An efficient zinc-catalyzed dehydration of primary amides to nitriles

Article abstract of DOI:10.1002/asia.201100493

In the present study, the zinc-catalyzed dehydration of a variety of amides with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) as a dehydration reagent into the corresponding nitriles has been examined in detail. With the straightforward and commercially available zinc(II)triflate as the precatalyst and MSTFA, an excellent system has been established to afford nitriles in excellent yields and chemoselectivities. After investigation of reaction conditions and the scope and limitations, several efforts were carried out to understand the reaction mechanism.

Full text of DOI:10.1002/asia.201100493

DOI: 10.1002/asia.201100493
An Efficient Zinc-Catalyzed Dehydration of Primary Amides to Nitriles
Stephan Enthaler*[a] and Shigeyoshi Inoue[b]
Abstract: In the present study, the zinc-catalyzed dehydration of a variety of
amides with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) as a dehy-
dration reagent into the corresponding nitriles has been examined in detail. With
Keywords: amides · dehydration ·
the straightforward and commercially available zinc(II)triflate as the precatalyst
homogeneous catalysis · nitriles ·
and MSTFA, an excellent system has been established to afford nitriles in excel-
zinc
lent yields and chemoselectivities. After investigation of reaction conditions and
the scope and limitations, several efforts were carried out to understand the reac-
tion mechanism.
Introduction
ported.[17,18] Herein, we demonstrate the usefulness of an
easy-to-adopt zinc catalyst for the dehydration of primary
amides by applying N-methyl-N-(trimethylsilyl)trifluoroace-
tamide (MSTFA) as the dehydration reagent.
Nitrile functionalities are extensively applied in organic
chemistry and represent building blocks for the production
of pharmaceuticals, agrochemicals, and polymers.[1] Within
the various protocols to synthesize nitriles, one convenient
and classical way to access nitriles is the dehydration of pri-
mary amides. Extensive application was achieved for dehy-
dration with stoichiometric acidic (e.g., POCl3, P2O5, SOCl2,
TiCl4) as well as basic reagents (e.g., NaBH4) or a combina-
tion of reagents.[2] The development of sustainable and se-
lective protocols is one of the fundamental research goals in
modern chemistry.[3] Based on these requirements more re-
cently the application of transition metal catalysts became
an efficient and flexible alternative.[4] Dehydration in the
presence of catalytic amounts of metal precursors (e.g., Ru,
Pd, Rh, W, V, Re, U)[5–11] and, for example, silanes as dehy-
dration reagents has been reported, while in the absence of
the dehydration reagent high reaction temperatures are re-
Results and Discussion
Initially, the dehydration of benzamide (1) with N-methyl-
N-(trimethylsilyl)trifluoroacetamide (2) in toluene was stud-
ied as a model reaction to evaluate suitable reaction condi-
tions and to study the influence of various reaction parame-
ters (Table 1). As expected when using MSTFA in the ab-
sence of any metal source no formation of benzonitrile (1a)
was observed, while significant amounts of the monosilylat-
ed benzamide was detected by GC-MS (Table 1, entry 1). In
contrast, in the presence of 5.0 mol% of commercially avail-
able ZnACTHNURTGENNG(U OTf)2 and MSTFA (3.5 equiv) excellent yield (>
99%) and chemoselectivity (>99%) were realized under
ambient conditions (Table 1, entry 2). Additionally, the
effect of various zinc sources such as ZnF2, ZnCl2, Zn-
AHCTNUGTREUN(GNN OAc)2, ZnAHCUTNRTGENNG(UN acac)2, and ZnCAHTNUGTREN(GUNN ClO4)2 on the benzonitrile for-
mation was investigated (Table 1, entries 3–7). All zinc sour-
ces led to a quantitative conversion of benzamide to yield
quired.[12] Primary benzamides were tretaed with R3Si H to
ꢀ
produce the corresponding nitrile, hydrogen, and siloxanes.
Nevertheless, present research is focused on the replace-
ment of these reagents with cheaper and less-toxic metals.[13]
Currently, the application of more environmental friendly
metals (e.g., Fe, Zn) in catalysis has been extensively stud-
ied.[14–16] Indeed, cheap, abundant, and non-toxic metals such
as iron have also been probed for the dehydration of
amides, while the application of zinc has been scarcely re-
benzonitrile, whereas ZnACTHNUTRGNE(UNG OAc)2 gave a decreased yield of
94%. Besides toluene as a solvent dioxane, dichlorome-
thane, and tetrahydrofuran (THF) have been applied. Excel-
lent performance was found for THF with a yield of >99%
(Table 1, entry 8). Noteworthy, the reaction temperature was
decreased to 708C. A further decrease to room temperature
resulted in a diminished yield (Table 1, entry 9). The loading
[a] Dr. S. Enthaler
Technische Universitꢀt Berlin
Department of Chemistry
of ZnACTHNUTRGNE(NUG OTf)2 was decreased to 1.0 mol%, thereby resulting
again in excellent yields of 1 (Table 1, entry 10). Moreover,
the amount of MSTFA was studied and demonstrated the
need for more than three equivalents (Table 1, entries 10–
12).[19]
To explore the scope and limitations of the presented zinc
catalyst, the dehydration of a variety of primary amides was
performed (Table 2). The reaction conditions are in accord-
Cluster of Excellence “Unifying Concepts in Catalysis”
Straße des 17. Juni 115, D-10623 Berlin (Germany)
Fax : (+49)3031429732
E-mail: stephan.enthaler@tu-berlin.de
[b] Prof. Dr. S. Inoue
Institute of Chemistry: Metalorganics and Inorganic Materials
Technische Universitꢀt Berlin
Straße des 17. Juni 135, Sekr. C2, D-10623 Berlin (Germany)
Chem. Asian J. 2012, 7, 169 – 175
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
169

FULL PAPERS
Table 1. Zinc-catalyzed dehydration of benzamide 1.
Having found a suitable system for the dehydra-
tion of amides into the corresponding nitrile func-
tionality, we became interested in the evaluation of
the reaction mechanism. Two different reaction
pathways can be considered (Scheme 1). The first
one is the “bissilylation” pathway, which has been
ꢀ
proposed recently for the application of Si H com-
Entry[a] Zinc source [mol%] MSTFA [equiv] t [h] T [8C] Solvent Yield [%][b]
pounds.[5a,17] In accordance to that the primary
amide can be activated by the Lewis acidic Zn-
1
2
3
4
5
6
7
8
–
Zn
Zn
ZnF2 (5)
ZnCl2 (5)
Zn
Zn
Zn
Zn
Zn
Zn
Zn
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
2.0
1.0
24
24
24
24
24
24
24
24
96
24
24
24
100
100
100
100
100
100
100
70
toluene <1
toluene >99
toluene 94
toluene >99
toluene >99
toluene >99
toluene >99
ACHTUNGTRENNUNG
AHCTUNGRTEGNUN(N OTf)2 and allow therefore the attack of the silyla-
ACHTUNGTRENNUNG
tion reagent MSTFA and the transfer of SiMe3 to
the amide functionality. This process takes place
two times, and results in the formation of N-methyl-
trifluoroacetamide (21) and the double silylated in-
termediate 23. As reported, this type of compound
can easily rearrange into the N,O-bis(trimethylsily-
l)imidate.[21] The zinc catalyst activates this inter-
mediate and forces the abstraction of the siloxane
25 to yield the desired nitrile and provides the free
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
T
THF
THF
THF
THF
THF
>99
<5
>99
<1
9
N
r.t.
70
70
10
11
12
N
T
A
70
<1
[a] Reaction conditions:
1 (0.72 mmol), zinc source (1–5 mol%), MSTFA (1.0–
3.5 equiv), solvent (2.0 mL), RT!1008C, 24–96 h. [b] Determined by GC methods
ZnACTHNUTRGEN(UGN OTf)2, which can then react again. The second
is the “monosilylation” pathway as proposed in
Scheme 1. In agreement to the bissilylation process
using biphenyl as an internal standard.
ance to optimized conditions discovered in Table 1; this
means the corresponding amides were converted in the pres-
ence of 5.0 mol% ZnACTHNUTRGNEUNG(OTf)2 and 3.5 equivalents of MSTFA
the amide will be activated by the zinc and thus allow the
transfer of the SiMe3 group to the amide functionality to
form the monosilylated amide 22. This silylated amide can
undergo a rearrangement into the O-(trimethylsilyl)imidate
26, which after activation by the zinc catalyst eliminates the
desired nitrile and trimethylsilanol (27). The trimethylsilanol
can react with an excess of MSTFA to form the siloxane 25
and 21.
To elucidate the underlying mechanism of the dehydra-
tion, various experiments have been carried out. For pre-
liminary mechanistic investigations the dehydration in the
absence of MSTFA was studied. As a model substrate para-
fluorobenzamide (3) was employed, because it is an excel-
lent probe for 19F NMR spectroscopy measurements. The
role of the MSTFA was clarified by dissolving substrate 3
in THF at 708C for 24 hours.[20] Firstly, various substituted
benzamides were tested. In all cases excellent yields were
observed. No significant effect was detected for electron-
withdrawing as well as electron-donating groups (Table 2,
entries 1–10). Only in the case of strong electron-withdraw-
ing functionalities such as para-trifluoromethylbenzamide
(10) and para-nitrilobenzamide (11) moderate yields were
obtained (Table 2, entries 8–9). Moreover, naphthylamides
were dehydrated with excellent yields and selectivities,
while for nitrogen-based heteroaromatics the catalyst was
completely inactive (Table 2, entries 11–14). Besides, alkyl
amides were reacted under optimized conditions, resulting
in excellent yields of the corresponding nitriles (Table 2, en-
tries 15–16). Furthermore the catalyst showed high efficien-
cy in the dehydration of thiobenzamide (19) (Table 2,
entry 17).
and catalytic amounts of ZnACHTNUGRTNEUNG(OTf)2 (10 mol%) in [D8]THF.
At room temperature as well as after heating for 24 hours
no product formation was observed, while the signals for
compound 3 (d=ꢀ111.0 ppm, sept, J=4.69 Hz) and Zn-
A
Zn
A
function of the zinc precursor, MSTFA and 3 were mixed in
[D8]THF in the absence of zinc, but no product formation
was detected, which clearly indicates that the zinc acts as a
catalyst. In addition, even after heating to 708C for 24 hours
no monosilylation or bissilylation of 3 was observed, which
is in contrast to substrate 1 (vide supra). This fact probably
points to a dual function of zinc, on the one hand it acts as a
silylation catalyst and on the other hand as an activator for
the elimination step. Obviously, for dehydration of primary
amides all three compounds are necessary. After addition of
MSTFA to this mixture three new peaks appeared, which
could be attributed to MSTFA and the hydrolyzed product
21. After heating for several hours, a 19F NMR spectrum
was recorded, which revealed the formation of para-fluoro-
Abstract in German: Im Rahmen dieser Arbeit wird die
Zink-katalysierte Dehydration von primꢀren Amiden zu
den entsprechenden Nitrilen mit Hilfe von N-Methyl-N-(tri-
methylsilyl)trifluoroacetamid (MSTFA) vorgestellt. Hierbei
konnten exzellente Ausbeuten und Selektivitꢀten (>99%)
durch Anwendung von einfachen und kommerziell verfꢂg-
baren Zinksalzen beobachtet werden. Nach eingehender
Untersuchung verschiedenster Reaktionsparameter wurden
die hervorragenden Eigenschaften des Katalysatorsystems in
der Dehydration zahlreicher primꢀrer Amide gezeigt. Zum
tieferen Verstꢀndnis der Reaktion wurden verschiedene
mechanistische Experimente durchgefꢂhrt.
170
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Chem. Asian J. 2012, 7, 169 – 175

Zinc-Catalyzed Dehydration of Primary Amides to Nitriles
Table 2. Scope and limitations of the zinc-catalyzed dehydration of pri-
mary amides.
benzonitrile (3a, d=ꢀ104.9 ppm, sept, J=4.56 Hz). Note-
worthy, the signal for Zn(OTf)2 was unchanged and no mon-
osilylated or bissilylated products of 3 were observed on the
NMR time scale.
AHCTUNGTRENNUNG
Entry[a]
Substrate
Yield [%][b]
In addition, the 29Si NMR spectrum revealed the forma-
tion of Me3SiOSiMe3 (25, d=7.1 ppm), while the signals for
MSTFA (2, d=25.6 ppm) disappeared.[22] To distinguish be-
tween the mono- and bissilylation pathway the monosilylat-
ed compound 30 and the bissilylated compound 29 were pre-
pared (Scheme 2). Compound 29 was synthesized according
to the procedure reported by Nagashima and co-workers.[5]
The benzoyl chloride 28 was treated with lithium hexame-
thyldisilazane (LiHMDS) at low temperature to yield com-
pound 29, which was later on heated in [D8]THF in the pres-
1
3
4
5
3a: >99 (94)
2
3
4a: >99 (94)
5a: 97 (91)
4
5
6
6
7
8
6a: >99 (93)
7a: >99 (90)
8a: >99 (90)
ence of catalytic amounts of ZnACHTUNRGTNEUNG(OTf)2 to obtain 3a with a
yield of 49% after six hours. However, the monosilylated
benzamide was accessible by reaction of benzamide 3 with
chlorotrimethylsilane in the presence of triethylamine. In
contrast to 29 no formation of 3a was observed.
Based on these results the reaction mechanism by the bis-
silylation pathway is more likely. To prove these assump-
tions, theoretical investigations were carried out. Quantum
chemical calculations using density functional theory at the
B3LYP/6-31G(d) level were performed.[23] First the starting
material MSTFA was examined, as different states are as-
sumed, for example, N- and O-silylation. Two isomers of the
N-silylated product are possible; these isomers are the tri-
methylsilyl group E- or Z-positioned to the oxygen
(Figure 1, 2 and 2a). As shown in Figure 1, the rotation
7
8
9
9
9a: >99 (95)
10a: 63
10
11
11a: 47
10
12
12a: >99 (92)
11
12
13
14
13a: >99 (93)
14a: >99 (92)
Figure 1. N-methyl-N-(trimethylsilyl)trifluoroacetamide (2) versus N-
methyl-O-(trimethylsilyl)trifluoroacetoimidate (2c).
ꢀ
energy of the C N
(SiMe3)(Me) bond in MSTFA (2) is
13
14
15
16
15a: <1
16a: <1
13.8 kcalmolꢀ1 and a lower energy for 2a was observed. Fur-
thermore, we assume for the transfer of the silyl group from
the nitrogen to the oxygen an intramolecular process
through a 4-membered transition state 2a-TS (Figure 1).
The transition state 2a-TS was found in this pathway with a
barrier of 16.9 kcalmolꢀ1. The O-silylated compound 2c was
comparable in energy with 2. By judging from the relative
energy of 2-TS and 2a-TS, it is reasonable to expect that the
reaction occurs at room temperature. Due to the attached
N-methyl group in MSTFA, an internal elimination of the
trimethylsilyl group is hampered. Based on this fact and in
cooperation with activation by the CF3 functionality, the
silyl group is transferred into a primary amide. As a model
for primary amides acetamide was chosen, because of sim-
plicity. Initially the bissilylation was studied. In Figure 2, the
pathway for the formation of acetonitrile (33) and
15
16
17
18
17a: >99 (87)
18a: >99 (91)
17
19
1a: >99[c]
[a] Reaction conditions: amide (1.0 mmol), ZnACTHNURTGNENG(U OTf)2 (5 mol%), MSTFA
(3.5 equiv), THF (2.0 mL), 708C, 24 h. [b] Determined by GC methods
and 1H NMR spectroscopy. The yield of isolated product is in brackets.
[c] Determined by GC methods using biphenyl as an internal standard.
Chem. Asian J. 2012, 7, 169 – 175
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171

S. Enthaler and S. Inoue
FULL PAPERS
Scheme 1. Mechanistic proposal for the dehydration of amides.
probably be influenced by the
catalyst. The overall pathway is
exothermic by 12.3 kcalmolꢀ1.
The monosilylation pathway
was investigated by theoretical
methods. A schematic poten-
tial-energy surface for the for-
mation of trimethylsilylanol 27
and acetonitrile 33 from the
monosilylated compound 34 is
given in Figure 3. This pathway
includes the rearrangement of
34 into 35 via transition state
34-TS, formation of O-silylated
species 36 via transition state
ꢀ
35-TS, and cleavage of the Si
ꢀ
O and N H bonds of 36 to give
33 and 27. Interestingly, this
process is endothermic by
14.3 kcalmolꢀ1. This is contrary
Scheme 2. Synthesis of mono- and bissilylated benzamide 29 and 30.
to the bissilylated pathway
(vide supra). Accordingly, we
have assumed that the bissily-
Me3SiOSiMe3 (25) from the bissilylated compound 30 are
presented with the energy profile.
lated pathway (Figure 2) is more favorable than the monosi-
lylated pathyway (Figure 3).
First a rearrangement takes place via the 4-membered
transition state 31-TS to form the more stable N,O-bis(tri-
methylsilyl)imidate 32 with a barrier of 10.1 kcalmolꢀ1.
Conclusions
ꢀ
ꢀ
Next, a concerted bond cleavage of the C O and N Si
bonds of 32 proceeds via transition state 32-TS, with a barri-
er of 54.6 kcalmolꢀ1, to afford 25 and 33. This barrier can
In summary, we have developed an efficient method for the
dehydration of primary amides into the corresponding ni-
172
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Chem. Asian J. 2012, 7, 169 – 175

Zinc-Catalyzed Dehydration of Primary Amides to Nitriles
4-Fluorobenzonitrile (3a)
1H NMR (CDCl3, 200 MHz): d=7.57–7.67 (m, 2H), 7.05–7.18 ppm (m,
2H); 13C NMR (CDCl3, 50 MHz): d=167.6, 162.5, 134.8, 134.6, 118.0,
117.1, 116.6, 108.6, 108.5 ppm; MS (EI) m/z=121 (100, M+), 94 (39);
t(GC)=5.192 min.
4-Chlorobenzonitrile (4a)
1H NMR (CDCl3, 200 MHz): d=7.39–7.59 ppm (m, 4H); 13C NMR
(CDCl3, 50 MHz): d=139.7, 133.4, 129.7, 118.0, 110.7 ppm; MS (EI) m/
z=137 (100, M+), 102 (38), 75 (17), 50 (15); t(GC)=8.142 min.
4-Bromobenzonitrile (5a)
Figure 2. Mechanistic proposal for the dehydration of amides—bissilya-
tion pathway.
1H NMR (CDCl3, 200 MHz): d=7.45–7.64 ppm (m, 4H); 13C NMR
(CDCl3, 50 MHz): d=133.4, 132.7, 128.1, 118.1, 111.2 ppm; MS (EI) m/
z=181 (60, M+), 102 (100), 75 (31), 50 (24); t(GC)=9.583 min.
triles with MSTFA as the silylation reagent in the presence
of simple zinc salts under mild reaction conditions. Further-
more, mechanistic investigations indicated, that zinc(II) tri-
flate acts as a Lewis acid catalyst.
4-Methylbenzonitrile (6a)
1H NMR (CDCl3, 200 MHz): d=7.47–7.55 (m, 2H), 7.19–7.28 (m, 2H),
2.39 ppm (s, 3H); 13C NMR (CDCl3, 50 MHz): d=143.7, 132.1, 129.8,
119.2, 109.8, 21.8 ppm; MS (EI) m/z=117 (100, M+), 90 (47), 63 (14);
t(GC)=7.467 min.
3-Methylbenzonitrile (7a)
Experimental Section
1H NMR (CDCl3, 200 MHz): d=7.23–7.43 (m, 4H), 2.34 ppm (s, 3H);
13C NMR (CDCl3, 50 MHz): d=139.3, 133.7, 132.4, 132.1, 129.2, 119.0,
112.2, 21.1 ppm; MS (EI) m/z=117 (100, M+), 90 (50); t(GC)=
7.250 min.
General
All compounds were used as received without further purification. THF
and toluene were dried by applying standard procedures. 1H, 19F, and
13C NMR spectra were recorded on a Bruker AFM 200 spectrometer
(1H: 200.13 MHz; 13C: 50.32 MHz; 19F: 188.31 MHz) using the proton
signals of the deuterated solvents as a reference. GC-MS measurements
were carried out on a Shimadzu GC-2010 gas chromatograph (30 m Rxi-
5 ms column) linked with a Shimadzu GCMA-QP 2010 Plus mass spec-
trometer.
2-Methylbenzonitrile (8a)
1H NMR (CDCl3, 200 MHz): d=7.39–7.57 (m, 2H), 7.15–7.33 (m, 2H),
2.50 ppm (s, 3H); 13C NMR (CDCl3, 50 MHz): d=141.9, 132.7, 132.5,
130.2, 126.2, 118.1, 112.8, 20.4 ppm; MS (EI) m/z=117 (100, M+), 90
(56), 63 (14); t(GC)=6.842 min.
4-Methoxybenzonitrile (9a)
1H NMR (CDCl3, 200 MHz): d=7.50–7.58 (m, 2H), 6.86–6.95 (m, 2H),
3.81 ppm (s, 3H); 13C NMR (CDCl3, 50 MHz): d=162.8, 133.9, 119.1,
114.7, 103.8, 55.5 ppm; MS (EI) m/z=133 (100, M+), 103 (46), 90 (47),
76 (12), 63 (17); t(GC)=10.150 min.
General Procedure for the Dehydration of Amides
A pressure tube was charged with an appropriate amount of ZnACTHNUTRGNEUNG(OTf)2
(0.05 mmol, 5.0 mol%), the corresponding amide (1.0 mmol), and
MSTFA (3.5 equivalents, 3.5 mmol). After addition of THF (2.0 mL), the
reaction mixture was stirred in a preheated oil bath at 708C for 24 h. The
mixture was cooled in an ice bath and biphenyl (internal standard) was
added. The solution was diluted with dichloromethane and an aliquot
was taken for GC-analysis (30 m Rxi-5 ms column, 40–3008C). The sol-
vent was carefully removed and the residue was purified by column chro-
matography (n-hexane/ethyl acetate 5:1). The analytical properties of the
corresponding nitriles are in agreement with literature.[24,25]
4-Trifluoromethylbenzonitrile (10a)
1H NMR (CDCl3, 200 MHz): d=7.68–7.82 ppm (m, 4H); 13C NMR
(CDCl3, 50 MHz): d=135.5, 134.9, 134.2, 133.5, 133.3, 132.7, 131.2,
126.29, 126.22, 126.14, 126.07, 125.8, 120.4, 117.4, 116.11, 116.08,
114.9 ppm; 19F NMR (CDCl3, 188 MHz) d=ꢀ63.6 ppm; MS (ESI) m/z=
171 (100, M+), 152 (40), 121 (70), 75 (20), 50 (11); t(GC)=5.008 min.
Figure 3. Potential-energy surface of the proposed pathway for the formation of trimethylsilylanol 27 and acetonitrile 33 from N-trimethylsilyl acetamide
34—monosilyation pathway.
Chem. Asian J. 2012, 7, 169 – 175
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173

S. Enthaler and S. Inoue
FULL PAPERS
4-Benzodinitrile (11a)
[4] a) Transition Metals for Organic Synthesis (Eds.: M. Beller, C.
Bolm), Wiley-VCH, Weinheim, 2004; b) Multiphase Homogeneous
Catalysis (Eds.: B. Cornils, W. A. Herrmann, I. T. Horvꢃth, W. Leit-
ner, S. Mecking, H. Olivier-Bourbigou, D. Vogt), Wiley-VCH, Wein-
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[5] For ruthenium, see: a) S. Hanada, Y. Motoyama, H. Nagshima, Eur.
J. Org. Chem. 2008, 4097–4100; b) Y. Watanabe, F. Okuida, Y.
Tsuji, J. Mol. Catal. 1990, 58, 87–94.
[6] For ruthenium, see: a) J. Blum, A. Fisher, Tetrahedron Lett. 1970,
11, 1963–1966; b) J. Blum, A. Fisher, E. Greener, Tetrahedron 1973,
29, 1073–1081.
[7] For tungsten, see: J. A. Campbell, G. McDougald, H. McNab,
L. V. C. Rees, R. G. Tyas, Synthesis 2007, 3179–3184.
(EI) m/z=128 (100, M+), 101 (27), 75 (12), 50 (11); t(GC)=10.083 min.
4-tert-Butylbenzonitrile (12a)
1H NMR (CDCl3, 200 MHz): d=7.38–7.56 (m, 4H), 1.26 ppm (s, 9H);
13C NMR (CDCl3, 50 MHz): d=156.8, 131.9, 126.2, 119.2, 109.1, 35.2,
30.8 ppm; MS (EI) m/z=159 (21, M+), 144 (100), 116 (71), 104 (15);
t(GC)=10.950 min.
Naphthalene-2-carbonitrile (13a)
1H NMR (CDCl3, 200 MHz): d=7.38–8.30 ppm (m, 7H); 13C NMR
(CDCl3, 50 MHz): d=133.3, 132.9, 132.6, 128.7, 128.6, 127.6, 125.1, 124.9,
117.8, 110.2 ppm; MS (EI) m/z=153 (100, M+), 126 (25); t(GC)=
13.533 min.
[8] For palladium, see: S. I. Maffioli, E. Marzorati, A. Marazzi, Org.
Lett. 2005, 7, 5237–5239.
[9] For vanadium, see: S. Sueoka, T. Mitsudome, T. Mizugaki, K. Jitsu-
kawa, K. Kaneda, Chem. Commun. 2010, 46, 8243–8245.
[10] For rhenium, see: a) K. Ishihara, Y. Furuya, H. Yamamoto, Angew.
Chem. 2002, 114, 3109–3112; Angew. Chem. Int. Ed. 2002, 41, 2983–
2986; b) Y. Furuya, K. Ishihara, H. Yamamoto, Bull. Chem. Soc.
Jpn. 2007, 80, 400–406.
Naphthalene-1-carbonitrile (14a)
1H NMR (CDCl3, 200 MHz): d=7.47–8.25 ppm (m, 7H); 13C NMR
(CDCl3, 50 MHz): d=133.4, 133.0, 132.7, 132.5, 128.9, 128.7, 128.6, 125.4,
124.9, 117.9, 110.3 ppm; MS (EI) m/z=153 (100, M+), 126 (28), 63 (11);
t(GC)=13.175 min.
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Benzyl cyanide (15a)
1H NMR (CDCl3, 200 MHz): d=7.31–7.42 (m, 5H), 3.83 ppm (s, 2H,
CH2); 13C NMR (CDCl3, 50 MHz): d=130.1, 129.2, 127.8, 127.7,
23.7 ppm; MS (EI) m/z=117 (100, M+), 90 (62), 63 (13), 51/14); t(GC)=
8.17083 min.
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1-Adamantylnitrile (16a)
1H NMR (CDCl3, 200 MHz): d=1.50–2.10 ppm (m, 15H); 13C NMR
(CDCl3, 50 MHz): d=125.2,39.9, 35.7, 27.1, 26.5 ppm; MS (ESI) m/z=
161 (44, M+), 146 (20), 134 (100), 119 (12), 104 (16), 93 (53), 79 (25), 69
(23); t(GC)=12.117 min.
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Acknowledgements
Financial support from the Cluster of Excellence “Unifying Concepts in
Catalysis” (funded by the Deutsche Forschungsgemeinschaft and admin-
istered by the Technische Universitꢀt Berlin) is gratefully acknowledged.
The authors thank Dr. K. Junge and B. Wendt (Leibniz Institut fꢂr Kata-
lyse e.V. an der Universitꢀt Rostock) for donation of substrates. Prof. Dr.
S.I thanks the Alexander von Humboldt foundation for financial support
by the Sofja Kovalevskaja Program. Furthermore, M. Weidauer, S.
Hennig, and R. Skobalj (Technische Universitꢀt Berlin) are thanked for
their support.
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Received: May 30, 2011
Published online: September 29, 2011
Chem. Asian J. 2012, 7, 169 – 175
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