448
AKBALINA et al.
Oxidation of cyclic acetals DH with complexes of 15-
crown-5 with potassium chlorodiperoxochromate (IIa) and
chlorochromate (IIb) (CH3CN, 60 C, [DH]/[III] 1 : 0.01)
The initial cyclic acetals Ia Ie were prepared as
described in [8]. Complexes IIa and IIb were prepared
according to [5, 6]. Nitroxyl radical III was purified
by recrystallization from hexane.
[DH]/
oxidant
Reaction
product
Yield,
%
DH
Oxidant
Oxidation was performed in a 30-ml temperature-
controlled glass vessel, stirred with a magnetic stirrer.
To a solution of 1 mmol of acetal in 10 ml of aceto-
nitrile we added 3 g of moist alumina and heated to
60 C. Then 3 6 mmol of IIa or IIb was added in
portions over a period of 1 h, and stirring was contin-
ued for an additional 6 7 h. The resulting mixture
was cooled to room temperature and filtered. The
solvent was removed on a rotary evaporator, and the
products were analyzed.
Ia
IIa
IIa + III
IIb
IIb + III
IIa
IIa + III
IIb
IIb + III
IIa
IIa + III
IIb
IIb + III
IIa
IIa + III
IIb
1: 3
1: 3
1: 6
1: 6
1: 3
1: 3
1: 3
1: 3
1: 3
1: 3
1: 6
1: 6
1: 3
1: 3
1: 6
1: 6
1: 3
1: 6
IV
IV
10
100
IV
V
V
100
70
100
Ib
Ic
Id
Ie
V
V
100
100
Oxidation in the presence of 2,2,5,5-tetramethyl-4-
5
phenyl-3-oxo-3 -imidazolin-1-yloxyl was performed
similarly. A solution of 1 mmol of acetal, 1 mmol of
KBr, and 0.01 mmol of III in 10 ml of acetonitrile
was heated to 60 C, 3 6 mmol of IIa or IIb was
added in portions over a period of 1 h, and stirring
was continued for an additional 6 7 h. The resulting
mixture was cooled to room temperature and filtered;
the solvent was evaporated.
V
V
V
100
50
100
IIb + III
IIa
IIb
V
VI
VI
100
100
95
REFERENCES
1. Rakhmankoulov, D.L., Zlotsky, S.S., Kouramshin, E.M.,
and Kulak, L.G., Int. J. Polym. Mater., 1990, vol. 13,
pp. 117 126.
cal III, which is known [7] to promote liquid-phase
oxidation, compound Ia is converted almost quantita-
tively into IV under the action of both complex IIa
and complex IIb. Catalytic oxidation of Ib Ie gives
2. Deslongchamps, P., Frehel, D., Malaval, A., and
Moreau, C., Can. J. Chem., 1974, vol. 52, p. 3651.
aldehyde
V in 90% yield (see table).
3. Zlotsky, S.S., Kulak, L.G., Nazarov, M.N., and Rakh-
mankulov, D.L., J. Prakt. Chem., 1992, vol. 334,
pp. 441 443.
The higher activity of IIa is probably due to the
presence of weak O O bonds [6]. In reaction with IIa,
six-membered acetal Id is less active than its five-
membered analog Ib.
4. Rakhmankulov, D.L., Zlotskii, S.S., Shereshovets, V.V.,
Abushakhmina, G.M., and Kabal’nova, N.N., Dokl.
Ross. Akad. Nauk, 1998, vol. 361, no. 3, pp. 355 356.
To conclude, agents IIa and IIb can be successfully
used for removing the acetal protective group from
aromatic aldehydes and from ketones.
5. Kotlyar, S.A., Fedorova, G.V., Gorodnyuk, V.P., and
Luk’yanenko, N.G., Zh. Obshch. Khim., 1989, vol. 59,
no. 12, pp. 2799 2801.
6. Fedorova, G.V., Novozhilova, N.V., Fedorova, L.S.,
Tudorovskaya, G.L., Kotlyar, S.A., and Luk’yanen-
ko, N.G., Zh. Neorg. Khim., 1990, vol. 35, no. 1,
pp. 92 96.
EXPERIMENTAL
The oxidation products were identified and ana-
lyzed with a Finnigan gas chromatograph mass spec-
trometer, by GLC (Chrom-5, 1200 3-mm column,
7. De Nooy, A.E.J., Besemer, A.C., and Van Bekkum, H.,
1
SE-30 stationary phase), and by H and 13C NMR
Synthesis, 1996, p. 1153.
spectroscopy (Bruker AM-300 spectrometer, 300 and
75 MHz, respectively; CDCl3, reference TMS). As
references we used specially prepared monoester IV
and reagent-grade carbonyl compounds V and VI.
8. Rakhmankulov, D.L., Karakhanov, R.A., Zlotskii, S.S.,
Kantor, E.A., Imashev, U.B., and Syrkin, A.M.,
Chemistry and Technology of 1,3-Dioxacyclanes, Itogi
Nauki Tekh., Ser.: Tekhnol. Org. Veshch., 1979, vol. 5.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 3 2002