Glycerol as an alternative green reaction medium for multicomponent reactions using PS-PEG-OSO3H as catalyst

Article abstract of DOI:10.1080/00397911.2010.517373

Development of green solvents from renewable resources has gained much attention recently, because of the extensive uses of solvents in almost all of the chemical industry and the predicted disappearance of fossil oil. Here we show that glycerol and PS-PE

Full text of DOI:10.1080/00397911.2010.517373

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Glycerol as an Alternative Green
Reaction Medium for Multicomponent
Reactions Using PS-PEG-OSO3H as
Catalyst
Zheng-Jun Quan a b , Rong-Guo Ren a b , Yu-Xia Da a b , Zhang Zhang a
b & Xi-Cun Wang a b
a Key Laboratory of Environment-Related Polymer Materials, Ministry
of Education, China
b Gansu Key Laboratory of Polymer Materials, College of Chemistry
and Chemical Engineering, Northwest Normal University, Lanzhou,
China
Version of record first published: 11 Jul 2011
To cite this article: Zheng-Jun Quan, Rong-Guo Ren, Yu-Xia Da, Zhang Zhang & Xi-Cun Wang (2011):
Glycerol as an Alternative Green Reaction Medium for Multicomponent Reactions Using PS-PEG-
OSO3H as Catalyst, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 41:20, 3106-3116
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Synthetic Communications1, 41: 3106–3116, 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.517373
GLYCEROL AS AN ALTERNATIVE GREEN REACTION
MEDIUM FOR MULTICOMPONENT REACTIONS USING
PS-PEG-OSO3H AS CATALYST
Zheng-Jun Quan, Rong-Guo Ren, Yu-Xia Da,
Zhang Zhang, and Xi-Cun Wang
Key Laboratory of Environment-Related Polymer Materials,
Ministry of Education, China and Gansu Key Laboratory of Polymer
Materials, College of Chemistry and Chemical Engineering, Northwest
Normal University, Lanzhou, China
GRAPHICAL ABSTRACT
Abstract Development of green solvents from renewable resources has gained much
attention recently, because of the extensive uses of solvents in almost all of the chemical
industry and the predicted disappearance of fossil oil. Here we show that glycerol and
PS-PEGOSO3H as a green and recyclable catalyst system were used in the multicomponent
reactions for the synthesis of 3,4-dihydropyrimidinones, amidoalkyl naphthols, and diben-
zoxanthenes, respectively. Excellent products yields and good recyclability of catalyst
and glycerol were achieved. It demonstrates that glycerol is a renewable and recyclable
green solvent that is nontoxic, biodegradable, and able to dissolve organic substrates. It
was easy to isolate the reaction products by simple extraction.
Keywords 3,4-Dihydropyrimidinones; glycerol; green chemistry; polymer-supported acid
catalyst
Received February 2, 2010.
Address correspondence to Xi-Cun Wang, Gansu Key Laboratory of Polymer Materials, College
of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China. E-mail:
wangxicun@nwnu.edu.cn
3106

GLYCEROL MEDIUM FOR MCRs
3107
INTRODUCTION
The use of large volumes of volatile hazardous organic solvents in industrial
processes poses a serious threat to the environment. Thus, procedures involving
alternative benign solvents in reaction, isolation, and purification are of high priority
in industry and academic research. Solvent-free processes have been developed,[1]
which to some extent have succeeded in some organic reactions. However, in per-
forming the majority of organic transformations, solvents play a critical role in mix-
ing the ingredients to be more efficient. The solvent can also deliver the thermal
energy needed for the reaction. In addition, the choice of solvent may affect the reac-
tion activity and selectivity. Meanwhile, using water as a green solvent has also been
well documented,[2,3] but the practical utilization is limited because of the hydro-
phobic nature of organic compounds and the sensitivity of catalysts to moisture.
Ionic liquid has also been used as reaction media instead of water and organic sol-
vents. However, ionic liquids, especially imidazolium-based systems containing PF6
and BF4 anions, are toxic in nature as they liberate hazardous HF, and their high
cost and disposability make their utility limited.[4–6]
Glycerol as a green solvent, previously uncharted, has become an emerging
field recently.[7] Wolfson’s group[8–10] and Jerome’s group
[11–12]
´ ˆ
have documented
that glycerol could be used as a green solvent for some catalytic and noncatalytic
organic transformations. As a solvent, glycerol has also promising physical and
chemical properties, which allows its use as an alternative environmentally friendly
solvent. It has a very high boiling point and negligible vapor pressure; it is stable
up to its boiling temperature, is compatible with most organic and inorganic
compounds, and does not requiring special handling or storage. In addition, like
water, glycerol is natural, highly hydrophilic, nontoxic, abundant, biodegradable,
and very cheap. Different hydrophobic solvents such as ethers and hydrocarbons,
which are immiscible in glycerol, allow removal of the products by simple extrac-
tion. Distillation of products is also feasible because of the high boiling point of
glycerol.
Multicomponent reactions (MCRs) have emerged as an important tool for
building diverse and complex organic molecules through carbon–carbon and car-
bon–hetero atom bond formations taking place in a tandem manner.[13,14] Therefore,
the design of novel MCRs has attracted great attention from research groups work-
ing in medicinal chemistry, drug discovery, and materials science. Among many
kinds of multi-component condensations, the Biginelli reaction is the most widely
exploited examples of MCRs.[15–17] We previously reported the synthesis of
Polyethylene Glycol (PEG)-bound sulfonic acid[18] and polystyrene-poly(ethylene
glycol) (PS-PEG) resin-supported sulfonic acid[19] and their utilization in the
Biginelli reaction.
The purpose of this study is to explore the scope and limitation of glycerol as
an alternative green solvent using PS-PEG-supported sulfonic acid as a catalyst in
three typical MCRs. These included the Biginelli reaction to synthesize 3,4-dihydro-
pyrimidones; reaction of amide, 2-naphthol, and aldehydes to produce amidoalkyl
naphthols; and the condensation of two molecules of 2-naphthol with one molecular
of aldehyde to produce dibenzoxanthenes.

3108
Z.-J. QUAN ET AL.
RESULTS AND DISCUSSION
PS-PEG-OSO3H was prepared according to our previous work.[19] Elemental
analysis found C 52.78%, H 6.41%, and S 11.64%, which indicated that the SO3H
group capacity of PS-PEG-OSO3H was 3.6 mmol=g. The SO3H group capacity of
PS-PEG-SO3H was found to be 3.3 mmol=g by titration using 20% NaOH aqueous
as standard solution.
First, we started the investigation of the acid-catalyzed Biginelli reaction of
acetoacetate 1a, benzaldehyde 2a, and urea 3a in glycerol. When this reaction was
performed at 100 ꢀC using acid catalysts, such as p-toluene sulfonic acid (p-TSA),
poly(ethylene glycol)-supported sulfonic acid (PEGOSO3H), PS-PEGOSO3H, and
acetic acid, the desired product 4a was obtained with 73–88% yields after 8 h
(Table 1, entries 1–4). All acids used in this reaction could effectively catalyze this
three-component reaction. When the reaction was performed without any catalyst,
the product 4a was obtained with 20% yield (entry 5). The combination solvent
system of equal amounts of glycerol with H2O and pure water were also tested
as the reaction solvents (entries 6 and 7). Because of the good recyclability, we
selected PS-PEG-OSO3H as the catalyst to perform the synthesis of compounds
4a–k (Table 2). From Table 2, it is evident that our methodology is reasonably
general and can be applied to the synthesis of 3,4-dihydropyrimidinone
derivatives.
The recyclability of the glycerol and PS-PEGOSO3H was also investigated. At
the end of the reaction, because glycerol and PS-PEGOSO3H are not soluble in the
organic phase, the product can be easily extracted with ethyl acetate. After simple
filtration and washing with ethyl acetate and ether, the recycled PS-PEGOSO3H
was used directly in the next run. The solutions were combined and washed with
Table 1. Biginelli reaction in glycerol in the presence of acid catalystsa
Entry
Catalyst
p-TSA
PEGOSO3H
Solvent
Glycerol
Yield (%)b
1
2
3
4
5
6
7
84
87
88
73
20
48c
44
Glycerol
Glycerol
Glycerol
Glycerol
Glycerol=water
Water
PS-PEGOSO3H
Acetic acid
No catalyst
PS-PEGOSO3H
PS-PEGOSO3H
a1a: 1 mmol, 2a: 1 mmol, 3a: 1.2 mmol, solvent: 2.0 g, catalyst: 30% mmol.
bIsolated yield.
cAt 120 ꢀC for 12 h.

GLYCEROL MEDIUM FOR MCRs
3109
Table 2. Biginelli reaction in glycerol using PS-PEGOSO3H as catalysta
Entry
1=Ar
3=X
Product
Yield (%)b
1
2
C6H5
O
O
O
O
O
S
4a
4b
4c
4d
4e
4f
88
82
76
85
89
84
85
81
75
88
93
4-MeOC6H4
4-NO2C6H4
2-ClC6H4
4-ClC6H4
C6H5
3
4
5
6
7
4-MeOC6H4
3-NO2C6H4
4-NO2C6H4
4-ClC6H4
4-MeC6H3
S
4g
4h
4i
8
S
9
S
10
11
S
4j
4k
S
aIsolated yield.
bReaction conditions: 1: 1 mmol, 2: 1 mmol, 3: 1.2 mmol, glycerol: 2.0 g,
PS-PEGOSO3H: 0.2 g, at 100 ꢀC for 8 h.
ethyl acetate and ether. It was then dried with anhydrous magnesium sulfate, filtered,
and concentrated under reduced pressure to give glycerol. The recycled glycerol was
used directly in the next run. The yields obtained after five cycles were comparable to
those of fresh glycerol and PS-PEGOSO3H. After the first run of the preparation of
4a, the recovered glycerol and PS-PEGOSO3H were subjected to the second use
without an additional charge of glycerol or PS-PEGOSO3H to give 4a in 74% yield.
The yields of 4a observed in the third to fifth reuses were 68%, 62%, and 60%,
respectively, demonstrating high recyclability of the PS-PEG resin-supported
sulfonic acid.
Second, the coupling reaction of amides, 2-naphthol, and aldehydes to produce
the amidoalkyl naphthols using glycerol and PS-PEGOSO3H as reaction system was
investigated. The reaction conditions were investigated in glycerol at 100 ꢀC in the
presence of various acid catalysts using the reaction of 5, 6a, and 7a as a model.
When para-toluenesulfonic acid (p-TSA) was used as catalyst in glycerol, amidoalkyl
naphthol 8a was obtained in poor yield; however, a good yield of dibenzoxanthene
9a was obtained (84%). Interestingly, we found that PEGOSO3H, and
PS-PEGOSO3H can effectively drive the condensation of amides, 2-naphthol, and
aldehydes to give amidoalkyl naphthols in good yields (86% and 80%). Only a trace
of amount of desired product 8a was detected using acetic acid as catalyst (5%).
PEG-400, water, and 1,2-dichloroethane were also studied as solvents. This reaction
could also be carried out in PEG-400 and 1,2-dichloroethane to give the products in
good yields (81% and 83%). Compared to the reaction in 1,2-dichloroethane, the
reaction in glycerol has the advantages of easy isolation of products, good recyclabil-
ity, and environmental friendliness. Other aromatic aldehydes as substrates were also

3110
Z.-J. QUAN ET AL.
Table 3. Reactions of amides, 2-naphthol, and aldehydes for amidoalkyl-
naphthols in glycerola
Entry
6=Ar
C6H5
7=R
Product
Yield (%)b
1
2
3
4
5
6
7
CH3
CH3
CH3
CH3
CH3
C6H5
C6H5
8a
8b
8c
8d
8e
8f
80
85
81
85
89
82
86
4-MeOC6H4
4-MeC6H4
4-ClC6H4
4-NO2C6H4
3-NO2C6H5
4-MeC6H3
8g
a5: 1 mmol, 6: 1 mmol, 7: 1.2 mmol, glycerol: 2.0 g, and PS-PEGOSO3H:
0.15 g.
bIsolated yield.
successfully used in this condensation, giving amidoalkyl naphthols in the presence
of PS-PEGOSO3H in glycerol (Table 3).
We then moved on to the three-component reaction of two of molecules of
2-naphthol and one molecular of aldehyde to investigate the versatility of glycerol
Table 4. Reaction of 2-naphthol and aldehydes for synthesis of dibenzoxanthenea
Entry
6=Ar
C6H5
Product
Yield (%)b
1
2
3
4
5
6
7
9a
9b
9c
9d
9e
9f
81
77
90
86
88
78
76
4-MeOC6H4
4-MeC6H4
2-ClC6H4
4-ClC6H4
3-NO2C6H4
4-NO2C6H4
9g
a5: 2 mmol, 6: 1 mmol, glycerol: 2.0 g, PS-PEGOSO3H: 0.15 g.
bIsolated yield.

GLYCEROL MEDIUM FOR MCRs
3111
in the synthesis of dibenzoxanthene. Dibenzoxanthenes (9a–g) were synthesized in
glycerol catalyzed by PS-PEGOSO3H with good yields (Table 4). In this reaction,
p-TSA, PEGOSO3H, and PS-PEGOSO3H all were shown to be greatly effective,
resulting dibenzoxanthene in good yield. Though this reaction can also be performed
in 1,2-dichloroethane or under solvent-free conditions, the product separation and
the catalyst recycling is difficult. Furthermore, the organic solvent is not environ-
mentally friendly.
CONCLUSIONS
In conclusion, we have investigated that the combination of glycerol and
PS-PEGOSO3H could be an environmentally friendly system for conducting MCRs
such as Biginelli condensation; the three-component reactions of 2-naphthol, amides,
and aldehydes; and the condensation of 2-naphthol with aldehydes (molar ratio of b-
naphthol to aryl aldehyde is 2:1). To the best of our knowledge, the utilization of
glycerol and PS-PEGOSO3H as reaction system in these three-component reactions
virtually has not been reported in the open literature. Glycerol is a safe and very
cheap green solvent. We believe that the use of glycerol as a solvent will provide
improved results compared with those observed in water, and further investigations
are currently under way in our group on this topic.
EXPERIMENTAL
Typical Procedure for Compounds 4a–k
A mixture of aldehyde 1 (1 mmol), ethyl acetoacetate 2 (1 mmol), urea or thio-
urea 3 (1.2 mmol), and PS-PEG-SO3H (0.2 g) in glycerol (2.0 g) under air was heated
at 100 ꢀC for 8 h. After the reaction, the products were extracted with ethyl acetate
(6 mL ꢁ 3). After concentration of the organic phase, the crude products were
recrystallized from EtOH to give pure compounds 4a–k.
Selected Data
1
Compound 4a. Mp: 206–207 ꢀC (lit.[20] 202–204 ꢀC). H NMR (400 MHz,
CDCl3) d: 1.14 (t, J ¼ 7.2 Hz, 3H), 2.34 (s, 3H), 4.06 (q, J ¼ 7.2 Hz, 2H), 5.37
(s, 1H,), 7.24–7.31 (m, 5H), 7.16 (brs, 1H), 7.76 (brs, 1H) ppm; IR (KBr) v: 3320,
.
3160, 3100, 2980, 1725, 1701, 1645, 1570, 1460, 1365, 1320, 1280 cmꢂ1
1
Compound 4b. Mp: 199–201 ꢀC (lit.[20] 202–204 ꢀC); H NMR (400 MHz,
DMSO-d6) d: 1.10 (t, J ¼ 7.0 Hz, 3H), 2.24 (s, 3H), 3.71 (s, 3H), 3.98 (q, J ¼ 7.0 Hz,
2H), 5.09 (s, 1H), 6.88 (d, J ¼ 8.5 Hz, 2H), 7.15 (d, J ¼ 8.6 Hz, 2H), 7.66 (brs, 1H),
9.14 (brs, 1H) ppm; IR (KBr) v: 3313, 3172, 1700, 1667, 1575, 1508, 1460 cmꢂ1
.
Compound 4c. Mp: 207–209 ꢀC (lit.[20] 207–209 ꢀC). 1H NMR (400 MHz,
DMSO-d6) d: 1.10 (t, J ¼ 7.2 Hz, 3H), 2.28 (s, 3H), 3.99 (q, J ¼ 7.2 Hz, 2H), 5.29
(s, 1H), 7.53 (d, J ¼ 8.6 Hz, 2H), 7.91 (brs, 1H), 8.23 (d, J ¼ 8.6 Hz, 2H), 9.37 (brs,
1H) ppm; IR (KBr) v: 3238, 3172, 3119, 2976, 1728, 1699, 1645, 1595, 1520,
1513 cmꢂ1
.

3112
Z.-J. QUAN ET AL.
1
Compound 4d. Mp: 221–223 ꢀC (lit.[20] 222–224 ꢀC). H NMR (400 MHz,
DMSO-d6) d: 1.02 (t, J ¼ 7.2 Hz, 3H), 2.28 (s, 3H), 3.89 (q, J ¼ 7.2 Hz, 2H), 5.61
(s, 1H), 7.29–7.38 (m, 4H), 7.71 (brs, 1H), 9.21 (brs, 1H) ppm; IR (KBr) v: 3430,
.
3331, 3112, 2979, 1723, 1688, 1524 cmꢂ1
1
Compound 4e. Mp: 212–214 ꢀC (Lit.[20] 212–214 ꢀC). H NMR (400 MHz,
DMSO-d6) d: 1.17 (t, J ¼ 7.2 Hz, 3H), 2.33 (s, 3H), 4.08 (q, J ¼ 7.2 Hz, 2H), 5.36
(s, 1H), 7.23–7.29 (m, 4H), 6.08 (brs, 1H), 8.39 (brs, 1H) ppm; IR (KBr) v: 3242,
3175, 3116, 2982, 1703, 1688, 1648, 1525 cmꢂ1
.
Compound 4f. Mp: 207–209 ꢀC (lit.[20] 208–210 ꢀC). 1H NMR (400 MHz,
CDCl3) d: 1.18 (t, J ¼ 6.4 Hz, 3H), 2.31 (s, 3H), 4.10 (t, J ¼ 6.4 Hz, 2H), 5.40 (s,
1H), 7.50–754 (m, 5H), 9.07 (brs, 1H), 9.41 (brs, 1H) ppm; IR (KBr) v: 3326,
3173, 3103, 1670, 1573, 1464, 1284, 1192 cmꢂ1
.
1
Compound 4g. Mp: 153–154 ꢀC (lit.[20] 150–152 ꢀC). H NMR (400 MHz,
CDCl3) d: 1.17 (t, J ¼ 7.2 Hz, 3H), 2.42 (s, 3H), 3.77 (s, 3H), 4.09 (q, J ¼ 7.2 Hz,
2H), 5.35 (s, 1H), 6.89 (d, J ¼ 8.6 Hz, 2H), 7.26 (d, J ¼ 8.6 Hz, 2H), 7.96 (brs, 1H),
8.18 (brs, 1H) ppm; IR (KBr) v: 3323, 3171, 3102, 2985, 1678, 1575, 1521, 1467,
1200 cmꢂ1
.
1
Compound 4h. Mp: 208–209 ꢀC (lit.[20] 208–209 ꢀC). H NMR (400 MHz,
CDCl3) d: 1.09 (t, J ¼ 7.2 Hz, 3H), 2.35 (s, 3H), 4.01 (q, J ¼ 7.2 Hz, 2H), 5.32 (s,
1H), 7.64–7.68 (m, 2H), 8.05–8.15 (m, 2H), 7.21 (brs, 1H), 8.23 (brs, 1H) ppm; IR
(KBr) v: 3324, 3177, 3102, 2988, 1660, 1594, 1531, 1475, 1189 cmꢂ1
.
Compound 4i. Mp: 212–214 ꢀC (lit.[20] 210–213 ꢀC). 1H NMR (400 MHz,
CDCl3) d: 1.09 (t, J ¼ 7.2 Hz, 3H), 2.31 (s, 3H), 4.02 (q, J ¼ 7.2 Hz, 2H), 5.30 (s,
1H), 7.48 (d, J ¼ 8.6 Hz, 2H), 8.24 (d, J ¼ 8.6 Hz, 2H), 7.20 (brs, 1H), 8.45 (brs,
1H) ppm; IR (KBr) v: 3323, 3170, 3102, 2985, 1678, 1606, 1521, 1467, 1374, 1320,
1284, 1268, 1202 cmꢂ1
.
Compound 4j. Mp: 190–192 ꢀC (lit.[20] 192–194 ꢀC). 1H NMR (400 MHz,
CDCl3) d: 1.10 (t, J ¼ 7.2 Hz, 3H), 2.30 (s, 3H), 4.02 (q, J ¼ 7.2 Hz, 2H), 5.20 (s,
1H), 7.23 (d, J ¼ 8.6 Hz, 2H), 7.43 (d, J ¼ 8.6 Hz, 2H), 7.28 (brs, 1H), 7.80 (brs,
1H) ppm; IR (KBr) v: 3327, 3176, 2982, 1673, 1614, 1573, 1464, 1370, 1322, 1280,
1268, 1209 cmꢂ1
.
1
Compound 4k. Mp: 190–192 ꢀC (lit.[20] 192–194 ꢀC). H NMR (400 MHz,
CDCl3) d: 1.17 (t, J ¼ 7.2 Hz, 3H), 2.22 (s, 3H), 2.43 (s, 3H), 4.09 (q, J ¼ 7.2 Hz,
2H), 5.25 (s, 1H), 7.00 (d, J ¼ 8.6 Hz, 2H), 7.20 (d, J ¼ 8.6 Hz, 2H), 7.91 (brs, 1H),
8.45 (brs, 1H) ppm; IR (KBr) v: 3324, 3169, 3108, 3068, 1669, 1606, 1526, 1492,
1464, 1374, 1320, 1284, 1268, 1241 cmꢂ1
.
Typical Procedure for Compounds 8a–g
A mixture of 2-naphthol 5 (2 mmol), aldehydes 6 (2 mmol), urea or acetamide 7
(2.5 mmol), and PS-PEGOSO3H (0.15 g) in glycerol (2.0 g) was heated at 100 ꢀC for
6 h. After the reaction, the products were extracted with ethyl acetate (6 mL ꢁ 3).

GLYCEROL MEDIUM FOR MCRs
3113
After removal of the solvent, the residual solid was purified by flash chromatography
over silica to give pure amidoalkyl naphthols.
Selected Data
1
Compound 8a. Mp: 238–240 ꢀC (lit.[21] 245–246 ꢀC); H NMR (400 MHz,
DMSO-d6) d: 2.03 (s, 3H), 7.11–7.23 (m, 8H), 7.32 (t, J ¼ 7.6 Hz, 1H), 7.74 (d,
J ¼ 7.8 Hz, 1H), 7.76 (d, J ¼ 8.0 Hz, 1H), 7.85 (s, 1H), 8.46 (d, J ¼ 8.0 Hz, 1H),
10.05 (s, 1H) ppm; 13C NMR (100 MHz, DMSO-d6) d: 23.2, 40.3, 118.8, 119.6,
122.8, 123.6, 126.2, 126.8, 127.4, 128.5, 128.9, 129.2, 129.6, 132.8, 143.2, 153.8,
168.8 ppm; IR (KBr) v: 3449, 3230–2229, 1642, 1602, 1579, 1503, 1433, 1370,
1232, 832 cmꢂ1
.
1
Compound 8b. Mp: 185–187 ꢀC (lit.[21] 182–183.5 ꢀC); H NMR (400 MHz,
DMSO-d6) d: 2.01 (s, 3H), 3.66 (s, 3H), 6.88–7.39 (m, 8H), 7.74–7.79 (m, 2H),
7.85 (d, J ¼ 8.0 Hz, 1H), 8.45 (d, J ¼ 8.0 Hz, 1H), 10.05 (s, 1H, NH); 13C NMR
(100 MHz, DMSO-d6) d: 22.7, 47.5, 55.1, 113.4, 118.5, 119.0, 122.3, 123.2, 126.2,
127.2, 128.5, 129.0, 132.3, 134.4, 143.5, 153.0, 157.7, 169.0; IR (KBr) v: 3426,
3055, 1625, 1582, 1513, 1436, 1250, 1042, 810 cmꢂ1
.
Compound 8c. Mp: 220–222 ꢀC (lit.[21] 222–223 ꢀC); 1H NMR 1H NMR
(400 MHz, DMSO-d6) d: 1.98 (s, 3H), 2.21 (s, 3H), 6.87–7.34 (m, 8H), 7.74 (d,
J ¼ 8.0 Hz, 1H), 7.80 (d, J ¼ 8.0 Hz, 1H), 7.83 (br, 1H), 8.37 (d, J ¼ 8.0 Hz, 1H),
9.98 (s, 1H) ppm; 13C NMR (100 MHz, DMSO-d6): 21.3, 23.6, 48.2, 117.1, 118.8,
122.4, 123.6, 125.9, 126.7, 128.6, 128.8, 129.4, 129.8, 133.5, 134.9, 138.5, 153.2,
168.1 ppm; IR (KBr, cmꢂ1): 3433, 3055, 1628, 1578, 1515, 1437, 1276, 1181,
813 cmꢂ1
.
1
Compound 8d. Mp: 226–228 ꢀC (lit.[21] 223–225 ꢀC); H NMR (400 MHz,
DMSO-d6) d: 2.03 (s, 3H), 7.06 (d, J ¼ 8.6 Hz, 1H), 7.12 (d, J ¼ 8.6 Hz, 1H),
7.16–8.48 (m, 10H), 10.01 (s, 1H) ppm; 13C NMR (100 MHz, DMSO-d6): 22.7,
48.3, 118.3, 119.5, 123.6, 127.1, 128.3, 128.9, 129.3, 129.5, 129.8, 130.1, 131.3,
132.9, 143.4, 153.3, 168.9 ppm; IR (KBr) v: 3392, 2962, 1638, 1577, 1493, 1436,
1278, 1245, 1172, 820 cmꢂ1
.
1
Compound 8e. Mp: 247–249 ꢀC (lit.[21] 248–250 ꢀC); H NMR (400 MHz,
DMSO-d6) d: 2.03 (s, 3H), 7.20 (d, J ¼ 8 .0 Hz, 1H), 7.24 (d, J ¼ 8.0 Hz, 1H), 7.26
(t, J ¼ 7.5 Hz, 1H), 7.40 (t, J ¼ 7.5 Hz, 1H), 7.54–7.53 (m, 2H), 7.75–8.63 (m, 6H),
10.11 (s, 1H) ppm; 13C NMR (100 MHz, DMSO-d6) d: 22.9, 47.7, 116.9, 118.6,
120.2, 120.9, 123.3, 126.7, 128.6, 129.2, 129.8, 132.1, 133.4, 145.6, 148.1, 153.7,
169.8 ppm; IR (KBr) v: 3396, 3267, 1648, 1603, 1522, 1438, 1063, 825 cmꢂ1
.
Compound 8f. Mp: 218–220 ꢀC (lit.[22] 216–217 ꢀC); 1H NMR (400 MHz,
DMSO-d6) d: 6.15 (brs, 1H), 6.55 (brs, 1H), 7.65–6.95 (m, 11H), 8.10–7.85 (m,
4H), 10.30 (s, 1H). 13C NMR (100 MHz, DMSO-d6) d: 48.7, 115.4, 118.6, 118.9,
122.5, 123.2, 123.5, 124.6, 126.3, 127.5, 128.3, 128.8, 128.9, 130.2, 132.2, 133.5,
134.2, 134.4, 143.7, 148.9, 153.5, 167.9. IR (KBr) v: 3372, 3229, 3092, 1645, 1576,
1520, 1435, 1346, 1299, 1062, 858 cmꢂ1
.

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Z.-J. QUAN ET AL.
1
Compound 8g. Mp: 188–190 ꢀC (lit.[22] 192–193 ꢀC); H NMR (400 MHz,
DMSO-d6) d: 2.24 (s, 3H), 6.98–7.02 (m, 2H), 7.46–7.20 (m, 11H), 7.90–7.68 (m,
2H), 8.14 (d, 1H, J ¼ 8.0 Hz), 8.86 (d, 1H, J ¼ 8.0 Hz), 9.88 (brs, 1H); 13C NMR
(100 MHz, DMSO-d6) d: 21.3, 49.1, 99.7, 114.9, 118.8, 122.4, 123.8, 126.5, 127.2,
127.8, 128.5, 128.6, 128.7, 129.4, 130.6, 132.3, 134.0, 135.2, 138.5, 153.2, 166.6; IR
(KBr) n: 3396, 1638, 1601, 1523, 1436, 1351,1258, 1054, 826 cmꢂ1
.
Typical Procedure for Compounds 9a–g
2-Naphthol (2 mmol), benzaldehydes (1 mmol), and PS-PEGOSO3H (0.15 g)
were mixed with glycerol (2.0 g). The mixture was stirred for 12 h at 120 ꢀC. After
the reaction, the products were extracted with ethyl acetate (6 mL ꢁ 3). The organic
phase was concentrated, and the crude products were recrystallized from EtOH to
give pure product 9.
Selected Data
Compound 9a. Mp: 181–183 ꢀC (lit.[23] 185 ꢀC); 1H NMR (CDCl3, 400 MHz):
6.49 (s, 1H), 6.99 (t, 1H, J ¼ 7.6 Hz), 7.15 (t, 2H, J ¼ 7.6 Hz), 7.41 (t, 2H, J ¼ 7.6 Hz),
7.48–7.60 (m, 6H), 7.78–7.84 (m, 4H), 8.41 (2H, d, J ¼ 8.5 Hz) ppm; IR (KBr) v:
3073, 1612, 1593, 1460, 1255, 1081, 968 cmꢂ1
.
Compound 9b. Mp: 202–203 ꢀC (lit.[23] 204 ꢀC); 1H NMR (CDCl3,
400 MHz): 3.67 (s, 3H), 6.56 (s, 1H), 7.72 (d, 2H, J ¼ 9.4 Hz), 7.39–7.96 (m, 12H),
8.43 (d, 2H, J ¼ 9.4 Hz) ppm; IR (KBr) v: 3043, 1616, 1582, 1397, 1246, 1160,
960 cmꢂ1
.
1
Compound 9c. Mp: 225–227 ꢀC (lit.[23] 229 ꢀC); H NMR (CDCl3): 2.15 (s,
3H), 6.50 (s, 1H), 7.00–7.60 (m, 10H), 7.75–8.45 (m, 6H) ppm; IR (KBr) v: 3077,
2918, 1594, 1506, 1459, 1239, 964 cmꢂ1
.
1
Compound 9d. Mp: 215–217 ꢀC (lit.[23] 215 ꢀC); H NMR (CDCl3): 6.47 (s,
1H), 7.11–8.24 (m, 16H); IR (KBr) v: 3041, 2920, 1628, 1595, 1513, 1456, 1250,
964 cmꢂ1
.
1
Compound 9e. Mp: 283–285 ꢀC (lit.[23] 289 ꢀC); H NMR (CDCl3): 6.43 (s,
1H), 6.90–7.12 (m, 2H), 7.28–7.61 (m, 8H), 7.73–7.86 (m, 4H), 8.28 (d, J ¼ 8.59 Hz,
2H) ppm; IR (KBr) v: 3066, 2925, 1623, 1590, 1514, 1456, 1245, 959, 812 cmꢂ1
.
Compound 9f. Mp: 213–215 ꢀC (lit.[23] 211 ꢀC); 1H NMR (CDCl3, 400 MHz):
6.66 (s, 1H), 7.08–8.67 (m, 16H); IR (KBr) v: 3033, 2938, 1628, 1585, 1450, 1246,
812 cmꢂ1
.
Compound 9g. Mp > 300 ꢀC (lit.[23] mp > 310 ꢀC); 1H NMR (CDCl3,
400 MHz): 6.63 (s, 1H), 7.46 (t, J ¼ 8.0 Hz, 2H),7.50 (d, J ¼ 8.8 Hz, 2H), 7.62 (t,
J ¼ 8.0 Hz, 2H), 7.65 (d, J ¼ 8.8 Hz, 2H), 7.82 (d, J ¼ 5.6 Hz, 2H), 7.86 (d, J ¼ 5.6 Hz,
2H), 8.00 (d, J ¼ 8.6 Hz, 2H), 8.30 (d, J ¼ 8.6 Hz, 2H) ppm; IR (KBr) v: 3062, 2930,
1627, 1591, 1457, 1202, 1145, 964 cmꢂ1
.

GLYCEROL MEDIUM FOR MCRs
3115
ACKNOWLEDGMENTS
We are thankful for the financial support by the National Nature Science
Foundation of China (No. 20902073), the Natural Science Foundation of
Gansu Province (No. 096RJZA116), and Gansu Key Laboratory of Polymer
Materials.
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