Gold(III) (C^N) complex-catalyzed synthesis of propargylamines via a three-component coupling reaction of aldehydes, amines and alkynes

Article abstract of DOI:10.1016/j.jorganchem.2008.12.008

Propargylamines are synthesized in high yields via a gold(III) (C^N) complex-catalyzed three-component coupling reaction of aldehydes, amines and alkynes in water at 40 °C. Excellent diastereoselectivities (up to 99:1) have been achieved when chiral prolinol derivatives are employed as the amine component. Notably, the [Au(C^N)Cl₂] complex (N^CH = 2-phenylpyridine) could be repeatedly used for 10 reaction cycles, leading to an overall turnover number of 812.

Full text of DOI:10.1016/j.jorganchem.2008.12.008

Journal of Organometallic Chemistry 694 (2009) 583–591
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Gold(III) (C^N) complex-catalyzed synthesis of propargylamines via
a three-component coupling reaction of aldehydes, amines and alkynes
a,
Vanessa Kar-Yan Lo a,b, Karen Ka-Yan Kung b, Man-Kin Wong b, , Chi-Ming Che
*
*
a Department of Chemistry and Open Laboratory of Chemical Biology of the Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong,
Pokfulam Road, Hong Kong, China
b Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 8 October 2008
Received in revised form 1 December 2008
Accepted 1 December 2008
Available online 13 December 2008
Propargylamines are synthesized in high yields via a gold(III) (C^N) complex-catalyzed three-component
coupling reaction of aldehydes, amines and alkynes in water at 40 °C. Excellent diastereoselectivities (up
to 99:1) have been achieved when chiral prolinol derivatives are employed as the amine component.
Notably, the [Au(C^N)Cl2] complex (N^CH = 2-phenylpyridine) could be repeatedly used for 10 reaction
cycles, leading to an overall turnover number of 812.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords:
Gold(III) catalyst
Three-component coupling reaction
Propargylamines
Prolinol derivatives
1. Introduction
lysts for organic transformations. Furthermore, by changing the
substituents on the ligand, the electronic and steric properties,
Propargylamines are versatile building blocks for organic syn-
thesis. They are generally used as precursors for the synthesis of
N-containing heterocyclic compounds such as pyrrolidines, oxaz-
oles and pyrroles [1], and as key intermediates for natural product
synthesis [2]. Conventionally, propargylamines are synthesized by
nucleophilic attack of lithium acetylides or Grignard reagents to
imines or their derivatives [3,4]. However, these methods require
the use of stoichiometric amount of organometallic reagents and
strictly controlled reaction conditions. In addition, protection of
sensitive functional groups, such as aldehyde, is necessary. Thus,
there has been an ongoing interest to develop transition metal cat-
alysts for C–H bond activation of terminal alkynes under mild reac-
tion conditions [5]. Complexes of iridium [6], indium [7], zinc [8],
copper [1c,9] and silver [10] have been developed as catalysts for
the activation of acetylides for subsequent nucleophilic attack to
imines or iminium ions to give propargylamines.
and thus the catalytic activity, of the gold(III) complexes can be
fine-tuned [14].
As part of our ongoing program to develop gold-catalyzed or-
ganic transformation reaction [15], we have employed gold(III)
salen complexes as catalysts for the synthesis of chiral propargyl-
amines [15b]. For the search of more stable gold(III) catalysts,
gold(III) (C^N) complex [Au(C^N)Cl2] (N^CH = 2-phenylpyridine)
was found to be catalytically active towards this three-component
coupling reaction. Here we report the first use of a gold(III) (C^N)
complex [Au(C^N)Cl2] as a recyclable catalyst for the synthesis of
propargylamines via a three-component coupling reaction of alde-
hydes, amines and alkynes in water at 40 °C. By employing chiral
prolinol derivatives as the amine component, excellent diastere-
oselectivities (99:1) have been achieved. The [Au(C^N)Cl2] com-
plex could be repeatedly used for 10 consecutive cycles leading
to 812 product turnovers in total.
Recently, gold catalysis has emerged to be an active research
area in organic synthesis [11]. The AuBr3-catalyzed synthesis of
propargylamines via a three-component coupling reaction of alde-
hydes, amines and alkynes in water was firstly reported by Li’s
group [12,13]. To extend and broaden the practical applications
of gold catalysis, gold(III) complexes have been employed as cata-
2. Results and discussion
2.1. Synthesis of [Au(C^N)Cl2]
Gold(III) (C^N) complex [Au(C^N)Cl2] (N^CH = 2-phenylpyri-
dine) was synthesized according to a reported procedure [16]. In
brief, KAuCl4 and 2-phenylpyridine were stirred in 1:1 CH3CN/
H2O at room temperature for 30 min. [Au(HC^N)Cl3] complex
was isolated as a yellow precipitate, which was refluxed overnight
* Corresponding authors. Tel.: +852 3400 8701; fax: +852 2364 9932 (M.-K.
Wong), tel.: +852 2859 2154; fax: +852 2915 5176 (C.-M. Che).
E-mail addresses: bcmkwong@inet.polyu.edu.hk (M.-K. Wong), cmche@hku.hk
(C.-M. Che).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.12.008

584
V.Kar-Yan Lo et al. / Journal of Organometallic Chemistry 694 (2009) 583–591
Table 1
loading of [Au(C^N)Cl2] to 0.25 mol% gave 1a with complete benz-
aldehyde conversion in 24 h. Further reducing the catalyst loading
to 0.1 mol% led to 74% benzaldehyde conversion within 24 h and
97% conversion (70% yield) when the reaction time was extended
to 48 h, representing a turnover number of 970 within 48 h. The
reaction also worked well for aliphatic cyclohexylaldehyde (86%
yield; entry 2), pyrrolidine (76% yield; entry 3), and trimethylsilyl
(TMS) substituted alkyne (69% yield; entry 4).
Effects of different gold(III) catalysts on the synthesis of propargylamines.a
Catalyst (1 mol%)
O
H
N
H2O, N2, 40 o
24 h
C
+
+
N
H
Ph
H
Ph
Ph
1a
Ph
Entry
Catalyst
Conversionb
Yieldc
Coupling reactions using chiral prolinol derivatives as the
amine component were studied, and excellent diastereoselectivi-
ties (up to 99:1) were obtained. As depicted in Table 3, the a-sub-
1
2
3
4
[Au(C^N)Cl2]
[Au(salen)PF6]
[Au(C^N^C)Cl]
[Au(TPP)Cl]
99
99
10
0
82
94
–
stituents of the prolinol derivatives play a key role on the
diastereoselectivities. With prolinol methyl ether as the amine
component, propargylamine 2a was obtained with a diastereo-
meric ratio of 94:6 in 83% yield (entry 1). The absolute configura-
tion of 2a was assigned with reference to the literature data [18],
and that of others were assigned accordingly. Improved diastere-
oselectivity (96:4) was obtained when prolinol coupled with benz-
aldehyde and phenylacetylene to give 2b (62% yield; entry 2).
Chiral propargylamine 2c was obtained in high diastereoselectivity
by using prolinol of opposite chirality (75% yield, dr = 96:4, entry
3). Apart from prolinol derivatives, the coupling reaction involving
1-(2-pyrrolidinylmethyl)-pyrrolidine was also performed, giving
2d in 94% yield with 97:3 dr (entry 4). The coupling of bulky
–
a
Reaction conditions: 1 mmol of benzaldehyde, 1.1 mmol of piperidine,
1.5 mmol of phenylacetylene, 1 mL of H2O, 40 °C, 24 h.
b
Determined by 1H NMR analysis of crude reaction mixture based on benzal-
dehyde conversion.
c
Isolated yield based on benzaldehyde conversion.
+
N
O
N
O
-
Au
PF6
N
Au
Cl Cl
[Au(salen)]PF6
Ph
[Au(C^N)Cl2]
a,a-diphenylprolinol gave the highest diastereoselectivity (99:1)
where propargylamine 2e was synthesized in good yield (83% yield
based on 69% aldehyde conversion; entry 5). These experiments re-
vealed that the chiral substituents on the prolinol derivatives are
able to transfer chirality to the newly formed sp3 carbon center.
In addition, the methoxy, the hydroxyl and tertiary amine groups
remained intact after the coupling reactions.
We extended our study to the coupling reaction of prolinol with
aldehydes and acetylenes bearing various functionalities (Table 4).
The coupling of benzaldehydes bearing various p-substituents with
prolinol and phenylacetylene were performed. Excellent diastere-
oselectivities were observed in all attempts (entries 1–4). Propar-
gylamines 2f–i bearing different substituents in the p-position
were obtained in up to 99% yield and up to 98:2 dr (entries 1–4).
Propargylamine 2j bearing m-Cl substituent was obtained in 85%
yield with good diastereoselectivity (96:4; entry 5).
+
N
N
N
Ph
Au
Cl-
Ph
N
N
Au
Cl
[Au(TPP)]Cl
[Au(C^N^C)Cl]
Ph
in 1:1 CH3CN/H2O solution. The product [Au(C^N)Cl2] was filtered
as a pale yellow solid, and was identified by 1H NMR spectroscopy.
2.2. Ligand effects on the synthesis of propargylamines
The [Au(C^N)Cl2]-catalyzed three-component coupling reaction
also worked well for various alkynes. Coupling of benzaldehyde,
prolinol and 1-ethynylcyclohexene led to the formation of 2k in
84% yield with diastereoselectivity of 96:4 (Table 4, entry 6).
Changing the alkyne component to 1-ethynyl-5-methoxynaphtha-
lene gave propargylamine 2l in 71% yield with 96:4 dr (entry 7).
The coupling reaction of p-methylphenylacetylene with benzalde-
hyde and prolinol proceeded smoothly and gave propargylamine
2m in 92% yield with diastereoselectivity of 95:5 (entry 8).
By reacting isophthalaldehyde bearing two aldehyde groups
with prolinol and 1-ethynylcyclohexene, propargylamine 2n was
obtained in 87% yield with dr = 93:7 based on 75% aldehyde con-
version (entry 9). When phenylacetylene was used, propargylam-
ines 2o and 2p in a ratio of 1.7:1 in 83% total yield were
obtained (entry 10).
The catalytic activities of a panel of gold(III) complexes with dif-
ferent N-donor ligands towards the three-component coupling
reaction of benzaldehyde, piperidine and phenylacetylene in water
at 40 °C were examined. As depicted in Table 1, [Au(C^N)Cl2] was
found to have a comparable activity as that of [Au(salen)PF6], lead-
ing to 99% aldehyde conversion and 82% product yield (Table 1, en-
try 1).
The complex [Au(C^N^C)Cl] (CH^N^CH = 2,6-diphenylpyridine)
is much less reactive and only 10% aldehyde conversion was found
(entry 3). Interestingly, a stable [Au(C^N^C)] acetylide complex
was collected after the coupling reaction by flash column chroma-
tography, and its 1H NMR spectrum is consistent with its chemical
formulation [17]. We have also examined the catalytic activity of
gold(III) porphyrin complex [Au(TPP)Cl] (H2TPP = meso-tetraphen-
ylporphyrin), but no substrate conversion was observed (entry 4).
2.4. Mechanism
2.3. Substrate scope
To provide insight on the gold(III) (C^N) complex-catalyzed
three-component coupling reaction, the conversion of aldehyde
against reaction time was monitored. The study was conducted
as follows: coupling reaction of benzaldehyde, piperidine and
phenylacetylene was performed under the reaction conditions as
depicted in entry 1 of Table 1. An aliquot amount of reaction mix-
ture was taken out at regular time interval for the determination of
aldehyde conversion by 1H NMR analysis.
To examine the scope of this gold(III) (C^N) complex-catalyzed
three-component coupling reaction, we extended the catalysis to
different combinations of aldehydes, amines and alkynes. As de-
picted in Table 2, coupling of benzaldehyde with piperidine and
phenylacetylene led to propargylamine 1a in 82% yield based on
99% benzaldehyde conversion (entry 1). Reducing the catalyst

V.Kar-Yan Lo et al. / Journal of Organometallic Chemistry 694 (2009) 583–591
585
Table 2
Synthesis of propargylamines catalyzed by [Au(C^N)Cl2].a
)
n
(
)
(
n
[Au(C^N)Cl2] (1 mol%)
H
O
+
N
+
H2O, N2, 40 oC
R3
R1
H
N
H
R1
24 h
R3
Entry
1
R1
n
R3
Ph
Product
Conversionb
99
Yieldc
82
Ph
2
N
Ph
1a
Ph
2
C6H11
2
Ph
100
86
N
Ph
1b
3
Ph
1
Ph
98
76
N
Ph
1c
Ph
4
Ph
1
TMS
95
69
N
Ph
1d
TMS
a
Reaction conditions: 1 mmol of aldehyde, 1.1 mmol of amine, 1.5 mmol of alkyne, 1 mL of H2O, 40 °C, 24 h.
Determined by 1H NMR analysis of crude reaction mixture based on aldehyde conversion.
Isolated yields based on aldehyde conversion.
b
c
As depicted in Fig. 1, the plot of aldehyde conversion against
A proposed mechanism for the three-component coupling reac-
tion of aldehyde, amine and alkyne is illustrated in Scheme 1. Alde-
hyde is first condensed in situ with the secondary amine to give an
iminium ion, while the gold(III) (C^N) complex activates the C-H
bond of terminal alkyne to generate a gold acetylide intermediate.
The gold acetylide intermediate undergoes a nucleophilic attack on
the iminium ion to give propargylamine.
time showed that an induction period of around 2 h was required
for the [Au(C^N)Cl2] catalyst to become catalytically active. The
addition of NaCl or AgNO3 did not significantly affect the induction
period of the catalysis with [Au(C^N)Cl2] as catalyst.
We next examined the recyclability of [Au(C^N)Cl2], and exper-
iments were conducted as follows: coupling reaction of benzalde-
hyde, piperidine and phenylacetylene was performed under the
reaction conditions as depicted in entry 1 of Table 1. After 24 h,
the substrate conversion based on benzaldehyde was determined
by 1H NMR analysis of an aliquot of reaction mixture taken out
from the reaction flask. An additional portion of starting materials
was added into the reaction mixture. Then, the reaction continued
for an additional 24 h.
As depicted in Table 5, [Au(C^N)Cl2] could be repeatedly used
for 10 cycles leading to 812 product turnovers in total. In addition,
the reaction remained clean without the formation of side product.
These experiments demonstrated the recyclability of [Au(C^N)Cl2].
Comparing to the results obtained from gold(III) salen complex
(Fig. 2) [15b], [Au(C^N)Cl2] exhibited a higher stability.
3. Conclusion
In summary, we have developed a three-component coupling
reaction of aldehydes, amines and alkynes catalyzed by
[Au(C^N)Cl2] in water at 40 °C. A variety of propargylamines were
synthesized in good to excellent yields. Using chiral prolinol deriv-
atives as the amine component, diastereoselectivities up to 99:1
could be achieved. It was observed that [Au(C^N)Cl2] was able to
catalyze 10 successive reaction cycles, leading to an overall turn-
over number of 812.

586
V.Kar-Yan Lo et al. / Journal of Organometallic Chemistry 694 (2009) 583–591
Table 3
Effect of chiral prolinol derivatives on diastereoselectivity.a
R2
[Au(C^N)Cl2] (1 mol%)
H
O
R2
N
+
+
H2O, N2, 40 oC
24 h
N
Ph
Ph
H
Ph
H
Ph
Entry
1
R2
Product
Conversionb
Yieldc
83
drd
CH2OMe
99
78
94:6
OMe
N
Ph
2a
Ph
2
3
4
5
CH2OH
62
75
94
83
96:4
96:4
97:3
99:1
OH
N
Ph
2b
Ph
OH
Ph
CH2OH
86
62
69
N
Ph
2c
CH2N(C4H8)
N
N
Ph
2d
Ph
CPh2OH
Ph Ph
OH
N
Ph
2e
Ph
a
Reaction conditions: 1 mmol of benzaldehyde, 1.1 mmol of amine, 1.5 mmol of phenylacetylene, 1 mL of H2O, 40 °C, 24 h.
Determined by 1H NMR analysis of crude reaction mixture based on benzaldehyde conversion.
Isolated yield based on benzaldehyde conversion.
b
c
d
Determined by 1H NMR analysis of crude reaction mixture.
( )n
R2
N
H
[Au(C^N)Cl2]
R3
R1
R3
R2
-H+
(
)
n
)
(
- OH-
-
n
O
R2
Cl2(N^C)Au
N
+
R1
H
N
H
+ OH-
R3
R1
H
Scheme 1. Proposed reaction mechanism for the three-component coupling reaction.

V.Kar-Yan Lo et al. / Journal of Organometallic Chemistry 694 (2009) 583–591
587
Table 4
Substrate scope on the synthesis of chiral propargylamines catalyzed by [Au(C^N)Cl2].a
OH
R3
mol%)
H2O, N2, 40 oC
24 h
[Au(C^N)Cl2] (1
H
O
N
OH
+
+
N
H
R3
R1
H
R1
Entry
1
R1
R3
Product
Conversionb
100
Yieldc
68
drd
p-BrC6H4
98:2
H
H
H
H
H
OH
N
Ph
Ph
Ph
Ph
Ph
Ph
2f
Br
2
3
4
5
6
p-MeC6H4
p-t-BuC6H4
p-OMeC6H4
m-ClC6H4
Ph
39
87
18
100
97
91
70
99
85
84
96:4
97:3
96:4
96:4
96:4
OH
Ph
N
2g
Me
OH
Ph
N
2h
t
-Bu
OH
Ph
N
2i
MeO
Cl
OH
Ph
N
2j
H
OH
N
Ph
2k
7
Ph
99
71
96:4
H
OH
N
MeO
Ph
2l
OMe
(continued on next page)

588
V.Kar-Yan Lo et al. / Journal of Organometallic Chemistry 694 (2009) 583–591
Table 4 (continued)
Entry
8
R1
R3
Product
Conversionb
99
Yieldc
92
drd
Ph
95:5
H
OH
N
Me
Ph
2m
Me
9
m-CHOC6H4
75
87
93:7
H
OH
N
OHC
2n
10
m-CHOC6H4
85e
83f
94:6g
H
OH
N
Ph
OHC
Ph
2o
and
HO
OH
N
N
Ph
Ph
2p
a
Reaction conditions: 1 mmol of aldehyde, 1.1 mmol of amine, 1.5 mmol of alkyne, 1 mL of H2O, 40 °C, 24 h.
Determined by 1H NMR analysis of crude reaction mixture based on aldehyde conversion.
Isolated yield based on aldehyde conversion.
b
c
d
e
f
Determined by 1H NMR analysis of crude reaction mixture.
Determined by recovery of isophthalaldehyde.
2o:2p = 1.7:1.
Table 5
Experiment on the recycling of [Au(C^N)Cl2].a
[Au(C^N)Cl2] (1 mol%)
H2O, N2, 24 h
H
O
N
+
+
N
H
Ph
Ph
H
Ph
1a
Ph
Cycle
1
100
2
100
3
92
4
89
5
84
6
76
7
73
8
70
9
67
10
60
Conversionb
a
Reaction conditions: 1 mmol of benzaldehyde, 1.1 mmol of piperidine, 1.5 mmol of phenylacetylene, 1 mL of H2O, 40 °C, 24 h.
b
Determined by 1H NMR analysis of crude reaction mixture based on benzaldehyde conversion.
spectrometer. IR spectra were recorded, using NaCl or KBr discs, on
a Bio-Rad FTS-165 spectrometer.
4. Experimental
4.1. General
4.2. General procedure for [Au(C^N)Cl2]-catalyzed three-component
coupling reaction
Gold(III) (C^N) complex [Au(C^N)Cl2] (N^CH = 2-phenylpyri-
dine) was synthesized according to a reported procedure [16]. All
reagents were commercially available and used without further
purification. All experiments were carried out under an inert atmo-
sphere of nitrogen. NMR spectra were recorded in CDCl3 on Bruker
DX300 or DX400 spectrometer at 25 °C with TMS as an internal
standard. Mass spectra were obtained on a Finnigan MAT 95 mass
A mixture of [Au(C^N)Cl2] (0.01 mmol), aldehyde (1.0 mmol),
amine (1.1 mmol) and alkyne (1.5 mmol) in water (1 mL) was stir-
red at 40 °C for 24 h under N2 atmosphere. The reaction mixture
was extracted with diethyl ether or CH2Cl2. The combined organic
layers were dried over anhydrous Na2SO4 or MgSO4, filtered, and

V.Kar-Yan Lo et al. / Journal of Organometallic Chemistry 694 (2009) 583–591
589
4H), 1.80–1.77 (m, 4H); 13C NMR (100 MHz, CDCl3) d 139.32,
131.79, 128.32, 128.26, 128.10, 127.61, 123.19, 86.98, 86.56,
59.08, 50.23, 23.49; IR (NaCl, neat, cmÀ1) 2333; EIMS m/z 261
(M+); HRMS (EI) for C19H19N, Calc. 261.1517, found: 261.1506.
100
80
60
40
20
0
4.3.4. 1-(1-phenyl-3-trimethylsilylprop-2-ynyl)pyrrolidine (1d)
Yellowish oil; analytical TLC (silica gel 60) (10% EtOAc in hex-
ane) Rf = 0.36; 1H NMR (400 MHz, CDCl3) d 7.53–7.51 (m, 2H),
7.33–7.31 (m, 2H), 7.28–7.26 (m, 1H), 4.65 (s, 1H), 2.58 (t,
J = 6.7 Hz, 4H), 1.76 (t, J = 6.3 Hz, 4H), 0.21 (s, 9H); 13C NMR
(100 MHz, CDCl3) d 139.25, 128.26, 128.18, 127.48, 102.92, 91.23,
59.23, 50.06, 23.47, 0.18; IR (NaCl, neat, cmÀ1) 2163; EIMS m/z
257 (M+); HRMS (EI) for C16H23NSi, Calc. 257.1599, found:
257.1589.
4.3.5. (S)-1-((S)-1,3-diphenylprop-2-ynyl)-2-
(methoxymethyl)pyrrolidine (2a) [18]
0
5
10
15
20
25
Time (hours)
Pale yellow oil; analytical TLC (silica gel 60) (30% EtOAc in hex-
ane), Rf = 0.24; 1H NMR (300 MHz, CDCl3) d 7.61–7.59 (m, 2H),
7.53–7.48 (m, 2H), 7.40–7.30 (m, 6H), 5.12 (s, 1H), 3.84 (dd,
J = 10.9, 3.5 Hz, 1H), 3.54 (dd, J = 10.9, 2.2 Hz, 1H), 3.31–3.27 (m,
1H), 2.82 (dd, J = 9.2, 7.3 Hz, 1H), 2.63 (td, J = 8.0, 3.0 Hz, 1H),
1.97–1.92 (m, 1H), 1.87–1.75 (m, 1H), 1.73–1.66 (m, 2H); 13C
NMR (125 MHz, CDCl3) d 139.18, 131.85, 128.46, 128.40, 128.37,
128.34, 128.31, 128.09, 127.62, 122.99, 87.83, 85.37, 61.83, 61.75,
56.25, 47.90, 28.04, 23.60; IR (NaCl, neat, cmÀ1) 3436, 2361,
2341; EIMS m/z 291 (M+); HRMS (EI) for C20H21NO, Calc.
291.1623, found: 291.1617.
Fig. 1. Reaction profile of [Au(C^N)Cl2]-catalyzed coupling of benzaldehyde,
piperidine and phenylacetylene.
concentrated under reduced pressure. The product was purified by
flash column chromatography on silica gel using ethyl acetate–
hexane as eluent.
4.3. Characterization
4.3.1. 1-(1,3-diphenylprop-2-ynyl)piperidine (1a) [12]
4.3.6. ((S)-1-((S)-1,3-diphenylprop-2-ynyl)pyrrolidin-2-yl)methanol
(2b) [15b]
Yellowish oil; analytical TLC (silica gel 60) (10% EtOAc in hex-
ane) Rf = 0.30; 1H NMR (400 MHz, CDCl3) d 7.64–7.62 (m, 2H),
7.53–7.50 (m, 2H), 7.37–7.24 (m, 6H), 4.79 (s, 1H), 2.57–2.54 (m,
4H), 1.61–1.55 (m, 4H), 1.45-1.42 (m, 2H); 13C NMR (100 MHz,
CDCl3) d 138.51, 131.81, 128.57, 128.27, 128.06, 127.43, 123.34,
Pale yellow oil; analytical TLC (silica gel 60) (30% EtOAc in hex-
ane), Rf = 0.24; 1H NMR (300 MHz, CDCl3) d 7.61–7.59 (d, J = 7.2 Hz,
2H), 7.53–7.48 (m, 2H), 7.40–7.30 (m, 6H), 5.12 (s, 1H), 3.86–3.81
(dd, J = 10.9, 3.5 Hz, 1H), 3.56–3.51 (dd, J = 10.9, 2.2 Hz, 1H),
3.31–3.27 (m, 1H), 2.86–2.77 (dd, J = 9.2, 7.3 Hz, 1H), 2.66–2.59
(td, J = 8.0, 3.0 Hz, 1H), 1.97–1.92 (m, 1H), 1.87–1.75 (m, 1H),
1.73–1.66 (m, 2H); 13C NMR (125 MHz, CDCl3) d 139.18, 131.85,
128.46, 128.40, 128.37, 128.34, 128.31, 128.09, 127.62, 122.99,
87.83, 85.37, 61.83, 61.75, 56.25, 47.90, 28.04, 23.60; IR (KBr, neat,
cmÀ1) 3436, 2361, 2341; EIMS m/z 291 (M+); HRMS (EI) for
C20H21NO, Calc. 291.1623, found: 291.1617.
87.86, 86.04, 62.36, 50.68, 26.14, 24.42; IR (NaCl, neat, cmÀ1
)
2314; EIMS m/z 275 (M+); HRMS (EI) for C20H21N, Calc. 275.1674,
found: 275.1672.
4.3.2. 1-(1-cyclohexyl-3-phenylprop-2-ynyl)piperidine (1b) [10a]
Yellowish oil; analytical TLC (silica gel 60) (10% EtOAc in hex-
ane) Rf = 0.45; 1H NMR (400 MHz, CDCl3) d 7.45–7.43 (m, 2H),
7.29–7.27 (m, 3H), 3.10 (d, J = 9.9 Hz, 1H), 2.63–2.61 (m, 2H),
2.41–2.39 (m, 2H); 13C NMR (100 MHz, CDCl3) d 131.72, 128.19,
127.62, 123.69, 87.94, 85.75, 64.39, 39.61, 31.34, 30.46, 39.72,
26.82, 26.30, 26.12, 24.73; IR (NaCl, neat, cmÀ1) 2335; EIMS m/z
281 (M+); HRMS (EI) for C20H27N, Calc. 281.2143, found: 281.2130.
4.3.7. (S)-1-((S)-1,3-diphenylprop-2-ynyl)-2-(pyrrolidin-1-
ylmethyl)pyrrolidine (2d)
Yellow oil; analytical TLC (silica gel 60) (80% EtOAc in hexane)
Rf = 0.17; 1H NMR (300 MHz, CDCl3) d 7.66–7.63 (m, 2H), 7.52–
7.48 (m, 2H), 7.40–7.22 (m, 6H), 5.56 (s, 1H), 3.22–3.13 (m, 1H),
2.78 (dd, J = 12.0, 5.6 Hz, 1H), 2.71 (t, J = 8.4 Hz, 1H), 2.64–2.49
(m, 6H), 2.04–1.97 (m, 1H), 1.81–1.75 (m, 4H), 1.71–1.56 (m,
3H); 13C NMR (75 MHz, CDCl3) d 140.03, 131.80, 128.27, 128.17,
128.09, 127.96, 127.16, 123.43, 87.48, 86.46, 62.45, 59.57, 56.95,
4.3.3. 1-(1,3-diphenylprop-2-ynyl)pyrrolidine (1c) [10a]
Yellowish oil; analytical TLC (silica gel 60) (10% EtOAc in hex-
ane) Rf = 0.20; 1H NMR (300 MHz, CDCl3) d 7.62–7.59 (m, 2H),
7.50–7.47 (m, 2H), 7.39–7.28 (m, 6H), 4.89 (s, 1H), 2.71–2.67 (m,
H
O
[Au(salen)]PF6 (1 mol%)
H2O, N2, 24 h
N
+
+
N
H
Ph
Ph
H
Ph
1a
Ph
Conversion
96%
1st cycle
83%
2nd cycle
3rd cycle
73%
Fig. 2. Recyclability experiment for gold(III) salen complex [15b].

590
V.Kar-Yan Lo et al. / Journal of Organometallic Chemistry 694 (2009) 583–591
54.97, 47.84, 30.60, 29.69, 23.54, 22.78; IR (NaCl, neat, cmÀ1) 3427,
2246; EIMS m/z 344 (M+); HRMS (EI) for C24H28N2, Calc. 344.2252,
found: 344.2246.
m/z 321 (M+); HRMS (EI) for C21H23NO2, Calc. 321.1729, found:
321.1722.
4.3.13. ((S)-1-((S)-1-(3-chlorophenyl)-3-phenylprop-2-
4.3.8. ((S)-1-((S)-1,3-diphenylprop-2-ynyl)pyrrolidin-2-
ynyl)pyrrolidin-2-yl)methanol (2i) [15f]
yl)diphenylmethanol (2e) [15b]
Pale yellow oil; analytical TLC (silica gel 60) (30% EtOAc in hex-
ane) Rf = 0.31; 1H NMR (400 MHz, CDCl3) d 7.60 (s, 1H), 7.52–7.50
(m, 3H), 7.35–7.34 (m, 3H), 7.29–7.25 (m, 2H), 5.10 (s, 1H), 3.81
(dd, J = 11.0, 3.6 Hz, 1H), 3.55 (dd, J = 11.0, 1.9 Hz, 1H), 3.29–3.24
(m, 1H), 2.81–2.75 (m, 1H), 2.63–2.58 (m, 2H), 1.98–1.62 (m,
4H); 13C NMR (100 MHz, CDCl3) d 141.28, 134.20, 131.85, 129.56,
128.46, 128.38, 128.14, 127.77, 126.27, 122.64, 88.20, 84.53,
62.07, 61.81, 55.91, 47.87, 28.89, 23.55; IR (KBr, neat cmÀ1) 3431,
2362; EIMS m/z 294 (M+-CH2OH); HRMS (EI) for C19H17NCl, Calc.
294.1049, found: 294.1046.
Pale yellow solid; analytical TLC (silica gel 60) (10% EtOAc in
hexane), Rf = 0.39; 1H NMR (300 MHz, CDCl3) d 7.86–7.83 (m,
2H), 7.64–7.61 (m, 2H), 7.57–7.54 (m, 2H), 7.40–7.37 (m, 3H),
7.32–7.29 (m, 6H), 7.26–7.21 (m, 3H), 7.20–7.12 (m, 2H), 4.69 (s,
1H), 4.51 (q, J = 5.0 Hz, 1H), 4.27 (s, 1H), 2.94 (td, J = 9.1, 7.1 Hz,
1H), 1.98–1.82 (m, 1H), 1.81–1.60 (m, 3H); 13C NMR (125 MHz,
CDCl3) d 147.98, 146.53, 139.19, 131.89, 128.74, 128.43, 128.40,
128.32, 128.12, 128.11, 127.99, 127.90, 127.44, 127.02, 126.68,
126.28, 125.49, 125.46, 123.16, 87.58, 85.83, 77.89, 68.10, 57.90,
49.48, 30.92, 29.89, 24.26; IR (NaCl, neat, cmÀ1) 3391, 2360; FAB-
MS m/z 444 (M++H).
4.3.14. ((S)-1-((S)-cyclohexenyl-1-phenylprop-2-ynyl)pyrrolidin-2-
yl)methanol (2k) [15f]
4.3.9. ((S)-1-((S)-1-(4-bromophenyl)-3-phenylprop-2-
ynyl)pyrrolidin-2-yl)methanol (2f) [15f]
Yellowish oil; analytical TLC (silica gel 60) (30% EtOAc in hex-
ane) Rf = 0.26; 1H NMR (400 MHz, CDCl3) d 7.54–7.52 (m, 2H),
7.32–7.28 (m, 2H), 7.24–7.21 (m, 1H), 6.16–6.13 (m, 1H), 4.99 (s,
1H), 3.73 (dd, J = 10.9, 3.8 Hz, 1H), 3.49 (dd, J = 10.9, 2.5 Hz, 1H),
3.19–3.13 (m, 1H), 2.89 (br, s, 1H), 2.73–2.67 (m, 1H), 2.55–2.50
(m, 1H), 2.19–2.18 (m, 2H), 2.10–2.08 (m, 2H), 1.96–1.76 (m,
2H), 1.67–1.49 (m, 6H); 13C NMR (100 MHz, CDCl3) d 139.34,
134.32, 127.99, 127.94, 127.15, 120.25, 89.43, 82.14, 61.90, 61.49,
56.01, 47.49, 29.46, 27.85, 25.39, 23.30, 22.14, 13.91; IR (NaCl,
neat, cmÀ1) 3412, 2361, 1602; EIMS m/z 264 (M+ÀCH2OH).
Light yellow oil; analytical TLC (silica gel 60) (10% EtOAc in hex-
ane) Rf = 0.09; 1H NMR (300 MHz, CDCl3) d 7.52–7.48 (m, 6H),
7.36–7.33 (m, 3H), 5.07 (s, 1H), 3.80 (dd, J = 11.0, 3.5 Hz, 1H),
3.54 (dd, J = 11.0, 2.6 Hz, 1H), 3.30–3.16 (m, 1H), 2.79–2.75 (m,
1H), 2.00–1.65 (m, 4H); 13C NMR (75 MHz, CDCl3) d 138.26,
131.82, 131.52, 131.39, 129.96, 129.78, 128.44, 128.38, 122.68,
121.50, 88.15, 87.71, 62.05, 61.80, 55.83, 47.83, 27.93, 23.53; IR
(NaCl, neat, cmÀ1) 3430, 2359; EIMS m/z 369 (M+); HRMS (EI) for
C20H20BrNO, Calc. 369.0728, found: 369.0710.
4.3.15. ((S)-1-((S)-3-(5-methoxynaphthalen-1-yl)-1-phenylprop-2-
ynyl)pyrrolidin-2-yl)methanol (2l)
4.3.10. ((S)-1-((S)-1-(4-methylphenyl)-3-phenylprop-2-
ynyl)pyrrolidin-2-yl)methanol (2g)
Pale yellow solid; analytical TLC (silica gel 60) (30% EtOAc in
hexane) Rf = 0.25; 1H NMR (400 MHz, CDCl3) d 7.94 (s, 1H), 7.69–
7.63 (m, 4H), 7.52–7.50 (dd, J = 8.5, 1.6 Hz, 1H), 7.39–7.35 (m,
2H), 7.31–7.27 (t, J = 2.4 Hz, 1H), 7.16–7.14 (dd, J = 8.9, 2.5 Hz,
1H), 7.09–7.08 (d, J = 2.4 Hz, 1H), 5.15 (s, 1H), 3.88 (s, 3H), 3.84–
3.70 (dd, J = 10.9, 3.6 Hz, 1H), 3.57–3.53 (dd, J = 10.9, 2.5 Hz, 1H),
3.34–3.29 (m, 1H), 2.89–2.83 (td, J = 9.3, 7.3 Hz, 1H), 2.67–2.62
(m, 1H), 2.04–1.94 (m, 1H), 1.90–1.82 (m, 1H), 1.78–1.61 (m,
2H); 13C NMR (75 MHz, CDCl3) d 158.24, 139.21, 134.08, 131.33,
129.18, 129.14, 128.41, 128.27, 128.08, 127.54, 126.79, 119.42,
117.75, 105.28, 88.26, 84.87, 61.93, 61.78, 56.37, 55.24, 47.90,
28.50, 23.53; IR (NaCl, neat cmÀ1) 3436, 2361, 2214; EIMS m/z
371 (M+); HRMS (EI) for C25H25NO2, Calc. 371.1885, found:
371.1874.
Light yellow oil; analytical TLC (silica gel 60) (10% EtOAc in hex-
ane) Rf = 0.31; 1H NMR (300 MHz, CDCl3) d 7.51–7.46 (m, 4H),
7.33–7.29 (m, 3H), 7.17–7.15 (d, J = 7.9 Hz, 2H), 5.07 (s, 1H),
3.82–3.77 (dd, J = 10.9, 3.6 Hz, 1H), 3.54–3.49 (dd, J = 10.9, 2.4 Hz,
1H), 3.29–3.22 (m, 1H), 2.85–2.76 (td, J = 9.2, 7.3 Hz, 1H), 2.66–
2.60 (m, 1H), 2.34 (s, 3H), 2.00–1.65 (m, 4H); 13C NMR (75 MHz,
CDCl3) d 137.19, 136.18, 131.76, 128.94, 128.28, 128.17, 127.93,
122.99, 87.54, 85.61, 61.85, 61.64, 55.94, 47.84, 28.02, 23.51,
21.03; IR (NaCl, neat, cmÀ1) 3418, 2358; EIMS m/z 305 (M+); HRMS
(EI) for C21H23NO, Calc. 305.1780, found: 305.1770.
4.3.11. ((S)-1-((S)-1-(4-tert-butylphenyl)-3-phenylprop-2-
ynyl)pyrrolidin-2-yl)methanol (2h) [15f]
Yellowish oil; analytical TLC (silica gel 60) (10% EtOAc in hex-
ane) Rf = 0.10; 1H NMR (300 MHz, CDCl3) d 7.54–7.48 (m, 4H),
7.39–7.36 (m, 2H), 7.32–7.30 (m, 3H), 5.08 (s, 1H), 3.80 (dd,
J = 10.9, 3.6 Hz, 1H), 3.52 (dd, J = 10.9, 2.2 Hz, 1H), 3.29–3.23 (m,
1H), 2.87–2.78 (m, 1H), 2.69–2.62 (m, 1H), 1.96-1.67 (m, 4H),
1.32 (s, 9H); 13C NMR (75 MHz, CDCl3) d 150.45, 136.14, 131.76,
128.27, 128.15, 127.95, 127.70, 125.16, 123.03, 87.49, 85.68,
61.90, 61.67, 55.88, 47.88, 34.44, 31.32, 28.02, 23.53; IR (NaCl,
neat, cmÀ1) 3430, 2361; EIMS m/z 347 (M+); HRMS (EI) for
C24H29NO, Calc. 347.2249, found: 347.2243.
4.3.16. ((S)-1-((S)-1-phenyl-3-p-tolylprop-2-ynyl)pyrrolidin-2-
yl)methanol (2m)
Yellowish oil; Analytical TLC (silica gel 60) (30% EtOAc in hex-
ane) Rf = 0.40; 1H NMR (300 MHz, CDCl3) d 7.61–7.59 (d, J = 7.3
Hz, 2H), 7.40–7.38 (d, J = 8.0 Hz, 2H), 7.34–7.30 (m, 2H), 7.26–
7.21 (m, 1H), 7.10–7.07 (d, J = 7.9 Hz, 2H), 5.10 (s, 1H), 3.78–3.73
(dd, J = 10.9, 3.9 Hz, 1H), 3.54–3.50 (dd, J = 10.9, 2.6 Hz, 1H),
3.27–3.20 (m, 1H), 2.84–2.75 (m, 1H), 2.62–2.59 (m, 1H), 2.30 (s,
3H), 1.98–1.58 (m, 4H); 13C NMR (75 MHz, CDCl3) d 139.13,
138.05, 131.48, 128.85, 128.03, 127.88, 127.27, 119.73, 87.67,
84.55, 62.11, 61.63, 56.23, 47.67, 27.86, 23.31, 21.19; IR (NaCl,
neat, cmÀ1) 3426, 2209; EIMS m/z 305 (M+); HRMS (EI) for
C21H23NO, Calc. 305.1779, found: 305.1781.
4.3.12. ((S)-1-((S)-1-(4-methoxyphenyl)-3-phenylprop-2-
ynyl)pyrrolidin-2-yl)methanol (2i)
Yellowish oil; analytical TLC (silica gel 60) (30% EtOAc in hex-
ane) Rf = 0.20; 1H NMR (300 MHz, CDCl3) d 7.52–7.48 (m, 4H),
7.35–7.30 (m, 3H), 6.90–6.87 (d, J = 8.7 Hz, 2H), 5.06 (s, 1H),
3.81–3.76 (m, 1H), 3.80 (s, 3H), 3.54–3.50 (dd, J = 10.9, 2.4 Hz,
1H), 3.27–3.21 (m, 1H), 2.84–2.59 (m, 2H), 1.99–1.66 (m, 4H);
13C NMR (75 MHz, CDCl3) d 158.94, 131.70, 131.28, 129.09,
128.24, 128.13, 122.93, 113.54, 87.50, 85.70, 61.97, 61.58, 55.62,
55.15, 47.78, 28.01, 23.43; IR (NaCl, neat, cmÀ1) 3430, 2202; EIMS
4.3.17. 3-((S)-3-cyclohexenyl-1-((S)-2-(hydroxymethyl)pyrrolidin-1-
yl)prop-2-ynyl)benzaldehyde (2n)
Yellow oil; analytical TLC (silica gel 60) (30% EtOAc in hexane)
Rf = 0.29; 1H NMR (400 MHz, CDCl3) d 10.04 (s, 1H), 8.07 (s, 1H),
7.84–7.80 (m, 2H), 7.53–7.49 (m, 1H), 6.22–6.19 (m, 1H), 5.09 (s,
1H), 3.80 (dd, J = 11.0, 3.7 Hz, 1H), 3.55 (dd, J = 11.0, 2.7 Hz, 1H),

V.Kar-Yan Lo et al. / Journal of Organometallic Chemistry 694 (2009) 583–591
[4] (a) C.W. Ryan, C. Ainsworth, J. Org. Chem. 26 (1961) 1547;
591
3.24–3.19 (m, 1H), 2.74–2.67 (m, 1H), 2.52–2.47 (m, 1H), 2.22–2.19
(m, 2H), 2.14–2.12 (m, 2H), 1.96–1.55 (m, 8H); 13C NMR (100 MHz,
CDCl3) d 192.32, 140.79, 136.37, 135.23, 134.23, 129.44, 128.90,
128.71, 120.10, 90.31, 80.25, 62.09, 61.73, 55.89, 47.63, 29.51,
27.81, 25.55, 23.42, 22.21, 21.39; IR (KBr, neat, cmÀ1) 3435, 2365,
2219, 1698; EIMS m/z 323 (M+); HRMS (EI) for C21H25NO2, Calc.
323.1885, found: 323.1881.
(b) F. Tubéry, D.S. Grierson, H.-P. Husson, Tetrahedron Lett. 28 (1987) 6457;
(c) M.E. Jung, A. Huang, Org. Lett. 2 (2000) 2659;
(d) T. Murai, Y. Mutoh, Y. Ohta, M. Murakami, J. Am. Chem. Soc. 126 (2004)
5968.
[5] (a) C. Wei, Z. Li, C.-J. Li, Synlett (2004) 1472;
(b) L. Zani, C. Bolm, Chem. Commun. (2006) 4263;
(c) V.V. Kouznetsov, L.Y. Vargas Méndez, Synthesis (2008) 491.
[6] (a) C. Fischer, E.M. Carreira, Org. Lett. 3 (2001) 4319;
(b) S. Sakaguchi, T. Mizuta, M. Furuwan, T. Kubo, Y. Ishii, Chem. Commun.
(2004) 1638.
[7] N. Sakai, M. Hirasawa, T. Konakahara, Tetrahedron Lett. 44 (2003) 4171.
[8] (a) L. Zani, T. Eichhorn, C. Bolm, Chem. Eur. J. 13 (2007) 2587;
(b) E. Ramu, R. Varala, N. Sreelatha, S.R. Adapa, Tetrahedron Lett. 48 (2007)
7184;
4.3.18. 3-((S)-1-((S)-2-(hydroxymethyl)pyrrolidin-1-yl)-3-
phenylprop-2-ynyl)benzaldehyde (2o) [15f]
Yellowish oil; analytical TLC (silica gel 60) (30% EtOAc in hex-
ane) Rf = 0.19; 1H NMR (300 MHz, CDCl3) d 10.04 (s, 1H), 8.14 (s,
1H), 7.90 (dd, J = 7.7, 0.6 Hz, 1H), 7.83 (d, J = 7.6 Hz, 1H), 7.56–
7.51 (m, 3H), 7.36–7.34 (m, 3H), 5.24 (s, 1H), 3.84 (dd, J = 11.0,
3.7 Hz, 1H), 3.60 (dd, J = 11.0, 2.8 Hz, 1H), 3.34–3.27 (m, 1H),
2.85–2.77 (m, 1H), 2.61–2.55 (m, 2H), 1.91–1.64 (m, 4H); 13C
NMR (75 MHz, CDCl3) d 192.15, 140.50, 136.48, 134.15, 131.81,
129.33, 128.97, 128.82, 128.44, 128.34, 122.55, 88.39, 84.45,
(c) M.L. Kamtam, V. Balasubrahmanyam, K.B.S. Kumar, G.T. Venkanna,
Tetrahedron Lett. 48 (2007) 7332.
[9] (a) C.-J. Li, C. Wei, Chem. Commun. (2002) 268;
(b) N.E. Leadbeater, H.M. Torenius, H. Tye, Mol. Divers. 7 (2003) 135;
(c) L. Shi, Y.-Q. Tu, M. Wang, F.-M. Zhang, C.-A. Fan, Org. Lett. 6 (2004) 1001;
(d) C. Wei, J.T. Mague, C.-J. Li, Proc. Natl. Acad. Sci. 101 (2004) 5749;
(e) S.B. Park, H. Alper, Chem. Commun. (2005) 1315;
(f) B. Sreedhar, P.S. Reddy, B.V. Prakash, A. Ravindra, Tetrahedron Lett. 46
(2005) 7019;
62.42, 61.94, 56.12, 47.83, 27.84, 23.45; IR (NaCl, neat, cmÀ1
)
(g) B. Huang, X. Yao, C.-J. Li, Adv. Synth. Catal. 348 (2006) 1528;
(h) A. Bisai, V.K. Singh, Org. Lett. 8 (2006) 2405;
(i) P. Aschwanden, C.R.J. Stephenson, E.M. Carreira, Org. Lett. 8 (2006) 2437;
(j) N. Gommermann, P. Knochel, Chem. Eur. J. 12 (2006) 4380;
(k) M. Kidwai, V. Bansal, N. Kumar Mishra, A. Kumar, S. Mozumdar, Synlett
(2007) 1581.
3421, 2361, 1699; EIMS m/z 319 (M+); HRMS (EI) for C21H21NO2,
Calc. 319.1572, found: 319.1570.
4.3.19. Compound 2p [15f]
[10] (a) C. Wei, Z. Li, C.-J. Li, Org. Lett. 5 (2003) 4473;
(b) J.-X. Ji, T.T.-L. Au-Yeung, J. Wu, C.W. Yip, A.S.C. Chan, Adv. Synth. Catal. 346
(2004) 42;
Pale yellow solid; analytical TLC (silica gel 60) (30% EtOAc in hex-
ane) Rf = 0.03; 1H NMR (400 MHz, CDCl3) d 7.92 (s, 1H), 7.54–7.51
(m, 2H), 7.48–7.45 (m, 4H), 7.37 (t, J = 7.6 Hz, 1H), 7.33–7.24 (m,
4H), 5.14 (s, 2H), 3.82 (dd, J = 10.9, 3.5 Hz, 2H), 3.54 (dd, J = 11.0,
2.3 Hz, 2H), 3.31–3.26 (m, 2H), 2.85–2.79 (m, 2H), 2.67–2.56 (m,
2H), 2.00–1.83 (m, 5H), 1.76–1.64 (m, 5H); 13C NMR (100 MHz,
CDCl3) d 139.35, 131.82, 128.32, 128.22, 127.68, 127.33, 122.89,
87.84, 85.40, 62.02, 61.81, 56.35, 48.01, 28.03, 23.61; IR (NaCl, neat,
cmÀ1) 3435, 2336; EIMS m/z 473 (M+ÀCH2OH); HRMS (EI) for
C33H33N2O, Calc. 473.2593, found: 473.2599.
(c) Z. Li, C. Wei, L. Chen, R.S. Varma, C.-J. Li, Tetrahedron Lett. 45 (2004) 2443;
(d) X. Yao, C.-J. Li, Org. Lett. 7 (2005) 4395;
(e) K.M. Reddy, N.S. Babu, I. Suryanarayana, P.S. Sai Prasad, N. Lingaiah,
Tetrahedron Lett. 47 (2006) 7563.
[11] (a) A.S.K. Hashmi, Gold Bull. 36 (2003) 3;
(b) A. Arcadi, S. di Giuseppe, Curr. Org. Chem. 8 (2004) 795;
(c) A. Hoffmann-Röder, N. Krause, Org. Biomol. Chem. 3 (2005) 387;
(d) S. Ma, S. Yu, Z. Gu, Angew. Chem., Int. Ed. 45 (2006) 200;
(e) A.S.K. Hashmi, G.J. Hutchings, Angew. Chem., Int. Ed. 45 (2006) 7896;
(f) D.J. Gorin, F.D. Toste, Nature 446 (2007) 395;
(g) A.S.K. Hashmi, Chem. Rev. 107 (2007) 3180;
(h) N. Marion, S.P. Nolan, Angew. Chem., Int. Ed. 46 (2007) 2750;
(i) A. Fürstner, P.W. Davies, Angew. Chem., Int. Ed. 46 (2007) 3410;
(j) Z. Li, C. Brouwer, C. He, Chem. Rev. 128 (2008) 3239;
(k) A. Arcadi, Chem. Rev. 128 (2008) 3266;
Acknowledgments
This work was supported by the Hong Kong Research Grants
Council (PolyU 7052/07P), PolyU Departmental General Research
Funds, The University of Hong Kong (University Development
Fund), and the University Grants Committee of the Hong Kong
SAR of China (Area of Excellence Scheme, AoE/P-10/01).
(l) E. Jiménez-Núñez, A.M. Echavarren, Chem. Rev. 128 (2008) 3326;
(m) D.J. Gorin, B.D. Sherry, F.D. Toste, Chem. Rev. 128 (2008) 3351.
[12] C. Wei, C.-J. Li, J. Am. Chem. Soc. 125 (2003) 9584.
[13] (a) M.L. Kantam, B.V. Prakash, C.R.V. Reddy, B. Sreedhar, Synlett 15 (2005)
2329;
(b) M. Kidwai, V. Bansal, A. Kumar, S. Mozumdar, Green Chem. 9 (2007) 742;
(c) F. Xiao, Y. Chen, Y. Liu, J. Wang, Tetrahedron 64 (2008) 2755;
(d) X. Zhang, A. Corma, Angew. Chem., Int. Ed. 47 (2008) 4358.
[14] A.S.K. Hashimi, J.P. Weyrauch, M. Rudolph, E. Kurpejovic´, Angew. Chem., Int.
Ed. 43 (2004) 6545.
References
[15] (a) C.-Y. Zhou, P.W.H. Chan, C.-M. Che, Org. Lett. 8 (2006) 325;
(b) V.K.-Y. Lo, Y. Liu, M.-K. Wong, C.-M. Che, Org. Lett. 8 (2006) 1529;
(c) X.-Y. Liu, C.-H. Li, C.-M. Che, Org. Lett. 8 (2006) 2707;
(d) X.-Y. Liu, P. Ding, J.-S. Huang, C.-M. Che, Org. Lett. 9 (2007) 2645;
(e) C.-Y. Zhou, C.-M. Che, J. Am. Chem. Soc. 129 (2007) 5828;
(f) V.K-Y. Lo, M.-K. Wong, C.-M. Che, Org. Lett. 10 (2008) 517;
(g) X.-Y. Liu, C.-M. Che, Angew. Chem., Int. Ed. 47 (2008) 3805;
(h) M.-Z. Wang, M.-K. Wong, C.-M. Che, Chem. Eur. J. 14 (2008) 8353.
[16] E.C. Constable, T.A. Leese, J. Organomet. Chem. 363 (1989) 419.
[17] (a) V.W.-W. Yam, K.M.-C. Wong, L.-L. Hung, N. Zhu, Angew. Chem., Int. Ed. 44
(2005) 3107;
[1] (a) D.F. Harvey, D.M. Sigano, J. Org. Chem. 61 (1996) 2268;
(b) A. Fürstner, H. Szillat, F. Stelzer, J. Am. Chem. Soc. 122 (2000) 6785;
(c) Y. Yamamoto, H. Hayashi, T. Saigoku, H. Nishiyama, J. Am. Chem. Soc. 127
(2005) 10804;
(d) E.-S. Lee, H.-S. Yeom, J.-H. Hwang, S. Shin, Eur. J. Org. Chem. (2007) 3503;
(e) B. Yan, Y. Liu, Org. Lett. 9 (2007) 4323;
(f) O. Russo, S. Messaoudi, A. Hamze, N. Olivi, J.-F. Peyrat, J.-D. Brion, S. Sicsic, I.
Berque-Bestel, M. Alami, Tetrahedron 63 (2007) 10671.
[2] (a) M. Shibasaki, Y. Ishida, G. Iwasaki, T. Iimori, J. Org. Chem. 52 (1987) 3488;
(b) N. Gommermann, P. Knochel, Chem. Commun. (2004) 2324;
(c) B. Jiang, M. Xu, Angew. Chem., Int. Ed. 43 (2004) 2543;
(d) Q. Xu, E. Rozners, Org. Lett. 7 (2005) 2821.
(b) K.M.-C. Wong, L.-L. Hung, W.H. Lam, N. Zhu, V.W.-W. Yam, J. Am. Chem.
Soc. 129 (2007) 4350.
[18] N. Gommermann, C. Koradin, K. Polborn, P. Knochel, Angew. Chem., Int. Ed. 42
(2003) 5763.
[3] (a) For reviews, see: D. Enders, U. Reinhold, Tetrahedron: Asymmetry 8 (1997)
1895;
(b) R. Bloch, Chem. Rev. 98 (1998) 1407.