Yb[N(SO2C8F17)2]3-catalyzed allylation of 1,3-dicarbonyl compounds with allylic alcohols in a fluorous biphase system

Article abstract of DOI:10.1016/j.jfluchem.2009.03.006

Allylation of 1,3-dicarbonyl compounds with allylic alcohols was successfully accomplished using rare earth metal (III) bis(perfluorooctanesulfonyl)imide [RE(NPf₂)₃, RE = La～Lu] as catalysts in fluorous solvents. Ytterbium bis(perflu

Full text of DOI:10.1016/j.jfluchem.2009.03.006

Journal of Fluorine Chemistry 130 (2009) 595–599
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Short communication
Yb[N(SO2C8F17)2]3-catalyzed allylation of 1,3-dicarbonyl compounds with allylic
alcohols in a fluorous biphase system
*
Ming-Gui Shen, Chun Cai , Wen-Bin Yi
Chemical Engineering College, Nanjing University of Science & Technology, Nanjing 210094, Jiangsu, China
A R T I C L E I N F O
A B S T R A C T
Article history:
Allylation of 1,3-dicarbonyl compounds with allylic alcohols was successfully accomplished using rare
earth metal (III) bis(perfluorooctanesulfonyl)imide [RE(NPf2)3, RE = LaꢀLu] as catalysts in fluorous
solvents. Ytterbium bis(perfluorooctanesulfonyl)imide [Yb(NPf2)3] catalyzes the high efficient reaction
of allylation in fluorous solvents. By simple separation, fluorous phase containing only catalyst can be
reused several times.
Received 7 January 2009
Received in revised form 20 March 2009
Accepted 23 March 2009
Available online 2 April 2009
ß 2009 Elsevier B.V. All rights reserved.
Keywords:
Allylation
Allylic alcohols
Fluorous biphasic catalysis
Rare earth(III)
bis(perfluorooctanesulfonyl)amide
1. Introduction
There has been rapidly increasing interest in the design and
synthesis of compounds that exhibit high affinities for ‘‘fluorous’’
Allylation of 1,3-dicarbonyl compounds is an important type of
carbon–carbon bond formation reaction in organic synthesis [1,2].
Many works have been devoted to this transformation in order to
develop new methods consisting of inexpensive and readily
available starting materials, atom-economy, mild reaction condi-
tions, simple manipulation, and environmentally friendly catalysts
[3–13]. A recent example is the establishment of new synthetic
strategies that employ allylic alcohols as the allylating reagent in the
presence of various transition-metal based reagents, such as
palladium in the presence of a base or acid [3–5]; equimolar
amounts of Cu(I) [6] and Co-salts [7,8]. Recently, Lewis acids such as
BF3ÁOEt2 [9], InCl3 [10], and FeCl3 [11] or BrØnsted acids such as p-
toluenesulfonic acid [12] and H-Montmorillonite [13] have also
been reported to catalyze this reaction efficiently. However, most of
these methods have problems including drastic reaction conditions,
long reaction times and use of expensive, toxic and moisture
sensitive reagents. Recently, Noji [14] and Huang [15] group
reported that certain metal triflates can catalyze the allylation of
1,3-dicarbonyl compounds with allylic alcohols giving rise to the
desired products in good to excellent yields. However, for the reuse
of these catalysts, tedious work up procedures such as filtration,
purification and drying should be required. Iodine (I2) as a catalyst
was also reported for the allylation of 1,3-dicarbonyl compounds by
Rao’s group [16]. However, the catalyst iodine cannot be recycled.
phases since the technique of ‘‘fluorous biphasic system’’ (FBS) was
´
described by Horvath and Rabai [17–19]. The technique of FBS, as a
phase-separation and catalyst immobilization technique, has
become one of the most important methods for facile catalyst
separation from the reaction mixture and recycle use of the
catalyst [18,19]. In this catalytic system, the metallic catalyst
coordinated by perfluoroalkylated ligands can dissolve into the
fluorous phase after the reaction. Recently, novel Lewis acids of
lanthanide tris(perfluorooctanesulfonyl)methide {Ln[C(SO2Rf8)]3,
Rf8 = (CF2)7CF3, Ln(CPf3)3} [20,21], lanthanide bis(perfluoroocta-
nesulfonyl)imide {Ln[N(SO2Rf8)2]3, Ln(NPf2)3} [22] and lanthanide
perfluorooctanesulfonate [Ln(OSO2Rf8)3, Ln(OPf)3] [23–29] have
been of special interest due to their characteristic features such as
moisture insensitivity, ease of handling, robustness for the reuse
and high solubility in fluorous solvent.
During our studies to explore the utility of fluorinated Lewis
acid catalysts in fluorous solvents [26–29], we found that the
allylation of 1,3-dicarbonyl compounds with allylic alcohols can
proceed smoothly in the presence of ytterbium bis(perfluoroocta-
nesulfonyl)imide [Yb(NPf2)3] in
a FBS system [Scheme 1].
Concurrently, we also found that the robustness of the catalytic
system for reuse can be obtained by simple phase-separation.
2. Results and discussion
The reaction of allylic alcohol 1a with 2,4-pentadione 2a in
perfluorodecalin (C10F18, cis- and trans-mixture) was selected as a
model reaction for studying the effect of co-solvent and catalyst.
* Corresponding author. Tel.: +86 25 84315514; fax: +86 25 84315030.
E-mail address: c.cai@mail.njust.edu.cn (C. Cai).
0022-1139/$ – see front matter ß 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2009.03.006

596
M.-G. Shen et al. / Journal of Fluorine Chemistry 130 (2009) 595–599
Scheme 1.
Table 1
Table 2
Effect of the catalysts on the allylation reactiona.
Allylation reaction in different co-solvents and the amount of catalyst loadinga.
Entry
Catalyst loading (mol%)
Co-solvent
Time (h)
3aa yield (%)b
Entry
Catalyst
3aa yield (%)b
1
2
3
4
5
6
7
8
1
CH3NO2
CH3NO2
CH3NO2
CH3NO2
MeCN
6
6
90
80
72
–
1
2
Yb(NPf2)3
Ce(NPf2)3
Nd(NPf2)3
Sm(NPf2)3
Eu(NPf2)3
Tb(NPf2)3
Dy(NPf2)3
Er(NPf2)3
La(NPf2)3
Lu(NPf2)3
90
84
81
85
69
81
76
76
66
66
0.75
0.5
–
6
3
12
6
4
1
73
35
70
50
5
1
PhMe
6
6
1
1,4-Dioxane
THF
6
7
1
6
8
9
a
The reaction condition: Yb(NPf2)3 (0.31 g, 0.1 mmol), allylic alcohol 1a (2.10 g,
10 mmol), 2,4-pentadione 2a (1.08 g, 12 mmol), co-solvent (2 mL) and perfluor-
odecalin (C10F18, cis- and trans-mixture, 2 mL), 80 8C.
10
a
The reaction condition: RE(NPf2)3 (0.31 g, 0.1 mmol), allylic alcohol 1a (2.10 g,
10 mmol), 2,4-pentadione 2a (1.08 g, 12 mmol), CH3NO2 (2 mL) and perfluorode-
calin (C10F18, cis- and trans-mixture, 2 mL), 80 8C, 6 h.
b
Isolated yields.
b
Isolated yields.
Table 1 shows the influence of co-solvent and the amount of
catalyst. We found that treating a solution of allylic alcohol 1a
(1 equiv.) and 2,4-pentadione 2a (1.2 equiv.) in CH3NO2 with
1 mol% Yb(NPf2)3 as catalyst at 80 8C for 6 h gave the product 3aa in
90% yield (Table 1, entry 1). Under the similar condition, lower
product yields of 72–80% were obtained when decreasing the
catalyst amount from 1 to 0.75, and 0.5 mol% (Table 1, entries 2 and
3), and no reaction was observed in the absence of Yb(NPf2)3 after
12 h (Table 1, entry 4). In contrast, the reactions operated in other
co-solvent were less effective and lower product yields of 35–73%
were obtained for reactions in MeCN, toluene, 1,4-dioxane or THF
as the co-solvent (entries 5–8). Nitromethane proved to be the
most efficient and was selected as the co-solvent for the
subsequent investigation.
Table 2 shows the catalytic activity of 10 different rare earth
metal-imide complexes in perfluorodecalin. Yb(NPf2)3 was found
to be the most efficient catalyst, which produced almost
quantitative yield of the desired product in perfluorodecalin.
The use of the catalytic system Yb(NPf2)3/C10F18 was extended to
explore the scope of the reaction to various allylic alcohols and 1,3-
dicarbonyl compounds. As shown in Table 3, 1,3-dicarbonyl
compounds 2a and 2b were allylated by five different allylic
alcohols togivethe corresponding products inmoderateto excellent
Table 3
Yb(NPf2)3 catalyzed allylation reaction of 1,3-dicarbonyl compounds and allylic alcoholsa.
Entry
Alcohol
2,4-pentadione
Product
Yield (%)b
1
90
2
88

M.-G. Shen et al. / Journal of Fluorine Chemistry 130 (2009) 595–599
597
Table 3 (Continued )
Entry Alcohol
2,4-pentadione
Product
Yield (%)b
3
85
4
92
90
5
6
88
7
85
8
82
89
9
10
87
a
The reaction condition: Yb(NPf2)3 (0.31 g, 0.1 mmol), allylic alcohol (10 mmol), 2,4-pentadione (12 mmol), CH3NO2 (2 mL) and perfluorodecalin (C10F18, cis- and trans-
mixture, 2 mL), 80 8C, 6 h.
b
Isolated yields base on the starting alcohol.

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M.-G. Shen et al. / Journal of Fluorine Chemistry 130 (2009) 595–599
Table 4
4.3. Typical procedure for allylation of 1,3-dicarbonyl compounds
Recycling studies of catalyst.
with allylic alcohols
Entry
Run
Yield (%)a
A mixture of Yb(NPf2)3 (0.31 g, 0.1 mmol), allylic alcohol 1a
(2.10 g, 10 mmol), 2,4-pentadione 2a (1.08 g, 12 mmol), CH3NO2
(2 mL) and perfluorodecalin (2 mL). The mixture was stirred at
80 8C for 6 h. Then, the fluorous layer on the bottom was separated
for the next reaction. The organic solvent in the reaction mixture
(organic phase) was removed under reduced pressure and the
residue was purified by SiO2 gel column chromatography using
CH2Cl2:MeOH (99:1) as a eluent.
1b
2
–
–
90c
87
Run 1
Run 2
Run 3
Run 4
3
4
88
5
87
a
Isolated yields.
b
Blank experiment without using catalyst.
Experiment 1, reaction conditions as Table 2.
c
Compound 3aa (Lit. [16]): 90% yield; 1H NMR (500 MHz, CDCl3)
d
= 1.93 (s, 3H), 2.24 (s, 3H), 3.77–3.79 (d, J = 0.8 Hz, 1H), 4.25–4.27
yields. The substituents on the allylic alcohols 1a, 1b, 1c and 1d had
noobviouseffect onthe conversion(entries 1–4, 6–9). Allylicalcohol
1e have the similar reaction activity with the other four allylic
alcohols (entries 5, 10). In all cases, the double bonds on the allylic
alcohols were not migrated (checked by 1H NMR) and the reactions
proceeded very cleanly (checked by TLC) and no side reaction
products were observed.
(m, 1H), 6.02–6.08 (dd, J = 8.2, 15.7 Hz, 1H), 6.32 (d, J = 15.7 Hz,
1H), 6.77–7.20 (m, 10H); MS (EI) m/z 292 (M+).
Compound 3ba (Lit. [16]): 88% yield; 1H NMR (500 MHz, CDCl3)
d
= 1.91 (s, 3H), 2.22 (s, 3H), 3.74–3.79 (m, 4H), 3.94 (s, 3H), 4.25–
4.27 (m, 1H), 6.01–6.07 (dd, J = 8.2, 15.7 Hz, 1H), 6.30 (d,
J = 15.7 Hz, 1H), 6.80–7.22 (m, 8H); MS (EI) m/z 320 (M+).
Compound 3ca (Lit. [16]): 85% yield; 1H NMR (500 MHz, CDCl3)
To examine the reusability of the catalytic system, the catalyst
recovered by simple phase-separation from the reaction mixture of
allylation reaction was reused for the next experiment (up to four
cycles) under the reaction condition described in Table 2. The results
shown in Table 4 indicate that the catalyst can be reused without
significant loss in activity. When the reaction was finished, and then
the catalyst mixture was cooled to room temperature. The fluorous
phase containing RE(NPf2)3 can be separated from the organic layer
and returned to the bottom layer. Based on GC–MS and 19F NMR
data,nodistributionofYb(NPf2)3 wasfoundinorganiclayerandonly
trace amount of perfluorodecalin leached to organic phase was
detected.
d = 1.95 (s, 3H), 2.23 (s, 3H), 4.13–4.47 (m, 2H), 6.12 (dd, J = 8.2,
15.7 Hz, 1H), 6.33 (d, J = 15.8 Hz, 1H), 7.11–7.44 (m, 8H); MS (EI) m/
z 361 (M+).
Compound 3da (Lit. [15]): 92% yield; 1H NMR (500 MHz, CDCl3)
d
= 1.92 (s, 3H), 2.23 (s, 3H), 3.77–3.79 (m, 7H), 4.25–4.27 (m, 1H),
6.02–6.08 (dd, J = 8.2, 15.7 Hz, 1H), 6.32 (d, J = 15.7 Hz, 1H), 6.80–
7.22 (m, 8H); MS (EI) m/z 352 (M+).
Compound 3ea (Lit. [16]): 90% yield; 1H NMR 500 MHz, CDCl3)
d
= 1.20 (d, J = 8.7 Hz, 3H), 1.95 (s, 3H), 2.25 (s, 3H), 3.77–3.79 (d,
J = 10.8 Hz, 1H), 4.25–4.27 (m, 1H), 6.02–6.08 (dd, J = 8.2, 15.7 Hz,
1H), 6.32 (d, J = 15.7 Hz, 1H), 6.80–6.89 (m, 5H); MS (EI) m/z 234
(M+).
Compound 3ab (Lit. [12]): 88% yield; 1H NMR 500 MHz, CDCl3)
3. Conclusion
d = 1.03 (t, J = 7.0 Hz, 3H), 1.95 (s, 3H), 3.87–3.96 (m, 3H), 4.18 (m,
1H), 6.04–6.09 (dd, J = 8.2, 15.7 Hz, 1H), 6.35 (d, J = 15.7 Hz, 1H),
6.77–7.20 (m, 10H); MS (EI) m/z 322 (M+).
In conclusion, RE(NPf2)3 are demonstrated to be new and highly
effective catalysts for the allylation of 1,3-dicarbonyl compounds
with allylic alcohols in fluorous biphasic system (FBS). By simple
separation of the fluorous phase containing only catalyst, the
reaction can be repeated many times. Further study on the
application of FBS to other reactions, which can be promoted by
such Lewis acids, is under way in this laboratory.
Compound 3bb (Lit. [16]): 85% yield; 1H NMR 500 MHz, CDCl3)
d
= 1.05 (t, J = 7.0 Hz, 3H), 1.98 (s, 3H), 3.74–3.78 (s, 6H), 3.87–3.96
(m, 3H), 4.18 (m, 1H), 6.02–6.08 (dd, J = 8.2, 15.7 Hz, 1H), 6.33 (d,
J = 15.7 Hz, 1H), 6.82–7.24 (m, 8H); MS (EI) m/z 350 (M+).
Compound 3cb (Lit. [16]): 82% yield; 1H NMR 500 MHz, CDCl3)
d
= 1.05 (t, J = 7.0 Hz, 3H), 1.95 (s, 3H), 3.87–3.96 (m, 3H), 4.18 (m,
1H), 6.04–6.09 (dd, J = 8.2, 15.7 Hz, 1H), 6.35 (d, J = 15.7 Hz, 1H),
6.77–7.20 (m, 8H); MS (EI) m/z 391 (M+).
4. Experimental
Compound 3db (Lit. [15]): 89% yield; 1H NMR 500 MHz, CDCl3)
4.1. General
d = 1.03 (t, J = 7.0 Hz, 3H), 1.95 (s, 3H), 3.77–3.79 (s, 6H), 3.89–3.99
(m, 3H), 4.18 (m, 1H), 6.04–6.09 (dd, J = 8.2, 15.7 Hz, 1H), 6.35 (d,
J = 15.7 Hz, 1H), 6.77–7.20 (m, 8H); MS (EI) m/z 382 (M+).
Compound 3eb (Lit. [15]): 87% yield; 1H NMR 500 MHz, CDCl3)
Chemicals used were obtained from commercial suppliers and
used without further purifications. 1H NMR and 19F NMR spectra
were recorded with a Bruker Advance RX500 spectrometer. Mass
spectra were recorded on a Saturn 2000GC/MS instrument.
Inductively coupled plasma (ICP) spectra were measured on an
Ultima2C apparatus. Elemental analyses were performed on a
Yanagimoto MT3CHN recorder.
d
= 1.03 (t, J = 7.0 Hz, 3H), 1.20 (d, J = 8.7 Hz, 3H), 1.95 (s, 3H), 3.77–
3.99 (m, 3H), 4.25–4.27 (m, 1H), 6.02–6.08 (dd, J = 8.2, 15.7 Hz, 1H),
6.32 (d, J = 15.7 Hz, 1H), 6.80–6.89 (m, 5H); MS (EI) m/z 264 (M+).
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