Synthesis of 1,3-Diaryl-2-methoxyindenes by hydriodic acid-catalyzed cyclization of Aryl[2-(1-aryl-2-methoxyvinyl)phenyl]methanols

Article abstract of DOI:10.1080/00397910802669375

An efficient two-step method for the synthesis of 1,3-diaryl-2- methoxyindenes from 1-(1-aryl-2-methoxyvinyl)-2-bromobenzenes has been developed. Thus, the reaction of 2-(1-aryl-2-methoxyvinyl)phenyllithiums, generated in situ by halogen-lithium exchange between 1-(1-aryl-2-methoxyvinyl)- 2-bromobenzenes and butyllithium, with aromatic aldehydes gives aryl[2-(1-aryl-2-methoxyvinyl)phenyl]methanols, which in turn are treated with a catalytic amount of concentrated hydriodic acid to afford the corresponding 1,3-diaryl-2-methoxyindenes in reasonable yields.

Full text of DOI:10.1080/00397910802669375

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Synthesis of 1,3-Diaryl-2-
methoxyindenes by
Hydriodic Acid–Catalyzed
Cyclization of Aryl[2-(1-aryl-2-
methoxyvinyl)phenyl]methanols
Kazuhiro Kobayashi a , Yuu Shirai a , Toshiyuki
Nagaoka a & Hisatoshi Konishi a
a Division of Applied Chemistry, Department of
Chemistry and Biotechnology , Graduate School of
Engineering, Tottori University , Tottori, Japan
Published online: 14 Jul 2009.
To cite this article: Kazuhiro Kobayashi , Yuu Shirai , Toshiyuki Nagaoka &
Hisatoshi Konishi (2009) Synthesis of 1,3-Diaryl-2-methoxyindenes by Hydriodic
Acid–Catalyzed Cyclization of Aryl[2-(1-aryl-2-methoxyvinyl)phenyl]methanols,
Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 39:16, 2866-2881, DOI: 10.1080/00397910802669375
To link to this article: http://dx.doi.org/10.1080/00397910802669375
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Synthetic Communications1, 39: 2866–2881, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802669375
Synthesis of 1,3-Diaryl-2-methoxyindenes by
Hydriodic Acid–Catalyzed Cyclization of
Aryl[2-(1-aryl-2-methoxyvinyl)phenyl]methanols
Kazuhiro Kobayashi, Yuu Shirai, Toshiyuki Nagaoka, and
Hisatoshi Konishi
Division of Applied Chemistry, Department of Chemistry and
Biotechnology, Graduate School of Engineering,
Tottori University, Tottori, Japan
Abstract: An efficient two-step method for the synthesis of 1,3-diaryl-2-methox-
yindenes from 1-(1-aryl-2-methoxyvinyl)-2-bromobenzenes has been developed.
Thus, the reaction of 2-(1-aryl-2-methoxyvinyl)phenyllithiums, generated in situ
by halogen–lithium exchange between 1-(1-aryl-2-methoxyvinyl)-2-bromoben-
zenes and butyllithium, with aromatic aldehydes gives aryl[2-(1-aryl-2-methoxyvi-
nyl)phenyl]methanols, which in turn are treated with a catalytic amount of
concentrated hydriodic acid to afford the corresponding 1,3-diaryl-2-methoxyin-
denes in reasonable yields.
Keywords: Benzyl cations, hydriodic acid, indenes, 2-lithiostyrenes
In a previous article, we reported that isochromenes could be obtained by
hydriodic acid–catalyzed cyclization of 2-(2-methoxyvinyl)benzyl alcohol
derivatives, which were prepared by treating 2-(2-methoxyvinyl)
phenyllithiums with aliphatic aldehydes and ketones.[1] In this article,
we report a convenient method for the preparation of 1,3-diaryl-2-
methoxyindenes 5 from 1-(1-aryl-2-methoxyvinyl)-2-bromobenzenes 1
in two steps. We found that the reaction of 2-(1-aryl-2-methoxyvinyl)
Received October 1, 2008.
Address correspondence to Kazuhiro Kobayashi, Division of Applied
Chemistry, Department of Chemistry and Biotechnology, Graduate School of
Engineering, Tottori University, 4-101 Koyama minami, Tottori 680-8552, Japan.
E-mail: kkoba@chem.tottori-u.ac.jp
2866

Synthesis of 1,3-Diaryl-2-methoxyindenes
2867
phenyllithiums, generated in situ by treating 1 with butyllithium, with
aromatic aldehydes gave aryl[2-(1-aryl-2-methoxyvinyl)phenyl]methanols
2, which in turn were treated with a catalytic amount of concentrated
hydriodic acid to afford 1,3-diaryl-2-methoxyindenes 5. Recently, indene
derivatives have attracted much interest for synthesis[2] because of their
clinically useful biological activities.[3] However, there had been no
reported examples of the synthesis of 2-alkoxyindenes starting with com-
pounds other than 2-indanone[4] until recently, when Nakamura et al.
reported a synthesis of 2,3-dialkoxyindenes from 2-alkynylbenzaldehyde
dialkyl acetals utilizing palladium- and platinum-catalyzed reactions.[5]
The preparation of 1,3-diaryl-2-methoxyindenes 5 from 1-(1-aryl-
2-methoxyvinyl)-2-bromobenzenes 1 was conducted as illustrated in
Scheme 1. Thus, 2-(1-aryl-2-methoxyvinyl)phenyllithiums, which were
generated by bromine–lithium exchange between 1 and butyllithium in
diethyl ether at 0ꢀC, were allowed to react with aromatic aldehydes at
the same temperature. Fair to good yields of aryl[2-(1-aryl-2-methoxyvi-
nyl)phenyl]methanols 2 were obtained after the usual aqueous workup,
followed by purification using preparative thin-layer chromatography
(TLC) on silica gel, as summarized in Table 1. These products were
isolated by silica-gel preparative TLC as mixtures of stereoisomers, of
which ratios and stereochemistries were determined on the basis of their
1H NMR spectra (see the Experimental section).
The isomeric mixtures of the benzhydrol derivatives 2 thus obtained
were treated with a catalytic amount of concentrated hydriodic acid in
acetonitrile to generate the benzylic cation intermediates 3, which under-
went cyclization to yield the 2-methoxyindenes 5 through the other
benzylic cation intermediates 4. The presence of the aryl group is thought
to facilitate the generation of these intermediates via protolytic dehydra-
tion of the hydroxy group rather than the formation of isochromenes
via protonation to the methoxyvinyl moiety.[1] Reaction conditions as well
Scheme 1. Preparation of 1,3-diaryl-2-methoxyindenes from 1-(1-aryl-2-methoxy-
vinyl)-2-bromobenzenes.

2868
K. Kobayashi et al.
Table 1. Preparation of 1,3-diaryl-2-methoxyindenes 3
Entry
Ar
2 (Yield, %)a Temperature
Time
3 (Yield, %)a
1
2
3
4
5
6
7
8
9
Ph
m-Tol
p-Tol
4-t-BuC6H4
4-FC6H4
4-ClC6H4
3-MeOC6H4
4-MeOC6H4
Biphenyl-4-yl
2a (73)
2b (76)
2c (77)
2d (78)
2e (75)
2f (75)
2g (82)
2h (74)
2i (75)
0ꢀC
0ꢀC
0ꢀC
0ꢀC
0ꢀC
0ꢀC
rt
10 min
10 min
10 min
1 h
1 h
2 h
30 min
5 min
30 min
3a (50)
3b (55)
3c (51)
3d (50)
3e (33)
3f (35)
3g (30)
3h (51)
3i (46)
0ꢀC
0ꢀC
aIsolated yields.
as results of these indene-forming reactions are also summarized in
Table 1. The reactions generally proceeded smoothly at 0ꢀC, except that
compound 2 g (Ar ¼ 3-methoxyphenyl; entry 7) required a greater reaction
temperature (room temperature). Although the yields of the desired
2-methoxyindenes 5 were generally moderate to fair, the substrates carry-
ing aryl groups, such as 4-fluorophenyl (2e; entry 5), 4-chlorophenyl (2f;
entry 6), and 3-methoxyphenyl (2g; entry 7) gave lesser yields of the corre-
sponding 2-methoxyindenes than the others. These results suggest that the
inductive effect of these substituents on the benzene nucleus presumably
instabilizes the corresponding benzyl cationic intermediates 3 and=or 4.
When (4-methylphenyl)[2-(2-methoxy-1-phenylethenyl)phenyl]metha-
nol (6), which was obtained from 1a and 4-methylbenzaldehyde, was
subjected to the treatment with concentrated hydriodic acid under condi-
tions similar to those described previously for the preparation of 5 from
2, the regioisomers, 2-methoxy-1-(4-methylphenyl)-3-phenylindene (7a),
and 2-methoxy-3-(4-methylphenyl)-1-phenylindene (7b) were obtained in
moderate yields as a ca. 1:1 mixture, as judged by its 1H NMR spectrum.
The results of these reactions are illustrated in Scheme 2.
Scheme 2. Formation of regioisomeric 2-methoxy-1(or 3)-(4-methylphenyl)-3-
(or 1)-phenylindenes.

Synthesis of 1,3-Diaryl-2-methoxyindenes
2869
In conclusion, we have demonstrated that 1,3-diaryl-2-methoxyindenes
could be prepared from 1-(1-aryl-2-methoxyvinyl)-2-bromobenzene in two
steps. Because the method employs readily available starting materials
and is experimentally simple, it may be of value in organic synthesis.
EXPERIMENTAL
The melting points were determined on a Laboratory Devices Mel-Temp II
melting-point apparatus and are uncorrected. The infrared (IR) spectra were
recorded on a Shimadzu Fourier transform (FT)–IR-8300 spectrometer. The
1H NMR spectra were determined in CDCl3 using SiMe4 as an internal refer-
ence with a Jeol ECP500 FT NMR spectrometer operating at 500 MHz. The
13C NMR spectrum was determined in CDCl3 using tetramethylsilane
(TMS) as an internal reference with a Jeol ECP500 FT NMR spectrometer
operating at 125 MHz. Low-resolution mass spectra (EI, 70 eV) were mea-
sured by a Jeol JMS-AX505 HA spectrometer. Thin-layer chromatography
(TLC) was carried out on Merck Kieselgel 60 PF254. Column chromatogra-
phy was performed using Merck Kieselgel 60 (0.063–0.200mm).
Starting Materials
1-Bromo-2-(2-methoxy-1-phenylethenyl)benzene (1a) and 1-bromo-2-[1-
(4-chlorophenyl)-2-methoxyethenyl]benzene (1f) were prepared by our pre-
viously reported method.[6] 2-Bromophenyl(3-methylphenyl)methanone,[7]
2-bromophenyl(4-methylphenyl)methanone,[7] 2-bromophenyl(4-fluoro
phenyl)methanone,[8] 2-bromophenyl(4-methoxyphenyl) methanone,[9]
and (biphenyl-4-yl)(2-bromophenyl)methanone[10] were prepared accord-
ing to the appropriate reported methods. All other chemicals used in this
study were commercially available.
1-Bromo-2-[1-(3-methylphenyl)-2-methoxyethenyl]benzene (1b)
This compound was prepared by treatment of 2-bromophenyl
(3-methylphenyl)methanone[7] with (methoxymethylene)triphenylpho-
sphorane in THF at 0ꢀC in 81% yield; a mixture of stereoisomers
(E:Z ¼ ca. 6:4). An analytical specimen of each isomer was obtained by
fractional column chromatography on silica gel. E-1a: a pale yellow oil;
Rf 0.55 (1:4 CH2Cl2–hexane); IR (neat) 1634 cmꢁ1 1H NMR d 2.29
;
(3H, s), 3.81 (3H, s), 6.23 (1H, s), 6.98 (1H, dd, J ¼ 7.8, 1.8 Hz),
7.15–7.20 (3H, m), 7.29–7.35 (3H, m), 7.59 (1H, dd, J ¼ 7.8, 0.9 Hz).

2870
K. Kobayashi et al.
Anal. calcd. for C16H15BrO: C, 63.38; H, 4.99. Found: C, 63.29; H, 5.00.
Z-1a: a white solid; mp 60–61ꢀC (hexane); IR (KBr) 1641 cmꢁ1; 1H NMR
d 2.29 (3H, s), 3.74 (3H, s), 6.66 (1H, s), 6.90 (1H, d, J ¼ 7.8 Hz), 6.94
(1H, s), 6.99 (1H, d, J ¼ 7.8 Hz), 7.14 (1H, t, J ¼ 7.8 Hz), 7.17 (1H,
ddd, J ¼ 7.8, 7.3, 1.8 Hz), 7.24 (1H, dd, J ¼ 7.8, 1.8 Hz), 7.33 (1H, ddd,
J ¼ 7.8, 7.3, 1.4 Hz), 7.64 (1H, dd, J ¼ 7.8, 1.4 Hz). Anal. calcd. for
C16H15BrO: C, 63.38; H, 4.99. Found: C, 63.34; H, 5.22.
1-Bromo-2-[1-(4-methylphenyl)-2-methoxyethenyl]benzene (1c)
This compound was prepared by treatment of 2-bromophenyl
(4-methylphenyl)methanone[7] with (methoxymethylene)triphenylpho-
sphorane in tetrahydrofuran (THF) at 0ꢀC in 71% yield: a mixture of
stereoisomers (E:Z ¼ ca. 6:4); a pale-yellow oil; Rf 0.31 (1:3 CH2Cl2–
1
hexane); IR (neat) 1639 cmꢁ1; H NMR d 2.31 (3H, s), 3.73 (1.2H, s),
3.80 (1.8H, s), 6.21 (0.6H, s), 6.64 (0.4H, s), 7.00 (0.8H, d, J ¼ 8.7 Hz),
7.05–7.09 (2.2H, m), 7.15–7.35 (4H, m), 7.58 (0.6H, dd, J ¼ 7.3,
0.9 Hz), 7.64 (0.4H, dd, J ¼ 7.8, 1.4 Hz). Anal. calcd. for C16H15BrO:
C, 63.38; H, 4.99. Found: C, 63.36; H, 5.25.
2-Bromophenyl[4-(1,1-dimethylethyl)phenyl]methanol
This compound was prepared by the reaction of 2-bromobenzaldehyde
with 4-(1,1-dimethylethyl)phenylmagnesium bromide in THF at 0ꢀC in
86% yield: a colorless oil; Rf 0.28 (1:5 Et2O–hexane); IR (neat) 3308 cmꢁ1
;
1H NMR d 1.30 (9H, s), 2.29 (1H, d, J ¼ 3.2 Hz), 6.18 (1H, d, J ¼ 3.2 Hz),
7.14 (1H, ddd, J ¼ 7.8, 7.3, 1.8 Hz), 7.33 (2H, d, J ¼ 8.7 Hz), 7.35–7.37 (3H,
m), 7.53 (1H, d, J ¼ 7.8, 1.4 Hz), 7.63 (1H, dd, J ¼ 7.8, 1.8 Hz). Anal. calcd.
for C17H19BrO: C, 63.96; H, 6.00. Found: C, 63.75; H, 6.15.
2-Bromophenyl[4-(1,1-dimethylethyl)phenyl]methanone
This compound was prepared by the pyridinium chlorochromate (PCC)
oxidation of 2-bromophenyl[4-(1,1-dimethylethyl)phenyl]methanol in
1,2-dicloroethane at room temperature in 83% yield: a white solid; mp
1
71–72ꢀC (hexane); IR (KBr) 1668 cmꢁ1; H NMR d 1.34 (9H, s), 7.32
(1H, dd, J ¼ 7.8, 1.8 Hz), 7.34 (1H, ddd, J ¼ 7.8, 7.3, 1.8 Hz), 7.40 (1H,
ddd, J ¼ 7.8, 7.3, 1.4 Hz), 7.48 (2H, d, J ¼ 8.7 Hz), 7.65 (1H, dd,
J ¼ 7.8, 1.4 Hz), 7.75 (2H, d, J ¼ 8.7 Hz). Anal. calcd. for C17H17BrO:
C, 64.37; H, 5.40. Found: C, 64.09; H, 5.67.

Synthesis of 1,3-Diaryl-2-methoxyindenes
2871
1-Bromo-2-{1-[4-(1,1-dimethylethyl)phenyl]-2-methoxyethenyl}
benzene (1d)
This compound was prepared by treatment of 2-bromophenyl[4-(1,1-
dimethylethyl)phenyl]methanone with (methoxymethylene)triphenylpho-
sphorane in THF at 0ꢀC in 78% yield: a pale-yellow oil; Rf 0.35 (1:7
CH2Cl2–hexane); a mixture of stereoisomers (E:Z ¼ ca. 5:5). An analyti-
cal specimen of each isomer was obtained by fractional column chroma-
tography on silica gel. E-1d: a white solid; mp 72–74ꢀC (hexane); IR
1
(KBr) 1636 cmꢁ1; H NMR d 1.29 (9H, s), 3.80 (3H, s), 6.21 (1H, s),
7.17 (1H, ddd, J ¼ 7.8, 6.9, 2.3 Hz), 7.28–7.35 (6H, m), 7.59 (1H, d,
J ¼ 7.8 Hz). Anal. calcd. for C19H21BrO: C, 66.09; H, 6.13. Found: C,
65.85; H, 6.24. Z-1d: a colorless oil; Rf 0.41 (1:7 CH2Cl2–hexane); IR
1
(neat) 1638 cmꢁ1; H NMR d 1.29 (9H, s), 3.73 (3H, s), 6.65 (1H, s),
7.05 (2H, d, J ¼ 8.7 Hz), 7.17 (1H, ddd, J ¼ 7.8, 7.3, 1.4 Hz), 7.23 (1H,
dd, J ¼ 7.3, 1.4 Hz), 7.27 (2H, d, J ¼ 8.7 Hz), 7.32 (1H, td, J ¼ 7.3,
0.9 Hz), 7.64 (1H, d, J ¼ 7.8 Hz). Anal. calcd. for C19H21BrO: C, 66.09;
H, 6.13. Found: C, 65.93; H, 6.21.
1-Bromo-2-[1-(4-fluorophenyl)-2-methoxyethenyl]benzene (1e)
This compound was prepared by treatment of 2-bromophenyl
(4-fluorophenyl)methanone[8] with (methoxymethylene)triphenylpho-
sphorane in THF at 0ꢀC in 77% yield; a mixture of stereoisomers
(E:Z ¼ ca. 6:4). An analytical specimen of each isomer was obtained by
fractional column chromatography on silica gel. E-1e: a colorless oil;
Rf 0.69 (1:5 CH2Cl2–hexane); IR (neat) 1645 cmꢁ1 1H NMR d 3.81
;
(3H, s), 6.23 (1H, s), 6.95 (2H, dd, J ¼ 9.2, 8.7 Hz), 7.16–7.20 (1H, m),
7.31–7.36 (4H, m), 7.59 (1H, d, J ¼ 8.2 Hz). Anal. calcd. for C15H12BrFO:
C, 58.65; H, 3.94. Found: C, 65.54; H, 4.01. Z-1e: a white solid; mp
1
84–85ꢀC (hexane–Et2O); IR (KBr) 1641 cmꢁ1; H NMR d 3.74 (3H, s),
6.59 (1H, s), 6.94 (2H, t, J ¼ 8.7 Hz), 7.07 (2H, dd, J ¼ 8.7, 5.5 Hz),
7.17 (1H, ddd, J ¼ 7.8, 7.3, 1.8 Hz), 7.23 (1H, dd, J ¼ 7.8, 1.4 Hz), 7.33
(1H, dd, 7,8, 7.3, 1.4 Hz), 7.64 (1H, dd, J ¼ 7.8 and 1.8 Hz). Anal. calcd.
for C15H12BrFO: C, 58.65; H, 3.94. Found: C, 58.64; H, 4.17.
2-Bromophenyl(3-methoxyphenyl)methanol
This compound was prepared by the reaction of 2-bromobenzaldehyde
with 3-methoxyphenylmagnesium bromide in Et2O at 0ꢀC in 87% yield:
a pale-yellow oil; Rf 0.40 (1:3 AcOEt–hexane); IR (neat) 3368,

2872
K. Kobayashi et al.
1
1601 cmꢁ1; H NMR d 2.34 (1H, d, J ¼ 3.7 Hz), 3.79 (3H, s), 6.18 (1H,
d, J ¼ 3.7 Hz), 6.82 (1H, dd, J ¼ 8.2, 2.7 Hz), 6.97–6.99 (2H, m), 7.15
(1H, ddd, J ¼ 7.8, 7.3, 1.8 Hz), 7.25 (1H, dd, J ¼ 8.2, 7.8 Hz), 7.33
(1H, ddd, J ¼ 7.8, 7.3, 7.4 Hz), 7.54 (1H, dd, J ¼ 7.8, 1.4 Hz), 7.56 (1H,
dd, J ¼ 7.8, 1.8 Hz). Anal. calcd. for C14H13BrO2: C, 57.36; H, 4.47.
Found: C, 57.09; H, 4.67.
2-Bromophenyl(3-methoxyphenyl)methanone
This compound was prepared by the oxidation of (2-bromophenyl)
(3-methoxyphenyl)methanol with PCC in CH2Cl2 at room temperature
in 69% yield: a pale-yellow solid; mp 79–80ꢀC (hexane); IR (KBr)
1668 cmꢁ1
;
1H NMR d 3.86 (3H, s), 7.15 (1H, ddd, J ¼ 8.2, 2.7,
0.9 Hz), 7.25–7.29 (1H, dd, J ¼ 8.2, 7.8 Hz), 7.33–7.37 (3H, m),
7.40–7.45 (2H, m), 7.65 (1H, dd, J ¼ 7.8 and 0.9 Hz). Anal. calcd. for
C14H11BrO2: C, 57.76; H, 3.81. Found: C, 57.59; H, 3.95.
1-Bromo-2-[2-methoxy-1-(3-methoxyphenyl)ethenyl]benzene (1g)
This compound was prepared by treatment of 2-bromophenyl
(3-methoxyphenyl)methanone with (methoxymethylene)triphenylpho-
sphorane in THF at 0ꢀC in 62% yield: a mixture of stereoisomers;
(E:Z ¼ ca. 6:4). An analytical specimen of each isomer was obtained by
fractional column chromatography on silica gel. E-1g: a colorless oil;
1
Rf 0.32 (1:3 CH2Cl2–hexane); IR (neat) 1638, 1603 cmꢁ1; H NMR d
3.76 (3H, s), 3.82 (3H, s), 6.24 (1H, s), 6.73 (1H, ddd, J ¼ 8.2, 2.7,
0.9 Hz), 6.91 (1H, ddd, J ¼ 7.8, 1.8, 0.9 Hz), 7.03 (1H, J ¼ 2.7, 1.8 Hz),
7.15–7.20 (2H, m), 7.28–7.32 (2H, m), 7.59 (1H, dd, J ¼ 7.8, 0.9 Hz).
Anal. calcd. for C16H15BrO2: C, 60.21; H, 4.74. Found: C, 60.04; H,
4.93. Z-1g: a colorless oil; Rf 0.25 (1:3 CH2Cl2–hexane); IR (neat) 1634
1
and 1607 cmꢁ1; H NMR (500 MHz, CDCl3) d 3.74 (3H, s), 3.76 (3H,
s), 6.65 (1H, dd, J ¼ 2.3 and 1.8 Hz), 6.69 (1H, s), 6.71–6.74 (2H, m),
7.15–7.18 (2H, m), 7.25 (1H, ddd, J ¼ 7.8, 7.3, and 1.8 Hz), 7.32 (1H,
ddd, J ¼ 7.8, 7.3, and 1.4 Hz), 7.63 (1H, dd, J ¼ 7.8 and 1.4 Hz). Anal.
calcd. for C16H15BrO2: C, 60.21; H, 4.74. Found: C, 60.06; H, 4.89.
1-Bromo-2-[2-methoxy-1-(4-methoxyphenyl)ethenyl]benzene (1h)
This compound was prepared by treatment of 2-bromophenyl(4-metho
xyphenyl)methanone[9] with (methoxymethylene)triphenylphosphorane

Synthesis of 1,3-Diaryl-2-methoxyindenes
2873
in THF at 0ꢀC in 72% yield; a mixture of stereoisomers (E:Z ¼ ca. 5:5); a
pale-yellow oil; Rf 0.31 (1:3 CH2Cl2–hexane); IR (neat) 1645, 1607 cmꢁ1
;
1H NMR d 3.72 (1.5H, s), 3.778 (1.5H, s), 3.784 (1.5H, s), 3.80 (1.5H, s),
6.17 (0.5H, s), 6.57 (0.5H, s), 6.80 (1H, d, J ¼ 9.2 Hz), 6.83 (1H, d,
J ¼ 8.7 Hz), 7.04 (1H, d, J ¼ 8.7 Hz), 7.14–7.19 (1H, m), 7.24 (0.5H,
ddd, J ¼ 7.8, 7.3, 1.4 Hz), 7.30–7.34 (2.5H, m), 7.59 (0.5H, d, J ¼ 7.8 Hz),
7.64 (0.5H, d, J ¼ 7.3 Hz). Anal. calcd for C16H15BrO2: C, 60.21; H, 4.74.
Found: C, 60.12; H, 4.78.
4-[1-(2-Bromophenyl)-2-methoxyethenyl]biphenyl (1i)
This compound was prepared by treatment of (biphenyl-4-yl)
(2-bromophenyl)methanone[10] with (methoxymethylene)triphenylpho-
sphorane in THF at 0ꢀC in 74% yield as a mixture of stereoisomers
(E:Z ¼ ca. 6:4). An analytical specimen of each isomers was isolated by
fractional column chromatography on silica gel (1:3 CH2Cl2–hexane).
1
E-1i: a white solid; mp 111–112ꢀC (hexane); IR (KBr) 1634 cmꢁ1; H
NMR d 3.85 (3H, s), 6.28 (1H, s), 7.20 (1H, td, J ¼ 7.8, 2.3 Hz),
7.29–7.36 (3H, m), 7.41 (2H, t, J ¼ 7.8 Hz), 7.45 (2H, d, J ¼ 8.7 Hz),
7.52 (2H, d, J ¼ 8.7 Hz), 7.59 (2H, d, J ¼ 7.8 Hz), 7.62 (1H, d, J ¼ 7.8 Hz).
Anal. calcd. for C21H17BrO: C, 69.05; H, 4.69. Found: C, 69.03; H, 4.94.
1
Z-1i: a white solid; mp 110–112ꢀC (hexane); IR (KBr) 1634 cmꢁ1; H
NMR d 3.77 (3H, s), 6.75 (1H, s), 7.18–7.21 (3H, m), 7.28 (1H, dd,
J ¼ 7.8, 1.8 Hz), 7.31 (1H, t, J ¼ 7.3 Hz), 7.35 (1H, ddd, J ¼ 7.8, 7.3,
1.4 Hz), 7.41 (2H, dd, J ¼ 7.8, 7.3 Hz), 7.49 (2H, d, J ¼ 8.2 Hz), 7.57
(2H, d, J ¼ 7.8 Hz), 7.67 (1H, dd, J ¼ 7.8, 1.4 Hz). Anal. calcd. for
C21H17BrO: C, 69.05; H, 4.69. Found: C, 69.05; H, 4.92.
Typical Procedure for Preparation of 2-Vinylbenzyl
Alcohol Derivatives 2
[2-(2-Methoxy-1-phenylethenyl)phenyl]phenylmethanol (2a)
n-BuLi (1.6 M in hexane; 0.82 mmol) was added to a stirred solution of
1a (0.20 g, 0.68 mmol) in Et2O (6 mL) at 0ꢀC. After 1 h, PhCHO (87 mg,
0.82 mmol) was added, and stirring continued for an additional 30 min at
the same temperature. Water (15 mL) was added, and organic materials
were extracted with Et2O three times (10 mL each). The combined
extracts were washed with brine, dried over anhydrous Na2SO4, and eva-
porated. The residue was purified by preparative TLC on silica gel to give
2a (0.15 g, 73%): a mixture of stereoisomers (E:Z ¼ ca. 7:3); a pale-yellow

2874
K. Kobayashi et al.
1
oil; Rf 0.22 (1:5 AcOEt–hexane); IR (neat) 3445, 1634 cmꢁ1; H NMR d
1.92 (0.7H, s), 3.64 (2.1H, br s), 3.66 (0.9H, s), 4.96 (0.3H, br s), 5.83
(0.7H, s), 5.935 (0.3H, s), 5.936 (0.7H, s), 6.76 (0.3H, s), 7.14–7.31
(11.2H, m), 7.37 (0.7H, ddd, J ¼ 7.8, 7.3, 1.4 Hz), 7.42 (1.4H, dd,
J ¼ 7.3, 1.4 Hz), 7.54 (0.7H, d, J ¼ 7.8 Hz). Anal. calcd. for C22H20O2:
C, 83.51; H, 6.37. Found: C, 83.67; H, 6.47.
{2-[2-Methoxy-1-(3-methylphenyl)ethenyl]phenyl}(3-methylphenyl)-
methanol (2b)
A yellow oil; a mixture of stereoisomers (E:Z ¼ ca. 6:4); Rf 0.17 (1:11
1
AcOEt–hexane); IR (neat) 3417, 1634 cmꢁ1; H NMR d 1.90 (0.6H, s),
2.27 (3.6H, s), 2.29 (2.4H, s), 3.66 (3H, s), 4.68 (0.4H, br s), 5.82 (0.6H,
s), 5.91 (0.4H, br s), 5.96 (0.6H, s), 6.74 (0.4H, s), 6.94–7.02 (4H, m),
7.11–7.18 (4H, m), 7.21–7.37 (3.6H, m), 7.53 (0.4H, d, J ¼ 7.8 Hz). Anal.
calcd. for C24H24O2: C, 83.69; H, 7.02. Found: C, 83.42; H, 7.11.
{2-[2-Methoxy-1-(4-methylphenyl)ethenyl]phenyl}(4-
methylphenyl)methanol (2c)
A yellow oil; a mixture of stereoisomers (E:Z ¼ ca. 7:3); Rf 0.31 (1:6
1
AcOEt–hexane); IR (neat) 3428, 1634 cmꢁ1; H NMR d 1.87 (0.7H, s),
2.30 (2.1H, s), 2.31 (2.1H, s), 2.32 (1.8H, br s), 3.64 (3H, s), 4.94 (0.3H,
br s), 5.81 (0.7H, s), 5.91 (1H, br s), 6.72 (0.3H, br s), 7.03–7.10 (6H,
m), 7.19–7.22 (1.4H, m), 7.25–7.30 (3.2H, m), 7.34 (0.7H, ddd, J ¼ 7.8,
7.3, 1.4 Hz), 7.52 (0.7H, d, J ¼ 7.8 Hz). Anal. calcd. for C24H24O2: C,
83.69; H, 7.02. Found: C, 83.53; H, 7.12.
[4-(1,1-Dimethylethyl)phenyl](2-{1-[4-(1,1-dimethylethyl)phenyl]-2-
methoxyethenyl}phenyl)methanol (2d)
A pale-yellow oil; a mixture of stereoisomers (E:Z ¼ ca. 6:4); Rf 0.25 (1:7
AcOEt–hexane). An analytical specimen of each isomer was isolated by
fractional column chromatography on silica gel. E-2d: a pale-yellow oil;
Rf 0.29 (1:7 AcOEt–hexane); IR (neat) 3406, 1636 cmꢁ1; 1H NMR d 1.27
(9H, s), 1.29 (9H, s), 1.90 (1H, d, J ¼ 2.7 Hz), 3.60 (3H, s), 5.83 (1H, d,
J ¼ 2.7 Hz), 5.84 (1H, s), 7.12 (2H, d, J ¼ 8.2 Hz), 7.21 (1H, dd, J ¼ 7.8,
1.4 Hz), 7.26–7.29 (5H, m), 7.34 (2H, d, J ¼ 8.2 Hz), 7.36 (1H, dd,
J ¼ 7.8, 7.3 Hz), 7.59 (1H, d, J ¼ 7.8 Hz). Anal. calcd. for C30H36O2: C,
84.07; H, 8.47. Found: C, 84.01; H, 8.19. Z-2d: a pale-yellow oil; Rf
1
0.21 (1:7 AcOEt–hexane); IR (neat) 3423, 1638 cmꢁ1; H NMR d 1.29

Synthesis of 1,3-Diaryl-2-methoxyindenes
2875
(9H, s), 1.30 (9H, s), 3.60 (3H, br s), 4.56 (1H, br s), 5.91 (1H, br s), 6.70
(1H, br s), 7.07 (2H, d, J ¼ 8.2 Hz), 7.22–7.31 (10H, m). Anal. calcd. for
C30H36O2: C, 84.07; H, 8.47. Found: C, 84.02; H, 8.30.
4-Fluorophenyl{2-[1-(4-fluorophenyl)-2-methoxyethenyl]phenyl}
methanol (2e)
A yellow oil; a mixture of stereoisomers (E:Z ¼ ca. 7:3); Rf 0.30 (1:6
1
AcOEt–hexane); IR (neat) 3408, 1636 cmꢁ1; H NMR d 1.92 (0.7H, d,
J ¼ 3.7 Hz), 3.66 (3H, s), 4.67 (0.3H, br s), 5.77 (0.7H, d, J ¼ 3.7 Hz),
5.87 (0.3H, br s), 5.92 (0.7H, s), 6.67 (0.3H, br s), 6.90–6.97 (4H, m),
7.07 (0.6H, dd, J ¼ 9.2, 5.5 Hz), 7.13 (1.4H, dd, J ¼ 8.7, 5.5 Hz),
7.21–7.25 (2H, m), 7.29–7.41 (3.3H, m), 7.55 (0.7H, d, J ¼ 7.3 Hz). Anal.
calcd. for C22H18F2O2: C, 74.99; H, 5.15. Found: C, 74.96; H, 5.24.
4-Chlorophenyl{2-[-1-(4-chlorophenyl)-2-methoxyethenyl]phenyl}
methanol (2f)
A yellow oil; a mixture of stereoisomers (E:Z ¼ ca. 8:2); Rf 0.29 (1:3
1
AcOEt–hexane); IR (neat) 3408, 1636 cmꢁ1; H NMR d 1.91 (0.8H, s),
3.68 (3H, br s), 4.71 (0.2H, br s), 5.74 (0.8H, s), 5.82 (0.2H, s), 5.96
(0.8H, s), 6.74 (0.2H, br s), 7.03 (0.4H, d, J ¼ 8.7 Hz), 7.09 (1.6H, d,
J ¼ 8.2 Hz), 7.19–7.23 (6H, m), 7.30–7.54 (4H, m). Anal. calcd. for
C22H18Cl2O2: C, 68.58; H, 4.71. Found: C, 68.42; H, 4.63.
{2-[2-Methoxy-1-(3-methoxyphenyl)ethenyl]phenyl}(3-methoxyphenyl)-
methanol (2g)
A yellow oil; a mixture of stereoisomers (E:Z ¼ ca. 6:4); Rf 0.14 (1:5
AcOEt–hexane); IR (neat) 3474, 1634, 1601 cmꢁ1 1H NMR d 1.88
;
(0.6H, br s), 3.67 (1.8H, s), 3.74 (5.4H, s), 3.74 (1.8H, s), 4.63 (0.4H,
br s), 5.82 (0.6H, s), 5.91 (0.4H, s), 5.98 (0.6H, s), 6.68–6.80 (4.4H, m),
6.86–6.94 (1.4H, m), 7.08 (0.6H, dd, J ¼ 2.3, 1.8 Hz), 7.14–7.36 (5.4H,
m), 7.51 (0.6H, d, J ¼ 6.9 Hz). Anal. calcd. for C24H24O4: C, 76.57; H,
6.43. Found: C, 76.28; H, 6.19.
{2-[2-Methoxy-1-(4-methoxyphenyl)ethenyl]phenyl}
(4-methoxyphenyl)methanol (2h)
A yellow oil; a mixture of stereoisomers (E:Z ¼ ca. 6:4); Rf 0.29 (1:6
AcOEt–hexane); IR (neat) 3479, 1634, 1609 cmꢁ1 1H NMR d 1.88
;

2876
K. Kobayashi et al.
(0.6H, s), 3.64 (3H, s), 3.76 (1.8H, s), 3.779 (3H, s), 3.783 (1.2H, s), 4.63
(0.4H, br s), 5.79 (0.6H, s), 5.85 (0.6H, s), 5.89 (0.4H, br s), 6.64 (0.4H, br
s), 6.77 (2H, d, J ¼ 9.2 Hz), 6.81 (2H, d, J ¼ 9.2 Hz), 7.05 (0.8H, d,
J ¼ 8.7 Hz), 7.11 (1.2H, d, J ¼ 8.7 Hz), 7.20–7.22 (2H, m), 7.28–7.40
(1.8H, m), 7.32 (1.2H, d, J ¼ 8.7 Hz), 7.36 (0.4H, ddd, J ¼ 7.8, 7.3,
1.4 Hz), 7.58 (0.6H, dd, J ¼ 7.8, 7.3 Hz). Anal. calcd. for C24H24O4: C,
76.57; H, 6.43. Found: C, 76.31; H, 6.69.
(Bipheny-4-yl){2-[1-(biphenyl-4-yl)-2-methoxyethenyl]
phenyl}methanol (2i)
A mixture of stereoisomers (E:Z ¼ ca. 5:5). An analytical specimen of
each isomer was isolated by column chromatography on silica gel (1:5
AcOEt–hexane). E-2i: a yellow oil; Rf 0.29; IR (neat) 3439, 1634 cmꢁ1
;
1H NMR d 2.01 (1H, d, J ¼ 3.6 Hz), 3.69 (3H, s), 5.92 (1H, d, J ¼ 3.6 Hz),
6.01 (1H, s), 7.26–7.38 (3H, m), 7.30–7.34 (3H, m), 7.38–7.56 (15H, m),
7.67 (1H, d, J ¼ 7.8 Hz). Anal. calcd. for C34H28O2: C, 87.15; H, 6.02.
Found: C, 87.12; H, 6.19. Z-2i: a pale-yellow solid; mp 56–59ꢀC (pen-
1
tane); IR (KBr) 3420, 1626 cmꢁ1; H NMR d 3.69 (3H, br s), 4.75 (1H,
br s), 5.99 (1H, br s), 6.83 (1H, br s), 7.21 (2H, d, J ¼ 8.2 Hz),
7.32–7.60 (20H, m). Anal. calcd. for C34H28O2: C, 87.15; H, 6.02. Found:
C, 86.91; H, 6.16.
Typical Procedure for the Preparation of 2-Methoxyindene
Derivatives 5
2-Methoxy-1,3-diphenylindene (5a)
A drop of conc. HI was added to a stirred solution of 2a (0.11 g,
0.36 mmol) in MeCN (5 mL) at 0ꢀC. After 10 min, saturated aqueous
NaHCO3 (20 mL) was added, and the organic solvent was evaporated.
The resulting mixture was extracted with Et2O three times (10 mL each),
and the combined extracts were dried over anhydrous K2CO3. After
evaporation of the solvent, the residue was purified by preparative
TLC on silica gel to give 4a (55 mg, 50%): a pale-yellow oil; Rf 0.48
(1:8 AcOEt–hexane); IR (neat) 1622 cmꢁ1 1H NMR d 3.61 (3H, s),
;
4.75 (1H, s), 7.02 (1H, td, J ¼ 7.3, 1.4 Hz), 7.09 (1H, d, J ¼ 7.3 Hz),
7.18 (1H, dd, J ¼ 7.8, 7.3 Hz), 7.24–7.28 (4H, m), 7.31–7.35 (3H, m),
7.46 (2H, dd, J ¼ 7.8, 7.3 Hz), 7.63 (2H, dd, J ¼ 7.8, 1.4 Hz); MS m=z
298 (Mþ, 100). Anal. calcd. for C22H18O: C, 88.56; H, 6.08. Found:
C, 88.28; H, 6.10.

Synthesis of 1,3-Diaryl-2-methoxyindenes
2877
2-Methoxy-1,3-bis(3-methylphenyl)indene (5b)
A pale-yellow oil; Rf 0.33 (1:19 CH2Cl2–hexane); IR (neat) 1622,
1
1606 cmꢁ1; H NMR d 2.32 (3H, s), 2.42 (3H, s), 3.61 (3H, s), 4.69
(1H, s), 7.00 (1H, t, J ¼ 7.3 Hz), 7.05–7.09 (4H, m), 7.14–7.24 (4H, m),
7.34 (1H, dd, J ¼ 7.8, 7.3 Hz), 7.42–7.44 (2H, m); 13C NMR d 21.46,
21.55, 53.35, 58.91, 118.46, 118.55, 123.29, 123.55, 124.96, 126.30,
126.86, 127.70, 127.93, 128.17, 128.33, 128.82, 129.83, 133.65, 137.80,
138.57, 138.62, 141.83, 144.02, 162.46; MS m=z 326 (Mþ, 100). Anal.
calcd. for C24H22O: C, 88.31; H, 6.79. Found: C, 88.37; H, 6.97.
2-Methoxy-1,3-bis(4-methylphenyl)indene (5c)
A pale-yellow oil; Rf 0.53 (1:9 CH2Cl2–hexane); IR (neat) 1622, 1609 cmꢁ1
;
1H NMR d 2.32 (3H, s), 2.41 (3H, s), 3.62 (3H, s), 4.69 (1H, s), 7.00 (1H, t,
J ¼ 7.3 Hz), 7.07 (1H, d, J ¼ 7.3 Hz), 7.11–7.18 (5H, m), 7.23 (1H, d,
J ¼ 7.3 Hz), 7.26 (2H, d, J ¼ 7.8 Hz), 7.51 (2H, d, J ¼ 7.8 Hz); MS m=z
326 (Mþ, 100). Anal. calcd. for C24H22O: C, 88.31; H, 6.79. Found: C,
88.46; H, 6.87.
1,3-Bis[4-(1,1-dimethylethyl)phenyl]-2-methoxyindene (5d)
A yellow oil; Rf 0.35 (1:9 CH2Cl2–hexane); IR (neat) 1624, 1603 cmꢁ1
;
1H NMR d 1.29 (9H, s), 1.37 (9H, s), 3.62 (3H, s), 4.73 (1H, s), 7.00
(1H, t, J ¼ 7.3 Hz), 7.10 (1H, d, J ¼ 7.3 Hz), 7.17 (1H, dd, J ¼ 7.8,
7.3 Hz), 7.19 (2H, d, J ¼ 8.2 Hz), 7.30 (1H, d, J ¼ 7.8 Hz), 7.31 (2H, d,
J ¼ 8.2 Hz), 7.47 (2H, d, J ¼ 8.7 Hz), 7.58 (2H, d, J ¼ 8.2 Hz); MS m=z
410 (Mþ, 100). Anal. calcd. for C30H34O: C, 87.76; H, 8.35. Found: C,
87.75; H, 8.35.
1,3-Bis(4-fluorophenyl)-2-methoxyindene (5e)
A pale-yellow oil; Rf 0.40 (1:8 CH2Cl2–hexane); IR (neat) 1622, 1601 cmꢁ1
;
1H NMR d 3.60 (3H, s). 4,71 (1H, s), 7.00–7.07 (4H, m), 7.15 (2H, t,
J ¼ 8.7 Hz), 7.19–7.23 (4H, m), 7.58 (2H, dd, J ¼ 8.7, 5.5 Hz); MS m=z
334 (Mþ, 100). Anal. calcd. for C22H16F2O: C, 79.03; H, 4.82. Found:
C, 79.03; H, 4.55.
1,3-Bis(4-chlorophenyl)-2-methoxyindene (5f)
A colorless oil; Rf 0.28 (1:20 AcOEt–hexane); IR (neat) 1622, 1601 cmꢁ1
1H NMR d 3.60 (3H, s), 4.71 (1H, s), 7.03–7.07 (2H, m), 7.18–7.21
;

2878
K. Kobayashi et al.
(4H, m), 7.30 (2H, d, J ¼ 8.2 Hz), 7.43 (2H, d, J ¼ 8.2 Hz), 7.55 (2H, d,
J ¼ 8.2 Hz); MS m=z 366 (Mþ, 100). Anal. calcd. for C22H16Cl2O: C,
71.95; H, 4.39. Found: C, 71.79; H, 4.59.
2-Methoxy-1,3-bis(3-methoxyphenyl)indene (5g)
Preparation of this compound was carried out at room temperature: a
pale-yellow oil; Rf 0.24 (1:11 AcOEt–hexane); IR (neat) 1625, 1606 cmꢁ1
;
1H NMR d 3.63 (3H, s), 3.78 (3H, s), 3.86 (3H, s), 4.70 (1H, s),
6.79–6.81 (2H, s), 6.87–6.90 (2H, m), 7.01 (1H, td, J ¼ 7.3, 1.4 Hz), 7.10
(1H, d, J ¼ 7.3 Hz), 7.16–7.25 (5H, m), 7.37 (1H, dd, J ¼ 8.2, 7.8 Hz);
MS m=z 358 (Mþ, 100). Anal. calcd. for C24H22O3: C, 80.42; H, 6.19.
Found: C, 80.19; H, 6.05.
2-Methoxy-1,3-bis(4-methoxyphenyl)indene (5h)
A pale-yellow oil; Rf 0.30 (1:9 AcOEt–hexane); IR (neat) 1625,
1
1606 cmꢁ1; H NMR d 3.61 (3H, s), 3.79 (3H, s), 3.86 (3H, s), 4.68 (1H,
s), 6.86 (2H, d, J ¼ 8.7 Hz), 6.99–7.03 (3H, m), 7.07 (1H, d, J ¼ 7.3 Hz),
7.16–7.18 (3H, m), 7.23 (1H, d, J ¼ 7.8 Hz), 7.55 (2H, d, J ¼ 8.7 Hz); MS
m=z 358 (Mþ, 16), 252 (100). Anal. calcd. for C24H22O3: C, 80.42; H,
6.19. Found: C, 80.18; H, 6.29.
1,3-Bis(biphenyl-4-yl)-2-methoxyindene (5i)
A pale-yellow solid; mp 180–182ꢀC (hexane–CH2Cl2); IR (KBr) 1622,
1
1601 cmꢁ1; H NMR d 3.70 (3H, s), 4.83 (1H, s), 7.06 (1H, dd, J ¼ 7.8,
7.3 Hz), 7.15 (1H, d, J ¼ 7.8 Hz), 7.23 (1H, dd, J ¼ 7.8, 7.3 Hz),
7.32–7.38 (5H, m), 7.43 (2H, dd, J ¼ 7.8, 7.3 Hz), 7.47 (2H, dd, J ¼ 7.8,
7.3 Hz), 7.56 (2H, d, J ¼ 8.2 Hz), 7.58 (2H, d, J ¼ 8.7 Hz), 7.67 (2H, d,
J ¼ 8.2 Hz), 7.71 (2H, d, J ¼ 8.2 Hz), 7.75 (2H, d, J ¼ 8.2 Hz); 13C NMR
d 53.03, 59.01, 118.25, 118.70, 123.44, 123.79, 127.00, 127.03 (two over-
lapped C’s), 127.06 (two overlapped C’s), 127.23, 127.79, 128.23,
128.75, 128.79, 129.53, 132.72, 137.75, 139.71, 140.09, 140.77, 141.00,
141.76, 143.76, 162.76; MS m=z 450 (Mþ, 100). Anal. calcd. for
C34H26O: C, 90.63; H, 5.82. Found: C, 90.37; H, 6.11.
[2-(2-Methoxy-1-phenylethenyl)phenyl](4-methylphenyl)methanol (6)
This compound was prepared from 1 and 4-methylbenzaldehyde in a
manner similar to that described for the preparation of 2a: a mixture

Synthesis of 1,3-Diaryl-2-methoxyindenes
2879
of stereoisomers (E:Z ¼ ca. 7:3); a yellow oil; Rf 0.20 (1:5 AcOEt–
1
hexane); IR (neat) 3560, 3418, 1634 cmꢁ1; H NMR d 1.88 (0.7H, d,
J ¼ 3.7 Hz), 2.30 (2.1H, s), 2.31 (0.9H, s), 3.65 (3H, s), 4.65 (0.3H, br
s), 5.80 (0.7H, d, J ¼ 3.7 Hz), 5.90 (0.7H, br s), 5.94 (0.3H, s), 6.75
(0.3H, br s), 7.05 (2H, d, J ¼ 7.8 Hz), 7.09 (2H, d, J ¼ 7.8 Hz),
7.14–7.55 (9H, m). Anal. calcd. for C23H22O2: C, 83.60; H, 6.71. Found:
C, 83.32; H, 6.72.
2-Methoxy-1-(4-methylphenyl)-3-phenylindene (7a) and 2-Methoxy-3-
(4-methylphenyl)-1-phenylindene (8b)
This compound was prepared from 6 as described for the preparation of
5a: ca. 1:1 mixture; a yellow oil; Rf 0.52 (1:8 AcOEt–hexane); IR (neat)
1
1622 cmꢁ1; H NMR d 2.33 (1.5H, s), 2.41 (1.5H, s), 3.60 (1.5H, s),
3.61 (1.5H, s), 4.71 (0.5H, s), 4.73 (0.5H, s), 7.01 (1H, t, J ¼ 7.3 Hz),
7.08 (1H, d, J ¼ 7.3 Hz), 7.12–7.19 (3H, m), 7.23–7.28 (3H, m),
7.31–7.34 (2H, m), 7.45 (1H, t, J ¼ 7.3 Hz), 7.52 (1H, d, J ¼ 8.2 Hz),
7.63 (1H, dd, J ¼ 8.2, 1.4 Hz); MS m=z 312 (Mþ, 100). Anal. calcd. for
C23H20O: C, 88.43; H, 6.45. Found: C, 88.59; H, 6.56.
ACKNOWLEDGMENT
The authors thank Mrs. Miyuki Tanmatsu of this university for
determining mass spectra and performing combustion analyses.
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