Efficient addition of alcohols, amines and phenol to unactivated alkenes by AuIII or PdII stabilized by CuCl2

Article abstract of DOI:10.1039/b714617e

The nucleophilic addition of alcohols, amines and phenol to unactivated alkenes catalyzed by cationic gold and palladium becomes limited due to the fast reduction into metallic gold under reaction conditions. The presence of CuCl₂ retards the reduction of Au^III and Pd^II, strongly increasing the turnover number of gold and palladium catalysts. It is shown that new Au^III-CuCl₂ and Pd^II-CuCl ₂ catalysts are active and selective for the nucleophilic addition of alcohols, amines and phenol to unactivated alkenes. This journal is The Royal Society of Chemistry.

Full text of DOI:10.1039/b714617e

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Efficient addition of alcohols, amines and phenol to unactivated alkenes by
AuIII or PdII stabilized by CuCl2†
Xin Zhang and Avelino Corma*
Received 21st September 2007, Accepted 19th November 2007
First published as an Advance Article on the web 12th December 2007
DOI: 10.1039/b714617e
The nucleophilic addition of alcohols, amines and phenol to unactivated alkenes catalyzed by cationic
gold and palladium becomes limited due to the fast reduction into metallic gold under reaction
conditions. The presence of CuCl2 retards the reduction of AuIII and PdII, strongly increasing the
turnover number of gold and palladium catalysts. It is shown that new AuIII–CuCl2 and PdII–CuCl2
catalysts are active and selective for the nucleophilic addition of alcohols, amines and phenol to
unactivated alkenes.
temperatures requires the use of very reactive substrates. This is
probably a reason why most reports on cationic gold catalysis are
limited to activation of alkynes and allenes1,2 Teles et al.5b found
Introduction
Interest in the catalytic chemistry of gold has undergone a marked
increase in recent years.1 Cationic gold (AuI and AuIII) salts
that by using gold(I) complexes in the presence of a strong acid
as cocatalyst, instead of using AuIII (Na[AuCl4]), the efficiency
of gold(I) catalyst was greatly improved. Mizushima et al.6 found
that the efficiency of the AuI catalyst was significantly enhanced by
addition of large amounts of appropriate ligands (e.g., (PhO)3P),
which improved the stability of the catalyst.
Activation of alkenes catalyzed by cationic gold remains one
of the most significant challenges and is regarded as the gate
to catalytic asymmetric synthesis in homogenous gold catalysis.1
Recently, Yao and Li4a reported that AuIII catalyzes the addition
of b-diketone to alkenes with AgI as co-catalyst. An interesting
AuI-mediated addition of phenols, carboxylic acids, and amines
to alkenes was also shown.4b,4c However in most cases the stability
of the catalyst is a major issue.
and organic complexes have emerged as powerful homogeneous
and heterogeneous catalysts for the activation of C–C multiple
bonds.1–3 The major virtue of gold salts in homogenous catalysis
is their unique ability to activate C–C multiple bonds as soft,
carbophilic Lewis acids, allowing for the formation of new
C–C, C–O, C–N, and C–S bonds by nucleophilic attack at
these activated substrates. While there are many reports1,2 about
the activation of alkynes and allenes, activation of less active
substrates, e.g., alkenes, by cationic gold salts have remained
relatively unexplored.4 It is also important to consider that cationic
gold salts and organic complexes are easily reduced by alkynes,
alkenes, alcohols, CO, and phosphines, present in the reaction
medium.1,5 In fact, even the addition of water and methanol
to alkyne catalyzed by AuIII catalysts (Na[AuCl4]), which has
become a kind of benchmark for gold catalysts,1c,5c presents
the serious drawback of the reduction of gold(III) into inactive
metallic gold under the reaction conditions. In this sense Fukuda
and his coworkers5d–f found that gold(III)-catalyzed (AuCl3 and
Na[AuCl4]) hydroamination of alkynylamines required to work at
high dilution levels to prevent catalyst decomposition into metallic
gold, and furthermore their system was not effective for the
hydroamination of arylacetylenes. Mizushima et al.6 discovered
that the low activity for gold(I) [(Ph3P)AuCH3] catalyzed hydration
of alkynes was due to the decomposition of the catalyst to metallic
particles. Therefore the reduction of cationic gold species to
metallic gold often results in deactivation of cationic gold salts,
which unambiguously weaken their utilization.
In the present work we will show that AuIII as well as PdII when
used in combination with CuCl2 are able to catalyze efficiently
the nucleophilic addition of alcohols, amines and phenol to
unactivated alkenes. The stabilizing role of CuCl2 for cationic gold
species is investigated.
Results and discussion
The role of CuCl2 on stabilizing AuIII active species during reaction
conditions: addition of methanol to styrene
Fukuda and Utimoto5c first reported on the nucleophilic addition
of alcohols and water to alkynes by means of AuIII catalyst
(Na[AuCl4]) under refluxing conditions. However, the catalyst was
soon deactivated under the reaction conditions due to formation
of metallic gold particles. Teles et al.5b overcame the drawback
by using cationic gold(I) complexes (phosphane/phosphite–Au+)
to replace Na[AuCl4] and found the cationic gold(I) to be highly
active for addition of alcohols to alkynes at 20–50 ◦C using strong
acid (CH3SO3H) as the co-catalyst. Nevertheless, the authors
reported that alkenes did not react.1c Based on this, we thought that
since alkenes are much less reactive than alkynes, the addition of
alcohols (e.g., methanol) to alkenes (e.g., styrene) could be carried
Efforts to enhance the use of cationic gold catalysts have
long been sought. The simple methodology involves employing
the cationic gold under very mild reaction conditions (e.g.,
room temperature), however the low activity at low reaction
Instituto de Tecnolog´ıa Qu´ımica, UPV-CSIC, Universidad Polite´cnica de
Valencia, Avda. de los Naranjos s/n, 46022, Valencia, (Spain). E-mail:
acorma@itq.upv.es; Fax: (+34) 96-387-7809
† Electronic supplementary information (ESI) available: GC-MS and 1H-
NMR Analysis: MS and 1H-NMR spectra data of products. See DOI:
10.1039/b714617e
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out at higher temperatures provided that the rapid reduction of
AuIII could be avoided or, at least, slow down.
Addition of methanol to styrene catalyzed by the gold(III) salts
occurred at 120 ◦C, giving main products of 1-methoxyethyl-
benzene and 2,2-dimethoxyethylbenzene (Scheme 1).4d Fig. 1 com-
pares styrene conversion and 1-methoxyethylbenzene selectivity
over cationic gold (AuIII, AuI), and PdII. The maximum styrene
conversion obtained was 46, 38, 23, 5, and 29% on HAuCl4, AuCl3,
Na[AuCl4], AuCl, and PdCl2 catalysts, respectively (Fig. 1a). It is
evident that cationic gold(III) salts (e.g., HAuCl4, AuCl3) show
much higher activity than AuCl, or PdCl2. The selectivity to
the adduct (1-methoxyethylbenzene) was in the range of 70–
80% with all cationic gold catalysts, while some lower selectivity
(62%) was found with PdCl2 (Fig. 1b), and 18–35% of 2,2-
dimethoxyethylbenzene was also found with all cationic gold and
palladium catalysts.
Scheme 2 Formation of palladium(II) alkene p-complexes (a) and
gold(III) alkene p-complexes (b) and then converted to acetals by redox
decomposition.
because catalyst deactivation is due to the reduction of cationic
gold (AuIII, AuI) and PdII to metallic Au0 and Pd0, respectively.
At this point, we thought that the great success of the Wacker
process8 relies on its ingenious catalytic cycle, in which the reduced
Pd0 is reoxidized in situ to PdII by CuCl2 which is reduced to
CuCl. In turn, CuCl is easily reoxidized to CuCl2 with oxygen.
Although in a first approximation it appears difficult that the
oxidation of Au0 and Pd0 can be carried out by CuCl2, taking
into account the redox potentials,8a,9 it should be considered that
cationic gold(III) and palladium(II) species can be easily stabilized
by complex formation in the presence of chloride ions,1,6,8a and
the initially reduced AuI and metallic Au nanoparticles should
have lower redox potential.10 Then, the effect of adding CuCl2
on styrene conversion and 1-methoxyethylbenzene selectivity was
studied and the results were shown in Fig. 2 and 3, respectively.
After addition of 8, 16, and 32 mol% of CuCl2 to AuCl3, the
styrene conversion increased from 38 to 62, 82, and 89% (Fig. 2A);
and the conversion also significantly increased from 29 to 55, 87
and 93% in the case of PdCl2 (Fig. 3A). It should be noted that
styrene conversion is only about 1 and 15% with 8 and 16 mol% of
CuCl2 alone at 2 and 5.7 h, respectively (Fig. 2A). The greatly
enhanced activity of both AuCl3 and PdCl2 after addition of
CuCl2 demonstrated that the key role of CuCl2 is to stabilize
AuIII and PdII species. In comparison with the products of the
reaction catalyzed by only AuCl3 and/or PdCl2, the addition of
CuCl2 also results in significant increase of 1-methoxyethylbenzene
selectivity (Fig. 2B and Fig. 3B), with a sharp decrease of 2,2-
dimethoxyethylbenzene. The result indicated that the formation
of acetal and Au/Pd metal by redox decomposition of gold(III)
and/or palladium(II) complexes8 (Scheme 2) was greatly retarded
after addition of CuCl2. Nevertheless a further increase in the
amount of CuCl2 from 16 to 32 mol% can not improve the
selectivity to 1-methoxyethylbenzene, since the formation of 1,2-
dichloroethylbenzene by chlorination of styrene also increased.
Scheme 1 Addition of methanol to styrene on AuIII salts.
The major adduct (1-methoxyethylbenzene) was achieved by
nucleophilic addition of one molecule of methanol to styrene
which was activated by cationic gold and/or palladium. Fukuda
and Utimoto5c reported that the direct formation of dimethyl
acetals (e.g., 2,2-dimethoxyethylbenzene) were achieved from
alkynes by addition of two moles of methanol mediated by AuIII
catalyst (e.g., Na[AuCl4]). However, the direct formation of acetal
from alkenes and alcohols on cationic gold catalyst was not
reported, to the best of our knowledge. Taking into account that
palladium(II) complex (p-C2H4·PdCl2) is facially formed when
refluxing an aqueous solution of PdCl2, alkene, and alcohols,
and that palladium(II) alkene p-complexes have been reported7
to undergo redox decomposition in alcohol solutions to give
acetals and Pd metal (Scheme 2a). We thought that AuIII by being
“isoelectronic” with PdII should follow, a similar reaction scheme
(Scheme 2b).
Indeed, as shown in Fig. 1A the maximum conversion at
120 ◦C is obtained within 2 h on all cationic gold and palladium
catalysts, while the formation of gold and palladium metals was
evident. The result indicated that the reaction stops after ∼2 h
Fig. 1 Styrene conversion (A) and 1-methoxyethylbenzene selectivity (B) over 8 mol% of: (᭺) AuCl3, (ꢀ) HAuCl4, (ꢁ) NaAuCl4, (᭛) AuCl, and (ꢀ)
PdCl2 catalysts.
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Fig. 2 Effect of CuCl2 amount on styrene conversion (A) and 1-methoxyethylbenzene selectivity (B) over: (᭛) 8 mol% CuCl2, (᭜) 16 mol% CuCl2, (ꢀ)
8 mol% AuCl3, (ꢂ) 8 mol% AuCl3–8 mol% CuCl2, (᭺) 8 mol% AuCl3–16 mol% CuCl2, and (ꢁ) 8 mol% AuCl3–32 mol% CuCl2 catalysts.
Fig. 3 Effect of CuCl2 amount on styrene conversion (A) and 1-methoxyethylbenzene selectivity (B) over (ꢂ) 8 mol% PdCl2, (᭜) 8 mol% PdCl2–8 mol%
CuCl2, (᭺) 8 mol% PdCl2–16 mol% CuCl2, and (ꢁ) 8 mol% PdCl2–32 mol% CuCl2 catalysts.
The stabilizing effect was proven through the observation that
AuCl3 (0.1 mmol) in 1.0 mL of methanol at 120 ◦C starts to
form metallic particles after 2 min, while in the presence of CuCl2
(0.2 mmol), no metallic particles were observed after 1 h. The same
occurs in the case of PdCl2.
It is expected that the stabilizing role of CuCl2 will be lost when
CuCl2 is reduced to CuCl. Indeed a green-tinged white precipitate
formed due to the reduction of CuCl2 to CuCl was observed
when the catalytic activity stopped. However, since as mentioned
earlier, the reduced CuCl is reoxidized to CuCl2 with oxygen in
the Wacker process,8 we have studied the effect of the reaction
atmosphere (N2, air, O2) on the catalytic performance of AuCl3–
CuCl2 and PdCl2–CuCl2 (Fig. 4, and 5 respectively). In agreement
with the hypothesis, the styrene conversion over PdCl2 increased
from 80, 87 to 98% when the reaction atmosphere was changed
from N2, air, to oxygen, respectively (Fig. 5A). This result shows
that introduction of O2 significantly improves the activity of PdCl2.
On the contrary, the reaction under O2 led to a distinct decrease in
the catalytic activity of AuCl3 compared with N2 and air (Fig. 4A).
And the 1-methoxyethylbenzene selectivity also sharply decreased
(Fig. 4B). The different catalytic result between AuCl3 and PdCl2
under O2 is due to their different stability to air (and/or O2). It is
Fig. 4 Styrene conversion (A) and 1-methoxyethylbenzene selectivity (B) over 8 mol% AuCl3–16 mol% CuCl2 catalyst under different reaction
atmospheres: (ꢀ) N2; (ꢀ) air; (᭜) O2.
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Fig. 5 Styrene conversion (A) and 1-methoxyethylbenzene selectivity (B) over 8 mol% PdCl2–16 mol% CuCl2 catalyst under different reaction
atmospheres: (ꢀ) N2; (ꢀ) air; (᭜) O2.
well known that PdCl2 are air stable, while the gold salts are air
sensitive, and this matter is now under investigation.
The effect of chloride ions on the catalytic performance has
also been considered, due to the stabilizing effect by complex
formation with cationic gold(III) and palladium(II).1,6,8a However,
the catalytic activity of AuCl3 was not improved after introduction
of 0.16 mmol NaCl. The result indicates the importance of CuII
on stabilizing the AuIII.
The simple methodology by addition of CuCl2 which retards
the reduction of the gold salt and/or oxidizes it back to gold(III)
will unambiguously enhance the utilization of cationic gold salts
to activate alkenes. The following are three examples in such a
direction.
ceuticals, agrochemicals, cosmetics, and important intermediates
for a number of industrial processes.11 Therefore, the catalytic
addition of N–H to a C–C multiple bond (hydroamination)
has received considerable attention.11,12 It was reported5c,d that
the AuIII salts (Na[AuCl4] and AuCl3) catalyze intramolecular
hydroamination of 5-alkynylamines to form tetrahydropyridine
derivatives. Unfortunately, AuIII salts catalyzed hydroamination
of alkynylamines requires high dilution to prevent catalyst
decomposition and was not effective for the hydroamination
of acrylacetylenes.5e Recently, an interesting gold(I)-catalyzed
(Ph3PAuOTf) hydroamination of alkenes,4c and 1,3-dienes13 was
shown using p-toluenesulfonamide, and benzyl carbamate as the
main nucleophiles, respectively.
We find that as shown in Table 2 the direct nucleophilic addition
of aniline to styrene can be realized at 150 ◦C on 8 mol% of
AuCl3, Na[AuCl4], and HAuCl4 catalysts after addition of 16 mol%
of CuCl2, giving up to 60–70% yield of phenyl-(1-phenyl-ethyl)-
amine (entries 2–4, Table 2). The electron rich styrene substrate
(e.g., 4-methylstyene) gives a higher yield (88%, entry 4, Table 2).
Remarkably, less than 21% yields of phenyl-(1-phenylethyl)-amine
was found solely on AuCl3 (entry 1, Table 2). These results demon-
strate that the efficiency of cationic gold(III) for hydroamination
of alkenes has greatly improved after addition of CuCl2. Luo
et al.14 recently reported 88% yield of phenyl-(1-phenylethyl)-
amine obtained by two steps in a sequential hydroamination–
reduction of phenylacetylene with aniline using AuCl3 and NaBH4
at room temperature. We have seen that although AuCl3 gives only
32% yield of 4-methyl-N-(1-phenylethyl)-benzenesulfonamide for
hydroamination of p-toluenesulfonamide with styrene (entry 6,
Table 2) the yield was significantly increased (ca. 60%) with the
AuIII–CuCl2 catalysts (entries 7–9, Table 2). A higher yield (71%)
was also obtained when the addition of benzyl carbamate to 1-
methyl-1-cyclohexene was carried out on 8 mol% AuCl3–16 mol%
CuCl2 instead of solely AuCl3 (35% yield) (entries 10, 11, Table 2).
It should be pointed that less than 8% yield was found with solely
CuCl2 under the same reaction conditions. Clearly, the presence
of CuCl2 also stabilizes cationic gold(III) during the nucleophilic
addition of amines to alkenes.
Addition of alcohols to alkenes
The nucleophilic addition of various alcohols to alkenes over
AuIII–CuCl2 was shown in Table 1. Addition of 16 mol% of CuCl2
into 8 mol% of AuCl3, Na[AuCl4], HAuCl4, sharply increased
styrene conversion from 38, 23 and 46% to 82, 65 and 88%,
respectively. The 1-methoxyethylbenzene selectivity also increased
from 80, 65, 75% to 85, 86, 83%, respectively (Fig. 1, and
entries 1–3, Table 1). We find that the primary alcohols (such as
ethanol, 1-propanol, and 1-butanol) work successfully on 8 mol%
AuCl3–16 mol% CuCl2 and give yields up to 80% (entries 4, 5,
7, Table 1). The secondary alcohols (such as 2-propanol and
2-butanol) react more slowly than primary alcohols and give
yields of up to 60% (entries 6, 8, Table 1), while the tertiary
alcohol (e.g., tert-butyl alcohol) failed in this reaction due to
steric inhibition (entry 9, Table 1).5b Interestingly, addition of
ethylene glycol is also effective, and gives 88% styrene conversion
and 71% yield to 2-(1-phenylethoxy)ethanol (entry 10, Table 1).
Both electron-rich and electron-deficient styrene derivatives serve
as good substrates (entries 11, 12, Table 1). The alcohols can also
be added to the straight-chain and cyclo-alkenes, but a higher
reaction temperature (150 ◦C) is needed (entry 14, Table 1). It
has to be remarked that all the products are formed following
Markovnikov’s rule.
Addition of amines to alkenes
Addition of phenol to alkenes
Acyclic amines are an important class of compounds widely
present in nature and they are common components of pharma-
Nucleophilic addition of phenols to unsaturated carbon–carbon
bonds provides one of the simplest methods to construct valuable
400 | Dalton Trans., 2008, 397–403
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Table 1 Nucleophilic addition of alcohols to alkenes over AuIII–CuCl2 catalystsa
Entry
1
Alkene
Alcohol
t/h
3.5
Conv. (%)
82
Product (sel.) (%)
(85)
Yieldb(%)
1a
Methanol
70
56
73
2c
3d
1a
1a
Methanol
Methanol
3.5
3.5
65
88
(86)
(83)
(86)
4
5
1a
1a
Ethanol
4.0
4.0
93
95
80
80
1-Propanol
(84)
6
7
1a
1a
2-Propanol
1-Butanol
4.0
4.0
67
95
(74)
50e
83
(87)
8
1a
2-Butanol
4.0
69
(84)
58e
9
10
1a
1a
tert-Butyl alcohol
4.0
5.7
3
88
—
—
71
Glycol
(81)
(86)
11
12
2a
Methanol
Methanol
2.5
8.0
93
75
80
59
3a
(79)
13
4a
Methanol
Methanol
12
60
52
(93)
56
35
14f
5a
12
(68)
a Without specified, reactions were performed on 8 mol% AuCl3–16 mol% CuCl2 at 120 ◦C. b GC yield. c 8 mol% Na[AuCl4]–16 mol% CuCl2. d 8 mol%
HAuCl4–16 mol% CuCl2. e Mixture of distereoisomers. f Reaction temperature: 150 ◦C.
synthetic building blocks.15 The use of metal-based catalysts is
promising for enantioselective additions. Recently, Yang and He4b
Conclusion
attempted the gold(I)-catalyzed (Ph3PAuCl/AgOTf) intermolec-
ular addition of phenols to alkenes at 85 ◦C, and claimed that
5 mol% AuCl3–15 mol% AgOTf failed to give the desired product
(yield < 5%).
We have comparatively investigated the role of CuCl2 for AuCl3,
PdCl2 catalyzed addition of methanol to styrene. The results show
that the catalytic performance of gold(III) and palladium(II) has
greatly improved after addition of small amounts of CuCl2, which
can retard reduction of the gold(III) and/or oxidizes it back to
gold(III). This is even more notorious in the case of the PdCl2–
CuCl2 system where the presence of air in the reaction system
improves the process, as it occurs within the Wacker process.
The AuIII–CuCl2 catalysts presented allow nucleophilic addition of
alcohols, amines, and phenol to simple unactivated alkenes. Good
to excellent yields were obtained in most cases and unambiguously
demonstrated that CuCl2 stabilizes cationic gold(III) and Pd(II)
and should also allow the expansion of the use of gold salts to
other reactions in which the cationic gold becomes reduced, and
therefore deactivated, under reaction conditions.
We found that 40% yield of 1-methoxy-4-(1-phenyl-ethoxy)-
benzene can be obtained on 8 mol% AuCl3 at 120 ◦C using toluene
as solvent (entry 1, Table 3). However, after addition of 16 mol%
CuCl2, the yields were sharply increased to 63%, and 80% on
8 mol% of AuCl3, and HAuCl4, respectively (entry 2, 3, Table 3).
Using 4-methylstyrene as a substrate gave excellent yields (85–
93%) on 8 mol% of AuCl3, HAuCl4, or Na[AuCl4] together with
16 mol% of CuCl2 (entry 4–6, Table 3). It should be remarked
that the reaction works almost exclusively with styrene derivatives
and the attempt to react 1-methyl-1-cyclohexene failed to give the
desired product (entry 7, Table 3).
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Table 2 Nucleophilic addition of amines to alkenes over AuIII–CuCl2 catalystsa
Entry
1c
Alkene
Nucleophile
t/h
Product
Yieldb (%)
1a
1b
12
1c
<21
2
1a
1a
1a
2a
1b
1b
1b
1b
12
12
12
8
1c
1c
1c
67
59
73
88
3d
4e
5
2c
6c
1a
2b
12
3c
32
7
8
1a
2a
2b
2b
12
12
3c
57
59
4c
9
10c
11
4a
4a
2b
3b
3b
12
12
12
5c
6c
61
35
71
4a
6c
◦
a Reactions were carried out at 150 C with toluene (1.5 mL) as solvent using 8 mol% AuCl3–16 mol% CuCl2 as catalyst (if not specified). b GC yield,
entries 1–8 contain mixtures of distereoisomers. c Using 8 mol% AuCl3 as catalyst. d Using 8 mol% Na[AuCl4]–16 mol% CuCl2 as catalyst. e Using 8 mol%
HAuCl4–16 mol% CuCl2 as catalyst.
Table 3 Nucleophilic addition of phenol to alkenes over AuIII–CuCl2 catalystsa
Entry
1c
Alkenes
Nucleophile
t/h
Product
Yieldb (%)
40
1a
4b
7
7c
2
1a
1a
2a
4b
4b
4b
7
12
7
7c
7c
63
80
90
3d
4
8c
5d
6e
7
2a
2a
4a
4b
4b
4b
12
12
12
8c
8c
—
93
85
—
◦
a Reactions were carried out at 120 C with toluene (1.5 mL) as solvent using 8 mol% AuCl3–16 mol% CuCl2 as catalyst (if not specified). b GC yield.
c Using 8 mol% AuCl3 as catalyst. d Using 8 mol% HAuCl4–16 mol% CuCl2 as catalyst. e Using 8 mol% Na[AuCl4]–16 mol% CuCl2 as catalyst.
Merck), ethanol (C2H5OH, 99.9%, Scharlau), 1-propanol
(C3H7OH, 99.5+%, Aldrich), 2-propanol (CH3(CH)OHCH3,
Experimental
99.9%, Scharlau), 1-butanol (C4H9OH, 99.4+%, Sigma-
Aldrich), 2-butanol (CH3CH2(CH)OHCH3, 99%, Aldrich),
tert-butyl alcohol ((CH3)3C(OH), 99+%, Aldrich), ethylene glycol
(CH2(OH)CH2(OH), 99+%, Aldrich), styrene (C6H5CHCH2,
99+%, Aldrich), 4-methylstyrene (CH3C6H4CHCH2, 96%,
Aldrich), 4-chlorostyrene (ClC6H4CHCH2, 97%, Aldrich), 1-
methyl-1-cyclohexene (C6H9CH3, 97%, Aldrich), 1-octene (C8H16,
97%, Acros), aniline (C6H5NH2, 99%, Aldrich), p-toluene-
sulfonamide (C7H9NO2S, 99+%, Aldrich), benzyl carbamate
Materials
Commercially available reagents including gold(III) chloride
(AuCl3, 99%), hydrogen tetrachloroaurate(III) trihydrate (HAuCl4·
3H2O, 99.9+%), sodium tetrachloroaurate(III) dihydrate (Na-
[AuCl4]·2H2O, 99%), gold(I) chloride (AuCl, 99.9+%),
palladium(II) chloride (PdCl2, 99.9%) were purchased from Sigma-
Aldrich and used as received. Copper(II) chloride dehydrate
(CuCl2·2H2O, 98%, Panreac), methanol (CH3OH, 99.9+%,
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(NH2COOCH2C6H5, 99%, Aldrich), 4-methoxyphenol (CH3OC6-
H4OH, 99%, Aldrich), and toluene (C6H5CH3, 97+%, Aldrich)
were used as received without further purification.
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Reaction Test: Nucleophilic addition of alcohols, amines, and
phenol to alkenes were performed in a closed glass reactor (2.0 mL,
2 For selected recent examples, see: (a) A. S. K. Hashmi, J. P. Weyrauch,
R
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(20 lL) uptake through to analysis at the desired time. Certain
reactant mixtures were put into the reactor and closed tightly. After
extensive mixing under magnetic stirring at room temperature, the
reaction was assumed to start after the reactor was put into the oil
bath at the desired temperature and stirred extensively.
A typical procedure for the addition of alcohols to alkenes is:
the gold or palladium(II) catalyst (0.10 mmol) and/or a proper
amount (without specifying, the amount is equal to two moles
of gold, i.e., 0.20 mmol) of CuCl2 was added into 1.5 mL of
the mixtures of the alcohol and alkene (1.21 mmol). Then the
reactor was closed tightly and the reactants mixed in the room
temperature. Specifically, for the addition of methanol to styrene in
different atmospheres (N2, air, O2), the reactor was further purged
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start when the reactor was put into the oil bath at 120 ◦C (unless
otherwise specified) and stirred extensively.
A typical procedure for the addition of amines to alkenes is:
The reactants contain a mixture of alkene (0.50 mmol) and amine
(2.0 mmol for aniline, the others 1.0 mmol) and gold(III) salts
(8 mmol%, i.e. 0.04 mmol)-CuCl2 (16 mmol%, i.e. 0.08 mmol) in
toluene (1.5 mL). The reaction temperature is 150 ◦C.
A typical procedure for the addition of phenol to alkenes
is: The reactants contain a mixture of alkene (0.50 mmol) and
4-methoxphenol (1.0 mmol) and gold(III) salts (8 mmol%, i.e.
0.04 mmol)–CuCl2 (16 mmol%, i.e. 0.08 mmol) in toluene (1.5 mL).
The reaction temperature is 120 ◦C.
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Acknowledgements
9 Handbook of Chemistry and Physics, ed. D. R. Lide, CRC Press, Boca
Roton, FL, USA, 80th edn, 1999, pp. 8–21.
This work was supported by the Spanish government (Project
MAT 2006–14274-C02–01). X. Zhang thanks the ITQ for post-
doctoral scholarship.
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