Synthesis of novel dimeric allylpalladium(II) complexes from PdC1 2-Promoted Ring-Opening reactions of vinylidenecyclopropanes

Article abstract of DOI:10.1021/om801117g

Novel dimeric allylpalladium(II) complexes have been successfully synthesized from the transition metal PdC1₂-promoteci ring-opening reactions of VDCPs 1 in good yields. These dimeric allylpalladium(II) complexes have been characterized by X-ra

Full text of DOI:10.1021/om801117g

Organometallics 2009, 28, 1569–1574
1569
Synthesis of Novel Dimeric Allylpalladium(II) Complexes from
PdCl2-Promoted Ring-Opening Reactions of
Vinylidenecyclopropanes
Xingxing Gu,† Feijun Wang,*,† Ming-hui Qi,† Li-xiong Shao,† and Min Shi*,†,‡
School of Chemistry & Molecular Engineering, East China UniVersity of Science and Technology,
130 MeiLong Road, Shanghai 200237, People’s Republic of China, and State Key Laboratory of
Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Road, Shanghai 200032, People’s Republic of China
ReceiVed NoVember 23, 2008
Novel dimeric allylpalladium(II) complexes have been successfully synthesized from the transition
metal PdCl2-promoted ring-opening reactions of VDCPs 1 in good yields. These dimeric allylpalladium(II)
complexes have been characterized by X-ray crystal structure diffraction.
Scheme 1. Transition Metal-Catalyzed Reactions of
Methylenecyclopropanes (MCPs)
Introduction
Transition metal-catalyzed reactions of strained cyclic hy-
drocarbons such as methylenecyclopropanes (MCPs) and cy-
clopropenes have been widely explored and have received
considerable attention from synthetic and mechanistic viewpoints
since the middle of the 20th century.1 The reaction course of
MCPs with transition metal catalysts (M) may be categorized
into the following four patterns (Scheme 1).2 Among them the
most significant findings are the selective cleavage of the
proximal (C2-C3 or C2-C4) and/or distal bonds (C3-C4) of
MCPs catalyzed by palladium to afford the corresponding ring-
opening products under mild conditions. So far, only two papers
have been reported regarding the transition metal-catalyzed
reactions of vinylidenecyclopropanes (VDCPs),3 which are also
highly strained but readily accessible and stable molecules that
serve as useful building blocks in many organic synthesis.4 It
is necessary to study the coordination behavior of VDCPs with
transition metal so as to develop novel synthetic methods using
VDCPs in the presence of transition metals.
numerous palladium-catalyzed reactions, offering many syn-
thetically useful methods for organic chemists.5 These allylpal-
ladium complexes are mainly prepared from oxidative addition
of Pd(0) complexes and insertion reactions of Pd(II) complexes
with the corresponding allylic compounds. Recently, Battiste
and co-workers have reported the ring-opening reaction of
cyclopropenes by using [(PhCN)2PdCl2] under mild conditions
to give a novel type of allylpalladium complexes in good yields
(Scheme 2).6 Furthermore, we have recently also disclosed that
the ring-opening reaction of MCPs and VDCPs could take place
to give the corresponding ring-opened products under mild
conditions in the presence of Lewis acids such as BF3 · OEt2,
MCln (M ) Al, Zn or Sn etc), or Ln(OTf)m (Ln ) Yb, Sm, Sc,
It is well known that allylpalladium complexes, as the active
intermediates or the precursors of active organometallic com-
plexes, have been widely used as the catalysts or reagents in
* Corresponding author. (M.S.) Fax: 86-21-64166128. E-mail: Mshi@
mail.sioc.ac.cn. (F.W.) E-mail: feijunwang@ecust.edu.cn.
† East China University of Science and Technology.
‡ Shanghai Institute of Organic Chemistry.
(1) (a) Krief, A. Top. Curr. Chem. 1987, 135, 1. (b) Binger, P.; Bu¨ch,
H. M. Top. Curr. Chem. 1987, 135, 77. (c) Ohta, T.; Takaya, H. In
ComprehensiVe Organic Synthesis; Pergamon Press: Oxford, 1991; Vol. 5,
p 1185. (d) Carbocyclic Three-Membered Ring Compounds, Houben-Weyl;
de Meijere, A., Ed.; Thieme: Stuttgart, 1996; Vol. E17. (e) Brandi, A.; Goti,
A. Chem. ReV. 1998, 98, 589. (f) Brandi, A.; Cicchi, S.; Cordero, F. M.;
Goti, A. Chem. ReV. 2003, 103, 1213.
(2) Nakamura, I.; Yamamoto, Y. AdV. Synth. Catal. 2002, 344, 111.
(3) (a) Lu, J.-M.; Shi, M. Tetrahedron 2006, 62, 9115. (b) Stepakov,
A. V.; Larina, A. G.; Molchanov, A. P.; Stepakova, L. V.; Starova, G. L.;
Kostikov, R. R. Russ. J. Org. Chem. 2007, 43, 40.
(4) (a) Lu, J.-M.; Shi, M. Org. Lett. 2008, 10, 1943. (b) Liu, L.-P.; Lu,
J.-M.; Shi, M. Org. Lett. 2007, 9, 1303. (c) Shi, M.; Lu, J.-M. J. Org. Chem.
2006, 71, 1920. (d) Mizuno, K.; Nire, K.; Sugita, H.; Maeda, H. Tetrahedron
Lett. 2001, 42, 2689. (e) Maeda, H.; Hirai, T.; Sugimoto, A.; Mizuno, K.
J. Org. Chem. 2003, 68, 7700. (f) Su, C.; Huang, X.; Liu, Q. J. Org. Chem.
2008, 73, 6421. (g) Mizuno, K.; Maeda, H.; Sugita, H.; Nishioka, S.; Hirai,
T.; Sugimoto, A. Org. Lett. 2001, 3, 581. (h) Mizuno, K.; Ichinose, N.;
Yoshimi, Y. J. Photochem. Photobiol. C: Photochem. ReV. 2000, 1, 167.
(i) Ma, S.; He, Q. Tetrahedron 2006, 62, 2769. (j) Li, W.; Shi, M. J. Org.
Chem. 2008, 73, 4151.
(5) (a) Maitlis, P. M. The Organic Chemistry of Palladium; Academic
Press: New York, 1971; Vols. 1 and 2. (b) Tsuji, J. Organic Synthesis with
Palladium Compounds; Springer-Verlag: New York, 1980. (c) Heck, R. F.
Palladium Reagents in Organic Synthesis; Academic Press: New York,
1985. (d) Larock, R. C. In AdVances in Metal-Organic Chemistry;
Liebeskind, L. S., Ed.; JAI Press: London, 1994; Vol. 5, Chapter 3. (e)
Tsuji, J. Palladium Reagents and Catalysts: InnoVations in Organic
Synthesis; Wiley and Sons: New York, 1995. (f) Li, J. J.; Gribble, G. W.
Palladium in Heterocyclic Chemistry; Pergamon: New York, 2000. (g)
Negishi, E. Handbook of Organopalladium Chemistry for Organic Synthesis;
Wiley and Sons: New York, 2002; Vols. 1 and 2.
(6) (a) Mushak, P.; Battiste, M. A. J. Organomet. Chem. 1969, 17, 46.
(b) Battiste, M. A.; Friedrich, L. E.; Fiato, R. A. Tetrahedron Lett. 1975,
45. (c) Fiato, R. A.; Mushak, P.; Battiste, M. A. J. Chem. Soc., Chem.
Commun. 1975, 869.
10.1021/om801117g CCC: $40.75
2009 American Chemical Society
Publication on Web 02/11/2009

1570 Organometallics, Vol. 28, No. 5, 2009
Scheme 2. Pd(II) Complex-Promoted Ring-Opening
Gu et al.
Scheme 4. Reactions of PdCl2 with VDCPs 1a-e
Reactions of Cyclopropenes
Scheme 3. Synthesis of VDCPs 1
moisture stable in the solid state and even in the solution state.
Their structures were determined by microanalysis, IR and NMR
spectroscopic data, and ESI-MS spectroscopy. It should be noted
that complex 2 may exist in four isomers (trans-anti-2, trans-
syn-2, cis-anti-2, and cis-syn-2) (Scheme 4).9 On the basis of
1
their H NMR spectroscopic data, complex 2 was assigned as
only two isomers in a nearly equimolar ratio. The signal for
the allylic proton of these two isomers was relatively close in
chemical shift, suggesting that the two isomers were trans-anti-2
and cis-anti-2. Moreover, the syn-isomer did not exist because
of the steric interaction between the R5 group and the isopro-
penyl group.9,10 Single crystals of 2e were obtained by recrys-
tallization from a mixed solvent of dichloromethane/petroleum
ether (1:4), and its structure was unambiguously determined by
X-ray diffraction.11 An ORTEP drawing of 2e is depicted in
Figure 1. As can be seen from Figure 1, the palladium(II) center
is in a slightly distorted planar geometry, defined by two chloride
atoms and one allyl group. The angle of the C(2)-Pd(1)-C(4)
plane is 69.6°, smaller than the sum angle of C(2)-Pd(1)-C(3)
and C(3)-Pd(1)-C(4), which is 38.8° and 38.9°, respectively.
The bond length of Pd-C is comparable to its analogues.10,12
To optimize the reaction conditions of PdCl2 with VDCPs 1,
various solvents, reaction temperatures, and employed amounts
of PdCl2 were investigated using 1a as a model reactant. The
results of these experiments are shown in Table 1. It was found
that THF is the solvent of choice, affording the corresponding
dimeric allylpalladium(II) complex 2a in 68% yield at 50 °C
(Table 1, entries 1-6). Raising or lowering the reaction
temperature did not improve the yield of 2a (Table 1, entries 7
and 8). Increasing the employed amounts of PdCl2 produced
2a in 60% and 53% yield, respectively (Table 1, entries 9 and
10). Under these optimized reaction conditions, as for other
reactants 1b-e having different electronic properties of aryl
groups, the corresponding dimeric allylpalladium(II) complexes
La, etc.).7 These interesting results stimulated us to further
investigate the reactions of PdCl2 with VDCPs 1. Herein we
report a novel synthetic method of allylpalladium complexes
from the ring-opening reactions of VDCPs 1 with PdCl2 along
with their application in Suzuki coupling reactions.
Results and Discussion
Reactions of VDCPs 1 with Transition Metal PdCl2. A
series of multiaryl-substituted VDCPs 1 was synthesized ac-
cording to the previously reported procedures, and their
structures are shown in Scheme 3.8 First, triaryl-substituted
VDCPs 1a-e (R1, R2, and R5 ) aryl group) were used as the
substrates to react with PdCl2 in tetrahydrofuran (THF) at 50
°C (Scheme 4). It was found that a novel type of dimeric
allylpalladium(II) complexes, 2a-e, was obtained in moderate
yields. These dimeric allylpalladium(II) complexes are air and
(7) (a) Shi, M.; Xu, B. Org. Lett. 2002, 4, 2145. (b) Shi, M.; Chen, Y.;
Xua, B.; Tang, J. Tetrahedron Lett. 2002, 43, 8019. (c) Xu, B.; Shi, M.
Org. Lett. 2003, 5, 1415. (d) Shi, M.; Chen, Y. J. Fluorine Chem. 2003,
122, 219. (e) Huang, J.-W.; Shi, M. Tetrahedron Lett. 2003, 44, 9343. (f)
Shi, M.; Chen, Y.; Xu, B.; Tang, J. Green Chem. 2003, 5, 85. (g) Shao,
L.-X.; Huang, J.-W.; Shi, M. Tetrahedron 2004, 60, 11895. (h) Liu, L.-P.;
Shi, M. Chem. Commun. 2004, 2878. (i) Wang, B.-Y.; Jiang, R.-S.; Li, J.;
Shi, M. Eur. J. Org. Chem. 2005, 4002. (j) Shi, M.; Liu, L.-P.; Tang, J.
J. Am. Chem. Soc. 2006, 128, 7430. (k) Shi, M.; Liu, L.-P.; Tang, J. Org.
Lett. 2006, 8, 4043. (l) Shi, M.; Jiang, M.; Liu, L.-P. Org. Biomol. Chem
2007, 5, 438. (m) Lu, J.-M.; Shi, M. Tetrahedron 2007, 63, 7545. (n) Lu,
J.-M.; Shi, M. J. Org. Chem. 2008, 73, 2206. (o) Shi, M.; Wu, L.; Lu,
J.-M. Tetrahedron 2008, 64, 3315. (p) Xu, G.-C.; Liu, L.-P.; Lu, J.-M.;
Shi, M. J. Am. Chem. Soc. 2005, 127, 14552. (q) Zhang, Y.-P.; Lu, J.-M.;
Xu, G.-C.; Shi, M. J. Org. Chem. 2007, 72, 509.
(9) Rosset, J.-M.; Glenn, M. P.; Cotton, J. D.; Willis, A. C.; Kennard,
C. H. L.; Byriel, K. A.; Riches, B. H.; Kitching, W. Organometallics 1998,
17, 1968–1983.
(10) Lukas, J.; Ramakers-Blom, J. E.; Hewitt, T. G.; De Boer, J. J. J.
Organomet. Chem. 1972, 46, 167.
(11) The crystal data of 2e have been deposited in the CCDC with
number 671929. Empirical formula: C50H40Br2Cl2Pd2; formula weight:
1084.34; crystal color, habit: colorless, prismatic; crystal system: monoclinic;
lattice type: primitive; lattice parameters: a ) 15.4519(12) Å, b ) 7.9145(6)
Å, c ) 18.5937(15) Å, R ) 90°, ꢀ ) 99.013(2)°, γ ) 90°, V ) 2245.8(3)
Å3; space group: P2(1)/c; Z ) 2; Dcalc ) 1.604 g/cm3; F000 ) 1072;
diffractometer: Rigaku AFC7R; residuals: R, Rw: 0.0568, 0.1132.
(12) (a) Zhang, T.; Wang, W.; Gu, X.; Shi, M. Organometallics 2008,
27, 753. (b) Liu, Z.; Zhang, T.; Shi, M. Organometallics 2008, 27, 2668.
(c) Larock, R. C.; Song, H.; Kim, S.; Jacobson, R. A. J. Chem. Soc., Chem.
Commun. 1987, 834.
(8) (a) Isagawa, K.; Mizuno, K.; Sugita, H.; Otsuji, Y. J. Chem. Soc.,
Perkin Trans 1 1991, 2283. (b) Sugita, H.; Mizuno, K.; Mori, T.; Isagawa,
K.; Otsuji, Y. Angew. Chem. 1991, 103, 1000. ; Angew. Chem. Int. Ed.
Engl. 1991, 30, 984.

NoVel Dimeric Allylpalladium(II) Complexes
Organometallics, Vol. 28, No. 5, 2009 1571
Table 2. Reactions of PdCl2 with Tetraaryl-Substituted VDCPs
1f-k
yield (%)b
entrya
1
3
4
1
2
3
4
5
6
1f
3a, 69
3b, 82
3c, 48
3d, 79
3e, 70
3f, 59
trace
trace
4c, 41
trace
4e, 20
4f, 32
1g
1h
1i
1j
1k
a All reactions were carried out using 1 (0.2 mmol) and PdCl2 (1.2
equiv) in THF (3 mL) at 50 °C for 3 h. b Isolated yields as mixtures of
trans-syn-3 and cis-syn-3 (1:1).
Figure 1. ORTEP drawing of dimeric allylpalladium(II) complex
2e with thermal ellipsoids at the 30% probability level. Selected
bond distances (Å) and angles (deg): C1-C2 ) 1.315(8), C2-C3
) 1.384(8), C3-C4 ) 1.415(8), C4-C8 ) 1.449(8), Pd1-C2 )
2.034(6), Pd1-C3 ) 2.121(6), Pd1-C4 ) 2.127(6), C2-Pd1-C3
) 38.8(2), C3-Pd1-C4 ) 38.9(2), C2-Pd1-C4 ) 69.6(2),
C2-C3-C4 ) 116.2(6).
Table 1. Optimized Reaction Conditions of PdCl2 with
Triaryl-Substituted VDCPs 1a-e
entrya reactant solvent PdCl2 (equiv) temp (°C) yield (%)b
1
2
3
4
5
6
7
8
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1b
1c
1d
1e
CH2Cl2
CH3CN
DMF
toluene
DCE
THF
THF
THF
THF
THF
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.5
2.0
1.2
1.2
1.2
1.2
40
50
50
50
50
50
rt
65
50
50
50
50
50
50
2a, 48
2a, 36
2a, 48
2a, 58
2a, 59
2a, 68
2a, 45
2a, 60
2a, 60
2a, 53
2b, 59
2c, 53
2d, 42
2e, 39
Figure 2. ORTEP drawing of dimeric allylpalladium(II) complex
3c with thermal ellipsoids at the 30% probability level. Selected
bond distances (Å) and angles (deg): C1-C2 ) 1.386(8), C2-C3
) 1.438(8), C1-Pd1 ) 2.041(6), C2-Pd1 ) 2.130(6), C3-Pd1
) 2.176(6), Pd1-Cl1 ) 2.3617(15), Pd1-Cl2 ) 2.4466(26),
C1-Pd1-C2 ) 38.7(2), C2-Pd1-C3 ) 39.0(2), C1-Pd1-C3
) 70.4(2), C1-C2-C3 ) 119.1(5), Cl1-Pd1-Cl2 ) 87.00(6).
9
10
11
12
13
14
THF
THF
THF
THF
Besides that, a novel type of dimeric allylpalladium(II) com-
plexes 3 was obtained; tetraaryl-substituted VDCPs 1h, 1j, and
1k, bearing electron-donating groups on the aromatic rings of
R3 and R4 as well as R1 and R2, could also give other products,
4, in moderate yields at the same time, which are derived from
PdCl2-catalyzed rearrangement of 1 (Table 2, entries 3, 5 and
6).7o-q The single crystals of 3c were grown from a mixed
solvent of dichloromethane/petroleum ether (1:4), and its X-ray
crystal structure is shown in Figure 2.13 The palladium(II) center
is in a slightly distorted planar geometry, defined by two chloride
atoms and one allyl group. The angle of the C(1)-Pd(1)-C(3)
plane is 70.4°, smaller than the sum angle of C(1)-Pd(1)-C(2)
and C(2)-Pd(1)-C(3), which is 38.7° and 39.0°, respectively.
The bond length of Pd-C is comparable to its analogue 2e.
a All reactions were carried out using 1 (0.2 mmol) in the presence of
the solvent (3 mL) for 12 h. b Isolated yields as mixtures of trans-anti-2
and cis-anti-2 (1:1).
2b-e were also obtained in moderate yields as mixtures of
trans-anti-2 and cis-anti-2, suggesting that the substituents on
the aromatic rings did not have a significant effect on the
reaction outcomes (Table 1, entries 11-14).
With the optimized reaction conditions in hand, the reactions
of PdCl2 with tetraaryl-substituted VDCPs 1f-k were investi-
gated, and the results of these experiments are summarized in
Table 2. A novel type of dimeric allylpalladium(II) complexes
3 was attained in moderate to good yields (Table 2, entries 1-6).
On the basis of their 13C NMR spectroscopic data, a cis-trans
isomerization equilibrium also existed in complex 3. The two
isomers were assigned as trans-syn-3 and cis-syn-3 by X-ray
diffraction.9,10 Furthermore, it was found that the electronic
properties of aryl groups had a remarkable influence on the
reactions of PdCl2 with tetraaryl-substituted VDCPs 1f-k.
(13) The crystal data of 3c have been deposited in the CCDC with
number 661676. Empirical formula: C64H54Cl2Pd2; formula weight: 1106.77;
crystal color, habit: colorless, prismatic; crystal system: monoclinic; lattice
type: primitive; lattice parameters: a ) 16.1405(11) Å, b ) 16.7692(11)
Å, c ) 22.9735(16) Å, R ) 90°, ꢀ ) 104.3370(10)°, γ ) 90°, V ) 6024.4(7)
Å3; space group: P2(1)/c; Z ) 4; Dcalc ) 1.220 g/cm3; F000 ) 2256;
diffractometer: Rigaku AFC7R; residuals: R, Rw: 0.0630, 0.1951.

1572 Organometallics, Vol. 28, No. 5, 2009
Gu et al.
Scheme 5. Plausible Mechanism for PdCl2-Promoted Ring-Opening Reactions of 1a-k
Scheme 6. Allylpalladium(II) Complexes-Catalyzed Suzuki
Coupling Reaction
On the basis of the above results, a plausible mechanism for
this interesting PdCl2 promoted ring-opening reaction and the
formation of dimeric allylpalladium(II) complexes is tentatively
outlined in Scheme 5. The coordination of 1 with PdCl2 produces
the initial zwitterionic intermediate A, from which the corre-
sponding cyclopropyl ring-opened zwitterionic intermediate B
is formed. The intermediate B can exist as intermediate C and
its resonance-stabilized intermediate C′. As for VDCPs 1a-e
(R3, R4 ) Me, R5 ) aryl group), intermediate C is a more
reactive species since it bears two alkyl groups R3 and R4 at
the C-1 position, which can be easily transformed to the
corresponding intermediate D along with the elimination of HCl.
Then, the corresponding dimeric allylpalladium(II) complexes
2a-e are produced from intermediate D. On the other hand, as
for VDCPs 1f-k (R3, R4 ) aryl group, R5 ) Me), intermediate
C′ is a more reactive species, which easily undergoes intramo-
lecular Friedel-Crafts reaction with the adjacent aromatic group
at the C-1 position (R3 group) to afford the corresponding
intermediate E along with the elimination of HCl. Intermediate
E can be transformed to the products 4 by protonation as well
as the corresponding dimeric allylpalladium(II) complexes 3a-f.
In the case of VDCPs 1h, 1j, and 1k, the formation of 4c, 4e,
and 4f is favored since R3 and R4 are electron-rich aromatic
groups, which can facilitate the intramolecular Friedel-Crafts
reaction.
coupling reaction. The details of these results have been
summarized in the Supporting Information.
Conclusion
In conclusion, we have developed a novel synthetic method
for the preparation of dimeric allylpalladium(II) complexes from
the ring-opening reactions of PdCl2 with VDCPs 1. These
dimeric allylpalladium(II) complexes have been isolated and
characterized by IR and NMR spectroscopic data and ESI-MS
spectroscopy. Moreover, two of them have been characterized
by X-ray crystal structure analyses. The catalytic activities of
these interesting complexes have been tested in the Suzuki
coupling reaction, and we have found that those complexes are
quite effective in the Suzuki coupling reaction under mild
conditions. Efforts are underway to develop novel synthetic
methods for transition metal-promoted ring-opening reactions
of VDCPs 1.
(14) (a) Son, S. U.; Kim, D. H.; Jung, I. G.; Chung, Y. K.; Lee, S.-G.;
Chun, S.-H. J. Polym. Sci., Part A: Polym. Chem 2002, 41, 76. (b) Joo,
J.-E.; Lee, K.-Y.; Pham, V.-T.; Ham, W.-H. Eur. J. Org. Chem. 2007, 1586.
(c) Terao, J.; Naitoh, Y.; Kuniyasu, H.; Kambe, N. Chem. Commun. 2007,
825. (d) Tilley, S. D.; Francis, M. B. J. Am. Chem. Soc. 2006, 128, 1080.
(e) Thomas, I. W.; Bruce, M. N. J. Org. Chem. 1994, 59, 5034. (f)
Nakamura, H.; Nakamura, K.; Yamamoto, Y. J. Am. Chem. Soc. 1998, 120,
4242. (g) Nakamura, H.; Shim, J.-G.; Yamamoto, Y. J. Am. Chem. Soc.
1997, 119, 8113.
Catalytic Abilities in Suzuki Coupling Reaction. Allylpal-
ladium complexes as catalysts have been widely applied in many
organic reactions such as coupling reactions, polymerization,
and allylation.14 Therein, we turned our interest to investigate
the catalytic abilities of these dimeric allylpalladium(II) com-
plexes in Suzuki coupling reactions. As shown in Scheme 6,
complexes 2b and 3a are effective catalysts in the Suzuki

NoVel Dimeric Allylpalladium(II) Complexes
Organometallics, Vol. 28, No. 5, 2009 1573
136.9, 139.8, 140.2. MS (ESI) m/z (%): 1045 [M - Cl]+, 505 [1/2M
- Cl]+. Anal. Calcd for C50H40 Br2Cl2Pd2: C, 55.38; H, 3.72. Found:
C, 55.11; H, 3.50.
General Procedure for the Synthesis of Dimeric Allylpalla-
dium(II) Complexes 3a-f and Indene Compounds 4c, 4e, and
4f. A mixture of VDCPs 1 (0.20 mmol) and PdCl2 (0.24 mmol)
was stirred in anhydrous THF (3 mL) at 50 °C for 3 h. The solvent
was removed under reduced pressure, and the residue was purified
by flash chromatography on silica gel (eluent: CH2Cl2 and petroleum
ether) to give dimeric allylpalladium(II) complexes 3 and products
4.
Dimeric Allylpalladium(II) Complex 3a (trans-syn-3a and
cis-syn-3a). Yellow solid. Mp: 155.2-158.4 °C. IR (CH2Cl2): ν
3055, 3024, 2960, 2922, 2853, 1490, 1470, 1443, 1375, 1335, 1155,
1075, 1028, 971, 771, 745, 731 cm-1. 1H NMR (300 MHz, CDCl3,
TMS): δ 1.66-1.73 (3H, m, CH3), 3.60-3.67 (1H, m), 7.07-7.47
(19H, m, ArH), 7.70-7.72 (1H, m). 13C NMR (75 MHz, CDCl3):
δ 19.0, 44.7, 45.0, 103.9,104.2, 106.4, 106.7, 124.1, 124.5, 127.4,
127.5, 127.8, 128.0, 128.4, 130.3, 130.5, 133.1, 133.3, 137.8, 139.7,
140.1, 142.4, 142.6, 147.6, 154.3. MS (ESI) m/z (%): 1013 [M -
Cl]+, 489 [1/2M - Cl]+. Anal. Calcd for C60H46Cl2Pd2: C, 68.58;
H, 4.41. Found: C, 68.64; H, 4.31.
Experimental Section
General Procedure for the Synthesis of Dimeric Allylpalla-
dium(II) Complexes 2a-e. A mixture of VDCPs 1 (0.20 mmol)
and PdCl2 (0.24 mmol) was stirred in anhydrous THF (3 mL) at
50 °C for 12 h. The solvent was removed under reduced pressure,
and the residue was purified by flash chromatography on silica gel
(eluent: CH2Cl2 and petroleum ether) to give dimeric allylpalla-
dium(II) complex 2.
Dimeric Allylpalladium(II) Complex 2a (trans-anti-2a and
cis-anti-2a). Yellow solid. Mp: 194.8-199.5 °C. IR (CH2Cl2): ν
3080, 3057, 3025, 1943, 1884, 1801, 1625, 1594, 1577, 1492, 1464,
1443, 1421, 1375, 1264, 1180, 1167, 1098, 1072, 1031, 1000, 913,
840, 824, 693 cm-1 1H NMR (300 MHz, CDCl3, TMS): δ
.
1.82-2.01 (3H, m, CH3), 5.09-5.14 (1H, m, CH2), 5.43-5.47 (1H,
m, CH2), 6.11-6.14 (1H, m, CH), 7.02-7.26 (15H, m, ArH). 13
C
NMR (75 MHz, CDCl3): δ 20.8, 21.0, 99.4, 99.6, 117.0, 127.0,
127.2, 127.4, 127.9, 128.0, 128.3, 128.5, 128.7, 130.4, 135.5, 135.6,
136.8, 137.0, 137.5, 139.8, 140.3. MS (ESI) m/z (%): 889 [M -
Cl]+, 427 [1/2M - Cl]+. Anal. Calcd for C50H42Cl2Pd2: C, 64.81;
H, 4.57. Found: C, 64.40; H, 4.40.
Dimeric Allylpalladium(II) Complex 2b (trans-anti-2b and
cis-anti-2b). Yellow solid. Mp: 115.7-119.4 °C. IR (CH2Cl2): ν
3084, 3023, 2920, 2852, 2395, 2294, 1655, 1624, 1608, 1508, 1492,
1459, 1448, 1420, 1375, 1265, 1181, 1108, 1097, 1020, 914, 821,
Dimeric Allylpalladium(II) Complex 3b (trans-syn-3b and
cis-syn-3b). Yellow solid. Mp: 159.2-163.8 °C. IR (CH2Cl2): ν
3067, 2960, 2924, 2854, 1600, 1505, 1469, 1261, 1231, 1156, 1015,
1
783, 752, 738, 720 cm-1. H NMR (300 MHz, CDCl3, TMS): δ
1
836, 746 cm-1. H NMR (400 MHz, CDCl3, TMS): δ 1.60-1.76
1.87-1.98 (3H, m, CH3), 2.32 (3H, s, CH3), 2.40-2.43 (3H, m,
CH3), 5.08-5.12 (1H, m, CH2), 5.41-5.44 (1H, m, CH2), 6.05-6.10
(1H, m, CH), 6.98-7.36 (13H, m, ArH). 13C NMR (75 MHz,
CDCl3): δ 20.9, 21.1, 21.4, 21.5, 99.3, 99.8, 116.6, 116.8, 127.0,
127.1, 127.8, 128.0, 128.5, 128.7, 129.2, 130.3, 130.4,134.2, 134.8,
135.0, 135.8, 136.6, 136.7, 137.3, 140.1, 140.7. MS (ESI) m/z (%):
957 [M - Cl]+, 461 [1/2M - Cl]+. Anal. Calcd for C54H50Cl2Pd2:
C, 66.00; H, 5.13. Found: C, 66.09; H, 5.11.
(3H, m, CH3), 3.45-3.70 (1H, m), 6.62-7.49 (17H, m, ArH),
7.63-7.75 (1H, m). 13C NMR (100 MHz, CDCl3): δ 19.0, 38.7,
39.0, 44.7, 45.1, 104.3, 104.7, 106.4, 106.6, 114.4, 114.5, 114.6,
114.7, 114.9, 115.2, 115.3, 115.4, 115.6, 123.9, 124.1, 124.2, 124.5,
124.6, 127.6, 127.9, 128.0, 128.2, 128.3, 128.4, 128.6, 128.9, 129.0,
129.1, 129.2, 129.3, 129.4, 132.0, 132.2, 132.96, 133.02, 133.1,
133.3, 133.6, 133.7, 134.0, 134.0, 135.9, 142.2, 142.4, 147.4, 147.5,
147.6, 154.3, 154.4, 160.9, 161.0, 161.1, 163.4, 163.4, 163.5. MS
(ESI) m/z (%): 1085 [M - Cl]+, 525 [1/2M - Cl]+. HRMS (ESI):
calcd for C60H42F4ClPd2 [M - Cl]+ 1085.0981, found 1085.0975.
Dimeric Allylpalladium(II) Complex 2c (trans-anti-2c and
cis-anti-2c). Yellow solid, Mp: 213.6-219.5 °C. IR (CH2Cl2): ν
3076, 3048, 3023, 2909, 2852, 2387, 2298, 1599, 1491, 1455, 1443,
1377, 1263, 1184, 1157, 1095, 1072, 1030, 916, 904, 840, 807,
Dimeric Allylpalladium(II) Complex 3c (trans-syn-3c and
cis-syn-3c). Yellow solid. Mp: 162.4-170.4 °C. IR (CH2Cl2): ν
3018, 3058, 2959, 2922, 2853, 1736, 1507, 1469, 1444, 1372, 1332,
765 cm-1. H NMR (300 MHz, CDCl3, TMS): δ 1.81-1.95 (3H,
1
m, CH3), 2.17-2.21 (3H, m, CH3), 5.07-5.12 (1H, m, CH2),
5.40-5.45 (1H, m, CH2), 6.08-6.11 (1H, m, CH), 6.86-6.92 (2H,
m, ArH), 7.12-7.42 (12H, m, ArH). 13C NMR (75 MHz, CDCl3,
TMS): δ 20.9, 21.0, 21.4, 21.45, 98.8, 99.1, 116.8, 127.0, 127.2,
127.4, 127.9, 128.2, 128.5, 129.5, 129.6, 130.4, 132.5, 132.7, 136.9,
137.2, 138.2, 139.9, 140.4. MS (ESI) m/z (%): 917 [M - Cl]+,
441 [1/2M - Cl]+. Anal. Calcd for C52H46Cl2Pd2+1/5CH2Cl2: C,
63.66; H, 4.77. Found: C, 63.67; H, 4.66.
1
1180, 1155, 1071, 1022, 918, 819, 773, 745, 730 cm-1. H NMR
(300 MHz, CDCl3, TMS): δ 1.64-1.72 (3H, m, CH3), 2.19-2.41
(6H, m, 2CH3), 3.52-3.65 (1H, m), 6.80-6.88 (1H, m, ArH),
7.07-7.46 (17H, m, ArH), 7.65-7.74 (1H, m). 13C NMR (75 MHz,
CDCl3): δ 19.0, 21.1, 21.4, 22.6, 31.6, 31.9, 106.4, 106.8, 124.1,
124.5, 127.4, 127.5, 127.8, 128.1, 128.4, 129.1, 130.2, 130.4, 133.4,
134.8, 136.7, 137.1, 142.6, 142.8, 147.7, 153.7. MS (ESI) m/z (%):
1069 [M - Cl]+, 517 [1/2M - Cl]+. Anal. Calcd for C64H54Cl2Pd2:
C, 69.45; H, 4.92. Found: C, 68.68.70; H, 5.01.
Dimeric Allylpalladium(II) Complex 2d (trans-anti-2d and
cis-anti-2d). Yellow solid, Mp: 210.1-215.9 °C. IR (CH2Cl2): ν
3082, 3056, 3022, 2376, 2296, 1958, 1592, 1490, 1443, 1377, 1261,
1175, 1164, 1092, 1072, 1029, 1013, 999, 929, 916, 905, 831, 816,
Dimeric Allylpalladium(II) Complex 3d (trans-syn-3d and
cis-syn-3d). Yellow solid. Mp: 158.5-163 °C. IR (CH2Cl2): ν 3056,
2974, 2921, 2379, 1874, 1713, 1613, 1602, 1509, 1489, 1477, 1441,
1369, 1336, 1292, 1278, 1244, 1224, 1160, 1137, 1065, 1027, 950,
765, 748 cm-1. H NMR (300 MHz, CDCl3, TMS): δ 1.85-1.95
1
(3H, m, CH3), 5.15-5.18 (1H, m, CH2), 5.44-5.48 (1H, m, CH2),
6.05 (1H, s, CH), 7.02-7.32 (14H, m, ArH). 13C NMR (75 MHz,
CDCl3): δ 20.8, 21.0, 99.8, 100.0, 117.3, 127.0, 127.4, 127.7, 128.0,
128.7, 129.0, 130.4, 133.7, 134.1, 136.7, 137.0, 137.5, 139.8, 140.2.
MS (ESI) m/z (%): 957 [M - Cl]+, 461 [1/2M - Cl]+. Anal. Calcd
for C50H40Cl4Pd2+1/6CH2Cl2: C, 59.05; H, 4.00. Found: C, 59.30;
H, 3.99.
1
905, 872, 821, 807, 775, 766, 734 cm-1. H NMR (300 MHz,
CDCl3, TMS): δ 1.69-1.79 (3H, m, CH3), 3.49-3.72 (1H, m),
6.70-7.41 (17H, m, ArH), 7.49-7.70 (1H, m). 13C NMR (75 MHz,
DMSO): δ 16.2, 49.4, 113.1 (d, JC-F ) 23.0 Hz), 114.3 (d, JC-F
)
21.6 Hz), 120.0, 120.1, 125.0, 126.6, 126.8, 127.0, 129.0, 130.3
(d, JC-F ) 8.3 Hz), 131.2, 131.9, 139.4, 140.5, 141.4, 142.9, 145.7,
151.7 (d, JC-F ) 8.6 Hz), 153.7, 160.5 (d, JC-F ) 240.5 Hz), 160.7
(d, JC-F ) 241.4 Hz). MS (ESI) m/z (%): 1085 [M - Cl]+, 525
[1/2M - Cl]+. HRMS (ESI): calcd for C60H42F4ClPd2 [M - Cl]+
1085.0981, found 1085.0975.
Dimeric Allylpalladium(II) Complex 2e (trans-anti-2e and
cis-anti-2e). Yellow solid. Mp: 212.5-216.7 °C. IR (CH2Cl2): ν
3071, 3010, 2915, 2843, 2368, 2300, 1600, 1585, 1489, 1443, 1377,
1266, 1180, 1165, 1095, 1072, 1029, 1010, 999, 929, 916, 904,
829, 765, 760, 746, 700 cm-1. 1H NMR (300 MHz, CDCl3, TMS):
δ 1.85-1.99 (3H, m, CH3), 5.16-5.19 (1H, m, CH2), 5.45-5.48
(1H, m, CH2), 6.03 (1H, s, CH), 7.00-7.44 (14H, m, ArH). 13C
NMR (75 MHz, CDCl3): δ 20.8, 21.0, 99.8, 100.0, 117.3, 122.1,
127.0, 127.4, 127.7, 128.0, 128.7, 129.3, 130.4, 132.0, 134.6, 136.7,
Dimeric Allylpalladium(II) Complex 3e (trans-syn-3e and
cis-syn-3e). Yellow solid. Mp: 170.5-174.5 °C. IR (CH2Cl2): ν
3024, 2959, 2921, 2857, 1606, 1490, 1444, 1331, 1185, 1073, 820,
766, 729, 696 cm-1 1H NMR (300 MHz, CDCl3, TMS): δ
.
1.63-1.69 (3H, m, CH3), 2.21-2.48 (6H, m, 2CH3), 3.46-3.67

1574 Organometallics, Vol. 28, No. 5, 2009
Gu et al.
(1H, m), 6.78-7.47 (17H, m, ArH), 7.57-7.64 (1H, m). 13C NMR
(75 MHz, CDCl3): δ 19.0, 19.2, 21.4, 21.9, 44.2, 44.8, 104.9, 106.1,
124.3, 124.7, 124.9, 127.2, 127.38, 127.45, 128.2, 128.4, 129.1,
130.3, 130.5, 137.3, 137.8, 137.9, 139.8, 140.1, 148.2, 154.2. MS
(ESI) m/z (%): 1069 [M - Cl]+, 517 [1/2M - Cl]+. Anal. Calcd
for C64H54Cl2Pd2: C, 69.45; H, 4.92. Found: C, 69.07; H, 4.77.
Dimeric Allylpalladium(II) Complex 3f (trans-syn-3f and
cis-syn-3f). Yellow solid. Mp: 157.7-160.6 °C. IR (CH2Cl2): ν
2959, 2924, 2844, 1605, 1513, 1489, 1443, 1337, 1276, 1256, 1178,
2.33 (3H, s, CH3), 2.95 (1H, q, J ) 7.2 Hz), 6.71 (1H, d, J ) 1.2
Hz), 6.97-7.02 (2H, m, ArH), 7.15-7.36 (15H, m, ArH). 13C NMR
(75 MHz, CDCl3): δ 17.6, 21.3, 21.5, 43.5, 119.9, 123.4, 123.7,
127.0, 127.2, 127.6, 127.8, 128.0, 128.1, 129.0, 129.2, 129.6, 130.0,
131.2, 132.2, 135.2, 137.2, 140.9, 142.80, 142.82, 143.4, 145.4,
149.5. MS (EI) m/z (%): 412 (100) [M+], 305 (35). HRMS (EI):
calcd for C32H28 (M+) 412.2191, found 412.2198.
2-(2,2-Diphenylvinyl)-6-methoxy-3-(4-methoxyphenyl)-1-methyl-
1H-indene (4f). Green solid. Mp: 181.2-181.3 °C. IR (CH2Cl2):
ν 3050, 3025, 2927, 2858, 1605, 1502, 1450, 1250, 1171, 1034,
835, 765 cm-1. 1H NMR (300 MHz, CDCl3, TMS): δ 1.02 (3H, d,
J ) 7.2 Hz, CH3), 3.02 (1H, q, J ) 7.2 Hz), 3.79 (3H, s, OCH3),
3.85 (3H, s, OCH3), 6.76-6.80 (3H, m, ArH), 6.96-6.99 (2H, m,
ArH), 7.23-7.26 (6H, m, ArH), 7.34-7.37 (5H, m, ArH),
7.44-7.48 (2H, m, ArH). 13C NMR (75 MHz, CDCl3): δ 17.7,
43.6, 55.2, 55.5, 109.2, 111.8, 113.8, 120.6, 123.4, 127.1, 127.50,
127.53, 127.7, 128.0, 128.1, 130.9, 131.2, 136.6, 141.0, 142.1,
142.3, 143.5, 144.0, 151.2, 158.5, 159.0. MS (EI) m/z (%): 444
(100) [M+]. Anal. Calcd for C32H28O2: C, 86.45; H, 6.35. Found:
C, 86.54; H, 6.28.
1
1031, 831, 764, 697 cm-1. H NMR (300 MHz, CDCl3, TMS): δ
1.604-1.71 (3H, m, CH3), 3.46-3.63 (1H, m), 3.80-3.91 (6H,
m, 2OCH3), 6.64-7.41 (17H, m, Ar), 7.56-7.67 (1H, m). 13C NMR
(75 MHz, CDCl3): δ 19.1, 19.2, 44.3, 44.7, 55.2, 55.5, 105.1, 109.7,
110.3, 113.3, 113.9, 125.5, 127.1, 127.3, 128.4, 129.6, 130.3, 130.5,
135.4, 138.0, 139.7, 140.2, 150.1, 154.0, 159.1, 159.9. MS (ESI)
m/z (%): 549 [1/2M - Cl]+. Anal. Calcd for C64H54Cl2O4Pd2+1/
3CH2Cl2: C, 63.28; H, 4.54. Found: C, 63.43; H, 4.23.
2-(2,2-Di-p-tolylvinyl)-1-methyl-3-phenyl-1H-indene (4c). Col-
orless liquid. IR (CH2Cl2): ν 3056, 3022, 2962, 2922, 2867, 1602,
1509, 1443, 1265, 1020, 818, 777 cm-1 1H NMR (300 MHz,
.
CDCl3, TMS): δ 0.96 (3H, d, J ) 7.5 Hz, CH3), 2.25 (3H, s, CH3),
2.33 (3H, s, CH3), 3.05 (1H, q, J ) 7.5 Hz), 6.66 (1H, m),
6.97-7.17 (11H, m, ArH), 7.25-7.29 (m, 2H, ArH), 7.33-7.38
(m, 2H, ArH), 7.44-7.47 (2H, m, ArH). 13C NMR (75 MHz,
CDCl3): δ 17.5, 21.1, 21.4, 43.8, 120.0, 122.0, 122.7, 125.2, 126.2,
127.4, 127.8, 128.3, 128.7, 128.8, 129.7, 131.0, 135.2, 137.2, 137.3,
137.9, 140.8, 142.2, 143.6, 143.7, 147.1, 149.2. MS (EI) m/z (%):
412 (100) [M+]. HRMS (EI): calcd for C32H28 (M+) 412.2191, found
412.2190.
Acknowledgment. Financial support from the Shanghai
MunicipalCommitteeofScienceandTechnology(06XD14005
and 08dj1400100-2), National Basic Research Program of
China (973-2009CB825300), and the National Natural Sci-
ence Foundation of China (20872162, 20672127, 20732008,
and 20702013) is greatly acknowledged.
2-(2,2-Diphenylvinyl)-1,6-dimethyl-3-p-tolyl-1H-indene (4e).
Colorless liquid. IR (CH2Cl2): ν 3061, 2963, 2927, 2859, 1600,
1507, 1443, 1224, 1156, 1014, 834, 777 cm-1. 1H NMR (300 MHz,
CDCl3, TMS): δ 0.95 (3H, d, J ) 7.2 Hz, CH3), 2.28 (3H, s, CH3),
Supporting Information Available: This material is available
free of charge via the Internet at http://pubs.acs.org.
OM801117G