Synthesis of quaternary carbon centered chromans from the reactions of ethyl 2-(2-hydroxyaryl)-2-oxoacetates with allenic ester or allenic sulfone catalyzed by tertiary phosphine and SPTS

Article abstract of DOI:10.1016/j.tet.2012.04.036

Cyclization reactions of ethyl 2-(2-hydroxyaryl)-2-oxoacetates with ethyl 2,3-butadienoate and allenylsulfone proceeded smoothly in the presence of tertiary phosphine and sodium p-toluenesulfinate (SPTS) to give the corresponding quaternary carbon centere

Full text of DOI:10.1016/j.tet.2012.04.036

Tetrahedron 68 (2012) 4782e4790
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Synthesis of quaternary carbon centered chromans from the reactions of ethyl
2-(2-hydroxyaryl)-2-oxoacetates with allenic ester or allenic sulfone catalyzed
by tertiary phosphine and SPTS
,b,
Fangle Hu a, Xiaoyang Guan b, Min Shi a
*
a Key Laboratory for Advanced Materials and Institute of Fine Chemicals, School of Chemistry & Molecular Engineering, East China University of Science and Technology,
130 Mei-Long Road, Shanghai 200237, China
b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Cyclization reactions of ethyl 2-(2-hydroxyaryl)-2-oxoacetates with ethyl 2,3-butadienoate and alle-
nylsulfone proceeded smoothly in the presence of tertiary phosphine and sodium p-toluenesulfinate
(SPTS) to give the corresponding quaternary carbon centered chromans in moderate to good yields under
mild conditions, which provides an alternative efficient approach for the synthesis of biologically active
chroman products.
Received 7 February 2012
Received in revised form 31 March 2012
Accepted 1 April 2012
Available online 19 April 2012
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
p-toluenesulfinate (SPTS) to give the corresponding quaternary
carbon centered chromans in moderate to good yields under mild
2H-1-Chromenes or chromans are attractive targets of oxygen-
ated heterocycles that have attracted much synthetic interest be-
cause of their wide-ranging biological activity of naturally
occurring representatives.1,2 Thus far, the synthesis of 2H-1-
chromenes or chromans has achieved significant progress during
the last decade. Among these synthetic methods the reactions of
salicyclic aldehydes with various conjugated olefins such as acry-
conditions.
2. Results and discussion
2.1. The [4D2] annulation reaction of ethyl 2-(2-hydroxyaryl)-
2-oxoacetates with allenic ester
late derivatives,
a,b-unsaturated ketones to give different
substituted chromenes or chromans have made huge successes.3
Moreover, the reactions of salicylaldehydes or salicylaldimines
with allenic ketones or esters4e6 have also been disclosed recently.
For example, Huang and co-workers recently have reported
phosphine-catalyzed interesting domino reactions of salicyl
N-thiophosphinyl imines with electron-deficient allenes, affording
cis-2,3-dihydrobenzofurans or chroman derivatives in good yields
under mild conditions.7a,7b During our ongoing investigation on the
phosphorus or nitrogen containing Lewis base-catalyzed domino
cyclization of salicylaldehydes or salicylaldimines with electron-
deficient olefins as well as allenic ketones or esters, we found
that the nucleophilicity and electronic property of the employed
phosphorus or nitrogen containing Lewis base can significantly
affect the reaction outcomes even under the same reaction condi-
tions.6 Herein we wish to report the cyclization reactions of ethyl
2-(2-hydroxyaryl)-2-oxoacetates with allenic ester and alle-
nylsulfone catalyzed by tris(4-fluorophenyl)phosphine or sodium
Initially we examined the reactions of ethyl 2-(2-hydroxy-4-
methoxyphenyl)-2-oxoacetate 1a (0.2 mmol, 1.0 equiv) with ethyl
2,3-butadienoate (0.4 mmol, 2.0 equiv) catalyzed by various phos-
phorus and nitrogen containing Lewis bases (20 mol %) in tetra-
hydrofuran (THF) (2.0 mL) at 20 ꢀC (room temperature). The results
are summarized in Table 1. Using triphenylphosphine (PPh3), tri-
butylphosphine (PnBu3), 1,4-diazabicyclo[2,2,2]octane (DABCO),
4-N,N-dimethylaminopyridine (DMAP), methyldiphenylphosphine
(PPh2Me), and dimethylphenylphosphine (PPhMe2) as the Lewis
base promoters, it was found that the corresponding chroman de-
rivative 2a was formed in up to 73% yield as E- and Z-isomeric
mixtures only in the presence of PPhMe2 after 144 h, while the
other Lewis base promoters were less effective in this reaction
(Table 1, entries 1e6). Raising the reaction temperature to 60 ꢀC did
not facilitate the formation of 2a using PPhMe2 as a Lewis base
promoter (Table 1, entry 7). In toluene using PPhMe2 or PPh2Me as
a Lewis base promoter, we found that the reaction became sluggish,
giving 2a in 10% and 5% yields after 168 h, respectively (Table 1,
entries 8 and 9). Pleasingly, PPh3 could catalyze the reaction in
toluene efficiently to give 2a in 64% yield as E- and Z-isomeric
* Corresponding author. Fax: þ86 21 64166128; e-mail address: Mshi@mail.
sioc.ac.cn (M. Shi).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2012.04.036

F. Hu et al. / Tetrahedron 68 (2012) 4782e4790
4783
Table 1
Screening of catalysts and solvents for the reaction
O
HO CO2Et
O
6
CO2Et
1
2
5
CO2Et
catalyst (0.2 equiv)
+
CO2Et
solvent, temp, additive
4
H3CO
OH
H3CO
3
H
1a
2a
Entrya
Catalyst
Solvent
Temp (ꢀC)
Additive
Time (h)
Yieldb (%)
2a (E:Z)
1
2
3
4
5
6
7
8
PPh3
THF
THF
THF
THF
THF
THF
THF
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
THF
25
25
25
25
25
25
60
25
25
25
25
25
60
60
60
80
60
60
60
60
60
/
/
/
/
/
/
/
/
24
24
24
24
48
144
48
168
168
120
48
48
48
48
48
48
48
48
48
5 (Z)
Trace
Trace
2 (Z)
25 (Z)
73 (1:1.1)
Trace
10 (Z)
5 (Z)
64 (1:1.1)
36 (1:1.3)
NR
53 (1:1.1)
Trace
84 (1:1.3)
28 (1:3)
Complex
Complex
21 (1:1)
12 (1:1)
Trace
PnBu3
DABCO
DMAP
PPh2Me
PPhMe2
PPhMe2
PPhMe2
PPh2Me
PPh3
9
/
/
10
11
12
13
14
15
16
17
18
19
20
21
PPh3
PPh3
PPh3
LiCIO4
Zn(OTf)2
/
/
/
/
CH3CO2H
PhCO2H
/
/
/
P(p-CH3OC6H4)3
P(p-FC6H4)3
P(p-FC6H4)3
P(p-FC6H4)3
P(p-FC6H4)3
P(p-FC6H4)3
P(p-FC6H4)3
P(p-FC6H4)3
DCE
MeCN
48
48
a
All reactions were carried out with 1a (0.2 mmol) and ethyl 2,3-butadienoate (0.4 mmol) in the presence of catalyst.
Isolated yield.
b
mixtures after 120 h at room temperature (Table 1, entry 10).
solvent effects have been also examined using P(p-FC6H4)3 as the
catalyst in THF and 1,2-dichloroethane (DCE), affording 2a in 21%
and 12% yields, respectively, and almost no reaction occurred in
acetonitrile (MeCN) (Table 1, entries 19e21). Therefore, the best
reaction conditions have been determined as that P(p-FC6H4)3
(20 mol %) should be used as the catalyst and the reaction should be
carried out in toluene at 60 ꢀC without any additive.
With the identification of the optimized reaction conditions, we
next examined the substrate scope of this reaction using a variety
of ethyl 2-(2-hydroxyaryl)-2-oxoacetates 1 to react with ethyl
2,3-butadienoate under these optimized conditions. The results are
shown in Table 2. Whether an electron-withdrawing or electron-
donating group was introduced into the benzene ring of ethyl
2-(2-hydroxyaryl)-2-oxoacetate 1, all of the reactions proceeded
smoothly to give the corresponding [4þ2] annulation products 2 in
good total yields as E- and Z-isomeric mixtures after 48 h (Table 2,
Adding some additives such as LiClO4 or Zn(OTf)2 did not improve
the reaction outcome and raising the reaction temperature to 60 ꢀC
did not increase the yield of 2a under otherwise identical condi-
tions (Table 1, entries 11e13). Next, we attempted to examine other
triarylphosphines in above reaction and subsequently to further
optimize the reaction conditions. We found that P(p-CH3OC6H4)3
was totally ineffective in this reaction, but P(p-FC6H4)3 could give
2a in 84% yield as E- and Z-isomeric mixtures after 48 h upon
heating at 60 ꢀC in toluene, suggesting that less nucleophilic
phosphine could efficiently catalyze the reaction to give the desired
product in good yield (Table 1, entries 14 and 15). Raising the
temperature to 80 ꢀC using P(p-FC6H4)3 as the catalyst decreased
the yield of 2a significantly (Table 1, entry 16). Adding some addi-
tives such as CH3CO2H or PhCO2H afforded complex product mix-
tures under the standard conditions (Table 1, entries 17 and 18). The
Table 2
Substrate scope of the [4þ2] annulation reaction of ethyl 2-(2-hydroxyaryl)-2-oxoacetates with allenic ester in the presence of P(p-FC6H4)3
O
HO CO2Et
6
CO2Et
R 5
R
CO2Et
P(p-FC6H4)3 (20 mol %)
toluene, 60 oC, 48 h
1
+
CO2Et
4
2
O
H
OH
3
2
1
Entrya
R
Yieldb (%)
Yieldb (%)
1
2
3
4
5
6
7
4-Me
4-Cl
E-2b, 43
E-2c, 47
E-2d, 44
E-2e, 41
E-2f, 42
E-2g, 41
E-2h, 48
Z-2b, 44
Z-2c, 31
Z-2d, 50
Z-2e, 41
Z-2f, 36
Z-2g, 42
Z-2h, 49
5-Me
5-tBu
5-MeO
3-Me
H
a
All reactions were carried out with 1 (0.2 mmol) and ethyl 2,3-butadienoate (0.4 mmol) in the presence of P (p-FC6H4)3 in toluene (2.0 mL) at 60 ꢀC within 48 h.
Isolated yields.
b

4784
F. Hu et al. / Tetrahedron 68 (2012) 4782e4790
entries 1e6). As for substrate 1h, in which the benzene ring did not
have a substituent, the desired product 2h was obtained in 97%
total yield (Table 2, entry 7). It should be also noted that all these
two E- and Z-isomers could be easily separated by silica gel column
chromatography (see Supplementary data for the details).
Initially the Lewis base promoter P(p-FC6H4)3 acts as a nucleo-
philic trigger, producing the zwitterionic intermediate A or
another resonance-stabilized zwitterionic intermediate B,
which undergoes the nucleophilic attack with ethyl 2-(2-
hydroxyaryl)-2-oxoacetate
1 to give the corresponding in-
To improve the Z/E selectivity of the product, benzyl or tert-butyl
2,3-butadienoates were employed in this reaction under these
optimized conditions. However, no improvements on the E/Z ratios
were observed, affording the desired products 2i and 2j in 55% yield
(E/Z¼1/1.4) and 33% yield (E/Z¼1/2), respectively (Scheme 1).
termediate C. Subsequent proton transferring produces in-
termediate D. The cyclization of the resulting intermediate D
affords intermediate E, which is followed by elimination of
P(p-FC6H4)3 to produce chroman derivative 2 and regenerates
P(p-FC6H4)3 promoter.
O
HO CO2Et
CO2R'
CO2R'
CO2Et
P(p-FC6H4)3 (20 mol %)
toluene, 60 oC, 48 h
+
H3CO
OH
H3CO
O
1a
2
H
2i, R' = Bn, 55% yield, E/Z = 1/1.4
t
2j
, R' = Bu, 33% yield, E/Z = 1/2
Scheme 1. Using benzyl or tert-butyl 2,3-butadienoates in the reaction.
Their structures have been determined by 1H and 13C NMR
spectroscopic data, MS, and HRMS analyses. The configuration of
Z-2c has been unambiguously determined by X-ray diffraction. The
ORTEP drawing of Z-2c is shown in Fig. 1 and its CIF data are pre-
sented in the Supplementary data. Therefore, the configurations of
E- and Z-isomers of 2 could be identified on the basis of their 1H
NMR spectroscopic data with those of Z-2c (see Supplementary
data for the details).
2.2. The [4D2] annulation reaction of ethyl 2-(2-hydroxyaryl)-
2-oxoacetates with allenylsulfone
In order to extend the scope of this interesting [4þ2] annulation
reaction, allenylsulfone 3 was also used as another substrate to react
with ethyl 2-(2-hydroxyphenyl)-2-oxoacetates 1. To the best of our
knowledge, allenylsulfones have been successfully used as dien-
ophiles8 and dipolarophiles9 in organic synthesis as well as allenyl
p
-bond in PausoneKahnd reactions.10 However, their behaviors as
precursors of 1,3-dipoles have scarcely been exploited. The first re-
port on the use of allenylsulfones as precursors of 1,3-dipoles was
described by Padwa et al.,11 in which the reactions with acrylonitrile
or methyl vinyl ketone catalyzed by ionic species (KCN, NaNO2 or
NaSO2Ph) in polar solvent such as THF have been extensively studied.
Later, Ruano et al. reported the results obtained from the highly
stereoselective reactions of furan-2(5H)-ones with allenylsulfones in
the presence of different nucleophilic catalysts such as PPh3, NaNO2,
or sodium p-toluenesulfinate (SPTS), yielding the corresponding
5-sulfonyl-substituted adducts in good yields.12 Therefore, we sub-
sequentlyutilized tertiaryphosphines and sodiump-toluenesulfinate
(SPTS) to catalyze the [4þ2] annulation reaction of allenylsulfone 3
with ethyl 2-(2-hydroxyaryl)-2-oxoacetates 1. The reaction of ethyl 2-
(2-hydroxy-4-methoxyphenyl)-2-oxoacetate 1a with allenylsulfone
3 was first conducted in the presence of various phosphines. How-
ever, none of the desired product could be obtained, because alle-
nylsulfone is not stable in the presence of nucleophilic phosphines
under the standard conditions.12 We subsequently examined the
reaction of 1a (0.1 mmol,1.0 equiv) with allenylsulfone 3 (0.15 mmol,
1.5 equiv) in the presence of SPTS (50 mol %) in THF (2 mL) at room
temperature. The results are summarized in Table 3. To our delight,
we found that the desired product 4a was obtained in 31% yield as
a single stereoisomer with Z-configuration along with some un-
identified byproducts within 24 h. These byproducts could not be
separated by silica gel column chromatography and we could not
determine their structure at this stage (Table 3, entry 1). We believed
that sulfonyl group isa stericallybulkygroupcompared withtheester
group, thus only Z isomer was obtained in this case. Increasing the
employedamountofallenylsulfonecould furtherimprove theyield of
4a to 48% (Table 3, entries 2 and 3). However, increasing ordecreasing
Fig. 1. X-ray crystal structure of Z-2c.
The mechanism of this interesting [4þ2] annulation reaction
to give quaternary carbon centered chromans has not been
unequivocally established, but a rational explanation is pro-
posed in Scheme 2 on the basis of previous literature.4e7

F. Hu et al. / Tetrahedron 68 (2012) 4782e4790
4785
CO2Et
CO2Et
CO2Et
PAr3
+
PAr3
PAr3
B
A
O
PAr3 = P(p-FC6H4)3
CO2Et
R
OH
1
CO2Et
HO
CO2Et
O
CO2Et
PAr3
H+ transfer
CO2Et
R
R
PAr3
O
OH
D
C
HO CO2Et
O
HO CO2Et
R
R
CO2Et
CO2Et
O
PAr3
E
H
2
Scheme 2. A plausible mechanism for the PAr3-catalyzed [4þ2] annulation reaction.
Table 3
Screening of catalysts and solvents for the [4þ2] annulation reaction of ethyl 2-(2-hydroxyaryl)-2-oxoacetates with allenylsulfone
HO CO2Et
O
H
O
O
S
O
H3CO
O
CO2Et
+
SPTS (x equiv)
solvent, additive
Cl
O
S
H3CO
OH
1a
3 (y equiv)
4a
Cl
Entrya
y
x
Additive
Solvent
Time (h)
Yielde (%)
1
2
3
4
1.5
2
3
3
3
2
3
3
3
3
3
3
3
3
3
3
3
3
0.5
0.5
0.5
0.3
0.7
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
/
/
/
/
/
/
/
/
THF
THF
THF
THF
THF
THF
THF
THF
THF
THF
Toluene
Dioxane
THF/H2O (10/1)
DCM
DMF
Fluorobenzene
Chloroform
Benzene
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
31
36
48
34
41
20
39
Trace
Trace
Trace
4
40
25
Trace
Trace
Trace
Trace
Trace
5
6b
7b
8c
9
15-C-5
/
/
/
/
/
/
/
10d
11
12
13
14
15
16
17
18
/
18-C-6
a
The reaction was carried out by employing 1a (0.1 mmol), 3 (y mmol), and solvent (2 mL) at room temperature within 24 h.
b
c
The reaction was carried out at 0 ꢀC.
The reaction was conducted in 1 mL THF.
Compound 3 (0.3 mmol) in THF (1 mL) was added dropwise to 1a in THF (1 mL).
Isolated yield.
d
e
the employed amountofSPTSdid not improve theyield of 4a(Table 3,
reaction temperature to 0 ꢀC did not improve the yield of 4a either
(Table 3, entries 6 and 7). Carrying out the reaction in 1.0 mL of THF
gave trace of 4a (Table 3, entry 8). Using 15-crown-5 (15-C-5) as an
additive or adding 3 dropwise with a syringe pump also gave trace of
4a (Table 3, entries 9 and 10). The solvent effects have been examined
entries 4 and 5). This result suggested that the employed amount of
allenylsulfone and the catalyst were the key factors that influence the
reaction outcomes, increasing or decreasing the employed amount of
allenylsulfone or the catalyst decreased the yield of 4a. Lowering the

4786
F. Hu et al. / Tetrahedron 68 (2012) 4782e4790
using SPTS as the catalyst in toluene, 1,4-dioxane, and mixed solvent
(THF/H2O), but 4a was obtained in 4%, 40% and 25% yields, re-
spectively (Table 3, entries 11e13). Almost no reaction occurred in
dichloromethane (DCM), DMF, fluorobenzene, chloroform, or ben-
zene with additive of 18-crown-6 (18-C-6) (Table 3, entries 14e18),
implying that solvent effect was also the key factor for the [4þ2] re-
action and THF is the best solvent for this reaction.
Having identified the optimal reaction conditions, we next set
out to examine the scope and limitations of this reaction using 1
having different substituents on the benzene rings with 3, and the
results are summarized in Table 4. As can be seen in Table 4,
whether an electron-withdrawing or electron-donating group was
introduced at meta or para position of the benzene ring of 1, the
reactions proceeded smoothly to give the corresponding products 4
in moderate yields as Z-configuration at room temperature, sug-
could be identified on the basis of their 1H NMR spectroscopic data
with those of 4d as well (see Supplementary data for the details).
A plausible mechanism for the SPTS-catalyzed tandem reactions
between allenylsulfone 3 and ethyl 2-(2-hydroxyaryl)-2-oxoacetate
1 is proposed in Scheme 3. The salt SPTS as a nucleophile reacts
with allenylsulfone to produce the zwitterionic intermediate F or
another resonance-stabilized zwitterionic intermediate G, which
undergoes the nucleophilic attack with ethyl 2-(2-hydroxyphenyl)-
2-oxoacetate 1 to give the corresponding intermediate H. Sub-
sequent proton transferring produces intermediate I. The cycliza-
tion of the resulting intermediate I affords intermediate J, which is
followed by elimination of SPTS to produce chroman derivative 4
and regenerates SPTS promoter.
In this paper, we have presented a fairly efficient [4þ2] annu-
lation reaction of allenic ester or allenylsulfone with ethyl 2-(2-
Table 4
Substrate scope of the [4þ2] annulation reaction in the presence of SPTS
HO CO2Et
O
R
H
O
6
O
S
O
R 5
CO2Et
STPS (50 mol %)
THF, rt, 24 h
1
O S O
+
Cl
4
2
OH
3
1
3
4
Cl
Entrya
R
Yieldb (%)
1
2
3
4
5
6
7
4-Me
4-Cl
5-Me
5-tBu
H
4b, 38
4c, 30
4d, 31
4e, 30
4f, 33
4g, 32
4h, 34
4,5-Me2
5-Et
a
All reactions were carried out with 1 (0.1 mmol) and allenic sulfone 3 (0.3 mmol) in the presence of SPTS in THF (2.0 mL) at room temperature within 24 h.
Isolated yields.
b
gesting that the substituent on the benzene of 1 did not have sig-
hydroxyaryl)-2-oxoacetates catalyzed by tertiary phosphine and
SPTS, respectively, which provides an easy access to the synthesis of
the corresponding quaternary carbon centered chroman de-
rivatives under mild reaction conditions in moderate to good yields.
Efforts are in progress to elucidate the mechanistic details of this
reaction and to disclose its scope and limitations as well as the
application in the preparation of biologically active substances.
nificant impact on the reaction outcome (Table 4, entries 1e7).
Their structures were determined by 1H and 13C NMR spectro-
scopic data, MS, and HRMS analyses. The Z-configuration of 4d has
been unambiguously assigned by X-ray diffraction. The ORTEP
drawing of 4d is shown in Fig. 2 and its CIF data are presented in the
Supplementary data as well. Therefore, the Z-configurations of 4
3. Experimental section
3.1. General remarks
1H and 13C NMR spectra were recorded at the 300 and 75 MHz
or the 400 and 100 MHz, respectively. Mass and HRMS spectra were
recorded by EI, ESI, or MALDI method. Organic solvents used were
dried by standard methods when necessary. Satisfactory CHN mi-
croanalyses were obtained with an analyzer. Commercially
obtained reagents were used without further purification. All these
reactions were monitored by TLC with silica gel coated plates. Flash
column chromatography was carried out using silica gel at in-
creased pressure.
3.2. General procedure for the preparation of ethyl 2-(2-
hydroxyaryl)-2-oxoacetates
The substrates 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, and 1j were syn-
Fig. 2. X-ray crystal structure of 4d.
thesized following a known literature procedure.1 To a solution of

F. Hu et al. / Tetrahedron 68 (2012) 4782e4790
4787
p-ClC6H4SO2
SO2Ar
O2STol
SO2Ar
O2STol
SO2Na +
SPTS
3
F
G
O
CO2Et
R
OH
CO Et
HO
CO2Et
O
2
SO2Ar
O2STol
H+ transfer
SO2Ar
R
R
O2STol
O
OH
I
H
HO CO2Et
O
HO CO2Et
O
R
R
SO2Ar
H
SO2Ar
J
4
O2STol
Scheme 3. A plausible reaction mechanism.
phenol (20 mmol) in CH2Cl2 (25 mL) at ꢁ5 ꢀC was added TiCl4
(4.2 g, 22 mmol). Ethyl chlorooxoacetate (3.0 g, 22 mmol) was
added over 3 min while maintaining the temperature below ꢁ5 ꢀC.
The resulting mixture was stirred at ꢁ15 ꢀC to ꢁ5 ꢀC for 2 h for
completion. The reaction was then diluted with CH2Cl2 (25 mL) and
poured into previously cooled 1.0 M HCl (75 mL). After concd HCl
(2.5 mL) was added, the aqueous layer was separated and extracted
with CH2Cl2. The combined organic layer was washed with 1.0 M
HCl and 20% NaCl aqueous solution. The organic layer was con-
centrated and purified by column chromatography on silica gel.
4.28e4.36 (m, 1H, OCH2), 5.69 (s, 1H, ]CH2), 6.56 (d, J¼2.0 Hz, 1H,
Ar), 6.62 (dd, J¼8.8 Hz, J¼2.0 Hz, 1H, Ar), 7.19 (d, J¼8.8 Hz, 1H, Ar).
13C NMR (CDCl3, 100 MHz, TMS)
d 14.0, 14.3, 34.1, 55.5, 59.9, 62.9,
69.8, 100.0, 101.9, 109.7, 116.0, 126.3, 152.2, 161.2, 164.2, 167.2, 173.8.
IR (CH2Cl2) n 844, 1037, 1133, 1160, 1197, 1243, 1374, 1507, 1617, 1658,
1707, 1733, 2933, 2981, 3486 cmꢁ1. MS (ESI) m/e 319.0 (MþꢁOH).
HRMS (ESI) calcd for C17H20NaO7: 359.1101, found: 359.1111.
3.4.2. Compound Z-2a. Yield: 48%, 29 mg; a yellow oil. 1H NMR
(CDCl3, 400 MHz, TMS)
d
1.22 (t, J¼7.2 Hz, 3H, CH3), 1.30 (t, J¼7.2 Hz,
3H, CH3), 2.89 (d, J¼14.8 Hz, 1H, CH2), 2.94 (d, J¼14.8 Hz, 1H, CH2),
3.80 (s, 3H, CH3), 3.92 (s, 1H, OH), 4.13e4.23 (m, 3H, CH2),
4.28e4.34 (m, 1H, CH2), 5.10 (s, 1H, ]CH), 6.63 (dd, J¼8.4 Hz,
J¼2.8 Hz,1H, Ar), 6.73 (d, J¼2.8 Hz,1H, Ar), 7.17 (d, J¼8.4 Hz,1H, Ar).
3.3. General procedure for the tandem reaction of allenic
ester with ethyl 2-(2-hydroxyaryl)-2-oxoacetates
Into a 25 mL oven-dried reaction flask under Ar gas protection
were added ethyl 2-(2-hydroxyphenyl)-2-oxoacetates (0.2 mmol),
tris(4-fluorophenyl)phosphine (0.04 mmol), toluene (2 mL), and
allenic ester (0.4 mmol). The reaction mixture was stirred at 60 ꢀC
for 48 h, then the solvent was removed under reduced pressure and
the residue was purified by flash column chromatography.
13C NMR (CDCl3, 100 MHz, TMS)
d 13.9, 14.3, 39.0, 55.5, 59.7, 63.0,
70.1, 98.2, 101.9, 110.4, 115.3, 126.0, 152.2, 159.6, 161.3, 164.4, 173.6.
IR (CH2Cl2)
n 858, 954, 1038, 1124, 1217, 1373, 1588, 1739, 2359,
2850, 2925, 3479 cmꢁ1. MS (ESI) m/e 337.0 (Mþþ1). HRMS (ESI)
calcd for C17H20NaO7: 359.1101, found: 359.1105.
3.4.3. Compound E-2b. Yield: 43%, 27 mg; a yellow oil. 1H NMR
3.4. General procedure for the tandem reaction of allenic
sulfone with ethyl 2-(2-hydroxyaryl)-2-oxoacetates
(CDCl3, 400 MHz, TMS)
d
1.20 (t, J¼7.2 Hz, 3H, CH3), 1.28 (t, J¼7.2 Hz,
3H, CH3), 2.34 (s, 3H, CH3), 3.39 (d, J¼15.6 Hz, 1H, CH2), 3.95 (s, 1H,
OH), 3.97 (d, J¼15.6 Hz,1H, CH2), 4.09e4.19 (m, 3H, CH2), 4.28e4.34
(m, 1H, CH2), 5.68 (s, 1H, ]CH), 6.85 (s, 1H, Ar), 6.87 (d, J¼8.0 Hz,
1H, Ar) 7.17 (d, J¼8.0 Hz, 1H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
Into a 25 mL oven-dried reaction flask under Ar gas protection
were added ethyl 2-(2-hydroxyphenyl)-2-oxoacetates (0.1 mmol),
allenic sulfone (0.3 mmol), THF (2 mL), and SPTS (0.05 mmol). The
reaction mixture was stirred at room temperature for 24 h, then the
solvent was removed under reduced pressure and the residue was
purified by flash column chromatography.
d
13.9, 14.3, 21.2, 34.0, 59.8, 62.9, 69.9, 99.7, 117.2, 120.8, 124.0, 125.2,
140.7, 151.0, 164.3, 167.3, 173.7. IR (CH2Cl2)
n 845, 1044, 1118, 1137,
1245, 1304, 1354, 1374, 1393, 1619, 1657, 1705, 1737, 2926, 2982,
3485 cmꢁ1. MS (ESI) m/e 303.2 (MþꢁOH). HRMS (ESI) calcd for
C17H20NaO6: 343.1152, found: 343.1154.
3.4.1. Compound E-2a. Yield: 36%, 22 mg; a yellow oil. 1H NMR
(CDCl3, 400 MHz, TMS)
3H, CH3), 3.40 (d, J¼15.6 Hz,1H, CH2), 3.80 (s, 3H, OCH3), 3.93 (s, 1H,
OH), 3.95 (d, J¼15.6 Hz, 1H, CH2), 4.10e4.20 (m, 3H, OCH2),
d
1.21 (t, J¼7.2 Hz, 3H, CH3), 1.28 (t, J¼7.2 Hz,
3.4.4. Compound Z-2b. Yield: 44%, 28 mg; a yellow solid, Mp:
102e104 ꢀC. 1H NMR (CDCl3, 300 MHz, TMS)
d
1.22 (t, J¼7.2 Hz, 3H,
CH3), 1.30 (t, J¼7.2 Hz, 3H, CH3), 2.34 (s, 3H, CH3), 2.89 (d, J¼15.9 Hz,

4788
F. Hu et al. / Tetrahedron 68 (2012) 4782e4790
1H, CH2), 2.94 (d, J¼15.9 Hz, 1H, CH2), 3.99 (s, 1H, OH), 4.13e4.23
(m, 3H, CH2), 4.29e4.35 (m, 1H, CH2), 5.08 (s, 1H, ]CH), 6.88 (d,
J¼8.1 Hz, 1H, Ar), 7.02 (s, 1H, Ar), 7.16 (d, J¼8.1 Hz, 1H, Ar). 13C NMR
3493 cmꢁ1. MS (ESI) m/e 345.3 (MþꢁOH). HRMS (ESI) calcd for
C20H26NaO6: 385.1622, found: 385.1622.
(CDCl3, 100 MHz, TMS)
d
13.9, 14.3, 21.1, 38.9, 59.6, 63.0, 70.2, 98.1,
3.4.10. Compound Z-2e. Yield: 41%, 30 mg; a yellow solid, Mp:
117.8, 120.3, 124.1, 125.0, 141.0, 151.1, 159.5, 164.4, 173.5. IR (CH2Cl2)
n
104e106 ꢀC. 1H NMR (CDCl3, 300 MHz, TMS)
d
1.23 (t, J¼7.2 Hz, 3H,
818, 976, 1017, 1103, 1126, 1167, 1215, 1418, 1619, 1660, 1698, 1731,
2905, 2929, 2982, 3434 cmꢁ1. MS (ESI) m/e 321.2 (Mþþ1). HRMS
(ESI) calcd for C17H20NaO6: 343.1152, found: 343.1157.
CH3), 1.28e1.30 (m, 12H, CH3), 2.90 (d, J¼16.2 Hz, 1H, CH2), 2.95 (d,
J¼16.2 Hz, 1H, CH2), 4.04 (s, 1H, OH), 4.14e4.25 (m, 3H, CH2),
4.27e4.35 (m, 1H, CH2), 5.07 (s, 1H, ]CH), 7.12 (d, J¼8.4 Hz, 1H, Ar),
7.27 (d, J¼2.4 Hz, 1H, Ar), 7.36 (dd, J¼8.4 Hz, J¼2.4 Hz, 1H, Ar). 13C
3.4.5. Compound E-2c. Yield: 47%, 32 mg; a yellow oil. 1H NMR
NMR (CDCl3, 75 MHz, TMS) d 13.9, 14.3, 31.3, 34.4, 39.1, 59.6, 63.0,
(CDCl3, 400 MHz, TMS)
d
1.20 (t, J¼7.2 Hz, 3H, CH3), 1.28 (t,
70.5, 97.8, 116.9, 121.7, 122.4, 127.6, 146.2, 149.1, 159.6, 164.5, 173.6.
J¼7.2 Hz, 3H, CH3), 3.26 (d, J¼16.0 Hz, 1H, CH2), 4.02 (s, 1H, OH),
4.07 (d, J¼16.0 Hz, 1H, CH2), 4.11e4.20 (m, 3H, CH2), 4.28e4.36 (m,
1H, CH2), 5.70 (s, 1H, ]CH), 7.04e7.05 (m, 2H, Ar), 7.26 (d,
IR (CH2Cl2) n 827, 956, 1019, 1097, 1145, 1219, 1268, 1367, 1495, 1611,
1659, 1702, 1725, 2870, 2963, 3431 cmꢁ1. MS (ESI) m/e 363.3
(MþþH). HRMS (ESI) calcd for C20H26NaO6: 385.1622, found:
385.1609.
J¼8.8 Hz, 1H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d 13.9, 14.2, 33.8,
59.9, 63.1, 69.6, 100.5, 117.1, 122.4, 123.3, 126.6, 135.5, 151.7, 163.4,
166.9, 173.2. IR (CH2Cl2)
n
855, 914, 1042, 1120, 1218, 1350, 1373,
3.4.11. Compound E-2f. Yield: 42%, 28 mg; a yellow oil. 1H NMR
1603, 1657, 1738, 2926, 2982, 3473 cmꢁ1. MS (ESI) m/e 323.2
(MþꢁOH). HRMS (ESI) calcd for C16H17ClNaO6: 363.0606, found:
363.0593.
(CDCl3, 400 MHz, TMS)
d
1.20 (t, J¼7.2 Hz, 3H, CH3), 1.28 (t, J¼7.2 Hz,
3H, CH3), 3.25 (d, J¼16.0 Hz, 1H, CH2), 3.77 (s, 3H, CH3), 4.03 (s, 1H,
OH), 4.08e4.19 (m, 4H, CH2), 4.29e4.37 (m, 1H, OCH2), 5.64 (s, 1H,
]CH), 6.85e6.86 (m, 2H, Ar), 6.94e6.96 (m, 1H, Ar). 13C NMR
3.4.6. Compound Z-2c. Yield: 31%, 21 mg; a yellow solid, Mp:
(CDCl3, 100 MHz, TMS)
109.6, 116.4, 117.7, 124.4, 145.2, 155.3, 164.4, 167.4, 173.6. IR (CH2Cl2)
d 13.9, 14.3, 34.1, 55.7, 59.8, 63.1, 70.1, 99.0,
127e129 ꢀC. 1H NMR (CDCl3, 300 MHz, TMS)
d
1.21 (t, J¼7.2 Hz, 3H,
CH3), 1.31 (t, J¼7.2 Hz, 3H, CH3), 2.88 (d, J¼15.6 Hz,1H, CH2), 2.94 (d,
J¼15.6 Hz, 1H, CH2), 4.09 (s, 1H, OH), 4.13e4.24 (m, 3H, OCH2),
4.27e4.38 (m, 1H, OCH2), 5.11 (s, 1H, ]CH), 7.05 (dd, J¼8.1 Hz,
J¼2.1 Hz, 1H, Ar), 7.22 (d, J¼2.1 Hz, 1H, Ar), 7.24 (d, J¼8.1 Hz, 1H, Ar).
n 820, 857, 1043, 1118, 1208, 1352, 1373, 1495, 1651, 1703, 1738, 2927,
2981, 3479 cmꢁ1. MS (ESI) m/e 319.0 (MþꢁOH). HRMS (ESI) calcd
for C17H20NaO7: 359.1101, found: 359.1100.
13C NMR (CDCl3, 100 MHz, TMS)
d
13.9, 14.3, 38.8, 59.8, 63.3, 70.0,
3.4.12. Compound Z-2f. Yield: 36%, 24 mg; a yellow solid, Mp:
99.1, 117.7, 122.0, 123.5, 126.4, 135.8, 151.8, 158.4, 164.1, 173.2. IR
107e109 ꢀC. 1H NMR (CDCl3, 400 MHz, TMS)
d
1.22 (t, J¼6.8 Hz, 3H,
(CH2Cl2)
n
817, 972, 1083, 1218, 1372, 1410, 1602, 1699, 1732, 2979,
CH3), 1.30 (t, J¼7.2 Hz, 3H, CH3), 2.88 (d, J¼15.6 Hz,1H, CH2), 2.94 (d,
J¼15.6 Hz, 1H, CH2), 3.77 (s, 3H, CH3), 4.03 (s, 1H, OH), 4.11e4.22 (m,
3H, CH2), 4.29e4.35 (m, 1H, CH2), 5.04 (s, 1H, ]CH), 6.84e6.89 (m,
2H, Ar), 7.12 (d, J¼8.0 Hz, 1H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
3383 cmꢁ1. MS (ESI) m/e 341.2 (Mþþ1). HRMS (ESI) calcd for
C16H17ClNaO6: 363.0606, found: 363.0612.
3.4.7. Compound E-2d. Yield: 44%, 28 mg; a yellow oil. 1H NMR
d 13.9, 14.4, 39.1, 55.7, 59.6, 63.3, 70.4, 97.4, 109.5, 116.3, 118.3, 123.9,
(CDCl3, 400 MHz, TMS)
d
1.20 (t, J¼7.2 Hz, 3H, CH3), 1.28 (t, J¼7.2 Hz,
145.4, 155.4, 159.7, 164.5, 173.5. IR (CH2Cl2) n 816, 860, 955, 1041,
3H, CH3), 2.30 (s, 3H, CH3), 3.32 (d, J¼16.0 Hz, 1H, CH2), 4.00 (s, 1H,
OH), 4.04 (d, J¼16.0 Hz, 1H, CH2), 4.09e4.19 (m, 3H, CH2), 4.29e4.37
(m, 1H, CH2), 5.66 (s, 1H, ]CH), 6.91 (d, J¼7.2 Hz, 1H, Ar), 7.09e7.11
1141, 1208, 1495, 1651, 1699, 1732, 2982, 3426 cmꢁ1. MS (ESI) m/e
337.0 (Mþþ1). HRMS (ESI) calcd for C17H20NaO7: 359.1101, found:
359.1106.
(m, 2H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d 13.9, 14.3, 20.7, 34.0,
59.7, 62.9, 70.0, 99.3, 116.5, 123.4, 125.6, 130.9, 132.7, 149.1, 164.4,
3.4.13. Compound E-2g. Yield: 41%, 26 mg; a yellow oil. 1H NMR
167.3, 173.7. IR (CH2Cl2)
n
820, 1119, 1220, 1291, 1373, 1497, 1614,
(CDCl3, 400 MHz, TMS)
d
1.22 (t, J¼7.2 Hz, 3H, CH3), 1.28 (t, J¼7.2 Hz,
1651, 1699, 1731, 2825, 2888, 2984, 3473 cmꢁ1. MS (ESI) m/e 303.2
(MþꢁOH). HRMS (ESI) calcd for C17H20NaO6: 343.1152, found:
343.1140.
3H, CH3), 2.29 (s, 3H, CH3), 3.49 (d, J¼16.0 Hz, 1H, CH2), 3.91 (d,
J¼16.0 Hz, 1H, CH2), 3.95 (s, 1H, OH), 4.11e4.20 (m, 3H, CH2),
4.29e4.37 (m, 1H, CH2), 5.75 (s, 1H, ]CH), 6.94e6.97 (m, 1H, Ar),
7.11 (d, J¼7.2 Hz, 1H, Ar), 7.16 (d, J¼7.6 Hz, 1H, Ar). 13C NMR (CDCl3,
3.4.8. Compound Z-2d. Yield: 50%, 32 mg; a yellow solid, Mp:
100 MHz, TMS) d 13.9, 14.3, 15.8, 33.7, 59.8, 62.9, 70.2, 99.7, 122.5,
106e108 ꢀC. 1H NMR (CDCl3, 400 MHz, TMS)
d
1.22 (t, J¼7.2 Hz, 3H,
122.9, 123.4, 126.1, 131.7, 149.3, 164.1, 167.3, 173.7. IR (CH2Cl2) n 847,
CH3), 1.30 (t, J¼6.8 Hz, 3H, CH3), 2.30 (s, 3H, CH3), 2.89 (d, J¼15.6 Hz,
1H, CH2), 2.93 (d, J¼15.6 Hz, 1H, CH2), 3.99 (s, 1H, OH), 4.12e4.22
(m, 3H, CH2), 4.29e4.37 (m, 1H, CH2), 5.06 (s, 1H, ]CH), 7.06e7.10
(m, 2H, Ar), 7.25 (d, J¼8.8 Hz, 1H, Ar). 13C NMR (CDCl3, 100 MHz,
892, 1040, 1123, 1181, 1214, 1243, 1351, 1373, 1469, 1652, 1705, 1736,
2982, 3485 cmꢁ1. MS (ESI) m/e 303.0 (MþꢁOH). HRMS (ESI) calcd
for C17H20NaO6: 343.1152, found: 343.1153.
TMS)
d
13.9, 14.3, 20.6, 39.0, 59.5, 63.0, 70.3, 97.7, 117.1, 122.9, 125.3,
3.4.14. Compound Z-2g. Yield: 42%, 27 mg; a yellow oil. 1H NMR
131.0, 132.8, 149.2, 159.6, 164.5, 173.5. IR (CH2Cl2)
n
820, 955, 1100,
(CDCl3, 400 MHz, TMS)
d
1.23 (t, J¼6.8 Hz, 3H, CH3), 1.32 (t,
1144, 1211, 1496, 1614, 1658, 1698, 1731, 2926, 2981, 3433 cmꢁ1. MS
(ESI) m/e 321.3 (Mþþ1). HRMS (ESI) calcd for C17H20NaO6: 343.1152,
found: 343.1144.
J¼6.8 Hz, 3H, CH3), 2.43 (s, 3H, CH3), 2.90 (d, J¼15.2 Hz, 1H, CH2),
2.98 (d, J¼15.2 Hz, 1H, CH2), 3.92 (s, 1H, OH), 4.14e4.25 (m, 3H,
CH2), 4.29e4.37 (m, 1H, CH2), 5.09 (s, 1H, ]CH), 6.95e6.98 (m, 1H,
Ar), 7.10 (d, J¼6.8 Hz, 1H, Ar), 7.20 (d, J¼8.0 Hz, 1H, Ar). 13C NMR
3.4.9. Compound E-2e. Yield: 41%, 29 mg; a yellow oil. 1H NMR
(CDCl3, 100 MHz, TMS)
d
14.0, 14.4, 15.8, 38.6, 59.7, 63.1, 70.6, 98.3,
(CDCl3, 400 MHz, TMS)
d
1.21 (t, J¼7.2 Hz, 3H, CH3), 1.26e1.30 (m,
122.6, 122.8, 126.9, 131.9, 149.5, 159.0, 164.7, 173.6. IR (CH2Cl2) n 955,
12H, CH3), 3.41 (d, J¼15.2 Hz, 1H, CH2), 3.97 (s, 1H, OH), 3.97 (d,
J¼15.2 Hz,1H, CH2), 4.14e4.19 (m, 3H, CH2), 4.30e4.35 (m,1H, CH2),
5.67 (s, 1H, ]CH), 6.95 (d, J¼8.8 Hz, 1H, Ar), 7.28 (d, J¼2.4 Hz, 1H,
Ar), 7.33 (dd, J¼8.8 Hz, J¼2.4 Hz, 1H, Ar). 13C NMR (CDCl3, 75 MHz,
1050, 1093, 1138, 1213, 1372, 1470, 1660, 1699, 1731, 2982,
3463 cmꢁ1. MS (ESI) m/e 321.0 (Mþþ1). HRMS (ESI) calcd for
C17H20NaO6: 343.1152, found: 343.1143.
TMS)
d
14.0, 14.3, 31.3, 34.1, 34.4, 59.7, 62.9, 70.2, 99.4, 116.3, 122.0,
3.4.15. Compound E-2h. Yield: 48%, 29 mg; a colorless oil. 1H NMR
122.9, 127.4, 146.1, 148.9, 164.4, 167.3, 173.7. IR (CH2Cl2)
1043, 1125, 1177, 1292, 1373, 1496, 1610, 1652, 1738, 2966,
n
824, 891,
(CDCl3, 300 MHz, TMS)
3H, CH3), 3.38 (d, J¼15.9 Hz, 1H, CH2), 4.03 (d, J¼15.9 Hz, 1H, CH2),
d
1.20 (t, J¼7.2 Hz, 3H, CH3), 1.28 (t, J¼7.2 Hz,

F. Hu et al. / Tetrahedron 68 (2012) 4782e4790
4789
4.08 (s, 1H, OH), 4.10e4.23 (m, 3H, CH2), 4.26e4.38 (m, 1H, CH2),
5.70 (s, 1H, ]CH), 7.01e7.09 (m, 2H, Ar), 7.29e7.33 (m, 2H, Ar). 13C
J¼8.4 Hz, 1H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d
13.9, 28.3, 39.1,
55.5, 63.0, 70.2, 79.8, 100.2, 102.0, 110.3, 115.4, 126.0, 152.4, 158.5,
NMR (CDCl3, 100 MHz, TMS)
116.8, 123.1, 123.8, 125.4, 130.3, 151.2, 164.1, 167.2, 173.6. IR (CH2Cl2)
d
13.9, 14.3, 33.9, 59.8, 63.0, 70.0, 99.8,
161.3, 163.8, 173.7. IR (CH2Cl2) n 836, 1025, 1114, 1157, 1355, 1382,
1507, 1615, 1707, 2853, 2925, 3457 cmꢁ1. MS (ESI) m/e 387.1
(MþþNa). HRMS (ESI) calcd for C19H24O7: 364.1522, found:
364.1516.
n
856, 891, 1042, 1097, 1124, 1176, 1221, 1290, 1374, 1456, 1487, 1608,
1656, 1732, 1709, 2936, 2982, 3479 cmꢁ1. MS (ESI) m/e 289.0
(MþꢁOH). HRMS (ESI) calcd for C16H18NaO6: 329.0996, found:
329.1005.
3.4.21. Compound 4a. Yield: 48%, 21 mg; a yellow oil. 1H NMR
(CDCl3, 300 MHz, TMS)
d
1.08 (t, J¼7.2 Hz, 3H, CH3), 2.83 (d,
3.4.16. Compound Z-2h. Yield: 49%, 30 mg; a colorless oil. 1H NMR
J¼15.9 Hz, 1H, CH2), 2.89 (d, J¼15.9 Hz, 1H, CH2), 3.83 (s, 3H, CH3),
4.00 (s, 1H, OH), 4.01e4.07 (m, 1H, CH2), 4.09e4.17 (m, 1H, CH2),
5.74 (s, 1H, ]CH), 6.57 (d, J¼2.4 Hz, 1H, Ar), 6.65 (dd, J¼8.4 Hz,
J¼2.4 Hz,1H, Ar), 7.19 (d, J¼8.4 Hz,1H, Ar), 7.50 (d, J¼8.4 Hz, 2H, Ar),
(CDCl3, 300 MHz, TMS)
d
1.21 (t, J¼7.2 Hz, 3H, CH3), 1.30 (t, J¼7.2 Hz,
3H, CH3), 2.94 (s, 1H, CH2), 4.10 (s, 1H, OH), 4.13e4.24 (m, 3H, CH2),
4.27e4.38 (m,1H, CH2), 5.09 (s,1H, ]CH), 7.04e7.09 (m 1H, Ar), 7.19
(d, J¼7.8 Hz, 1H, Ar), 7.27e7.36 (m, 2H, Ar). 13C NMR (CDCl3,
8.02 (d, J¼8.4 Hz, 2H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d 13.8,
100 MHz, TMS)
d
13.9, 14.3, 38.9, 59.6, 63.1, 70.3, 98.2, 117.4, 123.25,
37.9, 55.6, 63.4, 69.6, 102.0, 108.4, 110.4, 115.3, 126.2, 129.0, 129.2,
123.32, 125.2, 130.5, 151.3, 159.2, 164.4, 173.5. IR (CH2Cl2)
n
954,
139.6, 141.2, 151.2, 158.5, 161.4, 173.1. IR (CH2Cl2) n 831, 1013, 1130,
1062, 1097, 1220, 1456, 1607, 1660, 1699, 1731, 2934, 2982,
3435 cmꢁ1. MS (ESI) m/e 307.1 (MþþH). HRMS (ESI) calcd for
C16H18NaO6: 329.0996, found: 329.1006.
1199, 1320, 1507, 1584, 1610, 1646, 1735, 2849, 2925, 3079,
3466 cmꢁ1. MS (MALDI) m/e 461.3 (MþþNa). HRMS (MALDI) calcd
for C20H19O7SClNa: 461.0432, found: 461.0420.
3.4.17. Compound E-2i. Yield: 23%, 17 mg; a yellow oil. 1H NMR
3.4.22. Compound 4b. Yield: 38%, 16 mg; a yellow oil. 1H NMR
(CDCl3, 400 MHz, TMS)
d
1.17 (t, J¼7.2 Hz, 3H, CH3), 3.40 (d,
(CDCl3, 400 MHz, TMS)
d
1.08 (t, J¼7.2 Hz, 3H, CH3), 2.36 (s, 3H,
J¼15.6 Hz, 1H, CH2), 3.80 (s, 3H, OCH3), 3.93 (s, 1H, OH), 3.97 (d,
J¼15.6 Hz,1H, CH2), 4.12 (dq, J¼10.8 Hz, J¼7.2 Hz,1H, CH2), 4.29 (dq,
J¼10.8 Hz, J¼7.2 Hz, 1H, CH2), 5.14 (d, J¼12.4 Hz, 1H, CH2), 5.18 (d,
J¼12.4 Hz, 1H, CH2), 5.75 (s, 1H, ]CH2), 6.56 (d, J¼1.8 Hz, 1H, Ar),
6.62 (dd, J¼8.4 Hz, J¼1.8 Hz, 1H, Ar), 7.19 (d, J¼8.4 Hz, 1H, Ar),
CH3), 2.82 (d, J¼15.6 Hz, 1H, CH2), 2.89 (d, J¼15.6 Hz, 1H, CH2), 3.99
(s, 1H, OH), 4.00e4.07 (m, 1H, CH2), 4.12e4.18 (m, 1H, CH2), 5.73 (s,
1H, ]CH), 6.88 (s, 1H, Ar), 6.92 (d, J¼8.0 Hz, 1H, Ar), 7.18 (d,
J¼8.0 Hz, 1H, Ar), 7.50 (d, J¼8.4 Hz, 2H, Ar), 8.03 (d, J¼8.4 Hz, 2H,
Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d 13.8, 21.2, 37.9, 63.4, 69.7,
7.30e7.39 (m, 5H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d
13.9, 34.1,
108.2, 117.2,120.3,125.1,129.0,129.2,139.5,141.3,141.4,150.2, 158.6,
55.5, 63.0, 65.7, 69.7, 99.6, 101.9, 109.7, 115.9, 126.3, 128.1, 128.3,
128.5, 136.2, 152.0, 161.2, 164.9, 167.0, 173.8. IR (CH2Cl2) 838, 1025,
1113, 1354, 1382, 1455, 1506, 1615, 1653, 1706, 252, 2294,
3457 cmꢁ1. MS (ESI) m/e 421.1 (MþþNa). HRMS (ESI) calcd for
C22H22O7: 398.1366, found: 398.1363.
173.1. IR (CH2Cl2) n 828, 1013, 1083, 1135, 1245, 1321, 1474, 1580,
n
1611, 1644, 1736, 2853, 2924, 3079, 3465 cmꢁ1. MS (MALDI) m/e
445.0 (MþþNa). HRMS (MALDI) calcd for C20H19O6SClNa: 445.0483,
found: 445.0491.
3.4.23. Compound 4c. Yield: 30%, 13 mg; a yellow oil. 1H NMR
3.4.18. Compound Z-2i. Yield: 32%, 23 mg; a yellow oil. 1H NMR
(CDCl3, 300 MHz, TMS)
d
1.09 (t, J¼7.2 Hz, 3H, CH3), 2.82 (d,
(CDCl3, 400 MHz, TMS)
d
1.20 (t, J¼7.2 Hz, 3H, CH3), 2.89 (d,
J¼15.6 Hz, 1H, CH2), 2.91 (d, J¼15.6 Hz, 1H, CH2), 4.00e4.08 (m, 1H,
CH2), 4.10 (s, 1H, OH), 4.12e4.18 (m, 1H, OCH2), 5.78 (s, 1H, ]CH),
7.08 (s, 1H, Ar), 7.09 (d, J¼8.8 Hz, 1H, Ar), 7.28 (d, J¼8.8 Hz, 1H, Ar),
7.51 (d, J¼8.4 Hz, 2H, Ar), 8.02 (d, J¼8.4 Hz, 2H, Ar). 13C NMR (CDCl3,
J¼15.2 Hz, 1H, CH2), 2.89 (d, J¼15.2 Hz, 1H, CH2), 3.78 (s, 3H, OCH3),
3.97 (br, 1H, OH), 4.15 (dq, J¼10.8 Hz, J¼7.2 Hz, 1H, CH2), 4.30 (dq,
J¼10.8 Hz, J¼7.2 Hz, 1H, CH2), 5.15 (s, 1H, ]CH2), 5.20 (s, 2H, CH2),
6.62 (dd, J¼8.4 Hz, J¼2.0 Hz, 1H, Ar), 6.70 (d, J¼2.0 Hz, 1H, Ar), 7.17
(d, J¼8.4 Hz, 1H, Ar), 7.29e7.42 (m, 5H, Ar). 13C NMR (CDCl3,
100 MHz, TMS)
d 13.8, 37.7, 63.7, 69.5, 109.3, 117.1, 122.0, 124.4,
126.5, 129.1, 129.2, 136.0, 139.8, 141.0, 150.7, 157.6, 172.6. IR (CH2Cl2)
100 MHz, TMS)
d
13.9, 39.0, 55.5, 63.0, 65.5, 70.0, 97.9, 101.8, 110.5,
n 826, 973, 1014, 1085, 1160, 1224, 1317, 1599, 1737, 2854, 2926,
115.3, 126.0, 127.95, 128.0, 128.4, 136.4, 152.2, 160.1, 161.3, 164.1,
3085, 3459 cmꢁ1. MS (MALDI) m/e 465.0 (MþþNa). HRMS (MALDI)
173.6. IR (CH2Cl2)
n
837, 997, 1108,1138,1210,1256,1443,1506, 1615,
calcd for C19H16O6SCl2Na: 464.9937, found: 464.9924.
1659, 1720, 2934, 3435 cmꢁ1. MS (ESI) m/e 421.1 (MþþNa). HRMS
(ESI) calcd for C22H22O7: 398.1366, found: 398.1363.
3.4.24. Compound 4d. Yield: 31%, 13 mg; a yellow solid, Mp:
120e122 ꢀC. 1H NMR (CDCl3, 400 MHz, TMS)
d
1.07 (t, J¼7.2 Hz, 3H,
3.4.19. Compound E-2j. Yield: 11%, 8 mg; a yellow oil. 1H NMR
CH3), 2.30 (s, 3H, CH3), 2.81 (d, J¼15.2 Hz, 1H, CH2), 2.91 (d,
J¼15.2 Hz, 1H, CH2), 3.97e4.04 (m, 1H, CH2), 4.05 (s, 1H, OH),
4.10e4.18 (m, 1H, CH2), 5.73 (s, 1H, ]CH), 6.95 (d, J¼8.4 Hz, 1H, Ar),
7.12e7.14 (m, 2H, Ar), 7.50 (d, J¼8.8 Hz, 2H, Ar), 8.03 (d, J¼8.8 Hz,
(CDCl3, 400 MHz, TMS)
d
1.22 (t, J¼7.2 Hz, 3H, CH3), 1.48 (s, 9H,
CH3), 3.36 (d, J¼15.6 Hz, 1H, CH2), 3.80 (s, 3H, OCH3), 3.92 (d,
J¼15.6 Hz, 1H, CH2), 3.93 (s, 1H, OH), 4.12 (dq, J¼10.8 Hz, J¼7.2 Hz,
1H, CH2), 4.34 (dq, J¼10.8 Hz, J¼7.2 Hz, 1H, CH2), 5.62 (s, 1H, ]CH2),
6.54 (d, J¼2.4 Hz, 1H, Ar), 6.61 (dd, J¼8.4 Hz, J¼2.4 Hz, 1H, Ar), 7.18
2H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d 13.8, 20.7, 37.8, 63.5, 69.8,
107.9, 116.5, 122.8, 125.5, 129.0, 129.3, 131.2, 133.9, 139.5, 141.3,
(d, J¼8.4 Hz, 1H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d
14.0, 28.3,
148.3, 158.6, 173.0. IR (CH2Cl2) n 775, 823, 1007, 1083, 1220, 1319,
33.9, 55.5, 62.9, 69.8, 80.0, 101.79, 101.8, 109.5, 115.9, 126.4, 152.3,
1494, 1609, 1640, 1732, 2854, 2924, 3078, 3463 cmꢁ1. MS (MALDI)
m/e 445.1 (MþþNa). HRMS (MALDI) calcd for C20H19O6SClNa:
445.0483, found: 445.0472.
161.2, 163.1, 166.6, 173.9. IR (CH2Cl2)
n 797, 1014, 1110, 1155, 1259,
1366, 1507, 1616, 1701, 1733, 2930, 3471 cmꢁ1. MS (ESI) m/e 387.1
(MþþNa). HRMS (ESI) calcd for C19H24O7: 364.1522, found:
364.1520.
3.4.25. Compound 4e. Yield: 30%, 14 mg; a yellow oil. 1H NMR
(CDCl3, 400 MHz, TMS)
d
1.09 (t, J¼7.2 Hz, 3H, CH3), 1.28 (s, 9H,
3.4.20. Compound Z-2j. Yield: 22%, 16 mg; a yellow oil. 1H NMR
C(CH3)3), 2.83 (d, J¼15.6 Hz, 1H, CH2), 2.90 (d, J¼15.6 Hz, 1H, CH2),
4.02 (s, 1H, OH), 4.03e4.09 (m, 1H, OCH2), 4.12e4.20 (m, 1H, OCH2),
5.73 (s, 1H, ]CH), 6.98 (d, J¼8.8 Hz, 1H, Ar), 7.28 (d, J¼2.8 Hz, 1H,
Ar), 7.36 (dd, J¼8.8 Hz, J¼2.8 Hz, 1H, Ar), 7.49 (d, J¼8.4 Hz, 2H, Ar),
(CDCl3, 400 MHz, TMS)
d
1.23 (t, J¼7.2 Hz, 3H, CH3),1.51 (s, 9H, CH3),
2.85 (d, J¼14.8 Hz, 1H, CH2), 2.91 (d, J¼14.8 Hz, 1H, CH2), 3.80 (s, 3H,
OCH3), 3.94 (s, 1H, OH), 4.17 (dq, J¼7.2 Hz, J¼10.8 Hz, 1H, CH2), 4.32
(dq, J¼7.2 Hz, J¼10.8 Hz, 1H, CH2), 5.02 (s, 1H, ]CH2), 6.61 (dd,
J¼8.4 Hz, J¼2.4 Hz, 1H, Ar), 6.74 (d, J¼2.4 Hz, 1H, Ar), 7.16 (d,
8.03 (d, J¼8.4 Hz, 2H, Ar). 13C NMR (CDCl3, 100 MHz, TMS)
d 13.8,
31.3, 34.6, 38.0, 63.4, 70.0, 108.0, 116.3, 121.8, 122.5, 127.8, 129.0,

4790
F. Hu et al. / Tetrahedron 68 (2012) 4782e4790
129.3, 139.5, 141.4, 147.4, 148.2, 158.6, 173.2. IR (CH2Cl2)
n
823, 850,
and 4d (CCDC 865626). This material is available free of charge from
authors or via the Internet. Supplementary data associated with
this article can be found in the online version, at doi:10.1016/
j.tet.2012.04.036.
1010, 1084, 1233, 1321, 1494, 1607, 1641, 1737, 2856, 2924, 2958,
3085, 3462 cmꢁ1. MS (MALDI) m/e 487.1 (MþþNa). HRMS (MALDI)
calcd for C23H25O6SClNa: 487.0953, found: 487.0948.
3.4.26. Compound 4f. Yield: 34%, 14 mg; a yellow oil. 1H NMR
References and notes
(CDCl3, 400 MHz, TMS)
d
1.08 (t, J¼7.2 Hz, 3H, CH3) 2.84 (d,
J¼16.0 Hz, 1H, CH2), 2.92 (d, J¼16.0 Hz, 1H, CH2), 4.05 (s, 1H, OH),
4.00e4.08 (m, 1H, CH2), 4.10e4.18 (m, 1H, OCH2), 5.75 (s, 1H, ]CH),
7.05 (d, J¼7.2 Hz, 1H, Ar), 7.09e7.13 (m, 1H, Ar), 7.32e7.36 (m, 2H,
Ar), 7.50 (d, J¼8.4 Hz, 2H, Ar), 8.03 (d, J¼8.4 Hz, 2H, Ar). 13C NMR
1. (a) Schweizer, E. E.; Meeder-Nycz, O. In Chromenes, Chromanes, Chromones; Ellis,
G. P., Ed.; Wiley-Interscience: New York, NY, 1977; pp 11e139; (b) Bowers, W. S.;
Ohta, T.; Cleere, J. S.; Marsella, P. A. Science 1976, 193, 542e543.
2. Hepworth, J. In Comprehensive Heterocyclic Chemistry; Katrizky, A. R., Rees, C. W.
, Eds.; Pergamon: Oxford, 1984; Vol. 3, pp 737e883.
3. (a) Kaye, P. T.; Musa, M. A.; Nocanda, X. W.; Robinson, R. S. Org. Biomol. Chem.
2003, 1, 1133e1138; (b) Kaye, P. T.; Musa, M. A. Synthesis 2003, 531e534; (c)
Kaye, P. T.; Nocanda, X. W. J. Chem. Soc., Perkin Trans. 1 2002, 1318e1323; (d)
Kaye, P. T.; Musa, M. A. Synthesis 2002, 2701e2706; (e) Kaye, P. T.; Nocanda, X.
W. Synthesis 2001, 2389e2392; (f) Kaye, P. T.; Nocanda, X. W. J. Chem. Soc.,
Perkin Trans. 1 2000, 1331e1332; (g) Familoni, O. B.; Kaye, P. T.; Klaas, P. J. Chem.
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(CDCl3, 100 MHz, TMS)
d 13.8, 37.7, 63.5, 69.8, 108.4, 116.7, 123.3,
124.2, 125.3, 129.0, 129.3, 130.7, 139.5, 141.2, 150.3, 158.3, 172.9. IR
(CH2Cl2) 827, 868, 101, 1084, 1132, 1226, 1320, 1456, 1603, 1643,
n
1737, 2853, 2924, 3079, 3462 cmꢁ1
. MS (MALDI) m/e 431.0
(MþþNa). HRMS (MALDI) calcd for C19H17O6SClNa: 431.0327,
found: 431.0312.
€
26, 2085e2097; (i) Lesch, B.; Brase, S. Angew. Chem., Int. Ed. 2004, 43, 115e118;
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3.4.27. Compound 4g. Yield: 32%, 14 mg; a yellow solid, Mp:
140e142 ꢀC. 1H NMR (CDCl3, 400 MHz, TMS)
d
1.06 (t, J¼7.2 Hz, 3H,
€
€
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CH3), 2.19 (s, 3H, CH3), 2.26 (s, 3H, CH3), 2.81 (d, J¼15.2 Hz,1H, CH2),
2.88 (d, J¼15.2 Hz, 1H, CH2), 4.00 (s, 1H, OH), 3.96e4.04 (m, 1H,
CH2), 4.09e4.17 (m, 1H, CH2), 5.71 (s, 1H, ]CH), 6.85 (s, 1H, Ar), 7.04
(s, 1H, Ar), 7.50 (d, J¼8.4 Hz, 2H, Ar), 8.03 (d, J¼8.4 Hz, 2H, Ar). 13C
€
rahedron 2007, 63, 10415e10424; (p) Nising, C.; Brase, S. Chem. Soc. Rev. 2008,
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Kwon, O. J. Am. Chem. Soc. 2007, 129, 6722e6723; (g) Moreno-Clavijo, E.; Car-
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6276e6282; (i) Zhao, G.-L.; Shi, M. J. Org. Chem. 2005, 70, 9975e9984.
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(a) Zhu, X.-F.; Henry, C. E.; Wang, J.; Dudding, T.; Kwon, O. Org. Lett. 2005, 7,
1387e1390; (b) Zhu, X.-F.; Schaffner, A.-P.; Li, R. C.; Kwon, O. Org. Lett. 2005, 7,
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NMR (CDCl3, 100 MHz, TMS) d 13.8, 19.1, 19.7, 38.0, 63.4, 69.7, 107.8,
117.5,120.1,125.8, 129.0, 129.2, 132.7,139.4, 139.7,141.3,148.3,158.9,
173.2. IR (CH2Cl2) n 747, 827, 848, 1014, 1083, 1218, 1321, 1456, 1582,
1613, 1643, 1737, 2853, 2924, 3085, 3465 cmꢁ1. MS (MALDI) m/e
459.2 (MþþNa). HRMS (MALDI) calcd for C21H21O6SClNa: 459.0640,
found: 459.0644.
3.4.28. Compound 4h. Yield: 34%, 15 mg; a white solid, Mp:
179e181 ꢀC. 1H NMR (CDCl3, 400 MHz, TMS)
d
1.07 (t, J¼7.2 Hz, 3H,
CH3), 1.19 (t, J¼7.2 Hz, 3H, CH3), 2.73 (q, J¼7.2 Hz, 2H, CH2), 2.82 (d,
J¼15.6 Hz, 1H, CH2), 2.91 (d, J¼15.6 Hz, 1H, CH2), 3.98e4.04 (m, 1H,
OCH2), 4.06 (s, 1H, OH), 4.10e4.18 (m, 1H, CH2), 5.73 (s, 1H, ]CH),
6.97 (d, J¼8.4 Hz, 1H, Ar), 7.13 (s, 1H, Ar), 7.16 (d, J¼8.4 Hz, 1H, Ar),
7.50 (d, J¼8.0 Hz, 2H, Ar), 8.03 (d, J¼8.0 Hz, 2H, Ar). 13C NMR (CDCl3,
100 MHz, TMS)
d 13.7, 15.3, 28.0, 37.7, 63.4, 69.7, 107.8, 116.4, 122.7,
124.2, 128.8, 129.2, 129.9, 139.3, 140.2, 141.1, 148.3, 158.5, 172.9. IR
(CH2Cl2) 831, 1014, 1085, 1135, 1225, 1320, 1493, 1609, 1642, 1737,
n
2854, 2927, 2965, 3085, 3466 cmꢁ1
. MS (MALDI) m/e 459.1
6. For reactions of allenic esters and ketones with salicyl N-tosylimines or alde-
hydes: (a) Shi, Y.-L.; Shi, M. Org. Lett. 2005, 7, 3057e3060; (b) Zhao, G.-L.; Shi, M.
Org. Biomol. Chem. 2005, 3, 3686e3694; (c) Zhao, G.-L.; Shi, Y.-L.; Shi, M. Org.
Lett. 2005, 7, 4527e4530; (d) Dai, L.-Z.; Shi, Y.-L.; Zhao, G.-L.; Shi, M. Chem.dEur.
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Catal. 2006, 348, 967e972; (f) Sun, Y.-W.; Guan, X.-Y.; Shi, M. Org. Lett. 2010, 12,
5664e5667.
(MþþNa). HRMS (MALDI) calcd for C21H21O6SClNa: 459.0640,
found: 459.0635.
Acknowledgements
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We thank the Shanghai Municipal Committee of Science and
Technology (11JC1402600), National Basic Research Program of
China (973)-2009CB825300, the Fundamental Research Funds for
the Central Universities and the National Natural Science Founda-
tion of China for financial support (21072206, 20472096, 20872162,
20672127, 21121062 and 20732008).
Supplementary data
Detailed description of experimental procedures, spectral
charts, and analytical data for new compounds shown in Schemes
and Figures, CIF files, and X-ray crystal data of Z-2c (CCDC 829459)