A highly stereoselective synthesis of stilbenes under solvent-free conditions

Article abstract of DOI:10.3184/030823410X12814419570511

A highly stereoselective synthesis of stilbenes (trans-1,2-diarylethylenes) was achieved under solvent-free conditions from aryl-aldehydes and aromatic substances bearing an activated methyl group in the presence of anhydrous K ₂CO₃ and poly(ethylene glycol). This method avoided the need for completely anhydrous condition and use of a noxious organic solvent.

Full text of DOI:10.3184/030823410X12814419570511

JOURNAL OF CHEMICAL RESEARCH 2010
RESEARCH PAPER 489
SEPTEMBER, 489–492
A highly stereoselective synthesis of stilbenes under solvent-free
conditions
Xia-Bing Lia, Li Wanga, Xi-Quan Zhangb, Hong-Mei Gub, Jian Guoa and Bao-Lin Lia*
a Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, and School of Chemistry and
Materials Science, Shaanxi Normal University, Xi’an 710062, P. R. China
b Jiangsu ChiaTaiTianqing Pharmaceutical Co., Ltd. Nanjing 210018, P. R. China
A highly stereoselective synthesis of stilbenes (trans-1,2-diarylethylenes) was achieved under solvent-free conditions
from aryl-aldehydes and aromatic substances bearing an activated methyl group in the presence of anhydrous K2CO3
and poly(ethylene glycol). This method avoided the need for completely anhydrous condition and use of a noxious
organic solvent.
Keywords: trans-stilbenes, trans-1,2-diarylethylenes, stereoselectivity, Knoevenagel type condensation, solvent-free condition
Stilbenes (1,2-diarylethylenes) are very useful chemical
substances which are used as liquid crystal materials,1 fluores-
cence reagents2 and anti-tumour drugs including resveratrol
(3,4′,5-trihydroxystilbene)3–5 and pterostilbene (3,5-dime-
thoxy-4′-hydroxystilbene).6 They are also important building
blocks with applications in materials science and synthetic
chemistry since their E/Z isomerisation, cyclisation, cyclodi-
merisation, and statistical C–C bond formations (polymerisa-
tion, crosslinking) offer various reaction possibilities.7 Interest
in the drug synthesis and evaluation of 1,2-diaryl ethylenes
as potential anticancer agents stems from the discovery of
many such natural products as antimitotic and antileukemic
agents.8–10 This includes the isolation of some polymethoxyl-
ated stilbene derivatives, termed combretastatins, from the
South African tree Combretum caffrum. Many of these com-
bretastatins were found to be cytotoxic, with combretastatin
A-4 the most potent.11 This compound was found to cause
mitotic arrest in L1210 murine leukemia cells, inhibit tubulin
polymerisation, and competitively inhibit the binding of radio-
labeled colchicine to tubulin.12 Therefore, in order to obtain
new 1,2-diarylethylenes with antitumour activity, we have
separation to give the corresponding trans-3,4,5-trimethoxy-
4′-nitrostilbene in 44% yield.11 There are three obvious
drawbacks in this route: the phosphonium bromide is sensitive
to moisture, thus the reaction requires anhydrous condition
and an argon atmosphere; the low stereoselectivity of reaction
gave
a mixture of cis- and trans-3,4,5-trimethoxy-4′-
nitrostilbene and there is a low reaction overall yield. To
overcome these disadvantages, we attempted to find a new
synthesis method for trans-3,4,5-trimethoxy-4′-nitrostilbene.
For the synthesis of trans-3,4,5-trimethoxy-4′-nitrostilbene,
we used Zou’s method for the synthesis of pterostilbene,17 in
which a mixture of 10 mmol 3,4,5-trimethoxybenzaldehyde
and 20 mmol of the activated methyl compound, p-nitrotolu-
ene, was refluxed in dry methanol in the presence of sodium
methoxide for 48 h to give (E)-3,4,5-trimethoxy-4′-nitrostil-
bene in 39% yield. The base, sodium methoxide, was neces-
sary for this reaction. This removes a proton from the activated
methyl group of p-nitrotoluene to yield a nucleophilic carban-
ion. The double bond is formed by the nucleophilic addition
of this carbanion to the carbonyl of 3,4,5-trimethoxybenzalde-
hyde followed by dehydration. However, this process still
requires anhydrous conditions and a long time, and gave a low
yield.
Some reactions can be achieved in high yield and shorter
time by grinding under solvent-free condition.18 Therefore
we ground the mixture of 3,4,5-trimethoxybenzaldehyde, p-
nitrotoluene and anhydrous K2CO3 to explore the solvent-free
synthesis of 3,4,5-trimethoxy-4′-nitrostilbene, but the reaction
did not occur, possibly because K2CO3 did not adequately react
with the p-nitrotoluene to remove the proton of the methyl
group in the solid. Polyethylene glycols (PEGs) have been
widely used as phase transfer catalyst in many organic reac-
tions19,20 because of their stability, low cost, environment-
friendly and easy availability. PEG can effectively catalyse the
reactions of K+ or Na+ participation.21 Thus Cao’s group used
PEG-400 and K2CO3 as catalysts to explore Knoevenagel con-
densation of aromatic aldehydes with ethyl cyanoacetate as
active methylene compounds under solvent-free conditions,
and successfully achieved an efficient synthesis of mono-aryli-
dene compounds.22 In our exploration of the synthesis of stil-
benes (diarylidene compounds), when PEG-400 was added as
a phase transfer catalyst to the mixture of 3,4,5-trimethoxy-
benzaldehyde, p-nitrotoluene and anhydrous K2CO3, the colour
of the mixture changed immediately from white to yellow,
which showed the reaction has occured. After adequately
grinding and leaving the mixture for 24 h, 3,4,5-trimethoxy-4′-
nitrostilbene was identified by TLC. The nondehydrated prod-
uct, 1-(3,4,5-trimethoxyphenyl)-2-(4-nitrophenyl)ethanol, was
observed from the 1H NMR spectrum of the resultant mixture.
The molar ratio of the dehydrated and nondehydrated products
was about 1:8 based on the integral ratio between resonance
synthesised
a series of trans-4′-alkyloylimino-3,4,5-tri-
methoxystilbene13 and 4′–O-substituted derivatives of trans-
4′-hydroxy-3,4,5-trimethoxystilbene14,15 from trans-3,4,5-
trimethoxy-4′-nitrostilbene as a key intermediate. To the best
of our knowledge, the preparation of this key intermediate and
analogues, 1,2-diaryl ethylenes, requires anhydrous conditions
and affords low yields. Wang’s group reported a method for
the synthesis of hemicyanine dyes through the condensation
of activated aromatic methyl groups with aldehydes in the
presence of piperidine under microwave irradiation,16 this pro-
cess was not adaptable to the preparation of these stilbenes and
its analogue on a larger scale. Recently we have found a highly
stereoselective synthesis for these 1,2-diaryl ethylenes which
is described here.
Results and discussion
We are interested in the synthesis of stilbenes (1,2-diaryl
ethylenes) with antitumour activity. Firstly, A key intermedi-
ate, trans-3,4,5-trimethoxy-4′-nitrostilbene, was required for
our work. Cushman’s group, synthesised a series of methoxyl-
ated stilbenes and related compounds for evaluation as cyto-
toxic agents and inhibitors of tubulin polymerisation, using the
Wittig reaction of 3,4,5-trimethoxybenzyltriphenyl phospho-
nium bromide with p-nitrobenzaldehyde in the presence of
sodium hydride in benzene under an argon atmosphere for
16 h. This gave a mixture of cis- and trans-3,4,5-trimethoxy-
4′-nitrostilbene, which was followed by preparative TLC
* Correspondent. E-mail: baolinli@snnu.edu.cn

490 JOURNAL OF CHEMICAL RESEARCH 2010
trans-3,4,5-Trimethoxy-4′-nitrostilbene (entry 1 of Table 1): M.p.
192–194 °C; 1H NMR (300 MHz, CDCl3): δ 3.89 (s, 3H, OCH3), 3.93
(s, 6H, 2OCH3), 6.77 (s, 2H, 2,6-ArH), 7.07 (d, 1H, J = 16.2 Hz,
–CH=CH–), 7.17 (d, 1H, J = 16.2 Hz, –CH=CH–), 7.64 (d, 2H, J =
8.6 Hz, 2′,6′-ArH), 8.24 (d, 2H, J = 8.6 Hz, 3′,5′-ArH); 13C NMR
(75 MHz, CDCl3): δ 56.2, 60.9, 104.4, 124.1, 125.7, 126.7, 131.8,
133.3, 139.2, 143.8, 146.7, 153.6; IR: νmax 3066, 2928, 2831, 1633,
1587, 1503, 1454, 1329, 1236, 1122, 980 cm−1. Anal. Calcd for
C17H17NO5: C, 64.75; H, 5.43; N, 4.44. Found: C, 64.77; H, 5.39; N,
4.43%.
peaks at δ 7.07 for the proton of the double bond of 3,4,5-tri-
methoxy-4′-nitrostilbene and at δ 4.87 of the proton at the
1-position of the methine of 1-(3,4,5-trimethoxyphenyl)-2-
(4-nitrophenyl)ethanol. This was further confirmed by the 1H,
13C, DEPT NMR spectra of the isolated product from silica gel
column chromatographic separation of the mixture eluted with
a mixture of ethyl acetate and petroleum ether, v/v =1:1. This
result led us to further explore this process.
Since p-nitrotoluene has low melting point (54.5 °C), we
examined the condensation reaction of 3,4,5-trimethoxybenz-
aldehyde with p-nitrotoluene in the presence of anhydrous
K2CO3 and PEG-400 when the mixture was heated up to the
melting point of p-nitrotoluene, i.e. using p-nitrotoluene as
both a reactant and a solvent. A good result was obtained when
the mixture of 10.0 mmol 3,4,5-trimethoxybenzaldehyde,
10.0 mmol p-nitrotoluene, 20.0 mmol anhydrous K2CO3 and
1.0 mL PGE-400 was heated to 100 °C with magnetic stirring
for 3 h. After the addition of water to the mixture, filtration and
recrystallising from ethanol, 3,4,5-trimethoxy-4′-nitrostilbene
was obtained in 85% yield (see entry 1 of Table 1). The trans
isomer was obtained exclusively by this simple process
without the need for chromatographic separation. This was
confirmed by the characteristic coupling constant in the NMR
spectrum of 3,4,5-trimethoxy-4′-nitrostilbene for the olefinic
protons of 16.2 Hz.23 This method has a remarkable advantage
compared to the previous methods, such as its high stereose-
lectivity for the trans isomer, and completely avoiding anhy-
drous condition and the use of noxious organic solvent.
This procedure using solvent-free conditions was success-
fully applied to the stereoselective synthesis of other trans-1,2-
diarylethylenes from aryl aldehydes and aromatic substances
bearing activated methyl groups (see Table 1). The results indi-
cated that the yields of compounds bearing electron donating
groups on the aromatic ring of the aldehyde were higher than
those of electron withdrawing groups on the aromatic ring.
Higher yields were obtained when there were more electron
donating groups on the aromatic ring of aldehyde (entries 1–5
and 7). Although there were more electron donating groups on
the aromatic ring of the aldehydes in entries 8–10, lower yields
were obtained because of the steric hindrance of the nitro
group in the ortho position (entry 8) or two methyl groups in
the ortho position of the activated methyl (entries 9 and 10).
In summary, an effective synthesis method of trans-1,2-dia-
rylethylenes was achieved under solvent-free conditions from
aryl-aldehydes and aromatic substances bearing an activated
methyl group in the presence of anhydrous K2CO3 and the
phase transfer catalyst PEG. This method avoided the need
for completely anhydrous conditions and the use of noxious
organic solvents, and it exhibited a high stereoselectivity for
the trans configuration of the 1,2-diaryl ethylene compounds.
trans-3,4-Dimethoxy-4′-nitrostilbene (entry 2 of Table 1): M.p.
131.3–132.5 °C; 1H NMR (300 MHz, CDCl3): δ 3.92 (s, 3H, –OCH3),
3.96 (s, 3H, –OCH3), 6.90 (d, 1H, J = 8.5 Hz, 5-ArH), 7.03 (d, 1H,
J = 16.2 Hz, –CH=CH–), 7.09 (d, 1H, J = 8.5 Hz, 6-ArH), 7.09 (s, 1H,
2-ArH), 7.24 (d, 1H, J = 16.2 Hz, –CH=CH–), 7.61 (d, 2H, J = 8.7
Hz, 2′,6′-ArH), 8.22 (d, 2H, J = 8.7 Hz, 3′,5′-ArH); 13C NMR (75MHz,
CDCl3): δ 55.9, 56.0, 109.2, 111.4, 120.9, 124.1, 124.3, 126.5, 129.4,
133.2, 144.2, 149.4, 150.1; IR: νmax1508, 1462, 1259, 1633, 1587,
1503, 1454, 1329, 1236, 1122, 962 cm−1. Anal. Calcd for C16H15NO4:
C, 67.36; H, 5.30; N, 4.91. Found: C, 67.56; H, 5.50; N, 4.81%.
trans-4-Methoxy-4′-nitrostilbene (entry 3 of Table 1): M.p. 130.0–
131.8 °C; 1H NMR (300 MHz, CDCl3): δ 3.85 (s, 3H, OCH3), 6.93 (d,
2H, J = 8.6 Hz, 3,5-ArH), 7.00 (d, 1H, J = 16.6 Hz, –CH=CH–), 7.20
(d, 1H, J = 16.6 Hz, –CH=CH–), 7.49 (d, 2H, J = 8.6 Hz, 2,6-ArH),
7.84 (d, 2H, J = 7.7 Hz, 2′,6′-ArH), 8.20 (d, 2H, J = 7.7 Hz, 3′,5′-
ArH); 13C NMR (75 MHz, CDCl3): δ 54.3, 113.3, 123.1, 125.4, 127.3,
127.9, 131.9, 143.2, 145.4, 159.2; IR: νmax 3026, 2917, 1584, 1505,
1331, 1248, 1171, 1102, 1023, 961 cm−1. Anal. Calcd for C15H13NO3:
C, 70.58; H, 5.13; N, 5.49. Found: C, 71.19; H, 5.24; N, 5.33%.
trans-4-(N,N-Dimethylamino)-4′-nitrostilbene (entry 4 of Table 1):
1
M.p. 152.0–153.8 °C; H NMR (300 MHz, CDCl3): δ 3.02 (s, 6H,
N(CH3)2), 6.72 (d, 2H, J = 8.1 Hz, 2,6-ArH), 6.93 (d, 1H, J = 16.1 Hz,
–CH=CH–), 7.16 (d, 1H, J = 16.1 Hz, –CH=CH–), 7.45 (d, 2H, J = 8.1
Hz, 3,5-ArH), 7.56 (d, 2H, J = 8.2 Hz, 2′,6′-ArH), 8.18 (d, 2H, J = 8.1
Hz, 3′,5′-ArH); 13C NMR (75 MHz, CDCl3): δ 39.2, 111.2, 120.6,
123.1, 123.2, 125.0, 126.4, 127.3, 127.8, 129.6, 132.6; IR: νmax 3031,
2914, 1586, 1507, 1331, 1177, 1112, 962 cm−1. Anal. Calcd for
C16H16N2O2: C, 71.62; H, 6.01; N, 10.44. Found: C, 71.58; H, 6.19;
N, 10.71%.
trans-4-nitrostilbene (entry 5 of Table 1): M.p. 136.0–138.0 °C;
1H NMR (300 MHz, CDCl3): δ 7.17 (m, 1H, 4′-ArH), 7.30 (d, 1H,
J = 16.2 Hz, –CH=CH–), 7.33 (d, 1H, J = 16.2 Hz, –CH=CH–), 7.41
(d, 2H, J = 7.3 Hz, 3, 5-ArH), 7.55 (d, 2H, J = 7.3 Hz, 2, 6-ArH), 7.63
(d, 2H, J=8.2 Hz, 2′, 6′-ArH), 8.22 (d, 2H, J=8.2 Hz, 3′, 5′-ArH); IR:
νmax 2909, 1638, 1583, 1512, 1430, 1331, 1107, 964 cm−1. Anal. Calcd
for C14H11NO2: C, 74.65; H, 4.92; N, 6.22. Found: C, 74.89; H, 4.78;
N, 6.36%.
trans-2-(4-Nitrostyryl)furan (entry 6 of Table 1): M.p. 129.8–131.4
1
°C; H NMR (300 MHz, CDCl3): δ 6.48 (d, 2H, J = 2.5 Hz, 3,4-H),
7.02 (br s, 2H, –CH=CH– and 5-H), 7.46 (d, 1H, J = 16.1 Hz,
–CH=CH–), 7.57 (d, 2H, J = 8.4 Hz, 2′,6′-ArH), 8.20 (d, 2H, J =
8.4 Hz, 3′, 5′-ArH); IR: νmax 2915, 1578, 1501, 1320, 1106, 1019, 958,
854 cm−1. Anal. Calcd for C12H9NO3: C, 66.97; H, 4.22; N, 6.51.
Found: C, 66.71; H, 4.23; N, 6.49%.
trans-4,4′-Dinitrostilbene (entry 7 of Table 1): M.p. 117.2–118.9
°C; 1H NMR (300 MHz, CDCl3): δ 7.30 (s, 2H, –CH=CH–), 7.69 (d,
4H, J = 7.6 Hz, 2,2′,6,6′-ArH), 8.27 (d, 4H, J = 7.6 Hz, 3,3′,5,5′-ArH);
13C NMR (75 MHz, CDCl3): δ 124.6, 128.5, 131.4, 143.5, 146.1. IR:
νmax 3106, 2926, 1600, 1501, 1331, 1106, 964 cm−1. Anal. Calcd for
C14H10N2O4: C, 62.22; H, 3.73; N, 10.37. Found: C, 62.39; H, 3.65; N,
10.45%.
trans-3,4,5-Trimethoxy-2′-nitrostilbene (entry 8 of Table 1): M.p.
127.0–128.5 °C; 1H NMR (300 MHz, CDCl3): δ 3.88 (s, 3H, OCH3),
3.92 (s, 6H, 2–OCH3), 6.76 (s, 2H, 2,6-ArH), 7.02 (d, 1H, J = 16.0 Hz,
–CH=CH–), 7.41 (m, 1H, 4′-ArH), 7.50 (d, 1H, J = 16.0 Hz,
–CH=CH–), 7.61 (m, 1H, 5′-ArH), 7.76 (d, 1H, J = 7.46 Hz, 6′-ArH),
7.97 (d, 1H, J = 7.93 Hz, 3′-ArH); 13C NMR (75 MHz, CDCl3): δ 56.2,
60.9, 103.3, 118.9, 121.9, 122.0, 126.8, 127.0, 132.0, 132.8, 139.2,
143.8, 146.7, 153.6; IR: νmax 3021, 1582, 1515, 1462, 140, 1341, 1250,
1121, 997 cm−1. Anal. Calcd for C17H17NO5: C, 64.75; H, 5.43; N,
4.44. Found: C, 64.77; H, 5.39; N, 4.43%.
trans-2-(3,4,5-Trimethoxystyryl)-3,3-dimethyl-3H-benzo[e]indole
(entry 9 of Table 1): M.p. 157.2–158.1 °C; 1H NMR (300 MHz,
CDCl3): δ 1.73 (s, 6H, –CH3), 3.92 (s, 3H, –OCH3), 3.94 (s, 6H,
–OCH3), 6.76 (s, 2H, ArH), 7.06 (d, 1H, J = 16.2 Hz, –CH=CH–),
7.49 (m, 1H, ArH), 7.58 (m, 1H, ArH), 7.75 (d, 1H, J = 16.2 Hz,
Experimental
All chemicals were of analytical reagent grade. The NMR spectra
were recorded with a Bruker AVANCE300 spectrometer using TMS
as internal standard. The IR spectra were recorded with a Nicolet
170SX FT-IR spectrometer using KBr pellets. Elemental analyses
were performed on a VarioEL CHNS Elementar Analysensystem. The
melting point were determined using a WRS-113 digital melting point
instrument (the thermometer was not corrected).
Synthesis of trans-1,2-diaryl ethylene compounds
The aryl aldehyde (10.0 mmol) was added to the mixture of aro-
matic substance bearing the activated methyl (10.0 mmol), anhydrous
K2CO3 (20.0 mmol) and PGE-400 (0.5–1.0 mL) (or 1 g PGE-600 or
1 g PEG-1000) in a 50 mL flask and the mixture was heated to 90–
100 °C with magnetic stirring for 2–4.5 h. Water (10 mL) was added
to the mixture and the product was filtered. The filter cake was rinsed
with H2O (5 mL × 3) and recrystallised from ethanol to give trans-1,2-
diaryl ethylene compounds as a solid.

JOURNAL OF CHEMICAL RESEARCH 2010 491
Table 1 Synthesis of trans-1,2-diaryl ethylenes under solvent-free conditionsa
Entry
1
Ar
Ar’
Temperature/°C
100
Time/h
3.0
Yield/%b
85
2
100
3.0
81
3
100
100
90
3.0
3.0
2.0
2.0
2.0
74
82
71
89
50
4
5
6
90
7c
90
8d
100
100
100
2.5
4.5
4.0
26
35
38
9
10
aReactions performed with 10 mmol of aryl-aldehydes, 10 mmol of aromatic substances bearing activity methyl, 20 mmol of anhy-
drous K2CO3 and 0.5–1.0 mL of PEG-400 under solvent-free conditions.
bIsolated yields after recrystallisation.
c1.0 g PEG-1000 was used as phase transfer catalyst.
d1.0 g PEG-600 was used as phase transfer catalyst.
–CH=CH–), 7.88 (d, 2H, J = 3.9 Hz, ArH), 7.96 (1H, J = 7.80 Hz,
ArH), 8.07 (d, 1H, J = 7.80 Hz, ArH); 13C NMR (75 MHz, CDCl3):
δ 23.4, 54.4, 56.2, 61.0, 104.7, 118.9, 120.3, 122.8, 124.6, 126.4,
128.5, 129.2, 129.8, 131.7, 132.6, 137.7, 137.8, 153.5, 184.9; IR: νmax
3057, 2920, 1572, 1506, 1452, 1413, 1342, 1238, 1117, 1001 cm−1.
Anal. Calcd for C25H25NO3: C, 77.49; H, 6.50; N, 3.61. Found: C,
77.37; H, 6.58; N, 3.43%.
20.0 mmol) and PGE-400 (0.5 mL) were ground thoroughly in a por-
celain mortar in room temperature. After leaving the mixture for 24 h,
water (10 mL) was added to the mixture and the product was filtered.
The filter cake was rinsed with H2O (5 mL × 3). The resultant was
separated by silica gel column chromatography (eluted with the
mixture of ethyl acetate and petroleum ether, v/v =1:1) to give 1.9 g
of 1-(3,4,5-trimethoxyphenyl)-2-(4-nitrophenyl)ethanol as a yellow
1
trans-2-(3,4,5-Trimethoxystyryl)-3,3-dimethyl-3H-indoleninium-5-
solid. M.p. 122.0–123.0 °C; H NMR (300 MHz, CDCl3): δ 2.11
1
sulfonate (entry 10 of Table 1): M.p. >300 °C; H NMR (300 MHz,
(s, 1H, OH), 3.12 (d, 2H, J = 6.9 Hz, CH2), 3.83 (s, 9H, OCH3), 4.87
(t, 1H, J = 6.9 Hz, CH), 6.52 (s, 2H, 2, 6-ArH), 7.34 (d, 2H, J =
8.4 Hz, 2′, 6′-ArH), 8.12 (d, 2H, J = 8.4 Hz, 3′, 5′-ArH); 13C NMR
(75 MHz, CDCl3): δ 45.5, 56.2, 60.9, 75.0, 102.8, 123.4, 130.4, 137.7,
139.1, 146.0, 146.8, 153.4; IR: νmax 3477, 2926, 2846, 1595, 1511,
1458, 1336, 1233, 1119, 964 cm−1.
D2O): δ 1.06 (s, 6H, C(CH3)2), 3.38 (s, 3H, –OCH3), 3.46 (s, 6H,
–OCH3), 6.40 (s, 2H, ArH), 6.50 (d, 1H, J = 16.5 Hz, CH=CH), 7.08–
7.13 (m, 2H, ArH), 7.50 (d, 1H, J = 8.1 Hz, ArH), 7.56 (s, 1H, ArH);
13C NMR (75 MHz, D2O): δ 22.8, 52.9, 56.0, 60.9, 105.2, 118.3,
119.0, 119.4, 125.9, 131.6, 138.4, 134.0, 140.3, 147.0, 152.5, 154.3,
186.7; IR: νmax1611, 1564, 1311, 1236, 1105, 1023, 975 cm−1. Anal.
Calcd for C21H23NO6S: C, 60.42; H, 5.55; N, 3.36. Found: C, 60.25;
H, 5.43; N, 3.42%.
The authors are thankful for financial support from the National
Natural Science Foundation of China (No. 20972090), and
Jiangsu Chia Tai Tianqing Pharmaceutical Co., Ltd., P. R.
China.
Synthesis of 1-(3,4,5-trimethoxyphenyl)-2-(4-nitrophenyl)ethanol
A mixture of 3,4,5-trimethoxybenzaldehyde (1.96 g, 10.0 mmol),
p-nitrotoluene (1.37 g, 10.0 mmol), anhydrous K2CO3 (2.76 g,

492 JOURNAL OF CHEMICAL RESEARCH 2010
11 M. Cushman, D. Nagarathnam, D. Gopal, A.K. Chakraborti, C.M. Lin and
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12 C.M. Lin, S.B. Singh, P.S. Chu, R.O. Dempcy, J.M. Schmidt, G.R. Pettit
Received 23 May 2010; accepted 23 July 2010
Paper 1000153 doi: 10.3184/030823410X12814419570511
Published online: 7 October 2010
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