Oxidative alkylation of 1,3-diarylpropenes using O2 catalysed by 2,3-dichloro-5,6-dicyano-benzoquinone and N-hydroxyphthalimide

Article abstract of DOI:10.3184/174751912X13527292608404

A simple oxidative alkylation of 1,3-diarylpropenes with 1,3-dicarbonyl compounds is reported with O₂ catalysed by a mixture of 2,3-dichloro-5,6-dicyano-benzoquinone, N-hydroxyphthalimide, CuBr and NiCl ₂.

Full text of DOI:10.3184/174751912X13527292608404

JOURNAL OF CHEMICAL RESEARCH 2012
RESEARCH PAPER 729
DECEMBER, 729–731
Oxidative alkylation of 1,3-diarylpropenes using O2 catalysed by
2,3-dichloro-5,6-dicyano-benzoquinone and N-hydroxyphthalimide
Dongping Cheng, Xinyi Ye, Wei Cui, Ruirui Sun and Jizhong Yan*
College of Pharmaceutical Science, Zhejiang University ofTechnology, Hangzhou 310014, P. R. China
A simple oxidative alkylation of 1,3-diarylpropenes with 1,3-dicarbonyl compounds is reported with O2 catalysed by
a mixture of 2,3-dichloro-5,6-dicyano-benzoquinone, N-hydroxyphthalimide, CuBr and NiCl2.
Keywords: oxidative alkylation, 2,3-dichloro-5,6-dicyano-benzoquinone, N-hydroxyphthalimide
The formation of carbon–carbon bonds is one of the most
fundamental and important reactions in organic synthesis.1,2
The oxidative cross-dehydrogenative-coupling (CDC) reaction
by using two different C–H bonds directly is one of the most
efficient methods for constructing carbon–carbon bonds.3,4 It
avoids use of functionalising substrates and greatly improves
the atom-economy. 2,3-Dichloro-5,6-dicyano-benzoquinone
(DDQ) is a well-known dehydrogenation reagent,5,6 which has
been applied successfully in the CDC reaction in recent
years.7–18 Our group has developed CDC reactions of 1,3-diar-
ylpropene or 1,3-diarylpropyne with a series of compounds
containing active hydrogen such as β-diketo,19,20 indole,21 alco-
hol,22 and oxime.23–25 In these coupling reactions, DDQ shows
excellent efficiency in the transfer of electrons and protons, but
it has two main problems. First that excess amounts of DDQ
are required and second, the by-product HDDQ is difficult to
remove.26–28 Recently, Floreancig reported oxidative reactions
with MnO2 in the presence of substoichiometric quantities of
DDQ.26 Prabhu reported the CDC reactions of N-aryl tetrahy-
droisoquinolines mediated by a catalytic amount of DDQ with
molecular oxygen as the co-oxidant and azobisisobutyronitrile
as an additive.27 To the best of our knowledge, the formation of
carbon–carbon bond using a catalytic amount of DDQ is rare.
Xu reported a catalytic system of quinone/NHPI (N-
hydroxyphthalimide) in the oxygenation of hydrocarbons to
the corresponding ketone.28 In this system, active species
phthalimido-N-oxyl were formed via quinone abstracting a
hydrogen atom from NHPI. It can in situ abstract a hydrogen
atom from hydrocarbons to form alkyl radicals which gives
the hydroxyl intermediate. We now report a catalytic system
of NHPI/DDQ for the oxidative coupling reaction of
1,3-diarylpropene and 1,3-dicarbonyl compounds using O2.
the substituents on aromatic ring of 1 did not show obvious
electronic effects. Heteroaryl species such as furanyl, thienyl
were compatible with the present procedure and moderate
results were obtained (Table 2, entries 6 and 7). β-Keto esters
were also suitable substrates and 45–46% yields were obtained
(Table 2, entries 10 and 11). To expand the scope of the
substrates, we further examined the mono- and disubstituted
1,3-diarylpropenes (Table 2, entries 12–14) and obtained the
expected products.
In summary, we have developed an oxidative alkylation of
1,3-diarylpropene with 1,3-dicarbonyl compounds catalysed
by NHPI/DDQ. Only a catalytic amount of DDQ is used to
accomplishtheformationofcarbon–carbonbond. Furthermore,
copper and nickel salts are used as co-catalysts under an
atmospheric pressure of O2.
Experimental
Column chromatography was carried out on silica gel (200–300 mesh).
1H NMR spectra was recorded on Bruker AMX-500 MHz instrument
and the chemical shifts were reported in parts per million (δ) relative
to internal standard TMS (0 ppm) for CDCl3. The coupling constants,
J, are reported in Hz. Low-resolution MS was obtained using EI or
ESI ionization. IR spectra were determined on a Bruker Tensor 27
spectrometer. The elements were analysed by Carbo Erbo EA-1110.
Melting points were uncorrected. All reagents were weighed and
handled in air at room temperature and all reactions were performed
without exclusion of air or moisture.
Table 1 Optimisation of the reaction conditionsa
Results and discussion
To establish the best reaction conditions, we chose the
coupling reaction of 1a with 2a catalysed by NHPI/DDQ as a
model reaction. Initially, it was carried out without solvent at
60 °C by the cocatalysis of transition-metal such as Mn(OTf)2,
Co(OAc)2, Mn(OAc)2, CuBr and NiCl2. The expected coupling
product 3a could be obtained, but the yields are all low and
only about 25–35%. When both CuBr and NiCl2 were used as
cocatalysts, the yield was improved to 45% (Table 1, entry 1).
Then a series of solvent was tested (Table 1, entries 2–7). It
was observed that the reaction could proceed in all the solvents
screened. DCE (1,2-dichloroethane) was selected as the best
solvent (Table 1, entry 5). The yield was up to 53% when
the reaction was performed at 80 °C. Varying the amount of
transition-metal catalyst did not improve the yield (Table 1,
entries 9–13).
Entry
Solvent
T/°C
Yield/%b
1
2
neat
THF
CHCl3
CH2Cl2
DCE
60
60
45c
25
3
Reflux
Reflux
60
36
4
34
5
46
6
MeNO2
Dioxane
DCE
60
36
7
60
40
8
80
53
9
DCE
80
45d
44e
47f
42g
46h
10
11
12
13
DCE
80
DCE
80
DCE
80
DCE
80
a 0.5 mmol 1a, 0.6 mmol 2a, 1.2 mL solvent, 5 mol% DDQ,
10 mol% NHPI, 10 mol% CuBr, 10 mol% NiCl2, 24 h.
b Isolation yield.
With the optimised reaction conditions in hand, we exam-
ined the scope of the oxidative alkylation of 1,3-diarylpropene.
A variety of β-diketone could reaction with 1,3-diphenylpro-
pene and 48–64% yields were obtained. It was observed that
c 0.5 mmol 1a, 4 mmol 2a, 10 mol% CuBr, 10 mol% NiCl2.
d 5 mol% CuBr, 5 mol %NiCl2.
e 5 mol% CuBr, 10 mol% NiCl2.
f 10 mol% CuBr, 5 mol% NiCl2.
g 5 mol % NHPI.
h 15 mol % NHPI.
* Correspondent. E-mail: yjz@zjut.edu.cn

730 JOURNAL OF CHEMICAL RESEARCH 2012
Table 2 Oxidative alkylation of 1,3-diarylpropenesa
2-[(2E)-1,3-Diphenylprop-2-en-1-yl]-1-phenyl-3-(2-thienyl)pro-
1
pane-1,3-dione (3f): Solid, m.p. 144–145 °C (lit.19 146–148 °C). H
NMR (500 MHz, CDCl3): δ 8.12–8.09 (m, 1H), 7.98–7.97 (m,
0.5×1H), 7.91–7.89 (m, 1H), 7.77–7.76 (m, 0.5×1H), 7.67–7.66 (m,
0.5×1H), 7.60–7.55 (m, 1H),7.51–7.46 (m, 1+0.5×1H), 7.39–7.35 (m,
3H), 7.27–7.12 (m, 8+0.5×1H), 7.04–7.02 (m, 0.5×1H), 6.40–6.27
(m, 2H), 5.74, 5.71 (dd, J = 11.0, 11.0 Hz, 1H), 4.85–4.80 (m, 1H)
ppm.
Entry
R1, R2
R3, R4
Yield/%b
2-[(2E)-1,3-Diphenylprop-2-en-1-yl]-1-(2-furanyl)-3-phenylpro-
1
pane-1,3-dione (3g): Solid, m.p. 153–155 °C (lit.19 155–157 °C). H
1
2
C6H5, C6H5
4-CH3C6H4, C6H5
4-CH3OC6H4, C6H5
3-CH3OC6H4, C6H5
4-ClC6H4, C6H5
2-Thienyl, C6H5
2-Furanyl, C6H5
CH3, CH3
C6H5, C6H5
C6H5, C6H5
53, 3a
55, 3b
64, 3c
61, 3d
48, 3e
60, 3f
56, 3g
41, 3h
44, 3i
46, 3j
45, 3k
49, 3l
54, 3m
46, 3n
NMR (500 MHz, CDCl3): δ 8.11–8.10 (m, 1H), 7.91–7. 89 (m, 1H),
7.66–7.65 (m, 0.5×1H), 7.57–7.46 (m, 2+0.5×1H), 7.39–7.32 (m,
3H), 7.26–7.12 (m, 9H), 6.56–6.55 (m, 0.5×1H), 6.44–6.25 (m,
2+0.5×1H), 5.91, 5.90 (dd, J = 10.5, 11.0 Hz, 1H), 4.81–4.74 (m, 1H)
ppm.
3-[(2E)-1,3-Diphenylprop-2-en-1-yl]-pentane-2,4-dione (3h): Solid,
m.p. 82–84 °C (lit.19 81–83 °C). 1H NMR (500 MHz, CDCl3): δ 7.25–
7.17 (m, 10H), 6.36 (d, J = 16.0 Hz, 1H), 6.15–6.10 (m, 1H), 4.27–
4.26 (m, 2H), 2.18 (s, 3H), 1.85 (s, 3H) ppm.
2-[(2E)-1,3-Diphenylprop-2-en-1-yl]-1-phenylbutane-1,3-dione
(3i): Solid, m.p. 132–134 °C (lit.19 130–132 °C). 1H NMR (500 MHz,
CDCl3): δ 8.10 (d, J = 7.5 Hz, 1H), 7.90 (d, J = 7.5 Hz, 1H), 7.61 (t,
J = 7.5 Hz, 0.5×1H), 7.56–7.49 (m, 1+0.5×1H), 7.43–7.11 (m, 11H),
6.58 (d, J = 15.5 Hz, 0.5×1H), 6.40–6.35 (m, 0.5×1+0.5×1H), 6.18
(dd, J = 7.8, 16.3 Hz, 0.5×1H), 5.26, 5.21 (dd, J = 11.0, 11.5 Hz, 1H),
4.70–4.61(m, 1H), 2.28 (s, 0.5×3H), 2.02 (s, 0.5×3H) ppm.
Ethyl 2-benzoyl-3,5-diphenylpent-4-enoate (3j):29 Oil. 1H NMR
(500 MHz, CDCl3): δ 8.00–7.98 (m, 1H), 7.83 (d, J = 7.5 Hz, 1H),
7.44–6.99 (m, 13H), 6.44 (d, J = 15.5 Hz, 0.5×1H), 6.34–6.26 (m,
1H), 6.16–6.11 (m, 0.5×1H), 4.93, 4.91 (dd, J = 11.0, 10.5 Hz, 1H),
4.54–4.47 (m, 1H), 4.04–3.96 (m, 0.5×2H), 3.79–3.73 (m, 0.5×2H),
1.02 (t, J = 7.0 Hz, 0.5×3H), 0.79 (t, J = 7.0 Hz, 0.5×3H) ppm.
Ethyl 2-acetyl-3,5-diphenylpent-4-enoate (3k):19 Oil. 1H NMR
(500 MHz, CDCl3): δ 7.35–7.20 (m, 10H), 6.50, 6.46 (dd, J = 16.0,
16.0 Hz, 1H), 6.36–6.26 (m, 1H), 4.34–4.30 (m, 1H), 4.21–4.11 (m,
1+ 0.5×2H), 3.96 (q, J = 7.0 Hz, 0.5×2H), 2.33 (s, 0.5×3H), 2.06 (s,
0.5×3H), 1.23 (t, J = 7.0 Hz, 0.5×3H), 1.00 (t, J = 7.0 Hz, 0.5×3H)
ppm.
3
C6H5, C6H5
4
C6H5, C6H5
5
C6H5, C6H5
6
C6H5, C6H5
7
C6H5, C6H5
8
C6H5, C6H5
9
C6H5, CH3
C6H5, C6H5
10
11c
12
13
14
C6H5, OEt
C6H5, C6H5
CH3, OEt
C6H5, C6H5
C6H5, C6H5
4-CH3C6H4, C6H5
4-CH3C6H4, 4-CH3C6H5
4-BrC6H4, 4-BrC6H4
C6H5, C6H5
C6H5, C6H5
a 0.5 mmol 1, 0.6 mmol 2, 1.2 mLClCH2CH2Cl, 5 mol% DDQ,
10 mol% NHPI, 10 mol% CuBr, 10 mol% NiCl2, 24h, 80 °C.
b Isolation yield.
c 4 mmol 2.
Alkylation of 1,3-diarylpropenes; general procedure
DDQ (5 mol%), NHPI(10 mol%), CuBr (10 mol%), NiCl2 (10 mol%)
were added to a stirred suspension of 1,3-dicarbonyl compound (1,
0.5 mmol) and 1,3-diarylpropene (2, 0.6 mmol) in 1,2-dichloroethane
(1.2 mL) at 80 °C for 24 h. After completion of the reaction, 1,2-
dichloroethane was removed under reduced pressure. The residue
obtained was purified through silica gel using petroleum ether/ethyl
acetate (20:1–10:1) as an eluent.
2-[(2E)-1,3-Diphenylprop-2-en-1-yl]-1,3-diphenylpropane-1,3-
dione (3a): Solid, m.p. 124–126 °C (lit.19 123–125 °C). H NMR
1
2-[(2E)-1-(4-methylphenyl)-3-phenylprop-2-en-1-yl]-1,3-diphe-
nylpropane-1,3-dione (3l): Solid, m.p. 135–137 °C (lit.19 137–
(500 MHz, CDCl3): δ 8.07–8.05 (m, 2H), 7.84 (d, J = 7.4 Hz, 2H),
7.56 (t, J = 7.4 Hz, 1H), 7.49–7.45 (m, 3H), 7.38–7.33 (m, 4H), 7.28–
7.10 (m, 8H), 6.38–6.30 (m, 2H), 5.99 (d, J = 10.5 Hz, 1H), 4.82 (dd,
J = 6.9, 10.5 Hz, 1H) ppm.
2-[(2E)-1,3-diphenylprop-2-en-1-yl]-1-(4-methylphenyl)-3-
phenylpropane-1,3-dione (3b): Solid, m.p. 120–122 °C. H NMR
1
139 °C). H NMR (500 MHz, CDCl3): δ 8.06 (d, J = 8.5 Hz, 2H),
7.87–7.83 (m, 2H), 7.58–7.55 (m, 1H), 7.48–7.45 (m, 3H), 7.37–7.33
(m, 3H), 7.27–7.00 (m, 8H), 6.36–6.24 (m, 2H), 5.99, 5.97 (dd,
J = 10.5, 10.5 Hz, 1H), 4.83–4.78 (m, 1H), 2.28 (s, 0.5×3H), 2.25 (s,
0.5×3H) ppm.
1
2-[(2E)-1,3-Bis(4-methylphenyl)prop-2-en-1-yl]-1,3-diphenylpro-
pane-1,3-dione (3m): Solid, m.p. 156–158 °C (lit.30 159–163 °C).1H
NMR (500 MHz, CDCl3): δ 8.05 (d, J = 7.5 Hz, 2H), 7.86–7.85 (m,
2H), 7.58–7.55 (m, 1H), 7.49–7.44 (m, 3H), 7.37–7.34 (m, 2H), 7.26–
7.24 (m, 2H), 7.05 (d, J = 7.5 Hz, 4H), 6.98 (s, 2H), 6.31–6.22 (m,
2H), 5.97 (d, J = 11.0 Hz, 1H), 4.79–4.76 (m, 1H), 2.27 (s, 3H), 2.25
(s, 3H) ppm.
(500 MHz, CDCl3): 8.05 (d, J = 7.5 Hz, 1H), 7.96 (d, J = 8.0 Hz, 1H),
7.83 (d, J = 7.5 Hz, 1H), 7.76 (d, J = 8.0 Hz, 1H), 7.56–7.44 (m, 2H),
7.37–7.32 (m, 3H), 7.26–7.09 (m, 10H), 6.34–6.32 (m, 2H), 5.95 (d,
J = 10.5 Hz, 1H), 4.81 (dd, J = 7.0, 10.5 Hz, 1H), 2.40 (s, 0.5×3H),
2.35 (s, 0.5×3H) ppm. 13C NMR (125 MHz, CDCl3): 195.2, 195.1,
144.5, 144.3, 141.1, 137.4, 137.0, 134.8, 134.4, 133.4, 133.2, 131.8,
131.75, 130.1, 130.07, 129.7, 129.4, 129.0, 128.9, 128.85, 128.78,
128.67, 128.61, 128.58, 128.4, 127.3, 127.2, 126.9, 126.3, 62.6, 50.03,
50.0, 21.72, 21.66 ppm. IR (KBr): 1689, 1605, 1494, 1447, 1262,
1179, 966, 745, 696 cm−1. ESI-MS: m/z = 453 [M+Na]. Anal. Calc. for
C31H26O2: C, 86.48; H, 6.09. Found: C, 86.59; H, 6.21%.
2-[(2E)-1,3-Diphenylprop-2-en-1-yl]-1-(4-methoxylphenyl)-3-
phenylpropane-1,3-dione (3c): Solid, m.p. 173–175 °C (lit.19 172–
174 °C). 1H NMR (500 MHz, CDCl3): δ 8.05–8.04 (m, 2H), 7.87–7.83
(m, 2H), 7.56–7.54 (m, 0.5×1H), 7.47–7.44 (m, 1+0.5×1H), 7.36–7.33
(m, 3H), 7.25–7.11 (m, 8H), 6.94–6.92 (m, 1H), 6.83–6.81 (m, 1H),
6.34–6.32 (m, 2H), 5.90 (d, J = 10.5 Hz, 1H), 4.82 (dd, J = 6.5, 10.5
Hz, 1H), 3.86 (s, 0.5×3H), 3.82 (s, 0.5×3H) ppm.
2-[(2E)-1,3-Bis(4-bromophenyl)prop-2-en-1-yl]-1,3-diphenylpro-
1
pane-1,3-dione (3n): Solid, m.p. 187–189 °C. H NMR (500 MHz,
CDCl3): δ 8.03 (d, J = 7.5 Hz, 2H), 7.84 (d, J = 7.5 Hz, 2H), 7.58 (t,
J = 7.5 Hz, 1H), 7.52–7.45 (m, 3H), 7.38–7.28 (m, 6H), 7.23 (d,
J = 8.5 Hz, 2H), 6.94 (d, J = 8.5 Hz, 2H), 6.25–6.24 (m, 2H), 5.90 (d,
J = 10.5 Hz, 1H), 4.78–4.74 (m, 1H). 13C NMR (125MHz, CDCl3):
194.2, 193.4, 139.8, 137.1, 136.6, 135.6, 133.7, 133.5, 131.8, 131.5,
131.1, 130.1, 130.0, 129.0, 128.8, 128.7, 128.5, 127.8, 121.3, 120.9,
62.4, 49.3. IR (KBr): 1691, 1659, 1594, 1486, 1384, 1260, 1072,
1010, 806, 709, 685 cm−1. ESI-MS: m/z = 595 [M+Na]. Anal. Calcd
for C30H22Br2O2: C, 62.74; H, 3.86. Found: C, 62.85; H, 3.71%.
2-[(2E)-1,3-Diphenylprop-2-en-1-yl]-1-(3-methoxylphenyl)-3-
phenylpropane-1,3-dione (3d): Solid, m.p. 97–99 °C (lit.19 99–
101 °C). 1H NMR (500 MHz, CDCl3): δ 8.07–8.05 (m, 1H), 7.85–7.83
(m, 1H), 7.69–7.68 (m, 0.5×1H), 7.57–7.09 (m, 16H), 7.04–7.02 (m,
0.5×1H), 6.38–6.32 (m, 2H), 6.00, 5.97 (dd, J = 10.5, 10.0 Hz, 1H),
4.82 (dd, J = 7.5, 10.5 Hz, 1H), 3.75 (s, 0.5×3H), 3.73 (s, 0.5×3H)
ppm.
2-[(2E)-1,3-Diphenylprop-2-en-1-yl]-1-(4-chlorophenyl)-3-phenyl-
propane-1,3-dione (3e): Solid, m.p. 189–191 °C (lit.19 190–192 °C).
1H NMR (500 MHz, CDCl3): δ 8.05–8.03 (m, 1H), 7.99 (d, J = 8.6 Hz,
1H), 7.83–7.82 (m, 1H), 7.77 (d, J = 8.6 Hz, 1H), 7.58–7.10 (m, 15H),
6.38–6.31 (m, 2H), 5.90, 5.89 (dd, J = 10.7, 10.5 Hz, 1H), 4.81 (dd,
J = 7.5, 10.5 Hz, 1H) ppm.
This work was supported by the Research Fund of Zhejiang
University of Technology (1001116044408).
Received 27 August 2012; accepted 16 October 2012
Paper 1201484 doi: 10.3184/174751912X13527292608404
Published online: 5 December 2012
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