Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts

Article abstract of DOI:10.1002/chem.201605269

Tremorine and precursors of gemini surfactants were synthesised in a one-pot, three-step, double-catalytic A³coupling reaction and characterised by structural and spectroscopic methods. The cationic [Au^I(L1)]SbF₆complex is a more active catalyst compared to neutral L2– and L3–Au^Ibis(trifluoromethanesulfonyl)imidate complexes (L1, L2=Buchwald-type biaryl phosphane; L3=triphenylphosphine) in promoting the double A³coupling of ethynyltrimethylsilane, secondary amines (cyclic, aliphatic, or aromatic) and formaldehyde. The solvent influences the catalytic performance by desilylation of silyl acetylene or deactivation of the catalyst by a halide anion. Acetylide-bridged cationic digold(I) L1 and L2 complexes were isolated and characterised by means of single-crystal X-ray structure analysis and their spectroscopic properties. Iodine in the acetylene reagent deactivates the Au^Icatalyst by formation of the less active iodido-bridged cationic digold(I) L1 complex, which was fully characterised by single-crystal X-ray crystal structure analysis and spectroscopy. The nature of the phosphine ligand of the gold complexes used as catalyst affects the stability and activity of the formed cationic ethynyl-bridged Au^I₂–L intermediates, isolation of which lends support to the proposed double A³coupling mechanism.

Full text of DOI:10.1002/chem.201605269

A Journal of
Accepted Article
Title: Preparation of Tremorine and Gemini Surfactant Precursors
using Cationic Ethynyl-Bridged Digold Catalysts
Authors: Abdessamad Grirrane, Eleuterio Alvarez, Hermenegildo
García, and Avelino Corma
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10.1002/chem.201605269
Chemistry - A European Journal
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Preparation of Tremorine and Gemini Surfactant Precursors using
Cationic Ethynyl-Bridged Digold Catalysts
Abdessamad Grirrane,*[a] Eleuterio Álvarez,[b] Hermenegildo García,*[a] and Avelino Corma*[a]
Abstract: Tremorine and precursors of Gemini surfactants have
been synthesized in one pot, three-steps, double catalytic A3-
coupling reaction and characterized by structural and spectroscopic
properties. The cationic [Au(I)-L1][SbF6] complex is a more active
explosion, especially when pressurized.[4] For this reason, it
would be highly desirable to develop alternative synthetic
procedures for tremorine and geminis surfactant precursors that
not require acetylene manipulation in the academic and small-
scale industrial research laboratories. Surprisingly, however,
there are no reports on catalytic processes for the synthesis of
these high-value compounds in one-pot, multistep reaction
involving a double A3 coupling[5] in the two carbons of an ethynyl
fragment. The known activity of homogeneous gold catalysts
with [Au(I)-L][A] (L = phosphine and A = counterion) complexes[6]
for the activation of numerous alkynes[5h,5i,7] has led us to
anticipate that such complexes can also be efficient catalysts for
the double A3 coupling to synthesize tremorine and gemini
surfactant precursors. In this regard, herein, we describe an
efficient homogeneous Au(I) catalyst for the double A3-coupling
as new one-pot procedure for preparation tremorine and gemini
surfactant precursors using ethynyltrimethylsilane (TMS-
acetylene) as ethynyl fragment, secondary amines (cyclic,
aliphatic or aromatic) and formaldehyde. Other acetylene
precursor, namely 1-iodo-2-(trimethylsilyl)acetylene, was also
used in this study to shed light on the reaction mechanism.
catalyst
compared
to
neutral
L2
and
L3-
Au(I)-
[bis(trifluoromethanesulfonyl)imidate] complexes (L1, L2
=
Buchwald-type biaryl phosphane and L3 = triphenylphosphine) to
promote the double A3-coupling of ethynyltrimethylsilane, secondary
amine (cyclic, aliphatic or aromatic) and formaldehyde. The solvent
influences the catalytic performance by desilylation of silyl acetylene
or deactivation of catalyst by a halide anion. Acetylide-bridged
cationic digold(I)-L1 and -L2 complexes have been isolated and
characterized by a single-crystal X-ray crystal structure analysis and
their spectroscopic properties. Iodine in the acetylene reagent
deactivates the Au(I) catalyst by formation the less active iodide-
bridged cationic digold(I)-L1 complex that was fully characterized by
a single-crystal X-ray crystal structure analysis and spectroscopic
properties. Also it was observed that the nature of the phosphine
ligand of the gold complexes used as catalyst affects the stability
and activity of the formed cationic ethynyl-bridged di-Au(I)-L
intermediates whose isolation lends support to the proposed double
A3-coupling mechanism.
Results and Discussion
Introduction
In this work, two Au(I) complexes with Buchwald phosphanes,
one cationic 2-di-tert-butylphosphanylbiphenyl (L1) and the other
neutral 2-di-cyclohexyl phosphanyl-2’,4’,6’-triisopropylbiphenyl
(L2) complexes (1) and (2) [Table 1, Scheme (bottom)] have
been tested as catalysts to promote the double A3-coupling of
ethynyltrimethylsilane (4), pyrrolidine (5) and formaldehyde (6).
Their catalytic activity has been compared with that of the
neutral triphenylphosphine (L3) AuI complex (3)[8] [Table 1,
Scheme (bottom)]. Formation of 1-(3-(trimethylsilyl)prop-2-yn-1-
yl)pyrrolidine (7) and 1-(prop-2-yn-1-yl)pyrrolidine (8) [Table 1,
Scheme (top)] as first and second product intermediates,
respectively, and finally tremorine (9) was observed in high yield
and selectivity, at low temperature [Table 1, Scheme (top)]. One
important conclusion from Table 1 (entries 1-3) is that the
cationic AuI complex (1) is more active in the presence of
ethanol as solvent compared to toluene or CH2Cl2. This higher
activity in ethanol can be explained by the faster desilylation[9] of
TMS-protected alkyne (7) formed at the beginning as the first
reaction intermediate by the OH-groups to afford the terminal
alkyne 8 as second reaction intermediate. Compound 8 finally
reacts to give the targeted tremorine (9) [Table 1, Scheme (top)].
Controls in the absence of any catalyst do not allow the
detection of any product [Table 1 (entry 4)]. Tremorine (9) was
characterized by NMR spectroscopy and GC-MS (see the
Tremorine,[1] a symmetric pyrrolidinyl methyl acetylene [see
structure in Table 1, Scheme (top)] is used to induce tremor in
animals, allowing evaluation of the therapeutical activity of drugs
for the treatment of Parkinson's disease. Gemini surfactants are
structurally diverse type of symmetric amphiphilic compounds
with two quaternary ammonium head groups connected through
a spacer [see structure in Table 2, Scheme (top)].[2] These
compounds can be prepared from acetylene. However, the use
of acetylene[3] in the laboratory is hazardous due to its high
flammability and its intrinsic instability, resulting in spontaneous
[a] Dr. A. Grirrane, Prof. Dr. H. Garcia, Prof. Dr. A. Corma
Instituto Universitario de Tecnología Química CSIC-UPV
Universitat Politècnica de València
Av. De los Naranjos s/n, 46022 Valencia (Spain)
Fax: (+34) 963877809
E-mail: grirrane@itq.upv.es, hgarcia@qim.upv.es, acorma@itq.upv.es
[b] Dr. E. Álvarez
Instituto de Investigaciones Químicas CSIC-US
Departamento de Química Inorgánica
Av. Américo Vespucio 49, 41092 Sevilla (Spain)
Supporting information for this article is given via a link at the end of
the document.
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10.1002/chem.201605269
Chemistry - A European Journal
FULL PAPER
experimental section and Figs. S1-S4 in Supporting Information).
1H, 13C and Dept NMR spectra in CD2Cl2 provided evidence that
the starting TMS-acetylene (4) and the intermediate compounds
7 and 8 are completely converted into tremorine (9). GC-MS
data of 9 (C12H20N2) shows a peak at 192.16 Da in agreement
with the expected molecular formula (see Fig. S4 in the SI). The
intermediate compounds 7 (C10H19NSi) and 8 (C7H11N) were
also characterized during the kinetic study of this reaction by
their, GC-MS peaks at 181.13 and 109.09 Da, respectively, in
agreement with their expected molecular formulas (see Fig. S5
for 7 and Fig. S6 for 8 in the SI). The solid catalyst 1 can be
recovered from the reaction mixture when ethanol is used as
solvent by addition of cold n-Hexane over this mixture at final
reaction time, followed by filtration, then the resulting crystalline
solid was washed three time by n-Hexane, dried under reduced
pressure at RT and reused several times without losing activity
and selectivity [Table 1 (entries 5-6)].
Under the optimal conditions, catalyst evaluation was extended
to neutral complexes Au(I)-L2 (2) and Au(I)-L3 (3) [Table 1,
Scheme (bottom)]. Also in these cases tremorine (9) was
obtained in good yield, but longer reaction times were required
[Table 1 (entries 7-8)]. It was observed that the activity of the
catalysts decreased in the order 1 ˃ 2 ˃ 3. This catalytic activity
order can be explained by the higher electrophilicity of the Au(I)
atom in cationic complex 1 respect to the neutral complexes 2
and 3, and the higher structural stability of complex 2 compared
with labile complex 3. In the case of Au(I)-L3 (3) complex, it was
observed the PPh3 ligand is not able to stabilize the di-gold
species formed during the catalytic reaction and decomposition
takes place (see below).[7b]
To expand the scope of this catalytic process,
ethynyltrimethylsilane (4) and aqueous formaldehyde (6) were
reacted under optimal conditions, with a series of amines
including 4-methylpiperidine (10), diisopropylamine (14),
dibutylamine (18) and dibenzylamine (22) using the most active
and stable cationic Au(I) complex 1 as catalyst (see Table 2).
The expected reaction intermediates TMS-protected alkynes (11,
15, 19 and 23) and 1-(prop-2-yn-1-yl)amines (12, 16, 20 and 24)
(see Table 2), were characterized during the kinetic studies of
these reactions by GC-MS (see the experimental section and
the Figs. S7-S14 in SI).
Table 1. One pot, double A3-coupling of TMS-acetylene (4), pyrrolidine (5),
and formaldehyde (6) with complexes of Au(I) 1, 2, 3, 26, (26 + 1eq. of
HSbF6), 27, (27 + 1eq. of HNTf2) or 31 as catalysts (6 mol %).[a]
Table 2. One pot, double A3-coupling of TMS-acetylene, amines, and aqueous
formaldehyde with complex of Au(I) 1 as catalysts (6 mol %).[a]
entry
Catalyst
Solvent
Time (h)
Conv.
(%)[b]
Yield
(%)[b]
(7 / 9)
1
2
3
4
5
1
1
1
CH2Cl2
Toluene
Ethanol
Ethanol
Ethanol
5
5
2
5
2
100
100
100
0
99 / 0
99 / 0
0 / 99
0 / 0
none
First reuse of
1
100
0 / 99
6
Second reuse Ethanol
of 1
2
100
0 / 99
en
try
Amine
First
intermediate
Second
intermediate
t
Conv
(%)[b]
Yield of final
product (%)[b]
(h)
7
8
9
10
2
Ethanol
Ethanol
Ethanol
Ethanol
3
4
4
2
100
100
100
100
0 / 97
0 / 91
0 / 96
0 / 99
1
6
100
3
26[c]
10
26[c] + 1eq. of
11
15
12
16
[d]
HSbF6
13 (99)
17 (99)
11
12
27[c]
Ethanol
Ethanol
6
3
100
100
0 / 95
0 / 96
2
3
10
13
100
100
27[c] + 1eq. of
[e]
HNTf6
0 / 60[f]
0 / 68[f]
14
13
14
31
Ethanol
Ethanol
6
6
81
89
1[g]
18
22
19
23
20
24
21 (98)
25 (92)
4
28
100
[a] Reactions were carried out using 0.25 mmol of TMS-acetylene, 0.7 mmol
of pyrrolidine, 1.4 mmol of aqueous formaldehyde and 1.5 ml of solvent. [b]
conv. of 4 and yields (%) were determined by 1H NMR spectroscopy and GC
of the crude reaction mixture. [c] 3 mol % of di-Au(I) complex was used as
catalyst. [d] 3 mol % of HSbF6 acid was added. [e] 3 mol % of HNTf2 acid
was added. [f] 16 % of compound 8 are detected. [g] 0.25 mmol of 1-iodo-2-
(trimethylsilyl)acetylene was used in the reaction instead of TMS-acetylene.
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10.1002/chem.201605269
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a 3:1 mixture of ethynyltrimethylsilane (4) with gold(I) complexes
1 and 2 in dry CH2Cl2 at RT for 24 h and 60 ºC for 72 h,
respectively (Scheme 1). Filtration of the resulting dark solutions
followed by addition of n-hexane at -30 ºC or RT to the formation
of colourless needles crystals of the air stable cationic di-gold(I)
acetylide complexes[7a,7b,10] of 26 and 27, respectively, in good
isolated yields respect to the initial complexes 2 and 3 (86 and
71 %). Complexes 26 and 27 were fully characterized by
analytical and spectroscopic data (see the Experimental Section,
Table S3-S4 and Figs. S36-S48 in the SI).
[a] Reactions were carried out using 0.25 mmol of TMS-acetylene, 0.7 mmol of
amine, 1.4 mmol of aqueous formaldehyde and 1.5 ml of Ethanol. [b] conv. of 4
1
and yield of final products (%) were determined by H NMR spectroscopy and
GC of the crude reaction mixture.
The desired gemini surfactant precursors 1,4-bis(4-
methylpiperidin-1-yl)but-2-yne (13), N,N,N´,N´-tetraisopropylbut-
2-yne-1,4-diamine
(17),
N,N,N´,N´-tetrabutylbut-2-yne-1,4-
diamine (21) and N,N,N´,N´-tetrabenzylbut-2-yne-1,4-diamine
(25) (see Table 2) were isolated and characterized by 1H, 13C
and Dept NMR spectroscopy (see Figs. S15-S17 for 13, S19-
S21 for 17, S23-S25 for 21 and S27-S29 for 25 in the SI). GC-
MS data obtained dissolving 13 (C16H28N2), 17 (C16H32N2), 21
(C20H40N2) and 25 (C32H32N2) in CH2Cl2 show peaks at 248.3,
252.3, 308.2 and 444.2 Da, respectively, in agreement with the
expected molecular formulae (see Figs. S18, S22, S26 and S30,
respectively, in the SI).
1H, 13C, and 31P NMR spectroscopy of CD2Cl2 solutions provides
evidence showing that under the reaction condition the starting
complexes
1 and 2 are completely converted into the
corresponding cationic di-gold(I) acetylide complexes 26 and 27,
[11]
releasing Me3Si-SbF6
and Me3Si-NTf2 adducts, respectively
(see Figs. S36-S39 for 26 and S41-S42 for 27 in the SI). Thus,
31P NMR spectroscopy shows the appearance of new peaks at δ
= 62.46 and 38.74 ppm corresponding to 26 and 27, respectively
(see Figs. S39 and S45 in the SI). These peaks are different
from those recorded in 31P NMR spectroscopy for the original
Au(I) complexes 1 (57.49 ppm) and 2 (33.29 ppm). Cationic
bridged-acetylide di-gold(I) complexes 26 and 27 (Scheme 1)
are fluxional in solution and exhibit at room temperature a single
The solid state structure of 25 was confirmed by a single-crystal
X-ray crystal structure analysis (For X-ray data, ortep view and
crystal packing details see, Table S1 and Fig. S31 in the SI).
Also high quality crystals of protonated salt 13a suitable for a
single-crystal X-ray crystal structure analysis were obtained by
adding 2 eq. of aqueous HCl (37 %) over the solution of
compound 13 in CH2Cl2 at RT allowing the biphasic mixture to
equilibrate. The solid state structure confirms the double
protonation of compound 13 with the presence of two chlorine
atoms as counterion, leading to the dipositive salt 13a (For X-ray
data, ortep view and crystal packing details see Table S2 and
Fig. S32 in the SI). Following the same procedure the salt 17a of
the dication was obtained and confirmed by elemental analysis
1
31P{1H} resonance. Similarly to 31P NMR, H NMR spectroscopy
also shows new signals of methyl groups for complex 26 at
1.37/1.32 instead of 1.38/1.33 ppm corresponding to the initial
complex 1 and for complex 27 at 1.32/1.22/0.93 instead of
1.38/1.21/0.90 ppm corresponding to the initial complex 2 (see
Fig.S36 for 26 and Fig.S44 for 27 in the SI). The ethynyl bridge
in the σ,π-acetylide complex 26 exhibits 13C{1H} resonances at
2
3
138.52 (t, JCP = 64.34 Hz) and 96.37 ppm (t, JCP = 15.17 Hz)
(see Fig. S37 in the SI), which are due to the C and CH moieties
of bridging ethynyl ligand (C≡CH) as confirmed by Dept.135,
HMQC and COSY -NMR experiments (see Figs. S38, S40 and
S41, respectively, in the SI). Recently, it was published the first
cationic ethynyl-bridge di-gold(I) complex stabilized by bulky
terphenyl phosphine ligand using hydrocarbonyl transfer reagent
[Mg(C≡CH)X; X = Cl, Br] as precursor of ethynyl fragment.[12]
1
and H, 13C and Dept NMR spectroscopy in deuterated DMSO
(see Figs. S33-S35 in the SI) providing evidence that compound
17 is completely converted into double protonated salt 17a.
Besides Gemini surfactant precursors 13, 17, 21 and 25,
formation of TMS-protected- alkynes 11 (C12H23NSi), 15
(C12H25NSi), 19 (C14H29NSi) and 23 (C20H25NSi) was observed
as primary products at the initial stages of the reactions (see
Table 2). These reaction intermediates were characterized by
GC-MS data showing a peak at 209.2, 211.2, 239.2 and 307.3
Da, respectively, in agreement with their expected molecular
formulae (see Figs. S7, S9, S11 and S13 in the SI). Subsequent
desilylation of compounds 11, 15, 19 and 23 leads to the
corresponding terminal alkynes, i.e., 4-methyl-1-(prop-2-yn-1-
yl)piperidine (12), N,N-diisopropylprop-2-yn-1-amine (16), N-
butyl-N-(prop-2-yn-1-yl)butan-1-amine
dibenzylprop-2-yn-1-amine (24)
(20)
second
and
N,N-
reaction
as
intermediates in the formation of Gemini surfactant precursors
(see Table 2). These terminal alkynamines were also
characterized by GC-MS data showing peaks at 137.2, 139.3,
167.3 and 235.3 Da in agreement with the expected molecular
formulae 12 (C9H15N), 16 (C9H17N), 20 (C11H21N) and 24
(C17H17N) (see Figs. S8, S10, S12 and S14 in the SI).
In an attempt to isolate some AuI complexes that could shed
light on the reaction mechanism leading to the formation of
these Gemini surfactant precursors obtained in one pot, double
A3-coupling using gold(I) complexes as catalysts, several
experiments were done. In one of them, we proceeded to react
Scheme 1. Synthesis of the cationic bridged-acetylide di-gold(I) complexes 26
and 27.
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Figure 1. ORTEP views of cationic bridged-acetylide di-gold(I) complexes 26
and 27; hydrogen are omitted for clarity, and thermal ellipsoids are set at 30 %
probability level (a single-crystal X-ray crystal structure analysis data and
crystal packing details are given in Table S3 and Fig.S43 for 26 and Table S4
and Fig.S48 for 27 in the SI).
ESI-MS of solutions obtained after dissolving fluxional cationic
[(σ,π)](L1-Au)2(µ-acetylene)[SbF6] (26) and [(σ,π)](L2-Au)2(µ-
acetylene)[NTf2] (27) complexes, respectively, in CH2Cl2 showed
intense positive MS peaks at 1015.3 and 1371.9 Da (see Fig.
S42 for 26 and Fig. S47 for 27 in the SI) that are attributable,
- +
respectively, to the cationic [C42H55Au2F6P2Sb (26) - SbF6 ] and
- +
[C70H99Au2F6NO4P2S2 (27) - N(SO2CF3)2 ] species, that are also
In both complexes the carbon atom C1 of bridged-acetylene is
bonded to the two gold atoms in a non-symmetric and symmetric
fashion, respectively, with the Au1-C1 and Au1A-C1 distance of
2.006(4) and 2.138(6) Å, respectively, for 26 and 27, bonds
being shorter and equal than Au2-C1 and Au1-C1 with distances
about 2.309(4) and 2.138(6) Å, respectively, for 26 and 27. In
both complexes, Au2 and Au1 atoms are also bonded to the
terminal ethynyl carbon atom C2 with the Au2-C2 and Au1-C2
distance of 2.194(5) and 2.418(6) Å, respectively, for 26 and 27.
The aurophilic bonding Au1-Au2 and Au1-Au1A in 26 and 27 is
about 3.679 and 3.638 Å, respectively.
in good agreement with the simulated isotopic distributions for
the molecular formula [C42H55Au2P2] and [C68H99Au2P2],
respectively (see Fig. S42 for 26 and Fig. S47 for 27 in the SI).
Two negative MS peaks were found in the case of complex 26 at
234.6 and 236.6 Da corresponding to the two isotopes 121Sb and
123Sb of [SbF6]- counter anion (see Fig. S42 in the SI), versus
single negative MS peak at 279.7 Da corresponding to
[N(SO2CF3)2]- counter anion of complex 27 (see Fig. S47 in the
SI).
The molecular structure of complexes 26 and 27 (Scheme 1)
was confirmed by a single-crystal X-ray crystal structure analysis.
ORTEP structures of complexes 26 and 27 are shown in Figure
1 (For X-ray data, ortep view and crystal packing details see in
the SI: Table S3 and Fig.S43 for 26 and Table S4 and Fig.S48
for 27).
The catalytic activity of cationic di-gold [(σ,π)](L1-Au)2(µ-
acetylene)[SbF6] (26) complex was also tested for the double A3-
coupling of ethynyltrimethylsilane (4), pyrrolidine (5) and
formaldehyde (6), whereby tremorine (9) was obtained in good
yield, but needing longer reaction time (Table 1, entry 9)
compared to the cationic complex 1 (Table 1, entry 3). We found
that when 1 eq. of HSbF6 is added to the di-gold complex 26 in
the catalytic double A3-coupling, a higher reaction rate for the
formation of tremorine (9) is observed (Table 1, entry 10) and
the result in this case is similar as when cationic complex 1 is
used as pre-catalyst (Table 1, entry 3). The role of this
equivalent of acid is justified in our mechanistic proposal
(Scheme 3) in the absence of CH2Cl2.[5i] Also the catalytic
activity of cationic di-gold [(σ,π)](L2-Au)2(µ-acetylene)[NTf2] (27)
and its mixture with 1 eq. of HNTf6 acid were measured (Table 1,
entries 11 and 12, respectively), the results following the same
trend as the previously commented experiments of complex 26.
Another additional unsuccessful experiment aimed to isolate the
di-gold(I) acetylide complex (28) (Scheme 2, top) was performed
by using the same conditions as those used in the formation of
complexes 26 and 27 (Scheme 1), but using in this case a 1:3
mixture of gold(I) complex 3 with ethynyltrimethylsilane (4), in
dry CH2Cl2 at RT for 24 h (Scheme 2). A black precipitate was
formed. This precipitate could be collected by filtration to be
analysed by HR-TEM, DF-STEM and EDX-analysis after
sonication in DCE (see below), addition of toluene to the
collected transparent supernatant solution and slow
crystallization at RT, leading to the formation of pure cationic
complex [Au(I)-(PPh3)2][N(SO2CF3)2] (30) (Scheme 2, top) in
46 % yield. Complex 30 has been previously reported by us[7b]
as being formed in a different reaction (see the experimental
section in the SI). Complex 30 was fully characterized by 1H, 13C,
dept.135, 31P and 19F NMR spectroscopy (see, Figs. S49-S53 in
the SI), ESI-MS (see, Fig. S54 in the SI), combustion analysis
and by a single-crystal X-ray crystal structure analysis (see, Figs.
S55 in the SI). The structure obtained here resulting identical to
the one previously published for 30.[7b]
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In another experiment, 1-iodo-2-(trimethylsilyl)acetylene was
used as reagent instead of ethynyltrimethylsilane (4) to react
with gold(I) complex 1, in a 3:1 mixture, in dry CH2Cl2 at RT and
40 ºC for 48 h (Scheme 2, bottom). Filtration of the resulting dark
solution followed by addition of n-hexane at -30 ºC lead to the
formation of colourless crystals of the air stable cationic bridged
iodide di-gold(I) [(L1-Au)2(µ-I)[SbF6] (31) complex in good
isolated yield respect to the initial complex 1 (92 %). The di-
gold(I) complex 31 was characterized by NMR spectroscopy and
ESI-MS (see the experimental section and Figs. S61-S65 in the
1
SI). H, 13C, Dept.135 and 31P NMR spectra in CD2Cl2 provided
evidence that the starting gold(I) complex 1 was completely
converted into complex 31 (see Figs. S61-S64 in the SI). Thus,
31P NMR spectroscopy shows the appearance of a new peak at
δ = 66.58 ppm, attributable to 31 (see Fig. S64 in the SI). This
peak is different from the one recorded in 31P NMR spectroscopy
for the original complex 1 (57.49 ppm).
ESI-MS of the solution obtained after dissolving, cationic [(L1-
Au)2(µ-I)][SbF6] (31) complex in CH2Cl2 showed an intense
positive MS peak at 1117.3 Da (see Fig. S65 in the SI) that is
Scheme 2. Top: Failure to isolate any Au(I) acetylide complex and formation
of Au NPs and cationic Au(I) complex 30. bottom: deactivation of cationic Au(I)
complex 1 by formation of a less active, cationic bridged iodide digold(I)
[(L1Au)2(µ-I)][SbF6] (31) complex when 1-iodo-2-(trimethylsilyl)acetylene is
used as reagent instead of ethynyltrimethylsilane (4).
- +
attributable to the cationic [C40H54Au2F6IP2Sb (31) - SbF6 ]
species whose isotopic distribution is in good agreement with
the simulated isotopic distribution for the molecular formula
[C40H54Au2IP2] (see details in Fig. S65 in the SI). Negative MS
exhibits mainly single cluster at 234.6 and 236.6 Da attributable
The HR-TEM and DF-STEM images together with the EDX-
analysis of this black solid reveal the formation of well dispersed
homogeneous Au NPs with diameter between 1 and 3 nm [see
Figure 2 (top) and Figs. S56-S57 in the SI for more details]. Note
that this experiment is similar to the previously published one[7b]
in which phenylacetylene was used as reagent instead of
ethynyltrimethylsilane (4), but in the present case no alkyne
gold(I) complexes such as 28 and 29 (Scheme 2, top) were
detected probably due the quick decomposition of the presumed
cationic [(σ,π)(PPh3-Au)2(µ-acetylene)][NTf2] (28) and neutral
[(σ)(PPh3-Au)(acetylene)] (29) (Scheme 2, top). The easy
decomposition of presumed complexes 28 and 29 can be
explained considering that it is known[7a,7b] that the less bulky
PPh3 ligand has low ability to stabilize such (µ-
acetylene)[(σ,π)]digold- system compared with the sterically
encumbered phosphine ligands L1 and L2 present, respectively,
in 26 and 27 (Scheme 1). Thus, the mixture of gold(I) complex 3
with ethynyltrimethylsilane (4) in CD2Cl2 at RT was followed by
31P NMR spectroscopy providing evidence that the starting
gold(I) complex 3 (30.48 ppm) was completely converted into
complex 30 (45.09 ppm) over the time (see Figs. S58-S60 in the
SI). 31P NMR spectroscopy shows the appearance at 5 min
reaction time of a minor (1 %) new peak at (45.09 ppm)
corresponding to complex 30 versus a major (99 %) peak of
starting complex 3 (see Fig. S58 in the SI). Over the time (30
min) complex 3 disappeared completely, accompanied by the
appearance of a new peak at 36.50 ppm (92 %) attributable to a
presumed σ-acetylide gold(I) complex 29, similarly to the
previously isolated σ-phenylacetylide gold(I) complex,[7b]
together with 8 % of complex 30 (45.09 ppm) (see Fig. S59 in
the SI). At 2 h reaction time, complex 30 was almost (99 %) the
only product detectable, with a remaining trace (less than 1%)
amount of acetylide gold(I) complexes di-gold 28 (32.80 ppm)
and mono-gold 29 (36.60 ppm) (see Fig. S60 in the SI).
-
to counter-anion SbF6 of complex 31 with the 121Sb and 123Sb
isomers (see Fig. S65 in the SI). Combustion elemental analysis
of complex 31 was also in accordance with the percentages
expected for its molecular formula (see experimental section in
the SI).
The molecular structure of complex 31 [Scheme 2 (Bottom)] was
confirmed by a single-crystal X-ray crystal structure analysis, the
ORTEP structure of 31 complex is shown in Figure 2 (bottom)
(see, Table S5 and Figs. S66 for details in the SI). In this
complex, iodide atom is bonded to the two gold atoms in a
symmetric fashion, with the Au1-I1 and Au2-I1 distance of
2.5895(8) and 2.5888(8) Å. The aurophilic Au1-Au2 bonding for
31 is about 3.837 Å, being this bond longer than the Au1-Au2
and Au1-Au1A bonds in complexes 26 and 27 that are 3.679
and 3.638 Å, respectively.
The catalytic activity of this cationic iodide bridged di-gold(I)
[(L1-Au)2(µ-I)][SbF6] (31) complex was tested for the preparation
of tremorine (9) (Table 1, entry 13), the result confirming its low
activity. This low activity was also observed when gold(I)
complex
(trimethylsilyl)acetylene
1
is used as catalyst, but using 1-iodo-2-
as reagent instead of
ethynyltrimethylsilane (4). It is very likely that using iodo
acetylene as reagent, deactivation of gold(I) complex 1 occurs
due to reaction with iodide atoms released to the medium and
leading to the formation of the less active cationic iodide bridged
di-gold(I) 31 complex (Table 1, entry 14).
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10.1002/chem.201605269
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di-gold(I) complex 27 and releasing one equivalent of Me3Si-
1
NTf2 to the reaction medium (see Figs. S71-S73 for H, 31P and
19F NMR spectra in the SI). In a second step of this catalytic
process, pyrrolidine (5), formaldehyde (6) and 0.5 ml of ethanol
were added over the mixture and the changes were followed
again by NMR spectroscopy. After 1 h, the mixture was
analysed by 31P NMR spectroscopy, showing the total
disappearance of the peak at 38.48 ppm corresponding to
cationic acetylide-bridged di-gold(I) intermediate 27 (see Fig.
S74 in the SI) and the formation of new peaks at 33.63, 33.68,
35.17 and 44.39 ppm attributable to proposed cationic
nitrogenated gold(I) complexes 32, 33, 34 and 35 (Scheme 3). In
addition, other two peaks at 35.73 and 43.81 ppm were also
observed attributable, respectively, to a total (neutral chlorine
gold(I) L2-Au-Cl) and partially (cationic chloride-bridged di-
gold(I) [(L2-Au)2(µ-Cl)][NTf2])[13] deactivated forms of gold(I)
complexes,[5i] originated from the use as solvent of CD2Cl2 in the
presence of pyrrolidine (5). Over the time (5 h), the peaks
corresponding to active catalytic intermediates (33.63, 33.68,
35.17 and 44.39 ppm) were gradually consumed (see Fig. S75
in the SI) and after 12 h reaction time, the only observed species
was the deactivated chlorine-Au(I) complexes with 31P NMR
spectroscopy peaks at 35.75 and 43.59 ppm (see Fig. S76 in the
SI).
Based on these spectroscopic observations, a plausible reaction
mechanism[5g-i,14] for the one pot, double A3-coupling of ethynyl,
pyrrolidine and formaldehyde using bulky L1- or L2- gold(I)
complexes as precatalyst in the absence of CH2Cl2 can be
proposed (Scheme 3). The main feature of this mechanism is
the coordination of Au(I) precatalyst 1 or 2 with the ethynyl group
leading to the isolated cationic acetylide-bridged di-gold(I)
complexes [(σ,π)](L1-Au)2(µ-acetylene)[SbF6] (26) or [(σ,π)](L2-
Au)2(µ-acetylene)[NTf2] (27) as catalytic intermediates, releasing
to the medium Me3Si-SbF6 or Me3Si-NTf2 adducts that can be
converted in the presence of ethanol as solvent to the
corresponding acids HSbF6 or HTf2 and ethoxytrimethylsilane.
The condensation reaction between formaldehyde and
pyrrolidine would take place spontaneously or catalysed by
acids. The presumed π-complexes intermediates 32 and 33
involved in the mechanism (see Scheme 3) formed between
gold and ethynyltrimethylsilane (4) or ethynyl, will undergo N-
ligand exchange to from the 1-(3-(trimethylsilyl)prop-2-yn-1-
yl)pyrrolidine (7) and 1-(prop-2-yn-1-yl)pyrrolidine (8) as first and
second reaction intermediates. This ligand exchange will give
rise to the formation of [Au(L1)(pyrrolidine)][SbF6] (34)[5i] as
catalytic complex intermediate. Subsequent reaction of gold(I) π-
complex 33, gold(I) complex 34 and formaldehyde (6) leads to
Figure 2. Top: HR-TEM and DF-STEM images as well as EDX analysis of well
dispersed homogeneous Au NPs with diameter between 1-3 nm obtained in
the reaction of complex 3 and acetylene 4. bottom: ORTEP view of complex
31; hydrogen are omitted for clarity, and ellipsoids are given at the 30 %
probability level (a single-crystal X-ray crystal structure analysis data and
crystal packing details are given in Table S5 and Fig. S66 in the SI).
In order to shed light in to the reaction mechanism and also to
gain understanding on the implication of acetylide di-gold(I)
complexes 26 and 27 in catalysis, the reaction of
ethynyltrimethylsilane (4), pyrrolidine (5) and formaldehyde (6)
using the bulky gold complex 2 as precatalyst was followed by
1H, 31P NMR and ESI-MS spectroscopy. In the first step, 15
mol % of gold complex 2 was added to ethynyltrimethylsilane (4),
whereby 31P NMR spectroscopy shows a new peak at 38.48
ppm matching with the chemical shit of cationic acetylide-
bridged di-gold(I) complex 27, together with the peak
corresponding to original complex 2 (33.37 ppm) in CD2Cl2 (see
Fig. S68 for details in the SI). Also 1H NMR spectroscopy and
ESI-MS confirm the coexistence of the two complexes 2 and 27
in the isolated solid catalyst during the first stage of reaction at 3
the formation of
a
presumed di-cationic [(L1-Au)2(µ-
tremorine)][(SbF6)2] (35) complex closely related to our previous
isolated di-copper(I) complex.[5h] In the last step, tremorine (9) as
final product would be formed by exchange from the
coordination sphere of the two atoms of Au(I) from di-gold(I)
complex 35 by replacement with free pyrrolidine present in the
reaction medium and regeneration [Au(L1)(pyrrolidine)][SbF6]
(34) complex that can start over other cycles of this catalytic
reaction.
1
h reaction time (see Fig. S67 for H NMR and Fig. S69 for ESI-
MS spectra in the SI). It should be commented that from this
mixture of complexes, we have been able to isolate crystals of
complex 2 with quality enough to be analysed by a single-crystal
X-ray crystal structure analysis, resulting in a new solid structure
of this complex (ORTEP, crystal packing details and X-ray data
are given in Table S6 and Fig. S70 in the SI). Over the time (12
h) complex 2 completely disappeared, remaining exclusively the
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10.1002/chem.201605269
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Experimental Section
Experimental Details of preparation,
isolation and full characterization of
tremorine and Gemini surfactant
precursors 9 and 13, 13a, 17, 17a, 21,
25 as well as new gold(I) complexes
26, 27 and 31, including NMR spectra,
combustion analysis, GC-MS, ESI-
MS. GC-MS data of intermediate
compounds 7, 8, 11, 12, 15, 16, 19,
20, 23 and 24; HR-TEM, STEM-DF
and EDX-analysis of black precipitate
formed during the reaction of gold
complex 3 and ethynyltrimethylsilane
(4) in CH2Cl2 at RT; Kinetic
experiments followed by NMR and
ESI-MS spectroscopy and X-ray
crystallography data are provided in
the Supporting Information. CCDC-
1515673
1515675
(2),
(25),
1515674
1515676
(13a),
(26),
1515677 (27) and 1515678 (31)
contain the supplementary
crystallographic data for 2, 13a, 25,
26, 27, 31 respectively. These data
can also be obtained free of charge
from The Cambridge Crystallographic
Data
centre
via
http//www.ccdc.cam.ac.uk/data_requ
est/cif. All reactions were carried out
under Ar in dried solvent using a
Solvent Purification System (SPS).1H
NMR spectra were recorded on a
Scheme 3. Plausible mechanism for one pot, double A3- coupling of ethynyl, secondary amine and formaldehyde
using cationic gold(I) complex 1 as precatalyst in ethanol. Pyrrolidine (5) was choosen as model of secondary
amine, resulting in the formation of tremorine (9).
Bruker
AV300
(300
MHz)
spectrometer. Chemical shifts of 1H
signals are reported in ppm using the
solvent peak as internal standard
(CD2Cl2: 5.27 ppm, CDCl3: 7.26 ppm and (CD3)2SO: 2.50 ppm). Data are
reported as follows: chemical shift, integral, multiplicity (s = singlet, br =
broad, d = doublet, t = triplet, sept = septuplet, m = multiplet), coupling
constants (Hz) and assignment. Chemical shifts of 13C are reported also
in ppm using the solvent peak as internal standard (CD2Cl2: 53.84 ppm,
CDCl3: 77.16 ppm and (CD3)2SO: 39.50 ppm). 31P and 19F NMR spectra
were recorded on a Bruker 300 MHz spectrometer. 31P and 19F chemical
shifts are reported in ppm. Gas chromatography (GC) was performed in a
Varian 3900 apparatus equipped with an TRB-5MS column (5% phenyl,
95% polymethylsiloxane, 30 m, 0.25 mm × 0.25 µm, Teknokroma). GC-
MS (5973N-6890N) analyses were performed on an Agilent spectrometer
equipped with the same column as the GC and operated under the same
conditions. ESI-MS were acquired on an Agilent Esquire 6000 instrument.
Elemental analyses were measured on an EuroEA Elemental Analyser
Eurovector. HR-TEM was acquired using a JEOL JEM-2100F with the
field emission gun operating at 200 kV and the images were recorded
using a GATAN Orius SC600A.
Conclusions
This manuscript has shown the synthesis of tremorine and
gemini surfactant precursors through a catalytic one pot, double
A3-coupling reaction. The reaction products have been fully
characterized by their structural and spectroscopic properties. It
was observed that the nature of the phosphine ligand (L1, L2 or
L3) present in the gold complexes used as catalyst affects the
stability and activity of the formed cationic ethynyl-bridged di-
Au(I)-L complexes involved in the reaction mechanism
intermediates. The activity data show the possible ways in which
the solvent can influence the catalyst performance by limiting the
extent of desilylation of acetylene reagents. The presence of
iodine in the acetylene reagent results on the partial deactivation
of the Au(I) catalyst by formation the iodide-bridged cationic
digold(I)-L1 complex that was fully characterized by its structural
and spectroscopic properties. Unsubstituted acetylide unit-
bridged cationic digold(I)-L1 and -L2 complexes have been
isolated, characterized by structural and spectroscopic
properties and their role as intermediates in the reaction
mechanism supported by control experiments.
General Procedure for the one pot double A3-Coupling reactions:
Preparation of tremorine (9) and gemini surfactant precursors 13, 17,
21, 25: A mixture of TMS-acetylene (4) (0.25 mmol), pyrrolidine (5), 4-
methylpiperidine (10), diisopropylamine (14), dibutylamine (18) or
dibenzylamine (22) (0.7 mmol), respectively, formaldehyde (aq. 37%, 1.4
mmol) and gold(I) complex 1 (0.015 mmol) as catalyst (Au/alkyne ratio 6
mol%) was suspended in ethanol (1.5 ml), then the flask was evacuated
under vacuum and refilled with argon. The evacuation/refilling cycle was
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10.1002/chem.201605269
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repeated three times (pressure 2 bar). The mixture was stirred at 50 ºC
for the required time to obtain the maximum yield of tremorine (9) and
gemini surfactant precursors 13, 17, 21, 25 (see Table 1 and Table 2).
Then, cold n-hexane was added to the reaction mixture, the suspension
filtered and the solvents removed under reduced pressure at 50 ºC to
provide as light-yellow oils in yields higher than 90 % (see Table 1 and
Table 2) the compounds 9, 17 and 21 and as light-yellow solids the
copounds 13 and 25. The structure and purity of tremorine (9) and gemini
surfactants precursors 13, 17, 21, 25 were confirmed by 1H, 13C, 13C
Dept-135 NMR spectroscopies, GC-MS spectrometry analysis. Crystals
of 25 suitable for X-ray crystallography (see Table S1 and Fig. S31) were
obtained by recrystallization of the yellow solid 25 in a mixture of
dichloromethane/acetone (1/2) and after standing for 24 h at RT.
Composition of 25 also was confirmed by elemental analysis.
Preparation of double protonated gemini surfactant precursors 13a
and 17a: 2 eq. of aqueous HCl (37 %) were added, respectively, over the
solutions of compounds 13 (0.248 g, 0.10 mmol) and 17 (0.252 g, 0.10
mmol) in CH2Cl2 at RT. A yellow crystalline material corresponding to the
anionic compounds 13a and 17a was obtained upon standing the
biphasic mixture for 50 h at RT. The solids were collected by filtration,
washed with n-hexane and dried under vacuum (0.311 g, 97 % yield for
13a) and (0.312 g, 96 % yield for 17a). The double protonation of these
gemini surfactant precursors were confirmed by a single-crystal X-ray
crystal structure analysis and elemental analysis in the case of 13a and
by NMR spectroscopy and elemental analysis in the case of 17a.
Compound 13a: Elemental analysis, calc. for C16H30Cl2N2 (13a) (%): C,
59.81; H, 9.41; N, 8.72. Found: C, 59.93; H, 9.37; N, 8.84. The solid state
structure confirms the double protonation of 13a and the presence of two
chlorine atoms as counterion (For X-ray data, ortep view and crystal
packing details see, Table S2 and Fig. S32 in the SI).
Tremorine 9: 1H NMR (300 MHz, CD2Cl2): δ (ppm) = 3.31 (s, 4 H; CH2-
butyne), 2.58-2.42 (m, 8 H; CH2-pyrrolidine), 1.78-1.63 (m, 8 H; CH2-
pyrrolidine) (see Fig. S1). 13C NMR (75 MHz, CD2Cl2): δ (ppm) = 80.19,
52.82, 43.52, 24.22 (see Fig. S2). 13C Dept-135 NMR (75 MHz, CD2Cl2):
δ (ppm) = Positive Signals: 52.82 and 24.22 for (CH2, pyrrolidine), 43.52
for (CH2, group) (see Fig. S3). GC-MS m/z: 192.2 amu for [C12H20N2 (9)]
(see Fig. S4 for details).
Compound 17a: Elemental analysis, calc. for C16H34Cl2N2 (13a) (%): C,
59.07; H, 10.53; N, 8.61. Found: C, 59.15; H, 10.45; N, 8.70. 1H NMR
(300 MHz, DMSO-d6): δ (ppm) = 10.90 (s (br), 2 H; NH-groups), 4.14 (s,
4 H; CH2-butyne), 3.80 (sept, 4 H; CH-isopropyl), 1.35 (d, 24 H; CH3-
isopropyl) (see Fig. S33). 13C NMR (75 MHz, DMSO-d6): δ (ppm) = 80.14,
53.48, 35.10, 17.43 (see Fig. S34). 13C Dept-135 NMR (75 MHz, DMSO-
d6): δ (ppm) = Positive Signals: 53.48 (CH, group), 17.43 (CH3, group);
Negative Signals: 35.10 (CH2, groups) (see Fig. S35).
Compound 13: 1H NMR (300 MHz, CD2Cl2): δ (ppm) = 3.18 (s, 4 H;
CH2-butyne), 2.76 (m, 4 H; CH2-piperidine), 2.06 (m, 4 H; CH2-piperidine),
1.57 (m, 5 H; CH and two CH2-piperidine), 1.17 (m, 5 H; CH and two CH2-
piperidine), 0.86 (d, 6 H; CH3-group) (see Fig. S15). 13C NMR (75 MHz,
CD2Cl2): δ (ppm) = 80.54, 53.16, 47.90, 34.79, 30.89, 22.04 (see Fig.
S16). 13C Dept-135 NMR (75 MHz, CD2Cl2): δ (ppm) = Positive Signals:
53.16, 47.90, 34.79 (CH2, groups); Negative Signals: 30.89 (CH, group),
22.04 (CH3, group) (see Fig. S17). GC-MS m/z: 248.3 amu for [C16H28N2
(13)] (see Fig. S18 for details).
Isolation of cationic [(σ,π)](L1-Au)2(µ-acetylene)[SbF6] complex 26:
A mixture of complex [Au(L1)(CH3CN)][SbF6] (1) (0.116 g, 0.15 mmol)
and ethynyltrimethylsilane (4) (0.0442 g, 0.45 mmol) was dissolved in
dichloromethane (2 ml). The solution was stirred at 40 ºC under argon
atmosphere. The stirring was maintained for 24 h. Then, the resulting
mixture was diluted with other
2 ml of CH2Cl2, filtered and the
Compound 17: 1H NMR (300 MHz, CD2Cl2): δ (ppm) = 3.40 (s, 4 H;
CH2-butyne), 3.19 (sept, 4 H; CH-isopropyl), 1.05 (d, 24 H; CH3-
isopropyl) (see Fig. S19). 13C NMR (75 MHz, CD2Cl2): δ (ppm) = 82.17,
49.41, 34.81, 20.45 (see Fig. S20). 13C Dept-135 NMR (75 MHz, CD2Cl2):
δ (ppm) = Positive Signals: 49.40 (CH, group), 20.45 (CH3, group);
Negative Signals: 34.81 (CH2, groups) (see Fig. S21). GC-MS m/z: 252.3
amu for [C16H32N2 (17)] (see Fig. S22 for details).
supernatant was covered carefully with a layer of 1.5 ml of n-hexane. A
colourless crystalline material suitable for X-ray crystallography
corresponding to complex 26 was formed by standing for 24 h at -30 ºC,
the solid was collected by filtration, washed with cold n-hexane and dried
under vacuum (0.081 g, 86 % yield). Elemental analysis, calc. for
C42H55Au2F6P2Sb (26) (%): C, 40.31; H, 4.43. Found: C, 40.12; H, 4.67.
1H NMR (300 MHz, CD2Cl2): δ (ppm) = 7.89-7.78 (m, 2 H; ArH); 7.59-
7.47 (m, 4 H; ArH), 7.44-7.29 (m, 6 H; ArH), 7.25-7.17 (m, 2 H; ArH),
7.14-7.06 (m, 4 H; ArH), 1.91 (s, 1 H; Au2µ-C≡CH), 1.37 (s, 9 H; tert-butyl
CH3), 1.32 (s, 9 H; tert-butyl CH3) (see Fig. S36). 13C NMR (75 MHz,
CD2Cl2): δ (ppm) = 149.55, 149.41, 143.41, 143.34, 138.52, 134.42,
133.70, 133.62, 131.49, 129.92, 129.34, 128.23, 127.89, 127.82, 125.84,
125.39, 96.37, 38.42, 38.18, 31.17, 31.10 (see Fig. S37). 13C Dept-135
NMR (75 MHz, CD2Cl2): Positive Signals: δ (ppm) = 134.42, 134.40,
133.69, 133.62, 131.49, 131.48, 129.92, 129.34, 128.23, 127.89, 127.82,
31.17, 31.10 (see Fig. S38). 31P NMR (CD2Cl2): δ (ppm) = 62.46 (s,
phosphine ligands) (see Fig. S39). ESI-MS (+MS) m/z: 1015.3 amu for
Compound 21: 1H NMR (300 MHz, CD2Cl2): δ (ppm) = 3.32 (s, 4 H;
CH2-butyne), 2.38 (t, 8 H; CH2-butyl), 1.41-1.19 (m, 16 H; CH2-buyl), 0.86
(t, 12 H; CH3-group) (see Fig. S23). 13C NMR (75 MHz, CD2Cl2): δ (ppm)
= 79.74, 53.93, 42.21, 30.18, 21.10, 14.27 (see Fig. S24). 13C Dept-135
NMR (75 MHz, CD2Cl2): δ (ppm) = Negative Signals: 14.27 for (CH3-
group); Positive Signals: 53.91, 42.19 and 30.16 for (CH2-buyl), 21.94 for
(CH2-butyne) (see Fig. S25). GC-MS m/z: 308.2 amu for [C20H40N2 (21)]
(see Fig. S26 for details).
- +
[C42H55Au2F6P2Sb (26) - SbF6 ] (see Fig. S42). ESI-MS (-MS) m/z: 234.6
Compound 25: 1H NMR (300 MHz, CD2Cl2): δ (ppm) = 7.48-7.18 (m, 20
H; Ph -ring), 3.75 and 3.66 (s, 8 H; CH2-benzylamine for Z and E
isomers), 3.32 and 3.22 (s, 4 H; CH2-butyne for Z and E isomers) (see
Fig. S27). 13C NMR (75 MHz, CD2Cl2): δ (ppm) = 139.60 and 139.40
(quaternary C -Ph -ring for Z and E isomers), 129.44, 128.70, 127.52,
80.32 and 73.60 (quaternary C-butyne for Z and E isomers), 58.09 and
57.82 (CH2-benzylamine for Z and E isomers), 41.86 and 41.50 (CH2-
butyne for Z and E isomers) (see Fig. S28). 13C Dept-135 NMR (75 MHz,
CD2Cl2): Positive Signals: δ (ppm) = 129.44, 128.70, 127.52 (CH, Ph-
ring); Negative Signals: 58.09 and 57.821 (CH2-benzylamine for Z and E
isomers), 41.86 and 41.50 (CH2-butyne for Z and E isomers) (see Fig.
S29). GC-MS m/z: 444.2 amu for [C32H32N2 (25)] (see Fig. S30 for
details). Elemental analysis, calc. for C32H32N2 (25) (%): C, 86.44; H,
7.25; N, 6.30. Found: C, 85.36; H, 7.46; N, 6.17.
and 236.6 amu for anionic counter ion [SbF6]- of complex 26 (see Fig.
S42).
Isolation of cationic [(σ,π)](L2-Au)2(µ-acetylene)[NTf2] complex 27: A
mixture of complex [Au(L2)(NTf2)] (2) (0.143 g, 0.15 mmol) and
ethynyltrimethylsilane (4) (0.044 g, 0.45 mmol) was dissolved in
dichloromethane (2 ml). The solution was stirred at 60 ºC under argon
atmosphere. The stirring was maintained for 72 h. Then, the resulting
mixture was diluted with other 2 ml of CH2Cl2 and filtered. n-Hexane (2
ml) was added carefully over the supernatant and after standing for 48 h
at RT, a colourless crystalline material suitable for X-ray crystallography
corresponding to complex 27 was obtained. The crystals were collected
by filtration, washed with cold n-hexane and dried at RT under vacuum
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10.1002/chem.201605269
Chemistry - A European Journal
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(0.088 g, 71 % yield). Elemental analysis, calc. for C70H99Au2F6NO4P2S2
(27) (%): C, 50.88; H, 6.04; N, 0.85; S, 3.88. Found: C, 50.86; H, 6.10; N,
0.89; 3.62. 1H NMR (300 MHz, CDCl3): δ (ppm) = 7.75-7.63 (m, 2 H;
ArH); 7.62-7.46 (m, 4 H; ArH), 7.20-7.10 (m, 2 H; ArH), 7.07-6.95 (s, 4 H;
ArH), 2.90 (sept, 2 H; i-PrCH), 2.24 (sept, 4 H; i-PrCH), 2.06 (m, 4 H;
CyCH), 1.95-1.60 (m, 20 H; CyCH2), 1.47 (s, 1 H; Au2µ-C≡CH), 1.45-1.10
(m, 20 H; CyCH2), 1.32 (d, 12 H; i-PrCH3), 1.22 (d, 12 H; i-PrCH3), 0.93
(d, 12 H; i-PrCH3) (see Fig. S44). 31P NMR (CDCl3): δ (ppm) = 38.74 (s,
phosphine ligands) (see Fig. S45). 19F NMR (CDCl3): δ (ppm) = - 78.58 (s,
counter ion Fluor’s) (see Fig. S46). ESI-MS (+MS) m/z: 1371.87 amu for
Langmuir 2000, 16, 2062-2067; c) G. M. Everett, L. E. Blockus, I. M.
Shepperd, Science (Washington, DC, U. S.) 1956, 124, 79.
[2]
a) L. C. S. L. Morais, L. J. Quintans-Junior, C. I. F. Franco, J. R. G. S.
Almeida, R. N. Almeida, Pharmacol., Biochem. Behav. 2004, 79, 745-
749; b) H. Szmigielska, A. Szmigielski, A. Szadowska, Pol. J.
Pharmacol. 1993, 45, 291-298; c) V. Dutt Sharma, M. A. Ilies, Med. Res.
Rev. 2014, 34, 1-44.
[3]
[4]
[5]
a) J. N. Wilson, S. M. Waybright, K. McAlpine, U. H. F. Bunz,
Macromolecules 2002, 35, 3799-3800; b) C.-J. Li, W. T. I. V. Slaven,
C.-J. Li, Y.-P. Chen, V. T. John, S. H. Rachakonda, Chem. Commun.
(Cambridge) 1998, 1351-1352.
- +
[C70H99Au2F6NO4P2S2 (27) - N(SO2CF3)2 ] (see Fig. S47). ESI-MS (-MS)
m/z: 279.76 amu for anionic counter ion [N(SO2CF3)2]- of complex 27
(see Fig. S47).
a) C. R. Gillett, O. S. Hellwig, ACETYLENE-GAS GENERATOR 1898,
US603506A, CAPLUS AN 1906:71268(Patent); b) A. Rosenberg,
APPARATUS FOR THE GENERATION OF ACETYLENE GAS 1906,
US824509A, CAPLUS AN 1906:52518(Patent).
Isolation of cationic [(σ,π)](L1-Au)2(µ-I)[SbF6] complex 31: A mixture
of complex [Au(L1)(CH3CN)][SbF6] (1) (0.116 g, 0.15 mmol) and 1-iodo-
2-(trimethylsilyl)acetylene (0.10 g, 0.45 mmol) was dissolved in
dichloromethane (2 ml). The solution was stirred at 40 ºC under argon
atmosphere. The stirring was maintained for 48 h. Then, the resulting
orange mixture was diluted with other 2 ml of CH2Cl2, filtered and the
supernatant was covered carefully with a layer of 1.5 ml of n-hexane. A
colourless crystalline material suitable for X-ray crystallography
corresponding to complex 31 was formed upon standing for 30 h at -30
ºC. The solid was collected by filtration, washed with cold n-hexane and
dried under vacuum (0.093 g, 92 % yield). Elemental analysis, calc. for
C40H54Au2F6IP2Sb (31) (%): C, 35.50; H, 4.02. Found: C, 35.47; H, 4.27.
1H NMR (300 MHz, CD2Cl2): δ (ppm) = 7.90-7.78 (m, 2 H; ArH); 7.60-
7.42 (m, 6 H; ArH), 7.37-7.28 (m, 4 H; ArH), 7.27-7.20 (m, 2 H; ArH),
7.11-7.063 (m, 4 H; ArH), 1.37 (s, 9 H; tert-butyl CH3), 1.31 (s, 9 H; tert-
butyl CH3) (see Fig. S61). 13C NMR (75 MHz, CD2Cl2): δ (ppm) = 149.57,
149.39, 143.32, 143.23, 134.07, 134.03, 133.81, 133.71, 131.73, 131.70,
129.94, 129.64, 128.62, 128.03, 127.93, 125.52, 124.91, 39.06, 38.75,
31.15, 31.07 (see Fig. S62). 13C Dept-135 NMR (75 MHz, CD2Cl2):
Positive Signals: δ (ppm) = 134.07, 134.04, 133.81, 133.71, 131.73,
131.70, 129.94, 129.64, 128.62, 128.03, 127.94, 31.15, 31.07 (see Fig.
S63). 31P NMR (CD2Cl2): δ (ppm) = 66.58 (s, phosphine ligands) (see Fig.
a) C. Wei, C.-J. Li, J. Am. Chem. Soc. 2003, 125, 9584-9585; b) C. Wei,
Z. Li, C.-J. Li, Synlett 2004, 1472-1483; c) B. Yan, Y. Liu, Org. Lett.
2007, 9, 4323-4326; d) J. Li, L. Liu, D. Ding, J. Sun, Y. Ji, J. Dong, Org.
Lett. 2013, 15, 2884-2887; e) S. Shi, T. Wang, V. Weingand, M.
Rudolph, A. S. K. Hashmi, Angew. Chem., Int. Ed. 2014, 53, 1148-
1151; f) J. Li, M. Rudolph, F. Rominger, J. Xie, A. S. K. Hashmi, Adv.
Synth. Catal. 2016, 358, 207-211; g) A. Grirrane, E. Alvarez, H. Garcia,
A. Corma, Chem. - Eur. J. 2016, 22, 340-354; h) A. Grirrane, E. Alvarez,
H. Garcia, A. Corma, Chem. - Eur. J. 2014, 20, 14317-14328; i) A.
Grirrane, E. Alvarez, H. Garcia, A. Corma, Angew. Chem., Int. Ed. 2014,
53, 7253-7258.
[6]
a) A. S. K. Hashmi, G. J. Hutchings, Angew. Chem., Int. Ed. 2006, 45,
7896-7936; b) A. Arcadi, Chem. Rev. (Washington, DC, U. S.) 2008,
108, 3266-3325; c) S. Diez-Gonzalez, N. Marion, S. P. Nolan, Chem.
Rev. (Washington, DC, U. S.) 2009, 109, 3612-3676; d) D. J. Gorin, B.
D. Sherry, F. D. Toste, Chem. Rev. (Washington, DC, U. S.) 2008, 108,
3351-3378; e) A. Fuerstner, P. W. Davies, Angew. Chem., Int. Ed. 2007,
46, 3410-3449; f) D. Pflaesterer, A. S. K. Hashmi, Chem. Soc. Rev.
2016, 45, 1331-1367.
[7]
a) A. Grirrane, H. Garcia, A. Corma, E. Alvarez, ACS Catal. 2011, 1,
1647-1653; b) A. Grirrane, H. Garcia, A. Corma, E. Alvarez, Chem. -
Eur. J. 2013, 19, 12239-12244; c) R. E. M. Brooner, R. A. Widenhoefer,
Angew. Chem., Int. Ed. 2013, 52, 11714-11724; d) A. M. Asiri, A. S. K.
Hashmi, Chem. Soc. Rev. 2016, 45, 4471-4503.
-
S64). ESI-MS (+MS) m/z: 1117.3 amu for [C40H54Au2F6IP2Sb (31) - SbF6
]
+ (see Fig. S65). ESI-MS (-MS) m/z: 234.6 and 236.6 amu for anionic
counter ion [SbF6]- of complex 31 (see Fig. S65).
[8]
[9]
N. Mezailles, L. Ricard, F. Gagosz, Org. Lett. 2005, 7, 4133-4136.
a) A. S. K. Hashmi, E. Kurpejovic, W. Frey, J. W. Bats, Tetrahedron
2007, 63, 5879-5885; b) A. Zeiler, M. J. Ziegler, M. Rudolph, F.
Rominger, A. S. K. Hashmi, Adv. Synth. Catal. 2015, 357, 1507-1514.
Acknowledgements
[10] a) A. S. K. Hashmi, T. Lauterbach, P. Noesel, M. H. Vilhelmsen, M.
Rudolph, F. Rominger, Chem. - Eur. J. 2013, 19, 1058-1065; b) A. S. K.
Hashmi, I. Braun, P. Noesel, J. Schaedlich, M. Wieteck, M. Rudolph, F.
Rominger, Angew. Chem., Int. Ed. 2012, 51, 4456-4460; c) I. Braun, A.
M. Asiri, A. S. K. Hashmi, ACS Catal. 2013, 3, 1902-1907.
Financial support by the Spanish Ministry of Economy and
Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-R1)
and Generalidad Valenciana (Prometeo 2013-014) is gratefully
acknowledged.
[11] G. A. Olah, L. Heiliger, X. Y. Li, G. K. S. Prakash, J. Am. Chem. Soc.
1990, 112, 5991-5995.
Keywords: homogeneous catalysis • organometallic chemistry •
gold complex intermediates • tremorine • gemini surfactants
[12] M. F. Espada, J. Campos, J. Lopez-Serrano, M. L. Poveda, E.
Carmona, Angew. Chem., Int. Ed. 2015, 54, 15379-15384.
[13] A. Zhdanko, M. Stroebele, M. E. Maier, Chem. - Eur. J. 2012, 18,
14732-14744, S14732/14731-S14732/14102.
[1]
a) A. K. Cho, W. L. Haslett, D. J. Jenden, Biochem. Biophys. Res.
Commun. 1961, 5, 276-279; b) F. M. Menger, J. S. Keiper, V. Azov,
[14] A. S. K. Hashmi, Angew. Chem., Int. Ed. 2010, 49, 5232-5241.
This article is protected by copyright. All rights reserved.

10.1002/chem.201605269
Chemistry - A European Journal
FULL PAPER
Layout 1:
FULL PAPER
A. Grirrane,* E. Álvarez, H.
García,* A. Corma*
Tremorine and precursors of
Gemini surfactants have been
synthesized in one pot, three-
steps, double catalytic A3-
coupling reaction. The formed
cationic ethynyl-bridged di-
Au(I)-L(Buchwald-type biaryl
phosphane) intermediates
whose isolation lends support
to the proposed double A3-
coupling mechanism are fully
characterized by structural and
spectroscopic properties.
Page No. – Page No.
Preparation of Tremorine and
Gemini Surfactant Precursors
using Cationic Ethynyl-
Bridged Digold Catalysts
This article is protected by copyright. All rights reserved.