G. P. Romanelli et al. / Tetrahedron Letters 43 (2002) 7589–7591
7591
Table 3. Deprotection of THP-acetals of phenols and
Acknowledgements
alcoholsa
THP-acetal of
% Yield
Supported WDb
Financial support from CONICET (Argentina), and
Universidad Nacional de La Plata is gratefully
acknowledged. G.P.R., G.B. and H.J.T. are members
of CONICET.
Bulk WD
2
3
99
98
94
97
4
5
100
96
98 (97)
95
References
6
95
95
7
8
9
10
11
12
13
98
96
98
99
100
100
98
96 (96)
95
98
97 (95)
99
98
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99
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The THP-acetal (0.5 mmol) was dissolved in THF–1%
MeOH (2 ml), 1% WD catalyst was added and the
mixture was stirred at room temperature for the stated
time (Tables 2 and 3). The suspension was filtered, the
solution was dried over anhydrous Na2SO4, filtered and
concentrated, and the crude product was subjected to
column chromatography (toluene–EtOAc) to yield the
alcohol or phenol.
Conclusions
These procedures provide a useful alternative for the
preparation of THP-acetals, as well as for their cleav-
age to the corresponding phenols or alcohols. Advan-
tages of this methodology are: operational simplicity,
no corrosive and reusable catalyst, mild conditions,
short reaction times and excellent yields. The use of the
solid catalyst allows replacement of the usual soluble
inorganic acids, contributing to a reduction of waste.
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Catal., A 1998, 172, 265.