Chemistry Reference
In-Depth Information
O
⎯
CH
2
CH
3
CH
2
Cl
⎯
O
⎯
CH
2
OC
O
S
CH
3
Fig.
8
.2
8
Oxidations with sulfoxides.
S
S
S
N
N
N
H
+
Br
3
-
H
3
C
H
3
C
H
3
C
Fig.
8
.29
Oxidations with
hydrotribromide on polythiazoles.
CH
2
NMe
3
+
S
2
O
8
--
Ar
Ar
C
NOH
C O
R
R
R
R
C O
C
NOH
H
H
Ar
Ar
C O
CH
OH
R
R
Ar
CH
O
Fig.
8
.30
Oxidations with
peroxodisulfate-exchanged resins.
Ar
CH
2
OH
odourless sulfoxides and methyl sulfides through
polymer modification.
The copolymerisation of 4-methyl-5-vinylthiazole
affords a thiazolic support that is treated with hydro-
gen bromide and bromine to give the hydrotribro-
mide [97], which can oxidise primary and secondary
alcohols in basic aqueous solution (Fig. 8.29).
A peroxodisulfate-exchanged resin is a stable, mild
and clean oxidation reagent of benzylic alcohols and
oximes to carbonyl compounds [98,99]; anhydrous
and aprotic solvents are required (Fig. 8.30a). On
the other hand, reduction reactions sometimes are
used to obtain carbonyl compounds: dithionite-
exchanged resins are excellent reagents for the selec-
tive reduction of C=C double bonds of a-b-unsatu-
rated aldehydes and ketones [100]; some terpenic
ketones were chosen as examples. In the steroid
series [101], oxidation of alkenes with ozone fol-
lowed by reduction of the ozonide with supported
triphenylphosphine gives aldehydes and ketones. A
supported perruthenate is used in the conversion of
primary and secondary alcohols to pure aldehydes
and ketones [102] (Fig. 8.31).
A way of making ketones from aldehydes is
described through the formation of dithiolanes with
a polymer containing pendant dithiols groups: alky-
lation of the lithium salt followed by hydrolysis
affords the free ketones and the starting polymer
