Calogero G. Piscopo et al.
COMMUNICATIONS
Table 2. BV oxidation of ketones.[a]
Experimental Section
Entry
Substrate
Product
Conv. [%] Sel. [%][b]
Procedure for the Catalytic BV Oxidation of Cyclic
Ketones
a
83
86
In a typical procedure cyclohexanone 1a (0.95 mmol) and
30% aqueous H2O2 (1.0 mmol) were dissolved in HFIP
(2.0 mL) and were heated to 508C under stirring in the pres-
ence of the selected catalyst for 90 min. The reaction was
followed by GC analysis and the e-caprolactone product
(3a) was identified by comparison with a reference sample,
accompanied by variable amounts of intermediate 2a and 6-
hydroxyhexanoic acid.
b
c
100
81
100
92
Acknowledgements
d
e
64
75
100
77
This work was supported by the Ministero dell’Universitꢀ e
della Ricerca (MIUR), Italy, and the University of Parma
(National Project “Attivazione ossidativa catalitica e fotocata-
litica per la sintesi organica”). The Centro Interdipartimen-
tale Misure (CIM) is acknowledged for the use of NMR in-
struments. The authors are indebted to Prof. A. Berkessel for
the valuable advice regarding preparation and handling of
spirobisperoxide intermediates.
f
83
97
65
References
g
100
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[a]
Reaction conditions: ketone: 0.95 mmol, 30% H2O2:
1 mmol, HFIP: 2 mL, SiO2-(CH2)3-SO3H: 0.4 mol%,
508C, 1.5 h.
Formation of corresponding lactone was determined by
GC analysis by comparison with reference samples.
[b]
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[4] Highly concentrated H2O2 has been removed from the
commercial market because of the possible dangers in-
volved in transport and handling.
termediate spirobisperoxides and the w-hydroxyalka-
noic acids.
The reaction shows also a good level of efficient
oxygen utilization as a 0.95/1.00 ketone/H2O2 molar
ratio was used in all experiments.
In conclusion we have demonstrated that the BV
oxidation of cyclic ketones can be efficiently per-
formed in 1,1,1,3,3,3-hexafluoro-2-propanol with 30%
aqueous H2O2 in the presence of propylsulfonic acid
supported on silica used as a heterogeneous and reus-
able catalyst. The reaction involves the fast formation
of a spirobisperoxide intermediate that rearranges to
the corresponding lactone product. The catalytic oxi-
dation reaction can be applied to different cyclic ke-
tones showing good conversion and high selectivity
combined with a good level of efficient oxygen uti-
lization.
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Adv. Synth. Catal. 2010, 352, 1625 – 1629