PtBr2-catalyzed transformation of allyl(o-ethynylaryl)carbinol derivatives into functionalized indenes. Formal sp3 C-H bond activation

Article abstract of DOI:10.1021/jo060951g

The PtBr₂-catalyzed reaction of 1-ethynyl-2-(1-alkoxybut-3-enyl) benzenes at 120 °C in CH₃CN gave functionalized indenes in good to allowable yields. Most probably, the hydrogen at the terminal alkyne is transferred to the adjacent internal β-carbon to form an (η²-vinylidene)platinum carbene intermediate, which activates the sp³ C-H bond at the benzylic carbon. This reaction pathway is supported by DFT calculations which suggest that the formation of the Pt-vinylidene complex is the rate-limiting stage for the whole transformation.

Full text of DOI:10.1021/jo060951g

PtBr -Catalyzed Transformation of Allyl(o-ethynylaryl)carbinol
2
3
Derivatives into Functionalized Indenes. Formal sp C-H Bond
Activation
Gan B. Bajracharya, Nirmal K. Pahadi, Ilya D. Gridnev, and Yoshinori Yamamoto*
Department of Chemistry, Graduate School of Science, Tohoku UniVersity, Sendai 980-8578, Japan
yoshi@mail.tains.tohoku.ac.jp
ReceiVed May 8, 2006
2 3
The PtBr -catalyzed reaction of 1-ethynyl-2-(1-alkoxybut-3-enyl)benzenes at 120 °C in CH CN gave
functionalized indenes in good to allowable yields. Most probably, the hydrogen at the terminal alkyne
2
is transferred to the adjacent internal â-carbon to form an (η -vinylidene)platinum carbene intermediate,
3
which activates the sp C-H bond at the benzylic carbon. This reaction pathway is supported by DFT
calculations which suggest that the formation of the Pt-vinylidene complex is the rate-limiting stage for
the whole transformation.
Introduction
tion of 1-vinylnaphthalenes 4 in the PtBr2-catalyzed reaction
of the internal alkyne analogues 3, in which the cyclobutene
Transition-metal-catalyzed cyclization of alkynes for the
synthesis of carbo- and heterocycles has attracted great attention
in recent years. Although it is well established that terminal
intermediates are formed through Pt-catalyzed enyne metathesis
6
(
eq 4). It is interesting that the terminal alkynes 1 behaved
1
differently.
alkynes on treatment with transition metals lead to the forma-
2
tion of (η -vinylidene)metal complexes, we still await further
(2) For reviews, see: (a) Bruce, M. I.; Swincer, A. G. AdV. Organomet.
development of synthetically useful transformations through
these intermediates. Depending upon the type of involved
nucleophiles, mechanistically two distinct classes of intramo-
lecular cycloisomerizations through metal vinylidene complexes
exist in the literature: (1) intramolecular cyclization of dienyl-
Chem. 1983, 22, 59. (b) Bruce, M. I. Chem. ReV. 1991, 91, 197. (c) Bruneau,
C.; Dixneuf, P. H. Acc. Chem. Res. 1999, 32, 311. Also see: (d)
Weyerhausen, B.; Dotz, K. H. Eur. J. Inorg. Chem. 1999, 1057. (e)
McDonald, F. E. Chem.sEur. J. 1999, 5, 3103 and references therein. (f)
Nevado, C.; Echavarren, A. M. Synthesis 2005, 167 and references therein.
(g) Miki, K.; Uemura, S.; Ohe, K. Chem. Lett. 2005, 34, 1068 and references
therein.
2
3
alkynes through 6π-electrocyclization (eq 1) and (2) cyclization
(
3) (a) Merlic, C. A.; Pauly, M. E. J. Am. Chem. Soc. 1996, 118,
1319. Also see: (b) Miura, T.; Iwasawa, N. J. Am. Chem. Soc. 2002,
124, 518 and references therein. (c) Dankwardt, J. W. Tetrahedron Lett.
001, 42, 5809. (d) Mart ´ı n-Matute, B.; Nevado, C.; C a´ rdenas, D. J.;
of terminal alkynes tethered to hetero- and carbonucleophiles
1
e
(
eq 2).2 In the latter case, a stoichiometric amount of a base is
2
needed to remove a proton from YH. It is rather surprising that
carbon nucleophiles have not been explored in the line of this
strategy, except for in McDonald’s paper.4
Echavarren, A. M. J. Am. Chem. Soc. 2003, 125, 5757. (e) Madhushaw,
R. J.; Lo, C.-Y.; Hwang, C.-W.; Su, M.-D.; Shen, H.-C.; Pal, S.; Shaikh,
I. R.; Liu, R.-S. J. Am. Chem. Soc. 2004, 126, 15560 and references
therein.
Herein, we report the PtBr2-catalyzed transformation of
(4) McDonald, F. E.; Olson, T. C. Tetrahedron Lett. 1997, 38, 7691.
1-ethynyl-2-(1-alkoxybut-3-enyl)benzenes 1 into functionalized
NaH (0.5 equiv) was used as a base, and 0.5 equiv of (Et3N)Mo(CO)5 was
needed to promote the carbocyclization.
3
indenes 2 in which most probably a formal sp C-H activation
takes place by carbene insertion into the C-H bond of the
(5) (a) Recently, ruthenium vinylidene complex-mediated alkenylation
of pyridine at the R-C-H bond via [2 + 2] heterocycloaddition was
reported: Murakami, M.; Hori, S. J. Am. Chem. Soc. 2003, 125, 4720. For
recent advances in C-H activation, see: (b) Handbook of C-H Transfor-
mation, Applications in Organic Synthesis; Dyker, G., Ed.; Wiley-VCH:
Weinheim, 2005; Vols. 1 and 2.
Pt-vinylidene complex (eq 3).2f,5 We recently reported forma-
(
1) For recent reviews see: (a) Nakamura, I.; Yamamoto, Y. Chem. ReV.
004, 104, 2127. (b) Zeni, G.; Larock, R. C. Chem. ReV. 2004, 104, 2285.
c) Takacs, J. M.; Vayalakkada, S.; Jiang, X. Science of Synthesis;
Thieme: Stuttgart, Germany, 2003; Vol. 1, pp 265-318.
2
(
(6) Bajracharya, G. B.; Nakamura, I.; Yamamoto, Y. J. Org. Chem. 2005,
70, 892.
10.1021/jo060951g CCC: $33.50 © 2006 American Chemical Society
6
204
J. Org. Chem. 2006, 71, 6204-6210
Published on Web 07/14/2006

Allyl(ethynylaryl)carbinol Transformation into Indenes
corresponding indene derivatives 2b-d with a high selectivity
over the formation of 4a (entries 2-4). No significant effect
was observed with the bulkiness of the alkoxide moiety. The
reaction of 1e,f bearing an electron-donating substituent (OMe)
at the aromatic ring proceeded with perfect selectivity and
produced the corresponding products 2e,f (entries 5 and 6).
Similarly, an excellent selectivity was observed with the sub-
strate 1g bearing a poor electron-withdrawing group (F) under
the standard conditions, and product 2g was isolated in a
moderate yield (entry 7). On the other hand, the presence of a
strong electron-withdrawing group (CF3) reduced both the
chemical yield and selectivity (entries 8 and 9).
1
We tested the effect of the R group in 1 on the present
carbocyclization. The saturated analogue 1j, the vinyl derivative
1k bearing a shorter carbon chain, and 1l having a longer carbon
chain did not give 2 at all under the standard conditions;
decomposition of the substrates took place, and a complex
mixture of products was obtained. This observation suggests
that the coordination of olefin to Pt at a right position/geometry
might be essential for the indene formation. External olefin
additives did not exert an influence on the reaction, but the
internal olefin was needed to induce the reaction. On the other
hand, replacing the methoxy substituent with the phenyl group
proved to be possible. Thus, the phenyl-substituted analogue
Results and Discussion
In our initial experimental setup, when 1-ethynyl-2-(1-meth-
oxybut-3-enyl)benzene (1a) was heated with 2 mol % PtBr2 in
1
,4-dioxane at 120 °C for 42 h, 1-allyl-1-methoxy-1H-indene
1
-ethynyl-2-(1-phenylbut-3-enyl)benzene (5) gave 1-allyl-1-
(2a) was isolated in 42% yield as the major product together
phenyl-1H-indene (6) in 40% isolated yield (eq 5).
with 24% 1-vinylnaphthalene (4a) (R ) H). Encouraged by this
result, we further optimized the reaction conditions. When
CH3CN was used as solvent, the selectivity for the formation
of 2a was improved. Increasing the amount of catalyst loading
(5 mol %) was proved worthy, and 2a was isolated in 55%
yield in 12 h (65% NMR yield) (Table 1, entry 1). Besides plati-
num halides, [RuCl2(CO)3]2 could be used as an alternative cat-
alyst, but it requires a longer reaction time. Other catalysts,
A deuterium-labeling experiment was carried out to get
additional data for the elucidation of the reaction mechanism.
When the substrate 1a-d was treated with 5 mol % PtBr2 under
the standard conditions, the corresponding product 2a-d (labeled
with 100% deuterium at C-2 position) was obtained in 50%
yield (eq 6). The deuterium labeling at another position was
7
such as NiBr2, PdCl2(CH3CN)2, Pd(PPh3)4, Rh6(CO)16, CoCl2,
W(CO)6, AuCl3, etc., did not promote the reaction at all. This
reaction was not sensitive to moisture and was unaffected by
addition of 50 mol % H2O. The reaction was completely halted
on treatment with an additional base (e.g., K2CO3 and Et3N).
Olefin additives, such as â-pinene (which can activate the plati-
8
num catalyst through π-coordination), produced a comparable
yield.
The scope of this reaction is summarized in Table 1. The
reaction of substrates 1b-d proceeded smoothly, affording the
(
7) More recently, two papers on cycloisomerization via Ru- and Rh-
vinylidene intermediates appeared: (a) Datta, S.; Odedra, A.; Liu, R.-S. J.
Am. Chem. Soc. 2005, 127, 11606. (b) Kim, H.; Lee, C. J. Am. Chem. Soc.
not observed. The structure of 2a-d, as well as perfect selectivity
of the position of deuterium incorporation, strongly suggests
the intermediate formation of a vinylidene intermediate similar
to those shown in eqs 1 and 2. In the case of a cationic pathway
similar to the cyclization reactions of o-alkynylbenzaldehyde
2
005, 127, 10180.
8) Recently, we reported the Pd-catalyzed carbocyclization of alkynyl-
(
acetals in which the cleavage of the C-O bond of o-alkynylbenzaldehyde
acetal produces the cationic intermediate and both the triple bond and the
acetal group are bonded to the metal. Ring closure of the cationic
intermediates leads to the cyclic vinyl cations, which are trapped by Pd-
OR. (a) Nakamura, I.; Bajracharya, G. B.; Wu, H.; Oishi, K.; Mizushima,
Y.; Gridnev, I. D.; Yamamoto, Y. J. Am. Chem. Soc. 2004, 126, 15423. (b)
Nakamura, I.; Bajracharya, G. B.; Yamamoto, Y. Chem. Lett. 2005, 34,
8
acetals and thioacetals, one would expect some randomness in
the distribution of deuterium. Moreover, the cationic mechanism
would open the door to the migration of the methoxy group,
actually observed in the corresponding reactions but not in the
reaction under study. This observation corresponds well to the
mechanism involving vinylidene insertion into the C-H bond,
since it implies the conservation of the C-OMe bond throughout
the whole transformation (Scheme 1). Another argument for
the intermediate vinylidene formation in the case of terminal
acetylenes is the completely different structure of the products
yielded by the alkyl-substituted substrates under the same
1
74. (c) Nakamura, I.; Mizushima, Y.; Gridnev, I. D.; Yamamoto, Y. J.
Am. Chem. Soc. 2005, 127, 9844. We were aware that if the present reaction
proceeds through a similar mechanistic fashion, 7a, 7b, 7c, or 7d should
be obtained. None of them were obtained.
6
conditions (eq 4). Although we are unaware of known examples
J. Org. Chem, Vol. 71, No. 16, 2006 6205

Bajracharya et al.
TABLE 1. PtBr2-Catalyzed endo-Carbocyclization of Terminal Alkynesa
a
b
1
c
Conditions: 5 mol % PtBr2, CH3CN, 120 °C, 12 h. Combined yields of 2 + 4 based on H NMR analysis; isolated yields are in parentheses. Ratio
d
based on isolated yield. Reaction time was 24 h.
of platinum vinylidene intermediates, recent results demonstrate
that the pincer vinylidene complexes of Pt(IV) can be isolated.
To get more support for the mechanism of Pt-vinylidene
insertion, we have followed the reaction pathway (Scheme 1)
computationally (Figures 1 and 2).We have located the structures
of three different complexes of PtBr2 with the starting compound
Br-Pt-Br and Br-Pt-C are 91.6° and 82.5°, respectively).
On the other hand, in the optimized structure of the intermediate
11 (analogue of 8 having a vinyl substituent instead of allyl)
the square planar geometry of Pt atom is significantly distorted
(angles Br-Pt-Br and Br-Pt-C are 104.5° and 49.1°,
respectively). The less effective intramolecular coordination of
the vinyl substituent might be one of the reasons why we failed
to obtain the corresponding cyclization products, although one
cannot exclude the possibility of just inferior stability of the
vinyl-substituted product.
9
1
a, viz., alkyne-PtBr2-alkene complex 7, PtBr2-vinylidene
complex 8, alkyne-PtBr2-OMe complex 9, and PtBr2-product
complex 10 (Scheme 1, Figure 2).
Interestingly, PtBr2-vinylidene complex 8 is much more
stable (about 8 kcal/mol) than alkyne-PtBr2-OMe complex 9
and only 2.2 kcal/mol less stable than starting 7. The geometry
of the Pt atom in 8 is very close to square planar (angles
(9) Kubo, K.; Jones, D.; Ferguson, M. J.; McDonald, R.; Cavell, R. G.
J. Am. Chem. Soc. 2005, 127, 5314.
6206 J. Org. Chem., Vol. 71, No. 16, 2006

Allyl(ethynylaryl)carbinol Transformation into Indenes
b
SCHEME 1. Formation of the Product via Insertion of the PtBr
2
-Vinylidene Complex into the C-H Bond
We have also located transition structures (Figure 3) con-
necting 7 and 8 (TS1) as well as 8 and 10 (TS2); their validity
was confirmed with the frequency analysis (only one negative
vibration for either TS1 or TS2). In both transition structures
the participation of the double bond in the Pt coordination is
evident: the Pt atom keeps almost ideal square planar geometry,
one of the four ligands being the double bond of the allylic
substituent. The activation barrier for the isomerization of 7 to
substituted substrates for the cyclization might be stipulated for
the geometry of the allylic substituent which is appropriate to
keep the square planar geometry on the Pt atom throughout the
whole transformation.
Experimental Section
1
General Information. H NMR spectra are reported as fol-
lows: chemical shift in parts per million (δ) relative to the chemical
shift of CDCl at 7.24 ppm, integration, multiplicities (s ) singlet,
3
8
is quite high (33.4 kcal/mol); this is the limiting stage of the
whole transformation, since the activation barrier of the cy-
clization step is quite low (3.1 kcal/mol). Energy minimization
using TS2 as the input structure afforded 10; therefore, no other
intermediates are involved in the cyclization step.
A alternative transition state (TS3) for the limiting stage
connecting 9 and 12 (analogue of 8 with Pt coordinated to OR
rather than to the double bond) was also computed. It was 18.2
kcal/mol higher in energy than TS1. The geometry of the Pt
atom in TS3 strongly deviated from square planar. Hence, the
computational results indicate that the uniqueness of the allyl-
d ) doublet, t ) triplet, m ) multiplet), and coupling constants
Hz). 13C NMR spectra are reported in parts per million (δ) relative
to the central line of the triplet for CDCl at 77 ppm. IR bands are
reported in inverse centimeters. Column chromatography was
carried out employing silica gel 60 N (spherical, neutral, 100-210
µm). Analytical thin-layer chromatography (TLC) was performed
on 0.2 mm precoated plate Kieselgel 60 F254. All manipulations
were conducted under an argon atmosphere using standard Schlenk
techniques.
(
3
Materials. 2-[(Trimethylsilanyl)ethynyl]benzaldehyde derivatives
were obtained from the coupling of the corresponding 2-bromoben-
FIGURE 1. Energy profile for the transformation of the alkyne-Pt-alkene complex 7 to the product-PtBr
2
complex 10.
J. Org. Chem, Vol. 71, No. 16, 2006 6207

Bajracharya et al.
5-fluorobenzaldehyde, (trimethylsilyl)acetylene, and allyltrimeth-
ylsilane were purchased and used as received. 2-Bromo-5-meth-
oxybenzaldehyde,12 2-bromo-4-methoxybenzaldehyde, 2-bromo-
13
1
4
4
-(trifluoromethyl)benzaldehyde, and 2-bromo-5-(trifluoromethyl)-
14
benzaldehyde were prepared according to the reported procedures.
-[(Trimethylsilanyl)ethynyl]benzaldehyde on treatment with phen-
2
ylmagnesium bromide produced phenyl[2-[(trimethylsilanyl)ethy-
nyl]phenyl]methanol, which after allylation15 followed by depro-
tection of the trimethylsilyl group using KF afforded 1-ethynyl-2-
(
1-phenylbut-3-enyl)benzene. All the catalysts used were com-
mercially available.
Representative Procedure for the endo-Carbocyclization. To
a mixture of PtBr
2
(5.3 mg, 0.015 mmol, 5 mol %) and 1-ethynyl-
2
-(1-methoxybut-3-enyl)benzene (1a) (55.9 mg, 0.3 mmol) was
3
added CH CN (5.0 mL, 0.06 M) under an argon atmosphere in a
microreactor. The mixture was stirred for 20 min at room
temperature and then heated at 120 °C for 12 h. The product was
2
filtered through a short column of SiO using ethyl acetate as an
eluent, and the resulting filtrate was concentrated. The residue was
purified by column chromatography (silica gel, hexane/ethyl acetate,
100/1) to afford 1-allyl-1-methoxy-1H-indene (2a) in 55% yield
(30.7 mg), and 1-vinylnaphthalene (4a) was obtained in 6% yield
(2.8 mg).
Data for 1-allyl-1-methoxy-1H-indene (2a): R
hexane/EtOAc, 10/1); H NMR (500 MHz, CDCl
f
0.52 (silica gel,
3
) δ 2.52 (dd, J
1
)
7.0, 14.0 Hz, 1H), 2.71 (dd, J ) 7.5, 14.0 Hz, 1H), 2.97 (s, 3H),
5
.02-4.98 (m, 2H), 5.77-5.69 (m, 1H), 6.19 (d, J ) 5.5 Hz, 1H),
6
.74 (d, J ) 5.5 Hz, 1H), 7.32-7.18 (m, 4H); 13C NMR (125 MHz,
3
CDCl ) δ 42.2, 51.7, 89.7, 117.7, 121.5, 122.6, 126.0, 128.5, 132.9,
1
1
C
(
33.7, 139.3, 143.0, 145.0; IR (neat) 3070-2824, 1640, 1464, 1315,
-
1
101, 1074, 990, 920, 791, 758 cm ; HRMS (EI) m/z calcd for
+
13
H
14O (M ) 186.1045, found 186.1039. Anal. Calcd for C13
186.25): C, 83.83; H, 7.58. Found: C, 83.54; H, 7.66. The
structure of 2a was confirmed by an NOE experiment:
14
H O
FIGURE 2. Structures of Pt complexes 7-10 optimized at the B3LYP/
SDD level of theory. The relative energies are given with respect to
product-PtB complex 10.
2
Data for 1-allyl-1-ethoxy-1H-indene (2b): R
f
0.48 (silica gel,
hexane/EtOAc, 10/1); yield 53%; H NMR (400 MHz, CDCl ) δ
.99 (t, J ) 7.2 Hz, 3H), 2.45 (dd, J ) 7.2, 14.0 Hz, 1H), 2.64 (dd,
1
3
0
J ) 7.2, 14.0 Hz, 1H), 2.96-2.88 (m, 1H), 3.17-3.10 (m, 1H),
4
6
.91-4.86 (m, 2H), 5.66-5.57 (m, 1H), 6.13 (d, J ) 5.6 Hz, 1H),
.62 (d, J ) 5.6 Hz, 1H), 7.25-7.08 (m, 4H); 13C NMR (100 MHz,
3
CDCl ) δ 16.0, 42.3, 59.2, 89.2, 117.4, 121.2, 122.5, 125.8, 128.2,
1
1
32.1, 133.6, 139.9, 142.7, 145.7; IR (neat) 3070-2876, 1639,
-
1
464, 1456, 1315, 1119, 1080, 995, 914, 789, 756 cm ; HRMS
+
(
EI) m/z calcd for C14
H
16O (M ) 200.1201, found 200.1204. Anal.
FIGURE 3. Transition structures TS1 and TS2 optimized at the
B3LYP/SDD level of theory via the QST3 procedure. The relative
energies are given with respect to product-PtB complex 10.
2
Calcd for C14
H, 7.72.
Data for 1-allyl-1-butoxy-1H-indene (2c): R
H16O (200.28): C, 83.96; H, 8.05. Found: C, 84.09;
f
0.44 (silica gel,
zaldehyde derivatives with (trimethylsilyl)acetylene by using the
Sonogashira reaction.10 2-[(Trimethylsilanyl)ethynyl]benzaldehyde
derivatives were then treated with KF in methanol for the
deprotection of the trimethylsilyl group, producing the correspond-
ing 2-ethynylbenzaldehydes. 2-Ethynylbenzaldehydes on treatment
with allyltrimethylsilane in the presence of scandium triflate
following the known protocol produced the desired 1-ethynyl-2-
1
hexane/EtOAc, 10/1); yield 50%; H NMR (400 MHz, CDCl ) δ
3
(
(
12) Gies, A.-E.; Pfeffer, M. J. Org. Chem. 1999, 64, 3650.
13) Stuffert, J.; Abraham, E.; Raeppel, S.; Br uˆ ckner, R. V. Liebigs Ann.
1996, 447.
(14) (a) Sˇ indel a´ rˇ , K.; Dlaba cˇ , A.; Mety sˇ ov a´ , J.; Kak a´ cˇ , B.; Holubek, J.;
Sv a´ tek, E.; Sediv y´ , Z.; Protiva, M. Collect. Czech. Chem. Commun. 1975,
40, 1940. (b) Perchonock, C. D.; Uzinskas, I.; McCarthy, M. E.; Erhard,
K. F.; Gleason, J. G.; Wasserman, M. A.; Muccitelli, R. M.; DeVan, J. F.;
Tucker, S. S.; Vickery, L. M.; Kirchner, T.;. Weichman, B. M.; Mong, S.;
Scott, M. O.; Chi-Rosso, G.; Wu, H.-L.; Croole, S. T.; Newton, J. F. J.
Med. Chem. 1986, 29, 1442.
1-alkoxybut-3-enyl)benzene.11 2-Bromobenzaldehyde, 2-bromo-
(
(10) For a review, see: Brandsma, L.; Vasilevsky, S. F.; Verkruijsse,
H. D. Application of Transition Metal Catalyst in Organic Synthesis;
Springer-Verlag: Berlin, Heidelberg, 1999; Chapter 10.
(15) Yasuda, M.; Saito, T.; Ueba, M.; Baba, A. Angew. Chem., Int. Ed.
2004, 43, 1414.
(11) Yadav, J. S.; Subba Reddy, B. V.; Srihari, P. Synlett 2001, 673.
6208 J. Org. Chem., Vol. 71, No. 16, 2006

Allyl(ethynylaryl)carbinol Transformation into Indenes
+
0
2
2
4
6
.82 (t, J ) 7.2 Hz, 3H), 1.29-1.23 (m, 2H), 1.42-1.37 (m, 2H),
.49 (dd, J ) 7.2, 13.6 Hz, 1H), 2.69 (dd, J ) 7.2, 13.6 Hz, 1H),
.92 (td, J ) 6.8, 8.8 Hz, 1H), 3.12 (td, J ) 6.4, 9.2 Hz, 1H),
.97-4.92 (m, 2H), 5.73-5.65 (m, 1H), 6.19 (d, J ) 6.0 Hz, 1H),
.68 (d, J ) 6.0 Hz, 1H), 7.30-7.14 (m, 4H); 13C NMR (100 MHz,
14 13 3 13 3
C H F O (M ) 254.1, found 254.0. Anal. Calcd for C14H F O
(254.25): C, 66.14; H, 5.15; F, 22.42. Found: C, 66.17; H, 5.36.
Data for 1-allyl-1-methoxy-6-(trifluoromethyl)-1H-indene
0.42 (silica gel, hexane/EtOAc, 10/1); yield 9%; H NMR
(400 MHz, CDCl
1
(2i): R
f
3
) δ 2.51 (dd, J ) 7.2, 14.0 Hz, 1H), 2.68 (dd, J
CDCl
3
) δ 14.0, 19.3, 32.5, 42.4, 63.4, 89.0, 117.3, 121.2, 122.5,
) 7.2, 14.0 Hz, 1H), 2.96 (s, 3H), 5.01-4.96 (m, 2H), 5.75-5.65
125.7, 128.2, 132.1, 133.7, 140.0, 142.7, 145.7; IR (neat) 3070-
2870, 1639, 1464, 1315, 1281, 1094, 993, 914, 789, 756 cm
(m, 1H), 6.36 (d, J ) 5.6 Hz, 1H), 6.75 (d, J ) 5.6 Hz, 1H), 7.28-
-
1
13
;
7.26 (m, 1H), 7.53-7.51 (m, 2H); C NMR (100 MHz, CDCl
3
) δ
+
HRMS (EI) m/z calcd for C16
Anal. Calcd for C16 20O (228.33): C, 84.16; H, 8.83. Found: C,
4.29; H, 8.92.
Data for 1-allyl-1-benzyloxy-1H-indene (2d): R
H
20O (M ) 228.1514, found 228.1514.
42.0, 52.0, 90.0, 117.3, 118.3, 119.3, 121.4, 126.0, 126.1, 131.9,
H
132.9, 142.4, 145.7, 146.2; IR (neat) 3076-2827, 1431, 1331, 1267,
-
1
8
1165, 1122, 1076, 1053, 918, 839 cm ; GC-MS m/z calcd for
+
C
14
H
13
F
3
O (M ) 254.1, found 254.0. Anal. Calcd for C14
13 3
H F O
f
0.38 (silica
gel, hexane/EtOAc, 10/1); yield 49%; H NMR (400 MHz, CDCl
δ 2.58 (dd, J ) 7.2, 13.6 Hz, 1H), 2.79 (dd, J ) 7.2, 13.6 Hz, 1H),
.02 (d, J ) 11.6 Hz, 1H), 4.18 (d, J ) 11.6 Hz, 1H), 5.01-4.96
m, 2H), 5.83-5.73 (m, 1H), 6.25 (d, J ) 5.6 Hz, 1H), 6.74 (d, J
5.6 Hz, 1H), 7.38-7.17 (m, 9H); 13C NMR (100 MHz, CDCl
1
(254.25): C, 66.14; H, 5.15; F, 22.42. Found: C, 66.41; H, 5.28.
3
)
16
Data for 1-vinylnaphthalene (4a): R
f
0.66 (silica gel, hexane/
EtOAc, 10/1); H NMR (400 MHz, CDCl ) δ 5.48 (dd, J ) 1.6,
0.8 Hz, 1H), 5.80 (dd, J ) 1.6, 17.2 Hz, 1H), 7.54-7.40 (m, 4H),
1
4
(
)
3
1
1
3
7.64-7.62 (m, 1H), 7.87-7.78 (m, 2H), 8.15-8.11 (m, 1H);
NMR (100 MHz, CDCl ) δ 117.0, 123.5, 123.7, 125.5, 125.7, 126.0,
28.0, 128.4, 131.0, 133.5, 134.3, 135.5; IR (neat) 3085-2978,
618, 1590, 1509, 1418, 1389, 1341, 1168, 1009, 986, 916, 861,
C
3
)
δ 42.3, 65.7, 89.5, 117.6, 121.4, 122.7, 126.0, 127.1, 127.2, 128.1,
3
1
1
1
2
7
2
28.4, 132.6, 133.6, 139.3, 139.5, 142.8, 145.2; IR (neat) 3067-
860, 1637, 1558, 1497, 1456, 1379, 1317, 1097, 1063, 993, 916,
-
1
+
-1
+
800, 777 cm ; GC-MS m/z calcd for C H (M ) 154.1, found
56 cm ; HRMS (EI) m/z calcd for C19
H
18O (M ) 262.1358, found
12 10
1
54.0.
Data for 7-(trifluoromethyl)-1-vinylnaphthalene (4b): R
silica gel, hexane/EtOAc, 10/1); yield 15%; 1H NMR (400
MHz, CDCl ) δ 5.55 (dd, J ) 1.2, 10.8 Hz, 1H), 5.81 (dd,
J ) 1.2, 17.2 Hz, 1H), 7.48-7.41 (m, 1H), 7.58-7.54 (m, 1H),
62.1359. Anal. Calcd for C19 18O (262.35): C, 86.99; H, 6.92.
H
f
0.58
Found: C, 86.67; H, 7.15.
(
Data for 1-allyl-1,6-dimethoxy-1H-indene (2e): R
f
0.55 (silica
gel, hexane/EtOAc, 8/2); yield 65%; H NMR (400 MHz, CDCl
δ 2.48 (dd, J ) 7.2, 14.0 Hz, 1H), 2.67 (dd, J ) 7.2, 14.0 Hz, 1H),
1
3
3
)
7
8
1
.70-7.63 (m, 2H), 7.83-7.81 (m, 1H), 7.95-7.93 (m, 1H), 8.43-
.37 (m, 1H); 13C NMR (100 MHz, CDCl
) δ 118.4, 121.3, 121.7,
24.8, 125.8, 127.5, 127.8, 127.8, 129.5, 129.9, 133.5, 134.7, 136.6;
IR (neat) 3090-2924, 1462, 1313, 1234, 1161, 1122, 1068, 837,
9 3
54, 739 cm ; GC-MS m/z calcd for C13H F (M ) 122.1, found
2
6
1
.96 (s, 3H), 3.81 (s, 3H), 5.03-4.97 (m, 2H), 5.76-5.66 (m, 1H),
.06 (d, J ) 5.6 Hz, 1H), 6.66 (d, J ) 5.6 Hz, 1H), 6.76-6.74 (m,
H), 6.91-6.89 (m, 1H), 7.09-7.07 (m, 1H); 13C NMR (100 MHz,
3
CDCl
3
) δ 42.6, 51.7, 55.5, 89.6, 109.7, 112.8, 117.6, 121.7, 132.4,
33.5, 135.6, 137.0, 147.0, 158.7; IR (neat) 3074-2825, 1599,
475, 1429, 1364, 1313, 1279, 1161, 1101, 1068, 1030, 916, 816,
-
1
+
7
1
1
1
7
22.0.
-
1
+
Data for 6-(trifluoromethyl)-1-vinylnaphthalene (4c): R
f
0.62
silica gel, hexane/EtOAc, 10/1); yield 16%; H NMR (400 MHz,
CDCl ) δ 5.53 (dd, J ) 1.2, 11.2 Hz, 1H), 5.80 (dd, J ) 1.2, 17.2
81 cm ; HRMS (EI) m/z calcd for C14
H
16
O
2
(M ) 216.1150,
1
(
found 216.1150. Anal. Calcd for C14
.46. Found: C, 77.60; H, 7.35.
Data for 1-allyl-1,5-dimethoxy-1H-indene (2f): R
16 2
H O (216.28): C, 77.75; H,
3
7
Hz, 1H), 7.73-7.40 (m, 4H), 7.86-7.84 (m, 1H), 8.22-8.13 (m,
H); C NMR (100 MHz, CDCl
25.7, 126.1, 126.9, 127.4, 128.1, 128.7, 132.3, 133.6, 135.8; IR
neat) 3088-2926, 1473, 1381, 1346, 1315, 1234, 1198, 1124,
074, 918, 899, 831, 798, 758, 739 cm ; GC-MS m/z calcd for
f
0.31 (silica
gel, hexane/EtOAc, 10/1); yield 20%; H NMR (400 MHz, CDCl
δ 2.50 (dd, J ) 7.2, 14.0 Hz, 1H), 2.66 (dd, J ) 7.2, 14.0 Hz, 1H),
13
2
1
3
) δ 118.1, 121.5, 121.5, 125.0,
1
3
)
(
1
C
2
6
1
.94 (s, 3H), 3.80 (s, 3H), 5.01-4.96 (m, 2H), 5.76-5.66 (m, 1H),
.19 (d, J ) 5.6 Hz, 1H), 6.66 (d, J ) 5.6 Hz, 1H), 6.70-6.68 (m,
H), 6.77-6.75 (m, 1H), 7.19-7.16 (m, 1H); 13C NMR (100 MHz,
-1
+
13
H
9
F
3
(M ) 122.1, found 122.0.
Data for 1-allyl-1-phenyl-1H-indene (6): yellow liquid; H
NMR (400 MHz, CDCl ) δ 2.84 (dd, J ) 6.8, 14.0 Hz, 1H), 3.05
dd, J ) 7.6, 14.0 Hz, 1H), 4.99-4.94 (m, 1H), 4.89-4.85 (m,
1
CDCl
3
) δ 42.3, 51.5, 55.4, 89.0, 108.0, 110.4, 117.6, 123.2, 132.5,
3
133.7, 136.6, 140.5, 144.5, 160.2; IR (neat) 3072-2833, 1610,
1508, 1473, 1431, 1279, 1257, 1232, 1032, 916, 831, 787 cm
(
-
1
;
1
5
4
1
1
H), 5.49-5.42 (m, 1H), 6.55 (d, J ) 5.6 Hz, 1H), 6.78 (d, J )
+
GC-MS m/z calcd for C14
Calcd for C14
H, 7.07.
H
16
O
2
(M ) 216.1, found 216.0. Anal.
13
3
.6 Hz, 1H), 7.32-7.12 (m, 10H); C NMR (100 MHz, CDCl ) δ
16 2
H O (216.28): C, 77.75; H, 7.46. Found: C, 78.02;
1.0, 60.6, 117.3, 121.4, 123.3, 125.3, 126.3, 126.5, 126.8, 128.4,
30.0, 134.3, 141.6, 143.4, 144.2, 150.7; IR (neat) 3062-2923,
654, 1496, 1461, 1033, 914 cm ; HRMS (EI) m/z calcd for C18H
6
M ) 232.1252, found 232.1250.
2
Deuterium-Labeling Experiment. To a mixture of PtBr (5.3
mg, 0.015 mmol, 5 mol %) and 1-ethynyl-2-(1-deuterio-1-meth-
oxybut-3-enyl)benzene (1a-d) (56.4 mg, 0.3 mmol) was added
3
CH CN (5.0 mL, 0.06 M) under an argon atmosphere in a micro-
reactor. The mixture was stirred for 20 min at room temperature
Data for 1-allyl-6-fluoro-1-methoxy-1H-indene (2g): R
f
0.40
silica gel, hexane/EtOAc, 10/1); yield 50%; H NMR (400 MHz,
CDCl ) δ 2.48 (dd, J ) 7.2, 14.0 Hz, 1H), 2.65 (dd, J ) 7.2, 14.0
-1
1
(
+
(
3
Hz, 1H), 2.96 (s, 3H), 5.02-4.96 (m, 2H), 5.74-5.64 (m, 1H),
6
1
.16 (d, J ) 5.6 Hz, 1H), 6.67 (d, J ) 5.6 Hz, 1H), 6.94-6.89 (m,
H), 7.03-7.00 (m, 1H), 7.12-7.09 (m, 1H); 13C NMR (100 MHz,
3
CDCl ) δ 42.2, 51.8, 89.6, 110.8, 114.8, 118.0, 122.0, 132.0, 133.1,
1
38.7, 147.6, 160.8, 163.5; IR (neat) 3076-2825, 1641, 1603, 1472,
and then heated at 120 °C for 12 h. The product was filtered through
a short column of SiO using ethyl acetate as an eluent, and the
2
-1
1427, 1362, 1257, 1101, 987, 912, 872, 825, 783, 739 cm ; HRMS
+
(EI) m/z calcd for C13
H
13FO (M ) 204.0950, found 204.0952. Anal.
resulting filtrate was concentrated. The residue was purified by
column chromatography (silica gel, hexane/ethyl acetate, 100/1)
to afford 2a-d in 50% yield (28.1 mg), and 4a-d was obtained in
6% isolated yield (2.7 mg).
Computational Details. Geometries of all stationary points were
optimized using analytical energy gradients of self-consistent-field
theory and density functional theory (DFT).17 The latter utilized
Calcd for C13
C, 76.34; H, 6.64.
H13FO (204.24): C, 76.45; H, 6.42; F, 9.30. Found:
Data for 1-allyl-1-methoxy-5-(trifluoromethyl)-1H-indene
1
(
(
)
(
2h): R
400 MHz, CDCl
7.2, 14.0 Hz, 1H), 2.95 (s, 3H), 5.00-4.96 (m, 2H), 5.75-5.65
m, 1H), 6.30 (d, J ) 5.6 Hz, 1H), 6.75 (d, J ) 5.6 Hz, 1H), 7.47-
f
0.42 (silica gel, hexane/EtOAc, 10/1); yield 21%; H NMR
3
) δ 2.51 (dd, J ) 7.2, 14.0 Hz, 1H), 2.67 (dd, J
18
Becke’s three-parameter exchange-correlation functional including
the nonlocal gradient corrections described by Lee-Yang-Parr
7
1
1
1
.38 (m, 3H); 13C NMR (100 MHz, CDCl
3
) δ 42.0, 52.0, 90.0,
18.2, 118.2, 122.7, 123.1, 130.7, 131.0, 131.9, 132.9, 141.1, 143.4,
48.8; IR (neat) 3078-2827, 1431, 1360, 1321, 1269, 1165, 1126,
076, 1053, 920, 895, 837, 791, 746 cm-1; GC-MS m/z calcd for
(
16) Littke, A. F.; Schwarz, L.; Fu, G. C. J. Am. Chem. Soc. 2002, 124,
6343.
J. Org. Chem, Vol. 71, No. 16, 2006 6209

Bajracharya et al.
(
LYP),19 as implemented in the Gaussian 03 program package.20
All geometry optimizations were performed using the SDD basis
Supporting Information Available: NMR charts, Cartesian
Coordinates, and full Gaussian citation. This material is available
free of charge via the Internet at http://pubs.acs.org.
21
set. This approach is widely used for the recent computational
studies of transition-metal complexes and was shown to yield results
JO060951G
8,22
conforming with experimental data in our work
and the work
of others.23
(20) Gaussian 03, Revision B.05: M. J. Frisch et al., Gaussian, Inc.,
Pittsburgh PA, 2003 (full reference in the Supporting Information).
(21) (a) Dunning, T. H., Jr.; Hay, P. J. In Modern Theoretical Chemistry;
Schaefer, H. F., III, Ed.; Plenum: New York, 1976; Vol. 3, p 1. (b)
Leininger, T.; Nicklass, A.; Stoll, H.; Dolg, M.; Schwerdtfeger, P. J. Chem.
Phys. 1996, 105, 1052.
Acknowledgment. The computational results in this research
were obtained using supercomputing resources at the Informa-
tion Synergy Center, Tohoku University.
(22) (a) Nishikata, T.; Yamamoto, Y.; Gridnev, I. D.; Miyaura, N.
Organometallics 2005, 25, 5025. (b) Gridnev, I. D.; del Rosario, M. K. C.;
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Yashio, K.; Crepy, K. V. L.; Katagiri, K.; Takahashi, H.; Kouchi, M.;
Gridnev, I. D. Organometallics 2006, 26, 908. (d) Patil, N. T.; Lutete, L.
M.; Wu, H.; Pahadi, N. K.; Gridnev, I. D.; Yamamoto, Y. J. Org. Chem.
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McKee, M. L.; Swart, M. Inorg. Chem. 2005, 44, 6975. (c) Kondo, T.;
Tsunawaki, F.; Ura, Y.; Sadaoka, K.; Iwasa, T.; Wada, K.; Mitsudo, T.
Organometallics 2005, 24, 905. (d) Nowroozi-Isfahani, T.; Musaev, D. G.;
McDonald, F. E.; Morokuma, K. Organometallics 2005, 24, 2921.
(
17) (a) Parr, R. G.; Yang, W. Density Functional Theory of Atoms and
Molecules; Oxford University Press: New York, 1989. (b) Cheeseman, J.
R.; Frisch, M. J.; Devlin, F. J.; Stephens, P. J. Chem. Phys. Lett. 2 1996,
5
2, 211.
18) (a) Becke, A. D. Phys. ReV. A 1988, 38, 3098. (b) Becke, A. D. J.
Chem. Phys. 1993, 98, 5648.
19) (a) Lee, C.; Yang, W.; Parr, R. G. Phys. ReV. B 1988, 37, 785. (b)
Miehlich, B.; Savin, A.; Stoll, H.; Preuss, H. Chem. Phys. Lett. 1989, 157,
00.
(
(
2
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