Process for preparing substituted indole derivatives

1. A process for preparing an indole derivative of the formula (IV) without the use of dimethylsulfide, said process comprising reacting an indole-derivative with a C—H-group in the 2-position of the formula (I) with a nucleophilic compound R N —H of the formula (II) in a solvent and with oxygen in the presence of at least one catalyst:

wherein R 1 represents four substituents R 1a , R 1b , R 1c and R 1d on the aromatic ring which substituents may be the same of different and may be selected each from hydrogen, heterosubstituents, C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally including hetero atoms and/or optionally having one or more unsaturated, C 3 -C 8 -heterocycloalkyl or C 6 to C 20 aromatic hydrocarbon or partially arene-hydrogenated forms, each heterosubstituent or hydrocarbon optionally being substituted by one or more groups selected from C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally including hetero atoms and/or optionally having one or more unsaturated bonds, or C 6 to C 20 aromatic hydrocarbon or partially arene-hydrogenated forms or heterosubstituents, or

at least two of said R 1a , R 1b , R 1c and R 1d substituents may also form an aliphatic or heteroaliphatic ring structure having 4 to 10 ring atoms optionally including unsaturated bond(s), an aromatic or heteroaromatic ring structure having 4 to 10 ring atoms, each ring structure optionally being substituted by one or more substituents selected from heterosubstituents, C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds, C 3 -C 8 -heterocycloalkyl or C 6 to C 20 aromatic hydrocarbon, each hydrocarbon optionally being substituted by one or more heterosubstituents;

R 2 and R 3 may be the same or different and may be selected each from hydrogen, C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally including hetero atoms and/or optionally having one or more unsaturated bonds, C 3 -C 8 -heterocycloalkyl or C 6 to C 20 aromatic hydrocarbon or partially arene-hydrogenated forms, each hydrocarbon optionally being substituted by one or more groups selected from C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds, or C 6 to C 20 aromatic hydrocarbon or partially arene-hydrogenated forms or heterosubstituents, and may also form a ring system between two or more R 1 substituents, or

R 2 and R 3 may form an aliphatic or heteroaliphatic ring structure having 4 to 8 carbon atoms, said ring structure optionally being substituted by one or more substituents selected from heterosubstituents, C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds, C 3 -C 8 -heterocycloalkyl or C 6 to C 20 aromatic hydrocarbon, each hydrocarbon optionally being substituted by one or more heterosubstituents;

R 4 may be selected from hydrogen, C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally including hetero atoms and/or optionally having one or more unsaturated bonds, C 3 -C 8 -heterocycloalkyl or C 6 to C 20 aromatic hydrocarbon or partially arene-hydrogenated forms, each hydrocarbon optionally being substituted by one or more groups selected from C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds, or C 6 to C 20 aromatic hydrocarbon and partially arene-hydrogenated forms or heterosubstituents;

R N is a nucleophilic group selected from —OR 5 , —NR 5 R 6 or —CR 5 R 6 R 7 ,

wherein R 5 , R 6 and R 7 may be the same or different and may be selected each from hydrogen, C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds, C 3 -C 8 -heterocycloalkyl or C 6 to C 20 aromatic hydrocarbon and partially arene-hydrogenated forms, each hydrocarbon optionally being substituted by one or more groups selected from C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds, or C 6 to C 20 aromatic hydrocarbon or partially arene-hydrogenated forms or heterosubstituents, wherein at least one of R 5 , R 6 and R 7 bears a heteroatom if R N is —CR 5 R 6 R 7 , or

at least two of R 5 , R 6 and R 7 may form an aliphatic or saturated heteroaliphatic ring structure having 3 to 10 ring atoms and including unsaturated bond(s), an aromatic or heteroaromatic ring structure having 4 to 10 ring atoms, each rings structure optionally being substituted by one or more substituents selected from heterosubstituents, C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds, C 3 -C 8 -heterocycloalkyl or C 6 to C 20 aromatic hydrocarbon, each hydrocarbon optionally being substituted by one or more heterosubstituents,

wherein the process is conducted without the use of dimethylsulfide.

2. Process according to claim 1 , wherein the catalyst is a photosensitizer and the reaction is carried under irradiation with light.

3. Process according to claim 2 , wherein compound (I) is converted, under the action of oxygen and irradiation with light in the presence of a photosensitizer, into the hydroperoxide compound of the formula (III) which is further reacted with the nucleophilic compound R N —H of the formula (II) to yield compound (IV):

4. Process according to claim 2 , wherein the photosensitzer is selected from Rose Bengal, Trisbipyridyldichlororuthenium-hexahydrate, 9,10-Bis(Cyanoanthracene), Meso-Tetraphenylporphyrin, Phthalocyanine, Zinc Phthalocyanine, Copper Phthalocyanine, Iron Phthalocyanine, or Methylene Blue.

5. Process according to claim 1 , wherein the reaction is carried out in the presence of a Lewis acid or Brønsted acid as catalyst.

6. Process according to claim 1 , wherein said C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons are independently selected from the group consisting of C 1 -C 20 -alkyl, C 2 -C 20 -alkenyl and C 2 -C 20 -alkinyl.

7. Process according to claim 1 , wherein said C 6 to C 20 aromatic hydrocarbon and partially arene-hydrogenated forms are independently selected from the group consisting of aryl, aryl-(C 1 -C 6 )-alkyl and heteroaryl-(C 1 -C 6 )-alkyl.

8. Process according to claim 1 , wherein said heterosubstituents are independently selected from the group consisting of ═O, OH, F, Cl, Br, I, CN, NO 2 , SO 3 H, a monohalogenomethyl group, a dihalogenomethyl group, a trihalogenomethyl group, CF(CF3) 2 , SF 5 , amine bound through N atom, —O-alkyl (alkoxy) and —O-aryl.