BF3·OEt2-mediated: Syn -selective Meyer-Schuster rearrangement of phenoxy propargyl alcohols for Z -β-aryl-α,β-unsaturated esters

Article abstract of DOI:10.1039/c6ob01090c

Synthesis of Z-β-aryl-α,β-unsaturated esters from readily available 1-aryl-3-phenoxy propargyl alcohols is achieved via a BF₃-mediated syn-selective Meyer-Schuster rearrangement under ambient conditions. The reaction mechanism is postulated to involve an electrophilic borylation of an allene intermediate as the key step to kinetically control the stereoselectivity.

Full text of DOI:10.1039/c6ob01090c

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BF3·OEt2-mediated syn-selective Meyer–Schuster
rearrangement of phenoxy propargyl alcohols for
Z-β-aryl-α,β-unsaturated esters†
Cite this: DOI: 10.1039/c6ob01090c
Surendra Puri,a Madala Hari Babua and Maddi Sridhar Reddy*a,b
Received 18th May 2016,
Accepted 21st June 2016
Synthesis of Z-β-aryl-α,β-unsaturated esters from readily available 1-aryl-3-phenoxy propargyl alcohols is
achieved via a BF3-mediated syn-selective Meyer–Schuster rearrangement under ambient conditions.
The reaction mechanism is postulated to involve an electrophilic borylation of an allene intermediate as
the key step to kinetically control the stereoselectivity.
DOI: 10.1039/c6ob01090c
www.rsc.org/obc
challenge yet to be addressed in this area of research is to
achieve the syn-selective MSR averting the advantage of
Introduction
The Meyer–Schuster rearrangement (MSR)1 has been evolved thermodynamic control for trans-products. As part of our on-
as a powerful tool for the synthesis of trans-α,β-unsaturated going program2 of uncovering the new activities of activated
carbonyls, highly potential synthetic intermediates, from alkynes, we herein report a syn-selective MSR of phenoxy pro-
readily available propargyl alcohols via activation of hydroxyl pargyl alcohols for Z-β-aryl-α,β-unsaturated esters.
and alkynyl moieties independently or cooperatively
(Scheme 1). The reaction is well tuned for the entire spectrum
of conjugated carbonyls i.e. conjugated-aldehydes,1h -ketones,1i
-esters,1j,k -amides1l and even silylketones.1m Furthermore,
halogenative,1n–q alkylative,1r allylative,1s arylative1t and
trifluoromethylative1u,v versions of the reaction are reported
for extra functionalization of the subunit in tandem. A long
list of metal complexes based on Au, Ag, Cu, Ti, Re, V, Mo, W,
and Ru are identified to execute this transformation. The only
Results and discussion
Our synthetic efforts began with the optimization studies for
the conversion of 1a2g to 2a (or 3a) as shown in Table 1. The
use of 0.5 equiv. of AlCl3 in dioxane resulted in the formation
of trans-ester 4a almost exclusively (Table 1, entry 1). The sub-
strate was found to be stable and no conversion was observed
in the presence of other Lewis acids like InCl3, ZnCl2 and
MgCl2 (entries 2–4). Pleasingly, when we opted BF3·OEt2 for
the conversion, the desired cis-ester 2a was obtained in a
reasonable ratio (2a : 4a in 71 : 29) albeit in 35% yield (entry 5).
An increase of BF3·OEt2 loading to 1 equivalent led to 55%
yield of the product with no change of the ratio (entry 6).
A further increase of the dose of the acid incurred no
change in the outcome (entry 7). The use of BF3·THF (entry 8)
instead of BF3·OEt2 was proved to be a bad choice (50% of
2a : 4a in 77 : 23). The change of the solvent to CH3CN (entry 9)
improved the ratio towards the cis-isomer (81 : 19) but still with
a moderate yield (45%). Other solvents CH2Cl2, toluene,
DMSO, DCE, DMF, DMA and THF all either produced an un-
acceptable ratio of the products or were found to be ineffective
for the intended conversion (entries 10–16). Interestingly,
EtOH as the solvent (entry 17) produced a better yield (69%)
with an acceptable ratio of 77 : 23 (Z/E respectively) but with a
concomitant trans-esterification yielding 3a3 instead of 2a.
Gratifyingly, the use of dioxane and EtOH as a 1 : 1 mixture
(entry 18) of solvents improved both the yield (76%) and the
Scheme 1 Meyer–Schuster rearrangements.
aMedicinal & Process Chemistry Division, CSIR-Central Drug Research Institute,
BS-10/1, Sector 10, Jankipuram extension, Sitapur Road, Lucknow 226031, India.
E-mail: msreddy@cdri.res.in
bAcademy of Scientific and Innovative Research, New Delhi 110001, India
†Electronic supplementary information (ESI) available. See DOI:
10.1039/c6ob01090c
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Table 1 Optimization studies
S. no.
Reagent
Equiv.
Solvent
Temp./time
Ratio of 2a : 3a : 4a : 5a
Yieldb
70%
1
2
3
4
5
6
7
8
AlCl3
InCl3
ZnCl2
MgCl2
0.5
0.5
0.5
0.5
0.5
1.0
2.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
CH3CN
CH2Cl2
Toluene
DMSO
DCE
DMF
DMA
THF
rt/3 h
rt/3 h
rt/3 h
rt/3 h
2 : 0 : 98 : 0
c
c
—
—
—
—
c
c
—
c
c
—
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·THF
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
BF3·OEt2
TMSCI
rt/3 h
71 : 0 : 29 : 0
72 : 0 : 28 : 0
72 : 0 : 28 : 0
77 : 0 : 23 : 0
81 : 0 : 19 : 0
33 : 0 : 67 : 0
50 : 0 : 50 : 0
35%
55%
50%
50%
45%
45%
40%
rt/10 min
rt/10 min
rt/1 h
rt/10 min
rt/10 min
rt/10 min
rt/6 h
rt/6 h
rt/1 h
rt/1 h
rt/1 h
rt/10 min
rt/10 min
0 °C/0.5 h
rt/0.5 h
rt/10 min
rt/10 min
rt/0.5 h
rt/6 h
rt/6 h
rt/6 h
rt/6 h
rt/6 h
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
c
c
—
—
—
c
c
—
40 : 0 : 60 : 0
50%
0%
Decomposition
c
c
—
—
Ethanol
0 : 77 : 0 : 23
0 : 85 : 0 : 15
0 : 80 : 0 : 20
0 : 73 : 0 : 27
0 : 82 : 0 : 18
0 : 80 : 0 : 20
80 : 0 : 20 : 0
69%
76%
60%
60%
58%
70%
55%
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanold
Dioxane : ethanole
Dioxane : CH3OH
Dioxane : (CH3)3COH
Dioxane : C6H5CH2OH
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanol
Dioxane : ethanol
c
c
—
—
—
—
c
c
—
Ti(iOPr)4
Bi(OTf)3
Hg(OTf)2
La(OTf)3
FeCl2
—
c
c
0 : 73 : 0 : 27
50%
c
c
—
—
—
—
c
c
rt/6 h
rt/6 h
rt/6 h
rt/6 h
rt/6 h
rt/6 h
—
c
c
—
AgOTf
0 : 84 : 0 : 16
0 : 86 : 0 : 14
0 : 50 : 0 : 50
40%
35%
40%
Yb(OTf)3
Cu(OTf)2
Zn(OTf)2
c
c
—
—
a Reaction conditions: 1 mmol of 1a in 4 mL of solvent was added to the reagent slowly at rt. b Isolated yields. c Most of the starting material was
recovered. d Double concentration. e Half concentration.
ratio of the syn adduct (85 : 15). Attempts for further improve-
ment by lowering the temperature or changing the reaction
concentrations were all unsuccessful (entries 19–21). The use
of MeOH (1 : 1 dioxane : MeOH) instead of EtOH afforded the
methyl ester of the product in a similar yield and ratio (entry
22) whereas the reaction in t-BuOH afforded the phenyl ester
(no trans-esterification) but in 55% yield (2a : 3a in 80 : 20).
The exchange of EtOH with benzyl alcohol completely
halted the reaction. Other Lewis acids than BF3·OEt2 like
TMSCl, Ti(iOPr)4, Bi(OTf)3, Hg(OTf)2, La(OTf)2, FeCl2, AgOTf,
Yb(OTf)3, Cu(OTf)2 and Zn(OTf)2 were either found to be less
productive or completely ineffective (entries 25–34). We then
verified whether we can avoid the unnecessary trans-esterifica-
tion by directly choosing the ethoxypropargyl alcohol
6
(Scheme 2). Surprisingly, no selective rearrangement occurred,
indicating that only a certain degree of electron richness
(ethoxyacetylene is electronically rich compared to phenoxyace- Scheme 2 Oxy terminal substitution effect on MSR.
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Table 2 syn-Selective MSR of phenoxypropargyl alcohols 1a
tylene) of the alkyne is key for kinetically controlled cis-selec-
tion in the product formation. Indeed, there were some reports
in the literature which used ethoxypropargyl alcohols in MSR
which often led to a trans-adduct or this kind of mixture of
isomers. Furthermore, to unveil any role of steric and elec-
tronic factors exerted by the phenyl ring on oxy terminal, we
synthesized the substrates 7 and 8 and screened them through
the standard conditions. The yield and the ratio of the isomers
were slightly varied but not in a favourable way. Synthesis of
the substrates with an electron withdrawing group (–NO2 or
–F) attached to the phenoxy end seemed to be impractical (low
yielding and non-reproducible) and hence could not be
screened.
With these observations, we decided to go for generali-
zation of syn-selective MSR with phenoxypropargyl alcohols as
substrates using one equivalent of BF3·OEt2 in the 1 : 1 di-
oxane/EtOH system. We then synthesized several 1-aryl-3-
phenoxy propargyl alcohols and subjected to the standardized
conditions (Table 2). Alkyl groups like Me, Et, iPr and tBu on
the phenyl ring were smoothly accommodated in the reaction
irrespective of their position. Thus 1a–h were converted to the
corresponding cis-products 3a–h in 70–80% yields with 82 : 18
to 96 : 4 ratios. Next, electron rich substrates with various
alkoxy groups were tested.
o-, m- and p-Methoxy precursors (1i–k) conveniently reacted
under the optimized conditions to afford the products (3i–k)
in good yields and ratios. Other alkoxy groups like ethoxy, allyl-
oxy and phenoxy groups (1l–n) were also equally tolerated in
the reaction (3l–n). Similarly, di- and tri-methoxy adducts (3o–
p) were successfully obtained in excellent yields (76–80%) and
ratios (91 : 9 to 94 : 6) from the corresponding precursors (1o–
p). Although the halo groups Br, Cl and F survived well in the
reaction, their substitution (1q–u) was found to slightly discou-
rage the reaction, thus producing the products (3q–u) in
reduced yields (62–66%) and diminished ratios (70 : 30 to
82 : 18) of cis-adducts. Similarly, a p-phenyl substituted adduct
(1v) was obtained in moderate yield but with comparably
better selectivity (85 : 15). Furthermore, 2-naphthyl precursor
1w smoothly underwent the transformation with an excellent
yield (3w, 74%) and ratio (90 : 10) whereas its 1-naphthyl
counterpart 1x suffered the declined ratio of the cis adduct
(66 : 33). This must have been due to steric constraints exerted
by closely positioned C8-hydrogen. Next, as is evident from the
conversion of 1y and 1z to 3y and 3z, respectively, alkynyl and
trimethylsilyl groups were found unaffected under the opti-
mised conditions but the alkyne group was found to be slightly
detrimental for the ratio of the cis-adduct (75 : 25 to 68 : 32).
Expanding the scope further, the heteroaryl adducts 3za–3zc
were obtained in good to excellent yields (68–80%) and ratios
(79 : 21 to 87 : 13).
a Reaction conditions: 1 mmol of 1a in 4 mL of solvent was added to
the reagent slowly at rt. b Isolated yields of the Z-product. c The ratio
was determined by 1H NMR of the crude sample. d Yield of the mixture
of Z & E isomers which were inseparable.
In the case of substrates with nitrophenyl substitution
(1zd–1zg), the course of the reaction was found to be slightly
different. Under the standard conditions, the trans-isomer was
found to be the major adduct. When dioxane was used as the
only solvent (instead of a 1 : 1 mixture of dioxane : ethanol)
with 1 equivalent of BF3·OEt2 (following alternate conditions
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in entry 5, Table 1), the cis-adduct was obtained as the major the coordination of BF3 to a free hydroxyl group (A). Thus the
product (more than 80 : 20) but surprisingly as a mixture of coordinated hydroxyl group gets easily cleaved (B) because of
phenyl and ethyl esters. This current phenyl-to-ethyl trans- its benzylic nature which was further corroborated by an elec-
esterification occurred from an ether of BF3·OEt2. The use of tron rich propargylic system. A concerted transfer of the
2.5 equivalents of BF3·OEt2 was necessary for the complete hydroxyl group to the alkyne-terminal is disregarded because
phenyl-to-ethyl transformation. But, the use of diethyl ether as it fails to justify the formation of ethyl ester at the end. The
a co-solvent to reduce the dose of BF3·OEt2 did not work. Thus, subsequent C3-nucleophilic attack by hydroxyl oxygen (poss-
1zd–1zg were converted to 3zd–3zg in good yields (64–68%) ible when done in only dioxane) or ethereal oxygen (in the case
and satisfactory ratios (81 : 19 to 73 : 27) using 2.5 equivalents of nitrophenyl adducts 3zd–3zg) or EtOH form C or D or E,
of BF3·OEt2 in dioxane at room temperature. Finally, setting a respectively, which rationalizes the formation of both ethyl
limitation, the reaction was not applicable to aliphatic sub- and/or phenyl esters at the end. Next, we presume that an elec-
strates. Also, when an acetophenone (ketone) based substrate trophilic borylation of an allene intermediate, a key step which
was used in the reaction, a 1 : 1 mixture of isomers was formed determines the stereoselective outcome of the reaction, led to
which again indicated that there existed a kinetic control F–G which has preferably hydrogen cis to the BF3 fragment to
based on the steric constraints of one of the intermediates minimize steric hindrance. The intermediate G after elimin-
which outshined the conjugation factor that should favour the ation of PhOH, due to the better leaving properties of the phe-
trans-isomer. The ratio of the isomers was measured by 1H noxyl group over the ethoxyl group, formed H. The subsequent
NMR of the crude sample of the reaction after work-up. In stereospecific boron–proton exchange in F and H led to the
70% of the cases, the E and Z isomers were easily isolable and corresponding cis-products predominantly or exclusively. Our
hence the data of the pure Z isomers are provided in the ESI† efforts to detect any intermediate by mass spectroscopy in the
in those cases.
midway of the reaction all failed. To verify whether the phenyl
A mechanism is proposed in Scheme 3 rationalizing both ester 2a was the initial product that thereafter underwent a
the selective formation of Z-configured β-aryl-α,β-unsaturated tandem trans-esterification with EtOH, we treated the isolated
esters and the trans-esterification. The reaction is initiated by 2a with the optimized conditions (1 equiv. BF3·OEt, EtOH/diox-
ane). No trace of trans-esterified product 3a was observed (2a
was isolated as such), suggesting that the phenyl-to-ethyl
exchange occurred during the reaction pathway (as we
explained in Scheme 3) and not after the reaction. Finally, we
at this stage are unable to explain why BF3·OEt2 is required in
a stoichiometric amount (1 equivalent) although it seems to
act as a catalyst in the reaction.
In conclusion, we demonstrated the BF3·OEt2 mediated syn-
thesis of Z-β-aryl-α,β-unsaturated esters from readily available
phenoxy propargyl alcohols via a hitherto formidable syn selec-
tive Meyer–Schuster rearrangement. The transformations
proceed almost instantly (10 min) generating the products in
excellent yields and with very high stereoselectivities. The
mechanism appears to involve oxyborylation of an allene inter-
mediate as the critical step for a kinetically controlled
outcome of the reaction.
Experimental section
General information
All reagents and solvents were purchased from commercial
sources and used without purification. NMR spectra were
recorded with a 400 or 500 MHz spectrometer for 1H NMR,
100 or 125 MHz for 13C NMR spectroscopy. Chemical shifts are
reported relative to the residual signals of tetramethylsilane in
1
CDCl3 or deuterated solvent CDCl3 for H and 13C NMR spec-
troscopy. HRMS were recorded by using a Q-TOF mass spectro-
meter. Column chromatography was performed with silica gel
(100–200 mesh) as the stationary phase. All reactions were
Scheme 3 Proposed mechanism for syn-selective MSR.
monitored by using TLC.
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General procedure A for synthesis of (Z)-α,β-unsaturated esters CDCl3, major Z isomer) δ 166.0, 143.0, 135.7, 135.1, 129.7,
128.8, 128.4, 125.2, 121.2, 60.2, 19.9, 14.0; IR (neat) ν 3398,
1 equiv. (2.5 equiv. for 1zd–zg) of BF3 (in diethyl ether 48 w/v%) 3019, 1709, 1635, 1385, 1216, 1159, 1030, 757, 668 cm−1
;
was added slowly to a solution of substrate 1 (1 mmol, HRMS (ESI-TOF) calcd for C12H15O2 [M + H]+ 191.1072, found
1 equiv.) in 4 mL of anhydrous 1 : 1 dioxane : ethanol (only 191.1068.
dioxane in the case of 1zd–zg) under a nitrogen atmosphere at
(Z)-Ethyl 3-(4-ethylphenyl)acrylate (3e). 0.142 g of 3e was
room temperature. The resulting mixture was stirred at room obtained from 0.252 g, (1 mmol) of 1e using general procedure
temperature until the reaction was complete (10 min in A. Yield 70%; orange oil; Rf = 0.50 (SiO2, 2% EtOAc/hexanes);
general except 1zd and 1ze which took 1.5 h) as indicated by 1H NMR (400 MHz, CDCl3, major Z isomer) δ 7.64–7.56 (m,
TLC. Then the ethanol was evaporated under reduced pressure 2H), 7.29–7.17 (m, 2H), 6.93 (d, J = 12.6 Hz, 1H), 5.93 (d, J =
and 10 ml water was added to the residue. The reaction was 12.6 Hz, 1H), 4.22 (q, J = 7.1 Hz, 2H), 2.74–2.63 (m, 2H),
extracted with EtOAc (2 × 10 mL) and the combined organic 1.32–1.24 (m, 6H); 13C NMR (100 MHz, CDCl3, major Z isomer)
layers were washed with brine, and dried over anhydrous δ 166.3, 143.2, 132.2, 130.1, 127.5, 126.6, 118.8, 60.1, 38.2,
Na2SO4. After removal of the solvent under reduced pressure 15.3, 14.1; IR (neat) ν 3411, 3019, 2968, 1714, 1629, 1511, 1385,
the crude was purified by column chromatography with silica 1180, 757, 668 cm−1; HRMS (ESI-TOF) calcd for C13H17O2
gel (100–200 mesh) using 1–5% EtOAc/hexanes to obtain the [M + H]+ 205.1229, found 205.1221.
required product.
(Z)-Ethyl 3-(4-isopropylphenyl)acrylate (3f). 0.163 g of 3f was
(Z)-Ethyl 3-phenylacrylate (3a). 0.128 g of 3a was obtained obtained from 0.266 g, (1 mmol) of 1f using general procedure
from 0.224 g (1 mmol) of 1a using general procedure A. Yield A. Yield 75%; orange oil; Rf = 0.60 (SiO2, 3% EtOAc/hexanes);
1
73%; yellow oil; Rf = 0.40 (SiO2, 2% EtOAc/hexanes); H NMR 1H NMR (400 MHz, CDCl3, major Z isomer) δ 7.60–7.53 (m,
(400 MHz, CDCl3, major Z isomer) δ 7.68–7.54 (m, 2H), 2H), 7.24–7.18 (m, 2H), 6.90 (d, J = 12.7 Hz, 1H), 5.89 (d, J =
7.45–7.30 (m, 3H), 6.97 (d, J = 12.6 Hz, 1H), 5.97 (d, J = 12.7 Hz, 1H), 4.18 (q, J = 7.1 Hz, 2H), 2.91 (sep, J = 6.9 Hz, 1H),
12.6 Hz, 1H), 4.20 (q, J = 7.1 Hz, 2H), 1.27 (t, J = 7.1 Hz, 3H); 1.27–1.22 (m, 9H); 13C NMR (100 MHz, CDCl3, major Z isomer)
13C NMR (100 MHz, CDCl3, major Z isomer) δ 166.2, 143.0, δ 166.5, 150.3, 143.3, 132.4, 130.2, 126.2, 118.9, 60.3, 34.1,
134.9, 129.7, 129.0, 128.0, 119.9, 60.3, 14.1; IR (neat) ν 3399, 29.9, 14.2; IR (neat) ν 3412, 2963, 1712, 1630, 1401, 1215, 1169,
3019, 2927, 1637, 1403, 1216, 1157, 1068, 770, 668 cm−1
;
1066, 762 cm−1; HRMS (ESI-TOF) calcd for C14H19O2 [M + H]+
HRMS (ESI-TOF) calcd for C11H13O2 [M + H]+ 177.0916, found 219.1385, found 219.1382.
177.0913.
(Z)-Ethyl 3-(4-(tert-butyl)phenyl)acrylate (3g). 0.180 g of 3g
(Z)-Ethyl 3-(p-tolyl)acrylate (3b). 0.152 g of 3b was obtained was obtained from 0.280 g, (1 mmol) of 1g using general pro-
from 0.238 g (1 mmol) of 1b using general procedure A. Yield cedure A. Yield 78%; orange oil; Rf = 0.50 (SiO2, 2% EtOAc/hex-
1
1
80%; yellow oil; Rf = 0.50 (SiO2, 3% EtOAc/hexanes); H NMR anes); H NMR (400 MHz, CDCl3, major Z isomer) δ 7.62–7.56
(400 MHz, CDCl3, Z isomer) δ 7.59–7.46 (m, 2H), 7.20–7.11 (m, (m, 2H), 7.41–7.36 (m, 2H), 6.91 (d, J = 12.6 Hz, 1H), 5.90 (d,
2H), 6.89 (d, J = 12.6 Hz, 1H), 5.89 (d, J = 12.6 Hz, 1H), 4.18 (q, J = 12.6 Hz, 1H), 4.20 (q, J = 7.1 Hz, 2H), 1.33 (s, 9H), 1.27 (t,
J = 7.1 Hz, 2H), 2.36 (s, 1H) 1.26 (t, J = 7.1 Hz, 3H); 13C NMR J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3, major Z isomer)
(100 MHz, CDCl3, Z isomer) δ 166.4, 143.2, 139.3, 132.1, 130.0, δ 166.3, 152.4, 143.2, 132.0, 129.9, 125.0, 118.9, 60.2, 34.8,
128.8, 118.9, 60.3, 21.4, 14.2; IR (neat) ν 3398, 3021, 1714, 31.2, 14.2; IR (neat) ν 3410, 3019, 2968, 2400, 1710, 1629, 1511,
1629, 1511, 1404, 1214, 1137, 1030, 762, 668 cm−1; HRMS 1402, 1385, 852, 668 cm−1
(ESI-TOF) calcd for C12H15O2 [M + H]+ 191.1072, found C15H21O2 [M + H]+ 233.1542, found 233.1536.
; HRMS (ESI-TOF) calcd for
191.1063.
(Z)-Ethyl 3-(3,4-dimethylphenyl)acrylate (3h). 0.155 g of 3h
(Z)-Ethyl 3-(m-tolyl)acrylate (3c). 0.144 g of 3c was obtained was obtained from 0.252 g, (1 mmol) of 1h using general pro-
from 0.238 g, (1 mmol) of 1c using general procedure A. Yield cedure A. Yield 76%; orange oil; Rf = 0.40 (SiO2, 2% EtOAc/hex-
1
1
76%; orange oil; Rf = 0.40 (SiO2, 3% EtOAc/hexanes); H NMR anes); H NMR (400 MHz, CDCl3, major Z isomer) δ 7.43–7.36
(400 MHz, CDCl3, major Z isomer) δ 7.39 (d, J = 9.3 Hz, 2H), (m, 2H), 7.15–7.08 (m, 1H) 6.87 (d, J = 12.6 Hz, 1H), 5.88 (d, J =
7.24 (t, J = 7.2 Hz, 1H), 7.14 (d, J = 7.2 Hz, 1H), 6.92 (d, J = 12.6 12.6 Hz, 1H), 4.19 (q, J = 7.1 Hz, 2H), 2.27 (s, 6H), 1.27, (t, J =
Hz, 1H), 5.93 (d, J = 12.6 Hz, 1H), 4.18 (q, J = 7.1 Hz, 2H), 2.36 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3, major Z isomer) δ
(s, 3H), 1.25 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3, 166.5, 143.2, 138.0, 136.1, 132.5, 131.2, 129.4, 127.5, 118.8,
major Z isomer) δ 166.2, 142.9, 137.4, 134.8, 130.3, 129.7, 60.3, 19.8, 19.8, 14.2; IR (neat) ν 3409, 3020, 1638, 1402, 1216,
127.9, 126.8, 119.7, 60.2, 21.3, 14.0; IR (neat) ν 3397, 3019, 1069, 769, 668 cm−1; HRMS (ESI-TOF) calcd for C13H17O2
1711, 1632, 1371, 1212, 1157, 1032, 759, 660; HRMS (ESI-TOF) [M + H]+ 205.1229, found 205.1221.
calcd for C12H15O2 [M + H]+ 191.1072, found 191.1063.
(Z)-Ethyl 3-(4-methoxyphenyl)acrylate (3i). 0.162 g of 3i was
(Z)-Ethyl 3-(o-tolyl)acrylate (3d). 0.138 g of 3d was obtained obtained from 0.254 g, (1 mmol) of 1i using general procedure
from 0.238 g, (1 mmol) of 1d using general procedure A. Yield A. Yield 79%; yellow oil; Rf = 0.60 (SiO2, 4% EtOAc/hexanes);
1
73%; yellow oil; Rf = 0.50 (SiO2, 2% EtOAc/hexanes); H NMR 1H NMR (400 MHz, CDCl3, Z isomer) δ 7.78–7.65 (m, 2H),
(400 MHz, CDCl3, major Z isomer) δ 7.36–7.15 (m, 4H), 7.12 (d, 6.98–6.79 (m, 3H) 5.84 (d, J = 12.7, 1H), 4.21 (q, J = 7.1 Hz, 2H),
J = 12.1 Hz, 1H) 6.03 (d, J = 12.1 Hz, 1H), 4.10 (q, J = 7.1 Hz, 3.84 (s, 3H), 1.30 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz,
2H), 2.29 (s, 3H), 1.16 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3, Z isomer) δ 166.4, 160.4, 143.1, 132.1, 127.4, 117.2,
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113.4, 60.1, 55.2, 14.2; IR (neat) ν 3745, 3399, 3019, 1634, 1604, major Z isomer) δ 166.1, 157.1, 157.0, 141.9, 136.7, 129.8,
1511, 1403, 1256, 1216, 1161, 1029, 769 cm−1; HRMS (ESI-TOF) 129.4, 124.6, 123.4, 120.7, 119.9, 119.4, 119.0, 60.5, 14.1;
calcd for C12H15O3 [M + H]+ 207.1021, found 207.1015.
IR (neat) ν 3391, 3021, 2401, 1521, 1414, 1215, 1026, 761,
(Z)-Ethyl 3-(3-methoxyphenyl)acrylate (3j). 0.154 g of 3j was 670 cm−1; HRMS (ESI-TOF) calcd for C17H17O3 [M + H]+
obtained from 0.254 g, (1 mmol) of 1j using general procedure 269.1178, found 269.1181.
A. Yield 75%; yellow oil; Rf = 0.40 (SiO2, 3% EtOAc/hexanes);
(Z)-Ethyl 3-(2,5-dimethoxyphenyl)acrylate (3o). 0.179 g of 3o
1H NMR (400 MHz, CDCl3, major Z isomer) δ 7.32–7.20 (m, was obtained from 0.284 g, (1 mmol) of 1o using general pro-
2H), 7.16–7.08 (m, 1H), 6.95–6.84 (m, 2H), 5.94 (d, J = 12.6 Hz, cedure A. Yield 76%; yellow oil; Rf = 0.60 (SiO2, 5% EtOAc/
1H), 4.17 (q, J = 7.1 Hz, 2H), 3.81 (s, 3H), 1.24 (t, J = 7.1 Hz, hexanes); 1H NMR (400 MHz, CDCl3, major
Z isomer)
3H); 13C NMR (100 MHz, CDCl3, major Z isomer) δ 166.2, δ 7.25–7.19 (m, 1H), 7.12 (d, J = 12.5 Hz, 1H) 6.91–6.74 (m,
159.3, 142.6, 136.2, 129.0, 122.4, 120.0, 115.0, 114.8, 60.3, 55.3, 2H), 5.96 (d, J = 12.5 Hz, 1H), 4.14 (q, J = 7.1 Hz, 2H), 3.78 (s,
14.1; IR (neat) ν 3399, 3019, 1637, 1403, 1215, 1156, 768, 3H), 3.76 (s, 3H), 1.21 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz,
669 cm−1; HRMS (ESI-TOF) calcd for C12H15O3 [M + H]+ CDCl3, major Z isomer) δ 166.3, 152.9, 151.7, 138.4, 124.8,
207.1021, found 207.1015.
120.3, 116.1, 115.7, 111.4, 60.2, 56.1, 55.8, 14.1; IR (neat)
(Z)-Ethyl 3-(2-methoxyphenyl)acrylate (3k). 0.154 g of 3k was ν 3848, 3398, 3019, 2927, 1702, 1632, 1496, 1215, 1046,
obtained from 0.254 g, (1 mmol) of 1k using general procedure 758 cm−1; HRMS (ESI-TOF) calcd for C13H17O4 [M + H]+
A. Yield 75%; yellow oil; Rf = 0.50 (SiO2, 3% EtOAc/hexanes); 237.1127, found 237.1120.
1H NMR (400 MHz, CDCl3, major Z isomer) 7.60–7.46 (m, 1H)
(Z)-Ethyl 3-(3,4,5-trimethoxyphenyl)acrylate (3p). 0.212 g of
7.38–7.27 (m, 1H), 7.16 (d, J = 12.4 Hz, 1H), 6.99–6.82 (m, 2H), 3p was obtained from 0.314 g, (1 mmol) of 1p using general
5.97 (d, J = 12.4 Hz, 1H), 4.13 (q, J = 7.1 Hz, 1H), 3.83 (s, 3H), procedure A. Yield 80%; yellow solid; Rf = 0.60 (SiO2, 10%
1.20 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3, major EtOAc/hexanes); 1H NMR (400 MHz, CDCl3, Z isomer) δ 7.02 (s,
Z isomer) δ 166.3, 157.1, 138.9, 130.7, 130.3, 124.1, 120.0, 2H), 6.77 (d, J = 12.8, 1H) 5.86 (d, J = 12.8, 1H), 4.16 (q, J = 7.1,
119.8, 110.2, 60.0, 55.4, 14.0; IR (neat) ν 3398, 3019, 1708, 2H), 3.84 (s, 9H), 1.24 (t, J = 7.1, 3H); 13C NMR (100 MHz,
1633, 1464, 1403, 1251, 1215, 1160, 1068, 1027, 758 cm−1
HRMS (ESI-TOF) calcd for C12H15O3 [M + H]+ 207.1021, found 107.8, 60.6, 60.1, 55.9, 14.0; IR (neat) ν 3399, 3022, 1732, 1637,
207.1015.
1403, 1246, 1218, 770, 668 cm−1; HRMS (ESI-TOF) calcd for
(Z)-Ethyl 3-(4-ethoxyphenyl)acrylate (3l). 0.169 g of 3l was C14H19O5 [M + H]+ 267.1232, found 267.1224.
;
CDCl3, Z isomer) δ 166.1, 152.5, 142.9, 139.0, 130.0, 118.7,
obtained from 0.268 g, (1 mmol) of 1l using general procedure
Ethyl (Z)-3-(4-bromophenyl)acrylate (3q). 0.164 g of 3q was
A. Yield 77%; yellow oil; Rf = 0.50 (SiO2, 3% EtOAc/hexanes); obtained from 0.301 g (1 mmol) of 1q using general procedure
1H NMR (400 MHz, CDCl3, major Z isomer) δ 7.74–7.61 (m, A. Yield 65%; orange oil; Rf = 0.50 (SiO2, 3% EtOAc/hexanes);
2H), 6.92–6.73 (m, 3H), 5.81 (d, J = 12.7, 1H), 4.91 (q, J = 7.1 1H NMR (400 MHz, CDCl3, Z isomer) δ 7.64–7.60 (m, 2H), 7.02
Hz, 2H), 4.05 (q, J = 7.0, 2H), 1.41 (t, J = 7.0 Hz, 3H), 1.27 (t, J = (t, J = 8.6 Hz, 2H), 6.87 (d, J = 12.6 Hz, 1H), 5.92 (d, J = 12.6 Hz,
7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3, major Z isomer) 1H), 4.17 (q, J = 7.1 Hz, 2H), 1.25 (t, J = 7.1 Hz, 3H); 13C NMR
δ 166.6, 159.9, 143.3, 132.3, 127.3, 117.2, 114.0, 63.5, 60.2, (100 MHz, CDCl3, Z isomer) δ 166.0, 142.0, 132.1, 132.0, 119.5,
14.8, 14.3; IR (neat) ν 3396, 3021, 1710, 1604, 1510, 1396, 1216, 115.0, 114.8, 60.3, 14.0; IR (neat) ν 3390, 3019, 2399, 1637,
1044, 765, 668 cm−1; HRMS (ESI-TOF) calcd for C13H17O3 1522, 1215, 831, 757 cm−1
; HRMS (ESI-TOF) calcd for
[M + H]+ 221.1178, found 221.1164.
C11H12BrO2 [M + H]+ 255.0021, found 255.0020.
(Z)-Ethyl 3-(4-(allyloxy)phenyl)acrylate (3m). 0.167 g of 3m
Ethyl (Z)-3-(4-chlorophenyl)acrylate (3r). 0.136 g of 3r was
was obtained from 0.280 g, (1 mmol) of 1m using general pro- obtained from 0.258 g, (1 mmol) of 1r using general procedure
cedure A. Yield 72%; yellow oil; Rf = 0.40 (SiO2, 2% EtOAc/hex- A. Yield 65%; orange oil; Rf = 0.60 (SiO2, 3% EtOAc/hexanes);
1
anes); H NMR (400 MHz, CDCl3, major Z isomer) δ 7.75–7.64 1H NMR (400 MHz, CDCl3, Z isomer) δ 7.54 (d, J = 8.4 Hz, 2H),
(m, 2H), 6.93–6.86 (m, 2H), 6.82 (d, J = 12.7 Hz, 1H), 6.13–5.97 7.31 (d, J = 8.5 Hz, 2H), 6.87 (d, J = 12.7 Hz, 1H), 5.95 (d, J =
(m, 1H), 5.82 (d, J = 12.7 Hz 1H), 5.46–5.36 (m, 1H), 5.34–5.23 12.7 Hz, 1H), 4.17 (q, J = 7.1 Hz, 2H), 1.25 (t, J = 7.1 Hz, 3H);
(m, 1H), 4.60–4.50 (m, 2H), 4.19 (q, J = 7.1 Hz, 2H), 1.27 (t, J = 13C NMR (100 MHz, CDCl3, Z isomer) δ 165.9, 141.8, 134.9,
7.1 Hz); 13C NMR (100 MHz, CDCl3, major Z isomer) δ 166.4, 133.3, 131.2, 128.2, 120.4, 60.4, 14.1; IR (neat) ν 3391, 3019,
159.4, 143.1, 133.0, 132.2, 127.5, 117.8, 117.3, 114.2, 68.7, 60.1, 2400, 1633, 1402, 1215, 929, 831 cm−1; HRMS (ESI-TOF) calcd
14.2; IR (neat) ν 3411, 3019, 2968, 1714, 1629, 1402, 1215, 852, for C11H12ClO2 [M + H]+ 211.0526, found 211.0522.
757 cm−1; HRMS (ESI-TOF) calcd for C14H17O3 [M + H]+
233.1178, found 233.1177.
Ethyl (Z)-3-(4-fluorophenyl)acrylate (3s). 0.126 g of 3s was
obtained from 0.242 g, (1 mmol) of 1s using general procedure
(Z)-Ethyl 3-(3-phenoxyphenyl)acrylate (3n). 0.176 g of 3n was A. Yield 65%; orange oil; Rf = 0.40 (SiO2, 2% EtOAc/hexanes);
obtained from 0.316 g, (1 mmol) of 1n using general procedure 1H NMR (400 MHz, CDCl3, Z isomer) δ 7.65–7.61 (m, 2H),
A. Yield 66%; orange oil; Rf = 0.60 (SiO2, 4% EtOAc/hexanes); 7.05–7.00 (m, 2H), 6.87 (d, J = 12.7 Hz, 1H), 5.92 (d, J = 12.7
1HNMR (400 MHz, CDCl3, major Z isomer) δ 7.35–7.29 (m, Hz, 1H), 4.17 (q, J = 7.1 Hz, 2H), 1.25 (t, J = 7.1 Hz, 3H); 13C
4H), 7.20 (s, 1H), 7.10 (t, J = 7.3 Hz, 1H), 7.03–6.96 (m, 3H), NMR (100 MHz, CDCl3, Z isomer) δ 165.9, 162.9 (d, J = 249.4
6.88 (d, J = 12.6 Hz, 1H), 5.94 (d, J = 12.6 Hz, 1H), 4.14 (q, J = Hz), 142.0, 132.0 (d, J = 8.4 Hz), 130.9 (d, J = 3.2 Hz), 119.4 (d,
7.1 Hz, 2H), 1.22 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3, J = 1.1 Hz), 114.9 (d, J = 21.5 Hz), 60.2, 14.0; IR (neat) ν 3684,
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3022, 2401, 1713, 1631, 1511, 1421, 1215, 928, 846, 762 cm−1
;
Hz, 1H), 4.34 (q, J = 7.1 Hz, 1H), 4.02 (q, J = 7.1 Hz, 3H), 1.39
HRMS (ESI-TOF) calcd for C11H12FO2 [M + H]+ 195.0821, found (t, J = 7.1 Hz, 1.5H), 1.02 (t, J = 7.1 Hz, 3H); 13C NMR
195.0821.
(100 MHz, CDCl3) δ 166.9, 166.0, 141.9, 141.7, 133.7, 133.3,
(Z)-Ethyl 3-(5-bromo-2-methoxyphenyl)acrylate (3t). 0.190 g 133.1, 131.9, 131.5, 131.1, 130.5, 128.7, 128.6, 126.9, 126.6,
of 3t was obtained from 0.332 g, (1 mmol) of 1t using general 126.3, 125.9, 125.5, 125.0, 124.5, 123.5, 122.9, 121.0, 60.6, 60.2,
procedure A. Yield 67%; yellow oil; Rf = 0.40 (SiO2, 2% EtOAc/ 14.4, 13.9; IR (neat) ν 3399, 3019, 2928, 2349, 1634, 1584, 1403,
hexanes); 1H NMR (400 MHz, CDCl3, major
Z
isomer) 1215, 1155, 1068 cm−1; HRMS (ESI-TOF) calcd for C15H15O2
δ 7.67–7.57 (m, 1H), 7.46–7.32 (m, 1H) 7.04 (d, J = 12.4 Hz, [M + H]+ 227.1072, found 227.1071.
1H), 6.83–6.68 (m, 1H), 5.98 (d, J = 12.4 Hz, 1H), 4.14 (q, J = 7.1
Ethyl (Z)-3-(4-((trimethylsilyl)ethynyl)phenyl)acrylate (3y).
Hz, 2H), 3.80 (s, 3H), 1.21 (t, J = 7.1 Hz, 3H); 13C NMR 0.190 g of 3y was obtained from 0.320 g, (1 mmol) of 1y using
(100 MHz, CDCl3, major Z isomer) δ 166.1, 156.3, 137.2, 133.3, general procedure A. Yield 70%; orange oil; Rf = 0.6 (SiO2, 3%
132.7, 126.2, 121.4, 113.0, 112.0, 60.4, 55.8, 14.1; IR (neat) EtOAc/hexanes); 1H NMR (400 MHz, CDCl3, major Z isomer)
ν 3398, 3019, 2926, 1635, 1404, 1215, 1068, 768, 758 cm−1
;
δ 7.52 (d, J = 8.0 Hz, 2H), 7.47–7.41 (m, 2H), 6.88 (d, J = 12.4
HRMS (ESI-TOF) calcd for C12H14BrO3 [M + H]+ 285.0126, Hz, 1H), 5.95 (d, J = 12.4 Hz, 1H), 4.17 (q, J = 7.1 Hz, 2H), 1.24
found 285.0125.
(t, J = 7.1 Hz, 3H), 0.25 (s, 9H); 13C NMR (100 MHz, CDCl3,
(Z)-Ethyl 3-(5-chloro-2-methoxyphenyl)acrylate (3u). 0.156 g major Z isomer) δ 166.0, 142.0, 134.9, 131.5, 129.7, 123.7,
of 3u was obtained from 0.288 g, (1 mmol) of 1u using general 120.5, 104.9, 95.6, 60.4, 14.1, 0.02; IR (neat) ν 3019, 2399, 1602,
procedure A. Yield 65%; yellow oil; Rf = 0.40 (SiO2, 2% EtOAc/ 1522, 1476, 1215, 1024, 758 cm−1; HRMS (ESI-TOF) calcd for
hexanes); 1H NMR (400 MHz, CDCl3, major
δ 7.53–7.48 (m, 1H), 7.30–7.19 (m, 1H), 7.04 (d, J = 12.4 Hz,
Z
isomer) C16H21O2Si [M + H]+ 273.1311, found 273.1285.
(Z)-Ethyl 3-(2-((trimethylsilyl)ethynyl)phenyl)acrylate (3z).
1H), 6.89–6.74 (m, 1H), 5.98 (d, J = 12.4 Hz, 1H), 4.14 (q, J = 7.1 0.184 g of 3z was obtained from 0.320 g, (1 mmol) of 1z using
Hz, 2H), 3.80 (s, 3H), 1.21 (t, J = 7.1 Hz, 3H); 13C NMR general procedure A. Yield 68%; yellow oil; Rf = 0.50 (SiO2, 3%
(100 MHz, CDCl3, major Z isomer) δ 166.0, 155.8, 137.3, 130.4, EtOAc/hexanes); 1H NMR (400 MHz, CDCl3, Z/E mixture)
129.7, 125.7, 124.9, 121.3, 115.5, 60.4, 55.8, 14.1; IR (neat) δ 7.68–7.57 (m, 1.4H), 7.55–7.46 (m, 1.6H), 7.38–7.21 (m, 4.4
ν 3399, 3019, 2925, 1712, 1635, 1484, 1407, 1253, 1215, 1159, Hz), 6.06 (d, J = 12.4, 1H), 4.15 (q, J = 7.1 Hz, 2H), 1.21 (t, J =
769 cm−1; HRMS (ESI-TOF) calcd for C12H14ClO3 [M + H]+ 7.1 Hz, 3H), 0.27 (s, 9H); 13C NMR (100 MHz, CDCl3, Z/E
241.0631, found 241.0630.
mixture) δ 166.8, 166.0, 142.3, 141.6, 137.5, 136.2, 133.0, 132.2,
(Z)-Ethyl 3-([1,1′-biphenyl]-4-yl)acrylate (3v). 0.166 g of 3v 129.5, 129.3, 128.8, 128.3, 127.8, 126.2, 123.8, 122.8, 121.5,
was obtained from 0.300 g, (1 mmol) of 1v using general pro- 121.2, 120.0, 103.2, 102.6, 101.1, 99.8, 60.5, 60.3, 14.3, 14.0,
cedure A. Yield 66%; orange gum; Rf = 0.50 (SiO2, 3% EtOAc/ 0.02, 0.05; IR (neat) ν 3021, 2272, 1730, 1593, 1487, 1216, 1085,
hexanes); 1H NMR (400 MHz, CDCl3, major
Z
isomer) 766 cm−1; HRMS (ESI-TOF) calcd for C16H21O2Si [M + H]+
δ 7.77–7.69 (m, 2H), 7.67–7.56 (m, 4H), 7.50–7.43 (m, 2H), 273.1311, found 273.1285.
7.41–7.34 (m, 1H), 6.98 (d, J = 12.7 Hz, 1H), 5.99 (d, J = 12.7
(Z)-Ethyl 3-(furan-2-yl)acrylate (3za). 0.116 g of 3za was
Hz, 1H), 4.23 (q, J = 7.1 Hz, 2H), 1.30 (t, J = 7.1 Hz, 3H); 13C obtained from 0.214 g, (1 mmol) of 1za using general pro-
NMR (100 MHz, CDCl3, major Z isomer) δ 166.1, 142.6, 141.7, cedure A. Yield 70%; orange gum; Rf = 0.50 (SiO2, 3% EtOAc/
140.4, 133.7, 130.5, 128.7, 127.5, 127.0, 126.5, 119.6, 60.2, 14.1; hexanes); 1H NMR (400 MHz, CDCl3, Z isomer) δ 7.71–7.62 (m,
IR (neat) ν 3399, 3021, 1711, 1631, 1485, 1215, 1181, 1031, 854, 1H), 7.50–7.43 (m, 1H), 6.77 (d, J = 12.9 Hz, 1H), 6.51–6.46 (m,
761 cm−1; HRMS (ESI-TOF) calcd for C17H17O2 [M + H]+ 1H), 5.73 (d, J = 12.9 Hz, 1H), 4.22 (q, J = 7.1 Hz, 2H), 1.31 (t,
253.1229, found 253.1226.
J = 7.1, 3H); 13C NMR (100 MHz, CDCl3, Z isomer) δ 166.2,
(Z)-Ethyl 3-(naphthalen-2-yl)acrylate (3w). 0.167 g of 3w was 151.0, 144.0, 130.5, 117.1, 114.6, 112.7, 60.3, 14.4; IR (neat)
obtained from 0.274 g, (1 mmol) of 1w using general pro- ν 3400, 3019, 1638, 1403, 1216, 1069, 769, 669 cm−1; HRMS
cedure A. Yield 74%; yellow gum; Rf = 0.40 (SiO2, 2% EtOAc/ (ESI-TOF) calcd for C9H11O3 [M + H]+ 167.0708, found
hexanes); 1H NMR (400 MHz, CDCl3, major Z isomer) δ 8.05 (s, 167.0716.
1H), 7.91–7.68 (m, 4H), 7.56–7.42 (m, 2H), 7.10 (d, J = 12.6,
(Z)-Ethyl 3-(furan-3-yl)acrylate (3zb). 0.112 g of 3zb was
1H), 6.04 (d, J = 12.6, 1H), 4.22 (q, J = 7.1 Hz, 2H), 1.30–1.23 obtained from 0.214 g, (1 mmol) of 1zb using general pro-
(m, 3H); 13C NMR (100 MHz, CDCl3, major Z isomer) δ 166.4, cedure A. Yield 68%; brown gum; Rf = 0.40 (SiO2, 2% EtOAc/
143.0, 133.5, 133.0, 132.5, 129.9, 128.5, 127.7, 127.5, 127.1, hexanes); 1H NMR (400 MHz, CDCl3, major Z isomer) δ 8.11 (s,
126.8, 126.3, 120.1, 60.4, 14.2; IR (neat) ν 3408, 2932, 1630, 1H), 7.42–7.36 (m, 1H), 6.95–6.90 (m, 1H), 6.69 (d, J = 12.5 Hz,
1397, 1068, 768, 703 cm−1
C15H15O2 [M + H]+ 227.1072, found 227.1071.
;
HRMS (ESI-TOF) calcd for 1H), 5.79 (d, J = 12.5 Hz, 1H), 4.20 (q, J = 7.1 Hz, 2H), 1.30 (t,
J = 7.1 Hz, 1H 3H); 13C NMR (100 MHz, CDCl3, major
(Z)-Ethyl 3-(naphthalen-1-yl)acrylate (3x). 0.153 g of 3x was Z isomer) δ 166.3, 147.0, 142.9 133.6, 121.3, 116.8, 112.3, 60.1,
obtained from 0.274 g, (1 mmol) of 1x using general procedure 14.3; HRMS (ESI-TOF) calcd for C9H11O3 [M + H]+ 167.0708,
A. Yield 68%; orange oil; Rf = 0.40 (SiO2, 2% EtOAc/hexanes); found 167.0718.
1H NMR (400 MHz, CDCl3) δ 8.55 (d, J = 15.5 Hz, 0.5H),
(Z)-Ethyl 3-(benzofuran-2-yl)acrylate (3zc). 0.151 g of 3zc was
8.26–8.18 (m, 0.5H), 7.98–7.79 (m, 4H), 7.79–7.72 (m, 0.5H), obtained from 0.264 g, (1 mol) of 1zc using general procedure
7.65–7.40 (m, 6H), 6.55 (d, J = 15.7 Hz, 0.5H), 6.26 (d, J = 12.1 A. Yield 70%; yellow gum; Rf = 0.50 (SiO2, 4% EtOAc/hexanes);
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1H NMR (400 MHz, CDCl3, major Z isomer) δ 7.95 (s, 1H), cedure A. Yield 75%; yellow oil; Rf = 0.4 (SiO2, 2% EtOAc/hex-
1
7.66–7.59 (m, 1H), 7.48–7.42 (m, 1H), 7.38–7.30 (m, 1H), anes); H NMR (400 MHz, CDCl3, Z/E mixture) δ 7.53–7.43 (m,
7.27–7.19 (m, 1H), 6.88 (d, J = 12.9 Hz, 1H), 5.96 (d, J = 12.9 2H), 7.41–7.28 (m, 6H), 7.25–7.16 (m, 2H), 6.14 (d, J = 1.2 Hz,
Hz, 1H), 4.28 (q, J = 7.1 Hz, 2H), 1.35 (t, J = 7.1 Hz, 3H); 13C 1H), 5.91 (d, J = 1.4 Hz, 1H), 4.22 (q, J = 7.1 Hz, 2H), 4.00 (q, J =
NMR (100 MHz, CDCl3, major Z isomer) δ 165.9, 154.9, 151.7, 7.1 Hz, 2H), 2.58 (d, J = 1.2 Hz, 3H), 2.18 (d, J = 1.4 Hz, 3H),
130.3, 128.9, 126.2, 123.2, 122.3, 118.7, 112.6, 111.3, 60.5, 14.3; 1.32 (t, J = 7.1 Hz, 3H), 1.08 (t, J = 7.1 Hz, 3H); 13C NMR
IR (neat) ν 3399, 3021, 1709, 1633, 1425, 1215, 1021, 761, (100 MHz, CDCl3, Z/E mixture) δ 166.9, 165.9, 155.5, 155.3,
669 cm−1; HRMS (ESI-TOF) calcd for C13H13O3 [M + H]+ 142.3, 140.9, 129.0, 128.5, 127.9, 127.7, 126.9, 126.3, 117.8,
217.0865, found 217.0852.
117.2, 59.8, 59.8, 27.1, 18.0, 14.4, 14.0; IR (neat) ν 3400, 3020,
(Z)-Ethyl 3-(4-nitrophenyl)acrylate (3zd). 0.143 g of 3zd was 2981, 2927, 1708, 1630, 1488, 1444, 1273, 1165, 1045, 855,
obtained from 0.269 g, (1 mmol) of 1zd using general pro- 697 cm−1; HRMS (ESI-TOF) calcd for C12H15O2 [M + H]+
cedure A. Yield 65%; yellow solid; Rf = 0.6 (SiO2, 5% EtOAc/ 191.1072, found 191.1068.
hexanes); 1H NMR (400 MHz, CDCl3, major
Z isomer)
δ 8.32–8.10 (m, 2H), 7.76–7.59 (m, 2H), 7.00 (d, J = 12.5 Hz,
1H), 6.12 (d, J = 12.5 Hz, 1H), 4.17 (q, J = 7.1 Hz, 2H), 1.24 (t,
J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3, major Z isomer)
δ 165.4, 147.6, 141.6, 140.6, 130.3, 123.4, 123.2, 60.8, 14.1;
IR (neat) ν 3401, 3020, 1594, 1514, 1402, 1385, 1258, 1067,
668 cm−1; HRMS (ESI-TOF) calcd for C11H12NO4 [M + H]+
222.0766, found 222.0774.
Acknowledgements
SP and MHR thank CSIR for the fellowships. We thank SAIF
division CSIR-CDRI for the analytical support. We gratefully
acknowledge the financial support by CSIR-THUNDER (BSC
0102). CDRI Communication no. 9260.
(Z)-Ethyl 3-(3-nitrophenyl)acrylate (3ze). 0.141 g of 3ze was
obtained from 0.269 g, (1 mmol) of 1ze using general pro-
cedure A. Yield 64%; orange gum; Rf = 0.7 (SiO2, 5% EtOAc/
1
hexanes); H NMR (400 MHz, CDCl3, Z isomer) δ 8.43 (s, 1H),
Notes and references
8.24–8.12 (m, 1H) 7.92–7.81 (m, 1H), 7.59–7.48 (m, 1H), 6.99
(d, J = 12.5 Hz, 1H), 6.11 (d, J = 12.5 Hz, 1H), 4.18 (q, J = 7.1 1 (a) K. H. Meyer and K. Schuster, Chem. Ber., 1922, 55, 819;
Hz, 2H), 1.25 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3,
Z isomer) δ 165.5, 140.5, 136.5, 135.5, 129.0, 124.5, 123.5,
122.8, 115.3, 60.8, 14.1; IR (neat) ν 3408, 3020, 1590, 1402,
1385, 1215, 1154, 1068, 757 cm−1; HRMS (ESI-TOF) calcd for
C11H12NO4 [M + H]+ 222.0766, found 222.0772.
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Ethyl (Z)-3-(4-fluoro-3-nitrophenyl)acrylate (3zf). 0.155 g of
3zf was obtained from 0.287 g, (1 mmol) of 1zf using general
procedure A. Yield 65%; orange oil; Rf = 0.60 (SiO2, 5% Ehex-
1
anes); H NMR (400 MHz, CDCl3, Z isomer) δ 8.34 (dd, J = 7.1,
2.2 Hz, 1H), 7.86–7.90 (m, 1H), 7.26 (dd, J = 10.4, 8.7 Hz, 1H),
6.89 (d, J = 12.5 Hz, 1H), 6.08 (d, J = 12.5 Hz, 1H), 4.14 (q, J =
7.1 Hz, 2H), 1.26 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3,
Z isomer) δ 165.4, 15.5 (d, J = 262.7 Hz), 139.6, 136.9 (d, J =
8.6), 131.8 (d, J = 4.3 Hz), 127.5, 122.6, 118.0 (d, J = 21.0 Hz),
60.9, 14.1; IR (neat) ν 3407, 3020, 1630, 1531, 1400, 1379, 1261,
1066, 770, 666 cm−1; HRMS (ESI-TOF) calcd for C11H11FNO2
[M + H]+ 240.0672, found 240.0670.
(Z)-Ethyl 3-(4-bromo-3-nitrophenyl)acrylate (3zg). 0.202 g of
3zg was obtained from 0.346 g, (1 mmol) of 1zg using general
procedure A. Yield 68%; yellow gum; Rf = 0.50 (SiO2, 5%
EtOAc/hexanes); 1H NMR (400 MHz, CDCl3, major Z isomer)
δ 8.13–8.07 (m, 1H), 7.77–7.47 (m, 2H), 6.92–6.74 (m, 2H), 6.09
(d, J = 12.5 Hz, 1H), 4.17 (q, J = 7.1 Hz, 2H), 1.25 (t, J = 7.1 Hz,
3H); 13C NMR (100 MHz, CDCl3, major Z isomer) δ 165.3,
139.4, 135.4, 134.6, 134.2, 129.5, 126.6, 123.0, 115.3, 60.9, 14.0;
IR (neat) ν 3409, 3020, 1638, 1537, 1402, 1385, 1216, 1069, 769,
668 cm−1; HRMS (ESI-TOF) calcd for C11H11BrNO4 [M + H]+
299.9871, found 299.9865.
Ethyl 3-phenylbut-2-enoate (3zh). 0.142
g of 3zh was
obtained from 0.238 g (1 mmol) of 1zh using general pro-
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