J. Biomedical Science and Engineering, 2009, 2, 318-322
doi: 10.4236/jbise.2009.25047 Published Online September 2009 (http://www.SciRP.org/journal/jbise/
JBiSE
).
Published Online September 2009 in SciRes.http://www.scirp.org/journal/jbise
Dendritic compound of triphenylene-2,6,10-trione
ketal-tri-{2,2-di-[(N-methyl-N-(4-pyridinyl) amino)
methyl]-1,3-propanediol}: an easily recyclable
catalyst for Morita-Baylis-Hillman reactions
Rong-Bao Wei, Hong-Lin Li*, Ya Liang, Yan-Ru Zang
School of Chemistry and chemical Engineering, Tianjin Institute of Technology, Tianjin, China.
Received 11 April 2009; revised 10 May 2009; accepted 13 May 2009.
ABSTRACT
A novel Dendritic Compound (2) of triphenylene-
2,6,10-trione ketal-tri-{2,2-di-[(N-methyl-N-(4-py-
ridinyl) amino)methyl]-1,3-propanediol} was
conveniently synthesized by aromatization of
cyclohexanedione mono-ketal, ketal-exchange
reaction with 2,2-dibromomethyl-1,3-propane-
diol and nuclophilic substitution with N-methy-
laminopyridine as nuclophilic reagent. The Mo-
rita-Baylis-Hillman reaction of various aryl al-
dehydes with methyl vinyl ketone and acryloni-
trile in (DMF/cyclohexane, 1/1, v/v) has been
investigated by using Dendritic Compound (2)
as catalyst. The corresponding Morita-Baylis-
Hillman adducts was obtained in good yields by
using the recycled and reactivated dendritic
catalyst.
Keywords: Morita-Baylis-Hillman Reaction; Methyl
Vinyl Ketone; Aryl Aldehydes; Dendritic Compound;
DMAP
1. INTRODUCTION
The Morita-Baylis-Hillman reaction possesses cheap and
easy availability of starting materials, easing perform-
ance, atom economy, forming chemo-specific functional
groups in the product, providing an avenue for introduc-
ing asymmetry, and fitting for simulation on the solid
phase as a prelude for combinatorial synthesis represent
some of the reasons, which have led to an exponential
increase in the synthetic utility of this reaction [1,2,3,4,5,
6,7,8,9,10]. The Morita-Baylis-Hillman reaction can be
promoted by using organic bases. However, almost all
the Morita-Baylis-Hillman reactions reported so far use
small molecular homogeneous catalyst, and it impedes
the reusing of the catalyst. In addition, this reaction
could be accomplished in a perfect atom-economic way
if a recyclable Lewis base was employed as the promoter.
Recently, Corma et al. [11] developed a heterogeneous
catalyst system by using an insoluble Merrifield type
resin-supported 4-(N-benzyl- N-methyl amino)pyridine
as reusable catalyst for the Morita-Baylis-Hillman cou-
pling of aromatic aldehydes and unsaturated ketones. Shi
[12] reported the use of soluble polymer-supported
Lewis bases, such as PEG4600-(PPh2)2 and linear poly
(DMAP) in the Morita-Baylis-Hillman reactions of N-
tosylimines with unsaturated ketones.
Yang [13] employed the dendritic Lewis base as the
catalyst together with a binary solvent system (DMF-
cyclohexane, 1:1, v/v) ,which could become homogene-
ous when heated up to 60◦C and then could be readily
separated by cooling the system to room temperature.
Several other examples of immobilized praline are re-
ported in literature: poly-(ethylene glycol)-supported
praline [14], proline immobilized on polyethyleneglycol
grafted on cross-linked polystyrene [15], proline immo-
bilized on mesoporous silica [16], polystyrene-supported
praline [17] or polymer-supported proline-decorated
dendrons [18,19].
Dendritic compound of triphenylene-2,6,10-trione
ketal-tri-{2,2-di-[(N-methyl-N-(4-pyridinyl) amino) me-
thyl]-1,3-propanediol} provided the following key ad-
vantages: a) reaction system provides complete miscibil-
ity under the reaction temperature; b) the structure of
dendrier catalyst is well-defined; c) the dosage of cata-
lyst is less than other catalysts.
2. RESULTS AND DISCUSSION
We chose a dendritic compound of triphenylene-2,6,
10-trione ketal-tri-{2,2-di-[(N-methyl-N-(4-pyridinyl)
amino)methyl-1,3-propanediol} 2 as catalyst for Mo-
rita-Baylis-Hillman reaction, which was conveniently
prepared according to following synthesis procedure
(Scheme 1).

R. B. Wei et al. / J. Biomedical Science and Engineering 2 (2009) 318-322 319
SciRes Copyright © 2009 JBiSE
(1) (2)
Scheme 1
The Compound (1) was prepared by one-pot method.
Through the exchange reaction after the aromatization,
the five-membered ketal transformed to the more stable
six-membered ketal. It omitted the hydrolysis of the
ketal and separation steps. The reaction was in the Lewis
acid, so the dehydration was reduced.
Because Compound (1) contains six bromine atoms,
the amount of the alkaline must be controlled seriously
in case of more side-reaction such as HBr elimination.
The content of 30%NaH should be tested before use.
Even so, they were forming some cross linked macro-
molecules. These were obviously increased in the
NaOH/H2O system.
The advantages of grafted DMAP to dendritic com-
pound are as follows: for the macromolecular compound
can be dissolved in most of the organic solvent instead of
water, so it can be isolated by adding water after reaction
and be used after activation by alkaline; for it has large
cavities and dissolves in organic phase, it is helpful for
contacting the reactant and catalyst and thus the reaction
rate is higher than that of the polymer carried DMAP. So it
combines the advantages of both forms of DMAP.
In order to determine the activity of this dendritic
catalyst, we chose the coupling of 4-nitrobenzaldehyde
with methyl vinyl ketone (MVK) as the model reaction,
which is a paradigmatic example of the Mo-
rita-Baylis-Hillman reaction. In all cases only the normal
Morita-Baylis-Hillman product was found [20,21,22].
The results were summarized in Table 1. As seen from
the table, the highest yield was achieved when the molar
ratio of aldehyde:MVK: dendritic-DMAP being 1:3:0.2,
making it in the condition that the reacting time reach 48
h (Table 1, Entry 5).
The dendritic catalyst could be easily recovered by
cooling the reaction mixtures to room temperature and
adding water at the end of the reaction. In order to regain
the catalyst activity, the deactivated catalyst was treated
with 2M NaOH at 45◦C for 2 h and subsequent was ap-
plied to the reaction under the same conditions, giving
good yields. (see Table 1: Entries (9-13))
To demonstrate the applicability of dendritic DMAP
as a homogeneous catalyst for the Morita-
Baylise-Hillman reaction, various aldehydes were tested
as reactants reacting with MVK or acrylonitrile and the
results are shown in Table 2. It was found that the aryl
aldehydes had strongly electron-withdrawing groups on
the benzene rings such as dinitrobenzaldehyde and ni-
trilbenzaldehydes reacting with MVK and acrylonitrile
gave the corresponding Morita-Baylis-Hillman adducts
with high yields (1a,2a, 4a,7a,10a, 1b,2b, 4b,7b,10b). On
the contrary, other aryl aldehydes, in particular with
electron-donating substituents, provided low yields.
3. CONCLUSIONS
In summary, we have described a new catalytic system
by using dendritic derivative of 4-(N,N-dimethylamino)
pyridine as catalyst for the Morita-Baylis-Hillman reac-
tions of aryl aldehydes with MVK and acrylonitrile. The
recyclability and applicability of this catalytic system
has been well demonstrated.

320 R. B. Wei et al. / J. Biomedical Science and Engineering 2 (2009) 318-322
SciRes Copyright © 2009
Table 1. Morita-Baylis-Hillman Reactions of 4-nitrobenzaldehyde (1.0 equiv.) with MVK in the pre-
sence of Cat 1.
O
2
NCHO +
O
Cat 1
DMF-cyclohexane
O
OH
O
2
N
Entry Aldehyde: MVK: Cat 1(mol) Time (d) Ylide(%)
1 1:1:0.2 0.5 30.5
2 1:2:0.2 0.5 45.3
3 1:3:0.2 0.5 49.7
4 1:4:0.2 0.5 50.1
5 1:3:0.2 1 88.6
6 1:3:0.2 2 90.5
7 1:3:0.2 3 90.0
8 1:3:0.2 4 89.4
9 1:3:0.2 2 90.5
10 1:3:0.2 2 90.5
11 1:3:0.2 2 90.5
12 1:3:0.2 2 90.5
13 1:3:0.2 2 90.5
Cat 1 is the Compound (2)
Table 2. The Baylis-Hillman reactions of aryl aldehydes with active alkene in the presence of Cat 1.
ArCHO +
EWG Cat 1
DMF-cycloh exane
EWG
OH
Ar
Enty Ar EWG Time(d) Yield(%)
1 4-NO2-C6H4CHO 2 1a 92.2
2 2-NO2-C6H4CHO 2 2a 92.2
3 3-NO2-C6H4CHO 2 3a 82.2
4 4-CN-C6H4CHO 2 4a 90.2
5 4-Cl-C6H4CHO 2 5a 82.2
6 4-Br-C6H4CHO 2 6a 72.2
7 4-NO2-C5H4NCHO 2 7a 90.2
8 4-CH3O-C6H4CHO 2 8a 32.2
9 3-CH3O-C6H4CHO 2 9a 52.2
10 3,4-dinitro-C6H3CHO COCH3 2 98.5
11 3,4-dinitro-C6H3CHO CN 2 97.9
12 4-NO2-C6H4CHO CN 2 95.2
13 2-NO2-C6H4CHO CN 2 94.7
14 3-NO2-C6H4CHO CN 2 87.9
15 4-CN-C6H4CHO CN 2 89.2
16 4-Cl-C6H4CHO CN 2 84.2
17 4-Br-C6H4CHO CN 2 79.5
18 4-NO2-C5H4NCHO 2 7b 95.3
19 4-CH3O-C6H4CHO 2 8b 40.3
20 3-CH3O-C6H4CHO 2 9b 56.2
21 C6H5CHO COCH3 2 52.6
22 C6H5CHO CN 2 47.2
Cat 1 is the Compound (2)
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R. B. Wei et al. / J. Biomedical Science and Engineering 2 (2009) 318-322 321
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4. EXPERIMENTAL
4.1. General Remarks
Aryl aldehydes and acrylonitrile were stored under a
nitrogen atmosphere before using. Other commercially
supplied reagents were used as 4supplied without further
purification. Organic solvents were dried by standard
methods when necessary.
1H NMR spectra were recorded on an INOVA400
spectrometer for solution in CDCl3 with TMS as internal
standard. Varian MAT 44S MS; Cavlo Eba 1106 ele-
mental analysis instrument; WRR melting point appara-
tus (Shanghai Precision Instrument Co. Ltd.).
4.2. Synthesis of Dendrimer Compound (2)
ZrCl4/SiCl4 (0.5g, 1:1 in weight) was added to dissolving
1,4-cyclohexane-dione mono-ketal ethylene diol (1.56g,
10 mmol) in anhydrous ethanol (100mL). It was refluxed
for 10~12 h and controlled by TCL until the 1, 4-cyclo-
hexane-dione mono-ketal ethylene diol almost disap-
peared. After cooling, 2,2-dibromomethyl-1,3-pro-
panediol (3.93g, 15 mmol) was added and refluxed for
9~12 h. Then cooling to room temperature, Ethanol was
removed to 1/3 by evaporation. The raw product was
crystallized by isopropyl alcohol. Compound (1) (2.95g)
was obtained. Yield: 88.2%. M.p.:247~248℃ (decom-
posed).
M+ :1013, C%: 39.14(39.08), H%:4.20(4.17), Br%:
47.27（47.28）. IR(KBr,cm-1):2897,2860, 1465,1357; 1H-
NMR (CDCl3,δppm): 3.55 (2H,s,O-CH2) 2.62 (2H, s,Br
-CH2), 2.02 (2H,t, J = 7.4 Hz CH2), CH2), 1.85(2H,t, J =
7.4 Hz CH2), 1.52(2H,s,CH2).
In the protection of N2, 30 % NaH (0.48 g, 0.006 mol)
was added to dissolving N-methyl-4-aminopyridine
(0.65 g,6 mmol) in anhydrous THF (100 mL). It was
refluxed for 1~2 h. After cooling, Compound (1) (1.01g,
1mmol) was added and refluxed for 10~15 h until
N-methyl-4-amino pyridine could not be examined by
TCL. THF was removed to 2/3 by evaporation. After
cooling and filtering, the product was crystallized by
CHCl3:C2H5OH. Compound (2) (0.98g) was obtained.
Yield: 83.5%. M.p.>300(decomposed).℃
M+:1176.5, C%: 70.44(70.38), H%: 7.23(7.19), N%:
14.30 （14.27 .IR(KBr,cm-1):3112, 3008,2875, 2861,
1605,1465,1375; 1H-NMR (CDCl3,δppm): 8.41(2H, d, J
= 8.0 Hz, Ar), 7.85(2H, d, J = 8.0 Hz, Ar), 3.54 (2H,
s,O-CH2) 2.64(2H,s,N-CH2), 2.02(2H,t, J = 7.4 Hz CH2),
1.98(2H,s, N-CH2),1.85(2H,t, J = 7.4 Hz CH2), 1.52
(2H,s,CH2).
4.3. General Procedure for the Mo-
rita-Baylis-Hillman Reaction of Aryl
Aldehydes with MVK and Acrylonitrile
To a 50ml bottom flask charged with aryl aldehydes (5.0
mmol) and dendritic DMAP (0.2 mmol) in 20ml DMF
was added methyl vinyl ketone (MVK) (15.0 mmol) or
acrylonitrile (15.0 mmol) under nitrogen atmosphere and
the reacted mixture was stirred 48 h at 60◦C. At the end
of the reaction, the reacted mixture was cooled back to
25◦C and then adding 20ml water to the reacted mixture.
The catalyst was recovered by filtration. The product
was remained in the DMF/water layer, the solvent was
removed under reduced pressure, and the residue was
further purified by recrystalization
4.4. Characterization of the Morita-
Baylis-Hillman Reaction Adducts
Compounds 1a, 2a , 4a, 5a , 6a, 8a,11a, and 1b, 2b, 4b,
5b, 6b, 8b,11b have been successfully characterized in
the literature [23].
Compound 3a 1H NMR (CDCl3, 400 MHZ, TMS): δ
2.35(3H, s, Me), 3.00 (1H, br., s, OH) 5.63 (1H, s, CH),
6.01 (1H,s, olefinic), 6.24 (1H, s, olefinic), 7.40 (1H, m,
Ar), 8.12 (1H, m, Ar), 8.15 (1H, m, Ar), 8.25 (1H, m,
Ar).
Compound 3b 1H NMR (CDCl3, 400 MHZ, TMS):
3.00 (1H, br., s, OH) 5.63 (1H, s, CH), 6.11 (1H,s, ole-
finic), 6.27 (1H, s, olefinic), 7.35 (1H, m, Ar), 8.00(1H,
m, Ar), 8.10 (1H, m, Ar), 8.20 (1H, m, Ar).
Compound 7a 1H NMR (CDCl3, 400 MHZ, TMS): δ
2.35 (3H, s, Me), 3.00 (1H, br., s, OH) 5.63 (1H, s, CH),
6.01 (1H,s, olefinic), 6.24 (1H, s, olefinic), 7.59 (2H, d,
J = 8.4 Hz, Ar),8.62 (2H, d, J = 8.0 Hz, Ar).
Compound 7b 1H NMR (CDCl3, 400 MHZ, TMS):
3.00 (1H, br., s, OH) 5.63 (1H, s, CH), 6.01 (1H,s, ole-
finic), 6.24 (1H, s, olefinic), 7.50 (2H, d, J = 8.4 Hz,
Ar),8.60 (2H, d, J = 8.0 Hz, Ar).
Compound 9a 1H NMR (CDCl3, 400 MHZ, TMS): δ
2.00 (1H, br., s, OH), 2.13 (3H, s, Me), 3.87 (3H, s,
OCH3), 5.80 (1H, s, CH), 5.83 (1H, s, olefinic), 6.02 (1H,
s, olefinic), 6.87-7.47(4H, m, Ar).
Compound 9b 1H NMR (CDCl3, 400 MHZ, TMS): δ
2.00 (1H, br., s, OH), 3.87 (3H, s, OCH3), 5.80 (1H, s,
CH), 5.83 (1H, s, olefinic), 6.02 (1H, s, olefinic),
6.87-7.47(4H, m, Ar).
Compound 10a 1H NMR (CDCl3, 400 MHZ, TMS): δ
2.35(3H, s, Me), 3.00 (1H, br., s, OH) 5.63 (1H, s, CH),
6.01 (1H,s, olefinic), 6.24 (1H, s, olefinic), 7.49 (1H, d,
J = 8.4 Hz, Ar),8.12 (1H, d, J = 8.0 Hz, Ar) , 9.15 (1H, d,
J = 3.0 Hz, Ar).
Compound 10b 1H NMR (CDCl3, 400 MHZ, TMS):
3.20 (1H, br., s, OH) 5.70 (1H, s, CH), 6.21 (1H,s, olefinic),
6.27 (1H, s, olefinic), 7.47 (1H, d, J = 8.4 Hz, Ar),8.10 (1H,
d, J = 8.0 Hz, Ar) , 8.95 (1H, d, J = 3.0 Hz, Ar).
5. ACKNOWLEDGEMENTS
We appreciate the National Natural Science Foundation of China
(G20472064) and the Tianjin Natural Science Foundation of China

322 R. B. Wei et al. / J. Biomedical Science and Engineering 2 (2009) 318-322
SciRes Copyright © 2009
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[14] Benaglia, M., Cinquini, M., Cozzi, F., Puglisi, A., and
Celentano, G., (2002) Adv. Synth. Catal., 344, 533.
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