Synthesis of polystyrene-bound perfluoroalkyl sulfonic acids and the application of their ytterbium salts in multicomponent reactions (MCRs)

Article abstract of DOI:10.1016/j.tet.2005.08.118

New polystyrene-bound perfluoroalkyl sulfonic acids and their ytterbium salts have been prepared. Multicomponent reactions (MCRs) for the efficient synthesis of homoallylic amines or amides catalyzed by the polystyrene-bound perfluoroalkyl sulfonic ytterb

Full text of DOI:10.1016/j.tet.2005.08.118

Tetrahedron 61 (2005) 12042–12052
Synthesis of polystyrene-bound perfluoroalkyl sulfonic acids and
the application of their ytterbium salts in multicomponent
reactions (MCRs)
*
Yueyan Yin, Gang Zhao and Gui-Long Li
Laboratory of Modern Organic Synthetic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, People’s Republic of China
Received 31 May 2005; revised 14 August 2005; accepted 14 August 2005
Available online 26 October 2005
Abstract—New polystyrene-bound perfluoroalkyl sulfonic acids and their ytterbium salts have been prepared. Multicomponent reactions
(MCRs) for the efficient synthesis of homoallylic amines or amides catalyzed by the polystyrene-bound perfluoroalkyl sulfonic ytterbium
salts are reported.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
therefore, development of new polymer-bound super
Brønsted acids and Lewis acids is still desirable.
Polymer-bound catalysts and reagents have attracted much
attention of researchers in the development of economically
and environmentally benign organic synthesis.1 Up to now,
several polymer-bound super Brønsted acids and Lewis
acids (such as 1,2a–c 2,2d 3,2e 4,2f 52g) have been reported to
be useful in organic reactions (Scheme 1). Other ways
similar to polymer attachment such as microencapsulated
and perfluorous chain ‘immobilized’ Lewis acids (6 and 7)
were also reported.3 Perfluororesinsulfonic acid such as
Nafion is one of the most famous immobilized super acids
superior to conventional resin sulfonic acids such as
sulfonated polystyrenes in its catalytic activity, thermal
stability and chemical resistance.2a,b However, its low
swelling in non-protic organic solvents leads to its
compromised reactivity in some cases.4 On the other
hand, the commercially available polystyrene can be
efficiently swollen by both polar and non-polar organic
solvents.5 Merrifield type resins, the cross-linked chloro-
methyl polystyrenes, are widely developed for polymer-
bound catalysts.6 Up to now, polystyrene-bound super
Brønsted acid 5 is believed to be the strongest acid among
the known solid acids.2g,7 In light of the Brønsted acidity
order reported in AcOH (TfOHOTf2NHOTf3CH),8
Recently, multicomponent reactions (MCRs) have received
increasing attention due to their diversity-oriented synthetic
methodology for the rapid generation of small molecules
libraries.9 MCRs have been also considered as one of the
most efficient methods to construct complex molecules from
simple starting materials in a single operation. Multi-
component coupling reactions to produce homoallylic
amines has attracted much attention because they are as
key structural moieties in a variety of important naturally
occurring compounds and pharmaceuticals. Addition of
allylstannane reagents to imines catalyzed by Lewis acids
has been widely investigated. The first addition of
allylstannane with imine catalyzed by Ln(OTf)3 in organic
solvents was reported in 1995, which afforded moderate
yield in 24 h.10a In 1998, both Kobayashi’s and Akiyama’s
groups reported one-pot reaction catalyzed by 20 mol% of
scandium triflate.10b,11 In the same year, Greeves et al.
reported Yb(OTf)3 catalyzed allylation of aldehydes with
the accelerating co-catalyst of benzoic acid using only
2 mol% of Yb(OTf)3 in CH3CN in much shorter time.10c
They also reported the synthesis of homoallylic alcohols and
amines catalyzed by La(OTf)3/benzoic acid in 2002.10d The
authors suggested that the Brønsted acid of PhCOOH was
not only simply regenerating the catalyst but also the
Brønsted acid and the Lewis acid working together as a
combined catalyst to produce a ‘double activation’. Recent
developments in this area deal with imines activation by
Keywords: Lewis acid; Merrifield resin; Polymer-bound.
*
Corresponding author. Fax: C86 21 641 66128.;
e-mail: zhaog@pub.sioc.ac.cn
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.08.118

Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
12043
Scheme 1. Typical immobilized super Brønsted acids and their metal salts.
Scheme 2.
chlorotrimethylsilane or acid chloride, catalytic Pd(II) or
Pt(II) complex, NdCl5, montmorillonite and other Lewis
acids.12 Herein, we would like to report the synthesis of
polystyrene-bound super Brønsted acids 8, 9 and their
ytterbium salts, 10 and 11 (Scheme 2), and the highly
efficient one-pot multicomponent coupling reactions for the
synthesis of homoallylic amines and amides catalyzed by
polystyrene-bound perfluoroalkyl sulfonic ytterbium.
2. Results and discussion
2.1. Synthesis of polystyrene-bound perfluoroalkyl
sulfonic acids and their ytterbium salts
We began our synthesis with addition reaction of
perfluoroalkyl iodide 14 or 15 to the Merrifield resin allyl-
PS 1313 accomplished by sodium dithionite and radical
Scheme 3. Reaction conditions: (a) Ref. 7, Merrifield resin, 100–200 mesh (or 200–400 mesh), 1 or 2% DVB cross-linker; (b) BPO, toluene, 110–120 8C;
(c) Bu3SnH, AIBN (cat.), THF, reflux, 24 h; (d) (i) NaOH, 1N, THF/H2O, room temperature, overnight; (ii) 1 N HNO3, rt, 8 h; (e) (i) Na2SO4 (satd); (ii) YbCl3
(aq), room temperature, overnight.

12044
Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
initiators.14 Sulfinatodehalogenation reaction was first
investigated because of its high efficiency for various
alkenes had been reported.13a,15 The addition reaction of
polyfluoro sulfonyl fluoride 14 (or 15) (3 equiv) with 13 was
carried out in CH3CN/H2O (v/v:1:1) monitored by IR
spectrometry and 19F NMR in the presence of Na2S2O4 and
NaHCO3 under reflux. Unfortunately, no addition reaction
occurred even with prolonged reaction time. Poor swelling
of the Merrifield resin in the aqueous solvent might account
for this result (Scheme 3).
Table 2. Three-component coupling reaction of benzaldehyde, aninline and
tributylallylstannane catalyzed by different Yb-resinsa
Yb-PS2-Rf6
PhCOOH(1equiv)
CHO
NH2
HN
SnBu3
+
+
CH3CN , rt.
20a
21a
22a
Entry
Yb–PSm–Rfn (mol%)
Time (h)
Yield (%)b
1
2
3
4
5
5
6
7
7
8
9
10
11
Yb–PS1–Rf2 (2.0)
Yb–PS1–Rf2 (1.0)
Yb–PS1–Rf2 (0.5)
Yb–PS1–Rf2 (0.3)
Yb–PS1–Rf2 (0.1)
Yb–PS1–Rf2 (0.05)
Yb–PS1–Rf6 (0.1)
Yb–PS2–Rf2 (0.1)
Yb–PS2–Rf6 (0.1)
Yb–PS3–Rf2 (0.1)
Yb–PS3–Rf2 (0.1)
Yb–PS4–Rf2 (0.1)
Yb–PS4–Rf6 (0.1)
0.5
1.0
2.5
3.0
5.0
8.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
93
91
92
93
93
84
94
93
95
89
90
88
91
So, we tried to carry out the radical addition using the
initiator of AIBN or BPO. The radical initiators most
commonly used dissolve easily in CH2Cl2, THF and
toluene, which swell the Merrifield resin well. In 1993,
Burton et al. reported the synthesis of partially fluorinated
phosphonic/sulfonic acids using addition of I(CF2)4OCF2-
CF2SO2F or I(CF2)2OCF2CF2SO2 to (EtO)2P(O)CH2OCH2-
CH]CH2 initiated by BPO.14b Using this method, we
employed 1–20 mol% of freshly recrystallized BPO, 13(1 or
2% DVB cross-linker) and 3 equiv of 14 or 15 in dry
toluene. After gas exchange for three times with nitrogen,
the mixture was heated in oil bath at 110–120 8C. IR
spectrum indicated that the more BPO (1, 5, 10 and
20 mol%) used, the weaker the absorption of the C–C
double bond, but far from complete conversion yet.
Using100 or 200 mol% of BPO, the C–C double bond of
resin almost disappeared completely in 24 h in toluene.
However, this was unpractical method. To find the
optimized conditions, we focused on carefully degassing
of the reaction mixture because radical reaction is sensitive
to oxygen. After dry nitrogen is bubbled through the mixture
of 20 mol% of BPO and 3 equiv of perfluoroakyl iodide in
toluene for 1 h, the mixture was stirred at 110–120 8C for
6 h, a second portion of BPO (20 mol%) was added to
complete the reaction during another 20 h at 120 8C. The
next step was to remove the iodide of the polymer. Although
zinc powder is cheap and widely used for the reduc-
tion,14b,15 the reduction of polymer 16 (or 17) was run in the
mixture of THF/i-PrOH using activated zinc powder with or
without adding AcOH for longer reaction time, only a slight
amount of the iodide was reduced to be indicated by
elemental analysis. Bu3SnH as a candidate was employed to
perform the reduction according literature.16 As a result,
polymer 16 (or 17) was completely reduced by 3 equiv of
Bu3SnH in the presence of catalytic amount of AIBN in
THF under reflux (elemental analysis, I!0.5 wt%). The
resulting polymer was filtrated and washed, and dried
polymer 18 (or 19) gave comparable loading of F and S. 18
a Molar ratio: 20a:21a: allyltribuylstannane: PhCOOH: Yb–PSm–Rfn(10 or
11)Z1.0:1.0:1.1:1.0:0.1.
b Isolated yield.
(or 19) was dispersed in THF, and NaOH solution was then
added slowly. It is noteworthy that the resin could not be
completely wetted by water. The mixture was stirred
overnight. After filtration, the polymer was redispersed in
water and acidified by HNO3.17 After washing and drying,
elemental analysis of PS–fSO3H 8 (or 9) and IEC(HC
exchange capacity determined by titration according to Ref.
2e). Then, 8 (or 9) was dispersed in saturated Na2SO4 and
several drops of THF to exchange all of the HC. Washed till
the filtrate was neutral then redispersed in YbCl3 solution
and stirred overnight. Loading of 10 (or 11) was determined
by titration (Table 1).2e
2.2. One-pot multi-component reaction for synthesis of
homoallylic amines and amides catalyzed by polymer-
bound perfluoroalkyl sulfonic ytterbium
To evaluate the catalytic activity of the Yb-resins, we first
conducted the three-component coupling reaction of
benzaldehyde, aniline and tributylallylstannane in the
presence of 1 equiv of benzoic acid (with respect to
benzaldehyde) at room temperature using the different Yb-
resins in CH3CN. The results are shown in Table 1. It was
found that the reaction underwent smoothly in the presence
Table 1. Yb-resins prepared from different resins and ytterbium chloride
Entry
Yb resin
(PSm–RfnSO3)3Yb
Merrifield resin used
HC exchange capacity
Loading of Yb
(mmol/g)b
(8 or 9, IEC: mmol/g)a
1
2
3
4
5
6
7
8
10a (Yb–PS1–Rf2)
11a (Yb–PS1–Rf6)
10b (Yb–PS2–Rf2)
11b (Yb–PS2–Rf6)
10c (Yb–PS3–Rf6)
11c (Yb–PS3–Rf6)
10d (Yb–PS4–Rf2)
10d (Yb–PS4–Rf6)
1% DVB, 0.95–1.05 mmol/g ClK, 100–200 mesh
1% DVB, 0.95–1.05 mmol/g ClK, 100–200 mesh
1% DVB, 2.8–3.0 mmol/g ClK, 200–300 mesh
1% DVB, 2.8–3.0 mmol/g ClK, 200–300 mesh
2% DVB, 0.98–1.02 mmol/g ClK, 100–200 mesh
2% DVB, 0.98–1.02 mmol/g ClK, 100–200 mesh
2% DVB, 2.8–3.0 mmol/g ClK, 200–400 mesh
2% DVB, 2.8–3.0 mmol/g ClK, 200–400 mesh
0.69
0.46
1.22
0.92
0.67
0.57
1.20
0.86
0.21
0.13
0.38
0.28
0.21
0.16
0.36
0.26
a Determined by acid base titration.
b Determined by titration using EDTA (according to Ref. 2e).

Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
12045
of 0.1 mol% of Yb–PSm–Rfn in CH3CN at room tempera-
ture. No big differences in the reaction yield were observed
for these Yb-resins (Table 2). The Yb–PS2–Rf6 (11b) with a
cross-linked degree of 1% and a longer perfluoroalkyl chain
was the most effective to catalyze this reaction. Complete
conversion of the substrates could be achieved in 5 h in
CH3CN. Further, we examined the reaction in other solvents
listed in Table 3. Reactions in other organic solvents other
than acetonitrile needed much longer time to complete.
A slight decrease in the yield was observed in the solvents
of DMF, CH2Cl2, and THF (Table 3, entries 1–3). Toluene,
water or ethanol gave good yield. We presume that these
Yb-resins have amphiphilic property. Moreover, a number
of substrates were subjected to the optimized reaction
conditions to examine scope and limitation of this reaction.
Aromatic, aliphatic or a,b-unsaturated aldehydes were
found to undergo highly efficient conversions in high yields.
Substituted aromatic aldehydes and anilines with electron-
withdrawing substituents reacted somewhat faster (Table 4,
entries 2, 3, 6 and 12); cyclohexyl aldehyde reacted even
faster (Table 2).
The polymer bound catalysts could be recovered by simple
filtration. For example, Yb–PS2–Rf6 (11b) was reused for
10 times in the reaction of benzaldehyde, aniline and
tributylallylstannane in the presence of 1 equiv of benzoic
acid in CH3CN (Table 5). No lost of activity was observed
for the recovered catalyst.
Table 3. Effect of solvents on the reaction catalyzed by Yb–PS2–Rf6 (11b)a
Then, we chose the one-pot four-component coupling
reaction of benzaldehyde, aniline, tributylallylstannane and
acrylic chloride in the presence of 1 equiv of benzoic acid
(with respect to benzaldehyde) at room temperature using
0.1–1 mol% Yb–PS2–Rf6 (11b) Yb-resins in CH3CN.
Thus, the three-component coupling of benzaldehyde,
aniline, tributylallylstannane is fast under the above
reaction conditions. When the aldehyde disappeared,
1.2 equiv of acrylic chloride (with respect to aldehyde)
was added. However, the homoallylic amine did not
Entry
Solvent
Time (h)
Yield (%)b
1
2
3
4
5
5
DMF
THF
CH2Cl2
Tulene
EtOH
H2O
18
18
18
18
10
8.0
65
81
72
92
94
90
a Molar ratio: 20a:21a: allyltribuylstannane: PhCOOH: Yb–PS2–Rf6
(11b)Z1.0:1.0:1.1:1.0:0.1.
b Isolated yield.
Table 4. Three-component coupling reaction catalyzed by Yb–PS2–Rf6 (11b) in CH3CNa
Entry
R1
R2
Time (h)
Product
Yield (%)b
1
2
3
4
5
6
7
8
Ph
p-F-Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
5.0
3.5
3.0
4.0
6.5
3.0
5.5
3.0
2.0
4.5
4.0
3.0
6.0
22a
22b
22c
22d
22e
22f
22g
22h
22i
95
93
90
92
87
90
90
86
85
89
90
86
95
p-Cl-Ph
p-Br-Ph
p-MeO-Ph
p-O2N-Ph
m-MeO-Ph
2-Furyl
c-Hexane
trans-PhCH]CH
Ph
9
Ph
Ph
10
11
12
13
22j
22k
22l
p-F-Ph
p-O2N-Ph
p-MeO-Ph
Ph
Ph
22k
a Molar ratio: 20:21 : allyltribuylstannane: PhCOOH: Yb–PS2K Rf6(11b)Z1.0:1.0:1.1:1.0:0.1.
b Isolated yield.
Table 5. Recycling of Yb–PS2–Rf6 (11b)
Run
1
2
3
4
5
6
7
8
9
10
93
Yield (%)
95
95
94
94
94
93
93
92
93

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Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
Table 6. One-pot four component tandem reaction for synthesis of acrylic amide
Entry
Yb–PS2–Rf6 (mmol%)
T1 (h)
T2 (h)
Acrylic chloride
(equiv)
Yield (%)a
1
2
3
4
5
6
0.1
0.1
0.3
0.5
1.0
2.0
5
5
5
4
2
1
6
6
6
6
6
6
1.2
2.2
2.2
2.2
2.2
2.2
Trace
54
60
77
78
76
a Isolated yield.
disappear even after a long time. Only trace amide was
isolated (Table 6, entry 1). Water generated from the imine
in situ to destroy the acrylic chloride. So 2.2 equiv of
acrylic chloride was used and the yield increased to 54%
(Table 6, entry 2). With the increasing amount of catalyst
used, the allylation reaction finished in shorter time as
expected. Yield of the acylated product also improved a
little. Further increase of the catalyst loading to 2 mol%
Scheme 4. Structures and yields of one-pot four-component reaction.

Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
12047
Scheme 5.
gave no better result than 0.5 mol% of catalyst used
(Table 6, entries 4 and 6).
3. Conclusion
In summary, we have developed the synthesis of new
polymer-bound polyfluoroalkyl super Brønsted acids and
their ytterbium salts. In addition, the polymer-bound-Yb
salts as Lewis acids catalyzed multicomponent reaction for
the synthesis of homoallylic amines and amides. These
heterogeneous catalysts are highly efficient, recyclable and
reusable.
Having in hand the optimized conditions, a number of acid
chlorides were subjected to examine the scope and
limitation of the one-pot four-component reaction in the
presence of 0.5 mol% of Yb–PS2–Rf6 (11b). In view of the
synthetic usefulness of this reaction, para-methoxy aniline
was used as an amine component. The reactions were
carried out; the allylation step was a little slower when
para-methoxy aniline was used instead of aniline. To
ensure the complete conversion of reaction, acid chlorides
were added after 4 h and the acylation reaction proceeded
for 6 h. It turned out that aryl, heteroaryl or a,b-
unsaturated aryl substituted acid chlorides produced the
a-substituted amides in good yield, while aliphatic
chlorides such as 24 and 25 reacted slowly to give the
poor yield (Scheme 4).
4. Experimental
4.1. General
Melting point was recorded on a METTLER FP62 capillary
1
melting point apparatus and is uncorrected. The H NMR
(300 MHz), 13C NMR (75 MHz) and 19F NMR spectra
(282 MHz) were recorded on a Bruker AMX-300 spectro-
meter. Chemical shifts are reported in d-units (ppm) and
J-values (Hz) with Me4Si and CF3COOH as the internal
standard. IR spectra were recorded with a Nicolet AV-360
spectrometer by films and disks. Mass spectra (EI) were
taken on an HP5898-A. Elemental analyses were performed
on a Carlo-Erba 1106. Merrifield resins were received from
Acros. Polyfluoroalkyl sulfonyl fluorides were obtained
from SIOC. All starting materials were used as received
unless otherwise stated. Column chromatography was
performed on silica gel 300–400 mesh (Yantai Chemical
Co. Ltd.).
Figure 1. X-ray structure of compound 26.
4.1.1. Preparation of polystyrene-bound olefin 13 in
quantitative yield according to the literature.13 To a dry
500 mL three-necked flask, dry Merrifield resin PS4 10.0 g
(estimated as 30.0 mmol, 2% DVB, 200–400 mesh, 2.8–
3.0 mmol/g Cl) was suspended in dry THF 100 mL under
nitrogen. Ally magnesium chloride (0.80 M in Et2O,
160 mL, 128 mmol) was slowly added at 0–25 8C in 1 h.
The reaction mixture was stirred at 50 8C for 20 h. After
cooling to room temperature, the mixture was quenched
with 100 mL of THF: 1 N HCl, the mixture was filtered.
The resin was washed successively with water, THF and
MeOH and dried in vacuo to give the polymer-bound olefin
9.83 g (yield %: 98.3%) IR (cmK1, KBr) 3079, 2920, 1941,
1639, 1601, 1493, 1451, 994, 758, 698. Elemental analysis:
Cl!0.1%.
We finally investigated the product 23l of four-component
domino reaction in one operation for preparation of
polycyclic compound by raising the reaction temperature
through intramolecular Diels–Alder reactions to produce
compounds 26 and 27 in moderate yield (Scheme 5). An
X-ray diffraction analysis confirmed the structure and
stereochemistry of 26 in Figure 1. It is well known that
both Lewis acid and heating can promote Diels–Alder
reactions. To investigate either or both are playing in this
reaction, in the absence of Yb–PS2–Rf6 (11b), pure 23l
was subjected to Diels–Alder reaction. Without heating,
no intramolecular Diels–Alder reaction took place
(Scheme 5).

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Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
4.1.2. Typical procedure for synthesis of polymer bound
super acid: addition of perfluoroalkyl chain. To a 250 mL
three-necked flask, dry allyl-PS4 13 5.0 g (estimated as
15 mmol, Cl!0.5% by elemental analysis, derived from
Merrifield resin 2% DVB, 200–400 mesh, 2.8–3.0 mmol/g
Cl), BPO 725 mg (3 mmol, 20 mol%) and I (CF2)6O
(CF2)2SO2F (15) 28.2 g (45 mmol, 3 equiv) were added in
dry toluene 100 mL under dry nitrogen. The mixture was
bulbed for 1 h and then stirred at 110–120 8C for 6 h. The
off-white dispersion turned to dark brown within 2 h.
Another portion of BPO (725 mg, 20 mol%) was added, and
the reaction mixture was stirred at 120 8C for another 20 h.
After cooling to room temperature, the mixture was filtered
and washed successively with water, EtOAc and THF till
the filtrate was colorless. Then filter cake was dispersed in
THF standing overnight, wash by THF, dried (P2O5) at
30 8C till no loss of weight was observed. 17(12.1 g, 85%
conversion) of yellowish power was obtained. Almost
complete consumption of the allylic C–C double bond was
indicated by IR spectrum. IR (cmK1, KBr) 3084, 2926,
1603, 1513, 1465, 1360, 1330, 1248, 1215, 1148, 1118, 991,
822, 699.
9.9!0.004!100/5Z0.792 mmol. 0.132!10K0.792Z
0.528 mmol. Loading of YbZ0.528/2Z0.264 mmol/g
4.1.6. General procedure for three-component coupling
reaction. Aldehyde (10.0 mmol), amine (10.0 mmol),
benzoic acid (367 mg, 10.0 mmol) and [PS2-Rf6SO3]3Yb
(11b) 2.8 mg (0.28 mmol/g, 0.1 mol%) and allyltributyl-
stannane (1.2 mL, 3.3 mmol) were mixed in CH3CN
(15 mL), and it was stirred at room temperature. TLC
monitored the reaction. After filtration, the filtrate was
washed with saturated NaHCO3 solution, extracted with
Et2O (3!10 mL). The combined extracts were dried over
Na2SO4. After removal of solvent at reduced pressure, the
residue was purified by flash chromatography to give
product 22.
N-(1-Phenylbut-3-enyl)aniline (22a).18 Yellow oil; 1H
NMR (300 MHz, CDCl3) d 7.22–7.38 (m, 4H), 7.16–7.22
(m, 1H), 7.05 (t, JZ7.5 Hz, 2H), 6.61 (t, JZ7.4 Hz, 1H),
6.46 (d, JZ7.5 Hz, 2H), 5.63–5.80 (m, 1H), 5.08–5.18 (m,
2H), 4.36 (dd, JZ5.4, 8.1 Hz, 1H), 4.12 (s, 1H), 2.40–2.61
(m, 2H); IR (cmK1, film) 3412, 3054, 2965, 1639, 1602,
1504, 1316, 748, 700.
4.1.3. Reduction of iodide. To a 250 mL three-necked
flask, dry 17 10.3 g (estimated as 8.8 mmol), Bu3SnH 23.6 g
(31 mmol, 3.5 equiv) and AIBN 48 mg (0.3 mmol, 3 mol%)
were added in dry THF 60 mL under nitrogen. The mixture
was heated to reflux for 24 h; another portion of AIBN
(48 mg, 0.3 mmol) was added under reflux for another 24 h.
The reaction mixture was cooled to room temperature, the
mixture was filtered and the polymer was washed
successively with THF, THF/petroleum ether (1:1), EtOAc
and petroleum ether. Then, it was dried at 30 8C till no loss
of weight. 9.3 g of 19 was obtained as yellowish power. IR
(cmK1, KBr) 3084, 2926, 1602, 1512, 1494, 1466, 1360,
1215, 1147, 1021, 822, 699; 19F NMR (282 MHz, CDCl3) d
K121.5 (s, 1F), K4.0 to K10.0 (m, 4F), K35 to K55
(m, 12F). Elemental analysis: I!0.5 wt%, F: 28.6 wt%
(loadingZ0.8 mmol/g).
N-[1-(4-Fluorophenylbut-3-enyl)] aniline (22b). Yellow
oil; 1H NMR (300 MHz, CDCl3) d 7.30 (dd, JZ5.7,
8.7 Hz, 2H), 7.04 (t, JZ7.5 Hz, 2H), 6.96 (t, JZ9.0 Hz,
2H), 6.62 (t, JZ6.9 Hz, 1H), 6.44 (d, JZ7.8 Hz, 2H), 5.62–
5.80 (m, 1H), 5.10–5.20 (m, 2H), 4.36 (dd, JZ5.4, 7.8 Hz,
1H), 4.12 (br s, 1H), 2.38–2.60 (m, 2H); 13C NMR
(75.0 MHz, CDCl3) d 163.6, 160.4, 147.3, 139.4, 139.3,
134.5, 129.3, 128.0, 127.9, 118.7, 177.7, 115.7, 115.4,
113.7, 56.7, 43.5; 19F NMR (282 MHz, CDCl3) d K38.3; IR
(cmK1, film) 3413, 3052, 3020, 2979, 1639, 1603, 1505,
1429, 1315, 1221, 1155, 882, 750, 692; MS (m/z, %): 241,
(MC, 3.36), 200 (100), 77 (17.14). Anal. Calcd for
C16H16FN: C 79.64, H 6.68, F 7.87, N 5.80; found C
79.40, H 6.77, F 7.85, N 6.13.
N-[1-(4-Chlorophenylbut-3-enyl)]aniline (22c).19 Yellow
oil; H NMR (300 MHz, CDCl3) d 7.28 (s, 4H), 7.06 (t,
JZ7.5 Hz, 2H), 6.64 (t, JZ7.5 Hz, 1H), 6.42 (d, JZ7.5 Hz,
2H), 5.64–5.80 (m, 1H), 5.12–5.20 (m, 2H), 4.36 (dd, JZ
5.7, 8.1 Hz, 1H), 4.14 (br s, 1H), 2.36–2.60 (m, 2H); IR
(cmK1, film) 3415, 3079, 3052, 2925, 1639, 1603, 1504,
1316, 1190, 921, 824, 750, 692.
4.1.4. Preparation of sulfonic acid. To a 250 mL flask, dry
19 8.5 g (10.6 mmol, 0.8 mmol/g) was dispersed in 60 mL
of THF. And 12 mL of 1 N NaOH aq was added. The
mixture was stirred at room temperature for 4 h. Then, it
was filtered and washed by water till neutral. Redispersed in
15 mL of HNO3 (1 N), and stirred overnight. After filtration,
it was washed again by water till neutral. 8.0 g of yellowish
power was obtained. IR (cmK1, KBr) 3650, 3027, 2928,
1513, 1454, 1215, 1146, 760, 699. Elemental analysis: F:
28.52 wt%, S, 2.76 wt% (loadingZ0.86 mmol/g).
1
N-[1-(4-Bromophenylbut-3-enyl)]aniline (22d).20 Yellow
oil; 1H NMR (300 MHz, CDCl3) d 7.42 (d, JZ8.4 Hz,
2H), 7.20 (d, JZ8.4 Hz, 2H), 7.03 (dd, JZ7.2, 7.8 Hz, 2H),
6.62 (t, JZ7.2 Hz, 1H), 6.41 (d, JZ7.8 Hz, 2H), 5.61–5.79
(m, 1H), 5.12–5.20 (m, 2H), 4.32 (dd, JZ5.1, 7.8 Hz, 1H),
4.12 (br s, 1H), 2.37–2.60 (m, 2H); IR (cmK1, film) 3412,
3077, 3019, 1639, 1603, 1504, 1316, 1009.
4.1.5. Preparation of ytterbium salt. Sodium salt of 8
(2.0 g, S, 2.76 wt%) was dispersed in 10 mL of YbCl3 soln
(0.132 mmol/mL, titrated by EDTA) and H2O 10 mL, and
the mixture was stirred room temperature overnight. After
filtration, the resin was washed by water and EtOH,
respectively. The resin was dried overnight in vacuo at
65 8C in the presence of P2O5 to afford 2.0 g. The combined
filtrated was diluted to 100, 5 mL of the diluted solution was
taken out and titrated by 0.004 M EDTA for three times.
9.9 mL of EDTA soln. was consumed by average. Thus,
loading of the polymer bound perfluoroalkyl sulfonic
ytterbium was calculated to be 0.264 mmol/g.
N-[1-(4-Methoxyphenylbut-3-enyl)]aniline (22e).19 Yellow
oil; 1H NMR (300 MHz, CDCl3) d 7.22 (d, JZ9.0 Hz, 2H),
7.04–7.08 (m, 2H), 6.80 (d, JZ9.0 Hz, 2H), 6.62 (t, JZ
7.5 Hz, 1H), 6.48 (d, JZ7.8 Hz, 2H), 5.66–5.82 (m, 1H),
5.08–5.20 (m, 2H), 4.32 (dd, JZ5.7, 7.8 Hz, 1H), 4.10 (br s,
1H), 3.74 (s, 3H), 2.40–2.60 (m, 2H); IR (cmK1, film) 3410,
3075, 1638, 1603, 1510, 1246, 1035, 750, 692.

Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
12049
N-[1-(4-Nitrophenylbut-3-enyl)] aniline (22f).19 Yellow oil;
1H NMR (300 MHz, CDCl3) d 8.12 (d, JZ8.7 Hz, 2H), 7.50
(d, JZ8.7 Hz, 2H), 7.04 (dt, JZ7.5, 8.7 Hz, 2H), 6.64 (t,
JZ7.5 Hz, 1H), 6.42 (d, JZ8.7 Hz, 2H), 5.62–5.80 (m, 1H),
5.10–5.22 (m, 2H), 4.42 (dd, JZ5.7, 7.5 Hz, 1H), 4.12 (br s,
1H), 2.40–2.62 (m, 2H); IR (cmK1, film) 3411, 3078, 3020,
1640, 1603, 1521, 1345, 910, 751.
(10 mmol), amine (10 mmol), benzoic acid (10 mmol),
[PS2-Rf6SO3]3Yb (11b) 14 mg (0.5 mol%, 0.280 mmol/g)
and allyltributylstannane (1.1 mmol) were added in CH3CN
15 mL. The resulting mixture was stirred at room
temperature till TLC inferred disappearance of the aldehyde
within 4 h. Then acid chloride (2.2 mmol, 2.2 equiv) was
added and stirred for another 6 h. The mixture was filtrated.
The resin was washed by 20 mL of ethyl acetate. The
combined organic layer was washed by saturated NaHCO3
solution (2!10 mL), H2O (10 mL), then dried over
Na2SO4. Flash chromatography (ethyl acetate: hexaneZ
1:10–1:4) gave the product 23.
N-[1-(3-Methoxyphenylbut-3-enyl)] aniline (22g). Yellow
oil; 1H NMR (300 MHz, CDCl3) d 7.20 (t, JZ7.8 Hz, 1H),
7.02–7.10 (m, 2H), 6.88–6.92 (m, 2H), 6.74 (dd, JZ2.4,
8.1 Hz, 1H), 6.62 (t, JZ7.5 Hz, 1H), 6.50 (d, JZ7.5 Hz,
2H), 5.66–5.80 (m, 1H), 5.08–5.20 (m, 2H), 4.32 (dd, JZ
5.7, 7.8 Hz, 1H), 4.12 (br s, 1H), 3.70 (s, 3H), 2.40–2.60 (m,
2H); IR (cmK1, film) 3409, 3076, 3004, 1639, 1602, 1504,
1263, 1155, 1047, 920, 750, 693.
N-Phenyl-N-(1-phenylbut-3-enyl) benzamide (23a). Color-
less oil; 1H NMR (300 MHz, CDCl3) d 7.22–7.36 (m, 10H),
6.32–6.42 (m, 2H), 5.72–5.94 (m, 2H), 5.43 (m, 1H), 5.08–
5.12 (m, 2H), 2.56–2.76 (m, 2H); 13C NMR (75.0 MHz,
CDCl3) d 165.5, 139.3, 137.9, 134.8, 130.6, 129.0, 128.7,
128.2, 128.0, 127.6, 117.4, 56.8, 35.1; IR (cmK1, film)
3063, 3031, 2929, 1656, 1616, 1594, 1493, 1452, 1405,
1321, 1255, 702; MS (m/z, %): 277 (MC, 3.86), 236 (55.52),
182 (100), 77 (28.73). Anal. Calcd for C19H19NO: C 82.28,
H 6.90, N 5.05; found C 82.04, H 7.12, N 4.96.
N-[1-(2-Furyl)but-3-enyl]aniline (22h).19 Yellow oil; 1H
NMR (300 MHz, CDCl3) d 7.30 (s, 1H), 7.08–7.16 (m, 2H),
6.66 (t, JZ7.5 Hz, 1H), 6.58 (d, JZ8.7 Hz, 2H), 6.22 (s,
1H), 6.12 (s, 1H), 5.64–5.80 (m, 1H), 5.08–5.18 (m, 2H),
4.52 (t, JZ6.0 Hz, 1H), 3.96 (br s, 1H), 3.72 (t, JZ6.6 Hz,
2H); IR (cmK1, film) 3410, 3077, 3021, 1640, 1602, 1504,
1314, 1150, 921, 748, 692.
3-Chloro-N-(4-methoxyphenyl)-N-(1-phenylbut-3-enyl)
benzamide (23b). Colorless oil; 1H NMR (300 MHz,
CDCl3) d 7.20–7.36 (m, 6H), 7.08 (d, JZ4.2 Hz, 1H),
7.00 (d, JZ4.2 Hz, 1H), 6.46–6.60 (m, 4H), 6.30 (t, JZ
7.8 Hz, 1H), 5.82–6.00 (m, 1H), 5.10–5.24 (m, 2H), 3.64 (s,
3H), 2.58–2.74 (m, 2H); 13C NMR (75.0 MHz, CDCl3) d
169.8, 158.5, 139.4, 138.7, 134.9, 131.5, 129.0, 128.9,
128.7, 128.2, 128.1, 128.0, 127.7, 126.0, 117.6, 113.7,
113.4, 55.1, 35.0; IR (cmK1, film) 3064, 3005, 2934, 1643,
1510, 1333, 1249, 1035, 734, 700; MS (m/z, %): 391 (MC,
32.63), 350 (33.18), 261 (34.52), 139 (100), 77 (53.96).
Anal. Calcd for C24H21NO2Cl: C 73.56, H 5.66, N 3.57;
found C 74.33, H 5.96, N 3.55.
1
N-(1-Cyclohexylbut-3-enyl)aniline (22i).18 Yellow oil; H
NMR (300 MHz, CDCl3) d 7.12 (dt, JZ7.2, 8.7 Hz, 2H),
6.62 (t, JZ7.2 Hz, 1H), 6.56 (d, JZ8.7 Hz, 2H), 5.72–5.84
(m, 1H), 5.00–5.08 (m, 2H), 3.50 (br s, 1H), 3.22 (dd, JZ
5.1, 12.9 Hz, 1H), 2.12–2.38 (m, 2H), 1.40–1.56 (m, 1H),
1.00–1.28 (m, 5H); IR (cmK1, film) 3409, 3075, 3018, 2924,
1639, 1601, 1505, 1321, 992, 912, 747, 691.
N-{1-[(E)-2-Phenylethenyl]but-3-enyl}aniline (22j).19 Yel-
low oil; H NMR (300 MHz, CDCl3) d 7.10–7.38 (m, 7H),
6.58–6.72 (m, 4H), 6.22 (dd, JZ6.0, 16.5 Hz, 1H), 5.76–
5.80 (m, 1H), 5.10–5.22 (m, 2H), 4.02 (dd, JZ5.4, 8.4 Hz),
3.80 (br s, 1H), 2.38–2.52 (m, 2H); IR (cmK1, film) 3409,
3054, 3018, 1639, 1601, 1502, 1316, 968, 749, 693.
1
3,5-Dichloro-N-(4-methoxyphenyl)-N-(1-phenylbut-3-enyl)
benzamide (23c). Colorless oil; 1H NMR (300 MHz,
CDCl3) d 7.38 (s, 1H), 7.20–7.32 (m, 5H), 7.06 (d, JZ
8.4 Hz, 1H), 6.94 (d, JZ8.4 Hz, 1H), 6.60 (br s, 1H), 6.30 (t,
JZ7.2 Hz, 1H), 5.84–6.00 (m, 1H), 5.12–5.23 (m, 2H), 3.64
(s, 3H), 2.60–2.82 (m, 2H); 13C NMR (75.0 MHz, CDCl3) d
168.8, 158.8, 139.3, 137.0, 134.9, 133.1, 132.0, 131.6,
131.3, 130.3, 129.6, 128.8, 128.3, 127.9, 127.4, 117.7,
113.7, 57.9, 55.3, 35.1; IR (cmK1, film) 3065, 2934, 1634,
1510, 1454, 1389, 1333, 1296, 1250, 1033, 834, 788, 700;
MS (m/z, %): 425 (MC, 6.26), 384 (70.34), 295 (49.16), 173
(100). Anal. Calcd for C24H20NO2Cl2: C 67.61, H 4.96, N
3.29, Cl, 16.63; found C 67.75, H 5.09, N 3.05, 16.86.
4-Fluoro-N-(1-phenylbut-3-enyl)aniline (22k).19 Yellow
oil; 1H NMR (300 MHz, CDCl3) d 7.20–7.36 (m, 5H),
6.76 (t, JZ8.7 Hz, 2H), 6.40 (m, 2H), 5.66–5.82 (m, 1H),
5.10–5.22 (m, 2H), 4.30 (dd, JZ5.4, 8.7 Hz, 1H), 3.88 (br s,
1H), 2.40–2.62 (m, 2H); IR (cmK1, film) 3415, 3077, 3029,
1639, 1601, 1513, 1221, 921, 819, 701.
4-Nitro-N-(1-phenylbut-3-enyl)aniline (22l).18 Yellow oil;
1H NMR (300 MHz, CDCl3) d 7.98 (d, JZ9.3 Hz, 2H), 7.36
(m, 5H), 6.45 (d, JZ9.3 Hz, 2H), 5.64–5.80 (m, 1H), 5.12–
5.40 (m, 2H), 4.50 (dd, JZ5.4, 12.6 Hz, 1H), 2.50–2.70 (m,
2H); IR (cmK1, film) 3371, 3080, 3029, 1641, 1601, 1525,
1504, 1321, 1112, 833, 754, 701.
N-(4-Methoxyphenyl)-N-(1-phenylbut-3-enyl) furan-2-car-
boxamide (23d). Colorless solid; mp 110 8C; 1H NMR
(300 MHz, CDCl3) d 7.40 (s, 1H), 7.12–7.30 (m, 5H), 6.50–
6.98 (m, 4H), 6.42 (t, JZ7.9 Hz, 1H), 6.14 (s, 1H), 5.70–
5.94 (m, 1H), 5.08–5.36 (m, 3H), 3.76 (s, 3H), 2.56–2.78
(m, 2H); 13C NMR (75.0 MHz, CDCl3) d159.5, 159.4,
147.1, 144.4, 139.2, 135.0, 132.0, 130.7, 129.0, 128.1,
4-Methoxyl-N-(1-phenylbut-3-enyl)aniline (22m).21 Yellow
oil; 1H NMR (300 MHz, CDCl3) d 7.16–7.46 (m, 5H), 6.76
(d, JZ9.0 Hz, 2H), 6.54 (d, JZ9.0 Hz, 2H), 5.76–5.92 (m,
1H), 5.18–5.30 (m, 2H), 4.40 (dd, JZ3.6, 7.8 Hz, 1H), 4.00
(br s, 1H), 3.72 (s, 3H), 2.49–2.70 (m, 2H); IR (cmK1, film)
3405, 3061, 3020, 1638, 1601, 1511, 1238, 1036, 818, 701.
127.7, 117.6, 116.0, 113.9, 110.9, 57.2, 55.4, 34.8; IR (cmK1
,
film) 3063, 3032, 1638, 1510, 1470; MS (m/z, %): 347 (MC,
10.35), 306 (70.44), 237 (10.86), 131 (14.76), 95 (100).
4.1.7. General procedure of one-pot four-component
reaction for synthesis of compound 23. Aldehyde

12050
Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
Anal. Calcd for C22H21NO3: C 76.06, H 6.09, N 4.03; found
C 75.95, H 6.05, N 3.80.
NMR (75.0 MHz, CDCl3) d 158.7, 156.3, 140.0, 135.1,
131.1, 128.9, 128.6, 128.3, 128.2, 127.7, 127.1, 117.5,
113.6, 67.0, 60.0, 55.3, 35.6; IR (cmK1, film) 3064, 3032,
2955, 1698, 1643, 1512, 1454, 1397, 1295, 1248, 1041, 700;
MS (m/z, %): 387 (MC, 8.80), 306 (50.84), 131 (14.22), 91
(100). Anal. Calcd for C25H25NO3: C 77.52, H 6.46, N 3.62;
found C 77.37, H 6.50, N 3.44.
N-Phenyl-N-(1-phenylbut-3-enyl) acryl amide (23e). Yel-
lowish oil; H NMR (300 MHz, CDCl3) d 7.30 (s, 5H),
1
7.18–7.22 (m, 2H), 6.98–7.16 (m, 6H), 6.60 (m, 1H), 6.38
(m, 1H), 5.86–6.04 (m, 1H), 5.14–5.26 (m, 2H), 2.64–2.86
(m, 2H); 13C NMR (75.0 MHz, CDCl3) d 171.0, 139.7,
139.6, 136.8, 135.0, 130.4, 128.9, 128.6, 128.2, 128.1,
127.6, 127.4, 127.2, 117.5, 57.7, 35.1; IR (cmK1, film)
3062, 3032, 2929, 1719, 1693, 1644, 1593, 1493, 1451,
1381, 1333, 1286, 1231, 1026, 919, 699; MS (m/z, %): 327
(MC, 1.41), 286 (32.28), 105 (100), 77 (46.02). Anal. Calcd
for C23H21NO: C 84.37, H 6.46, N 4.28; found C 84.51, H
6.79, N 4.52.
3-Cyclopentyl-N-(4-methoxyphenyl)-N-(1-phenylbut-3-
enyl) propanamide (23j). Colorless oil; 1H NMR (300 MHz,
CDCl3) d 7.04–7.26 (m, 6H), 6.90 (m, 1H), 6.60 (m, 1H),
6.36 (t, JZ8.1 Hz, 1H), 6.02 (m, 1H), 5.76–5.84 (m, 1H),
5.06–5.20 (m, 2H), 3.78 (s, 3H), 2.46–2.64 (m, 2H), 1.78–
2.00 (m, 2H), 1.34–1.64 (m, 9H), 0.78–0.99 (m, 2H); MS
(m/z, %): 377 (MC, 8.39), 336 (20.70), 212 (100), 131
(7.46), 91 (6.13). Anal. Calcd for C25H31NO2: C 79.54, H
8.38, N 3.71; found C 79.39, H 8.42, N 3.63.
N-(4-Methoxyphenyl)-N-(1-phenylbut-3-enyl) cinnamamide
(23f). Yellowish oil; H NMR (300 MHz, CDCl3) d 7.30
1
2-Methoxy-N-(4-methoxyphenyl)-N-(1-phenylbut-3-enyl)
acetamide (23k). Colorless oil; 1H NMR (300 MHz, CDCl3)
d 7.08–7.24 (m, 6H), 6.86 (m, 1H), 6.58 (m, 1H), 6.24 (t, JZ
7.8 Hz, 1H), 6.00 (m, 1H), 5.76–5.82 (m, 1H), 5.04–5.20
(m, 2H), 3.78 (s, 3H), 3.58 (q, JZ15.0 Hz, 2H), 3.30 (s, 3H),
2.48–2.54 (m, 2H); 13C NMR (75.0 MHz, CDCl3) d 169.3,
159.5, 139.2, 135.1, 128.9, 128.8, 128.1, 127.7, 117.5,
114.1, 70.9, 59.1, 56.4, 55.4, 34.8; IR (cmK1, film) 3064,
3032, 2931, 2838, 1670, 1510, 1415, 1394, 1251, 1130,
1031, 702; MS (m/z, %): 325 (MC, 14.30), 284 (100), 256
(56.79), 195 (53.09), 131 (45.91). Anal. Calcd for
C20H23NO3: C 73.28, H 7.12, N 4.30 O 14.75; found C
73.88, H 7.57, N 4.16.
(s, 5H), 7.18–7.22 (m, 2H), 6.98–7.16 (m, 6H), 6.60 (m,
1H), 6.38 (t, JZ7.2 Hz, 1H), 5.86–6.04 (m, 1H), 5.14–5.26
(m, 2H), 2.64–2.86 (m, 2H); 13C NMR (75.0 MHz, CDCl3)
d 171.0, 139.7, 139.6, 136.8, 135.0, 130.4, 128.9, 128.6,
128.2, 128.1, 127.6, 127.4, 127.2, 117.5, 57.7, 35.1; IR
(cmK1, film) 3062, 3032, 2929, 1719, 1693, 1644, 1593,
1493, 1451, 1381, 1333, 1286, 1231, 1026, 919, 699; MS
(m/z, %): 327 (MC, 1.41), 286 (32.28), 105 (100), 77
(46.02). Anal. Calcd for C23H21NO: C 84.37, H 6.46, N
4.28; found C 84.51, H 6.79, N 4.52.
(E)-N-(4-Methoxyphenyl)-3-(4-nitrophenyl)-N-(1-phenyl-
but-3-enyl) acryl amide (23g). Colorless solid; mp143.2 8C;
1H NMR (300 MHz, CDCl3) d 8.12 (d, JZ8.7 Hz, 2H), 7.74
(d, JZ15.6 Hz, 1H), 7.46 (d, JZ9.3 Hz, 1H), 7.12–7.34 (m,
5H), 6.90 (m, 1H), 6.62 (m, 1H), 6.34 (t, JZ7.5 Hz, 1H),
6.20 (d, JZ15.6 Hz, 1H), 6.16 (m, 1H), 5.76–5.84 (m, 1H),
5.06–5.24 (m, 2H), 3.70 (s, 3H, OMe), 2.54–2.66 (m, 2H);
13C NMR (75.0 MHz, CDCl3) d 165.3, 159.3, 147.8, 141.4,
139.2, 139.0, 134.8, 130.0, 128.7, 128.2, 128.1, 127.7,
123.8, 117.5, 114.0, 56.9, 55.3, 35.0; IR (cmK1, film) 3076,
2933, 2246, 1651, 1621, 1596, 1510, 1342, 1294, 1249,
1108, 913, 841, 732, 701; MS (m/z, %): 428 (MC, 11.20),
387 (40.10), 298 (10.86), 216 (100), 176 (30.58), 123
(34.44), 77 (9.30). Anal. Calcd for C26H24N2O4: C 72.90, H
5.61, N 6.54; found C 72.97, H 5.66, N 6.52.
N-(1-(Furan-2-yl) but-3-enyl)-N-(4-methoxyphenyl) acryl
amide (23l). White solid; mp 78 8C; H NMR (300 MHz,
1
CDCl3) d 7.08 (s, 1H), 7.06 (m, 1H), 6.64–6.88 (m, 2H),
6.20–6.40 (m, 4H), 5.68–5.82 (m, 1H), 5.10–5.18 (m, 2H),
4.46 (t, JZ6.3 Hz, 1H), 3.72 (s, 3H), 2.62 (m, 2H); 13C
NMR (75.0 MHz, CDCl3) d 168.6, 162.0, 155.6, 144.4,
137.0, 133.2, 131.6, 130.5, 120.4, 112.9, 111.5, 58.1, 54.2,
37.2; IR (cmK1, film) 3077 2933, 2246, 1652 1620 1596
1500; MS (m/z, %) 297, (MC, 31.87), 256 (69.61), 202
(92.10), 177 (100), 91 (24.54), 7728.27). Anal. Calcd for
C18H19NO3: C 72.73, H 6.40, N 4.71; found C 72.53, H
6.56, N 4.56.
N-(4-Methoxyphenyl)-2-phenyl-N-(1-phenylbut-3-enyl)
acetamide (23h). Yellowish oil; 1H NMR (300 MHz,
CDCl3) d 7.00–7.26 (m, 11H), 6.82 (d, JZ7.5 Hz, 1H),
6.58 (d, JZ8.1 Hz, 1H), 6.24 (t, JZ7.8 Hz, 1H), 5.96 (d,
JZ8.1 Hz, 1H), 5.76–5.92 (m, 1H), 5.04–5.20 (m, 2H) 3.78
(s, 3H), 3.34 (s, 2H), 2.50–2.64 (m, 2H); 13C NMR
(75.0 MHz, CDCl3) d 172.8, 160.6, 140.9, 137.0, 136.5,
132.1, 130.5, 130.2, 129.6, 129.5, 129.0, 127.8, 118.8,
115.2, 57.9, 56.8, 43.3, 36.5; IR (cmK1, film) 3064, 3030,
2928, 1649, 1510, 1249, 700; MS (m/z, %): 371 (MC,
10.64), 330 (42.19), 212 (100), 91 (30.92). Anal. Calcd for
C25H25NO2: C 80.83, H 6.78, N 3.77; found C 80.60, H
6.72, N 3.64.
4.1.8. Procedure of the one-pot four-component intra-
molecular Diels–Alder reaction of 23l. In a 25 mL three-
necked flask, furfuraldehyde 166 mL (2 mmol), p-methy-
oxyaniline 246 mg (2 mmol), benzoic acid 244 mg
(2 mmol), [PS2–Rf6SO3]3Yb(11b) 28 mg (0.5 mol%,
0.28 mmol/g) and allyltributylstannane 0.68 mL
(2.2 mmol) were dissolved in 4 mL of CH3CN. The mixture
was stirred at room temperature for 4 h. 0.36 mL (4.4 mmol,
2.2 equiv) of acrylic chloride was then added and reacted at
room temperature for another 6 h. The mixture was heated
to reflux for 15 h. Then, the mixture was cooled to room
temperature. After filtration, the polymer was washed by
20 mL of ethyl acetate. The combined organic layer was
washed by saturated NaHCO3 solution (2!10 mL), H2O
(10 mL), then dried over Na2SO4. Flash chromatography
(ethyl acetate: hexaneZ1:1) gave 259 mg of compound 26
and 58 mg of compound 27 (4.5:1, total yield 53%),
respectively.
N-Benzyl-N-4-methoxyphenyl (1-phenylbut-3-enyl) carba-
mate (23i). Colorless oil; H NMR (300 MHz, CDCl3) d
1
7.02–7.56 (m, 10H), 6.58–6.76 (m, 4H), 5.68–5.84 (m, 2H),
5.02–5.08 (m, 4H), 3.70 (s, 3H), 2.50–2.74 (m, 2H); 13C

Y. Yin et al. / Tetrahedron 61 (2005) 12042–12052
12051
2. (a) England, D. C. US Patent 2852554, 1958; Du Pont; Chem.
Abstr. 1959, 53, 2253. (b) Olah, G. A.; Lyer, P. S.; Prakash,
G. K. S. Synthesis 1986, 513. (c) Kobayashi, S.; Nagayama, S.
J. Org. Chem. 1996, 61, 2256. (d) Kobayashi, S.; Nagayama,
S. J. Am. Chem. Soc. 1996, 118, 8977. (e) Yu, L. B.; Chen,
D. P.; Li, J.; Wang, P. G. J. Org. Chem. 1997, 62, 3575.
(f) Nagayama, S.; Kobayashi, S. Angew. Chem., Int. Ed. 2000,
39, 567. (g) Ishihara, K.; Hasegawa, A.; Yamamoto, H. Angew.
Chem., Int. Ed. 2001, 40, 4077.
2-Allyl-3-(4-methyoxyphenyl)-4-oxo-10-oxa-3-azo-tricyclo
[5.2.1.01,5] dec-8-en-4-one (26). White solid; mp 82 8C; 1H
NMR (300 MHz, CDCl3) d 7.26 (d, JZ9.0 Hz, 2H), 6.96 (d,
JZ9.0 Hz, 2H), 6.58 (d, JZ5.9 Hz, 1H), 6.42 (dd, JZ1.7,
5.9 Hz), 5.76–5.84 (m, 1H), 5.14–5.24 (m, 2H), 5.06 (dd,
JZ1.7, 4.5 Hz, 1H), 4.42 (t, JZ5.2 Hz, 1H), 3.80 (s, 3H),
2.58–2.66 (m, 3H), 2.25 (ddd, JZ3.6, 4.5, 11.8 Hz, 1H),
1.62 (dd, JZ8.9, 11.8 Hz, 1H); 13C NMR (75.0 MHz,
CDCl3) d 173.7, 157.8, 137.4, 132.3, 132.1, 130.5, 126.1,
119.4, 114.5, 91.7, 78.6, 62.1, 55.5, 47.4, 34.2, 28.9; IR
(cmK1, film) 3077, 3002, 2952, 2837, 2244, 1697, 1640,
1513, 1247, 1035, 918, 831, 731, 699; MS (m/z, %): 297
(MC, 37.59), 256 (21.44), 202 (100), 177 (16.16), 91 (7.19),
77 (12.67). Anal. Calcd for C18H19NO3: C 72.73, H 6.40, N
4.71; found C 72.72, H 6.34, N 4.50. Crystal system, space
group: monoclinic, P2(1)/c. Unit cell dimensions: aZ
3. (a) Kobayashi, S.; Nagayama, S. J. Am. Chem. Soc. 1998, 120,
2985. (b) Kobayashi, S.; Akiyama, R. Chem. Commun. 2003,
449. (c) Barrett, A. G. M.; Braddock, D. C.; Catterrick, D.;
Chadwick, D.; Henschke, J. P.; Mckinnell, R. M. Synlett 2000,
847. (d) Mikami, K.; Mikami, Y.; Matsumoto, Y.; Niskikido,
J.; Yamamoto, F.; Nakajima, H. Tetrahedron Lett. 2001, 42,
289.
˚
˚
˚
4. Corma, A. Chem. Rev. 1995, 95, 559.
6.4883(5) A, bZ31.818(3) A, cZ14.7894(12) A, aZ908,
3
˚
´
5. (a) Farrall, M. J.; Frechet, J. M. J. Org. Chem. 1976, 41, 3877.
(b) Santini, R.; Griffith, M. C.; Qi, M. Tetrahedron Lett. 1998,
39, 8951.
bZ94.0950(10)8, gZ908; volume: 3045.4(4) A ; ZZ8;
calculated density: 1.297 mg/m3; absorption coefficient:
0.088 mmK1; F(000): 1264; crystal size: 0.478!0.453!
0.412 mm3; theta range for data collection: 1.38–27.008;
completeness to qZ27.00, 99.9%; data/restraints/para-
meters: 11191/23/925; goodness-of-fit on F2: 0.930; final
R indices[IO2s(I)]: R1Z0.0552, wR2Z0.1251; R indices
(all data): R1Z0.0816, wR2Z0.1368; absolute structure
parameter: K0.7(14); largest diff. peak and hole: 0.184 and
6. Leadbeater, N. E.; Marco, M. Chem. Rev. 2002, 102, 3217.
7. (a) Ishihara, K.; Hasegawa, A.; Yamamoto, H. Synlett 2002,
1296. (b) Ishihara, K.; Hasegawa, A.; Yamamoto, H. Synlett
2002, 1299.
8. (a) Rode, B. M.; Engelbrecht, A.; Schantl, J. Z. Phys. Chem.
(Leipzig) 1973, 253, 17. (b) Foropoulos, J.; DeaMarteau, D. D.
Inorg. Chem. 1984, 23, 3270. (c) Gas phase acidity: Koppel,
I. A.; Taft, R. W.; Aniva, F.; Zhu, S. Z.; Hu, L. Q.; Sung, K. S.;
DeaMarteau, D. D.; Yagupolskii, Y. L.; Vlasov, V. M.;
Notario, R.; Maria, P. C. J. Am. Chem. Soc. 1994, 116, 3047.
9. Review: (a) Dolmling, A.; Ugi, I. Angew. Chem., Int. Ed.
2000, 39, 3168. (b) Zhu, J.-P. Eur. J. Org. Chem. 2003,
1133. (c) Bienayme, H.; Hulme, C.; Oddon, G.; Schimitt, P.
Chem. Eur. J. 2000, 6, 3321. (d) Beck, B.; Picard, A.;
Herdtweck, E.; Dolmling, A. Org. Lett. 2004, 6, 39. (e) Fayol,
A.; Zhu, J.-P. Org. Lett. 2004, 6, 115. (f) Yong, I. S.; Kerr,
M. A. Org. Lett. 2004, 6, 139. (g) Frantz, D. E.; Morency, L.;
Soheili, A.; Murry, J. A.; Grabowski, E. J. J.; Tillyer, R. D.
Org. Lett. 2004, 6, 843. (h) Nair, V.; Menon, R. S.; Beneesh,
P. B.; Sreekumar, V.; Bindu, S. Org. Lett. 2004, 6, 767.
(i) Yamamoto, Y.; Nakano, S.; Maekawa, H.; Nishiguchi, I.
Org. Lett. 2004, 6, 799. (j) Neijere, A.; Nu¨ske, H.; E-Sayed,
3
˚
K0.246 e A .
Compound 27. White solid; mp 100 8C; 1H NMR
(300 MHz, CDCl3) d 7.20 (d, JZ9.0 Hz, 2H), 6.96 (d, JZ
9.0 Hz, 2H), 6.42 (dd, JZ1.8, 6.0 Hz, 1H), 6.38 (dt, JZ1.5,
5.7 Hz), 5.66–5.82 (m, 1H), 5.00–5.16 (m, 3H), 4.56 (dt, JZ
6.6, 8.4 Hz, 1H), 3.80 (s, 3H), 2.60 (dd, JZ1.8, 8.7 Hz, 1H),
2.24–2.38 (m, 3H), 1.62 (dd, JZ8.7, 11.7 Hz, 1H); 13C
NMR (75.0 MHz, CDCl3) d 173.8, 158.1, 135.6, 134.2,
132.9, 129.6, 127.2.1, 118.3, 114.3, 90.6, 78.5, 60.4, 55.4,
47.6, 32.9, 28.6; IR (cmK1, film) 3077, 3002, 2953, 2837,
2243, 1697, 1642, 1513, 1364, 1247, 1036, 918, 835, 732;
MS (m/z, %): 297 (MC, 44.30), 256 (24.16), 202 (100), 77
(14.87). Anal. Calcd for C18H19NO3: C 72.73, H 6.40, N
4.71; found C 73.03, H 6.58, N 4.56.
¨
M.; Labahn, T.; Schroen, M.; Brase, S. Angew. Chem., Int. Ed.
1998, 37, 3669. (k) Nakamura, H.; Yamamoto, H. Chem.
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1999, 1565.
Acknowledgements
We are grateful to the Ministry of Sciences and Technology,
the State Key Project of Basic Research (Project 973, NO. G
20000448007) and National Natural Science Foundation of
China for financial support.
10. (a) Bellucci, C.; Cozzi, P. G.; Umani-Ronchi, A. Tetrahedron
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