Triphenylphosphine-mediated synthesis of methyl 2-aroyloxypropenoates from 2-aroyl-2-methoxycarbonyloxiranes

Article abstract of DOI:10.1080/00397910902763920

A new synthesis of several 2-aroyloxypropenoic acid methyl esters 5 by the reaction of 2-aroyl-2-methoxycarbonyloxiranes 2 with triphenylphosphine in tetrahydrofuran has been described.

Full text of DOI:10.1080/00397910902763920

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Triphenylphosphine-Mediated
Synthesis of Methyl 2-
Aroyloxypropenoates
from 2-Aroyl-2-
methoxycarbonyloxiranes
Eun-Gu Han a & Kee-Jung Lee a
a Organic Synthesis Laboratory, Department of
Chemical Engineering, Hanyang University, Seoul,
Korea
Published online: 04 Sep 2009.
To cite this article: Eun-Gu Han & Kee-Jung Lee (2009): Triphenylphosphine-Mediated
Synthesis of Methyl 2-Aroyloxypropenoates from 2-Aroyl-2-methoxycarbonyloxiranes,
Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 39:19, 3399-3405
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Synthetic Communications1, 39: 3399–3405, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902763920
Triphenylphosphine-Mediated Synthesis
of Methyl 2-Aroyloxypropenoates from
2-Aroyl-2-methoxycarbonyloxiranes
Eun-Gu Han and Kee-Jung Lee
Organic Synthesis Laboratory, Department of Chemical Engineering,
Hanyang University, Seoul, Korea
Abstract: A new synthesis of several 2-aroyloxypropenoic acid methyl esters 5 by
the reaction of 2-aroyl-2-methoxycarbonyloxiranes 2 with triphenylphosphine in
tetrahydrofuran has been described.
Keywords: 2-Aroyl-2-methoxycarbonyloxirane, Baylis–Hillman adduct, methyl
2-aroyloxypropenoate, triphenylphosphine
The captodative alkene 2-aroyloxypropenoic acid methyl esters have been
shown to be highly reactive and regioselective in Diels–Alder reactions.[1]
Radical homopolymerization of some captodative substituted methyl
2-acyloxypropenoates was studied kinetically by azo initiators and was
found to give a polymer with excellent optical properties.[2] The captodative
olefin methyl 2-acyloxypropenoates were prepared mainly by reaction of
methyl pyruvate with an acyl chloride in the presence of triethylamine.[1a,3]
The Baylis–Hillman reaction[4] is a powerful carbon–carbon bond-
forming method for installing b-hydroxy-a-methylenecarbonyl units, which
are extremely versatile building blocks in organic synthesis.[5] It is known
that the reaction of Baylis–Hillman adducts with silica gel–supported
sodium hypochlorite is an efficient procedure for the synthesis of acyloxir-
anes.[6] We envisioned that deoxygenation of acyloxiranes with a suitable
Received October 23, 2008.
Address correspondence to Kee-Jung Lee, Organic Synthesis Laboratory,
Department of Chemical Engineering, Hanyang University, Seoul 133-791,
Korea. E-mail: leekj@hanyang.ac.kr
3399

3400
E.-G. Han and K.-J. Lee
Table 1. Methyl 2-benzoyloxypropenoate 5a synthesis in various reaction
conditions
Entry
Reagem
Solvent
Time (h)a
Yield (%)
1
2
3
4
5
6
7
8
9
Ph3P
Ph3P
Ph3P
(EtO)3P
Bu3P
Ph3P
Ph3P
Ph3P
Ph3P
Benzene
Toluene
Xylene
Benzene
Benzene
THF
Dioxane
CH3CN
CH2C12
72
72
48
120
120
36
24
4
72
20
14
Trace
13
Trace
46
25
23
23
aReflux temperature.
phosphine reagent, originally discovered by Wittig,[7] might lead to the
a-methylene-b-oxo esters, which are not easy to obtain.
Various reaction media were first scrutinized in a test reaction of
benzoyloxirane 2a with triphenylphosphine, tributylphosphine, or
triethylphosphite (Table 1). The expected a-methylene-b-oxo ester 6a
Scheme 1. Synthesis of methyl 2-aroyloxypropenoates.

Triphenylphosphine-Mediated Synthesis
3401
Table 2. Methyl 2-Aroyloxypropenoates 5a–f
Entry
Substrate
Product
Time (h)
Yield (%)
1
2
3
4
5
6
2a
2b
2c
2d
2e
2f
5a
5b
5c
5d
5e
5f
36
10
17
48
10
20
46
40
47
75
58
43
was not produced at all. We found that the product was the known
methyl 2-benzoyloxypropenoate 5a[1a] and the use of triphenylphosphine
in tetrahydrofuran (THF) solvent system was the best reaction condition
to improve product yields (entry 6, Table 1). The optimized protocol for
the aroyloxypropenoic acid methyl ester synthesis proved to be general,
and a wide range of acyloxiranes were readily converted to the aroyloxy
propenoate product in moderate to poor yields (Scheme 1, Table 2).
The conversion of 2 into 5 would appear to proceed in such a way
that a nucleophilic attack of triphenylphosphine at the epoxide gives a
betaine 3, the resulting negative oxygen attacks carbonyl carbon to give
another epoxide betaine 4, and the electrons on the negative oxygen
reform the pi bond as the carbon–carbon bond cleaves and the triphenyl-
phosphine leaves. Similar conversions are known, such as flash vacuum
pyrolysis of indenone epoxide to isocoumarin[8] and acid treatment of
2,3-diphenyl-2,3-epoxyindanone to 3,4-diphenylisocoumarin.[9]
In summary, we have introduced a new synthesis of 2-aroyloxypro-
penoic acid methyl esters from the reaction of 2-aroyl-2-methoxycarbo-
nyloxiranes, which are readily prepared from the Baylis–Hillman
adducts with triphenylphosphine.
EXPERIMENTAL
Silica gel 60 (70–230 mesh ASTM) used for column chromatography was
supplied by E. Merck. Analytical thin layer chromatography (TLC) was
carried out on Merck silica-gel 60 F254 TLC plates. Melting points were
taken using an Electrothermal melting-point apparatus and are uncor-
rected. Infrared (IR) spectra were recorded on a Nicolet Magna 550
1
Fourier transform (FTIR)-spectrometer. The H and 13C NMR spectra
were measured on a Gemini 300 spectrometer using CDCl3. All chemical
shifts are reported in parts per million (ppm) relative to tetramethylsilane
(TMS). Mass spectra (MS) were recorded on a Hewlett-Packard 5972A
instrument operating at 70 eV.

3402
E.-G. Han and K.-J. Lee
The known Baylis–Hillman (BH) adducts 1a–f[10] and oxiranes 2a,
2c, 2e, and 2f[6] were prepared according to the literature procedures.
2-(2-Chlorobenzoyl)-2-methoxycarbonyloxirane (2b)
Silica gel (10 g) was added to a stirred solution of BH adduct 1b (2.27 g,
10 mmol) in acetonitrile (10 ml), and the mixture was treated with 10–13%
sodium hypochlorite solution (40 ml). After stirring for 2.5 h, the mixture
was extracted with diethyl ether (2 ꢀ 20 ml). The organic layer was dried
over anhydrous magnesium sulfate, and the solvent was evaporated in
vacuo. The residue was purified by column chromatography to produce
1
1.54 g (64%) of 2b as an yellow oil: IR (CH2Cl2) 1754, 1708 cmꢁ1; H
NMR (CDCl3) d 3.19 (d, J ¼ 6.4 Hz, 1H), 3.47 (d, J ¼ 6.4 Hz, 1H), 3.80
(s, 3H), 7.28–7.58 (m, 3H), 7.66–7.69 (m, 1H); 13C NMR (CDCl3) d
52.6, 53.2, 59.5, 126.9, 128.9, 130.6, 132.7, 133.2, 134.9, 166.8, 190.4;
EIMS (%) 240 (1) [Mþ], 205 (5), 141 (34), 139 (100), 113 (9), 111 (28),
75 (18). Anal. calcd. for C11H9ClO4: C, 54.90; H, 3.77. Found: C,
54.72; H, 3.59.
2-(4-Fluorobenzoyl)-2-methoxycarbonyloxirane (2d)
Silica gel (10 g) was added to a stirred solution of BH adduct 1d (2.10 g,
10 mmol) in acetonitrile (10 ml), and the mixture was treated with 10–13%
sodium hypochlorite solution (40 ml). After stirring for 10 min, the
mixture was extracted with diethyl ether (2 ꢀ 20 ml). The organic layer
was dried over anhydrous magnesium sulfate, and the solvent was evapo-
rated in vacuo. The residue was purified by column chromatography to
produce 1.48 g (66%) of 2d as a white solid: mp 39–40ꢂC; IR (KBr)
1
1763, 1692 cmꢁ1; H NMR (CDCl3) d 3.23 (d, J ¼ 6.1 Hz, 1H), 3.41 (d,
J ¼ 6.1 Hz, 1H), 3.79 (s, 3H), 7.15–7.21 (m, 2H), 8.03–8.08 (m, 2H); 13C
NMR (CDCl3) d 51.3, 53.4, 58.8, 116.1 (d, J ¼ 22.0 Hz), 130.6, 131.9
(d, J ¼ 9.8 Hz), 166.4 (d, J ¼ 258 Hz), 167.5, 189.0; EIMS (%) 224 (1)
[Mþ], 123 (100), 95 (35), 75 (12). Anal. calcd. for C11H9FO4: C, 58.93;
H, 4.05. Found: C, 58.78; H, 4.25.
General Procedure for the Synthesis of Methyl
2-Aroyloxypropenoates 5a–f
2-Aroyl-2-methoxycarbonyloxirane 2a–f (1 mmol), PPh3 (1 mmol), and
THF (2 ml) were stirred at reflux temperature for the time indicated in

Triphenylphosphine-Mediated Synthesis
3403
Table 2. After the reaction was completed, the reaction mixture was
concentrated under reduced pressure. The resulting mixture was chroma-
tographed on silica gel, eluting with hexane=EtOAc (8:1) to produce
pure 5a–f.
The physical and spectral data of 5a–f prepared by this general
method follow.
Methyl 2-Benzoyloxypropenoate (5a)[1a]
Yellow oil; yield 46%; IR (CH2Cl2) 1736, 1649 cmꢁ1; 1H NMR (CDCl3) d
3.82 (s, 3H), 5.62 (d, J ¼ 1.8 Hz, 1H), 6.17 (d, J ¼ 1.8 Hz, 1H), 7.46–7.52
(m, 2H), 7.60–7.66 (m, 1H), 8.12–8.14 (m, 2H); 13C NMR (CDCl3) d 52.6,
114.3, 128.6, 128.8, 130.3, 133.8, 144.8, 162.0, 164.7; EIMS (%) 206 (1)
[Mþ], 175 (2), 105 (100), 77 (44).
Methyl 2-(2-Chlorobenzoyloxy)propenoate (5b)
Yellow oil; yield 40%; IR (CH2Cl2) 1737, 1649 cmꢁ1; 1H NMR (CDCl3) d
3.84 (s, 3H), 5.65 (d, J ¼ 1.8 Hz, 1H), 6.18 (d, J ¼ 1.8 Hz, 1H), 7.34–7.40
(m, 1H), 7.48–7.52 (m, 2H), 8.02–8.05 (m, 1H); 13C NMR (CDCl3) d 52.7,
114.6, 126.7, 128.1, 131.3, 132.2, 133.5, 134.7, 144.5, 161.8, 163.1; EIMS
(%) 240 (1) [Mþ], 209 (2), 211 (1), 141 (33), 139 (100), 113 (9), 111 (26), 75
(19). Anal. calcd. for C11H9ClO4: C, 54.90; H, 3.77. Found: C, 54.68; H,
3.57.
Methyl 2-(4-Chlorobenzoyloxy)propenoate (5c)[1a]
1
White solid; yield 47%; mp 38–39 ꢂC; IR (KBr) 1736, 1650 cmꢁ1; H
NMR (CDCl3) d 3.82 (s, 3H), 5.63 (d, J ¼ 1.8 Hz, 1H), 6.18 (d, J ¼ 1.8 Hz,
1H), 7.45–7.48 (m, 2H), 8.05–8.08 (m, 2H); 13C NMR (CDCl3) d 52.7,
114.5, 127.0, 129.0, 131.6, 140.4, 144.6, 161.8, 163.8; EIMS (%) 240 (1)
[Mþ], 209 (3), 211 (1), 141 (44), 139 (100), 113 (13), 111 (41), 75 (26).
Methyl 2-(4-Fluorobenzoyloxy)propenoate (5d)
1
White solid; yield 75%; mp 53–54 ꢂC; IR (KBr) 1739, 1650 cmꢁ1; H
NMR (CDCl3) d 3.82 (s, 3H), 5.63 (d, J ¼ 1.8 Hz, 1H), 6.18 (d, J ¼ 1.8 Hz,
1H), 7.13–7.20 (m, 2H), 8.13–8.17 (m, 2H); 13C NMR (CDCl3)
d 52.7, 114.4, 115.8 (d, J ¼ 22.0 Hz), 124.8, 132.9 (d, J ¼ 9.8 Hz), 144.6,

3404
E.-G. Han and K.-J. Lee
161.9, 163.7, 166.3 (d, J ¼ 255 Hz); EIMS (%) 224 (1) [Mþ], 193 (2), 123
(100), 95 (33), 75 (13). Anal. calcd. for C11H9FO4: C, 58.93; H, 4.05.
Found: C, 58.72; H, 4.26.
Methyl 2-(4-Nitrobenzoyloxy)propenoate (5e)[1a]
White solid; yield 58%; mp 79–81 ꢂC; IR (KBr) 1745, 1726, 1647, 1526,
1
1325 cmꢁ1; H NMR (CDCl3) d 3.84 (s, 3H), 5.69 (d, J ¼ 1.8 Hz, 1H),
6.23 (d, J ¼ 1.8 Hz, 1H), 8.29–8.36 (m, 4 H); 13C NMR (CDCl3) d 52.8,
114.9, 123.7, 131.4, 134.0, 144.4, 151.0, 161.5, 162.8; EIMS (%) 251 (1)
[Mþ], 220 (3), 150 (100), 120 (7), 104 (30), 92 (13), 76 (22).
Methyl 2-(4-Methylbenzoyloxy)propenoate (5f)
Yellow oil; yield 43%; IR (CH2Cl2) 1734, 1650 cmꢁ1; 1H NMR (CDCl3) d
2.43 (s, 3H), 3.81 (s, 3H), 5.60 (d, J ¼ 1.8 Hz, 1H), 6.15 (d, J ¼ 1.8 Hz,
1H), 7.27–7.30 (m, 2H), 8.00–8.03 (m, 2H); 13C NMR (CDCl3) d 21.7,
52.6, 114.2, 125.8, 129.3, 130.3, 144.7, 144.8, 162.1, 164.7; EIMS (%)
220 (1) [Mþ], 189 (2), 119 (100), 91 (37), 65 (15). Anal. calcd. for
C12H12O4: C, 65.45; H, 5.49. Found: C, 65.28; H, 5.25.
ACKNOWLEDGMENTS
This work was supported by a grant from the University Information
Technology Research Center Project, Republic of Korea.
REFERENCES
ꢀ
´
1. (a) Herrera, R.; Jimenez-Vazquez, H. A.; Modelli, A.; Jones, D.; So¨derberg,
B. C.; Tamariz, J. Synthesis of new captodative alkenes: Alkyl 2-aroyloxy
acrylates—Structure and reactivity in Diels–Alder cycloadditions. Eur. J.
´
Org. Chem. 2001, 4657–4669; (b) Domingo, L. R.; Chamorro, E.; Perez, P.
Understanding the reactivity of captodative ethylenes in polar cycloaddition
reactions: A theoretical study. J. Org. Chem. 2008, 73, 4615–4624.
2. (a) Tanaka, H.; Yoshida, S. Kinetic study of radical homopolymerization
of captodative substituted methyl a-(acyloxy)acrylates. Macromolecules
1995, 28, 8117–8121; (b) Hongo, T.; Yoshida, S.; Yamada, T.; Tanaka, H.
Radical copolymerization of methyl a-acyloxyacrylates with some vinyl
monomers. Polym. Int. 1999, 48, 505–508.

Triphenylphosphine-Mediated Synthesis
3405
3. Tanaka, H.; Sakai, I.; Sasai, K.; Sato, T.; Ota, T. Long-range interaction
between radical center and b-hydrogens of penultimate monomer unit in
ESR of model propagating acrylate radicals. J. Polym. Sci., Part C: Polym.
Lett. 1988, 26, 11–15.
4. Baylis, A. B.; Hillman, M. E. D. German Patent 2155113, 1972; Chem. Abstr.
1972, 77, 34174.
5. For reviews of the Baylis–Hillman reaction, see (a) Drewes, S. E.; Roos, G.
H. P. Synthetic potential of the tertiary-amine-catalyzed reaction of activated
vinyl carbanions with aldehydes. Tetrahedron 1988, 44, 4653–4670; (b)
Basavaiah, D.; Rao, P. D.; Hyma, R. S. The Baylis–Hillman reaction: A
novel carbon–carbon bond-forming reaction. Tetrahedron 1996, 52, 8001–
8062; (c) Ciganek, E. The catalyzed a-hydroxyalkylation and a-aminoalkyla-
tion of activated olefins (the Morita–Baylis–Hillman reaction). Org. React.
1997, 51, 201–350; (d) Langer, P. New strategies for the development of an
asymmetric version of the Baylis–Hillman reaction. Angew. Chem. Int. Ed.
2000, 39, 3049–3052; (e) Kim, J. N.; Lee, K. Y. Synthesis of cyclic compounds
from the Baylis–Hillman adducts. Curr. Org. Chem. 2002, 6, 627–645; (f)
Basavaiah, D.; Rao, A. J.; Satyanarayana, T. Recent advances in the
Baylis–Hillman reaction and applications. Chem. Rev. 2003, 103, 811–891;
(g) Kataoka, T.; Kinoshita, H. Chalcogenide–Lewis acid–mediated tandem
Michael aldol reaction––An alternative to the Morita–Baylis–Hillman reac-
tion and a new development. Eur. J. Org. Chem. 2005, 45–58; (h) Basavaiah,
D.; Rao, K. V.; Reddy, R. J. The Baylis–Hillman reaction: A novel source of
attraction, opportunities, and challenges in synthetic chemistry. Chem. Soc.
Rev., 2007, 36, 1581–1588; (i) Singh, V.; Batra, S. Advances in the Baylis–
Hillman reaction-assisted synthesis of cyclic frameworks. Tetrahedron 2008,
64, 4511–4574.
´
6. Foucaud, A.; Le Rouille, E. One-pot preparation of 1-acyl-1-methoxycarbo-
nyloxiranes and 1-acyl-1-cyanooxiranes from methyl 3-hydroxy-2-methyle-
nealkanoates or 3-aryl-3-hydroxy-2-methylenepropanenitriles. Synthesis
1990, 787–789.
7. Wittig, G.; Haag, W. Triphenylphosphinemethylenes as olefin-forming
reagents, II. Chem. Ber. 1955, 88, 1654–1666.
8. (a) Mal, D.; Bandyopadhyay, M.; Ghorai, S. K.; Datta, K. Total synthesis of
coriandrin and 7-demethylcoriandrin via a new synthesis of isocoumarins.
Tetrahedron Lett. 2000, 41, 3677–3680; (b) Houwen-Claassen, A. A. M.;
Klunder, A. J. H.; Zwanenburg, B. Synthesis of cyclopentadienone epoxides
from 10-oxatricyclodecadienones. Tetrahedron 1989, 45, 7134–7148.
9. Koelsch, C. F.; Le Claire, C. D. The action of acids on 2,3-diphenyl-2,3-
epoxyindanone. J. Am. Chem. Soc. 1943, 65, 754–755.
10. (a) Cai, J.; Zhou, Z.; Zhao, G.; Tang, C. Dramatic rate acceleration of
the Baylis–Hillman reaction in homogeneous medium in the presence of
water. Org. Lett. 2002, 4, 4723–4725; (b) Basavaiah, D.; Bhavani, A. K.
D.; Pandiaraju, S.; Sarma, P. K. S. Baylis–Hillman reaction: Magnesium
bromide as a stereoselective reagent for the synthesis of [E]- and [Z]-allyl
bromides. Synlett 1995, 243–244.