Gold catalysed Suzuki-Miyaura coupling of arenediazonium o-benzenedisulfonimides

Article abstract of DOI:10.1016/j.tet.2018.08.018

Arenediazonium o-benzenedisulfonimides have been used as efficient electrophilic partners in Au(I) catalysed Suzuki coupling reactions. The synthetic protocol is general, easy and produced either biaryls or heteroaryl arenes in good yields (51 positive examples, average yield 80%). o-Benzenedisulfonimide was recovered at the end of the reactions and was reused to prepare the starting salts for further reactions. Mechanistic insights suggest that the o-benzenedisulfonimide anion act as an electron transfer agent and promotes a catalytic cycle which does not require the presence of photocatalysts or external oxidants.

Full text of DOI:10.1016/j.tet.2018.08.018

Accepted Manuscript
Gold catalysed Suzuki-Miyaura coupling of arenediazonium o-benzenedisulfonimides
Margherita Barbero, Stefano Dughera
PII:
S0040-4020(18)30971-2
10.1016/j.tet.2018.08.018
TET 29738
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 10 July 2018
Revised Date: 9 August 2018
Accepted Date: 13 August 2018
Please cite this article as: Barbero M, Dughera S, Gold catalysed Suzuki-Miyaura coupling of
arenediazonium o-benzenedisulfonimides, Tetrahedron (2018), doi: 10.1016/j.tet.2018.08.018.
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ACCEPTED MANUSCRIPT
Graphical Abstract
Gold catalyzed Suzuki-Miyaura coupling of
arenediazonium o-benzenedisulfonimides
Margherita Barbero, Stefano Dughera*
Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy.
Click here and insert/paste graph

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Gold catalysed Suzuki-Miyaura coupling of arenediazonium o-benzenedisulfonimides
Margherita Barbero, Stefano Dughera*
Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy.
* Corresponding author.
Tel: +39(011)6707645; Fax: +39(011)6707642; e-mail: stefano.dughera@unito.it
Keywords: Diazonium salts. C-C coupling. Boronic acids. Gold catalysis. Au(I)/Au(III). Electron
transfer agent.
Abstract: Arenediazonium o-benzenedisulfonimides have been used as efficient electrophilic
partners in Au(I) catalysed Suzuki coupling reactions. The synthetic protocol is general, easy and
produced either biaryls or heteroaryl arenes in good yields (51 positive examples, average yield
80%). o-Benzenedisulfonimide was recovered at the end of the reactions and was reused to prepare
the starting salts for further reactions. Mechanistic insights suggest that the o-benzenedisulfonimide
anion act as an electron transfer agent and promotes a catalytic cycle which does not require the
presence of photocatalysts or external oxidants.
1. Introduction
The use of oxidative gold catalysis as an effective means of facilitating C–C bond-forming
reactions has been attracting increasing amount of attention in recent years.1 The fact that Au (I)
and Pd(0) are isoelectronics means that Au (I) species are able to catalyse reactions, including
cross-coupling reactions, that are typically promoted by Pd(0). A number of Au(I) catalysts have
therefore been successfully used in several of these reactions, such as Suzuki,2 Sonogashira,3
Stille1h,4 and Hiyama5 couplings.
The higher redox potential that exists between Au(I) and Au(III) could be seen as a drawback.
However, the Au(I)/Au(III) redox cycle takes place quite easily in the presence of external
oxidants.1h,2f,6
A number of research group have recently presentend a new strategy for gold-catalysed cross-
coupling reactions.7 They propose using aryl radicals, which operate as both oxidants and coupling
partners, instead of external oxidants. These aryl radicals usually resulted from the light-mediated
decomposition of arenediazoniumm salts after nitrogen loss, which generally occurred in the
presence of an appropriate photocatalyst. Two efficient gold-catalysed Suzuki-Miyaura couplings of
arenediazonium salts that make use of this mechanism have been recently reported.8a,b This
approach was recently improved into a photocatalyst-free coupling as proposed by Hashmi and co-
workers.8c

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Our own research has produced a large family of dry diazonium salts, the arenediazonium o-
benzenedisulfonimides 1, (Fig. 1)9a which, have shown significant potential in numerous synthetic
applications and in particular have given excellent results in palladium catalysed coupling
reactions.9b-h
Fig. 1. Arenediazonium o-benzenedisulfonimides 1 and o-benzenedisulfonimide (2).
In fact, they are easy to prepare and isolate, are extremely stable, and can be stored for an unlimited
period. Moreover, they react easily both in water and in organic solvents, and o-
benzenedisulfonimide (2; Fig. 1) can be easily recovered and reused at the end of the reactions.
As part of a broader project aimed at exploring the synthetic potential of 1 in metal catalysed
reactions we herein describe the reactivity of 1 as electrophilic partners in Au(I) catalysed Suzuki-
Miyaura coupling10 (Scheme 1). It must be stressed that, in our recent paper,11a we obtained
significant results from using salts 1 in Au(I) catalysed Heck-coupling reactions.
Scheme 1. The gold catalysed Suzuki-Miyaura coupling of arenediazonium o-
benzenedisulfonimides 1.
2. Results and discussion
In order to optimise the reaction conditions, the coupling reaction of benzenediazonium o-
benzenedisulfonimide (1a) and 4-methoxyphenylboronic acid (3a) in the presence of two different
Au(I) catalysts was initially performed and studied under varying conditions, as reported in Table 1.
First of all, it must be stressed that better results were achieved using
[bis(trifluoromethanesulfonyl)imidate] (triphenylphosphine) gold (Table 1, entries 13−24) than with
chloro(triphenylphosphine)gold (Table 1, entries 1−12). A variety of bases, solvent ant
temperatures were tested in the presence of the first catalyst and the best result was obtained using
Cs2CO3 in THF at room temperature (Table 1, entry19).

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Table 1
Trial reactions
Entry
Temp Time Solvent
Catalyst
Base
Photocatalyst
Yield (%)
of 4a a,b
-
(°C)
50
r.t
(h)
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
4
c
c
1
2
THF
THF
THF
THF
THF
THF
THF
THF
THF
EtOH
MeCN
DMSO
THF
THF
THF
THF
THF
THF
THF
THF
EtOH
-
-
Ru(bpy)3(PF6)2
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuNTf2
Ph3PAuNTf2
Ph3PAuNTf2
-
-
Ru(bpy)3(PF6)2
20
3
r.t
-
-
-
-
-
25
4
50
r.t.
r.t
-
15
5
CaCO3
NaOH
Na2CO3
K3PO4
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
-
35
6
-
7
r.t.
r.t.
r.t
28
8
25
47d,e
9
-
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
r.t
-
14
r.t.
r.t.
r.t.
r.t.
50
r.t.
r.t.
r.t
-
20
-
traces
42
c
Ru(bpy)3(PF6)2
-
-
40
-
-
22
Ph3PAuNTf2 CaCO3
Ph3PAuNTf2 K3PO4
Ph3PAuNTf2 Na2CO3
Ph3PAuNTf2 Cs2CO3
Ph3PAuNTf2 Cs2CO3
Ph3PAuNTf2 Cs2CO3
-
68
3.5
7
-
60
-
45
88d,e
r.t.
50
r.t.
r.t
2
-
1
-
42
4
-
58
8
MeCN Ph3PAuNTf2 Cs2CO3
DMSO Ph3PAuNTf2 Cs2CO3
-
-
74
r.t.
r.t.
1.5
2
80
THF
Ph3PAuNTf2 Cs2CO3
dark
87

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a All the reactions were carried under nitrogen flow, using 0.5 mmol of 1a, 0.6 mmol of 3a, 5 mol%
of Au catalysts and 1 mmol of various bases.
b Yields refer to pure and isolated 4a, purified on a silica gel chromatography column. The eluent
was petroleum ether/diethyl ether (9 : 1).
c 5 mol% of photocatalyst were used
d Higher amount of base or Au catalyst did not lead to increased yield
e
No product 4a was formed when when the reaction was carried out in the presence of 1,3-
dinitrobenzene (0.5 mmol, 85 mg) or TEMPO (0.5 mmol, 78 mg).
An excellent yield (88%) of 4a was achieved in a short reaction time (2 h) and in the presence of
and Cs2CO3 (2 equiv.) and using 5 mol % of Ph3PAuNTf2 as the catalyst. It is worth noting that,
unlike other gold catalysed Suzuki reactions, no external oxidants, photocatalysts or light were
necessary for the completion of the reaction which also occurred in the dark (Table 1, entry 24).
The high yield, short reaction time and simplicity of the procedure encouraged us to further exploit
its generality and scope, using a number of variously substituted diazonium salts 1 and boronic
acids 3. The results are collected in Table 2. Most of these examples demonstrate the usefulness and
the simplicity of this method, which requires mild reaction conditions and relatively short reaction
times. The target products were obtained in good yields and selectivity while producing negligible
amounts of by-products, namely symmetrical biphenyls, arenes, N-aryl-o-benzenedisulfonimides.
The reaction was chemoselective; diazonium salts which bear a bromine atom 1e and that could
potentially react as a diazonium group, only furnished target products 4b, j, r, s, t, u, v, w (Table 2;
entries 22−30) and no traces of possible terphenyl were detected. On the other hand, the reaction
carried out with salt 1i which bears an iodine atom, provided a complex mixture of products, which
included the target 4-iodobiphenyl, but also terphenyl (Table 2, entry 44). It can be stated that the
reaction was not affected by electronic effects as biaryls 4 were obtained in satisfactory yields from
the reactions between 1 or 3 which bear either electron-donating and/or electron-withdrawing
groups. However, steric effects were found to be significant. The presence of a substituent in the
ortho position of either 1 or 3 drastically reduced the yield; (Table 2, entries 4–8,14, 23, 32, 40, 43)
in fact, the preparation of hindered biaryls via a cross-coupling reaction has historically been proven
to
be
difficult.
Surprisingly, the reactions carried out with heteroaryl boronic acids 3l
–
n failed (Table 2, entries 45–
47). Therefore, four heteroarenediazonium salts 5a–d were synthesized in order to produce
heteroaryl arenes 6. These salts, which are extremely well-stabilized by the anion of 2, were easy to
isolate and

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handle and were used as electrophilic partners for reactions carried out with six selected arylboronic
acids 3a–f (Table 3). The target heteroaryl arenes 6a-i were obtained in satisfactory yields.
Table 2
Au catalysed reactions between arenediazonium salts 1 and boronic acids 3
Entry Ar in 1
Ar’ in 3
Time (h) Products 4 and yields (%)a,b
1
2
3
4
1a; C6H5
3a; 4-MeOC6H4
3b; 4-BrC6H4
3c; 4-NO2C6H4
3d; 2-MeC6H4
2
4a; 88
2.5
1a
4b; 89
3
1a
4c; 84
1b; 2-MeC6H4
24
4d; 60c
5
3e; 3-NO2C6H4
7
1b
4e; 76c
6
7
8
9
6
1b
3a
3b
3c
3d
4f; 65c
7
1b
4g; 62c
6.5
1b
4h; 68c
1c; 3-NO2C6H4
5
4e; 61c
10
2
1c
3a
4i; 92

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11
2.5
1c
1c
3b
3c
4j; 90
12
3
4k; 88
13
14
1d; 4-MeOC6H4
3f; C6H5
2
4a; 91
4f; 61c
5.5
1d
3d
15
16
3g; 3-MeC6H4
3
1d
1d
4l; 79
2.5
3e
4i; 87
4m; 92
4n; 85
4o; 93
4p; 87
17
18
19
20
21
2.5
3
1d
1d
1d
1d
1d
3a
3c
3h; 4-ClC6H4
3i; 4-CHOC6H4
3j; 2-naphthyl
2
3
4
4q; 83
4b; 90
22
23
1e; 4-BrC6H4
2
8
3f
1e
3d
4g; 62c
24
25
3.5
3
1e
1e
3g
3e
4r; 83
4j; 86
4s; 91
4t; 93
26
27
2
1e
1e
3a
3c
3.5

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28
29
30
3.5
1e
1e
1e
3h
3i
4u; 84
4v; 87
3
4
3j
4w; 81
4c; 91
31
32
1f; 4-NO2C6H4
2.5
7
3f
1f
3d
4h; 64c
4x; 84
4k; 82
33
34
3
1f
1f
3g
3e
3.5
35
36
37
38
39
2.5
2.5
3
1f
1f
1f
1f
1f
3a
3c
3h
3i
4n; 92
4y; 86
4z; 92
4aa; 84
3.5
4.5
3j
4ab; 83
40
24
1f
3k;
3a
3c
4ac; 25c
41
42
43
1g; 2-naphthyl
1g; 2-naphthyl
1h; 2-BrC6H4
6
4q; 87
4
4ab; 83
d
24
-
3a

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e
44
1i; 4-IC6H4
3
-
3a
45
8
8
1f
d
-
3l;
46
47
1f
1f
3m;
3n;
d
-
-
8
d
a All the reactions were performed in THF at room temperature under nitrogen flow in the presence
of Cs2CO3 (1 mmol) and Ph3PAuNTf2 (5 mol%). The 1 (0.5 mmol) : 3 ratio was 1:1.1.
b Yields refer to pure and isolated 4, purified from the by-products on a silica gel chromatography
column. The eluent was petroleum ether/diethyl ether (9 : 1).
c The 1 (0.5 mmol) : 3 ratio was 1:3.
d
No products 4 were obtained. After 8 hours salts 1 were still present (azo-coupling test with 2-
naphthol was positive). Heating at 50 ° C caused the decomposition of 1.
e
GC-MS analyses of the crude residue showed a complex mixture of products among which 4-
iodobiphenyl, MS (EI): m/z 280 (M+) and terphenyl, MS (EI): m/z 230 (M)+ were recognized.
Table 3
Au catalysed reactions between heteroaromatic salts 5 and 3
Entry
1
HetAr in 5
Ar’ in 3
Time (h)
8
Products 6 and yields (%)a, b
3d; 2-MeC6H4
5a;
6a; 59c
6b; 91
2
3f; C6H5
3
5a

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3
4
3h; 4-ClC6H4
3.5
5a
6c; 84
6d; 81
3e; 3-NO2C6H4
4
5b;
CHO
5
6
3i; 4-CHOC6H4
2.5
8
5b
N
6e; 78
6f; 48c
3d
5c;
7
8
3
4
5c
3h
6g; 70
3a; 4-MeOC6H4
5d;
6h; 79
9
3.5
5d
3f
6i; 77
a All the reactions were performed in THF at room temperature under nitrogen flow in the presence
of Cs2CO3 (1 mmol) and Ph3PAuNTf2 (5 mol%). The 5 (0.5 mmol) : 3 ratio was 1:1.1.
b
Yields refer to pure and isolated 6, purified from the by-products on a silica gel chromatography
column. The eluent was petroleum ether/diethyl ether (9 : 1).
c The 1 (0.5 mmol) : 3 ratio was 1:3.
Finally, it is worth noting that was possible to recover o-benzenedisulfonimide (2) in more than
80% yield from all the reactions described above. It was also possible to recycle 2 for the
preparation of other salts 1 with economic and ecological benefits.
The large amounts of data collected provide a good basis for some remarks on the mechanism
involved.

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Elegant hypotheses as to the mechanism of the gold-catalysed Suzuki couplings of arenediazonium
salts have been proposed by the three different research groups mentioned above and are
summarized in Scheme 2.8 In two of these protocols, aryl radicals, generated by a visible-light
photoredox process, enable the oxidation of Au(I) to Au(III). According to Lee hypothesis,8b using
Ph3PAuNTf2 as a catalyst means that the transmetallation step occurrs prior to the oxidation step,
whereas oxidation precedes
transmetallation in the presence of Ph3PAuCl.
reductive
elimination
oxidation
transmetallation
Ar' B(OH)2
LAuIIIAr(Ar')
LAuICl
LAuIAr'
LAuIIAr(Ar')
Ar N2
Ar Ar'
Ar
X
photo-redox cycle
Ar
Ar N2
Hermange and Fouquet8a
reductive
elimination
radical
addition
SET
LAuI
transmetallation
LAuIAr'
LAuIIIAr(Ar')
LAuIIAr(Ar')
Ar N2
Ar Ar'
Ar' B(OH)2
Ar
Ru(bpy)33+
Ru(bpy)32+
2+*
visible light
Ru(bpy)3
Lee8b; transmetallation first; Au catalyst = PPh3AuNTf2
radical
reductive
elimination
Cl
AuIII
Ar'
SET
transmetallation
addition
LAuIIIAr(Cl)
LAuICl
LAuIIAr(Cl)
Ar
L
Ar Ar'
Ar N2
Ar' B(OH)2
Ru(bpy)32+
Ar
Ru(bpy)33+
2+*
visible light
Ru(bpy)3
Lee8b; oxidation first
Cl
SET
r.e.
h
oxidation
transmetallation
II
LAuICl
LAuIIICl
N2 Ar
LAuIIICl
Ar
N Ar
2
LAu Cl [
]
Ar
AuIII
Ar'
L
Ar Ar'
N2
Ar' B(OH)2
Ar N2
Hashmi8c
Scheme 2. Mechanisms proposed in the literature
On the other hand, Hermange and Fouquet,8a who only used Ph3PAuCl, proposed that
transmetallation came before gold oxidation in the catalytic cycle. Finally, Hashmi8c hypothesized a
photosensitizer-free visible-light driven process in which the first step involved the oxidation of

11
ACCEPTED MANUSCRIPT
Ph3PAuCl to a Au(III) specie by a diazonium salt in a SET process. It must be noted that the specie
that actually undergoes the transmetallation is only formed after the light-mediated elimination of
N2.
In a previous paper,11a we obtained significant results from using salts 1 in Au(I) catalysed Heck-
coupling reactions. Mechanistic insights highlighted the interesting role that the o-
benzenedisulfonimide anion played as an electron transfer agent11b-c in promoting a pathway that
does not require the presence of photocatalysts or external oxidants. Moreover, this reaction also
occurred in the dark and without any photocatalysts. With the above-described mechanism in mind,
we hypothesize the pathway shown in Scheme 3.
We assume that the transmetallation, namely the interaction between 3 and Ph3PAuNTf2 leading to
the Au(I) intermediate 7, is the first step.
Scheme 3. Hypothesized mechanism.
At this point, we also believe that the anion of salts 1 may act as a primary electron donor reagent
toward the arenediazonium cations also in this coupling reaction, which would most likely give rise
to the electron transfer complex 8 (Fig. 2). This would be favoured by the formation of a complex in

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which the partner of the aryldiazenyl radical is a species that is highly resonance stabilized (8a, 8b,
etc)
Fig. 2. Electron transfer complex 8.
We then assume that complex 8 interacts with 7 to form the Au(II) complex 9 by transferring an
aryl radical to it. A further oxidation of 9, most likely due to an electron donated by 1, gives the
Au(III) complex 11 and other radicals 10 which contribute to oxidizing the Au(I) catalyst.
Ultimately, this radical chain enables the oxidation of the Au(I) to Au(III) (even in the dark; Table
1, entry 24) and without the involvement of photocatalysts or external oxidants. Finally, the
reductive elimination step allows target 4 to be obtained and the Au catalyst restored.
It must be stressed that no product 4a was formed when the reaction was carried out in the presence
of 1,3-dinitrobenzene or TEMPO, known radical scavengers (Table 1; entry 19, note e). This is a
good evidence that radicals are the actual reactive species.
It is known from the literature that the decomposition of diazonium salts in the presence of toluene
furnished three isomers derived from phenylation of toluene at the ortho, meta and para positions.
For a heterolytic decomposition the o:m:p ratio is 2.4:1.0:1.0 12a whereas for a homolytic one the
o:m:p ratio is 4.0:1.0:0.7.12b In a control experiment (Experimental: control experiment 4.4.1)
carried out under standard conditions, we added toluene in the reaction enviroment (in equimolar
amount with respect to arylboronic acid). At the end of the reactions, GC analyses showed the
presence of a significant amount of methylbiphenyl o, m, p isomers. The ratio was 4.08:1.0:0.61.,
typical of an homolytic pathway. This can be a further evidence of the formation of aryl radicals
resulting from 8.
The trial reactions (Table 1) clearly indicated that Ph3PAuNTf2 was a better catalyst than
Ph3PAuCl. The type of the counterion is crucial here. In fact the presence of NTf2, a strong
electron-withdrawing group, makes Au (I) much more electrophilic than when it is bound to Cl13
and therefore makes it very reactive in the transmetallation step.

13
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A simple control experiment was carried out (Experimental: control experiment 4.4.2) in order to
confirm that transmetallation really is the first step. First, we prepared PPh3AuPh by reacting
Ph3PAuNTf2 with 3a in the presence of Cs2CO3 and we then added salt 1. The reaction completed
after 1 h and the usual work-up furnished target 4a in yields comparable to those obtained under
standard conditions. Interestingly, the same reaction provided poor results when carried out with
Ph3PAuCl, confirming that this catalyst is less inclined to undergo the transmetallation reaction.
An alternative mechanism, in which the oxidation step precedes the transmetallation step, is showed
in Scheme 4. We believe this alternative mechanism is very unlikely; in fact, the possible
intermediate 13, formed via Au (I) oxidation by aryl radicals, would be highly destabilized by the
presence of NTf2, thus hindering the progress of the reaction. A control experiment (Experimental:
control experiment 4.4.3) confirmed this hypothesis.
Scheme 4. Alternative mechanism.
3. Conclusions
We have proposed a mild, easy and efficient gold catalysed Suzuki-Miyaura coupling of
arenediazonium o-benzenedisulfonimides 1 and heteroarenediazonium o-benzenedisulfonimides 5.

14
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The target products, biaryls 4 or heteroarenes 6 were generally obtained in satisfactory yields (51
positive examples, 80% average yield). We also confirm the interesting role that the o-
benzenedisulfonimide anion plays as an electron transfer agent in enabling a pathway that does not
require the presence of photocatalysts or external oxidants.
4. Experimental
4.1. General information
All the reactions were carried out in oven dried glassware and under a nitrogen flow. Analytical
grade reagents and solvents were used and reactions were monitored by GC, GC-MS and TLC.
Column chromatography and TLC were performed on Merck silica gel 60 (70-230 mesh ASTM)
and GF 254, respectively. Petroleum ether refers to the fraction boiling in the range 40–70 °C.
Room temperature is 20-25 °C. Mass spectra were recorded on an HP 5989B mass selective
detector connected to an HP 5890 GC with a methyl silicone capillary column. 1H NMR, 13C NMR,
31P spectra were recorded on a Jeol ECZR spectrometer at 600, 150 and 243 MHz respectively. IR
spectra were recorded on an IR PerkinElmer UATR-two spectrometer. Dry arenediazonium o-
benzenedisulfonimides 1 and dry heteroarenediazonium o-benzenedisulfonimides 5 were prepared
1
as described previously by us.9a The crude salts 1 and 5 were virtually pure (by H NMR
spectroscopy) and were used in subsequent reactions without further crystallization. All the other
reagents were purchased from Sigma-Aldrich or Alfa-Aesar. Structures and purity of all the
products obtained in this research were confirmed by their spectral (NMR, MS ) and physical data,
substantially identical to those reported in the literature. Yields of the pure (GC, GC-MS, TLC and
NMR) isolated compounds 4, 6 are collected in Tables 2 and 3. NMR spectra of 4 and 6 are
reported in Supplementary material. Satisfactory microanalyses were obtained for new compound
4ac.
4.2. Benzenediazonium o-benzenedisulfonimide (1a): representative procedure for the preparation
of salts 1.
A solution of o-benzenedisulfonimide (2; 2.63 g, 12 mmol) in glacial AcOH (40 mL) was slowly
added, over period of 10 min, to a stirred solution of aniline ( 0.93 g, 10 mmol) in the same solvent,
previously cooled to 0-5°C in an ice bath. i-Pentyl nitrite (1.28 g, 11 mmol) was added dropwise
(about 10 min). A white precipitate of 1a began to separe at once. After the addition was complete,
the cooling bath was removed and the mixture was maintained under stirring for further 10 min.
Then anhydrous Et2O was added to complete the precipitation of 1a, that was gathered by filtration
on a Büchner funnel and washed several times with additional anhydrous Et2O. After drying under
reduced pressure, the title compound 1a was obtained in 98% yield (3.18 g). Dp 110°C (lit.9a dp 110
°C).

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ACCEPTED MANUSCRIPT
4.3. 4-Methoxybiphenyl (4a): representative procedure for the Au catalyzed Suzuki-Miyaura
couplings
In a oven-dried flask and under nitrogen flow, benzenediazonium o-benzenedisulfonimide (1a, 161
mg, 0.5 mmol) was added to a suspension of 4-methoxyphenylboronic acid (3a, 91 mg, 0.6 mmol),
[bis(trifluoromethanesulfonyl)imidate](triphenylphosphine)gold(I) (2:1) toluene adduct (39 mg,
0.025 mmol, 5mol%), Cs2CO3 (325 mg, 1 mmol) in THF (5 mL). The resulting mixture was stirred
at room temperature for 2 h; the completion of the reaction was confirmed by the absence of azo
coupling with 2-naphthol. Then, the reaction mixture was poured into diethyl ether/water (100 mL,
1:1). The aqueous layer was separated and extracted with diethyl ether (50 mL). The combined
organic extracts were washed with water (50 mL), dried with Na2SO4 and evaporated under reduced
pressure. GC-MS analyses of the crude residue showed 4-methoxybiphenyl (4a), MS (EI): m/z 184
(M+) as the major product, besides traces of biphenyl, MS (EI): m/z 154 (M+), 4,4’-
dimethoxybiphenyl, MS (EI): m/z 214 (M+), N-phenyl-o-benzenedisulfonimide, MS (EI): m/z 295
(M+). The crude residue was purified on a short column, eluting with petroleum ether/diethyl ether
(9:1). The only isolated product was the title compound (4a, 81 mg, 88% yield). The aqueous layer
and aqueous washings were collected and evaporated under reduced pressure. The tarry residue was
passed through a column of Dowex HCR-W2 ion exchange resin (1.6 g/1 g of product), eluting with
water (about 50 mL). After removal of water under reduced pressure, virtually pure (1H NMR) o-
benzenedisulfonimide (2) was recovered (89 mg, 81% yield; mp 192–194 °C. Lit. 190–193 °C).
A gram-scale reaction was also carried out between 1a (1.61 g, 5 mmol) and 1b (0.91 g, 6 mmol) in
the presence of bis(trifluoromethanesulfonyl)imidate](triphenylphosphine)gold(I) (2:1) toluene
adduct 0.39 g, 0.25 mmol, 5mol%) and Cs2CO3 (3.25 g, 10 mmol) in THF (20 mL). After the above
described work-up, 4a (0.78 g) was obtained in 85% yield and 2 was recovered (1.00 g, 91%).
4.3.1 4-Methoxybiphenyl (4a).
4a was obteined as a white solid; 81 mg (88% yield from 1a and 3a) or 84 mg (91% yield from 1d
and 3f ; mp 87–88 °C (MeOH; lit.14 mp 87–88 °C); Rf (petroleum ether/Et2O 9:1) 0.43; δH (600
MHz, CDCl3) 7.58−7.54 (m, 4H), 7.43 (t, J = 8.4 Hz, 2H), 7.31 (t, J = 7.8 Hz, 1H), 6.99 (d, J = 9.0
Hz, 2H), 3.82 (s, 3H); δC (150 MHz, CDCl3) 159.3, 140.9, 133.9, 128.8, 128.3, 126.8, 126.7, 114.6,
55.4; MS (EI): m/z 184 (100, M+)
4.3.2. 4-Bromobiphenyl (4b).
4b was obtained as a pale grey solid; 104 mg (89% yield from 1a and 3b) or 105 mg (90% yield
from 1e and 3f); mp 90–91°C (MeOH; lit.15 mp 89–90 °C); Rf (petroleum ether/Et2O 9:1) 0.41; δH
(600 MHz, CDCl3) 7.58−7.55 (m, 4H), 7.47−7.43 (m, 4H), 7.39−7.36 (m, 1H); δC (150 MHz,

16
ACCEPTED MANUSCRIPT
CDCl3) 140.2, 140.1 131.9, 129.0, 128.9, 127.8, 127.1, 121.7; MS (EI): m/z 232 (100, M+), 234
(100, M+ +2).
4.3.3 4-Nitrobiphenyl (4c).
4c was obtained as a pale yellow solid; 84 mg (84% yield from 1a and 3c) or 91 mg (91 % yield
from 1f and 3f); mp 114–115 °C (MeOH; lit.16 mp 112–113 °C); Rf (petroleum ether/Et2O 9:1)
0.37; δH (600 MHz, CDCl3) 8.28 (d, J = 9.0 Hz, 2H), 7.72 (d, J = 8.5 Hz, 2H), 7.62−7.61 (m, 2H),
7.51−7.48 (m, 2H), 7.46−7.44 (m, 1H); δC (150 MHz, CDCl3) 147.8, 147.2, 138.9, 129.3, 129.0,
127.9, 127.5, 124.2; MS (EI): m/z 199 (100, M+).
4.3.4. 2,2’-Dimethylbiphenyl (4d).
4d was obtained as a pale yellow viscous oil;17 55 mg (60% yield); Rf (petroleum ether/Et2O 9:1)
0.65; δH (600 MHz, CDCl3) 7.26–7.20 (m, 6H), 7.11–7.09 (m, 2H), 2.05 (s, 6H); δC (150 MHz,
CDCl3) 141.6, 135.8, 129.9, 129.4, 127.2, 125.7, 19.9; MS (EI): m/z 182 (75, M+).
4.3.5. 2-Methyl-3’-nitrobiphenyl (4e).
4e was obtained as a pale yellow viscous oil;18 81 mg (76% yield from 1b and 3e) or 65 mg (61%
yield from 1c and 3d); Rf (petroleum ether/Et2O 9:1) 0.41; δH (600 MHz, CDCl3) 8.21–8.20 (m,
2H), 7.67–7.65 (m, 1H), 7.61–7.57 (m, 1H), 7.33–7.21 (m, 4H), 2.27 (s, 3H); δC (150 MHz, CDCl3)
148.2, 143.7, 139.4, 135.4, 135.3, 130.7, 129.7, 129.1, 128.4, 126.2, 124.2, 121.9, 20.6; MS (EI):
m/z 213 (100, M+).
4.3.6. 4’-Methoxy-2-methylbiphenyl (4f).
4f was obtained as a pale yellow solid; 64 mg (65% yield from 1b and 3a) or 60 mg (61% yield
from 1d and 3d); mp 52–53 °C (MeOH; lit.19 mp 51–52 °C); Rf (petroleum ether/Et2O 9:1) 0.49; δH
(600 MHz, CDCl3) 7.28–7.26 (m, 4H), 7.25–7.23 (m, 2H), 6.97 (d, J = 8.4 Hz, 2H), 3.87 (s, 3H),
2.30 (s, 3H); δC (150 MHz, CDCl3) 158.6, 141.6, 135.6, 134.5, 130.4, 130.3, 130.0, 127.1, 125.9,
113.6, 55.8, 21.1; MS (EI): m/z 198 (100, M+).
4.3.7. 4’-Bromo-2-methylbiphenyl (4g).
4g was obtained as a pale yellow viscous oil;20 77 mg (62% yield from 1b and 3b) or 77 mg (62%
yield from 1e and 3d); Rf (petroleum ether/Et2O 9:1) 0.58; δH (600 MHz, CDCl3) 7.55 (d, J = 8.4
Hz, 2H), 7.34–7.24 (m, 4H), 7.21 (d, J = 8.4 Hz, 2H), 2.28 (s, 3H); δC (150 MHz, CDCl3) 140.9,
140.7, 135.3, 131.4, 131.0, 130.7, 130.6, 127.7, 126.0, 121.1, 20.7; MS (EI): m/z 246 (80, M+), 248
(80, M+ +2).
4.3.8. 2-Methyl-4’-nitrobiphenyl (4h).
4h was obtained as a pale yellow solid; 72 mg (68% yield from 1b and 3c) or 69 mg (64% yield
from 1f and 3d); mp 105–106 °C (MeOH; lit.21 mp 104–105 °C); Rf (petroleum ether/Et2O 9:1)
0.40; δH (600 MHz, CDCl3) 8.27 (d, J = 8.4 Hz, 2H), 7.48 (d, J = 8.4 Hz, 2H), 7.34–7.27 (m, 3H),

17
ACCEPTED MANUSCRIPT
7.21 (d, J =7.2 Hz, 2H), 2.27(s, 3H); δC (150 MHz, CDCl3): δ = 148.9, 146.9, 139.7, 135.2, 130.8,
130.2, 129.5, 128.6, 126.2, 123.7, 20.5; MS (EI): m/z 213 (100, M+).
4.3.9. 4’-Methoxy-3-nitrobiphenyl (4i).
4i was obtained as a pale brown solid; 105 mg (92% yield from 1c and 3a) or 100 mg (87% yield
from 1d and 3e); mp 75–77 °C (MeOH; lit.22 mp 75–76 °C); Rf (petroleum ether/Et2O 9:1) 0.28; δH
(600 MHz, CDCl3) 8.38 (t, J = 1.8 Hz, 1H), 8.13–8.12 (m, 1H), 7.85–7.84 (m, 1H), 7.57–7.54 (m,
3H), 6.99 (d, J =9.0 Hz, 2H), 3.86 (s, 3H); δC (150 MHz, CDCl3) 160.2, 148.8, 142.5, 132.6, 131.1,
129.7, 128.3, 121.4, 121.3, 114.7,55.5; MS (EI): m/z 229 (100, M+).
4.3.10. 4’-Bromo-3-nitrobiphenyl (4j).
4j was obtained as a white solid; 125 mg (90% yield from 1c and 3b) or 120 mg (86% yield from 1e
and 3e); mp 94–95 °C (MeOH; lit.23 mp 93 °C); Rf (petroleum ether/Et2O 9:1) 0.35; δH (600
MHz, CDCl3): δ = 8.39 (t, J = 1.8 Hz, 1H), 8.21–8.19 (m, 1H), 7.87–7.86 (m, 1H), 7.62–7.58 (m,
3H), 7.47 (d, J =9.0 Hz, 2H); δC (150 MHz, CDCl3) 141.7, 137.6, 133.1, 132.9, 132.4, 130.0, 128.8,
123.1, 122.5, 121.8; MS (EI): m/z 277 (100, M+), 279 (100, M+ +2).
4.3.11. 3-Nitro-4’-nitrobiphenyl (4k).
4k was obtained as a pale orange solid; 107 mg (88% yield from 1c and 3c) or 100 mg (82% yield
from 1f and 3e); mp 185–186 °C (MeOH; lit.24 mp 184–187 °C); Rf (petroleum ether/Et2O 9:1)
0.18; δH (600 MHz, CDCl3) 8.48 (t, J = 1.8 Hz, 1H), 8.35 (d, J = 9.0 Hz, 2H), 8.30–8.29 (m, 1H),
7.95–7.94 (m, 1H), 7.78 (d, J = 9.0 Hz, 2H), 7.69 (t, J = 7.8 Hz, 1H); δC (150 MHz, CDCl3) 148.9,
147.9, 144.9, 140.5, 133.3, 130.4, 128.2, 124.5, 123.6, 122.4; MS (EI): m/z 244 (100, M+).
4.3.12. 4’-Methoxy-3-methylbiphenyl (4l).
4l was obtained as a pale grey solid; 78 mg (79% yield); mp 50–51 °C (MeOH; lit.25 mp 51–52 °C);
Rf (petroleum ether/Et2O 9:1) 0.49; δH (600 MHz, CDCl3) 7.56 (d, J = 8.4 Hz, 2H), 7.45–7.33 (m,
3H), 7.17–7.16 (m, 1H), 7.01 (d, J = 8.4 Hz, 2H), 3.87 (s, 3H), 2.45 (s, 3H); δC (150 MHz, CDCl3)
159.2, 140.9, 138.3, 134.0, 128.8, 128.3, 127.7, 127.6, 123.9, 114.2, 55.3, 21.3; MS (EI): m/z 198
(100, M+).
4.3.13. 4,4’-Dimethoxybiphenyl (4m).
4m was obtained as a white solid; 98 mg (92% yield); mp 174–175 °C (MeOH; lit.26 mp 172–174
°C); Rf (petroleum ether/Et2O 9:1) 0.25; δH (600 MHz, CDCl3) 7.48 (d, J = 8.4 Hz, 2H), 6.86 (d, J
= 8.4 Hz, 2H), 3.84 (s, 3H); δC (150 MHz, CDCl3) 158.8, 133.6, 127.9, 114.2, 55.8; MS (EI): m/z
214 (100, M+).
4.3.14. 4-Methoxy-4’-nitrobiphenyl (4n).
4n was obtained as a pale orange solid; 97 mg (85% yield from 1d and 3c) or 105 mg (92% yield
from 1f and 3a); mp 109–110°C (MeOH; lit.27 mp 109–110 °C); Rf (petroleum ether/Et2O 9:1)

18
ACCEPTED MANUSCRIPT
0.22; δH (600 MHz, CDCl3) 8.25 (d, J = 9.0 Hz, 2H), 7.66 (d, J = 8.4 Hz, 2H), 7.57 (d, J = 9.0 Hz,
2H), 7.00 (d, J = 8.4 Hz, 2H), 3.86 (s, 3H); δC (150 MHz, CDCl3) 160.5, 147.4, 146.6, 131.1, 128.7,
127.1, 124.4, 114.7, 55.8; MS (EI): m/z 229 (100, M+).
4.3.15. 4-Chloro-4’-methoxybiphenyl (4o).
4o was obtained as a pale grey solid; 101 mg (93% yield); mp 111–112°C (MeOH; lit.28 mp 110–
111 °C); Rf (petroleum ether/Et2O 9:1) 0.45; δH (600 MHz, CDCl3) 7.49–7.58 (m, 4H), 7.38–7.37
(m, 2H), 6.98 (d, J = 8.4 Hz, 2H), 3.85 (s, 3H); δC (150 MHz, CDCl3) 159.5, 139.4, 132.8, 132.5,
129.1, 128.1, 128.0, 114.6, 55.8; MS (EI): m/z 218 (100, M+).
4.3.16. 4-(4-Methoxyphenyl)benzaldehyde (4p).
4p was obtained as a white solid; 92 mg (87% yield); mp 110–111°C (MeOH; lit.29 mp 109–110
°C); Rf (petroleum ether/Et2O 9:1) 0.29; δH (600 MHz, CDCl3)10.00 (s, 1H), 7.89 (d, J = 9.0 Hz,
2H), 7.68 (d, J = 8.4 Hz, 2H), 7.56 (d, J = 9.0 Hz, 2H), 6.98 (d, J = 8.4 Hz, 2H), 3.84 (s, 3H); δC
(150 MHz, CDCl3) 192.0, 160.2, 146.8, 134.8, 132.1, 130.4, 128.6, 127.1, 114.5, 55.4; MS (EI): m/z
212 (100, M+).
4.3.17. 2-(4-Methoxyphenyl)naphthalene (4q).
4q was obtained as a grey solid; 97 mg (83% yield from 1d and 3j) or 102 mg (87% yield from 1g
and 3a); mp 132–133°C (MeOH; lit.30 mp 130–131 °C); Rf (petroleum ether/Et2O 9:1) 0.38; δH
(600 MHz, CDCl3) 8.01 (d, J = 2.4 Hz, 1H), 7.91–7.87 (m, 3H), 7.75–7.73 (m, 1H), 7.68 (d, J =
8.4 Hz, 2H), 7.55–7.45 dC (m, 2H), 7.04 (d, J = 8.4 Hz, 2H), 3.88 (s, 3H); δC (150 MHz, CDCl3)
159.4, 138.3, 133.7, 133.6, 132.4, 128.6, 128.5, 128.2, 127.8, 126.4, 125.8, 125.6, 125.2, 114.4,
55.6 ; MS (EI): m/z 234 (75, M+).
4.3.18. 4’-Bromo-3-methylbiphenyl (4r).
4r was obtained as a pale yellow viscous oil;31 103 mg (83% yield); Rf (petroleum ether/Et2O 9:1)
0.62; δH (600 MHz, CDCl3) 7.57 (d, J = 8.4 Hz, 2H), 7.46 (d, J = 8.4 Hz, 2H), 7.39–7.35 (m, 4H);
δC (150 MHz, CDCl3) 140.4, 140.1, 138.6, 131.9, 128.9, 128.8, 128.5, 127.8, 124.1, 121.5, 21.6;
MS (EI): m/z 246 (100, M+), 248 (100, M+ +2).
4.3.19. 4-Bromo-4’-methoxybiphenyl (4s).
4s was obtained as a pale grey solid; 120 mg (91% yield); mp 144–145°C (MeOH; lit.32 mp 143–
144 °C); Rf (petroleum ether/Et2O 9:1) 0.45; δH (600 MHz, CDCl3) 7.53 (d, J = 8.4 Hz, 2H), 7.53
(d, J = 9.0 Hz, 2H), 7.41 (d, J = 8.4 Hz, 2H), 6.97 (d, J = 9.0 Hz, 2H), 3.85 (s, 3H); δC (150 MHz,
CDCl3) 159.5, 139.8, 132.5, 131.9, 128.3, 128.1, 120.9, 114.5, 54.9; MS (EI): m/z 262 (100, M+),
264 (100, M+ +2).
4.3.20. 4-Bromo-4’-nitrobiphenyl (4t).

19
ACCEPTED MANUSCRIPT
4t was obtained as a yellow solid; 129 mg (93% yield); mp 173–174 °C (MeOH; lit.33 mp 175–
176°C); Rf (petroleum ether/Et2O 9:1) 0.38; δH (600 MHz, CDCl3): δ = 8.28 (d, J = 9.0 Hz, 2H),
7.69 (d, J = 9.0 Hz, 2H), 7.60 (d, J = 8.4 Hz, 2H), 7.47 (d, J = 8.4 Hz, 2H); δC (150 MHz, CDCl3)
147.3, 146.4, 137.8, 132.4, 129.0, 127.7, 124.4, 123.0; MS (EI): m/z 277 (70, M+), 279 (70, M+ +2).
4.3.21. 4-Bromo-4’-chlorobiphenyl (4u).
4u was obtained as a pale grey solid; 112 mg (84% yield); mp 153–155 °C (MeOH; lit.34 mp 150–
153°C); Rf (petroleum ether/Et2O 9:1) 0.70; δH (600 MHz, CDCl3) 7.55 (d, J = 8.4 Hz, 2H), 7.46
(d, J = 8.4 Hz, 2H), 7.41–7.39 (m, 4H); δC (150 MHz, CDCl3) 138.9, 138.5, 133.8, 132.0, 129.1,
128.7, 128.3, 122.0; MS (EI): m/z 266 (80, M+), 268 (100, M+ +2).
4.3.22. 4-(4-Bromophenyl)benzaldehyde (4v).
4v was obtained as a white solid; 113 mg (87% yield); mp 140–141°C (MeOH; lit.35 mp 140–142
°C); Rf (petroleum ether/Et2O 9:1) 0.48; δH (600 MHz, CDCl3) 10.04 (s, 1H), 7.93 (d, J = 9.0 Hz,
2H), 7.70 (d, J = 8.4 Hz, 2H), 7.58 (d, J = 8.4 Hz, 2H), 7.47 (d, J = 9.0 Hz, 2H); δC (150 MHz,
CDCl3) 191.9, 145.9, 138.7, 135.5, 132.3, 130.4, 129.0, 127.6, 123.0; MS (EI): m/z 260 (75, M+),
262 (75, M+ +2).
4.3.23. 2-(4-Bromophenyl)naphthalene (4w).
4w was obtained as a pale orange solid; 115 mg (81% yield); mp 128–129°C (MeOH; lit.36 mp 129–
130°C); Rf (petroleum ether/Et2O 9:1) 0.68; δH (600 MHz, CDCl3) 8.01 (s, 1H), 7.92–7.87 (m,
3H), 7.70–7.68 (m, 1H), 7.62–7.57 (m, 4H), 7.53–7.51 (m, 2H); δC (150 MHz, CDCl3) 140.1,
137.4, 133.7, 132.8, 132.1, 129.0, 128.8, 128.3, 127.8, 126.6, 126.3, 125.8, 125.2, 121.8; MS (EI):
m/z 282 (65, M+), 284 (65, M+ +2).
4.3.24. 3-Methyl-4’-nitrobiphenyl (4x).
4x was obtained as a pale yellow solid; 89 mg (84% yield); mp 49–50 °C (MeOH; lit.37 mp 48–49
°C); Rf (petroleum ether/Et2O 9:1) 0.42; δH (600 MHz, CDCl3) 8.27 (d, J = 9.0 Hz, 2H), 7.71 (d, J
= 9.0 Hz, 2H), 7.43–7.37 (m, 4H), 2.45 (s, 3H); δC (150 MHz, CDCl3) 147.9, 147.1, 138.9, 138.8,
129.8, 129.2, 128.2, 127.9, 124.6, 124.1, 21.6; MS (EI): m/z 213 (100, M+).
4.3.25. 4,4’-Dinitrobiphenyl (4y).
4y was obtained as a pale yellow solid; 105 mg (86% yield); mp 236–237°C (MeOH; lit.38 mp 239–
240°C); Rf (petroleum ether/Et2O 9:1) 0.42; δH (600 MHz, CDCl3) 8.34 (d, J = 8.4 Hz, 2H), 7.78
(d, J = 8.4 Hz, 2H); δC (150 MHz, CDCl3) 148.2, 145.1, 128.4, 124.5; MS (EI): m/z 244 (100, M+).
4.3.26. 4-Chloro-4’-nitrobiphenyl (4z).
4z was obtained as a white solid; 107 mg (92% yield); mp 145–146 °C (MeOH; lit.39 mp 145–
146°C); Rf (petroleum ether/Et2O 9:1) 0.35; δH (600 MHz, CDCl3) 8.27 (d, J = 9.0 Hz, 2H), 7.68

20
ACCEPTED MANUSCRIPT
(d, J = 9.0 Hz, 2H), 7.54 (d, J = 9.0 Hz, 2H), 7.46 (d, J = 8.4 Hz, 2H); δC (150 MHz, CDCl3) 147.4,
146.4, 137.2, 135.3, 129.5, 128.7, 127.8, 124.3; MS (EI): m/z 233 (90, M+).
4.3.27. 4-(4-Nitrophenyl)benzaldehyde (4aa).
4aa was obtained as a pale yellow solid; 95 mg (84% yield); mp 128–130°C (MeOH; lit.26 mp 127–
129 °C); Rf (petroleum ether/Et2O 9:1) 0.20; δH (600 MHz, CDCl3) 10.01 (s, 1H), 7.89 (d, J = 9.0
Hz, 2H), 7.99–7.97 (m, 2H), 7.77–7.75 (m, 4H); δC (150 MHz, CDCl3) 191.8, 147.8, 146.18, 144.5,
136.3, 130.5, 128.3, 128.2, 124.3; MS (EI): m/z 227 (100, M+).
4.3.28. 2-(4-Nitrophenyl)naphthalene (4ab).
4ab was obtained as a pale grey solid; 103 mg (83% yield from 1f and 3j) or 103 mg (83% yield
from 1g and 3c); mp 184–185°C (MeOH; lit.40 mp 183–184 °C); Rf (petroleum ether/Et2O 9:1)
0.35; δH (600 MHz, CDCl3) 8.32 (d, J = 9.0 Hz, 2H), 8.08 (d, J = 1.8 Hz, 1H), 7.96–7.95 (m, 1H),
7.93–7.88 (m, 1H), 7.86 (d, J = 9.0 Hz, 2H), 7.74–7.72 (m, 2H), 7.57–7.54 (m, 2H); δC (150 MHz,
CDCl3) 147.7, 147.2, 136.1, 133.5, 133.4, 129.1, 128.6, 128.1, 127.8, 127.0, 126.9, 124.9, 124.2;
MS (EI): m/z 249 (75, M+).
4.3.29. 2-Ethoxy-1-(4-nitrophenyl)naphthalene (4ac).
4ac was obtained as a pale grey solid; 37 mg (25% yield); mp 102–103°C (MeOH); [Found: C
73.75; H 5.12; N 4.74. C18H15NO3 requires C, 73.71; H, 5.15; N, 4.78%]; Rf (petroleum ether/Et2O
9:1) 0.25; νmax (neat) 2965, 1555, 1505, 1429, 1336, 1214, 1180, 1044, 836, 800, 718 cm−1; δH (600
MHz, CDCl3) 8.35 (d, J = 9.0 Hz, 2H), 7.56 (d, J = 9.0 Hz, 2H), 7.43–7.42 (m, 1H), 7.38–7.33 (m,
3H), 7.16–7.13 (m, 2H), 4.15 (q, J = 7.2 Hz, 4H), 1.26 (t, J = 7.2 Hz, 3H); δC (150 MHz, CDCl3)
153.1, 147.0, 144.3, 134.8, 132.3, 130.4, 129.5, 127.7, 127.0, 126.8, 124.0, 123.6, 123.4, 114.9,
63.5, 14.9; MS (EI): m/z 293 (100, M+), 265 (80), 218 (45), 189 (65).
4.3.30. Methyl 3-(2-methylphenyl)thiophene-2-carboxylate (6a).
6a was obtained as a white solid; 68 mg (59% yield); mp 103–104°C (MeOH; lit.41 mp 102–104
°C); Rf (petroleum ether/Et2O 9:1) 0.35; δH (600 MHz, CDCl3) 7.51 (d, J = 4.8 Hz, 1H), 7.32–7.20
(m, 4H), 6.97 (d, J = 5.4 Hz, 1H), 3.71 (s, 3H), 2.13 (s, 3H); δC (150 MHz, CDCl3) 162.3, 148.5,
136.1, 131.4, 130.6, 130.3, 129.8, 129.0, 128.0, 127.9, 125.3, 51.9, 20.0; MS (EI): m/z 232 (25,
M+).
4.3.31. Methyl 3-phenylthiophene-2-carboxylate (6b).
6b was obtained as a pale orange solid; 99 mg (91% yield); mp 115–116°C (MeOH; lit.42 mp 117–
118 °C); Rf (petroleum ether/Et2O 9:1) 0.38; δH (600 MHz, CDCl3) 7.51 (d, J = 4.8 Hz, 1H), 7.46–
7.40 (m, 2H), 7.38–7.37 (m, 3H), 7.07 (d, J = 4.8 Hz, 1H), 3.77 (s, 3H); δC (150 MHz, CDCl3)
162.5, 148.8, 135.7, 131.7, 130.4, 129.3, 128.0, 127.9, 126.9, 51.8; MS (EI): m/z 218 (85, M+).
4.3.32. Methyl 3-(4-chlorophenyl)thiophene-2-carboxylate (6c).

21
ACCEPTED MANUSCRIPT
6c was obtained as a pale grey solid; 106 mg (84% yield); mp 98–99°C (MeOH; lit.43 mp 98–99
°C); Rf (petroleum ether/Et2O 9:1) 0.40; δH (600 MHz, CDCl3): δ = 7.49 (d, J = 5.4 Hz, 1H), 7.39–
7.35 (m, 4H), 7.03 (d, J = 5.4 Hz, 1H), 3.77 (s, 3H); δC (150 MHz, CDCl3) 162.4, 147.5, 134.1,
134.0, 131.4, 130.7, 130.6, 128.1, 127.2, 52.1; MS (EI): m/z 252 (55, M+).
4.3.33. 3-(3-Nitrophenyl)pyridine (6d).
6d was obtained as a pale yellow solid; 81 mg (81% yield); mp 95–96°C (MeOH; lit.44 mp 93–95
°C); Rf (petroleum ether/Et2O 9:1) 0.35; δH (600 MHz, CDCl3) 8.82 (s, 1H), 8.59–8.57 (m, 2H),
8.25 (d, J = 7.2 Hz, 1H), 7.99 (t, J = 7.8 Hz, 2H), 7.70 (t, J = 7.8 Hz, 1H), 7.41 (t, J = 7.8 Hz, 1H);
δC (150 MHz, CDCl3) 149.3, 148.7, 147.7, 140.2, 135.9, 134.4, 131.1, 128.8, 125.5, 124.6, 122.5;
MS (EI): m/z 200 (85, M+).
4.3.34. 4-(3-Pyridinyl)benzaldehyde (6e).
6e was obtained as a pale grey solid; 72 mg (78% yield); mp 128–130°C (MeOH; lit.44 mp 127–129
°C); Rf (petroleum ether/Et2O 9:1) 0.42; δH (600 MHz, CDCl3) 9.92 (s, 1H), 8.82 (s, 1H), 8.57 (d, J
= 6.6 Hz, 1H), 7.98–7.97 (m, 3H), 7.80 (d, J = 8.4 Hz, 2H), 7.41 (t, J = 7.2 Hz, 1H); δC (150 MHz,
CDCl3) 191.9, 148.9, 147.9, 142.9, 137.4, 136.4, 131.4, 131.3, 128.9, 125.4; MS (EI): m/z 183 (55,
M+).
4.3.35. 2-(2-Methylphenyl)benzo[d]thiazole (6f).
6f was obtained as a pale orange solid; 54 mg (48% yield); mp 53–54°C (MeOH; lit.45 mp 52 °C);
Rf (petroleum ether/Et2O 9:1) 0.45; δH (600 MHz, CDCl3) 8.05–8.03 (m, 1H), 8.00–7.98 (m, 1H),
7.62–7.61 (m, 1H), 7.48–7.46 (m, 2H), 7.32–7.29 (m, 3H), 2.46 (s, 3H); δC (150 MHz, CDCl3)
168.1, 152.5, 136.5, 136.3, 135.4, 131.2, 130.7, 128.4, 127.4, 126.9, 125.5, 123.7, 122.2, 20.3; MS
(EI): m/z 225 (40, M+).
4.3.36. 2-(4-Chlorophenyl)benzo[d]thiazole (6g).
6g was obtained as a white solid; 86 mg (70% yield); mp 113–114°C (MeOH; lit.46 mp 115–116
°C); Rf (petroleum ether/Et2O 9:1) 0.50; δH (600 MHz, CDCl3) 8.05–8.03 (m, 1H), 8.00–7.98 (m,
1H), 7.60 (d, J = 7.2 Hz, 2H), 7.48–7.44 (m, 4H); δC (150 MHz, CDCl3) 162.1, 152.5, 137.8, 136.3,
136.1, 129.2, 128.3, 126.9, 125.3, 123.6, 122.7; MS (EI): m/z 245 (50, M+).
4.3.37. 3-(4-Methoxyphenyl)quinoline (6h).
6h was obtained as a grey solid; 93 mg (79% yield); mp 85–86°C (MeOH; lit.47 mp 83–85 °C); Rf
(petroleum ether/Et2O 9:1) 0.30; δH (600 MHz, CDCl3) 8.93 (s, 1H), 8.38 (s, 1H), 8.08 (d, J = 7.2
Hz, 1H), 7.72 (d, J = 7.2 Hz, 1H), 7.61–7.57 (m, 3H), 7.41 (t, J = 7.2 Hz, 1H), 7.05 (d, J = 8.4 Hz,
2H), 3.82 (s, 3H); δC (150 MHz, CDCl3) 158.5, 148.7, 148.4, 135.2, 135.1, 132.1, 129.9, 129.5,
129.2, 129.0, 128.7, 126.4, 114.5, 56.0; MS (EI): m/z 235 (65, M+).
4.3.38. 3-Phenylquinoline (6i).

22
ACCEPTED MANUSCRIPT
6i was obtained as a grey solid; 79 mg (77% yield); mp 50–51°C (MeOH; lit.47 mp 49–51 °C); Rf
(petroleum ether/Et2O 9:1) 0.38; δH (600 MHz, CDCl3) 8.97 (s, 1H), 8.41 (s, 1H), 8.09 (d, J = 7.2
Hz, 1H), 7.64–7.58 (m, 3H), 7.48–7.42 (m, 3H), 7.36–7.34 (m, 1H); δC (150 MHz, CDCl3): δ =
148.7, 148.4, 138.1, 135.2, 135.1, 132.1, 129.9, 129.2, 129.0, 128.7, 128.4, 126.8 126.4; MS (EI):
m/z 205 (70, M+).
4.4. Control experiments
4.4.1 In a oven-dried flask and under nitrogen flow, benzenediazonium o-benzenedisulfonimide
(1a, 161 mg, 0.5 mmol) was added to a suspension of 4-methoxyphenylboronic acid (3a, 91 mg,
0.6 mmol), [bis(trifluoromethanesulfonyl)imidate](triphenylphosphine)gold(I) (2:1) toluene adduct
(39 mg, 0.025 mmol, 5mol%), Cs2CO3 (325 mg, 1 mmol) and toluene (55 mg, 0.6 mmol) in THF (5
mL). The resulting mixture was stirred at room temperature for 2 h; the completion of the reaction
was confirmed by the absence of azo coupling with 2-naphthol. Then, the reaction mixture was
poured into diethyl ether/water (100 mL, 1:1). The aqueous layer was separated and extracted with
diethyl ether (50 mL). The combined organic extracts were washed with water (50 mL), dried with
Na2SO4 and evaporated under reduced pressure. GC analyses of the crude residue, beside target 4a
and other by-products, showed the precence of o, m, p-methylbiphenyl, each with MS (EI): m/z 168
(M+), in a 4.08:1:0.61 ratio. The structure of these three isomers was confirmed by comparison
with authentic and commercial samples (Sigma-Aldrich)
4.4.2. In a oven-dried flask and under nitrogen flow, 4-methoxyphenylboronic acid (3a, 91 mg, 0.6
mmol)
was added to
a
suspension of Cs2CO3 (325 mg,
1
mmol) and
[bis(trifluoromethanesulfonyl)imidate](triphenylphosphine)gold(I) (2:1) toluene adduct (942 mg,
0.6 mmol) in THF (5 mL). The resulting mixture was stirred at room temperature for about 1 h until
TLC, (petroleum ether/acetone 1:1) GC and GC-MS analyses showed the complete disappearance
of 3a. Moreover, 31PNMR spectrum of a reaction sample showed a peak at 43.0 ppm, in accordance
to the data reported in the literature for Ph3PAuPh.1h,8a
At this point, benzenediazonium o-benzenedisulfonimide (1a, 161 mg, 0.5 mmol) was added. The
mixture was stirred at room temperature for about 1.5 h; the completion of the reaction was
confirmed by the absence of azo coupling with 2-naphthol. The above described work-up furnished
4a (65 mg, 71% yield).
The same reaction was carried out using chloro(triphenylphosphine)gold (297 mg, 0.6 mmol). Even
after 8 h, TLC, GC and GC-MS analyses showed the presence of unreacted 3a. Anyhow,
benzenediazonium o-benzenedisulfonimide (1a, 161 mg, 0.5 mmol) was added. The mixture was

23
ACCEPTED MANUSCRIPT
stirred at room temperature for about 5 h and interrupted (though azo coupling with 2-naphthol was
still positive). The usual work-up furnished 4a (32 mg, 35% yield).
4.3.3. In a oven-dried flask and under nitrogen flow, benzenediazonium o-benzenedisulfonimide
(1a,
193
mg,
0.6
mmol)
was
added
to
a
solution
of
[bis(trifluoromethanesulfonyl)imidate](triphenylphosphine)gold(I) (2:1) toluene adduct (942 mg,
0.6 mmol) in THF (5 mL). The resulting mixture was stirred at room temperature for about 4 h;
however, unreacted 1a was still present as confirmed by azo coupling with 2-naphthol. At this
point, 4-methoxyphenylboronic acid (3a, 76 mg, 0.5 mmol) and Cs2CO3 (325 mg, 1 mmol) were
added. The mixture was stirred at room temperature for about 8 h and interrupted (though azo
coupling with 2-naphthol was still positive). GC-MS analyses of the crude residue showed a
complex mixture of products among which 4-methoxybiphenyl (4a), MS (EI): m/z 184 (M+) was
recognized.
Acknowledgements
This work has been supported by the University of Torino and the Ministero dell’Università e della
Ricerca.
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