Siloxyallenes revisited. A useful functional intermediate for the synthesis of (Z)-β-branched Morita-Baylis-Hillman type adducts and (Z)-chalcones

Article abstract of DOI:10.1016/j.tet.2007.02.025

Siloxyallenes proved to be a useful functional intermediate in the preparation of (Z)-β-branched Morita-Baylis-Hillman type adducts by the reaction of aldehydes with silylacetylenes or siloxypropynes. Various (Z)-chalcones were stereoselectively synthesized from siloxypropynes via siloxyallenes.

Full text of DOI:10.1016/j.tet.2007.02.025

Tetrahedron 63 (2007) 6259–6286
Siloxyallenes revisited. A useful functional intermediate
for the synthesis of (Z)-b-branched Morita–Baylis–Hillman
type adducts and (Z)-chalcones
*
Kazuhiro Yoshizawa and Takayuki Shioiri
Graduate School of Environmental and Human Sciences, Meijo University, Shiogamaguchi, Tempaku, Nagoya 468-8502, Japan
Received 15 December 2006; revised 6 February 2007; accepted 7 February 2007
Available online 13 February 2007
Abstract—Siloxyallenes proved to be a useful functional intermediate in the preparation of (Z)-b-branched Morita–Baylis–Hillman type
adducts by the reaction of aldehydes with silylacetylenes or siloxypropynes. Various (Z)-chalcones were stereoselectively synthesized
from siloxypropynes via siloxyallenes.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
treatment of siloxyallenes A was revealed to produce (Z)-
chalcone derivatives E.4 We now report the details of the
method for the preparation of (Z)-b-branched Morita–
Baylis–Hillman type adducts D and (Z)-chalcone derivatives
E via siloxyallenes A.
Siloxyallenes (allenyl silyl ethers or silyl allenolates) A have
been recognized as useful functional intermediates in organic
synthesis.1 They have been synthesized in three ways: (1)
isomerization of siloxypropynes (2-propynyl silyl ethers)
with base,1f–i (2) coupling of silyl ketones with acetylides
followed by a Brook rearrangement,1a–e and (3) reaction of
a,b-alkynyl ketones with iodotrimethylsilane.1j
2. Results and discussion
2.1. Reaction of 1-phenyl-2-(trimethylsilyl)acetylene
and aromatic aldehydes catalyzed with ammonium
fluorides
Recently, we found by chance that siloxyallenes A were
formed as an intermediate in the synthesis of (Z)-b-branched
Morita–Baylis–Hillman (MBH) type adducts D, as shown in
Scheme 1. Reaction of silylacetylenes B with aldehydes cat-
alyzed by a chiral ammonium fluoride gave (Z)-b-branched
MBH type adducts D via siloxypropynes C and then siloxy-
allenes A as intermediates.2 Formation of siloxyallenes A
was also observed by treatment of siloxypropynes C with
KOt-Bu, and siloxyallenes A reacted with other aldehydes
to give (Z)-b-branched MBH type adducts D.3 Acidic
In 1993, a chiral quaternary ammonium fluoride 5a corre-
sponding to a chiral version of tetrabutylammonium fluoride
was prepared by our group5 for the first time6 from cincho-
nine. The fluoride has been revealed to be a good catalyst for
a catalytic asymmetric silyl aldol reaction.5 Since then, im-
portance of chiral ammonium fluorides has been increasing
in organic synthesis.7
H
O
Ar3
OH
1) Ar3CHO
2) H3O+
SiMe3
Ar1
Ar1
OSiMe3
B
Ar2
Ar1
OSiMe3
Ar2
D
Ar2
O
Ar1
H
H3O+
Ar1
Ar2
H
C
A
O
Ar2
E
Scheme 1.
Keywords: Siloxyallene; Morita–Baylis–Hillman type adduct; Silylacetylene; Siloxypropyne; (Z)-Chalcone.
* Corresponding author. Tel./fax: +81 52 832 1555; e-mail: shioiri@ccmfs.meijo-u.ac.jp
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2007.02.025

6260
K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
As an extension of the utilization of chiral ammonium
fluorides to organic synthesis, the reaction of 1-phenyl-2-
(trimethylsilyl)acetylene (1) with benzaldehyde (2a) was
investigated by use of the quaternary ammonium fluoride
5a derived from cinchonine.5 To our surprise, the main prod-
uct of the reaction, after acidic workup, was not the expected
propargyl alcohol 4 but the MBH type adduct 3. The latter 3
was probably formed by the reaction of another equivalent of
benzaldehyde with the originally formed silyl derivative of
the propargyl alcohol. The structure of 3 was identified by
spectral comparison with the known compound,8 but the
exclusive formation of the (Z)-isomer was recognized. Tetra-
butylammonium fluoride (TBAF) as well as other fluoride
anion reagents were already utilized for the same reaction,
but the main product was always reported to be the propargyl
alcohol 4,9 contrary to our result. Furthermore, b-substituted
MBH type adducts are not so easy to prepare by use of the
MBH reaction though several alternative improved methods
have been reported.1a,c,d,h–j,8,10 Thus, we launched to explore
the versatility of the unprecedented reaction.
function, 5b and 5c, resulted in the decrease of the formation
of 3 but increase of the formation of 4 (entries 7–9 in
Table 1).
The order of the addition of the reactants and catalyst influ-
enced the reaction. The reaction smoothly proceeded when
the acetylene 1 was added to a mixture of benzaldehyde
(2a) and the catalyst 5a, while no reaction occurred when
the acetylene was first mixed with the catalyst and then the
aldehyde was added. Suitable quantities of benzaldehyde
in CH2Cl2 were 1.25–1.5 equiv, but not 2 equiv (entries
10–13). The MBH type adduct 3 was preferentially formed
even when less than 1 equiv of the aldehyde was used. The
requisite concentration of the catalyst was 10 mol %. The
use of TBAF in THF (commercially available, 1 M solution
containing ca. 5% water) afforded the propargyl alcohol 4 as
the major product as reported. A similar result was obtained
when anhydrous TBAF11 was used. These experiments
clearly indicate that the reaction producing the b-substituted
MBH type product will be specific to the cinchoninium am-
monium fluoride and different from TBAF. The reaction pro-
ceeded in a complete diastereoselective manner to give the
(Z)-isomer only, but, unfortunately, the enantioselectivity
of the reaction was quite low, as shown in Table 1.
The results are summarized in Table 1. The reaction rapidly
proceeded at lower temperature in various solvents. Conver-
sion of the hydroxyl function of the catalyst 5a to the ether
Table 1. Reaction of 1-phenyl-2-(trimethylsilyl)acetylene (1) with benzaldehyde (2a) catalyzed with benzylcinchoninium fluoride (5a) and its derivativesa
OH
SiMe3
O
H
Catalyst 5
(10 mol%)
1N HCl
OH
H
+
+
1 h
MeOH
O
1
2a
3
4
(major product)
(minor product)
RO
N+
5a : R = H
5b : R = Allyl
5c : R = Bn
F-
N
Entry
Catalyst
Solvent
Temperature (ꢀC)
2a (equiv)
Yield (%)b; 3d
ee%c; 4e
1
2
3
4
5
5a
5a
5a
5a
5a
CH2Cl2
Toluene
THF
DMF
MeCN
ꢁ20 to rt
ꢁ20 to rt
ꢁ20
1.1
1.1
1.1
1.1
1.1
90 (0)
73 (3)
73 (6)
78 (2)
84 (0)
—
—
—
—
—
ꢁ20
ꢁ20
6
5a
5a
5b
5c
THF
THF
THF
THF
ꢁ40
ꢁ20
ꢁ20
ꢁ20
1.1
1.1
1.1
1.1
73 (7)
80 (9)
49 (16)
45 (17)
13 (15)
—
18 (28)
27 (21)
7f
8
9
10
11
12
13
14
5a
5a
5a
5a
5ag
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
ꢁ20 to rt
ꢁ20 to rt
ꢁ20 to rt
ꢁ20 to rt
ꢁ20 to rt
0.8
1.25
1.5
2.0
1.5
46 (0)
86 (0)
83 (0)
58 (0)
65 (3)
9
2
2
4
23
15f
TBAFh
THF
ꢁ20
1.1
10
63
a
To a mixture of the catalyst 5 and benzaldehyde (2a) was added the acetylene 1.
Isolated yield.
b
c
d
e
f
Checked by DAICEL CHIRALCEL OD (hexane/i-PrOH¼9:1, 1 mL/min, 254 nm).
Yield based on 2a.
Yield based on 1.
To a mixture of the acetylene 1 and benzaldehyde (2a) was added the catalyst 5a.
The catalyst 5a (5 mol %) was used.
THF solution was purchased and used directly.
g
h

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6261
Application of a catalytic amount of the reagent generated in
situ from N-benzylcinchoninium bromide (6) and CsF to the
reaction also smoothly afforded the MBH type adduct 3 in
DMF, as shown in Table 2. Again, the O-benzyl derivative
7 did not give even a trace of the products.
quenching the reaction. The minor product of the reaction
proved to be the dihydroisobenzofuran 19, which would be
formed by the reaction of one of the aldehyde group with
the acetylene 1 followed by cyclization and then methyl
ether formation by acidic methanol treatment.
Various aromatic aldehydes 2 underwent the reaction with
the acetylene 1 to give the (Z)-MBH type adducts D as the
major products under the reaction conditions shown in entry
12 of Table 1, as summarized in Table 3.
O
O
UV (365 nm)
MeCN
rt, 10 h
20%
H
C6H5
C6H5
H
HO
(Z)-18
OH
(E)-18
H
NOE 5%
Although both 4-methyl- and 3,4-methylenedioxybenzalde-
hydes (2b and 2h) solely afforded 8 and 15 in good yield, re-
spectively, the methoxy and dimethoxy derivatives, 2c and
2g, respectively, furnished a mixture of the MBH type ad-
ducts, 9 and 12, and the propargyl derivatives, 13 and 14,
in preference of the latter. The aromatic aldehydes 2d and
2e having halogen atoms smoothly afforded the MBH type
adducts 10 and 11, respectively. However, the reaction using
4-nitrobenzaldehyde (2f) and 4-pyridylaldehyde (2k) did not
proceed at all, while the reaction with 4-dimethylaminobenz-
aldehyde (2l) gave a complicated mixture. In all the cases,
the MBH type adducts D obtained proved to have (Z)-config-
uration.
NOE 5%
O
O
KOt-Bu
C6H5
H
C6H5
H
(10 mol%)
THF
rt, 0.5 h
OSiMe3
OSiMe3
Z : E = 2 : 1
Scheme 2.
Application of the above method to aliphatic trimethylsilyl-
acetylenes or aldehydes resulted in the formation of the
propargyl alcohols, and no MBH type adducts could be
detected in the products, as shown in Scheme 3.13
Phthalaldehyde (2m) having two aldehyde functions af-
forded a mixture of the indanone 18 and dihydroisobenzo-
furan 19 in preference of the former. The major product 18
was revealed to be (E)-isomer while the crude product was
a mixture of (Z)- and (E)-isomers in a ratio of 13:87. The
(Z)-isomer was prepared by photoisomerization of the (E)-
isomer according to the literature,12 and its structure was
confirmed by its NOE measurement, as shown in Scheme
2. The trimethylsilyl derivative of (Z)-18 was isomerized
to (E)-18 silyl ether under basic conditions. Thus, the iso-
lated major product (E)-18 would be formed during the reac-
tion by isomerization of the initially formed (Z)-18. The
isomerization did not occur under acidic conditions for
O
SiMe3
H
+
2a
O
SiMe3
+
OH
R2
H
n-C4H9
2a
R1
40~60%
SiMe3
+
O
H
H
R2
1
R1
OH
R2
O
Table 2. Reaction of the silylacetylene 1 with the aldehyde 2a using CsF and
the bromides
Scheme 3.
CsF (10 mol%)
Catalyst
1 (1 eq)
+
2a (1.5 eq)
(10 mol%)
Two reaction routes would be possible for the formation of
the MBH type adducts: the siloxyallene and oxetene routes,
as shown in Scheme 4. If aldehydes having substituents on
aromatic rings are used, two possible structurally isomeric
adducts will be considered. The siloxyallene route will pro-
duce G while H will be obtained through the oxetene route.
1N HCl
MeOH
3 + 4
RO
N+
6 : R = H
7 : R = Bn
Br-
N
This was clarified in the case of 4-fluorobenzaldehyde (2d)
(Scheme 5). Thus, 4-fluorobenzaldehyde (2d) was subjected
to the reaction with the propargyl alcohols 20 and 22, respec-
tively, by use of tris(triphenylsilyl)vanadate according to the
procedure developed by Trost and Oi.8 The reaction with 20
afforded a mixture of 10 and 21,14 in which the major prod-
uct was identical to the MBH type adduct 10 obtained by use
of the cinchonine catalyst 5a. In contrast, the reaction with
22 afforded the compound 23. All the products 10, 21, and
23 have (Z)-configuration, which was revealed by the char-
Entry
Catalyst
Solvent
Temperature/time
Yield (%)a
3b
4c
1
2
3
4
5
6
6
7
—
6
6
—
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
DMF
rt/0.5 h
rt/1 h
rt/0.5 h
0 ꢀC/1 h
rt/0.5 h
rt/0.5 h
72
—
—
—
91
—
19
—
—
—
—
d
d
d
d
d
d
DMF
Trace
a
Isolated yield.
Based on 2a.
Based on 1.
1
acteristic J-value (ca. 4 Hz) at allylic position in their H
NMR spectra. The other MBH type adducts will have anal-
ogous structures G, as shown in Table 3.
b
c
d
Starting material was recovered.

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K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
Table 3. Synthesis of b-substituted Morita–Baylis–Hillman type adducts from the silylacetylene 1 and various aldehydes 2
H
O
Ar
Ar
OH
Ar
SiMe3
ArCHO (2, 1.5 mmol)
5a (0.1 mmol)
1N HCl
MeOH
OH
+
CH2Cl2
-20 to 0 °C, 1 h
1
F
(1.0 mmol)
D
Entry
ArCHO
2
Yield (%)a
Entry
ArCHO
2
Yield (%)a
Db
Fc
Db
Fc
O
O
1
2
3
4
5
6
2a
2b
2c
2d
2e
3
8
92
87
37
89
89
4
7
—
52d
—
—
8
9
2h
2i
15
16
17
87
85
54
—
—
—
—
—
—
—
27h
CHO
CHO
CHO
Me
MeO
F
CHO
9
13
10
11
12
13f
2j
CHO
O
CHO
N
10
11
2k
2l
CHO
CHO
Cl
Me2N
CHO
CHO
O2N
CHO
2f
—
23
—
26
2m
18
49g
19
CHO
CHO
CHO
MeO
MeO
7e
2g
12
14
a
Isolated yield.
Based on 2.
Based on 1.
b
c
d
e
f
The propargyl derivative 13 was obtained as a mixture of OH and OMe derivatives.
Quenched in MeCN instead of MeOH.
Phthalaldehyde (0.75 mmol) was used. The crude product was a mixture of stereoisomers (Z/E¼13:87).
g
Product 18:
O
H
C6H5
OH
h
Product 19:
C6H5
O
OMe
O
Me3SiO
H
Ar
Ar
H
Ar
Ar
H
H
SiMe3
2
OSiMe3
OSiMe3
•
O
H
Ar
1
G
Siloxyallene
+
O
O
H
O
H
O
Ar
Ar
Ar
Ar
O
H
Ar
H
2
Ar
OSiMe3
2
SiMe3
SiMe3
H
Oxetene
Scheme 4.

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6263
F
OH
H
O
H
O
O
V(OSiPh3)3
(5 mol%)
OH
OH
+
20
+
F
F
O
Cl
F
Cl
H
80 °C, 20 h
18%
10
21
F
F
Product via siloxyallene
2d
10 : 21 = 3 : 2
F
OH
H
O
O=V(OSiPh3)3
(5 mol%)
F
OH
22
+
O
Cl
F
Cl
80 °C, 20 h
23%
H
23
2d
F
Product via oxetene
Scheme 5.
1
3
Thus, the reaction mechanism for the formation of the MBH
type adducts G would be as shown in Scheme 6. The silyl-
acetylene 1 would first add to the aldehyde 2 by the catalytic
action of the fluoride 5a to give the siloxypropyne 24. Iso-
merization of the acetylenic triple bond to the allene bond
would furnish the siloxyallene intermediate 25, which would
add the second aldehyde at the central carbon of the allene
function. The (Z)-geometry preference in the product would
be explained by the preferred chair form transition state I in
which the reaction exclusively would occur from the less
hindered site of the siloxyallene.
(0.5 mmol)
(0.71 mmol)
1) 5a (10 mol%)
+
2a
+
2a
CH2Cl2, 0 °C
2) 1N HCl
MeOH
(1.5 mmol)
(0.35 mmol)
+
4
+
24
(0.04 mmol)
(0.5 mmol)
Scheme 7.
amount of potassium tert-butoxide (KOt-Bu) to a mixture
of the siloxypropyne 24 and benzaldehyde (2a) in DMF
afforded the MBH type adduct 3 after acid treatment, as
shown in Scheme 8. Obviously, the reaction intermediate
will be the siloxyallene formed by isomerization of the sil-
oxypropyne1a,c,d,h–j As shown in Table 4, a combination of
KOt-Bu and DMF gave the superior result, and the reaction
Although no isomerization of 24 occurred by the action of
the ammonium fluoride 5a, treatment of a mixture of 1,
2a, and 24 with the catalyst 5a gave evidence of the conver-
sion of 24, as shown in Scheme 7. The base, e.g., phenylace-
tylide anion, probably generated in situ would participate in
the deprotonation of 24 to induce the isomerization to the
allene intermediate.
OSiMe3
O
H
O
2.2. Reaction of 1,3-diaryl-2-propynyl trimethylsilyl
ethers and aldehydes using potassium tert-butoxide
Base
(10 mol%)
1N HCl
H
OH
+
1 h
MeCN
The above consideration of the reaction mechanism sug-
gested that a base in addition to the fluoride ion might play
a key role in the reaction. In fact, addition of a catalytic
24
2a
3
Scheme 8.
O
Ar
SiMe3
Me3SiO
H
Ar
Ar
H
OSiMe3
H
ex. base
2
5a
1
24 : Ar = C6H5
25 : Ar = C6H5
O
Ar
H
Ar
H
Ar
H
2
SiMe3
OSiMe3
Ar
O
O
O
Ar
G
H
I
Scheme 6.

6264
K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
Table 4. Reaction of the siloxypropyne 2a with the aldehyde 2a using basea
1928 cm ,
ꢁ1 15 as shown in Scheme 9. Purification of the crude
product by silica gel column chromatography failed, and (Z)-
chalcone was obtained. This observation led us to an explo-
ration of the method for the synthesis of (Z)-chalcones, which
will be described later in this paper. Attempted isolation of
the siloxyallene failed in DMF probably because of higher
reactivity of the siloxyallene and its decomposition. The
siloxyallene was revealed to be quickly formed within
10 min at ꢁ78 ꢀC in THF, and 10 mol % of KOt-Bu was
sufficient to conduct the reaction.
Entry
Catalyst
Solvent
Temperature (ꢀC)
Yield (%)b
1
2
3
4
5
6
7
8
9
10
KOt-Bu
KOt-Buc
KOt-Bu
KOt-Buc
KOt-Bu
KOt-Bu
KOt-Bu
NaOt-Bu
LiOt-Bu
i-Pr2NEtd
DMF
DMF
THF
THF
THF
CH2CI2
DMF
DMF
DMF
DMF
ꢁ20
ꢁ20
ꢁ20
ꢁ20
rt
82
76
33
57
68
2
—
79
13
—
rt
ꢁ65
ꢁ20
ꢁ20
rt
Next, the reaction was conducted in two-step procedure: the
formation of the siloxyallene and then addition of the alde-
hyde. After acidic treatment, the desired MBH adduct was
obtained in good yield comparable to the one-step proce-
dure. Furthermore, it was found that addition of KOt-Bu to
a mixture of benzaldehyde (2a) and 1-phenyl-2-(trimethyl-
silyl)acetylene (1), a precursor of the siloxypropyne,
afforded the MBH adduct 3 though the yield was much lower
(33% yield). No or little amount of 3 was formed by the
reaction of benzaldehyde (2a) with phenylacetylene (26),
1,3-diphenylpropargyl alcohol (4), or 1,3-diphenylallyl
alcohol (28), as shown in Scheme 10.
a
Reaction time of all was 1 h.
b
Yields of 3 were assayed by HPLC analysis using YMC Pro C 18
(4.6 mmꢂ150 mm) column (UV 254 nm; flow rate, 1.0 mL/min; eluent,
MeCN/H2O/70% aq HClO4¼600:400:1 (v/v/v)).
KOt-Bu in THF (1 M) was used.
c
d
An excess (100 mol %) was used.
quickly proceeded at ꢁ20 ꢀC within 1 h. NaOt-Bu afforded
€
the comparable result while LiOt-Bu and Hunig base were
not suitable for the reaction.
Isolation of the siloxyallene 25 was accomplished through
the reaction of KOt-Bu with the siloxypropyne 24 without
the aldehyde 2a in THF. The crude product proved to be the
siloxyallene 25 by H NMR and IR spectra, the latter of
which exhibited absorption of the allene moiety at
The synthesis of the MBH type adducts catalyzed with
KOt-Bu was investigated using various substrates by two
methods: method A in which KOt-Bu was added to a mixture
1
OSiMe3
H
KOt-Bu in THF
C6H5CHO (2a)
OSiMe3
(1M, 10 mol%)
(1.2 eq)
1N HCl
MeCN
•
OH
THF
H
THF
-78 °C to 0 °C
1.5 h
-78 °C, 10 min
O
24
25
3
Scheme 9.
SiMe3
+
O
KOt-Bu
(10 mol%)
1N HCl
MeCN
H
OH
DMF
-20 °C, 1 h
O
1 1 eq
2a 1.5 eq
3 33%
H
OH
KOt-Bu
(10 mol%)
1N HCl
MeCN
2a
+
DMF
rt, 1 h
1.5 eq
26 1 eq
4 14%
OH
O
KOt-Bu
(10 mol%)
1N HCl
MeCN
3 (5%) + 4 (3%) +
+
2a
DMF
-20 °C to rt
3 h
1.2 eq
4 1 eq
27 57%
OH
KOt-Bu
(10 mol%)
1N HCl
MeCN
No reaction
Starting material was recovered.
2a
+
DMF
rt, 3 d
1.2 eq
28 1 eq
Scheme 10.

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6265
of the siloxypropyne 24 and the aldehyde 2 in DMF and
method B in which the siloxyallene 25 was first formed by
reaction of the siloxypropyne 24 with KOt-Bu in THF and
then the aldehyde 2 was added. As summarized in Table 5,
the siloxypropyne 24 rapidly reacted with various aldehydes
2 by use of a catalytic amount (10 mol %) of KOt-Bu to give
the MBH type adducts D with (Z)-configuration in good to
moderate yields. In general, method B gave a better result
than method A. As in the reaction using the fluoride catalyst
5a (entry 6 in Table 3), the reaction with 4-nitrobenzalde-
hyde (3f) resulted in the recovery of the starting aldehyde
by use of method A. In contrast, the MBH type adduct 33
was obtained in 67% yield using method B. Although 4-di-
methylaminobenzaldehyde (2l) did not give any products
when cinchoninium fluoride 5a was used (see entry 12 in
Table 3), the MBH type adduct 31 was obtained in 35% yield
by method A and the application of method B increased the
yield to 74%. The ester function of the aldehyde 2n and the
sterically hindered case such as 2o did not cause any trouble
and the MBH type products 32 and 34 were obtained in 83
and 68% yields, respectively. Method B proved to be supe-
rior in the reaction with 2-pyridylaldehyde (2q) and cinna-
maldehyde (2r), the latter of which did not give any 1,4-
adduct. A striking contrast between the reaction catalyzed
with the ammonium fluoride 5 and that using KOt-Bu was
observed in the reactions utilizing aliphatic aldehydes. Piv-
alaldehyde (2s) afforded the MBH type adduct 39 by method
A while only method B was effective for the reaction with
the aldehydes 2t and 2u having a-proton.
Then, the reaction procedure of method B was applied to the
reaction with ketones. Although 3-pentanone (42), aceto-
phenone (43), and ethyl acetoacetate (44) did not give any
MBH type adducts, the reaction with trifluoroacetophenone
(45) and a-ketoesters 46 and 47 proceeded to give the
MBH type adducts J, as shown in Table 6. In the latter
cases, the carbonyl functions of the ketones may be activated
by the electron-withdrawing functions, CF3 and esters, or
the reaction may proceed via a robust bicyclic transition
state 51.16
Table 5. Synthesis of b-substituted Morita–Baylis–Hillman type adducts D from the siloxypropyne 24 and various aldehydes 2
ArCHO (2, 1.2 eq), KOt-Bu (10 mol%)
Method A
OSiMe3
DMF, -20 °C, 1 h
H
Ar
OH
1N HCl
MeCN
O
ArCHO (2)
KOt-Bu
24
OSiMe3
(1.2 eq)
(10 mol%)
D
•
Method B
THF
-78 °C, 10 min
THF
-78 °C to 0 °C
1.5 h
H
25
RCHO
2
Method
D
Yield (%)a
RCHO
2
Method
A
D
Yield (%)a
95
A
B
82
85
2a
3
2j
35
36
CHO
CHO
O
CHO
Cl
2e
2c
A
A
29
30
76
72
2p
2q
A
83
S
CHO
MeO
Me2N
N
A
B
35
54
37
CHO
CHO
CHO
A
B
35
74
A
B
52
66
2l
2r
2s
31
32
38
39
CHO
MeO2C
O2N
2n
B
83
A
67
CHO
CHO
A
B
—
67
A
B
—
69
2f
2tb
33
34
40
41
CHO
CHO
Me
A
B
—
69
2ub
CHO
2o
A
CHO
68
Me
Method A: To a mixture of 24 and RCHO 2 in DMF was added KOt-Bu at ꢁ20 ꢀC. After being stirred at ꢁ20 ꢀC for 1 h, the mixture was quenched with
1 N aq HCl.
Method B: To a solution of 24 in THF was added KOt-Bu at ꢁ78 ꢀC. After 10 min, RCHO 2 was added at ꢁ78 ꢀC. The mixture was warmed to 0 ꢀC during 0.5 h,
stirred at 0 ꢀC for 1 h, and quenched with 1 N aq HCl.
Isolated yield.
The aldehyde (1.5 equiv) was used.
a
b

6266
K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
Table 6. Synthesis of b-substituted Morita–Baylis–Hillman type adducts J from the siloxypropyne 24 and ketones
R1
R2
OH
OSiMe3
R1COR2
(1.2 eq)
KOt-Bu
(10 mol%)
1N HCl
MeCN
THF
THF
-78 °C to 0 °C
1.5 h
O
-78 °C, 10 min
24
J
R1COR2
Yield (%)a
—
R1COR2
J
Yield (%)a
O
O
42b
43b
45b
48
78c
11
CF3
Me
O
O
O
O
SiMe3
—
—
46
49
50
O
CO2Me
O
O
R
H
O
44b
47
60c
51
CO2Me
CO2Et
a
b
c
Isolated yield.
R1COR2 (1.5 equiv) was used.
Trimethylsilyl ether was obtained.
Next, the reaction was carried out by use of various siloxy-
propynes C and aromatic aldehydes 2. The starting siloxy-
propynes C were prepared by (1) lithiation of acetylenes
with BuLi, (2) coupling with aldehydes, and then (3) O-silyl-
ation with Me3SiCl–Et3N. As expected, almost all the
reactions proceeded to give the MBH type adducts D by
use of method A, as shown in Table 7. Although method A
afforded the adducts in lower yield in the reaction with the
siloxypropynes 56 and 57, method B improved the yields.
The reaction with the alkyl derivatives 58 and 59 sluggishly
proceeded. This will be due to the lower acidity of the prop-
argylic proton, and no or little proton abstraction or isomer-
ization occurred.
to be deuterated in either case. This result clearly indicates
that t-BuO anion is not regenerated and recycled. Thus
KOt-Bu proved to be an initiator but not a catalyst in the
reaction, and the proton transfer would occur between the
allenyl anion 70 and the (starting) siloxypropyne C.
The reactivity of the siloxyallene was confirmed by mixing
the isolated crude siloxyallene 25 with benzaldehyde (2a)
to give the MBH type adduct 3 in DMF. However, the
reaction did not proceed in THF. As already described, the
reaction with cinnamaldehyde (2q) afforded the MBH type
adduct 38 as a sole isolable product but not 1,4-addition
product (see Table 5). This result would suggest the forma-
tion of the six-membered transition state K,17 and the alde-
hyde 2 would approach from the site of the hydrogen atom in
the siloxyallene A to furnish the (Z)-isomer with superior
stereoselectivity (Scheme 11).
The MBH type adducts D obtained by use of KOt-Bu were
(Z)-isomers, and no peaks of (E)-isomers were detected in
their H NMR spectra. NOE was observed in 63 and 64 as
1
shown in Figure 1, which further confirmed the (Z)-configu-
ration. The (Z)-configuration of the olefin part of the other
adducts could be assigned by analogy.
The reaction of the siloxypropyne 24 with the aldehyde 2a
did not proceed well when LiOt-Bu or BuLi was used as al-
ready described (Table 4). This will suggest the influence of
the cationic species. Furthermore, Reich and co-workers re-
ported stabilized propargyl anions, which were not easy to
isomerize to the allenyl anions.1d These interests led us to in-
vestigate the siloxyallene formation by use of the siloxypro-
pyne 73 having the tert-butyldimethylsilyl function instead
of the trimethylsilyl one, because the anion generated would
attack the silicon atom of the latter as a Lewis base and de-
composition would occur. As shown in Table 8, KOt-Bu was
effective for isomerization to form the siloxyallene 74 while
BuLi was not effective. Quenching the reaction using BuLi
with D2O afforded the deuterated siloxyallene accompanied
with the recovered starting siloxypropyne, which was not
deuterated. Thus, the reaction with BuLi would stop at the
allenyl anion stage in Scheme 11, and 73 would not form
the stabilized propargyl anion. The siloxyallene 74 thus ob-
tained was easily converted to (Z)-chalcone by column chro-
matography on silica gel. The different reactivity between
KOt-Bu and BuLi would be due to the strength of the
The mechanism for the formation of the MBH type adducts
D will be as shown in Scheme 11. Abstraction of the proton
from the propargyl position of the siloxypropyne C with
KOt-Bu would afford the propargyl anion 69 together with
t-BuOH. The propargyl anion 69 would be isomerized to
the allenyl anion 70, which would exchange the proton
with the other siloxypropyne C to give the siloxyallene A
and to regenerate the propargyl anion 69. The siloxyallene
A thus formed would react with the aldehyde 2 to produce
the MBH type adduct D via the six-membered transition
state K.
To prove whether t-BuOH generated in the first stage would
be regenerated to t-BuO anion and KOt-Bu would work as
a catalyst, the siloxypropyne 71 deuterated at the propargylic
position reacted with benzaldehyde (2a) in the presence of
10 mol % of KOt-Bu with or without t-BuOH, as shown in
Scheme 12. The MBH type adduct 72 obtained was found

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6267
Table 7. Synthesis of b-substituted Morita–Baylis–Hillman type adducts D from the siloxypropynes C and various aldehydes 2
H
Ar3
OH
Ar2
OSiMe3
Ar2
Ar3CHO (2, 1.2 eq), KOt-Bu (10 mol%)
Ar1
1N HCl
Ar1
O
C
D
Ar1
Ar2
C
Ar3CHO
2
Method
A
D
Yield (%)a
74
52
2a
60
Cl
CHO
MeO
2c
2a
2e
2c
A
A
A
A
61
62
63
9
71
83
83
79
CHO
53
OMe
CHO
CHO
Cl
MeO
CHO
54
55
2a
2a
A
A
64
65
80
76
O
S
CHO
CHO
CHO
A
B
40
78
56
2a
66
N
A
B
28
50
57
58
59
2a
2a
2a
67
68
—
CHO
n-C4H9
Ab
A
23
—
CHO
CHO
n-C4H9
Method A: To a mixture of C and Ar3CHO 2 in DMF was added KOt-Bu at ꢁ20 ꢀC. After being stirred at ꢁ20 ꢀC for 1 h, the mixture was quenched with
1 N aq HCl.
Method B: To a solution of C in THF was added KOt-Bu at ꢁ78 ꢀC. After 10 min, Ar3CHO 2 was added at ꢁ78 ꢀC. The mixture was warmed to 0 ꢀC during
0.5 h, stirred at 0 ꢀC for 1 h, and quenched with 1 N aq HCl.
Isolated yield.
a
b
KOt-Bu (20 mol %) was used.
11%
11%
7%
8%
ammonium fluorides, 5a–c, described in Section 2.1 (Table
1), in which the free hydroxyl function influenced the reac-
tion. Interestingly, choline fluoride also catalyzed the reac-
tion of the silylacetylene 1 with benzaldehyde (2a) in
DMF to give 6a as the MBH type adduct 3 in 59% yield
while 4 was obtained in 8% yield after acid treatment.
This result is contrary to that using TBAF and will suggest
the importance of the presence of the b-hydroxyl function
in the cinchoninium salt.
Cl
H
H
O
H
H
OH
OH
O
O
OMe
63
64
Figure 1.
coordination to the anionic species, and higher coordination
of the lithium atom would stabilize the allenyl anion and the
reaction would not proceed further.
2.3. Attempts for the enantioselective reaction
The enantioselectivity for the synthesis of the MBH type
adduct 3 was less than 10% ee by use of the cinchoninium
fluoride 5, as already described in Section 2.1 (Table 1). We
already reported an enantioselective synthesis of optically
Such difference of the cationic species was also observed in
the MBH type adduct synthesis utilizing the quaternary

6268
K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
OSiMe3
Ar2
H
Ar1
C
t-BuO
t-BuOH
Ar2
O
DMF
and
Ot-Bu
H
Ar3
H
OSiMe3
Ar1
H
OSiMe3
Ar2
Si
2
O
Ar2
O
Ar1
Ar1
Ar3
A
69
K
H
H+
Ar3
OH
OSiMe3
H
H
Ar1
OSiMe3
Ar2
Ar2
Ar1
Ar1
C
Ar2
70
D
O
Scheme 11.
OSiMe3
D
O
O
D
A) KOt-Bu (10 mol%)
DMF, -20 °C
H+
OH
H
+
B) KOt-Bu (10 mol%)
t-BuOH (100 mol%)
DMF, -20 °C
2a
71
D = 99%
A : 48%, D = 96%
B : 43%, D = 93%
72
Scheme 12.
Table 8. Deuteration results using the siloxypropyne 73
OSit-BuMe2
OSit-BuMe2
Quenched with
H2O or D2O
H or D
H
Base
THF
OSit-BuMe2
•
+
-78 °C
20 min
H or D
73
161 mg
74
73
Base
Quench
Recovery (mg)
74:73
KOt-BU (10 mol %)
n-BuLi (20 mol %)
n-BuLi (20 mol %)
H2O
H2O
D2O
151
157
158
100:0
22:78
22:78a
a
D content of 74 was 78%, but no deuteride was observed in 73.
active allenes from 1,3-biarylpropynes by a combination of
base (KOH) and a chiral PTC derived from cinchonine.18
These facts led us to investigate to change the racemic
synthesis of the MBH type adduct utilizing KOt-Bu to an
enantioselective one. Thus, a combination of chiral quater-
nary ammonium salts and various bases was applied to the
reaction of the siloxypropyne 24 with benzaldehyde (2a).
The results are shown in Table 9. Although most of the reac-
tion proceeded as expected, no increase of enantioselectivity
was observed at all.
2.3.1. Synthesis of (Z)-chalcone derivatives. As described
earlier, the crude siloxyallene 25 formed from the siloxy-
propyne 24 by the action of KOt-Bu was transformed to
(Z)-chalcone by column chromatography on silica gel. In
addition, (Z)-chalcone was obtained as the major product
when acetic acid was used instead of benzaldehyde (2a)
in the two-step conversion of the siloxypropyne 25 to
the MBH type adduct using KOt-Bu. Although many
(E)-and (Z)-chalcone derivatives are biologically active20a
as well as substrates for the evaluation of various organic
reactions,20b,c their preparative methods have been mainly
concerned with thermodynamically stable (E)-isomers be-
cause of their easy preparation, and very few reports have
been concerned with the synthesis of (Z)-isomers.20 In
general, photoisomerization of (E)-chalcones will be the
choice of method for the (Z)-isomer synthesis. However,
it takes time and a special apparatus for photochemical
reactions.21
Furthermore, the reaction utilizing the optically active siloxy-
propyne 2419 and benzaldehyde (2a) afforded the MBH type
adduct 3, but a great loss of enantiomeric purity was
observed in the MBH type adduct, as shown in Scheme 13.
Further investigation will be necessary to determine which
step, the siloxyallene formation or reaction with the alde-
hyde, will induce racemization.

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
Table 9. Attempted asymmetric synthesis of Morita–Baylis–Hillman type adduct 3
6269
O
C6H5CHO (2a)
Base (1 eq)
H
OSiMe3
PTC (10 mol%)
OH
1N HCl
MeCN
+
rt, 15 h
O
27
24
3
Entry
Base
Solvent
PTC
Yield (%)a (ee%)b
3
27
24
1
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
THF
THF
THF
THF
THF
—
TBAB
6
7
75
—
56
72 (9)
30 (3)
57 (3)
—
28
24
35
39
Quant.
—
—
26
—
TBAB
n-Bu4N+Br-
2
3c
4d
5e
RO
N+
6
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
THF
THF
THF
THF
—
TBAB
6
7
—
56
72 (9)
37 (2)
—
28
22
42
Quant.
—
—
Br-
7
8f
9d
N
19
6 : R = H
7 : R = Bn
10
K2CO3
THF
6
—
—
Quant.
11
12
K3PO4
K3PO4
CH2Cl2
CH2Cl2
TBAB
6
3
57 (3)
3
31
80
14
Cl-
N+
13
14
K3PO4
K3PO4
Toluene
Toluene
TBAB
6
49
—
19
—
28
Quant.
N
OH
75
a
Yields of 3 were assayed by HPLC analysis using YMC Pro C 18 (4.6 mmꢂ150 mm) column (UV 254 nm; flow rate, 1.0 mL/min; eluent, MeCN/H2O/70% aq
HClO4¼600:400:1 (v/v/v)).
b
c
d
e
f
ee% was determined by DAICEL CHIRALCEL OD (4.6 mmꢂ150 mm) column (UV 254 nm; flow rate, 1 mL/min; eluent n-hexane/i-PrOH¼9:1 (v/v)).
Reacted for 6 h.
Reacted for 20 h.
Reacted for 4 h.
Reacted for 2 h.
OSiMe3
KOt-Bu in THF
C6H5CHO
H
O
OSiMe3
(1M, 10 mol%)
(2a, 1.2 eq)
1N HCl
*
*
•
OH
-78 °C
0.5 h
MeCN
-78 °C, 10 min
H
24
87% ee
25
3
Reaction Solvent, Yield of 3 (% ee) : THF, 83% (29% ee); MeOt-Bu 34% (26% ee); CH2Cl2, 66% (12% ee)
Scheme 13.
Our experimental results together with consideration of the
above situation led us to explore a general synthetic method
for (Z)-chalcone derivatives.4 Preliminary survey of the re-
action conditions suggested that addition of concd sulfuric
acid in 1,2-dimethoxyethane (DME) would give a better
result after the formation of the siloxyallene 25 from the si-
loxypropyne 24 by the action of KOt-Bu in THF. The results
of the (Z)-chalcone synthesis under this preferred reaction
conditions are summarized in Table 10. Most of the (Z)-
chalcone derivatives E have been conveniently synthesized
at ꢁ78 ꢀC as the major product. However, in the case of the
4-nitro substrate 76, the isomerization from the siloxypro-
pyne to the siloxyallene did not proceed even at 0 ꢀC. The
reaction of siloxypropyne 77 having the sterically hindered
20,60-dimethylphenyl group at the Ar2 position did not pro-
ceed at all, while another 2,6-dimethylphenyl analog 95
was obtained though in moderate yield. In the latter case,
isomerization of the siloxypropyne 83 to the siloxyallene
was not complete and 83 remained after the reaction.
Thus the steric influence will be quite significant in the re-
action. Exceptionally, the siloxypropyne 78 having the 4-
methoxyphenyl function at the vinyl position afforded the
(E)-isomer 90 only though the crude product was a mixture
of (Z)- and (E)-isomers in a ratio of 25:75. Some of the prod-
ucts were isomerized during the reaction and/or purification
on a silica column. Isomerization during purification could
be prevented if a suitable workup for each product was
devised.
Treatment of the tert-butyldimethylsilyl ether 96 with
10 mol % of KOt-Bu afforded the siloxyallene 97, which
was converted to the crude (Z)-chalcone (84, Z/E¼92:8)
(Scheme 14). Purification by one recrystallization from hex-
ane gave pure (Z)-chalcone (84, Z/E¼>99:1) in 74% yield.
The (Z)-geometry preference of the chalcone derivatives E
will be explained by the preference of the protonation in

6270
K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
Table 10. Synthesis of (Z)-chalcones
H
O
OSiMe3
Ar2
Ar1
H
OSiMe3
Ar2
H
Ar1
KOt-Bu (10 mol%)
H2SO4
•
THF
-78 °C, 10 min
Ar2
DME
-78 °C, 10 min
Ar1
C
A
E
Ar1
Ar2
C
E
Yield (%)a
82
Z/Eb
Ar1
Ar2
C
E
Yield (%)a
75
Z/Eb
24
84
93:7
57
78
89
80:20 (84:16)
52
85
86
73
88:12
90
76
E only (25:75)
Cl
MeO
53
76
54
55
66
—
83
76
97:3
—
79
80
81
82
91
92
93
94
54
71
85
82
85:15 (89:11)
90:10
OMe
NO2
O
O
Cl
87
88
93:7
95:5
80:20 (95:5)
97:3
O
S
S
Me
Me
77
—
—
83
95
54
70:30
Me
Me
Isolated yield.
a
Z/E ratio was determined by 1H NMR analysis. Parentheses are Z/E ratio of crude product. No parenthesis depicts no isomerization during the purification
step.
b
H
O
OSit-BuMe2
KOt-Bu
H
(10 mol%)
H2SO4
OSit-BuMe2
•
THF
DME
-78 °C
10 min
H
-78 °C, 10 min
96
97
84
74%, Z : E = >99 : 1
Scheme 14.
Ar2
aldehydes to give the MBH type adducts. Furthermore, the
siloxyallene intermediates afforded (Z)-chalcone derivatives
with sulfuric acid.
SiMe3
H
O
H
Ar1
A
Further application of the siloxyallenes to organic synthesis
will be waited.
Figure 2.
which the reaction mainly occurs from the less hindered site
of the siloxyallene A, as shown in Figure 2.
4. Experimental
4.1. General
3. Conclusion
In conclusion, siloxyallenes well proved to be a useful func-
tional intermediate in organic synthesis. The reaction of si-
lylacetylenes with aromatic aldehydes was catalyzed with
the quaternary ammonium fluoride derived from cinchonine,
giving the b-branched MBH type adducts in moderate to
good yields via the siloxypropyne and siloxyallene interme-
diates. Treatment of the siloxypropyne with a small amount
of KOt-Bu afforded the siloxyallene, which reacted with
Melting points were determined on a Yamato MP-21 appara-
tus and are uncorrected. Optical rotations were measured
with a JASCO DIP-1000 digital polarimeter. IR spectra
were measured with a Perkin–Elmer 1600 FTIR spectrome-
ter. 1H NMR and 13C NMR spectra were recorded on JEOL
JNM-ALPHA 400 or JNM-AL 400 spectrometer with tetra-
methylsilane, chloroform or dimethyl sulfoxide as an inter-
nal standard. High-resolution MS spectra were measured

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6271
on a JEOL MS-700 or HX-100 spectrometer. HPLC analysis
was performed on a Shimadzu LC-10AVP high-performance
liquid chromatograph. TLC was done on precoated
(0.25 mm) Merck silica gel F254 plates. Silica gel (Merck
Silica gel 60 of 0.040–0.063 mm for column chromato-
graphy) was used for column chromatography.
1H), 8.15 (d, J¼8.5 Hz, 1H), 8.70 (d, J¼8.3 Hz, 1H), 8.96
(d, J¼6.3 Hz, 1H).
4.1.4. (2Z)-2-[Hydroxy(phenyl)methyl]-1,3-diphenyl-
prop-2-en-1-one (3).8 Typical procedure. To a solution of
the catalyst 5a (40 mg, 0.1 mmol) and benzaldehyde (2a,
0.153 mL, 1.5 mmol) in CH2Cl2 (2 mL) was added 1-phen-
yl-2-(trimethylsilyl)acetylene (1, 0.197 mL, 1.0 mmol) at
ꢁ20 ꢀC under Ar, and then the mixture was immediately
warmed to 0 ꢀC. After 1 h, 1 N aq HCl (1 mL) and methanol
(4 mL) were added, and the mixturewas stirred for only a few
minutes at 0 ꢀC. Water, brine, and EtOAc were added, and the
separated organic layer was washed with brine and dried over
MgSO4. After removal of the solvent in vacuo, the residue
was purified by silica gel column chromatography (hexane/
EtOAc, 10:1) to give 3 (219 mg, 92%) as a white solid and
4.1.1. N-Benzylcinchoninium fluoride (5a).5 Amberlyst A-
26 resin (chloride ion form, 10 mL) swollen in water over-
night was packed in a column and converted to its hydroxide
ion form by passing 1 N aqueous sodium hydroxide
(150 mL) until no turbidity was observed with aqueous silver
nitrate in the eluate acidified with 10% aqueous nitric acid.
The resin was washed with water (200 mL) until the eluate
became neutral and then with methanol (200 mL). N-Benzyl-
cinchoninium chloride (842 mg, 2.0 mmol) in methanol
(20 mL) was slowly passed through the resin, and the resin
was washed with methanol (10 mLꢂ2). The eluate was
neutralized with 1 mmol/g aqueous hydrofluoric acid (ca.
2 g, 2.0 mmol) until pH of the eluate became ca. 7, and
concentrated in vacuo. The residue was co-evaporated with
toluene/acetonitrile (1:1) a few times and dried invacuo over-
night. The fluoride 5a was quantitatively obtained as a pale
brown amorphous solid (848 mg) and used for the next step
without further purification: 1H NMR (DMSO-d6,
400 MHz) d 0.79–0.88 (m, 1H), 1.42–1.52 (m, 3H), 2.24–
2.30 (m, 1H), 2.52–2.59 (m, 1H), 2.94 (dd, J¼9.2, 20.2 Hz,
1H), 3.14 (t, J¼11.1 Hz, 1H), 3.71 (t, J¼9.3 Hz, 1H), 3.76 (t,
J¼10.5 Hz, 1H), 4.50 (br s, 1H), 4.88 (d, J¼11.7 Hz, 1H),
5.03 (s, 1H), 5.20 (d, J¼8.3 Hz, 1H), 5.55 (d, J¼7.3 Hz,
1H), 5.96–6.05 (m, 1H), 6.33 (s, 1H), 7.47–7.53 (m, 3H),
7.63–7.78 (m, 4H), 7.84 (d, J¼4.4 Hz, 1H), 8.04 (d, J¼
8.3 Hz, 1H), 8.20 (d, J¼8.3 Hz, 1H), 8.87 (d, J¼4.4 Hz, 1H).
4.1.2. N,O-Dibenzylcinchoninium fluoride (5b).9b N,O-
Dibenzylcinchoninium bromide (1.11 g, 2.0 mmol) was
treated as described for the synthesis of 5a. The fluoride 5b
was quantitatively obtained as a pale brown amorphous solid
(1.02 g): 1H NMR (CDCl3, 400 MHz) d 1.15–1.25 (m, 1H),
1.50–1.54 (m, 1H), 1.70–1.77 (m, 1H), 1.93 (br s, 1H),
1.97–2.05 (m, 1H), 2.35–2.43 (m, 2H), 2.72 (dd, J¼9.5,
21.0 Hz, 1H), 3.38 (t, J¼11.5 Hz, 1H), 4.07 (d, J¼11.7 Hz,
1H), 4.40 (d, J¼11.5 Hz, 1H), 4.60–4.75 (m, 2H), 4.83 (t,
J¼11.5 Hz, 1H), 5.09 (d, J¼10.0 Hz, 1H), 5.25 (d,
J¼10.5 Hz, 1H), 5.82–5.92 (m, 2H), 6.32 (br s, 1H), 7.28–
7.52 (m, 10H), 7.68 (br s, 1H), 7.81 (t, J¼7.5 Hz, 1H), 7.93
(br s, 1H), 8.17 (d, J¼8.5 Hz, 1H), 8.70 (d, J¼8.1 Hz, 1H),
9.01 (d, J¼4.4 Hz, 1H).
4
19b (15 mg, 7%).
Compound 3: mp 77 ꢀC; IR (neat) n 3373, 3060, 1634, 1591,
1
1447, 1372, 1236, 1020, 965, 757, 695 cmꢁ1; H NMR
(CDCl3, 400 MHz) d 3.14 (d, J¼4.9 Hz, 1H), 5.73 (d,
J¼4.9 Hz, 1H), 6.97 (s, 1H), 7.03–7.09 (m, 5H), 7.13–7.16
(m, 2H), 7.20–7.24 (m, 1H), 7.29–7.32 (m, 3H), 7.44 (d,
J¼7.6 Hz, 2H), 7.63 (d, J¼7.3 Hz, 2H); 13C NMR (CDCl3,
100 MHz) d 76.7, 126.2, 127.6, 127.8, 127.8, 128.1, 128.7,
129.1, 131.9, 132.8, 134.6, 135.7, 140.5, 141.5, 199.9;
Anal. calcd for C22H18O2: C, 84.05; H, 5.77. Found: C,
84.20; H, 5.81.
Compound 4: 1H NMR (CDCl3, 400 MHz) d 2.29 (m, 1H),
5.69 (d, J¼6.3 Hz, 1H), 7.31–7.38 (m, 4H), 7.39–7.44 (m,
2H), 7.47–7.49 (m, 2H), 7.61–7.64 (m, 2H). The enantio-
meric excess was determined by HPLC analysis: DAICEL
CHIRALCEL OD (4.6 mm i.d.ꢂ250 mm), UV 254 nm,
flow rate 1.0 mL/min, hexane/2-propanol¼9:1, retention
time 3: 12.3 min, 14.1 min; 4: 13.1 min, 19.8 min.
4.1.5. Preparation of (2Z)-2-[hydroxy(phenyl)methyl]-
1,3-diphenylprop-2-en-1-one (3) using catalytic amount
of quaternary ammonium bromide and CsF. To a solution
of the catalyst 6 (47 mg, 0.1 mmol) and CsF (15 mg,
0.1 mmol) in CH2Cl2 (2 mL) was added benzaldehyde (2a,
0.153 mL, 1.5 mmol) followed by 1-phenyl-2-(trimethyl-
silyl)acetylene (1, 0.197 mL, 1.0 mmol) at ꢁ20 ꢀC under
Ar, and then the mixture was immediately warmed to
0 ꢀC. After 1 h, workup as described previously followed
by silica gel column chromatography (hexane/EtOAc,
10:1) gave 3 (169 mg, 72%) as a white solid and 4 (40 mg,
19%).
4.1.3. O-Allyl-N-benzylcinchoninium fluoride (5c).22 As
described for the synthesis of 5a, O-allyl-N-benzylcinchoni-
nium bromide (1.01 g, 2.0 mmol) was treated. The fluoride
5c was quantitatively obtained as a pale brown amorphous
4.1.6. (2Z)-2-[Hydroxy(4-methylphenyl)methyl]-1-(4-
methylphenyl)-3-phenylprop-2-en-1-one (8). As described
for the synthesis of 3, 1-phenyl-2-(trimethylsilyl)acetylene
(1, 0.197 mL, 1.0 mmol) and 4-methylbenzaldehyde (2b,
0.177 mL, 1.5 mmol) were treated with the catalyst 5a
(40 mg, 0.1 mmol) in CH2Cl2 (2 mL) at ꢁ20 ꢀC for 1 h.
Workup as described previously followed by silica gel col-
umn chromatography (hexane/EtOAc, 3:1) gave 8 (223 mg,
87%) as a white solid: mp 100 ꢀC; IR (neat) n 3393, 3026,
1635, 1602, 1446, 1362, 1240, 1179, 1027, 936, 812, 755,
1
solid (0.88 g): H NMR (CDCl3, 400 MHz) d 1.10–1.15
(m, 1H), 1.75–1.80 (m, 1H), 1.95–2.05 (m, 2H), 2.25–2.35
(m, 1H), 2.45–2.50 (m, 1H), 2.80 (dd, J¼9.8, 21.0 Hz, 1H),
3.56 (t, J¼11.5 Hz, 1H), 4.01 (dd, J¼6.4, 12.7 Hz, 1H),
4.17–4.25 (m, 2H), 4.45 (d, J¼11.9 Hz, 1H), 4.65 (t, J¼
8.8 Hz, 1H), 4.72 (t, J¼11.4 Hz, 1H), 5.22 (d, J¼17.3 Hz,
1H), 5.31 (d, J¼10.5 Hz, 1H), 5.39 (d, J¼10.2 Hz, 1H),
5.43 (d, J¼16.9 Hz, 1H), 5.87–5.95 (m, 1H), 6.07–6.13 (m,
2H), 6.26 (br s, 1H), 7.49–7.51 (m, 3H), 7.55–7.63 (m,
1H), 7.68–7.73 (m, 2H), 7.77–7.81 (m, 1H), 7.89 (br s,
692 cmꢁ1 1H NMR (CDCl3, 400 MHz) d 2.25 (s, 3H),
;
2.30 (s, 3H), 3.02–3.05 (m, 1H), 5.67 (d, J¼4.6 Hz, 1H),
6.90 (d, J¼1.2 Hz, 1H), 6.96 (d, J¼7.8 Hz, 2H), 7.03–7.12

6272
K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
(m, 7H), 7.31 (d, J¼8.0 Hz, 2H), 7.58 (d, J¼8.1 Hz, 2H); 13
C
5a (40 mg, 0.1 mmol) in CH2Cl2 (2 mL) at ꢁ20 ꢀC for
1 h. Workup as described previously followed by silica gel
column chromatography (hexane/EtOAc, 5:1) gave 11
(257 mg, 89%) as a white solid: mp 151 ꢀC; IR (neat) n
3466, 1664, 1587, 1492, 1365, 1228, 1084, 974, 823, 755,
NMR (CDCl3, 100 MHz) d 21.1, 21.6, 76.6, 126.2, 127.6,
127.7, 128.6, 128.7, 128.8, 129.3, 131.2, 133.3, 134.7,
137.2, 137.6, 141.7, 143.7, 199.5; Anal. calcd for
C24H22O2: C, 84.18; H, 6.48. Found: C, 84.04; H, 6.52.
696 cmꢁ1
;
1H NMR (CDCl3, 400 MHz) d 3.11 (d,
4.1.7. (2Z)-2-[Hydroxy(4-methoxyphenyl)methyl]-1-
(4-methoxyphenyl)-3-phenylprop-2-en-1-one (9). As
described for the synthesis of 3, 1-phenyl-2-(trimethylsilyl)-
acetylene (1, 0.197 mL, 1.0 mmol) and 4-methoxybenzalde-
hyde (2c, 0.183 mL, 1.5 mmol) were treated with the catalyst
5a (40 mg, 0.1 mmol) in CH2Cl2 (2 mL) at ꢁ20 ꢀC for 1 h.
Workup as described previously followed by silica gel col-
umn chromatography (hexane/EtOAc, 2:1) gave 9 (96 mg,
37%) as a white foam, 1323 (13 mg, 5%), and methyl ether
of 13 (118 mg, 47%).
J¼4.9 Hz, 1H), 5.70 (d, J¼4.9 Hz, 1H), 6.99 (s, 1H),
7.06–7.09 (m, 5H), 7.12 (d, J¼8.8 Hz, 2H), 7.28 (d,
J¼8.6 Hz, 2H), 7.37 (d, J¼8.3 Hz, 2H), 7.55 (d, J¼8.7 Hz,
2H); 13C NMR (CDCl3, 100 MHz) d 76.0, 127.5, 127.9,
128.2, 128.3, 128.4, 128.6, 130.3, 132.5, 133.4, 134.0,
134.2, 139.0, 139.4, 140.6, 198.4; Anal. calcd for
C22H16Cl2O2: C, 68.94; H, 4.21. Found: C, 68.94; H, 4.26.
4.1.10. (2Z)-1-(3,4-Dimethoxyphenyl)-2-[(3,4-dimethoxy-
phenyl)(hydroxy)methyl]-3-phenylprop-2-en-1-one (12).
To a solution of the catalyst 5a (40 mg, 0.1 mmol) and
2,3-dimethoxybenzaldehyde (2g, 0.153 mL, 1.5 mmol) in
CH2Cl2 (2 mL) was added 1-phenyl-2-(trimethylsilyl)acetyl-
ene (1, 0.197 mL, 1.0 mmol) at ꢁ20 ꢀC under Ar, and then
the mixture was immediately warmed to 0 ꢀC. After 1 h,
1 N aq HCl (1 mL) and acetonitrile (10 mL) were added,
and the mixture was stirred for only a few minutes. Water,
brine, and EtOAc were added, and the separated organic
layer was washed with brine and dried over MgSO4. After
removal of the solvent in vacuo, the residue was purified
by silica gel column chromatography (hexane/EtOAc, 2:1)
to give 12 (74 mg, 23%) as a white foam and 14 (71 mg,
26%) as a white solid.
Compound 9: IR (neat) n 3415, 2969, 1645, 1592, 1509,
1462, 1364, 1240, 1164, 1026, 955, 831, 756, 694 cmꢁ1
;
1H NMR (CDCl3, 400 MHz) d 3.10 (d, J¼4.6 Hz, 1H),
3.74 (s, 3H), 3.76 (s, 3H), 5.65 (d, J¼4.6 Hz, 1H), 6.64 (d,
J¼8.8 Hz, 2H), 6.83 (d, J¼8.5 Hz, 2H), 6.89 (s, 1H), 7.06–
7.14 (m, 5H), 7.34 (d, J¼8.8 Hz, 2H), 7.65 (d, J¼8.8 Hz,
2H); 13C NMR (CDCl3, 100 MHz) d 55.1, 55.2, 76.4,
113.2, 113.5, 127.5, 127.6, 127.8, 128.6, 128.8, 130.6,
131.6, 132.8, 134.7, 141.8, 158.8, 163.2, 198.4; Anal. calcd
for C24H22O4: C, 76.99; H, 5.92. Found: C, 76.81; H, 6.05.
Compound 13: 1H NMR (CDCl3, 400 MHz) d 2.18–2.31 (m,
1H), 5.65 (d, J¼6.1 Hz, 1H), 6.93 (dd, J¼2.1, 6.8 Hz, 2H),
7.30–7.34 (m, 3H), 7.46–7.48 (m, 2H), 7.55 (dd, J¼2.1,
6.6 Hz, 2H).
Compound 12: IR (neat) n 3492, 2935, 1642, 1579, 1510,
1
1462, 1417, 1260, 1134, 1020, 761, 696 cmꢁ1; H NMR
(CDCl3, 400 MHz) d 3.13 (d, J¼4.6 Hz, 1H), 3.77 (s, 3H),
3.81 (s, 3H), 3.82 (s, 3H), 3.84 (s, 3H), 5.65 (d, J¼4.4 Hz,
1H), 6.57 (d, J¼8.6 Hz, 1H), 6.79 (d, J¼8.8 Hz, 1H), 6.92
(s, 1H), 6.96–6.98 (m, 2H), 7.07–7.10 (m, 5H), 7.28–7.30
(m, 2H); 13C NMR (CDCl3, 100 MHz) d 55.65, 55.72,
55.75, 55.77, 77.0, 109.4, 109.57, 109.64, 118.6, 124.8,
127.8, 127.9, 128.6, 128.8, 130.6, 133.3, 134.7, 141.6,
148.3, 148.6, 153.1, 198.3; Anal. calcd for C26H26O6: C,
71.87; H, 6.03. Found: C, 71.54; H, 6.19.
Methyl ether of 13: 1H NMR (CDCl3, 400 MHz) d 3.46 (s,
3H), 3.82 (s, 3H), 5.26 (s, 1H), 6.91 (d, J¼8.8 Hz, 2H),
7.30–7.32 (m, 3H), 7.46–7.50 (m, 4H).
4.1.8. (2Z)-1-(4-Fluorophenyl)-2-[(4-fluorophenyl)-
(hydroxy)methyl]-3-phenylprop-2-en-1-one (10). As
described for the synthesis of 3, 1-phenyl-2-(trimethylsilyl)-
acetylene (1, 0.197 mL, 1.0 mmol) and 4-methoxybenzalde-
hyde (2d, 0.161 mL, 1.5 mmol) were treated with the catalyst
5a (40 mg, 0.1 mmol) in CH2Cl2 (2 mL) at ꢁ20 ꢀC for 1 h.
Workup as described previously followed by silica gel
column chromatography (hexane/EtOAc, 5:1) gave 10
(235 mg, 89%) as a white solid: mp 113 ꢀC; IR (neat) n
3453, 1665, 1597, 1503, 1408, 1222, 1150, 1034, 973, 827,
Compound 14: mp 87 ꢀC; IR (neat) n 3274, 2934, 1592,
1
1518, 1416, 1237, 1133, 1022, 984, 755, 690 cmꢁ1; H
NMR (CDCl3, 400 MHz) d 2.21 (d, J¼6.1 Hz, 1H), 3.90
(s, 3H), 3.93 (s, 3H), 5.65 (d, J¼6.1 Hz, 1H), 6.88 (d,
J¼8.8 Hz, 1H), 7.16–7.18 (m, 2H), 7.31–7.33 (m, 3H),
7.46–7.48 (m, 2H); 13C NMR (CDCl3, 100 MHz) d 55.78,
55.84, 77.0, 86.3, 88.5, 109.7, 110.7, 118.8, 122.1, 128.0,
128.3, 131.3, 131.4, 148.75, 148.82; Anal. calcd for
C26H26O6: C, 76.10; H, 6.01. Found: C, 76.00; H, 6.10.
1
754, 696 cmꢁ1; H NMR (CDCl3, 400 MHz) d 3.11 (d,
J¼4.9 Hz, 1H), 5.70 (d, J¼4.9 Hz, 1H), 6.99 (s, 1H), 7.06–
7.09 (m, 5H), 7.12 (d, J¼8.8 Hz, 2H), 7.28 (d, J¼8.6 Hz,
2H), 7.37 (d, J¼8.3 Hz, 2H), 7.55 (d, J¼8.7 Hz, 2H); 13C
NMR (CDCl3, 100 MHz) d 76.0, 115.10 (d, J¼19.9 Hz),
115.11 (d, J¼21.6 Hz), 127.8 (d, J¼8.3 Hz), 127.9, 128.1,
128.6, 131.7 (d, J¼9.1 Hz), 131.9, 132.1 (d, J¼2.4 Hz),
134.3, 136.3 (d, J¼3.3 Hz), 141.1, 161.9 (d, J¼244.7 Hz),
165.3 (d, J¼253.8 Hz), 198.1; Anal. calcd for C22H16F2O2:
C, 75.42; H, 4.60. Found: C, 75.25; H, 4.70.
4.1.11. (2Z)-1-(1,3-Benzodioxol-5-yl)-2-[1,3-benzodioxol-
5-yl(hydroxy)methyl]-3-phenylprop-2-en-1-one (15). As
described for the synthesis of 3, 1-phenyl-2-(trimethylsilyl)-
acetylene 1 (0.197 mL, 1.0 mmol) and piperonal (2h,
225 mg, 1.5 mmol) were treated with the catalyst (5a,
40 mg, 0.1 mmol) in CH2Cl2 (2 mL) at ꢁ20 ꢀC for 1 h.
Workup as described previously followed by silica gel
column chromatography (hexane/EtOAc, 3:1) gave 15
(262 mg, 87%) as a white solid: mp 133 ꢀC; IR (neat) n
3352, 1619, 1590, 1486, 1441, 1365, 1248, 1035, 928,
4.1.9. (2Z)-1-(4-Chlorophenyl)-2-[(4-chlorophenyl)-
(hydroxy)methyl]-3-phenylprop-2-en-1-one (11). As
described for the synthesis of 3, 1-phenyl-2-(trimethylsilyl)-
acetylene (1, 0.197 mL, 1.0 mmol) and 4-chlorobenzalde-
hyde (2e, 211 mg, 1.5 mmol) were treated with the catalyst
1
807, 759, 696 cmꢁ1; H NMR (CDCl3, 400 MHz) d 3.05

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6273
(br s, 1H), 5.60 (d, J¼4.6 Hz, 1H), 5.92 (d, J¼2.4 Hz, 4H),
6.53 (d, J¼8.6 Hz, 1H), 6.72 (d, J¼8.1 Hz, 1H), 6.86 (d,
J¼8.0 Hz, 1H), 6.88 (s, 1H), 7.08–7.12 (m, 5H), 7.22–7.25
(m, 3H); 13C NMR (CDCl3, 100 MHz) d 100.8, 101.5,
106.8, 107.4, 107.8, 108.1, 119.8, 126.6, 127.7, 127.8,
128.6, 130.6, 130.8, 134.60, 134.61, 141.5, 146.8, 147.4,
147.5, 151.6, 197.7; Anal. calcd for C24H18O6: C, 71.64;
H, 4.51. Found: C, 71.19; H, 4.66.
2H); 13C NMR (CDCl3, 100 MHz) d 68.7, 123.5, 125.7,
128.7, 129.5, 130.2, 131.5, 133.5, 135.1, 136.7, 136.9,
137.4, 151.0, 191.9; Anal. calcd for C16H12O2: C, 81.34;
H, 5.12. Found: C, 80.95; H, 5.18.
Compound 19: IR (neat) n 2932, 1490, 1370, 1326, 1192,
1
1086, 964, 748, 690 cmꢁ1; H NMR (CDCl3, 400 MHz)
d 3.41 (s, 1.5H), 3.53 (s, 1.5H), 6.04 (s, 0.5H), 6.24 (d,
J¼6.1 Hz, 0.5H), 6.27 (d, J¼1.6 Hz, 0.5H), 6.30 (s, 0.5H),
7.27–7.31 (m, 3H), 7.40–7.47 (m, 6H); 13C NMR (CDCl3,
100 MHz) d 53.1, 55.3, 72.5, 72.7, 85.9, 86.0, 86.1, 86.8,
106.6, 107.0, 121.6, 121.7, 121.9, 122.2, 122.6, 122.7,
122.8, 127.86, 127.90, 128.2, 128.31, 128.34, 129.3,
129.5, 131.5, 131.6, 136.3, 137.0, 140.0, 140.1; HRMS
(EI) calcd for C20H16O2S (M+) 250.0994, Found 250.0985.
4.1.12. (2Z)-2-[Hydroxy(2-naphthyl)methyl]-1-(2-naph-
thyl)-3-phenylprop-2-en-1-one (16). As described for
the synthesis of 3, 1-phenyl-2-(trimethylsilyl)acetylene (1,
0.197 mL, 1.0 mmol) and 2-naphthaldehyde (2i, 234 mg,
1.5 mmol) were treated with the catalyst 5a (40 mg,
0.1 mmol) in CH2Cl2 (2 mL) at ꢁ20 ꢀC for 1 h. Workup as
described previously followed by silica gel column chroma-
tography (hexane/EtOAc, 2:1) gave 16 (265 mg, 85%) as
a white solid: mp 142–143 ꢀC; IR (neat) n 3399, 1618,
1358, 1230, 1128, 1060, 938, 817, 787, 742, 697 cmꢁ1; 1H
NMR (CDCl3, 400 MHz) d 3.27 (d, J¼4.6 Hz, 1H), 5.95
(d, J¼4.6 Hz, 1H), 6.95–7.01 (m, 3H), 7.06 (s, 1H), 7.13
(d, J¼7.8 Hz, 2H), 7.35–7.48 (m, 4H), 7.60–7.69 (m, 4H),
7.75–7.81 (m, 4H), 7.94 (s, 1H), 8.15 (s, 1H); 13C NMR
(CDCl3, 100 MHz) d 76.8, 124.1, 124.2, 125.3, 125.7,
125.8, 126.1, 127.2, 127.3, 127.75, 127.79, 127.81, 128.0,
128.1, 128.6, 129.3, 131.8, 131.9, 132.3, 132.7, 132.9,
133.1, 134.6, 135.2, 138.0, 141.6, 199.7; Anal. calcd for
C30H22O2: C, 86.93; H, 5.35. Found: C, 86.51; H, 5.36.
4.1.15. (Z)-2,3-Dihydro-3-hydroxy-2-(phenylmethylene)-
1H-inden-1-one (Z-18). A solution of E-18 (210 mg,
0.89 mmol) in acetonitrile (25 mL) was exposed to UV
(365 nm) light for 10 h at rt. After removal of the solvent in
vacuo, the residue was purified by silica gel column chroma-
tography (hexane/ether, 2:1) to give Z-18 (42 mg, 20%) as
yellow crystals: mp 77 ꢀC; IR (neat) n 3356, 2973, 1686,
1613, 1385, 1240, 1185, 1072, 1019, 970, 739, 690 cmꢁ1
;
1H NMR (CDCl3, 400 MHz) d 2.27 (d, J¼10.0 Hz, 1H),
5.60 (d, J¼9.5 Hz, 1H), 7.30 (d, J¼1.2 Hz, 1H), 7.41–7.44
(m, 3H), 7.48–7.51 (m, 1H), 7.68 (dt, J¼1.0, 7.6 Hz, 1H),
7.74 (dd, J¼1.0, 7.6 Hz, 1H), 7.81 (d, J¼7.8 Hz, 1H),
8.13–8.15 (m, 2H); 13C NMR (CDCl3, 100 MHz) d 72.0,
123.4, 125.3, 127.9, 129.4, 130.1, 131.1, 133.8, 134.7,
138.6, 138.7, 141.4, 149.6, 189.7; Anal. calcd for
C26H26O6: C, 71.34; H, 5.12. Found: C, 71.16; H, 5.16.
4.1.13. (2Z)-1-(2-Furyl)-2-[2-furyl(hydroxy)methyl]-3-
phenylprop-2-en-1-one (17). As described for the synthesis
of 3, 1-phenyl-2-(trimethylsilyl)acetylene (1, 0.197 mL,
1.0 mmol) and 2-furaldehyde (2j, 0.124 mL, 1.5 mmol) were
treated with the catalyst 5a (40 mg, 0.1 mmol) in CH2Cl2
(2 mL) at ꢁ20 ꢀC for 1 h. Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 2:1) gave 17 (119 mg, 54%) as a pale yellow oil:
IR (neat) n 3410, 1627, 1561, 1460, 1269, 1163, 1012,
4.1.16. 3-(4-Fluorophenyl)-1-phenylprop-2-yn-1-ol (20).
To a solution of 4-fluorophenylacetylene (360 mg, 3 mmol)
in THF (5 mL) was added n-BuLi in hexane (1.58 M,
2 mL, 3.15 mmol) at ꢁ78 ꢀC under N2. After 5 min, a solu-
tion of benzaldehyde (2a, 318 mg, 3 mmol) in THF
(2.5 mL) was added to the mixture, and then the mixture
was immediately warmed to rt. After 21 h, the reaction mix-
ture was quenched with water, followed by addition of
EtOAc. The separated organic layer was washed with brine
and dried over MgSO4. After removal of the solvent invacuo,
the residuewas purified by silica gel column chromatography
(hexane/EtOAc, 5:1) to give 20 (603 mg, 89%) as a colorless
oil: IR (neat) n 3323, 3064, 1601, 1505, 1219, 1155, 1014,
1
853, 754, 696 cmꢁ1; H NMR (CDCl3, 400 MHz) d 3.14
(d, J¼6.6 Hz, 1H), 5.70 (d, J¼6.3 Hz, 1H), 6.22 (dd,
J¼1.4, 3.4 Hz, 1H), 6.28 (dd, J¼2.0, 3.2 Hz, 1H), 6.34 (d,
J¼2.9 Hz, 1H), 6.80 (d, J¼3.4 Hz, 1H), 7.12 (s, 1H),
7.14–7.19 (m, 5H), 7.35 (dd, J¼1.5, 15.1 Hz, 2H); 13C
NMR (CDCl3, 100 MHz) d 70.7, 107.6, 110.2, 111.9,
120.7, 127.96, 128.00, 128.5, 133.7, 134.7, 138.3, 142.1,
146.9, 151.5, 153.0, 185.5; Anal. calcd for C18H14O4: C,
73.46; H, 4.79. Found: C, 73.45; H, 4.89.
1
960, 833, 747, 697 cmꢁ1; H NMR (CDCl3, 400 MHz) d
2.23–2.26 (m, 1H), 5.68 (d, J¼6.1 Hz, 1H), 7.01 (t,
J¼8.5 Hz, 2H), 7.35–7.46 (m, 5H), 7.50 (d, J¼6.8 Hz, 2H);
13C NMR (CDCl3, 100 MHz) d 64.9, 85.4, 88.2, 115.3 (d,
J¼22.4 Hz), 118.2 (d, J¼4.4 Hz), 126.4, 128.2, 128.4, 133.3
(d, J¼8.3 Hz), 140.2, 162.3 (d, J¼248.4 Hz); Anal. calcd for
C26H26O6: C, 79.63; H, 4.90. Found: C, 79.71; H, 4.91.
4.1.14. (E)-2,3-Dihydro-3-hydroxy-2-(phenylmethylene)-
1H-inden-1-one (E-18). As described for the synthesis
of 3, 1-phenyl-2-(trimethylsilyl)acetylene (1, 0.197 mL,
1.0 mmol) and 2-phthalaldehyde (2m, 101 mg, 1.5 mmol)
were treated with the catalyst 5a (40 mg, 0.1 mmol) in
CH2Cl2 (2 mL) at ꢁ20 ꢀC for 1 h. Workup as described
previously followed by silica gel column chromatography
(hexane/EtOAc, 3:1) gave E-18 (86 mg, 49%) as a pale
yellow solid and 19 (68 mg, 27%) as a pale yellow oil.
4.1.17. A mixture of (2Z)-1-(4-fluorophenyl)-2-[(4-fluoro-
phenyl)(hydroxy)methyl]-3-phenylprop-2-en-1-one (10)
and (2Z)-1,3-bis(4-fluorophenyl)-2-[hydroxy(phenyl)-
methyl]prop-2-en-1-one (21). A mixture of 20 (136 mg,
Compound E-18: mp 188 ꢀC; IR (neat) n 3380, 1682, 1617,
0.6 mmol),
4-fluorobenzaldehyde
(2d,
0.054 mL,
1
1422, 1335, 1262, 1024, 955, 751, 688 cmꢁ1; H NMR
0.5 mmol), and VO(OSiPh3)3 (22 mg, 0.025 mmol) in 1,2-
dichloroethane (0.3 mL) was stirred at 80 ꢀC for 20 h under
Ar. After removal of the solvent in vacuo, the residue was pu-
rified by silica gel column chromatography (hexane/EtOAc,
(CDCl3, 400 MHz) d 2.21 (d, J¼9.5 Hz, 1H), 5.96 (d,
J¼9.5 Hz, 1H), 7.42–7.54 (m, 4H), 7.70–7.74 (m, 2H),
7.81 (d, J¼7.4 Hz, 1H), 7.85–7.89 (m, 1H), 7.94–7.96 (m,

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K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
5:1) to give a mixture of 10 and 21 (3:2, 32 mg, 18%) as a col-
orless oil: IR (neat) n 3414, 2975, 1652, 1594, 1506, 1227,
used for the next step without further purification. To a solu-
tion of 4 (2.50 g, 12 mmol) and triethylamine (2.17 mL,
15.6 mmol) in THF (50 mL) was added chlorotrimethyl-
silane (1.83 mL, 14.4 mmol) at 0 ꢀC, and then the mixture
was immediately warmed to rt. After 30 min, the insoluble
ammonium salt was filtered off and washed with hexane. Af-
ter removal of the solvent of the filtrate in vacuo, the residue
was passed through a short silica gel column chromato-
graphy (hexane/EtOAc, 10:1) to give 24 (3.29 g, 98%) as
a pale yellow oil.
1
1152, 1013, 956, 835, 756, 697 cmꢁ1; H NMR (CDCl3,
400 MHz) d 3.04 (d, J¼4.5 Hz, 0.4H), 3.16 (d, J¼4.5 Hz,
0.6H), 5.71 (d, J¼4.2 Hz, 0.6H), 5.72 (d, J¼3.7 Hz, 0.4H),
6.74–6.85 (m, 2.8H), 6.91 (s, 0.4H), 6.96–7.09 (m, 5.4H),
7.21–7.25 (m, 0.4H), 7.28–7.32 (m, 1H), 7.38–7.42 (m,
1H), 7.62–7.66 (m, 1H); 13C NMR (CDCl3, 100 MHz)
d 76.0, 115.0 (d, J¼17.4 Hz), 115.2 (d, J¼17.4 Hz), 126.1,
127.7, 128.2, 130.2, 130.3 (d, J¼8.3 Hz), 130.6 (d,
J¼3.3 Hz), 140.4, 141.5, 162.0 (d, J¼247.2 Hz), 165.3 (d,
J¼254.6 Hz), 198.07; HRMS (EI) calcd for C20H16O2S
(M+) 350.1118, Found 350.1107. The ratio of 10 and 21
was determined by 1H NMR analysis.
Compound 4: 1H NMR (CDCl3, 400 MHz) d 2.29 (m, 1H),
5.69 (d, J¼6.3 Hz, 1H), 7.31–7.38 (m, 4H), 7.39–7.44 (m,
2H), 7.47–7.49 (m, 2H), 7.61–7.64 (m, 2H).
4.1.18. 1-(4-Fluorophenyl)-3-phenylprop-2-yn-1-ol
(22).19b To a solution of phenylacetylene (27, 0.33 mL,
3 mmol) in THF (5 mL) was added n-BuLi in hexane
(1.58 M, 2 mL, 3.15 mmol) at ꢁ78 ꢀC under N2. After
5 min, to the mixture was added a solution of 4-fluorobenz-
aldehyde (2d, 0.32 mL, 3 mmol) in THF (2.5 mL), and then
the mixture was immediately warmed to rt. After 21 h, the
reaction mixture was quenched with water, followed by ad-
dition of EtOAc. The separated organic layer was washed
with brine and dried over MgSO4. After removal of the sol-
vent in vacuo, the residue was purified by silica gel column
chromatography (hexane/EtOAc, 5:1) to give 22 (550 mg,
81%) as a colorless oil: 1H NMR (CDCl3, 400 MHz)
d 2.26 (d, J¼6.1 Hz, 1H), 5.68 (d, J¼5.9 Hz, 1H), 7.08 (t,
J¼8.6 Hz, 2H), 7.30–7.35 (m, 3H), 7.46–7.48 (m, 2H),
7.59 (dd, J¼2.1, 5.4 Hz, 2H).
Compound 24: 1H NMR (CDCl3, 400 MHz) d 0.24 (s, 9H),
5.71 (s, 1H), 7.29–7.32 (m, 4H), 7.36–7.39 (m, 2H), 7.43–
7.46 (m, 2H), 7.56–7.57 (m, 2H).
4.1.21. [(1,3-Diphenyl-1,2-propadienyl)oxy]-trimethyl-
silane (25). To a solution of 24 (140 mg, 0.5 mmol) in THF
(1 mL) was added 1 M KOt-Bu in THF (0.05 mL,
0.05 mmol) at ꢁ78 ꢀC under Ar. After 10 min, water and
tert-butyl methyl ether were added, and the separated organic
layer was washed with water and brine and dried over
MgSO4. After removal of the solvent in vacuo, crude 25
(127 mg) was obtained as a yellow oil: IR (neat) n 2958,
1928, 1665, 1597, 1492, 1447, 1251, 1201, 1073, 1019,
867, 747, 689 cmꢁ1; 1H NMR (CDCl3, 400 MHz) d 0.24 (s,
9H), 6.94 (s, 1H), 7.21–7.40 (m, 8H), 7.53 (d, J¼5.9 Hz, 2H).
4.1.22. Preparation of (2Z)-2-[hydroxy(phenyl)methyl]-
1,3-diphenylprop-2-en-1-one (3) from 1 and 2a using cat-
alytic amount of KOt-Bu. To a solution of 1 (0.197 mL,
1.0 mmol) and benzaldehyde (2a, 0.152 mL, 1.5 mmol) in
DMF (2 mL) was added KOt-Bu (11 mg, 0.1 mmol) at
ꢁ20 ꢀC under Ar. After 1 h, 1 N aq HCl (1 mL) and aceto-
nitrile (2 mL) were added, and the yield (33%) of 3 was
assayed by HPLC analysis of the diluted mixture. HPLC
analysis for determination of the yield of 3: YMC Pro C18
(4.6 mm i.d.ꢂ150 mm), UV 254 nm, flow rate 1.0 mL/
min, MeCN/H2O/70% aq HClO4¼600:400:1 (v/v/v), reten-
tion time 3: 7.4 min.
4.1.19. (2Z)-3-(4-Fluorophenyl)-2-[(4-fluorophenyl)-
(hydroxy)methyl]-1-phenylprop-2-en-1-one (23). A mix-
ture of 22 (136 mg, 0.6 mmol), 4-fluorobenzaldehyde
(2d, 0.054 mL, 0.5 mmol), and VO(OSiPh3)3 (22 mg,
0.025 mmol) in 1,2-dichloroethane (0.3 mL) was stirred at
80 ꢀC for 20 h under Ar. After removal of the solvent in va-
cuo, the residue was purified by silica gel column chromato-
graphy (hexane/EtOAc, 5:1) to give 23 (41 mg, 23%) as
a white solid: mp 77–78 ꢀC; IR (neat) n 3429, 3064, 1645,
1601, 1221, 1157, 1013, 954, 829, 729, 686 cmꢁ1 1H
;
NMR (CDCl3, 400 MHz) d 3.13 (d, J¼4.9 Hz, 1H), 5.71
(d, J¼4.4 Hz, 1H), 6.75 (t, J¼8.6 Hz, 2H), 6.93 (s, 1H),
6.97–7.07 (m, 4H), 7.17–7.21 (m, 2H), 7.34–7.43 (m, 3H),
7.61–7.63 (m, 2H); 13C NMR (CDCl3, 100 MHz) d 76.0,
114.9 (d, J¼21.6 Hz), 115.1 (d, J¼20.7 Hz), 127.9 (d, J¼
8.3 Hz), 128.0, 129.0, 130.4 (d, J¼8.3 Hz), 130.58, 130.62,
131.9, 133.1, 135.5, 136.3 (d, J¼3.3 Hz), 141.3, 161.95 (d,
J¼244.7 Hz), 161.96 (d, J¼248.0 Hz), 199.6; Anal. calcd
for C22H16F2O2: C, 75.42; H, 4.60. Found: C, 75.30; H, 4.62.
4.1.23. (2Z)-2-[Hydroxy(phenyl)methyl]-1,3-diphenyl-
prop-2-en-1-one (3) from 24. Typical procedure. Method
A: To a solution of 24 (280 mg, 1.0 mmol) and benzaldehyde
(2a, 0.122 mL, 1.2 mmol) in DMF (2 mL) was added
KOt-Bu (11 mg, 0.1 mmol) at ꢁ20 ꢀC under Ar. After 1 h,
1 N aq HCl (1 mL) and acetonitrile (2 mL) were added, and
the mixture was stirred at rt for a few minutes. Water and
EtOAc were added, and the separated organic layer was
washed with water and brine, and dried over MgSO4. After
removal of the solvent in vacuo, the residue was purified
by silica gel column chromatography (hexane/EtOAc,
10:1) to give 3 (258 mg, 82%) as a white solid.
4.1.20. [(1,3-Diphenyl-2-propynyl)oxy]-trimethylsilane
(24).24 To a solution of phenylacetylene (26, 2.97 mL,
27 mmol) in THF (25 mL) was added n-BuLi in hexane
(1.58 M, 16.5 mL, 26 mmol) at ꢁ78 ꢀC under N2. After
10 min, benzaldehyde (2a, 2.54 mL, 25 mmol) in THF
(10 mL) was added, and then the mixture was immediately
warmed to rt. After 1 h, water was added to the reaction mix-
ture, followed by addition of ether, and the separated organic
layer was washed with brine and dried over MgSO4. After
removal of the solvent in vacuo, 1,3-diphenylprop-2-yn-1-
ol (4, 5.12 g, 98%) was obtained as a pale yellow oil and
Method B: To a solution of 24 (280 mg, 1.0 mmol) in THF
(2 mL) was added 1 M KOt-Bu in THF (0.1 mL,
0.1 mmol) at ꢁ78 ꢀC under Ar. After 10 min, benzaldehyde
(2a, 0.122 mL, 1.2 mmol) was added, and then the mixture
was warmed to 0 ꢀC in 30 min. After 1 h, 1 N aq HCl
(1 mL) and acetonitrile (2 mL) were added, and the mixture

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6275
was stirred at rt for a few minutes. Water and EtOAc were
added, and the separated organic layer was washed with
brine, and dried over MgSO4. After removal of the solvent
in vacuo, the residue was purified by silica gel column chro-
matography (hexane/EtOAc, 10:1) to give 3 (267 mg, 85%)
as a white solid.
Method A followed by silica gel column chromatography
(hexane/EtOAc, 2:1) gave 31 (264 mg, 74%) as a yellow
foam: IR (neat) n 3414, 2885, 1650, 1612, 1520, 1446,
1351, 1227, 1163, 1032, 946, 818, 754, 693 cmꢁ1 1H
;
NMR (CDCl3, 400 MHz) d 2.85 (d, J¼4.2 Hz, 1H), 2.90
(s, 6H), 5.65 (d, J¼2.2 Hz, 1H), 6.67 (dd, J¼2.0, 6.6 Hz,
2H), 6.93 (s, 1H), 7.02–7.10 (m, 5H), 7.15–7.19 (m, 2H),
7.29–7.33 (m, 3H), 7.70–7.73 (m, 2H); 13C NMR (CDCl3,
100 MHz) d 40.5, 76.3, 112.2, 127.4, 127.5, 127.7, 127.8,
128.3, 128.6, 129.1, 130.9, 132.6, 134.9, 136.0, 142.4,
150.0, 199.9; Anal. calcd for C24H23NO2: C, 80.64; H,
6.49; N, 3.92. Found: C, 80.38; H, 6.64; N, 3.71.
4.1.24. (2Z)-2-[(4-Chlorophenyl)(hydroxy)methyl]-
1,3-diphenylprop-2-en-1-one (29). As described for the
synthesis of 3 by Method A, 24 (0.280 mg, 1.0 mmol) and
4-chlorobenzaldehyde (2e, 0.169 mL, 1.2 mmol) were
treated with KOt-Bu (11 mg, 0.1 mmol) in DMF (2 mL).
Workup as described previously followed by silica gel
column chromatography (hexane/EtOAc, 5:1) gave 29
(265 mg, 76%) as a white solid: mp 121 ꢀC; IR (neat) n
3362, 1634, 1592, 1447, 1369, 1237, 1082, 1031, 959,
4.1.27. Methyl 4-[(2Z)-2-benzoyl-1-hydroxy-3-phenyl-
prop-2-en-1-yl]benzoate (32). As described for the synthe-
sis of 3 by Method B, a THF (2 mL) solution of 24 (280 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF (0.1 mL,
0.1 mmol), followed by reaction with a THF (1 mL) solution
of methyl 4-formylbenzoate (2n, 197 mg, 1.2 mmol).
Workup as described previously followed by silica gel col-
umn chromatography (hexane/EtOAc, 20:1) gave 32
(310 mg, 83%) as a white solid: mp 116 ꢀC; IR (neat) n
3359, 2952, 1722, 1634, 1592, 1446, 1278, 1113, 1032,
1
828, 757, 696 cmꢁ1; H NMR (CDCl3, 400 MHz) d 3.30
(m, 1H), 5.70 (d, J¼4.9 Hz, 1H), 6.99 (d, J¼1.2 Hz, 1H),
7.05–7.09 (m, 5H), 7.15–7.19 (m, 2H), 7.27–7.35 (m, 3H),
7.38 (d, J¼8.5 Hz, 2H), 7.63 (dd, J¼1.2, 8.3 Hz, 2H); 13C
NMR (CDCl3, 100 MHz) d 76.1, 127.5, 127.8, 127.9,
128.0, 128.3, 128.7, 129.0, 132.4, 133.0, 133.3, 134.3,
135.6, 139.1, 140.9, 199.7; Anal. calcd for C22H17ClO2: C,
75.75; H, 4.91. Found: C, 75.49; H, 5.03.
958, 872, 758, 694 cmꢁ1 1H NMR (CDCl3, 400 MHz)
;
d 3.18 (d, J¼4.9 Hz, 1H), 5.71 (d, J¼4.6 Hz, 1H), 6.73
(dd, J¼3.9, 4.9 Hz, 1H), 6.93 (s, 1H), 7.10–7.14 (m, 3H),
7.16–7.20 (m, 3H), 7.20–7.25 (m, 1H), 7.28–7.32 (m, 2H),
7.41–7.45 (m, 3H); 13C NMR (CDCl3, 100 MHz) d 51.9,
76.4, 126.1, 127.8, 127.9, 128.0, 128.7, 129.0, 129.2,
129.4, 132.7, 133.0, 134.3, 135.5, 140.7, 145.8, 166.4,
199.6; Anal. calcd for C26H26O6: C, 77.40; H, 5.41. Found:
C, 77.47; H, 5.54.
4.1.25. (2Z)-2-[Hydroxy(4-methoxyphenyl)methyl]-
1,3-diphenylprop-2-en-1-one (30). As described for the
synthesis of 3 by Method A, 24 (0.280 mg, 1.0 mmol) and
4-methoxybenzaldehyde (2c, 0.146 mL, 1.2 mmol) were
treated with KOt-Bu (11 mg, 0.1 mmol) in DMF (2 mL).
Workup as described previously followed by silica gel
column chromatography (hexane/EtOAc, 5:1) gave 30
(246 mg, 72%) as a white solid: mp 92–93 ꢀC; IR (neat) n
3367, 1637, 1592, 1510, 1447, 1368, 1236, 1172, 1033,
4.1.28. (2Z)-2-[Hydroxy(4-nitrophenyl)methyl]-1,3-di-
phenylprop-2-en-1-one (33). As described for the synthesis
of 3 by Method B, a THF (2 mL) solution of 24 (280 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF (0.1 mL,
0.1 mmol), followed by reaction with a THF (1 mL) solution
of 2-nitrobenzaldehyde (2f, 181 mg, 1.2 mmol). Workup as
described previously followed by silica gel column chroma-
tography (hexane/EtOAc, 3:1) gave 33 (241 mg, 67%) as
a pale yellow solid: mp 174 ꢀC; IR (neat) n 3337, 1634,
1
828, 753, 695 cmꢁ1; H NMR (CDCl3, 400 MHz) d 3.01
(d, J¼4.6 Hz, 1H), 3.77 (s, 3H), 5.70 (d, J¼3.9 Hz, 1H),
6.85 (dd, J¼2.2, 6.6 Hz, 2H), 6.96 (d, J¼1.2 Hz, 1H), 7.04–
7.10 (m, 5H), 7.15–7.19 (m, 2H), 7.30–7.38 (m, 3H), 7.67
(dd, J¼1.2, 8.3 Hz, 2H); 13C NMR (CDCl3, 100 MHz) d
55.6, 76.7, 114.1, 128.0, 128.2, 128.2, 128.3, 129.2, 129.6,
131.9, 133.2, 133.3, 135.1, 136.3, 142.3, 159.3, 200.4;
Anal. calcd for C23H20O3: C, 80.21; H, 5.85. Found: C,
80.14; H, 5.98.
1592, 1447, 1351, 1238, 1032, 956, 872, 761, 698 cmꢁ1
;
1H NMR (CDCl3, 400 MHz) d 3.60 (d, J¼5.4 Hz, 1H),
5.80 (d, J¼5.1 Hz, 1H), 7.07–7.09 (m, 6H), 7.13–7.17 (m,
2H), 7.33 (t, J¼7.3 Hz, 1H), 7.59–7.64 (m, 4H), 8.16 (d,
J¼8.6 Hz, 2H); 13C NMR (CDCl3, 100 MHz) d 76.3,
123.3, 126.9, 127.9, 128.0, 128.3, 128.8, 129.0, 133.3,
133.8, 134.0, 135.3, 139.7, 147.1, 148.0, 199.3; Anal. calcd
for C22H17NO4: C, 73.53; H, 4.77; N, 3.90. Found: C,
73.41; H, 4.87; N, 3.88.
4.1.26. (2Z)-2-{[4-(Dimethylamino)phenyl](hydroxy)-
methyl}-1,3-diphenylprop-2-en-1-one (31). As described
for the synthesis of 3 by Method A, 24 (0.280 mg,
1.0 mmol) and 4-dimethylaminobenzaldehyde (2l, 179 mg,
1.2 mmol) were treated with KOt-Bu (11 mg, 0.1 mmol) in
DMF (2 mL). After the reaction mixture was quenched
with 1 N aq HCl (1 mL) and acetonitrile (2 mL), water and
EtOAc were added, and the separated organic layer was
washed with water, saturated aq NaHCO3, and brine. After
the solution was dried over MgSO4 followed by removal
of the solvent in vacuo, the residue was purified by silica
gel column chromatography (hexane/EtOAc, 2:1) that gave
31 (123 mg, 35%) as a yellow foam.
4.1.29. (2Z)-2-[(2,6-Dimethylphenyl)(hydroxy)methyl]-
1,3-diphenylprop-2-en-1-one (34). As described for the
synthesis of 3 by Method A, 24 (0.280 mg, 1.0 mmol) and
2,6-dimethylbenzaldehyde (2o, 161 mg, 1.2 mmol) were
treated with KOt-Bu (11 mg, 0.1 mmol) in DMF (2 mL).
Workup as described previously followed by silica gel col-
umn chromatography (hexane/EtOAc, 2:1) gave 34
(234 mg, 68%) as a white solid: mp 97 ꢀC; IR (neat) n
3443, 2966, 1639, 1594, 1447, 1378, 1232, 1172, 1046,
As described for the synthesis of 3 by Method B, 24
(280 mg, 1.0 mmol) in THF (2 mL) was treated with 1 M
KOt-Bu in THF (0.1 mL, 0.1 mmol), followed by reaction
with a THF (0.5 mL) solution of 4-dimethylaminobenz-
aldehyde (2l, 179 mg, 1.2 mmol). Workup as described in
1
950, 756, 694 cmꢁ1; H NMR (CDCl3, 400 MHz) d 2.49
(s, 6H), 2.52 (d, J¼4.4 Hz, 1H), 6.32 (dd, J¼2.2, 4.4 Hz,

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K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
1H), 6.54 (d, J¼2.2 Hz, 1H), 7.02–7.13 (m, 8H), 7.24–7.28
(m, 2H), 7.37–7.41 (m, 1H), 7.83 (dd, J¼1.3, 8.6 Hz, 2H);
13C NMR (CDCl3, 100 MHz) d 20.9, 72.5, 127.6, 127.6,
127.8, 128.0, 128.5, 128.9, 129.0, 129.9, 132.8, 134.7,
135.7, 136.1, 137.0, 140.6, 199.8; Anal. calcd for
C24H22O2: C, 84.18; H, 6.48. Found: C, 84.03; H, 6.57.
d 5.16 (d, J¼5.6 Hz, 1H), 5.67 (d, J¼5.1 Hz, 1H), 7.06–
7.08 (m, 3H), 7.11–7.14 (m, 3H), 7.17–7.21 (m, 3H), 7.33
(t, J¼7.5 Hz, 1H), 7.41 (d, J¼7.8 Hz, 2H), 7.63 (dt, J¼1.7,
7.6 Hz, 1H), 7.74–7.76 (m, 2H), 8.52 (d, J¼4.6 Hz, 1H);
13C NMR (CDCl3, 100 MHz) d 76.1, 121.1, 122.4, 127.8,
128.7, 129.1, 132.1, 132.7, 134.5, 136.1, 136.4, 141.1,
147.6, 158.4, 199.1; HRMS (EI) calcd for C21H17NO2 (M+)
315.1259, Found 315.1273.
4.1.30. (2Z)-2-[2-Furyl(hydroxy)methyl]-1,3-diphenyl-
prop-2-en-1-one (35). As described for the synthesis of 3
by Method A, 24 (0.280 mg, 1.0 mmol) and 2-furaldehyde
(2j, 0.099 mL, 1.2 mmol) were treated with KOt-Bu
(11 mg, 0.1 mmol) in DMF (2 mL). Workup as described
previously followed by silica gel column chromatography
(hexane/EtOAc, 3:1) gave 35 (288 mg, 95%) as a pale yel-
low oil: IR (neat) n 3414, 3059, 1643, 1594, 1447, 1365,
4.1.33. (2Z,4E)-2-Benzylidene-3-hydroxy-1,5-diphenyl-
pent-4-en-1-one (38). As described for the synthesis of 3
by Method A, 24 (0.280 mg, 1.0 mmol) and cinnamaldehyde
(2r, 0.151 mL, 1.2 mmol) were treated with KOt-Bu (11 mg,
0.1 mmol) in DMF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 2:1) gave 38 (176 mg, 52%) as a yellow solid.
1
1230, 1072, 1009, 954, 723, 688 cmꢁ1; H NMR (CDCl3,
400 MHz) d 3.41 (d, J¼6.6 Hz, 1H), 5.70 (d, J¼6.6 Hz,
1H), 6.25 (dd, J¼1.8, 3.4 Hz, 1H), 6.32 (d, J¼3.4 Hz, 1H),
7.06–7.08 (m, 3H), 7.10–7.14 (m, 3H), 7.17–7.21 (m, 2H),
7.30 (dd, J¼0.8, 1.7 Hz, 1H), 7.33 (t, J¼7.4 Hz, 1H),
7.71–7.73 (m, 2H); 13C NMR (CDCl3, 100 MHz) d 71.2,
107.4, 110.1, 127.8, 127.8, 127.9, 128.7, 129.1, 132.9,
133.0, 134.4, 135.5, 138.6, 142.0, 153.2, 199.4; HRMS
(EI) calcd for C20H16O3 (M+) 304.1099, Found 304.1092.
As described for the synthesis of 3 by Method B, a THF
(2 mL) solution of 24 (280 mg, 1.0 mmol) was treated with
1 M KOt-Bu in THF (0.1 mL, 0.1 mmol), followed by
reaction with cinnamaldehyde (2r, 0.151 mL, 1.2 mmol).
Workup as described previously followed by silica gel
column chromatography (hexane/EtOAc, 5:1) gave 38
(225 mg, 66%) as a yellow solid: mp 118 ꢀC; IR (neat) n
3343, 3027, 1643, 1592, 1447, 1362, 1237, 1088, 1022,
1
4.1.31. (2Z)-2-[Hydroxy(2-thienyl)methyl]-1,3-diphenyl-
prop-2-en-1-one (36). As described for the synthesis of 3
by Method A, 24 (0.280 mg, 1.0 mmol) and 2-thiophenecarb-
oxaldehyde (2p, 0.112 mL, 1.2 mmol) were treated with
KOt-Bu (11 mg, 0.1 mmol) in DMF (2 mL). Workup as de-
scribed previously followed by silica gel column chromato-
graphy (hexane/EtOAc, 5:1) gave 36 (264 mg, 83%) as
a colorless oil: IR (neat) n 3413, 3058, 1646, 1594, 1447,
968, 739, 693 cmꢁ1; H NMR (CDCl3, 400 MHz) d 2.81
(m, 1H), 5.27 (t, J¼5.7 Hz, 1H), 6.34 (dd, J¼6.6, 15.9 Hz,
1H), 6.72 (d, J¼15.9 Hz, 1H), 7.07–7.14 (m, 6H), 7.20–
7.33 (m, 7H), 7.38 (t, J¼7.3 Hz, 1H), 7.83 (d, J¼3.6 Hz,
2H); 13C NMR (CDCl3, 100 MHz) d 75.6, 126.3, 127.5,
127.8, 128.0, 128.2, 128.5, 128.6, 129.2, 131.6, 133.0,
134.6, 135.9, 136.0, 140.6, 199.7; Anal. calcd for
C24H20O2: C, 84.68; H, 5.92. Found: C, 84.35; H, 5.99.
1364, 1229, 1022, 946, 853, 757, 687 cmꢁ1 1H NMR
;
(CDCl3, 400 MHz) d 3.52 (d, J¼4.4 Hz, 1H), 5.97 (d,
J¼2.2 Hz, 1H), 6.90 (dd, J¼3.6, 5.1 Hz, 1H), 7.02–7.11
(m, 6H), 7.15–7.22 (m, 4H), 7.30–7.34 (m, 1H), 7.70 (d,
J¼7.8, Hz, 2H); 13C NMR (CDCl3, 100 MHz) d 73.5,
125.3, 125.6, 127.1, 128.4, 128.5, 128.6, 129.5, 129.4,
133.3, 133.6, 135.1, 136.5, 141.2, 145.6, 200.5; HRMS
(EI) calcd for C20H16O2S (M+) 320.0871, Found 320.0877.
4.1.34. (2Z)-2-Benzylidene-3-hydroxy-4,4-dimethyl-1-
phenylpentan-1-one (39). As described for the synthesis
of 3 by Method A, 24 (0.280 mg, 1.0 mmol) and pivalalde-
hyde (2s, 0.130 mL, 1.5 mmol) were treated with KOt-Bu
(11 mg, 0.1 mmol) in DMF (2 mL). Workup as described
previously followed by silica gel column chromatography
(hexane/EtOAc, 10:1) gave 39 (198 mg, 67%) as a pale yel-
low solid: mp 96 ꢀC; IR (neat) n 3468, 2955, 1637, 1595,
1
4.1.32. (2Z)-2-[Hydroxy(pyridin-2-yl)methyl]-1,3-diphe-
nylprop-2-en-1-one (37). As described for the synthesis of 3
by Method A, 24 (0.140 mg, 0.5 mmol) and 2-pyridinecarb-
oxaldehyde (2q, 0.057 mL, 0.6 mmol) were treated with
KOt-Bu (6 mg, 0.05 mmol) in DMF (1 mL). After the reac-
tion mixture was quenched with 1 N aq HCl (1 mL) and ace-
tonitrile (2 mL), water and EtOAc were added, and the
separated organic layer was washed with water, saturated
aq NaHCO3, and brine. After the solution was dried over
MgSO4 followed by removal of the solvent in vacuo, the res-
idue was purified by silica gel column chromatography (hex-
ane/EtOAc, 2:1) that gave 37 (55 mg, 35%) as a yellow oil.
1445, 1350, 1235, 1178, 1077, 954, 756, 698 cmꢁ1; H
NMR (CDCl3, 400 MHz) d 0.96 (s, 9H), 3.36 (d,
J¼5.9 Hz, 1H), 4.37 (d, J¼5.8 Hz, 1H), 7.03–7.07 (m,
5H), 7.17 (s, 1H), 7.21 (t, J¼7.8 Hz, 2H), 7.35 (t,
J¼7.3 Hz, 1H), 7.77–7.80 (m, 2H); 13C NMR (CDCl3,
100 MHz) d 26.3, 36.8, 84.4, 127.7, 127.9, 128.3, 129.5,
132.7, 135.1, 135.4, 136.2, 139.7, 199.6; Anal. calcd for
C20H22O2: C, 81.60; H, 7.53. Found: C, 81.59; H, 7.59.
4.1.35. (2Z)-2-Benzylidene-3-hydroxy-4-methyl-1-phe-
nylpentan-1-one (40). As described for the synthesis of
3 by Method B, a THF (2 mL) solution of 24 (280 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF (0.1 mL,
0.1 mmol), followed by reaction with isobutyraldehyde (2t,
0.137 mL, 1.5 mmol). Workup as described previously fol-
lowed by silica gel column chromatography (hexane/EtOAc,
5:1) gave 40 (192 mg, 69%) as a pale yellow solid: mp
104 ꢀC; IR (neat) n 3495, 2960, 1645, 1593, 1448, 1371,
As described for the synthesis of 3 by Method B, THF (2 mL)
solutionof 24(280 mg, 1.0 mmol)was treated with 1 MKOt-
Bu in THF (0.1 mL, 0.1 mmol), followed by reaction with 2-
pyridinecarboxaldehyde (2q, 0.114 mL, 1.2 mmol). Workup
as described in Method A followed by silica gel column chro-
matography (hexane/EtOAc, 2:1) gave 37 (171 mg, 54%) as
a yellow oil: IR (neat) n 3057, 1651, 1593, 1447, 1375, 1229,
1
1234, 1031, 912, 858, 735, 694 cmꢁ1; H NMR (CDCl3,
400 MHz) d 1.01 (d, J¼6.6 Hz, 3H), 1.03 (d, J¼6.6 Hz,
1
1043, 956, 752, 688 cmꢁ1; H NMR (CDCl3, 400 MHz)
3H), 1.90 (dq, J¼6.6, 6.8 Hz, 1H), 2.51 (d, J¼6.1 Hz, 1H),

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6277
4.24 (m, 1H), 7.04 (s, 1H), 7.06–7.13 (m, 5H), 7.23–7.27 (m,
2H), 7.39 (t, J¼7.3 Hz, 1H), 7.82–7.84 (m, 2H); 13C NMR
(CDCl3, 100 MHz) d 17.4, 19.8, 32.5, 81.1, 127.6, 127.8,
128.0, 128.6, 129.2, 132.3, 132.9, 134.9, 135.7, 141.1,
199.7; Anal. calcd for C19H20O2: C, 81.40; H, 7.19. Found:
C, 81.09; H, 7.21.
of 3 by Method B, a THF (2 mL) solution of 24 (280 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF (0.1 mL,
0.1 mmol), followed by reaction with methyl benzoyl-
formate (47, 0.171 mL, 1.2 mmol). Workup as described
previously followed by silica gel column chromatography
(hexane/EtOAc, 20:1) gave 50 (265 mg, 60%) as a colorless
oil: IR (neat) n 2952, 1749, 1660, 1594, 1448, 1247, 1137,
1
4.1.36. (2Z)-2-Benzylidene-3-hydroxy-1-phenylheptan-1-
one (41). As described for the synthesis of 3 by Method B,
a THF (2 mL) solution of 24 (280 mg, 1.0 mmol) was treated
with 1 M KOt-Bu in THF (0.1 mL, 0.1 mmol), followed by
reaction with valeraldehyde (2u, 0.160 mL, 1.5 mmol).
Workup as described previously followed by silica gel
column chromatography (hexane/EtOAc, 5:1) gave 41
(198 mg, 67%) as a pale yellow oil: IR (neat) n 3413, 2956,
1650, 1595, 1447, 1377, 1229, 1070, 1001, 950, 720,
1011, 837, 757, 694 cmꢁ1; H NMR (CDCl3, 400 MHz)
d ꢁ0.12 (s, 9H), 3.88 (s, 3H), 6.48 (s, 1H), 7.01–7.03 (m,
5H), 7.23–7.27 (m, 3H), 7.35–7.45 (m, 4H), 7.57–7.60 (m,
2H), 7.80–7.82 (m, 2H); 13C NMR (CDCl3, 100 MHz)
d 1.6, 52.5, 85.4, 127.3, 127.66, 127.68, 127.9, 128.1,
128.7, 128.8, 132.3, 132.5, 134.5, 137.1, 140.9, 143.3,
171.9, 198.5; Anal. calcd for C26H26O6: C, 72.94; H, 6.35.
Found: C, 72.73; H, 6.40.
693 cmꢁ1
;
1H NMR (CDCl3, 400 MHz) d 0.89 (t, J¼
4.1.40. [[1-(4-Chlorophenyl)-3-phenyl-2-propynyl]oxy]-
trimethylsilane (52). As described for the synthesis of 24,
a THF (25 mL) solution of phenylacetylene (26, 2.97 mL,
27 mmol) was treated with n-BuLi in hexane (1.58 M,
16.5 mL, 26 mmol), followed by reaction with a THF
(10 mL) solution of 4-chlorobenzaldehyde (2e, 3.51 g,
25 mmol). Workup as described previously gave 1-(4-chloro-
phenyl)-3-phenylprop-2-yn-1-ol (6.28 g, quant.) as a pale
yellow oil and used for the next step without further purifi-
cation. A THF (50 mL) solution of 1-(4-chlorophenyl)-3-
phenylprop-2-yn-1-ol (2.91 g, 12 mmol) and triethylamine
(2.17 mL, 15.6 mmol) was treated with chlorotrimethysilane
(1.83 mL, 14.4 mmol). Workup as described previously gave
52 (3.49 g, 92%) as a pale yellow oil.
7.3 Hz, 3H), 1.27–1.58 (m, 4H), 1.60–1.72 (m, 2H), 2.45
(d, J¼5.9 Hz, 1H), 4.52 (dd, J¼5.4, 13.2 Hz, 1H), 7.02 (s,
1H), 7.06–7.12 (m, 5H), 7.26 (t, J¼7.8 Hz, 2H), 7.40 (t,
J¼7.3 Hz, 1H), 7.81–7.83 (m, 2H); 13C NMR (CDCl3,
100 MHz) d 14.0, 22.4, 28.0, 36.0, 75.3, 127.6, 127.8,
128.1, 128.6, 129.1, 130.7, 133.0, 134.8, 135.9, 142.2,
200.0; HRMS (EI) calcd for C20H22O2 (M+)294.1620, Found
294.1602.
4.1.37. (2Z)-2-Benzylidene-4,4,4-trifluoro-3-trimethyl-
siloxy-1,3-diphenylbutan-1-one (48). As described for the
synthesis of 3 by Method B, a THF (2 mL) solution of 24
(280 mg, 1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mL, 0.1 mmol), followed by reaction with trifluoroace-
tophenone (45, 0.225 mL, 1.5 mmol). Workup as described
previously followed by silica gel column chromatography
(hexane/EtOAc, 20:1) gave 48 (356 mg, 78%) as a white
solid: mp 70 ꢀC; IR (neat) n 2957, 1656, 1593, 1449, 1254,
1201, 1153, 983, 894, 841, 757, 696 cmꢁ1; 1H NMR (CDCl3,
400 MHz) d ꢁ0.12 (s, 9H), 7.08–7.10 (m, 3H), 7.12 (s, 1H),
7.14–7.16 (m, 2H), 7.23–7.27 (m, 2H), 7.36–7.41 (m, 4H),
7.61–7.63 (m, 2H), 7.78–7.80 (m, 2H); 13C NMR (CDCl3,
100 MHz) d 1.1, 127.4 (q, J¼2.5 Hz), 127.75, 127.81,
127.9, 128.0, 128.3, 128.7, 129.0, 132.5, 133.51, 133.53,
134.2, 136.4, 138.5, 139.1, 196.2; Anal. calcd for
C26H25F3O2Si: C, 68.70; H, 5.54. Found: C, 69.03; H, 5.59.
1-(4-Chlorophenyl)-3-phenylprop-2-yn-1-ol:19a 1H NMR
(CDCl3, 400 MHz) d 2.28 (dd, J¼0.5, 6.1 Hz, 1H), 5.67 (d,
J¼6.1 Hz, 1H), 7.32–7.39 (m, 3H), 7.38 (dd, J¼2.0,
6.6 Hz, 2H), 7.46–7.48 (m, 2H), 7.56 (dd, J¼2.2, 6.1 Hz, 2H).
Compound 52: IR (neat) n 2957, 1489, 1250, 1068, 979, 873,
837, 752, 689 cmꢁ1; 1H NMR (CDCl3, 400 MHz) d 0.25 (s,
9H), 5.67 (s, 1H), 7.30–7.36 (m, 5H), 7.42–7.45 (m, 2H),
7.49 (dd, J¼1.7, 7.2 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
d 0.3, 64.3, 86.0, 89.0, 122.3, 127.5, 128.0, 128.2, 128.2,
131.3, 133.3, 139.7; HRMS (EI) calcd for C18H19ClOSi
(M+) 314.0894, Found 314.0877.
4.1.38. Methyl (3Z)-3-benzoyl-2-hydroxy-2-methyl-4-
phenylbut-3-enoate (49). As described for the synthesis
of 3 by Method B, a THF (2 mL) solution of 24 (280 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF (0.1 mL,
0.1 mmol), followed by reaction with methyl pyruvate (46,
0.109 mL, 1.2 mmol). Workup as described previously fol-
lowed by silica gel column chromatography (hexane/EtOAc,
20:1) gave 49 (35 mg, 11%) as a colorless oil: IR (neat) n
3484, 2952, 1732, 1655, 1595, 1448, 1362, 1253, 1133,
4.1.41. [[1-(4-Methoxyphenyl)-3-phenyl-2-propynyl]-
oxy]-trimethylsilane (53). As described for the synthesis
of 24, a THF (25 mL) solution of phenylacetylene (26,
2.97 mL, 27 mmol) was treated with n-BuLi in hexane
(1.58 M, 16.5 mL, 26 mmol), followed by reaction with
a THF (10 mL) solution of 4-methoxybenzaldehyde (2c,
3.04 mL, 25 mmol). Workup as described previously gave
1-(4-methoxyphenyl)-3-phenylprop-2-yn-1-ol (13, 5.98 g,
quant.) as a pale yellow oil and used for the next step without
further purification. A THF (50 mL) solution of 13 (2.91 g,
12 mmol) and triethylamine (2.17 mL, 15.6 mmol) was
treated with chlorotrimethylsilane (1.83 mL, 14.4 mmol).
Workup as described previously gave 53 (3.49 g, 92%) as
a pale yellow oil.
1
947, 758, 694 cmꢁ1; H NMR (CDCl3, 400 MHz) d 1.79
(s, 3H), 3.68 (s, 3H), 3.90 (s, 1H), 7.06–7.09 (m, 3H),
7.10–7.14 (m, 2H), 7.21–7.26 (m, 3H), 7.34–7.38 (m, 1H),
7.77 (d, J¼7.8 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
d 24.8, 53.0, 76.1, 127.8, 127.90, 127.92, 128.7, 128.9,
130.7, 132.8, 134.3, 136.0, 140.7, 174.8, 198.7; Anal. calcd
for C26H26O6: C, 73.53; H, 5.85. Found: C, 73.35; H, 5.86.
Compound 13: 1H NMR (CDCl3, 400 MHz) d 2.18–2.31 (m,
1H), 3.81 (s, 3H), 5.65 (d, J¼6.1 Hz, 1H), 6.93 (dd, J¼2.1,
6.8 Hz, 2H), 7.30–7.34 (m, 3H), 7.46–7.48 (m, 2H), 7.55
(dd, J¼2.1, 6.6 Hz, 2H).
4.1.39. Methyl (3Z)-3-benzoyl-2-trimethylsiloxy-2,4-di-
phenylbut-3-enoate (50). As described for the synthesis

6278
K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
Compound 53: IR (neat) n 2956, 1509, 1246, 1171, 1034,
979, 873, 836, 753, 689 cmꢁ1 1H NMR (CDCl3,
61.0, 85.4, 88.6, 122.2, 124.5, 125.2, 126.2, 128.0, 128.2,
131.3, 145.4; HRMS (EI) calcd for C16H18OSSi (M+)
286.0848, Found 286.0832.
;
400 MHz) d 0.23 (s, 9H), 3.81 (s, 3H), 5.66 (s, 1H), 6.90
(dd, J¼2.1, 6.8 Hz, 2H), 7.29–7.32 (m, 3H), 7.43–7.46 (m,
2H), 6.90 (dd, J¼2.0, 6.8 Hz, 2H); 13C NMR (CDCl3,
100 MHz) d 0.4, 55.2, 64.7, 85.6, 89.7, 113.5, 122.6,
127.6, 127.9, 128.0, 131.3, 133.4, 158.9; HRMS (EI) calcd
for C19H22O2Si (M+) 310.1389, Found 310.1401.
4.1.44. [[3-Phenyl-1-(pyridin-2-yl)-2-propynyl]oxy]-tri-
methylsilane (56). To phenylacetylene (26, 0.88 mL,
8 mmol) in THF (8 mL) was added n-BuLi in hexane
(1.6 M, 5.0 mL, 8 mmol) at ꢁ78 ꢀC under N2. After
10 min, the mixture was warmed to 0 ꢀC and added drop-
wise to a THF (10 mL) solution of 2-pyridinecarboxalde-
hyde (2q, 0.95 mL, 10 mmol) at ꢁ8 ꢀC for 30 min. After
20 min, the reaction mixture was poured into water,
followed by addition of tert-butyl methyl ether, and the sep-
arated organic layer was washed with water and brine, and
then dried over MgSO4. After removal of the solvent in
vacuo, the residue was purified by silica gel column chroma-
tography (hexane/EtOAc, 2:1) to give 3-phenyl-1-pyridin-2-
ylprop-2-yn-1-ol (1.09 g, 52%) as a yellow oil. As described
for the synthesis of 24, a THF (17 mL) solution of 3-phenyl-
1-pyridin-2-ylprop-2-yn-1-ol (897 mg, 4.2 mmol) and
triethylamine (0.76 mL, 5.46 mmol) was treated with
chlorotrimethylsilane (0.64 mL, 5.04 mmol). Workup as de-
scribed previously followed by short silica gel column chro-
matography (hexane/EtOAc, 4:1) gave 56 (1.03 g, 87%) as a
yellow oil.
4.1.42. [[1-(2-Furyl)-3-phenyl-2-propynyl]oxy]-tri-
methylsilane (54). As described for the synthesis of 24,
a THF (13 mL) solution of phenylacetylene (26, 1.48 mL,
13.5 mmol) was treated with n-BuLi in hexane (1.6 M,
8.1 mL, 13 mmol), followed by reaction with a THF (5 mL)
solution of 2-furaldehyde (2j, 1.03 mL, 12.5 mmol). Workup
as described previously gave 1-(2-furyl)-3-phenylprop-2-yn-
1-ol (2.59 g, quant.) as a pale yellow oil and used for the next
step without further purification. ATHF (25 mL) solution of
1-(2-furyl)-3-phenylprop-2-yn-1-ol (1.19 g, 6 mmol) and
triethylamine (1.09 mL, 7.8 mmol) was treated with chloro-
trimethylsilane (0.91 mL, 7.2 mmol). Workup as described
previously gave 54 (1.48 g, 91%) as a pale yellow oil.
1-(2-Furyl)-3-phenylprop-2-yn-1-ol:25 1H NMR (CDCl3,
400 MHz) d 2.39–2.43 (m, 1H), 5.69 (d, J¼6.5 Hz, 1H),
6.38 (dd, J¼1.7, 3.2 Hz, 1H), 6.53 (d, J¼3.4 Hz, 1H),
7.30–7.35 (m, 3H), 7.45 (dd, J¼0.9, 1.7 Hz, 1H), 7.47–
7.50 (m, 2H).
3-Phenyl-1-pyridin-2-ylprop-2-yn-1-ol: IR (neat) n 3056,
1
1670, 1594, 1489, 1315, 1033, 969, 751, 689 cmꢁ1; H
NMR (CDCl3, 400 MHz) d 4.85 (br, 1H), 5.73 (s, 1H),
7.26–7.31 (m, 4H), 7.44–7.46 (m, 2H), 7.60 (d, J¼7.8 Hz,
1H), 7.76 (dt, J¼1.6, 7.8 Hz, 1H), 8.58 (d, J¼4.9 Hz, 1H);
13C NMR (CDCl3, 100 MHz) d 63.8, 85.4, 88.1, 120.7,
122.1, 122.9, 127.9, 128.2, 131.5, 137.0, 147.8, 157.5;
HRMS (EI) calcd for C14H11NO (M+) 209.0841, Found
209.0835.
Compound 54: IR (neat) n 2958, 1490, 1251, 1143, 1055,
867, 839, 753, 689 cmꢁ1 1H NMR (CDCl3, 400 MHz)
;
d 0.22 (s, 9H), 5.72 (s, 1H), 6.36 (dd, J¼1.8, 3.4 Hz, 1H),
6.48 (dd, J¼0.7, 3.9 Hz, 1H), 7.31–7.33 (m, 3H), 7.42 (dd,
J¼0.9, 2.0 Hz, 1H), 7.46–7.48 (m, 2H); 13C NMR (CDCl3,
100 MHz) d 0.2, 58.9, 64.7, 85.0, 86.8, 107.3, 110.1,
122.2, 127.9, 128.2, 131.4, 142.3, 152.9; HRMS (EI) calcd
for C16H18O2Si (M+) 270.1076, Found 270.1064.
Compound 56: IR (neat) n 2957, 1588, 1435, 1250, 1102,
1
1068, 838, 749, 689 cmꢁ1; H NMR (CDCl3, 400 MHz)
4.1.43. [[1-(2-Thienyl)-3-phenyl-2-propynyl]oxy]-tri-
methylsilane (55). As described for the synthesis of 24,
a THF (12 mL) solution of phenylacetylene (26, 1.54 mL,
14 mmol) was treated with n-BuLi in hexane (1.6 M, 8.1 mL,
13 mmol), followed by reaction with a THF (6 mL) solution
of 2-thiophenecarboxaldehyde (2p, 1.12 mL, 12 mmol).
Workup as described previously gave 3-phenyl-1-(2-thi-
enyl)prop-2-yn-1-ol (2.60 g, quant.) as a pale yellow oil and
used for the next step without further purification. A THF
(30 mL) solution of 3-phenyl-1-(2-thienyl)prop-2-yn-1-ol
(1.50 g, 7 mmol) and triethylamine (1.27 mL, 9.1 mmol) was
treated with chlorotrimethylsilane (1.07 mL, 8.4 mmol).
Workup as described previously gave 55 (2.01 g, quant.) as
a colorless oil.
d 0.26 (s, 9H), 5.76 (s, 1H), 7.22 (t, J¼6.0 Hz, 1H), 7.27–
7.28 (m, 3H), 7.42–7.44 (m, 2H), 7.69–7.76 (m, 2H), 8.57
(d, J¼4.9 Hz, 1H); 13C NMR (CDCl3, 100 MHz) d 0.3,
66.7, 85.7, 89.0, 120.3, 122.4, 122.5, 127.8, 128.0, 131.4,
136.7, 148.5, 160.1; HRMS (EI) calcd for C17H19NOSi
(M+) 281.1236, Found 281.1225.
4.1.45. (2E)-[[3-Phenyl-1-(phenylethynyl)-2-propenyl]-
oxy]-trimethylsilane (57). To phenylacetylene (26,
1.21 mL, 11 mmol) in THF (5 mL) was added n-BuLi in hex-
ane (1.58 M, 6.3 mL, 10 mmol) at ꢁ78 ꢀC under N2. After
10 min, the mixture was warmed to 0 ꢀC and added to
a THF (10 mL) solution of cinnamaldehyde (2r, 1.26 mL,
10 mmol) at ꢁ78 ꢀC. After 1 h, water was added to the
reaction mixture, followed by addition of EtOAc, and the
separated organic layer was washed with brine and dried
over MgSO4. After removal of the solvent in vacuo, (1E)-
1,5-diphenylpent-1-en-4-yn-3-ol (2.28 g, 97%) was obtained
as a pale yellow oil and used for the next step without further
purification. As described for the synthesis of 24, a THF
(40 mL) solution of (1E)-1,5-diphenylpent-1-en-4-yn-3-ol
(2.28 g, 9.73 mmol) and triethylamine (1.73 mL,
12.7 mmol) was treated with chlorotrimethylsilane
(1.48 mL, 11.7 mmol). Workup as described previously
gave 57 (3.12 g, quant.) as a white solid.
3-Phenyl-1-(2-thienyl)prop-2-yn-1-ol:26 1H NMR (CDCl3,
400 MHz) d 2.49 (br, 1H), 5.89 (d, J¼7.0 Hz, 1H), 7.00
(dd, J¼3.7, 5.1 Hz, 1H), 7.24–7.26 (m, 1H), 7.31–7.35 (m,
4H), 7.47–7.50 (m, 2H).
Compound 55: IR (neat) n 2957, 1490, 1250, 1060, 962, 868,
837, 753, 688 cmꢁ1; 1H NMR (CDCl3, 400 MHz) d 0.25 (s,
9H), 5.92 (s, 1H), 6.96 (dd, J¼3.7, 5.1 Hz, 1H), 7.15–7.17
(m, 1H), 7.27 (dd, J¼3.6, 4.9 Hz, 1H), 7.30–7.32 (m, 3H),
7.45–7.47 (m, 2H); 13C NMR (CDCl3, 100 MHz) d 0.3,

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6279
(1E)-1,5-Diphenylpent-1-en-4-yn-3-ol:27 1H NMR (CDCl3,
400 MHz) d 2.14 (d, J¼6.1 Hz, 1H), 5.29 (dt, J¼1.5,
6.1 Hz, 1H), 6.39 (dd, J¼6.1, 15.8 Hz, 1H), 6.84 (d,
J¼15.9 Hz, 1H), 7.27–7.30 (m, 1H), 7.31–7.36 (m, 5H),
7.42–7.45 (m, 2H), 7.46–7.49 (m, 2H).
(m, 2H), 1.77–1.86 (m, 3H), 4.59 (d, J¼2.6, 12.2 Hz, 1H),
7.29–7.32 (m, 3H), 7.41–7.44 (m, 2H).
Compound 59: 1H NMR (CDCl3, 400 MHz) d 0.21 (s, 9H),
0.93 (t, J¼7.1 Hz, 3H), 1.32–1.50 (m, 4H), 1.74–1.79 (m,
2H), 4.55 (d, J¼6.6 Hz, 1H), 7.28–7.30 (m, 3H), 7.40–
7.42 (m, 2H).
Compound 57: mp 47–48 ꢀC; IR (neat) n 2957, 1489, 1315,
1251, 1099, 1056, 961, 871, 834, 754, 691 cmꢁ1; 1H NMR
(CDCl3, 400 MHz) d 0.27 (s, 9H), 5.29 (dd, J¼1.4, 5.9 Hz,
1H), 6.34 (dd, J¼5.9, 15.6 Hz, 1H), 6.75 (dd, J¼1.0,
15.6 Hz, 1H), 7.25–7.27 (m, 1H), 7.31–7.35 (m, 5H),
7.41–7.47 (m, 4H); 13C NMR (CDCl3, 100 MHz) d 0.3,
63.5, 85.5, 88.2, 122.3, 126.3, 127.3, 127.8, 127.9, 128.0,
128.5, 130.3, 131.1, 135.9; Anal. calcd for C20H22OSi: C,
78.38; H, 7.24. Found: C, 78.27; H, 7.29.
4.1.48. (2Z)-1-(4-Chlorophenyl)-2-[hydroxy(phenyl)-
methyl]-3-phenylprop-2-en-1-one (60). As described for
the synthesis of 3 by Method A, 52 (315 mg, 1.0 mmol)
and benzaldehyde (2a, 0.122 mL, 1.2 mmol) was treated
with KOt-Bu (11 mg, 0.1 mmol) in DMF (2 mL). Workup
as described previously followed by silica gel column chro-
matography (hexane/EtOAc, 3:1) gave 60 (258 mg, 74%) as
a colorless oil: IR (neat) n 3421, 3028, 1651, 1585, 1400,
4.1.46. [(1-Phenyl-2-heptynl)oxy]-trimethylsilane (58).
As described for the synthesis of 24, a THF (15 mL) solution
of 1-hexyne (1.95 mL, 17 mmol) was treated with n-BuLi in
hexane (1.58 M, 10.1 mL, 16 mmol) at ꢁ78 ꢀC for 30 min,
followed by reaction with the THF (5 mL) solution of
benzaldehyde (2a, 1.52 mL, 15 mmol) for 3 h at rt. Workup
as described previously gave 1-phenylhept-2-yn-1-ol
(2.71 g, 96%) as a colorless oil and used for the next step
without further purification. A THF (16 mL) solution of 1-
phenylhept-2-yn-1-ol (753 mg, 4 mmol) and triethylamine
(0.725 mL, 5.2 mmol) was treated with chlorotrimethyl-
silane (0.609 mL, 4.8 mmol). Workup as described previ-
ously gave 58 (997 mg, 96%) as a colorless oil.
1227, 1089, 1013, 956, 843, 741, 695 cmꢁ1 1H NMR
;
(CDCl3, 400 MHz) d 3.07 (m, 1H), 5.74 (d, J¼4.9 Hz,
1H), 6.99 (d, J¼1.2 Hz, 1H), 7.07–7.08 (m, 5H), 7.11 (d,
J¼8.8 Hz, 2H), 7.22–7.25 (m, 1H), 7.29–7.33 (m, 2H),
7.41–7.44 (m, 2H), 7.55 (d, J¼8.8 Hz, 2H); 13C NMR
(CDCl3, 100 MHz) d 76.5, 126.1, 127.7, 127.9, 128.0,
128.1, 128.2, 128.6, 130.3, 131.7, 134.2, 134.4, 139.1,
140.4, 141.3, 198.6; HRMS (EI) calcd for C22H17ClO2
(M+) 348.0917, Found 348.0941.
4.1.49. (2Z)-1-(4-Chlorophenyl)-2-[hydroxy(4-methoxy-
phenyl)methyl]-3-phenylprop-2-en-1-one (61). As de-
scribed for the synthesis of 3 by Method A, 52 (315 mg,
1.0 mmol) and 4-methoxybenzaldehyde (2c, 0.146 mL,
1.2 mmol) were treated with KOt-Bu (11 mg, 0.1 mmol) in
DMF (2 mL). Workup as described previously followed by
silica gel column chromatography (hexane/EtOAc, 3:1)
gave 61 (269 mg, 71%) as a colorless oil: IR (neat) n 3438,
2967, 1652, 1584, 1509, 1400, 1242, 1170, 1089, 1031,
1-Phenylhept-2-yn-1-ol:28 1H NMR (CDCl3, 400 MHz)
d 0.92 (t, J¼7.3 Hz, 3H), 1.38–1.47 (m, 2H), 1.50–1.57
(m, 2H), 2.09 (d, J¼6.1 Hz, 1H), 2.28 (dt, J¼2.0, 7.0 Hz,
2H), 5.45 (d, J¼6.1 Hz, 1H), 7.29–7.33 (m, 1H), 7.35–
7.39 (m, 2H), 7.53–7.55 (m, 2H).
956, 830, 747, 696 cmꢁ1 1H NMR (CDCl3, 400 MHz)
;
Compound 58: IR (neat) n 2958, 1452, 1250, 1137, 1057,
874, 838, 750, 694 cmꢁ1 1H NMR (CDCl3, 400 MHz)
;
d 2.91 (dd, J¼1.5, 4.6 Hz, 1H), 3.77 (s, 3H), 5.69 (d,
J¼4.6 Hz, 1H), 6.84 (d, J¼8.8 Hz, 2H), 6.98 (d, J¼5.2 Hz,
1H), 7.05–7.09 (m, 5H), 7.12 (d, J¼8.8 Hz, 2H), 7.34 (d,
J¼4.3 Hz, 2H), 7.58 (d, J¼8.8 Hz, 2H); 13C NMR (CDCl3,
100 MHz) d 55.3, 76.3, 113.8, 127.7, 128.0, 128.1, 128.3,
128.8, 130.6, 131.5, 132.8, 134.4, 134.6, 139.3, 141.8,
159.1, 198.8; HRMS (EI) calcd for C23H19ClO3 (M+)
378.1023, Found 378.1006.
d 0.19 (s, 9H), 0.90 (t, J¼7.2 Hz, 3H), 1.36–1.45 (m, 2H),
1.47–1.54 (m, 2H), 2.24 (dt, J¼2.2, 7.1 Hz, 2H), 5.47 (s,
1H), 7.24–7.28 (m, 2H), 7.31–7.35 (m, 2H), 7.48 (d,
J¼6.8 Hz, 2H); 13C NMR (CDCl3, 100 MHz) d 0.3, 13.6,
18.5, 22.0, 30.6, 64.7, 80.5, 86.6, 126.0, 127.3, 127.9,
141.8; HRMS (EI) calcd for C16H24OSi (M+) 260.1596,
Found 260.1593.
4.1.50. (2Z)-2-[Hydroxy(phenyl)methyl]-1-(4-methoxy-
phenyl)-3-phenylprop-2-en-1-one (62). As described for
the synthesis of 3 by Method A, 53 (310 mg, 1.0 mmol)
and benzaldehyde (2a, 0.122 mL, 1.2 mmol) were treated
with KOt-Bu (11 mg, 0.1 mmol) in DMF (2 mL). Workup
as described previously followed by silica gel column chro-
matography (hexane/EtOAc, 3:1) gave 62 (287 mg, 83%) as
a white solid: mp 106–107 ꢀC; IR (neat) n 3388, 3024, 1625,
1595, 1423, 1353, 1245, 1167, 1106, 1021, 942, 753,
4.1.47. [[1-(Phenylethynyl)pentyl]oxy]-trimethylsilane
(59).29 As described for the synthesis of 24, a THF
(15 mL) solution of phenylacetylene (26, 1.89 mL,
17 mmol) was treated with n-BuLi in hexane (1.58 M,
10.1 mL, 16 mmol), followed by reaction with a THF
(5 mL) solution of valeraldehyde (2u, 1.60 mL, 15 mmol)
for 3 h at rt. Workup as described previously gave 1-phenyl-
hept-1-yn-3-ol (2.73 g, 97%) as a colorless oil and used
for the next step without further purification. A THF
(16 mL) solution of 1-phenylhept-1-yn-3-ol (753 mg,
4 mmol) and triethylamine (0.725 mL, 5.2 mmol) was
treated with chlorotrimethylsilane (0.609 mL, 4.8 mmol).
Workup as described previously gave 59 (902 mg, 87%)
as a colorless oil.
697 cmꢁ1
;
1H NMR (CDCl3, 400 MHz) d 3.30 (d,
J¼4.9 Hz, 1H), 3.73 (s, 3H), 5.69 (d, J¼4.9 Hz, 1H), 6.63
(d, J¼9.0 Hz, 2H), 6.90 (d, J¼1.0 Hz, 1H), 7.06–7.12 (m,
5H), 7.20–7.24 (m, 1H), 7.28–7.32 (m, 2H), 7.42–7.44 (m,
2H), 7.63 (d, J¼9.0 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
d 55.2, 76.9, 113.1, 126.1, 127.5, 127.7, 127.8, 128.1,
128.6, 128.7, 130.9, 131.5, 134.6, 130.6, 141.5, 163.2,
198.3; Anal. calcd for C23H20O3: C, 80.21; H, 5.85. Found:
C, 79.87; H, 6.00.
1-Phenylhept-1-yn-3-ol:27 1H NMR (CDCl3, 400 MHz)
d 0.94 (t, J¼7.1 Hz, 3H), 1.35–1.44 (m, 2H), 1.46–1.53

6280
K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
4.1.51. (2Z)-2-[(4-Chlorophenyl)(hydroxy)methyl]-1-(4-
methoxyphenyl)-3-phenylprop-2-en-1-one (63). As de-
scribed for the synthesis of 3 by Method A, 53 (310 mg,
1.0 mmol) and 4-chlorobenzaldehyde (2e, 0.169 mL,
1.2 mmol) were treated with KOt-Bu (11 mg, 0.1 mmol) in
DMF (2 mL). Workup as described previously followed by
silica gel column chromatography (hexane/EtOAc, 3:1)
gave 63 (313 mg, 83%) as a colorless oil: IR (neat) n 3414,
2972, 1643, 1591, 1489, 1365, 1242, 1164, 1027, 956,
synthesis of 3 by Method A, 56 (281 mg, 1.0 mmol) and
benzaldehyde (2a, 0.122 mL, 1.2 mmol) were treated with
KOt-Bu (11 mg, 0.1 mmol) in DMF (2 mL). After the reac-
tion mixture was quenched, 1 N aq HCl (1 mL), acetonitrile
(2 mL), water, and EtOAc were added, and the separated or-
ganic layer was washed with water, saturated aq NaHCO3,
and brine. After the solution was dried over MgSO4 followed
by removal of the solvent in vacuo, the residue was purified
by silica gel column chromatography (hexane/EtOAc, 2:1)
that gave 66 (127 mg, 40%) as a yellow oil.
1
831, 756, 694 cmꢁ1; H NMR (CDCl3, 400 MHz) d 3.40–
3.44 (m, 1H), 3.74 (s, 3H), 5.65 (d, J¼4.9 Hz, 1H), 6.64
(d, J¼9.0 Hz, 2H), 6.91 (d, J¼1.0 Hz, 1H), 7.07–7.11 (m,
5H), 7.25–7.28 (m, 3H), 7.35–7.39 (m, 2H), 7.62 (d,
J¼9.0 Hz, 2H); 13C NMR (CDCl3, 100 MHz) d 55.2, 76.3,
113.3, 127.5, 127.8, 127.9, 128.2, 128.5, 128.7, 131.4,
131.6, 133.1, 134.4, 139.2, 140.9, 163.3, 198.1; HRMS
(EI) calcd for C23H19ClO3 (M+) 378.1023, Found 378.0992.
As described for the synthesis of 3 by Method B, a THF
(2 mL) solution of 56 (281 mg, 1.0 mmol) was treated with
1 M KOt-Bu in THF (0.1 mL, 0.1 mmol), followed by reac-
tion with benzaldehyde (2a, 0.122 mL, 1.2 mmol). Workup
as described in Method A followed by silica gel column chro-
matography (hexane/EtOAc, 2:1) gave 66 (246 mg, 78%) as
a yellow oil: IR (neat) n 3333, 3058, 1675, 1582, 1449, 1364,
1
4.1.52. (2Z)-2-[Hydroxy(4-methoxyphenyl)methyl]-1-(4-
methoxyphenyl)-3-phenylprop-2-en-1-one (9). As de-
scribed for the synthesis of 3 by Method A, 53 (310 mg,
1.0 mmol) and 4-methoxybenzaldehyde (2c, 0.169 mL,
1.2 mmol) were treated with KOt-Bu (11 mg, 0.1 mmol) in
DMF (2 mL). Workup as described previously followed by
silica gel column chromatography (hexane/EtOAc, 2:1)
gave 9 (296 mg, 79%) as a colorless oil.
1227, 1023, 964, 866, 750, 695 cmꢁ1; H NMR (CDCl3,
400 MHz) d 5.54 (br s, 1H), 5.70 (s, 1H), 6.91 (s, 1H),
7.10–7.12 (m, 5H), 7.21–7.24 (m, 1H), 7.29–7.32 (m, 2H),
7.39–7.45 (m, 3H), 7.77 (dt, J¼1.7, 7.8 Hz, 1H), 7.90 (d,
J¼7.8 Hz, 1H), 8.61 (d, J¼3.9 Hz, 1H); 13C NMR (CDCl3,
100 MHz) d 75.6, 123.1, 126.1, 126.8, 127.1, 127.7,
127.86, 127.89, 128.4, 134.4, 134.8, 137.2, 140.9, 144.0,
148.2, 153.4, 197.9; HRMS (EI) calcd for C21H17NO2 (M+)
315.1259, Found 315.1249.
4.1.53. (2Z)-1-(2-Furyl)-2-[hydroxy(phenyl)methyl]-3-
phenylprop-2-en-1-one (64). As described for the synthesis
of 3 by Method A, 54 (270 mg, 1.0 mmol) and benzaldehyde
(2a, 0.122 mL, 1.2 mmol) were treated with KOt-Bu (11 mg,
0.1 mmol) in DMF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 3:1) gave 64 (242 mg, 80%) as a colorless oil: IR
(neat) n 3412, 3028, 1625, 2560, 1459, 1394, 1266, 1017,
4.1.56. (1Z,4E)-2-[Hydroxy(phenyl)methyl]-1,5-di-
phenylpenta-1,4-dien-3-one (67). As described for the syn-
thesis of 3 by Method A, 57 (306 mg, 1.0 mmol) and
benzaldehyde (2a, 0.122 mL, 1.2 mmol) were treated with
KOt-Bu (11 mg, 0.1 mmol) in DMF (2 mL). Workup as de-
scribed previously followed by silica gel column chromato-
graphy (hexane/EtOAc, 3:1) gave 67 (94 mg, 28%) as
a yellow oil.
955, 855, 754, 695 cmꢁ1 1H NMR (CDCl3, 400 MHz)
;
d 3.44 (d, J¼5.4 Hz, 1H), 5.68 (d, J¼5.1 Hz, 1H), 6.34 (d,
J¼16.1 Hz, 1H), 7.08 (s, 1H), 7.11 (d, J¼7.1 Hz, 2H),
7.21–7.29 (m, 11H), 7.31–7.35 (m, 2H), 7.44 (d, J¼7.6 Hz,
2H); 13C NMR (CDCl3, 100 MHz) d 76.3, 111.9, 120.6,
126.2, 127.6, 127.8, 127.9, 128.1, 128.4, 132.7, 134.9,
140.5, 141.2, 146.8, 151.7, 186.2; HRMS (EI) calcd for
C20H16O3 (M+) 304.1099, Found 304.1092.
As described for the synthesis of 3 by Method B, a THF
(2 mL) solution of 57 (306 mg, 1.0 mmol) was treated with
1 M KOt-Bu in THF (0.1 mL, 0.1 mmol), followed by reac-
tion with benzaldehyde (2a, 0.122 mL, 1.2 mmol). Workup
as described previously followed by silica gel column chro-
matography (hexane/EtOAc, 3:1) gave 67 (169 mg, 50%)
as a yellow oil: IR (neat) n 3402, 3027, 1622, 1593, 1448,
1
4.1.54. (2Z)-2-[Hydroxy(phenyl)methyl]-3-phenyl-1-(2-
thienyl)prop-2-en-1-one (65). As described for the synthe-
sis of 3 by Method A, 55 (286 mg, 1.0 mmol) and benzalde-
hyde (2a, 0.122 mL, 1.2 mmol) were treated with KOt-Bu
(11 mg, 0.1 mmol) in DMF (2 mL). Workup as described
previously followed by silica gel column chromatography
(hexane/EtOAc, 3:1) gave 65 (243 mg, 76%) as a colorless
oil: IR (neat) n 3413, 3027, 1619, 1514, 1408, 1240, 1033,
1365, 1228, 1193, 1068, 976, 727, 695 cmꢁ1; H NMR
(CDCl3, 400 MHz) d 3.44 (d, J¼5.4 Hz, 1H), 5.68 (d,
J¼5.1 Hz, 1H), 6.34 (d, J¼16.1 Hz, 1H), 7.08 (s, 1H), 7.11
(d, J¼7.1 Hz, 2H), 7.21–7.29 (m, 11H), 7.31–7.35 (m, 2H),
7.44 (d, J¼7.6 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
d 76.4, 126.1, 127.5, 127.9, 128.09, 128.13, 128.3, 128.9,
130.0, 133.5, 134.1, 135.0, 140.9, 143.2, 143.6, 197.5;
HRMS (EI) calcd for C24H20O2 (M+) 340.1463, Found
340.1464.
924, 839, 722, 694 cmꢁ1 1H NMR (CDCl3, 400 MHz)
;
d 3.18 (d, J¼4.9 Hz, 1H), 5.71 (d, J¼4.6 Hz, 1H), 6.73 (dd,
J¼3.9, 4.9 Hz, 1H), 6.93 (s, 1H), 7.10–7.14 (m, 3H), 7.16–
7.20 (m, 3H), 7.20–7.25 (m, 1H), 7.28–7.32 (m, 2H), 7.41–
7.45 (m, 3H); 13C NMR (CDCl3, 100 MHz) d 76.5, 126.2,
127.5, 127.6, 127.8, 127.9, 128.1, 128.6, 131.4, 134.5,
134.7, 140.4, 142.0, 143.2, 191.5; HRMS (EI) calcd for
C20H16O2S (M+) 320.0871, Found 320.0895.
4.1.57. (2Z)-2-[Hydroxy(phenyl)methyl]-1-phenylhept-2-
en-1-one (68). As described for the synthesis of 3 by Method
A, 58 (260 mg, 1.0 mmol) and benzaldehyde (2a, 0.122 mL,
1.2 mmol) were treated with KOt-Bu (22 mg, 0.2 mmol) in
DMF (2 mL). Workup as described previously followed by
silica gel column chromatography (hexane/EtOAc, 10:1)
gave 68 (67 mg, 23%) as a colorless oil: IR (neat) n 3437,
4.1.55. (2Z)-2-[Hydroxy(phenyl)methyl]-3-phenyl-1-
pyridin-2-ylprop-2-en-1-one (66). As described for the
2957, 1650, 1595, 1449, 1377, 1232, 1022, 956, 697 cmꢁ1
;
1H NMR (CDCl3, 400 MHz) d 0.74 (t, J¼7.1 Hz, 3H),

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6281
1.10–1.18 (m, 2H), 1.22–1.30 (m, 2H), 1.80 (q, J¼7.6 Hz,
2H), 3.14 (d, J¼5.4 Hz, 1H), 5.54 (d, J¼5.4 Hz, 1H), 5.91
(dt, J¼1.0, 7.8 Hz, 1H), 7.19–7.23 (m, 1H), 7.27–7.31 (m,
2H), 7.35–7.38 (m, 4H), 7.50 (t, J¼7.5 Hz, 1H), 7.71–7.73
(m, 2H); 13C NMR (CDCl3, 100 MHz) d 13.7, 22.1, 26.9,
29.4, 31.0, 126.0, 127.3, 128.0, 128.1, 128.9, 133.0, 134.8,
137.4, 140.8, 141.2, 199.6; HRMS (EI) calcd for
C20H22O2 (M+) 294.1620, Found 294.1628.
a solution of tert-butyldimethylsilylchloride (1.33 g,
8.8 mmol) in THF (4 mL) was added and the mixture was
warmed to rt. After 2 h, water and tert-butyl methyl ether
were added, and the separated organic layer was washed
with brine and dried over MgSO4. After removal of the sol-
vent in vacuo, the residue was purified by silica gel column
chromatography (hexane/EtOAc, 10:1) to give 73 (0.78 g,
30%) as a colorless oil: IR (neat) n 2957, 1599, 1490, 1443,
1250, 1192, 1061, 977, 838, 753, 689 cmꢁ1 1H NMR
;
4.1.58. Preparation of (2Z)-2-[hydroxy(phenyl)methyl]-
1,3-diphenylprop-2-en-1-one (3) from 24 using phase
transfer catalyst. Typical procedure. To a solution of 24
(280 mg, 1 mmol), the catalyst 6 (47 mg, 0.1 mmol), and
benzaldehyde (2a, 0.122 mL, 1.2 mmol) in THF (2 mL)
was added K3PO4 (212 mg, 1.0 mmol) at rt under Ar. After
6 h, the insoluble salts were filtered and the yields of 3, 27
and 24 were assayed by HPLC analysis of the filtrate. After
the remaining sample was treated with EtOAc and water, the
separated organic layer was washed with water and brine,
and dried over MgSO4. After removal of the solvent in va-
cuo, the residue was purified by silica gel column chromato-
graphy (hexane/EtOAc, 10:1) to give 3. HPLC analysis for
determination of the yield of 3, 27 and 24: YMC Pro C18
(4.6 mm i.d.ꢂ150 mm), UV 254 nm, flow rate 1.0 mL/
min, MeCN/H2O/70% aq HClO4¼600:400:1 (v/v/v), reten-
tion time 3: 7.4 min; 27: 9.1 min; 24: 5.4 min. HPLC analy-
sis for determination of the enantiomeric excess of 3:
DAICEL CHIRALCEL OD (4.6 mm i.d.ꢂ250 mm), UV
254 nm, flow rate 1.0 mL/min, hexane/2-propanol¼9:1, re-
tention time 3: 12.3 min, 14.1 min; 4: 13.1 min, 19.8 min.
(CDCl3, 400 MHz) d 0.20 (s, 3H), 0.22 (s, 3H), 0.97 (s,
9H), 5.73 (s, 1H), 7.281–7.30 (m, 4H), 7.35–7.38 (m, 2H),
7.42–7.44 (m, 2H), 7.55–7.57 (m, 2H).
4.1.61. [(1,3-Diphenyl-1,2-propadienyl)oxy]-tert-butyldi-
methylsilane (74). To a solution of 73 (161 mg, 0.5 mmol)
in THF (1 mL) was added 1 M KOt-Bu in THF (0.05 mL,
0.05 mmol) at ꢁ78 ꢀC under N2. After 20 min, water and
tert-butyl methyl ether were added, and the separated or-
ganic layer was dried over MgSO4. After removal of the sol-
vent in vacuo, crude 74 (151 mg) was obtained as a yellow
oil: IR (neat) n 2929, 1929, 1597, 1492, 1447, 1251, 1202,
1072, 1019, 834, 778, 690 cmꢁ1
;
1H NMR (CDCl3,
400 MHz) d 0.14 (s, 3H), 0.19 (s, 3H), 1.02 (s, 9H), 6.94
(s, 1H), 7.22–7.27 (m, 2H), 7.30–7.35 (m, 4H), 7.38–7.41
(m, 2H), 7.53–7.55 (m, 2H); 13C NMR (CDCl3, 100 MHz)
d ꢁ4.5, 18.4, 26.0, 107.3, 124.9, 127.5, 127.7, 128.1,
128.6, 129.7, 134.2, 135.0, 200.1.
4.1.62. [[3-(4-Methoxyphenyl)-1-phenyl-2-propynyl]-
oxy]-trimethylsilane (78). As described for the synthesis
of 24, a THF (4 mL) solution of 2-ethynyl-4-methoxyben-
zene (529 mg, 4 mmol) was treated with n-BuLi in hexane
(1.57 M, 2.55 mL, 4 mmol), followed by reaction with
a THF (3 mL) solution of benzaldehyde (2a, 0.41 mL,
4 mmol). Workup as described previously followed by silica
gel column chromatography (hexane/EtOAc, 10:1) gave 3-
(4-methoxyphenyl)-1-phenylprop-2-yn-1-ol (0.83 g, 87%)
as a colorless oil. ATHF (10 mL) solution of 3-(4-methoxy-
phenyl)-1-phenylprop-2-yn-1-ol (596 mg, 2.5 mmol) and
triethylamine (0.45 mL, 3.25 mmol) was treated with chloro-
trimethylsilane (0.38 mL, 3 mmol). Workup as described
previously gave 78 (0.76 g, 98%) as a colorless oil.
4.1.59. Preparation of optically active (R)-[(1,3-diphenyl-
2-propynyl)oxy]-trimethylsilane (24).19 To a solution of
phenylacetylene (26, 2.31 mL, 21 mmol) in THF (20 mL)
was added 1 M Et2Zn in hexane (20 mL, 20 mmol) at rt un-
der Ar, and then the mixture was warmed to 70 ꢀC. After 5 h,
to the mixture was added a solution of (S)-BINOL (285 mg,
1 mmol), phenol (100 mg, 1 mmol), and Ti(Oi-Pr)4 (0.9 mL,
3 mmol) in THF (10 mL) at 0 ꢀC. After 40 min, benzalde-
hyde (2a, 1.02 mL, 10 mmol) was added to the mixture,
and then the mixture was stirred at 0 ꢀC for 24 h. 1 N aq
HCl (100 mL) and tert-butyl methyl ether (50 mL) were
added, and the separated organic layer was washed with
brine and dried over MgSO4. After removal of the solvent
in vacuo, the residue was purified by silica gel column chro-
matography (hexane/EtOAc, 10:1) to give (R)-4 (1.79 g,
82%) as a colorless oil.
3-(4-Methoxyphenyl)-1-phenylprop-2-yn-1-ol:31 1H NMR
(CDCl3, 400 MHz) d 2.31 (s, 1H), 3.80 (s, 3H), 5.67 (s,
1H), 6.83 (d, J¼8.8 Hz, 2H), 7.33–7.41 (m, 5H), 7.61 (d,
J¼7.6 Hz, 2H).
A THF (16 mL) solution of optically active (R)-4 (874 mg,
4.2 mmol) and triethylamine (0.76 mL, 5.5 mmol) was
treated with chlorotrimethylsilane (0.64 mL, 5.0 mmol).
Workup as described previously gave optically active (R)-
24 (1.15 g, 98%) as a pale yellow oil. The enantiomeric
excess of 4 was determined by HPLC analysis: DAICEL
CHIRALCEL OD (4.6 mm i.d.ꢂ250 mm), UV 254 nm,
flow rate 1.0 mL/min, hexane/2-propanol¼9:1, retention
time 4: 13.1 min (major), 19.8 min (minor).
Compound 78: IR (neat) n 2957, 1770, 1508, 1246, 1057,
1
829, 750, 697 cmꢁ1; H NMR (CDCl3, 400 MHz) d 0.24
(s, 9H), 3.80 (s, 3H), 5.70 (s, 1H), 6.83 (d, J¼8.8 Hz, 2H),
7.28–7.39 (m, 5H), 7.56 (d, J¼7.1 Hz, 2H); 13C NMR
(CDCl3, 100 MHz) d 0.5, 55.3, 65.2, 85.9, 88.3, 113.8,
114.9, 126.4, 127.7, 128.2, 132.9, 141.5, 159.4; HRMS
(EI) calcd for C19H22O2Si (M+) 310.1389, Found 310.1304.
4.1.63. [[1-Phenyl-3-[4-(tetrahydro-2H-pyran-2-yloxy)-
phenyl]-2-propynyl]oxy]-trimethylsilane
(79).
As
4.1.60. [(1,3-Diphenyl-2-propynyl)oxy]-tert-butyldi-
methylsilane (73).30 To a solution of 4 (1.67 g, 8 mmol) in
THF (8 mL) was added n-BuLi in hexane (1.58 M,
5.57 mL, 8.8 mmol) at ꢁ78 ꢀC under N2, and then the mix-
ture was immediately warmed to 0 ꢀC. After 10 min,
described for the synthesis of 24, a THF (7 mL) solution of
2-(4-ethynylphenoxy)tetrahydro-2H-pyran (1.42 g, 7 mmol)
was treated with n-BuLi in hexane (2.67 M, 2.62 mL,
7 mmol), followed by reaction with a THF (3 mL) solution
of benzaldehyde (2a, 0.71 mL, 7 mmol). Workup as

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K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
described previously followed by silica gel column chroma-
tography (hexane/EtOAc, 5:1) gave 1-phenyl-3-[4-(tetrahy-
dro-2H-pyran-2-yloxy)phenyl]prop-2-yn-1-ol (2.08 g, 96%)
as a pale yellow oil. A THF (25 mL) solution of 1-phenyl-
3-[4-(tetrahydro-2H-pyran-2-yloxy)phenyl]prop-2-yn-1-ol
(1.04 g, 3.37 mmol) and triethylamine (0.61 mL, 4.38 mmol)
was treatedwithchlorotrimethylsilane(0.51 mL, 4.05 mmol).
Workup as described previously gave 79 (1.10 g, 86%) as
a colorless oil.
HRMS (EI) calcd for C18H19ClOSi (M+) 314.0894, Found
314.0854.
4.1.65. [[3-(2-Naphthyl)-1-phenyl-2-propynyl]oxy]-tri-
methylsilane (81). As described for the synthesis of 24,
a THF (4 mL) solution of 2-ethynylnaphthalene (609 mg,
4 mmol) was treated with n-BuLi in hexane (1.57 M,
2.55 mL, 4 mmol), followed by reaction with a THF
(2 mL) solution of benzaldehyde (2a, 0.41 mL, 4 mmol).
Workup as described previously followed by silica gel col-
umn chromatography (hexane/EtOAc, 5:1) gave 3-(2-naph-
thyl)-1-phenylprop-2-yn-1-ol (0.81 g, 78%) as a pale yellow
solid. ATHF (10 mL) solution of 3-(4-chlorophenyl)-1-phe-
nylprop-2-yn-1-ol (646 mg, 2.5 mmol) and triethylamine
(0.45 mL, 3.25 mmol) was treated with chlorotrimethyl-
silane (0.38 mL, 3 mmol). Workup as described previously
gave 81 (0.78 g, 94%) as a pale yellow solid.
1-Phenyl-3-[4-(tetrahydro-2H-pyran-2-yloxy)phenyl]prop-
2-yn-1-ol: IR (neat) n 3390, 2946, 1770, 1604, 1506, 1384,
1
1239, 1020, 956, 917, 832, 697 cmꢁ1; H NMR (CDCl3,
400 MHz) d 1.58–1.73 (m, 3H), 1.83–1.87 (m, 2H), 1.95–
2.04 (m, 1H), 2.36 (br s, 1H), 3.58–3.62 (m, 1H), 3.84–
3.90 (m, 1H), 5.42 (t, J¼3.2 Hz, 1H), 5.67 (d, J¼7.3 Hz,
1H), 6.99 (d, J¼8.8 Hz, 2H), 7.32–7.41 (m, 5H), 7.62 (d,
J¼8.8 Hz, 2H); 13C NMR (CDCl3, 100 MHz) d 18.8, 25.3,
30.3, 62.1, 65.1, 86.6, 87.4, 96.2, 115.2, 116.2, 126.6,
128.2, 128.5, 133.0, 140.7, 157.1; HRMS (EI) calcd for
C20H20O3 (M+) 308.1412, Found 308.1388.
3-(2-Naphthyl)-1-phenylprop-2-yn-1-ol: mp 51 ꢀC; IR
(neat) n 3289, 2995, 1770, 1383, 1246, 1014, 818, 744,
1
695 cmꢁ1; H NMR (CDCl3, 400 MHz) d 2.43 (br s, 1H),
5.74 (s, 1H), 7.34–7.52 (m, 6H), 7.65 (d, J¼7.6 Hz, 2H),
7.76–7.81 (m, 3H), 7.99 (s, 1H); 13C NMR (CDCl3,
100 MHz) d 65.2, 87.0, 89.0, 199.6, 126.4, 126.6, 126.7,
127.61, 127.62, 127.8, 128.2, 128.3, 128.6, 131.6, 132.7,
132.8, 140.5; Anal. calcd for C19H14O: C, 88.34; H, 5.46.
Found: C, 88.22; H, 5.57.
Compound 79: IR (neat) n 2950, 1770, 1604, 1506, 1383,
1239, 1060, 958, 918, 831, 751, 695 cmꢁ1 1H NMR
;
(CDCl3, 400 MHz) d 0.23 (s, 9H), 1.56–1.70 (m, 3H),
1.83–1.86 (m, 2H), 1.95–2.05 (m, 1H), 3.57–3.61 (m,
1H), 3.83–3.90 (m, 1H), 5.41 (t, J¼2.9 Hz, 1H), 5.69 (s,
1H), 6.97 (d, J¼8.3 Hz, 2H), 7.27–7.38 (m, 5H), 7.55 (d,
J¼7.6 Hz, 2H); 13C NMR (CDCl3, 100 MHz) d 0.6,
18.8, 25.3, 30.3, 62.0, 65.2, 85.9, 88.3, 96.1, 115.7,
116.2, 126.4, 127.6, 128.2, 132.8, 141.4, 156.9; Anal.
calcd for C23H20O3Si: C, 72.59; H, 7.42. Found: C,
72.56; H, 7.95.
Compound 81: mp 41 ꢀC; IR (neat) n 2995, 1770, 1382,
1248, 1064, 841, 748, 698 cmꢁ1
;
1H NMR (CDCl3,
400 MHz) d 0.25 (s, 9H), 5.76 (s, 1H), 7.30–7.34 (m, 1H),
7.38–7.41 (m, 2H), 7.46–7.50 (m, 3H), 7.60 (d, J¼7.0 Hz,
2H), 7.75–7.81 (m, 3H), 7.96 (s, 1H); 13C NMR (CDCl3,
100 MHz) d 0.6, 65.3, 86.2, 90.0, 120.0, 126.36, 126.39,
126.5, 127.6, 127.8, 128.2, 128.3, 131.4, 132.68, 132.74,
141.3; Anal. calcd for C22H22OSi: C, 79.95; H, 6.71. Found:
C, 79.77; H, 6.72.
4.1.64. [[3-(4-Chlorophenyl)-1-phenyl-2-propynyl]oxy]-
trimethylsilane (80). As described for the synthesis of 24,
a THF (4 mL) solution of 4-chloro-2-ethynylbenzene
(546 mg, 4 mmol) was treated with n-BuLi in hexane
(1.57 M, 2.55 mL, 4 mmol), followed by reaction with
a THF (2 mL) solution of benzaldehyde (2a, 0.41 mL,
4 mmol). Workup as described previously followed by silica
gel column chromatography (hexane/EtOAc, 5:1) gave 3-(4-
chlorophenyl)-1-phenylprop-2-yn-1-ol (0.89 g, 91%) as
a white solid. A THF (25 mL) solution of 3-(4-chloro-
phenyl)-1-phenylprop-2-yn-1-ol (607 mg, 2.5 mmol) and
triethylamine (0.45 mL, 3.25 mmol) was treated with chlo-
rotrimethylsilane (0.38 mL, 3 mmol). Workup as described
previously gave 79 (1.10 g, 86%) as a colorless oil.
4.1.66. [[1-Phenyl-3-(2-thienyl)-2-propynyl]oxy]-trime-
thylsilane (82). As described for the synthesis of 24, a THF
(2 mL) solution of 2-ethynylthiophene (0.40 g, 2.2 mmol)
was treated with n-BuLi in hexane (1.57 M, 1.40 mL,
2.2 mmol), followed by reaction with a THF (2 mL) solution
of benzaldehyde (2a, 0.41 mL, 4 mmol). Workup as de-
scribed previously gave 1-phenyl-3-(2-thienyl)prop-2-yn-1-
ol (0.55 g, quant.) as a pale yellow oil and used for the next
step without further purification. A THF (8 mL) solution of
1-phenyl-3-(2-thienyl)prop-2-yn-1-ol (0.40 g, 1.87 mmol)
and triethylamine (0.34 mL, 2.43 mmol) was treated with
chlorotrimethylsilane (0.28 mL, 2.24 mmol). Workup as
described previously gave 82 (0.53 g, 99%) as a yellow oil.
3-(4-Chlorophenyl)-1-phenylprop-2-yn-1-ol: mp 56 ꢀC; IR
(neat) n 3235, 2995, 1770, 1488, 1383, 1246, 1014, 824,
1
756, 696 cmꢁ1; H NMR (CDCl3, 400 MHz) d 2.35 (br s,
1H), 5.67 (s, 1H), 7.27–7.30 (m, 2H), 7.32–7.42 (m, 5H),
7.59 (d, J¼7.9 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
d 65.1, 85.5, 89.6, 120.8, 126.5, 128.4, 128.5, 128.6,
132.8, 134.5, 140.3; Anal. calcd for C15H11ClO: C, 74.23;
H, 4.57. Found: C, 74.01; H, 4.83.
1-Phenyl-3-(2-thienyl)prop-2-yn-1-ol:32 1H NMR (CDCl3,
400 MHz) d 2.27 (br s, 1H), 5.71 (s, 1H), 6.98 (dd, J¼3.7,
5.1 Hz, 1H), 7.24–7.28 (m, 2H), 7.34–7.43 (m, 3H), 7.59–
7.61 (m, 2H).
Compound 82: IR (neat) n 2995, 1770, 1383, 1248, 1058,
1
Compound 80: IR (neat) n 2957, 1770, 1489, 1383, 1249,
839, 750, 694 cmꢁ1; H NMR (CDCl3, 400 MHz) d 0.24
1
1087, 844, 734, 697 cmꢁ1; H NMR (CDCl3, 400 MHz)
(s, 9H), 5.71 (s, 1H), 6.96 (dd, J¼3.7, 5.1 Hz, 1H), 7.21
(dd, J¼1.2, 3.7 Hz, 1H), 7.23–7.25 (m, 1H), 7.29–7.40 (m,
3H), 7.53–7.55 (m, 2H); 13C NMR (CDCl3, 100 MHz)
d 0.5, 65.3, 79.3, 93.5, 122.6, 126.3, 126.8, 127.0, 127.8,
d 0.23 (s, 9H), 5.69 (s, 1H), 7.26–7.40 (m, 7H), 7.53–7.55
(m, 2H); 13C NMR (CDCl3, 100 MHz) d 65.1, 84.7, 90.7,
121.2, 126.3, 127.8, 128.3, 128.5, 132.7, 134.3, 141.1;

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6283
128.3, 131.9, 140.9; Anal. calcd for C16H18OSSi: C, 67.08;
H, 6.33. Found: C, 66.63; H, 6.36.
400 MHz) d 6.80 (d, J¼12.9 Hz, 1H), 7.09 (d, J¼13.0 Hz,
1H), 7.26–7.28 (m, 3H), 7.36–7.39 (m, 2H), 7.45–7.47 (m,
0.42H), 7.55 (d, J¼8.6 Hz, 2H), 7.63 (d, J¼8.6 Hz,
0.28H), 7.76 (d, J¼15.6 Hz, 0.14H), 7.92 (d, J¼8.6 Hz,
2H), 8.18 (d, J¼8.5 Hz, 0.28H). The ratio of Z- and E-iso-
mers was determined by 1H NMR analysis of vinylic proton,
d 6.80 and 7.76.
4.1.67. [[3-(2,6-Dimethylphenyl)-1-phenyl-2-propynyl]-
oxy]-trimethylsilane (83). As described for the synthesis
of 24, a THF (6 mL) solution of 2-ethynyl-1,3-dimethylbenz-
ene (781 mg, 6 mmol) was treated with n-BuLi in hexane
(2.67 M, 2.25 mL, 6 mmol), followed by reaction with
a THF (3 mL) solution of benzaldehyde (2a, 0.41 mL,
4 mmol). Workup as described previously gave 3-(2,6-di-
methylphenyl)-1-phenylprop-2-yn-1-ol (1.28 g, 90%) as
a pale yellow solid and used for the next step without further
purification. A THF (10 mL) solution of 3-(2,6-dimethyl-
phenyl)-1-phenylprop-2-yn-1-ol (0.64 g, 2.71 mmol) and
triethylamine (0.45 mL, 3.25 mmol) was treated with chlo-
rotrimethylsilane (0.38 mL, 3 mmol). Workup as described
previously gave 83 (788 mg, 94%) as a pale yellow oil.
4.1.70. (2Z)-1-(4-Methoxyphenyl)-3-phenylprop-2-en-1-
one (86).35 As described for the synthesis of 84, 53
(0.280 mg, 1.0 mmol) was treated with 1 M KOt-Bu in
THF (0.1 mmol), and then 2 M sulfuric acid in DME
(1 mL, 2.0 mmol) in THF (2 mL). Workup as described pre-
viously followed by silica gel column chromatography (hex-
ane/EtOAc, 20:1) gave a mixture of Z-86 and E-86 (97:3,
157 mg, 66%) as a yellow solid: 1H NMR (DMSO-d6,
400 MHz) d 3.82 (s, 3H), 3.86 (s, 0.09H), 6.75 (d,
J¼13.0 Hz, 1H), 6.97 (d, J¼13.0 Hz, 1H), 7.01 (d,
J¼9.0 Hz, 2H), 7.21–7.28 (m, 3H), 7.35–7.37 (m, 2H),
7.70 (d, J¼15.6 Hz, 0.03H), 7.92 (d, J¼8.8 Hz, 2H), 8.15–
8.18 (m, 0.06H). The ratio of Z- and E-isomers was deter-
1-Phenyl-3-(2-thienyl)prop-2-yn-1-ol: mp 66 ꢀC; IR (neat) n
3297, 2995, 1770, 1466, 1381, 1246, 1019, 769, 731,
1
692 cmꢁ1; H NMR (CDCl3, 400 MHz) d 2.28 (br s, 1H),
1
2.43 (s, 6H), 5.78 (s, 1H), 7.03 (d, J¼7.8 Hz, 1H), 7.11
(dd, J¼6.8, 8.3 Hz, 1H), 7.33–7.37 (m, 1H), 7.38–7.42 (m,
2H), 7.64 (d, J¼6.8 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
d 21.2, 65.5, 84.4, 97.0, 122.0, 126.55, 126.60, 127.9,
128.2, 128.5, 140.4, 140.8; Anal. calcd for C17H16O: C,
86.40; H, 6.82. Found: C, 85.99; H, 6.98.
mined by H NMR analysis of vinylic proton, d 6.75 and
7.70.
4.1.71. (2Z)-1-(2-Furyl)-3-phenylprop-2-en-1-one (87).36
As described for the synthesis of 84, 54 (0.280 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mmol), and then 2 M sulfuric acid in DME (1 mL,
2.0 mmol) in THF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 20:1) gave a mixture of Z-87 and E-87 (93:7,
164 mg, 83%) as a yellow solid: 1H NMR (CDCl3,
400 MHz) d 6.50 (dd, J¼1.7, 3.7 Hz, 1H), 6.60 (dd, J¼1.7,
3.7 Hz, 0.07H), 6.69 (d, J¼12.7 Hz, 1H), 7.01 (d,
J¼12.7 Hz, 1H), 7.16–7.17 (m, 1H), 7.30–7.33 (m, 3H),
7.46 (d, J¼15.9 Hz, 0.07H), 7.56–7.57 (m, 1H), 7.63–7.65
(m, 2H), 7.89 (d, J¼15.9 Hz, 0.07H). The ratio of Z- and
Compound 83: IR (neat) n 2995, 1770, 1468, 1377, 1248,
1058, 839, 768, 731, 695 cmꢁ1
;
1H NMR (CDCl3,
400 MHz) d 2.28 (br s, 1H), 2.43 (s, 6H), 5.78 (s, 1H),
7.03 (d, J¼7.8 Hz, 1H), 7.11 (dd, J¼6.8, 8.3 Hz, 1H),
7.33–7.37 (m, 1H), 7.38–7.42 (m, 2H), 7.64 (d, J¼6.8 Hz,
2H); 13C NMR (CDCl3, 100 MHz) d 0.5, 21.3, 65.3, 83.6,
98.1, 122.4, 126.3, 126.5, 127.6, 127.7, 128.2, 140.4,
141.6; HRMS (EI) calcd for C20H24OSi (M+) 308.1596,
Found 308.1550.
1
E-isomers was determined by H NMR analysis of vinylic
4.1.68. (2Z)-1,3-Diphenylprop-2-en-1-one (84).33 To a so-
lution of 24 (280 mg, 1.0 mmol) in THF (2 mL) was added
1 M KOt-Bu in THF (0.1 mmol) at ꢁ78 ꢀC under Ar. After
10 min, 2 M sulfuric acid in DME (1 mL, 2.0 mmol) was
added dropwise for 5 min at ꢁ78 ꢀC. After 10 min, water
and EtOAc were added, and the separated organic layer
was washed with brine, and dried over MgSO4. After re-
moval of the solvent in vacuo, the residue was purified by
silica gel column chromatography (hexane/EtOAc, 20:1)
to give a mixture of Z-84 and E-84 (93:7, 171 mg, 82%) as
proton, d 6.69 and 7.89.
4.1.72. (2Z)-3-Phenyl-1-(2-thienyl)prop-2-en-1-one
(88).37 As described for the synthesis of 84, 55 (0.280 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mmol), and then 2 M sulfuric acid in DME (1 mL,
2.0 mmol) in THF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 20:1) gave a mixture of Z-88 and E-88 (95:5,
162 mg, 76%) as a yellow solid: 1H NMR (DMSO-d6,
400 MHz) d 6.89 (d, J¼13.0 Hz, 1H), 7.04 (d, J¼12.7 Hz,
1H), 7.21 (dd, J¼3.9, 4.9 Hz, 1H), 7.29–7.34 (m, 3H),
7.45–7.47 (m, 0.15H), 7.54–7.56 (m, 2H), 7.73 (d,
J¼15.6 Hz, 0.05H), 7.87–7.89 (m, 1H), 8.01 (dd, J¼1.0,
4.9 Hz, 1H), 8.06 (d, J¼4.9 Hz, 0.05H), 8.34 (d, J¼3.9 Hz,
0.05H). The ratio of Z- and E-isomers was determined by
1H NMR analysis of vinylic proton, d 6.89 and 7.73.
1
a yellow solid: H NMR (DMSO-d6, 400 MHz) d 6.81 (d,
J¼13.0 Hz, 1H), 7.05 (d, J¼13.0 Hz, 1H), 7.23–7.29 (m,
3H), 7.47–7.51 (m, 2H), 7.59–7.62 (m, 1H), 7.75 (d,
J¼15.6 Hz, 0.07H), 7.92–7.95 (m, 2H), 8.13–8.16 (m,
0.14H). The ratio of Z- and E-isomers was determined by
1H NMR analysis of vinylic proton, d 6.81 and 7.75.
4.1.69. (2Z)-1-(4-Chlorophenyl)-3-phenylprop-2-en-1-
one (85).34 As described for the synthesis of 84, 52
(0.280 mg, 1.0 mmol) was treated with 1 M KOt-Bu in
THF (0.1 mmol), and then 2 M sulfuric acid in DME
(1 mL, 2.0 mmol) in THF (2 mL). Workup as described pre-
viously followed by silica gel column chromatography (hex-
ane/EtOAc, 20:1) gave a mixture of Z-85 and E-85 (88:12,
176 mg, 73%) as a yellow solid: 1H NMR (DMSO-d6,
4.1.73. (1Z,4E)-1,5-Diphenylpenta-1,4-dien-3-one (89).
As described for the synthesis of 84, 57 (306 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mmol), and then 2 M sulfuric acid in DME (1 mL,
2.0 mmol) in THF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 20:1) gave a mixture of Z-89 and E-89 (80:20,

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K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
1
176 mg, 75%) as a yellow oil: IR (neat) n 2996, 1770, 1671,
1589, 1324, 1246, 1194, 1095, 980, 787, 687 cmꢁ1; 1H NMR
(DMSO-d6, 400 MHz) d 6.46 (d, J¼12.7 Hz, 1H), 6.80 (d,
J¼16.1 Hz, 1H), 6.93 (d, J¼12.7 Hz, 1H), 7.22–7.32 (m,
7.2H), 7.36–7.38 (m, 1.2H), 7.42–7.44 (m, 2H), 7.49–7.53
(m, 3H), 7.68–7.72 (m, 1.2H); 13C NMR (CDCl3,
100 MHz) d 126.9, 128.0, 128.18, 128.24, 128.3, 128.7,
129.2, 130.4, 135.0, 138.9, 143.2, 192.1; HRMS (EI) calcd
for C17H14O (M+) 234.1045, Found 234.1004. The ratio of
was determined by H NMR analysis of vinylic proton,
d 6.84 and 7.67.
4.1.77. (2Z)-3-(2-Naphthyl)-1-phenylprop-2-en-1-one
(93). As described for the synthesis of 84, 81 (330 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mmol), and then 2 M sulfuric acid in DME (1 mL,
2.0 mmol) in THF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 10:1) gave a mixture of Z-93 and E-93 (80:20,
191 mg, 85%) as a yellow solid: IR (neat) n 2995, 1770,
1
Z- and E-isomers was determined by H NMR analysis of
vinylic proton, d 6.46 and 7.68–7.72.
1659, 1588, 1383, 1246, 1057, 824, 691 cmꢁ1; H NMR
1
4.1.74. (2Z)-3-(4-Methoxyphenyl)-1-phenylprop-2-en-1-
one (90).34 As described for the synthesis of 84, 78
(310 mg, 1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mmol), and then 2 M sulfuric acid in DME (1 mL,
2.0 mmol) in THF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 10:1) gave E-90 (180 mg, 76%) as a yellow solid:
1H NMR (DMSO-d6, 400 MHz) d 3.82 (s, 3H), 7.01
(d, J¼8.8 Hz, 2H), 7.56 (m, 2H), 7.65 (m, 1H), 7.70
(d, J¼15.6 Hz, 1H), 7.79 (d, J¼15.6 Hz, 1H), 7.85 (d,
J¼8.8 Hz, 2H), 8.12 (m, 2H), 8.25–8.28 (m, 2H), 8.29–
8.31 (m, 0.06H). The ratio of Z- and E-isomers of clued
product was determined by 1H NMR analysis of clear vinylic
proton, d 6.73 (d, J¼13.0 Hz) and 7.70.
(DMSO-d6, 400 MHz) d 6.92 (d, J¼12.7 Hz, 1H), 7.23 (d,
J¼13.0 Hz, 1H), 7.46–7.51 (m, 5H), 7.56–7.61 (m, 2H),
7.65–7.70 (m, 0.5H), 7.76 (d, J¼8.5 Hz, 1H), 7.82–7.84
(m, 2H), 7.88–7.93 (m, 0.25H), 7.95–8.00 (m, 4H), 8.07 (d,
J¼15.6 Hz, 0.25H), 8.10–8.15 (m, 0.25H), 8.18–8.20 (m,
0.5H), 8.35 (s, 0.25H); 13C NMR (DMSO-d6, 100 MHz)
d 126.0, 126.2, 126.6, 127.2, 127.3, 127.9, 128.29, 128.33,
128.6, 129.0, 130.5, 132.3, 132.4, 132.6, 133.2, 138.6,
193.6; HRMS (EI) calcd for C19H14O (M+) 258.1045, Found
258.0983. The ratio of Z- and E-isomers was determined by
1H NMR analysis of vinylic proton, d 6.92 and 8.07.
4.1.78. (2Z)-1-Phenyl-3-(2-thienyl)prop-2-en-1-one
(94).39 As described for the synthesis of 84, 82 (286 mg,
1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mmol), and then 2 M sulfuric acid in DME (1 mL,
2.0 mmol) in THF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 10:1) gave a mixture of Z-94 and E-94 (97:3,
175 mg, 82%) as a yellow solid: 1H NMR (DMSO-d6,
400 MHz) d 7.23 (d, J¼12.4 Hz, 1H), 7.39 (dd, J¼3.8,
5.1 Hz, 1H), 7.65 (d, J¼12.2 Hz, 1H), 7.75–7.80 (m, 2H),
7.85–7.89 (m, 2H), 8.00 (d, J¼11.4 Hz, 1H), 8.13 (d,
J¼15.4 Hz, 0.03H), 8.25–8.28 (m, 2H), 8.29–8.31 (m,
0.06H). The ratio of Z- and E-isomers was determined by
1H NMR analysis of vinylic proton, d 7.23 and 8.13.
4.1.75. (2Z)-1-Phenyl-3-[4-(tetrahydro-2H-pyran-2-yl-
oxy)phenyl]prop-2-en-1-one (91). As described for the syn-
thesis of 84, 79 (380 mg, 1.0 mmol) was treated with 1 M
KOt-Bu in THF (0.1 mmol), and then 2 M sulfuric acid in
DME (1 mL, 2.0 mmol)in THF (2 mL). Workup as described
previously followed by silica gel column chromatography
(hexane/EtOAc, 10:1) gave a mixture of Z-91 and E-91
(85:15, 165 mg, 54%) as a yellow oil: IR (neat) n 2946,
1770, 1659, 1596, 1506, 1372, 1241, 1110, 1035, 956, 917,
834, 724, 689 cmꢁ1 1H NMR (DMSO-d6, 400 MHz)
;
d 1.50–1.84 (m, 7.08H), 3.50–3.54 (m, 1.18H), 3.67–3.72
(m, 1.18H), 5.46 (t, J¼3.4 Hz, 1H), 5.57 (s, 0.18H), 6.75
(d, J¼12.9 Hz, 1H), 6.92 (d, J¼8.8 Hz, 2H), 6.97 (d,
J¼12.9 Hz, 1H), 7.08 (d, J¼8.8 Hz, 0.36H), 7.47–7.52 (m,
4H), 7.53–7.65 (m, 1.72H), 7.70 (d, J¼15.6 Hz, 0.18H),
7.79 (d, J¼15.8 Hz, 0.18H), 7.83 (d, J¼8.8 Hz, 0.36H),
8.12 (d, J¼8.3 Hz, 0.36H); 13C NMR (DMSO-d6,
100 MHz) d 18.5, 24.6, 29.7, 61.5, 95.3, 115.7, 124.2,
128.16, 128.22, 128.5, 131.0, 133.1, 136.9, 139.0, 156.8,
193.0; Anal. calcd for C20H20O3: C, 77.90; H, 6.54. Found:
C, 77.49; H, 6.89. The ratio of Z- and E-isomers was deter-
mined by 1H NMR analysis of vinylic proton, d 6.75 and 7.70.
4.1.79. (2Z)-3-(2,6-Dimethylphenyl)-1-phenylprop-2-en-
1-one (95). As described for the synthesis of 84, 83
(308 mg, 1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mmol), and then 2 M sulfuric acid in DME (1 mL,
2.0 mmol) in THF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 10:1) gave a mixture of Z-95 and E-95 (70:30,
128 mg, 54%) as a yellow solid. Pure Z-isomer was obtained
as a pale yellow solid by crystallization from n-hexane.
Compound Z-95: mp 61 ꢀC; IR (neat) n 2995, 1770, 1665,
1
4.1.76. (2Z)-3-(4-Chlorophenyl)-1-phenylprop-2-en-1-
one (92).38 As described for the synthesis of 84, 80
(315 mg, 1.0 mmol) was treated with 1 M KOt-Bu in THF
(0.1 mmol), and then 2 M sulfuric acid in DME (1 mL,
2.0 mmol) in THF (2 mL). Workup as described previously
followed by silica gel column chromatography (hexane/
EtOAc, 10:1) gave a mixture of Z-92 and E-92 (90:10,
172 mg, 71%) as a yellow solid: 1H NMR (DMSO-d6,
400 MHz) d 6.84 (d, J¼12.7 Hz, 1H), 7.00 (d, J¼13.0 Hz,
1H), 7.28–7.31 (m, 2H), 7.36–7.39 (m, 2H), 7.43–7.48 (m,
2H), 7.50–7.54 (m, 0.33H), 7.56–7.60 (m, 1H), 7.60–7.64
(m, 0.11H), 7.67 (d, J¼15.6 Hz, 0.11H), 7.87–7.89 (m,
2H), 8.09–8.11 (m, 0.22H). The ratio of Z- and E-isomers
1448, 1386, 1246, 1058, 1007, 758, 689 cmꢁ1; H NMR
(DMSO-d6, 400 MHz) d 2.10 (s, 6H), 6.94 (d, J¼7.6 Hz,
2H), 7.00–7.03 (m, 1H), 7.17 (d, J¼12.2 Hz, 1H), 7.26 (d,
J¼12.2 Hz, 1H), 7.46–7.50 (m, 2H), 7.57–7.61 (m, 1H),
7.88 (d, J¼8.3 Hz, 2H); 13C NMR (DMSO-d6, 100 MHz)
d 20.0, 126.5, 126.6, 127.3, 127.9, 128.4, 132.9, 134.1,
135.9, 136.7, 141.1, 190.5; Anal. calcd for C17H16O: C,
86.40; H, 6.82. Found: C, 86.37; H, 7.02.
Compound E-95: 1H NMR (DMSO-d6, 400 MHz) d 2.37 (s,
6H), 7.11–7.15 (m, 3H), 7.40 (d, J¼16.1 Hz, 1H), 7.54–7.57
(m, 2H), 7.64–7.68 (m, 1H), 7.83 (d, J¼16.1 Hz, 1H), 8.07
(d, J¼7.3 Hz, 2H).

K. Yoshizawa, T. Shioiri / Tetrahedron 63 (2007) 6259–6286
6285
The ratio of Z- and E-isomers was determined by 1H NMR
analysis of vinylic proton, d 7.26 and 7.40.
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Acknowledgements
We thank Eisai Co., Ltd., for partial support of this research
and financial support to K. Y. This work was also financially
supported in part by a Grant-in-Aid for Scientific Research
from the Japan Society for the Promotion of Science. The
mass spectra were measured by Prof. Osamu Hara and
Dr. Daiki Furuta of Meijo University, to whom the authors’
thanks are due.
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