2119
R. Ghanbaripour et al.
Letter
Synlett
Table 2 Synthesis of Benzoate Derivatives
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X
O
C
TBHP (1.3 equiv)
magnetic catalyst (15 mg)
Me
+
X
O
O
DMF, 80 °C
R
O
R
3
4
5
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Entry
R
X
Product
Yield (%)
1
2
3
4
5
6
7
8
H
O
5a
5b
5c
5d
5e
5f
83
85
55
90
64
49
51
38
Me
Cl
O
O
OMe
Br
O
O
H
CH2
CH2
CH2
Me
Cl
5g
5h
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Chem. Soc. 2012, 9, 791.
dried at 100 °C overnight. The recovered catalyst could be
used at least five times without significant loss in yield. To
examine whether there was any leaching of the copper
complex, we removed the catalyst by using a magnet 10
minutes after the beginning of the reaction, and we ob-
served that the reaction did not reach completion, even af-
ter 24 hours. This clearly confirmed that the active species
does not leach into the solvent. Furthermore, ICP analysis
showed that there was no copper in solution
In summary, we have developed a novel magnetic cata-
lyst functionalized with a Schiff base–copper complex. The
new catalyst was characterized by a range of physical tech-
niques and its catalytic activity was successfully demon-
strated in oxidative C(sp2)–O and C(sp3)–O coupling reac-
tions. The recyclability of the catalyst, ease of manipulation,
shorter reaction times in comparison with other reported
catalysts, and good yields are the main advantages of this
protocol.
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2014, 16, 3086.
Supporting Information
Supporting information for this article is available online at
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u
p
p
ortioInfgrmoaitn
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u
p
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ortiInfogrmoaitn
References and Notes
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(15) Enol Carbamates 2a–g; General Procedure
A 70% aq solution of TBHP (0.193 g, 1.5 equiv) was added drop-
wise to a mixture of the appropriate 1,3-dicarbonyl compound
1 (1 mmol), the magnetic catalyst (10 mg), and DMF (2 mL). The
mixture was heated to 80 °C, stirred for 20 min, and then cooled
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 2117–2120