A facile one-pot synthesis of α-iodo-α,β-unsaturated esters

Article abstract of DOI:10.1081/SCC-120030760

Aldehydes reacted with (ethoxycarbonyliodomethyl)triphenylphosphonium iodide, tetrabutylammonium bromide, and potassium carbonate in methanol at 40°C to give α-iodo-α,β-unsaturated esters in good to excellent yield.

Full text of DOI:10.1081/SCC-120030760

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A Facile One‐Pot Synthesis of α‐Iodo‐α,β‐unsaturated
Esters
Xingguo Zhang a , Ping Zhong a & Fan Chen a
a The School of Chemistry and Material Science , Wenzhou Normal College , Zhejiang,
Wenzhou, 325027, P.R. China
Published online: 16 Aug 2006.
To cite this article: Xingguo Zhang , Ping Zhong & Fan Chen (2004) A Facile One‐Pot Synthesis of α‐Iodo‐α,β‐unsaturated
Esters, Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
34:9, 1729-1736, DOI: 10.1081/SCC-120030760
To link to this article: http://dx.doi.org/10.1081/SCC-120030760
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SYNTHETIC COMMUNICATIONSw
Vol. 34, No. 9, pp. 1729–1736, 2004
A Facile One-Pot Synthesis of a-Iodo-
a,b-unsaturated Esters
*
Xingguo Zhang, Ping Zhong, and Fan Chen
The School of Chemistry and Material Science, Wenzhou Normal
College, Zhejiang, Wenzhou, P.R. China
ABSTRACT
Aldehydes reacted with (ethoxycarbonyliodomethyl)triphenylphosphonium
iodide, tetrabutylammonium bromide, and potassium carbonate in methanol
at 408C to give a-iodo-a,b-unsaturated esters in good to excellent yield.
Key Words: One-pot synthesis; a-Iodo-a,b-unsaturated esters; 1H NMR;
Iodoylides.
INTRODUCTION
a-Halo-a,b-unsaturated esters are useful intermediates in organic
synthesis. They are usually prepared by the Wittig reaction of aldehydes with
*
Correspondence: Xingguo Zhang, The School of Chemistry and Material Science,
Wenzhou Normal College, Zhejiang, Wenzhou 325027, P.R. China; E-mail:
zxg7599@sohu.com.
1729
DOI: 10.1081/SCC-120030760
0039-7911 (Print); 1532-2432 (Online)
www.dekker.com
Copyright # 2004 by Marcel Dekker, Inc.

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Zhang, Zhong, and Chen
haloylides[1,2] and the condensation of aldehydes with halophosphonates in
presence of base.[3] It is well-known that a-iodo-a,b-unsaturated esters are
easily deprived of hydrogen iodide under basic or high temperature conditions to
turn into the corresponding propiolates. In addition, it is difficult to obtain
iodoylides. So, the above methods are not suitable for preparation of a-iodo-
a,b-unsaturated esters. Recently, Huang[4] reported a method to prepare
a-iodo-a,b-unsaturated esters via arsonium salts, but the reaction time was
too long: 14–33hr. Kayser[5] also reported a procedure to prepare them through
the reaction of carboethoxymethylenetriphenylphosphorane, potassium carbon-
ate, N-iodosuccinimide, and aldehyde, but this reaction was also carried out
in low temperature for a long time. Herein, we report our method to prepare
a-iodo-a,b-unsaturated esters by modified Chenault’s procedure[6] (Sch. 1).
A
suspension of (ethoxycabonyliodomethyl)triphenylphosphonium
iodide 2, tetrabutylammonium bromide, and aldehyde in methanol was stirred
at 408C, 1.0 equiv. of potassium carbonate was added in three portions (a
portion per 2 hr) to the mixture 4 hr, and the reaction was stirred for 2 hr.
We were delighted to found that (Z)-a-iodo-a,b-unsaturated esters were the
predominant product in high yields. The results were summarized in Table 1.
It is noteworthy that propiolic ester could be found in the product if
addition of potassium carbonate was too fast and if the quantity of potassium
carbonate was more than 1.0 equiv. The presence of tetrabutylammonium
bromide was essential to this reaction. If tetrabutylammonium bromide was
not added, the yield would had a obvious decline, especially when R was
not aryl groups. Therefore, a-iodo-a,b-unsaturated esters could be easily
prepared in good yields by our facile one-pot reaction.
a-Iodo-a,b-unsaturated esters 3 have recently emerged as valuable
reagents for organic synthesis. For example, the synthesis of a-trifluoro-
methyl-a,b-unsaturated ester 4 was based on the trifluoromethylation of
Scheme 1.

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Synthesis of a-Iodo-a,b-unsaturated Esters
1731

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Zhang, Zhong, and Chen

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Synthesis of a-Iodo-a,b-unsaturated Esters
1733
a-iodo-a,b-unsaturated esters 3c. Treatment of a 88 : 12 mixture of Z- and
E-3c with FSO2CF2CO2Me and CuI in DMF/HMPA at 708C gave a 88 : 12
mixture of Z- and E-4 in 89 %[7] (Sch. 2).
EXPERIMENTAL
1H NMR was determined with a Bruker Avance 300 MHz spectrometer
using tetramethylsilane as the internal standard. 19F NMR spectra was
obtained on a 300 MHz spectrometer using trifluoroacetic acid as external
standard, downfield shifts being designated as negative. All chemical shift
(d) were expressed in parts per million, and coupling constants (J) were
given in Hertz. Mass spectra were obtained using EI at 70 eV. IR spectra
were recorded on a Bruker Equinox 55 spectrometer.
General Procedure for the Synthesis of 3a–k
A
suspension of (ethoxycarbonyliodomethyl)triphenylphosphonium
iodide 2 (6.02 g, 10 mmol), 5% equivalent of tetrabutylammonium bromide
(161 mg, 0.5 mmol), and aldehyde (10 mmol) in methanol (40 mL) was stirred
at 408C, 1.0 equiv. of potassium carbonate (690 mg, 5 mmol) was added in
three portions (230 mg per 2 hr) to the mixture in 4 hr. The color of the mixture
turned to dark brown and the suspension dissolved completely during the
addition. After the finish of addition, the reaction was stirred for 2 hr. After
removal of methanol, the residue was purified by column chromatography
on silica gel with 20 : 1 petroleum ether (60–908C) and ethyl acetate to give
a-iodo-a,b-unsaturated esters 3.
(Z)-3a. Oil. 1H NMR (300 MHz, CDCl3): d ¼ 8.20 (s, 1H), 7.72
(d, J ¼ 8.4 Hz, 2H), 7.38 (d, J ¼ 8.4 Hz, 2H), 4.35 (q, J ¼ 7.1 Hz, 2H), 1.40
(t, J ¼ 7.1 Hz, 3H); m/z (EI): 337 (Mþ þ 1, 21), 336 (Mþ, 52), 209 (43),
181 (100), 136 (89); IR (nmax, thin film): 2982, 1712, 1595, 1490, 1249 cm21
.
Scheme 2.

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Zhang, Zhong, and Chen
(Z )-3b. Oil. 1H NMR (300 MHz, CDCl3): d ¼ 8.25 (s, 1H), 7.74
(d, J ¼ 7.9 Hz, 2H), 7.23 (d, J ¼ 7.9 Hz, 2H), 4.35(q, J ¼ 7.1 Hz, 2H), 2.38
(s, 3H), 1.35(t, J ¼ 7.1 Hz, 3H); m/z (EI): 316 (Mþ, 71), 189 (48), 161 (100),
115 (96); IR (nmax, thin film): 2981, 1716, 1599, 1511, 1445, 1180cm21
.
(Z )-3c. Oil. 1H NMR (300 MHz, CDCl3): d ¼ 8.25 (s, 1H), 7.88
(d, J ¼ 8.1 Hz, 2H), 6.95 (d, J ¼ 8.1 Hz, 2H), 4.35 (q, J ¼ 7.1 Hz, 2H), 3.88
(s, 3H), 1.40 (t, J ¼ 7.1 Hz, 3H); m/z (EI): 333 (Mþ þ 1, 47), 332 (Mþ,
100), 287 (46), 205 (41), 127 (2); IR (nmax, thin film): 2981, 1712, 1606,
1511, 1254, 1176 cm21
.
(Z )-3d. Solid: m.p. 98–1008C. 1H NMR (300 MHz, CDCl3): d ¼ 8.30–
8.28 (m, 3H), 7.85 (m, 2H), 4.38 (q, J ¼ 7.1 Hz, 2H), 1.42 (t, J ¼ 7.1 Hz, 3H);
m/z (EI): 348 (Mþ þ 1, 56), 347 (Mþ, 64), 302 (20), 220 (71), 192 (100); IR
(nmax, KBr): 2987, 1716, 1640, 1520, 1347, 1251 cm21
.
1
(Z )-3e. Oil. H NMR (300 MHz, CDCl3): d ¼ 7.70 (s, 1H), 7.60–7.45
(m, 2H), 7.25 (m, 1H), 6.48 (d, J ¼ 15.7 Hz, 1H), 4.28 (q, J ¼ 7.1 Hz, 2H),
1.35 (t, J ¼ 7.1 Hz, 3H); m/z (EI): 382/380 (Mþ, 24), 337/335 (9), 211
(92), 209 (100), 127 (4); IR (nmax, thin film): 2979, 1711, 1640, 1312, 1179,
1035 cm21
.
(Z )-3f. Oil. 1H NMR (300 MHz, CDCl3): d ¼ 7.78 (d, J ¼ 16.4 Hz, 1H),
7.26 (m, 1H), 7.15 (m, 1H), 6.58 (d, J ¼ 16.4 Hz, 1H), 4.32 (q, J ¼ 7.1 Hz,
2H), 1.38 (t, J ¼ 7.1 Hz, 3H); m/z (EI): 373 (Mþ þ 2, 2), 371 (Mþ, 3), 244
(6), 181 (100), 127 (14); IR (nmax, thin film): 2984, 1722, 1429, 1305, 1189,
1035 cm21
.
(Z )-3g. Oil. 1H NMR (300 MHz, CDCl3): d ¼ 8.28 (s, 1H), 7.80 (m, 2H),
7.42 (m, 2H), 7.32 (m, 1H), 4.35 (q, J ¼ 7.1 Hz, 2H), 1.40 (t, J ¼ 7.1 Hz, 3H);
m/z (EI): 303 (Mþ þ 1, 71), 302 (Mþ, 100), 257 (45), 175 (91), 127 (4); IR
(nmax, thin film): 2982, 1717, 1599, 1233, 1035 cm21
.
1
(Z)-3h. Oil. H NMR (300 MHz, CDCl3): d ¼ 7.80 (d, J ¼ 9.2 Hz, 1H),
7.68 (m, 2H), 7.40 (m, 3H), 7.15 (d, 2H), 4.35 (q, J ¼ 7.1 Hz, 2H), 1.38
(t, J ¼ 7.1 Hz, 3H); m/z (EI): 329 (Mþ þ 1, 13), 328 (Mþ, 40), 202 (14),
173 (10), 129 (100), 127 (60); IR (nmax, thin film): 2982, 1708, 1613, 1258,
1226, 1149 cm21
.
1
(Z )-3i. Oil. H NMR (300 MHz, CDCl3): d ¼ 7.38 (d, J ¼ 8.1 Hz, 1H),
4.85 (m, 1H), 4.28 (m, 3H), 3.68 (m, 1H), 1.45–1.25 (m, 9H); m/z (EI):
327 (Mþ þ 1, 21), 311 (67), 269 (100), 127 (5); IR (nmax, thin film): 2987,
1720, 1372, 1241, 1062, 1031 cm21
.
(Z )-3j. Oil. 1H NMR (300 MHz, CDCl3): d ¼ 8.30 (s, 1H), 7.63 (d, 2H),
6.62 (m, 1H), 4.35 (q, J ¼ 7.1 Hz, 2H), 1.38 (t, J ¼ 7.1 Hz, 3H); m/z (EI): 392
(Mþ, 78), 165 (69), 137 (100), 92 (63); IR (nmax, thin film): 2982, 1712, 1605,
1472, 1235, 1038 cm21
.
(Z )-3k. Oil. 1H NMR (300 MHz, CDCl3): d ¼ 7.55 (m, 1H), 6.62
(m, 1H), 6.40 (m, 1H), 4.28 (q, J ¼ 7.1 Hz, 2H), 1.90 (d, J ¼ 5.1 Hz, 3H),

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Synthesis of a-Iodo-a,b-unsaturated Esters
1735
1.30 (t, J ¼ 7.1 Hz, 3H); m/z (EI): 266 (Mþ, 100), 238 (35), 223 (81), 111
(69), 66 (88); IR (nmax, thin film): 2981, 1711, 1633, 1577, 1443, 1224 cm21
The Synthesis of a-Trifluoromethyl-a,b-unsaturated Ester 4
.
A solution of FSO2CF2CO2CH3 (0.5 mL, 4 mmol) in DMF(10 mmol) was
added dropwise over a period of 3 hr to a mixture of ester 3c (2 mmol), CuI
(96 mg, 0.5 mmol), and HMPA (1 mL) in DMF (15 mL) at 658C. The reaction
was stirred at 658C for 10 hr before being cooled to room temperature.
Saturated aqueous NH4Cl (30 mL) was added and the mixture was extracted
with ether. The extracts were washed with brine, and dried over Na2SO4.
The solvent was removed in vacuo. Purification of the residue by column
chromatography on silica gel and elution with 25 : 1 hexane and ethyl acetate
gave compounds 4.
(Z)-4. Oil. 1H NMR (300 MHz, CDCl3): d ¼ 7.99 (s, 1H), 7.41
(d, J ¼ 9.5 Hz, 2H), 6.91 (m, 2H), 4.34 (m, 2H), 3.83 (s, 3H), 1.37
(t, J ¼ 7.1 Hz, 3H), 19F NMR (300 MHz, CDCl3): d ¼ 220.6 (s); m/z (EI):
275 (Mþ þ 1, 18), 274 (Mþ, 100), 205 (8), 69 (12); IR (nmax, thin film):
2982, 1726, 1606, 1514, 1265, 1178 cm21
.
ACKNOWLEDGMENT
Project 20272043 was supported by The National Nature Science
Foundation of China. This work was also supported by The National Nature
Science Foundation of Zhejiang Province (201015).
REFERENCES
1. Denney, D.B.; Ross, S.T. The preparation and reaction of some halo-
phosphoranes. J. Org. Chem. 1962, 27 (3), 998–1000.
2. Speziale, A.J.; Ratts, K.W. Reaction of phosphorus compounds
V. Resonance-stabilized a-halomethylenephosphorunes. J. Org. Chem.
1963, 28 (2), 465–469.
3. Zhang, X.G.; Qing, F.L.; Yang, Y.; Yu, J.; Fu, X.K. A new route to
a-trifluoromethyl-a,b-unsaturated esters. Tetrahedron Lett. 2000, 41 (16),
2953–2956.
4. Huang, Y.; Shi, L.; Li, S.; Huang, R. An efficient one pot synthesis of
a-iodo-a,b-unsaturated esters, ketones and nitriles via arsonium salts.
Synth. Commun. 1989, 19 (15), 2639–2646.

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5. Kayser, M.M.; Zhu, J.; Hooper, D.L. Stabilized haloylides: synthesis and
reactivity. Can. J. Chem. 1997, 75 (10), 1315–1321.
6. Chenault, J.; Dupin, J.E. (Ethoxycarbonyliodomethyl)triphenylphosphonium
iodide: a convenient reagent for the direct synthesis of b-substituted
propiolic acids via the corresponding esters. Synthesis 1987 (5), 498–499.
7. Zhang, X.G.; Qing, F.L.; Peng, Y. The stereospecific trifluoromethylation
of a-iodo-a,b-unsaturated esters: a novel synthesis of (Z)-a-trifluoro-
methyl-a,b-unsaturated esters. J. Fluorine Chem. 2001, 108 (1), 79–82.
Received in Japan October 6, 2003

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