Stereoselective reaction between alkyl propiolates and phenols in the presence of sodium azide in tert-butyl alcohol

Article abstract of DOI:10.1007/s00706-011-0514-6

Stereoselective reaction of various substituted phenols with alkyl propiolates in the presence of a catalytic amount of sodium azide in tert-butyl alcohol at reflux temperature leads to alkyl (Z)-3-phenoxy-2-propenoates in good yields. Springer-Verlag 201

Full text of DOI:10.1007/s00706-011-0514-6

Monatsh Chem (2011) 142:807–812
DOI 10.1007/s00706-011-0514-6
ORIGINAL PAPER
Stereoselective reaction between alkyl propiolates and phenols
in the presence of sodium azide in tert-butyl alcohol
•
Farough Nasiri Davood Malakutikhah
Received: 10 September 2009 / Accepted: 26 April 2011 / Published online: 31 May 2011
Ó Springer-Verlag 2011
Abstract Stereoselective reaction of various substituted
phenols with alkyl propiolates in the presence of a catalytic
amount of sodium azide in tert-butyl alcohol at reflux
temperature leads to alkyl (Z)-3-phenoxy-2-propenoates in
good yields.
the presence of a catalytic amount of 1,4-diazabicy-
clo[2.2.2]octane (DABCO) to produce O-vinylated products.
On the other hand, Ramachandran et al. [19] found that
alkyl propiolates couple with themselves in the presence of
a catalytic amount of DABCO to provide a quantitative
yield of (E)-hex-2-en-4-ynedioates. Accordingly, the
reaction between phenols and alkyl propiolates in the
presence of tertiary amines is limited to simple phenols
[18]. As a part of our current studies on the development of
new routes to stereoselective additions of phenols to
acetylenic esters [20], we now report the stereoselective
reaction between alkyl propiolates and various substituted
phenols in the presence of a catalytic amount of sodium
azide.
Keywords Activated alkynes Á Alkyl propiolates Á
OH-acids Á Phenols Á Stereoselective addition
Introduction
There are many studies on the reactions between OH-acids
and acetylenic esters in the presence of various nucleo-
philic catalysts such as triphenylphosphine [1–5],
trialkylphosphites [6], alkyl isocyanides [7–9], and tertiary
amines [10, 11]. In most cases, the reaction was viewed as
starting from the initial formation of a zwitterionic inter-
mediate derived from the addition of a nucleophilic catalyst
to an activated alkyne [1–11]. The azide anion usually
reacts as a nucleophile in nucleophilic substitution reac-
tions [12, 13] or reacts as a 1,3-dipole in 1,3-dipolar
cycloaddition reactions [14–16]; however, to the best of
our knowledge, there is not any report about the catalytic
behavior of azide anions in the above reactions. Phenols
react with alkyl propiolates to give a mixture of E and
Z isomers, arising through a cis or trans mode of addition
[17, 18]. In the above studies the E isomer is usually the
major product. Recently, Liang and co-workers found
[18] that phenols react smoothly with alkyl propiolates in
Results and discussion
The reaction of alkyl propiolates 1 and substituted phenols
2 in the presence of a catalytic amount of sodium azide in
tert-butyl alcohol at reflux temperature leads to alkyl (Z)-3-
phenoxy-2-propanoates 3 in good to high yields (Scheme 1
and Table 1).
The structures of the products were determined on the
1
basis of their elemental analysis, mass spectrometry, H
NMR, 13C NMR, and IR data. The ratio of E/Z isomers was
determined by 1H NMR spectroscopy. The 1H NMR spectral
data of the crude products exhibited two isomers and both of
them displayed characteristic resonance patterns with
1
appropriate chemical shift. The H NMR spectra of E iso-
mers displayed two doublets with 3JHH = 12.3–12.5 Hz for
the two olefinic protons, whereas the signals of the Z forms
F. Nasiri (&) Á D. Malakutikhah
3
appeared with JHH = 6.7–7.0 Hz; this was in agreement
Department of Chemistry, Faculty of Sciences,
University of Kurdistan, P.O. Box 66315-416, Sanandaj, Iran
e-mail: fnasiri@uok.ac.ir; farough_na@yahoo.com
with the proposed E and Z isomers, respectively. For
example, the 1H NMR spectrum of 3a showed one singlet at
123

808
F. Nasiri, D. Malakutikhah
CO2R
summarized in Table 2. DABCO, triphenylphosphine,
and sodium azide in CH2Cl2, as Table 2 shows, were
particularly effective in producing E isomers. The stereo-
selectivity/conversion of this reaction was influenced by
the nature of the solvent. When the reaction of
2-methoxyphenol and methyl propiolate was carried out in
THF/H2O, the syn addition was dominant; however, the
yield of the reaction was low (entry 21). When this reaction
was carried out in acetonitrile, a polar aprotic solvent, the
stereoselectivity was inversed (entry 23). These results
show that the protic solvent can prompt syn addition of
phenols to alkyl propiolates. In methanol, the reaction
afforded a complex mixture of products as a result of the
high nucleophilicity of methanol (entry 22). Thus tert-butyl
alcohol, a protic solvent with weak nucleophilicity, could
lead to stereoselective syn addition of phenols to alkyl
propiolates (Table 2).
ArO
H
NaN3 (10 mol%), tert-BuOH
ArOH
+
Reflux, 5 h
RO2C
1
2
3 (Z)-isomer: 67-81%
Scheme 1
3.75 ppm for the methoxy group and two doublets with
3JHH = 7.0 Hz at 5.17 and 6.85 ppm for the olefinic protons
in the Z isomer and one singlet at 3.73 ppm for the methoxy
3
group and two doublets with JHH = 12.3 Hz at 5.56 and
7.81 ppm for the olefinic protons in the E isomer. These data
were in agreement with the values reported in the literature
[18]. Table 1 shows that this addition reaction tolerates a
wide range of functional groups on the phenol including
alkyls, alkoxyls, aldehydes, halides, and nitro groups.
Although the mechanism of the reaction between alkyl
propiolates and phenols in the presence of sodium azide is
unknown, a proposed mechanism for this reaction is out-
lined in Scheme 2 based on the previous reports [1–11].
Initially, the azide anion reacts with the electron-deficient
acetylenic esters to generate the conjugate ionic systems 4,
which deprotonate the OH-acid to give the corresponding
intermediates 5 and 6. Subsequent Michael addition of 6 to
5 forms the intermediates 7, which then eliminates azide
anion to afford the desired product (Scheme 2).
In conclusion, we have described a convenient route to
alkyl (Z)-3-phenoxy-2-propenoates through nucleophilic
syn addition of phenols to alkyl propiolates in tert-butyl
alcohol. In this procedure the catalyst can be removed by
filtration. The simplicity of this procedure makes it an
interesting alternative to other approaches.
Experimental
Further comparative studies demonstrate that sodium
azide in tert-butyl alcohol at reflux temperature was the
optimal catalyst for the stereoselective syn addition of
phenols to alkyl propiolates. Results of these studies are
Alkyl propiolates and phenols were obtained from Fluka
(Buchs, Switzerland) and were used without further puri-
fication. Melting points were measured with an
Electrothermal 9100 apparatus. Elemental analyses (C, H,
Table 1 Stereoselectivity of the addition of phenols to alkyl acetylenecarboxylate in the presence of sodium azide (10 mol%) in tert-BuOH at
reflux temperature
Entry
Ar
R
Product
Yield of 3 (%)a
Isomer (%)b
E
Z
1
Phenyl
Me
Me
Me
Et
3a
3b
3c
3d
3e
3f
96
76
95
96
96
97
60
97
80
90
97
80
96
26
30
22
23
30
28
19
26
24
21
33
29
33
74
70
78
77
70
72
81
74
76
79
67
71
67
2
4-Chlorophenyl
2,4-Dichlorophenyl
2,4-Dichlorophenyl
4-Formylphenyl
2-Methoxyphenyl
4-Formyl-2-methoxyphenyl
1-Naphthyl
3
4
5
Me
Me
Me
Me
Me
Me
Me
Me
Et
6
7
3g
3h
3i
8
9
2-Naphthyl
10
11
12
13
a
2-Nitrophenyl
3j
3-Nitrophenyl
3k
3l
2,6-Dimethylphenyl
2,6-Dimethylphenyl
3m
Isolated yields
b
1
Determined by H NMR spectroscopy
123

Stereoselective reaction between alkyl propiolates and phenols
809
Scheme 2
Table 2 Stereoselectivity of the addition of phenols to alkyl propiolates to produce alkyl 3-phenoxy-2-propanoates in the presence of different
catalysts and reaction conditions
Entry
Ar
R
Product
Catalyst
Solvent
Yield of 3 (%)a
E/Z [Ref.]
1
Phenyl
Me
Me
Me
Me
t-Bu
t-Bu
t-Bu
t-Bu
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
3a
3h
3i
DABCO
DABCO
DABCO
DABCO
Ph3P
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
H2O/THF
CH3OH
CH3CN
95
85:15 [18]
95:5 [18]
E [18]
2
1-Naphthyl
97
3
2-Naphthyl
90
b
–
c
4
2-Nitrophenyl
Phenyl
–
–
5
3n
3o
3p
3q
3r
3a
90
E [17]
E [17]
E [17]
E [17]
E [18]
99:1 [18]
6
1-Naphthyl
Ph3P
45
7
2-Naphthyl
Ph3P
55
8
4-Formyl-2-methoxyphenyl
8-Quinolyl
Ph3P
95
9
Ph3P
85
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Phenyl
Et3N
73
b
–
c
Phenyl
Me3N
Me3N
Me3N
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
NaN3
–
–
b
–
c
2-Nitrophenyl
4-Formylphenyl
2-Methoxyphenyl
2,6-Dimethylphenyl
1-Naphthyl
–
–
3e
3f
3l
3h
3i
–
75
Ec
66
74:26c
82:18c
84:16c
86:14c
50
45
2-Naphthyl
36
c
3-Nitrophenyl
4-Nitrophenyl
4-Formylphenyl
2-Methoxyphenyl
2-Methoxyphenyl
2-Methoxyphenyl
No reaction
No reaction
No reaction
55
–
c
–
–
c
–
–
3f
3f
3f
12:88c
d
c
–
–
55
85:15c
All reactions were carried out at room temperature
a
Isolated yields
b
Quantitative self-coupling of alkyl propiolate occurs
c
Considered in this research
d
The reaction afforded a complex mixture
1
and N) were performed using a Heraeus CHN-O-Rapid
analyzer. The results agreed favorably with the calculated
values. IR spectra were measured with a Shimadzu IR-460
spectrometer. NMR spectra were recorded with a Bruker
DRX-250 AVANCE instrument (250.1 MHz for H and
62.9 MHz for 13C) with CDCl3 as solvent. Chemical shifts
(d) are given in ppm relative to internal TMS, and coupling
constants (J) are reported in hertz (Hz). Mass spectra were
123

810
F. Nasiri, D. Malakutikhah
and 130.7 (2CH), 131.2 (C), 149.9 (O–Cipso), 158.6
(O–CH), 167.0 (C=O) ppm.
recorded with a Finnigan-Matt 8430 mass spectrometer
operating at an ionization potential of 70 eV.
Ethyl 3-(2,4-dichlorophenoxy)-2-propenoate
(3d, C11H10Cl2O3)
Typical procedure for preparation of methyl
3-phenoxy-2-propenoate (3a)
-1
ꢀ
Brown oil; IR (KBr): m = 1,710 (C=O), 1,645 (C=C) cm
.
Major isomer (Z)-3d: 77%; 1H NMR (250.1 MHz,
To a stirred solution of 0.02 g of NaN3 (10 mol%) and
0.29 g of phenol (3 mmol) in 10 cm3 of tert-butyl alcohol
was added dropwise a mixture of 0.26 g of methyl propi-
olate (3 mmol) in 2 cm3 of tert-butyl alcohol at room
temperature over 10 min. The reaction mixture was then
refluxed for 5 h. Sodium azide was separated by filtration,
the solvent was removed under reduced pressure, and the
residue was separated by silica gel column chromatography
(Merck 230–400 mesh) using n-hexane–EtOAc as eluent to
give 3a. Compounds 3a, 3 h, and 3i are known compounds
[18].
3
CDCl3): d = 1.29 (t, JHH = 7.0 Hz, OCH2CH3), 4.20 (q,
3
3JHH = 7.0 Hz, OCH2CH3), 5.21 (d, JHH = 6.8 Hz,
3
O–C=CH), 6.68 (d, JHH = 6.8 Hz, O–CH), 6.94–7.44
(m, 3CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 14.3
(OCH2CH3), 60.2 (OCH2CH3), 101.5 (O–C=CH), 119.7
(CH), 125.8 (C), 128.1 (CH), 130.4 (C), 130.5 (CH), 151.6
(O–Cipso), 153.1 (O–C=CH), 164.3 (C=O) ppm.
Minor isomer (E)-3d: 23%; 1H NMR (250.1 MHz,
3
CDCl3): d = 1.23 (t, JHH = 7.0 Hz, OCH2CH3), 4.16 (q,
3
3JHH = 7.0 Hz, OCH2CH3), 5.43 (d, JHH = 12.3 Hz,
3
O–C=CH), 6.93–7.44 (m, 3CH), 7.65 (d, JHH = 12.3 Hz,
O–CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 14.3
(OCH2CH3), 60.3 (OCH2CH3), 102.8 (O–C=CH), 121.1
(CH), 126.2 (C), 128.3 and 130.6 (2CH), 131.1 (C), 149.8
(O–Cipso), 158.6 (O–CH), 166.7 (C=O) ppm.
Methyl 3-(4-chlorophenoxy)-2-propenoate
(3b, C10H9ClO3)
ꢀ
Brown oil; IR (KBr): m = 1,713 (C=O), 1,646 and 1,585
(C=C) cm-1
.
Major isomer (Z)-3b: 70%; 1H NMR (250.1 MHz,
Methyl 3-(4-formylphenoxy)-2-propenoate
(3e, C11H10O4)
3
CDCl3): d = 3.75 (s, OCH3), 5.20 (d, JHH = 7.0 Hz,
O–C=CH), 6.79 (d, JHH = 7.0 Hz, CH), 6.98 and 7.32
3
ꢀ
Brown oil; IR (KBr): m = 1,714 and 1,713 (C=O), 1,649
3
(2d, JHH = 9.0 Hz, 4CH) ppm; 13C NMR (62.9 MHz,
(C=C) cm-1
.
CDCl3): d = 51.2 (OCH3), 100.2 (O–C=CH), 119.0 and
129.8 (4CH), 130.3 and 153.5 (2C), 157.2 (O–CH), 166.3
(C=O) ppm.
Major isomer (Z)-3e: 70%; 1H NMR (250.1 MHz,
3
CDCl3): d = 3.72 (s, OCH3), 5.28 (d, JHH = 7.3 Hz,
O–C=CH), 6.92 (d, JHH = 7.3 Hz, O–CH), 7.21 and 7.88
(2d, JHH = 8.5 Hz, 4CH), 9.92 (s, CHO) ppm; 13C NMR
3
Minor isomer (E)-3b: 30%; 1H NMR (250.1 MHz,
3
3
CDCl3): d = 3.73 (s, OCH3), 5.56 (d, JHH = 12.3 Hz,
O–C=CH), 6.98 and 7.32 (2d, JHH = 9.0 Hz, 4CH), 7.74
(62.9 MHz, CDCl3): d = 51.3 (OCH3), 101.9 (O–C=CH),
117.6 and 131.9 (4CH), 132.8 (C), 151.7 (O–CH), 160.9
(O–Cipso), 164.6 (C=O), 190.6 (CHO) ppm.
3
3
(d, JHH = 12.3 Hz, O–CH) ppm; 13C NMR (62.9 MHz,
CDCl3): d = 51.4 (OCH3), 102.4 (O–C=CH), 119.3 and
130.0 (4CH), 130.2 and 154.3 (2C-Ar), 158.5 (O–C=CH),
167.3 (C=O) ppm.
Minor isomer (E)-3e: 30%; 1H NMR (250.1 MHz,
3
CDCl3): d = 3.72 (s, OCH3), 5.70 (d, JHH = 12.3 Hz,
O–C=CH), 7.18 (d, JHH = 8.5 Hz, 2CH), 7.80 (d,
3
3
3JHH = 12.3 Hz, O–CH), 7.89 (d, JHH = 8.5 Hz, 2CH),
Methyl 3-(2,4-dichlorophenoxy)-2-propenoate
(3c, C10H8Cl2O3)
9.92 (s, CHO) ppm; 13C NMR (62.9 MHz, CDCl3):
d = 51.5 (OCH3), 104.1 (O–C=CH), 117.7 and 132.0
(4CH), 132.9 (C), 156.6 (O–CH), 160.1 (O–Cipso), 167.1
(C=O, ester), 190.6 (CHO) ppm.
ꢀ
Brown oil; IR (KBr): m = 1,713 (C=O), 1,647 and 1,575
(C=C) cm-1
.
Major isomer (Z)-3c: 78%; 1H NMR (250.1 MHz,
3
CDCl3): d = 3.74 (s, OCH3), 5.22 (d, JHH = 7.0 Hz,
O–C=CH), 6.68 (d, 3JHH = 7.0 Hz, O–CH), 7.03–7.44 (m,
3CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 51.3
(OCH3), 101.0 (O–C=CH), 120.0 (CH), 125.9 (C), 128.1
and 130.6 (2CH), 131.1 (C), 151.6 (O–Cipso), 153.9
(O–CH), 166.4 (C=O) ppm.
Methyl 3-(2-methoxyphenoxy)-2-propenoate
(3f, C11H12O4)
Orange oil; IR (KBr): ꢀm = 1,712 (C=O), 1,644 (C=C) cm-1
.
Major isomer (Z)-3f: 72%; 1H NMR (250.1 MHz,
CDCl3): d = 3.73 and 3.84 (2 s, 2OCH3), 5.08 (d,
Minor isomer (E)-3c: 22%; 1H NMR (250.1 MHz,
3JHH = 7.5 Hz, O–C=CH), 6.73 (d, JHH = 7.5 Hz,
3
3
CDCl3): d = 3.71 (s, OCH3), 5.45 (d, JHH = 12.3 Hz,
O–C=CH), 7.03–7.44 (m, 3CH), 7.65 (d, JHH = 12.3 Hz,
O–CH), 6.78–7.26 (m, 4CH) ppm; 13C NMR (62.9 MHz,
CDCl3): d = 51.1 and 56.1 (2OCH3), 98.3 (O–C=CH),
113.1, 119.8, 120.9, and 125.9 (4CH), 146.3 and 150.3
(2C), 156.6 (O–CH), 165.3 (C=O) ppm.
3
O–CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 51.5
(OCH3), 102.5 (O–C=CH), 121.1 (CH), 126.2 (C), 128.3
123

Stereoselective reaction between alkyl propiolates and phenols
811
3
Minor isomer (E)-3f: 28%; 1H NMR (250.1 MHz,
CDCl3): d = 3.69 and 3.85 (2 s, 2OCH3), 5.41 (d,
3JHH = 12.3 Hz, O–C=CH), 6.78–7.26 (m, 4CH), 7.71
O–C=CH), 6.89 (d, JHH = 6.8 Hz, O–CH), 7.26–8.07
(4CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 51.4
(OCH3), 102.2 (O–C=CH), 112.4, 119.4, 123.9, and 130.7
(4CH), 149.2 and 151.9 (2C), 156.1 (O–CH), 166.9 (C=O)
ppm.
3
(d, JHH = 12.3, Hz, O–CH) ppm; 13C NMR (62.9 MHz,
CDCl3): d = 51.2 and 55.9 (2OCH3), 100.5 (O–C=CH),
112.8, 120.4, 121.0, and 126.3 (4CH), 144.2 and 150.4
(2C), 161.0 (O–CH), 167.7 (C=O) ppm.
Minor isomer (E)-3k: 33%; 1H NMR (250.1 MHz,
3
CDCl3): d = 3.75 (s, OCH3), 5.69 (d, JHH = 12.3 Hz,
O–C=CH), 7.26-8.07 (4CH), 7.79 (d, JHH = 12.3 Hz,
O–CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 51.6
(OCH3), 104.1 (O–C=CH), 112.9, 119.7, 124.0, and 130.8
(4CH),149.2 and 151.9 (2C), 157.0 (O–CH), 166.9 (C=O)
ppm.
3
Methyl 3-(4-formyl-2-methoxyphenoxy)-2-propenoate
(3g, C12H12O5)
ꢀ
Yellow oil; IR (KBr): m = 1,713 and 1,686 (C=O), 1,649
(C=C) cm-1
.
Major isomer (Z)-3g: 81%; 1H NMR (250.1 MHz,
CDCl3): d = 3.73 and 3.91 (2 s, 2OCH3), 5.21 (d,
Methyl 3-(2,6-dimethylphenoxy)-2-propenoate
(3l, C12H14O3)
3
3JHH = 6.8 Hz, O–C=CH), 6.79 (d, JHH = 6.8 Hz,
3
-1
O–CH), 7.18 and 7.42 (2d, JHH = 7.5 Hz, 2CH), 7.45 (s,
ꢀ
Brown oil; IR (KBr): m = 1,712 (C=O), 1,644 (C=C) cm
.
CH), 9.82 (CHO) ppm; 13C NMR (62.9 MHz, CDCl3):
d = 51.3 and 56.3 (2OCH3), 100.5 (O–C=CH), 111.3, 118.9,
and 125.1 (3CH–Ar), 133.9 (C), 153.9 and 154.9 (2 O–Cipso),
158.6 (O–CH), 164.8 (C=O, ester), 190.7 (CHO) ppm.
Minor isomer (E)-3g: 19%; 1H NMR (250.1 MHz,
Major isomer (Z)-3l: 71%; 1H NMR (250.1 MHz,
3
CDCl3): d = 2.25 (s, 2CH3), 5.05 (d, JHH = 7.0 Hz,
O–C=CH), 6.48 (d, 3JHH = 7.0 Hz, O–CH), 7.03–7.08 (m,
3CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 16.1
(2CH3), 51.1 (OCH3), 97.5 (O–C=CH), 125.7 and 128.9
(3CH), 130.0 (2C), 157.5 (O–CH), 160.7 (O–Cipso), 165.3
(C=O) ppm.
CDCl3): d = 3.70 and 3.91 (2 s, 2OCH3), 5.62 (d,
3
3JHH = 12.3 Hz, O–C=CH), 7.18 and 7.42 (2d, JHH
=
3
Minor isomer (E)-3l: 29%; 1H NMR (250.1 MHz,
7.5 Hz, 2CH), 7.45 (s, CH), 7.72 (d, JHH = 12.3, Hz,
O–CH), 9.91 (CHO) ppm; 13C NMR (62.9 MHz, CDCl3):
d = 51.2 and 56.2 (2OCH3), 102.7 (O–C=CH), 111.1,
119.3, and 125.2 (3CH), 134.2 (C), 149.4 and 150.9
(2O–Cipso), 158.7 (O–CH), 167.2 (C=O, ester), 190.7
(CHO) ppm.
3
CDCl3): d = 2.17 (s, 2CH3), 5.01 (d, JHH = 12.5 Hz,
O–C=CH), 7.03–7.08 (3CH), 7.75 (d, JHH = 12.5 Hz,
O–CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 16.0
(2CH3), 51.2 (OCH3), 98.4 (O–C=CH), 125.9 and 129.1
(3CH), 129.8 (2C), 154.6 (O–CH), 161.5 (O–Cipso), 165.4
(C=O) ppm.
3
Methyl 3-(2-nitrophenoxy)-2-propenoate (3j, C10H9NO5)
ꢀ
-1
Brown oil; IR (KBr): m = 1,718 (C=O), 1,650 (C=C) cm
.
Major isomer (Z)-3j: 79%; 1H NMR (250.1 MHz,
Ethyl 3-(2,6-dimethylphenoxy)-2-propenoate
(3m, C13H16O3)
3
CDCl3): d = 3.75 (s, OCH3), 5.31 (d, JHH = 6.8 Hz, O–
-1
C=CH), 6.77 (d, 3JHH = 6.8 Hz, O–CH), 7.22–7.98 (4CH)
ppm; 13C NMR (62.9 MHz, CDCl3): d = 51.4 (OCH3),
102.4 (O–C=CH), 120.2, 125.1, 125.8, and 134.5 (4CH),
141.0 (C–Ar), 152.2 (O–CH), 157.9 (O–Cipso), 164.4
(C=O) ppm.
ꢀ
Brown oil; IR (KBr): m = 1,712 (C=O), 1,644 (C=C) cm
.
Major isomer (Z)-3m: 67%; 1H NMR (250.1 MHz,
3
CDCl3): d = 1.34 (t, JHH = 7.0 Hz, OCH2CH3), 2.26
(6H, s, 2CH3), 4.22 (q, JHH = 7.0 Hz, OCH2CH3), 5.03
3
3
3
(d, JHH = 6.8 Hz, O–C=CH), 6.47 (d, JHH = 6.8 Hz,
O–CH), 7.03–7.08 (3CH) ppm; 13C NMR (62.9 MHz,
CDCl3): d = 14.4 (OCH2CH3), 16.1 (2CH3), 59.7
(OCH2CH3), 97.9 (O–C=CH), 125.6 and 128.9 (3CH),
130.0 (2C–Ar), 157.3 (O–CH), 160.6 (O–Cipso), 164.9
(C=O) ppm.
Minor isomer (E)-3j: 21%; 1H NMR (250.1 MHz,
CDCl3): d = 3.73 (3H, s, OCH3), 5.58 (d, 3JHH = 12.3 Hz,
3
O–C=CH), 7.22–7.98 (4CH), 7.72 (d, JHH = 12.3 Hz,
O–CH) ppm; 13C NMR (62.9 MHz, CDCl3): d = 51.5
(OCH3), 103.9 (O–C=CH), 121.0, 125.6, 125.9, and 134.6
(4CH), 141.1 (C–Ar), 149.7 (O–CH), 155.1 (O–Cipso),
164.4 (C=O) ppm.
Minor isomer (E)-3m: 33%; 1H NMR (250.1 MHz,
3
CDCl3): d = 1.25 (t, JHH = 7.0 Hz, OCH2CH3), 2.17 (s,
2CH3), 4.14 (q, JHH = 7.0 Hz, OCH2CH3), 5.00 (d,
3
3JHH = 12.5 Hz, O–C=CH), 7.03–7.08 (3CH), 7.75 (1H,
Methyl 3-(3-nitrophenoxy)-2-propenoate
(3k, C10H9NO5)
d, JHH = 12.5 Hz, O–CH) ppm; 13C NMR (62.9 MHz,
3
CDCl3): d = 14.3 (OCH2CH3), 16.0 (2CH3), 60.0
(OCH2CH3), 98.7 (O–C=CH), 125.9 and 129.1 (3CH),
129.8 (2C), 154.7 (O–CH), 161.6 (O–Cipso), 167.5 (C=O)
ppm.
ꢀ
Pale yellow solid; m.p.: 80–81 °C; IR (KBr): m = 1,714
(C=O), 1,650 (C=C) cm-1
.
Major isomer (Z)-3k: 67%; 1H NMR (250.1 MHz,
3
CDCl3): d = 3.76 (s, OCH3), 5.33 (d, JHH = 6.8 Hz,
123

812
F. Nasiri, D. Malakutikhah
11. Stoermer MJ, Fairlie DP (1995) Aust J Chem 48:677
12. Matteson DS, Maliakal D, Fabry-Asztalos L (2008) J Organomet
Chem 693:2258
13. Tiecco M, Testaferri L, Santi C, Tomassini C, Santoro S, Marini
F, Bagnoli L, Temperini A (2007) Tetrahedron 63:12373
14. Lakshmi Kantam M, Swarna Jaya V, Sreedhar B, Mohan Rao M,
Choudary BM (2006) J Mol Cat A Chem 256:273
15. Yadav JS, Subba Reddy BV, Madhusudhan Reddy G, Narasimha
Chary D (2007) Tetrahedron Lett 48:8773
16. Chafin A, Irvin DJ, Mason MH, Mason SL (2008) Tetrahedron
Lett 49:3823
17. Yavari I, Souri S, Sirouspour M, Djahaniani H, Nasiri F (2005)
Synthesis 1761
References
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123