Process comprising the following process steps: a) introducing a first alcohol, the first alcohol having 2 to 30 carbon atoms; b) adding a phosphine ligand and a compound which comprises Pd, or adding a complex comprising Pd and a phosphine ligand; c) adding a second alcohol; d) supplying CO; e) heating the reaction mixture, the first alcohol reacting with CO and the second alcohol to form an ester; where the phosphine ligand is a compound of formula where m and n are each independently 0 or 1; R 1, R 2, R 3, R 4 are each independently selected from -(C 1- C 12)-alkyl, -(C 3 -C 12)-cycloalkyl, -(C 3 -C 12)-heterocycloalkyl, -(C 6 -C 20)-aryl, -(C 3 -C 20)-heteroaryl; 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 -(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, halogen, and where the first alcohol in process step a) is a secondary or tertiary alcohol and the second alcohol in process step c) is a primary alcohol, where the expression (C 3 -C 12)-heterocycloalkyl encompasses nonaromatic, saturated or partly unsaturated cycloaliphatic groups having 3 to 12 carbon atoms, where one or more of the ring carbon atoms are replaced by heteroatoms. a) introducing a first alcohol, the first alcohol having 2 to 30 carbon atoms; b) adding a phosphine ligand and a compound which comprises Pd, or adding a complex comprising Pd and a phosphine ligand; c) adding a second alcohol; d) supplying CO; e) heating the reaction mixture, the first alcohol reacting with CO and the second alcohol to form an ester; m and n are each independently 0 or 1; R 1, R 2, R 3, R 4 are each independently selected from -(C 1- C 12)-alkyl, -(C 3 -C 12)-cycloalkyl, -(C 3 -C 12)-heterocycloalkyl, -(C 6 -C 20)-aryl, -(C 3 -C 20)-heteroaryl; 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 -(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, halogen, and where the first alcohol in process step a) is a secondary or tertiary alcohol and the second alcohol in process step c) is a primary alcohol, where the expression (C 3 -C 12)-heterocycloalkyl encompasses nonaromatic, saturated or partly unsaturated cycloaliphatic groups having 3 to 12 carbon atoms, where one or more of the ring carbon atoms are replaced by heteroatoms.