Tetrabutylphosphonium 4-ethoxyvalerate as a biomass-originated media for homogeneous palladium-catalyzed Hiyama coupling reactions

Article abstract of DOI:10.1007/s11696-020-01287-y

The introduction of a biomass-derived ionic liquid into the Hiyama coupling reactions, which has been considered as a powerful tool for the synthesis of symmetrically and non-symmetrically substituted biaryl structures, could further control or even reduce the environmental impact of this transformation. It was shown that tetrabutylphosphonium 4-ethoxyvalerate, a γ-valerolactone-based ionic liquid, can be utilized as an alternative solvent to create carbon–carbon bonds between aryl iodides and functionalized organosilanes in the presence of 1?molpercent Pd under typical Hiyama conditions (130?°C, 24?h, tetrabutylammonium fluoride activator). A comparison of different ionic liquids was performed, and the effects of the catalyst precursor and the moisture content of the reaction mixture on the activity of the catalyst system were investigated. The functional group tolerance was also studied, resulting in 15 cross-coupling products (3a–o) with isolated yields of 45–72percent and excellent purity (' 98percent).

Full text of DOI:10.1007/s11696-020-01287-y

Chemical Papers
https://doi.org/10.1007/s11696-020-01287-y
ORIGINAL PAPER
Tetrabutylphosphonium 4‑ethoxyvalerate as a biomass‑originated
media for homogeneous palladium‑catalyzed Hiyama coupling
reactions
László Orha1,2 · Ábrahám Papp1 · József M. Tukacs1 · László Kollár3 · László T. Mika1
Received: 23 May 2020 / Accepted: 13 July 2020
© The Author(s) 2020
Abstract
The introduction of a biomass-derived ionic liquid into the Hiyama coupling reactions, which has been considered as a
powerful tool for the synthesis of symmetrically and non-symmetrically substituted biaryl structures, could further control
or even reduce the environmental impact of this transformation. It was shown that tetrabutylphosphonium 4-ethoxyvaler-
ate, a γ-valerolactone-based ionic liquid, can be utilized as an alternative solvent to create carbon–carbon bonds between
aryl iodides and functionalized organosilanes in the presence of 1 mol% Pd under typical Hiyama conditions (130 °C, 24 h,
tetrabutylammonium fuoride activator). A comparison of diferent ionic liquids was performed, and the efects of the cata-
lyst precursor and the moisture content of the reaction mixture on the activity of the catalyst system were investigated. The
functional group tolerance was also studied, resulting in 15 cross-coupling products (3a–o) with isolated yields of 45–72%
and excellent purity (>98%).
Keywords Hiyama coupling · Ionic liquids · Homogeneous catalysis · Green chemistry
Introduction
received outstanding interest, due to their excellent chemo-
selectivity, functional group tolerance, and mild operation
conditions, which are of great importance in the synthesis
of pharmaceuticals and agrochemicals (Devendar et al.
2018; Johansson Seechurn et al. 2012; Biajoli et al. 2014;
González-Sebastián and Morales–Morales 2019). Among
these reactions, the Hiyama coupling represents an excel-
lent protocol for the synthesis of symmetrically and non-
symmetrically substituted biaryl structures via coupling of
corresponding aryl halides and organosilanes (Hatanaka and
Hiyama 1988; Sore et al. 2012; Nakao and Hiyama 2011).
The latter, as transmetalation reagents exhibit several advan-
tages over organoboranes or organostannanes, such as low
cost, low toxicity, ready availability, and high chemical sta-
bility. The protocol exhibits high regio- and stereochemistry,
as well (Horn 1995; Nakao and Hiyama 2011). The silicon
waste of the reaction can easily be incinerated to harmless
SiO2. All of these points have made the Hiyama coupling an
environmentally attractive method; however, it had received
limited attention in comparison with Heck, Sonogashira, or
Suzuki reaction, before the improved synthetic approaches
towards novel organosilane compounds renewed its impor-
tance (Denmark and Regens 2008; Denmark and Liu 2010).
Depending on the structure and/or nature of organosilanes,
The transition-metal-catalyzed cross-coupling reactions have
emerged as one of the most powerful tools for the creative
construction of both C–C and C–X (X: heteroatom) bonds,
especially in multistep synthesis of biologically active com-
pounds (Yang et al. 2017; Shi et al. 2011; Hosseinian et al.
2018; Jana et al. 2011). From the series of typically applied
d10 metals, the palladium-catalyzed transformations have
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s11696-020-01287-y) contains
supplementary material, which is available to authorized users.
* László T. Mika
laszlo.t.mika@mail.bme.hu
1
Department of Chemical and Environmental Process
Engineering, Budapest University of Technology
and Economics, Műegyetem rkp. 3, Budapest 1111, Hungary
2
Institute of Isotopes, Konkoly-Thege Miklós str. 29-33,
Budapest 1121, Hungary
3
Department of Inorganic Chemistry, University of Pécs
and János Szentágothai Research Center and MTA-PTE
Research Group for Selective Chemical Synthesis, Ifúság
u. 6, Pécs 7624, Hungary
Vol.:(0123456789)
1 3

Chemical Papers
i.e., vinyl silanes (Wolf and Lerebours 2004), alkoxysilanes,
silanols (Hirabayashi et al. 1999), and silanolates (Denmark
et al. 2008), a huge variety of application scope can be drawn
including representation of a key step in the total synthesis
of complex structures, for example, the total synthesis of
(+)–brasilenyne (Denmark and Yang 2004) and of (+)-papu-
lacandin D (Denmark et al. 2007).
Experimental
Materials and equipment
The sources of chemicals are listed in the Supplementary
Material. The γ-valerolactone-based ionic liquids were
prepared by a published method with details presented in
Supplementary Material.
Despite these advantages, the Hiyama couplings are usu-
ally performed in common organic solvents, which usually
have high toxicity, fammability, and vapor pressure even at
low temperatures resulting in serious environmental con-
cerns. As reported by U.S. FDA guidelines (CDER 2017),
the commonly used solvents for the Hiyama reactions such
as tetrahydrofuran (Miller and Montgomery 2014; Cheng
et al. 2013), dioxane (Zhang et al. 2014), N,N-dimethylfor-
mamide (Handy et al. 2005), toluene (Denmark et al. 2008),
and 1,2-dichloroethane (Ramgren and Garg 2014) are classi-
fed into Class 1 and 2, which utilizations should be avoided
or limited, respectively, particularly in the pharmaceutical
industry. To eliminate these hazardous auxiliary materials,
the reactions have been demonstrated in alternative media,
e.g., water (Sakon et al. 2017; Inés et al. 2011; Wolf and
Lerebours 2004) or glycerol (Marset et al. 2018). Although,
numerous Pd-catalyzed coupling reactions such as Suzuki,
Sonogashira, Heck, and Stille were demonstrated in ionic
liquids (ILs) (Li et al. 2018; Prechtl et al. 2010; Hallett and
Welton 2011), which have been utilized as versatile and eas-
ily tunable alternative reaction media, and only a few studies
were published on the Hiyama reaction (Mandal et al. 2019).
First, Slattery and co-workers demonstrated the applicabil-
ity of 1-pentyl-1-methylpyrrolidinium bis(trifuoromethyl-
sulfonyl)imide ([C5MPyrr][Tf2N]) as a reaction media for
allyl–aryl coupling under mild conditions (Bäuerlein et al.
2009). Jain developed a phosphane-free protocol for the
manufacture of functionalized biaryls with good to excellent
yields in 3-(3-cyanopropyl)-1-methyl-1H-imidazol-3-ium
hexafuorophosphate ([CN-bmim][PF6]) by the use of in situ
generated Pd nanoparticles (Premi and Jain 2013). The efect
of the ILs on the stabilization of Pd nanoparticles was also
shown. However, acceptable isolated yields were achieved in
the presence of a common co-solvent (Planellas et al. 2014).
Although Hiyama coupling is a well-known transforma-
tion, according to the best of our knowledge, it has not been
carried out in biomass-originated ILs, which could addi-
tionally act as a ligand. Therefore, by the introduction of
a biomass-based solvent into this synthetically important
reaction, the environmental impacts of a Hiyama reaction
involved synthesis could be further controlled and reduced.
Herein, we report a study on the palladium-catalyzed
Hiyama coupling reactions to synthesize various biaryl
structures in biomass-originated γ-valerolactone-based
ionic liquid tetrabutylphosphonium 4-ethoxyvalerate ([TBP]
[4EtOV]) extending its utilization for catalysis.
The NMR spectra were recorded on a Brucker Avance
250 MHz spectrometer. Water contents of the ionic liquids
were determined by Karl Fischer titration performed by
HANNA Instruments 904. GC analyses were performed
on an Agilent 6890 N instrument with HP-Innowax capil-
lary column (15 m × 0.25 μm × 0.25 μm) using H2 as a
carrier gas.
General procedure for Hiyama coupling reactions
In a 4 mL screw-cap vial, 0.5 mmol of the corresponding
iodoarene compounds, 1.5 eq of the corresponding silane,
1.5 eq of tetrabutylammonium fuoride (TBAF), 0.01 eq
PdCl2(PPh3)2, and 0.8 mL of tetrabutylphosphonium 4-eth-
oxyvalerate ([TBP][4EtOV]) ionic liquid were mixed and
stirred at 130 °C for 24 h. After cooling, the mixture was
partitioned between 5 mL of 1 M HCl and 5 mL of pen-
tane. The aqueous phase was extracted subsequently with
3 × 5 mL of pentane. The combined organic phase was
washed with brine, dried over MgSO4, and fltered, and
the solvent was evaporated under reduced pressure (ca.
1.333 kPa). The residue was purifed by chromatography
on silica gel (Merck Silicagel 60 (0.063−0.200 mm) for
column chromatography (70−230 mesh ASTM)) eluted
with n-pentane:EtOAc. The detailed experimental proce-
dure, as well as the characterization of isolated compounds
are provided in the Supporting Information.
Preparation and characterization of isolated
compounds
Preparation and characterization of earlier published com-
pounds (3a–k and 3 m–o) are presented in Supporting
Information.
1-Phenyl-2-chloro-4-(trifuoromethyl)benzene (3 l) was
prepared according to general procedure using 0.5 mmol
2-chloro-1-iodo-4-(trifuoromethyl)benzene, 0.75 mmol
triethoxyphenylsilane, 0.75 mmol [N(C4H9)4][F]. Iso-
1
lated yield: 50%. H NMR (250 MHz, CDCl3): δ (ppm)
7.42–7.51 (m, 5H), 7.51–7.54 (m, 1H), 7.56–7.65 (m, 1H),
7.76–7.83 (m, 1H). 13C NMR (62.9 MHz, CDCl3) 123.8
(q, J=272 Hz), 124.1 (q, J=3.8 Hz), 127.4 (q, J=3.8 Hz),
1 3

Chemical Papers
Table 1 Palladium-catalyzed Hiyama coupling reactions of iodoben-
zene (1a) and triethoxyphenylsilane (2a)
128.7, 128.8, 129.6, 131.3 (q, J = 33.4 Hz), 132.2, 133.6,
138.5. HRMS [M + H]+ Calculated: 257.0345, Measured:
257.0341 (0.5 ppm).
Entry
Ionic liquids
Isolated
yield
(%)
Results and discussion
1
2
3
4
5
6
[BMIM][PF6]
[BMIM][BF4]
[BMIM][OctS]
[TEA][4HV]
[TBA][4HV]
[TBP][4EtOV]
< 5
< 1
< 1
10
8
58
The applications of ionic liquids into the synthesis protocols
have become into the focus of interest due to their versatil-
ity and tunability. However, it was shown that the number
of chemical steps could be over 20 or even 30, reducing
their impact towards green chemistry (Jessop 2011). Using
a biomass-originated building block for the synthesis of an
IL, this number could be signifcantly reduced. It was shown
that valerate-based ionic liquids could easily be synthesized
from γ-valerolactone (Fegyverneki et al. 2010; Orha et al.
2018), which can be obtained by a two-step synthesis via
valorization of lignocellulosic biomass wastes (Tukacs et al.
2014 and 2017).
Reaction conditions: solvent 0.5 mL, 0.5 mmol iodobenzene, 0.75
mmol triethoxyphenylsilane, 1 mol% Pd(OAc)2, 1.5 eq TBAF, T =
130 °C, t = 24 h
The residual moisture content could dramatically afect
a transition-metal-catalyzed reaction. In this case, however,
the fuoride activator ([N(C4H9)4][F], hereafter TBAF) con-
taining 3 eq water, the water content of the reaction mixtures
was ca 10 m/m%. It exceeds the typical residual water con-
tent of GVL-based ionic liquids (Strádi et al. 2015, Orha
et al. 2018). Consequently, that, the protocol is hardly sen-
sitive to water up to 10%, can be assumed and no special
handling of the reaction regarding the exclusion of air and
moisture is necessary.
To demonstrate their further applicability, they were frst
compared to the conventional 1-butyl-3-methylimidazolium
cation-based ILs in the coupling of iodobenzene (1a) and
triethoxyphenylsilane (2a) as a model reaction (Scheme 1)
under typically used “Hiyama conditions” using tetrabuty-
lammonium fuoride as a F− source (Ismalaj et al. 2014).
As with Sonogashira coupling in ILs (Orha et al. 2019),
negligible conversion rates of 1a were detected in butyl-
methylimidazolium cation containing ILs (Table 1 entries
1–3). The reaction efciency could be signifcantly increased
by the introduction of tetrabutylphosphonium 4-ethoxyvaler-
ate [TBP][4EtOV], resulting in the conversion of 1a. The
product biphenyl (3a) was isolated with a yield of 58%
(Table 1, entry 6), which could be assumed to be higher by
subsequent optimization of the reaction parameters.
The selection of a palladium source could have a sig-
nificant effect on the efficiency of a catalytic transfor-
mation (Błaszczyk et al. 2009). When different pre-
cursors were compared, it was revealed that using
of bis(triphenylphosphine)palladium(II) dichloride
(Pd(PPh3)2Cl2) and tris(dibenzylideneacetone)dipalla-
dium(0) (Pd2(dba)3) gave acceptable yields of 3a (Table 2,
entries 1 and 5). A similar observation was reported for the
Sonogashira reaction performed in biomass-originated ILs
(Orha et al. 2019).
Generally, the organosilane activation with fuoride ion,
that is, the formation of the pentavalent silicon center, is
considered as a key step. In this way, a facile bond breaking
of the carbon–silicon bond during transmetalation is favored.
It was demonstrated that alkali metal salt such as NaF or
CsF could also act as silane activators for Hiyama coupling
reactions (Gurung et al. 2013; Monguchi et al. 2012). In
addition, both ammonium- and phosphonium-based ionic
liquid have been proved to be good extractants of Pd sug-
gesting their complexing ability (Katsuta et al. 2011; Regel-
Rosocka et al. 2015). Because of high water tolerance of
Table 2 Palladium-catalyzed Hiyama coupling reactions of iodoaro-
matic compounds with triethoxyphenylsilane
Entry
Catalyst precursor
Isolated
yield
(%)
1
2
3
4
5
Pd(PPh3)2Cl2
Pd(OAc)2
Pd(cod)Cl2
Pd(dba)2
70
58
45
64
76
Pd2(dba)3
Reaction conditions: [TBP][4EtOV] solvent 0.5 mL, 0.5 mmol iodo-
benzene, 0.75 mmol triethoxyphenylsilane, 1 mol% catalyst, 1.5 eq
TBAF, T = 130 °C, t = 24 h
Scheme 1 Palladium-catalyzed Hiyama cross-coupling of iodoben-
zene (1a) and triethoxyphenylsilane (2a) in ionic liquid. F− source:
TBAF
dba benzylideneacetone, cod: 1,5-cyclooctadiene, OAc acetate
1 3

Chemical Papers
Table 3 Palladium-catalyzed Hiyama coupling reactions of iodoaro-
the catalytic reactions, we attempt to convert 1a and 2 to 3
by the use of cheaper NaF in the presence of the diferent
amount of water. However, no conversion was detected up to
20 wt% water. When 30 wt% of water loading was applied,
moderate (39%) conversion of 1a to 3a was detected in the
presence of 2 eqv NaF, even higher activator concentration
at 130 °C for 24 h. To conclude, the fuoride activator cannot
be eliminated from the system.
matic compounds with triethoxyphenylsilanea
R
R
Pd(PPh3)2Cl2
[TBA][4EtOV]
+
Si(OEt)3
I
TBAF
1a-o
2a
3a-o
Iodoaromatic
compounds
Product
Yield
(%)b
70
#
1
2
1a
1b
3a
3b
I
Hereafter, to facilitate C–C bond coupling involving sev-
eral iodoaromatic substances (1a–o) and triethoxyphenyl-
silane (2), bis(triphenylphosphine)palladium(II) dichloride
was selected as a catalyst precursor by the use of 1.5 eq
TBAF in the absence of any additional ligands and auxil-
iary base in [TBP][4EtOV] at 130 °C for 24 h (Table 3).
It was demonstrated that the catalytic system generally
could be utilized for the conversion of various iodoaromatic
compounds. The substrate reactivity was not afected by
the electronic parameters of the aromatic substrates. Thus,
no Hammet-sigma (σp) correlation can be established for
para-substituted species. Both electron-donating groups,
i.e., methyl, tert-butyl, methoxy (Table 3 entries 2–6), and
electron-withdrawing groups, i.e., chloro, fuoro or trifuo-
romethoxy (Table 2, entries 7–12) were tolerated on the
aryl iodide. No signifcant diferences of the isolated yields
were observed. Under identical conditions, iodopyridine
derivatives and 2-iodothiophene were easily converted to
the corresponding biphenyls (3 m–o). The conversion of
4-chloro-1-iodobenzene did not lead to the formation of
1,4-diphenylbenzene.
64
I
CH3
3
4
72
69
1c
3c
H3C
I
1d
3d
I
H3C
5
6
7
8
55
63
45
48
1e
1f
3e
3f
tBu
H3CO
Ph
I
I
1g
1h
3g
3h
I
Cl
I
9
61
68
58
1i
1j
3i
3j
F3CO
I
10
11
F
I
O
1k
3k
I
Ph
12
1l
3l
50
F3C
I
Cl
I
The GVL-based [TBP][4EtOV] ionic liquid has been
proven as an excellent reaction media for transition-metal-
catalyzed C–N (Ullmann type) (Orha et al. 2018) and C–C
(Sonogashira) (Orha et al. 2019) coupling reactions previ-
ously. In the present work, we demonstrated that its utiliza-
tion can be extended for Hiyama coupling, as well, which
makes it an attractive biomass-based, environmentally
friendly alternative for common, fossil-based solvents, and
opens the possibility for its application in wider range of
chemical transformations.
13
14
1m
1n
3m
3n
55
55
N
I
N
NH2
I
S
15
1o
3o
66
aReaction conditions: 0.5 mL [TBP][4EtOV], 0.5 mmol iodoaromatic
compounds, 0.75 mmol triethoxyphenylsilane, 1.5 eq TBAF, T = 130
°C, t = 24 h
bIsolated yield
Acknowledgements Open access funding provided by Budapest
University of Technology and Economics. This work was funded by
National Research, Development and Innovation Ofce under projects
KH 129508 as well as Higher Education Excellence Program of the
Ministry of Human Capacities in the frame of Biotechnology research
area of Budapest University of Technology and Economics (BME
FIKP-BIO).
Conclusions
In conclusion, we have shown that tetrabutylphosphonium
4-ethoxyvalerate [TBP][4EtOV], a γ-valerolactone-based
partially biomass-derived ionic liquid, can be applied as an
alternative, safer reaction media for palladium-catalyzed
Hiyama-type carbon–carbon bond-forming reactions of
iodoaromatic compounds with triethoxyphenylsilane. A
variety of biphenyl derivatives (3b–l) and aromatic heterocy-
cles (3 m–o) were obtained with 45–72% yield. The protocol
that can be performed under air showed excellent tolerance
to the moisture content of the reaction mixture.
Compliance with ethical standards
Conflict of interest On behalf of all authors, the corresponding author
states that there is no confict of interest.
1 3

Chemical Papers
Hallett JP, Welton T (2011) Room-temperature ionic liquids: solvents
for synthesis and catalysis. 2. Chem Rev 111:3508–3576. https://
doi.org/10.1021/cr1003248
Open Access This article is licensed under a Creative Commons Attri-
bution 4.0 International License, which permits use, sharing, adapta-
tion, distribution and reproduction in any medium or format, as long
as you give appropriate credit to the original author(s) and the source,
provide a link to the Creative Commons licence, and indicate if changes
were made. The images or other third party material in this article are
included in the article’s Creative Commons licence, unless indicated
otherwise in a credit line to the material. If material is not included in
the article’s Creative Commons licence and your intended use is not
permitted by statutory regulation or exceeds the permitted use, you will
need to obtain permission directly from the copyright holder. To view a
copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Handy CJ, Manoso AS, McElroy WT et al (2005) Recent advances
in siloxane-based aryl–aryl coupling reactions: focus on heter-
oaromatic systems. Tetrahedron 61:12201–12225. https://doi.
org/10.1016/j.tet.2005.08.057
Hatanaka Y, Hiyama T (1988) Cross-coupling of organosilanes
with organic halides mediated by a palladium catalyst and
tris(diethylamino)sulfonium difuorotrimethylsilicate. J Org Chem
53:918–920. https://doi.org/10.1021/jo00239a056
Hirabayashi K, Kawashima J, Nishihara Y et al (1999) A new trans-
formation of silanols. palladium-catalyzed cross-coupling with
organic halides in the presence of silver(I) oxide. Org Lett 1:299–
302. https://doi.org/10.1021/ol990614c
References
Horn KA (1995) Regio- and stereochemical aspects of the palladium-
catalyzed reactions of silanes. Chem Rev 95:1317–1350. https
://doi.org/10.1021/cr00037a009
Bäuerlein PS, Fairlamb IJS, Jarvis AG et al (2009) Ion-tagged π-acidic
alkene ligands promote Pd-catalysed allyl–aryl couplings in an
ionic liquid. Chem Commun 6:5734. https://doi.org/10.1039/
b906823f
Hosseinian A, Zare Fekri L, Monfared A et al (2018) Transition-
metal-catalyzed C-N cross-coupling reactions of N-unsubsti-
tuted sulfoximines: a review. J Sulfur Chem 39:674–698. https
://doi.org/10.1080/17415993.2018.1471142
Biajoli AFP, Schwalm CS, Limberger J et al (2014) Recent progress
in the use of Pd-catalyzed C-C cross-coupling reactions in the
synthesis of pharmaceutical compounds. J Braz Chem Soc. https
://doi.org/10.5935/0103-5053.20140255
Inés B, Moure MJ, SanMartin R et al (2011) “On-water” Hiyama
coupling catalyzed by CNC pincer complexes of Pd(II). Arkivoc
2011:191–199. https://doi.org/10.3998/ark.5550190.0012.315
Ismalaj E, Strappaveccia G, Ballerini E et al (2014) γ-valerolactone
as a renewable dipolar aprotic solvent deriving from biomass
degradation for the hiyama reaction. ACS Sustain Chem Eng
2:2461–2464. https://doi.org/10.1021/sc5004727
Błaszczyk I, Trzeciak AM, Ziółkowski JJ (2009) Catalytic activity of
Pd(II) complexes with triphenylphosphito ligands in the sonoga-
shira reaction in ionic liquid media. Catal Lett 133:262–266. https
://doi.org/10.1007/s10562-009-0181-y
Jana R, Pathak TP, Sigman MS (2011) Advances in transition metal
(Pd, Ni, Fe)-catalyzed cross-coupling reactions using alkyl-
organometallics as reaction partners. Chem Rev 111:1417–
1492. https://doi.org/10.1021/cr100327p
CDER F (2017) Q3C—Tables and List Guidance for Industry. 1–10
Cheng K, Hu S, Zhao B et al (2013) Palladium-catalyzed hiyama-type
cross-coupling reactions of arenesulfnates with organosilanes.
J Org Chem 78:5022–5025. https://doi.org/10.1021/jo302791q
Denmark SE, Liu JHC (2010) Silicon-based cross-coupling reactions
in the total synthesis of natural products. Angew Chem Int Ed
49:2978–2986. https://doi.org/10.1002/anie.200905657
Denmark SE, Regens CS (2008) Palladium-catalyzed cross-coupling
reactions of organosilanols and their salts: practical alternatives
to boron- and tin-based methods. Acc Chem Res 41:1486–1499.
https://doi.org/10.1021/ar800037p
Jessop PG (2011) Searching for green solvents. Green Chem
13:1391–1398. https://doi.org/10.1039/c0gc00797h
Johansson Seechurn CCC, Kitching MO, Colacot TJ, Snieckus V
(2012) Palladium-catalyzed cross-coupling: a historical contex-
tual perspective to the 2010 nobel prize. Angew Chem Int Ed
51:5062–5085. https://doi.org/10.1002/anie.201107017
Katsuta S, Yoshimoto Y, Okai M et al (2011) Selective extraction
of palladium and platinum from hydrochloric acid solutions by
trioctylammonium-based mixed ionic liquids. Ind Eng Chem
Res 50:12735–12740. https://doi.org/10.1021/ie201310v
Li J, Yang S, Wu W, Jiang H (2018) Recent advances in pd-cata-
lyzed cross-coupling reaction in ionic liquids. Eur J Org Chem
2018:1284–1306. https://doi.org/10.1002/ejoc.201701509
Mandal B, Ghosh S, Basu B (2019) Task-specifc properties and
prospects of ionic liquids in cross-coupling reactions. Top Curr
Chem. https://doi.org/10.1007/s41061-019-0255-2
Denmark SE, Yang SM (2004) Total synthesis of (+)-brasilenyne.
Application of an intramolecular silicon-assisted cross-cou-
pling reaction. J Am Chem Soc 126:12432–12440. https://doi.
org/10.1021/ja0466863
Denmark SE, Regens CS, Kobayashi T (2007) Total synthesis of
papulacandin D. J Am Chem Soc 129:2774–2776. https://doi.
org/10.1021/ja070071z
Denmark SE, Baird JD, Regens CS (2008) Palladium-catalyzed cross-
coupling of fve-membered heterocyclic silanolates. J Org Chem
73:1440–1455. https://doi.org/10.1021/jo7023784
Marset X, De Gea S, Guillena G, Ramón DJ (2018) NCN–pincer–Pd
complex as catalyst for the hiyama reaction in biomass-derived
solvents. ACS Sustain Chem Eng 6:5743–5748. https://doi.
org/10.1021/acssuschemeng.8b00598
Devendar P, Qu R-Y, Kang W-M et al (2018) Palladium-catalyzed
cross-coupling reactions: a powerful tool for the synthesis of
agrochemicals. J Agric Food Chem 66:8914–8934. https://doi.
org/10.1021/acs.jafc.8b03792
Miller ZD, Montgomery J (2014) Regioselective allene hydroar-
ylation via one-pot allene hydrosilylation/pd-catalyzed cross-
coupling. Org Lett 16:5486–5489. https://doi.org/10.1021/ol502
766q
Fegyverneki D, Orha L, Lang G, Horváth IT (2010) Gamma-valero-
lactone-based solvents. Tetrahedron 66:1078–1081. https://doi.
org/10.1016/j.tet.2009.11.013
Monguchi Y, Yanase T, Mori S, Sajiki H (2012) A practical protocol for
the hiyama cross-coupling reaction catalyzed by palladium on car-
bon. Synthesis 45:40–44. https://doi.org/10.1055/s-0032-1316801
Nakao Y, Hiyama T (2011) Silicon-based cross-coupling reaction: an
environmentally benign version. Chem Soc Rev 40:4893. https://
doi.org/10.1039/c1cs15122c
González-Sebastián L, Morales-Morales D (2019) Cross-coupling
reactions catalysed by palladium pincer complexes. A review
of recent advances. J Organomet Chem 893:39–51. https://doi.
org/10.1016/j.jorganchem.2019.04.021
Gurung SK, Thapa S, Vangala AS, Giri R (2013) Copper-catalyzed
Hiyama coupling of (hetero)aryltriethoxysilanes with (hetero)
aryl iodides. Org Lett 15:5378–5381. https://doi.org/10.1021/
ol402701x
Orha L, Tukacs JM, Gyarmati B et al (2018) Modular synthesis of
γ-valerolactone-based ionic liquids and their application as
alternative media for copper-catalyzed Ullmann-type coupling
1 3

Chemical Papers
reactions. ACS Sustain Chem Eng 6:5097–5104. https://doi.
org/10.1021/acssuschemeng.7b04775
reagents as nucleophiles. Chem Soc Rev 40:2761. https://doi.
org/10.1039/c0cs00125b
Orha L, Tukacs JM, Kollár L, Mika LT (2019) Palladium-catalyzed
sonogashira coupling reactions in γ-valerolactone-based ionic
liquids. Beilstein J Org Chem 15:2907–2913
Sore HF, Galloway WRJD, Spring DR (2012) Palladium-catalysed
cross-coupling of organosilicon reagents. Chem Soc Rev
41:1845–1866. https://doi.org/10.1039/C1CS15181A
Strádi A, Molnár M, Szakál P et al (2015) Catalytic transfer hydrogena-
tion in γ-valerolactone-based ionic liquids. RSC Adv 5:72529–
72535. https://doi.org/10.1039/C5RA08297H
Planellas M, Moglie Y, Alonso F et al (2014) Heck, sonogashira, and
hiyama reactions catalyzed by palladium nanoparticles stabilized
by tris-imidazolium salt. Eur J Org Chem 2014:3001–3008. https
://doi.org/10.1002/ejoc.201400162
Tukacs JM, Novák M, Dibó G, Mika LT (2014) An improved catalytic
system for the reduction of levulinic acid to γ-valerolactone. Catal
Sci Technol 4:2908–2912. https://doi.org/10.1039/C4CY00719K
Tukacs JM, Holló AT, Rétfalvi N et al (2017) Microwave-assisted val-
orization of biowastes to levulinic acid. ChemistrySelect 2:1375–
1380. https://doi.org/10.1002/slct.201700037
Prechtl MHG, Scholten JD, Dupont J (2010) Carbon-carbon cross
coupling reactions in ionic liquids catalysed by palladium metal
nanoparticles. Molecules 15:3441–3461. https://doi.org/10.3390/
molecules15053441
Premi C, Jain N (2013) Phosphane-free hiyama cross-coupling of
aryl and heteroaryl halides catalyzed by palladium nanoparticles
in ionic liquids. Eur J Org Chem 2013:5493–5499. https://doi.
org/10.1002/ejoc.201300307
Wolf C, Lerebours R (2004) Palladium−Phosphinous acid-catalyzed
NaOH-promoted cross-coupling reactions of arylsiloxanes with
aryl chlorides and bromides in water. Org Lett 6:1147–1150. https
://doi.org/10.1021/ol049851s
Ramgren SD, Garg NK (2014) Palladium-catalyzed acetylation of
arenes. Org Lett 16:824–827. https://doi.org/10.1021/ol403570z
Regel-Rosocka M, Rzelewska M, Baczynska M et al (2015) Removal
of palladium(ii) from aqueous chloride solutions with cyphos pho-
shonium ionic liquids as metal ion carriers for liquid-liquid extrac-
tion and transport across polymer inclusion membranes. Physico-
chem Probl Miner Process 51:621–631. https://doi.org/10.5277/
ppmp150221
Yang Y, Lan J, You J (2017) Oxidative C-H/C–H coupling reactions
between two (hetero)arenes. Chem Rev 117:8787–8863. https://
doi.org/10.1021/acs.chemrev.6b00567
Zhang P, Xu J, Gao Y et al (2014) Synthesis of diarylmethanes
through palladium-catalyzed coupling of benzylic phos-
phates with arylsilanes. Synlett 25:2928–2932. https://doi.
org/10.1055/s-0034-1379366
Sakon A, Ii R, Hamasaka G et al (2017) Detailed mechanism for hiy-
ama coupling reaction in water catalyzed by linear polystyrene-
stabilized pdo nanoparticles. Organometallics 36:1618–1622.
https://doi.org/10.1021/acs.organomet.7b00170
Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional afliations.
Shi W, Liu C, Lei A (2011) Transition-metal catalyzed oxidative cross-
coupling reactions to form C-C bonds involving organometallic
1 3