Deep Eutectic Solvents as Reaction Media for the Palladium-Catalysed C?S Bond Formation: Scope and Mechanistic Studies

Article abstract of DOI:10.1002/chem.201702892

A unique jigsaw catalytic system based on deep eutectic solvents and palladium nanoparticles where C?S bonds are formed from aryl boronic acids and sodium metabisulfite, is introduced. The functionalization step is compatible with a broad spectrum of reagents such as nucleophiles, electrophiles or radical scavengers. This versatile approach allows the formation of different types of products in an environmentally friendly medium by selecting the components of the reaction, which engage one with another as pieces in a jigsaw. This simple procedure avoids the use of toxic volatile organic solvents allowing the formation of complex molecules in a one-pot reaction under mild conditions. Despite the fact that only 1 mol % of metal loading is used, the recyclability of the catalytic system is possible. Kinetic experiments were performed and the reaction order for all reagents, catalyst and ligand was determined. The obtained results were compared to palladium nanocrystals of different known shapes in order to shed some light on the properties of the catalyst.

Full text of DOI:10.1002/chem.201702892

A Journal of
Accepted Article
Title: Deep Eutectic Solvents as Reaction Media for the Palladium-
Catalysed C-S bond Formation. Scope and Mechanistic Studies
Authors: Diego J. Ramón, Gabriela Guillena, and Xavier Marset
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Chem. Eur. J. 10.1002/chem.201702892
Link to VoR: http://dx.doi.org/10.1002/chem.201702892
Supported by

10.1002/chem.201702892
Chemistry - A European Journal
COMMUNICATION
Deep Eutectic Solvents as Reaction Media for the Palladium-
Catalysed C-S bond formation. Scope and Mechanistic Studies
Xavier Marset,[a] Gabriela Guillena*[a] and Diego J. Ramón*[a]
Abstract: A unique jigsaw catalytic system based on deep eutectic
solvents, and palladium nanoparticles where C-S bonds are formed
from aryl boronic acids and sodium metabisulfite, is introduced. The
functionalization step compatible with a broad spectra of reagents
such as nucleophiles, electrophiles or radical scavengers. This
versatile approach allows the formation of different type of products in
an environmentally friendly medium by selecting the components of
the reaction, which engage one with another as pieces in a jigsaw.
This simple procedure avoids the use of toxic VOCs as solvents,
allowing the formation of complex molecules in a one pot reaction
under mild conditions. Despite that only 1 mol% of metal loading is
used, the recyclability of the catalytic system is possible. Kinetic
experiments have been performed and the reaction order for all
reagents, catalyst and ligand was determined. The obtained results
were compared to palladium nanocrystals of different known shapes
in order to shed some light on the properties of the catalyst.
was obtained. Moreover, aryl sulphides can be obtained via C-H
functionalization by a thiolation of phenol or phenylamine
derivatives mediated by iodine using a sulfinate salts as
intermediates.13
Deep Eutectic Solvents (DESs) have emerged as an
environmentally benign alternative to hazardous organic solvents,
as they are available, non-toxic, biodegradable, recyclable, non-
flammable, renewable and cheap being considered a green
solvent.14 Their properties, such as conductivity, viscosity, vapour
pressure and thermal stability can be fine-tuned by the
appropriate choosing of the mixture components.15 Furthermore,
due to the nature of the reaction media, all the inorganic salts and
organic reagents would became soluble, with precedents of
organosulfur compounds being compatible with DES media,
having being employed in simple organic transformations.16
With these precedents, the sulfonylation reaction of
phenylboronic acid (2a) with sodium metabisulfite (3) as SO2
source was tested. Pentyl bromide was added from the beginning
of the reaction, performing the sulfonylation and subsequent
alkylation of the sulfinate salt in one pot. Best result was obtained
using a mixture of choline chloride (ChCl) and acetamide with only
1 mol% of PdCl2. Since a phosphine ligand seems to be
necessary for the reaction to proceed at good reaction rates, we
decided to use recently reported phosphine ligand 117 (3 mol%,
Table S1, Chart 1). Other possible safe sources of SO2 were also
tested (Table S2) as well as alternative aryl sources (Table S3),
but none of them improved the result obtained with sodium
metabilsufilte and phenylboronic acid. Despite the good results
obtained with palladium chloride, other metallic catalysts were
tested (Table S4). It should be noticed that the inexpensive FeCl2
also afforded the desired product 5a in a 90% yield (Chart 1,
footnote b). Changing the ligand/metal ratio to 1:1 in order to
obtain a more active Pd(I) species did not improve the reaction
yield.18
Due to the constantly growing importance of sustainability, the
use of simple and versatile protocols for the synthesis of complex
molecules is a main goal in chemistry. While planning a synthetic
pathway to achieve a product, factors like selectivity, waste
production, toxicity, energy or the overall number of synthetic
steps should be taken into account to design an efficient
transformation.1 New strategies such as multicomponent
reactions (MCRs),2 diversity oriented synthesis (DOS)3 or multiple
bond-forming transformations (MBFTs)4 are tools which try to
maximize all these aspects. Nevertheless, in most cases the
scope of this kind of approaches is quite limited, not being
extensible for the synthesis of related substructures.
Approaches in which reagents of different nature, such as
electrophiles, nucleophiles and radicals are assembled in order to
obtain a complex molecule along with all these previous concepts
like pieces in a jigsaw must be urgently addressed.
Sulfones, interesting in drug industry,5 or as intermediates in
the total synthesis of complex molecules,6 are a clear example in
which a sustainable approach is demanded. Methodologies for
their synthesis such as sulfide oxidation,7 alkylation of sulfinate
salts,8 palladium-catalyzed insertion of SO2,9 or use of DABSO
under Pd or Au catalysis10 suffered severe limitations related to
reagents, substrates and products scope.
The unique properties of DES, allowed the catalytic system to
be recycled, using 2-MeTHF as a sustainable VOC.19 Products
were extracted, while the catalyst remained in the DES phase.
The reaction was repeated 3 times by the addition of fresh
reagents, without adding more metal, ligand or solvent. without a
significant decrease in the reaction yield (Figure 1), achieving an
accumulate TON of 279, much higher than the previous reports
using K2S2O5 as SO2 source, ranging from 6.6 to 15.8.11,12
More readily available K2S2O5 can be used as a SO2 source,
under Pd11 or Au12 catalysis (5-10 mol%), but due to the poor
solubility of the inorganic salt in the organic media a limited scope
100
80
60
40
20
0
[a]
X. Marset, Dr. G. Guillena, Prof. D. J. Ramón.
Instituto de Síntesis Orgánica (ISO), and Departamento de Química
Orgánica. Facultad de Ciencias, Universidad de Alicante.
Apdo. 99, E-03080, Alicante, Spain.
1
2
3
Cycle
E-mail: gabriela.guillena@ua.es, djramon@ua.es
† Electronic supplementary information (ESI) available:
characterization data, 1H-NMR and 13C-NMR data. See DOI: xxxxx
Figure 1. Recyclability study.
This article is protected by copyright. All rights reserved.

10.1002/chem.201702892
Chemistry - A European Journal
COMMUNICATION
Chart 1. Scope of boronic acids.a
ChCl:Acetamide(1:2)
80ºC, PdCl2 (1mol%)
O
S
O
+
Br
Na2S2O5+
R
B(OH)2
R
Cl
N
2
3
4a
5
1
PCy2 (3 mol%)
O
O
O
S
O
O
O
S
S
S
S
S
O
O
O
O
O
O
HO
MeO
5a, 99% (90%)b
5b, 51%(72%)c
5c, 49%
5d, 38%
5e, 65%
5f, 70%
O
O
O
S
O
S
O
O
S
O
S
S
S
S
O
O
S
O
O
O
O
N
O
F3C
5g,17% (0%)b
5h, 25% (13%)b
5i, 25% (13%)b
5j, 67%
5k,68% (51)b
5l, 0%
a Reaction carried out using compounds 2 (1.0 mmol), 3 (2.2 mmol) and 4a (2.0 mmol) in 2 mL of DES. b Reaction carried out using FeCl2 (1 mol%) instead of
PdCl2. c Reaction carried out using 3.0 mmol of ArB(OH)2, 6.6 mmol Na2S2O5 and 1.0 mmol of C5H11Br. Isolated Yields.
Table 1. Scope of electrophiles.a
ChCl:Acetamide(1:2)
O
80ºC, PdCl2 (1mol%)
E
B(OH)2
S
+
Na2S2O5
+
E
O
Cl
N
2a
3
4
6
1
PCy2 (3 mol%)
Entry
1
Electrophile
Product
No
Entry
8
Electrophile
Product
No
Yield
(%)b
Yield
(%)b
O
O
N
Br
S
N
Br
O
S
O
5a
99
6g
35
16
O
O
O
Br
S
O
S
S
H
S
H
O
2
3
4
6a
6b
6c
31
42
29
9
Br
6h
6i
O
O
O
S
Br
S
O
O
10
O
10
11
O
Br
(46)c
Br
O
OH
O
S
O
S
38
O
O
Br
6j
O
(99)c
OH
O
O
S
O
O
O
OMe
S
O
Cl
O
5
6d
30
12
O
6k
57
OMe
This article is protected by copyright. All rights reserved.

10.1002/chem.201702892
Chemistry - A European Journal
COMMUNICATION
Table 1. Scope of electrophiles.a (Continued)
BF4
O
O
S
I
S
O
CN
13
6
6e
6f
33
98
13
14
6l
(41)c
CN
O
O
O
NH2
N
N
S
S
H2N OSO3H
Cl
S
O
7
6m
S
98
O
a Reaction carried out using compounds 2a (1.0 mmol), 3 (2.2 mmol) and 4 (2.0 mmol) in 2 mL of DES. b Isolated yields. c Reaction carried out using 3.0 mmol
of ArB(OH)2, 6.6 mmol Na2S2O5 and 1.0 mmol of electrophile.
Under optimized conditions, the scope of boronic acids was
evaluated (Chart 1). The reaction gave moderate to good yields
Table 2. Scope of aryl sulfides.a
with electron-donating substituents (products 5b-5f), while
1) PdCl2 (1 mol%), 1 (3 mol%)
sterically hindered or electron-acceptor substituents afforded
ChCl:Acetamide (1:2),
80ºC, 12h
lower yields (products 5g-5i). On the other hand, heteroaromatic
S
+
ArB(OH)2
Na2S2O5
Ph
Nu
boronic acids were tested, obtaining good yields with thienyl
moieties. In order to prove the versatility of the synthesis, other
electrophiles were tested (Table 1). The reaction proved its
versatility for alkyl halides (entries 1-5). Product 6c (entry 4) was
obtained in a moderate yield, demonstrating that the mechanism
of the latest step of the reaction does not occur via a radical
pathway. Less conventional electrophiles as diaryliodonium salts
can be employed (entry 6). 2-Chlorobenzo[d]thiazole afforded
product 6f with excellent yield (entry 7). Electron-poor aryl halides
(entries 8-9) and alkenes (entries 10-13) can be also used as
electrophiles. Finally, the use of H2N-OSO3H afforded the
corresponding sulfonamide (entry 14).
2) I2 20 min
3) Nu-H 12h
2
3
7
Entry
1
Nucleophile
Product
Yield (%)b
Ph
S
OH
OH
7a
7b
70
OH
S
OH
OH
2
79
The versatility of this process was showed by adding
molecular iodine to the aryl sulfinate salt, that in a protic media
gives the corresponding thiol or disulphide,21 acting now as
electrophile. In this way, a three steps process-transformation
was performed in one pot (formation of the sulfinate salt,
transformation to thiol derivative and reaction with nucleophiles).
The obtained results are shown in Table 2, showing moderate to
good yields using phenol derivatives (entries 1-3), N,N-
dimethylaniline (entry 4), 1,3,5-trimethoxybenzene (entry 5) or
even indole (entry 6).
SPh
3
4
7c
7d
45
83
OH
OH
S
N
N
Also a radical process can take place in this new reaction
media (Table 3), affording the corresponding disulfide (entries 1-
2). If a hydroxy-functionalized alkene is added, the double bond
reacts with the radical thiol with a subsequent cyclization to afford
products 8c-8e (entries 3-5).8c Another radical-mediated reaction
is the synthesis of 8f from phenylpropiolic acid catalyzed by
phosphoric acid.20b
Intrigued by the unique properties of this catalytic system, the
evolution of the reaction between phenylboronic acid (2a) and
sodium metabisulphite (3) to form sodium benzenesulfinate was
evaluated (Figure S1). Assuming a simple equation rate and that
the reaction conditions allow a pseudo-first order approximation
for all reagents, the equation rate can be expressed as Ln roi = a
Ln [A]oi + k, where [A] is the initial concentration of reagent.
Therefore, we could estimate the reaction order for the reagents
by the estimation of the reaction rate for each trial and their
representation. For both reagents, PhB(OH)2 and Na2S2O5, we
obtained a value very close to 1.
OMe
OMe
S
5
7e
7f
84
63
MeO
OMe
MeO
OMe
S
N
H
6
N
H
a
Reaction carried out using compounds 2a (1.0 mmol), 3 (2.2 mmol) in 2
mL of DES during 12h, then I2 (2 mmol) was added and stirred for 20 min
and finally phenol/aniline derivative (2 mmol) was added and stirred for 12h
at 80°C. b All examples are shown with yields of isolated product.
This article is protected by copyright. All rights reserved.

10.1002/chem.201702892
Chemistry - A European Journal
COMMUNICATION
Table 3. Scope using radical scavengers.
100
80
60
40
20
0
1) PdCl2 (1 mol%) 1 (3 mol%)
ChCl:Acetamide (1:2),
80ºC, 12h
S
+
ArB(OH)2
Na2S2O5
Ph
R
2) I2 20 min
3) Radical Scanvenger (R), 12h
2
3
8
Cubic Pd NCs
Radical
Scavenger
Entry
1
Product
Yield (%)a
95b
Octahedra Pd NCs
Decahedra Pd NCs
PdCl2 + 1a
Ph
S
S
-
8a
8b
Ph
0
100
200
300
400
500
S
t (min)
2
-
66 b
Figure 2. Plot time-yield for different shaped Pd NCs and reaction carried out
with PdCl2 + 1.
MeO
2
O
62b
42b
HO
3
4
8c
8d
S
Ph
a)
b)
O
S
Ph
HO
O
O
98b
32c
O
5
8e
8f
HO
S
Ph
O
S
c)
d)
Ph
CO2H
Ph
6
O
a
b
All examples are shown with yields of isolated product. reaction carried
out using compounds 2a (1.0 mmol), 3 (2.2 mmol) in 2 mL of DES during
12h, then I2 (2 mmol) was added and stirred for 20 min and finally enol (2
mmol) was added and stirred for 12h at 80°C. c Instead of I2, Phenylpropiolic
Acid (2 mmol) and H3PO4 (4 mmol) were added to the reaction media after
8h and the reaction proceeded for 16h.
f)
e)
g)
On the other hand, for the determination of the reaction order
of the ligand and catalyst a graphical method was employed,22
founding a zero-order dependence for the ligand (Figure S2). This
fact suggest that the ligand plays a key role in the formation of the
Pd(0) nano-catalyst, but not in the rate-determining step of the
reaction.23 The order for the catalyst was found to be 0.25,
indicating a not simple reaction mechanism.
Furthermore, since Pd nanoparticles are formed during the
reaction, we prepared different shaped palladium nanocrystals
(Pd NCs) in order to evaluate their activity and compare it with our
catalytic system (Figure 2).24 The highest activity was achieved
with the nanoparticles obtained from PdCl2 and catonic phosphine
ligand 1, followed by the octahedral, cubic and finally decahedral
ones. Decahedral particles are reported to be very stable, with
almost a spherical structure, which may explain its lower activity.
On the other hand, the activity of the cubic and octahedral
particles was very similar, being the octahedral slightly more
active, probably due to the exposed surface facets {1 1 1} in front
of the ones on the cubic nanoparticles {1 0 0}.
Figure 3. TEM images corresponding to palladium nanoparticles a) cubes b)
cubes after reaction c) octahedron d) octahedron after reaction e) decahedron
f) decahedron after reaction g) PdCl2 + 1a after reaction.
After the reaction, NCs were recovered and analyzed, with
average sizes kept in the same range (See TEM in Table S5).
Regarding the shape, the well-defined facets were slightly lost,
This article is protected by copyright. All rights reserved.

10.1002/chem.201702892
Chemistry - A European Journal
COMMUNICATION
[11] a) A. Shavnya, S. B. Coffey, A. C. Smith, V. Mascitti, Org. Lett. 2013, 15,
6226-6229; b) A. Shavnya, K. D. Hesp, V. Mascitti, A. C. Smith, Angew.
Chem. 2015, 127, 13775-13779; Angew. Chem. Int. Ed. 2015, 54,
13571-13575.
due to leaching processes (Figure 3). The crude TEM of our
standard catalytic system (PdCl2 and ligand 1), showed Pd
clusters of 0.8 nm of average size, with around 14 Pd atoms. 25 In
such small particles, the electronic structure seems to play a key
role, with high surface area/volume ratio explaining its higher
activity. This can be correlated with the reaction order obtained
for PdCl2, which was found to be 0.25, suggesting maybe that only
¼ of the Pd atoms are catalytically active, which means that in a
14-atom palladium cluster, only around 3 atoms have catalytic
activity.22
[12] M. W. Johnson, S. W. Bagley, N. P. Mankad, R. G. Bergman, V. Mascitti,
F. D. Toste, Angew. Chem. 2014, 126, 4493-4496; Angew. Chem. Int.
Ed. 2014, 53, 4404-4407.
[13] a) D. Wang, R. Zhang, S. Lin, Z. Yan, S. Guo, RSC Adv. 2015, 5, 108030-
108033; b) F. Xiao, S. Chen, J. Tian, H. Huang, Y. Liu, G.-J. Deng, Green
Chem. 2016, 18, 1538-1546; c) Y. Yang, W. Li, C. Xia, B. Ying, C. Shen,
P. Zhang, ChemCatChem 2016, 8, 304-307.
[14] E. L. Smith, A. P. Abbot, K. S. Ryder, Chem. Rev., 2014, 114, 11060-
11082.
Conclusions
[15] a) Q. Zhang, K. D. O. Vigier, S. Royer, F. Jérôme, Chem. Soc. Rev.,
2012, 41, 7108-7146; b) J. García-Álvarez, Eur. J. Inorg. Chem. 2015,
5147-5157; c) D. A. Alonso, A. Baeza, R. Chinchilla, G. Guillena, I. M.
Pastor, D. J. Ramón, Eur. J. Org. Chem. 2016, 612-632
In conclusion, DES, PdCl2 and ligand 1 can be efficiently
applied to the jigsaw synthesis of molecules containing new C-S
bonds, starting from aryl boronic acids and sodium metabisulfite,
which undergo subsequent transformations in one-pot manner,
reacting with nucleophiles, electrophiles and radical scavengers
to afford sulfones and aryl sulfides. Furthermore, the catalytic
system could be recycled up to three times without a decrease in
the yield of the reaction. The high activity seems due to the very
small size of nanoparticles but not to the shape.
[16] a) N. Azizi, E. Batebi, Catal. Sci. Technol. 2012, 2, 2445–2448; b) N.
Azizi, Z. Yadollahy, A. Rahimzadeh-Oskoo, Tetrahedron Lett. 2014, 55,
1722-1725; c) G. Dilauro, L. Cicco, F. M. Perna, P. Vitale, V. Capriati, C.
R. Chimie, 2017, DOI: 10.1016/j.crci.2017.01.008.
[17] X. Marset, A. Khoshnood, L. Sotorríos, E. Gómez-Bengoa, D. A. Alonso,
D. J. Ramón, ChemCatChem; 2016, Accepted Article, DOI:
10.1002/cctc.201601544.
[18]
C. C. C. Johansson Seechurn, T. Sperger, T. G. Scrase, F.
Schoenebeck, T. J. Colacot, J. Am. Chem. Soc. 2017, 139, 5194-5200.
[19] D. Prat, O. Pardigon, H.-W. Flemming, S. Letestu, V. Ducandas, P.
Isnard, E. Guntrum, T. Senac, S. Ruisseau, P. Cruciani, P. Hosek, Org.
Process. Res. Dev. 2013, 17, 1517-1525.
Acknowledgements
This work was supported by the University of Alicante
(UAUSTI16-10, VIGROB-173), and the Spanish Ministerio de
Economía, Industria y Competitividad (CTQ2015-66624-P). XM
thanks Generalitat Valenciana (ACIF/2016/057) for fellowship.
[20] For selected examples see: a) S. Liang, R.-Y. Zhang, L.-Y. Xi, S.-Y. Chen,
X.-Q. Yu, J. Org. Chem. 2013, 78, 11874-11880; b) G. Rong, J. Mao, H.
Yan, Y. Zheng, G. Zhang, J. Org. Chem. 2015, 80, 7652-7657; c) J.
Maesin, P. Katrun, C. Pareseecharoen, M. Pohmakotr, V. Reutrakul, D.
Soorukram, C. Kuhakarn, J. Org. Chem. 2016, 81, 2744-2752.
[21] S. Oae, H. Togo, Bull. Chem. Soc. Jpn. 1983, 56, 3813-3817.
[22] J. Burés, Angew. Chem. 2016, 128, 2068-2071; Angew. Chem. Int. Ed.
2016, 55, 2028-2031.
Keywords: Green Chemistry • Palladium • Solvent Effects •
Sulfur • Multicomponent Reactions
[23] C. Amatore, A. Jutand, J. Organomet. Chem. 1999, 576, 254-278.
[24] G. Collins, M. Schmidt, C. O’Dwyer, J. D. Holmes, G. P. McGlacken,
Angew. Chem. 2014, 126, 4226-4229; Angew. Chem. Int. Ed. 2014, 53,
4142-4145.
[1]
[2]
[3]
[4]
[5]
P. T. Anastas, J. C. Warner in Green Chemistry: Theory and Practice
(Eds.: Oxford University Press), New York, 1998, p.30.
T. J. J. Müller in Multicomponent Reactions (Ed. Science of Synthesis),
Stuttgart, 2014.
[25] D. J. Lewis, T. M. Day, J. V. MacPherson, Z. Pikramenou, Chem.
Commun. 2006, 1433-1435.
C. J. O’Connor, H. S. G. Beckman, D. R. Spring, Chem. Soc. Rev. 2012,
41, 4444-4456.
D. Bonne, T. Constantineux, Y. Coquerel, J. Rodriguez, Chem. Eur. J.
2013, 19, 2218-2231.
For selected examples see: a) S. Patai, Z. Rappoport, C. Stirling, in
Sulphones and Sulphoxides. Ed. John Wiley and Sons Ltd, Chichester,
1988. b) C. R. Craig,R. E. Stitzel, in Modern Pharmacology with Clinical
Applications. Ed. LWW, Hagerstwon, 2004.
[6]
[7]
[8]
A. El-Awa, M. N. Noshi, X. Mollat du Jourdin, P. L. Fuschs, Chem. Rev.
2009, 109, 2315-2349.
K. Sato, M. Hyodo, M. Aoki, X.-Q. Zheng, R. Noyori, Tetrahedron 2001,
57, 2469-2476.
a) K. Yang, M. Ke, Y. Lin, Q. Song, Green Chem. 2015, 17, 1395-1399;
b) A. Rodríguez, W. J. Moran, J. Org. Chem. 2016, 81, 2543-2548; c)
Y.Gao, Y. Gao, X. Tang, J. Peng, M. Hu, W. Wu, H. Jiang, Org. Lett.
2016, 18, 1158-1161.
[9]
G. Pelzer, J. Herwig, W. Keim, R. Goddard, Russ. Chem. B+ 1998, 47,
904-912.
[10] a) H. Woolven, C. González-Rodríguez, I. Marco, A. L. Thomson, M. C.
Willis, Org. Lett. 2011, 13, 4876-4878; b) S. Ye, J. Wu, Chem. Commun.
2012, 48, 7753-7755; c) S. Ye, H. Wang, Q. Xiao, Q. Ding, J. Wu, Adv.
Synth. Catal. 2014, 356, 3225-3230;d) B. N. Rocke, K. B. Bahnck, M.
Herr, S. Lavergne, V. Mascitti, C. Perreault, J. Polivkova, A. Shavnya,
Org. Lett. 2014, 16, 154-157; e) G. Liu, C. Fan, J. Wu, Org. Biomol. Chem.
2015, 13, 1592-1599; f) A. S. Deeming, C. J. Russell, M. C. Willis, Angew.
Chem. 2016, 128, 757-760; Angew. Chem. Int. Ed. 2016, 55, 747-750.
This article is protected by copyright. All rights reserved.

10.1002/chem.201702892
Chemistry - A European Journal
COMMUNICATION
COMMUNICATION
A new process concept: a unique
catalytic system, where C-S bonds
are formed from aryl boronic acids
X. Marset, G. Guillena*, D. J. Ramón*
Page No. – Page No.
and
sodium
metabisulfite,
is
Deep Eutectic Solvents as Reaction
Media for the Palladium-Catalysed
C-S bond formation. Scope and
Mechanistic Studies.
introduced. The functionalization step
is compatible with nucleophiles,
electrophiles or radical scavengers
and principles of green chemistry, as
in a jigsaw. Kinetic experiments have
been performed, comparing results to
palladium nanocrystals of different
known shapes in order to shed some
light on the properties of the catalyst.
This article is protected by copyright. All rights reserved.