A Practical and General Base-Catalyzed Carbonylation of Amines for the Synthesis of N-Formamides

Article abstract of DOI:10.1002/chem.201502107

A highly practical and general base-catalyzed carbonylation of amines to the corresponding N-formamides has been realized. Cheap inorganic bases, including GroupIA and IIA metal hydroxides, alkoxides, carbonates, and phosphates, were effective catalysts for the transformation. In the presence of 10-40mol% of KOH or K₂CO₃, various amines were converted into the corresponding N-formamides in good-to-excellent yields using CO as the formylation reagents. Metal-free carbonylation: A simple and practical procedure for the catalytic carbonylation of amines has been developed (see scheme). In the presence of 10-40mol% of KOH or K₂CO₃, various amines have been converted into the corresponding N-formamides in good-to-excellent yields by using CO as the formylation reagent.

Full text of DOI:10.1002/chem.201502107

DOI: 10.1002/chem.201502107
Full Paper
&
Amine Carbonylation
A Practical and General Base-Catalyzed Carbonylation of Amines
for the Synthesis of N-Formamides
[a]
Wanfang Li and Xiao-Feng Wu*
Abstract: A highly practical and general base-catalyzed car-
bonylation of amines to the corresponding N-formamides
has been realized. Cheap inorganic bases, including Group IA
and IIA metal hydroxides, alkoxides, carbonates, and phos-
phates, were effective catalysts for the transformation. In the
presence of 10–40 mol% of KOH or K CO , various amines
2 3
were converted into the corresponding N-formamides in
good-to-excellent yields using CO as the formylation re-
agents.
Introduction
Formamides are important intermediates in the synthesis of
[
1]
many biologically active molecules or related backbones. In
addition, they also provide starting materials for the introduc-
[2]
tion of versatile functional groups and undergo elegant
[3]
transformations catalyzed by transition metals. Owing to
their many applications, numerous approaches have been de-
[4]
veloped for their synthesis. Of the known procedures, the N-
formylation of amines using various C building blocks is one
1
[4g]
of the most economic and straightforward methods. The C1
building blocks that have been used for the N-formylation of
[
5]
[6]
amines include chloroform, formic acid and its derivatives,
[
7]
[8]
[9]
[10]
paraformaldehyde, methanol, CO2, and CO.
From the
Scheme 1. N-Formylation reactions of amines with CO.
viewpoints of atom economy (E factor=0; atom efficiency=
00%) and practicality, CO is the most attractive and ideal car-
1
bonyl source because it is cheap, readily available, and pro-
duces no additional waste.
transition-metal-free methodologies. As expected, this idea has
been accepted by synthetic chemists and some metal-free pro-
cedures have been developed. In the literature, NaOMe has
been reported as a catalyst for the carbonylation of dimethyl-
amine and this procedure has been applied in industry for the
For the CO-based carbonylative transformation of amines,
various procedures have been developed (Scheme 1) and the
oxidative carbonylation of amines to ureas using various transi-
[11]
tion-metal catalysts is well established. However, the direct
[
10b]
[18]
carbonylation of amines to N-formamides by using transition-
production of DMF.
In addition, N-heterocyclic carbenes
have been reported to catalyze the car-
[12]
[13]
[14]
[15]
[16]
[17]
[10c,d]
metal catalysts (e.g., Cu,
Fe,
Zn,
Ru,
Rh,
Ni ) is
and ionic liquids
much less explored. In an early example in 1966, Saegusa et al.
used copper salts to catalyze the carbonylation of N-alkyl-
amines to the corresponding formamides under harsh condi-
tions (1408C, 60 bar CO) and with only limited substrate
bonylation of amines to formamides, although the substrate
scope was narrow and the catalysts were relatively expensive.
In 2012, Gerack and McElwee-White reported an oxidative car-
bonylation of amines to formamides using NaIO (1.6 equiv) as
4
[
12a]
scope.
the oxidant together with a large amount of NaI (4 equiv) and
[
19a]
Under the banner of “Green Chemistry and Sustainable De-
velopment”, it is both interesting and necessary to develop
K CO (4 equiv).
Later on, they found the presence of the
2
3
oxidant was not necessary and K CO (4 equiv) can act as the
2
3
[
19b]
promoter.
Herein, we wish to report our results on the
base-catalyzed carbonylation of amines to N-formamides. In
the presence of some inorganic bases, various amines were
converted into the corresponding formamides in good-to-ex-
cellent yields. This procedure represents a highly practical pro-
cedure for the preparation of N-formamides.
[
a] Dr. W. Li, Prof. Dr. X.-F. Wu
Leibniz-Institut für Katalyse e.V. an der Universität Rostock
Albert-Einstein-Strasse 29a, 18059 Rostock (Germany)
E-mail: xiao-feng.wu@catalysis.de
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201502107.
Chem. Eur. J. 2015, 21, 14943 – 14948
14943
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when the reaction was carried out in MeOH (Table 1, entry 8).
Surprisingly, no product was detected with NaOH as the cata-
lyst when EtOH was used instead of MeOH (Table 1, entry 9). In
addition, the alkali hydroxides LiOH and KOH were very effi-
cient catalysts for this reaction (Table 1, entries 10 and 11).
Note, a yield of more than 99% of 2a was obtained with
Table 1. Optimization of the reaction conditions for the formylation of
piperidine (1a).
[a]
[b]
Entry
Catalyst (x [mol%])
Solvent
[CO] [bar]
Yield [%]
5
mol% of KOH within 40 h (Table 1, entry 12). The carbonyla-
[
c]
1
2
3
4
5
6
7
8
9
KOtBu (5)
toluene
toluene
toluene
toluene
toluene
toluene
MeOH
MeOH
EtOH
MeOH
MeOH
MeOH
THF
dioxane
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
40
40
40
40
40
40
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
14
>99
65
tion of 1a to 2a was totally ineffective in other solvents such
as THF and dioxane catalyzed by KOH (Table 1, entries 13 and
[
c]
KOtBu (40)
NaOtBu (40)
LiOtBu (40)
KOH (40)
NaOMe (40)
NaOMe (10)
NaOH (10)
NaOH (10)
LiOH (10)
KOH (40)
1
4). To our surprise, the cheaper base Ca(OH) was also a very
2
0
0
0
efficient catalyst for the N-formylation of 1a (Table 1, en-
tries 15). Other bases such as NaHCO , K CO , Na CO , K PO ,
3
2
3
2
3
3
4
>99
>99
0
and NaOAc were also tested in this reaction and gave good-to-
excellent yields (Table 1, entries 16–20). To exclude the possibil-
ity of trace amounts of metal remaining in the base catalyst,
sublimed-grade KOtBu (99.99% purity, trace metals basis) was
used (Table 1, entries 1 and 2). In addition, metal salts such as
CuCl , CuCl, PdCl , Pd(OAc) , and Pd/C were tested but these
1
0
96
[d]
1
1
>99 (91 )
>99
0
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
KOH (5)
KOH (40)
KOH (40)
2
2
2
0
did not catalyze the reaction under the same conditions. Sever-
al other control experiments were also carried out. No product
was detected in the absence of catalyst (Table 1, entry 21).
Only trace amounts of formylation product were formed with
an iron carbonyl complex as the catalyst, which is in agree-
Ca(OH)
NaHCO
2
(40)
(40)
(20)
(20)
(10)
>99
>99
>99
>99
>99
82
0
5
19
6
3
K
2
CO
3
Na
2
CO
3
K
3
PO
4
NaOAc (40)
–
ment with a previous report (when [Fe(CO) ] was applied as
5
[Fe(CO)
[Fe(CO)
5
3
] (5)
(cot)] (5)
the catalyst, 95 bar of CO and a temperature of 2008C was
[
e]
[13]
necessary). No better yields were observed with the other
FeCl
FeCl
2
(5)
(5)
iron catalysts tested.
3
0
9
28
[Fe(acac)
[Fe(acac)
2
3
] (5)
] (5)
Based on the results of the screening of the reaction condi-
tions, we chose KOH as the catalyst to examine the substrate
scope of this new N-formylation reaction. The cyclic secondary
amines pyrrolidine, 4-methylpiperidine, morpholine, and aze-
pane (1b–f) were smoothly formylated with CO in the pres-
ence of 40 mol% KOH to give good yields of the correspond-
ing formamides (Table 2). The bulkier cyclic amine 2,2,6,6-tetra-
methylpiperidine was also tested, but no conversion was de-
tected even under harsher conditions. When using KOH as the
catalyst with dibenzylamine (1g), the yield of 2g was less than
40% due to the incomplete conversion of the starting material.
However, an isolated yield of 76% was observed when
20 mol% KOtBu was used. Dihexylamine (1h) was carbony-
lated to 2h in excellent yield. Under the same conditions, the
formylations of N-methyl-2-fluorobenzylamine (1i) and N-ethyl-
aniline (1j) were much less efficient than other secondary
amines. The primary and secondary amines present in 2-piper-
azinylethylamine (1k) were both formylated. Various primary
amines 1l–r were also carbonylated to the desired products in
good-to-excellent yields. Of note, the enantiomerically pure
amine (S)-1-phenylethan-1-amine (1o) was formylated to 2o
without racemization. The allylic amine geranylamine (1s) was
also converted into corresponding formamide 2s in good
yield. Catalyzed by either KOH or K CO , 2-picolylamine (1t)
[
(
1
a] Reagents and conditions: 1a (50 mL, 0.5 mmol), solvent (2 mL), catalyst
x mol%), CO (y bar) reagents added for completeness; also in Table 2;
5 h, 1208C for entries 1–6, 110 8C for entries 7–27. [b] GC yield deter-
mined by using hexadecane as the internal standard. [c] Sublimed-grade
KOtBu (99.99% purity, trace metals basis) was used. [d] Isolated yield.
[
e] cot=cyclooctatetraene.
Results and Discussion
We began our investigation with piperidine (1a) as the sub-
strate and alkali metal alkoxides as the catalysts (Table 1). Ini-
tially, 5 mol% of KOtBu was used as the catalyst; only a yield
of 14% of piperidine-1-carbaldehyde (2a) was obtained in tol-
uene at 1208C under 40 bar of CO (Table 1, entry 1). Even
though the yield was improved to 99% with a catalyst loading
of 40 mol%, the high cost and instability of tBuOK towards
water still precludes this method from being a good procedure
(
Table 1, entry 2). During the examination of different alkali
tert-butoxides, we found that the nature of the cation plays an
important role in the carbonylation reaction. Under the same
conditions, NaOtBu gave a yield of only 65% and LiOtBu was
virtually ineffective (Table 1, entries 3 and 4). Other catalysts,
such as KOH and NaOMe, were also unable to catalyze this re-
action in toluene (Table 1, entries 5 and 6). However, when the
solvent was switched from toluene to methanol, the yield of
2
3
was also formylated to give 2t, which is a very useful inter-
mediate for the synthesis of azaindolizines. The formylation re-
action with the bulkier primary amine 1u showed lower activi-
ty and a yield of only 34% of 2u was observed.
2
a increased to 99% with 10 mol% of NaOMe (Table 1, en-
The procedure also worked well for the structurally more
complex amine 1v, which makes it potentially useful for some
tries 6 and 7). NaOH was found to be as effective as NaOMe
Chem. Eur. J. 2015, 21, 14943 – 14948
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[
a]
Table 2. Scope of the KOH-catalyzed formylation of amines.
Scheme 2. Scaled-up formylation of 1 f catalyzed by KOH.
Scheme 3. Proposed mechanism for the KOH-catalyzed N-formylation reac-
tion.
[
20]
tors. Remarkably, the model reaction can also be performed
on a large scale without any problem.
Finally, a possible reaction mechanism is proposed for this
base-catalyzed amine formylation reaction. KOH dissolves in
[
21]
heated MeOH to form potassium methoxide (Scheme 3a).
The nucleophilic attack of KOMe on CO then produces (me-
thoxycarbonyl) potassium (A), which can be protonated by
MeOH to form methyl formate while simultaneously regenerat-
ing KOMe. Next, the nucleophilic attack of the amine (or its
anion formed in the presence of KOMe) on methyl formate
leads to the formamide via intermediate C.
Another possibility is that NaOH or KOH reacts with CO to
[
22]
form formate (Scheme 4a), which acts as the formylation re-
agent. When 40 mol% of sodium or potassium formate were
employed as the catalyst, comparable high yields of 1a were
[
8
a] Reagents and conditions: 1 (2 mmol), solvent (4 mL), KOH (40 mol%,
5% purity), CO (10 bar), 15 h, 110 8C. [b] 20 mol% KOtBu was used as
the catalyst. [c] 40 mol% Ca(OH) was used as the catalyst. [d] No racemi-
2
zation occurred, as indicated by the closeness of the specific rotation to
our literature value, see our NMR and literature in Supporting Informa-
2 3
tion. [e] 40 mol% K CO was used as the catalyst. [f] 5mmol scale, 1208C,
4
8 h. n.d.=not detected.
multistep syntheses. Unfortunately, anilines 1w–y were rather
unreactive even under harsher conditions. The reaction of
amide 1z was also explored, but no conversion of the sub-
strate was observed.
Scheme 4. Exclusion of formate as the formylation reagent.
The above synthetic procedure could easily be scaled up to
synthesize some useful formamide intermediates. For example,
when 8 mmol of 1 f was subjected to a pressure of CO in the
presence of 10 mol% of KOH, an isolated yield of 88% of 2 f
was obtained after simple filtration of the reaction mixture
through a short pad of silica gel (Scheme 2). Compound 2 f
provides a starting material for the preparation of a class of
compounds that are used as mTOR and PI3K kinase inhibi-
observed (Scheme 4b). However, when 2 equivalents of
HCOONa or HCOOK were used under CO-free conditions, the
yield of 2a was only 6 and 13%, respectively (Scheme 4c).
Therefore potassium or sodium formate is not responsible for
the formylation reaction.
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1
3
C NMR (75 MHz, CDCl ): d=160.4, 45.6, 42.7, 24.5, 23.8 ppm; MS
Conclusion
3
+
(
EI): m/z (%): 99 (38) [M] , 71 (38), 43 (80), 29 (100).
We have developed a new, simple, practical, and efficient pro-
cedure for the N-formylation of amines by using CO as the car-
bonyl source. This procedure features the following advan-
tages. 1) There is no need for transition metals or any addi-
tives. 2) Cheap and stable catalysts are employed enabling
large-scale applications. 3) Purification of the final products is
easy because a gaseous formylation reagent is used. Therefore
we believe that this synthetic strategy would be a valuable
tool for the N-formylation of amines.
4-Methylpiperidine-1-carbaldehyde (2c): The product was ob-
tained by column chromatography (pentane/EtOAc, 1:1) as a color-
1
less liquid in a yield of 87% (221 mg). H NMR (300 MHz, CDCl ):
3
d=7.91 (s, 1H), 4.32–4.18 (m, 1H), 3.56–3.42 (m, 1H), 3.04–2.88 (m,
1
0
4
,
H), 2.60–2.45 (m, 1H), 1.69–1.46 (m, 3H), 1.08–0.92 (m, 2H),
13
.87 ppm (d, J=6.4 Hz, 3H); C NMR (75 MHz, CDCl ): d=160.5,
3
+
5.9, 39.7, 34.4, 33.0, 31.1, 21.5 ppm; MS (EI): m/z (%): 127 (43) [M]
112 (38), 91 (36), 98 (25), 84 (19), 56 (62), 42 (59), 20 (100).
Morpholine-4-carbaldehyde (2d): The product was obtained by
column chromatography (pentane/EtOAc, 1:1) as a colorless liquid
1
in a yield of 76% (175 mg). H NMR (300 MHz, CDCl ): d=7.90 (s,
3
1
H), 3.59–3.46 (m, 4H), 3.45–3.37 (m, 2H), 3.30–3.22 ppm (m, 2H);
13
Experimental Section
C NMR (75 MHz, CDCl ): d=160.5, 66.8, 66.0, 45.4, 40.1 ppm; MS
3
+
(
(
EI): m/z (%): 115 (100) [M] , 100 (63), 262 (88), 86 (42), 56 (71), 29
75).
General considerations
All reactions were carried out under an atmosphere of argon
unless otherwise specified. All solvents and reagents were pur-
chased from Sigma–Aldrich and used as received. NMR spectra
were recorded on a Bruker Avance 300 (300 MHz) spectrometer.
Azepane-1-carbaldehyde (2e): The product was obtained by
column chromatography (pentane/EtOAc, 2:1) as a colorless liquid
1
in a yield of 77% (196 mg). H NMR (300 MHz, CDCl ): d=8.07 (s,
3
1H), 3.44 (t, J=6.1 Hz, 2H), 3.36 (d, J=6.0 Hz, 2H), 1.80–1.64 (m,
13
Chemical shifts are given in ppm relative to the solvent: CDCl , d=
4H), 1.63–1.49 ppm (m, 4H); C NMR (75 MHz, CDCl ): d=162.3,
3
3
1
13
7
(
.26 ( H NMR) and 77.00 ppm ( C NMR); [D ]DMSO, d=2.50
H NMR) and 40.00 ppm ( C NMR). The products were isolated
47.1, 42.8, 42.8, 29.7, 27.4, 26.4, 26.3 ppm; MS (EI): m/z (%): 127 (35)
6
1
13
+
[M] , 112 (38), 98 (25), 84 (26), 70 (29), 56 (37), 42 (85), 29 (100).
from the reaction mixture by column chromatography on silica gel
0 (0.063–0.2 mm, 70–230 mesh, Merck). Mass spectra were re-
corded either on a HP 5989A mass selective detector or AMD 402/
. Gass chromatography was performed on a HP 6890 with a HP5
column. Optical rotations were measured on a Perkin-Elmer 341
polarimeter.
4
-Benzylpiperazine-1-carbaldehyde (2 f): The product was ob-
6
tained by column chromatography (EtOAc) as a white solid in
a yield of 89% (365 mg). H NMR (300 MHz, CDCl ): d=7.91 (s, 1H),
1
3
3
7
2
1
.28–7.11 (m, 5H), 3.51–3.44 (m, 2H), 3.43 (s, 2H), 3.31–3.21 (m,
13
H), 2.39–2.27 ppm (m, 4H); C NMR (75 MHz, CDCl ): d=160.5,
3
60.4, 137.3, 128.8, 128.1, 127.0, 62.6, 53.1, 52.0, 45.4, 39.7 ppm;
+
MS (EI): m/z (%): 204 (13) [M] , 146 (19), 132 (11), 91 (100), 85 (23),
General procedure for the base-catalyzed carbonylation
reactions
65 (28), 56 (27), 29 (17).
N,N-Dibenzylformamide (2g): The product was obtained by
column chromatography (pentane/EtOAc/CH Cl , 5:1:1) as a color-
2
2
The amine substrate (2 mmol) was added to each of the five
Wheaton vials (10 mL volume) equipped with a septum, short can-
nula, and stirring bar. The catalyst stock solution was prepared by
dissolving KOH (225 mg, 4 mmol) in anhydrous methanol (10 mL)
and injected equally into the five vials (5”2 mL). Further MeOH
1
less thick oil in a yield of 76% (343 mg). H NMR (300 MHz, CDCl ):
3
d=8.41 (s, 1H), 7.42–7.26 (m, 6H), 7.26–7.14 (m, 4H), 4.42 (s, 2H),
1
3
4
1
.23 ppm (s, 2H); C NMR (75 MHz, CDCl ): d=162.2, 135.5, 135.2,
3
28.3, 128.1, 127.9, 127.5, 127.1, 127.0, 49.5, 43.9 ppm; MS (EI): m/z
%): 225 (4) [M] , 134 (48), 106 (36), 91 (100), 79 (32), 65 (43), 29
+
(
(
(
2 mL) was subsequently added to each vial. Then the vials were
placed on an alloy plate and transferred under air to a 300 mL
560 series autoclave from Parr Instruments. After flushing the au-
7).
N,N-Dihexylformamide (2h): The product was obtained by
4
column chromatography (pentane/EtOAc, 5:1) as a colorless liquid
toclave three times with CO, a pressure of 10 bar was set and the
reaction was performed for 15 h at 1108C. After the autoclave had
cooled to room temperature, the pressure was carefully released.
The solvent was removed under reduced pressure and the crude
product purified by column chromatography on silica gel.
1
in a yield of 95% (407 mg). H NMR (300 MHz, CDCl ): d=7.86 (s,
3
1
4
H), 3.10 (t, J=7.8 Hz, 2H), 3.02 (t, J=7.1 Hz, 2H), 1.42–1.26 (m,
H), 1.23–1.01 (m, 12H), 0.79–0.61 ppm (m, 6H); C NMR (75 MHz,
13
CDCl ): d=162.2, 47.0, 41.6, 31.1, 31.0, 28.2, 26.8, 26.2, 25.7, 22.1,
3
+
2
2.1, 13.6, 13.5 ppm; MS (EI): m/z (%): 213 (1) [M] , 142 (78), 72
Caution! Carbon monoxide is toxic; all the manipulations must be
performed in a fume hood.
(
100), 41 (60), 29 (65).
N-(2-Fluorobenzyl)-N-methylformamide (2i): The product was ob-
tained by column chromatography (pentane/EtOAc, 1:1) as a color-
Characterization of the formylation products
less oil in a yield of 58% (195 mg) as a mixture of rotamers in
1
Piperidine-1-carbaldehyde (2a): The product was obtained by
a ratio of around 3:2. H NMR (300 MHz, CDCl
): d=8.25 and 8.10
3
column chromatography (pentane/EtOAc, 1:1) as a colorless liquid
(s, 2H), 7.34–6.95 (m, 4H), 4.55 and 4.40 (s, 2H), 2.85 and 2.75 ppm
1
13
in a yield of 91% (51.0 mg). H NMR (300 MHz, CDCl ): d=7.83 (s,
(s, 3H); C NMR (75 MHz, CDCl ): d=162.4, 159.2, 131.1–128.3 (m),
3
3
1
H), 3.41–3.22 (m, 2H), 3.21–3.02 (m, 2H), 1.64–1.21 ppm (m, 6H);
124.7, 124.2, 124.2, 124.1, 124.1, 122.7, 122.5, 115.3 (dd, JC-F =32.2,
13
19
C NMR (75 MHz, CDCl ): d=160.6, 46.5, 40.2, 26.1, 24.6, 24.2 ppm;
21.5 Hz), 47.0, 46.9, 40.7, 40.7, 33.9, 29.0; F NMR (282 MHz, CDCl
3
):
d=À118.3, À118.6 ppm; MS (EI): m/z (%): 167 (100) [M] , 124 (43),
109 (82), 83 (22); HRMS (ESI): m/z calcd for C 11NOF: 168.08192
3
+
+
MS (EI): m/z (%): 113 (41) [M] , 98 (17), 84 (29), 70 (15), 56 (52), 42
(
48), 29 (100).
H
9
+
[M+H] ; found: 168.08189.
Pyrrolidine-1-carbaldehyde (2b): The product was obtained by
column chromatography (pentane/EtOAc, 1:1) as a colorless liquid
N-Ethyl-N-phenylformamide (2j): The product was obtained by
column chromatography (pentane/EtOAc, 4:1) as a light-yellow
liquid in a yield of 37% (111 mg) as a mixture of rotamers in ratio
1
in a yield of 71% (141 mg). H NMR (300 MHz, CDCl ): d=8.09 (s,
3
1
H), 3.40–3.30 (m, 2H), 3.28–3.17 (m, 2H), 1.83–1.66 ppm (m, 4H);
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1
of around 12:1. H NMR (300 MHz, CDCl ): d=8.38 (s, 1H), 7.48–
3.25–3.06 (m, 0.24H), 1.75–1.50 (m, 5H), 1.31–0.75 ppm (m, 9H);
C NMR (75 MHz, CDCl ): d=164.0 (minor), 160.6 (major), 53.0,
3
3
13
7
7
3
1
4
.39 (m, 2H), 7.36–7.28 (m, 1H), 7.23–7.13 (m, 2H), 3.89 (q, J=
.2 Hz, 1.85H), 3.75 (q, J=7.2 Hz, 0.15H), 1.18 ppm (t, J=7.2 Hz,
H); C NMR (75 MHz, CDCl ): d=162.08 (minor), 162.01 (major),
38.29, 129.64, 129.25, 126.86, 126.09, 124.99, 124.24, 124.23,
4.94, 40.08, 15.04, 13.07 ppm; MS (EI): m/z (%): 149 (27) [M] , 121
48.0, 43.5, 42.6, 29.3, 28.8, 28.7, 28.2, 26.1, 26.1, 26.0, 25.9, 25.9,
1
3
+
25.8, 25.8, 19.1, 17.6 ppm; MS (EI): m/z (%): 155 (1) [M] , 140 (13),
3
110 (13), 72 (95), 55 (31), 44 (100), 29 (42).
+
N,N’-(Pentane-1,5-diyl)diformamide (2q): The product was ob-
tained by column chromatography (acetone) as a colorless crystal-
(
17), 106 (100), 93 (21), 77 (68), 65 (23), 51 (35), 39 (28), 29 (79).
N-[2-(4-Formylpiperazin-1-yl)ethyl]formamide (2k): The product
line solid in a yield of 85% (269 mg) as a mixture of rotamers in
1
was obtained by column chromatography (EtOH) as a white solid
a ratio of 7:1. H NMR (300 MHz, CDCl ): d=7.97 (d, J=2.0 Hz,
3
1
in a yield of 73% (272 mg). H NMR (300 MHz, [D ]DMSO): d=8.0
1.74H), 7.87 (d, J=11.9 Hz, 0.26H), 7.28 (s, 1.7H), 7.14–7.00 (m,
6
(
6
s, 1H), 7.98 (s, 1H), 7.97 (s, 1H), 3.42–3.28 (m, 4H), 3.20 (q, J=
0.3H), 3.19–2.97 (m, 4H), 1.51–1.32 (m, 4H), 1.30–1.13 ppm (m,
1
3
13
.4 Hz, 2H), 2.44–2.26 ppm (m, 6H); C NMR (75 MHz, [D ]DMSO):
2H); C NMR (75 MHz, CDCl ): d=164.7 (minor), 161.5 (major),
6
3
d=165.3, 161.7, 161.7, 161.3, 161.2, 59.0, 57.2, 53.8, 53.7, 52.5, 45.3,
41.3, 37.4, 37.3, 30.1, 28.4, 28.3, 23.5, 23.1 ppm; MS (EI): m/z (%):
158 (1) [M] , 127 (1), 113 (13), 100 (13), 87 (16), 73 (18), 59 (34), 58
+
+
3
9.8, 35.1 ppm; MS (EI): m/z (%): 185 (1) [M] , 140 (4), 127 (100), 98
(
17), 99 (17), 70 (35), 56 (48), 42 (51), 29 ppm (57); HRMS (ESI): m/z
(68), 30 (100), 29 (50).
+
calcd for C H N O : 186.12370 [M+H] ; found: 186.12383.
8
16
3
2
N-Nonylformamide (2r): The product was obtained by column
N-(4-Chlorobenzyl)formamide (2l): The product was obtained by
column chromatography (pentane/EtOAc, 1:2) as a white solid in
chromatography (pentane/EtOAc, 2:1) as a colorless oil in a yield
of 97% (333 mg) as a mixture of rotamers in a ratio of 4:1. H NMR
1
a yield of 72% (245 mg) as a mixture of rotamers in a ratio of
(300 MHz, CDCl ): d=8.09 (d, J=1.9 Hz, 0.8H), 7.97 (d, J=12.0 Hz,
3
1
around 9:1. H NMR (300 MHz, [D ]DMSO): d=8.56 (s, 1H), 8.17 (d,
0.2H), 6.21 (s, 1H), 3.32–2.98 (m, 2H), 1.47 (t, J=7.1 Hz, 2H), 1.33–
6
13
J=1.7 Hz, 1H), 7.37 (d, J=8.4 Hz, 2H), 7.29 (d, J=8.5 Hz, 2H),
1.13 (m, 12H), 0.88–0.77 ppm (m, 3H); C NMR (75 MHz, CDCl3):
1
3
4
1
1
.31 ppm (d, J=6.2 Hz, 2H); C NMR (75 MHz, [D ]DMSO): d=
d=164.6 (major), 161.3 (minor), 41.7, 38.1, 31.7, 29.4, 29.1, 29.1,
6
+
65.5 (minor), 161.7 (major), 138.6, 132.0, 129.7, 129.6, 129.4, 128.9,
28.8, 44.4 (minor), 40.7 ppm (major).
26.7, 22.5, 14.0 ppm; MS (EI): m/z (%): 171 (1) [M] , 142 (5), 128 (7),
100 (23), 72 (21), 58 (82), 41 (84), 30 (100), 29 (64). HRMS (ESI): m/z
+
calcd for C H NONa: 194.15154 [M+Na] ; found: 194.15148.
10
21
N-Phenethylformamide (2m): The product was obtained by
column chromatography (EtOAc) as a thick oil in a yield of 92%
N-Formylgeranylamine (2s): The product was obtained by column
1
(
(
275 mg) as a mixture of rotamers in a ratio of around 5:1. H NMR
chromatography (pentane/EtOAc, 3:1) as a colorless oil in a yield
1
300 MHz, CDCl ): d=8.09 (d, J=1.8 Hz, 0.81H), 7.84 (d, J=11.9 Hz,
of 84% (305 mg) as a mixture of rotamers in a ratio of 9:1. H NMR
3
0
1
.14H), 7.40–7.17 (m, 5H), 6.46–6.00 (m, 1H), 3.56 (q, J=6.6,
.68H), 3.47 (q, J=6.7 Hz, 0.31H), 2.86 ppm (t, J=7.1 Hz, 2H);
(300 MHz, CDCl ): d=7.99 (s, 0.9H), 7.91 (d, J=12.0 Hz, 0.1H), 6.76
(s, 0.9H), 6.32 (s, 0.1H), 5.12–5.01 (m, 1H), 5.01–4.88 (m, 1H), 3.72
3
13
C NMR (75 MHz, CDCl ): d=164.5 (minor), 161.2 (major), 138.4,
(t, J=8.1 Hz, 2H), 2.02–1.81 (m, 4H), 1.61–1.50 (m, 6H), 1.47 ppm
3
13
1
4
37.5, 128.7, 128.6, 128.6, 128.5, 128.5, 128.4, 128.4, 126.7, 126.4,
(d, J=1.6 Hz, 3H); C NMR (75 MHz, CDCl ) d=164.4 (minor), 161.0
3
+
3.0, 39.1, 37.5, 35.3, 35.3 ppm; MS (EI): m/z (%): 149 (7) [M] , 104
(major), 139.4, 131.3, 123.5, 123.3, 119.9, 119.3, 119.2, 39.1, 35.7,
31.6, 26.1, 26.0, 25.9, 25.3, 25.3, 25.3, 23.0, 17.3, 15.9 ppm; MS (EI):
(
100), 91 (36), 58 (18); HRMS (ESI): m/z calcd for C H NO:
9 11
+
+
1
49.08352[M] ; found: 149.08374.
m/z (%): 181 (1) [M] , 136 (21), 69 (51), 41 (100), 29 (22); HRMS
+
(
ESI): m/z calcd for C H NO: 182.15394 [M+H] ; found: 182.15411.
11
20
N-Formyl-1-adamantylmethylamine (2n): The product was ob-
tained by column chromatography (pentane/EtOAc, 1:1) as a white
N-(2-Pyridylmethyl)formamide (2t): The product was obtained by
solid in a yield of 75% (291 mg) as a mixture of rotamers in a ratio
column chromatography (EtOAc/EtOH, 6:1) as a colorless thick oil
1
1
of 7:2. H NMR (300 MHz, CDCl ): d=8.06 (d, J=2.2 Hz, 0.77H), 7.77
in a yield of 86% (234 mg). H NMR (300 MHz, CDCl ): d=8.27 (dd,
3
3
(
d, J=11.9 Hz, 0.22H), 7.01–6.71 (m, 1H), 2.81 (d, J=6.5 Hz, 1.56H),
J=5.0, 2.2 Hz, 1H), 8.08 (d, J=2.2 Hz, 1H), 7.87 (s, 1H), 7.53–7.36
2
1
5
.67 (d, J=6.8 Hz, 0.44H), 1.88–1.75 (m, 3H), 1.64–1.42 (m, 6H),
(m, 1H), 7.07 (d, J=7.9 Hz, 1H), 7.03–6.89 (m, 1H), 4.36 ppm (d, J=
1
3
13
.42–1.20 ppm (m, 6H); C NMR (75 MHz, CDCl ): d=165.3, 161.6,
5.6 Hz, 2H); C NMR (75 MHz, CDCl ): d=165.2, 161.2, 156.1, 148.4,
3
3
+
3.8, 49.2, 39.7, 39.4, 36.5, 36.4, 33.2, 33.1, 27.8, 27.7 ppm; HRMS
136.4, 121.9, 121.4, 46.7, 42.7 ppm; MS (EI): m/z (%): 136 (6) [M] ,
+
(
ESI): m/z calcd for C H NO: 194.15394 [M+H] ; found:
107 (100), 93 (43), 92 (38), 80 (52), 79 (57), 63 (21), 52 (70), 51 (60),
129 (100).
1
2
20
1
94.15406.
(S)-N-(1-Phenylethyl)formamide (2o): The product was obtained
N-(1-Adamantyl)formamide (2u): The product was obtained by
by column chromatography (acetone) as a colorless oil in a yield of
column chromatography (pentane/EtOAc, 1:1) as a white solid in
22
9
0% (268 mg) as a mixture of rotamers in a ratio of 4:1. [a] =
a yield of 34% (73 mg) as a mixture of rotamers in a ratio of 7:3.
D
2
4
1
À201.3 (c=1, EtOH) {lit.: [a] =À190 (c=1, EtOH), see ref. [10] in
H NMR (300 MHz, CDCl ): d=8.15 (d, J=12.3 Hz, 0.7H), 7.91 (d, J=
D
3
1
the Supporting Information}; H NMR (300 MHz, CDCl ): d=8.10 (d,
2.1 Hz, 0.3H), 7.09 (s, 0.7H), 5.81 (s, 0.3H), 2.07–1.88 (m, 5H), 1.82–
3
13
J=12.0 Hz, 0.18H), 8.06 (d, J=1.9, 0.82H), 7.43–7.22 (m, 5H), 7.13–
1.68 (m, 4H), 1.67–1.49 ppm (m, 6H); C NMR (75 MHz, CDCl ): d=
3
6
6
.87 (m, 1H), 5.24–5.07 (m, 1H), 4.74–4.58 (m, 0.86H), 1.56 (d, J=
.9 Hz, 0.14H), 1.48 ppm (d, J=7.0 Hz, 3H); C NMR (75 MHz,
162.3, 160.2, 51.6, 50.3, 43.7, 41.4, 36.0, 35.6, 29.1, 29.0 ppm; HRMS
1
3
+
(ESI): m/z calcd for C H NO: 179.13047 [M] ; found: 179.13066.
11
17
CDCl ): d=164.2 (minor), 160.5 (major), 142.6, 128.6, 128.4, 127.4,
3
N-{[1-(Thieno[3,2-d]pyrimidin-4-yl)piperidin-4-yl]methyl}formam-
ide (2v): The reaction was performed using 1t
127 mg, 0.511 mmol) and the resulting product was obtained by
1
27.1, 125.9, 125.6, 124.7, 51.6, 47.3, 23.3, 21.7 ppm; MS (EI): m/z
+
(
(
%): 149 (66) [M] , 148 (57), 134 (54), 106 (80), 79 (87), 77 (100), 51
67), 42 (49), 29 (7).
(
column chromatography (EtOAc/EtOH, 2:1) as a brown solid in
1
N-(1-Cyclohexylethyl)formamide (2p): The product was obtained
a yield of 61% (86 mg). H NMR (300 MHz, CDCl ): d=8.48 (d, J=
3
by column chromatography (pentane/EtOAc, 2:1) as a colorless oil
5.3 Hz, 1H), 8.14 (d, J=2.0 Hz, 1H), 7.95 (d, J=11.8 Hz, 0.8H), 7.66
(dd, J=5.6, 4.5 Hz, 0.2H), 7.32 (dd, J=5.6, 4.6 Hz, 1H), 6.77 and
6.63 (s, 1H), 4.87–4.66 (m, 2H), 3.17 (t, J=6.3 Hz, 2H), 3.11–2.94 (m,
in a yield of 87% (271 mg) as a mixture of rotamers in a ratio of
1
7
7
:2. H NMR (300 MHz, CDCl ): d=8.04 (dd, J=2.1, 1.1 Hz, 0.72H),
3
13
.91 (d, J=11.9 Hz, 0.23H), 6.48–6.12 (m, 1H), 3.91–3.68 (m, 0.76H),
2H), 1.91–1.70 (m, 3H), 1.38–1.12 ppm (m, 2H); C NMR (75 MHz,
Chem. Eur. J. 2015, 21, 14943 – 14948
www.chemeurj.org
14947 ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
CDCl ): d=164.8, 161.5, 160.9, 157.6, 154.0, 131.4, 131.3, 124.8,
Jang, Synlett 2010, 1231; e) L. A. Shastri, S. L. Shastri, C. D. Bathula, M.
Basanagouda, M. V. Kulkarni, Synth. Commun. 2011, 41, 476; f) S. Joseph,
P. Das, B. Srivastava, H. Nizar, M. Prasad, Tetrahedron Lett. 2013, 54, 929;
g) Z.-G. Wang, M. Lu, RSC Adv. 2014, 4, 1234.
3
1
14.1, 47.1, 46.0, 46.0, 43.2, 37.7, 36.3, 29.8, 29.4 ppm; MS (EI): m/z
+
(
%): 276 (34) [M] , 218 (39), 190 (38), 176 (31). 164 (56), 152 (29),
1
2
35 (100), 109 (52), 58 (51); HRMS (ESI): m/z calcd for C H N OS:
13 16 4
76.10393 [M] ; found: 276.10395.
+
[5] M. Mihara, Y. Ishino, S. Minakata, M. Komatsu, Synthesis 2003, 2317.
[
6] a) P. Ganapati Reddy, G. D. K. Kumar, S. Baskaran, Tetrahedron Lett. 2000,
41, 9149; b) S. H. Jung, J. H. Ahn, S. K. Park, J. K. Choi, Bull. Korean Chem.
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Shah, E. Gravel, D. V. Jawale, E. Doris, I. N. N. Namboothiri, ChemCatCh-
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N-Phenylformamide (2w): The reaction was performed using 1w
466 mg, 5 mmol) and the resulting product was obtained by
(
column chromatography (pentane/EtOAc, 2:1) as a white solid in
a yield of 12% (73 mg) as a mixture of rotamers in a ratio of 7:3.
1
H NMR (300 MHz, CDCl ): d=9.0 (s, 0.5H, NH), 8.7 (d, J=11.3 Hz,
3
[
0
.5H, COH), 8.4 (d, J=1.9 Hz, 0.5H, COH), 8.0 (s, 0.5H, NH), 7.6–7.5
1
3
(
m, 1H), 7.4–7.3 (m, 2H), 7.2–7.1 ppm (m, 2H); C NMR (75 MHz,
CDCl ): d=163.0, 159.3, 136.9, 136.7, 129.6, 129.6, 129.0, 125.2,
3
1
24.8, 124.7, 120.0, 118.7 ppm.
[
[
8] a) N. Ortega, C. Richter, F. Glorius, Org. Lett. 2013, 15, 1776; b) S. Tanaka,
T. Minato, E. Ito, M. Hara, Y. Kim, Y. Yamamoto, N. Asao, Chem. Eur. J.
N-(4-Methoxyphenyl)formamide (2x): The product was obtained
by column chromatography (pentane/EtOAc, 2:1) as a white solid
2013, 19, 11832.
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in a yield of 18% (55 mg) as a mixture of rotamers in a ratio of 5:4.
1
H NMR (300 MHz, CDCl ): d=8.7 and 8.1 (s, 1H; NH), 8.5 (d, J=
3
1
1.5 Hz) and 8.3 (d, J=2.0 Hz, 1H; COH), 7.5–7.4 (m, 1H), 7.1–6.9
13
(
(
m, 1H), 6.9–6.8 (m, 2H), 3.78 and 3.75 ppm (s, 3H); C NMR
75 MHz, CDCl ): d=163.3, 159.3, 157.4, 156.5, 130.0, 129.6, 121.8,
3
+
1
21.3, 114.7, 114.0, 55.3 ppm; MS (EI): m/z (%): 151 (49) [M] , 108
(
100), 80 (67), 52 (36), 29 (65).
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Acknowledgements
The authors thank the State of Mecklenburg-Vorpommern, the
Bundesministerium für Bildung und Forschung (BMBF), and the
Deutsche Forschungsgemeinschaft for financial support. We
also appreciate the general support of Prof. Matthias Beller of
LIKAT.
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base catalysis
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Published online on August 26, 2015
Chem. Eur. J. 2015, 21, 14943 – 14948
www.chemeurj.org
14948
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim