Process for the alkoxycarbonylation of ethers

1. A process for preparing an ester from an ether having 3 to 30 carbon atoms comprising the following process steps:

a) introducing the ether having 3 to 30 carbon atoms, forming a reaction mixture;

b) adding a phosphine ligand and a compound which comprises Pd, or adding a complex comprising Pd and a phosphine ligand;

c) adding an alcohol;

d) supplying CO;

e) heating the reaction mixture, the ether being reacted to form an ester from the ether, CO and alcohol;

where the phosphine ligand is a compound of formula (I)

where

m and n are each independently 0 or 1;

R 1 , R 2 , R 3 , R 4 are each independently selected from the groups consisting of —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl, —(C 6 -C 20 )-aryl, and —(C 3 -C 20 )-heteroaryl; where

at least one of the R 1 , R 2 , R 3 , R 4 radicals is a —(C 3 -C 20 )-heteroaryl radical; and

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

may each independently be substituted by one or more substituents selected from the group consisting of —(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 , and halogen; wherein the ether in process step a) is a compound of formula (IV)

where R 5 is selected from the group consisting of —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, and (C 6 -C 20 )-aryl;

R 6 and R 7 each independently are selected from the group consisting of —H, —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, and —(C 6 -C 20 )-aryl;

and R 8 is selected from the group consisting of —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, and —(C 6 -C 20 )-aryl.

2. The process according to claim 1 ,

where the phosphine ligand is a compound of one of the formulae (II) and (III)

3. The process according to claim 1 ,

where at least two of the R 1 , R 2 , R 3 , R 4 radicals are a —(C 3 -C 20 )-heteroaryl radical.

4. The process according to claim 1 ,

where the R 1 and R 3 radicals are each a —(C 3 -C 20 )-heteroaryl radical.

5. The process according to claim 1 ,

where the R 1 and R 3 radicals are each a —(C 3 -C 20 )-heteroaryl radical;

and R 2 and R 4 are each independently selected from the group consisting of —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl, and —(C 6 -C 20 )-aryl.

6. The process according to claim 1 ,

where the R 1 and R 3 radicals are each a —(C 3 -C 20 )-heteroaryl radical;

and R 2 and R 4 are each independently selected from —(C 1 -C 12 )-alkyl.

7. The process according to claim 1 ,

where R 1 , R 2 , R 3 , R 4 , if they are a heteroaryl radical, are each independently selected from the group consisting of furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, furazanyl, tetrazolyl, pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, benzofuranyl, indolyl, isoindolyl, benzimidazolyl, quinolyl, and isoquinolyl.

8. The process according to claim 1 ,

where the phosphine ligand is a compound of formula (1)

9. The process according to claim 1 ,

where R 5 and R 8 are each —(C 1 -C 12 )-alkyl.

10. The process according to claim 1 ,

where R 6 and R 7 each independently are selected from the group consisting of —H, —(C 1 -C 12 )-alkyl, and —(C 6 -C 20 )-aryl.

11. The process according to claim 1 ,

where not more than one of the radicals R 6 and R 7 is —H.

12. The process according to claim 1 ,

wherein the compound comprising Pd in process step b) is selected from the group consisting of palladium dichloride, palladium(II) acetylacetonate, palladium(II) acetate, dichloro(1,5-cyclooctadiene)palladium(II), bis(dibenzylideneacetone)palladium, bis(acetonitrile)dichloropalladium(II), and palladium(cinnamyl) dichloride.

13. The process according to claim 1 ,

wherein the alcohol in process step c) is selected from the group consisting of methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, tert-butanol, 3-pentanol, cyclohexanol, and mixtures thereof.

14. The process according to claim 1 ,

wherein the alcohol in process step c) is selected from methanol or ethanol.