Preparation of 2-haloacyl-3-aminoacrylic acid derivatives

Details Preparation of 2-haloacyl-3-aminoacrylic acid derivatives Preparation of 2-haloacyl-3-aminoacrylic acid derivatives

2002-12-13

2004-03-16

Rotman, Alan L. (Department: 1626)

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

Organic compounds

Carboxylic acid esters

Reexamination Certificate

active

06706911

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved process for preparing 2-haloacyl-3-aminoacrylic acid derivatives and pyrazole-4-carboxylic acid derivatives obtainable from them.
2. Brief Description of the Prior Art
2-Haloacyl-3-aminoacrylic acid derivatives, for example 2-trifluoroacetyl-3-aminoacrylic esters, are valuable intermediates in preparing substituted pyrazoles which find use as fungicides, pesticides and herbicides.
EP-A 1 000 926 discloses a process for preparing 2-trihaloacetyl-3-amino-acrylic esters by substituting trihaloacetyl acetates using orthoformic acid derivatives. However, the yields of the reaction obtained are only 61.8% and unacceptable for industrial use.
A further method for preparing such compounds is described by Bartnik et al. (Tetrahedron Lett. (1996), 37(48), 8751-8754). &bgr;-Chloroacroleins are reacted with secondary amines in diethyl ether at room temperature (RT) in yields of from 44 to 84%.
GHowever, a disadvantage of this process is that the chloroacroleins used as starting compounds are difficult to prepare and accordingly too expensive for industrial use.
There is accordingly a need to develop an improved process for preparing 2-haloacyl-3-aminoacrylic acid derivatives starting from easily obtainable reactants.
SUMMARY OF THE INVENTION
A process for preparing 2-haloacyl-3-aminoacrylic esters has now been found which is characterized in that
a) N-substituted 3-aminoacrylic esters are reacted with haloalkylcarboxylic anhydrides in the presence of base and optionally in the presence of solvent.
If desired, the 2-haloacyl-3-aminoacrylic esters obtained in this manner may be
b) converted by reaction with hydrazines to 3-haloalkyl-4-pyrazolecarboxylic esters which
c) may be reacted further by acid or alkali hydrolysis to give 3-haloalkyl-4-pyrazolecarboxylic acids.
DETAILED DESCRIPTION OF THE INVENTION
For the purposes of the invention, exemplary and preferred 3-aminoacrylic esters used are of the general formula (I)
where
R
1
is C
1
-C
12
-alkyl, C
6
-C
18
-aryl or C
7
-C
19
-arylalkyl and
R
2
and R
3
are each independently C
1
-C
12
-alkyl or C
7
-C
19
-arylalkyl.
Preference is given to R
1
being C
1
-C
4
-alkyl, more preferably methyl or ethyl, and to R
2
and R
3
each independently being C
1
-C
4
-alkyl, more preferably methyl or ethyl.
Particularly preferred 3-aminoacrylic esters of the general formula (I) are methyl 3-(N,N-dimethylamino)acrylate and methyl 3-(N,N-diethylamino)-acrylate, and methyl 3-(N,N-dimethylamino)acrylate is even more preferred.
The 3-aminoacrylic esters to be used can be prepared according to the literature or in a similar manner (EP-A 608 725).
For the purposes of the invention, alkyl is a straight-chain, cyclic, branched or unbranched alkyl radical which may optionally be further substituted by C
1
-C
6
-alkoxy radicals, for example methoxy or ethoxy. The same applies to the alkylene moiety of an arylalkyl radical.
For example, C
1
-C
4
-alkyl is methyl, ethyl, ethoxyethyl, n-propyl, isopropyl, n-butyl ortert-butyl, C
1
-C
8
-alkyl is also n-pentyl, cyclohexyl, n-hexyl, n-octyl or isooctyl, and C
1
-C
12
-alkyl is also, for example, n-decyl or n-dodecyl.
For the purposes of the invention, alkoxy is a straight-chain, cyclic, branched or unbranched alkoxy radical which may optionally be further substituted by C
1
-C
6
-alkoxy radicals, for example methoxy or ethoxy.
For example, C
1
-C
6
-alkoxy is methoxy, ethoxy, 2-ethoxyethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy or cyclohexyloxy.
For the purposes of the invention, exemplary and preferred aryl radicals are carbocyclic aromatic radicals having from 6 to 18 skeleton carbon atoms (C
6
-C
18
-aryl), for example phenyl or naphthyl.
The carbocyclic aromatic radicals may be further substituted by up to five identical or different substituents per cycle, for example those selected from the group of chlorine, fluorine, nitro, cyano, C
1
-C
4
-alkyl, for example methyl or ethyl, C
1
-C
4
-acyl, for example acetyl, C
1
-C
4
-alkoxy, for example methoxy or ethoxy, C
6
-C
12
-aryl, for example phenyl, C
7
-C
13
-arylalkyl, for example benzyl, or C
6
-C
12
-aryloxy, for example phenoxy.
Examples of C
6
-C
10
-aryl radicals include phenyl, o-, m- and p-tolyl, o-, m- and p-anisyl and naphthyl, and examples of C
6
-C
18
-aryl also include, for example, anthracenyl.
The same applies to the aryl moiety of an arylalkyl radical. C
7
-C
13
-Arylalkyl is, for example, benzyl or the isomeric 1-methylbenzyls, and C
7
-C
13
-arylalkyl is also, for example, fluorenyl.
In step a) of the process according to the invention, haloalkylcarboxylic anhydrides are used.
For the purposes of the invention, haloalkylcarboxylic anhydrides are not only symmetric anhydrides or mixed anhydrides of different haloalkylcarboxylic acids, but also mixed anhydrides of haloalkylcarboxylic acids with organic acids, for example sulphonic acids, or inorganic acids, for example hydrohalic acids. The latter are frequently also termed haloalkylcarbonyl halides.
Exemplary and preferred haloalkylcarboxylic anhydrides are of the general formula (IIa)
where
X is chlorine, bromine or iodine, preferably chlorine and
Hal are each independently chlorine or fluorine, preferably fluorine and
R
4
is chlorine, fluorine or C
1
-C
12
-haloalkyl, C
1
-C
12
-alkyl, C
6
-C
18
-aryl or C
6
-C
19
-arylalkyl, preferably chlorine, fluorine, trifluoromethyl, pentafluoroethyl, nonafluorobutyl or C
1
-C
4
-alkyl, more preferably fluorine.
Further exemplary and preferred haloalkylcarboxylic anhydrides are of the general formula (IIb)
where
Hal and the R
4
radicals are each as defined and subject to the same preferences as stated under the general formula (IIa).
Preference is given to the R
4
radicals in the general formula (IIb) being identical.
For the purposes of the invention, exemplary and preferred haloalkyl radicals are branched or unbranched, open-chain or cyclic alkyl radicals which may be singly, multiply or fully substituted by halogen atoms selected from the group of chlorine and fluorine.
Exemplary and preferred C
1
-C
12
-haloalkyl radicals are trifluoromethyl, trichloromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl and nonafluorobutyl.
Exemplary and preferred haloalkylcarboxylic anhydrides are trifluoroacetic anhydride, trifluoroacetyl chloride, trichloroacetic anhydride and trichloroacetyl chloride.
The molar ratio of haloalkylcarboxylic anhydrides to 3-aminoacrylic esters used may be, for example, from 0.3 to 1.5, preferably from 0.8 to 1.1 and more preferably from 0.95 to 1.05.
Exemplary and preferred bases are tertiary nitrogen bases, carbonates and hydrides.
Particular preference is given to using tertiary nitrogen bases, for example tertiary amines, substituted or unsubstituted pyridines and substituted or unsubstituted quinolines.
Very particular preference is given to using pyridine, 2-, 3-, 4-picoline, 2,6-lutidine and quinoline bases, and bases of the general formula (IIIa)
NR
5
R
6
R
7
  (IIIa)
where R
5
, R
6
and R
7
are each independently C
1
-C
16
-alkyl, C
7
-C
19
-arylalkyl or C
6
-C
18
-aryl, or two radicals together may also form part of a 5- to 8-membered N-heterocyclic radical, or all three radicals together may form part of an N-heterobicyclic or N-heterotricyclic radical having from 5 to 9 ring atoms per cycle which may also contain other heteroatoms, for example oxygen.
Preference is likewise given to using bases of the general formula (IIIb)
R
8
R
9
—N—A—NR
10
R
11
  (IIIb)
where
A is C
2
-C
8
-alkylene, preferably, for example, 1,2-ethylene, 1,3-propylene, 2,3-butylene, 1,2-cyclohexylene or C
6
-C
18
-arylenes, for example 1,2-phenylene and
the R
8
, R
9
, R
10
and R
11
radicals are each independently
C
1
-C
18
-alkyl, C
7
-C
19
-arylalkyl or C
6
-C
18
-aryl or two radicals together may also form part of a 5- to 8-membered N-heterocyclic ring or may form a bridge between the two nitrogen atoms or all four radicals together may form part of a bis-N-heterobicyclic or bis-N-heterotricyclic radical having from

Affiliated with

Also associated with

Rating

Preparation of 2-haloacyl-3-aminoacrylic acid derivatives does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Preparation of 2-haloacyl-3-aminoacrylic acid derivatives, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of 2-haloacyl-3-aminoacrylic acid derivatives will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3251014