Propargylic activation across a heterobimetallic ir-sn catalyst: Nucleophilic substitution and indene formation with propargylic alcohols

Article abstract of DOI:10.1021/jo100189z

(Figure presented) A nucleophilic substitution of propargylic alcohols with carbon (arene, heteroarene, and allyltrimethylsilane), sulfur (thiol), oxygen (alcohol), and nitrogen (sulfonamide) nucleophiles has been demonstrated using a high-valent [Ir(COD)

Full text of DOI:10.1021/jo100189z

pubs.acs.org/joc
Propargylic Activation Across a Heterobimetallic Ir-Sn
Catalyst: Nucleophilic Substitution and Indene Formation with
Propargylic Alcohols
Paresh Nath Chatterjee† and Sujit Roy*,†,‡
†Organometallics and Catalysis Laboratory, Chemistry Department, Indian Institute of Technology,
Kharagpur 721302, India, and Organometallics and Catalysis Laboratory, School of Basic Sciences,
Indian Institute of Technology, Bhubaneswar 751013, India
‡
royiitkgp@gmail.com; sroychem@iitbbs.ac.in
Received March 1, 2010
A nucleophilic substitution of propargylic alcohols with carbon (arene, heteroarene, and allyltri-
methylsilane), sulfur (thiol), oxygen (alcohol), and nitrogen (sulfonamide) nucleophiles has been
demonstrated using a high-valent [Ir(COD)(SnCl3)Cl(μ-Cl)]2 catalyst in 1,2-dichloroethane to afford
the corresponding propargylic products in moderate to excellent yields. Alkyl or aryl substituted
tertiary propargylic alcohols produce substituted indenes with bulky arenes via allenylic intermedi-
ate. An electrophilic mechanism is proposed from Hammett correlation.
Introduction
scaffold often results in selective substrate binding, dual and
synergistic activation, and higher efficiency toward coupl-
ing.6,7 Obviously, the success of such bimetallic catalysis
truly depends on the stereoelectronic features of and around
the two metals, and their ability to communicate during
substrate binding and activation. Our continuing success in
dual-reagent catalysis involving a transition metal partner
and tin as a main group metal partner8 led us to propose a
new heterobimetallic catalysis concept within the Ir-Sn
domain for the activation of different electrophiles, for
Heterobimetallic catalysis constitutes an important sub-
area within the broader domain of multimetallic catalysis.
The successful design of homogeneous heterobimetallic cat-
alysts is a topic of ongoing interest.1-5 This is mainly due to
the fact that the incorporation of two metals in a single
(1) Van den Beuken, E. K.; Feringa, B. L. Tetrahedron 1998, 54, 12985.
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Roy, S. J. Mol. Catal. A: Chem. 2006, 246, 231.
DOI: 10.1021/jo100189z
r
Published on Web 06/10/2010
J. Org. Chem. 2010, 75, 4413–4423 4413
2010 American Chemical Society

Chatterjee and Roy
JOCArticle
example, benzyl alcohols, ethers, and aldehydes.9 Keeping in
view the importance of metal-catalyzed activation of pro-
pargylic substrates (see later) and our own enthusiasm,10 we
became interested to test whether the heterobimetallic motif
is amenable toward propargylic activation. The success of
our endeavor is presented in this article, which demonstrates
the profound reactivity of the Ir-Sn catalyst [Ir(COD)-
(SnCl3)Cl(μ-Cl)]2 for the activation of propargylic alcohols
as electrophiles, bearing both terminal and internal alkyne
moieties, and their nucleophilic substitution with various
carbon (arene, heteroarene and allyltrimethylsilane), sul-
fur (thiol), oxygen (alcohol), and nitrogen (sulfonamide)
nucleophiles in a regioselective manner with high turnover
frequency (TOF). Additionally, the Ir-Sn catalyst is also
capable of steering a ring-closure with the formation of
1,3-substituted indenes from alkyl- and aryl-substituted
tertiary phenyl propargylic alcohols and bulky arenes like
1,3,5-trimethoxybenzene or 1-methoxynaphthalene, where
the steric factor possibly plays a pivotal role. Motifs bearing
indenes as core structures constitute an integral part of a
number of natural products and bioactive pharmaceutical
compounds.11 They are also well-exploited as building
blocks for functional materials12 and as ligands in metallo-
cene-based olefin polymerization catalysts.13
Transition-metal-catalyzed nucleophilic substitution reac-
tions involving propargylic alcohol and its surrogates remain
one of the demanding transformations because of the ease of
transposing the flexible alkyne moiety to a variety of func-
tional groups. Often the products of the propargylic sub-
stitution reactions are also interesting building blocks for
different complex natural product syntheses, for example, O-
methyldetrol, mimosifoliol, and β-apopicropodophyllin.14,15
In this context, one may note that there are few successful
reports of catalytic propargylic substitution reaction of
propargylic alcohols and their derivatives with carbon and
heteroatom-centered nucleophiles. A variety of transition
metals, such as Ru, Re, Rh, Ir, Ni, Pd, Pt, and Cu, form
organometallic species as intermediates, and several Lewis
acids and Brønsted acids are also applicable as catalysts in
these reactions.16 Likewise, many synthetic methods have
demonstrated the formation of indene skeletons from pro-
pargylic derivatives.17 Notably, it may be emphasized here
that, to the best of our knowledge, only four recent reports
are available where indenes are produced directly from
propargylic alcohols in the presence of Lewis acid catalysts.18
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Results and Discussions
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For model studies we had chosen 2-methyl-4-phenyl-but-
3-yn-2-ol 1a (having β-H) as representative alcohol and
anisole 2a as the arene in the presence of 1 mol % of
IrIII-SnIV bimetallic catalyst and in 1,2-dichloroethane
(DCE) as solvent. Initial catalyst screening included both
heterobimetallic and monometallic catalysts (Table 1).
The catalytic efficiency of the Ir-Sn heterobimetallic
catalyst [Ir(COD)(SnCl3)Cl(μ-Cl)]2 was highest and the de-
sired propargylic product 3aa was obtained in 75% yield
after 3 h (Table 1, entry 1). Other heterobimetallic catalysts
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4414 J. Org. Chem. Vol. 75, No. 13, 2010

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JOCArticle
SCHEME 1. Propargylation Reaction: Model Study with Alcohol 1a and Arene 2a
TABLE 2. Reactions of Various Propargylic Alcohols 1 with Nucleophiles 2a
bearing the Ir-Sn and Rh-Sn motif also promoted the
reaction but at varying efficiencies (entries 2-5). In contrast,
individually [Ir(COD)(μ-Cl)]2 was inactive, while SnCl4 was
poorly active. Even IrCl3 and cationic Ir(I) species [Ir(COD)-
(sol)]PF6 showed very low efficiency (entries 6-9). Both iron
and bismuth chlorides also promoted the reaction (entries
10 and 11).
TABLE 1. Propargylation of Anisole 2a with Propargyl Alcohol 1a:
Effect of Catalysta
entry
1, R1; R2; R3
Nu-H time (min) yield of 3 (%)
Carbon Nucleophiles
1
2
3
4
5
6
7
8
1b, H; 4-MeC6H4; Ph
1b
1c, H; 4-ClC6H4; Ph
1c
1d, H; 4-MeC6H4; H
1d
1a, Me; Me; Ph
1a
1e, H; Me; Ph
1f, Me; Et; Ph
1b
1b
1b
1d
1c
1b
2b
2c
2a
2d
2b
2e
2f
2g
2h
2i
2i
2j
2k
2f
2k
2l
30
30
40
15
60
60
720
75
360
60
30
30
30
1200
40
30
30
30
80
45
60
3bb, 92
3bc, 85
3ca, 81
3cd, 96
3db, 75
3de, 77
3af, 75b
3ag, 72
3eh, 52c
3fi, 78
3bi, 85
3bj, 83
3bk, 90
3df, 70b
3ck, 87
3bl, 95
3cl, 91
3gl, 85
3dl, 75
3hl, 89
3il, 80
entry
catalyst
yield of 3aa (%) TOF (h-1
)
1
2
3
4
5
6
7
8
[Ir(μ-Cl)(COD)Cl(SnCl3)]2
[Ir(μ-Br)(COD)Br(SnBr3)]2
[Rh(μ-Cl)(COD)Cl(SnCl3)]2
[Rh(μ-Br)(COD)Br(SnBr3)]2
IrCl(CO)(PPh3)2(SnCl4)
[Ir(COD)(μ-Cl)]2
[Ir(COD)(sol)]PF6
IrCl3
75
60
49
41
7
0
15
5
25.0
20.0
16.3
13.7
2.3
9
10
11
12
13
14
15
16
17
18
19
20
21
0
5.0b
1.6
9
10
11
SnCl4
FeCl3
BiCl3
10
59
42
3.3
19.7
1c
1g, Me; 4-MeC6H4; Ph
1d
1h, H; 4-MeC6H4; n-Bu
1i, H; 4-ClC6H4; TMS
2l
2l
2l
2l
14.0c
aUnless otherwise mentioned, reaction conditions are the following:
alcohol 1a (0.25 mmol), anisole 2a (0.75 mmol), catalyst (0.0025 mmol),
solvent DCE (1 mL), 60 °C for 3 h. bsol = MeCN. c1 mol % BiCl3 was
used from a stock solution of BiCl3 in MeCN.
2l
Sulfur Nucleophiles
22
23
24
25
1f
1j, H; Ph; Ph
1d
1g
2m
2n
2o
2p
45
30
75
30
3fm, 82
3jn, 75
3do, 79
3gp, 90
A reaction conducted at 80 °C using [Ir(COD)(SnCl3)-
Cl(μ-Cl)]2 as the catalyst and alcohol/arene ratio as 1:3
resulted in 78% of 3aa along with about 10% of the
eliminated product 4 after 75 min (Scheme 1). Under similar
conditions, but with an alcohol/arene ratio of 1:1.5, the
yields of 3aa and 4 were 62 and 29%, respectively, after 2 h.
Next we examined the propargylic substitution using
various propargylic alcohols and arenes, heteroarenes, allyl-
trimethylsilane, and heteroatom-centered nucleophiles in
DCE at 80 °C in the presence of 1 mol % of catalyst. For
convenience, the alcohol/nucleophile molar ratio was kept at
1:3, and the corresponding propargylic products were iso-
lated in moderate to good yields (Table 2).
Propargylic alcohols bearing internal as well as terminal
alkyne groups smoothly underwent the coupling reaction
with electron-rich arenes and heteroarenes (Table 2, entries
1-15) with complete regioselectivity. Friedel-Crafts arylated
products were isolated in excellent yields during the reaction
of anisole, 1,2-dimethoxybenzene, 1,3,5-trimethoxybenzene,
and 1-methoxynaphthalene with alcohols 1b and 1c (Table 2,
entries 1-4). Propargylic alcohol bearing a terminal alkyne
group gave lower yields with 1,3-dimethoxybenzene and
1-methoxynaphthalene (Table 2, entries 5 and 6). Propargy-
lation occurred with complete regioselectivity in the case of
Oxygen Nucleophiles
26
27
28
1a
1a
1j
2q
2r
2s
600
240
180
3aq, 60
3ar, 75
3js, 70
Nitrogen Nucleophiles
29
30
31
1a
1b
1j
2t
2u
2t
90
50
50
3at, 80
3bu, 95
3jt, 90
aUnless otherwise mentioned, reaction conditions were as follows:
alcohol (0.25 mmol), nucleophile (0.75 mmol), Ir-Sn cat. (0.0025
mmol), solvent DCE (1 mL), 80 °C. bAlcohol (0.25 mmol), furan (5.0
mmol), Ir-Sn cat. (0.0025 mmol), solvent DCE (1 mL), room tempera-
ture. cRatio of the isomers of 3eh is 3:1 [particular isomers could not be
identified from NMR]:
heteroarenes, for example, thiophene, furan, benzo[b]furan,
2-methylfuran, 2-methylthiophene, and 3-methylthiophene
J. Org. Chem. Vol. 75, No. 13, 2010 4415

Chatterjee and Roy
JOCArticle
CHART 1. Active Nucleophiles for Propargylation Reactiona
aThe position of substitution is indicated by the truncated bond.
SCHEME 2. Meyer-Schuster-Type Rearrangement vs Etherification of Tertiary Propargylic Alcohol 1a in the Presence of Ethanol:
Dependence of Temperature
in moderate to excellent yield (Table 2, entries 7, 8, and
10-15). Secondary aliphatic substrate 1e reacted sluggishly
to give only 52% of the desired product 3eh and as a mixture
of regioisomers (Table 2, entry 9). Because of the lower
boiling point of furan, we used furan 2f (Chart 1) in excess
(20 equiv with respect to alcohol) and the reaction was
conducted at room temperature. In case of tertiary aliphatic
alcohols 1a and 1f, desired propargylic products were
obtained in moderate yields along with a small amount of
eliminated product ( β-H elimination; Table 2, entries 7, 8,
and 10). In all the cases, propargylation took place at the
electron-rich center of the aromatic compounds. It may be
mentioned that our attempts to activate alkyl-substituted
aromatics using the bimetallic catalyst failed.
R3 = Ph) did not offer any coupling reaction with aromatic
compounds as well as allytrimethylsilane in presence of the
catalyst.
To explore the generality of the reaction further, we briefly
examined the reaction of alcohols 1a, 1b, 1d, 1f, 1g, and 1j
with representative sulfur, oxygen, and nitrogen nucleo-
philes (Table 2, entries 22-31). Generally sulfur-containing
compounds are potential catalyst poisons due to their strong
coordinating properties.20,21 However, we could successfully
construct a C(sp3)-S bond by the nucleophilic substitution
of propargylic alcohols with varieties of thiols using 1 mol %
of IrIII-SnIV catalyst. No Friedel-Crafts arylated product
was obtained while using thiophenol 2o as a nucleophile, and
the propargylic sulfide 3do was the only product (Table 2,
entry 24). Facile reaction of 1f and 1g with 1-propanethiol
2m and tert-butanethiol 2p resulted in the formation of
desired product 3fm and 3gp, respectively, with excellent
yield. Propargylation of mercaptoethanol 2n was 100%
S-selective over competitive O-alkylation (Table 2, entry
23). Similar reactions of propargylic alcohols with O-nucleo-
philes were briefly examined and the desired ethers were
obtained in moderate yields (Table 2, entry 26-28). Both
aryl- and alkyl-substituted propargylic alcohols 1a and 1j
underwent propargylic etherification to afford propargylic
ethers in moderate yields with ethanol, hex-2-en-1-ol, and
3-phenylpropan-1-ol (2q-2s). Notably, in the presence of
ethanol as nucleophile, rearranged enone 6 was isolated from
1a as the sole product at 80 °C.19,22 Upon reducing the
temperature to 45 °C, the desired ether 3aq along with
R,β-unsaturated ketone 6 were obtained in a 2:1 ratio
(Scheme 2). The formation of 6 could not be stopped even
on further lowering of temperature to 25 °C. The reaction of
With the bimetallic IrIII-SnIV catalyst we next explored
the coupling reactions of various propargylic alcohols with
allyltrimethylsilane 2l as a nucleophile. We were pleased
to find that only 1 mol % of the catalyst in DCE at 80 °C
successfully produced the substituted 1,5-enynes in excellent
yields and no R,β-unsaturated ketones via the Meyer-
Schuster-type rearrangement were detected.19 The bimetallic
complex efficiently catalyzed the substitution reaction of
various aryl- and alkyl-substituted propargylic alcohols with
excellent yields (Table 2, entries 16-21). We also noted that
the reaction can tolerate moisture or air without comprising
product yield. Substituents in the alkyne moiety, such as aryl,
alkyl, or trimethylsilane (1b-d, 1g-i) did not affect the
course of the reaction. Propargylic alcohol 1d bearing a
terminal alkyne moiety was also allylated successfully
(Table 2, entry 19) without any polymerization. The primary
propargylic alcohol 3-phenylprop-2-yn-1-ol (R1 = R2 = H,
(19) Several catalysts have been employed to carry out the conversion
of propargyl alcohols to enones (Meyer-Schuster rearrangement), see
(a) Narasaka, K.; Kusama, H.; Hayashi, Y. Tetrahedron 1992, 48, 2059.
(b) Yoshimatsu, M.; Naito, M.; Kawahigashi, M.; Shimizu, H.; Kataoka, T.
J. Org. Chem. 1995, 60, 4798. (c) Lorber, C. Y.; Osborn, J. A. Tetrahedron
Lett. 1996, 37, 853. (d) Fukuda, Y.; Utimoto, K. Bull. Chem. Soc. Jpn. 1991,
64, 2013.
(20) Inada, Y.; Nishibayashi, Y.; Hidai, M.; Uemura, S. J. Am. Chem.
Soc. 2002, 124, 15172.
(21) Hegedus, L. L.; McCabe, R. W. Catalyst Poisoning; Marcel Dekker:
New York, 1984.
(22) Georgy, M.; Boucard, V.; Campagne, J. M. J. Am. Chem. Soc. 2005,
127, 14180.
4416 J. Org. Chem. Vol. 75, No. 13, 2010

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JOCArticle
SCHEME 3. Propargylation vs Indene Formation: Dependence of Both Propargylic Alcohol and Arene
propargylic alcohols with N-nucleophiles such as aniline,
N,N-dimethylaniline, acetamide, and piperidine led to the
formation of complex mixtures. Lesser nucleophilic sub-
strates such as sulfonamides were amenable for the transfor-
mation. Thus, the reactions of alcohols 1a, 1b, and 1j with
p-toluenesulfonamide 2t and benzene sulfonamide 2u af-
forded the corresponding propargylated products in excel-
lent yields (Table 2, entries 29-31).
[Ir-Sn] catalyst [Ir(μ-Cl)(COD)Cl(SnCl3)]2, (iii) PhSnCl3 as
a representative Sn(IV) species, and (iv) [IrCp*Cl2]2 as a
representative Ir(III) species. The results are briefly high-
lighted: (1) In the absence of any reagent, both the -CH and
-OH protons of 1j appeared as a doublet at 5.45 and 1.64
ppm, respectively, with a coupling constant of 6.0 Hz. The
coupling between -CH and -OH protons was also sup-
ported by the COSY spectrum (see Supporting Information).
(2) Upon the addition of the [Ir-Sn] catalyst, the initial
doublet of the -CH proton of 1j was converted to a singlet at
5.45 ppm, while the -OH proton became a broad singlet.
The COSY spectrum clearly indicated the absence of cou-
pling between the -CH and the -OH proton. (3) In presence
of PhSnCl3, the initial doublet of the -CH proton of 1j was
converted to a singlet at 5.44 ppm. The COSY spectrum also
indicated the absence of coupling between the -CH and the
-OH proton. (4) In the presence of [IrCp*Cl2]2, the features
of -CH and -OH protons of 1j did not show any change
from the original spectra.
From the above studies we conclude that the preactivation
of the propargylic alcohol across the [Ir-Sn] catalyst in-
volves initial coordination of the alcoholic -OH group at the
hard Sn-center. Because Ir(III) alone does not influence
either the propargylation reaction or the NMR features of
1j, we therefore suggest that the enhanced efficiency of the
[Ir-Sn] catalyst in our case could be due to the higher Lewis
acidity of the IrIII-SnIV bond compared to Sn(IV) alone. We
are yet to understand the exact nature of the electronic
perturbation in the metal-metal bond that causes the en-
hancement in Lewis acidity.
FIGURE 1. Hammett plot of log(kR/kH) vs σpþ for propargylation
of anisole with propargylic alcohols p-R-C6H4-CtC-C(Me)2OH
(R = Et, Me, H, Cl, COMe).
To test the likelihood of an electrophilic propargylation
mechanism, we subjected the reaction to Hammett analysis
and evaluated the reaction constant (F value). This was
attempted by kinetic analysis using GC for the reaction of
anisole 2a with five different para-substituted propargylic
alcohols p-R-C6H4-CtC-C(Me)2OH (R = Et, Me, H, Cl,
COMe) at 70 °C (details in the Supporting Information). The
Hammett plot (Figure 1) resulted in a moderately negative
F-value (-1.45). It indicates the possibility of the generation
of a weak positive charge (δþ) at the propargylic carbon due
to the interaction of the alcohol with the bimetallic catalyst.
To gain preliminary insight into the initial activation of the
propargylic alcohol across the [Ir-Sn] heterobimetallic cata-
lyst, we undertook in situ 1D and 2D 1H NMR studies using
a representative alcohol PhCtCCH(Ph)OH (1j). The spec-
trum of 2n was recorded in C6D6 solvent in the absence of any
reagent, as well as in the presence of (ii) heterobimetallic
While extending the scope of the propargylation reaction,
we had yet another interesting observation (Scheme 3).
Secondary propargylic alcohol 1e reacted with a sterically
bulky arene such as 1,3,5-trimethoxybenzene 2d, providing
the desired propargylic product 3ed in low yield (48%). In
contrast, tertiary propargylic alcohol 1a reacted with 2d,
resulting in the exclusive formation of 1,3-substituted indene
5ad (80%), which may go via an allene intermediate.18d
The influence of the steric effect in guiding the reaction
became evident from the reaction of 1a with isomeric arene
1,2,3-trimethoxybenzene 2v, which afforded the desired pro-
pargylic product 3av (78%).
The generality of the indene formation reaction was
explored using aryl- and alkyl-substituted tertiary phenyl
propargylic alcohols 1a, 1f, 1g, 1k, 1l, 1m, 1n, and 1o with
bulky arenes such as 2b and 2d (Table 3, entries 1-8).
The structures of 5ad and 5kd were established by X-ray
J. Org. Chem. Vol. 75, No. 13, 2010 4417

Chatterjee and Roy
JOCArticle
TABLE 3. Reaction of Tertiary Propargylic Alcohol 1 with Bulky Arenes 2a
entry
1, R1; R2; R3
1a, Me; Me; H
1f, Me; Et; H
1g, Me; 4-MeC6H4; H
1k, Me; Me; CꢀC-C(Me)2OH
1l, Me; iso-Bu; H
1m, Ph; 4-MeC6H4; H
1n, Me; Me; Me
1o, Me; Me; OMe
1q, Me; Me; Cl
Ar-H
time (min)
yield of 5 (%)
1
2
3
4
5
6
7
8
9
2d
2b
2d
2d
2b
2d
2d
2b
2d
75
75
45
60
50
30
45
45
75
5ad, 80
5fb, 82
5gd, 91
5kd, 75
5lb, 80
5md, 92
5nd, 85
5ob, 87
b
aUnless otherwise mentioned, reaction conditions were as follows: alcohol (0.25 mmol), nucleophile (0.75 mmol), Ir-Sn cat. (0.0025 mmol), solvent
DCE (1 mL), 80 °C. bResulted in a complex mixture; the desired indene was not obtained.
SCHEME 4. Plausible Mechanism of Indene Formation Reaction
crystallographic analysis (Supporting Information). How-
ever, reaction of an aryl-substituted propargylic alcohol 1q
bearing an electron withdrawing halide substituent at the
arene ring with 2d led to an undefined complex mixture
(entry 9).
A preliminary proposal for the formation of indene via the
intermediacy of an allenyl species is shown in Scheme 4. The
proposal invokes prior activation of propargylic alcohol via
coordination at the hard Lewis acidic Sn(IV) center of the
catalyst, resulting in intermediate A, which can act as an
ambient electrophile. Due to steric reasons, a bulkier arene
would attack at the less crowded acetylenic center23 rather
than the more crowded tertiary propargylic center, leading to
the intermediate B. Indene 5 would result via subsequent
intramolecular hydroarylation of species C and rearomati-
zation of species D. Thus, the unfavorable steric interactions
between the substituents of the electrophiles and the incom-
ing nucleophiles govern the observed regioselection in the
product.
(23) For similar regioselectivties observed in other reactions with pro-
pargylic cations, see (a) Yoshimatsu, M.; Yamamoto, T.; Sawa, A.; Kato, T.;
Tanabe, G.; Muraoka, O. Org. Lett. 2009, 11, 2952. (b) Huang, W.; Shen,
Q. S.; Wang, J. L.; Zhou, X. G. J. Org. Chem. 2008, 73, 1586. (c) Sanz, R.;
To gain support on the proposed pathway, we monitored
the reaction of propargylic alcohol 1a with arene 2d in the
presence of 1 mol % of the catalyst in DCE at 45 °C for 3.5 h
by 1H NMR spectroscopy (Scheme 5). The signals due to the
ꢀ
ꢀ
Miguel, D.; Martınez, A.; Gutierrez, J. M. A.; Rodrıguez, F. Org. Lett. 2007,
9, 727. (d) Ishikawa, T.; Aikawa, T.; Mori, Y.; Saito, S. Org. Lett. 2003, 5, 51.
(e) Ishikawa, T.; Okano, M.; Aikawa, T.; Saito, S. J. Org. Chem. 2001, 66,
4635.
4418 J. Org. Chem. Vol. 75, No. 13, 2010

Chatterjee and Roy
JOCArticle
SCHEME 5. Reaction of Tertiary Propargylic Alcohol 1a with Bulky Arene 2d for an In Situ 1H NMR Study
[Ir(COD)(SnCl3)Cl(μ-Cl)]2 catalyst, and the nucleophilic sub-
stitution of both internal and terminal propargylic alcohols can
be achieved with various carbon (arene, heteroarene, and
allyltrimethylsilane), sulfur (thiol), oxygen (alcohol), and nitro-
gen (sulfonamide) nucleophiles, leading to a normal propargylic
product with high regioselectivity. In parallel, the bimetallic
catalyst can steer the reaction between a bulky arene and a
substituted tertiary phenyl propargylic alcohol to yield an indene
via the intermediacy of allene as an intermediate. By virtue of
their generality, selectivity, and efficiency, the catalytic reactions
presented in this article could be a meaningful addition to the
existing methods of propargylic functionalization as well as for
the synthesis of substituted indenes.
Experimental Section
General Methods. 1H NMR spectra were recorded at 400 and
200 MHz. Chemical shifts are reported in ppm from tetra-
methylsilane, with the solvent resonance as the internal standard
(chloroform: δ 7.26 ppm). Data are reported as follows: chemi-
cal shifts, multiplicity (s = singlet, d = doublet, t = triplet, q =
quartet, br=broad, dd=double doublet, dt=doublet of triplet,
td = triplet of doublet, m = multiplet), integration, coupling con-
stant (Hz). 13C NMR spectra were recorded at 100 MHz and
54.6 MHz with proton decoupling. Chemical shifts are reported in
ppm from tetramethylsilane with the solvent resonance as the
internal standard (chloroform: δ 77.0 ppm). ESI-MS experiments
were conducted at þve ionization mode. Melting points are un-
corrected. GC analysis was performed using a flame ionization
detector and 30 m ꢁ 0.25 mm ꢁ 0.25 μm SS 100% dimethyl poly-
siloxane capillary column. n-Nonane was used as internal standard.
The X-ray diffraction intensity data were collected at 293 K using a
CCD diffractometer.
FIGURE 2. Time evolution of allene and indene 5ad in the reaction
of alcohol 1a (0.25 mmol) with arene 2d (0.75 mmol) catalyzed by
the IrIII-SnIV complex at 45 °C. Inset shows the zoomed portion of
the main plot highlighting the allene and indene formation.
SCHEME 6. Cyclization of Tetra-Substituted Allene to Indene
by IrIII-SnIV Catalyst
All reactions were carried out under an argon atmosphere in
flame-dried glassware using Schlenk techniques. Chromatographic
purifications were done using either 60-120 or 100-200 mesh
silica gel. For reaction monitoring, precoated silica gel 60 F254 TLC
sheets were used. Petroleum ether refers to the fraction boiling in
the range 60-80 °C. 1,2-Dichloroethane (DCE) was dried and
methyl protons (-CH3) of alcohol 1a (δ 1.6 ppm), allenyl
intermediate (δ 1.8 ppm),24 and indene 5ad (δ 1.4 ppm) were
chosen for the study, which was monitored against triphe-
nylmethane as the internal standard. From the data, the time
evolution of the reactant and product was plotted (Figure 2).
It was found that, in the first part of the reaction, allene was
formed more rapidly than the product 5ad and reached a
maximum at 8 min. Thereafter, the yield of allene decreased,
while the yield of product 5ad increased.
To further test our proposal on the plausible interplay of
the allenyl intermediate, we reacted the tetra-substituted
allene Ph(Et)CdCdC(Me)2 7 in the presence of 1 mol %
catalyst in DCE at 80 °C. Gratifyingly, this led to the
corresponding indene 5x in 55% yield within 1 h (Scheme 6).
distilled prior to use. IrCl3 xH2O, 1,5-cyclooctadiene, and tin tetra-
3
chloride were commercially available. [Ir(COD)(μ-Cl)]2 and the
heterobimetallic catalyst [Ir(COD)(SnCl3)Cl(μ-Cl)]2 were pre-
pared following literature methods.9a,25 The propargylic alco-
hols, namely, 1b, 1c, 1f, 1g, 1h, 1i, 1j, 1l, and 1m were prepared
according to the literature.26 Another set of propargylic alco-
hols, for example, 1a, 1e, 1k, 1n, 1o, 1p, 1q, and 1r were also
prepared according to a previously reported procedure.10d
General Procedure. The following typical procedure has been
adopted for the synthesis of all the propargylic as well as indene
products.
Typical Procedure for the Propargylation of Anisole 2a with
2-Methyl-4-phenyl-but-3-yn-2-ol 1a Using [IrIII-SnIV] Catalyst.
A 10 mL Schlenk flask equipped with a magnetic bar was
Conclusions
In summary, we have shown that propargylic alcohols can
be activated in a facile manner by the heterobimetallic
(25) Walter, R.; Kirchner, S.; Franz, R. U.S. Patent 6,399,804, 2002.
(26) Spee, M. P. R.; Boersma, J.; Meijer, M. D.; Slagt, M. Q.; Koten, G.;
Geus, J. W. J. Org. Chem. 2001, 66, 1647.
(24) Zhang, H.; Fu, X.; Chen, J.; Wang, E.; Liu, Y.; Li, Y. J. Org. Chem.
2009, 74, 9351.
J. Org. Chem. Vol. 75, No. 13, 2010 4419

Chatterjee and Roy
JOCArticle
charged with [Ir(COD)(SnCl3)Cl(μ-Cl)]2 (3 mg, 0.0025 mmol),
anisole 2a (82 μL, 0.75 mmol), and 1,2-dichloroethane (1 mL).
The flask was degassed with argon and placed into a constant
temperature bath at 80 °C. After the mixture was stirred vigo-
rously for 5 min, 2-methyl-4-phenyl-but-3-yn-2-ol 1a (40 mg,
0.25 mmol) was added to it and the reaction was allowed to
continue at 80 °C (TLC monitoring; petroleum ether 60-80 °C/
ethylacetate 19:1 v/v). Following completion of the reaction,
solvent was removed under reduced pressure, and the mix-
ture was subjected to column chromatography over silica gel
(100-200 mesh, eluent: petroleum ether 60-80 °C/ethylacetate
49:1 v/v) to afford a corresponding propargylic product 3aa as a
light yellow oil in 78% isolated yield.
Analytical Data of Products. 1-Methoxy-4-(2-methyl-4-phe-
nylbut-3-yn-2-yl)benzene (3aa). 1H NMR (400 MHz, CDCl3): δ
(ppm) 1.66 (s, 6H), 3.81 (s, 3H), 6.88 (dd, 2H, J = 8.8 and 2.0
Hz), 7.29-7.33 (m, 3H), 7.45 (d, 2H, J = 7.2 Hz), 7.54 (dd, 2H,
J = 8.8 and 2.0 Hz). 13C NMR (100 MHz, CDCl3): 31.8, 35.7,
55.2, 81.8, 96.7, 113.5, 123.8, 126.6, 127.6, 128.1, 131.5, 139.2,
158.0. DEPT-135: 31.8, 55.2, 113.5, 126.6, 127.6, 128.1, 131.5.
HRMS (ESI) Calcd for C18H18O þ Hþ, 251.1436; found,
251.1417.
1-Methoxy-4-(1-p-tolylprop-2-ynyl)naphthalene (3db). Pale
yellow oil. 1H NMR (400 MHz, CDCl3): δ (ppm) 2.30 (s, 3H),
2.49 (d, 1H, J = 2.8 Hz), 4.01 (s, 3H), 5.59 (d, 1H, J = 2.8 Hz),
6.79 (d, 1H, J = 8.0 Hz), 7.09 (d, 2H, J = 7.6 Hz), 7.27 (d, 2H,
J = 8.0 Hz), 7.42-7.47 (m, 2H), 7.54 (d, 1H, J = 7.6 Hz),
7.94-7.97 (m, 1H), 8.28-8.31 (m, 1H). 13C NMR (100 MHz,
CDCl3): 20.9, 39.1, 55.4, 72.8, 85.1, 103.1, 122.5, 123.7, 124.8,
126.1, 126.4, 126.5, 127.6, 128.1, 129.1, 131.5, 136.4, 137.7,
155.1. HRMS (ESI) Calcd for C21H18O þ Hþ, 287.1436; found,
287.1426.
2,4-Dimethoxy-1-(1-p-tolylprop-2-ynyl)benzene (3de). Color-
less oil. 1H NMR (200 MHz, CDCl3): δ (ppm) 2.31 (s, 3H), 2.37
(d, 1H, J = 2.8 Hz), 3.82 (s, 6H), 5.36 (d, 1H, J = 2.8 Hz),
6.43-6.51 (m, 2H), 7.09 (d, 2H, J = 8.0 Hz), 7.28 (d, 2H, J = 8.0
Hz), 7.41 (d, 1H, J = 8.2 Hz). 13C NMR (54.6 MHz, CDCl3):
21.0, 34.9, 55.3, 55.5, 71.1, 85.7, 98.6, 104.5, 122.4, 127.5, 129.0,
129.2, 136.0, 138.5, 157.0, 159.9. DEPT-135: 21.0, 34.9, 55.3,
55.5, 71.1, 98.6, 104.5, 127.5, 129.0, 129.2. HRMS (ESI) Calcd
for C18H18O2 þ Hþ, 267.1385; found, 267.1388.
2-(2-Methyl-4-phenylbut-3-yn-2-yl)furan (3af). Yellow oil. 1H
NMR (400 MHz, CDCl3): δ (ppm) 1.66 (s, 6H), 6.23 (d, 1H, J =
3.2 Hz), 6.31 (dd, 1H, J = 3.2 and 2.0 Hz), 7.27-7.28 (m, 3H),
7.36 (d, 2H, J = 2.0 Hz), 7.40-7.44 (m, 2H). 13C NMR (100
MHz, CDCl3) 29.0, 32.6, 80.7, 94.1, 103.7, 109.9, 123.4, 127.7,
128.1, 131.6, 141.4, 158.9. DEPT-135: 29.0, 103.7, 109.9, 127.7,
128.1, 131.6, 141.4. Anal. Calcd (C15H14O): C, 85.68; H, 6.71.
Found: C, 85.58; H, 6.75.
(3-Methylbut-3-en-1-ynyl)benzene (4)27. 1H NMR (200 MHz,
CDCl3): δ (ppm) 1.99 (s, 3H), 5.30 (d, 1H, J = 3.2 Hz), 5.40 (d,
1H, J = 3.2 Hz), 7.29-7.32 (m, 3H), 7.42-7.47 (m, 2H). 13C
NMR (54.6 MHz, CDCl3): 23.5, 88.4, 90.5, 121.9, 123.2, 126.8,
128.1, 128.2, 131.5. DEPT-135: 23.5, 121.9, 128.1, 128.2, 131.5.
1-Methoxy-4-(3-phenyl-1-p-tolylprop-2-ynyl)naphthalene (3bb).
2-(2-Methyl-4-phenylbut-3-yn-2-yl)benzofuran (3ag). White
solid. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.76 (s, 6H), 6.66
(s, 1H), 7.18-7.30 (m, 6H), 7.43-7.51 (m, 3H). 13C NMR (100
MHz, CDCl3): 28.8, 33.0, 81.2, 93.4, 100.8, 111.0, 120.6, 122.5,
123.2, 123.5, 127.8, 128.1, 128.5, 131.6, 154.8, 162.0. DEPT-135:
28.8, 100.8, 111.0, 120.6, 122.5, 123.5, 127.8, 128.1, 131.6.
HRMS (ESI) Calcd for C19H16O þ Hþ, 261.1279; found,
261.1278.
1
Pale yellow oil. H NMR (400 MHz, CDCl3): δ (ppm) 2.31 (s,
3H), 4.01 (s, 3H), 5.79 (s, 1H), 6.81 (d, 1H, J = 8.0 Hz), 7.10 (d,
2H, J = 7.6 Hz), 7.27-7.29 (m, 3H), 7.33 (d, 2H, J = 7.6 Hz),
7.43-7.49 (m, 4H), 7.59 (d, 1H, J = 8.0 Hz), 8.06 (d, 1H,
J = 7.6 Hz), 8.31 (d, 1H, J = 7.6 Hz). 13C NMR (100 MHz,
CDCl3): 21.1, 40.1, 55.4, 84.8, 90.9, 103.2, 122.6, 123.7, 124.1,
124.9, 126.1, 126.6, 126.7, 127.8, 128.2, 128.9, 129.2, 131.6, 131.8,
136.3, 138.4, 155.1. DEPT-135: 21.1, 40.1, 55.4, 103.2, 122.6,
124.1, 124.9, 126.6, 126.7, 127.8, 128.2, 129.2, 131.8. HRMS(ESI)
Calcd for C27H22O þ Hþ, 363.1749; found, 363.1740.
Methyl-(4-phenylbut-3-yn-2-yl)thiophene (3eh): Mixture of
1
2- and 3-Regioisomers. H NMR (400 MHz, CDCl3): δ (ppm)
1.63 (d, 3H, J = 7.2 Hz), 2.45 (s, 3H), 4.16 (q, 1H, J = 7.2 Hz),
6.58 (d, 1H, J = 3.2 Hz), 6.80 (d, 1H, J = 3.2 Hz), 7.27-7.29 (m,
3H), 7.42-7.45 (m, 2H). Minor isomer: 1.52 (d, 3H, J = 7.2 Hz),
2.47 (s, 3H), 4.01 (q, 1H, J = 7.2 Hz), 7.03 (d, 1H, J = 5.2 Hz),
7.09 (d, 1H, J = 5.2 Hz). 13C NMR (100 MHz, CDCl3; major þ
minor isomers): 12.8, 15.3, 22.9, 24.3, 25.9, 27.9, 81.1, 81.8, 91.9,
92.6, 117.8, 121.3, 123.3, 123.4, 123.6, 124.5, 125.1, 127.3, 127.6,
127.7, 127.8, 128.1, 128.2, 131.5, 131.6, 138.2, 138.2, 144.5.
HRMS (ESI) Calcd for C15H14S þ Hþ, 227.0894; found,
227.0898.
2-Methyl-5-(3-methyl-1-phenylpent-1-yn-3-yl)furan (3fi). Col-
orless oil. 1H NMR (400 MHz, CDCl3): δ (ppm) 0.97 (t, 3H, J =
7.2 Hz), 1.59 (s, 3H), 1.79-1.86 (m, 1H), 1.90-1.97 (m, 1H),
2.28 (s, 3H), 5.87 (d, 1H, J = 3.2 Hz), 6.14 (d, 1H, J = 3.2 Hz),
7.27-7.30 (m, 3H), 7.40-7.45 (m, 2H). 13C NMR (100 MHz,
CDCl3): 9.7, 13.6, 26.9, 34.4, 37.7, 81.8, 93.2, 105.6, 105.8, 123.7,
127.7, 128.1, 131.6, 150.9, 156.0. DEPT-135: 9.7, 13.6, 26.9,
34.4, 105.6, 105.8, 127.7, 128.1, 131.6. Anal. Calcd (C17H18O):
C, 85.67; H, 7.61. Found: C, 85.49; H, 7.65.
1,2-Dimethoxy-4-(3-phenyl-1-p-tolylprop-2-ynyl)benzene (3bc).
Pale yellow oil. 1H NMR (400 MHz, CDCl3): δ (ppm) 2.33 (s,
3H), 3.85 (s, 3H), 3.86 (s, 3H), 5.13 (s, 1H), 6.82 (d, 1H, J = 8.8
Hz), 6.97 (d, 2H, J = 6.0 Hz), 7.13 (d, 2H, J = 8.0 Hz),
7.29-7.33 (m, 5H), 7.46-7.48 (m, 2H). 13C NMR (100 MHz,
CDCl3): 20.9, 42.8, 55.8 (2), 84.5, 90.5, 111.1, 111.2, 119.8, 123.5,
127.6, 127.8, 128.1, 129.2, 131.6, 134.4, 136.4, 138.9, 147.8,
148.9. DEPT-135: 20.9, 42.8, 55.8 (2), 111.1, 111.2, 119.8,
127.6, 127.8, 128.1, 129.2, 131.5. HRMS (ESI) Calcd for
C24H22O2 þ Hþ, 343.1698; found, 343.1693.
1-Chloro-4-(1-(4-methoxyphenyl)-3-phenylprop-2-ynyl)ben-
zene (3ca). Colorless oil. 1H NMR (400 MHz, CDCl3): δ (ppm)
3.79 (s, 3H), 5.14 (s, 1H), 6.87 (d, 2H, J = 8.4 Hz), 7.27-7.37 (m,
9H), 7.44-7.48 (m, 2H). 13C NMR (100 MHz, CDCl3): 42.3,
55.2, 85.1, 89.9, 113.9, 123.3, 128.1, 128.3, 128.7, 128.8, 129.2,
131.2, 131.6, 133.4, 140.6, 158.6. DEPT-135: 42.3, 55.2, 113.9,
128.1, 128.3, 128.7, 128.8, 129.2, 131.6. HRMS (ESI) Calcd for
C22H17ClO þ Hþ, 333.1046; found, 333.1040.
2-(1-(4-Chlorophenyl)-3-phenylprop-2-ynyl)-1,3,5-trimethoxy-
benzene (3cd). White solid. Mp 82 °C. 1H NMR (400 MHz,
CDCl3): δ (ppm) 3.78 (s, 6H), 3.80 (s, 3H), 5.81 (s, 1H), 6.14 (s,
2H), 7.20 (d, 2H, J = 8.4 Hz), 7.27-7.29 (m, 2H), 7.41-7.45 (m,
5H). 13C NMR (100 MHz, CDCl3): 30.9, 55.2, 55.9, 81.4, 90.2,
91.3, 110.7, 124.2, 127.5, 127.7, 128.1, 128.7, 131.4, 131.6, 140.2,
158.4, 160.5. DEPT-135: 30.9, 55.2, 55.9, 91.3, 127.5, 127.7,
128.1, 128.7, 131.6. HRMS (ESI) Calcd for C24H21ClO3 þ Hþ,
393.1257; found, 393.1255.
2-Methyl-5-(3-phenyl-1-p-tolylprop-2-ynyl)furan (3bi)28. 1H
NMR (400 MHz, CDCl3): δ (ppm) 2.24 (s, 3H), 2.34 (s, 3H),
5.16 (s, 1H), 5.88 (d, 1H, J = 2.8 Hz), 6.11 (d, 1H, J = 2.8 Hz),
7.15 (d, 2H, J = 8.0 Hz), 7.28-7.30 (m, 3H), 7.36 (d, 2H, J = 8.0
Hz), 7.45-7.47 (m, 2H). 13C NMR (100 MHz, CDCl3): 13.6,
21.1, 37.5, 83.5, 88.0, 106.1, 107.1, 123.3, 127.7, 127.9, 128.1,
129.2, 131.7, 136.2, 136.8, 151.8. 152.0. DEPT-135: 13.6, 21.1,
37.5, 106.1, 107.1, 127.7, 127.9, 128.1, 129.2, 131.7. HRMS
(ESI) Calcd for C21H18O þ Hþ, 287.1436; found, 287.1442.
(27) Pineda, A.; Salcedo, R.; Rio, F.; Ogawa, T. Eur. Polym. J. 1993, 29,
497.
(28) Nishibayashi, Y.; Inada, Y.; Yoshikawa, M.; Hidai, M.; Uemura, S.
Angew. Chem., Int. Ed. 2003, 42, 1495.
4420 J. Org. Chem. Vol. 75, No. 13, 2010

Chatterjee and Roy
JOCArticle
2-(3-Phenyl-1-p-tolylprop-2-ynyl)thiophene (3bj). Pale yellow
oil. 1H NMR (400 MHz, CDCl3): δ (ppm) 2.35 (s, 3H), 5.39 (s,
1H), 6.92 (dd, 1H, J = 3.2 and 4.8 Hz), 7.01 (d, 1H, J = 3.2 Hz),
7.16-7.19 (m, 3H), 7.30-7.32 (m, 3H), 7.39 (d, 2H, J = 8.0 Hz),
7.47-7.49 (m, 2H). 13C NMR (100 MHz, CDCl3): 21.1, 38.7,
84.1, 89.6, 123.2, 124.7, 124.9, 126.6, 127.5, 128.1, 128.2, 129.4,
131.6, 136.9, 138.3, 146.1. DEPT-135: 21.1, 38.7, 124.7, 124.9,
126.6, 127.5, 128.1, 128.2, 129.4, 131.6. Anal. Calcd (C20H16S):
C, 83.29; H, 5.59. Found: C, 82.97; H, 5.48.
1-(Dec-1-en-5-yn-4-yl)-4-methylbenzene (3hl)29. 1H NMR
(200 MHz, CDCl3): δ (ppm) 0.97 (t, 3H, J = 6.8 Hz), 1.47-
1.59 (m, 4H), 2.28 (td, 2H, J = 6.8 and 2.2 Hz), 2.49 (t, 2H, J =
7.0 Hz), 3.67 (td, 1H, J = 5.0 and 2.2 Hz), 5.05-5.15 (m, 2H),
5.81-6.01 (m, 1H), 7.17 (d, 2H, J = 7.8 Hz), 7.29 (d, 2H, J =
7.8 Hz). 13C NMR (54.6 MHz, CDCl3): 13.6, 18.5, 21.1, 21.9, 31.2,
37.7, 43.1, 81.3, 83.5, 116.5, 127.4, 129.1, 136.0, 136.1, 139.3.
(3-(4-Chlorophenyl)hex-5-en-1-ynyl)trimethylsilane (3il). Col-
orless oil. 1H NMR (200 MHz, CDCl3): δ (ppm) 0.18 (s, 9H), 2.46
(t, 2H, J = 7.0 Hz), 3.68 (t, 1H, J = 7.0 Hz), 4.98-5.06 (m, 1H),
7.27-7.49 (m, 4H). 13C NMR (54.6 MHz, CDCl3): 0.11, 38.3, 42.6,
88.3, 107.1, 117.3, 128.5, 128.9, 132.5, 134.8, 139.5. HRMS (ESI)
Calcd for C15H19ClSi þ Hþ, 263.1023; found, 263.1029.
3-Methyl-2-(3-phenyl-1-p-tolylptop-2-ynyl)thiophene (3bk).
Yellow oil. 1H NMR (400 MHz, CDCl3): δ (ppm) 2.22 (s,
3H), 2.33 (s, 3H), 5.40 (s, 1H), 6.79 (d, 1H, J = 5.2 Hz), 7.09
(d, 1H, J = 5.2 Hz), 7.14 (d, 2H, J = 8.0 Hz), 7.27-7.30 (m, 3H),
7.35 (d, 2H, J = 8.0 Hz), 7.45-7.47 (m, 2H). 13C NMR (100
MHz, CDCl3): 14.1, 21.1, 36.6, 83.7, 89.8, 122.5, 123.3, 127.5,
128.1, 128.2, 129.3, 130.3, 131.7, 133.3, 136.7, 137.7, 138.4.
DEPT-135: 14.1, 21.1, 36.6, 122.5, 127.5, 128.1, 128.2, 129.3,
130.3, 131.7. Anal. Calcd (C21H18S): C, 83.40; H, 6.00. Found:
C, 83.75; H, 5.96.
(3-Methyl-1-phenylpent-1-yn-3-yl)(propyl)sulfane (3fm). Col-
orless oil. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.02 (t, 3H, J =
7.4 Hz), 1.13 (t, 3H, J = 7.2 Hz), 1.59 (s, 3H), 1.64-1.72 (m,
2H), 1.74-1.81 (m, 1H), 1.83-1.91 (m, 1H), 2.76 (t, 2H, J = 7.2
Hz), 7.28-7.30 (m, 3H), 7.39-7.42 (m, 2H). 13C NMR (100
MHz, CDCl3): 9.8, 13.8, 22.9, 28.2, 32.2, 35.6, 43.7, 83.4, 92.5,
123.3, 127.8, 128.2, 131.6. DEPT-135: 9.8, 13.8, 22.9, 28.2, 32.2,
35.6, 127.8, 128.2, 131.6. HRMS (ESI) Calcd for C15H20S þ Hþ,
233.1364; found, 233.1356.
1
2-(1-p-Tolylprop-2-ynyl)furan (3df). Colorless oil. H NMR
(400 MHz, CDCl3): δ (ppm) 2.34 (s, 3H), 2.42 (d, 1H, J = 2.4
Hz), 5.02 (d, 1H, J = 2.4 Hz), 6.21 (d, 1H, J = 3.2 Hz),
6.29-6.34 (m, 1H), 7.12-7.16 (m, 2H), 7.29-7.38 (m, 3H).
13C NMR (100 MHz, CDCl3): 21.1, 36.6, 71.7, 82.1, 106.5,
110.2, 127.5, 129.3, 135.1, 137.1, 142.2, 153.3. HRMS (ESI)
Calcd for C14H12O þ Hþ, 197.0966; found, 197.0960.
2-(1-(4-Chlorophenyl)3-phenylprop-2-ynyl)-3-methylthio-
phene (3ck). Colorless oil. 1H NMR (400 MHz, CDCl3): δ (ppm)
2.25 (s, 3H), 5.41 (s, 1H), 6.81 (d, 1H, J = 5.2 Hz), 7.11 (d, 1H,
J = 5.2 Hz), 7.29-7.47 (m, 9H). 13C NMR (100 MHz, CDCl3):
14.0, 36.3, 84.3, 88.8, 122.9, 123.0, 128.2, 128.3, 128.7, 129.0,
130.4, 131.6, 132.9, 133.6, 137.5, 139.2. DEPT-135: 14.0, 36.3,
122.9, 128.2, 128.3, 128.7, 129.0, 130.4, 131.6. Anal. Calcd
(C20H15ClS): C, 74.40; H, 4.68. Found: C, 74.81; H, 4.65.
1-Methyl-4-(1-phenylhex-5-en-1-yn-3-yl)benzene (3bl)29. 1H
NMR (200 MHz, CDCl3): δ (ppm) 2.35 (s, 3H), 2.58 (t, 2H,
J = 7.0 Hz), 3.89 (t, 1H, J = 7.0 Hz), 5.06-5.15 (m, 2H),
5.83-6.01 (m, 1H), 7.16 (d, 2H, J = 7.8 Hz), 7.27-7.34 (m, 5H),
7.44-7.47 (m, 2H). 13C NMR (54.6 MHz, CDCl3): 21.1, 38.2,
42.8, 83.6, 91.2, 116.9, 123.8, 127.4, 127.7, 128.2, 129.2, 131.6,
135.6, 136.4, 138.4.
2-(1,3-Diphenylprop-2-ynylthio)ethanol (3jn)20. 1H NMR (400
MHz, CDCl3): δ (ppm) 2.15 (br, 1H), 2.86 (dt, 1H, J = 13.9 and
6.0 Hz), 3.00 (dt, 1H, J = 13.9 and 6.0 Hz), 3.74-3.81 (m, 2H),
5.06 (s, 1H), 7.33-7.40 (m, 6H), 7.46-7.51 (m, 2H), 7.56-7.60
(m, 2H). 13C NMR (100 MHz, CDCl3): 34.9, 39.2, 60.8, 86.2,
87.0, 122.6, 127.8, 127.9, 128.3, 128.4, 128.7, 131.7, 138.1.
1
Phenyl(1-p-tolyoprop-2-ynyl)sulfane (3do). Colorless oil. H
NMR (400 MHz, CDCl3): δ (ppm) 2.34 (s, 3H), 2.56 (d, 1H, J =
2.6 Hz), 4.97 (d, 1H, J = 2.6 Hz), 7.11 (d, 2H, J = 8.0 Hz),
7.22-7.31 (m, 5H), 7.41-7.45 (m, 2H). 13C NMR (100 MHz,
CDCl3): 21.1, 42.8, 74.3, 82.1, 127.6, 127.8, 128.2, 128.6, 129.2,
133.5, 134.2, 137.7. HRMS (ESI) Calcd for C16H14S þ Hþ,
239.0894; found, 239.0881.
tert-Butyl(4-phenyl-2-p-tolylbut-3-yn-2-yl)sulfane (3gp). Col-
1
orless oil. H NMR (400 MHz, CDCl3): δ (ppm) 1.25 (s, 9H),
1.92 (s, 3H), 2.34 (s, 3H), 7.14 (d, 2H, J = 8.0 Hz), 7.33-7.36 (m,
3H), 7.49-7.52 (m, 2H), 7.71 (d, 2H, J = 8.0 Hz). 13C NMR
(100 MHz, CDCl3): 20.9, 31.8, 34.1, 46.1, 47.4, 85.7, 93.2, 123.4,
126.7, 128.0, 128.2, 128.6, 131.3, 136.7, 141.4. DEPT-135: 20.9,
31.8, 34.1, 126.7, 128.0, 128.2, 128.6, 131.3. HRMS (ESI) Calcd
for C21H24S þ Hþ, 309.1677; found, 309.1686.
1-Chloro-4-(1-phenylhex-5-en-1-yn-3-yl)benzene (3cl)30. 1H
NMR (200 MHz, CDCl3): δ (ppm) 2.57 (t, 2H, J = 7.0 Hz),
3.90 (t, 1H, J = 7.0 Hz), 5.04-5.14 (m, 2H), 5.78-5.95 (m, 1H),
7.27-7.52 (m, 9H). 13C NMR (54.6 MHz, CDCl3): 37.9, 42.6,
84.1, 90.3, 117.5, 123.4, 127.9, 128.3, 128.6, 128.9, 131.7, 132.6,
135.1, 139.8.
1-Methyl-4-(3-methyl-1-phenylhex-5-en-1-yn-3-yl)benzene
(3gl). Colorless oil. 1H NMR (200 MHz, CDCl3): δ (ppm) 1.65
(s, 3H), 2.35 (s, 3H), 2.62 (t, 2H, J = 6.8 Hz), 5.03-5.15 (m, 2H),
5.79-5.93 (m, 1H), 7.16 (d, 2H, J = 8.0 Hz), 7.29-7.34 (m, 2H),
7.44-7.50 (m, 5H). 13C NMR (54.6 MHz, CDCl3): 20.9, 29.1,
40.3, 48.6, 83.9, 94.9, 117.6, 123.8, 126.1, 127.7, 128.2, 128.9,
131.6, 134.9, 135.9, 142.3. Anal. Calcd (C20H20): C, 92.26;
H, 7.74. Found: C, 92.38; H, 7.85.
1-(Hex-5-en-1-yn-3-yl)-4-methylbenzene (3dl). Colorless oil.
1H NMR (400 MHz, CDCl3): δ (ppm) 2.28 (d, 1H, J = 2.4 Hz),
2.33 (s, 3H), 2.51 (t, 2H, J = 6.8 Hz), 3.67 (dt, 1H, J = 2.4 and
6.8 Hz), 5.05-5.11 (m, 2H), 5.82-5.89 (m, 1H), 7.14 (d, 2H, J =
8.0 Hz), 7.25 (d, 2H, J = 8.0 Hz). 13C NMR (100 MHz, CDCl3):
20.9, 37.2, 42.3, 71.1, 85.5, 116.9, 127.2, 129.1, 135.2, 136.4,
137.7. Anal. Calcd (C13H14): C, 91.71; H, 8.29. Found: C, 91.83;
H, 8.24.
(3-Ethoxy-3-methylbut-1-ynyl)benzene (3aq)31. 1H NMR (400
MHz, CDCl3): δ (ppm) 1.24 (t, 3H, J = 7.2 Hz), 1.55 (s, 6H),
3.68 (q, 2H, J = 7.2 Hz), 7.29-7.30 (m, 3H), 7.41-7.43 (m, 2H).
13C NMR (100 MHz, CDCl3): 15.8, 29.3, 59.4, 70.2, 83.7, 91.6,
122.9, 128.0, 128.1, 131.6. DEPT-135: 15.8, 29.3, 59.4, 128.0,
128.1, 131.6. HRMS (ESI) Calcd for C13H16O þ Hþ, 189.1279;
found, 189.1272.
(3-(Hex-2-enyloxy)-3-methylbut-1-ynyl)benzene (3ar). Pale
1
yellow oil. H NMR (400 MHz, CDCl3): δ (ppm) 0.89 (t, 3H,
J = 7.6 Hz), 1.37-1.42 (m, 2H), 1.57 (s, 6H), 2.04-2.11 (m, 2H),
4.23 (d, 2H, J = 5.6 Hz), 5.55-5.61 (m, 2H), 7.29-7.31 (m, 3H),
7.41-7.44 (m, 2H). 13C NMR (100 MHz, CDCl3): 13.6, 22.6,
28.9, 60.1, 65.6, 70.5, 84.1, 91.4, 122.8, 126.7, 128.1, 128.2, 131.6,
133.1. DEPT-135: 13.6, 22.6, 28.9, 60.1, 65.6, 126.7, 128.1,
128.2, 131.6, 133.1. HRMS (ESI) Calcd for C17H22O þ Hþ,
243.1749; found, 243.1742.
(3-(3-Phenylpropoxy)prop-1-yne-1,3-diyl)dibenzene (3js). Col-
orless oil. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.98 (m, 2H),
2.74 (t, 2H, J = 7.2 Hz), 3.57-3.59 (m, 1H), 3.75-3.79 (m, 1H),
5.39 (s, 1H), 7.16-7.47 (m, 13H), 7.59 (d, 2H, J = 7.2 Hz). 13
C
NMR (100 MHz, CDCl3): 31.3, 32.3, 67.5, 72.1, 87.2, 87.4,
122.6, 125.7, 127.4, 128.1, 128.2, 128.3, 128.4, 128.5, 128.6,
(29) Nishibayashi, Y.; Shinoda, A.; Miyake, Y.; Matsuzawa, H.; Sato, M.
Angew. Chem., Int. Ed. 2006, 45, 4835.
(30) Kabalka, G. W.; Yao, M.-L.; Borella, S. J. Am. Chem. Soc. 2006,
128, 11320.
(31) Zhan, Z.; Yu, J.; Liu, H.; Cui, Y.; Yang, R.; Yang, W.; Li, J. J. Org.
Chem. 2006, 71, 8298.
J. Org. Chem. Vol. 75, No. 13, 2010 4421

Chatterjee and Roy
JOCArticle
131.8, 138.9, 141.9. DEPT-135: 31.3, 32.3, 67.5, 72.1, 125.7,
127.4, 128.1, 128.2, 128.3, 128.4, 128.5, 128.6, 131.8. HRMS
(ESI) Calcd for C24H22O þ Hþ, 327.1749; found, 327.1755.
4-Methyl-N-(2-methyl-4-phenylbut-3-yn-yl)benzenesulfon-
amide (3at). White solid. 1H NMR (400 MHz, CDCl3): δ (ppm)
1.65 (s, 6H), 2.26 (s, 3H), 4.68 (s, 1H), 7.05 (d, 2H, J = 8.0 Hz),
7.11 (d, 2H, J = 8.0 Hz), 7.20-7.28 (m, 3H), 7.78 (d, 2H, J = 8.0
Hz). 13C NMR (100 MHz, CDCl3): 21.3, 30.9, 50.5, 83.2, 90.4,
122.3, 127.5, 127.8, 128.1, 129.3, 131.5, 138.4, 143.1. DEPT-135:
21.3, 30.9, 127.5, 127.8, 128.1, 129.3, 131.5. HRMS (ESI) Calcd
for C18H19NO2S þ Naþ, 336.1034; found, 336.1042.
J = 8.8 and 2.0 Hz), 7.51 (d, 4H, J = 8.2 Hz), 7.89 (dd, 2H, J =
8.8 and 2.0 Hz). 13C NMR (54.6 MHz, CDCl3): 26.6, 31.6, 35.8,
55.3, 81.2, 100.6, 113.7, 126.6, 128.1, 128.9, 131.7, 135.8, 138.7,
158.2, 197.4. DEPT-135: 26.6, 31.6, 55.3, 113.7, 126.6, 128.1,
131.7. HRMS (ESI) Calcd for C20H20O2 þ Hþ, 293.1542; found,
293.1532.
1,3,5-Trimethoxy-2-(4-phenylbut-3-yn-2-yl)benzene (3ed).
1
Colorless oil. H NMR (400 MHz, CDCl3): δ (ppm) 1.51 (d,
3H, J = 7.2 Hz), 3.81 (s, 3H), 3.84 (s, 6H), 4.54 (q, 1H, J = 7.2
Hz), 6.16 (s, 2H), 7.21-7.24 (m, 3H), 7.36-7.38 (m, 2H). 13C
NMR (100 MHz, CDCl3): 20.3, 21.0, 55.3, 55.9, 78.1, 91.3, 94.4,
112.1, 124.7, 126.9, 128.0, 131.5, 158.6, 159.8. DEPT-135: 20.3,
21.0, 55.3, 55.9, 91.3, 126.9, 128.0, 131.5. HRMS (ESI) Calcd for
C19H20O3 þ Hþ, 297.1491; found, 297.1472.
N-(3-Phenyl-1-p-tolylprop-2-ynyl)benzenesulfonamide (3bu).
White solid. Mp 120 °C. 1H NMR (400 MHz, CDCl3): δ
(ppm) 2.34 (s, 3H), 4.96 (d, 1H, J = 9.0 Hz), 5.55 (d, 1H, J =
9.0 Hz), 7.12-7.16 (m, 4H), 7.22-7.31 (m, 3H), 7.41-7.53 (m,
5H), 7.93 (d, 2H, J = 7.2 Hz). 13C NMR (100 MHz, CDCl3):
21.1, 49.5, 85.6, 86.4, 121.9, 127.2, 127.4, 128.1, 128.6, 128.9,
129.4, 131.6, 132.6, 134.4, 138.3, 140.4. DEPT-135: 21.1, 49.5,
127.2, 127.4, 128.1, 128.6, 128.9, 129.4, 131.6, 132.6. HRMS
(ESI) Calcd for C22H19NO2S þ Naþ, 384.1034; found,
384.1052.
1,2,3-Trimethoxy-4-(2-methyl-4-phenylbut-3-yn-2-yl)benzene
(3av). Colorless oil. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.73
(s, 6H), 3.86 (s, 3H), 3.87 (s, 3H), 3.98 (s, 3H), 6.61 (d, 1H, J =
8.8 Hz), 7.25-7.29 (m, 4H), 7.41-7.44 (m, 2H). 13C NMR (54.6
MHz, CDCl3): 30.1, 34.9, 55.9, 60.4, 60.6, 80.6, 98.1, 106.0,
120.9, 124.2, 127.4, 128.1, 131.4, 131.7, 142.8, 152.7, 152.8.
HRMS (ESI) Calcd for C20H22O3 þ Hþ, 311.1647; found,
311.1654.
N-(1,3-Diphenylprop-2-ynyl)-4-methylbenzenesulfonamide (3jt)31.
1
White solid. Mp = 196 °C. H NMR (400 MHz, CDCl3): δ
1,1-Dimethyl-3-(2,4,6-trimethoxyphenyl)-1H-indene (5ad).
White solid. Mp 116 °C. 1H NMR (400 MHz, CDCl3): δ (ppm)
1.47 (s, 6H), 3.69 (s, 6H), 3.86 (s, 3H), 6.22 (s, 2H), 6.29 (s, 1H),
6.93 (d, 1H, J = 4.4 Hz), 7.16 (d, 2H, J = 4.8 Hz), 7.34 (d, 1H,
J = 4.4 Hz). 13C NMR (100 MHz, CDCl3): 24.7, 48.6, 55.2, 55.9,
91.1, 106.2, 120.7, 120.8, 124.3, 125.9, 132.4, 143.9, 146.6, 153.1,
159.1, 160.6. DEPT-135: 24.7, 55.2, 55.9, 91.1, 120.7, 120.8,
124.3, 125.9, 146.6. HRMS (ESI) Calcd for C20H22O3 þ Hþ,
311.1647; found, 311.1633.
(ppm) 2.32 (s, 3H), 4.84 (d, 1H, J = 9.0 Hz), 5.56 (d, 1H, J = 9.0
Hz), 7.12 (d, 2H, J = 6.4 Hz), 7.27-7.38 (m, 8H), 7.46 (d, 2H,
J = 7.2 Hz), 7.82 (d, 2H, J = 8.4 Hz). 13C NMR (100 MHz,
CDCl3): 21.4, 49.7, 85.4, 86.7, 121.9, 127.3, 127.5, 128.1, 128.5,
128.6, 128.7, 129.6, 131.5, 137.3, 143.6. HRMS (ESI) Calcd for
C22H19NO2S þ Naþ, 384.1034; found, 384.1026.
3-Methyl-1-phenylbut-2-en-1-one (6)32. 1H NMR (400 MHz,
CDCl3): δ (ppm) 2.02 (s, 3H), 2.21 (s, 3H), 6.75 (s, 1H),
7.42-7.54 (m, 3H), 7.92 (d, 2H, J = 7.2 Hz). 13C NMR (100
MHz, CDCl3): 21.1, 27.9, 121.1, 128.1, 128.3, 132.1, 156.6,
191.4.
1-(1-Ethyl-1-methyl-1H-indene-3-yl)-4-methoxynaphthalene
1
(5fb). Yellow gummy liquid. H NMR (400 MHz, CDCl3): δ
(ppm) 0.69 (t, 3H, J = 7.2 Hz), 1.42 (s, 3H), 1.79-1.88 (m, 1H),
1.94-2.03 (m, 1H), 4.07 (s, 3H), 6.18 (s, 1H), 6.89 (s, 1H), 7.20 (t,
1H, J = 7.6 Hz), 7.34 (t, 1H, J = 7.6 Hz), 7.41-7.51 (m, 5H),
7.64 (d, 1H, J = 8.4 Hz), 8.28 (d, 1H, J = 8.4 Hz). 13C NMR
(100 MHz, CDCl3): 9.4, 23.1, 31.2, 53.0, 55.7, 99.3, 122.6, 123.8,
124.1, 124.9, 125.6, 127.1, 128.1, 128.8, 129.1, 129.9, 139.3,
143.1, 152.1, 154.4. DEPT-135: 9.4, 23.1, 31.2, 55.7, 99.5,
122.6, 123.8, 124.1, 125.6, 127.1, 128.1, 128.8, 143.1. HRMS
(ESI) Calcd for C23H22O þ Hþ, 315.1749; found, 315.1740.
1-Methyl-1-p-tolyl-3-(2,4,6-trimethoxyphenyl)-1H-indene (5gd).
White solid. Mp 86 °C. 1H NMR (400 MHz, CDCl3): δ (ppm)
1.81 (s, 3H), 2.29 (s, 3H), 3.73 (s, 6H), 3.87 (s, 3H), 6.24 (s, 2H),
6.42 (s, 1H), 6.95 (d, 1H, J = 7.2 Hz), 7.06 (d, 2H, J = 8.0 Hz),
7.10-7.17 (m, 3H), 7.33 (d, 2H, J = 8.0 Hz). 13C NMR (100
MHz, CDCl3): 21.1, 22.5, 55.4, 55.6, 55.9, 91.1, 106.1, 121.1,
122.2, 125.1, 126.1, 126.2, 129.1, 134.2, 135.7, 140.5, 144.1,
146.3, 153.6, 159.3, 160.9. DEPT-135: 21.1, 22.5, 55.4, 55.9,
91.1, 121.1, 122.2, 125.1, 126.1, 126.2, 129.1, 146.3. HRMS
(ESI) Calcd for C26H26O3 þ Hþ, 387.1960; found, 387.1956.
1,1,5,5-Tetramethyl-3,7-bis(2,4,6-trimethoxyphenyl)-1,5-
dihydros-indacene (5kd). White solid. 1H NMR (200 MHz,
CDCl3): δ (ppm) 1.35 (s, 12H), 3.71 (s, 12H), 3.88 (s, 6H), 6.21
(s, 2H), 6.25 (s, 4H), 6.86 (s, 2H). 13C NMR (100 MHz, CDCl3):
25.1, 48.1, 55.2, 55.7, 90.9, 106.7, 113.6, 132.7, 140.9, 145.8,
151.3, 159.1, 160.4. DEPT-135: 25.1, 55.2, 55.7, 90.9, 113.6,
145.8.
1-Ethyl-4-(3-(4-methoxyphenyl)-3-methylbut-1-ynyl)benzene
(3pa). Light yellow oil. 1H NMR (200 MHz, CDCl3): δ (ppm)
1.22 (t, 3H, J = 7.6 Hz), 1.65 (s, 3H), 2.62 (q, 2H, J = 7.6 Hz),
3.81 (s, 3H), 6.88 (dd, 2H, J = 8.0 and 2.4 Hz), 7.14 (d, 2H, J =
8.4 Hz), 7.38 (d, 2H, J = 8.4 Hz), 7.54 (dd, 2H, J = 8.0 and 2.4
Hz). 13C NMR (54.6 MHz, CDCl3): 15.4, 28.8, 31.9, 35.8, 55.3,
81.9, 96.1, 113.6, 121.2, 126.7, 127.7, 131.6, 139.4, 144.0, 158.1.
DEPT-135: 15.4, 28.8, 31.9, 55.3, 113.6, 126.7, 127.7, 131.6.
HRMS (ESI) Calcd for C20H22O þ Hþ, 279.1749; found,
279.1756.
1-Methoxy-4-(2-methyl-4-p-tolylbut-3-yn-2-yl)benzene (3na).
Yellow oil. 1H NMR (200 MHz, CDCl3): δ (ppm) 1.65 (s,
6H), 2.34 (s, 3H), 3.81 (s, 3H), 6.87 (dd, 2H, J = 8.8 and 2.2
Hz), 7.10 (d, 2H, J = 7.8 Hz), 7.34 (d, 2H, J = 7.8 Hz), 7.53 (dd,
2H, J = 8.8 and 2.2 Hz). 13C NMR (54.6 MHz, CDCl3): 21.4,
31.9, 35.7, 55.2, 81.8, 96.0, 113.5, 120.8, 126.6, 128.9, 131.4,
137.5, 139.4, 158.1. DEPT-135: 21.4, 31.9, 55.2, 113.5, 126.6,
128.9, 131.4. HRMS (ESI) Calcd for C19H20O þ Hþ, 265.1592;
found, 265.1595.
1-Chloro-4-(3-(4-methoxyphenyl)-3-methylbut-1-ynyl)ben-
zene (3qa). White solid. 1H NMR (200 MHz, CDCl3): δ (ppm)
1.68 (s, 6H), 3.85 (s, 3H), 6.92 (dd, 2H, J = 9.0 and 2.2 Hz),
7.27-7.33 (m, 2H), 7.37-7.42 (m, 2H), 7.56 (dd, 2H, J = 9.0
and 2.2 Hz). 13C NMR (54.6 MHz, CDCl3): 31.7, 35.7, 55.3,
80.7, 97.9, 113.6, 122.4, 126.6, 128.5, 132.8, 133.6, 138.9, 158.1.
DEPT-135: 31.7, 55.3, 113.6, 126.6, 128.5, 132.8. HRMS (ESI)
Calcd for C18H17ClO þ Hþ, 285.1046; found, 285.1053.
1-(4-(3-(4-methoxyphenyl)-3-methylbut-1-ynyl)phenyl)ethan-
one (3ra). White solid. Mp 71 °C. 1H NMR (200 MHz, CDCl3):
δ (ppm) 1.67 (s, 6H), 2.60 (s, 3H), 3.81 (s, 3H), 6.88 (dd, 2H,
1-(1-iso-Butyl-1-methyl-1H-indene-3-yl)-4-methoxynaphtha-
lene (5lb). Pale yellow gummy liquid. 1H NMR (400 MHz,
CDCl3): δ (ppm) 0.62 (d, 3H, J = 6.8 Hz), 0.86 (d, 3H, J =
6.8 Hz), 1.27-1.30 (m, 1H), 1.39 (s, 3H), 1.87-1.91 (m, 2H),
4.08 (s, 3H), 6.26 (s, 1H), 6.91 (s, 1H), 7.21 (t, 1H, J = 7.6 Hz),
7.35 (t, 1H, J = 7.6 Hz), 7.41-7.50 (m, 5H), 7.64 (d, 1H, J = 8.4
Hz), 8.29 (d, 1H, J = 8.4 Hz). 13C NMR (100 MHz, CDCl3):
24.5, 24.9, 25.1, 25.5, 47.5, 52.8, 55.7, 99.5, 122.6, 123.8, 124.1,
124.9, 125.6, 127.1, 128.1, 128.8, 129.1, 129.9, 139.3, 143.1,
(32) Mugishima, T.; Tsuda, M.; Kasai, Y.; Ishiyama, H.; Fukushi, E.;
Kawabata, J.; Watanabe, M.; Akao, K.; Kobayashi, J. J. Org. Chem. 2005,
70, 9430.
4422 J. Org. Chem. Vol. 75, No. 13, 2010

Chatterjee and Roy
JOCArticle
152.1, 154.4. DEPT-135: 24.5, 24.9, 25.1, 25.5, 47.5, 55.7, 99.5,
122.6, 123.8, 124.1, 125.6, 127.1, 128.1, 128.8, 143.1. HRMS
(ESI) Calcd for C25H26O þ Hþ, 343.2062; found, 343.2056.
1-Phenyl-1-p-tolyl-3-(2,4,6-trimethoxyphenyl)-1H-indene (5md).
White solid. Mp 118 °C. 1H NMR (400 MHz, CDCl3): δ (ppm)
2.30 (s, 3H), 3.71 (s, 6H), 3.86 (s, 3H), 6.22 (s, 2H), 6.67 (s, 1H),
6.98 (d, 1H, J = 6.8 Hz), 7.05 (d, 2H, J = 8.4 Hz), 7.11-7.40 (m,
10H). 13C NMR (100 MHz, CDCl3): 20.9, 55.3, 55.8, 65.7, 90.9,
105.7, 121.5, 124.7, 124.8, 126.2, 126.3, 127.8, 127.9, 128.1,
128.8, 134.2, 135.8, 141.1, 144.4, 144.5, 144.7, 150.2, 159.2,
160.8. DEPT-135: 20.9, 55.3, 55.8, 90.9, 121.5, 124.7, 124.8,
126.2, 126.3, 127.8, 127.9, 128.1, 128.8, 144.7. HRMS (ESI)
Calcd for C31H28O3 þ Hþ, 449.2117; found, 449.2121.
1H), 6.95 (s, 1H), 6.99 (d, 2H, J = 8.4 Hz), 7.23 (t, 1H, J = 7.6
Hz), 7.35 (t, 1H, J = 7.6 Hz), 7.42 (d, 2H, J = 8.4 Hz), 7.71
(d, 1H, J = 8.4 Hz), 8.28 (d, 1H, J = 8.4 Hz). 13C NMR
(54.6 MHz, CDCl3): 24.5, 48.8, 55.4, 55.8, 99.3, 113.6, 122.7,
123.9, 124.1, 125.1, 125.7, 129.1, 129.3, 130.1, 131.5, 142.2,
143.9, 153.1, 154.6, 158.9. HRMS (ESI) Calcd for C23H22O2 þ
Hþ, 331.1698; found, 331.1703.
3-Ethyl-1,1-dimethyl-1H-indene (5x)33. 1H NMR (400 MHz,
CDCl3): 1.26 (t, 3H, J = 7.2 Hz), 1.33 (s, 6H), 2.46 (dd, 2H, J =
7.2 and 2.0 Hz), 6.02 (s, 1H), 7.16-7.38 (m, 3H).
(5-Methylhexa-3,4-dien-3-yl)benzene (7). 1H NMR (400
MHz, CDCl3): δ (ppm) 1.14 (t, 3H, J = 7.2 Hz), 1.85 (s, 6H),
2.43 (q, 2H, J = 7.2 Hz), 7.18-7.42 (m, 5H). 13C NMR (54.6
MHz, CDCl3): 12.6, 20.5, 23.2, 98.9, 105.3, 125.9, 126.1, 128.2,
138.5, 201.6. DEPT-135: 12.6, 20.5, 23.2, 125.9, 126.1, 128.2.
1,1,5-Trimethyl-3-(2,4,6-trimethoxyphenyl)-1H-indene (5nd).
White solid. Mp 122 °C. 1H NMR (400 MHz, CDCl3): δ
(ppm) 1.40 (s, 6H), 2.39 (s, 3H), 3.69 (s, 6H), 3.86 (s, 3H), 6.22
(s, 3H), 6.82 (d, 1H, J = 7.6 Hz), 6.98 (d, 1H, J = 7.6 Hz), 7.17
(s, 1H). 13C NMR (100 MHz, CDCl3): 21.5, 24.9, 48.5, 55.3,
55.9, 91.2, 106.5, 120.5, 121.8, 126.7, 132.3, 134.1, 141.4, 145.8,
153.4, 159.2, 160.6. HRMS (ESI) Calcd for C21H24O3 þ Hþ,
325.1803; found, 325.1798.
Acknowledgment. We thank DST (financial support to
S.R.) and IIT Kharagpur (fellowship to P.N.C.). Financial
support from DST-FIST program is also acknowledged.
1-Methoxy-4-(5-methoxy-1,1-dimethyl-1H-indene-3-yl)naphthal-
Supporting Information Available: Experimental proce-
dures, characterization data, kinetics plot, and 1H and 13C
NMR spectra for all compounds and crystallographic data for
5ad and 5kd. This material is available free of charge via the
Internet at http://pubs.acs.org.
1
ene (5ob). Yellowish solid. Mp 106 °C. H NMR (400 MHz,
CDCl3): δ (ppm) 1.43 (s, 6H), 3.90 (s, 3H), 4.08 (s, 3H), 6.21 (s,
(33) Gelin, R.; Chantegrel, B. Bull. Soc. Chim. Fr. 1971, 7, 2527.
J. Org. Chem. Vol. 75, No. 13, 2010 4423