Process for preparing pyridazin-3-on derivatives

Details Process for preparing pyridazin-3-on derivatives Process for preparing pyridazin-3-on derivatives

2001-06-28

2002-12-31

Bernhardt, Emily (Department: 1624)

Organic compounds -- part of the class 532-570 series

Organic compounds

Four or more ring nitrogens in the bicyclo ring system

C562S440000

Reexamination Certificate

active

06500951

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for preparing pyridazin-3-on derivatives.
BACKGROUND ART
WO97/7104 discloses that pyridazin-3-on derivatives have good herbicidal activities, and WO98/17632 discloses that carboxylic acids derivatives and their salts are useful intermediates for the preparation of pyridazin-3-on derivatives, and a process for preparing pyridazin-3-on derivatives from such intermediates. For example, WO98/17632 discloses a process of reacting a lower carboxylic acid and a base with such an intermediate.
However, the disclosed process does not always produce a desired product at an industrially satisfactory yield and purity.
SUMMARY OF THE INVENTION
One object of the. present invention is to provide a process for preparing pyridazin-3-on derivatives from carboxylic acid derivatives or their salts advantageously in an industrial scale.
This and other objects are accomplished by a method for preparing a pyridazin-3-on derivative of the formula (1):
wherein R
2
is a hydrogen atom or a C
1
-C
3
alkyl group, R
3
is a hydrogen atom or a C
1
-C
3
alkyl group, and Q is a phenyl group which may optionally be substituted, comprising the step of ring closing a carboxylic acid derivative of the formula (2):
wherein R
2
, R
3
and Q are the same as defined above, or its salt in the presence of a nitrogen-containing aromatic compound and a boron compound.
DETAILED DESCRIPTION OF THE INVENTION
The carboxylic acid of the formula (2) or its salt, which is a raw material used; in the process of the present invention, will be explained.
In the carboxylic acid of the formula (2) or its salt, examples of a substituent which may optionally present on the phenyl group Q include halogen atoms, and a group of the formula: —ZR
1
in which Z is an oxygen atom or a sulfur atom, and R
1
is a hydrogen atom, a C
1
-C
6
alkyl group, a C
1
-C
6
haloalkyl group, a C
3
-C
8
cycloalkyl group, a benzyl group, a C
3
-C
6
alkenyl group, a C
3
-C
6
haloalkenyl group, a C
3
-C
6
alkynyl group, a C
3
-C
6
haloalkynyl group, a cyano-C
1
-C
6
alkyl group, a C
2
-C
8
(alkoxyalkyl) group, a C
2
-C, (alkoxythioalkyl) group, a carboxy-C
1
-C
6
alkyl group, (C
1
-C
8
alkoxy) carbonyl-C
1
-C
6
alkyl group, [(C
1
-C
4
alkoxy)-C
1
-C
4
alkoxy]carbonyl-C
1
-C
6
alkyl group, a (C
3
-C
8
cycloalkoxy)carbonyl-C
1
-C
6
alkyl group or a [(C
1
-C
6
alkoxy)carbonyl-C
1
-C
6
alkyl]oxycarbonyl-C
1
-C
6
alkyl group, wherein the positions and number of the substituents are arbitrary.
Preferably, the group Q is an optionally substituted phenyl group of the formula (3):
wherein X is a hydrogen atom or a halogen atom, Y is a halogen atom, and W is a hydrogen atom or a group of the formula: —ZR
1
in which Z and R
1
are the same as defined above.
Examples of the halogen atom for X and Y include a fluorine atom, a chlorine atom, a bromine atom, etc.
Examples of the C
1
-C
6
alkyl group for R
1
include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert.-butyl group, an amyl group, an isoamyl group, a tert.-amyl group, etc.
Examples of the C
1
-C
6
haloalkyl group include a 2-chloroethyl group, a 2-bromoethyl group, a 2,2,2-trifluoroethyl group, etc.
Examples of the C
3
-C
8
cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc.
Examples of the C
3
-C
6
alkenyl group include an allyl group, a 1-methyl-2-propenyl group, a 3-butenyl group, a 2-butenyl group, a 3-methyl-2-butenyl group, a 2-methyl-3-butenyl group, etc.
Examples of the C
3
-C
6
haloalkenyl group include a 2-chloro-2-propenyl group, a 3,3-dichloro-2-propenyl group, etc.
Examples of the C
3
-C
6
alkynyl group include a propargyl group, a 1-methyl-2-propynyl group, a 2-butynyl group, a 1,1-dimethyl-2-propynyl group, etc.
Examples of the C
3
-C
6
haloalkynyl group include 3-bromopropargyl group, etc.
Examples of the cyano-C
1
-C
6
alkyl group include a cyanomethyl group, etc.
Examples of the C
2
-C
8
alkoxyalkyl group include a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, etc.
Examples of the C
2
-C
8
alkylthioalkyl group include a methylthiomethyl group, a methylthioethyl group, etc.
Examples of the carboxy-C
1
-C
6
alkyl group include a carboxymethyl group, a 1-carboxyethyl group, a 2-carboxyethyl group, etc.
Examples of the (C
1
-C
8
alkoxy)carbonyl-C
1
-C
6
alkyl group include a methoxycarbonylmethyl group, an ethoxycarbonylmethyl group, a propoxycarbonylmethyl group, an isopropoxycarbonylmethyl group, a butoxycarbony.methyl group, an isobutoxycarbonylmethyl group, a tert.-butoxycarbonylmethyl group, an amyloxycarbonylmethyl group, an isoamyloxycarbonylmethyl group, a tert.-amyloxy-carbonylmethyl group, a 1-methoxycarbonylethyl group, a 1-ethoxycarbonylethyl group, a 1-propoxycarbonylethyl group, a 1-isopropoxycarbonylethyl group, a 1-butoxycarbonylethyl group, a 1-isobutoxycarbonylethyl group, a 1-tert.-butoxycarbonylethyl group, a 1-amyloxycarbonylethyl group, a 1-isoamyloxycarbony-ethyl group, a 1-tert.-amyloxycarbonylethyl group, etc.
Examples of the [(C
1
-C
4
alkoxy)-C
1
-C
4
alkoxy]carbonyl-C
1
-C
6
alkyl group include a methoxymethoxycarbonylmethyl group, a methoxyethoxycarbonylmethyl group, a 1-methoxyethoxycarbonylethyl group, etc.
Examples of the (C
3
-C
8
cycloalkoxy)carbonyl-C
1
-C
6
alkyl group include a cyclobutyloxycarbonylmethyl group, a cyclopentyloxycarbonylmethyl group, a cyclohexyloxycarbonyl-methyl group, a 1-cyclobutyloxycarbonylethyl group, a 1-cyclopentyloxycarbonylethyl group, a 1-cyclohexyloxy-carbonylethyl group, etc.
Examples of the [(C
1
-C
6
alkoxy)carbonyl-C
1
-C
6
alkyl]oxy-carbonyl-C
1
-C
6
alkyl group include a (methoxycarbonyl)methoxycarbonylmethyl group, an (ethoxycarbonyl)methoxycarbonylmethyl group, etc.
Examples of the C
1
-C
3
alkyl group for R
2
and R
3
include a methyl group, an ethyl group, a propyl group, etc.
The salts of the carboxylic acid derivative of the formula (2) may be the salts of the above exemplified carboxylic acids and organic bases. Examples of such organic bases include nitrogen-containing aromatic compounds (e.g. pyridine, 4-dimethylaminopyridine, 2-picoline, 3-picoline, 4-picoline, 5-ethyl-2-methylpyridine, etc.), dialkylaniline derivatives (e.g. N,N-dimethylaniline, N,N-diethylaniline, etc.), tertiary amines (e.g. triethylamine, diisopropylethylamine, tri-n-propylamine, tri-n-butylamine, etc.), and the like.
Hereinafter, the specific carboxylic acid derivatives of the formula (2) as the raw materials are exemplified:
Carboxylic acid derivatives of the formula (2)
Compound
Carboxylic acid
No.
derivative
2-1

2-2

2-3

2-4

2-5

2-6

2-7

2-8

2-9

2-10

2-11

2-12

2-13

2-14

2-15

2-16

2-17

2-18
However, the raw materials that can be used in the present invention are not limited thereto.
Examples of the a boron compound to be used in the process of the present invention are as follows:
wherein R
4
, R
1
and R
6
are the same and different and represent a hydroxyl group, a C
1
-C
6
alkyl group, a C
1
-C
6
alkoxy group, a phenyl group which may optionally be substituted with at least one substituent (e.g. a halogen atom, a C
1
-C
4
alkyl group, a C
1
-C
3
haloalkyl group, a C
1
-C
3
alkoxy group, a nitro group, an amino group, a carboxyl group, a C
1
-C
3
amide group, a formyl group, a C
1
-C
3
alkylthio group, a dihydroxylboryl group, or a phenyl group which may optionally be substituted with a dihydroxyboryl group), a naphthyl group which may optionally be substituted with at least one substituent (e.g. a halogen atom, a C
1
-C
4
alkyl group or a C
1
-C
3
haloalkyl group), a thienyl group which may optionally be substituted with at least one substituent (e.g. a halogen atom or a C
1
-C
4
alkyl group), a furyl group which may optionally be substituted with at least one substituent (e.g. a halogen atom or a C
1
-C
4
alkyl group), a benzofuranyl group the benzene group of which may optionally be s

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