Ruthenium-catalyzed intramolecular cyclization of hetero-functionalized allylbenzenes

Article abstract of DOI:10.1016/j.jorganchem.2006.05.059

Intramolecular addition of heterofunctionalities to C{double bond, long}C double bonds without β-hydride elimination was investigated and catalyzed by ruthenium complexes. The combination of RuCl₃ · nH₂O (10 mol%) and 3 equiv. of AgOTf acted as a catalyst for cyclization of 2-allylphenol (1a) to 2,3-dihydro-2-methylbenzofuran (2a) in good yield in the presence of Cu(OTf)₂ as a co-catalyst and PPh₃ as a ligand. This catalyst system also catalyzed the cyclization of 2-allylbenzoic acid to lactone in 91% yield. Then, a new catalyst system (RuCp^*Cl₂)₂ (1.0 mol%)/4AgOTf/4PPh₃, was found to be more active even in the absence of Cu(OTf)₂. Furthermore, this catalysis was applied to asymmetric reaction of 2-allylphenol (1a). When using TolBINAP as a ligand, over 60% e.e. was achieved.

Full text of DOI:10.1016/j.jorganchem.2006.05.059

Journal of Organometallic Chemistry 692 (2007) 671–677
www.elsevier.com/locate/jorganchem
Ruthenium-catalyzed intramolecular cyclization of
hetero-functionalized allylbenzenes
*
Tetsuo Ohta , Yohei Kataoka, Akio Miyoshi, Yohei Oe, Isao Furukawa, Yoshihiko Ito
Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
Received 1 March 2006; received in revised form 12 May 2006; accepted 17 May 2006
Available online 30 August 2006
Abstract
Intramolecular addition of heterofunctionalities to C@C double bonds without b-hydride elimination was investigated and catalyzed
by ruthenium complexes. The combination of RuCl3 Æ nH2O (10 mol%) and 3 equiv. of AgOTf acted as a catalyst for cyclization of 2-
allylphenol (1a) to 2,3-dihydro-2-methylbenzofuran (2a) in good yield in the presence of Cu(OTf)2 as a co-catalyst and PPh3 as a ligand.
This catalyst system also catalyzed the cyclization of 2-allylbenzoic acid to lactone in 91% yield. Then, a new catalyst system (RuCp*Cl2)2
(1.0 mol%)/4AgOTf/4PPh3, was found to be more active even in the absence of Cu(OTf)2. Furthermore, this catalysis was applied to
asymmetric reaction of 2-allylphenol (1a). When using TolBINAP as a ligand, over 60% e.e. was achieved.
Ó 2006 Elsevier B.V. All rights reserved.
Keywords: Ruthenium; Intramolecular cyclization; Olefin; Heterocycles; Enantioselective reaction; Catalysis
1. Introduction
[11] can act as an effective catalyst for this reaction even
without Cu(OTf)2. Herein, we would like to describe the
details of the reaction using ruthenium catalysts [12].
As olefin is the most accessible raw material in chemical
industry, transformation of olefin is a great deal to con-
structing various materials. Nevertheless, addition of
RXH (X = heteroatom) to olefin under neutral conditions
has been limited [1–3]. There have been only few examples
of intramolecular [4] and intermolecular [5] addition of het-
eroatom nucleophiles to olefins, except for the amination
of olefins [6].
We have already reported the preliminary work of intra-
molecular addition of phenolic hydroxide to olefin in 2-
allylphenol in the presence of a catalytic amount of
RuCl3 Æ nH2O/3AgOTf and Cu(OTf)2 [7]. This catalysis
revealed that ruthenium complex catalyzes the addition of
nucleophiles (RXH) to olefins without b-elimination [8–
10]. The high loading of catalyst was needed for getting rea-
sonable yield of the product. Then, we have been searching
other catalysts for this reaction and found that (RuCp*Cl2)2
2. Results and discussion
2.1. Intramolecular cyclization using RuCl3 Æ nH2O/3AgOTf/
Cu(OTf)2
catalyst
+
+
O
O
solvent
OH
OH
1a
2a
3a
4a
Various catalytic systems and reaction conditions were
examined for the cyclization of 1a, and some representative
results are listed in Table 1. Ruthenium and iron com-
pounds treated with AgOTf showed some activities for this
reaction, while only the ruthenium compound exhibited
good catalytic activity with the addition of Cu(OTf)2.
Cyclization of 1a was effectively performed in acetonitrile
at 80 °C in the presence of a ruthenium-based catalyst pre-
pared by pre-heating a mixture of RuCl3 Æ nH2O and
*
Corresponding author. Fax: +81 774 65 6789.
E-mail address: tota@mail.doshisha.ac.jp (T. Ohta).
0022-328X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.05.059

672
T. Ohta et al. / Journal of Organometallic Chemistry 692 (2007) 671–677
Table 1
Table 2
Cyclization of 1a by transition-metal catalysta
Cyclization using RuCl3 Æ nH2O/3 AgOTf in the presence of Cu(OTf)2
a
Entry Catalyst
Additive
Yieldb (%)
Entry
Substrate
Product
Yieldb (%)
2a 3a
4a
O
1
2
3c
4
5
6
7d
8
RuCl3 Æ nH2O/3AgOTf Cu(OTf)2
51
4
0
0
4
0
0
0
4
1
4
15
10
23
5
10
0
OH
R
R
RuCl3 Æ nH2O/3AgOTf
–
1
2
3
4
5
1a: R = H
2a: R = H
61 (69)c
51
53
65
PdCl2/2AgOTf
Cu(OTf)2
1b: R = 4-MeO
1c: R = 6-MeO
1d: R = 6-Me
2b: R = 5-MeO
2c: R = 7-MeO
2d: R = 7-Me
RhCl3 Æ 3H2O/3AgOTf Cu(OTf)2
Trace
FeCl3 Æ 6H2O/3AgOTf
AgOTf
Cu(OTf)2
–
0
0
0
0
0
0
58
–
–
Cu(OTf)2
TfOHe
0
0
OH
9f
10g
a
RuCl3 Æ nH2O/3AgOTf Cu(OTf)2/TfOH 63
RuCl3 Æ nH2O/3AgOTf Cu(OTf)2/PPh3 69
Trace
2
O
5
Reaction conditions: 1a (4.0 mmol), RuCl3 Æ nH2O (0.4 mmol), AgOTf
6
(1.2 mmol), additive (2.0 mmol), CH3CN (10 mL), 80 °C, 24 h.
MeO
6
68
72
MeO
b
Determined by GLC analysis (PEG-20M).
CH3OH (10 mL) as a solvent.
Cu(OTf)2 (4.0 mmol).
TfOH (1.0 mL, 11 mmol).
TfOH (0.3 mL, 3.4 mmol).
CH3CN (3 mL), 48 h, PPh3 (0.8 mmol).
c
O
OH
d
8
7
e
f
7
g
OH
O
9
10
a
3 equiv. of AgOTf in the presence of Cu(OTf)2 in CH3CN
to give 2a in moderate yield. Acetonitrile was solely chosen
among the solvents examined. No reaction occurred by the
use of AgBF4 instead of AgOTf or by the addition of
CuCl2 instead of Cu(OTf)2.
Reaction conditions: substrate (4.0 mmol), RuCl3 Æ nH2O (0.4 mmol),
AgOTf (1.2 mmol), Cu(OTf)2 (2.0 mmol), CH3CN (10 mL), 80 °C, 24 h.
b
Isolated yield.
The figure in parentheses was determined by GC.
c
From the reaction, the desired product 2a was
obtained in moderate yield followed by considerable
amounts of 3a and olefin-isomerized product (E)- and
(Z)-2-(1-propenyl)phenol (4a). Interestingly, the addition
of TfOH or PPh3 suppressed the formation of 3a and
4a. Since TfOH alone was ineffective as a catalyst for
this cyclization in acetonitrile, TfOH influenced the cata-
lytic stage mediated by ruthenium.
This catalytic cyclization was not influenced by the sub-
stituents on the aromatic ring of the substrates (Table 2),
and five-membered ring compounds were always formed
from allyl derivatives (entries 1–5). In the case of phenol
derivative with 3-methyl-2-butenyl substituent 7, six-mem-
bered product 8, Markovnikov type product, was formed.
2-Homoallylphenol (9) was transformed to a six-membered
cyclic product, 3,4-dihydro-2H-2-methylbenzopyran (10),
in good yield, while 2-vinylphenol was not converted to
the cyclic compound.
Table 3
Cyclization of carboxylic acid derivativesa
Entry
1
Substrate
Product
Yieldb (%)
89 (91)
OH
O
O
O
11
13
12
2
78 (83)
O
OH
O
O
14
3
46 (67)
O
O
OH
15
Benzoic acids were also used for this catalysis (Table 3).
2-Allylbenzoic acid (11) was converted to six-membered
lactone 12 in good yield, while five-membered lactone 14
was obtained from the reaction of 2-vinylbenzoic acid
(13). This catalysis was also applied to aliphatic carboxylic
acid, 4-pentenoic acid (15), to give c-valerolactone (16) in
moderate yield.
O
16
a
Reaction conditions: substrates (4 mmol), RuCl3 Æ H2O (0.4 mmol),
AgOTf (1.2 mmol), Cu(OTf)2 (2 mmol), PPh3 (0.8 mmol), CH3CN (3 mL),
80 °C, 48 h, under Ar.
b
Isolated yield of cyclization product. Figures in parentheses show the
yield from the reaction for 96 h.
2.2. Intramolecular cyclization of 2-allylphenol (1a) using
(Cp*RuCl2)2
(Cp*RuCl2)2, 4 mol% of AgOTf, and PPh3, in various sol-
vents in the presence of Cu(OTf)2. The representative
results are listed in Table 4. The reaction did not proceed
The reaction of 2-allylphenol (1a) was performed in the
presence of a ruthenium complex derived from 1 mol% of

T. Ohta et al. / Journal of Organometallic Chemistry 692 (2007) 671–677
673
Table 4
Alcohols were subjected for this reaction instead of phe-
nols. Using RuCl3 Æ nH2O + AgOTf, 2-allylbenzyl alcohol
(17) reacted to give cyclic product 18 in 15%, while
(Cp*RuCl2)2 + AgOTf system showed better catalytic
activity even through the yield was low. Acidity of the pro-
tic hydrogen might affect the reactivity. Aliphatic alcohol,
5-hexen-1-ol, did not give the cyclic product (see Table 5).
In cases of aniline derivatives, the reaction was strongly
dependent of the substituent on nitrogen. In both catalytic
systems, 2-allylaniline was not converted at all. When N-
methyl-2-allylaniline was used, cyclization did not occur,
and furthermore, isomerization of olefin proceeded (2-(1-
propenyl)-N-methylaniline 95% (cis/trans = 59:36)). This
probably is due to the enhanced coordination ability of
nitrogen in N-methyl-2-allylaniline. 2-Allylacetanilide and
2-allylbenzanilide did not suffer any transformation, while
2-allyl-N-tosylaniline (19) converted to cyclic product 20
in 38% yield by RuCl3 Æ nH2O-based catalyst system and
in 79% yield by (Cp*RuCl2)2catalyst system. These results
suggested that the acidity of the proton on nitrogen of
the substrates was very important in this catalysis.
Ruthenium complex-catalyzed intramolecular cyclization of 2-allylphenola
Entry
Reaction condition
Yieldb of 2a (%)
Solvent
Temperature
(°C)/time (h)
Additive
(mol%)
1
2
3
4
5
6
CH3CN
THF
80/48
80/48
80/48
80/48
Reflux/48
60/48
60/48
60/48
60/48
60/48
60/48
60/48
60/48
60/48
60/48
Cu(OTf)2 (50)
Cu(OTf)2 (50)
Cu(OTf)2 (50)
Cu(OTf)2 (50)
Cu(OTf)2 (50)
Cu(OTf)2 (50)
Cu(OTf)2 (50)
Cu(OTf)2 (25)
Cu(OTf)2 (10)
Cu(OTf)2 (1)
–
0
0
0
MeOH
Benzene
CH2Cl2
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
CHCl3
88
72
>95
>95
>94
83
67
21
58–68
7
7c
8c
9c
10c
11c
12d
13d
14d
15d
a
Cu(OTf)2 (10)
AgOTf (10)
CuCl2 (50)
0
45
TfOH (20)
Reaction conditions: 1a (1.0 mmol), (Cp*RuCl2)2 (1 mol%), AgOTf
(4 mol%), solvent (3 mL), PPh3 (2 mol%), under Ar.
b
Yields were determined by 1H NMR using internal standard (dibenzyl
ether) method.
c
(Cp*RuCl2)2 (0.5 mol%), AgOTf (2 mol%), and PPh3 (1 mol%) were
used.
d
Without (Cp*RuCl2)2 and AgOTf.
N
N-Ts
H
19
Ts
20
RuCl3.nH2O (10 mol%), Ag(OTf) (30 mol%), PPh3 (20 mol%)
Cu(OTf)2 (50 mol%), CH3CN, 80 oC, 96 h
(RuCp*Cl2)2 (1 mol%), Ag(OTf) (4 mol%), PPh3 (2 mol%)
benzene, reflux, 48 h
in acetonitrile, which was chosen as the solvent for the reac-
tion using RuCl3 Æ nH2O/3AgOTf as a catalyst in the previ-
ous section. No reaction occurred in THF and methanol.
On the other hand, benzene, dichloromethane and chloro-
form are the choice of solvents for this catalysis to give
the cyclic product in good yield (up to >95%). In chloro-
form, the amount of catalyst was able to be reduced to
0.5 mol% without any loss of the yield (entry 7). The
amount of Cu(OTf)2 was also able to be reduced, but use
of less than 25 mol% of Cu(OTf)2 slightly decreased the
yield of the product. In acetonitrile, Cu(OTf)2 and AgOTf
showed no catalytic activities. But interestingly, Cu(OTf)2
was catalytically active in chloroform. Still, AgOTf gave
the product in less than catalytic amount yield in chloro-
form. CuCl2 did not work as a catalyst for cyclization.
These metal compounds are going to be demonstrated sep-
arately as a catalyst for this reaction. Trifluoromethanesulf-
onic acid also showed catalytic activity in chloroform.
38% yield
79% yield
2.4. Attempt for asymmetric reaction
Our preliminary study for asymmetric cyclization of 2-
allylphenol demonstrated that the reaction proceeded in
an asymmetric fashion using RuCl3 Æ nH2O with BINAP
without Cu(OTf)2 in acetonitrile to give the optically active
product with about 90% e.e. even in trace yield. On the
other hand, the reaction by the same catalyst in the presence
of Cu(OTf)2 (50 mol% to substrate) gave racemic product in
48% yield. These observations forced us to find the catalyst
system without Cu(OTf)2. The results are listed in Table 6.
Using high loading catalyst, higher reaction temperature,
and long reaction time gave the product in higher yields
(entries 1–5). Using less polar solvent, such as benzene
and toluene, exhibited good influence in yield. That is, in
benzene and the product was obtained in 95% yield from
the reaction at reflux for 48 h (entries 6–8). The use of cyclo-
hexane led to a decrease in the yield of the product (entry 9).
Then, we tested the asymmetric reaction using various
optically active phosphine ligands without Cu(OTf)2, and
the results are summarized in Table 7. At first, (S)-BINAP
was used as a ligand for determining a standard condition
(entries 1–4). Toluene was a choice of solvent, and long
reaction time did not affect enantiomeric excess. Lower
reaction temperature made e.e. better as 48% even through
the yield became low (entry 4). As a result, the reaction was
(RuCp*Cl2)2 / 2 PPh3 / 4 AgOTf
additive, solvent
O
OH
1a
2a
2.3. Other substrates
catalyst
OH
O
18
17

674
T. Ohta et al. / Journal of Organometallic Chemistry 692 (2007) 671–677
Table 5
a
Intramolecular cyclization of 2-allylbenzyl alcohol (17) using (Cp*RuCl2)2
Entry
Reaction condition
Catalyst (mol%)
Yieldb of 18 (%)
Solvent
Temperature (°C)/time (h)
Cu(OTf)2 (mol%)
1
2
3
a
RuCl3 Æ nH2O (10) + AgOTf (30)
(Cp*RuCl2)2 (1) + AgOTf (4)
(Cp*RuCl2)2 (1) + AgOTf (4)
CH3CN
Toluene
Benzene
80/48
Reflux/48
Reflux/48
50
0
0
15
12
24
Reaction conditions: 17 (1.0 mmol), catalyst, solvent (3 mL), PPh3 (20 mol% for RuCl3 Æ nH2O, 2 mol% for (Cp*RuCl2)2), under Ar.
b
Yields were determined by 1H NMR using internal standard (bibenzyl) method.
performed in toluene at reflux temperature using various
optically active ligands. Using (S)-TolBINAP showed
higher catalytic activity and moderate selectivity (entry
5). BPPM and BPPFA did not promote the reaction at
all (entries 10 and 11). DIOP and JOSIPHOS showed mod-
erate enantiomeric excesses as 37% and 69%, respectively,
Table 6
a
Intramolecular cyclization of 2-allylphenol (1a) using (Cp*RuCl2)2
Entry
Solvent
Temperature (°C)/time (h)
Yieldb of 2a (%)
1c
2
3
4
5
6
7
8
9
a
CHCl3
CHCl3
CHCl3
CHCl3
60/48
60/48
21
26
39
64
64
75
95
85
56
Reflux/24
Reflux/48
Reflux/72
Reflux/24
Reflux/48
Reflux/48
Reflux/48
even through
a considerable amount of substrates
CHCl3
remained unchanged (entries 11 and 13). Lowering the tem-
perature led to an increase in the enantiomeric the use of
(S)-TolBINAP, while the enantiomeric excess with became
lower in cases of DIOP and JOSIPHOS (entries 6, 12, and
14).
Benzene
Benzene
Toluene
Cyclohexane
Reaction conditions: 1a (1.0 mmol), (Cp*RuCl2)2 (1.0 mol%), AgOTf
(4.0 mol%), PPh3 (2.0 mol%), a solvent (3 mL), under Ar.
b
Yields were determined by 1H NMR using internal standard (dibenzyl
2.5. Reaction mechanism
ether) method.
c
(Cp*RuCl2)2 (0.5 mol%), AgOTf (2.0 mol%), PPh3 (1.0 mol%).
Now, we have no evidence about the reaction mecha-
nism. Nevertheless, plausible mechanism is shown in
Scheme 1. First, ruthenium precursor reacts with AgOTf
to give a cationic ruthenium species. This cationic Ru(III)
species has some TfOÀ, ligand, and/or solvent molecules.
The C@C double bond of 2-allylphenol coordinates to this
cationic ruthenium to give a Ru–olefin complex, which
allowed to react with phenolic oxygen in a nucleophilic
fashion intramolecularly to give cyclized intermediate. At
this stage, the counter anion holds the phenolic proton,
and the resulting TfOH reacts with carbon–ruthenium r-
bond by protonolysis to give the desired product and active
ruthenium intermediate. Hosokawa et al. also suggested a
similar intermediate in the reaction of 1a catalyzed by a
Pd compound [8b]. Product 2a could be obtained from
21 by protonolysis, and by-product 3a could be formed
from the same intermediate 21 by b-hydride elimination.
No formation of 3a by addition of TfOH indicates that
the protonolysis of 21 proceeds smoothly by adding TfOH.
The formation of olefinic by-product 4a was also sup-
pressed by adding TfOH or PPh3, suggesting that 4a was
formed from common olefin–ruthenium intermediate via
hydrogen migration proposed in the literature [12].
Table 7
Asymmetric intramolecular cyclization of 2-allylphenol (1a) using
(Cp*RuCl2)2
a
Entry
Ligand
Yield of 2 (%)b
% e.e.c of 2
1d
2
3e
4f
(S)-BINAP
(S)-BINAP
(S)-BINAP
(S)-BINAP
(S)-TolBINAP
(S)-TolBINAP
(S)-TolBINAP
(S,S)-BPPM
(S,R)-BPPFA
(R,R)-Me-DuPHOS
(R,R)-DIOP
63
74
50
28
80
37
2
0(100)
0(100)
90
33 (60)
75
10 (78)
41
57
17
28
7
48
33
65
13
–
5
6f
7g
8
9
–
2
10
11
12f
13
14f
15
16
17
a
37
15
69
47
3
(R,R)-DIOP
(R,S)-JOSIPHOS
(R,S)-JOSIPHOS
(R,R)-CHIRAPHOS
(R)-PROPHOS
(R,R)-NORPHOS
78
73
14
4
Reaction conditions: 2-allylphenol (1.0 mmol), (Cp*RuCl2)2 (1 mol%),
AgOTf (4 mol%), ligand (2 mol%), toluene (3 mL), reflux, 48 h, argon
atmosphere.
b
Yields were determined by 1H NMR using internal standard (dibenzyl
3. Experimental
ether) method, and figures in parentheses are recovered substrate 1a.
c
Determined by chiral HPLC (column packing: Daicel Chiralcel OJ-R;
3.1. General
eluent: MeOH/H2O = 3/2; detector: UV254 nm; flow rate 0.3 mL/min).
d
In benzene.
In cyclohexane.
At 50 °C for 96 h.
Proton nuclear magnetic resonance (1H NMR) spectra
were measured using a JEOL JNM A-400 (400 MHz) spec-
trometer using tetramethylsilane as the internal standard.
e
f
g
At 30 °C for 150 h.

T. Ohta et al. / Journal of Organometallic Chemistry 692 (2007) 671–677
675
RuLhClm
mAgOTf
mAgCl
RuLj(OTf)m
OH
O
LkRu(OTf)m-1
LkRu(OTf)m
OH
OTf
H
O
21
LkRu(OTf)m-1
TfOH
OTf
O
H
L = PPh3 and/or solvent
Scheme 1. Possible mechanism for the intramolecular cyclization of 2-allylphenol catalyzed by ruthenium complex.
IR spectra were measured on a Shimadzu IR-408 spectrom-
eter. Mass spectral (GC–MS) data were recorded on a Shi-
madzu QP2000A instrument. HPLC analysis was done by
Shimadzu LC-10A with chiral column (Daicel CHIRAL-
CEL OJ-R, 0.3 mL/min, detector UV254 nm). Optical rota-
tion was measured by Horiba Sepa-200 instrument. The
substrates purchased were used without further purifica-
tion. The solvents were purified according to the literature
method, and stored under argon.
2-Allyl-4-methoxyphenol (1b) [13], 1-allyl-2-naphthol (5)
[14], 2-(3-methyl-2-butenyl)-4-methoxyphenol (7) [15],
2-(3-butenyl)phenol (9) [16], 2-allylbenzoic acid (11) [17],
2-vinylbenzoic acid (13) [18], 2-allylbenzyl alcohol (17)
[19], 2-allylaniline [20], 2-allyl-N-methylaniline [21],
N-(2-allylphenyl)acetamide [22], 2-allyl-N-benzanilide [23],
2-allyl-N-tosylaniline (19) [24], and dichloropentamethyl-
cyclopentadienylruthenium dimer [Cp*RuCl2]2 [11] were
prepared according to the literature method.
and ether, and the organic materials were extracted by
ether. After removal of the solvent, the products were iso-
lated by column chromatography (silica gel, hexane–ethyl
1
acetate) and identified by H NMR, GC–MS, and/or IR.
3.2.2. Typical reaction procedure 2
Into a 20 mL Schlenk tube under argon were added
(Cp*RuCl2)2 (6.2 mg, 0.01 mmol), benzene (3.0 mL), and
AgOTf (10.3 mg, 0.06 mmol), and then the mixture was
heated at reflux for 3 h. After cooling, 2-allylphenol
(1.0 mmol) and PPh3 (0.02 mmol) were added and the mix-
ture was stirred at reflux for 48 h. The solvent was removed,
water and dibenzyl ether (48.5 mg, 0.25 mmol) were added,
and then the organic materials were extracted with chloro-
1
form. The obtained organic mixture was analyzed by H
NMR, and the yield of 2,3-dihydro-2-methylbenzofuran
was determined by its area compared to that of the internal
standard (dibenzyl ether). The product was isolated by col-
umn chromatography (silica gel, hexane:AcOEt = 10:1).
When chiral phosphine was used, the enantiomeric excess
was determined using chiral HPLC analysis (column pack-
ing: Daicel Chiral OJ-R; eluent: MeOH/H2O = 3/2; detec-
tor: UV254 nm; flow rate 0.3 mL/min).
3.2. Intramolecular cyclization of 2-allylphenol (1a)
3.2.1. Typical reaction procedure 1
Into
a
30 mL three-necked flask were added
RuCl3 Æ nH2O (0.10 g, 0.4 mmol), acetonitrile (3.0 mL),
and AgOTf (0.32 g, 1.2 mmol), and then the mixture was
heated at 80 °C for 2 h. After cooling, 2-allylphenol
(4.0 mmol), PPh3 (0.21 g, 0.8 mmol), and Cu(OTf)2
(0.72 g, 2.0 mmol) were added to the mixture, and the mix-
ture was stirred at 80 °C for 48 h. After the reaction, solid
materials were removed through a Celite pad, and then the
eluent was concentrated. To the residue were added water
3.3. 2,3-Dihydro-2-methylbenzofuran (2a)
1H NMR(CDCl3) d 1.46 (3H, d, J = 6.4, CH3), 2.81
(1H, dd, J = 14.4, 7.2, CH2), 3.30 (1H, dd, J = 14.4, 7.2,
CH2), 4.88–4.94 (1H, m, CH), 6.75 (1H, d, J = 7.6, Ar),
6.82 (1H, t, J = 7.6, Ar), 7.10 (1H, t, J = 7.6, Ar), 7.15
(1H, d, J = 7.6, Ar). GC–MS (m/z) 134.

676
T. Ohta et al. / Journal of Organometallic Chemistry 692 (2007) 671–677
3.4. 2,3-Dihydro-5-methoxy-2-methylbenzofuran (2b)
d, J = 7.6, Ar), 7.68 (1H, t, J = 7.3, Ar), 7.89 (1H, d,
J = 7.6, Ar). GC–MS (m/z) 169.
1H NMR(CDCl3) d 1.43 (3H, d, J = 6.79, CH3), 2.77 (1H,
dd, J = 15.2, 7.6, CH2), 3.25 (1H, dd, J = 15.2, 7.6, CH2),
3.73 (3H, s, OCH3), 4.83–4.91 (1H, m, CH), 6.61–6.67
(2H, m, Ar), 6.73 (1H, d, J = 2.4, Ar). GC–MS (m/z) 164.
3.12. c-Methylbutyrolactone (16)
1H NMR (CDCl3) d 1.38 (2H, d, J = 6.1, CH3), 1.77–
1.85 (1H, m, COCH2CH2), 2.03–2.37 (1H, m,
COCH2CH2), 2.50–2.54 (2H, m, COCH2), 4.57–4.65 (1H,
m, CH). GC–MS (m/z) 100.
3.5. 2,3-Dihydro-7-methoxy-2-methylbenzofuran (2c)
1H NMR(CDCl3) d 1.51 (3H d, J = 6.0, CH3), 2.84 (1H,
dd, J = 15.2, 7.6, CH2), 3.32 (1H, dd, J = 15.2, 7.6, CH2),
3.87 (3H, s, OCH3), 4.93–5.02 (1H, m, CH), 6.72–6.81 (3H,
m, Ar). GC–MS (m/z) 164.
3.13. 3-Methylisochroman (18)
1H NMR (CDCl3) d 1.35 (3H, d, J = 6.0, CH3), 2.71
(2H, d, J = 6.8, ArCH2CH), 3.82 (1H, m, CH), 4.83 (2H,
s, ArCH2O), 6.99–7.36 (4H, m, Ar).
3.6. 2,3-Dihydro-2,7-dimethylbenzofuran (2d)
1H NMR(CDCl3) d 1.47 (3H, d, J = 6.4, CH3), 2.20
(3H, s, CH3), 2.81 (1H, dd, J = 15.2, 7.6, CH2), 3.30 (1H,
dd, J = 15.2, 7.6, CH2), 4.86–4.94 (1H, m, CH), 6.73 (1H,
d, J = 7.6, Ar), 6.92 (1H, d, J = 7.6, Ar), 6.98 (1H, d,
J = 7.6, Ar). GC–MS (m/z) 148.
3.14. 2-Methyl-N-tosylindoline (20)
1H NMR (CDCl3) d 1.46 (3H, d, J = 6.4, CHCH3), 2.38
(3H, s, ArCH3), 2.46 (1H, dd, J = 6.4, 3.2, CH2), 4.34–4.42
(1H, m, CH), 7.03–7.09 (2H, m, Ar), 7.18–7.26 (3H, m, Ar),
7.58 (2H, d, J = 8.4, Ar),7.69 (1H,d, J = 8.0, Ar). GC–MS
(m/z) 287.
3.7. 2,3-Dihydro-2-methylnaphtho[3,2-b]furan (6)
1H NMR(CDCl3) d 1.54 (3H, d, J = 6.4, CH3), 3.07
(1H, dd, J = 15.2, 7.6, CHH), 3.60 (1H, dd, J = 15.2, 7.6,
CHH), 5.08–5.17 (1H, m, CH), 7.08 (1H, d, J = 8.8, Ar),
7.27–7.31 (1H, m, Ar), 7.43–7.47 (1H, m, Ar), 7.56 (1H,
d, J = 8.8, Ar), 7.67 (1H, d, J = 8.8, Ar), 7.79 (1H, d,
J = 8.8). GC–MS (m/z) 185 (MH+).
Acknowledgements
This work was partially supported by Doshisha Univer-
sity’s Research Promotion Fund, and a grant to RCAST at
Doshisha University from the Ministry of Education, Cul-
ture, Sports, Science and Technology, Japan. This work
was supported by Grant-in-Aid for Scientific Research on
Priority Areas (No. 16033259, ‘‘Reaction Control of Dy-
namic Complexes’’) from the Ministry of Education, Cul-
ture, Sports, Science and Technology, Japan.
3.8. 6-Methoxy-2,2-dimethylchroman (8)
1H NMR(CDCl3) d 1.31 (6H, s, 2CH3), 1.78 (2H, t,
J = 6.8, ArCH2CH2), 2.75 (2H, t, J = 6.8, ArCH2), 3.74
(3H, s, OCH3), 6.61 (1H, d, J = 2.4, Ar), 6.66–6.72 (2H,
m, Ar). GC–MS (m/z) 192.
References
3.9. 3,4-Dihydro-2-methyl-2H-1-benzopyran (10)
[1] (a) Wacker-type reactions see: L. Hintermann, second ed., in: M.
Beller, C. Bolm (Eds.), Transition Metals for Organic Synthesis, vol.
2, Wiley–VCH Verlag GmbH & Co. KGaA, Weinheim, 2004, pp.
379–388;
1H NMR (CDCl3) d 1.39 (3H, d, J = 6.0, CH3), 1.65–
1.48 (1H, m, CH2CH2CH), 1.94–2.00 (1H, m,
CH2CH2CH), 2.70–2.76 (1H, ddd, J = 16.4, 3.2,
CH2CH2CH), 2.81–2.90 (1H, ddd, J = 16.4, 6.4, 3.2,
CH2CH2CH), 4.08–4.18 (1H, m, CH), 6.78–6.83 (2H, m,
Ar), 7.02–7.09 (2H, m, Ar). GC–MS (m/z) 148.
(b) T. Punniyamurthy, S. Velusamy, J. Iqbal, Chem. Rev. 105 (2005)
2329–2363;
(c) J.M. Takacs, X-t Jiang, Curr. Org. Chem. 7 (2003) 369–396;
(d) R. Jira, second ed., in: B. Cornils, W.A. Herrmann (Eds.),
Applied Homogeneous Catalysis with Organometallic Compounds,
vol. 1, Wiley–VCH Verlag GmbH, Weinheim, 2002, pp. 386–405.
[2] (a) Acidic conditions see: D. Barton, W.D. Ollis, J.F. Stoddart
(Eds.), Comprehensive Organic Chemistry, vol. I, Pergamon, Oxford,
1979;
3.10. 3,4-Dihydro-3-methyl-1-oxoisocoumarine (12)
1H NMR (CDCl3) d 1.53 (3H, d, J = 6.0, CH3), 2.90–
3.02 (2H, m, CH2), 4.65–4.73 (1H, m, CH), 7.24 (1H, d,
J = 7.2, Ar), 7.39 (1H, t, J = 7.6, Ar), 7.54 (1H, t,
J = 7.6, Ar), 8.09 (1H, d, J = 6.4, Ar). GC–MS (m/z) 162.
(b) J. March, Advanced Organic Chemistry, Reactions, Mechanisms,
and Structure, fourth ed., John Wiley & Sons, New York, 1992
(Chapter 15);
(c) J. Meinwald, J. Am. Chem. Soc. 77 (1955) 1617;
(d) P.E. Peterson, E.V.P. Tao, J. Org. Chem. 29 (1964) 2322;
(e) A.O. Fitton, R.K. Smalley, Practical Heterocyclic Chemistry,
Academic Press, New York, 1968, p. 16;
(f) C.D. Hurd, W.A. Hoffman, J. Org. Chem. 5 (1940) 212;
(g) A.B. Sen, R.P. Rastogi, J. Indian Chem. Soc. 30 (1953) 355;
(h) C.M. Evans, A.J. Kirby, J. Chem. Soc. Perkin Trans. 2 (1984)
1259.
3.11. 3-Methylphthalide (14)
1H NMR (CDCl3) d 1.64 (3H, d, J = 6.4, CH3), 5.57
(1H, q, J = 6.5, CH), 7.46 (1H, t, J = 7.6, Ar), 7.53 (1H,

T. Ohta et al. / Journal of Organometallic Chemistry 692 (2007) 671–677
677
´
[3] Photocatalytic, see: G. Frater, H. Schmid, Helv. Chim. Acta 50
(g) T. Hosokawa, T. Kono, T. Uno, S.-I. Murahashi, Bull. Chem.
Soc. Jpn. 59 (1986) 2191;
(1967) 255.
[4] (a) C.-G. Yang, N.W. Reich, Z. Shi, C. He, Org. Lett. 7 (2005) 4553–
4556;
(h) M.F. Semmelhack, C.R. Kim, W. Dobler, M. Meier, Tetrahedron
Lett. 30 (1989) 4925;
(b) J.-S. Ryu, T.J. Marks, F.E. McDonald, J. Org. Chem. 69 (2004)
1038–1052;
(i) S. Saito, T. Hara, N. Takahashi, M. Hirai, T. Morikawa, Synlett
(1992) 237.
(c) H. Qian, X. Han, R.A. Windenhoefer, J. Am. Chem. Soc. 126
(2004) 9536;
(d) S. Geresh, O. Levy, Y. Markovits, A. Shani, Tetrahedron 31
(1975) 2803–2807;
(e) M.F. Grundon, D. Stewart, W.E. Watts, J. Chem. Soc. Chem.
Commun. (1973) 573–574.
[9] (a) Intramolecular cyclization of amino-olefins with b-hydride elim-
ination, see: L.S. Hegedus, G.F. Allen, E.L. Waterman, J. Am.
Chem. Soc. 98 (1976) 2674;
(b) L.S. Hegedus, G.F. Allen, J.J. Bozell, E.L. Waterman, J. Am.
Chem. Soc. 100 (1978) 5800;
(c) L.S. Hegedus, J.M. McKearin, J. Am. Chem. Soc. 104 (1982)
2444;
[5] (a) C.-G. Yang, C. He, J. Am. Chem. Soc. 127 (2005) 6966–6967;
(b) M. Beller, J. Seayad, A. Tillack, H. Jiao, Angew. Chem., Int. Ed.
43 (2004) 3368–3398;
(d) P.J. Harrington, L.S. Hegedus, J. Org. Chem. 49 (1984) 2657.
[10] B. Pugin, L.M. Venanzi, J. Organomet. Chem. 214 (1981) 125.
[11] N. Oshima, H. Suzuki, Y. Morooka, Chem. Lett. (1984) 1161.
[12] (a) Our intermolecular addition to olefins, see: Y. Oe, T. Ohta, Y.
Ito, Chem. Commun. (2004) 1620–1621;
(b) Y. Oe, T. Ohta, Y. Ito, Synlett (2005) 179–181.
[13] D.E. Nichols, A.J. Hoffman, R.A. Oberlender, R.M. Riggs, J. Med.
Chem. 29 (1986) 302–304.
[14] F.C. Gozzo, S.A. Fernandes, D.C. Rodrigues, M.N. Eberlin, A.J.
Marsaioli, J. Org. Chem. 68 (2003) 5493–5499.
[15] V. De Felice, A. De Renzi, M. Funicello, A. Panunzi, A. Saporito,
Gazz. Chim. Ital. 115 (1985) 13–15.
[16] P. Yates, T.S. Macas, Can. J. Chem. 66 (1988) 1–10.
[17] S. Ozaki, M. Adachi, S. Sekiya, R. Kamikawa, J. Org. Chem. 68
(2003) 4586–4589.
[18] S. Chamoin, S. Houldsworth, V. Snieckus, Tetrahedron Lett. 39
(1998) 4175–4178.
[19] C.F.H. Allen, J.W. Gates, Org. Synth., Coll. III (1991) 198.
[20] N. Takamatsu, S. Inoue, Y. Kishi, Tetrahedron Lett. (1971) 4661–
4664.
[21] L.G. Beholz, J.R. Stille, J. Org. Chem. 58 (1993) 5095–5100.
[22] S. Jolidon, H.-J. Hansen, Helv. Chem. Acta 101 (1977) 978–
1032.
(c) T. Yoshida, T. Matsuda, T. Okano, T. Kitani, S. Otsuka, J. Am.
Chem. Soc. 101 (1979) 2027;
(d) H.E. Bryndza, J.C. Calabrese, S.S. Wreford, Organometallics 3
(1984) 1603;
(e) C.M. Jensen, W.C. Trogler, Science 233 (1986) 1069.
[6] (a) J. Zhang, C.G. Yang, C. He, J. Am. Chem. Soc. 128 (2006) 1798–
1799, and references are cited therein;
(b) A.M. Johns, M. Utsunomiya, C.D. Incarvito, J.F. Hartwig, J.
Am. Chem. Soc. 128 (2006) 1828–1839;
(c) J.F. Hartwig, Pure Appl. Chem. 76 (2004) 507–516.
[7] K. Hori, H. Kitagawa, A. Miyoshi, T. Ohta, I. Furukawa, Chem.
Lett. (1998) 1083–1084.
[8] (a) Wacker-type cyclization of 2-allylphenol, see: K.F. McDaniel, in:
E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.), Comprehensive
Organometallic Chemistry II, vol. 12, Pergamon, 1995, p. 601;
(b) T. Hosokawa, K. Maeda, K. Koga, I. Moritani, Tetrahedron
Lett. (1973) 739;
(c) T. Hosokawa, H. Ohkata, I. Moritani, Bull. Chem. Soc. Jpn. 48
(1975) 1533;
(d) T. Hosokawa, S. Miyagi, S.-I. Murahashi, A. Sonoda, J. Chem.
Soc. Chem. Commun. (1978) 687;
(e) T. Hosokawa, T. Uno, S.-I. Murahashi, J. Chem. Soc. Chem.
Commun. (1979) 475;
[23] J.P. Marino Jr., M.H. Osterhout, A.T. Price, S.M. Sheehan, A.
Padwa, Tetrahedron Lett. 35 (1994) 849–852.
(f) T. Hosokawa, M. Hirata, S.-I. Murahashi, A. Sonoda, Tetrahe-
dron Lett. (1976) 1821;
[24] M. Muehlstadt, K. Hollmann, R. Widera, Zeits. Chem. 28 (1988)
436.