J. CHEM. RESEARCH (S), 1998 121
Table 2 Oxidation of alcohols to carbonyl compounds using iodobenzene diacetate
PhI(OAc)2
Al2O3^PhI(OAc)2
Mp (T/ 8C) or bp [(T/ 8C)/Torr]
Entry
R1
R2
R3
Time (t/min) Yield (%)a Time (t/min) Yield (%)a
Observed
Reported
1
2
3
4
5
6
7
8
9
H
H
H
p-Me
p-OMe
H
H
2.0
2.0
1.5
1.5
2.0
2.0
ö
89
88
91
81
83
1.0
1.0
2.0
1.5
2.0
2.0
3.0
3.0
0.5
94
92
95
86
89
90
96
69
43
51^54/6
80^82/4
92^95/3
72^73
64^65/2
93^95
178.6/760c
106/10c
83/2c
H
H
H
H
Et
Bz
CH2OH
72^74d
H
H
H
H
91.6/10c
95^96c
H
90
b
p-MeOC6H4CO p-OMe
Hydroquinone
131^132
116
132^134d
115^117d
60^70c,e
b
b
ö
Catechol
ö
61^66e
aUnoptimized yields refer to pure isolated products. bMixture of products was formed. Handbook of Chemistry and Physics, ed. R. C. West,
c
CRC Press, Boca Raton, 67th edn., 1986. dAldrich Catalog Handbook of Fine Chemicals, USA, 1996^1997. eDecomposed.
procedure was selective and avoided any over-oxidation to
carboxylic acids. The protocol also eliminated the excessive
use of corrosive solvents such as acetic acid, tri¯uoroacetic
acid and high-boiling DMSO normally employed in reac-
tions with relatively expensive hypervalent iodine reagents
such as IBX and BTI.3b,7,9a
References
1 (a) P. J. Stang and V. V. Zhdankin, Chem. Rev., 1996, 96, 1123;
(b) O. Prakash, Aldrichimica Acta, 1995, 28, 63; (c) A. Varvoglis,
The Organic Chemistry of Polycoordinated Iodine, VCH, New
York, 1992.
2 (a) J. B. Arterburn and S. L. Nelson, J. Org. Chem., 1996, 61,
2260; (b) R. Kakarla, R. G. Dulina, N. T. Hatzenbuhler, Y. W.
Hui and M. J. So®a, J. Org. Chem., 1996, 61, 8347; (c) R. Aldea
and H. Alper, J. Org. Chem., 1995, 60, 8365.
3 (a) W. Ando, R. Tajima and T. Takata, Tetrahedron Lett., 1982,
23, 1685; (b) D. H. R. Barton, G. R. A. Godfrey, J. W.
Morzycki, W. B. Motherwell and A. Stobie, Tetrahedron Lett.,
1982, 23, 957.
That the eect may not be purely thermal15 is borne out
by the fact that at ca. 85C in an oil-bath a relatively longer
time (25±30 min) is required for complete oxidation of ben-
zyl phenyl sul®de. Similarly, the oxidation of benzyl alcohol
to benzaldehyde could be completed in 2 h in an oil-bath at
a comparable temperature of 80C.
4 (a) H. H. Szmant and G. Suld, J. Am. Chem. Soc., 1956, 78,
3400; (b) J. P. A. Castrillon and H. H. Szmant, J. Org. Chem.,
1967, 32, 976.
5 D. Barbas, S. Spyroudis and A. Varvoglis, J. Chem. Res. (S),
1985, (S) 196; (M) 2201.
In conclusion, the new protocols with IBD on alumina
are simple, rapid and high-yielding and avoid the drastic
conditions normally employed. In addition, in a truly
environmentally benign manner, the alumina support can be
recovered and reused.
6 I. E. Marko, P. R. Giles, M. Tsukazaki, S. M. Brown and C. J.
Urch, Science, 1996, 274, 2044.
Experimental
7 (a) S. D. Munari, M. Frigerio and M. Santagostino, J. Org.
Chem., 1996, 61, 9275; (b) M. Frigerio and M. Santagostino,
Tetrahedron Lett., 1994, 35, 8019.
8 R. Barret and M. Daudon, Tetrahedron Lett., 1990, 31, 4871.
9 (a) D. B. Dess and J. C. Martin, J. Org. Chem., 1983, 48, 4155;
(b) R. J. Linderman and D. M. Graves, Tetrahedron Lett., 1987,
28, 4259.
10 (a) A. McKillop, L. McLaren and R. J. K. Taylor, J. Chem.
Soc., Perkin Trans. 1, 1994, 2047; (b) P. Wipf, Y. Kim and P. C.
Fritch, J. Org. Chem., 1993, 58, 7195.
11 (a) J. H. Clark, Catalysis of Organic Reactions by Supported
Inorganic Reagents, VCH, New York, 1994; (b) K. Smith,
Solid Supports and Catalysts in Organic Synthesis, Ellis
Horwood, Chichester, 1992; (c) P. Laszlo, Preparative Chemistry
Using Supported Reagents, Academic Press, San Diego,
1987; (d) A. McKillop and D. W. Young, Synthesis, 1979, 401,
481.
12 (a) R. S. Varma and R. Dahiya, Tetrahedron Lett., 1997, 38,
2043; (b) R. S. Varma, R. Dahiya and S. Kumar, Tetrahedron
Lett., 1997, 38, 2039; (c) R. S. Varma and R. K. Saini,
Tetrahedron Lett., 1997, 38, 2623; (d) R. S. Varma and R. K.
Saini, Tetrahedron Lett., 1997, 38, 4337; (e) R. S. Varma,
R. Dahiya and S. Kumar, Tetrahedron Lett., 1997, 38, 5131;
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38, 5427; (g) R. S. Varma and R. K. Saini, Synlett, 1997, 857;
(h) R. S. Varma, R. Dahiya and R. K. Saini, Tetrahedron Lett.,
1997, 38, 8819 and references cited therein.
A Sears Kenmore microwave (MW) oven operating at 2450 MHz
(power 900 W) was used for all the experiments. Products were
identi®ed by comparison of their mps and IR and NMR spectra
with those of authentic samples
General Procedure for Oxidation of Sul®des.ÐNeutral alumina
(1.5 g) was thorougly mixed with IBD (532 mg, 1.65 mmol) and ben-
zyl phenyl sul®de (300 mg, 1.5 mmol) using a pestle and mortar. The
adsorbed material was placed in an alumina bath inside the micro-
wave oven and irradiated at 50% power for two successive intervals
of 45 s each (with time interval of 3±4 min; bath temperature rose to
80±85C). The progress of the reaction was monitored by TLC (hex-
ane±ethyl acetate, 7:3 v/v). When the reaction was complete the
whole material was directly charged onto a silica gel column which
provided iodobenzene on elution with hexane (100 ml). The frac-
tions eluted by chloroform±hexane (1:1 v/v) provided sulfone
(<7% by NMR of crude product) and ®nally elution by chloro-
form aorded pure benzyl phenyl sulfoxide in 86% yield, mp 123 8C.
General Procedure for Oxidation of Alcohols.ÐBenzyl alcohol
(108 mg, 1 mmol), IBD (355 mg, 1.1 mmol) and neutral alumina (1 g)
were mixed using a pestle and mortar. The reaction mixture was
placed in an alumina bath inside a microwave oven and irradiated
for 1 min (bath temperature 80C). On completion of the reaction
(TLC, hexane±ethyl acetate, 9:1 v/v), the crude product was directly
charged onto a silica gel column. Elution with hexane (100 ml) pro-
vided iodobenzene. Subsequent use of hexane±ethyl acetate (9:1 v/v)
as eluent aorded the pure carbonyl compounds in 94% yield.
13 (a) A. Oussaid, L. N. Thach and A. Loupy, Tetrahedron Lett.,
1997, 38, 2451; (b) D. Villemin and A. Benalloum, Synth.
Commun., 1991, 21, 1, 63.
14 (a) S. Caddick, Tetrahedron, 1995, 51, 10403; (b) C. R. Strauss
and R. W. Trainor, Aust. J. Chem., 1995, 48, 1665.
15 K. D. Raner, C. R. Strauss, F. Vyskoc and L. Mokbel, J. Org.
Chem., 1993, 58, 950.
We are grateful to the Texas Advanced Research
Program (ARP) in chemistry (Grant no. 003606-023) and
Oce of Naval Research/SERDP (Grant no. N00014-96-1-
1067) for ®nancial support.
Received, 28th October 1997; Accepted, 12th November 1997
Paper E/7/07090J