Indium-mediated allylation of carbonyl compounds in deep eutectic solvents

Article abstract of DOI:10.1002/aoc.6418

This study describes, for the first time, the in situ generation of indium organometallic reagents in environmentally friendly deep eutectic solvents (DESs). The allylation process of different carbonyl compounds is achieved mediated by indium metal and u

Full text of DOI:10.1002/aoc.6418

Received: 28 June 2021
DOI: 10.1002/aoc.6418
Revised: 26 July 2021
Accepted: 5 August 2021
R E S E A R C H A R T I C L E
Indium-mediated allylation of carbonyl compounds in deep
eutectic solvents
ꢀ
Nerea Gonzalez-Gallardo
| Beatriz Saavedra
| Gabriela Guillena
|
ꢀ
Diego J. Ramon
ꢀ
Departamento de Química Organica and
This study describes, for the first time, the in situ generation of indium organo-
metallic reagents in environmentally friendly deep eutectic solvents (DESs).
The allylation process of different carbonyl compounds is achieved mediated
by indium metal and using cheap allyl chloride derivatives. The unique DES
properties allow to perform the reaction at room temperature and under air,
obtaining yields ranging from 45% to 99%. It is possible to recycle the reaction
medium for at least four consecutive cycles without much decrease of the
observed results. Also, a linear correlation between the yield of the reaction
and the density of the DESs is observed.
ꢀ
Instituto de Síntesis Organica (ISO),
Facultad de Ciencias, Universidad de
Alicante, Alicante, Spain
Correspondence
ꢀ
Gabriela Guillena and Diego J. Ramon,
ꢀ
Departamento de Química Organica and
ꢀ
Instituto de Síntesis Organica (ISO),
Facultad de Ciencias, Universidad de
Alicante, Apdo. 99, 03080 Alicante, Spain.
Email: gabriela.guillena@ua.es;
djramon@ua.es
K E Y W O R D S
Funding information
Generalitat Valenciana, Grant/Award
Numbers: ACIF/2017/211,
allylation, green chemistry, indium, solvent effects, sustainability
ACIF/2020/186; Spanish Ministerio de
Economia, Industria y Competitividad,
Grant/Award Number:
PGC2018-096616-B-100; University of
Alicante, Grant/Award Numbers:
VIGORB20-170, VIGROB-316FI
1 | INTRODUCTION
has been described with different metals (Ga, Zn, Sn,
etc.), with indium reagents offering several advantages,
The allylation of carbonyl compounds via allylmetal
reagents is one of the most valuable transformations in
Organic Synthesis because it creates a new C C bond
and a stereocenter.[1] The presence of a C C double
bond in the resulting homoallylic alcohols is very inter-
esting leading to highly functionalized compounds, suit-
able for the synthesis of natural and pharmaceutical
compounds. This type of compounds has played an
essential role in organic chemistry for the development of
novel chemical structures. For instance, antitumor
agents, such as leucascandrolide A, or psychostimulants,
such as (ꢀ)-lobeline, possess this kind of structural
feauture.[2] The allylation process of carbonyl compounds
because they are minimally toxic, compatible with a great
variety of functional groups, and stable to air and mois-
ture (Scheme 1).[3] This Barbier-type allylation process
has been previously performed in classical organic
solvents,[4a,b] water,[4c,d] ionic liquids (ILs),[4e–k] and
under solvent-free conditions.[4l–n]
Despite water might be seemed as a sustainable
solvent, its use has some disadvantages including
incompatibility of several functional groups and high
cost in the treatment of residual streams.[5] Some ILs
have been found to be toxic and nonbiodegradable,
with
also
several
synthetic
steps
involving
nonsustainable procedures being required for their
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided
the original work is properly cited.
© 2021 The Authors. Applied Organometallic Chemistry published by John Wiley & Sons Ltd.
Appl Organomet Chem. 2021;e6418.
wileyonlinelibrary.com/journal/aoc
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https://doi.org/10.1002/aoc.6418

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GONZALEZ-GALLARDO ET AL.
SCHEME 1 Typical Barbier allylation of
carbonyl compounds
TABLE 1 Optimization of the reaction conditions
Entry
1
Solvent (mol:mol)
T (ꢁC)
90
X
Yield (%)a
ChCl:glycerol (1:2)b
ChCl:ethylene glycol (1:2)b
ChCl:urea (1:2)b
AcChCl:acetamide (1:2)b
ChCl:urea (1:2)b
ChCl:glycerol (1:2)b
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Cl
Cl
Cl
Cl
Cl
Cl
Cl
80
2
90
99
3
90
79
4
90
45
5
25
36
6
25
58
7
Decanoic acid:TBAB (2:1)
Decanoic acid:menthol (1:2)
ChCl:ethylene glycol (1:2)b
AcChCl:acetamide (1:2)b
ChCl:ethylene glycol (1:2)b
AcChCl:acetamide (1:2)b
ChCl:glycerol (1:2)b
25
23
8
25
33
9
25
99
10
11
12
13
14
15
16
17
25
62
75, 99c
25
25
35, 99,c 14,d 0,e 67,f 56,g 34,h 21,i 10,j 34k, l
25
68l
50l
20l
0
ChCl:urea (1:2)b
25
MePPh3Br:glycerol (1:2)
ChCl:L-malic acid (1:1)b
ChCl:D-galactose (5:2)b
25
25
25
0
Note: Reaction conditions: 1a (0.25 mmol), allyl halide 2 (0.5 mmol), and indium powder (0.5 mmol) in 0.5 ml of solvent were stirred at different temperatures
for 16 h.
aYield determined by CG using 4,40-di-tert-butylbiphenyl (DTBB) as internal standard.
bChCl stands for choline chloride; AcChCl stands for acetylcholine chloride; TBAB stands for tetrabutylammonium bromide.
c28 mol% of NH4Cl or NH4OAc were added.
d28 mol% of KOAc were added.
e28 mol% of NaOAc were added.
f20 μl of acetic acid were added.
g14 mol% of NH4Cl were added.
h14 mol% of NH4OAc were added.
i28 mol% of NaCl were added.
j28 mol% of LiCl were added.
kZinc powder was used instead of indium powder.
l28 mol% of NH4Cl was added.
preparation.[6] Solvent-free conditions might not be
widely applicable, because solvents allow the heat and
mass transfer, thus playing a crucial role in the reac-
tion outcome. In addition, they stabilize some
transition states and even govern the selectivity of the
reaction.[7] Therefore, the search for sustainable sol-
vents for these Barbier-type allylation reactions
remains in demand.

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GONZALEZ-GALLARDO ET AL.
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Deep eutectic solvents (DESs) are generally referred
to as combinations of two or more safe and inexpensive
components forming liquid eutectic mixtures mainly due
to electrostatic and hydrogen bond interactions between
components, with a melting point far lower than that of
the ideal mixture. DESs have interesting properties and
benefits in terms of sustainability, such as low cost, low
vapor pressure, nonflammability, and benign and safe
nature along with renewability and biodegradability.[8]
Although several studies using organometallic
reagents under aerobic conditions in DESs have already
been reported,[8a,9] in most of the cases, the organometal-
lic reagents were synthesized previously under standard
conditions, including inert atmosphere and using typical
volatile organic solvents. To the best of our knowledge,
only a recent study has reported the use of highly reactive
lithium phosphides generated in situ in choline chloride-
based eutectic mixtures under aerobic conditions.[9d]
Herein, it is described for the first time the allylation
reaction by the in situ generation of the organometallic
reagent in DESs, employing low reactive allyl chlorides
as a source of nucleophilic alkylating agents. Different
carbonyl compounds were used as electrophiles per-
forming the reaction at room temperature and under air
atmosphere. The obtained results were similar and even
better than those previously described in organic sol-
vents, water, and ILs.
acetylcholine chloride:acetamide (1:2) mixtures. When
28 mol% of ammonium acetate was added, compound 3a
was obtained in both mixtures with excellent yields
(Entries 11 and 12, footnote c).
This beneficial effect might be due to the presence of
acetate or ammonium ions in the reaction mixture or to a
change in the pH of the reaction that could help in the
stabilization of the involved indium species as it has been
previously described.[11] Therefore, the effect of the addi-
tion of several acetate salts and acetic acid was evaluated
in acetylcholine chloride:acetamide (1:2) mixture, which
presents less toxicity in higher concentrations than cho-
line chloride:ethylene glycol mixture.[12] Poor yields or
no reaction were obtained when potassium acetate
or sodium acetate or acetic acid in 70 mol% were added
to the reaction mixture (Entry 12, footnotes d–f, respec-
tively). The effect of the amount of ammonium salt was
also tested. The reaction was run with different quanti-
ties, obtaining the best results with 28 mol% (Entry
12, footnote c). It is worthy to note that better results
were obtained by using a 14 mol% of ammonium chloride
instead of ammonium acetate (Entry 12, footnotes g and
h). Recently, it has been demonstrated that simple NaCl
can enhance the efficiency of organozinc and orga-
nolithium compounds in sustainable solvents.[9e,13]
Therefore, the addition of NaCl and LiCl instead of
ammonium chloride was considered. Unfortunately, poor
yields were obtained in both cases (Entry 12, footnotes i
and j, respectively).
2 | RESULTS AND DISCUSSION
It is well known that similar Barbier transformations
have already been performed using Zn instead of In[14]
;
The study started with the optimization of the reaction
conditions employing acetophenone (1a), allyl halides
(2), and indium powder as a model reaction under Bar-
bier conditions (Table 1). Several DESs were tested as sol-
vent for this transformation at 90ꢁC, obtaining promising
results (Entries 1–4). Unfortunately, low yields were
observed when the reaction was carried out at room tem-
perature employing both hydrophilic (Entries 5 and 6)
and hydrophobic DESs (Entries 7 and 8). Only when cho-
line chloride:ethylene glycol (1:2) or acetylcholine chlo-
ride:acetamide (1:2) were used as solvents, good results
were achieved (Entries 9 and 10). Thus, it was decided to
test these two DESs employing allyl chloride instead of
allyl bromide. It is well known that allyl chlorides are
cheaper and more stable than allyl bromides, although
their reactivity is lower, being the reaction more chal-
lenging. As expected, product 3a was obtained with lower
yields. The addition of ammonium salts has been
reported to have a positive impact on this type of reaction
under aqueous conditions.[10] Therefore, we decided to
study the impact of the addition of the ammonium ace-
tate in both choline chloride:ethylene glycol (1:2) and
thus, the use of Zn powder was also tested, but moderate
yield was obtained (Entry 12, footnote k). In sight of
these results, the rest of the DESs were also evaluated by
adding 28 mol% of ammonium salt to the reaction mix-
ture, affording compound 3a with poor to moderate
yields (Entries 13–15). Finally, we tried to perform the
enantioselective process by using chiral DESs such as
choline chloride:(S)-malic acid (1:1), choline chloride:(S)-
lactic acid (1:2), choline chloride:(2R,R)-tartaric acid
(1:0.5), (S)-proline:(S)-malic acid (1:1), or choline chlo-
ride:D-galactose (5:2). Unfortunately, in all the cases, no
reaction was observed recovering the starting material
(see, for instance, Entries 16 and 17).
A parallel study of the reaction progress with time,
with both ammonium acetate and chloride, was carried
out (Table 1, Entry 12). Similar results were obtained in
both cases, being the reaction completed after 12 h
(Table 2, Entries 1–4). It was decided to use ammonium
chloride instead of ammonium acetate because it is
cheaper and easier to handle. Finally, a study of the ratio
of indium and allyl chloride was performed. All the
attempts to change the ratio between indium and allyl

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GONZALEZ-GALLARDO ET AL.
TABLE 2 Optimization of the reaction time and equivalents of the reagents
Yield (%)a
Entry
Time (h)
NH4Cl
NH4OAc
1
2
3
4
5
1
0
0
3
64
65
86
95
-
8
88
12
12
98
65,b 60,c 55,d 0e
Note: Reaction conditions: 1a (0.25 mmol), 2a (0.5 mmol), NH4Cl or NH4OAc (28 mol%), and indium powder (0.5 mmol) in 0.5 ml of acetylcholine chloride:
acetamide (1:2) were stirred at room temperature. Bold characters were used to highlight the best conditions.
aYield determined by CG using DTBB as internal standard.
b1.5 equiv. of 2a and indium powder.
c1.5 equiv. of 2a and 1 equiv. of indium powder.
d1 equiv. of 2a and indium powder.
eNo indium powder was used.
chloride were unsatisfactory with a significant drop in
the yield being observed (Table 2, Entry 5, footnotes b–d).
As it was expected, no reaction occurred when it was car-
ried out in the absence of indium powder (Table 2, Entry
5, footnote e).
yield (Entry 11). This result seems to indicate the hard
behavior of the generated nucleophile. Then, several
aldehydes were also tested as electrophiles, obtaining in
all the cases excellent results (Entries 12–14). Next, differ-
ent substituted allylic chlorides were evaluated with mod-
erate to good yields being obtained. The reaction was
compatible with methyl 2-(chloromethyl)acrylate (2b)
obtaining product 3o with moderate yield (Entry 15). The
corresponding double addition was observed when met-
hallyl dichloride (2c) was made to react as Y-aromatic
nucleophile source with different ketones, affording
product 3p and 3q with moderate yields (Entries 16–18).
When crotyl chloride (2d) was used, a mixture of diaste-
reoisomers was achieved with the major one being the
anti-isomer (Entry 19). When cinnamyl chloride (2e) was
used, a single diastereoisomer was formed in moderate
yield (Entry 20).
For γ-substituted allyl chloride derivatives (2d and
2e), the addition gave the γ-anti-adducts, as a major or
sole diastereoisomer. Based on the stereochemical out-
come observed, a cyclic Ireland-transition state was pro-
posed as the expected pathway, leading to the anti-
product as the major one (Scheme 2). The results
obtained in both cases are in concordance with those pre-
viously reported in the literature.[16]
With the optimal conditions in hand (Table 2, Entry
4), the scope of this transformation was evaluated
(Table 3). First, different ketones were used with excel-
lent to quantitative yields being obtained when electron-
withdrawing groups were attached to the aromatic ring
of the aryl ketones (Entries 2 and 3). Conversely, a lower
yield was observed when an electron-donating substitu-
ent was present in the ketone (Entry 4). An excellent
yield was achieved employing 4-phenylacetophenone as a
substrate (Entry 5). Good yield was obtained employing
an aryl ketone bearing a substituent at meta-position
(Entry 6). The reaction was also compatible with longer
carbon chain ketones and benzophenone, obtaining the
expected allylated product with good results (Entries
7 and 8). Cyclic ketones (α-tetralone and cyclohexanone)
were also compatible substrates, affording results from
good to excellent (Entries 9 and 10). The similarity in the
obtained results using acetophenone and α-tetralone
seems to indicate the low basicity of the generated nucle-
ophile.[15] An α,β-unsaturated carbonyl compound
(2-cyclohexenone) was also employed, and no conjugate
addition was observed, being the reaction selective,
obtaining exclusively 1,2-addition product with a good
Finally, mixture of isomers and homopropargylic and
allenylic alcohols (5 and 6) were obtained in 81% overall
yield, in a 25:75 ratio, respectively, when propargylic

ꢀ
GONZALEZ-GALLARDO ET AL.
5 of 9
TABLE 3 Scope of the reaction employing different carbonyl and allylic compounds
Entry
1
R1
R2
R3
R4
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
R5
Product
3a
Yield (%)a
Ph
Me
Me
Me
Me
Me
Me
Et
H
H
95
99
90
56
90
80
88
71
85
90
80
99
90
90
45
47
55
58
75
52
2
p-FC6H5
p-CF3C6H5
p-MeOC6H5
4-Biphenyl
m-MeC6H5
Ph
H
H
3b
3c
3
H
H
4
H
H
3d
3e
5
H
H
6
H
H
3f
7
H
H
3g
8
Ph
Ph
H
H
3h
3i
9
[1,2-C6H4(CH2)3]
(CH2)5
C5H8
H
H
10
11
12
13
14
15
16b
17b
18b
19
20
H
H
3j
H
H
3k
3l
Ph
H
H
H
Furyl
H
H
H
3m
3n
3o
3p
3q
3r
C6H11
Ph
H
H
H
Me
COOMe
CH2Cl
CH2Cl
CH2Cl
Me
H
(CH2)5
(CH2)4
Et
CH2C(OH)C6H11
CH2C(OH)C5H9
CH2C(OH)Et2
Me
Et
Ph
Me
Me
3s
Ph
Ph
Ph
3t
Note: Reaction conditions: carbonyl compound 1 (0.25 mmol), allyl chloride 2 (0.5 mmol), NH4Cl (28 mol%), and indium powder (0.5 mmol) in 0.5 ml of
acetylcholine chloride:acetamide (1:2) were stirred at room temperature for 12 h.
aIsolated yield.
bCarbonyl compound 1 (0.5 mmol), allyl chloride 2c (0.25 mmol), NH4Cl (28 mol%), and indium powder (0.25 mmol) in 0.5 ml of acetylcholine chloride:
acetamide (1:2) were stirred at room temperature for 12 h.
SCHEME 2 Ireland-transition state for the
allylation of carbonyl compounds

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GONZALEZ-GALLARDO ET AL.
chloride (4) was used as
(Scheme 3).
The recycling of the DES and NH4Cl was attempted
because it is a crucial point for the sustainability of the
process.[17] Extraction of the organic compounds using
a
nucleophilic source
was postulated that a solvent “cage radical pair” is pro-
duced when radical species are involved in the reaction,
and this “cage” is treated as a “hole” in the solvent itself.
Consequently, escaping from this “pocket” is mainly
determined by the density of the surrounding molecules
of the solvent. Therefore, the behavior of the radical spe-
cies might be related to the density and viscosity of the
solvent and that could determine the possibility of radi-
cals to escape from the “pocket.”[21] In order to corrobo-
rate whether the densities and viscosities of the DESs
could have a significant impact on the reaction output, a
correlation was carried out (Figure 3).
According to the aforementioned mechanism, a linear
relationship between the densities and the yield of the
reaction was observed, indicating that the higher density
the DES has, the lower yield is obtained (Figure 3, left).
A similar tendency between the viscosity of the DES and
the yield of the reaction product was also observed,
although a linear relationship could not be drawn, proba-
bly due to the use of macroviscosity values instead of
microviscosity ones, which are better parameters to pre-
dict radical recombination efficiences.[23] The viscosity of
the DES employed has an important role in the reaction
output, because a significant drop in the yield was
observed with an increase of the viscosity (Figure 3,
right). All these results pointed out that an important fac-
tor for the reaction process might be the radical escape
from the “cage,” which is highly dependent on the
immiscible
organic
solvents,
such
as
2-methyltetrahydrofuran (2-MeTHF, a renewable sol-
vent), was performed.[18] The mixture of DES and NH4Cl
was reused, after being vacuum dried, performing a new
reaction cycle under the same reaction conditions. It was
possible to recycle the DES and NH4Cl up to four cycles,
even though a slight decrease in the reaction yield was
observed (Figure 1). Because the reaction yield dropped
from 99% to 65% in the fifth cycle, in the sixth cycle, fresh
NH4Cl was added to the reaction medium, along with the
other reagents. An improvement of the reaction yield was
observed, but it was lower than in the first run. This
slight decrease in the results might be due to the accumu-
lative presence of different salts and the regarding metal,
affecting the DES structure.
In order to gain insight into the possible mechanism
of the reaction, several control experiments were per-
formed. When 2.0 equivalents of TEMPO were added as
a radical quencher, the reaction under standard condi-
tions did not take place and the desired product 3a was
not observed. Possible TEMPO adducts were analyzed,
and the formation of 2,2,6,6-tetramethylpiperidin-1-ol
was observed by GC–MS (Scheme 4), which seems to
indicate the formation of radical species.[19] This is in
concordance with a mechanism involving a radical path-
way for the generation of allylmetal species, as it is stated
previously in the literature.[20]
In addition, the evolution of reagents/products versus
reaction time was also studied. At the beginning of the
reaction, the amount of allyl chloride derivative 2e
(cinnamyl chloride) decreased; meanwhile, the ketone 1a
remained unchanged; and the final product 3t could not
be detected by GC of the hydrolyzed reaction crude mix-
ture. After an induction period of about 1 h and a half,
product 3t started to be formed, indicating the generation
of radical species in the medium prior to the formation of
product 3t (Figure 2).
Previous studies have demonstrated that neutral radi-
cal pairs are highly influenced and affected by solvent
viscosity and density, among other factors.[21] Thus, it
FIGURE 1 Recyclability of the system
SCHEME 3 Reaction between
acetophenone and propargylic chloride

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GONZALEZ-GALLARDO ET AL.
7 of 9
SCHEME 4 Reaction under the presence of
TEMPO
FIGURE 2 Evolution of reagents/products
versus time
FIGURE 3 Impact of solvent's densities on the yield of the reaction (left). Influence of the viscosity in the yield of the reaction (right).
*The density of MePPh3Br:Gly (1:2) was estimated from values of similar deep eutectic solvents (DESs) described in the literature[22]
solvent properties, such as density or viscosity. Thus,
based on the results observed, it seems that the lower
densities and viscosities favor the escape from the “cage,”
affording the highest yields.
reaction at least four consecutive cycles without any sig-
nificant decrease in the results employing a nontoxic sol-
vent medium. An interesting linear correlation between
the densities of the DESs used and the yield of the reac-
tion was observed, pointing out the importance of the
choice of DES, a tailor-made solvent, in order to achieve
the best results.
3 | CONCLUSIONS
In summary, the in situ generation of organoindium
reagents and the subsequent addition to different car-
bonyl compounds has been achieved for the first time in
DESs under mild, aerobic conditions showing the high
compatibility of DESs with organometallic reagents. In
terms of sustainability, it is worthy to mention that the
right choice of DES allowed the recyclability of the
ACKNOWLEDGMENTS
This work was supported by the University of Alicante
(VIGROB-316FI and VIGORB20-170) and the Spanish
Ministerio de Economia, Industria y Competitividad
(PGC2018-096616-B-100). NGG and BS thank Generalitat
Valenciana (ACIF/2020/186 and ACIF/2017/211, respec-
tively) for their fellowships.

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GONZALEZ-GALLARDO ET AL.
8 of 9
ꢀ
ꢀ
Ramon, Eur. J. Org. Chem. 2016, 612; c) D. J. Ramon, G.
Guillena, Deep Eutectic Solvents: Synthesis, Properties, and
Applications, Weinheim, Wiley-VCH 2019; d) F. M. Perna, P.
Vitale, V. Capriati, Curr. Opin. Green Sustain. Chem. 2020, 21,
27; e) L. Cicco, G. Dilauro, F. M. Perna, P. Vitale, V. Capriati,
Org. Biomol. Chem. 2021, 19, 2558; f) B. B. Hansen, S. Spittle,
B. Chen, D. Poe, Y. Zhang, J. M. Klein, A. Horton, L.
Adhikari, T. Zelovich, B. W. Doherty, B. Gurkan, E. J.
Maginn, A. Ragauskas, M. Dadmun, T. A. Zawodzinski, G. A.
Baker, M. E. Tuckerman, R. F. Savinell, J. R. Sangoro, Chem.
Rev. 2021, 121, 1232; g) D. Yu, Z. Xue, T. Mu, Chem. Soc. Rev.
2021, 50, 8596.
CONFLICT OF INTEREST
The authors declare no competing financial interest.
AUTHOR CONTRIBUTIONS
ꢀ
Nerea Gonzalez-Gallardo: Formal analysis; methodol-
ogy. Beatriz Saavedra: Formal analysis; methodology.
Gabriela Guillena: Conceptualization; investigation;
methodology. Diego J. Ramon: Conceptualization;
ꢀ
funding
acquisition;
investigation;
methodology;
supervision.
ꢀ
ꢀ
[9] a) C. Vidal, J. García-Alvarez, A. Hernan-Gomez, A. R.
DATA AVAILABILITY STATEMENT
Data are available in the Supporting Information.
Kennedy, E. Hevia, Angew. Chem., Int. Ed. 2014, 53, 5969;
ꢀ
ꢀ
b) C. Vidal, J. García-Alvarez, A. Hernan-Gomez, A. R.
Kennedy, E. Hevia, Angew. Chem., Int. Ed. 2016, 55, 16145;
c) E. Hevia, Chimia 2020, 74, 681; d) L. Cicco, A. Fombona-
ORCID
ꢀ
Nerea Gonzalez-Gallardo https://orcid.org/0000-0003-
ꢀ
Pascual, A. Sanchez-Condado, G. A. Carriedo, F. M. Perna, V.
ꢀ
4564-4072
Capriati, A. P. Soto, J. García-Alvarez, ChemSusChem 2020,
13, 4967; e) G. Dilauro, C. S. Azzollini, P. Vitale, A. Salomone,
F. M. Perna, V. Capriati, Angew. Chem., Int. Ed. 2021, 60,
10632; f) F. M. Perna, P. Vitalea, V. Capriati, Curr. Opin. Green
Sust. Chem. 2021, 30, 100487-(+7); g) S. E. García-Garrido,
Beatriz Saavedra https://orcid.org/0000-0002-7460-
7636
Gabriela Guillena https://orcid.org/0000-0001-5915-
351X
ꢀ
A. P. Soto, E. Hevia, J. García-Alvarez, Eur. J. Inorg. Chem.
ꢀ
Diego J. Ramon https://orcid.org/0000-0002-6784-0245
2021. https://doi.org/10.1002/ejic.202100347
[10] a) A. Jõgi, U. Mäeorg, Molecules 2001, 6, 964; b) A. Hui, X. Xu,
Z. Zha, C. Zhou, Z. Wang, ARKIVOC 2004, 9, 52.
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Kotesova, D. Kim, P. L. Holland, R. A. Shenvi, Chem. Sci.
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How to cite this article: N. Gonzalez-Gallardo,
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B. Saavedra, G. Guillena, D. J. Ramon, Appl
Organomet Chem 2021, e6418. https://doi.org/10.
1002/aoc.6418
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