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S. S. Shinde et al. / Tetrahedron Letters 49 (2008) 4245–4248
Table 4
Nucleophilic substitution reactions of mesylate 6a
O
O
3, MNu
CH3CN
7a, X = Br
7b, X = Cl
7c, X = I
MsO
O
X
O
6
100 ºC
7d, X = OAc
Entry
3
MNu
Time (h)
Yieldb (%)
1
2
3
4
5
6
7
8
9
3a/3b/3c
3a/3b/3c
3a/3b/3c
3c
3c
3c
3c
3c
3c
KCl
NaBr
KBr
KCl
NaBr
KBr
CsBr
KI
KOAc
2.0
2.0
0.5
5.0
6.0
1.1
0.8
0.5
0.8
16/25/52
—/18/66
17/32/73
96
90
98
99
98
99
a
All reactions were carried out on a 0.5 mmol scale of mesylate 6 using 1.5 mmol MNu and 0.5 equiv of 3 in CH3CN (3 mL) at 100 °C.
b
Conversion determined by 1H NMR in entries 1–3, and isolated yield in entries 4–9.
O
O
NaN3, CH3CN
100 ºC, 3.5 h
8
N3
O
Br
O
7a
3 recycles
run
yield (%)
1
2
3
98
98
97
3c (5 mol%)
Scheme 4. Recycle of 3c in azidation reaction.
insoluble NaBr in CH3CN, despite the absence of any hydrogen
bonding interaction. Based on our experimental finding that poly-
mer catalyst 3c has a superior activity as a PTC to the others, sev-
eral nucleophilic substitutions were attempted under the same
condition for different reaction times, depending on the reactant
reactivities. Chlorination with KCl was completed within 5.0 h with
a product yield of 96%. Bromination was carried out using three al-
kali metal bromides (entries 5–7) to afford good to excellent yields.
Iodinated compound was readily synthesized by using KI with a
yield of 98%. Acetoxylation with KOAc was completed in 0.8 h
and provided a product yield of 99%.
mass spectra were carried out at the Korea Basic Science Institute
(Daegu, Korea).
Supplementary data
Experimental procedures and spectral data for all compounds
are available. Supplementary data associated with this article can
References and notes
Nucleophilic azidation of bromo compound 7a was also per-
formed under the same condition as the other reactions listed in
Table 4 using polymer catalyst 3c (Scheme 4). The polymer catalyst
3c catalyzed that reaction well, affording a 98% yield for azido
compound 8, and was recovered by simple filtration and was
reused twice more without any loss of activity and product yield.
In conclusion, three polymer-supported, quaternary ammo-
nium mesylates, 3a–c, were synthesized and used as recyclable,
polymeric PTCs in various nucleophilic substitution reactions.
PS[him-tOH][OMs] (3c), having a tertiary alcohol group-containing
IL [mim-tOH][OMs], showed an excellent and superior catalytic
activity compared to that of the other two polymer catalysts, 3a
and 3b. This catalyst is therefore expected to be generally applica-
ble to various phase transfer catalysis.
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Acknowledgments
This work was supported by a Korea Science and Engineering
Foundation (KOSEF) grant funded by the Korea government
(MOST) (2007-02236) and a Korea Health 21 R&D Project, Ministry
of Health & Welfare, Republic of Korea (A062254). High resolution
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