Method for preparing di- or tricarboxylic esters by alkoxycarbonylation of dienes having conjugated double bonds

1. A method for preparing di- or tricarboxylic esters in a reaction mixture, comprising the method steps of:

a) initially charging a diene having two conjugated double bonds, wherein the diene is selected from compounds of the formula (II)

where R 7 , R 8 , R 9 , R 10 may each independently be selected from —H, —(C 1 -C 12 )-alkyl, or —(C 6 -C 20 )-aryl;

b) adding a phosphine ligand and a catalyst precursor selected from palladium dichloride, palladium dibromide, palladium diiodide, palladium(II) acetylacetonate, palladium(II) acetate, bis(dibenzylideneacetone)palladium, bis(acetonitrile)dichloropalladium(II), or palladium (cinnamyl) dichloride;

c) adding an alcohol;

d) feeding in CO;

e) heating the reaction mixture, with conversion of the diene to a di- or tricarboxylic ester;

wherein the phosphine ligand is a compound according to formula (I)

where

R 1 , R 2 , R 3 , R 4 are selected from —(C 1 -C 12 )-alkyl, —(C 6 -C 20 )-aryl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl, or —(C 3 -C 20 )-heteroaryl;

R 5 , R 6 are selected from —H, —(C 1 -C 12 )-alkyl, —(C 6 -C 20 )-aryl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl, or —(C 3 -C 20 )-heteroaryl;

and R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , in the case that these are —(C 1 -C 12 )-alkyl, —(C 6 -C 20 )-aryl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl or —(C 3 -C 20 )-heteroaryl, may be each substituted independently of one another by one or more substituents selected from —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl, —O—(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl-(C 6 -C 20 )-aryl, —O—(C 3 -C 12 )-cycloalkyl, —S—(C 1 -C 12 )-alkyl, —S—(C 3 -C 12 )-cycloalkyl, —COO—(C 1 -C 12 )-alkyl, —COO—(C 3 -C 12 )-cycloalkyl, —CONH—(C 1 -C 12 )-alkyl, —CONH—(C 3 -C 12 )-cycloalkyl, —CO—(C 1 -C 12 )-alkyl, —CO—(C 3 -C 12 )-cycloalkyl, —N—[(C 1 -C 12 )-alkyl] 2 , —(C 6 -C 20 )-aryl, —(C 6 -C 20 )-aryl-(C 1 -C 12 )-alkyl, —(C 6 -C 20 )-aryl-O—(C 1 -C 12 )-alkyl, —(C 3 -C 20 )-heteroaryl, —(C 3 -C 20 )-heteroaryl-(C 1 -C 12 )-alkyl, —(C 3 -C 20 )-heteroaryl-O—(C 1 -C 12 )-alkyl, —COOH, —OH, —SO 3 H, —NH 2 , or halogen, and

wherein steps a), b), c), and d) may be effected in any sequence.

2. The method according to claim 1 ,

where R 1 , R 2 , R 3 , R 4 are selected from —(C 1 -C 12 )-alkyl, —(C 6 -C 20 )-aryl, or (C 3 -C 20 )-heteroaryl.

3. The method according to claim 1 ,

where R 5 , R 6 are selected from —H or —(C 1 -C 12 )-alkyl.

4. The method according to claim 1 ,

where R 1 , R 2 , R 3 , R 4 are each —(C 6 -C 20 )-aryl and R 5 , R 6 are each selected from —H or —(C 1 -C 12 )-alkyl.

5. The method according to claim 1 ,

wherein the diene has 4 to 30 carbon atoms.

6. The method according to claim 1 ,

wherein the catalyst precursor is selected from palladium dichloride, palladium dibromide, palladium diiodide, palladium(II) acetylacetonate, palladium(II) acetate, or bis(dibenzylideneacetone)palladium.

7. The method according to claim 1 ,

wherein the catalyst precursor is selected from palladium dichloride, palladium dibromide, or palladium diiodide.

8. The method according to claim 1 ,

wherein the alcohol in method step c) has 1 to 12 carbon atoms.

9. The method according to claim 1 ,

wherein the alcohol in method step c) is selected from methanol, ethanol, 1-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, cyclohexanol, 2-ethylhexanol, isononanol, 2-propylheptanol, benzyl alcohol, 1-phenylethanol or 2-phenylethanol.

10. The method according to claim 1 ,

wherein the alcohol in method step c) is selected from methanol, ethanol, isopropanol, n-butanol or 2-phenylethanol.

11. The method of claim 1 , wherein R 7 , R 8 , R 9 , R 10 may each independently be selected from —H, —(C 1 -C 6 )-alkyl, or phenyl.