# US 8,273,904 B2 · Method for preparing 4-aminobut-2-enolides

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- Number: US 8,273,904 B2
- Document ID: US8273904B2
- Status: Granted
- Kind: B2
- Application number: 12/677,769
- Filed: 2008-09-05
- Published: 2010-07-29
- Granted: 2012-09-25
- Earliest claimed: 2007-09-18
- Assignees: Bayer CropScience AG
- Inventors: Norbert Lui; Jens-Dietmar Heinrich
- Web page: https://patentgrep.com/patent/US8273904B2

## CPC

- C07D 307/68: Carbon atoms having three bonds to hetero atoms with at the most one bond to halogen
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

Process for preparing 2,2-difluoroethylamine derivatives, wherein compounds of the general formula (IV) are reduced to the corresponding 2,2-difluoroethylamine derivatives of the general formula (III), where the A radical is as defined in the description:

## Claims

### Claim 1

A process for preparing a 4-aminobut-2-enolide compound of formula (I)
comprising reacting a compound of formula (II)
with an amine of formula (III)
where
R1 is hydrogen, alkyl, fluoroalkyl, alkenyl, fluoroalkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, fluorocycloalkyl, alkoxy, alkoxyalkyl, fluorocycloalkylalkyl or arylalkyl;
R2 is alkyl, aryl or arylalkyl;
Z is hydrogen, an alkali metal or an alkaline earth metal;
A is pyrid-2-yl or pyrid-4-yl, or is pyrid-3-yl which is optionally 6-substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl or trifluoromethoxy, or is
in which
X is halogen, alkyl or fluoroalkyl, and
Y is halogen, alkyl, fluoroalkyl, or fluoroalkoxy.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the compound of the formula (II) is obtained by reacting a compound of formula (V)
wherein
R3 alkyl, with the exception of ethyl, or cycloalkyl; and
R4 is alkyl, cycloalkyl, fluoroalkyl, aryl or arylalkyl with a base.

### Claim 3 (depends on 2)

The process according to claim 2, wherein the compound of formula (II) is obtained by the following scheme proceeding from a compound of formula (V) by reaction with sodium alkoxide:
where
R2 is alkyl, aryl or arylalkyl;
R3 is alkyl, with the exception of ethyl, or cycloalkyl; and
R4 is alkyl, cycloalkyl, fluoroalkyl, aryl or arylalkyl.

### Claim 4 (depends on 2)

The process according to claim 2, wherein the compound of formula (II) is obtained by the following scheme proceeding from a compound of formula (V) by reaction with potassium tert-butoxide:
where
R3 is alkyl, with the exception of ethyl, or cycloalkyl; and
R4 is alkyl, cycloalkyl, fluoroalkyl, aryl or arylalkyl.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the compound of formula (II) is obtained by the following scheme proceeding from malonic esters and chloroacetyl chloride:
where R2 is alkyl, aryl or arylalkyl.

### Claim 6

A process for preparing a compound of formula (V)
comprising reacting a compound of formula (IV)
with an alkyl chloro acetate of formula (VI)
where
R3 is alkyl, with the exception of ethyl, or cycloalkyl;
R4 is alkyl, cycloalkyl, fluoroalkyl, aryl or arylalkyl.

### Claim 7 (depends on 1)

The process according to claim 1, wherein A is
in which
X is halogen, alkyl or fluoroalkyl, and
Y is halogen, alkyl, fluoroalkyl, or fluoroalkoxy.

### Claim 8 (depends on 7)

The process according to claim 7, wherein A is
in which
X is halogen, alkyl or fluoroalkyl and
Y is halogen, alkyl, fluoroalkyl, fluoroalkoxy, azido or cyano.

### Claim 9 (depends on 1)

The process according to claim 1, wherein
R1 is hydrogen, alkyl, fluoroalkyl, alkenyl, fluoroalkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, fluorocycloalkyl, fluorocycloalkylalkyl, or alkoxyalkyl,
R2 is C1-C12-alkyl, C6-aryl, or aralkyl, and
Z is an alkali metal or hydrogen.

### Claim 10 (depends on 1)

The process according to claim 1, wherein
R1 is methyl, ethyl, propyl, vinyl, allyl, propargyl, cyclopropyl, alkoxyalkyl, 2 fluoroethyl, 2,2-difluoroethyl, or 2-fluorocyclopropyl, and
R2 is C1-C12-alkyl, and
Z is hydrogen, sodium, or potassium.

### Claim 11 (depends on 1)

The process according to claim 1, wherein
R1 is methyl, ethyl, n-propyl, n-prop-2-enyl, n-prop-2-ynyl, cyclopropyl, methoxyethyl, 2-fluoroethyl, or 2,2-difluoroethyl, and
R2 is methyl or ethyl, and
Z is sodium or hydrogen.

### Claim 12 (depends on 1)

The process according to claim 1, wherein
A is pyrid-2-yl, which is optionally 6-substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, or trifluoromethoxy.

### Claim 13 (depends on 1)

The process according to claim 1, wherein
A is pyrid-3-yl, which is optionally 6-substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, or trifluoromethoxy.

### Claim 14 (depends on 1)

The process according to claim 1, wherein
A is pyrid-4-yl, which is optionally 6-substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, or trifluoromethoxy.

### Claim 15 (depends on 2)

The process according to claim 2, wherein the base is alkoxide.

### Claim 16 (depends on 6)

The process according to claim 6, wherein the alkyl chloroacetate is ethyl chloroacetate.