Reductive amination of aldehydes and ketones with primary amines by using lithium amidoborane as reducing reagent

Article abstract of DOI:10.1002/cjoc.201200132

A variety of secondary amines were obtained in high isolated yields in the reductive amination of aldehydes and ketones by using lithium amidoborane as reducing agent. Compared to ammonia borane, lithium amidoborane has higher reducibility, and thus, exhibits faster reaction rate.

Full text of DOI:10.1002/cjoc.201200132

FULL PAPER
DOI: 10.1002/cjoc.201200132
Reductive Amination of Aldehydes and Ketones with Primary
Amines by Using Lithium Amidoborane as Reducing Reagent
Xu, Weilianga(徐维亮)
Wu, Guotaoc(吴国涛)
Zheng, Xuelib(郑学丽)
Chen, Ping*,c(陈萍)
a Department of Chemistry, National University of Singapore, 117543 Singapore
b Key Lab of Green Chemistry and Technology, Ministry of Education, the Institute of Homogeneous Catalysis,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
c Dalian Institute of Chemical Physics, Dalian, Liaoning 116023, China
A variety of secondary amines were obtained in high isolated yields in the reductive amination of aldehydes and
ketones by using lithium amidoborane as reducing agent. Compared to ammonia borane, lithium amidoborane has
higher reducibility, and thus, exhibits faster reaction rate.
Keywords lithium amidoborane, reductive amination, primary amines, aldehydes, ketones
Introduction
Scheme 1 Mechanism of reductive amination
H
Reductive amination, where an aldehyde or ketone
and an amine are treated together with a reductant, is
one of the most useful and fundamental methods for the
preparation of primary, secondary and tertiary amines in
organic chemistry.[1] As shown in Scheme 1,[1,2] the
reductive amination involves the initial nuleophilic
addition of carbonyl compound by amine and is
followed by proton transfer to form a as an aminol
intermediate or carbinol amine through step 1.
Subsequently, a dehydrates to b after protonation of the
carbinolamine on oxygen as iminium ion or imine
through step 2. Finally, b is reduced by reducing reagent
to achieve the respective alkylated amine c through step
3.
H
O
H+
O
O
C
R1 C R2
step 1
+
R2
R4
R1
R3
R1
R2
C
+
H
N R4
R3
N
H
H
O
C
N
H
+
C
+
O
H
R2
R1
step 2
R1
R2
R4
H+
+ H2O
+
R1
R4
C
R2
N
R3
N
R3
R4
R3
a
H
R2
R1
C R2
R1
R3
C
[H]
+N R4
step 3
N R4
R3
b
c
Several reducing reagents have been reported for
reductive amination, such as NaBH3CN,[3] NaBH-
(OAc)3,[4] decaborane,[5] NaBH4-ZnCl2,[6] NaBH4-
Ti(OiPr)4,[7] zinc borohydride in the presence of Lewis
R1, R2, R3, R4 = H, aryl or alkyl
acids,[8] pyridine-BH3,[9] 2-picoline-BH3[10], dimethyl-
which displays improved performances to pristine AB
in hydrogen desorption.[15] Lithium amidoborane
(LiNH2BH3, LiAB for short) is a typical representative
of metal amidoboranes. Compared with AB, LiAB can
release hydrogen at ca. 90 ℃ in solid state or at ca. 40
℃ in THF solution.[16]
LiAB was first reported as a reducing reagent in
converting tertiary amides to primary alcohols in
1996.[17] More recently, high chemoselectivity of LiAB
in the reduction of α,β-unsaturated ketones to allylic
alcohols was identified.[18] However, to the best of our
knowledge, there is no report on its application in re-
[12]
amine-BH3,[11] and benzylamine-BH3
etc. In 2010,
Ramachandran et al.[13] reported reductive amination by
using ammonia borane (NH3BH3, AB for short) as re-
ducing reagent. In this work, a variety of primary, sec-
ondary and tertiary amines were synthesized in high
yields. AB is a promising solid-state hydrogen storage
material due to high hydrogen content and co-existence
of protic and hydridic hydrogen which facilitates hy-
drogen release under mild condition.[14] Cationic substi-
tution of protic H on AB by alkali or alkaline earth ele-
ment leads to the formation of metal amidoboranes,
*
E-mail: pchen@dicp.ac.cn; Tel.: 0086-0411-84379583
Received February 13, 2012; accepted March 27, 2012; published online XXXX, 2012.
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cjoc.201200132 or from the author.
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Xu et al.
FULL PAPER
ductive amination. Due to its excellent performance in
hydrogen desorption, we postulate that LiAB may also
exhibit distinct feature in reductive amination.
According to the experimental results shown above,
the reduction aminations of various aldehydes and ke-
tones with primary amine were carried out at room
temperature. The molar ratio of carbonyl/amine/AlCl3/
LiAB was 1/1.2/1.5/1.5. The results are shown in Table
2. All the reactions involving aldehydes were completed
within 1 h. On the other hand, reactions involving ke-
tones were slower. Additionally, LiAB presents higher
reactivity than AB in reductive amination. For example,
AB needs 6 h to aminate benzaldehyde and aniline
which was reported by Ramachandran and his cowork-
ers.[13] However, only 1 h is needed in the case of LiAB.
LiAB also shows higher reactivity than other boro-
hydrides such as NaBH3CN and pyridine-borane. For
example, NaBH3CN[3a] and pyridine borane[9a] need 72
h and 16 h, respectively, in reductive amination with
primary amines. Meanwhile, we tried to process reduc-
tive amination of aldehydes and ketones with secondary
amines such as morpholine. However, the results were
unsatisfactory because alcohols derivated from carbonyl
compounds were obtained in large amount. The reason
may be due to the iminium salts formed after condensa-
tion of a ketone or an aldehyde with a secondary amine.
Most of iminium salts are unstable.[20] The reducing
agent used in the reaction must be capable of reducing
the iminium salt, but it cannot reduce the carbonyl
group of the ketone or aldehyde at the same time.[19]
Therefore, it is assumed that LiAB which exhibits
strong reactivity in reducing ketones and aldehydes[18]
might not be a suitable reducing reagent in reductive
amination of carbonyl compounds with secondary
amines.
Results and Discussion
Generally, imine formation (step 2, Scheme 1) is
usually the rate-determining step in reductive amination
and it is under equilibrium control.[1] Therefore, it is
necessary to remove H2O either by separating water
physically or by adding a drying agent during the imine
formation in order to break the equilibrium. In addition,
reductive amination prefers acid solution.[19] Therefore,
Lewis acids are suitable co-reactants to promote ab-
straction of H2O in the imine formation step and provide
acidic environment.[13,8b] Therefore, we first screened
reductive amination of benzaldehyde and aniline by us-
ing LiAB with a number of common Lewis acids to fig-
ure out additive effect. It should be noted that imine
formation does not occur without Lewis acids in our
experiment. In a typical reaction procedure, 0.5 mmol
benzaldehyde was firstly added to the solution of 0.6
mmol aniline in 2 mL THF. Then, 0.75 mmol Lewis
acid was introduced into the mixture and the reaction
system was stirred for 1 h at room temperature. Subse-
quently, 5 mL of 0.15 mol•L－ LiAB solution (0.75
1
mmol LiAB) was added and the mixture was stirred at
room temperature until the completion of the reaction
(detected by GC). Based on the results listed in the Ta-
ble 1, AlCl3 exhibits the best performance. It is interest-
ing to note that Ti(OPr-i)4, the most effective Lewis acid
previously observed in the reductive amination using
AB, [13] did not perform well upon using LiAB as the
reducing reagent. In addition, most of the reducible
transition metal salts are inferior to AlCl3 and ZnCl2.
Such a phenomenon may be due to the fact that LiAB or
AB can readily reduce transition metal salts giving rise
to metallic species or alloys which can further catalyze
the self-decomposition of LiAB or AB.
Conclusions
LiAB is a powerful reductive amination reagent. The
formation of secondary amines was achieved in good
yield for aldehydes or ketones with primary amines by
LiAB in the presence of AlCl3. Therefore, this reductive
amination method may provide a novel way for synthe-
sizing secondary amines in organic chemistry.
Table 1 Reductive amination using LiAB in the presence of
different Lewis acids
NH2
CHO
(1) Lewis acid (1.5 equiv.)
THF, 1 h
+
Experimental
N
H
(2) LiAB (1.5 equiv.), r.t.
General remarks
Solvent and reagents were purchased commercially
and used without further purification. NMR spectra
were recorded on Bruker DRX-500 instrument. Chemi-
cal shifts are relative to the internal: singlet δ 0 of TMS
Entry
Lewis acid
ZnCl2
Time/h
Yielda/%
1
2
3
4
5
6
7
2
5
1
4
4
3
4
85
18
98
50
28
46
41
NiCl2
AlCl3
1
for H NMR; the middle of CDCl3 triplet δ 77 for 13C
NMR, or external singlet δ 0 of BF3•Et2O for 11B NMR.
IR spectra were obtained by Varian 3100 FTIR spec-
trophotometer using Resolution Pro program. GC re-
sults were detected by Ramin 2060. MS analyses were
performed on Agilent 6890-5973 GC-MS.
CoCl2
Ti(OPr-i)4
TiCl3-THF
FeCl3
a GC yield.
2
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Chin. J. Chem. 2012, XX, 1—6

Reductive Amination of Aldehydes and Ketones with Primary Amines
Table 2 Reductive amination of carbonyl compounds and primary amines by using LiAB in the presence of AlCl3
Entry
1
Carbonyl compound
Amine
Timea/h
Product
Yieldb/%
CHO
NH2
1
93
N
H
CHO
CHO
CHO
CHO
CHO
CHO
CHO
NH2
2
3
4
5
6
7
8
1
1
1
1
1
1
1
98
78
81
85
81
82
91
N
H
O
NH2
N
H
O
Cl
NH2
NH2
N
H
Cl
NO2
N
H
O2N
NH2
N
H
N
H
NH2
NH2
N
H
CHO
CHO
NH2
NH2
NH2
N
H
9
1
1
1
87
87
82
10
11
N
H
CHO
N
H
O
O
CHO
NH2
NH2
12
13
1
1
85
83
N
H
Cl
Cl
CHO
N
H
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Xu et al.
FULL PAPER
Continued
Entry
14
Carbonyl compound
Amine
Timea/h
1
Product
Yieldb/%
CHO
NH2
81
N
H
CHO
CHO
NH2
N
H
15
16
1
1
80
85
N
NH2
NH2
H
17
18
1
2
94
81
CHO
N
H
O
O
O
O
NH2
H
N
H
NH2
N
19
20
2
2
82
86
NH2
O
O
NH
HN
NH2
21
2
84
a The time of the first step (amination), which is 1 h, is not included in. b Isolated yields on the basis of the carbonyls.
Synthesis of LiAB
diethyl ether for 3 times. The combined diethyl ether
extracts were washed with brine, dried with NaSO4
overnight and concentrated in vacuum. In the final step,
the residue was purified by silica gel flash chromatog-
raphy to obtain the desired product. The product was
characterized by FTIR, 1H NMR, 13C NMR and
GC-MS.
1.5 mmol NH3BH3 was firstly dissolved in 10 mL
THF in metal jar in glove box. Then, 1.5 mmol LiH was
quickly added into the solution and the jar cap was
closed. The system was stirred under room temperature.
After one equivalent of H2 was released detected by
pressure gauge, clear 0.15 mol•L－ LiAB solution was
1
obtained characterized by 11B NMR (160 MHz, THF-d8)
δ:－22.14 (q, J＝85.09 Hz). The solution can be di-
rectly used into reducing reaction without further puri-
fication.
Product characterization
1
N-Benzylaniline (Entry 1,Table 2): H NMR (500
MHz, CDCl3) δ: 4.00 (s, 1H, NH), 4.32 (s, 2H, CH2),
6.64—6.72 (m, 3H, ArH), 7.16—7.36 (m, 7H, ArH);
13C NMR (126 MHz, CDCl3) δ: 48.36, 112.87, 117.59,
127.23, 127.52, 128.64, 129.27, 140.51; FT-IR (KBr)
νmax: 3419, 3052, 3026, 2920, 2841, 1602, 1505, 1452,
General experimental procedure for reducing ami-
nation with LiAB
0.5 mmol ketone or aldehyde was firstly added to the
solution of 0.6 mmol primary amine in 2 mL THF. Then,
0.6 mmol AlCl3 was introduced into the mixture and the
reaction system was stirred for 1 h at room temperature.
Subsequently, 5 mL of 0.15 mol•L－1 LiAB solution was
added and stirring was continued at room temperature
for 1—2 h until the completion of the reaction (the ex-
tent of reaction was determined by GC analyses and
TLC). Then, THF was removed under vacuum. After
this, the resulting mixture was treated with HCl (4 mL,
－
＋
1
1324, 750, 693 cm ; MS (EI) m/z (%): 182 ([M－H] ,
100), 91 (70), 106 (12), 77 (10), 65 (9).
N-Benzyl-4-methylaniline (Entry 2, Table 2): 1H
NMR (500 MHz, CDCl3) δ: 2.25 (s, 3H, CH3), 3.89 (s,
1H, NH), 4.31 (s, 2H, CH2), 6.57—7.00 (m, 4H, ArH),
7.28—7.36 (m, 5H, ArH); 13C NMR (126 MHz, CDCl3)
δ: 20.39, 48.67, 113.02, 126.75, 127.15, 127.50, 128.60,
129.75, 139.70, 145.96; FT-IR (KBr) νmax: 3416, 3027,
－
1
2918, 2863, 1617, 1521, 807, 742, 697 cm ; MS (EI)
m/z (%): 196 ([M－H]＋, 100), 91 (78), 120 (18), 65
(11).
－
1
2 mol•L ) and stirred for an additional hour. Then,
－
1
NaOH (2 mol•L ) solution was added to adjust the pH
1
N-Benzyl-4-methoxyaniline (Entry 3, Table 2): H
value to 8. Next, the solution was extracted with 10 mL
4
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Reductive Amination of Aldehydes and Ketones with Primary Amines
NMR (500 MHz, CDCl3) δ: 3.74 (s, 3H, CH3), 3.77 (s,
1H, NH), 4.28 (s, 2H, CH2), 6.60—6.62 (m, 2H, ArH),
6.78—6.79 (m, 2H, ArH), 7.28—7.37 (m, 5H, ArH);
13C NMR (126 MHz, CDCl3) δ: 49.27, 55.83, 114.14,
114.97, 127.17, 127.55, 128.60, 139.75, 142.52, 152.26;
FT-IR (KBr) νmax: 3392, 3060, 3028, 2998, 2906, 2833,
128.57, 129.29, 138.45, 139.45, 148.31; FT-IR (KBr)
νmax: 3418, 3050, 3021, 2919, 2860, 1602, 1505, 1323,
－
＋
1
749 cm ; MS (EI) m/z (%): 197 ([M] , 50), 105 (100),
77 (40), 93 (30).
1
N-(4-Methylbenzyl)aniline (Entry 10, Table 2): H
NMR (500 MHz, CDCl3) δ: 2.36 (s, 3H, CH3), 3.96 (s,
1H, NH), 4.30 (s, 2H, CH2), 6.64—6.73 (m, 3H, ArH),
7.17—7.27 (m, 6H, ArH); 13C NMR (126 MHz, CDCl3)
δ: 21.10, 48.11, 112.87, 117.51, 127.53, 129.26, 129.32,
136.41, 136.87, 148.27; FT-IR (KBr) νmax: 3419, 3049,
3020, 2920, 2860, 1603, 1505, 1325, 1266, 806, 748
－
1
1624, 1512, 1245, 1034, 820, 742, 694 cm ; MS (EI):
m/z (%): 212 ([M－H]＋, 100), 122 (53), 91 (47), 195
(43), 167 (18).
N-Benzyl-4-chloroaniline (Entry 4, Table 2): 1H
NMR (500 MHz, CDCl3) δ: 4.04 (s, 1H, NH), 4.30 (s,
2H, CH2), 6.54—6.57 (m, 2H, ArH), 7.09—7.10 (m, 2H,
ArH), 7.27—7.34 (m, 5H, ArH); 13C NMR (126 MHz,
CDCl3) δ: 48.36, 113.93, 122.13, 127.37, 127.41,
128.70, 129.07, 138.96, 146.67; FT-IR (KBr) νmax: 3427,
3062, 3028, 2922, 2852, 1600, 1500, 1321, 1177, 815,
－
＋
1
cm ; MS (EI) m/z (%): 196 ([M－H] , 85), 105 (100),
77 (18).
1
N-(4-Methoxybenzyl)aniline (Entry 11, Table 2): H
NMR (500 MHz, CDCl3) δ: 3.81 (s, 3H, CH3), 3.93 (s,
1H, NH), 4.26 (s, 2H, CH2), 6.65—6.90 (m, 5H, ArH),
7.19—7.30 (m, 4H, ArH); 13C NMR (126 MHz, CDCl3)
δ: 47.83, 55.31, 112.89, 114.89, 117.53, 128.82, 129.27,
131.49, 148.27, 158.92; FT-IR (KBr) νmax: 3398, 3047,
2962, 2836, 1604, 1514, 1425, 1302, 1253, 1175, 1034,
－
＋
1
733, 698 cm ; MS (EI) m/z (%): 216 ([M－H] , 82),
91 (100), 65 (9), 139 (9).
N-Benzyl-4-nitroaniline (Entry 5, Table 2): 1H NMR
(500 MHz, CDCl3) δ: 4.41 (s, 2H, CH2), 4.86 (s, 1H,
NH), 6.54—6.56 (m, 2H, ArH), 7.31—7.35 (m, 5H,
ArH), 8.05—8.07 (m, 2H, ArH); 13C NMR (126 MHz,
CDCl3) δ: 47.70, 111.34, 113.238, 126.37, 127.35,
127.87, 128.96, 137.38, 153.04; FT-IR (KBr) νmax: 3373,
－
＋
1
818, 748, 694 cm ; MS (EI) m/z (%): 212 ([M－H] ,
50), 121 (100), 77 (13).
1
N-(4-Chlorobenzyl)aniline (Entry 12, Table 2): H
NMR (500 MHz, CDCl3) δ: 4.02 (s, 1H, NH), 4.30 (s,
2H, CH2), 6.60—6.73 (m, 3H, ArH), 7.17—7.30 (m, 6H,
ArH); 13C NMR (126 MHz, CDCl3) δ: 47.63, 112.91,
117.82, 128.69, 128.75, 129.29, 132.89, 138.00, 147.85;
FT-IR (KBr) νmax: 3419, 3052, 3022, 2923, 2852, 1701,
－
1
2929, 1605, 1519, 740 cm ; MS (EI) m/z (%): 227
([M－H]＋, 100), 106 (40), 89 (24), 181 (21), 77 (19).
1
Dibenzylamine (Entry 6, Table 2): H NMR (500
MHz, CDCl3) δ: 1.62 (s, 1H, NH), 3.70—3.80 (m, 4H,
CH2), 7.25—7.33 (m, 10H, ArH); 13C NMR (126 MHz,
CDCl3) δ: 53.18, 58.72, 126.94, 128.15, 128.39, 128.80,
128.97, 129.58, 134.42, 140.35; FT-IR (KBr) νmax: 3308,
－
1
1603, 1088, 1014, 817, 750, 692 cm ; MS (EI) m/z (%):
216 ([M－H]＋, 98), 125 (100), 90 (17), 77 (13), 106
(10), 181 (13).
－
1
1
3195, 3062, 3027, 2920, 2837, 1495, 1454 cm ; MS
(EI) m/z (%): 197 ([M]＋, 100), 91 (78), 120 (18), 65
(11).
N-Cinnamylaniline (Entry 13, Table 2): H NMR
(500 MHz, CDCl3) δ: 3.83 (s, 1H, NH), 3.95 (s, 2H,
CH2), 6.33—6.36 (m, 1H, CH), 6.70 (d, 3JHH＝15.80 Hz,
1H, CH), 6,74—7.76 (m, 3H, ArH), 7.21—7.39 (m, 7H,
ArH); 13C NMR (126 MHz, CDCl3) δ: 46.24, 113.10,
117.60, 126.37, 127.12, 127.56, 128.60, 129.31, 131.56,
136.93, 148.10; FT-IR (KBr) νmax: 3414, 3052, 3023,
N-Benzylpropan-1-amine (Entry 7, Table 2): 1H
NMR (500 MHz, CDCl3) δ: 0.90 (t, 3JHH＝7.41 Hz, 3H,
CH3), 1.23 (s, 1H, NH), 1.49—1.53 (m, 2H, CH2), 2.58
3
(t, JHH＝7.24 Hz, 2H, CH2), 3.76 (s, 2H, CH2), 7.29—
－
7.31 (m, 5H, ArH); 13C NMR (126 MHz, CDCl3) δ:
11.74, 23.14, 51.32, 54.00, 126.85, 128.10, 128.35,
129.11; FT-IR (KBr) νmax: 3306, 3063, 3028, 2959,
2917, 2834, 1602, 1504, 1322, 966, 748, 692 cm ; MS
(EI) m/z (%): 208 ([M－H]＋, 60), 117 (100), 91 (20), 77
(19).
1
－
1
2928, 2873, 2817, 1494, 1454 cm ; MS (EI) m/z (%):
149 ([M]＋, 10), 91(100), 106 (5), 120 (60), 65 (15), 77
(5).
N-Cinnamyl-4-methylaniline (Entry 14, Table 2): 1H
NMR (500 MHz, CDCl3) δ: 2.23 (s, 3H, CH3), 3.68 (s,
1H, NH), 3.90 (s, 2H, CH2), 6.32—6.34 (m, 1H, CH),
6.57—6.59 (m, 3H, ArH), 7.00—7.36 (m, 7H, ArH);
13C NMR (126 MHz, CDCl3) δ: 20.36, 46.61, 113.28,
126.32, 126.88, 127.34, 127.46, 128.54, 129.75, 131.42,
136.96, 145.81; FT-IR (KBr) νmax: 3414, 3052, 3023,
1
N-(2-Methylbenzyl)aniline (Entry 8, Table 2): H
NMR (500 MHz, CDCl3) δ: 2.41 (s, 3H, CH3), 3.83 (s,
1H, NH), 4.30 (s, 2H, CH2), 6.67—6.77 (m, 5H, ArH),
7.23—7.37 (m, 4H, ArH); 13C NMR (126 MHz, CDCl3)
δ: 18.96, 46.44, 112.76, 117.51, 126.21, 127.46, 128.30,
129.32, 130.37, 136.37, 137.08, 148.37; FT-IR (KBr)
νmax: 3416, 3050, 3019, 2969, 2919, 2859, 1602, 1505,
－
1
2917, 2834, 1602, 1504, 1322, 966, 748, 692 cm ; MS
(EI) m/z (%): 223 ([M]＋, 80), 117 (100), 91 (40), 77
(19).
－
＋
1
1332, 747 cm ; MS (EI) m/z (%): 197 ([M] , 50), 105
N-Benzyl-3-phenylprop-2-en-1-amine (Entry 15,
1
(100), 77 (40), 93 (20).
Table 2): H NMR (500 MHz, CDCl3) δ: 1.55 (s, 1H,
1
N-(3-Methylbenzyl)aniline (Entry 9, Table 2): H
NH), 3.44 (s, 2H, CH2), 3.84 (s, 2H, CH2) 6.29—6.34
(m, 1H, CH), 6.53 (d, 3JHH＝15.80 Hz, 1H, CH), 7.21—
7.36 (m, 10H, ArH); 13C NMR (126 MHz, CDCl3) δ:
51.22, 53.36, 126.28. 126.98, 127.34, 128.20, 128.44,
128.48, 128.54, 131.41, 137.18, 140.29; FT-IR (KBr)
NMR (500 MHz, CDCl3) δ: 2.38 (s, 3H, CH3), 3.99 (s,
1H, NH), 4.31 (s, 2H, CH2), 6.67—6.75 (m, 3H, ArH),
7.12—7.26 (m, 6H, ArH); 13C NMR (126 MHz, CDCl3)
δ: 21.46, 48.40, 112.89, 117.56, 124.63, 128.03, 128.33,
Chin. J. Chem. 2012, XX, 1—6
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Xu et al.
FULL PAPER
νmax: 3311, 3059, 3025, 2918, 2816, 1494, 1452, 966,
734 cm ; MS (EI) m/z (%): 223 ([M] , 40), 117 (100),
Acknowledgement
－
＋
1
We appreciate the advice from Prof. Bakthan Sin-
garam of University of California, Santa Cruz. We are
also grateful to the financial supports from the Chinese
Academy of Sciences Hundred Talents Project (No.
KGCX2-YW-806), Knowledge Innovation Program of
Chinese Academy of Sciences (No. KJCX2-YW-H21)
91 (20), 77 (19).
3-Phenyl-N-propylprop-2-en-1-amine (Entry 16, Ta-
1
3
ble 2): H NMR (500 MHz, CDCl3) δ: 0.92 (t, JHH
＝
7.40 Hz, 3H, CH33), 1.48—1.56 (m, 2H, CH2), 1.75 (s,
1H, NH), 2.60 (t, JHH＝7.24 Hz, 2H, CH2) 3.38—3.40
(m, 2H, CH2), 6.26—6.31 (m, 1H, CH), 6.51 (d, 3JHH
＝
15.87 Hz, 1H, CH), 7.18—7.35 (m, 5H, ArH); 13C
NMR (126 MHz, CDCl3) δ: 11.76, 23.20, 51.35, 51.87,
126.24, 127.29, 128.50, 128.59, 131.18, 137.17; FT-IR
(KBr) νmax: 3307, 3059, 3025, 2958, 2929, 2872, 2813,
References
[1] Tripathi, R. P.; Verma, S. S.; Pandey, J.; Tiwari, V. K. Curr. Org.
Chem. 2008, 12, 1093.
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1
1494, 1448, 966, 742 cm ; MS (EI) m/z (%): 175
([M]＋, 20), 117 (100), 84 (25), 146 (20), 77 (5).
N-(3-(Furan-2-yl)-2-methylallyl)aniline (Entry 17,
[2] McMurry, J. Organic Chemistry, 7th ed., Thomson Brooks/Cole,
Belmont, USA, 2007.
[3] (a) Borch, R. F.; Bernstein, M. D.; Durst, H. D. J. Am. Chem. Soc.
1971, 93, 2897; (b) Borch, R. F.; Hassid, A. I. J. Org. Chem. 1972,
37, 1673.
1
Table 2): H NMR (500 MHz, CDCl3) δ: 2.03 (s, 3H,
CH3), 3.80 (s, 2H, CH2), 3.98 (s, 1H, NH), 2.60 (t,
3JHH＝7.24 Hz, 2H, CH2), 6.22 (s, 1H, CH), 6.32—6.69
(m, 5H, ArH), 7.14—7.35 (m, 3H, Furan-H); 13C NMR
(126 MHz, CDCl3) δ: 16.78, 52.08, 108.42, 111.06,
112.86, 114.21, 117.50, 129.23, 134.67, 141.04, 148.13,
153.24; FT-IR (KBr) νmax: 3420, 3051, 3030, 2911,
[4] (a) Abdel-Magid, A. F.; Mehrman, S. J. Org. Process Res. Dev.
2006, 10, 971; (b) Abdel-Magid, A. F.; Carson, K. G.; Harris, B. D.;
Maryanoff, C. A.; Shah, R. D. J. Org. Chem 1996, 61, 3849.
[5] Bae, J. W.; Lee, S. H.; Cho, Y. J.; Yoon, C. M. J. Chem. Soc.,
Perkin Trans. 1 2000, 145.
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1
[6] Bhattacharyya, S.; Chatterjee, A.; Williamson, J. S. Synth. Commun.
1997, 27, 4265.
2851, 1602, 1507, 1310, 1266 cm ; MS (EI) m/z (%):
213 ([M]＋, 90), 121 (100), 93 (85), 198 (20), 77 (90).
[7] Bhattacharyya, S.; Neidigh, K. A.; Avery, M. A.; Williamson, J. S.
Synlett 1999, 1781.
1
N-Cyclohexylaniline (Entry 18, Table 2): H NMR
(500 MHz, CDCl3) δ: 1.10—2.05 (m, 10H, CH), 3.24 (s,
1H, CH), 3.48 (s, H, NH) 6.58—6.64 (m, 3H, ArH),
7.13—7.20 (m, 2H, ArH); 13C NMR (126 MHz, CDCl3)
δ: 25.00, 25.94, 33.50, 51.69, 113.144, 116.82, 129. 23,
147.42; FT-IR (KBr) νmax: 3404, 3052, 3019, 2958,
[8] (a) Heydari, A.; Khaksar, S.; Esfandyari, M.; Tajbakhsh, M.
Tetrahedron 2007, 63, 3363; (b) Ranu, B. C.; Majee, A.; Sarkar, A.
J. Org. Chem. 1998, 63, 370.
[9] (a) Bomann, M. D.; Guch, I. C.; DiMare, M. J. Org. Chem. 1995, 60,
5995; (b) Burkhardt, E. R.; Coleridge, B. M. Tetrahedron Lett. 2008,
49, 5152.
－
＋
1
2929, 2859, 1601 cm ; MS (EI) m/z (%): 175 ([M] ,
[10] Uchiyama, S.; Inaba, Y.; Matsumoto, M.; Suzuki, G. Anal. Chem.
2008, 81, 485.
20), 132 (100), 106 (10), 93 (15), 77 (10).
1
N-Benzylcyclohexanamine (Entry 19, Table 2): H
[11] Heydari, A.; Tavakol, H.; Aslanzadeh, S.; Azarnia, J.; Ahmadi, N.
Synthesis 2005, 627.
NMR (500 MHz, CDCl3) δ: 1.10—1.89 (m, 13H, CH),
2.46 (s, 1H, NH), 3.79 (s, 2H, CH2), 7.32—7.29 (m, 5H,
ArH); 13C NMR (126 MHz, CDCl3) δ: 25.00, 26.19,
33.56, 51.04, 56.17, 126.75, 128.06, 128.36, 141.01;
FT-IR (KBr) νmax: 3404, 3052, 3019, 2958, 2929, 2859,
[12] Peterson, M. A.; Bowman, A.; Morgan, S. Synth. Commun. 2002,
443.
[13] Ramachandran, P. V.; Gagare, P. D.; Sakavuyi, K.; Clark, P.
Tetrahedron Lett. 2010, 51, 3167.
－
＋
1
1601 cm ; MS (EI) m/z (%): 189 ([M] , 30), 91 (100),
[14] (a) Staubitz, A.; Robertson, A. P. M.; Manners, I. Chem. Rev. 2010,
110, 4079; (b) Stephens, F. H.; Pons, V.; Baker, R. T. Dalton Trans.
2007, 2613.
146 (90), 160 (10), 77 (1).
1
N-(Hexan-2-yl)aniline (Entry 20, Table 2): H NMR
(500 MHz, CDCl3) δ: 0.90—1.34 (m, 11H, CH), 3.44 (s,
1H, NH), 6.57—6.6 (m, 3H, ArH), 7.15—7.20 (m, 2H,
ArH); 13C NMR (126 MHz, CDCl3) δ: 14.06, 20.80,
22.76, 28.36, 36.96, 48.46, 113.08, 116.75, 129.25,
147.76; FT-IR (KBr) νmax: 3404, 3052, 3019, 2958,
[15] (a) Chua, Y. S.; Chen, P.; Wu, G.; Xiong, Z. Chem. Commun. 2011,
47, 5116; (b) Wu, H.; Zhou, W.; Yildirim, T. J. Am. Chem. Soc.
2008, 130, 14834.
[16] (a) Xiong, Z. T.; Yong, C. K.; Wu, G. T.; Chen, P.; Shaw, W.;
Karkamkar, A.; Autrey, T.; Jones, M. O.; Johnson, S. R.; Edwards, P.
P.; David, W. I. F. Nature Mater. 2008, 7, 138; (b) Xiong, Z. T.;
Chua, Y. S.; Wu, G. T.; Xu, W. L.; Chen, P.; Shaw, W.; Karkamkar,
A.; Linehan, J.; Smurthwaite, T.; Autrey, T. Chem. Commun. 2008,
5595.
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1
2929, 2859, 1601, 1505, 1318 cm ; MS (EI) m/z (%):
177 [M]＋(20), 120 (100), 162 (10), 106 (5), 77 (10).
N-Benzylhexan-2-amine (Entry 21, Table 2): 1H
NMR (500 MHz, CDCl3) δ: 0.88—1.28 (m, 13H, CH),
2.62 (s, 1H, NH), 3.70—3.82 (m, 2H, CH2), 7.22—7.29
(m, 5H, ArH); 13C NMR (126 MHz, CDCl3) δ: 14.04,
20.29, 22.88, 28.19, 36.79, 51.39, 52.54, 126.77, 128.10,
128.35, 140.89; FT-IR (KBr) νmax: 3312, 3063, 3027,
[17] Myers, A. G.; Yang, B. H.; Kopecky, D. J. Tetrahedron Lett. 1996,
37, 3623.
[18] Xu, W.; Zhou, Y.; Wang, R.; Wu, G.; Chen, P. Org. Biomol. Chem.
2012, 10, 367.
[19] Carey, F. A. Organic Chemistry, McGraw-Hill, New York, 2006.
[20] Fujihira, T.; Takido, T.; Seno, M. J. Mol. Catal. A: Chem. 1999, 137,
65.
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1
2958, 2957, 3858, 1454, 1376 cm ; MS (EI) m/z (%):
191 ([M]＋, 5), 117 (100), 84 (80), 91 (70), 175 (60).
(Zhao, C.)
6
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Chin. J. Chem. 2012, XX, 1—6