Reaction between 1,3-dicarbonyl-containing CH acids and dialkyl acetylenedicarboxylates in the presence of silica gel in solvent-free conditions: An efficient method for the synthesis of electron-poor alkenes and pyranes

Article abstract of DOI:10.1080/00397910802517830

A two-component condensation reaction between a 1,3-dicarbonyl-containing CH acid and an electron-poor acetylenic ester efficiently provides fully substituted electron-poor alkenes and pyranes in a one-pot reaction in the presence of silica gel in solvent

Full text of DOI:10.1080/00397910802517830

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Reaction Between 1,3-
Dicarbonyl-Containing
CH Acids and Dialkyl
Acetylenedicarboxylates in
the Presence of Silica Gel
in Solvent-Free Conditions:
An Efficient Method for the
Synthesis of Electron-Poor
Alkenes and Pyranes
Ali Ramazani a & Nader Noshiranzadeh a
a Chemistry Department, Zanjan University, Zanjan,
Iran
Published online: 04 Mar 2009.
To cite this article: Ali Ramazani & Nader Noshiranzadeh (2009) Reaction Between
1,3-Dicarbonyl-Containing CH Acids and Dialkyl Acetylenedicarboxylates in the
Presence of Silica Gel in Solvent-Free Conditions: An Efficient Method for the
Synthesis of Electron-Poor Alkenes and Pyranes, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 39:7,
1204-1214
To link to this article: http://dx.doi.org/10.1080/00397910802517830

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Synthetic Communications1, 39: 1204–1214, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802517830
Reaction Between 1,3-Dicarbonyl-Containing
CH Acids and Dialkyl Acetylenedicarboxylates
in the Presence of Silica Gel in Solvent-Free
Conditions: An Efficient Method for the
Synthesis of Electron-Poor Alkenes and Pyranes
Ali Ramazani and Nader Noshiranzadeh
Chemistry Department, Zanjan University, Zanjan, Iran
Abstract: A two-component condensation reaction between a 1,3-dicarbonyl-
containing CH acid and an electron-poor acetylenic ester efficiently provides
fully substituted electron-poor alkenes and pyranes in a one-pot reaction in the
presence of silica gel in solvent-free conditions.
Keywords: Acetylenic ester, CH acid, 1,3-diketone, electron-poor alkene, pyrane,
silica gel, solvent-free conditions
INTRODUCTION
Environmentally friendly synthesis of organic compounds without
using of organic solvents has come several steps closer in recent years.[1]
Organic reactions using conventional organic solvents, especially
chlorinated hydrocarbons, have posed a serious threat to the environ-
ment because of their toxicity and volatile nature.[1] In this regard,
solvent-free catalytic organic reactions have received tremendous
attention in recent times.[2]
Received June 30, 2008.
Address correspondence to Ali Ramazani, Chemistry Department, Zanjan
University, P. O. Box 45195-313, Zanjan, Iran. E-mail: aliramazani@yahoo.com
1204

Electron-Poor Alkenes and Pyranes
1205
Solvent-free conditions are especially suitable for organic synthesis.
Environmentally benign synthesis can be easily designed using this
methodology:
. The use of large volumes of solvent is avoided, reducing solvent
emissions and redistillation.
. Workup is considerably simplified because in many cases the pure
product can be obtained directly from the crude reaction mixture by
simple extraction, distillation or sublimation.
. Recyclable solid supports can be used, replacing highly polluting
mineral acids and oxidants.
. Scale-up is facilitated by the absence of solvent.
. Safety is increased by reducing the risk of overpressure and explo-
sions.[3]
For several years, acetylenic esters have been attracting the attention
of organic chemists.[4–8] Acetylenic esters are reactive systems and take
part in many chemical syntheses.[4–8] The compounds almost act as
Michael acceptors in the organic reactions.[9] In the recent years, there
has been increasing interest in the applications of acetylenic esters in mul-
ticomponent[10–14] synthesis. Because of the atom economy, convergent
character, and simplicity of one-pot procedures, multicomponent con-
densation reactions (MCRs) have an advantageous position among other
reactions. The discovery and development of novel MCRs is receiving
growing interest from industrial chemistry research groups and represents
a new challenge for organic chemists and to the basic understanding of
organic chemistry itself.[15]
Silica gel as an additive promotes many condensation reactions in
solvent-free conditions.[16–21] Continuing our interest in solvent-free
synthesis (Ramazani reaction),[6] herein we report on a hitherto unknown
two-component reaction, which, starting from simple and readily
available precursors, affords fully functionalized electron-poor alkenes
and pyranes in a one-pot reaction in the presence of silica-gel powder
in solvent-free conditions.
RESULTS AND DISCUSSION
The 1,3-dicarbonyl-containing CH acids 1, 4, 6, and 8 and dialkyl acetyle-
nedicarboxylates 2 in the presence of silica-gel powder underwent a smooth
1:1 addition reaction in solvent-free conditions at 90ꢀC in 30 min to pro-
duce compounds 3, 5, 7, 9, 10, and 11(Scheme 1–4). The reaction proceeded
smoothly and cleanly under mild conditions, and no side reactions were

1206
A. Ramazani and N. Noshiranzadeh
Scheme 1.
observed. In the absence of the silica-gel powder, the starting materials were
not reacted under reaction conditions (90 ꢀC, 30 min) in the solvent-free
system. The reaction also did not occur in dichloromethane solutions after
several days. Thin-layer chromatography (TLC) indicated the formation of
products 3, 5, 7, 9, and 11 on the silica-gel surface. Compounds 10 are not
stable and rearranged to products 11 due to staying at room temperature in
solvent (CHCl3), neat or on the silica-gel surface. The conversion of com-
pounds 10 to products 11 is fairly fast in CHCl3 (or CDCl3) solution, and
it was completed less than 20min. In the other cases (silica-gel surface, neat,
and in solvents of CH2Cl2, ethyl acetate, and petroleum ether), the conver-
sion is very slow and was not complete after several days. These results
show that products 11 are more stable than compounds 10. We have not
investigated the role of CHCl3 (or CDCl3) solution in the fast conversion
of the compounds 10 to compounds 11. It seems that the presence of trace
amounts of HCl (or DCl) in the CHCl3 (or CDCl3) solution may be the fac-
tor as acid catalyst in the increasing of the conversion rate. In the case of the
mixture of compounds 10 and 11, we prepared the 1H NMR (CDCl3) spec-
trum. The chemical shifts (dH) for 10 [3.54 and 3.66 (6 H, 2 s, 2 OCH3); 5.28
(1 H,1 s, ¼ CH); 7.43-8.14 (10 H, m, arom); 17.20 (1 H, 1 s, OH)] and 11
[3.35 (2 H, 1 s, CH2); 3.52 and 3.64 (6 H, 2 s, 2 OCH3); 7.43-8.14 (10 H,
m, arom)] were assigned from the spectra. The relative population of
Scheme 2.

Electron-Poor Alkenes and Pyranes
1207
Scheme 3.
10:11 (40:60) was estimated on the basis of 1H NMR (CDCl3) spectrum of
the mixture. About after 10 min, the intermediate 10 was completely con-
verted to the product 11 in CDCl3 solution at room temperature and in
the 1H NMR (CDCl3) spectrum, signals of only 11 were observed. The 1H
NMR (CDCl3) spectra of compounds 5 show the presence of two estereoi-
somers (E and Z) for each alkenes. The relative population of E and Z iso-
mers were determined via their 1H NMR spectra (see Experimental section).
The mechanism of the reaction between the 1,3-dicarbonyl-
containing CH acids 1, 4, 6, and 8 and dialkyl acetylenedicarboxylate 2
in the presence of silica-gel powder in solvent-free conditions has not
been established experimentally. Michael addition of the enol form of
1,3-dicarbonyl-containing CH acid to the acetylenic ester in the presence
of silica gel as general acid–base catalyst may be considered as a plausible
mechanism.[6] The structures of the products were deduced from their IR,
1H NMR, and 13C NMR spectra (see Experimental section).
Scheme 4.

1208
A. Ramazani and N. Noshiranzadeh
CONCLUSIONS
In summary, we have found a new and efficient method for the synthesis
of fully substituted electron-poor alkenes and pyranes from 1,3-dicarbo-
nyl-containing CH acids and electron-poor acetylenic esters, in a one-pot
reaction in the presence of silica gel in solvent-free conditions. We believe
the reported method offers a mild, simple, and efficient route for the
preparation of substituted electron-poor alkenes and pyranes. Its ease
of workup, high yields, and fairly short reaction times make it a useful
addition to modern synthetic methodologies. Other aspects of this pro-
cess are under investigation.
EXPERIMENTAL
Starting materials and solvents were obtained from Merck (Germany)
and Fluka (Switzerland) and were used without further purification.
Flash chromatography columns were prepared from Merck silica-gel
powder. Elemental analyses for C and H were performed using a Heraeus
CHN-O-Rapid analyzer. IR spectra were measured on a Shimadzu
1
IR-460 spectrometer. H and 13C NMR spectra were measured (CDCl3
solution) with a Bruker DRX-250 Avance spectrometer at 250.0 and
62.5 MHz, respectively.
General Procedure
A homogenous mixture of 1,3-dicarbonyl-containing CH-acid derivative
(1 mmol), dialkyl acetylenedicarboxylate (1 mmol), and powdered silica
gel (0.7 g) were heated in a oven at 90 ꢀC for 30 min and then placed over
a column of silica gel (12 g). The column chromatography was performed
using ethyl acetate-light petroleum ether (1:10) as eluent. The solvent was
removed under reduced pressure, and the products were obtained as oils.
Relative populations of E and Z stereoisomers for the compounds 5a–5b
were determined via their 1H NMR spectra. The characterization data of
the new compounds are given next.
Data
Dimethyl (E)-2-[(Z)-1-Acetyl-2-hydroxy-1-propenyl]-2-butendioate (3a)
Yellow oil, yield 80%, IR (neat) (nmax, cmꢁ1): 2954 (CH, alipha); 1727
(C ¼ O, ester); 1612 (C ¼ C, alkene). Anal. calcd for C11H14O6 (242): C,

Electron-Poor Alkenes and Pyranes
1209
54.54; H, 5.83. Found: C, 54.51; H, 5.80%.1H NMR (CDCl3) dH: 1.95
(6H, 1s, 2CH3); 3.75 and 3.84 (6H, 2s, 2OCH3); 7.08 (1H, 1s, ¼ CH);
16.57 (1H, 1s, OH). 13C NMR (CDCl3) dC: 23.50 (2CH3); 52.24 and
53.16 (2OCH3); 106.98, 139.87 (2C); 132.03 (CH ¼ ); 165.08 and 166.7
(C ¼ O of ester); 189.93 (C ¼ O of keton).
Diethyl (E)-2-[(Z)-1-Acetyl-2- hydroxyl-1-propenyl]- 2- butenedioate (3b)
Yellow oil, yield 75%, IR (neat) (mmax, cmꢁ1) : 2954 (CH, alipha); 1727
(C ¼ O, ester); 1612 (C ¼ C, alkene). Anal. Calcd. for C13H18O6 (270): C,
1
57.77; H, 6.71. Found: C, 57.74; H, 6.67%. H NMR (CDCl3) dH: 1.24
and 1.30 ( 6H, 2 t, 3JHH ¼ 7.25 Hz, 2CH3 of 2Et); 1.94 (6H, 1s, 2CH3); 4.18
3
and 4.28 (4H, 2q, JHH ¼ 7.25 Hz, 2OCH2 of 2Et); 7.06 (1H, 1s, ¼ CH);
16.51 (1H, 1s, OH).13C NMR (CDCl3) dC: 14.00 and14.10 (2CH3 of 2Et);
23.44 (2CH3); 61.19 and 62.14 (2OCH2); 107.13 and 139.49 (2C); 132.29
(CH ¼ ); 164.76 and 166.15 (2C ¼ O of ester); 189.84 (C ¼ O of keton).
Dimethyl-(E)-2-[1-(2,2-dimethylpropanoyl)-3,3-dimethyl-2-oxobutyl]-
2-butenedioate (5a)
Colorless oil, yield 50%, IR (neat) (mmax, cmꢁ1): 2954 (CH, alipha); 1727
(C ¼ O, ester); 1612 (C ¼ C, alkene). Anal. calcd for C17H26O6 (326): C,
62.56; H, 8.03. Found: C, 62.52; H, 8.00%.1H NMR (CDCl3) dH: 1.15
(18H, 1s, 6CH3 of 2 t-Bu); 3.8 and 3.82 (6H, 2s, 2OCH3); 6.67 (1H,
1s, ¼ CH); 6.80 (1H, 1s, CH).13C NMR (CDCl3) dC: 26.75 (6CH3 of
2 t-Bu); 45.86 (2C of 2 t-Bu); 52.15 and 52.9 (2 OCH3); 55.35 and
124.70 (2CH); 130.86 (1C), 165.79 and 166.84 (2 C ¼ O of ester);
210.58 (C ¼ O of ketone).
Dimethyl-(Z)-2-[1-(2,2-dimethylpropanoyl)-3,3-dimethyl-2-oxobutyl]-2-
butenedioate (5a)
Colorless oil, yield 45%, IR (neat) (lmax, cmꢁ1): 2954 (CH, alipha); 1727
(C ¼ O, ester); 1612 (C ¼ C, alkene); 1240 (C-O, ether). Anal. Calcd. for
C17H26O6 (326): C, 62.56; H, 8.03. Found: C, 62.52; H, 8.00%. 1H NMR
(CDCl3) dH: 1.17 (18H, 1s, 6CH3 of 2 t-Bu); 3.74 and 3.79 (6H, 2s, 2CH3
of 2 OMe); 5.55 (1H, 1s, ¼ CH); 6.10 (1H, 1s, CH). 13C NMR (CDCl3)
dC: 27.06 (6 CH3 of 2 t-Bu); 45.35 (2C of 2 t-Bu); 52.11 and 52.77
(2OCH3); 55.95 and 129.54 (2CH); 134.51 (C); 165.44 and 166.69 (2
C ¼ O of ester); 205.17 (C ¼ O of ketone).

1210
A. Ramazani and N. Noshiranzadeh
Diethyl (E)-2-[1-(2,2-Dimethylpropanoyl)-3,3-dimethyl-2-oxobutyl]-2-
butenedioate (5b)
Colorless oil, yield 55%. IR (neat) (nmax, cmꢁ1): 2950 (CH, alipha); 1727
(C¼ O, ester); 1612 (C¼ C, alkene); 1240 (C-O, ether). Anal. calcd. for
1
C19H30O6 (354): C, 64.38; H, 8.53. Found: C, 64.35; H, 8.49%. H NMR
3
(CDCl3)dH: 1.12 (18H, 1s, 6CH3 of 2 t-Bu); 1.27 (6H, t, JHH ¼ 7.25Hz,
3
2CH3 of 2OEt); 4.22 and 4.25 (4H, 2q, JHH ¼ 7.25Hz, 2OCH2 of 2OEt);
6.63 (1H, 1s, ¼ CH); 6.79 (1H, 1s, CH). 13C NMR (CDCl3) dC: 13.89 and
14.05 (2CH3 of 2OEt); 26.73 (6CH3 of 2 t-Bu); 45.77 (2C of 2 t-Bu); 61.16
and 62.06 (2 OCH2 of 2OEt); 55.24 and 124.93 (2CH); 130.84 (1C),
165.38 and 166.34 (2 C ¼ O of ester); 210.41 (2C ¼ O of ketone).
Diethyl (Z)-2-[1-(2,2-Dimethylpropanoyl)-3,3-dimethyl-2-oxobutyl]-2-
butenedioate (5b)
Colorless oil, yield 40%. IR (neat) (nmax, cmꢁ1): 2961 (CH, alipha.); 1727
(C ¼ O, carbonyl); 1240 (C-O, ether). Anal. calcd. for C19H30O6 (354): C,
1
64.38; H, 8.53. Found: C, 64.35; H, 8.49%. H NMR (CDCl3) dH: 1.17
(18H, 1s, 6CH3 of 2 t-Bu); 1.27 (6H, t,3JHH ¼ 7.25 Hz, 2CH3 of 2OEt);
3
4.19 and 4.24 (4H, 2q, JHH ¼ 7.25 Hz, 2OCH2 of 2OEt); 5.57 (1H,
1s, ¼ CH); 6.09 (1H, 1s, CH). 13C NMR (CDCl3) dC: 13.83 and 14.01
(2CH3 of 2OEt); 27.08 (6CH3 of 2 t-Bu); 45.32 (2C of 2 t-Bu); 61.11
and 61.94 (2 OCH2 of 2OEt); 55.35 and 130.01 (2CH); 133.89 (1C),
165.06 and 166.18 (2 C ¼ O of ester); 205.29 (2C ¼ O of ketone).
5-Ethyl-4-methyl-6-methyl-2-oxo-2H-pyran-4,5-dicarboxylate (7a)
Yellow oil, yield 80%. IR (neat) (nmax, cmꢁ1): 2961 (CH, alipha); 1727 (C ¼ O,
carbonyl); 1688 (C ¼ C, alkene); 1263 (C-O of ether). Anal. calcd. for
1
C11H12O6 (240): C, 55.00; H, 5.04. Found: C, 54.97; H, 4.95%. H NMR
(CDCl3) dH: 1.32 (3H, t, 3JHH ¼ 7.25 Hz, CH3 of OEt); 2.49 (3H, 1s, CH3);
3
3.88 (3H, 1s, CH3 of OCH3), 4.3 (2H, 1q, JHH ¼ 7.25 Hz, CH2 of OEt);
6.46 (1H, 1s, ¼ CH).13C NMR (CDCl3) dC: 13.94 (CH3 of OEt); 19.36
(CH3); 53.16 (OCH3); 62.07 (OCH2 of OEt), 113.65 (CH); 109.32, 145.94
and 159.74 (3C); 164.18, 164.67 and 166.94 (3 C ¼ O of ester or lactone).
Methyl-5-benzoyl-6-methyl-2-oxo-2H-pyran-4-carboxylate (7b)
Yellow oil, yield 80%. IR (neat) (vmax, cmꢁ1): 2961 (CH, alipha); 1757
(C ¼ O, carbonyl); 1688 (C ¼ C, alkene); 1263 (C-O of ether). Anal.

Electron-Poor Alkenes and Pyranes
1211
Calcd. for C15H12O5 (272): C, 66.17; H, 4.44. Found: C, 66.14; H, 4.40%.
1H NMR (CDCl3) dH: 2.19 (3H,1s, CH3); 3.62 (3H, 1s, OCH3); 6.78(1H,
1s, HC ¼ ); 7.47–7.84 (4H, m, arom).13C NMR (CDCl3) dC: 18.62 (CH3);
53.18 (OCH3); 144.77 (HC ¼ ); 115.30, 115.57, and 160.50 (3C); 128.89,
129.08, 133.98 and 136.69 (4CH, arom); 162.80 and 163.58 (2C ¼ O of
ester); 192.31 (C ¼ O of keton).
Ethyl-5-benzoyl-6-ethyl-2-oxo-2H-pyran-4-carboxylate (7c)
Yellow oil, yield 80%. IR (neat) (vmax, cmꢁ1 ): 2961 (CH, alipha); 1757
(C ¼ O, carbonyl); 1688 (C ¼ C, alkene); 1263 (C-O of ether). Anal.
Calcd. for C16H14O5 (286): C, 67.13; H, 4.93. Found: C, 67.10; H,
3
4.90%. 1H NMR (CDCl3) dH: 1.06 (3H, 1 t, JHH ¼ 7.25 Hz, CH3 of
3
OEt); 2.19 (3H, 1s, CH3); 4.06 (2H, 1q, JHH ¼ 7.25 Hz, CH2 of OEt);
6.79 (1H, 1s, ¼ CH); 6.92–7.88 (5H, m arom). 13C NMR (CDCl3) dC:
13.46 (CH3 of Et); 18.84 (CH3); 62.79 (CH2 of Et); 115.81 (CH);
115.42, 145.15, 160.65 (3C); 128.99, 129.04, 133.98, 137.01 (4CH, arom);
162.64, 163.06 (2C ¼ O of ester); 192.29 (C ¼ O of ketone).
Ethyl-5-benzoyl-2-oxo-6-phenyl-2H-pyran-4-carboxylate (9b)
Brown oil; yield 34%. Anal. Calcd. for C21H16O5 (348): C, 72.41; H, 4.63.
Found: C, 71.38; H, 4.60%. 1H NMR (CDCl3) dH: 1.12 (3H, t,
3JHH ¼ 7.25Hz, CH3 of OEt); 4.18 (2H, q, 3JHH ¼ 7.25Hz, OCH2 of OEt);
7.27 (1H, 1s, ¼ CH); 7.28–8.16 (10H, m, arom). 13C NMR (CDCl3) dC:
13.55 (CH3 of OEt); 62.84 (OCH2 of OEt); 116.00, 128.52, 128.65, 128.69,
129.11, 131.25, 133.68, and 134.67 (11CH); 131.01, 136.80, 145.20, and
160.20 (4C); 161.20 and 163.50 (2C ¼ O of ester); 193.00 (C¼ O of keton).
Dimethyl (Z)-2-[(E)-1-Benzoyl-2-hydroxy-2-phenyl-1-ethyenyl]-2-
butenedioate (10a)
Brown oil; yield 80%, IR (neat) (nmax, cmꢁ1): 3350 (OH, alcohol); 3035
(CH, arom); 2954 (CH, alipha); 1727 (C ¼ O, ester); 1612 (C ¼ C, alkene),
1H NMR (CDCl3) dH: 3.54 and 3.66 (6H, 2s, 2OCH3); 5.28 (1H,
1s, ¼ CH); 7.43–8.14 (10H, m, arom); 17.20 (1H, 1s, OH).
Dimethyl 2-(1-Benzoyl-2-oxo-2-phenylethylidene)succinate (11a)
Green oil; yield 80%; IR (neat) (nmax, cmꢁ1): 3035 (CH, arom); 2954 (CH,
alipha); 1727 (C ¼ O, ester); 1710 (C ¼ O, keton); 1612 (C ¼ C, alkene).

1212
A. Ramazani and N. Noshiranzadeh
Anal. calcd. for C21H18O6 (366): C, 68.85; H, 4.95. Found: C, 68.80; H,
1
4.92%. H NMR (CDCl3) dH: 3.35 (2H, 1s, CH2); 3.52 and 3.64 (6H, 2s,
2OCH3); 7.43–8.14 (10H, m, arom). 13C NMR (CDCl3) dC: 34.79 (CH2);
52.01 and 52.24 (2OCH3); 128.54, 128.75, 129.54, 130.54, 133.57, and
134.62 (10CH); 134.95, 135.79, 145.20, and 152.44 (4C); 165.24 and
169.46 (2C ¼ O of ester); 191.38 and 192.03 (2C ¼ O of keton).
Diethyl (Z)-2-[(E)-1-Benzoyl-2-hydroxy-2-phenyl-1-ethyenyl]-2-
butenedioate (11a)
Brown oil; yield 66%. IR (neat) (nmax, cmꢁ1): 3350 (OH, alcohol); 3035
(CH, arom); 2954 (CH, alipha); 1727 (C ¼ O, ester); 1612 (C ¼ C, alke-
3
ne).1H NMR (CDCl3) dH: 0.97 and 1.24 (6H, 2 t, JHH ¼ 7.25 Hz, 2CH3
3
of 2OEt); 4.03 and 4.14 (4H, 2q, JHH ¼ 7.25 Hz, 2OCH2 of 2OEt);
6.87 (1H, 1s, ¼ CH); 7.28–8.16 (10H, m, arom); 17.05 (1H, 1s, OH).
Diethy2-(1-benzoyl-2-oxo-2-phenylethylidene)succinate (11b)
Green oil; yield 66%. IR (neat) (nmax, cmꢁ1): 3035 (CH, arom); 2954 (CH,
alipha); 1727 (C ¼ O, ester); 1710 (C ¼ O, keton); 1612 (C ¼ C, alkene).
Anal. Calcd. for C23H22O6 (394): C, 70.04; H, 5.62. Found: C, 70.01;
1
3
H, 5.59%. H NMR (CDCl3) dH: 0.97 and 1.24 (6H, 2 t, JHH ¼ 7.25 Hz,
Hz, 2CH3 of 2OEt); 3.32 (2H, 1s, CH2); 4.03 and 4.14 (4H, 2q,
3JHH ¼ 7.25 Hz, 2OCH2 of 2OEt); 7.26–8.16(10H, m, arom). 13C NMR
(CDCl3) dC: 13.35 and 14.07 (2CH3 of 2OEt); 34.14(CH2); 61.88 and
62.05 (2OCH2 of 2OEt); 128.66, 128.87, 129.78, 130.71, 133.81,
and 134.87 (10CH); 135.55, 136.80, 145.20, and 152.09 (4C); 164.79
and 169.24 (2C ¼ O of ester); 191.30 and 192.03 (2C ¼ O of keton).
ACKNOWLEDGMENTS
This work was supported by Zanjan University.
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