Preparation of substituted pyridine N-oxide compounds
A process for preparing substituted pyridine N-oxide compounds of the formula 1 in which R1, R2, R3 and R4 are each H, a carboxyl group or a C 1 -C 12 -alkyl radical which may contain atoms from the group of N, O and S, or R1 and R2 and/or R3 and R4 together may each form an optionally substituted C...
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| Main Authors | , , , |
|---|---|
| Format | Patent |
| Language | English |
| Published |
01.04.2004
|
| Online Access | Get full text |
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| Summary: | A process for preparing substituted pyridine N-oxide compounds of the formula
1
in which R1, R2, R3 and R4 are each H, a carboxyl group or a C
1
-C
12
-alkyl radical which may contain atoms from the group of N, O and S, or R1 and R2 and/or R3 and R4 together may each form an optionally substituted C
4
-C
20
-alkylene radical which may contain atoms from the group of N, O and S,
A is benzyl or a (CH
2
)
m
group where
m may be an integer from 1 to 12,
Z
1
and Z
2
are each independently O or S, and Y is H, a C
1
-C
12
-alkyl radical which may optionally contain atoms from the group of N, O and S, a C
6
-C
20
-aryl radical or a C
5
-C
20
-heterocycle, and the radicals may optionally be substituted,
or Z
2
and Y together form an optionally substituted ring or ring system, in which case the ring or ring system may contain atoms from the group of N, O and S, from the corresponding 4-halopyridine N-oxide of the formula
2
in which X is chlorine, bromine or iodine, by reacting the compound of the formula (II), in the presence of a phase transfer catalyst and of a base, with a compound of the formula
HZ
1
-A-Z
2
-Y (III)
in which Z
1
, Z
2
, A and Y are each as defined above, at a temperature up to the reflux temperature, to give the corresponding substituted pyridine N-oxide compound of the formula (I), and also a process for preparing the compound of the formula (II). |
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