Deactivation of gold(i) catalysts in the presence of thiols and amines-characterisation and catalysis

Article abstract of DOI:10.1039/c3dt50653c

Thiols and amines, which are common heteroatom nucleophiles in gold-catalysed reactions, are known to dampen the reactivity of gold catalysts. In this article, the identity and activity of gold(i) catalysts in the presence of thiols and amines is investig

Full text of DOI:10.1039/c3dt50653c

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Deactivation of gold(I) catalysts in the presence of
thiols and amines – characterisation and catalysis†
Cite this: Dalton Trans., 2013, 42, 9645
Paul C. Young, Samantha L. J. Green, Georgina M. Rosair and Ai-Lan Lee*
Thiols and amines, which are common heteroatom nucleophiles in gold-catalysed reactions, are known
to dampen the reactivity of gold catalysts. In this article, the identity and activity of gold(I) catalysts in the
presence of thiols and amines is investigated. In the presence of thioacid, thiophenol and thiol, digold
with bridging thiolate complexes [{Au(L)}2(μ-SR)][SbF6] are formed and have been fully characterised by
NMR and X-ray crystallography. In the presence of amines and anilines, complexes [LAu-NH2R][SbF6] are
formed instead. All new isolated gold complexes were investigated for their catalytic activity in order to
compare the level of deactivation in each species.
Received 8th March 2013,
Accepted 4th May 2013
DOI: 10.1039/c3dt50653c
www.rsc.org/dalton
1 Introduction
In less than a decade, homogenous gold catalysis has under-
gone a transformation from rarity to an incredibly active and
rapidly evolving field of research.1 Its popularity is partly result
of the excellent selectivity and efficiency of gold catalysts as
π-Lewis acids for activating C–C π bonds, and also the ability
to tune gold catalysts in order to vary the reactivity and selecti-
vity of the reactions.1 One of the research efforts within our
group is to explore the diverse chemistry of gold-catalysed reac-
tions with cyclopropenes,2,3 allenes4 and allylic alcohols.5
Within this context, we have used alcohols,2a,b,4,5 amines2f and
thiols2f as nucleophiles in gold-catalysed reactions, and have
observed that the presence of these nucleophiles can dramati-
cally alter the reactivity as well as selectivity of the gold cata-
lysts. For example, we have previously observed that although
gold(I)-catalysed reactions can work very well with alcohol
nucleophiles1l (Scheme 1, eqn (1)),2a,b,4a the equivalent reac-
tion of anilines with cyclopropenes do not proceed to com-
pletion (Scheme 1, eqn (2)),2f presumably due to deactivation
of the catalyst by the N-nucleophile. On the other hand,
despite the initial assumption that S-nucleophiles would fare
worse than N-nucleophiles (as they are known strong coordina-
tors to gold),6 reactions with thiols do proceed to completion.7
However, reactions are clearly slower with more nucleophilic
S-nucleophiles (progressively slower from thioacid→thiophe-
nol→alkyl thiols, Scheme 1, eqn (3)).2f Furthermore, function-
alities such as furans2c and alcohols,2a,b which usually react
Scheme 1 Previous work: gold(I) catalysed reactions of cyclopropenes with (1)
alcohols; (2) anilines; (3) thiols.
with cyclopropenes within minutes under gold(I)-catalysis, are
no longer reactive in the presence of thiols.2f
In order to explain these observations, we were keen to elu-
cidate the structure and activity of the actual gold(I) species
involved in these reactions.8,9 So far, not much effort has been
made to isolate, characterise10 and investigate the catalytic pro-
perties of these species. Nevertheless, heteroatom nucleophiles
such as RSH and RNH2 are commonly used in gold-catalysed
reactions,1a,d so a better understanding of the nature and
activity of gold(I) catalysts in the presence of these nucleo-
philes will be invaluable if we are to better understand the
mechanisms of gold-catalysed reactions.11
In a recent publication describing the gold(I)-catalysed reac-
tions of thiols with cyclopropenes, we briefly disclosed that
[{Au(L)}2(μ-SR)][SbF6] species are likely to be the thiol-deacti-
vated complexes formed in the reaction.2f,12 In this article, we
present our full investigations into the nature of the gold-
Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United
Kingdom. E-mail: A.Lee@hw.ac.uk; Tel: +44 (0)131 4518030
†Electronic supplementary information (ESI) available: 1H, 13C and 31P NMR
spectra of all new compounds. CCDC 914704–914708. For ESI and crystallo-
graphic data in CIF or other electronic format see DOI: 10.1039/c3dt50653c
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Scheme 2 Characterised deactivated gold(I) complexes 6a–c and 7a–c.
species formed in the presence of thiols, and compare these
with species formed in the presence of amines. Solution state
NMR studies are presented, along with the isolation and
characterisation of the thiol-deactivated species [{Au(L)}2-
(μ-SR)][SbF6] 6a–c and amine-deactivated species [LAu-NH2R]-
[SbF6] 7a–c by NMR spectroscopy and X-ray crystallography
(Scheme 2). Complexes of type [{Au(L)}2(μ-SR)][SbF6] and [LAu-
NH2R][SbF6] have never been studied in the context of cata-
lysis, so 6a–c and 7a–c were investigated for their catalytic
activity in an effort to compare the level of deactivation in each
of these species.
2 Results and discussion
2.1 Gold(I) catalyst with thiols, thiophenols and thioacids
Our investigations commenced with NMR studies of Echavar-
ren catalyst13 8 in the presence of sulfur nucleophiles RSH.
Catalyst 8 is a commonly used, commercially available Au(I)
catalyst and was chosen for our studies because it was pre-
viously found to have the best catalytic activity in the presence
of thiols.2f The second reason for using 8 is one of practicality:
the displacement of the MeCN in the complex by an S-nucleo-
Fig. 1 31P and 1H NMR analysis of a 20 : 1 mixture of 8 and RSH.
1
phile can be clearly monitored by H NMR spectroscopy, indi-
Au centre through a weak Au(I)–arene interaction (Au–arene
distances of 3.218/3.173, 3.212/3.183 and 3.218/3.204 Å for 6a,
6b and 6c respectively),16 an interaction which is also observed
in the parent Echavarren catalyst 8.13 The 31P NMR shift moves
more upfield the more nucleophilic the parent thiol RSH
(63.61, 62.96, 62.68 for 6a, 6b and 6c respectively), consistent
with a progressively more electron rich Au(I) centre.
A plausible mechanism for the formation of complexes
6a–c is shown in Scheme 3. Acetonitrile is displaced by RSH to
form 9, followed by loss of H+ to form 10. Complex 10 is
nucleophilic and reacts with 8 to form the observed digold
complex 6. Evidence for the reversibility of this process is dis-
cussed in section 2.3.
cated by the appearance of unbound MeCN in the solution.
When catalyst 8 was subjected to 20 equiv. of an alkyl thiol,
thiophenol or thiobenzoic acid (to replicate the ratio which
would be present in a typical 5 mol% gold(I)-catalysed reac-
tion), an almost instantaneous conversion to new complexes
was observed by 31P NMR analysis (Fig. 1, top), backed up by
the appearance of unbound MeCN in the 1H NMR spectra
(Fig. 1, bottom).
The analyses were repeated with 1 : 1 equiv. of 8 with the
same thiols (see ESI†), and crystallisation by vapour diffusion
method (CDCl3–hexane) produced single crystals which were
isolated and characterised by X-ray crystallography (Fig. 2). All
three are revealed to be digold with bridging thiolate com-
plexes14 [{Au(L)}2(μ-SR)][SbF6] 6a, 6b and 6c, which are now
1
2.2 Gold(I) catalyst with amines and anilines
fully characterised by X-ray crystallography, H, 31P, 13C NMR,
IR and HRMS (see section 4.2). Crystals of 6a–6c are all air- Having evaluated the identity of the gold complexes in the
stable over a period of >3 months. There is no formal Au–Au presence of thiols, we next carried out a similar study with
bond,15 although the intramolecular Au–Au distance of N-nucleophiles. With nBuNH2, p-MeO-C6H4NH2 (p-anisidine)
3.3987(3), 3.4066(4) and 3.4363(3) Å in 6a, 6b and 6c respect- and aniline, a clear shift in the 31P NMR peak is observed
ively may indicate weak aurophilic interactions (accepted range (Fig. 3), once again, accompanied by the appearance of
of aurophilic Au–Au distances ca. 2.85–3.50 Å).16 In addition, unbound MeCN in the 1H NMR spectra (see ESI†). The 31P
the aromatic ring from the ligand appears to be stabilising the NMR shift appears to move more upfield the better the parent
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Fig. 3 31P and 1H NMR analysis of a 1 : 1 mixture of 8 and RNH2.
Fig. 2 X-ray structures of 6a, 6b and 6c. SbF6− counterion is omitted for clarity
and only one independent molecule shown for 6b. 6a: Au–S 2.3233(10), Au’–S
2.3262(10) Å, Au–S–Au’ 93.94(3)°; 6b Au’–S 2.3190(16), Au–S 2.3362(16) Å,
Au–S–Au’ 94.07(5)°; 6c Au’–S 2.3196(9), Au–S 2.3285(10) Å; Au–S–Au’
95.34(3)°.
dampening of reactivity in some gold(I)-catalysed reactions
with amines and anilines (e.g. eqn (2), Scheme 1).17 The inter-
molecular Au–Au distances are 7.5686(4), 8.1290(3) and
7.6009(4) Å respectively for 7a, 7b and 7c, showing that there
are no significant aurophilic interactions. Weak Au–arene
stabilisation of the Au centre by the ligand is once again
evident in all of these structures (Au–arene distances of 3.154,
3.162 and 3.172 Å in 7a, 7b and 7c respectively). This inter-
action is thought to render extra stability to the gold complexes
in this study, and allows them to be stable (e.g. 7c is air stable
>6 months upon standing on the bench) and isolable for
characterisation. In contrast, subsequent attempts to grow the
corresponding NHC (IPr) versions of these complexes in the
same manner led to decomposition.
Scheme 3 Plausible mechanism for the formation of 6a–c.
While amines and anilines clearly react with the gold cata-
RNH2 nucleophile, consistent with a progressively more elec- lyst to form [LAu-NH2R][SbF6], the less nucleophilic amide
tron rich Au(I) centre. (PhCONH2) and protected amines BocNH2 and TsNH2 do not
In order to characterise these species, single crystals were show the same reactivity. When a 1 : 1 mix of catalyst 8 and
grown by vapour diffusion (CDCl3–hexane). In stark contrast to these N-nucleophiles are monitored by NMR, no displacement
1
the digold species with thiols, single crystal X-ray crystallogra- of MeCN is seen in the H NMR spectra, and no appreciable
phy reveals monogold [LAu-NH2R][SbF6] species 7a, 7b and 7c shift in the 31P NMR is observed. While this observation does
(Fig. 4). These species are more than likely to be the cause of not rule out the formation of small amounts of [LAu-NH2R]-
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respectively), we set out to study the catalytic activity of these
species. Complexes of type [{Au(L)}2(μ-SR)][SbF6] and [LAu-
NH2R][SbF6] have never been studied in the context of cataly-
sis, so it will be useful to know whether these complexes are
completely inactive or whether they can competently release
active catalyst in situ. For example, in related work, formation
of carbon bridged digold species have been shown to be inhibi-
tory to catalysis as they are in competition with the product
yielding protodeauration step.19 Related [{Au(L)}2(μ-OH)][X]
complexes have also been reported and utilised as active cata-
lysts.20 In addition, we were also keen to investigate the degree
of deactivation in 6a–c and 7a–c relative to each other.
Firstly, [{Au(L)}2(μ-SR)][SbF6] was investigated in a reaction
with RSH as a nucleophile, in order to ascertain whether it
could be the actual catalytically active species in these reac-
tions. When complex 6b was used as a catalyst in a reaction of
a cyclopropene21,22 with thiophenol,2f the production of the
gold(I) catalysed product 12 is nowhere near as good as with
the parent catalyst 8 (Table 1, entry 3 vs. 1). Instead, the back-
ground (non gold(I)-catalysed) addition reaction to form cyclo-
propane 13 dominates. This initially suggests that 6b is most
likely not the active catalyst in the reaction shown in entry 1,
Table 1, and is instead a deactivation pathway in gold(I)-cata-
lysed reactions with thiols.
However, this result was initially rather puzzling as the pro-
cedure in entry 1 involves pre-mixing catalyst 8 with PhSH in
CH2Cl2 before addition to cyclopropene substrate 11: this
forms 6b in situ almost instantaneously (see section 2.1). One
difference between using isolated 6b (entry 3) and 6b made
in situ from 8 (entry 1) is the presence of H+, released upon for-
mation of 6b from 8 (Scheme 3).23 If the formation of 6 from 8
is indeed reversible, then the presence of H+ may allow for
more active catalyst to be in solution for catalysis, whereas the
absence of residual H+ (entry 3) causes the equilibrium to be
towards inactive 6. Indeed, when 6b is used with added H+, the
gold(I)-catalysed product 12 is once again the major product
(entry 4). A control reaction using Brønsted acid alone (entry 5)
Fig. 4 X-ray structures of 7a, 7b and 7c. SbF6− counterion is omitted for clarity.
7a: Au–N 1 2.1197(17) Å, N–Au–P 172.28(6)°; 7b Au–N 2.116(4) Å, N–Au–P
175.76(11)°; 7c Au–N 2.097(2) Å, N–Au–P 175.22(8)°.
Table 1 Comparison of the reaction of cyclopropene 11 with thiophenol in
the presence of 8 and 6b; and control reactions
Scheme 4 Formation of complex 7.
[SbF6] in solution, the equilibrium firmly lies towards 8 (in
Scheme 4).18 This observation is as expected as it reflects the
catalytic activity of gold(I) in the presence of N-nucleophiles:
protected amines such as Boc- and Ts-amines are more com-
monly used nucleophiles.1a,d
Entry
Catalyst
mol%
12 : 13a
1b
2
3
4
5
8
5
12 only
13 only
1 : 20
2 : 1
13 only
No catalyst
6b
6b + HOTf
HOTf
N/A
2.5
2.5
2.5
2.3 Catalytic studies with 6a–c and 7a–c
1
a Determined by H NMR analysis of crude reaction mixture. b 8 is pre-
Having established, isolated and characterised the gold(I)
species in the presence of RSH and RNH2 (6a–c and 7a–c mixed with PhSH in CH2Cl2 before addition to 11.
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shows that the reaction to form 12 in entry 4 is gold(I)- basicity going from thioacid→thiophenol→alkyl thiol to form
catalysed. 6a, 6b, and 6c respectively is likely to push the equilibrium
Next, [LAu-NH2R][SbF6] complex 7b was investigated in a towards 6 (Scheme 3), resulting in a lower concentration of
reaction where RNH2 is a nucleophile. When complex 7b was active catalyst in the reaction. Complexes 7a–c show a similar
used as a catalyst in a reaction of a cyclopropene with p-anisi- trend (entries 4–6). The conversions, reflecting the catalytic
dine, the conversion to 15 is 15% with 7b compared to 27% activity, also decrease going from 7a→7b→7c, reflecting
using catalyst 8 (entries 1–2, Table 2). As expected, addition of the increasing Lewis basicity of the parent aniline→
acid does not improve the conversion to desired product (entry anisidine→amine.
3, Table 2 vs. entry 4, Table 1) as this time it does not affect the
equilibrium between 8 and 7 (Scheme 4). 31P NMR analysis of
a 1 : 1 : 1 ratio of 8 : 7b : p-anisidine in CD2Cl2 clearly shows
immediate formation of 7b in situ, which persists after
3 Conclusions
2 hours.
In conclusion, we found that thiols deactivate Au(I) catalysts by
Finally, the gold(I)-catalysed reaction of alcohols with cyclo- forming digold with bridging thiolate complexes [{Au(L)}2-
propenes (eqn (1), Scheme 1) was used to compare the catalytic (μ-SR)][SbF6] (e.g. 6a–c, which have now been fully character-
activities (or rather, the amount of dampening of catalytic ised). These species are in equilibrium with the active gold
activity) of complexes 6a–c and 7a–c. We have previously catalysts (Scheme 3) and the presence of residual H+ in situ is
shown that this reaction goes to full conversion with a variety required for enough active catalyst to be in solution for cataly-
of commercial gold(I) catalysts.2a,b In comparison, complexes sis, whereas the absence of residual H+ causes the equilibrium
6a–c do not produce full conversions to product 16 (entries to shift towards the inactive complex 6. In addition, the more
1–3, Table 3). The conversions are moderate to low: 47%, 25% nucleophilic the parent thiol (RSH), the less active the result-
and <5% respectively for 6a, 6b, and 6c. This observed trend ing gold(I) complex, presumably because this pushes the equi-
neatly reflects the Lewis basicity of the original RSH thiol librium increasingly towards the inactive complex [{Au(L)}2-
employed to form the complexes 6a–c. The increasing Lewis (μ-SR)][SbF6]. In contrast, amines deactivate Au(I) catalysts by
forming the monogold species [LAu-NH2R][SbF6] (e.g. 7a–c).
The difference in behaviour between gold(I) complexes in
Table 2 Comparison of the reaction of cyclopropene 14 with p-anisidine in the
thiols and amines is possibly due to the difference in acidity of
presence of 8 and 7b
the proton in 9 vs. 7. We hope that these results shed some
light on the identity as well as activity of gold(I) catalysts when
thiols and amines are used as nucleophiles in gold(I)-catalysed
reactions.
Conversiona (%)
4 Experimental
Entry
Catalyst
mol%
4.1 General experimental section
1
2
3
8
7b
5
5
27
15
13
All reactions were carried out in air without the need for pre-
dried solvents, in order to replicate the reaction conditions in
gold(I) catalysed reactions, which are typically carried out in
7b + HOTf
5 + 5
a Determined by 1H NMR of crude reaction mixture.
1
air. H NMR spectra were recorded on Bruker AV 300 and AV
400 spectrometers at 300 and 400 MHz respectively and refer-
enced to residual solvent. 13C NMR spectra were recorded
using the same spectrometers at 75 and 100 MHz respectively.
Chemical shifts (δ in ppm) were referenced to tetramethyl-
silane (TMS) or to residual solvent peaks (CDCl3 at δ = 7.26).
For 31P NMR, chemical shifts were referenced against H3PO4 at
δ 0 ppm. J values are given in Hz and s, d, dd, t, q and m
abbreviations correspond to singlet, doublet, doublet of
doublet, triplet, quartet and multiplet. Mass spectrometry data
was acquired at the EPSRC UK National Mass Spectrometry
Facility at Swansea University. Infrared spectra were obtained
on Perkin-Elmer Spectrum 100 FT-IR Universal ATR Sampling
Accessory, deposited neat or as a chloroform solution to a
diamond/ZnSe plate. Elemental analyses were determined by
the departmental service (HWU). Flash column chromato-
graphy was carried out using Matrix silica gel 60 from Fisher
Table 3 Comparison of catalytic activity of 6a–c and 7a–c
Entry
Catalyst
Conversionb (%)
1
2
3
4
5
6
6a
6b
6c
7a
7b
7c
47
25
<5
47
43
34
a 5 mol% with respect to gold, i.e. 2.5 mol% for digold species 6a–c.
b Determined by 1H NMR analysis of crude reaction mixture.
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Chemicals and TLC was performed using Merck silica gel 60 (CH2), 31.0 (d, J (13C–31P) = 6.8 Hz, CH3), 22.0 (CH2), 13.9
F254 precoated sheets and visualised by UV (254 nm) or (CH3). 31P NMR (162 MHz, CDCl3) δ = 62.75. IR νmax/cm−1
stained by the use of aqueous acidic ceric ammonium 2956 m, 2901 w, 2872 w, 1462 m, 1441 m, 1430 m. HRMS
molybdate. Petrol ether refers to petroleum ether (40–60 °C). (NESI): m/z calcd for C44H63Au2OP2S: 1079.3451 [M − SbF6]+;
Dichloromethane (DCM) was purchased from Fisher and used found: 1079.3434.
without further purification. All nucleophiles were purchased
Compound 7a. Complex 7a was obtained as white crystals
from Sigma-Aldrich or Acros, and used without further (21.0 mg, 0.025 mmol, 98%). M.p. 185 °C (decomposes).
purification.
1H NMR (400 MHz, CDCl3) δ = 7.85 (td, J = 7.9 Hz, 1.8, 1H,
Ar-H), 7.65–7.51 (m, 5H, Ar-H), 7.34–7.24 (m, 5H, Ar-H),
7.20–7.12 (m, 1H, Ar-H), 7.01 (d, J = 7.6 Hz, 2H, Ar-H), 4.67 (br.
s, 2H, NH2), 1.36 (d, J = 16.1 Hz, 18H, C(CH3)3). 13C NMR
4.2 General experimental procedure for crystals 6a–c and 7a–c
Catalyst 8 and the nucleophile RSH or RNH2 (1 equiv.) were (100 MHz, CDCl3) δ = 149.1 (d, J (13C–31P) = 12.1 Hz, C), 144.0
added to an NMR tube, and dissolved in CDCl3 (0.75 mL). H (d, J (13C–31P) = 6.3 Hz, C), 133.4 (CH), 133.3 (d, J (13C–31P) =
1
and 31P NMR were obtained from the resulting crude mixture. 10.1 Hz, CH), 131.5 (d, J (13C–31P) = 2.1 Hz, CH), 130.5 (CH),
The solution was then decanted into a vial, and crystals were 129.8 (CH), 129.2 (CH), 127.6 (d, J (13C–31P) = 7.3 Hz, CH),
grown by vapour diffusion from CDCl3–hexane. The crystals were 127.2 (CH), 126.3 (broad, C), 125.1 (d, J (13C–31P) = 48.5 Hz, C),
washed with hexane and dried under reduced pressure.
121.7 (broad, CH), 38.0 (d, J (13C–31P) = 26.2 Hz, C), 30.9 (d,
Compound 6a. Complex 6a was obtained as yellow crystals J (13C–31P) = 6.1 Hz, CH3). 31P NMR (162 MHz, CDCl3) δ =
(9.3 mg, 0.0068 mmol, 26%). M.p. 195 °C (decomposes). 58.86. IR νmax/cm−1 3314 w, 3266 m, 3016 w, 2954 w, 1605 m,
1H NMR (300 MHz, CDCl3) δ 7.94–7.80 (m, 4H, Ar-H), 1590 m, 1496 m, 1474 m, 1462 m. HRMS (NESI): m/z calcd for
7.64–7.11 (m, 19H, Ar-H), 1.30 (d, J = 16.0, 36H, C(CH3)3); C26H34AuNP: 588.2089 [M − SbF6]+; found: 588.2089. Anal.
13C NMR (100 MHz, CDCl3) δ = 189.5 (C), 149.2 (d, J (13C–31P) = Calc. for C26H34AuF6NPSb: C, 37.88; H, 4.17; N, 1.70. Found:
13.5 Hz, C), 143.1 (d, J (13C–31P) = 6.8 Hz, C), 138.3 (C), 134.5 C, 37.88; H, 4.13; N, 1.34.
(d, J (13C–31P) = 11.8 Hz, CH), 133.9 (CH), 133.3 (CH) (d,
Compound 7b. Complex 7b was obtained as white crystals
J (13C–31P) = 7.7 Hz, CH), 131.4 (CH), 129.7 (CH), 129.4 (CH), (22.1 mg, 0.026 mmol, 99%). M.p. 173 °C (decomposes).
129.1 (d, J (13C–31P) = 16.1 Hz, CH), 128.9 (CH), 128.7 (CH), 1H NMR (300 MHz, CDCl3) δ = 7.90–7.81 (m, 1H, Ar-H),
128.3 (CH), 128.0 (CH), 127.8 (d, J (13C–31P) = 7.0 Hz, CH), 7.63–7.50 (m, 4H, Ar-H), 7.36–7.22 (m, 4H, Ar-H), 6.96 (d, J =
125.4 (d, J (13C–31P) = 45.0 Hz, C), 38.2 (d, J (13C–31P) = 23.8 Hz, 8.9 Hz, 2H, Ar-H), 6.80 (d, J = 8.9 Hz, 2H, Ar-H), 4.57 (br s, 2H,
C), 30.8 (d, J (13C–31P) = 6.7 Hz, CH3). 31P NMR (121 MHz, NH2), 3.78 (s, 3H, OCH3), 1.38 (d, J(1H–31P) = 16.1 Hz, 18H, C
CDCl3) δ = 63.65. IR νmax/cm−1 3056 w, 2955 m, 2853 w, (CH3)3). 13C NMR (101 MHz, CDCl3) δ = 157.7 (broad, C), 149.2
1673 m, 1615 w, 1602 w, 1472 m. HRMS (NESI): m/z calcd for (d, J (13C–31P) = 12.5 Hz, C), 144.0 (d, J (13C–31P) = 6.5 Hz,),
C47H59Au2OP2S: 1127.3087 [M − SbF6]+; found: 1127.3084.
133.4 (d, J (13C–31P) = 6.0 Hz, CH), 133.3 (d, J (13C–31P) = 10.3
Compound 6b. Complex 6b was obtained as white crystals Hz, CH), 131.4 (d, J (13C–31P) = 2.2 Hz, CH), 130.5 (CH), 129.2
(8.4 mg, 0.0065 mmol, 97%). M.p. 184 °C (decomposes). 1H (CH), 127.6 (d, J (13C–31P) = 7.4 Hz, CH), 127.2 (CH), 125.1
NMR (300 MHz, CD2Cl2) δ 7.93–7.84 (m, 2H, Ar-H), 7.62–7.45 (d, J (13C–31P) = 48.4 Hz, C), 123.1 (broad, C), 114.9 (CH), 114.9
(m, 6H, Ar-H), 7.35–7.16 (m, 11H, Ar-H), 7.15–7.09 (m, 4H, (CH), 55.7 (CH3), 38.0 (d, J (13C–31P) = 26.3 Hz, C), 30.9 (d,
Ar-H), 1.37 (d, J(1H–31P) = 15.8 Hz, 36H, C(CH3)3). 13C NMR J (13C–31P) = 6.1 Hz, CH3). 31P NMR (121 MHz, CDCl3) δ =
(75 MHz, CD2Cl2) δ 149.8 (d, J(13C–31P) = 14.2 Hz, C), 143.3 (d, 58.71. IR νmax/cm−1 3312 w, 3268 w, 2960 w, 1607 w, 1577 m,
J(13C–31P) = 6.7 Hz, C), 134.4 (CH), 133.73 (d, J(13C–31P) = 7.6 1510 s, 1458 m, 1245 s. HRMS (NESI): m/z calcd for
Hz, CH), 133.72 (CH), 131.7 (CH), 129.9 (CH), 129.7 (CH), C27H36AuNOP: 618.2195 [M − SbF6]+; found: 618.2182. Anal.
129.3 (CH), 129.2 (CH), 128.5 (CH), 128.1 (CH), 128.0 (CH), Calc. for C27H36AuF6NOPSb: C, 37.96; H, 4.26; N, 1.64. Found:
127.8 (C), 127.5 (CH), 125.8 (d, J(13C–31P) = 44.3 Hz, C), 38.5 (d, C, 37.76; H, 4.25; N, 1.52.
J(13C–31P) = 23.7 Hz, C), 31.3 (d, J(13C–31P) = 6.9 Hz, CH3).
Compound 7c. Complex 7c was obtained as white crystals
31P NMR (121 MHz, CD2Cl2) δ 62.87. IR νmax/cm−1 2951 m, (19.7 mg, 0.024 mmol, 94%). M.p. 173 °C (decomposes); 1H
2886 w, 1577 m, 1469 m, 1440 m. HRMS (NESI): m/z calcd for NMR (300 MHz, CDCl3) δ = 7.86 (td, J = 7.6, 1.7 Hz, 1H, Ar-H),
C46H59Au2OP2S: 1099.3138 [M − SbF6]+; found: 1099.3137.
7.64–7.47 (m, 4H, Ar-H), 7.35–7.17 (m, 4H, Ar-H), 2.91–2.68 (m,
Compound 6c. Complex 6c was obtained as yellow crystals 4H, NH2CH2), 1.54–1.23 (m, 22H, C(CH3)3 & CH2CH2CH3), 0.90
1
(19.3 mg, 0.015 mmol, 55%). M.p. 193 °C; H NMR (300 MHz, (t, J = 7.3 Hz, 3H, CH2CH3). 13C NMR (100 MHz, CDCl3) δ =
CDCl3) δ = 7.94–7.83 (m, 2H, Ar-H), 7.61–7.09 (m, 16H, Ar-H), 149.2 (d, J (13C–31P) = 12.7 Hz, C), 143.8 (d, J (13C–31P) = 6.6 Hz,
2.65–2.50 (m, 2H, SCH2), 1.56–1.25 (m, 4H, alkyl CH2), 1.40 (d, C), 133.6 (d, J (13C–31P) = 3.2 Hz, CH), 133.3 (d, J (13C–31P) =
J = 15.7, 36H, C(CH3)3), 0.84 (t, J = 7.3, 3H, CH2CH3). 13C NMR 7.5 Hz, CH), 131.4 (d, J (13C–31P) = 2.1 Hz, CH), 130.3 (CH),
(100 MHz, CDCl3) δ = 149.3 (d, J (13C–31P) = 14.2 Hz, C), 143.1 128.9 (CH), 127.6 (d, J (13C–31P) = 7.3 Hz, CH), 127.4 (CH),
(d, J (13C–31P) = 6.7 Hz, C), 134.1 (CH), 133.3 (d, J (13C–31P) = 125.3 (d, J (13C–31P) = 47.8 Hz, C), 45.5 (CH2), 38.0 (d,
7.8 Hz, CH), 131.2 (CH), 129.6 (CH), 128.7 (CH), 128.0 (CH), J (13C–31P) = 26.3 Hz, C), 34.2 (CH2), 30.9 (d, J (13C–31P) = 6.1
127.6 (d, J (13C–31P) = 6.9 Hz, CH), 125.8 (d, J (13C–31P) = Hz, CH3), 19.7 (CH2), 13.8 (CH3). 31P NMR (121 MHz, CDCl3) δ
43.3 Hz, C), 40.1 (CH2), 38.2 (d, J (13C–31P) = 23.5 Hz, C), 32.9 = 58.30; IR νmax/cm−1 3320 m, 3276 m, 2962 m, 2902 w, 1474 s,
9650 | Dalton Trans., 2013, 42, 9645–9653
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1461 s. HRMS (NESI): m/z calcd for C24H38AuNP: 568.2402 Micromount. Diffraction data were collected at 100 K with
[M − SbF6]+; found: 568.2399. Anal. Calc. for C24H38AuF6NPSb: graphite monochromated MoKα radiation from a sealed X-ray
C, 35.84; H, 4.77; N, 1.74. Found: C, 36.13; H, 4.75; N, 1.49.
tube set at 50 kV and 35 mA. Diffraction data for 6b were col-
lected on an Agilent SuperNova, Dual, Atlas diffractometer
using Cu Kα radiation (1.5418 Å) with mirror optics. The
crystal was kept at 120.01(10) K during data collection. Using
Olex2,24 the structure was solved with the XS25 structure solu-
tion program using Direct Methods and refined with the XL25
Crystal data
Single crystal X-ray diffraction data were collected on crystals
6a, 6c, 7a–7c which were coated in Paratone-N oil and
mounted on an X8 Apex2 diffractometer with a MiTiGen
Table 4 Crystal data and structure refinements for 6a–c and 7a–c
6a
6b
6c
Empirical formula
Formula weight
Temperature/K
C
47H59OF6P2SSbAu2
C46H59Au2F6P2SSb
1335.61
120.01(10)
C44H63Au2F6P2SSb·0.5(CHCl3)
1375.31
100.15
1363.63
100(2)
Crystal system
Space group
Triclinic
P1
Monoclinic
Cc
Monoclinic
P21/n
ˉ
a/Å
b/Å
c/Å
13.4006(7)
13.5192(7)
15.7860(8)
24.6918(3)
13.08924(15)
29.3558(4)
12.0540(8)
30.084(2)
13.5903(8)
α/°
β/°
68.403(2)
80.115(2)
65.851(2)
2425.6(2)
90.0
90.7654(11)
90.0
9486.84(19)
8
1.870
90.00
96.316(3)
90.00
4898.4(5)
γ/°
Volume/Å3
Z
2
4
ρcalc mg mm−3
1.867
6.752
1.865
6.765
m/mm−1
17.388
F(000)
1316.0
5152.0
2660.0
Crystal size/mm3
2Θ range for data collection
Index ranges
0.40 × 0.40 × 0.30
2.78 to 52.74°
−16 ≤ h ≤ 16, −13 ≤ k ≤ 16,
−18 ≤ l ≤ 19
35 962
0.2426 × 0.123 × 0.056
6.017 to 152.5034°
−31 ≤ h ≤ 29, −16 ≤ k ≤ 15,
−36 ≤ l ≤ 36
77 919
0.38 × 0.32 × 0.28
2.7 to 66.64°
−18 ≤ h ≤ 18, −46 ≤ k ≤ 46,
−20 ≤ l ≤ 20
136 649
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indexes [I ≥ 2σ(I)]
Final R indexes [all data]
Largest diff. peak/hole/e Å−3
9865[R(int) = 0.0351]
9865/0/553
1.139
R1 = 0.0216, wR2 = 0.0545
R1 = 0.0259, wR2 = 0.0707
0.99/−1.48
19 283[R(int) = 0.0447]
19 283/2/1069
1.041
R1 = 0.0313, wR2 = 0.0819
R1 = 0.0315, wR2 = 0.0820
1.53/−0.91
18 698[R(int) = 0.0549]
18 698/13/600
1.081
R1 = 0.0328, wR2 = 0.0713
R1 = 0.0468, wR2 = 0.0765
4.07/−4.72
7a
7b
7c
Empirical formula
Formula weight
C
26H34NF6PSbAu
C27H36AuF6NOPSb
854.25
C24H38AuF6NPSb
804.24
824.23
Temperature/K
Crystal system
Space group
100.15
Monoclinic
P21/c
100(2)
Monoclinic
P21/c
100(2)
Monoclinic
P21/c
a/Å
b/Å
c/Å
α/°
7.5686(4)
13.1268(4)
11.7372(4)
19.9682(7)
90.00
7.6009(4)
17.4546(9)
20.8291(11)
90.00
17.7750(9)
20.5702(10)
90.00
β/°
95.628(3)
90.00
2738.4(2)
4
1.999
6.453
106.108(2)
90.00
2955.75(17)
4
1.920
5.985
98.499(2)
90.00
2748.6(2)
4
1.943
6.426
γ/°
Volume/Å3
Z
ρcalc mg mm−3
m/mm−1
F(000)
1584.0
1648.0
1552.0
Crystal size/mm3
2Θ range for data collection
Index ranges
0.43 × 0.38 × 0.26
4.58 to 72.04°
−12 ≤ h ≤ 12, −28 ≤ k ≤ 28,
−32 ≤ l ≤ 34
69 144
0.22 × 0.12 × 0.08
4.82 to 60.32°
−18 ≤ h ≤ 17, 0 ≤ k ≤ 16,
0 ≤ l ≤ 28
0.4 × 0.38 × 0.04
3.04 to 70.38°
−12 ≤ h ≤ 12, −27 ≤ k ≤ 28,
−33 ≤ l ≤ 29
82 430
Reflections collected
102 285
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indexes [I ≥ 2σ(I)]
Final R indexes [all data]
Largest diff. peak/hole/e Å−3
12 891[R(int) = 0.0376]
12 891/0/337
1.024
R1 = 0.0235, wR2 = 0.0458
R1 = 0.0324, wR2 = 0.0480
3.29/−2.04
8722[R(int) = 0.0691]
8722/2/359
1.029
R1 = 0.0294, wR2 = 0.0508
R1 = 0.0436, wR2 = 0.0546
0.72/−1.03
11 854[R(int) = 0.0375]
11 854/6/349
1.026
R1 = 0.0285, wR2 = 0.0639
R1 = 0.0466, wR2 = 0.0691
1.76/−1.80
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refinement package using least squares minimisation. All non
hydrogen atoms were refined anisotropically. All H atoms
including water were constrained to idealised geometries apart
from N bound H atoms in 7a–7c. CCDC 914704 (6a), 896069
(6b), 914705 (6c), 914706 (7a), 914707 (7b), and 914708 (7c),
contain the supplementary crystallographic data for this paper
(see Table 4 for crystal data and structure refinements).
Ed., 2008, 47, 2178; (h) D. J. Gorin, B. D. Sherry and
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General procedure for Table 1
A solution of thiophenol (1 equiv.) and catalyst (2.5 mol%) in
CH2Cl2 (0.2 mL) was added to a solution of cyclopropene 11
(1 equiv.) in CH2Cl2 (0.52 mL) at 25 °C and stirred for 30 min.
The solution was then filtered through a plug of silica with
diethyl ether, and concentrated under reduced pressure. The
1
reaction mixture was analysed by H NMR in CDCl3 to deter-
mine 12 : 13 ratio by comparison with literature known
spectra.2f
2 (a) J. T. Bauer, M. S. Hadfield and A. L. Lee, Chem.
Commun., 2008, 6405; (b) M. S. Hadfield, J. T. Bauer,
P. E. Glen and A. L. Lee, Org. Biomol. Chem., 2010, 8, 4090;
(c) M. S. Hadfield and A.-L. Lee, Chem. Commun., 2011, 47,
1333; (d) P. C. Young, M. S. Hadfield, L. Arrowsmith,
K. M. Macleod, R. J. Mudd, J. A. Jordan-Hore and A.-L. Lee,
Org. Lett., 2012, 14, 898; (e) M. S. Hadfield, L. J. Häller,
A.-L. Lee, S. A. Macgregor, J. A. T. O’Neill and A. M. Watson,
Org. Biomol. Chem., 2012, 10, 4433; (f) R. J. Mudd,
P. C. Young, J. A. Jordan-Hore, G. M. Rosair and A.-L. Lee,
J. Org. Chem., 2012, 77, 7633.
General procedure for Table 2
Catalyst (5 mol%) was added to a stirred solution of cyclopro-
pene 14 (1.2 equiv.) and p-anisidine (1 equiv.) in CH2Cl2
(0.1 M). The resulting solution was stirred for 18 h at 25 °C, fil-
tered through a silica plug with ether and concentrated under
reduced pressure. The reaction mixture was then analysed by
1H NMR in CDCl3 to determine reaction conversion by com-
parison with literature known spectra.2f
General procedure for Table 3
3 For reviews on gold-catalysed reactions with cyclopropenes,
see: (a) B.-L. Lu, L. Dai and M. Shi, Chem. Soc. Rev., 2012,
41, 3318; (b) F. Miege, C. Meyer and J. Cossy, Beilstein
J. Org. Chem., 2011, 7, 717.
4 (a) M. S. Hadfield and A. L. Lee, Org. Lett., 2010, 12, 484;
(b) A. Heuer-Jungemann, R. G. McLaren, M. S. Hadfield
and A.-L. Lee, Tetrahedron, 2011, 67, 1609; (c) K. J. Kilpin,
U. S. D. Paul, A. L. Lee and J. D. Crowley, Chem. Commun.,
2011, 47, 328.
Catalyst (5 mol% with respect to gold) was added in one
portion to a stirred solution of cyclopropene 11 (1 equiv.) and
phenethyl alcohol (1 equiv.) in CH2Cl2 (0.48 M). The resulting
solution was stirred for 19 h at 20 °C, the mixture was then fil-
tered through a silica plug with ether and concentrated under
reduced pressure. The reaction mixture was then analysed by
1H NMR in CDCl3 to determine reaction conversion by com-
parison with spectra of isolated 16 (see ESI†).
5 P. C. Young, N. A. Schopf and A.-L. Lee, Chem. Commun.,
2013, 49, 4262.
Acknowledgements
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A. Curioni and W. J. Andreoni, J. Am. Chem. Soc., 2000, 122,
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We thank EPSRC (PCY) for funding, EPSRC UK National Mass
Spectrometry Facility at Swansea University for analytical ser-
vices and Dr Scott J. Dalgarno and Dr Gary Nichol for
additional single crystal X-ray crystallography.
7 Gold(I)-catalysed reactions with thiols are still relatively
scarce, see for example: with allenes: (a) N. Morita and
N. Krause, Angew. Chem., Int. Ed., 2006, 45, 1897;
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12 The structure of complex 6b has been disclosed while
investigating gold-catalysed reactions with thiols (see ref.
see ref. 2 and 3 and: (a) Z. B. Zhu and M. Shi, Chem.–Eur.
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