The Heck reaction of allylic alcohols catalysed by an N-heterocyclic carbene-Pd(ii) complex and toxicity of the ligand precursor for the marine benthic copepod: Amphiascoides atopus

Article abstract of DOI:10.1039/d1ra03484g

The palladium-catalysed reaction of aryl halides and allylic alcohols is an attractive method for obtaining α,β-unsaturated aldehydes and ketones, which represent key intermediates in organic synthesis. In this context, a 1,2,3-triazol-5-ylidene (aNHC)-based palladium(ii) complex formed in situ has been found to be a selective catalyst for the syntheses of building blocks from the corresponding aryl halides and allylic alcohols, with yields ranging from 50% to 90%. The lack of toxic effects of the ligand precursor (1,2,3-triazolium salt) of the palladium(ii) complex for the harpacticoid copepod Amphiascoides atopus allowed us to contrast the efficiency of the catalytic system with the potential impact of the principal waste chemical in global aquatic ecosystems, which has not been previously addressed.

Full text of DOI:10.1039/d1ra03484g

RSC Advances
View Article Online
View Journal | View Issue
PAPER
The Heck reaction of allylic alcohols catalysed by
an N-heterocyclic carbene-Pd(II) complex and
toxicity of the ligand precursor for the marine
benthic copepod Amphiascoides atopus†
a
Cite this: RSC Adv., 2021, 11, 20278
Jorge Cardenas,
Ruben Gavino,a Erendira Garcıa-Rıos,a Lucero Rios-Ruiz,a
˜ ´ ´ ´
´
b
c
c
*
Francisco Neptalı Morales-Serna, Samuel Gomez,
´ ´
Ana C. Puello-Cruz,
Adolfo Lopez-Torresd and Jose Antonio Morales-Serna
d
*
´
´
The palladium-catalysed reaction of aryl halides and allylic alcohols is an attractive method for obtaining
a,b-unsaturated aldehydes and ketones, which represent key intermediates in organic synthesis. In this
context, a 1,2,3-triazol-5-ylidene (aNHC)-based palladium(II) complex formed in situ has been found to
be a selective catalyst for the syntheses of building blocks from the corresponding aryl halides and allylic
alcohols, with yields ranging from 50% to 90%. The lack of toxic effects of the ligand precursor (1,2,3-
triazolium salt) of the palladium(II) complex for the harpacticoid copepod Amphiascoides atopus allowed
us to contrast the efficiency of the catalytic system with the potential impact of the principal waste
chemical in global aquatic ecosystems, which has not been previously addressed.
Received 4th May 2021
Accepted 31st May 2021
DOI: 10.1039/d1ra03484g
rsc.li/rsc-advances
and Heck–Mizoroki cross-coupling reactions.9 In those cases,
the aNHC and palladium(II) complex are formed in situ from
Introduction
triazolium salts under mild reaction conditions. With these
relevant protocols, we focused on the use of a similar system in
the synthesis of a–b unsaturated aldehydes and ketones via the
Heck coupling of aryl halides and allylic alcohols, with the idea
of developing an efficient and selective protocol using 1,2,3-
triazol-5-ylidene (aNHC)-based palladium(II) complexes.
The high thermal stability and low vapour pressure make 1,2,3-
triazolium salts attractive for industrial eco-friendly processes. It is
assumed that their structural characteristics do not cause air
pollution or damage to occupational health. However, their
properties, such as resistance to photodegradation, water solu-
bility and stability, suggest that they may be a threat to aquatic
ecosystems due to bioaccumulation.10 For that reason, we
considered it necessary to compare the efficiency of the catalytic
system (aNHC-based palladium(II) complexes) with the impact of
Easy access to 1,2,3-triazoles via a simple copper-catalysed
azide–alkyne cycloaddition reaction (CuAAC) has led to the
development of a “post-click chemistry” strategy to obtain 1,2,3-
triazolium salts by selective alkylation at the N3 position of the
triazole ring.1 1,2,3-Triazolium salts represent an attractive
group of chemical compounds given that they can be used as
ionic liquids (ILs),2 as hosts in anion recognition, as compo-
nents of molecular machines and supramolecular assemblies3
or as precursors of abnormal (mesoionic)4 N-heterocyclic car-
benes (aNHCs) as a consequence of their high stability.5
As shown in Scheme 1, deprotonation and metalation of
1,2,3-triazolium salts give a 1,2,3-triazol-5-ylidene complex
(aNHC), which may be a precursor for an efficient catalyst for
organic reactions thanks to its unique electronic features and
donor properties.6 Recently, 1,2,3-triazolium iodide salts have
been used as efficient precursors for 1,2,3-triazol-5-ylidene
ligands7 (aNHCs) for palladium-catalysed Suzuki–Miyaaura8
a
´
´
´
Instituto de Quımica, Universidad Nacional Autonoma de Mexico, Circuito Exterior,
´
´
Ciudad Universitaria, Ciudad de Mexico, 04510, Mexico
b
´
´
´
Centro de Investigacion en Alimentacion y Desarrollo A.C., Unidad Academica
´
´
´
Mazatlan en Acuicultura y Manejo Ambiental, Mazatlan, Sinaloa, 82112, Mexico
c
´
´
Instituto de Ciencias del Mar y Limnologıa, Universidad Nacional Autonoma de
´
´
´
Mexico, Mazatlan, Sinaloa, 82040, Mexico. E-mail: neptali@ola.icmyl.unam.mx
d
´
Instituto de Quımica Aplicada, Universidad del Papaloapan, Tuxtepec, Oaxaca,
´
68301, Mexico. E-mail: joseantonio.moralesserna@gmail.com
† Electronic supplementary information (ESI) available. See DOI:
Scheme 1 Synthesis and uses of 1,2,3-triazolium salt.
10.1039/d1ra03484g
20278 | RSC Adv., 2021, 11, 20278–20284
© 2021 The Author(s). Published by the Royal Society of Chemistry

View Article Online
Paper
RSC Advances
the 1,2,3-triazolium salt precursor in aquatic ecosystems.11 Thus, cycloaddition (CuAAC) of alkyne 1, bromide derivatives 2a and
we evaluated its acute toxicity in the harpacticoid copepod 2b, and NaN3 under heterogeneous catalytic conditions. Then,
Amphiascoides atopus, considering that it will be among the prin- direct methylation of both nitrogen atoms of the triazole and
cipal waste chemicals eliminated aer the catalytic process.
pyridine ring allowed us to obtain 1,3,4-trisubstituted-1,2,3-
Sediments in aquatic ecosystems are rich in small crusta- triazolium iodide salts 4a and 4b (Scheme 2).
ceans, including benthic invertebrates, which are effective
Then, we were interested in evaluating the catalytic proper-
indicators of impacts at higher levels of biological organization ties of aNHC-based palladium(II) complexes formed in situ from
given their importance to overall ecosystem structure and 4a and 4b in the Heck reaction between bromo pyridine 5a and
function.12 In particular, marine copepods belonging to the allylic alcohol 6a to give ketone 7a. Aer various solvent systems
order Harpacticoida, one of the most abundant benthic inver- were examined, we concluded that DMF was the best solvent
tebrates and an important food source for macroinvertebrates (Table 1, entries 1–6). A higher reaction yield was obtained in
and sh, are suitable for use in tests that rapidly assess the the presence of Pd(OAc)2 and NaOAc (Table 1, entry 1).
acute, sublethal, or chronic effects of contaminants.13 To our Furthermore, the yield was lowered when the reaction was
knowledge, there are no previous studies testing the toxicity of carried out in the presence of PdCl2 (Table 1, entries 2 and 4) or
1,2,3-triazolium salts in copepods or in other crustaceans.
Results and discussion
Catalytic activity
Table 2 Scope of N-heterocyclic carbene and Pd(II) complex-cata-
lysed allylic alcohol Heck reactiona,b
Initially, we carried out the synthesis of 1,2,3-triazolium iodide
salts 4a and 4b with a simple copper-catalysed azide–alkyne
Scheme
2 Synthesis of 1,3,4-trisubstituted-1,2,3-triazolium iodide
salts 4a and 4b.
Table 1 Coupling of aryl halide 5a with allylic alcohol 6b in the
presence of 4a or 4ba
Entry
Solvent
Pd(II) source
Base
T (ꢀC)
Yieldb (%)
1
2
3
4
5
6
7
8
DMF
DMF
Toluene
Toluene
THF
Pd(OAc)2
PdCl2
Pd(OAc)2
PdCl2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
NaOAc
NaOAc
NaOAc
NaOAc
NaOAc
NaOAc
t-BuOK
K2CO3
NaOAc
NaOAc
NaOAc
90
90
90
90
Reux
90
90
90
50
80c and 78d
65c and 60d
67c and 60d
48c and 45d
0c and 0d
H2O
15c and 15d
70c and 60d
72c and 62d
55c and 50d
0c and 0d
DMF
DMF
DMF
DMF
DMF
9
10
rt
90
11e
82c and 80d
a
Reaction conditions: aryl halide 5a (1.0 mmol), allylic alcohol 6a (1.0
mmol), base (2.0 mmol), Pd(II) source (1 mol%), 1,2,3-triazolium salt 4
b
a
(1 mol%) and solvent (5 mL). Yields of isolated product aer
chromatographic purication. Yield obtained with 4a as aNHC mmol), NaOAc (2.0 mmol), Pd(OAc)2 (1 mol%), and 1,2,3-triazolium
precursor. Yield obtained with 4b as aNHC precursor. 5% of salt 4a (1 mol%) and DMF (5 mL). Yields of isolated product aer
Reaction conditions: aryl halide 5 (1.0 mmol), allylic alcohol 6 (1.0
c
d
e
b
Pd(OAc)2 and 5% of 1,2,3-triazolium salt 4 were used.
chromatographic purication.
© 2021 The Author(s). Published by the Royal Society of Chemistry
RSC Adv., 2021, 11, 20278–20284 | 20279

View Article Online
RSC Advances
Paper
when t-BuOK or K2CO3 was used as the base (Table 1, entries 7 presence of NaOAc to obtain in situ 1,2,3-triazol-5-ylidene
and 8). When the reaction was performed in THF under reux, (aNHC)-based palladium(II) complexes 8 (Scheme 3a), which
1
only the starting material was observed in the H NMR spec- should be the principal precursor to the catalytic species in the
trum of the reaction mixture (Table 1, entry 5). Product 7a was reaction. The catalytic process starts with the oxidative addition
obtained in 55% and 50% yields at 50 ꢀC (Table 1, entry 9), and of bromo pyridine 5a, followed by coordination and regiose-
it was not observed at room temperature (Table 1, entry 10) in lective alkene insertion (allylic alcohol 6a). Finally, Pd–H b-
the presence of 4a or 4b. When the reaction was carried out with elimination involving carbinol hydrogen furnished desired
5 mol% 4a or 4b and 5 mol% Pd(OAc)2, the yield did not carbonyl compound 7a.16
increase considerably (Table 1, entry 11). Notably, a complex
reaction mixture was obtained in the absence of triazolium salts
4a or 4b.
Toxicity of 1,2,3-triazolium salt 4a
Then, we used the harpacticoid copepod Amphiascoides atopus
as a model to evaluate the toxicity (LC50 at 24, 48, 72 and 96 h)
of 1,2,3-triazolium salt 4a. The results obtained were based on
the mortality of adult copepods, which varied signicantly
among triazolium salt concentrations at every exposure time
(Fig. 1, ANOVA: F ¼ 18.156 for 24 h, F ¼ 39.54 for 48 h, F ¼
45.562 for 72 h, and F ¼ 34.951 for 96 h; all P < 0.0001). There
was practically no mortality in unexposed (control) organisms
and those exposed to 30 mg Lꢁ1 4a. Some mortality was
observed at higher concentrations (Fig. 1); however, compared
to the control, signicant differences occurred above
250 mg Lꢁ1 at 24 h, 200 mg Lꢁ1 at 48 h, 150 mg Lꢁ1 at 72 h, and
100 mg Lꢁ1 at 96 h (all P < 0.05). The estimated LC50 values were
250.4 mg Lꢁ1 (CI 215.4 to 290.5 mg Lꢁ1) at 24 h, 173.9 mg Lꢁ1 (CI
150.4 to 196.4 mg Lꢁ1) at 48 h, 155 mg Lꢁ1 (CI 135.6 to
173.9 mg Lꢁ1) at 72 h, and 111.5 mg Lꢁ1 (CI 93.4 to
129.8 mg Lꢁ1) at 96 h. From these results and following the
Using the best reaction conditions, we next examined the
application of a 1,2,3-triazolium iodide and palladium salt
system from the 4a aNHC precursor for the cross-couplings of
a variety of aryl bromides with primary or secondary allylic
alcohols (Table 2). The results indicate that the aNHC-based
palladium(II) complex formed in situ constituted an efficient
and selective catalyst system for the synthesis of saturated
aldehydes 7b–7e and ketones 7f–7r in good yields. In the case of
tertiary allylic alcohols, the only nal products were a–b unsat-
urated alcohols (7s–7v, Table 2). Unfortunately, the reaction
does not evolve successfully when it was carried with aryl
chlorides. One of the principal drawbacks of the reaction
studied here is the formation of mixtures with both saturated
and unsaturated carbonyl compounds as principal products,14,15
which was not observed under our reaction conditions. Satu-
rated carbonyl compounds were obtained as the only product,
and unsaturated products (a–b unsaturated carbonyl
compounds) were not observed when crude products were
analysed by NMR.
Regarding the reaction mechanism, we propose the direct
metalation of 1,2,3-triazolium salt 4a with Pd(AcO)2 in the
Scheme 3 (a) Proposed structure of 1,2,3-triazol-5-ylidene (aNHC)-
based palladium(II) complex 8. (b) Proposed mechanism for synthesis Fig. 1 Toxicity of 1,2,3-triazolium salt 4a against (a) the harpacticoid
of a–b unsaturated aldehydes and ketones via the Heck coupling of copepod Amphiascoides atopus at (b) 24 h, (c) 48 h, (d) 72 h and (e)
aryl halide 5a and allylic alcohol 6a.
96 h. Asterisk (*) indicates significant difference from controls.
20280 | RSC Adv., 2021, 11, 20278–20284
© 2021 The Author(s). Published by the Royal Society of Chemistry

View Article Online
Paper
RSC Advances
hazard classication of the US EPA adopted by Tsarpali and
Dailianis17 for crustaceans, the triazolium salt tested in the
present study may be considered practically nontoxic since the
estimated LC50 values were >100 mg Lꢁ1 at every exposure time.
Similarly, Rodriguez Castillo et al.18 reported no toxicity of
[BMTriaz][NTf2] and [CF3CF2BTriaz][NTf2] triazolium salts
against zebrash Danio rerio.
The lack of toxic effect of triazolium salt 4a tested herein
could be attributed to its hydrophilic properties, which limit its
biocompatibility and adsorption onto or intercalation into the
cellular membrane.19 Our results are based only on the
mortality of adult copepods. This may be a shortcoming
considering that early developmental stages of copepods as well
as sublethal endpoints are more sensitive indicators of the
toxicity of contaminants.20 Additionally, further studies are
required to test the effect of the triazolium salt used in the
present work on other aquatic organisms, including marine and
freshwater species. However, it is noteworthy that there are no
previous studies testing the toxicity of triazolium salts in marine
eukaryotes or copepods because we consider that the LC50
values from toxicity bioassays described in the present work are
fundamental for future more ecologically relevant studies.21
Toxicity test
Copepods (A. atopus) were obtained from a stock maintained in
laboratory culture in a 15 L ask with ltered natural seawater
(35&) under natural conditions of photoperiod (typically, 12 h
light/12 h dark) and temperature (28 ꢂ 0.5 ꢀC), and fed with
microalgae diet.22
To choose the test concentrations a range-nding test was
performed. The denitive tests were performed in six-well
culture plates. Ten copepods (ovigerous females) were
randomly transferred to each well containing 5 mL of ltered
seawater (35&) at 28 ꢂ 0.5 ꢀC. Copepods were not fed and
exposed to increasing concentrations of 1,3,4-trisubstituted-
1,2,3-triazolium iodide salts 4a: 0, 30, 50, 100, 150, 200, 250,
300, 350, 450 and 550 mg Lꢁ1 for 96 h. Experiments were set up
with six replicates. Mortality of copepods was checked under
a stereomicroscope every 24 h. Copepods were considered dead
if they did not show movement of appendages and did not show
any reaction when transferred to wells with seawater without
1,3,4-trisubstituted-1,2,3-triazolium iodide salts 4a in a period
of up to 20 s of observation.
Signicant differences in mortality among different
concentrations of 1,3,4-trisubstituted-1,2,3-triazolium iodide
salts 4a were determined by one-way ANOVA with the Holm–
Sidak test posteriori, performed in RStudio soware. Signicant
differences were considered when P < 0.05. The LC50 value and
its respective 95% condence interval were determined by
probit analysis method (Finney, 1971) using PASW Statistics 18
soware (SPSS Inc. Chicago, IL, USA).
Conclusions
In summary, a 1,2,3-triazol-5-ylidene (aNHC)-based palladiu-
m(II) complex, formed in situ from a 1,2,3-triazolium salt, is an
efficient catalytic system for the formation of C–C bonds (Heck
coupling) in the selective synthesis of a–b unsaturated alde-
hydes and ketones from the corresponding aryl halides and
allylic alcohols. The efficiency of this catalytic system is rein-
forced by the null toxicity of the catalytic precursor (1,2,3-tri-
azolium salt) in the marine benthic copepod Amphiascoides
atopus. This result, in addition to the high thermal stability and
low vapour pressure of the catalytic precursor, allows a glimpse
of the low impact in air and in aquatic ecosystems resulting
from one of the main waste chemicals produced in the catalytic
process studied here.
General procedure
Synthesis of 1,2,3-triazoles 3a and 3b.23 To a solution of
alkyne 1 (1 mmol), benzyl halide 2a or 2b (1.2 mmol), NaN3 (1.2
mmol) in a mixture of THF–H2O (20 mL, 1 : 1 v/v), were added
sodium ascorbate (0.5 mmol%) and CuSO4 (0.5 mmol%). The
mixture was stirred at 50 ꢀC for 48 h. Aer the reaction time, the
mixture was cooled to room temperature and THF was elimi-
nated under vacuum. The resulting precipitate of the Cu
complex was decomposed by addition of small portions of
aqueous ammonia. Then, the mixture was diluted with ethyl
acetate (25 mL), washed with NaHCO3 (7% aqueous, 2 ꢃ 10 mL)
and brine (2 ꢃ 10 mL), dried over Na2SO4 and concentrated
under vacuum. The crude product was puried through a silica
gel column chromatography with a gradient AcOEt–hexane.
Synthesis of 1,2,3-triazolium salts 4a and 4b. A mixture of
1,2,3-triazole 3a or 3b (1.0 mmol) and CH3CN (10 mL) was
Experimental section
General methods
All reagents were purchased from Aldrich Chemical Co and
used without further purication unless stated otherwise.
Yields refer to the chromatographically and spectroscopically
(1H and 13C) homogeneous materials. The organic reactions
were monitored by TLC carried out on 0.25 mm E. Merck silica
gel plates. The developed TLC plates were visualised under
a short-wave UV lamp or by heating aer they were dipped in
Ce(SO4)2. Flash column chromatography (FCC) was performed
using silica gel (230–400) and employed a solvent polarity
correlated with the TLC mobility. NMR experiments were con-
ducted on a Varian 300 and Bruker 500 MHz instruments in
ꢀ
treated with CH3I (20.0 mmol) at 60 C for 48 h with vigorous
stirring. Then, the white precipitate obtained was ltered and
washed with acetonitrile and dried under vacuum to obtain the
corresponding 1,2,3-triazolium iodide salts 4a or 4b.
General procedure for the catalytic reactions
CDCl3 (99.9% D) and CD3OD (99.8% D) as solvents; the chem- In all Heck reactions, a DMF solution (5 mL) of 1 mmol of aryl
ical shis (d) were referenced to CHCl3 (7.26 ppm 1H, 77.00 ppm halide 5, 1.0 mmol of allylic alcohol 6, 2.0 mmol of NaOAc,
13C), CD3OD (4.87 ppm 1H, 49.00 ppm 13C), or TMS (0.00 ppm). 1% mmol of Pd(OAc)2 and 1% mmol of 1,2,3-triazolium salt 4
ꢀ
The chemical shis are reported in parts per million (ppm).
were heated for 6 h in a 90 C silicon oil bath equipped with
© 2021 The Author(s). Published by the Royal Society of Chemistry
RSC Adv., 2021, 11, 20278–20284 | 20281

View Article Online
RSC Advances
Paper
1
a condenser system. Aer the reaction time, the mixture was
cooled to room temperature and diluted with ethyl acetate (15
mL), washed with brine (3 ꢃ 10 mL), dried over Na2SO4 and
concentrated under vacuum. The crude product was puried
through a silica gel column chromatography with a gradient
AcOEt–hexane.
3-(Isoquinolin-4-il)butanal 7c (90% yield). NMR H (CDCl3,
300 MHz): d 9.85 (t, J ¼ 1.4 Hz, 1H), 9.16 (brs, 1H), 8.47 (brs, 1H),
8.09 (dd, J ¼ 8.2, 1.1 Hz, 1H), 8.01 (dd, J ¼ 8.0, 1.0 Hz, 1H), 7.78
(ddd, J ¼ 8.6, 6.8, 1.4 Hz, 1H), 7.64 (ddd, J ¼ 8.2, 6.8, 1.0 Hz, 1H),
4.15 (sex, J ¼ 6.8 Hz, 1H), 2.99 (ddd, J ¼ 16.1, 5.6, 1.2 Hz, 1H),
2.89 (ddd, J ¼ 16.8, 5.7, 1.4 Hz, 1H), 1.48 (d, J ¼ 6.8 Hz, 1H).
NMR 13C (CDCl3, 75 MHz): d 200.9, 151.7, 140.1, 134.5, 133.7,
130.6, 128.6, 128.45, 126.9, 121.9, 50.8, 26.9, 21.4. Anal. calcd for
13H13NO: C, 78.36; H, 6.58; N, 7.03. Found: C, 78.27; H, 6.47; N,
6.96.
3-(Quinolin-3-yl)butanal 7d (75% yield). NMR 1H (CDCl3, 300
MHz): d 9.73 (t, J ¼ 1.4, 1H), 8.81 (d, J ¼ 2.3, 1H), 8.08 (d, J ¼ 7.0,
1H), 7.97 (d, J ¼ 2.3, 1H), 7.78 (d, J ¼ 7.0, 1H), 7.64 (d, J ¼ 7.0,
1H), 7.56 (d, J ¼ 7.1, 1H), 3.57 (sex, J ¼ 7.2 Hz, 1H), 2.88 (ddd, J ¼
17.2, 6.8, 1.4, 1H, Hz), 2.76 (ddd, J ¼ 17.2, 7.4, 1.4 Hz, 1H), 1.40
(d, J ¼ 7.0 Hz, 3H). NMR 13C (CDCl3, 75 MHz, DEPT): d 200.6,
150.5, 146.8, 137.9, 132.8, 128.9, 127.9, 127.5, 126.7, 51.2, 31.5,
21.8. Anal. calcd for C13H13NO: C, 78.36; H, 6.58; N, 7.03. Found:
C, 78.30; H, 6.51; N, 6.95.
5-(4-Oxobutan-2-yl)furan-2-carbaldehyde 7e (85% yield).
NMR 1H (CDCl3, 300 MHz): d 9.79 (t, J ¼ 1.6 Hz, 1H), 9.54 (brs,
H1), 7.17 (d, J ¼ 3.6 Hz, 1H), 6.29 (d, J ¼ 3.6 Hz, 1H), 3.54 (m,
1H), 2.95 (ddd, J ¼ 17.6, 6.4, 1.6 Hz, 1H), 2.72 (ddd, J ¼ 17.6, 7.2,
1.6 Hz, 1H), 1.37 (d, J ¼ 7.2 Hz, 3H). NMR 13C (CDCl3, 75 MHz):
d 199.7, 177.2, 167.3, 151.9, 123.2, 107.9, 48.5, 27.8, 18.5. Anal.
calcd for C9H10O: C, 65.05; H, 6.07. Found: C, 64.96; H, 5.93.
5-(3-Pentanona)furan-2-carbaldehyde 7f (70% yield). NMR
1H (CDCl3, 300 MHz): d 9.65 (s, 1H), 7.33 (d, J ¼ 3.6 Hz, 1H, H-3),
6.43 (d, J ¼ 3.6 Hz, 1H), 3.16 (t, J ¼ 6.8 Hz, 2H), 3.02 (t, J ¼ 6.8 Hz,
2H), 2.62 (q, J ¼ 7.2 Hz, 2H), 1.21 (t, J ¼ 7.4, 3H). NMR 13C
(CDCl3, 75 MHz): d 208.9, 176.7, 161.9, 151.7, 123.6, 109.1, 39.2,
35.7, 22.2, 7.5. Anal. calcd for C10H12O3: C, 66.65; H, 6.71.
Found: C, 66.61; H, 6.67.
Characterization data
C
2-(1-(4-Bromobenzyl)-1H-1,2,3-triazol-4-yl)pyridine 3a (80%).
1H (CDCl3, 500 MHz): d 8.52 (ddd, J ¼ 4.5, 1.5, 1.0 Hz, 1H), 8.16
(ddd, J ¼ 8.0, 1.5, 1.0 Hz, 1H), 8.03 (brs, 1H), 7.75 (ddd, J ¼ 8.0,
7.5, 1.5 Hz, 1H), 7.35 (m, 4H), 7.19 (ddd, J ¼ 7.5, 4.5, 1.5 Hz, 1H),
5,57 (brs, 2H). NMR 13C (CDCl3, 125 MHz): d 150.4, 149.4, 148.5,
137.0, 134.5, 129.3, 128.9, 128.4, 122.97, 122.04, 120.03, 54.5.
Anal. calcd for C14H11BrN4: C, 53.35; H, 3.52; N, 17.78. Found: C,
53.30; H, 3.48; N, 17.73.
2-(1-(4-Iodobenzyl)-1H-1,2,3-triazol-4-yl)pyridine 3a (75%).
1H (CDCl3, 500 MHz): d 8.54 (ddd, J ¼ 4.5, 1.5, 1.0 Hz, 1H), 8.17
(ddd, J ¼ 8.0, 1.5, 1.0 Hz, 1H), 8.04 (brs, 1H), 7.76 (ddd, J ¼ 8.0,
7.5, 1.5 Hz, 1H), 7.71 (AA0BB0, m, 2H), 7.21 (ddd, J ¼ 7.5, 4.5,
1.5 Hz, 1H), 7.07 (AA0BB0, m, 2H), 5.52 (brs, 2H). NMR 13C
(CDCl3, 125 MHz): d 150.2, 149.5, 149.1, 138.4, 137.0, 134.2,
130.1, 123.0, 122.0, 120.3, 94.81, 53.9. Anal. calcd for C14H11IN4:
C, 46.43; H, 3.06; N, 15.47. Found: C, 46.37; H, 3.01; N, 15.42.
2-(1-(4-Bromobenzyl)-3-methyl-1H-1,2,3-triazol-3-ium-4-yl)-1-
methylpyridin-1-ium iodide 4a (50%). 1H (CD3OD, 500 MHz):
d 8.98 (brs, 1H), 8.97 (m, 1H), 8.59 (m, 1H), 8.49 (dd, J ¼ 8.0,
1.5 Hz, 1H), 8.02 (ddd, J ¼ 7.5, 6.0, 1.5 Hz, 1H), 7.57 (AA0BB0, m,
2H), 7.39 (AA0BB0, m, 2H), 5,57 (brs, 2H), 4.56 (brs, 3H), 3.31
(brs, 1H). NMR 13C (CD3OD, 125 MHz): d 148.2, 146.4, 140.2,
135.2, 133.2, 131.3, 129.9, 129.8, 129.6, 127.6, 123.8, 54.6, 49.2,
49.1. Anal. calcd for C16H17BrI2N4: C, 32.08; H, 2.86; Br, N, 9.35.
Found: C, 32.01; H, 2.82; N, 9.30.
5-(3-Oxo-3-phenylpropyl)furan-2-carbaldehyde
7g (85%
yield). NMR 1H (CDCl3, 300 MHz): d 9.41 (brs, 1H), 7.87 (d, J ¼
7.5 Hz, 2H), 7.41 (m, 3H), 7.11 (d, J ¼ 3.6 Hz, 1H), 6.25 (d, J ¼
3.5 Hz, 1H), 3.32 (t, J ¼ 7.2 Hz, 2H), 3.08 (t, J ¼ 7.2 Hz, 2H). NMR
13C (CDCl3, 75 MHz): d 197.4, 176.7, 162.1, 151.6, 135.9, 132.9,
128.4, 127.7, 123.7, 109.1, 35.7, 22.4. Anal. calcd for C14H12O3:
C, 73.67; H, 5.30. Found: C, 73.62; H, 5.27.
2-(1-(4-Iodobenzyl)-3-methyl-1H-1,2,3-triazol-3-ium-4-yl)-1-
methylpyridin-1-ium iodide 4b (45%). 1H (CD3OD, 500 MHz):
d 8.98 (brs, 1H), 8.97 (m, 1H), 8.59 (m, 1H), 8.49 (dd, J ¼ 8.0,
1.5 Hz, 1H), 8.02 (ddd, J ¼ 7.5, 6.0, 1.5 Hz, 1H), 7.57 (AA0BB0, m,
2H), 7.39 (AA0BB0, m, 2H), 5,57 (brs, 2H), 4.58 (s, 3H), 4.56 (s,
3H). NMR 13C (CD3OD3, 125 MHz): d 148.2, 146.5, 140.3, 135.2,
133.1, 131.4, 131.1, 129.9, 129.6, 127.6, 123.8, 54.7, 49.3, 49.2.
Anal. calcd for C16H17I3N4: C, 29.75; H, 2.65; Br, N, 8.67. Found:
C, 29.71; H, 2.59; N, 8.62.
5-(2-Butanone)furan-2-carbaldehyde 7h (85% yield). NMR 1H
(CDCl3, 200 MHz): d 9.44 (brs, 1H), 7.16 (d, J ¼ 3.6 Hz, 1H), 6.45
(d, J ¼ 3.6 Hz, 1H), 2.94 (m, 2H), 2.82 (m, 2H), 2.11 (s, 3H). NMR
13C (CDCl3, 75 MHz): d 206.1, 176.6, 161.8, 151.7, 123.5, 109.1,
40.5, 29.6, 22.1. Anal. calcd for C9H10O: C, 65.05; H, 6.07. Found:
C, 64.95; H, 5.94.
1-Phenyl-3-(pyridin-3-yl)propan-1-one 7a (80% yield). NMR
1H (CDCl3, 300 MHz): d 8.45 (brs, 1H), 8.35 (d, J ¼ 3.7 Hz, 1H),
7.86 (d, J ¼ 7.0 Hz, 2H), 7.52 (m, 4H), 7.14 (dd, J ¼ 7.5, 6.1 Hz,
1H), 3.19 (t, J ¼ 7.2 Hz, 2H), 2.98 (t, J ¼ 7.2 Hz, 2H). NMR 13C
(CDCl3, 75 MHz): d 198.1, 149.3, 146.9, 136.5, 136.2, 136.1, 133,
128.5, 127.7, 123.2, 39.3, 26.7. Anal. calcd for C14H13NO: C,
79.59; H, 6.20; N, 6.63. Found: C, 79.55; H, 6.17; N, 6.61.
2-(1-Methyl-3-oxopropyl)benzonitrile 7b (60% yield). NMR
1H (CDCl3, 300 MHz): d 9.84 (t, J ¼ 1.4 Hz, 1H), 7.62 (m, 2H), 7.18
(m, 2H), 3.68 (sex, J ¼ 7.2 Hz, 1H), 2.75 (dd, J ¼ 16, 7.2 Hz, 1H),
5-(2-Nitrobenzene)pentan-3-one 7i (90% yield). (CDCl3, 300
MHz): d 7.87 (d, J ¼ 8.0 Hz, 1H), 7.55 (dd, J ¼ 8.1 Hz, 7.3 Hz, 1H),
7.42 (m, 2H), 3.10 (t, J ¼ 7.4 Hz, 2H), 2.78 (t, J ¼ 7.6 Hz, 2H), 2.39
(q, J ¼ 7.4 Hz, 2H), 1.01 (t, J ¼ 7.4 Hz, 3H). NMR 13C (CDCl3, 75
MHz): d 209.7, 149.1, 136.3, 133.1, 132.3, 127.3, 124.7, 42.6, 35.8,
27.1, 7.6. Anal. calcd for C11H13NO3: C, 63.76; H, 6.32; N, 6.76.
Found: C, 63.70; H, 6.26; N, 6.71.
2.66 (dd, J ¼ 16, 7.2 Hz, 1H), 1.34 (d, J ¼ 7.2 Hz, 3H). NMR 13
C
4-(2-Nitrobenzene)butan-2-one 7j (90% yield). NMR 1H
(CDCl3, 300 MHz): d 7.88 (d, J ¼ 7.2 Hz, 1H), 7.51 (dd, J ¼ 8.0 Hz,
7.4 Hz, 1H), 7.39 (m, 2H), 3.11 (t, J ¼ 7.2 Hz, 2H), 2.85 (t, J ¼
(CDCl3, 75 MHz): d 200.3, 148.9, 133.3, 133, 127, 126.4, 117.8,
112, 50.5, 32.4, 21.4. Anal. calcd for C11H11NO: C, 76.28; H,
6.40; N, 8.09. Found: C, 76.25; H, 6.34; N, 8.01.
20282 | RSC Adv., 2021, 11, 20278–20284
© 2021 The Author(s). Published by the Royal Society of Chemistry

View Article Online
Paper
RSC Advances
7.2 Hz, 2H), 2.14 (s, 3H). NMR 13C (CDCl3, 75 MHz): d 206.8,
C
13H13NO: C, 78.36; H, 6.58; N, 7.03. Found: C, 78.32; H, 6.54; N,
148.9, 134.3, 133.0, 132.1, 127.2, 124.6, 43.8, 29.6, 26.9. Anal. 6.99.
calcd for C10H11NO3: C, 62.17; H, 5.74; N, 7.25. Found: C, 62.12;
(E)-5-(3-Hydroxy-3-methylbut-1-enyl)furan-2-carbaldehyde 7s
(80% yield). NMR 1H (CDCl3, 300 MHz): d 9.45 (s, 1H), 7.17 (d, J
H, 5.70; N, 7.19.
3-(2-Nitrobenzene)-1-phenylpropan-1-one 7k (70% yield). ¼ 3.6 Hz, 1H), 6.64 (d, J ¼ 15.8 Hz, 1H), 6.45 (d, J ¼ 15.8, 1H)
NMR 1H (CDCl3, 300 MHz): d 7.95 (m, 3H), 7.46 (m, 6H), 3.37 (m, 6.34 (d, J ¼ 3.6 Hz, 1H), 1.34 (s, 6H). NMR 13C (CDCl3, 75 MHz):
4H). NMR 13C (CDCl3, 75 MHz): d 198.4, 149.2, 136.5, 136.4, d 176.9, 158.3, 151.2, 143.1, 124.1, 113.8, 109.9, 70.7, 29.5. Anal.
133.1, 132.5, 128.5, 127.9, 127.4, 124.8, 39.3, 27.6. Anal. calcd for calcd for C10H12O3: C, 66.65; H, 6.71. Found: C, 66.59; H, 6.68.
C
15H13NO3: C, 70.58; H, 5.13; N, 5.49. Found: C, 70.51; H,
2-[(E)-1-Buten-3-methyl-3-ol]benzonitrile 7t (70% yield).
NMR H (CDCl3, 300 MHz): d 7.45 (m, 3H), 7.16 (dd, J ¼ 8.0,
1
5.05; N, 5.41.
2-(3-Oxo-3-phenylpropyl)benzonitrile 7l (50% yield). NMR 1H 7.8 Hz, 2H), 6.79 (d, J ¼ 16 Hz, 1H), 6.43 (d, J ¼ 16 Hz, 1H), 1.34
(CDCl3, 300 MHz): d 7.95 (d, J ¼ 7.8 Hz, 1H), 7.48 (m, 7H), 7.26 (t, (s, 6H). NMR 13C (CDCl3, 75 MHz): d 142.9, 140.3, 132.7, 132.6,
J ¼ 7.9 Hz, 1H), 3.32 (m, 4H). NMR 13C (CDCl3, 75 MHz): d 197.9, 127.3, 125.7, 122.2, 117.8, 110.6, 70.9, 29.4. Anal. calcd for
145.1, 136.3, 133.1, 132.8, 132.7, 129.9, 128.5, 127.9, 126.7,
C12H13NO: C, 76.98; H, 7.00; N, 7.48. Found: C, 76.94; H, 6.95; N,
117.9, 112.2, 38.9, 28.6. Anal. calcd for C16H13NO: C, 81.68; H, 7.43.
5.57; N, 5.95. Found: C, 81.60; H, 5.51; N, 5.89.
(E)-2-Metil-4-(quinolin-3-il)-3-buten-2-ol 7u (85% yield).
1
1-Phenyl-3-[4-(phenylcarbonyl)phenyl]propan-1-one
7m NMR H (CDCl3, 300 MHz): d 8.64 (brs, 1H), 8.04 (brs, 1H), 7.9
1
(75% yield). NMR H (CDCl3, 300 MHz): d 7.98 (d, J ¼ 7.0 Hz, (d, J ¼ 8.0 Hz, 1H), 7.43 (m, 2H), 7.36 (m, 1H), 6.61 (d, J ¼
2H), 7.79 (m, 4H), 7.45 (m, 8H), 3.35 (t, J ¼ 7.2 Hz, 2H), 3.17 (t, J 16.2 Hz, 1H), 6.44 (d, J ¼ 16.2, 1H), 1.33 (s, 6H). NMR 13C
¼ 7.2 Hz, 2H). NMR 13C (CDCl3, 75 MHz): d 198.7, 196.3, 146.4, (CDCl3, 75 MHz): d 149.1, 145.6, 136.9, 129.4, 128.8, 127.3,
137.6, 136.5, 135.4, 133.1, 132.3, 130.4, 129.8, 128.5, 128.3, 126.6, 140.4, 122.7, 116.7, 70.3, 29.7. Anal. calcd for C14H15NO:
128.1, 127.9, 39.7, 29.8. Anal. calcd for C22H18O2: C, 84.05; H, C, 78.84; H, 7.09; N, 6.57. Found: C, 78.79; H, 7.02; N, 6.51.
5.77. Found: C, 83.98; H, 5.71.
(3E,E0)-4,40-Pyridine-3,5-di(yl)bis(3-buten-2-methyl-2-ol) 7v
2-(3-Oxopentyl)-9H-uorene-9-one 7n (80% yield). NMR 1H (75% yield). NMR H (CDCl3, 300 MHz): d 8.56 (brs, 2H), 7.98
(CDCl3, 300 MHz): d 7.62 (d, J ¼ 7.9 Hz, 1H), 7.35 (m, 6H), 2.92 (t, (brs, 1H), 6.51 (d, J ¼ 15.9 Hz, 2H), 6.38 (d, J ¼ 15.9, 2H), 1.39 (s,
J ¼ 7.4 Hz, 2H), 2.76 (t, J ¼ 7.4 Hz, 2H), 2.43 (q, J ¼ 7.2 Hz, 2H), 12H). NMRN 13C (CDCl3, 75 MHz): d 149.0, 141.7, 135.3, 121.4,
1.05 (t, J ¼ 7.4 Hz, 3H). NMR 13C (CDCl3, 75 MHz): d 210.5, 120.8, 70.9, 29.8. Anal. calcd for C15H21NO2: C, 72.84; H, 8.56; N,
194.5.8, 144.6, 142.8, 138.1, 136.9, 135.3, 134.5, 133.8, 124.8, 5.66. Found: C, 72.80; H, 8.51; N, 5.62.
124.5, 124.2, 123.9, 122.6, 43.8, 29.8, 20.6, 7.5. Anal. calcd for
1
C
18H16O2: C, 81.74; H, 6.10. Found: C, 81.68; H, 6.02.
Conflicts of interest
1-(Naphthalene-yl)pentan-3-one 7o (60% yield). NMR 1H
(CDCl3, 300 MHz): d 7.95 (m, 4H), 7.62 (m, 3H), 3.48 (t, J ¼
7.4 Hz, 2H), 2.84 (t, J ¼ 7.6 Hz, 2H), 2.47 (q, J ¼ 7.4 Hz, 2H), 1.17
(t, J ¼ 7.2 Hz, 3H). NMR 13C (CDCl3, 75 MHz): d 210.5, 137.1,
There are no conicts to declare.
133.6, 131.7, 128.8, 127.7, 127.1, 125.8, 125.4, 125.3, 123.3, 42.8, Acknowledgements
35.8, 26.6, 7.6. Anal. calcd for C15H16O: C, 84.87; H, 7.60. Found:
C, 84.82; H, 7.56.
JAMS is grateful to the Royal Society (UK) for the International
Alumni Grant.
4-(Naphthalene-1-yl)butan-2-one 7p (55% yield). NMR 1H
(CDCl3, 300 MHz): d 7.85 (d, J ¼ 7.9 Hz, 1H), 7.75 (m, 3H), 7.46
(m, 3H), 3.30 (t, J ¼ 7.4 Hz, 2H), 2.79 (t, J ¼ 7.2 Hz, 2H), 2.07 (s,
3H). NMR 13C (CDCl3, 75 MHz): d 207.6, 136.8, 133.6, 131.5,
128.8, 127.8, 126.8, 125.9, 125.8, 125.4, 125.3, 44.2, 29.9, 26.6.
Anal. calcd for C14H14O: C, 84.81; H, 7.12. Found: C, 84.75; H,
7.05.
Notes and references
´
1 J. M. Aizpurua, R. M. Fratila, Z. Monasterio, N. Perez-
Esnaola, E. Andreieff, A. Irastorza and M. Sagartzazu-
Aizpurua, New J. Chem., 2014, 38, 474.
4-(Isoquinolin-4-yl)butan-2-one 7q (75% yield). NMR 1H
(CDCl3, 300 MHz): d 9.10 (s, 1H), 8.40 (s, 1H), 8.12 (d, J ¼ 7.5 Hz,
1H), 7.7 (m, 3H), 3.27 (t, J ¼ 7.2 Hz, 2H), 2.85 (t, J ¼ 7.2 Hz, 2H),
2.16 (s, 3H). NMR 13C (CDCl3, 75 MHz): d 206.8, 151.3, 144.2,
133.9, 131.2, 129.8, 128.1, 127.4, 126.6, 125.4, 42.5, 29.7, 23.1.
Anal. calcd for C13H13NO: C, 78.36; H, 6.58; N, 7.03. Found: C,
78.31; H, 6.52; N, 6.97.
2 (a) R. Mishra, J. S. Mishra and S. A. Chaubey, Curr. Org.
Chem., 2019, 23, 1239; (b) X. Zhou, J. Weber and J. Yuan,
Curr. Opin. Green Sustain. Chem., 2019, 16, 39.
3 (a) M. S. Shad, P. V. Santhini and W. Dehaen, Beilstein J. Org.
Chem., 2019, 15, 2142; (b) B. Schulzeab and U. S. Schubert,
Chem. Soc. Rev., 2014, 43, 2522.
4 (a) M. A. Sierra and M. C. de la Torre, ACS Omega, 2019, 4,
12983; (b) G. Guisado-Barrios, M. Soleilhavoup and
G. Bertrand, Acc. Chem. Res., 2018, 51, 3236; (c) D. Huanga,
P. Zhaoa and D. Astrucb, Coord. Chem. Rev., 2014, 272, 145;
(d) R. H. Crabtree, Coord. Chem. Rev., 2013, 257, 755.
4-(Quinolin-3-yl)butan-2-one 7r (65% yield). NMR 1H (CDCl3,
300 MHz): d 8.65 (s, 1H), 8.01 (s, 1H), 7.88 (m, 1H), 7.45 (m, 3H),
2.85 (t, J ¼ 7.4 Hz, 2H), 2.65 (t, J ¼ 7.0 Hz, 2H), 1.95 (s, 3H). NMR
13C (CDCl3, 75 MHz): d 206.6, 150.9, 148.9, 134.1, 130.5, 129.1,
128.1, 127.5, 127.3, 126.6, 44.1, 29.7, 26.5. Anal. calcd for
´
5 A. Vivancos, C. Segarra and M. Albrecht, Chem. Rev., 2018,
118, 9493.
© 2021 The Author(s). Published by the Royal Society of Chemistry
RSC Adv., 2021, 11, 20278–20284 | 20283

View Article Online
RSC Advances
Paper
6 P. Mathew, A. Neels and M. Albrecht, J. Am. Chem. Soc., 2008,
130, 13534.
Chem. Commun., 1997, 1275; (c) J. B. Melpolder and
R. F. Heck, J. Org. Chem., 1976, 41, 265.
7 E. Kleinpeter and A. Koch, Tetrahedron, 2019, 75, 1548.
8 (a) C. R. Shahini, G. Achar, S. Budagumpi, R. B. Dateer,
16 I. Ambrogio, G. Fabrizi, S. Cacchi, S. T. Hnriksen, P. Fristrup,
D. Tanner and P.-O. Norrby, Organometallics, 2008, 27, 3187.
¨
H. Muller-Bunz, M. Tacke and S. A. Patil, J. Coord. Chem., 17 V. Tsarpali and S. Dailianis, Ecotoxicol. Environ. Saf., 2015,
ˇ
2019, 72, 528; (b) A. Bolje and J. Kosmrlj, Org. Lett., 2013,
117, 62.
´
´
15, 5084; (c) T. Karthikeyan and S. Sankararaman, 18 A. S. Rodriguez Castillo, S. Guiheneuf, R. L. Guevel,
Tetrahedron Lett., 2009, 50, 5834.
9 S. Modak, M. K. Gangwar, M. Nageswar Rao, M. Madasu,
P. F. Biard, L. Paquin, A. Amrane and A. Couvert, J.
Hazard. Mater., 2016, 307, 221.
A. C. Kalita, V. Dorcet, M. A. Shejale, R. J. Butcher and 19 (a) R. S. Meinela, A. C. Almeidab, P. H. F. Stroppaa,
P. Ghosh, Dalton Trans., 2015, 44, 17617.
N. Glanzmanna, E. S. Coimbrab and A. D. da Silvaa,
Chem.-Biol. Interact., 2020, 315, 108850; (b) R. Wang, Y. Li
and W. Dehaen, Eur. J. Med. Chem., 2020, 207, 112737; (c)
J. T. Fletcher, J. M. Sobczyk, S. C. Gwazdacz and
A. J. Blanck, Bioorg. Med. Chem. Lett., 2018, 28, 3320; (d)
N. Glanzmann, A. M. L. Carmo, L. M. R. Antinarelli,
E. S. Coimbra, L. A. S. Costa and A. D. da Silva, J. Mol.
Model., 2018, 24, 160; (e) S. P. F. Costa, P. C. A. G. Pinto,
M. L. M. F. S. Saraiva, F. R. P. Rocha, J. R. P. Santos and
R. T. R. Monteiro, Chemosphere, 2015, 139, 288; (f)
10 (a) J. M. Gomes, S. S. Silva and R. L. Reis, Chem. Soc. Rev.,
2019, 48, 4317; (b) S. P. M. Ventura, A. M. M. Gonçalves,
T. Sintra, J. L. Pereira, F. Gonçalves and J. A. P. Coutinho,
Ecotoxicology, 2013, 22, 1; (c) D. J. Couling, R. J. Bernot,
K. M. Docherty, J. K. Dixon and E. J. Maginn, Green Chem.,
2006, 8, 82.
´
11 (a) B. Pawłowska, A. Telesinski and R. Biczak, Chemosphere,
2019, 237, 124436; (b) S. P. F. Costa, A. M. O. Azevedo,
P. C. A. G. Pinto and M. L. M. F. S. Saraiva, ChemSusChem,
2017, 10, 232; (c) M. Bystrzanowskaa, F. Pena-Pereirab,
L. Marcinkowskic and M. Tobiszewskia, Ecotoxicol. Environ.
Saf., 2019, 174, 455.
¨
S. Stolte, M. Matzke, J. Arning, A. Boschen, W.-R. Pitner,
U. Welz-Biermann, B. Jastorff and J. Ranke, Green Chem.,
2007, 9, 1170.
12 (a) T. J. Caneld, N. E. Kemble, W. G. Brumbaugh, 20 (a) G. R. Lotufo, Mar. Environ. Res., 1997, 44, 149; (b)
F. J. Dwyer, C. G. Ingersoll and J. F. Fairchild, Environ.
Toxicol. Chem., 1994, 13, 1999; (b) G. R. Bilyard, Mar.
Pollut. Bull., 1987, 18, 581.
A. Macken, A. Lillicrap and K. Langford, Environ. Toxicol.
Chem., 2015, 34, 1533.
21 R. J. Bernot, M. A. Brueseke, M. A. Evans-White and
G. A. Lamberti, Environ. Toxicol. Chem., 2005, 24, 87.
13 (a) A. Macken, A. Lillicrap and K. Langford, Environ. Toxicol.
´
Chem., 2015, 34, 1533; (b) D. J. Ward, V. Perez-Landa, 22 A. C. Puello-Cruz, S. Gomez, F. N. Morales-Serna,
´
D. A. Spadaro, S. L. Simpson and D. F. Jolley, Arch. Environ.
Contam. Toxicol., 2011, 61, 414.
P. M. Rodrıguez-Valenzuela and E. A. Pelayo-Romero, Proc.
Biol. Soc. Wash., 2014, 127, 78.
´
˜
14 A. Sauza, J. A. Morales-Serna, M. Garcıa-Molina, R. Gavino 23 M. Obata, A. Kitamura, A. Mori, C. Kameyama,
´
and J. Cardenas, Synthesis, 2012, 44, 272.
J. A. Czaplewska, R. Tanaka, I. Kinoshita, T. Kusumoto,
H. Hashimoto, M. Harada, Y. Mikata, T. Funabiki and
S. Yano, Dalton Trans., 2008, 3292.
15 (a) J. Liu, J. Zhu, H. Jiang, W. Wang and J. Li, Chem.
Commun., 2010, 46, 415; (b) J. Li, A. Mau and C. R. Strauss,
20284 | RSC Adv., 2021, 11, 20278–20284
© 2021 The Author(s). Published by the Royal Society of Chemistry