Amidation of 1,3-diarylallylic compounds catalysed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone with molecular oxygen as the terminal oxidant

Article abstract of DOI:10.3184/174751916X14537221307662

An efficient amidation has been developed of 1,3-diarylpropenes by carboxamides, sulfonamides, carbamates and anilines catalysed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and benzoyl peroxide with molecular oxygen. The corresponding products were obtai

Full text of DOI:10.3184/174751916X14537221307662

JOURNAL OF CHEMICAL RESEARCH 2016
VOL. 40 MARCH, 127–129
RESEARCH PAPER 127
Amidation of 1,3-diarylallylic compounds catalysed by 2,3-dichloro-5,6-
dicyano-1,4-benzoquinone with molecular oxygen as the terminal oxidant
Dongping Cheng, Xiayi Zhou, Kun Yuan and Jizhong Yan*
College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, P.R. China
An efficient amidation has been developed of 1,3-diarylpropenes by carboxamides, sulfonamides, carbamates and anilines catalysed by
2,3-dichloro-5,6-dicyano-1,4-benzoquinone and benzoyl peroxide with molecular oxygen. The corresponding products were obtained in
moderate to good yields.
Keywords: oxidative coupling, oxygen, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, benzoyl peroxide
Table 1 Optimisation of the reaction conditionsa
Oxidative coupling reactions play an important role in organic
chemistry. With the concept of green chemistry,1 the use of
molecular oxygen as the terminal oxidant in an oxidation
reaction has attracted much attention owing to its great
abundance in nature and water as the only by-product. To
accomplish the oxidation, a transition metal or transition–metal
complex is usually required to activate the molecular oxygen.2–4
Recently, there has been a great deal of emphasis on metal-
free reactions in organic synthesis because metal residues can
pollute the pharmaceutical intermediates and target products.
To the best of our knowledge, few efforts have been reported
involving metal-free oxidative couplings which simultaneously
employ molecular oxygen as the terminal oxidant.
NH Ph
CO
DDQ /Additive
O2 (balloon)
+
Ph NH
CO
2
Ph
Ph
Ph
Ph
1a
2a
3a
Entry
1
2
3
4d
5
6
7
8
9
10
11
12
13
14
DDQ/mol%
BPO/mol%
T/°C
100
100
100
100
100
100
100
100
100
100
100
80
Yield/%b
47
39
9
10
0
46
42
66
42
44
60
49
42
40
10
10
10
10
0
10
20
20
20
30
30
20
20
20
10
10c
0
10
10
20
10
20
30
20
30
20
20
20
Formation of C–N bonds is an important fundamental
reaction in organic synthesis because many bioactive and
medicinal molecules are nitrogen-containing compounds.5–7
Allylic amination represents one of the most common
C–N bond formation methodologies. An efficient and atom
economical approach to allylic amination is to use directly
allylic alcohols as electrophiles with catalysts such as transition-
metal complexes or salts and Lewis or Brønsted acids.8–17
Despite the excellent progress which has been made, it would
obviously be attractive if allylic amination might be achieved
via C–H oxidative activation. Recently, our group has reported
the metal-free coupling between 1,3-diarylpropenes and
nitrogen nucleophiles promoted by a stoichiometric amount of
2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ).18 However,
the use of a stoichiometric amount of DDQ caused purification
difficulties because of the formation of the by-product DDQH2.
With an interest in developing an application using a catalytic
amount of DDQ in the oxidative reaction,19 we wish to report
an efficient amidation at a diarylallylic sp3 carbon hydrogen
centre catalysed by DDQ with molecular oxygen as the terminal
oxidant.
60
110
a1a (0.24 mmol), 2a (0.2 mmol), CH3NO2 (1 mL), O2 balloon.
bIsolated yields.
cAzobisisobutyronitrile (AIBN) was used as an additive.
dIn the absence of O2.
amounts of both DDQ and BPO were 20 mol%. The yields were
42% and 49% respectively when the temperature was decreased
to 60 °C or 80 °C (Table 1, entries 12–13). The coupling product
was obtained with 40% yield when the temperature was raised
to 110 °C (Table 1, entry 14).
With the best reaction conditions identified, various amides were
examined and the results are summarised in Table 2. Carboxamides
including aromatic, heteroaromatic and cyclic were compatible
with the present procedure and good yields were obtained (Table
2, entries 2–7). Benzene and methylbenzene sulfamides were also
suitable substrates and the coupling products were obtained with
moderate yields (Table 2, entries 10–11). The reaction of aniline
and 1,3-diphenylpropene was carried out under the optimised
condition but no desired coupling product was detected. When
1,4-dioxane was used as solvent instead of nitromethane, the
product could be obtained in low yield. According to the literature,18
the addition sequence of the substrates was changed. To a solution
of DDQ, BPO and 1,3-diarylpropene in 1,4-dioxane, after stirring
for about 5 minutes at room temperature, aniline was added. The
yields were promoted to 46–49% (Table 2, entries 12–13). As a
result of this, the more useful but acid-sensitive carbamates such as
CH3OCO–, Boc– and Cbz– participated in the reaction to provide
Results and discussion
To begin our study we chose 1,3-diphenylpropene (1a)
and benzamide (2a) as model substrates. The reaction was
catalysed by 10 mol% DDQ and 10 mol% benzoyl peroxide
(BPO) at 100 °C in an atmosphere of oxygen (balloon). The
desired coupling product 3a was obtained in 47% yield after
24 h (Table 1, entry 1). Performing the reaction under aerobic
conditions or without BPO resulted in a low yield (Table 1,
entries 3–4). No coupling product was obtained in the absence of
DDQ (Table 1, entry 5). This indicated that DDQ was essential
and that molecular oxygen and BPO could promote the reaction.
Then the amounts of DDQ and BPO were examined (Table 1,
entries 6–11). The best result was obtained when the catalytic
* Correspondent. E-mail: chengdp@zjut.edu.cn; yjz@zjut.edu.cn

128 JOURNAL OF CHEMICAL RESEARCH 2016
Table 2 Oxidative coupling reaction of 1,3-diarylpropenesa
In summary, we have developed an amidation of
1,3-diarylallylic compounds with nitrogen nucleophiles
mediated by a catalytic amount of DDQ and BPO with
molecular oxygen as the terminal oxidant. It may be used
with carboxamides, sulfonamides, carbamates and anilines.
Moderate to good yields are obtained.
R3
R2
DDQ (20 mol%)
BPO (20 mol%)
CH3NO2, 100 oC
HN
R3 NH2
R1
R2
R1
1
2
3
O2 (balloon)
Entry R1, R2 (1)
R3 (2)
Product (3) Yield/%b
Experimental
1
2
3
4
5
6
7
8
C6H5, C6H5
C6H5CO
3a
3b
3c
3d
3e
3f
3g
3hc
3ic
3j
3k
3l
3m
3n
3o
3p
66
90
73
70
71
57
54
90
41
40
61
46
49
53
45
57
Column chromatography was carried out on silica gel (200–300
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5, 4-BrC6H4
4-CH3C6H4CO
4-CH3OC6H4CO
4-FC6H4CO
3-ClC6H4CO
2-thienylCO
(CH2)3C(O)
C6H5CO
1
mesh). H NMR spectra were recorded on a Bruker AMX-500 MHz
instrument and the chemical shifts are reported in parts per million
(δ) relative to the internal standard TMS (0 ppm) for CDCl3. The
coupling constants, J, are reported in Hertz (Hz). Low (high) resolution
MS was obtained using ESI ionisation on an Agilent 6210 TOF LC/
MS instrument. Melting points are uncorrected. All reagents were
weighed and handled in air at room temperature and all reactions were
performed without exclusion of air or moisture.
9
C6H5, 4-CH3OC6H4 C6H5CO
10
11
12d
13d
14d
15d
16d
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5, C6H5
C6H5SO2
4-CH3C6H4SO2
C6H5
4-BrC6H4
CH3OC(O)
Boc
Oxidative coupling reaction of 1,3-diarylpropenes 1; general procedure
DDQ (20 mol%, 9.08 mg, 0.04 mmol) and BPO (20 mol%,
9.69 mg, 0.04 mmol) were added to a mixture of 1,3-diarylpropene
1 (0.24 mmol) and substrate 2 (0.2 mmol) in CH3NO2 (1 mL). The
reaction was carried out at 100 °C under an oxygen atmosphere
(oxygen balloon) for 24 h. The resulting mixture was purified by flash
column chromatography on silica gel (petroleum ether:ethyl acetate =
10:1–20:1) to give the desired pure product 3a–k.
Cbz
a1 (0.24 mmol), 2 (0.2 mmol), DDQ (20 mol%), BPO (20 mol%), CH3NO2 (1 mL), 100 °C,
24 h, O2 balloon.
Procedure for the preparation of compounds 3l–p
bIsolated yields.
A mixture of DDQ (20 mol%, 9.08 mg, 0.04 mmol), BPO (20 mol%,
9.69 mg, 0.04 mmol) and 1,3-diarylpropene (0.2 mmol) in 1,4-dioxane
(1 mL) was stirred for about 5 minutes. Aniline (0.55 mmol) in
1,4-dioxane (0.5 mL) was added to the mixture. Stirring was continued
under an oxygen atmosphere (oxygen balloon) for 24 h. The resulting
mixture was purified by flash column chromatography on silica gel
(petroleum ether–ethyl acetate) to give the desired named products 3l–p.
(E)-N-(1,3-Diphenylallyl)benzamide (3a): White solid; m.p.
cA mixture of α- and γ-products was obtained.
d1,4-Dioxane instead of CH3NO2.
the corresponding products with moderate yields (Table 2, entries
14–16).
A possible mechanism of the reaction was proposed
(Scheme 1). In the experiment, the yield of coupling product was
decreased dramatically when (2,2,6,6-tetramethylpiperidin-
1-yl)oxyl (TEMPO) was added to the reaction mixture. By-
product 1,3-diphenylpropen-3-one, which might be generated
by further oxidation of 1,3-diphenylpropene, was obtained. The
reaction of asymmetrical 1,3-diarylpropene with benzamide
gave a mixture of the corresponding α- and γ-products (Table 2,
entries 8–9). According to the literature20 and the above results,
this indicated that the reaction is likely to proceed through a
radical process. In the presence of DDQ, 1,3-diphenylpropene
might generate an allylic cation intermediate, which will react
further with nitrogen nucleophiles to produce the coupled
products. The allylic cation can afford isomeric products
by reaction at the α- and γ-positions when an asymmetrical
1,3-diarylpropene is used as substrate.
1
162–163 °C (lit.15 163–164 °C); H NMR (500 MHz, CDCl3): δ 7.85
(d, J = 10.8 Hz, 2H), 7.53 (t, J = 7.4 Hz, 1H), 7.47–7.25 (m, 12H),
6.66–6.62 (m, 2H), 6.47 (dd, J = 6.1, 15.9 Hz, 1H), 6.06–6.04 (m, 1H);
13C NMR (125 MHz, CDCl3): δ 166.5, 141.0, 136.5, 134.5, 131.9, 131.6,
128.9, 128.63, 128.59, 127.85, 127.79, 127.2, 127.1, 126.6, 55.3.
(E)-N-(1,3-Diphenylallyl)-4-methylbenzamide (3b): White solid;
1
m.p. 156–157 °C (lit.21 156–158 °C); H NMR (500 MHz, CDCl3):
δ 7.75 (d, J = 8.1 Hz, 2H), 7.45–7.38 (m, 6H), 7.35–7.31 (m, 3H),
7.29–7.24 (m, 3H), 6.64–6.55 (m, 2H), 6.46 (dd, J = 6.1, 15.9 Hz, 1H),
6.06–6.03 (m, 1H), 2.41 (s, 3H); 13C NMR (125 MHz, CDCl3): δ 166.5,
142.1, 141.0, 136.5, 131.7, 131.5, 129.3, 128.9, 128.87, 128.6, 127.8, 127.7,
127.3, 127.1, 126.6, 55.2, 21.5.
(E)-N-(1,3-Diphenylallyl)-4-methoxybenzamide (3c): White solid;
m.p. 149–151 °C (lit.22 150–151 °C); 1H NMR (500 MHz, CDCl3): δ 7.82
+
H3C
H
C
3
Br
O
O
C
NaO
H2
P
C
Br–
CH3
+
P
H3C
H3CO
O
CH3
H3C
CH3
O
C
P
C
CH3
H
H3CO
CH3
Scheme 1 Possible mechanism of the coupling reaction.

JOURNAL OF CHEMICAL RESEARCH 2016 129
(d, J = 8.9 Hz, 2H), 7.44–7.38 (m, 6H), 7.34–7.24 (m, 4H), 6.95–6.93 (m,
2H), 6.64–6.61 (m, 1H), 6.53–6.52 (m, 1H), 6.46 (dd, J = 6.1, 15.9 Hz, 1H),
6.04–6.02 (m, 1H), 3.86 (s, 3H); 13C NMR (125 MHz, CDCl3): δ 166.1,
162.3, 141.1, 136.5, 131.6, 129.1, 129.0, 128.8, 128.5, 127.7, 127.6, 127.2,
126.59, 126.57, 113.7, 55.4, 55.2.
(E)-N-(1,3-Diphenylallyl)-4-fluorobenzamide (3d): White solid; m.p.
139–140 °C; 1H NMR (500 MHz, CDCl3): δ 7.86–7.83 (m, 2H), 7.43–7.25
(m, 10H), 7.07 (t, J = 8.6 Hz, 2H), 6.85 (d, J = 8.0 Hz, 1H), 6.60 (d, J = 15.9
Hz, 1H), 6.44 (dd, J = 6.2, 15.9 Hz, 1H), 6.02–5.99 (m, 1H); 13C NMR (125
MHz, CDCl3): δ 165.7, 165.5, 163.7, 140.7, 136.3, 131.8, 130.43, 130.41,
129.5, 129.4, 128.8, 128.61, 128.55, 127.9, 127.8, 127.2, 126.5, 115.6, 115.5,
55.4; HRMS (ESI) calcd for C22H18FNNaO [M + Na+]: 354.1265; found:
354.1271.
(E)-N-(1,3-Diphenylallyl)-3-chlorobenzamide (3e): White solid; m.p.
149–150 °C; 1H NMR (500 MHz, CDCl3): δ 7.82 (s, 1H), 7.70 (d, J = 7.6 Hz,
1H), 7.49–7.25 (m, 12H), 6.72 (d, J = 7.6 Hz, 1H), 6.61 (d, J = 15.9 Hz, 1H),
6.44 (dd, J = 6.1, 15.9 Hz, 1H), 6.02–5.99 (m, 1H); 13C NMR (125 MHz,
CDCl3): δ 165.2, 140.6, 136.3, 136.1, 134.8, 132.0, 131.6, 129.9, 128.9, 128.6,
128.4, 127.9, 127.88, 127.4, 127.2, 126.6, 125.2, 55.4; HRMS (ESI) calcd for
C22H18ClNNaO [M + Na+]: 370.0969; found: 370.0961.
3H), 7.31–7.28 (m, 1H), 7.24–7.21 (m, 2H), 6.80–6.77 (m, 1H), 6.72–6.68
(m, 3H), 6.47 (dd, J = 6.2, 15.9 Hz, 1H), 5.16 (d, J = 6.1 Hz, 1H), 4.19 (s,
1H); 13C NMR (125 MHz, CDCl3): δ 146.2, 141.1, 135.6, 130.1, 129.7, 128.1,
127.8, 127.5, 126.6, 126.5, 126.2, 125.5, 116.7, 112.6, 59.7.
(E)-4-Bromo-N-(1, 3-diphenylallyl)aniline (3m):18 Pale yellow oil;
1H NMR (500 MHz, CDCl3): δ 7.46–7.40 (m, 6H), 7.36–7.33 (m, 3H),
7.29–7.24 (m, 3H), 6.64 (d, J = 15.9 Hz, 1H), 6.56–6.53 (m, 2H), 6.41 (dd,
J = 6.2, 15.9 Hz, 1H), 5.08 (d, J = 6.1 Hz, 1H), 4.19 (s, 1H); 13C NMR (125
MHz, CDCl3): δ 145.1, 140.5, 135.4, 130.8, 130.4, 129.1, 127.9, 127.6, 126.8,
126.7, 126.1, 125.5, 114.2, 108.4, 59.6.
(E)-N-(1,3-Diphenylallyl)methylcarbamate (3n): White solid; m.p.
104–105 °C (lit.23 104–106 °C); 1H NMR (500 MHz, (CD3)2CO): δ 7.44 (d,
J = 8.0 Hz, 4H), 7.38–7.23 (m, 6H), 6.95 (s, 1H), 6.64 (d, J = 16.1 Hz, 1H),
6.49 (dd, J = 6.6, 15.9 Hz, 1H), 5.93–5.50 (m, 1H), 3.61 (s, 3H); 13C NMR
(125 MHz, (CD3)2CO): δ 157.1, 143.3, 137.9, 131.4, 131.1, 129.5, 129.4,
128.5, 128.1, 127.9, 127.4, 58.0, 52.1.
(E)-N-(1,3-Diphenylallyl)-tert-butylcarbamate (3o): White solid, m.p.
1
114–116 °C (lit.15 117 °C); H NMR (500 MHz, (CD3)2CO): δ 7.44 (d,
J = 8.0 Hz, 4H), 7.38–7.31 (m, 4H), 7.28–7.23 (m, 2H), 6.68(s, 1H), 6.62 (d,
J = 16.0 Hz, 1H), 6.48 (dd, J = 6.8, 15.9 Hz, 1H), 5.48 (s, 1H), 1.42 (s, 9H);
13C NMR (125 MHz, (CD3)2CO): δ 155.9, 143.6, 138.0, 131.4, 131.2, 129.5,
129.3, 128.4, 127.93, 127.86, 127.3, 79.1, 57.5, 28.7.
(E)-N-(1,3-Diphenylallyl)benzylcarbamate (3p): White solid, m.p.
107–109 °C (lit.15 109 °C); 1H NMR (500 MHz, (CD3)2CO): δ 7.47–7.23 (m,
15H), 7.09 (d, J = 6.4 Hz, 1H), 6.65 (d, J = 15.9 Hz, 1H), 6.50 (dd, J = 6.7,
15.9 Hz, 1H), 5.56–5.53 (m, 1H), 5.14–5.07 (m, 2H); 13C NMR (125 MHz,
(CD3)2CO): δ 156.6, 143.2, 138.4, 137.9, 131.5, 131.0, 129.5, 129.4, 129.2,
128.7, 128.6, 128.5, 128.1, 127.9, 127.4, 66.8, 58.1.
(E)-N-(1,3-Diphenylallyl)thiophene-2-carboxamide (3f): White solid;
1
m.p. 182–184 °C; H NMR (500 MHz, CDCl3): δ 7.58–7.57 (m, 1H),
7.51–7.50 (m, 1H), 7.45–7.39 (m, 6H), 7.35–7.31 (m, 3H), 7.28–7.25 (m, 1H),
7.10–7.09 (m, 1H), 6.63 (d, J = 16.0 Hz, 1H), 6.47–6.41 (m, 2H), 6.02–5.99
(m, 1H); 13C NMR (125 MHz, CDCl3): δ 161.0, 140.7, 138.7, 136.4, 133.6,
132.0, 130.2, 128.9, 128.59, 128.55, 128.46, 128.3, 127.9, 127.86, 127.7,
127.3, 126.6, 55.2; HRMS (ESI) calcd for C20H17NNaOS: [M + Na+]:
342.0923; found: 342.0924.
(E)-1-(1,3-Diphenylallyl)pyrrolidin-2-one (3g)23: Colourless oil;
1H NMR (500 MHz, CDCl3): δ 7.48–7.28 (m, 10H), 6.64 (d, J = 15.9 Hz,
1H), 6.47 (dd, J = 6.8, 15.9 Hz, 1H), 6.12 (d, J = 6.7 Hz, 1H), 3.48–3.43 (m,
1H), 3.18–3.13 (m, 1H), 2.53–2.49 (m, 2H), 2.10–1.99 (m, 2H); 13C NMR
(125 MHz, CDCl3): δ 174.8, 138.8, 136.6, 133.6, 130.0, 128.7, 128.6, 128.3,
127.9, 127.8, 129.7, 126.6, 125.5, 56.3, 43.5, 31.2, 18.2.
Electronic Supplementary Information
The ESI (NMR spectra for all compounds) is available through:
stl.publisher.ingentaconnect.com/content/stl/jcr/supp-data
(E)-N-[1-(4-Bromophenyl)-3-phenylallyl]-4-methylbenzamide (3h): As
a mixture of α- and γ-isomers; white solid; m.p. 151–153 °C; 1H NMR (500
MHz, CDCl3): δ 7.74 (d, J = 7.8 Hz, 2H), 7.49 (d, J = 8.4 Hz, 1H), 7.44–7.23
(m, 10H), 6.68–6.53 (m, 2H), 6.46–6.38 (m, 1H), 6.01–5.95 (m, 1H), 2.41
(s, 3H); 13C NMR (125 MHz, CDCl3): δ 166.62, 166.58, 142.23, 142.18,
140.7, 140.1, 136.2, 135.5, 132.3, 131.8, 131.7, 131.3, 131.2, 130.4, 129.8,
129.3, 128.95, 128.92, 128.6, 128.3, 128.1, 128.0, 127.9, 127.3, 127.2, 127.1,
126.6, 121.6, 55.2, 54.8, 21.5; HRMS (ESI) calcd for C23H21BrNO [M + H+]:
406.0807; found: 406.0818.
(E)-N-[1-(4-Methoxylphenyl)-3-phenylallyl]-4-methylbenzamide (3i):
As a mixture of α- and γ-isomers; pale yellow oil; 1H NMR (500 MHz,
CDCl3): δ 7.75–7.73 (m, 2H), 7.44–7.24 (m, 9H), 6.93–6.91 (m, 1H), 6.85
(d, J = 8.7 Hz, 1H), 6.62–6.52 (m, 2H), 6.45 (dd, J = 5.8, 15.9 Hz, 0.5 × 1H),
6.31 (dd, J = 6.2, 15.9 Hz, 0.5 × 1H), 6.02–5.97 (m, 1H), 3.82, 3.81 (ss, 3H),
2.41 (s, 3H); 13C NMR (125 MHz, CDCl3): 166.4, 166.39, 159.4, 159.1,
142.1, 141.2, 136.5, 133.0, 131.5, 131.3, 131.25, 129.3, 129.1, 128.8, 128.6,
128.5, 127.8, 127.7, 127.65, 127.2, 127.1, 126.7, 126.6, 114.2, 114.0, 58.4,
55.34, 55.30, 55.22, 54.6, 21.5, 18.4; HRMS (ESI): calcd for C24H24NO2 [M
+ H+]: 358.1807; found: 358.1807.
This work was supported by the Research Fund of Zhejiang
University of Technology (1001116044408).
Received 24 November 2015; accepted 9 January 2016
Paper 1503731 doi: 10.3184/174751916X14537221307662
Published online: 8 February 2016
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(E)-N-(1,3-Diphenylallyl)benzenesulfonamide (3j): White solid; m.p.
109–111 °C (lit.24 111–114 °C); 1H NMR (500 MHz, (CD3)2CO): δ 7.83 (d,
J = 7.3 Hz, 2H), 7.53 (t, J = 7.3 Hz, 1H), 7.48–7.43 (m, 2H), 7.34 (d, J = 7.3
Hz, 2H), 7.29–7.21 (m, 9H), 6.40 (d, J = 15.8 Hz, 1H), 6.26 (dd, J = 7.0, 15.8
Hz, 1H), 5.21–5.18 (m, 1H); 13C NMR (CD3)2CO): δ 143.1, 141.8, 137.6,
132.9, 132.1, 130.1, 129.7, 129.4, 129.3, 128.6, 128.2, 128.0, 127.9, 127.3,
60.7.
(E)-N-(1,3-Diphenylallyl)-4-methylbenzenesulfonamide (3k): White
solid; m.p. 138–140 °C (lit.15 140–141 °C); 1H NMR (500 MHz, CDCl3): δ
7.68 (d, J = 8.3 Hz, 2H), 7.29–7.15 (m, 12H), 6.36 (d, J = 15.8 Hz, 1H), 6.09
(dd, J = 6.8, 15.8 Hz, 1H), 5.23 (d, J = 7.3 Hz, 1H), 5.14–5.12 (m, 1H), 2.33
(s, 3H); 13C NMR (125 MHz, CDCl3): δ 143.2, 139.7, 137.7, 136.1, 132.1,
129.4, 128.7, 128.4, 128.2, 127.9, 127.8, 127.3, 127.1, 126.5, 59.8, 21.4.
1
(E)-N-(1,3-Diphenylallyl)aniline (3l):18 Pale yellow oil; H NMR (500
MHz, CDCl3): δ 7.51 (d, J = 7.6 Hz, 2H). 7.45–7.42 (m, 4H), 7.38–7.35 (m,