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HASHEMI et al.
622
Deprotection of acetals and trimethylsilyl ethers with HIO3 on silica gel under microwave irradiation (amounts of the
reactants: substrate, 1 mmol; HIO3, 1 or 0.5 mmol; silica gel, 1 g; water, 1 ml; irradiation power 1000 W)
Compound no.
R1
R2
Irradiation time, s
Product
Yield,a %
(CH2)5
Ph
40
20
80
90
92
95
88
98
95
86
88
86
90
Ia
IIIa
IIIb
IIIc
IIId
IIIe
IVa
IVb
IVc
IVd
IVe
IVf
Me
Me
Me
H
Ib
4-O2NC6H4
4-PhC6H4
4-O2NC6H4
PhCH=CH
C7H15
50
Ic
20
60b
Id
Ie
H
10
IIa
IIb
IIc
IId
IIe
IIf
H
10
Ph
H
Ph
110
10
Ph
H
4-MeOC6H4
Ph
10
Et
30
a
Isolated product.
2 ml of water.
b
Thus, iodic acid is an efficient and convenient re-
REFERENCES
agent for oxidative deprotection of acetals and tri-
methylsilyl ethers to the corresponding carbonyl com-
pounds and alcohols. Advantages of the proposed
procedure include its ready availability, low toxicity of
iodic acid, solvent-free conditions, and simple workup.
1. Greene, T.W. and Wuts, P.G.M., Protective Groups in
Organic Synthesis, New York: Wiley, 1991, 2nd ed.
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3. Meskens, F.A.J., Synthesis, 1981, p. 501.
General procedure for deprotection of acetals
and trimethylsilyl ethers. A mixture of 1 mmol of the
corresponding acetal or trimethylsilyl ether and 1 g of
silica gel was ground in a mortar until it became homo-
geneous and was then added to a mixture of 1 (for
acetals) or 0.5 mmol (for trimethylsilyl ethers) of HIO3
and 1 ml of water in an Erlenmeyer flask. The result-
ing mixture was irradiated in a microwave oven at
a power of 1000 W until the initial compound disap-
peared completely (according to the TLC data, see
table). The mixture was then extracted with 25 ml of
methylene chloride, the extract was filtered and evap-
orated, and the residue was purified by column chro-
matography on silica gel. The yields of the isolated
carbonyl compounds and alcohols are given in table.
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Chim. Slov., 2004, vol. 51, p. 333.
The products were identified by comparing their
physical and spectral data with those of authentic
samples. All yields refer to isolated products. The IR
and NMR spectra were recorded on Perkin–Elmer 781
and Bruker DPX-500 spectrometers, respectively. The
progress of reactions was monitored by TLC. Initial
acetals and trimethylsilyl ethers were prepared follow-
ing the procedures described in [13, 14].
12. Hashemi, M.M., Rahimi, A., Karimi-Jaberi, Z., and
Ahmadibeni, Y., Acta Chim. Slov., 2005, vol. 52, p. 86.
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Synop., 1999, p. 562.
14. Firouzabadi, H. and Karimi, B., Synth. Commun., 1993,
vol. 23, p. 1633.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 4 2007