Y. Chen, P. G. Wang / Tetrahedron Letters 42 (2001) 4955–4958
4957
O
HO
OBz
BzO
OH
3b
N OH
3a
NHPI
O
O2
AcO)2CoII
AcO)2CoIII
(AcO)2Co OO
III
(
III
(
(AcO)2Co OOH
O
Ph
OOH
Ph
O
O
NO
O
O
PINO
O
B
3
NHPI
Ph
Ph
OO
O
O
O
O
A
O2
Scheme 2. A plausible reaction path for the aerobic oxidative cleavage of benzylidene acetal 3.
placed in a flask equipped with a balloon filled with O2.
The mixture was stirred at ambient temperature for 15
h. Removal of the solvent under reduced pressure,
followed by silica-gel chromatography (EtOAc:Hexanes
Acknowledgements
This work was supported by a grant from the NIH
GM 54074).
1
:1 to 5:3) provided 1a (140 mg, 54%) as a solid and 1b
(
†
(
70 mg, 27%) as a liquid.
In conclusion, we have reported a facile procedure for
the oxidative cleavage of benzylidene acetals to the
corresponding hydroxy benzoate ester(s). The method-
ology is environmentally benign and experimentally
simple, and utilizes mild reaction conditions compatible
with common carbohydrate protecting groups.
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3
†
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4
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3
2
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(
8
7
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3
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1
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Ref. 11.
8
.