Strong Lewis acids of air-stable binuclear triphenylantimony(V) complexes and their catalytic application in C-C bond-forming reactions

Article abstract of DOI:10.1016/j.tet.2015.05.013

Two air-stable novel Lewis acids of triphenylantimony(V) pentafluorbezenesulfonates (2) and perfluorooctanesulfonates (3) were successfully synthesized and characterized. X-ray studies and thermo-gravimetric analysis found that these complexes showed high anti-hydrolyzability and thermal stability. The high catalytic activity and excellent recyclability of these complexes were achieved in the Michael addition reaction and the allylation reaction. On account of their stability, storability, as well as catalytic efficiency, these complexes should find a broad range of utility in organic synthesis.

Full text of DOI:10.1016/j.tet.2015.05.013

Tetrahedron 71 (2015) 4275e4281
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Strong Lewis acids of air-stable binuclear triphenylantimony(V)
complexes and their catalytic application in CeC bond-forming
reactions
*
*
*
Ningbo Li, Renhua Qiu , Xiaohong Zhang, Yun Chen, Shuang-Feng Yin , Xinhua Xu
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082,
China
a r t i c l e i n f o
a b s t r a c t
Article history:
Two air-stable novel Lewis acids of triphenylantimony(V) pentafluorbezenesulfonates (2) and per-
fluorooctanesulfonates (3) were successfully synthesized and characterized. X-ray studies and thermo-
gravimetric analysis found that these complexes showed high anti-hydrolyzability and thermal stabil-
ity. The high catalytic activity and excellent recyclability of these complexes were achieved in the
Michael addition reaction and the allylation reaction. On account of their stability, storability, as well as
catalytic efficiency, these complexes should find a broad range of utility in organic synthesis.
Ó 2015 Elsevier Ltd. All rights reserved.
Received 29 March 2015
Received in revised form 2 May 2015
Accepted 5 May 2015
Available online 9 May 2015
Keywords:
Organoantimony complexes
Pentafluorbezenesulfonate
Perfluorooctanesulfonate
CeC bond-forming
1. Introduction
instance, the m-oxo-bridged binuclear triphenylantimony dihalide
was easily synthesized from 1 in moisture solution, which pos-
sessing an appropriate stability,7 but its low Lewis acidity limited its
further application in catalysis. Recently, Otera et al.8 and us9 found
the use of perfluoroalkyl(phenyl)sulfonate groups as effective
counter anions could overcome the hydrolytic instability of the
organometallic species and enhance the Lewis acidity.10 This find-
ing has led us to postulate that perfluoroalkyl(phenyl)sulfonate
groups serve to overcome the hydrolytic instability of the organo-
metallic species in a general sense. With this in mind, we herein
Organoantimony complexes have attracted much attention due
to their structure and potential application in organic synthesis,
pharmaceuticals and material science.1 Recently, most of re-
searchers mainly focused on the structural diversity of organo-
antimony(III) complexes since their stabilities.2 For example, aryl
ligands with the lone pair donor groups (sulfur, oxygen, or nitro-
gen), such as 2-[Me2NCH2]C6H4, 2,6-(Me2NCH2)2C6H3, 2,6-
(ROCH2)2C6H3 (R¼Me, t-Bu) and E(CH2C6H4)2 (E¼RN, O, S) help to
stabilize organoantimony(III) halides, cations and compounds
containing metal-metal bonds.3 But these complexes’ application
as Lewis acid catalysts for organic synthesis was rarely reported
since their low Lewis acidity.4 By oxidizing the Sb(III) complexes to
Sb(V) ones, e.g., Ph3Sb is oxidized to Ph3SbCl2 (1), higher catalytic
activity was successfully achieved.5 Hence, design and synthesis of
highly efficient organoantimony (V) complexes that free of hydro-
lysis and can be conveniently applied in various Lewis acid-
catalyzed reactions are the key issues.
successfully synthesized and characterized
m-oxo-bridged binu-
clear triphenylantimony(V) perfluorobezenesulfonates [(Ph3Sb)2O]
(OSO2C6F5)2ꢀ(2) and perfluorooctanesulfonates [(Ph3SbOH2)2O]þ
[OSO2C8F17
]
(3). Furthermore, their catalytic activities were
2
assessed by using Lewis acid-catalyzed CeC bond-forming re-
actions such as the Michael addition reaction and the allylation
reaction.
2. Results and discussion
The synthesis of the organoantimony (V) complexes was chiefly
concentrated in the tri- and tetraphenylantimony halides as start-
ing material and further synthesis of their derivatives.6 For
Complexes 2 and 3 were synthesized by treatment of 1 with
silver perfluorobezenesulfonate and perfluorooctanesulfonate
(AgX, for 2, X¼OSO2C6F5; for 3, X¼OSO2C8F17) (2 equiv) in CH3CN or
THF solution, respectively (Scheme 1).
The crystal structures of 2 and 3 in the solid state were con-
firmed by X-ray analysis. An ORTEP representation of 2 and 3 and
* Corresponding authors. Fax: þ86 731 88821546; e-mail addresses: renhuaqiu@
hnu.edu.cn (R. Qiu), sf_yin@hnu.edu.cn (S.-F. Yin), xhx1581@hnu.edu.cn (X. Xu).
http://dx.doi.org/10.1016/j.tet.2015.05.013
0040-4020/Ó 2015 Elsevier Ltd. All rights reserved.

4276
N. Li et al. / Tetrahedron 71 (2015) 4275e4281
are 2.353(4), 2.233(3), respectively, which implies the Sb2eO4 and
Sb1eO1 bonds connected with anions are more easily to dissociate
when in catalytic solution than that of Sb1eO7 and Sb2eO7 bonds
for substrate activating. The Sb1eO7eSb2 angle of 2 is 135.8(16).
The O1eSb1eO7 and O4eSb2eO7 angle of 2 are 175.9(2), 173.4(2)
degree. The SbeC(phenyl) distance varies from 2.042(11) to
Scheme 1. Synthesis of complexes 2 and 3.
ꢀ
2.095(4) A.
The crystal structure of the complex 3 is depicted in Fig. 2. In
contrast to covalent complex 2, complex 3 is ionic complex in solid
state. It shows that each pentavalent antimony center adopts a five-
coordinate trigonal bipyramidal geometry surrounded by three
equatorial phenyl C atoms, an axial O atom from coordinate water
molecule and an axial bridging oxygen, with the bridging angle of
149.3(3)ꢁ for Sb1eO1eSb2. The SbeC(phenyl) distance varies from
selected bonds and angles were shown in Figs. 1 and 2. The crystal
structure of the complex 2 shows it is covalent structure, which is
similar with the complex [(Ph3Sb)2O](OSO2CF3)2.11 The unit cells of
2 contain four asymmetric molecules with a bent Sb1eO7eSb2
bridge as a central. The atoms bound to the Sb1 and Sb2 atoms form
distorted trigonal bipyramids with three C(phenyl) atoms in the
equatorial plane and the bridging O7 and O1/O4 of the unidentate
bonded sulfonate ligand in apical positions. The Sb1eO7 and
Sb2eO7 bond distances of Sb1eO7eSb2 bridge are 1.953(9),
2.028(18), respectively, while the Sb1eO1 and Sb2eO4 distances
ꢀ
2.091(7) to 2.117(6) A, and the bridging SbeO distances of 1.950(4)
ꢀ
and 1.956(4) A indicate that after the complex 3 dissociates as
cationic ion, the distances of the two SbeO bonds are almost same,
which are consistent with reports for other trigonal bipyramidal
m-
oxo bridged binuclear triphenylantimony complexes.12
Generally, water molecule is non-essential and even undesired
since it may lead to decomposition of the catalyst. But its partici-
pation in the hydrogen bond significantly enhances the stability of
the supermolecular structure of 3. And the longer distances of
ꢀ
2.402(5) and 2.370(5) A of terminal linkages between H2O and Sb
may benefit the common fluxional behavior of pentacoordinate
molecular geometry, which provides easy access to an open co-
ordination site for substrate attacking in catalysis.13
As shown in Fig. 3a, each diantimony moiety connects its
neighbors through the OeH(water)/O(sulfonate) hydrogen
ꢀ
bond(H/O¼2.00, 1.98, 1.73 and 1.82 A; O/O¼2.742(9), 2.ꢁ719(9),
ꢀ
ꢀ
2.683(8) A, and 2.765(8) A; OeH/O¼132, 132, 172, and 166 ) with
the graph set R44(12), forming a one-dimensional infinite chain. By
this way, the C8F17SOꢀ3 anions are packed around the complex
cation and produce hydrophobic domains. Furthermore, CH/p and
ꢀ
ꢀ
p
/
p
p
interactions (H/
p
p
¼2.815 to 3.209 A; C/ ¼3.59 to 3.85 A;
p
¼128 to 153ꢁ) between phenyl groups
ꢀ
p/
¼3.686 A; CeH/
connect chains into two-dimensional bilayer structure (Fig. 3b).
Thus, the supermolecular nonbonded contacts and the character-
istics of hydrophobicity and electron-withdrawing ability of per-
fluooctanesulfate counter anion can greatly enhance the stability
Fig. 1. The crystal structure of the complex 2 and selected bonds (Aꢁ) and angles (deg):
The Sb1eO7 and Sb2eO7 distances are 1.953(9) and 2.028(18). The Sb1eO1 and
Sb2eO4 distances are 2.353(4), 2.233(3). The Sb1eO7eSb2 angle is 135.8(16) deg. The
O1eSb1eO7 and O4eSb2eO7 angles are 175.9(2), 173.4(2) deg. The Sb1eC(phenyl)
and Sb2eC(phenyl) distances are Sb1eC13, 2.081(17); Sb1eC19, 2.042(11); Sb1eC25,
2.109(6) and Sb2eC31, 2.095(4); Sb2eC37, 2.028(12), Sb2eC43, 2.085(8).
and catalytic activity of the complex cation [(Ph3SbOH2)2O]2þ 5
.
Fig. 3. (a) Perspective view of the coordination environment in complex 3, and the
one-dimensional infinite chain structure along the c axis linked by hydrogen bond
between coordination water and sulfonate; (b) H atoms except for water molecules
and the perfluorocarbon chain have been omitted for clarity. Nonbonded contacts of
Fig. 2. The crystal structure of the complex 3 and selected bonds (Aꢁ) and angles (deg):
The Sb1eO1 and Sb2eO1distances are 1.950(4) and 1.956(4). The Sb1eO1eSb2 angle
is 149.3(3) deg. The O1eSb1eO10 and O1eSb2eO11 angles are 171.62(19) and
177.15(19) deg. The Sb1eC(phenyl) and Sb2eC(phenyl) distances are Sb1eC1, 2.100(7);
Sb1eC7, 2.093(8); Sb1eC13, 2.104(6) and Sb2eC19, 2.091(7); Sb2eC25, 2.105(7);
Sb2eC31, 2.117(6). The Sb1eO10 and Sb2eO11 distances of Sb with water molecules
are 2.402(5), 2.370(5).
OH/O and CH/
p as well as p/p interactions are indicated by dashed lines.
It is notable that the solid samples remain as dry crystals or
powder after being kept in open air over three months, and exhibits
no sign of skeleton change by 1H NMR spectroscopy analysis (see-
ing SI). The thermal behaviors of 2 and 3 were investigated by

N. Li et al. / Tetrahedron 71 (2015) 4275e4281
4277
Table 2
TG-DSC under N2 atmosphere (Fig. S1). The thermal analysis curves
showed that decomposition took places in three distinct stages. The
first endothermic step below 100 ꢁC can be assigned to the removal
of two coordinate water molecules for complex 3. Complexes 2 and
3 were stable up to about 300 ꢁC. The weight loss of an exothermic
nature at 350 ꢁC is plausibly due to the oxidation of organic entities
(Fig. 4).
Product yields of the reactions of indole derivatives with enones/nitroalkenes cat-
alyzed by 2 and 3a
Fig. 4. TG-DSC curves of complexes 2 and 3. Operation conditions: N2, 5 ꢁC/min
heating rate.
Another notable feature is the unusual solubility of 2 and 3 in
Acetone, THF, CH3CN, EtOAc and MeOH (Table 1). One can see that 2
and 3 show higher solubility in common polar organic solvents.
Another quite surprising behaviour is that these complexes is in-
soluble in CH2Cl2, because CH2Cl2 is usually the best solvent for
similar binuclear triphenylantimony (V) bis(triflate) complexes.11
Consistently, they are not soluble in much less polar toluene and
nonpolar n-hexane. Furthermore, as it is apparently insoluble in
water, these complexes are hydrophobic, which could be attributed
to the fluoroalkyl(aryl) chain in the sulfonate ligand.
a
2 or 3, 0.05 mmol; indoles 4, 1.0 mmol;
, -unsaturated
carbonyl compounds 5 / nitroalkenes 7, 1.0 mmol; CH3CN,
1.0 mL; room temperature; 3-6 hours; isolated yields. No
b
catalyst, 12 h.
Table 1
The solubility of complex 2 and 3 in Organic Solvents at 25 ꢁCa
(6aei, 77e91%). Gratifyingly, in the presence of 5.0 mol % of 2,
trans-b-nitro-styrene also showed good reactivity in good to ex-
Solvent
Solubility (g/L) of 2
Solubility (g/L) of 3
Acetone
CH3CN
THF
EtOAc
MeOH
Et2O
CH2Cl2
n-Hexane
Toluene
943
478
432
398
1025
31
1071
626
641
537
1328
23
cellent yields (8aeg, 75e86%). Controlled experiments were per-
formed in the absence of 3, the reaction basically did not take place;
only 9% yield of the product (6a) was obtained.
Moreover, the complex 3 also showed high catalytic efficiency in
the allylation reaction (Table 3, 11aej, 85e96%). The aromatic al-
dehydes with electron-withdrawing groups (e.g., Cl, Br, and NO2)
(11deh, 92e96%) exhibited almost similar reactivity in the reaction
as that with electron-donating groups in the para-position of the
phenyl plane (e.g., methyl and methoxyl) (11bec, 91e92%). The
cinnamaldehyde with double bond was tolerated (11i, 89%). And
the catalytic system can be easily extended to alkyl aldehyde (11j,
85%). Without the catalyst, only 23% yield of the desired product
(11a) was obtained.
In addition, the activities of 1, (Ph3SbCl)2O, 2, and 3 together
with [(Ph3SbOH2)2O](OSO2CF3)2 were estimated by the Michael
addition reaction and allylation reaction (Table 4). High yields were
attained over complexes 2 and 3, while the other catalysts showed
much lower yields, plausibly duo to their lower Lewis acidity or
moisture-sensitive properties.
0
0
0
0
0
0
a
All samples are fresh prepared and recrystallized in vacuum at room tempera-
ture in a period of 2 h.
In addition, we employed the Hammett indicator method to
determine their acidities, and found that they show a relatively
strong acidity with the acid strength of 3.3<H0<4.8 (H0 being the
Hammett acidity function).14 These features facilitate their catalytic
performance in CeC bond forming reactions.
The Michael addition reaction and the allylation reaction have
been recently extensively used to assess the catalytic efficiency
since these reactions required high Lewis acidity catalyst.15 Hence,
we evaluated the catalytic activities of complexes 2 and 3 in the
Michael addition reaction of indoles to
compounds or trans- -nitrostyrene and the allylation reaction of
aldehydes with tetraallyltin.
As shown in Table 2, the complex 3 showed high catalytic effi-
ciency in Michael addition, good-to-excellent yields were obtained
To test the reusability of the catalyst and reproducibility of
catalytic performance, the complex 3 was subject to cycles of the
Michael addition reaction (4aþ5a / 6a) and the allylation reaction
(9aþ10a / 11a). The decline in product yield was minimal in a run
of 5 cycles, indicating that the catalyst is stable and suitable for
reuse (Table 5).
a, b-unsaturated carbonyl
b

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N. Li et al. / Tetrahedron 71 (2015) 4275e4281
Table 3
4. Experimental section
Preparation of homoallyl alcohols catalyzed by 3a
4.1. General
All chemicals were purchased from Aldrich. Co. Ltd and used as
received unless otherwise indicated. The NMR spectra were
recorded at 25 ꢁC on INOVA-400M (USA) calibrated with tetrame-
thylsilane (TMS) as an internal reference. Elemental analyses were
performed by VARIO EL III. TG-DSC analysis was performed on an
HCT-1 (HENVEN, Beijing, China) instrument. IR spectra were
recorded on NICOLET 6700 FTR spectrophotometer (Thermo Elec-
tron Corporation). X-ray single crystal diffraction analysis was
performed with SMART-APEX and RASA-7A by Shanghai Institute
Organic Chemistry, China Academy of Science. Catalyst acidity was
measured by Hammett indicator method.
4.1.1. Preparation of [(Ph3Sb)2O](OSO2C5F6)2 (2). To a solution of
Ph3SbCl2 (0.419 g, 0.99 mmol) in 10 mL CH3CN, a solution of AgO-
SO2C6F5 (0.724 g, 2 mmol) in 5 mL CH3CN was added. After the
mixture was stirred in the absence of light at room temperature for
2 h, it was filtrated and evaporated in the vacuum and the resulted
residue was diluted with 10 mL THF and followed by five drops of
dry hexane and then was maintained in the refrigerator for 24 h,
and the colorless crystals were obtained (0.94 g, 78%). Mp:
a
3, 0.05 mmol; tetraallyltin 9, 0.3 mmol; aldehydes 10, 1.0
mmol; CH3CN, 1.0 mL; room temperature; 1-3 hours; isolated
yields. b No catalyst, 12 h.
Table 4
Catalyst comparison in the Michael addition reaction and allylation reaction of
262e263 ꢁC, 1H NMR (400 MHz, [d6] acetone)
Ph), 7.62e7.69 (m, 9H, Ph), 8.14e8.17 (m, 4H, Ph). 19F NMR (376M,
[d6] acetone):
: ꢀ138.82 to ꢀ138.90 (m, 2F; ArF), 155.04 (s, 1F;
d: 7.46e7.50 (m, 2H,
PhCHO with tetraallyltina
d
ArF),ꢀ163.83 to ꢀ163.94 (m, 2F; ArF). IR(KBr): ¼3085, 3020, 1652,
n
1488, 1257, 1139, 1074, 987, 936, 783, 685, 650, 547 cmꢀ1. Anal.
Calcd for C48H30F10Sb2O7S2: C, 47.40; H, 2.49; found: C 47.38; H,
2.47.
Crystal data for 2: C96H62F20Sb4O15S4; Mr¼2450.70, Monoclinic,
ꢀ
ꢀ
space group P 21/c, a¼9.5078(10) A, b¼31.297 (3) A, c¼15.9879 (14)
3
ꢀ
ꢀ
A; V¼4488.4(7) A ; T¼296(2) K; Z¼2; Reflections collected/unique,
34601/8334, Rint¼0.0225, Final R indices [I>2 (I)] R1¼0.0325,
wR2¼0.0895; indices (all data), R1¼0.0380, wR2¼0.0938.
GOF¼1.073; CCDC No. 949212.
s
Entry
Catalyst
6ab
10ab
R
1
2
3
4
5
Ph3SbCl2
(Ph3SbCl)2O
[(Ph3Sb)2O] (OSO2C6F5)2
[(Ph3SbOH2)2O]þ [OSO2C8F17
[(Ph3SbOH2)2O](OSO2CF3)2
12
15
87
91
71
58
61
92
94
82
ꢀ
]
2
4.1.2. Preparation of [(Ph3SbOH2)2O](OSO2C8F17)2 (3). To a solution
of Ph3SbCl2 (0.419 g, 0.99 mmol) in 20 mL THF, a solution of
AgOSO2C8F17 (1.212 g, 2 mmol) in 10 mL THF was added. After the
mixture was stirred in dark at room temperature for 2.5 h, it was
filtered in air. The filtrate mixed with 40 mL hexane was re-
frigerated for 24 h, and the colorless crystals were obtained
a
Cat., 0.05 mmol; tetraallyltin 9, 0.3 mmol; benzaldehyde 10a, 1.0 mmol; CH3CN,
1.0 mL; room temperature; 1 h.
b
Isolated yield.
(1.27 g, 73%). Mp: 188e189 ꢁC, 1H NMR (400 MHz, [d6] acetone)
d:
Table 5
Yields of the Michael addition reaction (4aþ5a / 6a) and the allylation reaction
4.64 (s, 2H, H2O), 7.58e7.60 (m, 3H, Ph), 7.70e7.75 (m, 9H, Ph),
8.14e8.16 (m, 3H, Ph). 19F NMR (376M, [d6] acetone): d¼ꢀ76.05 to
ꢀ76.10 (m, 3F; eCF3), ꢀ109.52 to ꢀ109.60 (m, 2F; eCF2e), ꢀ115.59
(s, 2F; eCF2e), ꢀ116.63 to ꢀ116.92 (d, 6F; e(CF2)3e), ꢀ117.82 (s,
2F; eCF2e), ꢀ121.20 to ꢀ121.24 ppm (m, 2F; eCF2e); IR(KBr):
(9aþ10a / 11a) catalyzed by recovered catalyst 3a
Cycle Yield (%)b4aþ5a / 6a Cat (%)c Yield (%)b 9aþ10a / 11a Cat (%)c
1
2
3
4
5
91
92
91
91
92
92
93
91
92
93
94
95
94
96
94
95
96
94
96
95
n
¼3421, 2923, 2854, 1649, 1482, 1442, 1247, 1148, 1066, 1031, 996,
940, 778, 735, 687, 650, 620, 557, 517, 450 cmꢀ1. Elemental anal-
ysis calculate (%) for C52H34F34Sb2O9S2: C, 35.56; H, 1.95; found: C
35.58; H, 1.94.
a
3, 0.05 mmol; methyl vinyl ketone 4a, 1.0 mmol; indole 5a, 1 mmol; tetraallyltin
9, 0.3 mmol; benzaldehyde 10a, 1.0 mmol.
b
Crystal data for 3: C52H34F34Sb2O9S2; Mr¼1756.41, Triclinic,
Isolated yield of desired product.
Isolated yield of recovered catalyst.
c
ꢀ
ꢀ
space group P-1, a¼13.0383(12) A, b¼15.0200(12) A, c¼17.9200(16)
3
ꢀ
ꢀ
A; V¼3288.7(5) A ; T¼153(2) K; Z¼2; Reflections collected/unique,
19878/12870, Rint¼0.0305, Final R indices [I>2 (I)] R1¼0.0635,
3. Conclusions
s
wR2¼0.1735;
R
indices (all data), R1¼0.0941, wR2¼0.2022.
In summary, we have synthesized and characterized two binu-
clear triphenylantimony (V) complexes. These complexes are
strongly acidic and air-stable, and show highly catalytic efficiency
in the Michael addition reaction and the allylation reaction.
Moreover, these complexes possess good reusability. On account of
their stability, storability, as well as catalytic efficiency, these
complexes should find a broad range of utility in organic synthesis.
GOF¼1.082; CCDC No. 895178.
4.1.3. Typical procedure for solubility of complexes
2
and
3.10 Acetone (0.5 mL) was placed in a test tube; the complex of
[(Ph3Sb)2O](OSO2C5F6)2 (2) was added gradually at room temper-
ature. When the amount of added 2 exceeds 471.5 mg, insoluble 2
appeared. Based on this data, solubility of 2 was determined to be

N. Li et al. / Tetrahedron 71 (2015) 4275e4281
4279
471.5 g Lꢀ1. According to the same procedure, the solubility of
complex 3 was determined.
4.2.1.4. 3-(3-Indolyl)-cyclohexan-1-one (6d).16c Red solid, mp:
103e104 ꢁC; 1H NMR (400 MHz, CDCl3):
ppm 1.81e1.89 (m, 1H,
d
CH2), 1.91e2.07 (m, 2H, CH2),;2.25e2.29 (m, 1H, CH2), 2.36e2.46
(m, 2H, CH2), 2.60e2.67 (m, 1H, CH2), 2.79e2.83 (m, 1H), 3.42e3.49
(m, 1H, CH), 6.98 (d, J¼2.4 Hz, 1H, ArH), 7.12 (t, J¼7.8 Hz, 1H, ArH),
7.19 (t, J¼8.0 Hz, 1H, ArH),7.37 (d, J¼8.0 Hz, 1H, ArH), 7.62 (d,
J¼8.0 Hz, 1H, ArH), 8.02 (br s, 1H, NH); 13C NMR (100 MHz, CDCl3):
4.1.4. General procedure for the Michael addition reaction of indoles
to
a
,
b
-unsaturated carbonyl compounds and trans-
b
-Nitrostyrene. A
-Nitro-
mixture of
a
,
b
-unsaturated carbonyl compound/trans-b
styrene (1.0 mmol), indoles (1 mmol) and 2 or 3 (0.05 mmol) in
acetonitrile (1 mL) was stirred at room temperature for the ap-
propriate reaction time and monitored by TLC. Then the solvents of
the resulted mixture were removed by evaporation in vacuum,
CH2Cl2 (10 mLꢂ3) was added to the reaction mixture and the cat-
alyst was filtered for the next cycle of reaction. To the filtrate, after
evaporation of the solvent a Pinkish solid mixture was obtained.
The residue was performed by a short column chromatography
eluted with ethyl acetate/petroleum ether (80/20).
d
ppm 29.34, 31.90, 35.91, 41.56, 48.04, 111.27, 118.37, 119.00, 119.37,
119.72, 120.28, 126.12, 136.41, 211.79.
4.2.1.5. 4-(1H-Indol-3-yl)-4-phenyl-2-butanone
(6e).16d Red
ppm 2.07 (s, 3H,
solid, mp: 97e99 ꢁC; 1H NMR (400 MHz, CDCl3):
d
CH3), 3.15 (dd, J¼16.0 Hz, 8.0 Hz, 1H, CH2), 3.24 (dd, J¼16.0 Hz,
7.2 Hz, 1H, CH2), 4.83 (t, J¼7.6 Hz, 1H, CH), 6.96 (d, J¼2.4 Hz, 1H,
ArH), 7.03 (t, J¼7.6 Hz, 1H, ArH), 7.14 (t, J¼8.0 Hz, 2H, ArH), 7.24 (t,
J¼7.6 Hz, 2H, ArH), 7.28 (d, J¼8.8 Hz, 3H, ArH), 7.42 (d, J¼8.0 Hz, 1H,
4.1.5. General procedure for allylation of benzaldehyde with tetral-
lyltin catalyzed by complex 3. Complex 3 (0.05 mmol) was added to
a solution of benzaldehyde (1.0 mmol) in CH3CN (1 mL). Tetrallyltin
(0.3 mmol) was then added to the mixture at room temperature.
After the mixture was stirred at room temperature for three hours
and monitored by TLC, it was evaporated in vacuum at room tem-
perature. n-Hexane (10 mLꢂ3) was added to the residue; the cat-
alyst precipitated and was recovered by filtration for the next
reaction cycle. The combined n-hexane solution was concentrated,
and then MeOH and HCl (aq) was added and stirred for 15 min
NaHCO3 (aq) was added for neutralization. After the mixture was
subject to evaporation, the as-obtained solids were dissolved in
AcOEt and water. After extraction with AcOEt (three times), the
organic layer was washed with NaCl (aq) and dried over MgSO4.
After evaporation, GLC yield was measured. Alternatively, the res-
idue was subject to silica gel column chromatography (petroleum
ether/ethyl acetate¼8:1) and 6a was obtained as a colorless oil
(139 mg, isolated yield 94%).
ArH), 8.03 (br s, 1H, NH); 13C NMR (100 MHz, CDCl3):
d ppm 29.83,
30.46, 30.51, 38.49, 38.58, 50.48, 111.28, 118.95, 119.55, 121.46,
121.51, 122.31, 126.50, 126.65, 127.82, 128.61, 136.71,144.07, 207.83.
4.2.1.6. 3-(2-Methyl-3-indolyl)-cyclopentan-1-one (6f).17a Red
solid, mp: 140e142 ꢁC; 1H NMR (400 MHz, CDCl3):
d ppm
2.28e2.36 (m, 2H, CH2), 2.42 (s, 3H, CH3), 2.45e2.51 (m, 1H,
CH2),;2.53e2.60 (m, 2H, CH2), 2.75e2.82 (m, 1H, CH2), 3.58e3.65
(m, 1H, CH), 7.06 (t, J¼7.4 Hz, 1H, ArH), 7.13 (t, J¼7.4 Hz, 1H, ArH),
7.29 (t, J¼7.6 Hz, 1H, ArH), 7.54 (d, J¼7.6 Hz, 1H, ArH), 7.88 (br s, 1H,
NH); 13C NMR (100 MHz, CDCl3):
d ppm 12.28, 29.89, 34.66, 39.63,
44.45, 110.83, 111.98, 118.80, 119.32, 121.15, 126.87, 131.00, 135.64,
219.95.
4.2.1.7. 3-(5-Bromo-methyl-3-indolyl)-cyclopentan-1-one
(6g).16b Red oil, 1H NMR (400 MHz, CDCl3):
d ppm 2.04e2.11 (m,1H,
CH2), 2.27e2.44 (m, 3H, CH2),;2.48e2.53 (m, 1H, CH2), 2.74 (dd,
J¼18.0 Hz, 7.6 Hz, 1H, CH2), 3.61e3.71 (m, 1H, CH), 6.98 (d, J¼2.4 Hz,
1H, ArH), 7.24e7.31 (m, 2H, ArH), 7.74 (s, 1H, ArH), 8.21 (br s, 1H,
NH); 13C NMR (100 MHz, CDCl3):
d ppm 29.85, 33.49, 38.04, 45.11,
4.2. Characterization data
112.68, 112.77, 118.26, 121.12, 121.17, 121.60, 121.65, 125.14, 128.36,
135.26, 218.99.
4.2.1. 6ae6i, 8ae8g are known compounds, and 1H NMR, 13C NMR
spectral data are summarized as follows
4.2.1.8. 4-(2-Methyl-1H-3-indolyl)-2-nonanone (6h).16c Yellow
4.2.1.1. 4-(1H-3-Indolyl)-2-butanone (6a).16a Red solid, mp:
oil, 1H NMR (400 MHz, CDCl3):
d
ppm 0.80 (t, J¼6.4 Hz, 3H, CH3),
70e71 ꢁC; 1H NMR (400 MHz, CDCl3):
d
ppm 2.15 (s, 3H, CH3),
1.13e1.22 (m, 6H, CH2), 1.65e1.76 (m, 2H, CH2), 1.83e1.90 (m, 1H,
CH2), 1.93 (s, 3H, CH3), 2.36 (s, 3H, CH3), 2.79 (dd, J¼16.0 Hz, 6.0 Hz,
1H, CH2), 3.04 (dd, J¼15.6 Hz, 8.4 Hz, 1H, CH), 3.33e3.38 (m, 1H,
CH2), 7.02e7.10 (m, 2H, ArH), 7.23 (d, J¼7.6 Hz, 1H, ArH), 7.58 (d,
J¼8.0 Hz, 1H, ArH), 7.77 (br s, 1H, NH); 13C NMR (100 MHz, CDCl3):
2.84e2.87 (m, 2H, CH2), 3.04e3.07 (m, 2H, CH3), 6.99 (d, J¼2.4 Hz,
1H, ArH), 7.11 (t, J¼8.0 Hz, 1H, ArH), 7.20 (t, J¼7.6 Hz, 1H, ArH), 7.36
(d, J¼8.0 Hz,1H, ArH), 7.59 (d, J¼7.6 Hz,1H, ArH), 7.96 (br s,1H, NH);
13C NMR (100 MHz, CDCl3):
d ppm 19.31, 29.86, 44.06, 111.11, 115.20,
118.64, 119.28, 121.41, 122.04, 127.14, 136.27, 208.75.
d ppm 12.03, 14.01, 25.55, 27.60, 30.74, 31.72, 32.67, 35.08, 49.28,
111.40, 113.29, 118.77, 118.93, 120.53, 127.06, 131.40, 135.56, 209.04.
4.2.1.2. 4-(1H-3-Indolyl)-2-nonanone (6b).16b Yellow oil, 1H
NMR (400 MHz, CDCl3):
d
ppm 0.82 (t, J¼6.6 Hz, 3H, CH3), 1.16e1.27
4.2.1.9. 4-(1-Methyl-1H-3-indolyl)-2-nonanone (6i).17b Yellow
(m, 6H, CH2), 1.70e1.79 (m, 2H, CH2), 2.02 (s, 3H, CH3), 2.81 (dd,
J¼16.0 Hz, 6.8 Hz, 1H, CH2), 2.88 (dd, J¼16.0 Hz, 7.6 Hz, 1H, CH2),
3.44e3.48 (m, 1H, CH), 6.97 (d, J¼2.4 Hz, 1H, ArH), 7.10 (t, J¼7.4 Hz,
1H, ArH), 7.18 (d, J¼7.8 Hz, 1H, ArH), 7.35 (d, J¼7.8 Hz, 1H, ArH), 7.65
(d, J¼8.0 Hz, 1H, ArH), 7.99 (br s, 1H, NH); 13C NMR (100 MHz,
oil, 1H NMR (400 MHz, CDCl3):
d
ppm 0.82 (t, J¼6.4 Hz, 3H, CH3),
1.22e1.26 (m, 6H, CH2), 1.65e1.78 (m, 2H, CH2), 2.01 (s, 3H, CH3),
2.76 (dd, J¼16.0 Hz, 7.2 Hz, 1H, CH2), 2.83 (dd, J¼16.4 Hz, 7.6 Hz, 1H,
CH), 3.42e3.49 (m, 1H, CH2), 3.71 (s, 3H, CH3), 6.81 (s, 1H, ArH), 7.07
(t, J¼8.0 Hz, 1H, ArH), 7.22 (t, J¼8.0 Hz, 1H, ArH), 7.26 (t, J¼8.4 Hz,
1H, ArH), 7.63 (t, J¼8.0 Hz, 1H, ArH); 13C NMR (100 MHz, CDCl3):
CDCl3):
d ppm 14.20, 22.71, 27.42, 29.85, 30.59, 32.03, 35.90, 50.36,
109.76, 111.22, 119.14, 119.29, 121.18, 121.87, 126.51, 136.50, 209.08.
d ppm 14.02, 25.51, 27.26, 30.36, 31.79, 32.52, 32.72, 35.91, 50.33,
109.21, 117.43, 118.49, 119.29, 121.33, 125.91, 126.89, 137.10, 208.79.
4.2.1.3. 3-(3-Indolyl)-cyclopentan-1-one (6c).16b Yellow oil, 1H
NMR (400 MHz, CDCl3):
d
ppm 2.10e2.19 (m, 1H, CH2), 2.29e2.46
4.2.1.10. 3-(2-Nitro-1-phenylethyl)-1H-indole (8a).17c Yellow oil;
(m, 3H, CH2),;2.51e2.55 (m, 1H, CH2), 2.75 (dd, J¼18.4 Hz, 7.6 Hz,
1H, CH2), 3.69e3.77 (m, 1H, CH), 6.98 (d, J¼1.6 Hz, 1H, ArH), 7.15 (t,
J¼7.8 Hz, 1H, ArH), 7.23 (t, J¼8.0 Hz, 1H, ArH), 7.38 (d, J¼8.4 Hz, 1H,
ArH), 7.64 (d, J¼8.0 Hz, 1H, ArH), 8.10 (br s, 1H, NH); 13C NMR
1H NMR (400 MHz, CDCl3):
d
ppm 4.94 (dd, J¼12.4 Hz, 8.4 Hz, 1H,
CH2), 5.07 (dd, J¼12.4 Hz, 8.4 Hz, 1H, CH2), 5.20 (t, J¼8 Hz, 1H, CH),
7.03 (d, J¼2.8 Hz, 1H, ArH), 7.07 (t, J¼7.6 Hz, 1H, ArH), 7.18e7.38 (m,
7H, ArH), 7.44 (d, J¼7.6 Hz, 1H, ArH),8.11 (br s, 1H, NH); 13C NMR
(100 MHz, CDCl3):
d
ppm 29.90, 33.53, 38.16, 45.20, 112.71, 112.90,
(100 MHz, CDCl3): d ppm 41.50, 79.48, 111.33, 118.89, 119.92, 121.55,
118.24, 121.27, 121.69, 125.18, 128.41, 135.32, 219.34.
122.67, 127.53, 127.72, 128.88, 136.43, 139.11.

4280
N. Li et al. / Tetrahedron 71 (2015) 4275e4281
4.2.1.11. 5-Fluoro-3-(2-nitro-1-phenylethyl)-1H-indole
(8b)S12. Red oil; 1H NMR (400 MHz, CDCl3):
ppm 4.92 (dd,
5.12e5.15 (m, 2H, 2 vinyls), 5.76e5.85 (m, 1H, vinyl), 7.15 (d,
d
J¼8.0 Hz, 2H, Ar), 7.24 (d, J¼7.8 Hz, 2H, Ar); 13C NMR (100 MHz,
J¼12.4 Hz, 8.4 Hz, 1H, CH2), 5.04 (dd, J¼12.4 Hz, 8.4 Hz, 1H, CH2),
CDCl3): d ppm 21.15, 43.81, 73.18, 118.36, 125.78, 129.13, 134.61,
137.26, 140.86.
5.15 (t, J¼7.6 Hz, 1H, CH), 6.82 (t, J¼9.0 Hz, 1H, ArH), 7.30 (d,
J¼9.2 Hz, 2H, ArH), 7.25e7.35 (m, 6H, ArH), 8.12 (br s, 1H, NH); 13
C
NMR (100 MHz, CDCl3):
d
ppm 41.54, 79.60, 97.63, 97.87, 108.78,
4.2.2.3. 1-(p-Hydroxyphenyl)-3-buten-1-ol
(11c).18b Colorless
109.02, 114.66, 119.79, 121.77, 122.77, 127.77, 129.05, 136.47, 136.60,
159.09, 161.47.
oil; 1H NMR (400 MHz, CDCl3):
d
ppm 2.11 (d, J¼4.0 Hz, 1H, OH),
2.25e2.42 (m, 2H, CH2), 4.67 (t, J¼6.6 Hz, 1H, CH), 4.90e4.98 (m,
2H, 2 vinyls), 5.59e5.68 (m, 1H, vinyl), 6.75e7.23 (m, 4H, ArH); 13
C
4.2.1.12. 5-Bromo-3-(2-nitro-1-phenylethyl)-1H-indole
NMR (100 MHz, CDCl3):
127.36, 128.77, 136.94.
d ppm 44.74, 73.10, 115.11, 115.33, 116.03,
(8c).17d Red solid, 1H NMR (400 MHz, CDCl3):
d ppm 4.91 (dd,
J¼12.4 Hz, 8.4 Hz, 1H, CH2), 5.02 (dd, J¼12.4 Hz, 8.4 Hz, 1H, CH2),
5.12 (t, J¼8.2 Hz, 1H, CH), 7.06 (d, J¼2.4 Hz, 1H, ArH), 7.20e7.35 (m,
7H, ArH), 7.54 (s, 1H), 8.17 (br s, 1H, NH); 13C NMR (100 MHz,
4.2.2.4. 1-(p-Methoxyphenyl)-3-buten-1-ol
oil; 1H NMR (400 MHz, CDCl3):
(11d).18a Colorless
ppm 2.12 (d, J¼4.0 Hz, 1H, OH),
d
CDCl3):
d
ppm 41.27, 79.36, 112.81, 113.22, 114.02, 121.45, 122.69,
2.48 (t, J¼7.4 Hz, CH2, 2H), 3.79 (s, 3H, CH3), 4.67 (t, J¼6.6 Hz, 1H,
CH), 5.10e5.16 (m, 2H, 2 vinyls), 5.75e5.82 (m, 1H, vinyl), 6.87 (d,
J¼8.8 Hz, 2H, ArH), 7.26 (d, J¼8.8 Hz, 2H, ArH); 13C NMR (100 MHz,
125.64, 127.63, 127.75, 127.83, 129.02, 135.05, 138.65.
4.2.1.13. 2-Methyl-3-(2-nitro-1-phenylethyl)-1H-indole
CDCl3): d ppm 43.77, 55.29, 72.99, 113.78, 118.25, 127.11, 134.66,
(8d):.17c Yellow oil, 1H NMR (400 MHz, CDCl3):
d
ppm 2.29 (s, 3H,
136.08, 159.01.
CH3), 5.04 (dd, J¼12.4 Hz, 8.4 Hz, 1H, CH2), 5.10 (dd, J¼12.4 Hz,
8.4 Hz,1H, CH2), 5.16 (t, J¼8.0 Hz,1H, CH), 6.95 (t, J¼7.4 Hz,1H, ArH),
7.03 (t, J¼7.6 Hz, 1H, ArH), 7.22e7.26 (m, 6H, ArH), 7.29 (d, J¼8.0 Hz,
4.2.2.5. 1-(o-Fluorophenyl)-3-buten-1-ol (11e).18c Colorless oil;
1H NMR (400 MHz, CDCl3):
d
ppm 2.11 (d, J¼3.6 Hz, 1H, OH),
1H, ArH), 7.79 (br s, 1H, NH); 13C NMR (100 MHz, CDCl3):
d
ppm
2.45e2.63 (m, 2H, CH2), 4.22 (t, J¼6.0 Hz, 1H, CH), 5.14e5.18 (m, 2H,
2 vinyls), 5.73e5.81 (m, 1H, vinyl), 7.03 (t, J¼9.4 Hz, 1H, ArH), 7.16 (t,
J¼7.0 Hz, 1H, ArH); 7.22e7.28 (m, 1H, ArH), 7.48 (t, J¼7.8 Hz, 1H,
11.91, 40.37, 78.55, 108.72, 110.64, 118.51, 119.66, 121.25, 126.75,
127.00, 127.23, 128.70, 132.80, 135.32, 139.42.
ArH); 13C NMR (100 MHz, CDCl3):
d ppm 42.61, 67.22, 115.15, 115.20,
4.2.1.14. 5-Methyl-3-(2-nitro-1-phenylethyl)-1H-indole
118.81, 124.24, 127.22, 128.82, 128.90, 132.42, 134.07.
(8e):.17d White solid, mp: 127e128 ꢁC, 1H NMR (400 MHz, CDCl3):
d
ppm 2.40 (s, 3H, CH3), 4.91 (dd, J¼12.8 Hz, 8.4 Hz, 1H, CH2), 5.02
4.2.2.6. 1-(p-Chlorophenyl)-3-buten-1-ol (11f).18a Colorless oil;
(dd, J¼12.4 Hz, 8.4 Hz, 1H, CH2), 5.15 (t, J¼8.0 Hz, 1H, CH), 6.92 (d,
J¼2.4 Hz, 1H, ArH), 7.01 (t, J¼8.0 Hz, 1H, ArH), 7.21e7.33 (m, 7H,
1H NMR (400 MHz, CDCl3):
d
ppm 2.13 (d, J¼3.2 Hz, 1H, OH),
2.41e2.50 (m, 2H, CH2), 4.71 (t, J¼6.4 Hz, 1H, CH), 5.14e5.20 (m, 2H,
ArH), 7.95 (br s, 1H, NH); 13C NMR (100 MHz, CDCl3):
d ppm 21.59,
2 vinyls), 5.72e5.81 (m, 1H, vinyl), 7.26e7.33 (m, 4H, ArH); 13C NMR
41.58, 79.58, 111.13, 113.91, 118.48, 121.85, 124.40, 126.38, 127.58,
127.81, 128.96, 129.34, 134.85, 139.29.
(100 MHz, CDCl3):
133.99, 142.20.
d ppm 43.90, 72.55,118.94,127.22,128.55,133.16,
4.2.1.15. 7-Methyl-3-(2-nitro-1-phenylethyl)-1H-indole
4.2.2.7. 1-(p-Bromophenyl)-3-buten-1-ol (11g).18b Colorless oil;
1H NMR (400 MHz, CDCl3):
(8f):.17d Yellow oil, 1H NMR (400 MHz, CDCl3):
d
ppm 2.46 (s, 3H,
d
ppm 2.16 (d, J¼3.2 Hz, 1H, OH),
CH3), 4.93 (dd, J¼12.4 Hz, 8.4 Hz, 1H, CH2), 5.06 (dd, J¼12.4 Hz,
8.4 Hz, 1H, CH2), 5.18 (t, J¼8.0 Hz, 1H, CH), 7.00 (d, J¼5.2 Hz, 2H,
ArH), 7.01 (d, J¼2.0 Hz, 1H, ArH), 7.24e7.32 (m, 5H, ArH), 8.02 (br s,
2.40e2.48 (m, 2H, CH2), 4.70 (t, J¼6.4 Hz, 1H, CH), 5.14e5.17 (m, 2H,
2 vinyls), 5.72e5.78 (m, 1H, vinyl), 7.22 (d, J¼8.8 Hz, 2H, ArH), 7.46
(d, J¼8.4 Hz, 2H, ArH); 13C NMR (100 MHz, CDCl3):
d ppm 43.85,
1H, NH), 13C NMR (100 MHz, CDCl3):
d
ppm 16.50, 41.61, 79.48,
72.58, 118.96, 121.28, 127.58, 131.50, 133.96, 142.81.
114.85, 116.60, 120.15, 120.57, 121.26, 123.17, 125.59, 127.49, 127.71,
128.86, 136.04, 139.17.
4.2.2.8. 1-(m-Nitrophenyl)-3-buten-1-ol (11h).18d Colorless oil;
1H NMR (400 MHz, CDCl3):
d
ppm 2.33 (d, J¼3.6 Hz, 1H, OH),
4.2.1.16. 1-Methyl-3-(2-nitro-1-phenylethyl)-1H-indole
2.44e2.57 (m, 2H, CH2), 4.86 (t, J¼6.0 Hz, 1H, CH), 5.17e5.22 (m,
2H, 2 vinyls), 5.75e5.84 (m, 1H, vinyl), 7.53 (t, J¼8.0 Hz, 1H, ArH),
7.70 (d, J¼7.6 Hz, 1H, ArH); 8.14 (d, J¼7.4 Hz, 1H, ArH); 8.24 (t,
(8g).17d Red oil, 1H NMR (400 MHz, CDCl3):
d ppm 3.69 (s, 3H, CH3),
4.90 (dd, J¼12.4 Hz, 8.4 Hz, 1H, CH2), 5.02 (dd, J¼12.4 Hz, 8.4 Hz,
1H, CH2), 5.12 (t, J¼8.0 Hz, 1H, CH), 7.00e7.28 (m, 9H, ArH); 13C
J¼3.6 Hz, 1H, ArH); 13C NMR (100 MHz, CDCl3):
d ppm 43.57,
NMR (100 MHz, CDCl3):
d
ppm 32.94, 41.61, 79.64, 109.60, 112.88,
72.06, 119.74, 120.88, 122.49, 129.37, 131.99, 133.28, 145.93,
148.32.
119.06, 119.54, 122.31, 126.46, 127.60, 127.82, 129.00, 137.37,
139.44.
4.2.2.9. 1-Phenyl-1,5-hexadien-3-ol (11i).18a Colorless oil; 1H
4.2.2. 11ae11j are known compounds, and the 1H NMR, 13C NMR
spectral data are summarized as follows
NMR (400 MHz, CDCl3):
d
ppm 1.88 (d, J¼4.0 Hz,1H, OH), 2.35e2.44
(m, 2H, CH2), 4.36 (t, J¼6.0 Hz, 1H, CH), 5.15e5.18 (m, 2H, 2 vinyls),
5.80e5.89 (m, 1H, vinyl), 6.24 (dd, J¼16.0 Hz, 6.4 Hz, 1H, vinyl), 6.59
(d, J¼16.0 Hz, 1H, ArH), 7.24 (t, J¼7.2 Hz, 1H, ArH); 7.31 (t, J¼7.6 Hz,
2H, ArH); 8.24 (d, J¼7.2 Hz, 2H, ArH); 13C NMR (100 MHz, CDCl3):
4.2.2.1. 1-Phenyl-3-buten-1-ol(11a).18a Colorless oil; 1H NMR
(400 MHz, CDCl3):
d ppm 2.11 (br, 1H, OH), 2.48e2.54 (m, 2H,
CH2), 4.74 (t, J¼6.4 Hz, 1H, CH), 5.13e5.16 (m, 2H, two vinyls),
5.77e5.83 (m, 1H, vinyl), 7.28e7.37 (m, 5H, Ar); 13C NMR
d
ppm 42.03, 71.73, 118.59, 126.51, 127.70, 128.61, 130.38, 131.55,
134.06, 136.65.
(100 MHz, CDCl3):
d ppm 43.87, 73.31, 118.50, 125.84, 127.60,
128.45, 134.51, 143.88.
4.2.2.10. Heptyl-1-en-4-ol (11j).18e Colorless oil; 1H NMR
4.2.2.2. 1-(p-Methylphenyl)-3-buten-1-ol (11b).18a Colorless oil;
1H NMR (400 MHz, CDCl3):
ppm 1.98 (d, J¼3.2 Hz, 1H, OH), 2.35 (s,
3H, CH3), 2.48e2.52 (m, 2H, CH2), 4.71 (t, J¼6.4 Hz, 1H, CH),
(400 MHz, CDCl3)
2H, CH2), 1.45e1.54 (m, 2H, CH2), 1.96 (s, 1H, OH), 2.18e2.36 (m, 2H,
CH2), 3.80e3.88 (m, 1H, CH), 5.11e5.19 (m, 2H, vinyl), 5.76e5.85 (m,
d
ppm 0.97 (t, J¼7.4 Hz, 1H, CH3), 1.30e1.38 (m,
d

N. Li et al. / Tetrahedron 71 (2015) 4275e4281
5. Pan, B. F.; Gabbaï, F. P. J. Am. Chem. Soc. 2014, 136, 9564.
4281
1H, vinyl); 13C NMR (100 MHz, CDCl3):
47.05, 72.70, 117.81, 135.28.
d
ppm 14.16, 19.06, 38.77,
ꢂ
ꢀꢂ ꢂ
ꢁ
6. (a) Simon, P.; de Proft, F.; Jambor, R.; Ruzicka, A.; Dostal, L. Angew. Chem., Int. Ed.
2010, 49, 5468; (b) Yin, H. D.; Wu, Q. K.; Hong, M.; Li, W. K. Z. Anorg. Allg. Chem.
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ganomet. Chem. 2009, 694, 3708; (d) Yin, H. D.; Wen, L. Y.; Cui, J. C.; Li, W. K.
Polyhedron 2009, 28, 2919.
Acknowledgements
7. Meinema, H. A.; Rivarola, M. E.; Noltes, J. G. J. Organomet. Chem. 1969, 17, 71.
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R. H.; Chen, J. Y.; Wang, X.; Yin, S. F. Adv. Synth. Catal. 2013, 355, 2430; (d) Li, N.
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The authors thank the NSFC (Nos. 21273068, 21373003,
J1210040), the NSF of Hunan Province (2014JJ7027), and the Fun-
damental Research Funds for the Central Universities, Hunan Uni-
versity, for financial support. The authors thank the Prof. A. Orita
(Okayama University of Science), Prof. N. Kambe (Osaka University)
and Profs. C.T. Au and W.-Y. Wong (HKBU) for helpful discussion.
Supplementary data
10. An, D. L.; Peng, Z. H.; Orita, A.; Kurita, A.; Man-e, S.; Ohkubo, K.; Li, X.; Fuku-
zumi, S.; Otera, J. Chem.dEur. J. 2006, 12, 1642.
€
11. Perut, H.; Ruther, R.; Huber, F. Acta Crystallogr. 1986, 42, 1154.
Supplementary data (The crystal data of complex 2 and 3, copies
of the 1H NMR and 13C NMR of all the products; additional in-
formation as needed can be seen in the Supplementary data.).
CCDC 949212 and 895178 contains the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge from the cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/ata_request/cif.) related to this article can be
found at http://dx.doi.org/10.1016/j.tet.2015.05.013.
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