# US 5,708,180 A · Process for the preparation of 2-halogenopyridinealdehydes and novel 2-halogenopyridinealdehydes

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- Number: US 5,708,180 A
- Document ID: US5708180A
- Status: Granted
- Kind: A
- Application number: 08/758,625
- Filed: 1996-11-27
- Granted: 1998-01-13
- Earliest claimed: 1994-08-19
- Assignees: Bayer Aktiengesellschaft
- Inventors: Gunther Beck; Helmut Heitzer
- Web page: https://patentgrep.com/patent/US5708180A

## CPC

- C07D 213/80: in position 3
- C07D 213/61: Halogen atoms or nitro radicals
- C07D 213/65: attached in position 3 or 5
- C07D 213/82: in position 3
- C07D 213/84: Nitriles
- C07D 213/85: in position 3
- C07D 409/04: directly linked by a ring-member-to-ring-member bond
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

The reaction of cyanoolefins, aminocarbonylolefins or hydroxyiminoolefins with a Vilsmeier reagent leads to 2-halogenopyridines which bear aldehyde groups in the 3 and/or 5 position. These pyridinealdehydes are valuable intermediates for the preparation of pharmaceuticals and crop protection agents.

## Claims

### Claim 1

A process for the preparation of a compound of the formula ##STR51## in which X denotes chlorine or bromine,
Q denotes hydrogen, halogen, C.sub.1 -C.sub.8 -alkyl, cyano-C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.4 -alkoxy-C.sub.1 -C.sub.8 -alkyl, C.sub.3 -C.sub.10 -cycloalkyl, C.sub.6 -C.sub.12 -aralkyl, C.sub.6 -C.sub.12 -aryl, hetaryl having 5 to 7 ring members and 1 to 3 hetero atoms selected from the group consisting of N, O, or S,
R.sup.1, R.sup.2 denote formyl, cyano, hydroxyl, halogen, C.sub.1 -C.sub.8 -alkyl, halogeno-C.sub.1 -C.sub.8 -alkyl, cyano-C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.4 -alkoxy-C.sub.1 -C.sub.8 alkyl, C.sub.3 -C.sub.10 -cycloalkyl, ##STR52## C.sub.6 -C.sub.12 aralkyl, C.sub.6 -C.sub.12 -aryl, C.sub.6 -C.sub.12 -aryloxy, hetaryl having 5 to 7 ring members and 1 to 3 hetero atoms selected from the group consisting of N, O, or S, hetaryloxy having 5 to 7 ring members and 1 to 3 hetero atoms selected from the group consisting of N, O, or S in the hetaryl moiety,
with the restriction that at least one of the two substituents R.sup.1 and R.sup.2 represents formyl,
R denotes halogen, C.sub.1 -C.sub.4 -alkoxy, phenoxy, --NR'R" and
R', R" denote, independently of cacti other, C.sub.1 -C.sub.4 -alkyl or both substituents together denote C.sub.4 -C.sub.6 -alkylene which can be interrupted by an oxygen atom, which comprises reacting a compound of the formula ##STR53## in which the dashed line indicates the two possible positions of a C.dbd.C bond,
Q' can assume the meanings defined for Q or denotes hydroxyl or C.sub.1 -C.sub.4 -alkoxy,
P denotes --CN, --CONH.sub.2 or --CH.dbd.NOH and
R.sup.1', R.sup.2' denote, independently of each other, hydrogen, cyano, halogen, --CONH.sub.2, C.sub.1 -C.sub.8 -alkyl, halogeno-C.sub.1 -C.sub.8 -alkyl, cyano-C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.4 -alkoxy-C.sub.1 -C.sub.8 -alkyl, hydroxy-C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.8 -alkoxy, C.sub.3 -C.sub.10 -cycloakyl, ##STR54## carboxyl, C.sub.1 -C.sub.8 -acyloxy, C.sub.6 -C.sub.12 -aralkyl, C.sub.6 -C.sub.12 -aryl, C.sub.6 -C.sub.12 -aryloxy, hetaryl having 5 to 7 ring members and 1 to 3 hetero atoms selected from the group consisting of N, O, or S, hetaryloxy having 5 to 7 ring members and 1 to 3 hetero atoms selected from the group consisting of N, O, or S in the hetaryl moiety with the restriction that at least one of the two substituents R.sup.1' and R.sup.2' represents hydrogen and
R has the meaning specified in formula (I)
with a Vilsmeier reagent wherein when R.sup.1' or R.sup.2' is hydrogen and P is CN at least 2 mols of the Vilsmeier reagent are used per mol of compound (II) and when R.sup.1' or R.sup.2' are hydrogen and P is CN, and at least 3 mols of Vilsmeier reagent per mol of compound (II) are employed.

### Claim 2 (depends on 1)

The process according to claim 1, wherein Q is hydrogen, halogen, C.sub.6 -C.sub.12 -aryl or hetaryl having 5 to 7 ring members and 1 to 3 heteroatoms selected from the group consisting of N, O or S.

### Claim 3 (depends on 1)

The process according to claim 1 wherein the Vilsmeier reagent is produced from the reaction of a N-formylamide with an acid halide and the N-formylamide is selected from the group consisting of dimethylformamide, N-methylformanilide, N-formylpiperidine, N-formylmorpholine and the acid halide is selected from the group consisting of phosphorus oxychloride, phosphorus oxybromide, phosgene, thionyl chloride, oxalyl chloride.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the reaction temperature is 0.degree. to 180.degree. C.

### Claim 5

A compound of the formula ##STR55## in which R.sup.1 represents hydroxy, methyl, phenyl, and chlorocarbonyl.

### Claim 6

A compound of the formula ##STR56## in which Q represents chlorine or phenyl.

### Claim 7

A compound of the formula ##STR57## in which R.sup.1 represents cyano or phenyl.