Facile synthesis of β-organotellurobutenolides via electrophilic tellurolactonization of α-allenoic acids

Article abstract of DOI:10.1021/jo050564r

We report a convenient and highly efficient method for the synthesis of β-organotellurobutenolides by the aryltellurenyl halides-induced electrophilic tellurolactonization of α-allenoic acids under mild conditions. The resulting β-organotellurobutenolides

Full text of DOI:10.1021/jo050564r

SCHEME 1
Facile Synthesis of
â-Organotellurobutenolides via
Electrophilic Tellurolactonization of
r-Allenoic Acids
Qing Xu,† Xian Huang,*,†,‡ and Jingqi Yuan†
Department of Chemistry, Zhejiang University (Campus
Xixi), Hangzhou 310028, P. R. China, and State Key
Laboratory of Organometallic Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, P. R. China
Recently, organotellurides,3 especially the vinyltellu-
rides,4 have been regarded as an important intermediate
in organic synthesis for their facile transformations to
regio- and stereocontrolled substituted alkenes by reac-
tions with organometallic reagents.5 On the other hand,
tellurium reagents-induced tellurocyclofunctionalization
of unsaturated compounds, which may lead to hetero-
cycles, has not been studied in detail (Scheme 1, Y )
Te).3b,6 Unlike similar seleno- and thiocyclofunctional-
izations that have been extensively studied and applied
in heterocycle synthesis (Scheme 1, Y ) S, Se),2,7 telluro-
cyclofunctionalization was reported only occasionally
huangx@mail.hz.zj.cn
Received March 20, 2005
(3) For reviews, see: (a) Comasseto, J. V.; Ling, L. W.; Petragnani,
N.; Stefani, H. A. Synthesis 1997, 373. (b) Petragnani, N.; Stefani, H.
A. Tetrahedron 2005, 61, 1613. For recent reports, see: (c) Braga, A.
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V. B.; Pereira, M. A. Tetrahedron Lett. 2001, 42, 1595. (h) Zhao, C.-Q.;
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A. L.; Vargas, F.; Zeni, G.; Silveira, C. C.; Andrade, L. H. Tetrahedron
Lett. 2002, 43, 4399. (k) Silveira, C. C.; Braga, A. L.; Guerra, R. B.
Tetrahedron Lett. 2002, 43, 3395. (l) Gil, J. M.; Oh, D. Y. J. Org. Chem.
1999, 64, 2950.
We report a convenient and highly efficient method for the
synthesis of â-organotellurobutenolides by the aryltellurenyl
halides-induced electrophilic tellurolactonization of R-alle-
noic acids under mild conditions. The resulting â-organo-
tellurobutenolides can be utilized as precursors for versatile
butenolide derivatives through a substitution reaction with
organocuprate reagent or Pd/Cu(I)-catalyzed cross-coupling
with terminal alkyne.
(4) (a) Nishibayashi, Y.; Cho, C. S.; Uemura, S. J. Organomet. Chem.
1996, 507, 197. (b) Ohe, K.; Takahashi, H.; Uemura, S.; Sugita, N. J.
Org. Chem. 1987, 52, 4859. (c) Zeni, G.; Nogueira, C. W.; Pena, J. M.;
Pilissao, C.; Menezes, P. H.; Braga, A. L.; Rocha, J. B. T. Synlett. 2003,
579. (d) Braga, A. L.; Andrade, L. H.; Silveira, C. C.; Moro, A. V.; Zeni,
G. Tetrahedron Lett. 2001, 42, 8563. (e) Zeni, G.; Alves, D.; Braga, A.
L.; Stefani, H. A.; Nogueira, C. W. Tetrahedron Lett. 2004, 45, 4823.
(f) Raminelli, C.; Gargalaka, J., Jr.; Silveira, C. C.; Comasseto, J. V.
Tetrahedron Lett. 2004, 45, 4927.
(5) (a) Dabdoub, M. J.; Begnini, M. L.; Guerrero, P. G., Jr. Tetra-
hedron 1998, 54, 2371. (b) Dabdoub, M. J.; Justino, A.; Guerrero, P.
G., Jr. Organometallics 1998, 17, 1901. (c) Dabdoub, M. J.; Baroni C.
M. J. Org. Chem. 2000, 65, 54. (d) Dabdoub, M. J.; Begnini, M. L.;
Guerrero, P. G., Jr.; Baroni, C. M. J. Org. Chem. 2000, 65, 61.
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C. A. Tetrahedron Lett. 1987, 28, 5611. (b) Comasseto, J. V.; Grazini,
M. V. A. Synth. Commun. 1992, 22, 949. (c) Comasseto, J. V.; Ferraz,
H. M. C.; Brandt, C. A.; Gaeta, K. K. Tetrahedron Lett. 1989, 30, 1209.
(d) Ferraz, H. M. C.; Sano, M. K.; Scafo, A. C. Synlett 1999, 567. (e)
Hu, N. X.; Aso, Y.; Otsuo, T.; Ogura, F. J. Org. Chem. 1989, 54, 4391.
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(g) Bergman, J.; Siden, J.; Maartmann-Moe, K. Tetrahedron 1984, 40,
1607. (h) Engman, L. Organometallics 1989, 8, 1997.
(7) For reviews, see: (a) Petragnani, N.; Stefani, H. A.; Valduga, C.
J. Tetrahedron 2001, 57, 1411. (b) Beaulieu, P. L.; Deziel, R. In
Organoselenium Chemistry; Back, T. G., Ed.; Oxford University
Press: Oxford, UK, 1999; p 35. (c) Nicolaou, K. C. Tetrahedron 1981,
37, 4097. For recent reports, see: (d) Khokhar, S. S.; Wirth, T. Angew.
Chem., Int. Ed. 2004, 43, 631. (e) Ma, S.; Pan, F.; Hao, X.; Huang, X.
Synlett 2004, 85. (f) Brimble, M. A.; Pavia, G. S.; Stevenson, R. J.
Tetrahedron Lett. 2002, 43, 1735. (g) Ternon, M.; Outurquin, F.;
Paulmier, C. Tetrahedron 2001, 57, 10259. (h) Pannecoucke, X.;
Outurquin, F.; Paulmier, C. Eur. J. Org. Chem. 2002, 995. (i)
Outurquin, F.; Pannecoucke, X.; Berthe, B.; Paulmier, C. Eur. J. Org.
Chem. 2002, 1007. (j) Gill, G. B.; Idris, M. S. H. Tetrahedron Lett. 1985,
26, 4811.
Ring structures abound in naturally occurring and
biologically active molecules, and developing methods to
construct those ring systems has been of substantial
interest to synthetic organic chemists. Among the cy-
clization methods reported to date, electrophilic cycliza-
tion of alkenes or alkynes with a suitably positioned
intramolecular nucleophile represents one of the most
efficient and powerful means to construct ring systems
because various functional auxiliaries can be easily
introduced into the molecule, which allows further trans-
formations for complex natural product synthesis.1,2
† Zhejiang University.
‡ Chinese Academy of Sciences.
(1) For reviews, see: (a) Dowle, M. D.; Davies, D. I. Chem. Soc. Rev.
1979, 8, 171. (b) Harding, K. E.; Tiner, T. H. In Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, UK, 1991;
Vol. 4, p 363. For recent reports, see: (c) Curini, M.; Epifano, F.;
Marcotullio, M. C.; Montanari, F. Synlett 2004, 368. (d) Knight, D.
W.; Redfern, A. L.; Gilmore, J. J. Chem. Soc., Perkin Trans. 1 2002,
622. (e) Cherry, K.; Thibonnet, J.; Duchene, A.; Parrain, J.-L.; Abarbri,
M. Tetrahedron Lett. 2004, 45, 2063. (f) Amjad, M.; Knight, D. W.
Tetrahedron Lett. 2004, 45, 539. (g) Yao, T.; Larock, R. C. J. Org. Chem.
2005, 70, 1432. (h) Peng, A.-Y.; Ding, Y.-X. Org. Lett. 2004, 6, 1119.
(2) For a review, see: (a) Frederickson, M.; Grigg, R. Org. Prep.
Proced. Int. 1997, 29, 63. For recent reports, see: (b) Yao, T.; Larock,
R. C. J. Org. Chem. 2003, 68, 5936. (c) Yue, D.; Ca, N. D.; Larock, R.
C. Org. Lett. 2004, 6, 1581. (d) Zhang, X.; Campo, M. A.; Yao, T.;
Larock, R. C. Org. Lett. 2005, 7, 763. (e) Huang, Q.; Hunter, J. A.;
Larock, R. C. Org. Lett. 2001, 3, 2973.
10.1021/jo050564r CCC: $30.25 © 2005 American Chemical Society
Published on Web 07/21/2005
6948
J. Org. Chem. 2005, 70, 6948-6951

TABLE 1. Electrophilic Tellurolactonization of
TABLE 2. Synthesis of Substituted
r-Allenoic Acid 1a with PhTeX
â-Organotellurobutenolides 2
prod- yield,a
uct
entry X (equiv) base solvent temp, °C
time
24 h
24 h
24 h
24 h
24 h
23 h
9 h
24 h
25 min
5 min
5 min
yield,a %
entry
1
1: R1, R2, R3
Ar
time
%
1
2
I (1.2)
I (2.0)
I (2.0)
Et3N THF
Et3N MeCN
MeCN
0
trace
32
1a: o-ClC6H4, H,
PhCH2
1b: H, H, PhCH2
1c: n-C4H9, H, H
1c: n-C4H9, H, H
Ph
5 min
2a
93
0
3
0
45
2
3
Ph
Ph
30 min 2b
10 min 2c
79
84
81
92
85
94
94
91
4
Br (1.2) Et3N THF
0
38
5
Br (1.2)
Br (2.0)
Br (2.0)
Br (2.0)
Cl (2.0)
Cl (2.0)
Cl (1.1)
THF
THF
MeCN
MeCN
MeCN
MeCN
MeCN
0
44
4
R-naphthyl 30 min 2d
6
0
92b
93b
76
5
1d: n-C4H9, H, PhCH2 Ph
10 min 2e
10 min 2f
6
1e: n-C8H17, H, H
1f: Ph, H, Allyl
1g: Ph, H, PhCH2
1h: o-ClC6H4, H, H
1i: H, H, H
Ph
Ph
Ph
Ph
Ph
Ph
7
0
7
5 min
5 min
5 min
24 h
2g
2h
2i
8
rt
0
93b
94b
93b
8
9
9
10
11
rt
rt
b
10
11
-
1j: H, H, Allyl
24 h
traceb
a Isolated yields based on 1a. b Complete conversion of 1a was
observed by TLC analysis.
a Isolated yields based on 1. b 2.0 equiv of PhTeCl was added
at room temperature. Complex reaction occurred and a mixture
of multiple unidentified products was obtained.
since its first example for tellurolactone synthesis in
1960.8 In addition, the most frequently employed tel-
lurium reagents are aryltellurium trihalides,6a-d,8 tel-
lurium tetrachloride,6h,8b or their equivalents,6e-g which
usually requires the reduction of the cyclization products
to tellurides prior to further transformations. Further-
more, only a few utilities of the resulting tellurides have
been developed and are mainly confined to detelluration
by tributyltin hydride.6c-e
reagent (1.2 equiv) was carried out in the presence of
triethylamine (1 equiv) in THF, only a trace amount of a
new product was observed, which was proved to be the
cyclization product 2a by spectra analysis (entry 1). While
better yields were obtained by using 2 equiv of PhTeI
and/or performing the reaction in the absence of an
external base in acetonitrile (entries 2 and 3), it was still
far from complete. It was observed that the reactions with
PhTeBr as the tellurenylating reagent allowed higher
conversion compared with those of PhTeI under similar
conditions (entries 4 and 5). A complete conversion was
achieved with 2 equiv of PhTeBr in THF at 0 °C in 23 h
to give 2a in 93% isolated yield (entry 6), and a similar
yield could be obtained in a shortened reaction time of 9
h when acetonitrile was used as the solvent instead of
THF (entry 7). However, attempts to shorten the reaction
time by executing the reaction at elevated temperature
failed even in prolonged reaction time affording lower
product yield than at 0 °C may be due to the limited
thermal stability of PhTeBr at room temperature (entry
8). On the other hand, we were pleased to find that
PhTeCl13 showed much higher reactivity than its bromide
and iodide analogues. With 2 equiv of PhTeCl as the
tellurenylating reagent, the reaction was complete in 25
min in acetonitrile at 0 °C (entry 9). Unlike PhTeBr that
is unstable above 0 °C, PhTeCl is thermally stable and
the reaction could be carried out at room temperature to
afford the product in high yield with complete conversion
in only 5 min (entry 10). Furthermore, the amount of
PhTeCl could be reduced to 1.1 equiv without any
decrease in reactivity (entry 11).
In our ongoing efforts to develop organotellurides9 and
heterocycle compounds,10 recently we achieved an ef-
ficient method for the preparation of â-iodovinyltellurides
through the addition of aryltellurenyl iodide to alkynes.9a
In this regard we deduced that the simple aryltellurenyl
halides could also serve as the tellurenylating reagents
in tellurocyclofunctionalization. Besides, it is well-known
that allenes are interesting compounds with particular
properties due to the presence of the unique cumulated
diene structural unit.11 Therefore, incorporating the
allenyl structure with a readily available nucleophile, we
commenced our study on the reaction of R-allenoic acids
112 and aryltellurenyl halides. Herein reported are our
preliminary findings on the ArTeX-induced electrophilic
tellurolactonization of R-allenoic acids (Table 1).
When the reaction of R-allenoic acid 1a (R1 ) o-ClC6H4,
R2 ) H, R3 ) PhCH2) and PhTeI9a as the tellurenylating
(8) (a) Moura Campos, M.; Petragnani, N. Chem. Ber. 1960, 93, 317.
(b) Moura Campos, M.; Petragnani, N. Tetrahedron 1962, 18, 521.
(9) (a) Huang, X.; Liang, C. G.; Xu, Q.; He, Q. W. J. Org. Chem.
2001, 66, 74. (b) Xu, Q.; Huang, X.; Ni, J. Tetrahedron Lett. 2004, 45,
2981. (c) Wu, Z.; Huang, X. Synlett 2005, 526. (d) Huang, X.; Wang,
Y.-P. Tetrahedron Lett. 1996, 37, 7417. (e) Huang, X.; Xie, L.; Wu, H.
J. Org. Chem. 1988, 53, 4862. (f) Huang, X.; Xie, L.; Wu, H.
Tetrahedron Lett. 1987, 28, 801.
(10) (a) Huang, X.; Sheng, S.-R. J. Comb. Chem. 2003, 5, 273. (b)
Huang, X.; Zhou, H. Org. Lett. 2002, 4, 4419. (c) Huang, X.; Zhou, H.;
Chen, W. J. Org. Chem. 2004, 69, 839. (d) Qian, H.; Huang, X. J. Comb.
Chem. 2003, 5, 569. (e) Huang, X.; Liu, Z. J. Org. Chem. 2002, 67,
6731.
Once the reaction condition was optimized with PhTeCl
as an effective tellurenylating reagent, we applied this
protocol for the tellurolactonization of R-allenoic acid. As
summarized in Table 2, various di- and trisubstituted
R-allenoic acids can be utilized as substrates to afford
corresponding substituted â-organotellurobutenolides in
good to high yield within 30 min. A bulky tellurenylating
(11) (a) In Allenes in Organic Synthesis; Schuster, H. F., Coppola,
G. M., Eds.; John Wiley & Sons: New York, 1984. (b) In The Chemistry
of Ketenes, Allenes, and Related Compounds Part 1; Patai, S., Ed.; John
Wiley & Sons: New York, 1980.
(12) (12) R-Allenoic acids were prepared according to literature
procedures: (a) Clinet, J.-C.; Linstrumelle, G. Synthesis 1981, 875.
(b) Ma, S.; Wu, S. J. Org. Chem. 1999, 64, 9314.
(13) ArTeCl was prepared in situ from (ArTe)2 and SO2Cl2. For a
recent report, see: Hayashi, M.; Miura, T.; Matsuchika, K.; Watanabe,
Y. Synthesis 2004, 1481.
J. Org. Chem, Vol. 70, No. 17, 2005 6949

SCHEME 2
SCHEME 3
SCHEME 4
reagent bearing the naphthyl group also gave cyclization
product in good yield (entry 4). In the case of 2-allyl
R-allenoic acid 1f, the allyl group remained unreacted
indicating that the allenyl moiety is more reactive than
the individual carbon-carbon double bond (entry 7).
However, with the reaction of nonsubstituted 2,3-buta-
dienoic acid 1i no cyclization product was observed by
NMR analysis of the reaction mixture (entry 10). When
monosubstituted 2-ally-2,3-butadienoic acid 1j was used
as the substrate, the reaction was sluggish, giving only
a trace amount of the desired product, as was observed
by NMR analysis (entry 11).
The tellurolactonization of R-allenoic acids probably
proceeds through the electrophilic attack of the aryl-
telluro cation on the central carbon atom of the allenyl
moiety to afford the intermediate, the allyl cation 3a and/
or the onium cation 3b,3j which is stabilized by neighbor-
ing group participation (Scheme 2).14 Further cyclization
of the intermediate affords the final product. Because the
stabilization of the cationic intermediate by substituents
is important for the generation of 3a or 3b, the lack of
neighboring group participation will result in sluggish
tellurolactonization of the R-allenoic acids. Therefore, in
the case of nonsubstituted 1i and monosubstituted 1j,
no or only a trace amount of the cyclization product was
observed, respectively (entries 10 and 11).
of Pd/Cu(I) and 1 equiv of Et3N, the mixture of 2h and
1-hexyne in methanol afforded the cross-coupling product
5 in a moderate yield after overnight stirring at room
temperature (Scheme 4).
In conclusion, we developed a convenient and highly
efficient method for the preparation of â-organotel-
lurobutenolides via ArTeCl-induced electrophilic telluro-
lactonization of R-allenoic acids. Preliminary transfor-
mation studies suggest that the obtained tellurobuteno-
lides are practical precursors for useful substituted
butenolides. Extensive studies of the reaction in hetero-
cycle synthesis as well as detailed mechanistic studies
are still in progress and will be reported in due course.
Experimental Section
General Procedure for Electrophilic Tellurolactoniza-
tion of r-Allenoic Acids. To a solution of diaryl ditelluride
(0.50 mmol) in dry MeCN (2 mL) under N2 was added dropwise
SO2Cl2 (0.081 g, 0.60 mmol) and the mixture was stirred at room
temperature for 1 h. R-Allenoic acid (0.50 mmol) in dry MeCN
(2 mL) was then added to above ArTeCl solution with stirring.
After the reaction was complete, the mixture was concentrated
and the residue purified by flash chromatography or preparative
TLC to afford â-organotellurobutenolides 2. Reactions carried
out under different conditions were conducted in a similar
manner.
3-Benzyl-4-phenyltelluro-5-(o-chloro)phenyl-2(5H)-
butenolide (2a): 93%, pale yellow crystal, mp 118-120 °C. 1H
NMR (400 MHz, CDCl3) δ 7.36-7.25 (m, 8H), 7.20-7.12 (m, 3H),
7.06-7.02 (m, 2H), 6.97-6.96 (d, J ) 5.6 Hz, 1H), 6.03 (s, 1H),
3.91-3.87 (d, J ) 15.3 Hz, 1H), 3.71-3.67 (d, J ) 15.3 Hz, 1H).
13C NMR (100 MHz, CDCl3) δ 170.7, 144.7, 141.0, 137.1, 136.2,
135.4, 132.3, 130.5, 129.7, 129.60, 129.5, 129.3, 128.9, 127.2,
127.0, 109.0, 33.4. MS (m/z) 490 (13, M+), 455 (5), 282 (7), 265
(13), 239 (8), 207 (6), 139 (53), 115 (43), 91 (35), 77 (100). IR
(KBr) ν 1739, 1602, 1473, 1435, 1300, 1171, 1065 cm-1. Anal.
Calcd for C23H17ClO2Te: C, 56.56; H, 3.51. Found: C, 56.32; H,
3.54.
Butenolides are a class of compounds commonly ob-
served in natural products,15 and are also important
intermediates in organic synthesis.16 Bearing a versatile
vinyltelluro moiety, the obtained â-organotellurobuteno-
lides can be considered as potential precursors for useful
substituted butenolides, which was confirmed by the
following preliminary synthetic transformation studies.
Substitution reaction of 2a with diethyl cuprate reagent
at -78 °C gave a good yield of target product 4 (Scheme
3). Furthermore, in the presence of a catalytic amount
Substitution Reaction of Organotellurobutenolide 2a
with Diethyl Cuprate Reagent. Ethylmagnesium bromide
(1.50 mmol) in dry THF was added at 0 °C to the THF
suspension of CuI (0.75 mmol) in a tube reactor under nitrogen
to form the diethyl cuprate reagent. The mixture was then cooled
to -78 °C and tellurobutenolide 2a (0.50 mmol) in dry THF was
added dropwise. After the temperature was gradually returned
to room temperature, the mixture was washed with saturated
aqueous NH4Cl and NaCl, extracted with EtOAc, and dried over
MgSO4. The solvent was evaporated and the residue purified
by TLC to afford substitution product 4.
(14) Macomber, R. S.; Krudy, G. A.; Seff, K.; Rendon-Diazmiron, L.
E. J. Org. Chem. 1983, 48, 1425.
(15) (a) Larock, R. C.; Riefling, B.; Fellows, C. A. J. Org. Chem. 1978,
43, 131. (b) Ma, S.; Shi, Z. J. Org. Chem. 1998, 63, 6387. (c) Wang,
T.-Z.; Pinard, E.; Paquette, L. A. J. Am. Chem. Soc. 1996, 118, 1309.
(d) Rodriguez, A. D.; Shi, J.-G.; Huang, S.-D. J. Org. Chem. 1998, 63,
4425. (e) Takayama, H.; Kuwajima, T.; Kitajima, M.; Nonato, M. G.;
Aimi, N. Heterocycles 1999, 50, 75. (f) Xu, L.-P.; Gou, D.; Liu, J.-S.;
Zheng, J.-H.; Koike, K.; Jia, Z.-H.; Nikaido, T. Heterocycles 1999, 51,
605.
(16) (a) Chia, Y.; Chang, F.; Wu, Y. Tetrahedron Lett. 1999, 40, 7513.
(b) Takahashi, S.; Maeda, K.; Hirota, S.; Nakata, T. Org. Lett. 1999,
1, 2025. (c) Siddiqui, B. S.; Afshan, F.; Faizi, S. G.; Naqvi, S. N.-H.;
Tariq, R. M. J. Chem. Soc., Perkin Trans. 1 1999, 2367. (d) Seki, T.;
Satake, M.; Mackenzie, L.; Kaspar, H. F.; Yasumoto, T. Tetrahedron
Lett. 1995, 36, 7093.
3-Benzyl-4-ethyl-5-(o-chloro)phenyl-2(5H)-butenolide (4):
73%, pale yellow oil. 1H NMR (400 MHz, CDCl3) δ 7.42-7.39
(dd, J ) 7.8, 1.4 Hz, 1H), 7.30-7.20 (m, 7H), 7.01-6.99 (dd, J )
7.2, 1.6 Hz, 1H), 6.35 (s, 1H), 3.74-3.64 (m, 2H), 2.53-2.43 (m,
6950 J. Org. Chem., Vol. 70, No. 17, 2005

1H), 2.10-2.01 (1H), 0.96-0.92 (t, J ) 7.6 Hz, 3H). 13C NMR
(100 MHz, CDCl3) δ 174.3, 165.6, 138.1, 133.8, 132.5, 130.4,
130.0, 128.7, 128.5, 127.9, 127.5, 126.6, 126.4, 79.7, 29.6, 20.1,
12.2. MS (m/z) 312 (2, M+), 84 (100). IR (film) ν 3029, 1760, 1669,
1602, 1495, 1454, 1299, 1164, 1107, 1044, 1015 cm-1. Anal. Calcd
for C19H17ClO2: C, 72.96; H, 5.48. Found: C, 72.65; H, 5.51.
Cross-Coupling Reaction of Organotellurobutenolide
2h with 1-Hexyne. The mixture of 2h (0.50 mmol), 1-hexyne
(1.0 mmol), PdCl2 (10 mol %), CuI (10 mol %), and triethylamine
(0.50 mmol) in MeOH (5 mL) was stirred overnight under
nitrogen. Conventional workup and preparative TLC purification
afforded 5.
2958, 2872, 2221, 1761, 1640, 1495, 1455, 1356, 1163, 1084, 1021
cm-1. Anal. Calcd for C23H22O2: C, 83.60; H, 6.71. Found: C,
83.34; H, 6.75.
Characterization data of other products are shown in the
Supporting Information.
Acknowledgment. We are grateful to the National
Natural Sciences Foundation of China (Project No.
20272050, 20332060) and the CAS Academicians Foun-
dation of Zhejiang Province for financial support.
3-Benzyl-4-(1-hexynyl)-5-phenyl-2(5H)-butenolide (5): 68%,
pale yellow oil. 1H NMR (400 MHz, CDCl3) δ 7.37-7.22 (m, 10H),
5.71 (s, 1H), 3.79-3.71 (m, 2H), 2.38-2.35 (t, J ) 7.0 Hz, 2H),
1.48-1.42 (m, 2H), 1.33-1.28 (m, 2H), 0.88-0.84 (t, J ) 7.3 Hz,
3H). 13C NMR (100 MHz, CDCl3) δ 173.5, 115.0, 137.6, 134.7,
133.0, 129.2, 128.9, 128.7, 128.6, 126.7, 110.0, 83.7, 72.1, 31.1,
30.1, 21.8, 19.7, 13.5. MS (m/z) 330 (2, M+). IR (film) ν 3031,
Supporting Information Available: Experimental pro-
cedures, characterization data, and copies of 1H NMR and 13
C
NMR spectra of all compounds. This material is available free
of charge via the Internet at http://pubs.acs.org.
JO050564R
J. Org. Chem, Vol. 70, No. 17, 2005 6951