Copper-catalyzed amidation of acids using formamides as the amine source

Article abstract of DOI:10.1002/ejoc.201300543

Copper-catalyzed amidation of acids with formamides or acetamide for the selective synthesis of amides with the aid of 1,4-diazabicyclo[2.2.2]octane as the ligand and tert-butyl hydroperoxide as the oxidant is presented. This method is highly compatible with a wide range of acids, including alkyl acids, aryl acids, α,β-unsaturated acids, and amino acids. A general and direct route for the synthesis of amides is described. The reaction involves the copper-catalyzed amidation of acids, wherein various formamides and an acetamide are used as the amine source. Importantly, this method represents a new strategy for the direct use of acids in the synthesis of amides. DABCO = 1,4-diazabicyclo[2.2.2]octane, TBHP = tert-butyl hydroperoxide. Copyright

Full text of DOI:10.1002/ejoc.201300543

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FULL PAPER
Amidation
Y.-X. Xie, R.-J. Song,* X.-H. Yang,
J.-N. Xiang, J.-H. Li* ....................... 1–7
Copper-Catalyzed Amidation of Acids
Using Formamides as the Amine Source
A general and direct route for the synthesis
of amides is described. The reaction in-
volves the copper-catalyzed amidation of
acids, wherein various formamides and an
acetamide are used as the amine source.
Importantly, this method represents a new
strategy for the direct use of acids in the
synthesis of amides. DABCO = 1,4-diaza-
Keywords: Copper / Cross-coupling / Carb-
oxylic acids / Formamides / Amides
bicyclo[2.2.2]octane, TBHP
hydroperoxide.
= tert-butyl
0000, 0–0
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Job/Unit: O30543
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Y.-X. Xie, R.-J. Song, X.-H. Yang, J.-N. Xiang, J.-H. Li
FULL PAPER
DOI: 10.1002/ejoc.201300543
Copper-Catalyzed Amidation of Acids Using Formamides as the Amine Source
Ye-Xiang Xie,[a] Ren-Jie Song,*[a] Xu-Heng Yang,[a] Jian-Nan Xiang,[a] and Jin-Heng Li*[a]
Keywords: Copper / Cross-coupling / Carboxylic acids / Formamides / Amides
Copper-catalyzed amidation of acids with formamides or
acetamide for the selective synthesis of amides with the aid
of 1,4-diazabicyclo[2.2.2]octane as the ligand and tert-butyl
hydroperoxide as the oxidant is presented. This method is
highly compatible with a wide range of acids, including alkyl
acids, aryl acids, α,β-unsaturated acids, and amino acids.
formamides have not yet been explored.[8g] Therefore, the
development of conceptually novel versions of this strategy
for the synthesis of amides is highly desirable. To the best
of our knowledge, however, metal-catalyzed amidation of
an acid by using a formamide as an amine source has not
yet been established. Herein, we report the copper-catalyzed
amidation of acids with formamides or an acetamide for the
direct synthesis of amides, wherein 1,4-diazabicyclo[2.2.2]
octane (DABCO) is used as a ligand and TBHP is used as
the oxidant (Scheme 1). Notably, this reaction represents a
conceptually novel, simple, and powerful route to amides
by using two commercially available and cheap reaction
partners.
Introduction
Amides are a class of fundamental chemicals in organic
synthesis and in the chemical industry.[1] Popular methods
for the synthesis of amides include the reactions of acids
and their derivatives (acyl chlorides and anhydrides) with
amines[1,2] and the coupling of primary amides with organo-
halides.[3] However, many methods are restricted to labile
substrates and/or suffer from a limited substrate scope, in-
volve a multistep process resulting in large amounts of un-
wanted byproducts, or require otherwise harsh conditions
and high pressures aside the requirement of additional puri-
fication steps. Alternative methods for the synthesis of
amides have been developed, and they include well-estab-
lished named reactions (Ritter, Schmidt, Beckmann, Ugi,
and Wolff, etc.);[4] the aminocarbonylation of organohal-
ides, alkenes, or alkynes;[5] the carbamoylation of aryl hal-
ides with formamides and their derivatives (carbamoyl-
silanes, carbamoylstannanes, or carbamoyl chlorides);[6]
transamidation reactions;[7] and oxidative coupling reac-
tions with amines.[8] Among these, one strategy utilizes for-
mamides as the source of the amines.[2l–2o,8g] An effective
synthesis of N,N-dimethylamides from acid chlorides, es-
ters, or anhydrides in DMF was reported, but the reaction
was carried out at 150 °C possibly in the presence of a trace
amount of a mineral acid.[2l–2o] Although Wan and co-
workers recently described a new synthesis route to amides
that involves the Bu4NI-catalyzed oxidative cross-coupling
of aryl aldehydes with formamides by using tert-butyl hy-
droperoxide (TBHP) as the oxidant, some disadvantages
still remain: aliphatic aldehydes display lower reactivity for
the synthesis of aliphatic amides and N-monosubstituted
Scheme 1. Cu-catalyzed synthesis of amides.
Results and Discussion
We began our investigation with the reaction of 4-meth-
oxybenzoic acid (1a) with DMF (2a) under the reported
reaction conditions (20 mol-% Bu4NI and 6 equiv. TBHP in
ClCH2CHCl2 at 90 °C); however, no reaction was observed
(Table 1, entry 1). After a series of trials, we found that
CuCl2 combined with TBHP catalyzed the reaction: treat-
ment of acid 1a with 2a, CuCl2, and TBHP at 80 °C under
an argon atmosphere overnight afforded desired product
3aa in 52% yield (Table 1, entry 2). Gratifyingly, the yield
was enhanced to 67% in the presence of a DABCO ligand
(Table 1, entry 3). Encouraged by these results, ligands L2–
L4 were examined. Whereas N-containing ligands L2–L4
facilitated the reaction, PPh3 (L5), a phosphane ligand, in-
hibited the reaction (Table 1, entries 4–7). Subsequently, the
amounts of CuCl2 and ligand L1 were evaluated (Table 1,
entries 8 and 9). The results demonstrate that a loading of
5 mol-% CuCl2 and 10 mol-% L1 gave the best results in
[a] State Key Laboratory of Chemo/Biosensing and Chemometrics,
College of Chemistry and Chemical Engineering, Hunan
University,
Changsha 410082, China
E-mail: jhli@hnu.edu.cn
srj0731@hnu.edu.cn
Homepage: http://cc.hnu.cn/index.php?option=com_content&
task=view&id=1054&Itemid=228
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201300543.
2
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Cu-Catalyzed Amidation of Acids
terms of yield (Table 1, entry 8). A moderate yield was still benzoic acid with 2a, CuCl2, L1, and TBHP afforded corre-
achieved at a loading of 2 mol-% CuCl2 after prolonging sponding N,N-dimethylbenzamide 3ba in 72% yield. Pleas-
the reaction time (Table 1, entry 9). Among the oxidants ingly, a variety of substituents, including Me, MeO, vinyl,
examined, TBHP displayed a higher reactivity than meta- Br, F, and NO2, on the aryl ring of the acid were well toler-
chloroperoxybenzoic acid (mCPBA) and Oxone (Table 1, ated to afford products 3ca–ia; however, an o-Me substitu-
entries 10 and 11). Notably, the reaction did not take place ent (to give 3fa) or an electron-withdrawing F or NO2 sub-
in the absence of an oxidant (Table 1, entry 12). Screening stituent (to give 3ha or 3ia) resulted in a diminished yield.
revealed that the amount of TBHP affected the reaction Gratifyingly, aliphatic acids were also compatible with the
(Table 1, entries 8, 13, and 14): 3 equiv. TBHP offered a optimized conditions, and they furnished corresponding
yield identical to that obtained with 2 equiv. TBHP, but the amides 3ja–oa in good yields. By using heptanoic acid, for
yield dropped to 58% with 1.3 equiv. TBHP. Three other instance, the reaction with 2a provided desired amide 3ja in
Cu catalysts, Cu(OTf)2, Cu(OAc)2, and CuCl, were also 78% yield. Other fatty acids having an aryl or a vinyl group
tested. They catalyzed the reaction in the order Cu(OTf)2 Ͼ were also suitable for the reaction with 2a, CuCl2, L1, and
Cu(OAc)2, CuCl in terms of yield (Table 1, entries 15–17). TBHP to afford products 3ka–ma. More importantly, three
However, the presence of air hindered the reaction (Table 1, α-amino acids, 3-(tert-butoxycarbonylamino)-3-phenyl-
entry 18). Of note, the yield decreased if the reaction was propanoic acid, 1-(tert-butoxycarbonyl)pyrrolidine-2-carb-
performed at either 110 or 60 °C (Table 1, entries 19 and oxylic acid, and 1H-indole-2-carboxylic acid, were success-
20). Interestingly, a good yield was still obtained at a 1 g fully modified and offered amide products 3na–pa in good
scale of acid 1a (Table 1, entry 21).
yields. Notably, 1H-indole-2-carboxylic acid furnished a C–
N bond-forming product, N1,N1,N2,N2-tetramethyl-1H-in-
dole-1,2-dicarboxamide (3pa), in 53% yield. Interestingly,
both acrylic acids and propiolic acids displayed high reac-
tivity for the reaction to give products 3qa–ta.
Table 1. Screening optimal conditions.[a]
Table 2. Scope of acids 1.[a]
Entry [Pd] (equiv.) Ligand (equiv.) [O] (equiv.) Yield [%][h]
1[b]
2
3
4
5
6
7
8
–
–
–
TBHP (6)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
Oxone (2)
mCPBA (2)
–
0
CuCl2 (20)
CuCl2 (20)
CuCl2 (20)
CuCl2 (20)
CuCl2 (20)
CuCl2 (20)
CuCl2 (5)
CuCl2 (2)
CuCl2 (5)
CuCl2 (5)
CuCl2 (5)
CuCl2 (5)
CuCl2 (5)
Cu(OTf)2 (5) L1 (10)
Cu(OAc)2 (5) L1 (10)
CuCl (5)
CuCl2 (5)
CuCl2 (5)
CuCl2 (5)
CuCl2 (5)
52
67
53
62
60
22
77
55
trace
8
L1 (40)
L2 (40)
L3 (40)
L4 (40)
L5 (40)
L1 (10)
L1 (4)
L1 (10)
L1 (10)
L1 (10)
L1 (10)
L1 (10)
9[c]
10
11
12
13
14
15
16
17
18[d]
19[e]
20[f]
21[g]
0
78
TBHP (3)
TBHP (1.3) 58
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
70
64
66
36
72
38
80
L1 (10)
L1 (10)
L1 (10)
L1 (10)
L1 (10)
[a] Reaction conditions: 1a (0.3 mmol), DMF (2a, 4.5 mmol), [Cu],
ligand, and [O] in ClCH2CHCl2 (1 mL) under an argon atmosphere
at 80 °C overnight. TBHP = 70% in water. [b] nBu4NI (20 mol-%)
was added. [c] For 24 h. [d] Under an air atmosphere. [e] At 110 °C.
[f] At 60 °C. [g] 1a (1 g, 6.6 mmol) and DMF (66 mmol) in
ClCH2CHCl2 (3 mL). [h] Yield of isolated product.
[a] Reaction conditions:
1 (0.3 mmol), 2a (4.5 mmol), CuCl2
(5 mol-%), DABCO (10 mol-%), and TBHP (2 equiv., 70% in
water) in ClCH2CHCl2 (1 mL) at 80 °C under an argon atmosphere
overnight. [b] 1H-Indole-2-carboxylic acid (1p) as substrate.
With the optimized reaction conditions in hand, we next
set out to explore the scope of acids 1 in the presence of 2a
(Table 2). Aryl, aliphatic, vinyl, and alkynyl acids and α-
Subsequently, the scope of formamides 2 for the reaction
amino acids were viable substrates, and they were converted with 3-phenylpropiolic acid (1t), CuCl2, DABCO (L1), and
into N,N-dimethylamides in 50–93% yield. Treatment of TBHP was exploited, and the results are summarized in
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FULL PAPER
Table 3. Gratifyingly, N,N-dimethylacetamide (DMA) pro- was allowed to run overnight. Interestingly, 6% yield of
vided the N,N-dimethyl group to form N,N-dimethyl-3- N,N-dimethyl-4-nitrobenzamide (3ia) was still obtained
phenylpropiolamide (3ta), albeit in a lower yield (51%) than from the reaction of 4-nitrobenzoic acid (1i) with 4-meth-
that obtained with DMF. In light of this result, a variety of oxy-N,N-dimethylbenzamide (3aa). This suggests that the
N,N-disubstituted formamides were employed in the reac- present reaction may be reversible between the acids and
tion with 3-phenylpropiolic acid (1t) under the optimized amides.
conditions to form products 3tc–th. Screening disclosed
that formamides having an N,N-dialkyl group, such as N,N-
diethyl, N,N-di(isopropyl), 1-(piperidin-1-yl), and 1- Conclusions
morpholino groups, were consistent with the optimized
In summary, we have described a general and direct route
conditions. N-Methyl-N-phenylformamide was also a viable
for the synthesis of amides through the copper-catalyzed
substrate, and it furnished N-methyl-N,3-diphenylpropiol-
oxidative cross-coupling of acids with formamides or an
amide (3th) in moderate yield. Notably, N-arylpropiol-
acetamide. Importantly, this method uses formamides and
amides are an important class of compounds that are
an acetamide as the source of the amines for the amidation
widely used in a range of cyclization reactions.[9] We were
with acids. This method opens a new door for the use of
pleased to find that N-phenylformamide with a free N-H
acids in the direct synthesis of amides.
group was also compatible with the reaction conditions to
provide N,3-diphenylpropiolamide (3ti) in 50% yield.
Table 3. Scope of formamides 2.[a]
Experimental Section
General Methods: CH2ClCH2Cl was dried with CaH2 and freshly
distilled. The other materials and solvents were purchased from
commercial suppliers and used without additional purification.
NMR spectra were recorded with Bruker Avance spectrometers op-
erating at 500 MHz for 1H, and at 125 MHz for 13C by using TMS
as internal standard. Chemical shifts are given relative to CDCl3 (δ
1
= 7.26 ppm for H and δ = 77.0 ppm for 13C). Mass spectrometry
data of the products were collected with an HRMS-TOF instru-
ment or a low-resolution MS instrument by using EI ionization.
IR spectra were recorded with a Bruker ATR-FTIR spectrometer.
Melting points were measured with a WRS-1A digital point appa-
ratus.
Typical Experimental Procedure for the Cu-Catalyzed Synthesis of
Amides 3: Acid 1 (0.3 mmol), DMF (2, 4.5 mmol), CuCl2 (5 mol-
%), DABCO (10 mol-%), TBHP (2 equiv.), and ClCH2CHCl2
(1 mL) were added to a Schlenk tube. Then, the tube was filled
with argon, and the mixture was stirred at 80 °C (oil bath tempera-
ture) for the indicated time or until complete consumption of the
starting material as monitored by TLC and GC–MS analysis. Upon
completion of the reaction, the mixture was washed with brine.
The aqueous phase was extracted with ethyl acetate. The combined
organic extract was dried with Na2SO4 and concentrated in vacuo,
and the resulting residue was purified by silica gel column
chromatography (hexane/ethyl acetate = 1:1) to afford desired
product 3.
[a] Reaction conditions: 1t (0.3 mmol), 2 (4.5 mmol), CuCl2 (5 mol-
%), DABCO (10 mol-%), and TBHP (2 equiv., 70% in water) in
ClCH2CHCl2 (1 mL) at 80 °C under an argon atmosphere over-
night.
As shown in Scheme 2, other substrates were investi-
gated. In the presence of CuCl2, DABCO (L1), and TBHP,
4-methoxybenzaldehyde (4) reacted with 2a, albeit in low
yield [Scheme 2, Equation (1)].[8,10] The low yield could re-
sult from the oxidation of 4 to 4-methoxybenzoic acid (1a),
and the reaction of 1a with 2a resulted in the amide. How-
ever, the conversion rate of 4 is slow under the optimized
conditions, and Ͼ60% of 4 was recovered after the reaction
4-Methoxy-N,N-dimethylbenzamide (3aa):[6n] Colorless oil. 1H
NMR (500 MHz, CDCl3): δ = 7.36 (d, J = 9.5 Hz, 2 H), 6.86 (d,
J = 9.5 Hz, 2 H), 3.79 (s, 3 H), 3.02 (br. s, 6 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 171.4, 160.5, 129.0, 128.3, 113.4, 55.2, 39.7,
35.4 ppm. IR (KBr): ν = 1610, 1575 cm–1. LRMS (EI, 70 eV): m/z
˜
(%) = 179 (21) [M]+, 178 (27), 135 (100).
N,N-Dimethylbenzamide (3ba):[6n] White solid, m.p. 40.1–41.2 °C
(uncorrected). 1H NMR (500 MHz, CDCl3): δ = 7.41–7.39 (m, 5
H), 3.12 (s, 3 H), 2.98 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 171.6, 136.2, 129.5, 128.3, 127.0, 39.5, 35.3 ppm. IR (KBr): ν
˜
= 1631, 1578 cm–1. LRMS (EI, 70 eV): m/z (%) = 149 (23) [M]+,
148 (49), 105 (100).
N,N,4-Trimethylbenzamide (3ca):[6n] Colorless oil. 1H NMR
(500 MHz, CDCl3): δ = 7.32 (d, J = 8.0 Hz, 2 H), 7.19 (d, J =
8.0 Hz, 2 H), 3.10 (s, 3 H), 2.99 (s, 3 H), 2.37 (s, 3 H) ppm. 13C
Scheme 2. Copper-catalyzed coupling of other substrates.
4
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Cu-Catalyzed Amidation of Acids
NMR (125 MHz, CDCl3): δ = 171.7, 139.5, 133.2, 128.8, 127.1,
6.78 (m, 3 H), 3.79 (s, 3 H), 3.69 (s, 3 H), 2.99 (s, 3 H), 2.96 (s, 3
39.6, 35.3, 21.3 ppm. IR (KBr): ν = 1632, 1598 cm–1. LRMS (EI,
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 170.9, 159.7, 136.4,
˜
70 eV): m/z (%) = 163 (29) [M]+, 162 (28), 148 (9), 119 (100).
129.5, 121.0, 114.2, 112.2, 55.1, 41.0, 37.6, 35.5 ppm. IR (KBr): ν
˜
= 1633, 1578 cm–1. LRMS (EI, 70 eV): m/z (%) = 193 (89) [M]+,
148 (13), 121 (33), 72 (100). HRMS (EI): calcd. for C11H15NO2
[M]+ 193.1103; found 193.1100.
3,5-Dimethoxy-N,N-dimethylbenzamide (3da):[11] Colorless oil. 1H
NMR (500 MHz, CDCl3): δ = 6.53 (s, 1 H), 6.52 (s, 1 H), 6.48 (s,
1 H), 3.80 (s, 6 H), 3.10 (s, 3 H), 2.98 (s, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 171.2, 160.6, 138.1, 104.7, 101.4, 55.3, 39.7,
(E)-N,N-Dimethyl-4-phenylbut-3-enamide (3ma):[6a] Colorless oil.
1H NMR (500 MHz, CDCl3): δ = 7.36 (d, J = 8.0 Hz, 2 H), 7.29
(t, J = 4.0 Hz, 2 H), 7.20 (t, J = 7.5 Hz, 1 H), 6.45 (d, J = 16.0 Hz,
1 H), 6.37–6.31 (m, 1 H), 3.26 (d, J = 6.5 Hz, 2 H), 3.00 (s, 3 H),
2.94 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 170.7, 136.7,
35.1 ppm. IR (KBr): ν = 1642, 1588 cm–1. LRMS (EI, 70 eV): m/z
˜
(%) = 209 (21) [M]+, 165 (100).
N,N-Dimethyl-4-vinylbenzamide (3ea):[12] White solid, m.p. 48.8–
1
49.9 °C (uncorrected). H NMR (500 MHz, CDCl3): δ = 7.43 (t, J
132.3, 128.2, 127.1, 125.9, 122.9, 37.7, 37.2, 35.2 ppm. IR (KBr): ν
˜
= 7.0 Hz, 2 H), 7.39 (d, J = 8.0 Hz, 2 H), 6.75–6.69 (m, 1 H), 5.80
(d, J = 17.5 Hz, 1 H), 5.31 (d, J = 10.5 Hz, 1 H), 3.11 (s, 3 H),
2.99 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 171.3, 138.7,
= 1637, 1598 cm–1. LRMS (EI, 70 eV): m/z (%) = 190 (3) [M +
1]+, 189 (21) [M]+, 115 (14), 72 (100).
136.0, 135.4, 127.4, 126.0, 115.1, 39.5, 35.3 ppm. IR (KBr): ν =
˜
tert-Butyl 3-(Dimethylamino)-3-oxo-1-phenylpropylcarbamate (3na):
Colorless oil. 1H NMR (500 MHz, CDCl3): δ = 7.29–7.25 (m, 2
H), 7.24–7.18 (m, 3 H), 5.57 (br. s, 1 H), 4.85–4.80 (m, 1 H), 2.96–
2.94 (m, 2 H), 2.85 (s, 3 H), 2.63 (m, 3 H), 1.41 (s, 9 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = –171.7, 155.1, 136.4, 129.3, 128.2,
1653, 1616, 1559 cm–1. LRMS (EI, 70 eV): m/z (%) = 175 (29)
[M]+, 174 (25), 132 (12), 131 (100).
N,N,2-Trimethyl-1-naphthamide (3fa):[13] Colorless oil. 1H NMR
(500 MHz, CDCl3): δ = 8.08 (d, J = 8.5 Hz, 1 H), 7.84 (t, J =
9.0 Hz, 2 H), 7.56–7.53 (m, 1 H), 7.48–7.45 (m, 1 H), 7.34 (d, J =
8.5 Hz, 1 H), 3.09 (s, 3 H), 3.03 (s, 3 H), 2.63 (s, 3 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 165.5, 134.6, 131.6, 130.6, 130.1,
128.4, 128.1, 127.9, 127.5, 125.7, 124.3, 37.1, 36.9, 20.2 ppm. IR
126.7, 79.5, 51.3, 40.0, 36.7, 35.4, 28.2 ppm. IR (KBr): ν = 1672,
˜
1663 cm–1. LRMS (EI, 70 eV): m/z (%) = 292 (1) [M]+, 236 (6), 220
(26), 164 (32), 120 (60), 57 (100). HRMS (EI): calcd. for
C16H24N2O3 [M]+ 292.1787; found 292.1782.
(KBr): ν = 1643, 1608 cm–1. LRMS (EI, 70 eV): m/z (%) = 213 (40)
˜
tert-Butyl 2-(Dimethylcarbamoyl)pyrrolidine-1-carboxylate (3oa):
Colorless oil. 1H NMR (500 MHz, CDCl3): δ = 4.70–4.66 (m, 1
H), 3.61–3.54 (m, 1 H), 3.47–3.40 (m, 1 H), 3.10, 3.08 (s, 3 H),
2.98, 2.96 (s, 3 H), 2.21–2.13 (m, 1 H), 2.06–2.00 (m, 1 H), 2.00–
1.82 (m, 2 H), 1.46 (s, 6 H), 1.40 (s, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 172.6, 172.2, 154.3, 153.6, 79.2, 79.1, 56.2,
56.1, 46.5, 46.3, 36.7, 36.6, 35.7, 35.6, 30.0, 29.2, 28.2, 28.0, 23.9,
[M]+, 212 (40), 184 (25), 129 (100).
4-Bromo-N,N-dimethylbenzamide (3ga):[14] White solid, m.p. 76.8–
77.9 °C (uncorrected). 1H NMR (500 MHz, CDCl3): δ = 7.54 (d, J
= 8.5 Hz, 2 H), 7.29 (d, J = 8.5 Hz, 2 H), 3.10 (s, 3 H), 2.97 (s, 3
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 170.5, 134.9, 131.5,
128.7, 123.8, 39.5, 35.3 ppm. IR (KBr): ν = 1622, 1598 cm–1.
˜
23.4 ppm. IR (KBr): ν = 1668, 1612 cm–1. LRMS (EI, 70 eV): m/z
LRMS (EI, 70 eV): m/z (%) = 229 (19) [M + 2]+, 228 (55) [M +
˜
(%) = 242 (1) [M]+, 170 (58), 114 (92), 70 (100). HRMS (EI): calcd.
for C12H22N2O3 [M]+ 242.1630; found 242.1625.
1]+, 227 (21) [M]+, 185 (98), 183 (100).
2,3,4,5,6-Pentafluoro-N,N-dimethylbenzamide (3ha): Colorless oil.
1H NMR (500 MHz, CDCl3): δ = 3.16 (s, 3 H), 2.99 (s, 3 H) ppm.
13C NMR (125 MHz, CDCl3): δ = 158.5, 143.8, 141.8, 140.8, 138.7,
N1,N1,N2,N2-Tetramethyl-1H-indole-1,2-dicarboxamide (3pa): Col-
1
orless oil. H NMR (500 MHz, CDCl3): δ = 7.63 (d, J = 7.5 Hz, 1
136.6, 111.4, 37.8, 35.0 ppm. IR (KBr): ν = 1638, 1603 cm–1.
˜
H), 7.34 (t, J = 7.5 Hz, 1 H), 7.29 (d, J = 8.5 Hz, 1 H), 7.20 (t, J
= 7.5 Hz, 1 H), 6.76 (s, 1 H), 3.32 (s, 3 H), 3.11 (s, 9 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 163.2, 154.0, 135.3, 132.3, 127.0,
124.9, 122.1, 121.7, 111.2, 107.6, 39.4, 37.7, 37.4, 35.5 ppm. IR
LRMS (EI, 70 eV): m/z (%) = 239 (6) [M]+, 195 (100). HRMS (EI):
calcd. for C9H6F5NO [M]+ 239.0370; found 239.0366.
N,N-Dimethyl-4-nitrobenzamide (3ia):[6n] White solid, m.p. 99.2–
1
(KBr): ν = 1665, 1634 cm–1. LRMS (EI, 70 eV): m/z (%) = 259 (55)
˜
101.3 °C (uncorrected). H NMR (500 MHz, CDCl3): δ = 8.28 (d,
[M]+, 258 (20), 215 (8), 89 (16), 72 (100). HRMS (EI): calcd. for
C14H17N3O2 [M]+ 259.1321; found 259.1318.
J = 8.5 Hz, 2 H), 7.60 (d, J = 7.5 Hz, 1 H), 3.15 (s, 3 H), 2.97 (s,
3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 169.3, 148.2, 142.4,
128.0, 123.8, 39.3, 35.4 ppm. IR (KBr): ν = 1637, 1598 cm–1.
N,N-Dimethylcinnamamide (3qa):[17] Yellow oil. 1H NMR
(500 MHz, CDCl3): δ = 7.67 (d, J = 15.0 Hz, 1 H), 7.53 (d, J =
7.0 Hz, 2 H), 7.39–7.34 (m, 3 H), 6.90 (d, J = 15.5 Hz, 1 H), 3.17
(s, 3 H), 3.07 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
166.6, 142.3, 135.2, 129.5, 128.7, 127.7, 117.3, 37.3, 35.9 ppm. IR
˜
LRMS (EI, 70 eV): m/z (%) = 194 (2) [M]+, 193 (12), 165 (25), 135
(100).
N,N-Dimethylheptanamide (3ja):[15] Colorless oil. 1H NMR
(500 MHz, CDCl3): δ = 2.95 (s, 3 H), 2.86 (s, 3 H), 2.24 (t, J =
7.5 Hz, 2 H), 1.56–1.53 (m, 2 H), 1.26–1.23 (m, 6 H), 0.81 (t, J =
6.5 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 162.4, 38.2,
(KBr): ν = 1629 cm–1. LRMS (EI, 70 eV): m/z (%) = = 175 (12)
˜
[M]+, 131 (100).
(E)-N,N-Dimethyloct-2-enamide (3ra):[18] Colorless oil. 1H NMR
(500 MHz, CDCl3): δ = 6.90–6.84 (m, 1 H), 6.24 (d, J = 15.0 Hz,
2 H), 3.07 (s, 3 H), 3.00 (s, 3 H), 2.22–2.18 (m, 2 H), 1.49–1.43 (m,
2 H), 1.32–1.26 (m, 4 H), 0.89 (t, J = 7.0 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 166.9, 146.3, 120.0, 37.2, 35.6, 32.4, 31.3,
37.0, 36.2, 35.0, 33.1, 28.8, 22.2, 13.7 ppm. IR (KBr): ν =
˜
1667 cm–1. LRMS (EI, 70 eV): m/z (%) = 157 (4) [M]+, 128 (2), 100
(20), 87 (100).
N,N-Dimethyl-3-phenylpropanamide (3ka):[16] Colorless oil. 1H
NMR (500 MHz, CDCl3): δ = 7.28–7.22 (m, 2 H), 7.21–7.16 (m, 2
H), 2.94 (t, J = 8.0 Hz, 2 H), 2.92 (s, 3 H), 2.89 (s, 3 H), 2.60 (t, J
= 8.0 Hz, 2 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 172.0,
28.0, 22.4, 13.9 ppm. IR (KBr): ν = 1633 cm–1. LRMS (EI, 70 eV):
˜
m/z (%) = 169 (28) [M]+, 125 (100).
141.0, 128.1, 128.0, 125.7, 36.8, 35.0, 34.8, 31.0 ppm. IR (KBr): ν
˜
N,N-Dimethyloct-2-ynamide (3sa):[19] Yellow oil. 1H NMR
(500 MHz, CDCl3): δ = 3.21 (s, 3 H), 2.97 (s, 3 H), 2.36 (t, J =
7.0 Hz, 2 H), 1.60–1.57 (m, 2 H), 1.41–1.31 (m, 4 H), 0.91 (t, J =
7.0 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 154.6, 92.9,
= 1658 cm–1. LRMS (EI, 70 eV): m/z (%) = 177 (100) [M]+, 131
(9), 91 (55).
2-(3-Methoxyphenyl)-N,N-dimethylacetamide (3la): Colorless oil.
1H NMR (500 MHz, CDCl3): δ = 7.23 (d, J = 8.0 Hz, 1 H), 6.84–
73.7, 38.0, 33.7, 30.7, 27.2, 21.8, 18.6, 13.6 ppm. IR (KBr): ν =
˜
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5

Job/Unit: O30543
/KAP1
Date: 22-07-13 12:27:43
Pages: 7
Y.-X. Xie, R.-J. Song, X.-H. Yang, J.-N. Xiang, J.-H. Li
FULL PAPER
1630 cm–1. LRMS (EI, 70 eV): m/z (%) = 167 (10) [M]+, 123 (76),
1
3ta and 3ta-D6: H NMR (500 MHz, CDCl3): δ = 7.55–7.54 (m, 2
H), 7.43–7.40 (m, 1 H), 7.37–7.34 (m, 2 H), 3.29 (s, 2.43 H), 3.03
(s, 2.45 H) ppm.
110 (100).
N,N-Dimethyl-3-phenylpropiolamide (3ta):[6b] Colorless oil. 1H
NMR (500 MHz, CDCl3): δ = 7.52 (d, J = 8.5 Hz, 2 H), 7.39 (t, J
= 7.5 Hz, 1 H), 7.36 (t, J = 7.5 Hz, 2 H), 3.27 (s, 3 H), 3.00 (s, 3
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 154.5, 132.2, 129.9,
Supporting Information (see footnote on the first page of this arti-
cle): H NMR and 13C NMR spectra for amide products 3.
1
128.4, 120.5, 90.0, 81.5, 38.3, 34.1 ppm. IR (KBr): ν = 1626 cm–1.
˜
LRMS (EI, 70 eV): m/z (%) = 173 (7) [M]+, 172 (18), 129 (100).
Acknowledgments
N,N-Diethyl-3-phenylpropiolamide (3tc):[20] Colorless oil. H NMR
1
The authors thank the Specialized Research Fund for the Doctoral
Program of Higher Education (grant number 20120161110041),
National Natural Science Foundation of China (NSFC) (grant
numbers 13JJ2018 and 21172060), and Fundamental Research
Funds for the Central Universities (Hunan University, grant
number 2011-015) for financial support. R.-J. S. also thanks the
China Postdoctoral Science Foundation (grant number
2012M511716).
(500 MHz, CDCl3): δ = 7.53 (t, J = 6.5 Hz, 2 H), 7.43–7.40 (m, 1
H), 7.36 (t, J = 7.5 Hz, 2 H), 3.69–3.65 (m, 2 H), 3.50–3.46 (m, 2
H), 1.28 (t, J = 7.5 Hz, 3 H), 1.18 (t, J = 7.5 Hz, 3 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 153.9, 132.2, 129.8, 128.4, 120.6,
88.9, 81.8, 43.5, 39.2, 14.3, 12.8 ppm. IR (KBr): ν = 1672 cm–1.
˜
LRMS (EI, 70 eV): m/z (%) = 201 (26) [M]+, 200 (40), 172 (58),
129 (100).
N,N-Diisopropyl-3-phenylpropiolamide (3td): Colorless oil. 1H
NMR (500 MHz, CDCl3): δ = 7.54–7.52 (m, 2 H), 7.41–7.33 (m, 3
H), 4.60 (t, J = 6.5 Hz, 1 H), 3.72 (s, 1 H), 1.41 (t, J = 7.0 Hz, 6
H), 1.31 (t, J = 7.0 Hz, 6 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 153.5, 132.1, 129.6, 128.3, 121.0, 88.3, 83.1, 50.2, 45.6, 21.0,
[1] a) J. M. Humphrey, A. R. Chamberlin, Chem. Rev. 1997, 97,
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2010, 66, 8968.
20.0 ppm. IR (KBr): ν = 1678 cm–1. LRMS (EI, 70 eV): m/z (%) =
˜
229 (28) [M]+, 228 (42), 214 (41), 186 (62), 129 (100). HRMS (EI):
calcd. for C15H19NO [M]+ 229.1466; found 229.1463.
3-Phenyl-1-(piperidin-1-yl)prop-2-yn-1-one (3te):[21] Yellow oil. 1H
NMR (500 MHz, CDCl3): δ = 7.55–7.54 (m, 2 H), 7.41–7.39 (m, 1
H), 7.37–7.34 (m, 2 H), 3.78 (t, J = 5.0 Hz, 2 H), 3.63 (t, J =
6.0 Hz, 2 H), 1.70–1.65 (m, 4 H), 1.61–1.58 (m, 2 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 153.0, 132.3, 129.8, 128.5, 120.8,
90.2, 81.5, 48.2, 42.4, 26.5, 25.4, 24.6 ppm. IR (KBr): ν =
˜
1663 cm–1. LRMS (EI, 70 eV): m/z (%) = 213 (36) [M]+, 212 (36),
184 (23), 129 (100).
1-Morpholino-3-phenylprop-2-yn-1-one (3tf):[20] Yellow oil. 1H
NMR (500 MHz, CDCl3): δ = 7.55–7.53 (m, 2 H), 7.44–7.41 (m, 1
H), 7.38–7.35 (m, 2 H), 3.84 (t, J = 5.0 Hz, 2 H), 3.75 (t, J =
5.0 Hz, 2 H), 3.70 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ
= 153.2, 132.3, 130.1, 128.5, 120.2, 91.1, 80.7, 66.8, 66.4, 47.3,
41.9 ppm. IR (KBr): ν = 1668 cm–1. LRMS (EI, 70 eV): m/z (%) =
˜
215 (48) [M]+, 186 (19), 129 (100).
N-Benzyl-N-methyl-3-phenylpropiolamide (3tg):[20] Yellow solid. H
1
NMR (500 MHz, CDCl3): δ = 7.55 (d, J = 7.0 Hz, 1 H), 7.50 (d,
J = 5.0 Hz, 1 H), 7.41–7.28 (m, 8 H), 4.86, 4.67 (s, 2 H), 3.19, 2.93
(s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 154.4 (2 C), 136.2,
136.1, 132.3 (2 C), 130.0 (2 C), 128.8, 128.6, 128.4 (2 C), 128.1,
127.9, 127.6, 127.4, 120.5, 120.4, 90.7, 90.2, 81.6 (2 C), 54.8, 49.8,
35.7, 31.9 ppm. IR (KBr): ν = 1667 cm–1. LRMS (EI, 70 eV): m/z
˜
(%) = 249 (29) [M]+, 248 (57), 220 (30), 129 (100).
N-Methyl-N,3-diphenylpropiolamide (3th):[22] White solid. 1H NMR
(500 MHz, CDCl3): δ = 7.45 (t, J = 7.5 Hz, 2 H), 7.40–7.35 (m, 3
H), 7.31 (d, J = 7.5 Hz, 1 H), 7.23 (t, J = 8.0 Hz, 2 H), 7.14 (d, J
= 7.5 Hz, 2 H), 3.39 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 154.3, 143.3, 132.4, 129.9, 129.1, 128.3, 127.9, 127.4, 120.4,
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90.8, 82.6, 36.3 ppm. IR (KBr): ν = 1670 cm–1. LRMS (EI, 70 eV):
˜
m/z (%) = 235 (86) [M]+, 206 (11), 178 (22), 129 (100).
N,3-Diphenylpropiolamide (3ti):[22] Yellow solid. 1H NMR
(500 MHz): δ = 7.82 (s, 1 H), 7.57 (t, J = 8.0 Hz, 4 H), 7.43 (t, J
= 7.5 Hz, 1 H), 7.37–7.33 (m, 4 H), 7.14 (t, J = 7.5 Hz, 1 H) ppm.
13C NMR (125 MHz): δ = 151.0, 137.3, 132.6, 130.3, 129.1, 128.5,
124.9, 119.0 (2 C), 85.7, 83.4 ppm. IR (KBr): ν = 1669 cm–1. LRMS
˜
(EI, 70 eV): m/z (%) = 222 (5) [M + 1]+, 221 (30) [M]+, 193 (6),
129 (100), 101 (10), 75 (13).
6
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O30543
/KAP1
Date: 22-07-13 12:27:43
Pages: 7
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Received: April 15, 2013
Published Online: ᭿
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