MOF-derived cobalt nanoparticles catalyze a general synthesis of amines

Article abstract of DOI:10.1126/science.aan6245

The development of base metal catalysts for the synthesis of pharmaceutically relevant compounds remains an important goal of chemical research. Here, we report that cobalt nanoparticles encapsulated by a graphitic shell are broadly effective reductive amination catalysts. Their convenient and practical preparation entailed template assembly of cobaltdiamine- dicarboxylic acid metal organic frameworks on carbon and subsequent pyrolysis under inert atmosphere.The resulting stable and reusable catalysts were active for synthesis of primary, secondary, tertiary, and N-methylamines (more than 140 examples).The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, or nitro compounds, and molecular hydrogen under industrially viable and scalable conditions, offering cost-effective access to numerous amines, amino acid derivatives, and more complex drug targets.

Full text of DOI:10.1126/science.aan6245

RESEARCH ARTICLES
Cite as: R. V. Jagadeesh et al.,
Science 10.1126/science.aan6245 (2017).
MOF-derived cobalt nanoparticles catalyze a general
synthesis of amines
Rajenahally V. Jagadeesh,1* Kathiravan Murugesan,1* Ahmad S. Alshammari,2 Helfried Neumann,1 Marga-Martina Pohl,1 Jörg Radnik,1
Matthias Beller1†
1Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Strasse 29a, Rostock, D-18059, Germany. 2King Abdulaziz City for Science and Technology,
Post Office Box 6086, Riyadh 11442, Saudi Arabia.
*These authors contributed equally to this work.
†Corresponding author. Email: matthias.beller@catalysis.de
The development of base metal catalysts for the synthesis of pharmaceutically relevant compounds
remains an important goal of chemical research. Here, we report that cobalt nanoparticles encapsulated
by a graphitic shell are broadly effective reductive amination catalysts. Their convenient and practical
preparation entailed template assembly of cobalt-diamine-dicarboxylic acid metal organic frameworks on
carbon and subsequent pyrolysis under inert atmosphere. The resulting stable and reusable catalysts
were active for synthesis of primary, secondary, tertiary and N-methylamines (>140 examples). The
reaction couples easily accessible carbonyl compounds (aldehydes, ketones) with ammonia, amines or
nitro compounds and molecular hydrogen under industrially viable and scalable conditions, offering cost-
effective access to numerous amines, amino acid derivatives, and more complex drug targets.
The development of nanostructured catalysts for innovative organic linkers (15–17). Recently, they have been used as self-
organic synthesis is crucial for the advancement of sustaina- sacrificing compounds for producing bulk materials by their
ble processes in the chemical, pharmaceutical and agrochem- direct pyrolysis without the use of external heterogeneous
ical industries (1–8). However, most of the nanocatalysts supports (18–23). Here, we describe the use of MOFs as spe-
known to date were developed for the activation of structur- cific precursors for producing highly active and stable cobalt
ally simple molecules (3–8) and are scarcely applied for more nanoparticles supported on commercial carbon. In contrast
challenging synthetic reactions or refinement of structurally to previous works (18–23), the pre-formed material (cobalt-
complex compounds. Among the different classes of nano- diamine-dicarboxylic acid MOF) acted as a structure direct-
materials, supported metal particles are particularly valued ing template for pyrolysis on carbon. Compared to more con-
for their low energy consumption and high activities and se- ventional routes to heterogeneous materials prepared by
lectivities (1–14), which can be tuned by controlling the na- impregnation or immobilization, in our procedure the pyrol-
ture, size, distribution and stability of the nanoparticles as ysis precursor is better defined. We applied the resulting na-
well as surface composition of the support (9–14). In general, noparticles to reductive amination of carbonyl compounds
simple supported metal nanoparticles are prepared by ther- for the general synthesis of amines.
mal (via pyrolysis or calcination) or chemical reduction of the
Amines represent a privileged class of compounds used
respective metal salts on heterogeneous supports (1–10). To extensively in fine and bulk chemicals, pharmaceuticals and
improve the activity of these simple materials, well-defined materials (24–29). In fact, 170 of the top 200 drugs of 2015
organometallic complexes have also recently been explored contained nitrogen and/or amino groups (26). Catalytic re-
as precursors for pyrolytic activation (13, 14). Although the ductive amination of carbonyl compounds with molecular hy-
resulting materials found application in catalytic hydrogena- drogen is widely performed in research laboratories and
tions and oxidations (13, 14), they largely exhibit poor reac- industrial facilities (30–48). However, the preparation of pri-
tivity and selectivity for other challenging synthetic organic mary amines using ammonia relies on either precious metal-
reactions. One key to more rational preparation of active na- based catalysts (30, 31, 33–39) or Raney nickel (30, 31, 40),
noparticulate catalysts might be the use of structure-control- which often remains non-selective or otherwise problematic
ling templates, which should strongly bind to the respective (30, 31, 34–40). Hence, the development of more selective and
metal ions. In this respect, metal organic frameworks (MOFs) earth-abundant metal-based catalysts continues to attract
represent a stable class of porous compounds, which can be scientific interest.
assembled in a highly modular manner from metal ions and
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Preparation of MOF-derived cobalt
nanoparticle-based catalysts
tion of some graphitic layers and short-range ordered gra-
phitic shells (Fig. 2A, middle). In addition, a smaller quantity
We initially explored MOFs assembled in dimethylformamide of core-shell particles with cobalt oxide shells at metallic Co
(DMF) at 150°C from iron, manganese, cobalt, nickel or cop- is also present (fig. S2A). In regions of short-range ordered
per nitrates and organic linkers 1,4-diazabicyclo[2.2.2]octane carbon, we detected single Co atoms as bright dots in high
(DABCO) and terephthalic acid (TPA). Next, these in situ gen- angle annular dark field (HAADF) images (Fig. 2A, right). To
erated MOFs were immobilized on commercial Vulcan XC get information on the cobalt/carbon/nitrogen relation the
72R carbon powder. Upon slow evaporation of the solvent fol- parallel mapping of EDXS for all elements and electron en-
lowed by drying of the resulting MOFs, the template on car- ergy loss spectroscopy (EELS) (Fig. 2B) optimized for carbon,
bon was formed (Fig. 1). Subsequent pyrolysis at 800°C for 2h nitrogen and oxygen was performed. Because the nitrogen
under argon atmosphere produced the final nanoparticles. In signal is superimposed on the carbon signal in EDXS, these
addition, the Co-DABCO-TPA MOF was separately prepared maps were only used for the Co distribution. Figure 2B shows
and isolated prior to pyrolysis on carbon (see supplementary the maps of C, N and Co (left image) in the neighborhood of
material S2.2 for detailed preparation). Hereafter, all these a metallic particle wrapped by graphitic carbon. The C/N
materials are labeled as M-L1-L2@C-x, where M = Fe, Mn, Co, overlay in the HAADF image (middle image) gives evidence
Ni, Cu; L1 = DABCO; and L2 = TPA and x denotes the pyrol- that nitrogen is not only located in the graphitic shell on the
ysis temperature, respectively.
Co particle but surprisingly in short range ordered carbon
All of these materials were tested in the benchmark re- which is not part of the graphitic shell and corresponds to
ductive amination of 3,4-dimethoxybenzaldehyde using am- features with single atoms shown in Fig. 2A. Co traces are
monia and hydrogen to give veratrylamine (3,4- detectable everywhere in the nitrogen containing carbon at
dimethoxybenzylamine), which is present as a structural mo- low concentration. In contrast, the less active material Co-
tif in several bioactive molecules. As shown in fig. S1, materi- DABCO@C-800 contained mainly hollow cobalt oxide
als resulting from pyrolysis of Fe-, Mn-, Cu- and Ni-DABCO- (Co3O4) particles (fig.S2B). In addition to Co3O4, some Co-
TPA@C at 800°C showed no or only little catalytic activity. Co3O4 core-shell particles were also present. Although sub-
Gratifyingly, the corresponding cobalt catalyst (Co-DABCO- nm Co structures are found in this material, no single Co at-
TPA@C-800) from Co-MOFs gave a very good yield (88%) of oms were detected. Similarly, Co-TPA@C-800 (fig. S2C) also
the desired amine. The pyrolyzed materials prepared from contained mainly cobalt oxide (Co3O4) particles encapsulated
the in situ generated and the isolated Co-MOFs exhibited within graphitic shells along with a small quantity of metallic
similar activity. Pyrolysis of cobalt nitrate with either DABCO cobalt in Co-Co3O4 core-shell structures. No single Co atoms
(Co-DABCO@C-800) or TPA (Co-TPA@C-800) linkers alone or sub nm Co structures were detected in this material. Co-
led to less active catalysts (15-20% yields). Apart from the balt nitrate@C-800, which was completely inactive, con-
metal and the linkers, the pyrolysis temperature was im- tained hollow Co3O4 with short-range ordered carbon from
portant for activity. Specifically, pyrolysis at 400°C gave ma- the support in the vicinity (fig. S2D).
terial with poor reactivity (16% yield), whereas pyrolysis at
In order to understand the formation mechanism of the
600°C and 1000°C resulted in active catalysts (75% and 83% active catalyst, materials pyrolyzed at lower temperatures
yields, respectively). As expected, the homogeneous catalyst were also characterized (fig. S3). In Co-DABCO-TPA@C-400,
and the pyrolyzed cobalt nitrate (Co(NO3)2@C-800) were not a minor amount of metallic cobalt was present in the core of
active. Similarly, the Co-MOFs with and without support cobalt/cobalt oxide core-shell structures, and no formation of
showed no product formation (fig. S1).
graphitic shells was observed. Co-DABCO-TPA@C-600 con-
tained more metallic cobalt, and incipient formation of gra-
phitic shells enveloping the metallic Co was evident.
Apparently, this structural process is crucial for high activity
Characterization of cobalt nanoparticle-based
catalysts
We undertook detailed structural characterization of these and stability. For the most active Co-DABCO-TPA@C-800,
cobalt-based catalysts. Aberration-corrected scanning trans- single Co atoms within some of the graphitic structures were
mission electron microscopy (STEM) analysis of the most ac- detected. In the case of Co-DABCO-TPA@C-1000, most of the
tive material (Co-DABCO-TPA@C-800) revealed the Co was present in metallic crystallite morphology completely
formation of mainly metallic cobalt particles with diameter covered by graphitic structures. In all of the active catalysts,
ranging from less than 5 nm to 30 nm (Fig. 2). The energy- cloudy regions of cobalt species in the 1-2 nm range were de-
dispersive X-ray spectroscopy map (EDXS) (Fig. 2A left) tected. The different phases of cobalt in both active and less
shows mainly the presence of metallic Co particles within the active catalysts have been also confirmed by x-ray powder dif-
carbon matrix. Most of these are surrounded by a combina- fraction data (figs. S7 and S8) that accorded with the TEM
analysis.
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The nature and quantity of nitrogen in these materials the reductive amination of aliphatic aldehydes is hampered
was further explored by x-ray photoelectron spectroscopy by unproductive aldol condensation, which can easily occur
(XPS) (fig. S10 and S11). Surprisingly, the combination of the under basic conditions. Nevertheless, several aliphatic and
two linkers increased the quantity of nitrogen in the near- araliphatic substrates gave the corresponding primary
surface region significantly compared to either linker alone amines in good yields (up to 92%) and high selectivity.
(fig. S12). The N content in Co-DABCO-TPA@C-800 was three
The hydrogenation of the in situ generated imine from al-
times higher than in Co-DABCO@C-800, whereas in Co- dehydes is faster than reduction of the corresponding ketone-
TPA@C-800 only traces of N were observed. In both Co- derived imines. Thus, a more active catalyst or more drastic
DABCO-TPA@C-800 and Co-DABCO@C-800, two N-states conditions tend to be required for efficient reductive amina-
could be detected (fig. S10): One correlating with imine-like tion of ketones. The generality of catalyst I was further
N known from pyridine (ca. 398 eV) (49, 50), the other man- demonstrated by the synthesis of branched primary amines
ifesting a higher binding energy, corresponding to N bonded starting from diverse ketones (Fig. 4). Gratifyingly, both in-
to the metal (49, 50). For the former sample a clear separation dustrially relevant and structurally challenging ketones un-
of both peaks was observed due to the slightly higher binding derwent smooth amination and produced the corresponding
energy. For Co-DABCO-TPA@C pyrolyzed at different tem- primary amines in good to excellent yields (Fig. 4). Biologi-
peratures, iminic N was observed and the binding energy of cally active amphetamines (products 77-79), which are po-
the Co-N bond increased as pyrolysis temperature ascended tent central nervous system (CNS) stimulating drugs, were
up to 800°C (fig. S11). In comparison to all other samples, the prepared in up to 91% yield. In general, amphetamines are
observation of the two N states was unique to these active synthesized by reductive amination of the corresponding
systems (fig. S11) (49, 50). It seems that for the optimal cata- phenyl-2-propanones using ammonium formate at higher
lyst, the bonding between Co and N is most pronounced. In temperature (Leuckart-Wallach reaction) (51). More sensitive
the material pyrolyzed at 1000°C the formation of nitrides products are prepared by reductive amination reactions us-
could be observed, as well (fig. S11). In the un-pyrolyzed and ing more expensive Pt- and Pd-based catalysts (51). We also
1000°C samples, the amount of Co in the near-surface region explored amination of non-steroidal anti-inflammatory
was too low for a reasonable peak fitting; for all other sam- agents (80-82) and steroid derivatives (83-87). Introduction
ples, the metal content was nearly the same.
of amino groups into these bio-active molecules has been
scarcely explored so far. Sulfur-containing compounds con-
stitute a common poison for most heterogeneous catalysts,
Synthesis of primary amines
With an active material (Co-DABCO-TPA@C-800; hereafter though they’re found in more than 300 FDA-approved drugs
represented as catalyst I) in hand, we investigated its sub- (52). In this context, thioethers are the most common scaf-
strate scope in the reductive amination. Initially, various pri- folds. Gratifyingly, catalyst I tolerated several S-containing
mary amines, which are easily further functionalized and substrates including thiophene, thioether, and sulfone (Figs.
therefore represent central building blocks, were prepared 3 and 4; products 28, 29, 30, 43, 46, 50).
starting from carbonyl compounds and simple ammonia
(Figs. 3 and 4). A crucial problem for the synthesis of primary
Synthesis of secondary and tertiary amines
amines has been the subsequent formation of secondary and We next explored the synthesis of secondary and tertiary
tertiary amines. The few catalysts known for the chemoselec- amines (Fig. 5), which are found in a large number of biolog-
tive reductive amination of aldehydes and ketones to give pri- ically active natural products (26–29). In contrast to the prep-
mary amines are based on precious metals (30, 31, 34–39) or aration of primary amines using ammonia (vide supra), a few
Raney Ni (30, 31, 40). Although Raney nickel is available and non-noble-metal based catalysts have already been used for
comparably inexpensive, it is highly flammable, hazardous reductive aminations to prepare secondary and tertiary
and less selective for functionalized and structurally complex amines; however, in such cases functional group tolerance
molecules.
and broad substrate scope have been limited (41–48). Both
By applying our cobalt catalyst, we performed selective re- nitroarenes and amines reacted with aldehydes to give the
ductive amination of 38 aldehydes to produce benzylic, het- corresponding secondary amines selectively in up to 92%
erocyclic and aliphatic linear primary amines, in good to yields (Fig. 5A; products 88-103). Compared to the traditional
excellent yields (up to 92%) (Fig. 3). Sensitive functional reaction of anilines, the one-pot reductive amination of ni-
groups including halides, esters as well as challenging car- troarenes and carbonyl compounds is straightforward and
bon-carbon double and triple bonds were well tolerated. We ensures a better step economy. This direct process shows that
also prepared amino-Salicin in 83% yield from the O-gluco- the cobalt nanocatalyst can also be used for the selective hy-
side Helicin (Fig. 3; product 41) to showcase the selective ami- drogenation of nitroarenes to anilines, which are of addi-
nation of bio-active compounds. Compared to benzaldehydes, tional interest for dye formation and materials synthesis. The
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reductive alkylation of N-containing heterocycles as well as 6A). In addition, the direct reductive methylation of ni-
primary and secondary amines gave the corresponding deriv- troarenes or amines with aqueous formaldehyde produced
atives in 81-88% yields. To demonstrate the amination of ke- selectively the corresponding N-methylamines (Fig. 6B).
tones, phenyl-2-propanone was reacted with 4- Compared to traditional alkylations using methyl-X com-
aminocyclohexane or 4-aminocyclohexanol (aliphatic pounds, advantageously the presented cobalt-catalyzed syn-
amines) and produced the corresponding secondary amines thesis of N-methylamines is either more cost-effective or
in 84% and 89%, respectively (Fig. 5A products 104 and 105). waste-free.
Further, we also tried the reductive amination of acetophe-
none using nitroarenes or aromatic amines, but did not ob-
Demonstrating catalyst recycling and gram scale re-
serve any significant desired product formation in this case. actions
Competition reactions of aniline with 4-bromobenzaldehyde Stability and recyclability are crucial features for any hetero-
and acetophenone were examined. Here, reductive amination geneous catalyst. In addition to the obvious cost advantages,
of the aldehyde occurred with excellent conversion and high the use of recyclable heterogeneous catalyst can considerably
selectivity, while the ketone remained untouched. Similarly, facilitate product purification. As shown in the reductive ami-
the reaction of 4-bromobenzaldehyde with aniline proceeded nation of phenylacetone our supported cobalt nanoparticles
selectively in the presence of phenyl-2-propanone. Thus, this are highly stable and are conveniently recycled up to 6 times
catalyst allows for selective amination of aldehydes in the without any significant loss of catalytic activity (fig. S14). Af-
presence of ketones. In general, for the majority of reductive ter that slight decrease of activity is observed.
amination reactions high chemoselectivity is obtained. How-
Next, gram scale reactions were performed for several in-
ever, in a few cases we observed minor amounts of the corre- teresting substrates. Apart from amphetamine, related 4(-4-
sponding alcohol (<5%), and/or secondary imine/amine hydroxyphenyl)-2-amino-butane and 1, 1-diphenyl-2-amino-
(<10%). In the preparation of secondary amines, up to 10% of propane as well as 17-amino-estrone were synthesized in up
the imine was observed. In bromo-substituted substrates to 50 g scale (Fig. 4). In all the cases similar yields to those of
(products 6, 7, 89, 112, 117, 122, 125), we also observed 50-100 mg scale reactions were obtained.
small amounts of de-halogenation. In general, we did not de-
Finally, we undertook preparation of ten existing drug
tect any over-alkylation products.
molecules (Fig. 5D). These syntheses showcase the applicabil-
To demonstrate compatibility with pre-existing stereo- ity of the supported cobalt nanoparticles for selective prepa-
chemistry, we performed the reductive N-alkylation with chi- ration of amine-based drugs. Previously, these molecules
ral amines. A plethora of chiral amines is available from were prepared by the reductive amination reactions using ei-
biological and industrial sources. As shown in Fig. 5B, the N- ther precious metal-based catalysts or sodium borohydride
alkylations of (S)-(−)-1-methylbenzylamine and (R)-(+)-α- (55–59). In addition, some have also been prepared by nucle-
methylbenzylamine proceeded efficiently and offered the cor- ophilic substitution reactions of corresponding amines with
responding chiral amine derivatives with retention of the halogenated compounds (55–60). Here, the corresponding ar-
original stereochemistry (Fig. 5B; products 106-108), as as- omatic aldehydes were treated with piperazine and morpho-
sessed by chiral HPLC (see supplementary materials S6.4(a) line derivatives or primary amines to give the desired
for procedure and HPLC data). Further, the reductive alkyla- products in 82-92% yields according to our standard proce-
tion of two amino acid esters (phenylalanine and tyrosine) dure, which further demonstrates the general utility of this
was performed in 82-89% yields (Fig. 5C; products 109-114). single cobalt-based catalyst.
However, the chirality of these N-alkylated amino acid esters
was not retained and we obtained the corresponding racemic
mixtures.
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ACKNOWLEDGMENTS
We gratefully acknowledge the support of European Research Council (ERC), Federal
Ministry of Education and Research (BMBF), the State of Mecklenburg-
Vorpommern and King Abdulaziz City for Science and Technology (KACST). We
thank the analytical staff of the Leibniz-Institute for Catalysis, Rostock for their
excellent service. All data are available in Supplementary Materials.
SUPPLEMENTARY MATERIALS
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www.sciencemag.org/cgi/content/full/science.aan6245/DC1
Materials and Methods
Figs. S1 to S14
NMR and HRMS spectra
10 May 2017; accepted 7 September 2017
Published online 21 September 2017
10.1126/science.aan6245
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6

Fig. 1. Preparation of graphitic shell encapsulated cobalt nanoparticles supported on carbon using MOF precursors.
Fig. 2. Catalyst characterization.
(A) EDXS map and STEM images of
Co-DABCO-TPA@C-800 catalyst.
EDXS map (left image): Cobalt =
red, Oxygen = blue, Carbon = green.
Black arrows highlight graphite
embedded metallic Co particles
(Middle image). White circles
represent single Co atoms at
carbon
(right
image).
(B)
EELS/EDXS study of Co-DABCO-
TPA@C-800 catalyst. Left image=
Parallel detected space-resolved
Carbon (EELS), Nitrogen (EELS)
and Cobalt (EDX) signals. Middle
image = HAADF image overlaid by
C/N elemental map at the position
of measurement. Right image=
Nitrogen K-edge EELS- spectrum of
the white box in the middle image.
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7

Fig. 3. Co-DABCO-TPA@C-800 catalyzed reductive amination of aldehydes for the
synthesis of linear primary amines. Reaction conditions: 0.5 mmol aldehyde, 25 mg catalyst
I (3.5 mol % Co), 5-7 bar NH3, 40 bar H2, 3 mL t-BuOH, 120°C, 15 hours; isolated yields reported
unless otherwise indicated. *GC yields using n-hexadecane standard. † 8 hours. Isolated as free
amines and converted to hydrochloride salts for measuring NMR and HRMS spectra.
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8

Fig. 4. Co-DABCO-
TPA@C-800
catalyzed reductive
amination of
ketones. Reaction
conditions: 0.5
mmol ketone, 25 mg
catalyst I (3.5 mol %
Co), 5-7 bar NH3, 40
bar H2, 3 mL THF
(dry), 120°C, 15
hours; isolated
yields reported
unless otherwise
indicated. *GC yields
using n-hexadecane
standard. †For 20
hours. ‡For 24
hours. § For 30
hours with 35 mg
catalysts. Isolated
as free amines and
converted to
hydrochloride salts
for measuring NMR
and HRMS. ||5-50 g
substrate, 25 mg
catalyst I (3.5 mol%
Co) for each 0.5
mmol substrate, 5-7
bar NH3, 40 bar H2,
120-150 mL dry THF,
120°C, 15-30 hours,
isolated yields.
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9

Fig. 5. Co-DABCO-
TPA@C-800 catalyzed
synthesis of secondary
and tertiary amines. (A)
Survey of nitroarenes and
amines. Reaction
conditions: 0.5 mmol
nitroarene, 0.75-1 mmol
aldehyde, 25 mg catalyst I
(3.5 mol % Co), 20 mg
amberlite IR-120, 3 mL t-
BuOH, 120°C, 24 hours;
isolated yields. *0.5 mmol
amine, 0.75 mmol
aldehyde. † 30 mg
catalyst, 30h. ‡0.5 mmol
amine, 0.75 mmol ketone.
(B) Reductive N-
alkylation of chiral
amines. Reaction
conditions: 10 mmol
amine, 15 mmol
benzaldehyde, 500 mg
catalyst I (3.5 mol% Co),
400 mg amberlite IR-120,
15 mL t-BuOH, 120°C, 24
hours; isolated yields. (C)
Reductive N-alkylation of
amino acid esters.
Reaction conditions: 0.5
mmol amino acid ester,
0.75 mmol aldehyde, 25
mg catalyst (3.5 mol%
Co), 20 mg amberlite IR-
120, 3 mL t-BuOH, 120°C,
24 hours; isolated yields.
(D) Preparation of
existing drug molecules.
Reaction conditions: 1
mmol amine, 1.5 mmol
aldehyde, 50 mg catalyst
I (3.5 mol % Co), 3 mL t-
BuOH, 120°C, 24 hours;
isolated yields. *75 mg
catalyst for 30 hours. †2
mmol amine, 1 mmol
aldehyde. ‡Synthesis
same as (†) followed by
acylation with acid
chlorides (see
supplementary materials
S6.5. for detailed
procedure).
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Fig. 6. Co-DABCO-TPA@C-800 catalyzed preparation of N-methylamines. (A) Reactions of aldehydes with
dimethylamine. Conditions: 0.5 mmol aldehyde, 100 μL aqueous dimethylamine (40%), 25 mg catalyst I (3.5 mol %
Co), 3 mL t-BuOH, 120°C, 24 hours; isolated yields yields reported unless otherwise indicated. *GC yields using n-
hexane standard. (B) Reactions of nitroarenes or amines with formaldehyde. Conditions: 0.5 mmol nitroarene, 100-
200 μL aqueous formaldehyde (37%), 1:1 THF- H2O (3mL); isolated yields. *0.5 mmol amine, 100-200 μL aqueous
formaldehyde (37%), 1:1 THF- H2O (3 mL).
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MOF-derived cobalt nanoparticles catalyze a general synthesis of amines
Rajenahally V. Jagadeesh, Kathiravan Murugesan, Ahmad S. Alshammari, Helfried Neumann, Marga-Martina Pohl, Jörg Radnik
and Matthias Beller
published online September 21, 2017
ARTICLE TOOLS
http://science.sciencemag.org/content/early/2017/09/20/science.aan6245
SUPPLEMENTARY
MATERIALS
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REFERENCES
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