InCl3 and ZrCl4 catalyzed regioselective reaction of 2,2′-dihydroxybiphenyl with terminal alkynes: synthesis of new dibenzo[d,f][1,3]dioxepines

Article abstract of DOI:10.1016/j.tet.2008.05.011

The regioselective reaction of 2,2′-dihydroxybiphenyl with terminal alkynes was found to be rapidly catalyzed by InCl₃ and ZrCl₄. The chemoselectivity of catalysts and alkynes for biphenol over water, together with the reaction mecha

Full text of DOI:10.1016/j.tet.2008.05.011

Tetrahedron 64 (2008) 6755–6759
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
InCl3 and ZrCl4 catalyzed regioselective reaction of 2,20-dihydroxybiphenyl
with terminal alkynes: synthesis of new dibenzo[d,f][1,3]dioxepines
*
Graziella Tocco , Michela Begala, Gabriele Meli, Gianni Podda
`
Dipartimento Farmaco Chimico Tecnologico, Universita degli Studi di Cagliari, via Ospedale 72, Cagliari 09124, Italy
a r t i c l e i n f o
a b s t r a c t
The regioselective reaction of 2,20-dihydroxybiphenyl with terminal alkynes was found to be rapidly
catalyzed by InCl3 and ZrCl4. The chemoselectivity of catalysts and alkynes for biphenol over water,
together with the reaction mechanism are discussed in details.
Article history:
Received 23 January 2008
Received in revised form 16 April 2008
Accepted 1 May 2008
Ó 2008 Elsevier Ltd. All rights reserved.
Available online 3 May 2008
Keywords:
Terminal alkynes
Dibenzo[d,f][1,3]dioxepine
Regioselectivity
Lewis acids
1. Introduction
additions of electron-deficient olefins and acetylenes with alcohols
or aminoacid-derived pronucleophiles7 and (3) the amine-cata-
Undoubtedly, the construction of new C–O bonds by addition of
oxygen nucleophiles to a C–C triple bond represents one of the
most useful methods to functionalize internal and terminal
alkynes.
lyzed hydroalkoxylation reactions of activated alkenes and
alkynes.8
In the present study, we report the InCl3 and ZrCl4 catalyzed
regioselective reaction of 2,20-dihydroxybiphenyl with terminal
alkynes, emphasizing the high chemoselectivity of the catalysts for
biphenol over water.
With this intention, several studies on the addition of water1 to
alkynes, also in the presence of alcohols,2 have been recently
reported in literature. As a consequence, a variety of catalysts for
this reaction have been extensively studied. The dichloro (diphos-
phine) platinum(II) complex/silver salt system,3 which led to ke-
tones with dry alcohols, seemed to be particularly interesting.
Another approach consists in the use of Pt(II)4 or Ir2b,5 complexes,
useful for the preparation of acetals in dry conditions.
2. Results and discussion
In recent years, we have focused our interest on the synthesis9
and mass spectrometric behaviour10 of dibenzo[d,f][1,3]dioxepines,
obtained from biphenols and a variety of carbonyl compounds. In
continuation of our research directed towards the development of
new catalytic reactions using Lewis acids, we found that, in the
presence of InCl3 or ZrCl4, terminal aliphatic and aromatic alkynes
easily reacted with 2,20-dihydroxybiphenyl (1), leading to 6,6-di-
alkyl or 6-alkyl-6-aryldibenzo dioxepine derivatives with excep-
tional regioselectivity.
In the beginning of our investigation, we studied the reactivity
of both terminal and internal alkynes. However, no product was
obtained using 3-hexyne (2a), dimethyl acetylenedicarboxylate
(2b), diphenyl acetylene (2c) or ethyl 2-hexynoate (2d), even with
higher temperatures, more catalyst or longer reaction times
(Scheme 1).
For these catalytic systems the presence of water is crucial in
order to maintain an interesting catalytic efficiency.2b Moreover,
these systems are almost chemoselective for water over alcohol,4,5
which decreases the regioselective formation of acetals.
Other interesting approaches involve the Michael addition re-
action, which is a versatile synthetic methodology for an efficient
coupling of electron poor acetylenes with a vast array of nucleo-
philes. Among the many methods, we report, as particularly in-
teresting, some recent works on: (1) the direct NaH-catalyzed
transformation of arylsulfonylalkynes into the acetals or thioacetals
of acetyl sulfones,6 (2) the phosphine-catalyzed conjugate
Conversely, the reaction took place smoothly when terminal
alkynes were employed (Scheme 2 and Tables 1 and 2).
* Corresponding author. Tel.: þ39 070 675 8711/8551; fax: þ39 070 675 8553.
E-mail address: toccog@unica.it (G. Tocco).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.05.011

6756
G. Tocco et al. / Tetrahedron 64 (2008) 6755–6759
Table 2
InCl3
Reaction of 2,20-dihydroxybiphenyl with terminal aromatic alkynes
or (10 mol %)
ZrCl4
Temp Time Prod. Yielda (%)
OH
OH
R
C
C
R1
No Product
Entry Alkyne
Cat.
(mol %) (ꢀC)
+
60 °C, 0.5 - 4 h
(min)
InCl3 ZrCl4
2a-d
1
2
3
4
5
6
7
8
9
10
PhC^CH
PhC^CH
PhC^CH
3-FPhC^CH
2-MePhC^CH
3-MePhC^CH
4-MePhC^CH
2-OMePhC^CH
2-OMePhC^CH
2-NO2PhC^CH
10
10
0
10
10
10
10
10
10
10
60
rt
35
90
90
90
45
45
45
45
90
90
(4e)
(4e)
(4e)
(4f)
(4g)
60
0
0
15
45
73
0
0
13
50
36
52
47
0
2a. R= -CH2CH3
2b. R=-COOCH3
2c. R= -Ph
;
R1= -CH2CH3
1
;
R1= -COOCH3
R1= -Ph
60
60
60
60
60
60
rt
;
;
2d. R=- CH2CH3
R1= -COOCH2CH3
(4h) 37
(4i)
(4j)
(4j)
(4k)
50
45
0
Scheme 1. Reaction of 2,2’-dihydroxybiphenyl with internal alkynes.
40b
0
0
C
CH
C
HC
C
O
C
O
R
11
10
60
90
(4l)
13
10
45
CH3
CH
InCl3
12
10
40b
40
(4m) 42
or (10 mol %)
ZrCl4
MeO
OH
OH
4a-m
a
R
C
C
H
+
Isolated yields.
Dichloromethane was used as solvent.
60 °C, 0.5-1 h
b
3a-m
O
C
H
alkynes were used, due to a major stability of the a-chlorostyrene
1
CH2R
O
derivatives. Compounds (5e), (5j) and (5m) were isolated (entries 1,
8 and 12 in Table 2) and their structures elucidated in order to
discern their role in the reaction mechanism (Scheme 3 and Fig. 1).
With this respect, 2,20-dihydroxybiphenyl (1) was allowed to
react with compound (5m), observing that, only in the presence of
InCl3 or ZrCl4, it converted promptly into 6-methyl-6-(6-methox-
ynaphthyl)dibenzo[d,f][1,3]dioxepine (4m) (Scheme 4). Derivatives
(5e) and (5j) exhibited the same behaviour.
3a. R= -(CH2)3CH3
3b. R=-(CH2)5CH3
3c. R= -C(CH3)2Cl
3d. R= -CH2OC6H5
3e. R= -C6H5
3f. R= -3-FC6H5
3l.R=
C CH
3g. R= -2-MeC6H5
3h. R= -3-MeC6H5
3i. R= -4-MeC6H5
3j. R= -2-OMeC6H5
3k. R= -2-NO2C6H5
3m. R=
OMe
Scheme 2. Reaction of 2,2’-dihydroxybiphenyl with terminal alkynes.
These experimental data suggest that the reaction effectively
proceeds successively through an
a-chloroalkene intermediate.
Moreover, it is evident that the Lewis acid is fundamental for the
formation of the intermediate and for the proceeding of the
reaction.
The experimental evidence seems to give credit also to the hy-
pothesis of a synergic interaction between the biphenol (1), the
alkynes (3a–m) and the catalyst. As a matter of fact, yields drasti-
cally decrease or the reaction did not take place at all, when the
components are added at different times.
On the basis of these experiments, we postulate the mechanism
presented in Scheme 5. The reaction presumably undergoes
a concerted six-membered transition state11 to form intermediates
(6) and (5). The 2-chloroalkene intermediate (5) is formed by
a Markovnikov addition of HCl derived from the nucleophilic in-
teraction between biphenol (1) and InCl3. The final product (4) is
afforded by the nucleophilic addition of compound (6) at 2-chloro-
alkene (5), which is rapidly followed by an intramolecular cycli-
zation, where an oxacarbenium ion represents the most likely
reactive state. Otherwise, 2-chloroalkene (5) might generate a vinyl
cation that could react with intermediate (6) to afford the final
product (4).
Our hypothesis was also confirmed with the aid of phenyl-
acetylene-d. The gas chromatogram reported in Figure 2 shows the
rapid formation, after only few minutes, of the deuterated 2-
chlorostyrene (m/z 139), which is rapidly transformed into the final
6-methyl-d1-6-phenyl dibenzo[d,f][1,3]dioxepine (m/z 289).
In particular, the best results have been obtained with phenyl-
acetylene (3e) and other electron rich aromatic alkynes such as
(3g–j), (3l), (3m), as evidenced in Tables 1 and 2. Moreover, we
observed that the maximum yields were isolated after not more
than 35–60 min and, apart from the reagents, the only product
obtained was the dibenzodioxepine derivative. The best results
have been achieved at 60 ꢀC; in fact, the reaction did not take place
at all at room temperature or without catalyst. Besides, no yield
enhancement was observed when the catalyst amount, the reaction
times or the temperature were altered. Furthermore, while com-
paring the effect of catalysts, we found that, InCl3 was slightly less
efficient than ZrCl4, in terms of isolated yields.
All the alkynes were used in excess in order to carry out the
reactions under homogeneous conditions, avoiding, with the ex-
ception of entries 10 and 12 in Table 2, the use of any solvent.
In order to better understand the regiochemistry of the reaction,
we explored the reaction mechanism by means of GC–MS analysis.
From the very beginning of the reaction, we observed the formation
of a 2-chloroalkene, which rapidly disappeared in favour of the
dibenzodioxepine. This was particularly evident when aromatic
Table 1
Reaction of 2,20-dihydroxybiphenyl with terminal aliphatic alkynes
Entry Alkyne
Cat. (mol %) Temp (ꢀC) Time (min) Prod. Yielda (%)
InCl3 ZrCl4
1
2
3
4
5
6
Bu–C^CH
10
10
0
60
rt
60
60
60
60
50
90
90
50
90
60
(4a)b 30
40
0
0
38
0
10
OCH3
H3CO
Bu–C^CH
Bu–C^CH
Hex–C^CH
ClCMe2C^CH 10
PhOCH2C^CH 10
(4a)
(4a)
0
0
10
(4b) 35
(4c)
(4d) 10
C
CH2
C
CH2
0
C
CH2
Cl
Cl
Cl
5j
5e
5m
a
Isolated yields.
Ref. 9a.
b
Scheme 3.
a
-Chlorostyrene derivatives isolated from entries 1, 8 and 12.

G. Tocco et al. / Tetrahedron 64 (2008) 6755–6759
6757
C
CH
H3CO
InCl2
Cl
O
InCl2
Cl
H3CO
O
H
C
CH2
R
3m
Cl
OH
OH
5m
C
C
CH2
HC
3
R
6
5
1
-Cl-
H3CO
C
CH2
Cl
m/z 218
O
O
InCl2
R
O
O
O
C
O
InCl2
R
R
CH3
C
C
CH3
CH3
4
Scheme 5. Proposed reaction mechanism.
We also studied the chemoselectivity of the catalysts. To this
end, the reactions reported in Scheme 2 were carried out in the
presence of water, observing that only the dibenzodioxepine de-
rivative was obtained as a final product. No trace of ketone was
evidenced, even when a stoichiometric amount of catalyst was used
(Scheme 6).
Figure 1. EIMS spectrum of 2-(1-chlorovinyl)-6-methoxynaphtalene (5m) obtained
from 2-ethynyl-6-methoxynaphtalene (3m).
In addition, we performed the reaction between phenyl-
acetylene (3e) and water, evidencing that InCl3 and ZrCl4 did not
catalyze, under our reaction conditions, the hydration of the
alkynes.1b
It is also known that phenols usually undergo regioselective
vinylation, especially with terminal alkynes, via C–H bond cleavage
in the presence of transition-metals12 or poor metal catalysts.13 It is
noteworthy that, during our experiments, we never found vinyl-
biphenol derivatives, which indicates that InCl3 or ZrCl4 did not
catalyze the alkenylation of 2,20-dihydroxybiphenyl (1).
Mass spectrometric studies on the gas-phase reactivity of aro-
matic alkynes towards 2,20-dihydroxybiphenyl are currently in
progress.
OCH3
O
C
O
CH3
CH2
Cl
Lewis
acid
C
OH
OH
+
4m
No
catalyst
No product
H3CO
5m
1
Scheme 4. Reaction between biphenol (1) and compound (5m).
O
C
O
CH2D
m/z 289
C
CHD
Cl
m/z 139
Figure 2. Gas chromatogram and mass spectra of deuterated 2-chlorostyrene intermediate and final 6-methyl-d1-6-phenyldibenzo[d,f][1,3]dioxepine, in the reaction between
compound (1) and labelled (3e).

6758
G. Tocco et al. / Tetrahedron 64 (2008) 6755–6759
3.2.2. 6-Hexyl-6-methyldibenzo[d,f][1,3]dioxepine (4b)
Yellow sticky oil. IR (NaCl):
3100, 1600, 1480, 1220 cmꢁ1
NMR (300 MHz, CDCl3): 6.89–7.40 (m, 8H), 2.10 (t, 2H), 1.90 (s,
3H), 1.25–1.33 (m, 8H), 0.78 (t, 3H) ppm. 13C NMR (300 MHz,
n
.
1H
O
C
O
R
d
CH3
CDCl3):
d
155.3, 133.2, 127.4, 114.9, 100.4, 38.3, 31.0, 22.8, 23.6, 18.7,
ꢃ
13.0 ppm. EIMS: m/z: 296 [Mþ ]. Anal. Calcd for C20H24O2: C 81.08, H
InCl3 or ZrCl4
4a-m
(10 - 100% mol)
OH
OH
8.11. Found: C 81.03, H 8.01.
R
C
3a-m
C
H
+
H2O
3.2.3. 6-Methyl-6-(phenoxymethyl)dibenzo[d,f][1,3]dioxepine (4d)
Yellow sticky oil. IR (NaCl):
n .
3110, 1590, 1315, 1220, 1035 cmꢁ1
O
1
1H NMR (300 MHz, CDCl3):
d
7.31–7.10 (m, 6H), 6.98–6.75 (m, 7H),
R
CH3
4.82 (s, 2H), 1.95 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d
157.3,
ꢃ
154.5,129.5,126.1,115.4,100.8, 74.0,19.9 ppm. EIMS: m/z: 318 [Mþ ].
Scheme 6. Chemoselectivity of InCl3 and ZrCl4 for 2,2’- dihydroxybiphenyl over water.
Anal. Calcd for C21H18O3: C 79.24, H 5.66. Found: C 79.32, H 5.59.
In conclusion, we succeeded in the high regioselective synthesis of
new 6,6-disubstituted dibenzo[d,f][1,3]dioxepines, demonstrating
that the reaction proceeds through a 2-chloroalkene intermediate
or its related vinyl cation, whose formation represents the key of
the reaction regiochemistry. The chemoselectivity of the catalysts
for 2,20-dihydroxybiphenyl over water was also investigated.
3.2.4. 6-Methyl-6-phenyldibenzo[d,f][1,3]dioxepine (4e)
Pale yellow crystals (mp 83–85 ꢀC). IR (NaCl):
n
3080,1600, 1450,
1260 cmꢁ1 1H NMR (300 MHz, CDCl3):
. d 7.42–7.38 (m, 5H), 7.35–
6.80 (m, 8H), 2.35 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d
154.4,
ꢃ
140.6,129.2,128.7,127.0,125.4,115.1, 26.1 ppm. EIMS:m/z:288 [Mþ ].
Anal. Calcd for C20H16O2: C 83.33, H 5.55. Found: C 83.36, H 5.50.
3. Experimental
3.1. General
3.2.5. 6-Methyl-6-(3-fluorophenyl)dibenzo[d,f][1,3]dioxepine (4f)
Yellow sticky oil. IR (NaCl):
NMR (300 MHz, CDCl3): 7.35–7.11 (m, 4H), 6.98–7.07 (m, 8H), 1.99
n .
3100, 1640, 1400, 1228 cmꢁ1 1H
d
1H and 13C NMR were recorded by a Varian 300 MHz using
tetramethylsilane as internal standard. Microanalysis for CHN were
performed by a Carlo Erba 1106 Elemental Analyzer. IR spectra were
recorded by a Perkin Elmer 157 spectrometer.
(s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d
155.5, 142.7, 134.9, 133.7,
ꢃ
128.2, 125.1, 119.3, 109.3, 102.8 ppm. EIMS: m/z: 306 [Mþ ]. Anal.
Calcd for C20H15FO2: C 78.43, H 4.90. Found: C 78.39, H 4.93.
GC–MS: Low resolution mass spectrometric experiments were
carried out on a Saturn 2000 ion-trap coupled with a Varian 3800
gas chromatograph (Varian, Walnut Creek, CA) operating under EI
3.2.6. 6-Methyl-6-(2-tolyl)dibenzo[d,f][1,3]dioxepine (4g)
Yellow sticky oil. IR (NaCl):
NMR (300 MHz, CDCl3): 7.85–7.60 (m, 4H), 6.98–7.42 (m, 8H), 2.32
n .
3050, 1560, 1480, 1235 cmꢁ1 1H
d
(s, 3H), 1.98 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d
156.7, 140.9,
conditions (electron energy 70 eV, emission current 20 mA, ion-trap
temperature 200 ꢀC, manifold temperature 80 ꢀC, automatic gain
control (AGC) target 21,000) with the ion-trap operating in scan
mode (scan range from m/z 40–400 at a scan rate of 1 scan sꢁ1).
ꢃ
133.0,126.0,114.4,109.5, 95.6,19.9 ppm. EIMS: m/z: 302 [Mþ ]. Anal.
Calcd for C21H18O2: C 83.44, H 5.96. Found: C 83.21, H 6.00.
Aliquot of 1
m
L of solutions 1.0ꢂ10ꢁ5 M in chloroform have been
3.2.7. 6-Methyl-6-(3-tolyl)dibenzo[d,f][1,3]dioxepine (4h)
introduced into the gas chromatograph inlet. A CIP Sil-8 CB Low-
Yellow sticky oil. IR (NaCl):
NMR (300 MHz, CDCl3): 7.80–7.45 (m, 4H), 7.32–7.03 (m, 8H), 2.28
n .
3100, 1630, 1460, 1228 cmꢁ1 1H
bleed/MS capillary column (30 m, 0.25 mm i.d., 0.25 mm film
d
thickness) was used. The oven temperature was programmed from
150 ꢀC (held for 2 min) to 310 ꢀC at 30 ꢀC minꢁ1 (held for 2 min).
The temperature was then ramped to 350 at 20 ꢀC minꢁ1. The
transfer line was maintained at 250 ꢀC and the injector port 30/1
split at 270 ꢀC.
(s, 3H), 2.18 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d 155.9, 138.3,
ꢃ
132.7,127.0,119.2,101.3, 21.4 ppm. EIMS: m/z: 302 [Mþ ]. Anal. Calcd
for C21H18O2: C 83.44, H 5.96. Found: C 83.46, H 5.91.
3.2.8. 6-Methyl-6-(4-tolyl)dibenzo[d,f][1,3]dioxepine (4i)
All starting materials and catalysts were purchased from com-
mercial sources and used without further treatment.
Yellow sticky oil. IR (NaCl):
NMR (300 MHz, CDCl3):
7.78 (dd, 4H, 3J 8.10 Hz, 4J 2.61 Hz), 7.28–
6.89 (m, 8H), 2.35 (s, 3H), 2.15 (s, 3H) ppm. 13C NMR (300 MHz,
n .
3120, 1550, 1450, 1210 cmꢁ1 1H
d
3.2. Typical procedure to synthesize
dibenzo[d,f][1,3]dioxepines
CDCl3):
d
154.4, 137.6, 128.9, 126.5, 119.0, 109.3, 102.8, 21.1 ppm.
ꢃ
EIMS: m/z: 302 [Mþ ]. Anal. Calcd for C21H18O2: C 83.44, H 5.96.
Found: C 83.41, H 5.93.
A mixture of 2,20-dihydroxybiphenyl (1) (5.37 mmol) and the
appropriate terminal alkyne (3a–m) (21.48 mmol) was stirred un-
der nitrogen for the period indicated (TLC) at 60 ꢀC, in the presence
of indium(III) chloride or zirconium(IV) chloride (0.54 mmol). After
reaction, the crude mixture was separated by flash-column chro-
matography (hexane/CH2Cl2 4/1 or 1/1) on alumina, obtaining the
desired product. Solid compounds were recrystallized from hex-
ane/CH2Cl2 6/1.
3.2.9. 6-Methyl-6-(2-methoxyphenyl)dibenzo[d,f][1,3]-
dioxepine (4j)
Pale yellow crystals (mp 77–80 ꢀC). IR (NaCl):
n
3110, 1660, 1480,
1310, 1220, 1050 cmꢁ1. 1H NMR (300 MHz, CDCl3):
7.50–7.03 (m,
4H), 7.28–6.82 (m, 8H), 3.68 (s, 3H), 2.20 (s, 3H) ppm. 13C NMR
d
(300 MHz, CDCl3):
d
157.6, 150.9, 130.7, 126.4, 113.0, 110.8, 99.0,
ꢃ
54.5 ppm. EIMS: m/z: 318 [Mþ ]. Anal. Calcd for C21H18O3: C 79.24, H
5.66. Found: C 79.19, H 5.68.
3.2.1. 6-Butyl-6-methyldibenzo[d,f][1,3]dioxepine (4a)
Pale yellow sticky oil. IR (NaCl):
(300 MHz, CDCl3):
7.35–6.80 (m, 8H), 2.12 (t, 2H, 3J 7.5 Hz), 1.85 (s,
3H), 1.63–1.26 (m, 4H), 1.02 (t, 3H, 3J 7 Hz) ppm. 13C NMR (300 MHz,
n
3080,1490, 1210 cmꢁ1. 1H NMR
d
3.2.10. 6-Methyl-6-(3-ethynylphenyl)dibenzo[d,f][1,3]-
dioxepine (4l)
CDCl3):
d
154.9, 127.3, 125.0, 120.1, 115.1, 99.9, 40.1, 24.0, 15.4,
Brown oil. IR (NaCl):
(300 MHz, CDCl3): 7.45–7.37 (m, 6H), 7.22–6.87 (m, 6H), 3.12 (s,
1H), 2.04 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
165.6, 134.2,
n .
3270, 3050, 1650 cmꢁ1 1H NMR
ꢃ
10.9 ppm. EIMS: m/z: 268 [Mþ ]. Anal. Calcd for C18H20O2: C 80.60, H
d
7.46. Found: C 80.55, H 7.43.
d

G. Tocco et al. / Tetrahedron 64 (2008) 6755–6759
6759
ꢃ
128.5, 126.2, 124.9, 122.7, 83.4, 27.3 ppm. EIMS: m/z: 312 [Mþ ].
Anal. Calcd for C22H16O2: C 84.61, H 5.13. Found: C 84.59, H 5.12.
3.3.3. 1-(1-Chlorovinyl)-2-methoxybenzene (5j)
IR (NaCl):
3100, 1620, 1450, 1330 cmꢁ1
n
.
1H NMR (300 MHz,
CDCl3):
d 7.25–669 (m, 4H), 5.60 (d, 1H), 5.48 (d, 1H), 3.68 (s,
3.2.11. 6-Methyl-6-(6-methoxynaphthyl)dibenzo[d,f][1,3]-
dioxepine (4m)
3H) ppm. 13C NMR (300 MHz, CDCl3):
d
156.7, 128.1, 122.8, 11.7,
ꢃ
59.7 ppm. EIMS: m/z: 168 [Mþ ]. Anal. Calcd for C9H9ClO: C 64.28, H
White crystals (mp 97–100 ꢀC). IR (NaCl):
n
3120, 1600, 1480,
5.35. Found: C 64.21, H 5.33.
1240, 1035 cmꢁ1 1H NMR (300 MHz, CDCl3):
. d 7.98–7.25 (m, 9H),
6.95–6.60 (m, 5H), 3.36 (s, 3H), 2.18 (s, 3H) ppm. 13C NMR
Acknowledgements
(300 MHz, CDCl3):
d 156.1, 154.4, 141.6, 135.1, 128.2, 125.9, 126.9,
121.3, 119.1, 115.0, 113.23, 107.1, 101.1, 58.1, 26.0 ppm. EIMS: m/z: 368
`
This work was supported by Ministero dell’Universita, dell’Is-
ꢃ
[Mþ ]. Anal. Calcd for C25H20O3: C 81.52, H 5.43. Found: C 81.48, H
truzione e della Ricerca MIURdPRIN 2005 and Progetto di Ricerca
5.39.
`
Scientifica 2005dUniversita di Cagliari.
3.3. Reaction between 2,20-dihydroxybiphenyl (1)
and 2-(1-chlorovinyl)-6-methoxynaphtalene (5m)
References and notes
1. (a) Blum, J.; Huminer, H.; Alper, H. J. Mol. Catal. 1992, 75, 753; (b) Damiano, J. P.;
Postel, M. J. Organomet. Chem. 1996, 522, 303; (c) Alonso, F.; Beletskaya, I. P.;
Yus, M. Chem. Rev. 2004, 104, 3079.
2. (a) Fukuda, Y.; Utimoto, K. J. Org. Chem. 1991, 56, 3729; (b) Hirabayashi, T.;
Okimoto, Y.; Saito, A.; Morita, M.; Sakaguchi, S.; Ishii, Y. Tetrahedron 2006, 62,
2231.
A mixture of 2,20-dihydroxybiphenyl (1) (0.54 mmol) and 2-(1-
chlorovinyl)-6-methoxynaphtalene (5m) (0.65 mmol) in dichloro-
methane (5 ml) was stirred under nitrogen for 30 min at 40 ꢀC, in
the presence of indium(III) chloride or zirconium(IV) chloride
(0.054 mmol). The reaction was monitored by GC–MS analysis,
observing the total conversion of compound (5m) into dibenzo-
dioxepine (4m) in the period indicated.
3. Kataoka, Y.; Matsumoto, O.; Tani, K. Organometallics 1996, 15, 5246.
4. Hartman, J. W.; Sperry, L. Tetrahedron Lett. 2004, 45, 3787.
5. Kim, S. Y.; Chin, C. S.; Eum, M.-S. J. Mol. Catal. A: Chem. 2006, 253, 245.
6. Cossu, S.; De Lucchi, O.; Fabris, F.; Ballini, R.; Bosica, G. Synthesis 1996, 12, 1481.
7. (a) Stewart, I. C.; Bergman, R. G.; Toste, F. D. J. Am. Chem. Soc. 2003, 125, 8696;
(b) Inanaga, J.; Baba, Y.; Hanamoto, T. Chem. Lett. 1993, 2, 241; (c) Sriramurthy,
V.; Barcan, G. A.; Kwon, O. J. Am. Chem. Soc. 2007, 129, 12928.
8. Murtagh, J. E.; McCooey, S. H.; Connon, S. J. Chem. Commun. 2005, 227.
9. (a) Tocco, G.; Begala, M.; Delogu, G.; Picciau, C.; Podda, G. Tetrahedron Lett.
2004, 45, 6909; (b) Tocco, G.; Begala, M.; Meli, G.; Podda, G. Heterocycles 2007,
71, 635.
10. (a) Begala, M.; Tocco, G.; Delogu, G.; Meli, G.; Picciau, C.; Podda, G. J. Mass.
Spectrom. 2006, 41, 577; (b) Begala, M.; Tocco, G.; Meli, G.; Podda, G.; Urru, S. A.
M. Rapid Commun. Mass Spectrom. 2007, 21, 114; (c) Begala, M.; Tocco, G.; Meli,
G.; Podda, G.; Urru, S. A. M. J. Mass. Spectrom., submitted for publication.
11. Kabalka, G. W.; Zhongzhi, W.; Ju, Y. Org. Lett. 2002, 4, 3415.
12. Satoh, T.; Miura, M. Topics in Organometallic Chemistry; Chatani, N., Ed.;
Springer: Berlin, Heidelberg, 2008; Vol. 24, pp 61–84.
3.3.1. 2-(1-Chlorovinyl)-6-methoxynaphtalene (5m)
IR (NaCl):
CDCl3): 7.72–6.95 (m, 6H), 5.71 (d, 1H), 5.46 (d, 1H), 3.70 (s,
n .
3150, 1430, 1310, 1250 cmꢁ1 1H NMR (300 MHz,
d
3H) ppm. 13C NMR (300 MHz, CDCl3):
d
158.1, 134.3, 132.6, 127.0,
ꢃ
129.4, 124.1, 121.9, 111.3, 57.8 ppm. EIMS: m/z: 218 [Mþ ]. Anal. Calcd
for C13H11ClO: C 71.56, H 5.04. Found: C 71.53, H 5.00.
3.3.2.
IR (NaCl):
7.30–7.12 (m, 5H), 5.82 (d, 1H), 5.35 (d, 1H) ppm. 13C NMR
a
-Chlorostyrene (5e)
n
3050, 1650, 1420 cmꢁ1. 1H NMR (300 MHz, CDCl3):
d
13. (a) Yamaguchi, M.; Hayashi, A.; Hirama, M. J. Am. Chem. Soc. 1995, 117, 1151; (b)
Yamaguchi, M.; Arisawa, M.; Omata, K.; Kabuto, K.; Hirama, M.; Uchimaru, T.
J. Org. Chem. 1998, 63, 7298.
(300 MHz, CDCl3):
d 137.4, 128.0, 121.5, 110.1 ppm. EIMS: m/z: 138
ꢃ
[Mþ ]. Anal. Calcd for C8H7Cl: C 69.56, H 5.07. Found: C 69.51, H 5.00.