Gold-catalyzed benzannulation of 3-alkoxy-1,5-enynes: Access to functionalized benzenes

Article abstract of DOI:10.1021/jo100137j

A cationic Au(I) complex catalyzed benzannulation of 3-alkoxy-1,5-enynes bridged by a cyclopropyl ring with a variety of nucleophiles is described. The reaction occurs selectively through a 6-endo-dig pathway to provide tri- and tetrasubstituted benzenes efficiently under mild reaction conditions.

Full text of DOI:10.1021/jo100137j

pubs.acs.org/joc
Gold-Catalyzed Benzannulation of 3-Alkoxy-1,5-enynes: Access to
Functionalized Benzenes
Guijie Li and Yuanhong Liu*
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry,
Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, People’s Republic of China
yhliu@mail.sioc.ac.cn
Received January 26, 2010
A cationic Au(I) complex catalyzed benzannulation of 3-alkoxy-1,5-enynes bridged by a cyclopropyl
ring with a variety of nucleophiles is described. The reaction occurs selectively through a 6-endo-dig
pathway to provide tri- and tetrasubstituted benzenes efficiently under mild reaction conditions.
Introduction
concentrated on the cyclopropanation reactions with or without
skeletal rearrangement, while the gold-catalyzed benzannulation
has received less attention.4 These include cyclization of aromatic
enynes to naphthalenes,4a,b cycloisomerization of enyne allene
intermediates generated by gold-catalyzed 1,3-acyloxy migration
of propargyl acetates to naphthyl ketones,4c cyclization of 7,7-di-
substituted cis-4,6-dien-1-yn-3-ols,4d,e cyclization of 3,5-dien-1-
ynes via a [1,7]-hydrogen shift,4f gold-catalyzed benzannulation
of 3-hydroxy-1,5-enynes to substituted tetrahydronaphthalenes,
4g,h and tandem allylation/cyclization reactions of alkynals via
the intermediacy of 3-hydroxy- or alkoxy-1,5-enynes.4i Due to
the importance of aromatic compounds, the regioselective con-
struction of benzene derivatives is still highly desirable. On the
other hand, cyclopropylmethyl cation has been proved to be
a good precursor for ring-expansion or ring-opening reac-
tions because of its ring strain energy.5 During our ongoing
Transition metal-catalyzed 1,5- or 1,6-enyne cycloisomeriza-
tions provide rapid and highly efficient access to a variety of
carbo- and heterocyclic structural motifs, which can find a wide
range of synthetic applications.1 Research of recent years de-
monstrates that gold complexes and its salts are emerging as
powerful catalysts for enyne cyclization reactions due to their
superior chemoselectivities and activities.2,3 The resulting pro-
ducts strongly depended on the substitution pattern of enynes
and the nature of the metallic species used. Although much
progress has been achieved in this field, most of the studies
*To whom correspondence should be addressed. Fax: (þ86) 021-
64166128.
^
(1) For reviews, see: (a) Michelet, V.; Toullec, P. Y.; Genet, J. P. Angew.
Chem., Int. Ed. 2008, 47, 4268. (b) Aubert, C.; Buisine, O.; Malacria, M.
Chem. Rev. 2002, 102, 813. (c) Trost, B. M.; Krische, M. J. Synlett 1998, 1.
(d) Ojima, I.; Tzamarioudaki, M.; Li, Z.; Donovan, R. J. Chem. Rev. 1996,
96, 635. (e) Trost, B. M. Acc. Chem. Res. 1990, 23, 34.
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J. W. Tetrahedron Lett. 2001, 42, 5809. (c) Zhao, J.; Hughes, C. O.; Toste, F. D.
J. Am. Chem. Soc. 2006, 128, 7436. (d) Lin, M.-Y.; Das, A.; Liu, R.-S. J. Am.
Chem. Soc. 2006, 128, 9340. (e) Tang, J.-M.; Bhunia, S.; Sohel, S. M. A.; Lin,
M.-Y.; Liao, H.-Y.; Datta, S.; Das, A.; Liu, R.-S. J. Am. Chem. Soc. 2007, 129,
15677. (f) Lian, J.-J.; Lin, C.-C.; Chang, H.-K.; Chen, P.-C.; Liu, R.-S. J. Am.
(2) For recent reviews on gold-catalyzed cycloisomerization of 1,n-enynes,
ꢀ
ꢀ~
see: (a) Jimenez-Nunez, E.; Echavarren, A. M. Chem. Rev. 2008, 108, 3326.
(b) Muzart, J. Tetrahedron 2008, 64, 5815. (c) Shen, H. C. Tetrahedron 2008, 64,
7847. (d) Ma, S.; Yu, S.; Gu, Z. Angew. Chem., Int. Ed. 2006, 45, 200.
(3) For recent reviews on gold-catalyzed reactions, see: (a) Lipshutz,
B. H.; Yamamoto, Y. Chem. Rev. 2008, 108, 2793. (b) Li, Z.; Brouwer, C.;
He, C. Chem. Rev. 2008, 108, 3239. (c) Arcadi, A. Chem. Rev. 2008, 108, 3266.
(d) Gorin, D. J.; Sherry, B. D.; Toste, F. D. Chem. Rev. 2008, 108, 3351.
(e) Patil, N. T.; Yamamoto, Y. Chem. Rev. 2008, 108, 3395. (f) Hashmi,
A. S. K.; Rudolph, M. Chem. Soc. Rev. 2008, 37, 1766. (g) Shen, H. C.
Tetrahedron 2008, 64, 3885. (h) Gorin, D. J.; Toste, F. D. Nature 2007, 446,
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Chem. Soc. 2006, 128, 9661. (g) Grise, C. M.; Barriault, L. Org. Lett. 2006, 8,
5905. (h)Grise, C.M.;Rodrigue, E.M.;Barriault,L.Tetrahedron2008, 64, 797.
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(i) Bhunia, S.; Sohel, S. M. A.; Yang, C.-C.;Lush, S.-F.;Shen, F.-M.; Liu, R.-S.
J. Organomet. Chem. 2009, 694, 566. (j) For Ru and DBU-cocatalyzed
benzannulation, see: Yang, C.-W.; Liu, R.-S. Tetrahedron Lett. 2007, 48,
5887. (k) For gold-catalyzed cyclization of indole-substituted N-propargyl-
amides to β-carbolines, see: Verniest, G.; England, D.; De Kimpe, N.; Padwa,
A. Tetrahedron 2010, 66, 1496.
(5) (a) Trost, B. M. Top. Curr. Chem. 2008, 133, 3. (b) Reissig, H. U.;
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DOI: 10.1021/jo100137j
r
Published on Web 03/25/2010
J. Org. Chem. 2010, 75, 2903–2909 2903
2010 American Chemical Society

Li and Liu
JOCArticle
SCHEME 1
TABLE 1. Optimization Studies on the Reaction Conditions
entry
catalyst
AuClPPh3
AgBF4
AuClPPh3/AgOTf CH2Cl2
AuClPPh3/AgSbF6 CH2Cl2
Ph3PAuN(Tf)2
AuCl3
AuClPPh3/AgBF4 CH2Cl2
AuClPPh3/AgBF4 CH2Cl2
AuClPPh3/AgBF4 THF
solvent
CH2Cl2
CH2Cl2
additive time (h) yielda
1
2
3
4
5
6
7
8
9
20
3
4
NRb
NRb
trace
trace
studies on gold-catalyzed transformations,6 we envisioned
that the incorporation of a cyclopropyl ring into an enyne
skeleton would greatly increase the versatility of the enyne
cyclization reactions.7 Herein, we would like to report our
recent achievement on the cycloisomerizations of 3-alkoxy-
1,5-enynes bridged by a cyclopropyl moiety like 1 assisted by
the attack of nueclophiles to form tri- or tetrasubstituted
benzenes (Scheme 1).
4
c
CH2Cl2
CH2Cl2
20
20
2
-
-
c
54%
78%
3%d
5.0 MeOH
5.0 MeOH
5.0 MeOH
5.0 MeOH
5.0 MeOH
5.0 MeOH
2
12
20
10
8
10 AuClPPh3/AgBF4 Et2O
11 AuClPPh3/AgBF4 toluene
12 AuClPPh3/AgBF4 CH3CN
13 AuClPPh3/AgBF4 CH3NO2
18%e
62%
trace
42%f
20
Results and Discussion
14 AuClPPh3/AgBF4 ClCH2CH2Cl 5.0 MeOH
15 AuClPPh3/AgBF4 ClCH2CH2Cl
16 AuClPPh3/AgBF4 ClCH2CH2Cl 2.0 MeOH
17 AuClPPh3/AgBF4 ClCH2CH2Cl 10.0 MeOH 10
18 AuClPPh3/AgBF4 ClCH2CH2Cl 2.0 H2O
2.5 81%
4
2
49%
83%
77%
To probe the feasibility of the enyne transformations, we ini-
tially investigated the cyclization reaction of (3-methoxy-3-(1-
(1-phenylvinyl)cyclopropyl)prop-1-ynyl)benzene (1a; Table 1),
which was easily prepared by three steps from commercially
available cyclopropyl phenyl ketone.8 To our disappointed, no
reaction or trace product formation was observed when PPh3-
AuCl, AgBF4, PPh3AuCl/AgOTf, or PPh3AuCl/AgSbF6 were
used as catalysts in dichloromethane (entries 1-4). PPh3Au-
NTf2 and AuCl3 also showed negative results even prolonged
the reaction time to 20 h (entries 5 and 6). Surprisingly, we
found that in the presence of 5 mol % of PPh3AuCl/AgBF4, 1a
could be consumed in 2 h to afford 4-methoxyethyl-1,3-diphe-
nylbenzene (2a) in 54% yield (entry 7). The presence of the
methoxy unit on the ethyl terminus in 2a indicated that the ring-
opening and alkoxylation by methanol formed in situ occurred
during the process. We then added 5 equiv of MeOH to the
reaction mixture; to our delight, the yield of the desired benzene
2a increased dramatically to 78% (entry 8). Among various
solvents we examined, 1,2-dichloroethane was found to be the
best solvent, which afforded 2a in 77-83% yields (entries 14
and 16-17). When 2 equiv of H2O was added to the mixture, 2a
was still formed in 69% yield, together with 15% 2-(1,10,30,100)-
terphenyl-40-yl-ethanol (entry 18).
With the optimized reaction conditions in hand, we pro-
ceeded to examine the reaction scope with a wide range of
nucleophiles and the substrates of 3-alkoxy-1,5-enynes. We first
investigated the scope of nucleophiles (Table 2). It was found
that in addition to methanol, a variety of alcohols could be used
as effective nucleophiles for this reaction. The use of 2 equiv of
nucleophile such as ethanol resulted in the formation of a
mixture of methyl and ethyl ether (Table 2, entry 1). In the
presence of a large excess of ethanol (10 equiv), the desired ethyl
ether 2b was obtained in 69% yield, while only a trace amount of
1.5 69%g
aIsolated yield. bNo reaction. c2a was not observed according to 1H
NMR of the crude mixture. d65% 1a was recovered. e47% 1a was
f
g
recovered. NMR yield. The product of 2-(1,10,30,100)-terphenyl-40-yl-
ethanol derived through ring-opening reaction by H2O was also ob-
tained in 15% yield.
2a was observed (entry 2). Treatment of 1a with a secondary
alcohol such as 2-butanol afforded the corresponding alkoxy-
cyclization9 product 2c in 77% yield (entry 3). Alcohols con-
taining alkene or alkyne moieties were well tolerated in this AuI-
catalyzed transformation, furnishing 2d-h in 54-91% yields
(entries 4-8). Benzylic alcohol with a halide functionality such
as (2-bromophenyl)methanol underwent the cyclization reac-
tion smoothly to generate the desired 2i in 75% yield (entry 9).
The enantiomerically pure alcohols such as (-)-menthol and
(-)-borneol were also successfully employed as nucleophiles for
this cyclization, and the corresponding alkoxylated benzenes 2j
and 2k were formed in 66% and 72% yields, respectively (entries
10 and 11). However, when 2-hydroxy-1,2-diphenylethanone or
TsNH2 were used, only low yields of the desired products were
obtained, which might be due to the lower nucleophilicity of
these nucleophiles (entries 12 and 13). When the cyclopropane
ring in enyne skeleton was replaced by a cyclobutane ring (for
example, the enyne of (3-methoxy-3-(1-(1-phenylvinyl)cyclo-
butyl)prop-1-ynyl)benzene, 3a) or dimethyl group at C-4 (for
example, the enyne of (3-methoxy-4,4-dimethylhex-5-en-1-yne-
1,5-diyl)dibenzene, 3b), only a complicated reaction mixture was
(9) For gold-catalyzed hydroxy- or alkoxycyclizations of enynes to form
carbo- or heterocycles other than benzenes, see: (a) Buzas, A. K.; Istrate,
F. M.; Gagosz, F. Angew. Chem., Int. Ed. 2007, 46, 1141. (b)Nieto-Oberhuber,
~
C.; Munoz, M. P.; Lopez, S.; Jimenez-Nunez, E.; Nevado, C.; Herrero-
Gomez, E.; Raducan, M.; Echavarren, A. M. Chem.;Eur. J. 2006, 12,
ꢀ
ꢀ
ꢀ~
(6) (a) Chen, Y.; Lu, Y.; Li, G.; Liu, Y. Org. Lett. 2009, 11, 3838. (b) Lu,
Y.; Fu, X.; Chen, H.; Du, X.; Jia, X.; Liu, Y. Adv. Synth. Catal. 2009, 351,
129. (c) Lu, Y.; Du, X.; Jia, X.; Liu, Y. Adv. Synth. Catal. 2009, 351, 1517.
(d) Yan, B.; Liu, Y. Org. Lett. 2007, 9, 4323. (e) Guo, S.; Song, F.; Liu, Y.
Synlett 2007, 964. (f) Liu, Y.; Liu, M.; Guo, S.; Tu, H.; Zhou, Y.; Gao., H.
Org. Lett. 2006, 8, 3445. (g) Liu, Y.; Song, F.; Song, Z.; Liu, M.; Yan, B. Org.
Lett. 2005, 7, 5409.
ꢀ
~
1677. (c) Munoz, M. P.; Adrio, J.; Carretero, J. C.; Echavarren, A. M.
Organometallics 2005, 24, 1293. (d) Munoz, M. P.; Mendez, M.; Nevado,
~
ꢀ
ꢀ
C.; Cardenas, D. J.; Echavarren, A. M. Synthesis 2003, 2898. (e) Nevado, C.;
CIrdenas, D. J.; Echavarren, A. M. Chem.;Eur. J. 2003, 9, 2627. (f) Nevado,
~
C.; Charruault, L.; Michelet, V.; Nieto-Oberhuber, C.; Munoz, M. P.;
ꢀ ^
Mendez, M.; Rager, M.-N.; Genet, J.-P.; Echavarren, A. M. Eur. J. Org.
(7) (a) Sethofer, S. G.; Staben, S. T.; Hung, O. Y.; Toste, F. D. Org. Lett.
ꢀ
ꢀ~
ꢀ ~ ꢀ
Chem. 2003, 706. (g) Mendez, M.; Munoz, M. P.; Nevado, C.; Cardenas, D. J.;
2008, 10, 4315. (b) Jimenez-Nunez, E.; Claverie, C. K.; Nieto-Oberhuber, C.;
Echavarren, A. M. Angew. Chem., Int. Ed. 2006, 45, 5452.
(8) See the Supporting Information.
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Echavarren, A. M. J. Am. Chem. Soc. 2001, 123, 10511. (h) Mendez, M.;
Munoz, M. P.; Echavarren, A. M. J. Am. Chem. Soc. 2000, 122, 11549.
~
2904 J. Org. Chem. Vol. 75, No. 9, 2010

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TABLE 2. Gold-Catalyzed Benzannulation of Enyne 1a with Various
Nucleophiles
TABLE 3. Scope of the Gold-Catalyzed Benzannulation Reactions
aIsolated yield. All the reactions were carried out for 0.5-3 h.
SCHEME 2
aIsolated yield. bThe reaction was carried out at room temperature.
c2.0 equiv of EtOH was used, the ratio of 2a/2b is 1:3.2. dEnyne was
consumed; however, the reaction was not clean. eThe reaction was
carried out at 50 °C, and 5.0 equiv of TsNH2 was used.
results indicated that both the ethyl and allyl groups were
compatible with the catalytic system, especially, a quantitive
yield of 2d was obtained within 1 h in the latter case with
allylic alcohol as the nucleophile (Scheme 2).
The reaction is also extendible to trisubstituted alkene 1j.
We prepared both Z- and E-isomers of this substrate, and
their stereochemistry has been confirmed by NOESY spec-
tra. Both isomers worked very well to afford the same
tetrasubstituted benzene 2x in good yields within a short
time (Scheme 3). The results indicated that the geometry of
the double bond in 1,5-enyne had a little influence on the
cyclization reaction. The structure of 2x has been confirmed
by X-ray crystallographic analysis.8
We propose the following mechanism for this reaction. In
the first step, the coordination of the triple bond of 1,5-enyne
1 to PPh3Auþ enhances the electrophilicity of the alkyne, and
the subsequent 6-endo-dig ring closure occurs to afford the
cyclopropylmethyl cationic intermediate 4, which is also
represented by the resonance of carbenoid intermedi-
ate 5. Two pathways might be involved in the following
observed. It is clear that the existence of the cyclopropyl ring is
crucial for the clean transformations.
Next, we studied the scope of the enyne substrates
(Table 3). It was found that the aromatic rings of R1 at the
alkyne terminus bearing an electron-donating or an electron-
withdrawing group were all compatible under the reaction
conditions, leading to the corresponding benzenes 2n-r in
77-91% yields at room temperature in 0.5-3 h (Table 3,
entries 1-5). A thienyl group of R1 was also suitable for this
reaction, and high yields of 2s and 2t could be achieved
through the reactions with either MeOH or allylic alcohol
(entries 6 and 7). A bulky aromatic ring such as 2-(6-
methoxy)naphthyl group was well accommodated to yield
the product 2u in 96% yield (entry 8). Enyne 1g with a
substituted aryl group such as p-MeOC6H4 present at the
alkene double bond (R2 group) was smoothly converted into
the benzene derivatives 2v-w in 67-75% yields (entries 9
and 10).
Enynes with a different protection group at the pro-
pargylic position (R4) have also been investigated. The
J. Org. Chem. Vol. 75, No. 9, 2010 2905

Li and Liu
JOCArticle
SCHEME 3
SCHEME 4
transformations: in path a, deprotonation of 4 leads to
cyclohexadienyl gold 6, then deauration followed by nucleo-
philic attack of ROH to cyclopropyl ring furnishes the ring-
opening and aromatized product 2 (Scheme 4).10 Alterna-
tively, in path b, direct attack of nucleophile to the cyclo-
propyl ring in 5 followed by protodemetalation and
elimination of MeOH leads to the same product 2.9a In
addition, ring-opening by ROH from intermediate 4 to 9
also cannot be excluded.
the residue was purified by chromatography on silica gel (eluent:
petroleum ether/ethyl acetate) to afford the benzene deriva-
tives 2.
2a: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 50:1)
afforded the title compound 2a as a brown sticky liquid in 83%
yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.91 (t, J = 7.2 Hz,
2H), 3.24 (s, 3H), 3.47 (t, J = 7.2 Hz, 2H), 7.28-7.47 (m, 10H),
7.54 (dd, J = 7.8, 2.1 Hz, 1H), 7.60-7.62 (m, 2H); 13C NMR
(CDCl3, Me4Si, 75 MHz) δ 32.8, 58.5, 73.0, 126.0, 127.0 (3C),
127.2, 128.1 (2C), 128.7 (2C), 128.8, 129.2 (2C), 130.1, 135.2,
139.0, 140.6, 141.5, 142.7; IR (KBr) 3057, 3027, 2976, 2925,
2871, 2824, 1600, 1479, 1443, 1383, 1180, 1113, 1027, 1012, 1000,
968, 895, 833, 762, 700 cm-1; HRMS (EI) calcd for C21H20O
288.1514, found 288.1513.
Conclusion
In summary, we have developed a gold-catalyzed benzan-
nulation of 3-alkoxy-1,5-enynes bridged by a cyclopropyl
ring with various nucleophiles under mild reaction condi-
tions, which provided an efficient route to tri- and tetrasub-
stituted benzenes with a wide range of substituents. The
existence of the cyclopropyl ring is proved to be crucial for
the clean transformations. Further research to explore the
new synthetic utility of this gold-catalyzed cascade reaction
is currently underway.
2b: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2b as a light yellow sticky liquid in
69% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 1.13 (t, J =
7.2 Hz, 3H), 2.91 (t, J = 6.9 Hz, 2H), 3.38 (q, J = 7.2 Hz, 2H),
3.51 (t, J = 7.2 Hz, 2H), 7.28-7.42 (m, 10H), 7.52-7.55 (m,
1H), 7.59 (d, J = 7.5 Hz, 2H); 13C NMR (CDCl3, Me4Si, 75
MHz) δ 15.1, 33.0, 66.0, 71.0, 125.9, 126.95, 126.97 (2C), 127.1,
128.1 (2C), 128.7 (2C), 128.8, 129.2 (2C), 130.2, 135.3, 138.9,
140.6, 141.5, 142.7; IR (KBr) 3058, 3027, 2971, 2865, 1600, 1479,
Experimental Section
1442, 1376, 1354, 1261, 1106, 1075, 1025, 894, 800, 762, 700 cm-1
;
General Procedure for Au(I)-Catalyzed Benzannulation of
3-Alkoxy-1,5-enynes. To a solution of 1,5-enyne 1 (0.3 mmol)
and alcohol (2-10 equiv) in ClCH2CH2Cl (6 mL) was added
Ph3PAuCl (0.015 mmol, 7.4 mg) and AgBF4 (0.015 mmol,
300 uL, used as a 0.05 M solution in toluene). The resulting
solution was stirred at room temperature or 60 °C until the
reaction was complete as monitored by thin-layer chromato-
graphy. The solvent was evaporated under reduced pressure and
HRMS (EI) calcd for C22H22O 302.1671, found 302.1674.
2c: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 50:1)
afforded the title compound 2c as a light yellow sticky liquid in
77% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 0.81 (t, J =
7.2 Hz, 3H), 1.02 (d, J = 6.0 Hz, 3H), 1.26-1.50 (m, 2H), 2.90 (t,
J = 7.5 Hz, 2H), 3.16-3.23 (m, 1H), 3.40-3.48 (m, 1H), 3.51-
3.59 (m, 1H), 7.28-7.47 (m, 10H), 7.53 (dd, J = 8.1, 2.1 Hz, 1H),
7.58-7.62 (m, 2H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ 9.7,
19.1, 29.0, 33.5, 68.7, 76.6, 125.9, 126.9, 127.0 (2C), 127.1, 128.1
(2C), 128.69 (2C), 128.74, 129.2 (2C), 130.3, 135.5, 138.9, 140.7,
141.6, 142.7; IR (KBr) 3058, 3028, 2966, 2931, 2873, 1600, 1479,
1464, 1443, 1373, 1340, 1261, 1172, 1139, 1113, 1083, 1026, 1012,
(10) As shown in Table 1, entry 7, the product of 2a could be obtained in
54% yield without addition of any nucleophile. We suggested that in this
case, a trace amount of H2O presented in the reaction mixture might induce
the ring-opening reaction to release the MeOH, then the reaction could
proceed.
2906 J. Org. Chem. Vol. 75, No. 9, 2010

Li and Liu
JOCArticle
895, 830, 762, 700 cm-1; HRMS (EI) calcd for C24H26O
330.1984, found 330.1981.
1110, 1075, 1026, 1012, 895, 832, 762, 700, 638 cm-1; HRMS
(EI) calcd for C24H22O 326.1671, found 326.1672.
2d: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 80:1)
afforded the title compound 2d as a light yellow sticky liquid in
84% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.93 (t, J =
7.2 Hz, 2H), 3.52 (t, J = 7.2 Hz, 2H), 3.87 (dd, J = 5.1, 0.9 Hz,
2H), 5.11 (d, J = 10.5 Hz, 1H), 5.18 (d, J = 17.4 Hz, 1H),
5.76-5.89 (m, 1H), 7.28-7.46 (m, 10H), 7.53 (d, J = 7.8 Hz,
1H), 7.59 (d, J = 8.1 Hz, 2H); 13C NMR (CDCl3, Me4Si, 75
MHz) δ 32.9, 70.6, 71.6, 116.7, 125.9, 127.0 (3C), 127.2, 128.1
(2C), 128.7 (2C), 128.8, 129.2 (2C), 130.2, 134.7, 135.2, 139.0,
140.6, 141.5, 142.7; IR (KBr) 3058, 3027, 2963, 2856, 1600, 1479,
1443, 1261, 1097, 1025, 923, 895, 800, 762, 700 cm-1; HRMS
(EI) calcd for C23H22O 314.1671, found 314.1667.
2e: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2e as a colorless sticky liquid in
91% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.26 (qt, J =
6.9, 1.5 Hz, 2H), 2.91 (t, J = 7.5 Hz, 2H), 3.36 (t, J = 6.6 Hz,
2H), 3.52 (t, J = 7.2 Hz, 2H), 4.98-5.07 (m, 2H), 5.69-5.82 (m,
1H), 7.27-7.46 (m, 10H), 7.53 (dd, J = 7.8, 1.5 Hz, 1H),
7.57-7.61 (m, 2H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ
32.9, 34.1, 70.0, 71.3, 116.2, 125.9, 127.0 (3C), 127.1, 128.1
(2C), 128.7 (2C), 128.8, 129.2 (2C), 130.2, 135.2, 135.3, 138.9,
140.6, 141.5, 142.6; IR (KBr) 3059, 3027, 2931, 2859, 1641, 1600,
1479, 1442, 1391, 1362, 1260,1108, 1026, 1012, 996, 914, 831,
762, 700 cm-1; HRMS (EI) calcd for C24H24O 328.1827, found
328.1828.
2f: Purification of the crude product by flash chromatography
on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2f as a colorless sticky liquid in 90%
yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 1.25-1.43 (m,
12H), 1.47-1.59 (m, 2H), 1.99-2.06 (m, 2H), 2.91 (t, J = 7.2,
Hz, 2H), 3.30 (t, J = 6.6 Hz, 2H), 3.50 (t, J = 7.2 Hz, 2H),
4.90-5.02 (m, 2H), 5.73-5.86 (m, 1H), 7.27-7.46 (m, 10H),
7.53 (dd, J = 8.1, 1.5 Hz, 1H), 7.58-7.61 (m, 2H); 13C NMR
(CDCl3, Me4Si, 75 MHz) δ 26.1, 28.9, 29.1, 29.4(2C), 29.5, 29.6,
33.0, 33.8, 70.8, 71.2, 114.1, 125.9, 126.9, 127.0 (2C), 127.1, 128.1
(2C), 128.7 (2C), 128.8, 129.2 (2C), 130.2, 135.4, 138.9, 139.2,
140.7, 141.6, 142.6; IR (KBr) 3060, 3028, 2926, 2854, 1640, 1600,
1479, 1465, 1442, 1366, 1111, 1027, 1012, 994, 910, 831, 761,
700 cm-1; HRMS (EI) calcd for C31H38O 426.2923, found
426.2926.
2g: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2g as a light yellow sticky liquid in
54% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.38 (s, 1H),
2.94 (t, J = 7.2 Hz, 2H), 3. 63 (t, J = 7.2 Hz, 2H), 4.05 (s, 2H),
7.30-7.47 (m, 10H), 7.50 (d, J = 7.5 Hz, 1H), 7.61 (d, J = 7.5
Hz, 2H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ 32.7, 57.9, 70.3,
74.3, 79.7, 126.0, 127.0 (2C), 127.2, 128.2 (2C), 128.7 (2C), 128.9,
129.2 (2C), 130.2, 134.8, 139.1, 140.6, 141.4, 142.7. One carbon
overlapped with other signals; IR (KBr) 3291, 3057, 3027, 2936,
2861, 2114, 1599, 1479, 1442, 1389, 1356, 1267, 1138, 1356, 1267,
1097, 1026, 1011, 896, 834, 762, 700 cm-1; HRMS (EI) calcd for
C23H20O 312.1514, found 312.1525.
2i: Purification of the crude product by flash chromatography
on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2i as a light yellow sticky liquid in
75% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.99 (t, J =
6.9 Hz, 2H), 3.62 (t, J = 7.5 Hz, 2H), 4.45 (s, 2H), 7.06 (td, J =
7.2, 1.5 Hz, 1H), 7.18-7.23 (m, 1H), 7.28-7.43 (m, 10H),
7.45-7.48 (m, 2H), 7.53 (dd, J = 7.8, 1.8 Hz, 1H), 7.57-7.60
(m, 2H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ 33.0, 71.2, 71.9,
122.4, 125.9, 126.96 (2C), 126.98, 127.2, 127.2, 128.1 (2C),
128.65, 128.69 (2C), 128.8, 129.2 (2C), 130.3, 132.3, 135.1,
137.6, 139.0, 140.6, 141.4, 142.7. One carbon overlapped with
other signals; IR (KBr) 3057, 3027, 2926, 2862, 1599, 1568, 1479,
1441, 1390, 1357, 1263, 1205, 1122, 1101, 1027, 895, 832, 751,
700 cm-1; HRMS (EI) calcd for C27H23OBr 442.0932, found
442.0940.
2j: Purification of the crude product by flash chromatography
on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2j as a brown sticky liquid in 66%
1
yield. [R]20 -37.7 (c 1.22, CHCl3); H NMR (CDCl3, Me4Si,
D
300 MHz) δ 0.63 (d, J = 6.9 Hz, 3H), 0.69-0.94 (m, 9H),
1.10-1.28 (m, 2H), 1.52-1.61 (m, 2H), 1.90 (d, J = 9.3 Hz, 1H),
2.02-2.08 (m, 1H), 2.82-2.93 (m, 3H), 3.29-3.37 (m, 1H),
3.64-3.72 (m, 1H), 7.27-7.46 (m, 10H), 7.51 (dd, J = 7.8, 2.1
Hz, 1H), 7.59 (d, J = 7.2, 2H); 13C NMR (CDCl3, Me4Si, 100
MHz) δ 16.1, 20.9, 22.3, 23.3, 25.4, 31.5, 33.7, 34.5, 40.4, 48.1,
68.9, 79.2, 125.9, 126.9, 127.0 (2C), 127.1, 128.1 (2C), 128.68
(2C), 128.74, 129.2 (2C), 130.3, 135.4, 139.0, 140.7, 141.6, 142.6;
IR (KBr) 3058, 3027, 2955, 2922, 2867, 1599, 1479, 1453, 1384,
1369, 1343, 1262, 1179, 1107, 1089, 1013, 895, 831, 761, 700
cm-1; HRMS (EI) calcd for C30H36O 412.2766, found 412.2762.
2k: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2k as a brown sticky liquid in 72%
yield. [R]20D -25.4 (c 0.674, CHCl3); 1H NMR (CDCl3, Me4Si,
400 MHz) δ 0.77-0.88 (m, 10H), 1.10-1.17 (m, 2H), 1.43-1.57
(m, 1H), 1.61-1.66 (m, 1H), 1.87-2.00 (m, 2H), 2.86-2.91 (m,
2H), 3.39-3.55 (m, 3H), 7.29-7.46 (m, 10H), 7.53 (dd, J = 7.6,
2.0 Hz, 1H), 7.59-7.62 (m, 2H); 13C NMR (CDCl3, Me4Si, 100
MHz) δ 14.0, 18.8, 19.8, 26.6, 28.2, 33.4, 36.2, 44.9, 47.7, 49.1,
70.4, 84.6, 125.8, 126.9, 127.0 (2C), 127.1, 128.1 (2C), 128.7 (3C),
129.3 (2C), 130.5, 135.8, 138.8, 140.8, 141.7, 142.6; IR (KBr)
3058, 3027, 2949, 2873, 1600, 1479, 1452, 1387, 1369, 1358, 1232,
1139, 1117, 1094, 1076, 1026, 1013, 895, 830, 761, 700 cm-1
HRMS (EI) calcd for C30H34O 410.2610, found 410.2609.
;
2l: Purification of the crude product by flash chromatography
on silica gel (eluent: petroleum ether/ethyl acetate = 25:1)
afforded the title compound 2l as a brown sticky liquid in
1
33% yield. H NMR (CDCl3, Me4Si, 400 MHz) δ 2.98-3.02
(m, 2H), 3.60-3.64 (m, 2H), 5.40 (s, 1H), 7.22-7.46 (m, 18H),
7.50 (dd, J = 8.0, 0.8 Hz, 1H), 7.59-7.61 (m, 2H), 7.87-7.89 (m,
2H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ 33.0, 70.2, 85.5,
125.9, 126.95 (3C), 127.12 (2C), 127.19, 128.1 (2C), 128.2, 128.3
(2C), 128.6 (2C), 128.7 (2C), 128.8, 129.1 (4C), 130.5, 133.1,
134.6, 134.9, 136.2, 139.1, 140.6, 141.3, 142.6, 197.4; IR (KBr)
3059, 3027, 2928, 2866, 1694, 1677, 1597, 1578, 1479, 1448, 1391,
1308, 1275, 1239, 1214, 1180, 1107, 1075, 1027, 968, 895, 831,
762, 697 cm-1; HRMS (EI) calcd for C34H28O2 468.2089, found
468.2093.
2h: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 10:1)
afforded the title compound 2h as a light yellow sticky liquid in
61% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 1.95 (t, J =
2.4 Hz, 1H), 2.38 (td, J = 6.9, 2.4 Hz, 2H), 2.92 (t, J = 7.5 Hz,
2H), 3.45 (t, J = 6.9 Hz, 2H), 3.56 (t, J = 7.5 Hz, 2H), 7.29-7.47
(m, 10H), 7.54 (dd, J = 8.1, 1.8 Hz, 1H), 7.60 (d, J = 7.5 Hz,
2H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ 19.7, 32.8, 68.6, 69.2,
71.4, 81.3, 126.0, 127.0 (3C), 127.2, 128.2 (2C), 128.7 (2C), 128.8,
129.2 (2C), 130.2, 135.1, 139.0, 140.6, 141.5, 142.7; IR (KBr)
3296, 3057, 3027, 2916, 2865, 2116, 1599, 1479, 1442, 1391, 1364,
2m: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 5:1)
afforded the title compound 2m as a brown sticky liquid in 23%
yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.40 (s, 3H), 2.81 (t,
J = 6.9 Hz, 2H), 3.00 (q, J = 6.9 Hz, 2H), 4.23 (t, J = 6.0 Hz,
1H), 7.20-7.23 (m, 5H), 7.25-7.46 (m, 7H), 7.51 (dd, J = 7.8,
1.8 Hz, 1H), 7.58 (d, J = 7.5 Hz, 4H); 13C NMR (CDCl3, Me4Si,
75 MHz) δ 21.5, 32.7, 43.4, 126.2, 126.96 (2C), 127.00 (2C),
J. Org. Chem. Vol. 75, No. 9, 2010 2907

Li and Liu
JOCArticle
127.2, 127.4, 128.3 (2C), 128.8 (2C), 129.0 (2C), 129.1, 129.6
(2C), 130.1, 134.0, 136.7, 139.6, 140.3, 141.0, 142.6, 143.2; IR
(KBr) 3285, 3058, 3028, 2926, 2872, 1710, 1598, 1479, 1443,
afforded the title compound 2s as a brown black sticky liquid in
91% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.86 (t, J =
7.2 Hz, 2H), 3.21 (s, 3H), 3.43 (t, J = 7.5 Hz, 2H), 7.02 (t, J = 5.1
Hz, 1H), 7.20 (d, J = 5.1 Hz, 1H), 7.27 (d, J = 3.6 Hz, 1H),
7.31-7.43 (m, 6H), 7.47 (d, J = 1.8 Hz, 1H), 7.53 (dd, J = 7.8,
1.8 Hz, 1H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ 32.8, 58.4,
72.9, 122.9, 124.5, 124.8, 127.0, 127.5, 127.9, 128.1 (2C), 129.1
(2C), 130.2, 132.3, 135.4, 141.1, 142.7, 143.9; IR (KBr) 3104,
3059, 2923, 2868, 1599, 1560, 1483, 1442, 1401, 1380, 1188, 1110,
1024, 962, 889, 856, 817, 779, 748, 702 cm-1; HRMS (EI) calcd
for C19H18OS 294.1078, found 294.1079.
2t: Purification of the crude product by flash chromatography
on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2t as a light yellow sticky liquid in
81% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.89 (t, J =
7.2 Hz, 2H), 3.49 (t, J = 7.2 Hz, 2H), 3.84-3.87 (m, 2H),
5.09-5.20 (m, 2H), 5.76-5.88 (m, 1H), 7.04 (dd, J = 5.1, 3.6 Hz,
1H), 7.23 (dd, J = 5.1, 0.9 Hz, 1H), 7.28 (dd, J = 3.9, 0.6 Hz,
1H), 7.33-7.45 (m, 6H), 7.47 (d, J = 1.8 Hz, 1H), 7.54 (dd, J =
7.8, 2.1 Hz, 1H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ 33.0,
70.5, 71.6, 116.7, 122.9, 124.6, 124.8, 127.1, 127.5, 127.9, 128.1
(2C), 129.2 (2C), 130.3, 132.3, 134.7, 135.5, 141.2, 142.8, 144.0;
IR (KBr) 3071, 3023, 2918, 2856, 1601, 1485, 1442, 1434, 1401,
1347, 1267, 1240, 1209, 1136, 1097, 990, 924, 891, 854, 818, 771,
701 cm-1; HRMS (EI) calcd for C21H20OS 320.1235, found
320.1237.
2u: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 20:1)
afforded the title compound 2u as a white solid in 96% yield. Mp
94-95 °C; 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.93 (t, J = 7.5
Hz, 2H), 3.25 (s, 3H), 3.48 (t, J = 7.2 Hz, 2H), 3.89 (s, 3H),
7.13-7.16 (m, 2H), 7.36-7.46 (m, 6H), 7.58 (s, 1H), 7.64 (d, J =
7.8 Hz, 1H), 7.70-7.78 (m, 3H), 7.98 (s, 1H); 13C NMR (CDCl3,
Me4Si, 75 MHz) δ 32.8, 55.2, 58.4, 73.0, 105.4, 119.1, 125.3,
125.8, 126.0, 127.0, 127.2, 128.1 (2C), 128.8, 129.1, 129.2 (2C),
129.6, 130.2, 133.7, 134.9, 135.7, 138.9, 141.5, 142.7, 157.6; IR
(KBr) 3052, 2993, 2954, 2920, 2871, 2817, 2807, 1626, 1606,
1490, 1388, 1239, 1201, 1168, 1114, 1029, 1016, 969, 893, 859,
837, 821, 775, 703 cm-1; HRMS (EI) calcd for C26H24O2
368.1776, found 368.1777.
2v: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 40:1)
afforded the title compound 2v as a colorless sticky liquid in
75% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.92 (t, J =
7.5 Hz, 2H), 3.25 (s, 3H), 3.48 (t, J = 7.2 Hz, 2H), 3.83 (s, 3H),
6.93-6.97 (m, 2H), 7.26-7.33 (m, 3H), 7.37-7.46 (m, 4H), 7.51
(dd, J = 7.8, 2.4 Hz, 1H), 7.58-7.61 (m, 2H); 13C NMR (CDCl3,
Me4Si, 75 MHz) δ 32.8, 55.2, 58.5, 73.0, 113.5 (2C), 125.7, 127.0
(2C), 127.1, 128.7 (2C), 129.0, 130.1, 130.2 (2C), 133.8, 135.3,
139.0, 140.7, 142.3, 158.6; IR (KBr) 3056, 3030, 2930, 2871,
2834, 1610, 1574, 1514, 1481, 1463, 1384, 1290, 1248, 1177, 1112,
1030, 835, 763, 699, 579 cm-1; HRMS (EI) calcd for C22H22O2
318.1620, found 318.1622.
1328, 1159, 1093, 1076, 896, 814, 762, 701, 662, 550 cm-1
HRMS (EI) calcd for C27H25NO2S 427.1606, found 427.1603.
;
2n: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 20:1)
afforded the title compound 2n as a light brown sticky liquid in
91% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.90 (t, J =
7.2 Hz, 2H), 3.23 (s, 3H), 3.46 (t, J = 7.2 Hz, 2H), 3.79 (s, 3H),
6.92-6.96 (m, 2H), 7.34-7.43 (m, 7H), 7.47-7.54 (m, 3H); 13C
NMR (CDCl3, Me4Si, 75 MHz) δ 32.7, 55.2, 58.4, 73.0, 114.1
(2C), 125.5, 126.9, 127.9 (2C), 128.1 (2C), 128.3, 129.2 (2C),
130.1, 133.1, 134.4, 138.6, 141.6, 142.6, 159.0; IR (KBr) 3053,
3024, 2930, 2894, 2834, 2808, 1609, 1580, 1519, 1499, 1484, 1463,
1442, 1384, 1287, 1249, 1179, 1112, 1041, 1029, 967, 896, 823,
773, 704 cm-1; HRMS (EI) calcd for C22H22O2 318.1620, found
318.1618.
2o: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 20:1)
afforded the title compound 2o as a light brown sticky liquid in
88% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.35 (s, 3H),
2.90 (t, J = 7.2 Hz, 2H), 3.22 (s, 3H), 3.46 (t, J = 7.2 Hz, 2H),
7.20 (t, J = 7.8 Hz, 2H), 7.31-7.53 (m, 10H); 13C NMR (CDCl3,
Me4Si, 75 MHz) δ 21.0, 32.7, 58.4, 73.0, 125.8, 126.8 (2C), 126.9,
128.1 (2C), 128.6, 129.2 (2C), 129.4 (2C), 130.1, 134.8, 136.9,
137.7, 138.9, 141.6, 142.6; IR (KBr) 3052, 3024, 2976, 2922,
2870, 2824, 1600, 1518, 1484, 1444, 1383, 1185, 1113, 1021, 1011,
967, 897, 811, 772, 703 cm-1; HRMS (EI) calcd for C22H22O
302.1671, found 302.1662.
2p: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2p as a light yellow sticky liquid in
86% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.36 (s, 3H),
2.92 (t, J = 7.5 Hz, 2H), 3.52 (t, J = 7.5 Hz, 2H), 3.85-3.88 (m,
2H), 5.09-5.21 (m, 2H), 5.76-5.89 (m, 1H), 7.21 (d, J = 7.8 Hz,
2H), 7.31-7.38 (m, 7H), 7.40-7.53 (m, 3H); 13C NMR (CDCl3,
Me4Si, 75 MHz) δ 21.0, 32.9, 70.6, 71.6, 116.7, 125.7, 126.8 (2C),
126.9, 128.1 (2C), 128.56, 129.2 (2C), 129.4 (2C), 130.2, 134.7,
134.8, 136.9, 137.7, 138.9, 141.6, 142.6; IR (KBr) 3054, 3023,
2921, 2858, 1600, 1518, 1498, 1484, 1443, 1385, 1347, 1249, 1138,
1099, 991, 922, 811, 772, 703 cm-1; HRMS (EI) calcd for
C24H24O 328.1827, found 328.1824.
2q: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 40:1)
afforded the title compound 2q as a light yellow sticky liquid in
84% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.91 (t, J =
7.2 Hz, 2H), 3.24 (s, 3H), 3.47 (t, J = 7.2 Hz, 2H), 7.34-7.45 (m,
9H), 7.48-7.53 (m, 3H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ
32.7, 58.4, 72.9, 125.7, 127.1, 128.2 (4C), 128.6, 128.8 (2C), 129.1
(2C), 130.2, 133.2, 135.6, 137.7, 139.0, 141.3, 142.8; IR (KBr)
3056, 3026, 2977, 2925, 2871, 2825, 1599, 1575, 1556, 1479, 1444,
1179, 1113, 1093, 1010, 968, 898, 816, 771, 752, 734, 703 cm-1
HRMS (EI) calcd for C21H19OCl 322.1124, found 322.1121.
;
2w: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 50:1)
afforded the title compound 2w as a colorless sticky liquid in
67% yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.94 (t, J =
7.5 Hz, 2H), 3.53 (t, J = 7.5 Hz, 2H), 3.84 (s, 3H), 3.89 (dt, J =
4.2, 1.2 Hz, 2H), 5.10-5.23 (m, 2H), 5.78-5.89 (m, 1H),
6.94-6.98 (m, 2H), 7.27-7.34 (m, 3H), 7.38-7.45 (m, 4H),
7.52 (dd, J = 7.8, 1.8 Hz, 1H), 7.58-7.61 (m, 2H); 13C NMR
(CDCl3, Me4Si, 75 MHz) δ 33.0, 55.3, 70.7, 71.6, 113.5 (2C),
116.7, 125.7, 127.0 (2C), 127.1, 128.7 (2C), 129.0, 130.2, 130.3
(2C), 133.9, 134.7, 135.4, 139.0, 140.7, 142.3, 158.6; IR (KBr)
3058, 3030, 2955, 2932, 2907, 2854, 2830, 1610, 1574, 1515,
1481, 1463, 1290, 1245, 1177, 1097, 1030, 924, 834, 762, 698
cm-1; HRMS (EI) calcd for C24H24O2 344.1776, found
344.1778.
2r: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 100:1)
afforded the title compound 2r as a colorless sticky liquid in 77%
yield. 1H NMR (CDCl3, Me4Si, 300 MHz) δ 2.92 (t, J = 7.2 Hz,
2H), 3.52 (t, J = 7.2 Hz, 2H), 3.88 (dt, J = 5.4, 1.2 Hz, 2H),
5.10-5.22 (m, 2H), 5.77-5.90 (m, 1H), 7.33-7.45 (m, 9H),
7.48-7.54 (m, 3H); 13C NMR (CDCl3, Me4Si, 75 MHz) δ 33.0,
70.6, 71.6, 116.8, 125.8, 127.1, 128.2 (4C), 128.6, 128.9 (2C),
129.2 (2C), 130.4, 133.2, 134.7, 135.7, 137.7, 139.1, 141.3, 142.9;
IR (KBr) 3058, 3025, 2927, 2856, 1599, 1479, 1443, 1381, 1348,
1137, 1094, 1015, 1000, 924, 817, 771, 703 cm-1; HRMS (EI)
calcd for C23H21OCl 348.1281, found 348.1285.
2s: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 20:1)
2908 J. Org. Chem. Vol. 75, No. 9, 2010

Li and Liu
JOCArticle
2x: Purification of the crude product by flash chromatogra-
phy on silica gel (eluent: petroleum ether/ethyl acetate = 100:1
to 50:1) afforded the title compound 2x as a white solid in 66%
(form Z-1j) or 67% (from E-1j) yield. Mp 60-62 °C; 1H NMR
(CDCl3, Me4Si, 300 MHz) δ 1.88 (s, 3H), 2.66 (t, J = 7.2 Hz,
2H), 3.22 (s, 3H), 3.43 (t, J = 7.2 Hz, 2H), 7.18-7.23 (m, 4H),
7.31-7.42 (m, 8H); 13C NMR (CDCl3, Me4Si, 100 MHz) δ 18.9,
33.7, 58.3, 73.0, 126.5, 126.6, 126.8, 128.0 (2C), 128.4 (2C),
128.9, 129.3 (2C), 129.4 (2C), 133.7, 135.6, 140.4, 140.9, 142.4,
142.6; IR (KBr) 3060, 3022, 2970, 2958, 2928, 2864, 2827, 1600,
1469, 1442, 1405, 1382, 1184, 1111, 1101, 1070, 1023, 1003, 970,
925, 833, 763, 702 cm-1; HRMS (EI) calcd for C22H22O
302.1671, found 302.1669.
Acknowledgment. We thank the National Natural Science
Foundation of China (Grant Nos. 20872163, 20732008, and
20821002), the Chinese Academy of Science, Science and
Technology Commission of Shanghai Municipality (Grant
No. 08QH14030), and the Major State Basic Research
Development Program (Grant No. 2006CB806105) for finan-
cial support.
Supporting Information Available: Experimental details,
spectroscopic characterization of all new compounds, and
X-ray crystallography of compound 2x. This material is avail-
able free of charge via the Internet at http://pubs.acs.org.
J. Org. Chem. Vol. 75, No. 9, 2010 2909