Orthogonal Nanoparticle Catalysis with Organogermanes

Article abstract of DOI:10.1002/anie.201910060

Although nanoparticles are widely used as catalysts, little is known about their potential ability to trigger privileged transformations as compared to homogeneous molecular or bulk heterogeneous catalysts. We herein demonstrate (and rationalize) that nanoparticles display orthogonal reactivity to molecular catalysts in the cross-coupling of aryl halides with aryl germanes. While the aryl germanes are unreactive in L_nPd⁰/L_nPd^II catalysis and allow selective functionalization of established coupling partners in their presence, they display superior reactivity under Pd nanoparticle conditions, outcompeting established coupling partners (such as ArBPin and ArBMIDA) and allowing air-tolerant, base-free, and orthogonal access to valuable and challenging biaryl motifs. As opposed to the notoriously unstable polyfluoroaryl- and 2-pyridylboronic acids, the corresponding germanes are highly stable and readily coupled. Our mechanistic and computational studies provide unambiguous support of nanoparticle catalysis and suggest that owing to the electron richness of aryl germanes, they preferentially react by electrophilic aromatic substitution, and in turn are preferentially activated by the more electrophilic nanoparticles.

Full text of DOI:10.1002/anie.201910060

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Accepted Article
Title: Orthogonal Nanoparticle Catalysis with Organogermaniums
Authors: Christoph Fricke, Grant Sherborne, Ignacio Funes-Ardoiz,
Erdem Senol, Sinem Guven, and Franziska Schoenebeck
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201910060
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10.1002/anie.201910060
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DOI: 10.1002/anie.201((will be filled in by the editorial staff))
Synthetic Methods
Orthogonal Nanoparticle Catalysis with Organogermaniums
Christoph Fricke,† Grant J. Sherborne,† Ignacio Funes-Ardoiz, Erdem Senol, Sinem Guven and
Franziska Schoenebeck*
Abstract: Although nanoparticles are widely used as catalysts, little is known about their potential ability to trigger privileged trans-
formations as compared to homogeneous molecular or bulk heterogeneous catalysts. We herein demonstrate (and rationalize) that
nanoparticles display orthogonal reactivity to molecular catalysts in the cross-coupling of aryl halides with aryl germanes. While
the aryl germanes are unreactive in LnPd(0)/LnPd(II) catalysis and allow selective functionalization of established coupling partners in
their presence, they display superior reactivity under Pd nanoparticle conditions, outcompeting established coupling partners (such
as e.g. ArBPin, ArBMIDA ) and allowing air-tolerant, base-free and orthogonal access to valuable and challenging biaryl motifs. As
opposed to the notoriously unstable polyfluoroaryl and 2-pyridyl boronic acids, the corresponding germanes are highly stable and
readily coupled. Our mechanistic and computational studies provide unambiguous support of nanoparticle catalysis and suggest that
owing to the electron-richness of aryl germanes, they preferentially react via electrophilic-aromatic substitution, and in turn are
preferentially activated by the more electrophilic nanoparticles.
Introduction: Over the past decade the nanotechnology in-
dustry has surged forward to reach a global market of greater
than one trillion US $ in 2018,1 with diverse applications rang-
ing from materials for solar cells, photonics, cosmetics or bio-
medical applications, such as drug delivery, tissue engineering
and cancer therapy to catalysis.2,3,4 While nanoparticle catalysts
are generally more reactive than their bulk metal counterparts
due to their greater surface area, they frequently need more forc-
ing reaction conditions than homogeneous molecular metal cat-
alysts to trigger the same transformations.5 However, leaching
from molecular catalysts can cause the release of nanoparticles,
and consequently their involvement as potentially ‘true’ cata-
lytic species in established catalytic transformations has also
been subject to intense debates.5,6,7 As opposed to homogeneous
molecular catalysis, lower loadings in metal are frequently re-
quired under nanoparticle catalysis conditions.2,5,8 This charac-
teristic paired with low cost of preparation and the absence of
sensitive ligands in nanoparticles, have led to immense interest
academically as well as their implementation in large scale in-
dustrial processes.9
chemists in academia and industry,12 as the established alterna-
tives can be associated with basicity, instability (organomagne-
sium and -zinc), toxicity (organotin) or lower reactivity. Despite
its relative mildness, broad scope and high reactivity, this pop-
ular coupling class is not free of challenges, however. These in-
clude, for example, the occasional instability of boronic acids,
which is particularly pronounced in the case of 2-pyridyl and
multifluoroaryl boronic acids and further aggravated by the
presence of (and need for) base.13 Ingenious masking strate-
gies14,15 or elegantly more reactive systems that make use of aryl
diazonium salts as acceptors16 have been developed to balance
the relative kinetics of deactivation versus productive cross-
coupling in these cases.17 Some toxicity concerns in conjunction
with organoboron compounds and their derivatives have re-
cently also been reported,18 which may create a need for alter-
native approaches in certain applications.
A
Homogeneous Catalysis
Nanoparticle Catalysis
However, despite the many publications on nanoparticle ca-
talysis, to date, there is no precedence of unambiguously unique
and orthogonal reactivity of nanoparticles compared to homo-
geneous molecular or heterogeneous bulk catalysts in organic
transformations. Such insights would be of utmost importance
however, as there is a high demand for innovative and orthogo-
nal synthetic strategies. Especially, a modular and straightfor-
ward access to richly-functionalized biaryl motifs is in consid-
erable demand, owing to its widespread abundance in drugs,
materials or privileged catalysts.10 In this context, a strategy that
operates in an orthogonal fashion to the widely employed Pd-
catalyzed cross coupling technology11 would offer an additional
dimension for structural diversification as well as potential to
overcome existing synthetic challenges through orthogonal syn-
thetic approaches.
Leaching?
Since the advent of metal catalyzed-cross coupling technol-
ogy more than 40 years ago, the field has grown to be ever-
increasingly enabling owing to numerous efforts to push the
frontiers of catalyst development and mechanistic understand-
ing; yet the transmetalation step to date largely still relies on the
original set of reagents.11 The Suzuki–Miyaura cross-coupling
of organoboron reagents with aryl halides is most widely and
ubiquitously used among organic, medicinal and materials
.
Base-free & robust
. Orthogonal & selective . Mechanistic rationale
Figure 1. (A) Homogeneous vs. nanoparticles catalysis and current
leaching assumptions. (B) Challenges of established transmetalation
reagents for Csp2-Csp2 couplings. (C) This work.
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10.1002/anie.201910060
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.
Mercury test
.
TEM imaging
40 nm
Pd
EDX
Ag
Pd
Ag
energy [keV]
100
Initiation phase
characteristic of
release of active
species
without
PPh3
[Pd]/L
1:1
AgBF4
AgBF4
[Pd]/L
1:3
0
0
10
20
time [h]
30
Figure 2. Mechanistic studies with aryl germanes and support of nanoparticle catalysis. (A) Aryl germanes are unreactive in homogeneous
catalysis. (B) Aryl germanes unreactive in transmetalation of Pd(II) complexes. (C) Support of nanoparticle-triggered reactivity (reactivity, imaging,
mercury test, characteristic initiation phase in reaction profile).
of the coupling process involving organogermanium com-
Results and Discussion: We aspired to widen the conceptual
coupling repertoire and focused on organogermanium com-
pounds may likely offer inspiration. In this context, we initially
probed the potential of defined homogeneous Pd(0)/Pd(II) cou-
pounds. Promisingly, no toxicity has been associated with this
pling cycles and synthesized a variety of Pd(II) complexes of the
compound class,19 and our stability tests of pentafluoroaryl ger-
nature LnPd(II)(X)(Ar), in which ‘X’ was a halide or hydroxide.
mane (ArGeEt3) indicated that as opposed to the corresponding
Upon subjection of phenyltriethylgermanium to the well-estab-
boronic acid that has a lifetime of milliseconds,13,16 the ArGeEt3
lished mono-, bis- and bidentate phosphine-coordinated Pd(II)
remains completely stable even upon subjection to acid (HCl)
complexes 2-7 at room temperature or 80°C, we saw no indica-
or base (NaOH, KF) for 2h at 90°C (see Figure 3).20 Similarly
the 2-pyridyl example proved to be fairly stable in basic condi-
tion of transmetalation taking place, regardless of the coordi-
nated halide (I, Br, F) or hydroxide, the employed solvent (THF,
tions but was sensitive to acid.
DMF, toluene) or additive (TBAF, CsF, KOH or K2CO3) (see
Figure 2B). In particular, Pd(II)-F complexes are usually privi-
leged intermediates that typically undergo direct transmeta-
lation with the established cross-coupling partners ArSiR3,
ArSnR3 or ArB(OH)2 without the need for additives.12,25 Indeed,
while the organogermane remains untouched (Figure 2), our
comparative studies showed that organoboron reagents react
with the same Pd(II)-F complex within seconds, and orga-
nosilane and organotin reagents within an hour at room temper-
ature (see supporting information, Table S1). These data clearly
reinforce that typical Pd(0)/Pd(II) reactivity modes are not readily
amenable to organogermaniums.
Interestingly, although Pd(II)-iodide complex 7 did not give
rise to any transformation of the organogermane, upon addition
of one equivalent of AgBF4 at room temperature, the cross-cou-
pled product 8 was generated in 18% yield (Figure 2C). We next
tested whether Pd(II) complex 7 in conjunction with AgBF4
could also trigger the catalytic conversion of organogermanes.
Using 2.5 mol% loading of 7 with AgBF4 indeed gave efficient
catalytic transformation of 1-iodo-4-(trifluoromethyl)benzene
with 4-fluorophenyl triethylgermane 1 to yield biaryl 8. Given
the rather labile nature of the Pd(II) complex 7 as well as the
visible metal precipitation upon AgBF4 addition, we speculated
that palladium nanoparticles might be generated under these
conditions and hence might also be involved in the coupling
process. We therefore next adopted conditions that are known
Figure 3. Test of stability of those ArGeEt3 that are highly unstable
as boronic acids. (*nBuLi was used in 2.0 -2.5 equivalents)
◦ Mechanistic tests for potential reactivity with Pd(II) & mecha-
nistic support of nanoparticle reactivity: The few reported Pd-
catalyzed cross-coupling reactions involving organogermanium
compounds ascribed relatively low reactivity to the latter as
compared to the established coupling partners, and coupling at-
tempts exclusively applied basic and relatively harsh conditions
without any detailed mechanistic interrogation.21,22,23,24 We en-
visioned that a detailed investigation of the fundamental aspects
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10.1002/anie.201910060
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Scope
Highly Challenging Couplings
Chemoselective Couplings
Figure 4. Scope of the Csp2-Csp2 cross coupling reaction, including challenging and chemoselective couplings. Conditions: Aryl germane (1.0
equiv.), aryl iodide (1.5 equiv.) in DMF (0.3 M). The reactions were run for 16 h but can be performed much shorter also (see below).
to generate nanoparticles and used Pd2dba3 along with AgBF4
(see Figure 2C).26 This resulted in efficient coupling of 1-iodo-
4-(trifluoromethyl)benzene with organogermane 1 under these
conditions, and we isolated biaryl 8 in 89% yield after 16 h at
80 °C.
◦ Exploration of synthetic potential: In light of these results,
i.e. the lack of reactivity of the organogermane with homogene-
ous Pd(II) complexes, but high reactivity under [Pd] nanoparticle
catalysis, we anticipated that there could be significant potential
towards maximizing diversity in cross-coupling and hence set
out to explore the potential of catalytic cross-coupling with or-
ganogermanes in greater detail.
Further support of nanoparticle catalysis was gained through
the following experiments and observations: (i) our analysis of
the mixture through TEM imaging revealed the presence of
spherical particles of approximate 5 nm diameter. EDX compo-
sition analysis showed the presence of both Pd and Ag in these
nanoparticles. (ii) The addition of mercury to this successful
catalytic reaction, resulted in complete inhibition; there was no
significant product formation (≤ 5%, Figure 2C). These results
are in accord with trapping and deactivation of the active nano-
particles.27 Moreover, (iii) when we monitored the formation of
4-methyl-4'-(trifluoromethyl)-1,1'-biphenyl as well as con-
sumption of starting materials over time, we observed a brief
induction period (of 90 min). This induction period was found
to significantly prolong to 27 h in the presence of added ligand
(5 mol% PPh3). These observations are common indicators that
the true active species is phosphine-free and is formed during
the initial induction phase. In this context, our further experi-
mentation revealed that the induction period and hence for-
mation of active species is independent of the aryl germane (see
supporting information for additional details).
Pleasingly, when we applied these nanoparticle conditions to
both electron-rich and electron-poor aryl iodides with a variety
of aryl germanes and stirred the mixture overnight, we obtained
excellent yields of the corresponding biaryl products (8-18, see
Figure 4). Alkyl-, ester, methoxy or fluorinated groups were
well tolerated and all electronic combinations of biaryl (i.e.
electron-rich/-rich, electron-poor/electron-rich or electron-
poor/-poor) could be prepared. Notably, the coupling was not
effected by oxygen or moisture, as the same coupling results
were obtained under inert conditions or when the reaction was
run open-flask (see 36, 37 in Figure 4).
◦ Major coupling challenges: With these successful condi-
tions in hand, we subsequently set out to couple those moieties
that are known to be tremendously challenging in the widely
employed Suzuki cross coupling, i.e. polyfluorinated arenes (27
and 28), and the medicinally and pharmaceutically relevant het-
erocycles thiophenes, furans and pyridines (19-26). The case of
pentafluorophenyl boronic acid has long been a challenge due
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10.1002/anie.201910060
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to its propensity for protodeboronation,13 typically requiring
donium salts is also effective in the absence of AgBF4. For ex-
ample, when 4-methoxyphenyl germane was reacted with di-
phenyliodonium salt in the presence of Pd2(dba)3 (2.5 mol%) in
DMF for 2 h at 80°C, 51% of biaryl product 38 was isolated. In
this context, we unambiguously verified the formation of nano-
particles under silver-free reaction conditions with diarylio-
donium salts (see SI for further information and TEM images).30
The ability to conduct these reactions silver-free suggests that
[Pd] instead of [Ag] is the key active component in the nano-
particles that allow for couplings of aryl germanes.
“designer” conditions.16
To our delight, when performing the coupling of triethyl(pen-
tafluorophenyl)germane with aryl iodides, we obtained near
quantitative yields (27, 28). Moreover, good yields were ob-
tained also for heterocyclic variants, i.e. the 2- and 3-
germylated thiophene reagents (24, 25, 26) or furan (19, 20).
Even the most challenging, 2-pyridyl germanes proved to be ro-
bust and stable and allowed for efficient cross-couplings (21-
23, 39, 40). The coupling of 2-pyridyl boronic acids has been a
long-standing challenge due to their inherent instabilities.
Burke and his team recently developed a solution through the
use of MIDA boronate derivatives,15 which require additional
protection/deprotection steps however.
◦ Exploration of C-I vs. C-Br/C-Cl chemoselectivity: Another
pertinent challenge in the cross-coupling arena is site selective
bond formation.28,29 Chemoselective coupling strategies are of
widespread interest, as they enable access to densely function-
alized biaryl motifs and rapid creation of diversely substituted
compound libraries. For poly(pseudo)halogenated arenes typi-
cal LnPd(0)/LnPd(II) based coupling protocols generally suffer
from low predictability of favored coupling site and a pro-
nounced substrate-specificity. Utilizing Pd(I) dimers or cationic
Pd-trimers, predictable site-selective functionalizations were
recently achieved involving basic Grignard or organozinc rea-
gents.28,29 Pleasingly, our mild and base-free conditions involv-
ing organogermanes allowed for C-I selective functionalization
with multiply halogenated substrates, bearing bromide and
chloride, as well as the pseudo-halogen OTf functionalities (29-
32, Figure 4).
◦ Exploration of practicability: With the exquisite synthetic
potential of nanoparticle-catalyzed couplings of aryl germanes
showcased, we next assessed practical and sustainability fea-
tures of the reaction for its wider applicability. While 2.5 mol%
of Pd source was employed in the above experiments, our tests
indicated that the transformation also proceeds under signifi-
cantly lower loading of [Pd] and is scalable: using 0.1 mol% of
Pd2(dba)3, biaryl product 9 was efficiently prepared on a scale
of ~1g and 96% yield. Aside from catalyst loading and scalabil-
ity, the reaction medium and time will also influence the wider
applications, especially in an industrial context. To this end, our
closer examination of the required reaction time revealed that
much shorter times are sufficient and alternative solvents can
be utilized. Only a small amount of DMF was found to be nec-
essary for the formation of active nanoparticle. As such, the pre-
stirring of catalytic amounts of Pd2dba3 with (potentially sacri-
ficial) iodobenzene (2.5 and 5 mol% respectively), AgBF4 (1.5
equiv.) with little DMF (2.5 equiv.) for 40 min at 80°C was
found to be sufficient and then allowed for rapid couplings of
aryl germane with aryl iodide within 1 h in dioxane in good
yields (43-48).
Figure 5. Scope of the Csp2-Csp2 cross coupling with iodonium rea-
gents and/or under pre-formed nanoparticle conditions.
◦ Aryl germanes truly privileged with nanoparticles? With the
synthetic potential of the nanoparticle-catalyzed couplings of
aryl germanes with aryl iodides or hypervalent iodine reagents
established, we next assessed whether the aryl germanes are
truly privileged in these transformations. To this end, we sub-
jected the established transmetalation agents, i.e. para-fluoro-
aryl boronic acid, boronic ester to the nanoparticle-catalysis
conditions and attempted to couple 1-iodo-4-(trifluorome-
thyl)benzene (see Figure 6A, right). While the corresponding
ArGeEt3 delivered the coupling product 8 in 57% yield after 30
min, the other transmetaling agents failed to deliver the cou-
pling in appreciable amounts and yielded 8 in only 2-8% yield.
As such, there is a profound selectivity reversal from tradi-
tional molecular Pd(0)/Pd(II) versus [Pd] nanoparticle conditions.
While the aryl germane proved to be the least reactive ( = unre-
active) under classical molecular LnPd(0)/LnPd(II) cross coupling
conditions as compared to the established cross coupling part-
ner (Figure 6A), it becomes the most reactive under nanoparti-
cle conditions. Consequently, selective couplings also should
◦ Tests of silver-free reactivity and hypervalent iodine rea-
gents: Our mechanistic data indicated that the silver’s primary
role appears to be an iodide scavenger. As such, we envisioned
that hypervalent iodine compounds may also be effective in the
coupling of organogermanium compounds, as they are inher-
ently more activated. Indeed, we found that diaryliodonium
salts function as complementary electrophiles, even for the ex-
ceptionally challenging 2-pyridyl substrates (38-42, Figure 5).
Both the BF4 and PF6 iodonium salts were shown to be effec-
tive. Notably, the coupling of organogermanes with diarylio-
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(A) Pd(0) / Pd(II) Catalysis
Pd Nanoparticle Catalysis
(B)
.
Pd(0) / Pd(II) Catalysis
.
Pd Nanoparticle Catalysis
One-Pot
Intermolecular
Competition
Figure 6. (A) Performance of ArGeEt3 versus established coupling agents in coupling with PhI under Pd(0)/Pd(II) catalysis (left) and nanoparticle
catalysis (right). (B) Intermolecular competitions in the coupling of PhI with ArGeEt3 versus ArB(Pin) or ArB(MIDA) under Pd(0)/Pd(II) molecular
catalysis (left) and nanoparticle catalysis (right). Reaction time in each case: 30 min.
have potential. Indeed, the intramolecular competition of
silane- and Bpin-substituted aryl germanes in the coupling with
4-iodophenylboronic acid pinacol ester gave exclusive coupling
at the C-Ge site (33-35, see Figure 4). Moreoever, the intermo-
lecular competition between ArGeEt3 versus ArB(Pin) or
ArB(MIDA) in the coupling with iodobenzene also showed or-
thogonal selectivities (Figure 6B), offering therefore an orthog-
onal tool for selective Csp2-Csp2 coupling reactions and an addi-
tional mode to increase diversity.
In the experimentally observed initiation phase involving Pd,
silver and the aryl iodide, a palladium cluster is likely formed
and stabilized through oxidative saturation of aryl iodide. Our
computational data suggest that addition of two molecules of
PhI to the Pd-cluster is highly exergonic and favored over coor-
dination of an aryl germane. The saturated Pd3 intermediate is
likely activated by Ag+, forming a cationic cluster (Int1) and
releasing AgI. Alternatively, Int1 is formed directly with dia-
ryliodonium salts (in the absence of silver salts). Subsequent
coordination of aryl germane to Int1 is now energetically fa-
vored over ArI. The key C-Ge bond activation then takes place
from Int2, which was found to proceed in an electrophilic aro-
matic substitution-type mechanism (SEAr) via TS3. The activa-
tion free energy barrier for the C-Ge bond cleavage is 24.6
kcal/mol and as such significantly lower than the SEAr-type
transmetalation at a Pd(II) complex.[33] From Int3 the release of
[GeMe3]+ and formation of biaryl is very facile.
◦ Computational study on the origins of reactivity: To gain
insight on the origins of orthogonality, we undertook computa-
tional studies using B3LYP-D3/Def2TZVPP// B3LYP-
D3/Def2SVP level of theory.31 We initially investigated why
organogermanes are not reactive in the transmetalation of de-
fined LnPd(II) complexes. Interestingly, we found that the gener-
ally assumed concerted 4-centered transmetalation of PhGeMe3
with [(PPh3)Pd(II)(X)(Ph)] with X = F or I is significantly disfa-
vored (ΔG‡ > 40 kcal/mol, Figure 7A), which appears to be due
to a lack of driving force to form a [Ge]-halogen bond. Our
search for alternative modes of activation revealed that electro-
philic aromatic substitution (SEAr) constitutes a lower energy
pathway for transmetalation at Pd(II) (see TS2, Figure 7A),
which is characterized by an activation free energy of ΔG‡ =
35.8 kcal mol-1 for X = I. While this barrier is still rather high,
these results indicate that organogermanes appear to be more
prone to react as nucleophiles and hence should prefer more
electrophilic and electron-deficient metal species than ligand-
coordinated Pd(II) complexes.
Importantly, although we considered a trimer as model for na-
noparticles, our computational data suggest that these reactivity
trends also hold for larger Pd-clusters. As such, the computa-
tional studies suggest that the bond activation under nanoparti-
cle catalysis is reminiscent of an electrophilic aromatic substi-
tution. Owing to its electron-richness the aryl germane is a priv-
ileged reaction partner with electron-deficient Pd species,
which is the origin of its superior reactivity with electrophilic
Pd nanoparticles and the lack of reaction under LnPd(0)/LnPd(II)
catalysis.
We next set out to study the molecular events under nanopar-
ticle catalysis. Building on previous studies on the likely speci-
ation of nanoparticles,32 we adopted a phosphine-free Pd trimer
as representative model for the active nanoparticle. We studied
the likely full catalytic cycle and investigated numerous possi-
bilities, of which the favored pathway is featured in Figure 7B.
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10.1002/anie.201910060
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Acknowledgements
We gratefully acknowledge RWTH Aachen University and the Eu-
ropean Research Council (ERC-637993) for financial support.
I.F.A. acknowledges the Alexander von Humboldt Foundation for
a fellowship.
Conflict of interest
The authors declare no conflict of interests.
Author Information
C. Fricke, G. J. Sherborne, I. Funes-Ardoiz, E. Senol, S. Guven,
Prof. Dr. F. Schoenebeck
Saturation
Institute of Organic Chemistry, RWTH Aachen University,
Landoltweg 1, 52074 Aachen (Germany).
E-mail: franziska.schoenebeck@rwth-aachen.de
Homepage: http://www.schoenebeck.oc.rwth-aachen.de
Author Contributions
†C.F. and G.J.S. contributed equally.
Received: ((will be filled in by the editorial staff))
Published online on ((will be filled in by the editorial staff))
Keywords: chemoselectivity • catalysis • DFT • germanium
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Figure 7. Computational study of nanoparticle catalyzed cross cou-
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germanes, including those involving 2-pyridyl or polyfluoro-
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germanes are the least reactive functionality under Pd(0)/Pd(II)
homogeneous molecular catalysis as compared to established
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This article is protected by copyright. All rights reserved.

10.1002/anie.201910060
Angewandte Chemie International Edition
Lennox, G. C. Lloyd‐Jones, Angew. Chem. Int. Ed. 2013, 52, 7362-
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evant homogeneous organometallic catalysis involving Ni, Pd, Ir,
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[20] The aryl germane can readily be made via reaction of aryl Grignard
with Et3GeCl (which is available at relatively low cost, i.e. 54€ (60
$)/gram).
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[33] We calculated the elementary step from INT2 to INT3 in the absence
and in the presence of BF4 (i.e. as an ion pair overall). This resulted
in no marked difference; the activation free energy barriers are es-
sentially the same (ΔΔG‡= 25.7 kcal/mol). Please see SI for further
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[23] J.-P. Pitteloud, Z.-T. Zhang, Y. Liang, L. Cabrera, S. F. Wnuk, J.
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10.1002/anie.201910060
Angewandte Chemie International Edition
Synthetic Methods
C. Fricke,† G. J. Sherborne,† I. Funes-Ar-
doiz, E. Senol, S. Guven and F.
Schoenebeck*
.
Base-free & robust
. Orthogonal & selective
. Mechanistic rationale
Page – Page
Orthogonal Nanoparticle Catalysis
with Organogermaniums
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“
a
a
a
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a
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8
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