4-dioxane. The use of chlorotrimethylsilane in a catalytic amount was the key to the success of this transformation; the use of an excess of chlorotrimethylsilane led to poor yields for the same reactions. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2006-950225

SPECIAL TOPIC
3305
Silicon-Catalyzed Conversion of Nitro Compounds into Ketones and
Poly(1,3-diketones)
a
a
b
S
J
ilicon-C
a
i
talyzed
h
Conversionof
Nit
R
roCompounds in
u
to
K
etones and Po
H
ly(1,3-diketones) wu,* Thainashmuthu Josephrajan, Shwu-Chen Tsay
a
Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
Well-being Biochemical Corporation, Neihu Technology Park, Taipei 114, Taiwan
Fax +886(3)5721594; E-mail: jrhwu@mx.nthu.edu.tw
b
Received 1 May 2006
plish the Nef reaction. This new method would be suitable
for the general synthesis of ketones and polyketones from
the corresponding nitro compounds by the use of a silicon
Abstract: The reaction of various secondary nitro compounds with
1
.1 equivalents of potassium hydride in 1,4-dioxane and then with
0
.10 equivalent of chlorotrimethylsilane gave the corresponding ke-
tones in 62–90% yields. By a similar strategy, poly(1,3-diketones) reagent in a catalytic amount.
were synthesized directly from nitroalkenes with sodium ethoxide,
First, we polymerized b-nitrostyrene (3) by using sodium
potassium hydride, and chlorotrimethylsilane in 1,4-dioxane. The
use of chlorotrimethylsilane in a catalytic amount was the key to the
success of this transformation; the use of an excess of chlorotri-
methylsilane led to poor yields for the same reactions.
ethoxide as the initiator (Scheme 1).1
5a,c
The resultant
multiple Michael adduct 5 was produced in 85% yield
4
with molecular weight (MW) of 2.43 × 10 . In the second
step, polymer 5 was treated with 1.1 equivalents of potas-
sium hydride in 1,4-dioxane and then with 0.10 equivalent
of chlorotrimethylsilane at 101 °C for 24 hours. The cor-
responding poly(1-oxo-2-phenylethylene) (1) with mo-
Key words: nitro, ketone, poly(1,3-diketone), Nef reaction, silicon
Polymers with conjugated backbones show great potential
4
lecular weight 1.94 × 10 was obtained in 78% yield.
1
in industry. Some of these polymers are applied in photo-
Furthermore, we prepared polymer 1 directly from b-ni-
trostyrene (3) by a newly developed one-flask method. b-
Nitrostyrene (3) was treated with 0.050 equivalent of so-
dium ethoxide in 1,4-dioxane and then with 1.1 equiva-
lents of potassium hydride. To this solution was added
lithography, imaging technology, precise micro-fabrica-
2
tion, packing materials, etc. Even more important are
3
their valuable electronic and optical properties. Among
conjugated polymers of various types, polyketones show
high thermostability, chemical resistance, and high fa-
0
.10 equivalent of chlorotrimethylsilane as the catalyst.
4
tigue strength. Along the line of development of new
The reaction mixture was heated at reflux for 24 hours to
give the same polymer 1 in 74% yield. Similarly, we were
able to synthesize poly(oxoethylene) (2) directly from ni-
5
–8
methods in our laboratory for the synthesis of function-
9
,10
al polymers, we planned to obtain polymers with a re-
1
1–14
peating 1,3-diketone unit
1 and 2, also known as
4
troethene (4) with molecular weight 4.15 × 10 in 80%
polyketenes (Figure 1), by a new and efficient method.
yield.
Poly(1,3-diketones) 1 and 2 showed hydroxy absorptions
O
–1
at >3000 cm in their IR spectra and low field resonances
1
n
1 R = Ph
2 R = H
around d = 10 in their H NMR spectra. Consistent with
R
13
the data reported by Khemani and Wudl, these spectral
characteristics indicate that polymers 1 and 2 possess enol
units in their skeleton and can be also regarded as
polyketenes. These enol units enable poly(oxoethylene)
Figure 1
Living polymerization strategy provides a smooth and
controllable avenue for the conversion of nitroalkenes
(
2) to be soluble in water and ethylene glycol.
1
5
into polynitro materials. On the other hand, the transfor-
mation of nitro materials to ketones is known as the Nef
reaction, for which many conditions have been devel-
NaOEt
0.050 equiv)
NO2
n
(
NO2
R
EtOH
1
6
oped. The first systematic application of the silicon g-ef-
R
8
5–95%
3
R = Ph
fect to control an organic reaction was the silicon-
4 R = H
5 R = Ph
6 R = H
1
7
promoted Nef reaction, in which a silyl group is placed
into the reaction substrate. Thus b-silyl ketones can be
prepared from silicon-containing nitroalkenes using a
one-flask method under mild conditions. Herein we report
a different version of utilizing a silicon reagent to accom-
1
2
. KH (1.1 equiv)
. Me3SiCl (0.10 equiv)
O
1
,4-dioxane
8–82%
n
1
2
R = Ph
R = H
7
R
Scheme 1
SYNTHESIS 2006, No. 19, pp 3305–3308
x
x.
x
x
.
2
0
0
6
Advanced online publication: 04.09.2006
DOI: 10.1055/s-2006-950225; Art ID: C04606SS
Georg Thieme Verlag Stuttgart · New York
©

3
306
J. R. Hwu et al.
SPECIAL TOPIC
To broaden the scope of the silicon-catalyzed Nef reac- to react with nitro compound 13. The desired ketone 14
tion, we investigated its application to organic substrates was obtained in 11% yield only. In contrast, reaction of
(
Scheme 2). Thus we removed the acidic proton from ben- various nitro compounds shown in Table 1 with 0.10
zylic nitro compound 9 with 1.1 equivalents of potassium equivalent of chlorotrimethylsilane afforded the corre-
hydride in 1,4-dioxane at low temperature. Then we added sponding ketones in 62–90% yields; the starting material
0
.10 equivalent of chlorotrimethylsilane to the nitronate was recovered in 6–10% yields. These results provide ev-
solution, which was heated at reflux for 12 hours. After idence to show the role of the silicon reagent chlorotri-
workup under anhydrous conditions, acetophenone (10) methylsilane as a catalyst.
was isolated in 90% yield (Table 1). Moreover, we con-
verted aralkyl nitro compound 11 into ketone 12 in 82%
yield, monocyclic nitro compound 13 into ketone 14 in
This new silicon-catalyzed strategy can be applied suc-
cessfully to the conversion of secondary nitro compounds
into ketones. However, we found that the use of primary
nitro compounds as the starting material did not afford al-
dehydes in appealing yields.
8
0% yield, and bicyclic nitro compounds 15 and 17 into
ketones 16 and 18 in 62% and 81% yields, respectively. In
all of our experiments, no explosion was encountered dur-
ing the handling of these nitro compounds.
Our mechanistic route for the conversion of secondary ni-
tro compounds into ketones under anhydrous conditions is
shown in Scheme 3. We believe that the potassium salt of
NO2
O
1. KH (1.1 equiv)
2
0, generated from nitronate 19 by silylation, could de-
R1
R2 2. Me SiCl (0.10 equiv)
R1
R2
3
compose upon heating. Once 20 gives fragments 21 and
7
1,4-dioxane
8
–
+
Me SiO , the latter would attack the carbon of C=N in 21
3
Scheme 2
to afford a-siloxy-a-nitroso intermediate 22.
NO2
R2
O
We also found that potassium hydride was a better base
than lithium hydride for the transformations shown in
Schemes 1 and 2; the use of the former gave ketones 8 in
much better yields. Seebach et al. reported that the lithi-
um salts of nitronates are more stable than the potassium
salts, which possess more ionic character.
1. KH, 1,4-dioxane
R1
R1
R2
2. Me SiCl (0.10 equiv)
3
7
8
heat
1
8
pathway b
1
. KH
O
O
SiMe3
N
In a control experiment, we used 1.1 equivalents of potas-
sium hydride and 1.5 equivalents of chlorotrimethylsilane
N
O
O
pathway a
R1
R2
R1
R2
2
2
1
9
Table 1 Conversion of Secondary Nitro Compounds into Ketonesa
2
. Me3Si Cl
Me3SiO
Substrate
Product
Yield (%)
90
O
N
NO2
O
O
OSiMe3
R2
N
Ph
Ph
R1
R1
R2
9
10
2
0
2
1
NO2
O
82
80
Scheme 3
Ph
Ph
O
1
1
1
3
12
14
For the reactions shown in Schemes 2 and 3, we convert-
ed all of the nitro starting materials into nitronates 19.
However, no more than 10% of the nitronates were sily-
lated in the beginning through ‘pathway a’ because we
used only 0.10 equivalent of chlorotrimethylsilane. The
remaining nitronates became an ideal nucleophile to at-
tack the silicon atom in 22, as shown by ‘pathway b’.
While the nitroso compounds 22 lead to the desired ke-
tones 8, some of nitronates 19 are converted into silylated
species 20. Such a catalytic cycle repeats until completion
of the entire transformation. Thus, conversion of second-
ary nitro compounds into ketones under alkaline condi-
tions requires only a catalytic amount of silicon-
containing reagent.
NO2
SiMe3
SiMe3
6
2
NO2
O
1
6
1
5
Me3Si
Me3Si
81
NO2
O
1
8
In conclusion, a novel reaction has been developed for the
conversion of secondary nitro compounds into ketones in
1
7
a
KH (1.1 equiv), Me SiCl (0.10 equiv), 1,4-dioxane.
3
Synthesis 2006, No. 19, 3305–3308 © Thieme Stuttgart · New York

SPECIAL TOPIC
Silicon-Catalyzed Conversion of Nitro Compounds into Ketones and Poly(1,3-diketones)
): d = 2.49–2.65 (br d, 2 H, CH
3307
good to excellent yields. Furthermore, this reaction was 1H NMR (80 MHz, CDCl
successfully applied to a one-flask synthesis of poly(1,3-
diketones) from nitroalkenes.
), 4.59–
3
2
4
.75 (br m, 1 H, CHNO2).
Anal. Calcd for (C H NO ) : C, 32.88; H, 4.14; N, 19.17. Found: C,
2
3
2 n
3
3.01; H, 4.15; N, 19.22.
All reactions were carried out in oven-dried glassware (120 °C) un-
Poly(1-oxo-2-phenylethylene) (1); Method A
To a stirred soln of poly(nitrostyrene) (5; 4.65 g, 1.0 equiv) in 1,4-
dioxane (104 mL) was added KH (1.38 g, 1.1 equiv). The mixture
der an atmosphere of N . EtOAc and hexanes from Tilley Chemical
2
Co. were dried and distilled from CaH . 1,4-Dioxane from J. T.
2
Baker Chemical Co. was freshly distilled from Na and benzophe-
stirred at r.t. for 30 min and then Me SiCl (339 mg, 3.12 mmol, 0.10
3
none. Me SiCl, from Aldrich Chemical Co., was distilled from
3
equiv) was added and the mixture was stirred at r.t. for 2.0 h and
then heated at reflux for 24 h. The cooled mixture was diluted with
hexanes and a golden solid was precipitated. The solid was washed
CaH . Analytical TLC analyses were performed on precoated plates
2
(silica gel GHLF), purchased from Analtech Inc. using EtOAc–hex-
ane mixtures as eluents; the visualization of spots on TLC plates
was performed using UV light or 2.5% phosphomolybdic acid in
EtOH with heating. GC analyses were carried out on a Hewlett–
Packard 5794 instrument equipped with a 12.5-m, cross-linked me-
thyl silicone gum capillary column (0.20 mm i.d.); the injector tem-
perature was set at 260 °C. Purification by gravity column
chromatography was performed with EM Reagents Silica Gel 60
with hexanes and CCl , and then dried under reduced pressure over
4
P O to give polymer 1; yield: 2.87 g (78%); soluble in CHCl ; MW
2
5
3
4
1
.94 × 10 .
IR (KBr): 3377 (br s, OH), 3060 (m), 3030 (m), 2925 (m), 2854 (m),
–
1
1
693 (w, C=O), 1598 (br s, C=C), 758 (m), 696 (s, =CH) cm .
1
H NMR (80 MHz, CDCl ): d = 5.34 (br s, 0.3 H, PhCH), 7.15–7.35
3
(
particle size 0.063–0.200 mm, 70–230 mesh ASTM). Separations
(br m, 5 H, C H ), 9.75–11.28 (br s, 0.7 H, =COH).
6
5
by radial thin-layer chromatography were performed on a model
Anal. Calcd for (C H O) : C, 81.34; H, 5.12. Found: C, 81.54; H,
8
6
n
7
1
924T Chromatotron from Harrison Research. The plates with
mm thickness were coated with EM Reagents Silica Gel 60 PF254
5
.10.
containing gypsum.
Poly(1-oxo-2-phenylethylene) (1); Method B in One Flask
NaOEt (148 mg, 2.17 mmol, 0.050 equiv) was added into a soln of
trans-b-nitrostyrene (3; 6.48 g, 43.5 mmol, 1.0 equiv) in 1,4-diox-
ane (435 mL) and the mixture was stirred at r.t. for 24 h. Then a 1,4-
dioxane soln of KH (1.92 g, 1.1 equiv) was added to the mixture and
IR spectra were measured on a Perkin–Elmer 1600 Series FT-IR.
The wave numbers reported are referenced to the polystyrene 1601
–
1
1
cm absorption. H NMR spectra were obtained on a Varian CFT-
0 (80 MHz) spectrometer using CDCl or DMSO-d as solvent and
2
3
6
TMS as an internal standard. HRMS and EIMS were obtained by
means of a VG Analytical 70-S mass spectrometer. The molecular
weight (MW) of polymers was determined by gel permeation chro-
matography.
stirring was continued at 10 °C for 1.5 h. Me SiCl (473 mg, 4.36
3
mmol, 0.10 equiv) was injected into the soln and this was stirred at
r.t. for 2.0 h and then heated at reflux for 24 h. The cooled mixture
was diluted with hexanes and a golden solid was precipitated. The
solid was washed with hexanes and CCl , and was then dried under
4
Secondary Nitro Compounds
reduced pressure over P O to give polymer 1; yield: 3.79 g (74%).
2
5
(1-Nitroethyl)benzene (9), (3-nitrobutyl)benzene (11), and 1,7,7-
trimethyl-2-nitrobicyclo[2.2.1]heptane (15) were produced by con-
Poly(oxoethylene) (2); Method A
To a stirred soln of poly(nitroethylene) (6; 2.51 g, 1.0 equiv) in 1,4-
dioxane (114 mL) was added KH (1.52 g, 1.1 equiv). The mixture
was stirred at r.t. for 30 min and then Me SiCl (374 mg, 3.44 mmol,
1
9
densation of the corresponding ketones with hydroxylamine, fol-
lowed by oxidation of the resultant ketoximes with
2
0
peroxytrifluoroacetic acid.
3
0
.10 equiv) was added and the mixture was stirred at r.t. for 2.0 h
Poly(nitrostyrene) (5)15a,c
To a stirred soln of trans-b-nitrostyrene (3; 5.89 g, 39.5 mmol, 1.0
equiv) in EtOH (395 mL) was added NaOEt (134 mg, 1.97 mmol,
and then heated at reflux for 24 h. The cooled mixture was diluted
with hexanes and a brown solid was precipitated. The solid was
washed with hexanes and CCl , and was then dried under reduced
pressure over P O to give polymer 2; yield: 1.18 g (82%); soluble
in ethylene glycol and H O; MW 4.15 × 10 .
4
0
.050 equiv). The mixture was stirred at r.t. for 24 h, and after this
2
5
4
time white solids were collected. The solids were purified by wash-
ing with MeOH (2 ×) and then dried under reduced pressure over
P O . Polymer 5 was thus obtained as a white solid; yield: 5.01 g
2
IR (KBr): 3385 (s, OH), 3270 (s, OH), 2957 (m), 2925 (m), 1690 (w,
C=O), 1596 (br s, C=C), 1150 (w, C–O) cm .
2
5
–1
4
(
85%); MW 2.43 × 10 .
1
H NMR (80 MHz, CDCl ): d = 3.40–4.70 (br s, 0.3 H, COCH CO),
3
2
IR (KBr): 3060 (m), 3025 (m), 2895 (m), 1554 (s, N–O), 1360 (s,
N–O), 732 (s), 696 (s, =CH) cm .
9
.81–11.32 (br s, 0.7 H, =COH).
–
1
Anal. Calcd for (C H O) : C, 57.14; H, 4.80. Found: C, 56.99; H,
4
1
2
2
n
H NMR (80 MHz, DMSO): d = 4.76–5.20 (br m, 1 H, CHNO ),
2
.78.
5
.60–6.25 (br m, 2 H, PhCH).
Anal. Calcd for (C H NO ) : C, 64.42; H, 4.73; N, 9.39; O, 21.45.
Found: C, 64.31; H, 4.75; N, 9.43.
Poly(oxoethylene) (2); Method B in One Flask
NaOEt (149 mg, 0.050 equiv) was added to a soln of nitroethene (4;
8
7
2 n
3
.20 g, 43.8 mmol, 1.0 equiv) in 1,4-dioxane (439 mL) and the mix-
Poly(nitroethylene) (6)15b
ture was stirred at r.t. for 24 h. Then a 1,4-dioxane soln of KH (1.94
g, 1.0 equiv) was added to the mixture and stirring was continued at
10 °C for 1.5 h. Me SiCl (477 mg, 4.39 mmol, 0.10 equiv) was in-
jected into the soln and this was stirred at r.t. for 2.0 h and then heat-
ed at reflux for 24 h. The cooled mixture was diluted with hexanes
and a brown solid was precipitated. The solid was washed with hex-
anes and CCl and then was dried under reduced pressure over P O
To a stirred soln of nitroethene (4; 5.03 g, 68.9 mmol, 1.0 equiv) in
EtOH (690 mL) was added NaOEt (234 mg, 3.44 mmol, 0.050
equiv). The mixture was stirred at r.t. for 14 h, and after this time a
white solid was obtained. The solid was purified by washing with
H O (1 ×), MeOH (2 ×), Et O (2 ×) and then dried under reduced
3
2
2
pressure over P O to give polymer 6; yield: 4.78 g (95%); soluble
2
5
4
2
5
4
in DMSO, THF, and DMF; MW 7.12 × 10 .
to give polymer 2; yield: 1.47 g (80%).
IR (KBr): 3000 (m), 2907 (m), 1559 (br s, N–O), 1436 (m), 1363 (br
–
1
m, N–O), 849 (s, =CH) cm .
Synthesis 2006, No. 19, 3305–3308 © Thieme Stuttgart · New York

3
308
J. R. Hwu et al.
SPECIAL TOPIC
Nef Reactions; General Procedure
References
In a one-necked, round-bottomed flask with a stirring bar and a rub-
ber septum, 35% KH (1.1 equiv) was washed with hexanes (3 × 5.0
mL). Hexanes were then removed to give KH as a white powder.
The nitro compound (1.0 equiv) and 1,4-dioxane were added to the
(1) For reviews, see: (a) Liu, Y.; Li, Y.; Schanze, K. S. J.
Photochem. Photobiol. C 2002, 3, 1. (b) Kraft, A.;
Grimsdale, A. C.; Holmes, A. B. Angew. Chem. Int. Ed.
1
998, 37, 402.
2) For recent reviews, see: (a) Holdcroft, S. Adv. Mater.
Weinheim, Ger.) 2001, 13, 1753. (b) Jager, E. W. H.;
flask. After 1.0 h of stirring at 10 °C, Me SiCl (0.10 equiv) was add-
3
(
ed to the reaction flask. Stirring was continued at r.t. for 2.0 h and
then heated at reflux for 12–24 h. The cooled mixture was filtered
through Celite and the solvents were removed under reduced pres-
sure. The resultant liquid was purified by chromatography to give
the desired ketone, of which the purity was >99.5% as checked by
GC.
(
Smela, E.; Inganäs, O. Science 2000, 290, 1540.
3) For books, see: (a) Barford, W. Electronic and Optical
Properties of Conjugated Polymers; Clarendon Press:
Oxford, 2005. (b) Blythe, T.; Bloor, D. Electrical Properties
of Polymers; Cambridge University Press: Cambridge, 2005,
Chapters IX and X.
(
Representative Examples
Camphor (16)
The standard procedure was followed by using 15 (1.17 g, 6.38
mmol, 1.0 equiv), KH (281 mg, 1.1 equiv), Me SiCl (69.3 mg,
(4) For recent works on polyketones, see: (a) Aly, K. I.;
Monem, M. I. A. J. Appl. Polym. Sci. 2005, 98, 2394.
(
b) Nozaki, K. Pure Appl. Chem. 2004, 76, 541. (c) Guo, J.;
Liu, B.; Wang, X.; Sun, J. React. Funct. Polym. 2004, 61,
63.
3
0
.638 mmol, 0.10 equiv), and 1,4-dioxane (64 mL). The mixture
1
was heated at reflux for 15 h. After purification by use of a Chroma-
totron (10% EtOAc–hexanes), ketone 16 was obtained as a white
solid in 62% yield; GC (column program: initial temperature 70 °C,
duration 2.00 min; increment rate 15 °C/min; final temperature
(
(
5) Hwu, J. R.; King, K. Y. Chem. Eur. J. 2005, 10, 3085.
6) Hwu, J. R.; Chen, J. H.; King, K. Y. Macromolecules 2004,
37, 3968.
(
7) Kuo, T.-Y.; Hwu, J. R.; Chang, T.-M. US 5 679 861, 1997.
2
50 °C) t 4.33 min. Its physical properties and spectroscopic char-
R
2
1
(8) Hwu, J. R.; Kuo, T.-Y.; Chang, T. M.; Patel, H. V.; Yong,
acteristics are consistent with those of an authentic sample.
Mp 176.5–177.5 °C (Lit.21 175.0–176.0 °C).
Rf 0.36 (20% EtOAc–hexanes).
K.-T. Fullerene Sci. Technol. 1996, 4, 407.
9) Chung, T. C. Prog. Polym. Sci. 2002, 27, 39.
(
(10) Braun, D.; Cherdron, H.; Ritter, H. Polymer Synthesis:
Theory and Practice; Springer: Berlin, 2001.
11) Voronkov, M. G.; Trukhina, A. A.; Vlasova, N. N. Russ. J.
Org. Chem. 2004, 40, 357.
12) Olah, G. A.; Zadok, E.; Edler, R.; Adamson, D. H.; Kasha,
W.; Prakash, G. K. S. J. Am. Chem. Soc. 1989, 111, 9123.
(13) Khemani, K. C.; Wudl, F. J. Am. Chem. Soc. 1989, 111,
IR (CCl ): 2954 (s), 2872 (s), 1743 (s, C=O), 1449 (s), 1414 (m),
4
(
1
390 (s), 1367 (m), 1326 (m), 1272 (w), 1190 (w), 1161 (w), 1114
–
1
(w), 1043 (m), 1014 (m) cm .
(
1
H NMR (80 MHz, CDCl ): d = 0.83 (s, 3 H, CH ), 0.91 (s, 3 H,
3
3
CH ), 0.96 (s, 3 H, CH ), 1.14–1.79 (m, 5 H, 2 × CH + CH), 1.85–
2
3
3
2
.46 (m, 2 H, CH CO).
2
9124.
(
(
14) Hiraguri, Y.; Endo, T. J. Am. Chem. Soc. 1987, 109, 3779.
15) For representative works, see: (a) Berry, R. W. H.; Mazza,
R. J.; Sullivan, S. F. Makromol. Chem. 1984, 185, 559.
HRMS (EI): m/z calcd for C H O: 152.1201; found: 152.1209.
1
0
16
7
-syn-(Trimethylsilyl)bicyclo[2.2.1]hept-5-en-2-one (18)
(
b) Ranganathan, D.; Rao, C. B.; Ranganathan, S.; Mehrotra,
The general procedure was followed. The mixture was heated at re-
flux for 24 h. After purification by use of a Chromatotron (5.0%
EtOAc–hexanes), ketone 18 was obtained as a colorless oil in 81%
yield; GC (column program: initial temperature 55 °C, duration
A. K.; Iyengar, R. J. Org. Chem. 1980, 45, 1185. (c)Carter,
M. E.; Nash, J. L. Jr.; Drueke, J. W. Jr.; Schwietert, J. W.;
Butler, G. B. J. Polym. Sci., Polym. Chem. Ed. 1978, 16, 937.
16) For reviews on the Nef reaction, see: (a) Ballini, R.; Petrini,
M. Tetrahedron 2004, 60, 1017. (b) Mundy, B. P.; Ellerd,
M. G.; Favaloro, F. G. Jr. Name Reactions and Reagents in
Organic Synthesis, 2nd ed.; Wiley: New Jersey, 2005.
(
2
.00 min; increment rate 10 °C/min; final temperature 200 °C) tR
8
.02 min. Its physical properties and spectroscopic characteristics
2
2
are consistent with those reported in literature.
Rf 0.34 (5% EtOAc–hexanes).
(
c) Pinnick, H. W. Org. React. 1990, 38, 655. (d) Nielsen,
IR (neat): 3060 (w, =C–H), 2955 (s), 2849 (m), 1737 (s, C=O), 1461
A. T. In The Chemistry of Functional Groups: Nitrones,
Nitronates and Nitroxides; Patai, S.; Rappoport, Z., Eds.;
Wiley: London, 1989, Chap. 1.
(
w, C=C), 1414 (w), 1314 (m), 1249 (s, Si–CH ), 1114 (m), 1055
3
(
m), 950 (m), 927 (m), 838 (s), 785 (w), 767 (w), 738 (w), 709 (m)
–
1
cm .
(17) Hwu, J. R.; Gilbert, B. A. J. Am. Chem. Soc. 1991, 113,
1
5917.
H NMR (80 MHz, CDCl ): d = 0.00 [s, 9 H, Si(CH ) ], 1.54–1.72
3
3 3
(
18) Colvin, E. W.; Beck, A. K.; Bastani, B.; Seebach, D.; Kai,
Y.; Dunitz, J. D. Helv. Chim. Acta 1980, 63, 697.
19) Guziec, F. S. Jr.; Russo, J. M. Synthesis 1984, 479.
20) Emmons, W. D.; Pagano, A. S. J. Am. Chem. Soc. 1955, 77,
4557.
21) Catalog Handbook of Fine Chemicals, Aldrich; Aldrich
Chemical: Milwaukee, 2005–2006, 568.
(
m, 1 H, Me SiCH), 1.81–2.10 (m, 2 H, CH CO), 2.90–3.05 (m, 1
3
2
H, =C–CH), 3.06–3.25 (m, 1 H, =C–CHCO), 5.89–6.03 (m, 1 H,
(
(
=CH), 6.43 (dd, J = 2.9, 5.2 Hz, 1 H, =CH).
+
HRMS (EI): m/z (M – CH ) calcd for C H OSi: 165.0736; found:
3
9
13
1
65.0738.
(
(
22) Hwu, J. R.; Gilbert, B. A.; Lin, L. C.; Liaw, B. R. J. Chem.
Soc., Chem. Commun. 1990, 161.
Acknowledgment
For financial support, we thank the National Science Council of the
Republic of China and the donors of Petroleum Research Fund, ad-
ministered by the American Chemical Society.
Synthesis 2006, No. 19, 3305–3308 © Thieme Stuttgart · New York