Catalytic activity of gold nanoclusters in intramolecular hydroamination of alkenes and alkynes with toluenesulfonamide under aerobic and basic conditions

Article abstract of DOI:10.1016/j.jorganchem.2010.08.038

Gold nanoclusters stabilized by a hydrophilic polymer, poly(N-vinyl-2- pyrrolidone) (Au:PVP), catalyzed the intramolecular hydroamination of toluenesulfonamides to unactivated alkenes/alkynes in EtOH under aerobic and basic conditions. The reaction procee

Full text of DOI:10.1016/j.jorganchem.2010.08.038

Journal of Organometallic Chemistry 696 (2011) 442e449
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Journal of Organometallic Chemistry
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Catalytic activity of gold nanoclusters in intramolecular hydroamination of
alkenes and alkynes with toluenesulfonamide under aerobic and basic conditions
,b,
Hiroaki Kitahara a, Hidehiro Sakurai a
*
a Research Center for Molecular-Scale Nanoscience, Institute for Molecular Science, Myodaiji, Okazaki 444-8787, Japan
b PRESTO, Japan Science and Technology Agency, Tokyo 102-0075, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Gold nanoclusters stabilized by a hydrophilic polymer, poly(N-vinyl-2-pyrrolidone) (Au:PVP), catalyzed
the intramolecular hydroamination of toluenesulfonamides to unactivated alkenes/alkynes in EtOH
under aerobic and basic conditions. The reaction proceeds via anti-addition of toluenesulfonamide to the
Received 5 October 2010
Received in revised form
4 November 2010
alkenes assisted by
p-activation of the gold clusters.
Accepted 9 November 2010
Ó 2010 Elsevier B.V. All rights reserved.
Keywords:
Gold nanocluster
Intramolecular hydroamination
Aerobic conditions
1. Introduction
quite different from those of reactions promoted by other catalysts
such as cationic Au(I) complexes [5], which behave as soft
acids under rather acidic conditions.
p-Lewis
Nanogold catalysis has long been focused only on oxidation
reactions since the first discovery of CO oxidation by Haruta [1]. We
have previously demonstrated that gold nanoclusters stabilized by
a hydrophilic polymer, poly(N-vinyl-2-pyrrolidone) (Au:PVP) [2]
can also behave as formal Lewis acid catalysts. The first example
reaction was the intramolecular hydroalkoxylation of unactivated
alkenes (Eq. (1)) [3]. The reaction was carried out under aerobic and
basic conditions similar to those used in typical aerobic oxidation
reactions [4]. After several experiments using deuterated solvents,
a reaction mechanism was proposed in which aerobic oxidation did
occur and the co-solvent DMF worked as a sacrificial reductant,
donating a hydrogen to give the formal additionproduct (Scheme 1).
It was noteworthy that basic conditions were necessary to improve
the nucleophilic reactivity of the alcohol, which was adsorbed onto
the surface of the cluster. The reaction mechanism for Au:PVP is
Our initial results strongly motivated us to develop an intra-
molecular hydroamination reaction using Au:PVP as an air/
moisture stable catalyst. Hydroamination of carbonecarbon
multiple bonds offers an efficient atom-economical route to
nitrogen containing molecules and is one of the most extensively
studied transformations [6]. In particular, intramolecular reac-
tions provide a useful method for the construction of heterocy-
cles. Among the various types of activating reagents reported for
the hydroamination of unactivated alkenes and alkynes, including
transition metals [7], organolanthanides [8], group IV metals [9],
alkali metals [10] and acids [11], there are still very few mois-
ture-/air-stable catalyst systems [12]. In addition, we have
previously reported that Au:PVP promotes the intramolecular
hydroamination of toluenesulfonamides [13] and primary amines
[14] to unactivated alkenes. As informed from the hydro-
alkoxylation reaction, the right combination of reaction condi-
tions and sacrificial reductant is critical for successful reaction;
for the toluensulfonamides, EtOH was used as a reductant under
basic conditions, while for the primary amines, formic acid
derivatives were used as reductants under slightly acidic
conditions.
OH
Ph
Ph
10 atom% Au:PVP
O
CH3
(1)
Ph
200 mol% DBU, H2O/DMF
50 °C, 16 h, air, 87%
Ph
In this paper, we describe the intramolecular hydroamination
of tolenesulfonamides to substrates with carbonecarbon multiple
bonds including unactivated alkenes and alkynes, along with
some additional results to provide insight into the reaction
mechanism.
* Corresponding author. Research Center for Molecular-Scale Nanoscience,
Institute for Molecular Science, Myodaiji, Okazaki 444-8787, Japan. Fax: þ81 564 59
5527.
E-mail address: hsakurai@ims.ac.jp (H. Sakurai).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.08.038

H. Kitahara, H. Sakurai / Journal of Organometallic Chemistry 696 (2011) 442e449
443
O
δ-
O
Ph
Ph
O
O
δ+
CH3
Ph
O2
Ph
Au
Au
A
HOO
NHMe2
CO2
δ-
O
O
O
Ph
Ph
O
Au
Au
O
H
δ+
OH
O
OH
C
Ph
Me2N
Ph
B
D
HO
O
H2O
Au
O
Ph
Ph
OH
DMF
C
Scheme 1.
2. Results and discussion
Representative results for the hydroamination of toluenesulfo-
namides are summarized in Table 1. The geminal effect at the
-position was investigated. The cyclization proceeded smoothly
2.1. Au:PVP-catalyzed intramolecular hydroamination
b
of toluenesulfonamide to alkenes
in the reactions with methyl -phenyl - (1b), phenyl - (1c), and
dimethyl - (1d) substitutes, affording the corresponding pyrrolidine
derivatives 2b, 2c, and 2d, respectively, in excellent yields (entries
2e4). Hydroamination of 1b and 1c afforded the syn-diastereomer
as a major product. Cyclization even took place using 1e without
the geminal effect, giving pyrrolidine derivatives 2e in moderate
yield after 16 h (entry 5). The reaction of d-methyl-substituted
alkene 1f quantitatively afforded 2f (entry 6). The bicyclic product
2g was also obtained in good yield (entry 7). The substrate with
The first substrate, 1a, was chosen because He and co-workers
have previously reported its reaction with cationic Au(Ι) complexes.
In their case, the cyclized product 2a was afforded in 96% yield
under conditions of 5 mol% PPh3AuCl and AgOTf in toluene at 85 ꢀC
for 17 h (Eq. (2)) [5]. In our case, when 1a was treated with 5 atom%
of Au:PVP and 300 mol% of Cs2CO3 at 50 ꢀC in EtOH as a solvent
under aerobic conditions, 2a was obtained in quantitative yield
after 1 h.
a diphenyl substitute at the
titative cyclization after 1
a
h
-position 1h also underwent quan-
(entry 8). As for the benzylic
Ts
substrates 1i, cyclization did proceed, giving only the endo-methyl
product 2i (entry 9). Au:PVP also catalyzed reactions to afford
six-membered ring derivatives as well as five-membered rings. For
example, piperidine derivative 2j was obtained in quantitative
yield when 1j was treated with 5 atom% of Au:PVP and 300 mol%
of Cs2CO3 at 50 ꢀC for 19 h in EtOH under aerobic conditions
(entry 10).
NHTs
N
5 mol% Ph3PAuCl/AgOTf
CH3
(2)
Ph
Ph
toluene, 85 °C
17 h, 96%
Ph
Ph
1a
2a
However, cyclization did not take place with
g-aminoalkene 1l, which was expected to proceed via three-exo/
four-endo or four-exo/five-endo cyclizations, respectively, even
under higher temperatures and longer reaction times (Eq. (4)). A
Ph-activated alkene 1m with geminal diphenyl groups at the
b-aminoalkene 1k
As previously reported [2e4,13,14], the catalytic activity of
Au:PVP drastically reduces as the cluster size is increased, which
may be a result of the limited ability of molecular oxygen to adsorb
onto the nanocluster surface. In fact, cyclization did not occur under
carefully degassed conditions, or with the use of larger clusters of
Au:PVP (average size: 9.5 nm), which indicates that molecular
oxygen plays an essential role in both the hydroamination and
hydroalkoxylation reactions (Eq. (3)) [3].
or
a
-position also failed to proceed to either the four-exo or five-endo
cyclization products (Eq. (5)).
2.2. Mechanistic insight for intramolecular hydroamination
to alkenes
Ts
NHTs
N
5 atom% Au:PVP
CH3
(3)
Ph
Ph
300 mol% Cs2CO3
EtOH, 50 °C, 1 h
Ph
As stated in the introduction, the presence of the sacrificial
reductant, which plays a role of the hydrogen donor, is indispens-
able to the reaction. In the case of intramolecular hydro-
alkoxylation, a formyl hydrogen of DMF, a co-solvent with H2O, was
found to be the hydrogen source to the terminal position of the
initial alkene as shown in Scheme 1. Experiments were performed
Ph
2a
1a
under air: >99%
under Ar: 0%
9.5 nm Au:PVP / under air: 0%

444
H. Kitahara, H. Sakurai / Journal of Organometallic Chemistry 696 (2011) 442e449
Table 1
Ts
NHTs
CH3
n R3
N
5 atom% Au:PVP
R3
R1
R2
R1
300 mol% Cs2CO3
n
R2
EtOH, 50 °C, air, time
1 (n = 1, 2)
2 (n = 1, 2)
Entry
Alkene
Time/h
Isolated yield/%
Ts
NHTs
R3
CH3
R3
N
R1
R2
R1
1a-f
2a-f
R2
1
2
3
4
5
6
1a R1, R2 ¼ Ph, R3 ¼ H
1b R1 ¼ Ph, R2 ¼ CH3, R3 ¼ H
1c R1 ¼ Ph, R2, R3 ¼ H
1d R1, R2 ¼ CH3, R3 ¼ H
1e R1, R2, R3 ¼ H
1
4
4
16
16
3
2a >99
2b 93(1.9:1)a
2c 89(1.2:1)a
2d 81
2e 41
2f >99
1f R1, R2 ¼ Ph, R3 ¼ CH3
NHTs
NTs
7
8
1
1
2g 87
1g
Ts
NHTs
Ph
Ph
Ph
N
Ph
CH3
1h
2h >99
NHTs
TsN
9
4
2i 95
1i
Ts
N
NHTs
CH3
Ph
Ph
10
19
Ph
Ph
2j >99
1j
a
cis- isomer is major, 1H NMR ratio.
using deuterated solvents as summarized in Table 2. No labeled
product or only a trace amount of labeled product was obtained in
a D2O/(CH3)2NCHO or H2O/(CD3)2NCHO solvent mixture, respec-
tively (entries 2 and 3). In contrast, the labeled product was
obtained effectively in H2O/(CD3)2NCDO and D2O/(CD3)2NCDO
(entries 4 and 5). To determine the source of hydrogen at the
methyl group of the product for the toluenesulfonamide reaction,
1a was treated with 300 mol% Cs2CO3 at 50 ꢀC in CH3CH2OD or
CD3CD2OD (Table 3). Hydroamination proceeded quantitatively in
CH3CH2OD after 6 h; however, 2a-D was not obtained with this
solvent. With CD3CD2OD, 2a-D was obtained in 96% yield (70% D)
after 20 h, which revealed that the hydrogen was introduced from
the ethyl group of EtOH [13]. It should be pointed out that in both
hydroalkoxylation and hydroamination, only 70% of the product
was labeled while 30% of the hydrogen source remained unclear
[15]. Since the hydroalkoxylation reaction took place in 10e20%
yield even in the absence of the hydrogen source (DMAeH2O: 15%,
CH3CNeH2O: 14%, H2O only: 12%), it can be concluded that the PVP
matrix likely offers an alternative hydrogen source.
Twomainpathways are possible in the cyclizationprocess, which
may occur together: amine activation and alkene activation. In one
pathway, a metal amide is formed via amine activation by NeH
oxidative addition, which then allows insertion of the alkene into
the MeN bond (Scheme 2 (a)). These pathways have been proposed

H. Kitahara, H. Sakurai / Journal of Organometallic Chemistry 696 (2011) 442e449
445
5 atom% Au:PVP
no reaction
TsHN
(4)
(5)
n
300 mol% Cs2CO3, EtOH, air
1k (n=1): 50 °C, 43 h then 80 °C, 20 h
1l (n=2): 50 °C, 40 h then 80 °C, 11 h
5 atom% Au:PVP
NHTs
Ph
Ph
Ph
no reaction
300 mol% Cs2CO3
EtOH, 50 °C, air, 6 h
1m
for organolanthanide or group IV complex catalyst systems. In
a variation on this, Bergman and co-workers proposed a [2 þ 2]
cycloaddition mechanism with a metal nitrenoid intermediate in
reactions catalyzed by zirconium bisamide (2,6-Me2C6H3NH)2ZrCp2
(Scheme 2(b)) [9a]. An alternative mechanism involves olefin acti-
vation via a transition metal complex. By this mechanism, nucleo-
philic attack by the amine onto the metal-coordinated olefin,
followed by protonation, affords the hydroamination product
(Scheme 2(c)). Such a mechanism usually requires an electrophilic
metal at the center of the catalyst. Therefore, research has tended to
focus on cationic late transition metal complexes. For example, He’s
cationic Au(Ι) complexes proceeded viathe olefin mechanism, giving
the anti-addition products [5]. It was considered worthwhile to
determine the reaction pathway under Au:PVP-catalyzed condi-
tions because it was expected that the mechanism would be
different from those reported for other catalysts.
NTs
D
D
Ph
Ph
5 atom% Au:PVP
H H
(6)
Ph
300 mol% Cs2CO3,
EtOH, 50 °C, 20 h, 71%
Ph
N
D
Ts
2n
D
1n
A
possible reaction mechanism of intramolecular hydro-
amination is shown in Scheme 4. As previously reported in the
aerobic oxidation of alcohols [4a], the Au cluster is activated by
molecular oxygen adsorption, giving rise to a negative charge on the
oxygen and a cationic site on the gold cluster surface. The adsorption
of alkoxide in basic conditions, followed by b-hydrogen extraction
by a superoxo-like oxygen as a rate-determining step, affords the
corresponding aldehyde with regeneration of the Au cluster. Simi-
larly, the hydroaminationreactionis initiated bytheformation of the
key intermediate A, which possesses an electron-deficient site as
a result of adsorption of O2 onto the surface of the Au nanoclusters. A
then acts as a formal Lewis acid to activate the alkene by adsorption
of the anionic 1 (B). From the adsorbed intermediate, anti-addition
of the amide to alkene proceeds, giving an alkyl-Au intermediate C.
Ethoxide is also adsorbed on the gold surface due to the basic
conditions (D), and subsequent hydrogen abstraction from the ethyl
group of EtOH affords the corresponding cyclized compound 2 along
with regeneration of the free Au nanoclusters.
To elucidate the mechanism of cyclization for hydroamination to
the alkene, we selected a cyclohexene derivative 1k, in which the
remote alkenic and allylic hydrogens are replaced with deuterium.
If the cyclization proceeds by
p-activation followed by anti-addi-
tion of nitrogen, the product should have an anti-configuration
between the N-tosyl and the H (equivalent to a syn-configuration
between the two Hs). On the other hand, if the cyclization proceeds
by formation of a metal-nitrogen bond followed by insertion of
toluenesulfonamide, the product should have a syn-configuration
(Scheme 3). The configuration can be easily determined based on
the 1H NMR coupling constant between the H at the fused position
and the newly installed H. Treatment of substrate 1n with Au:PVP
afforded 2n, which had a vicinal coupling constant of J ¼ 3.2 Hz,
assignable to a syn-configuration (Eq. (6)). This result revealed that
external attack of toluenesulfonamide proceeded from the opposite
side to the Au-coordinated olefin.
2.3. Intramolecular hydroamination to alkynes
Hydroamination of alkynes has been studied using various types
of activating reagents, because alkynes undergo hydroamination
Table 3
Table 2
Ts
NHTs
N
OH
Ph
Ph
Ph
O
CH2D
(H)
5 atom% Au:PVP
10 atom% Au:PVP
CH2D
(H)
Ph
Ph
Ph
200 mol% DBU
300 mol% Cs2CO3,
solvent, 50 °C, time
Ph
solvent, 50 °C, air
Ph
1a
2a
Solvent
Isolated yield/% (%D)a
H2O/(CH3)2NCHO
D2O/(CH3)2NCHO
H2O/(CD3)2NCHO
H2O/(CD3)2NCDO
D2O/(CD3)2NCDO
83
80 (0)
84 (4)
63 (71)
42 (62)
Solvent
Time/h
Isolated yield/ % (%D)a
2a
CH3CH2OD
CD3CD2OD
6
20
>99 (0)
96 (70)
a
a
Calcd by GC/MS.
Calcd by GC/MS.

446
H. Kitahara, H. Sakurai / Journal of Organometallic Chemistry 696 (2011) 442e449
system is expected to be applied to various types of formal Lewis
a) Aminometallation Mechanism
M NR2
acid reactions in addition to oxidation reactions due to its activity
under basic, mild, and atmospheric reaction conditions. The ulti-
mate success in the reaction design depends on in the selection of
reaction conditions and the sacrificial reductant. As described in the
introduction, the optimum reaction conditions and sacrificial
reductant were different for the toluenesulfonamides and primary
amines. In other words, Au:PVP is a tunable and versatile catalyst
for a variety of different substrates.
M
NR2
b) [2+2] Cyclization Mechanism
M NR
M NR
4. Experimental section
c) Coodination/Nucleophilic Addition Mechanism
HNR2
4.1. General
Melting points were determined on a Yanaco MP-J3 and were
uncorrected. Infrared (IR) spectra were recorded on a JASCO FT IR-
4100 spectrometer. 1H and 13C NMR spectra were measured on
a JEOL JMN LAMBDA 400 spectrometer at 23 ꢀC at 400 and
100 MHz, respectively. CDCl3 was used as a solvent and the residual
solvent peaks were used as an internal standard (1H NMR:
7.26 ppm; 13C NMR: 77.00 ppm). Elemental analyses were
measured on a Yanaco CHN corder MT-6. Mass spectra were
measured on a JEOL JMS-777V spectrometer using electron impact
mode (EI). GC/MS data was collected on a Shimadzu GSMS QP-2010
gas chromatography interfaced with mass spectroscopy. Silica gel
chromatography was performed on Kanto 60N, Wako Wakosil C-
300, or Yamazen Hi-Flash column using a Yamazen YFLC purifica-
tion system. TLC analysis was performed using Merck Silica gel 60
F254 and preparative TLC was conducted using Wako gel B-5F. GPC
was performed with Japan Analytical Industry LC-908 using chlo-
roform as a solvent. Other reagents and solvents were purchased
from commercial sources and were further purified by the standard
methods, if necessary. The 1H NMR spectra were recorded on a JEOL
Lambda 400 (400 MHz) spectrometer. Preparation of Au:PVP was
followed by the reported procedure [2].
M
NR2
M
Scheme 2.
more easily than alkenes due to their steric advantage and the
relative weakness of the -bond [6]. Thus, it was expected that the
p
reaction of alkynes would proceed readily. As expected, the cycli-
zation proceeded smoothly in reactions with terminal/internal
alkynes (Table 4). exo-Methylene pyrrolidine derivative 2o was
obtained in quantitative yield when terminal alkyne 1o was treated
with 5 atom% of Au:PVP and 300 mol% of Cs2CO3 at 50 ꢀC for 6 h in
EtOH under aerobic conditions (entry 1). Similarly, the cyclization
proceeded smoothly in reactions with internal alkynes; methyl-
(1p) and p-tolyl- (1q) substituted alkynes afforded the corre-
sponding exo-methylene pyrrolidine derivative 2p and 2q with Z
configuration in 97 and 91% yields, respectively (entries 2 and 3).
The resulting stereochemistry of these reactions was also consis-
tent with catalysis by Au:PVP via an
p-activation/anti-addition
mechanism. A trimethylsilyl substituted alkyne 1r underwent
successful cyclization followed by desilylation, giving the exo-
methylene pyrrolidine derivative 2o in quantitative yield (entry 4).
4.2. General procedure of Au:PVP-catalyzed intramolecular
3. Summary
hydroamination of toluenesulfonamide
In summary, we have demonstrated the catalysis by Au:PVP in
the intramolecular hydroamination of toluenesulfonamide to
unactivated alkenes as well as alkynes in basic EtOH media under
aerobic conditions. The reaction proceeds via anti-addition of the
All the reaction was carried out using an organic synthesizer
EYELA PPS-2510. A test tube (
4
¼ 30 mm) was placed 1 (0.1 mmol),
Cs2CO3 (97.7 mg, 0.30 mmol), and dried Au:PVP (38.1 mg ¼ 5 atom
%). EtOH (30 mL) was added and the reaction mixture was stirred
vigorously (1300 rpm) at 50 ꢀC for the time specified. The reaction
toluenesulfonamide followed by p-activation. The Au:PVP catalyst
Scheme 3.

H. Kitahara, H. Sakurai / Journal of Organometallic Chemistry 696 (2011) 442e449
447
-
2
Ts
N
CO3
NTs
CH3
δ-
O
O
δ+
1
Ph
O2
Ph
2
Ph
Ph
Au
Au
HCO3
A
HOO
Ts
N
δ-
CH3CHO
O
O
NTs
Au
O
Au
δ+
O
OH
H
Ph
Ph
C
Ph
Ph
CH3
B
H
D
OH
O
HCO3
Au
Ts
N
-
2
CO3
EtO
Ph
Ph
C
Scheme 4. Possible mechanism of intramolecular hydroamination.
mixture was extracted with ethyl acetate (3 ꢁ 20 ml), and then the
combined organic layers were washed with water and brine, dried
over Na2SO4, and concentrated in vacuo. Purification of the prod-
ucts was carried out by PTLC.
4.3.4. 1q
White solid; mp 161e162 ꢀC; IR (KBr) 3261, 3027, 2920, 1509,
1328, 1163, 1080, 673 cmꢂ1; 1H NMR (CDCl3):
(s, 3H), 3.16 (s, 2H), 3.77 (d, J ¼ 6.7 Hz, 2H), 4.06 (t, J ¼ 6.7 Hz, 1H),
7.02e7.08 (m, 4H), 7.14e7.16 (m, 4H), 7.21e7.31 (m, 8H), 7.66 (d,
J ¼ 8.3 Hz, 2H); 13C NMR: 143.78, 143.44, 137.77, 136.21, 131.31,
129.69, 128.81, 128.38, 127.78, 127.20, 127.00, 120.27, 85.25, 84.34,
50.15, 49.97, 29.24, 21.49, 21.40 ppm; HRMS m/z Calcd for
C31H29NO2S: 479.1919. Found: 479.1914.
d
¼ 2.32 (s, 3H), 2.37
4.3. Compounds data
4.3.1. 1j
White solid; mp 128e129 ꢀC; IR (KBr) 3276, 3063, 2952, 2932,
1599, 1424, 1168, 1071, 701 cmꢂ1
;
1H NMR (CDCl3):
d
¼ 1.61e1.67
(m, 2H), 2.16e2.20 (m, 2H), 2.42 (s, 3H), 3.56 (d, J ¼ 6.4 Hz, 2H), 3.83
(t, J ¼ 6.4 Hz, 1H), 4.84e4.90 (m, 2H), 5.65 (dddd, J ¼ 18.2, 10.0, 7.4,
6.6 Hz, 1H), 7.05 (m, 4H), 7.19e7.28 (m, 8H), 7.61 (d, J ¼ 8.0, 2H); 13C
NMR: 144.76, 143.44, 138.19, 136.30, 129.72, 128.43, 127.71, 127.08,
126.68, 114.56, 49.60, 49.37, 35.88, 28.23, 21.51 ppm; HRMS m/z
Calcd for C25H27NO2S: 405.1762. Found: 405.1756.
4.3.5. 1r
White solid; mp 122e123 ꢀC; IR (KBr) 2957, 2172, 1330, 1164,
841, 700 cmꢂ1; 1H NMR (CDCl3):
d
¼ 0.02 (s, 9H), 2.43 (s, 3H), 2.98
(s, 2H), 3.71 (d, J ¼ 6.6 Hz, 2H), 4.11 (t, J ¼ 6.6 Hz, 1H), 7.09e7.11 (m,
4H), 7.21e7.30 (m, 8H), 7.66 (d, J ¼ 8.3 Hz, 2H); 13C NMR: 143.83,
143.69, 136.64, 129.96, 128.52, 128.07, 127.40, 127.21, 103.43, 89.38,
50.50, 50.00, 30.11, 21.78, 0.00 ppm; HRMS m/z Calcd for
C27H31NO2SSi: 461.1845. Found: 461.1833.
4.3.2. 1o
White solid; mp 112e114 ꢀC; IR (KBr) 3269, 3060, 1330, 1164,
1087, 698 cmꢂ1; 1H NMR (CDCl3):
d
¼ 1.85 (t, J ¼ 2.5 Hz, 2H), 2.43
4.3.6. 2j
(s, 3H), 3.02 (d, J ¼ 2.5 Hz, 2H), 3.72 (d, J ¼ 6.7 Hz, 2H), 4.03 (t,
J ¼ 6.7 Hz, 1H) 7.09e7.11 (m, 4H), 7.22e7.30 (m, 8H), 7.66 (d,
J ¼ 8.0 Hz, 2H); 13C NMR: 143.48, 143.39, 136.25, 129.69, 128.39,
127.67, 127.17, 127.05, 80.21, 72.15, 50.08, 49.44, 28.28,
21.51 ppm; HRMS m/z Calcd for C24H23NO2S: 389.1449. Found:
389.1451.
Colorless oil; IR (neat) 3060, 1447, 1337, 1158, 1091, 666 cmꢂ1; 1H
NMR (CDCl3):
d
¼ 1.00 (d, J ¼ 6.8 Hz, 3H), 1.44 (dddd, J ¼ 15.0, 3.49,
3.0, 3.0 Hz, 1H), 1.78 (dddd, J ¼ 16.2, 15.0, 9.5, 5.7 Hz, 1H), 2.38e2.39
(m, 2H), 2.40 (s, 3H), 3.20 (d, J ¼ 13.0, Hz, 1H), 4.09 (ddq, J ¼ 6.8, 5.7,
3.5 Hz, 1H), 4.56 (d, J ¼ 13.0 Hz, 1H), 7.16e7.30 (m, 10H), 7.46 (d,
J ¼ 8.2 Hz, 2H), 7.61 (d, J ¼ 8.2 Hz, 2H); 13C NMR: 147.37, 143.93,
143.09, 137.15, 129.54, 128.43, 128.30, 128.03, 127.51, 126.54, 126.40,
125.89, 48.25, 48.12, 46.90, 28.82, 27.71, 21.45, 13.82 ppm; HRMS
m/z Calcd for C25H27NO2S: 405.1762. Found: 405.1757.
4.3.3. 1p
White solid; mp142e143 ꢀC; IR(KBr)3273, 2915,1495,1414,1327,
1169,1159, 669 cmꢂ1; 1HNMR(CDCl3):
d
¼ 1.61 (t, J ¼ 2.5Hz, 3H), 2.44
(s, 3H), 2.93 (q, J ¼ 2.5Hz, 2H), 3.71 (d, J ¼ 6.6 Hz, 2H), 4.11 (t, J ¼ 6.6 Hz
1H), 7.10e7.13 (m, 4H), 7.7.23e7.31 (m, 8H), 7.68 (d, J ¼ 8.3 Hz, 2H);
13C NMR: 143.97、143.39, 136.25, 129.61, 128.30, 127.69, 127.23,
126.86, 79.57, 74.92, 50.05, 49.56, 28.65, 21.52, 3.42 ppm; HRMS m/z
Calcd for C25H25NO2S: 403.1606. Found: 403.1604.
4.3.7. 2n
1H NMR (CDCl3):
d
¼ 1.11e1.28 (m, 1H), 1.43e1.64 (m, 6H), 2.41
(s, 3H), 3.75 (d, J ¼ 3.2 Hz, 1H), 4.23 (d, J ¼ 11.0 Hz, 1H), 4.48 (d,
J ¼ 11.0 Hz, 1H), 6.97e7.11 (m, 10H), 7.18 (d, J ¼ 8.1 Hz, 2H), 7.41 (d,
J ¼ 8.1 Hz, 2H).

448
H. Kitahara, H. Sakurai / Journal of Organometallic Chemistry 696 (2011) 442e449
Table 4
Au:PVP-catalyzed hydroamination of toluenesulfonamide to alkynes.
R
Ts
N
NHTs
R
5 atom% Au:PVP
H
Ph
Ph
300 mol% Cs2CO3
EtOH, 50 °C, air
Ph
Ph
Entry
1
Alkyne
Time/h
Isolated yield/%
Ts
N
1o R ¼ H
6
2o >99%
2p 97%
Ph
Ph
Ph
CH3
H
Ts
N
2
1p R ¼ CH3
1
Ph
CH3
Ts
N
3
1q R ¼ p-tol
9
2q 91%
H
Ph
Ph
Ph
Ts
N
4
1r R ¼ Si(CH3)3
3
2o >99%
Ph
4.3.8. 2o
53.40, 51.17, 45.98, 21.53, 21.32 ppm; HRMS m/z Calcd for
C31H29NO2S: 479.1919. Found: 479.1922.
Pale yellow solid; mp 87e88 ꢀC; IR (KBr) 3028, 1643, 1342,
1169 cmꢂ1
;
1H NMR (CDCl3):
d
¼ 2.43 (s, 3H), 3.10 (s, 2H), 4.32 (s,
2H), 4.42 (s,1H), 5.12 (s, 1H), 7.19e7.30 (m,12H), 7.67 (d, J ¼ 8.1, 2H);
13C NMR: 144.59, 143.85, 142.97, 134.34, 129.42, 128.48, 127.23,
126.65, 90.74, 67.04, 60.95, 49.73, 45.07, 21.51 ppm; HRMS m/z
Calcd for C24H23NO2S: 389.1449. Found: 389.1447.
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Pale yellow solid; mp 72e73 ꢀC; IR (KBr) 2918, 1495, 1446, 1354,
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d
¼ 1.90 (d, J ¼ 7.1 Hz, 3H), 2.33 (s, 2H)
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H. Kitahara, H. Sakurai / Journal of Organometallic Chemistry 696 (2011) 442e449
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