Esters derived from (RR,SS)-2-hydroxybenzoate of 3-(2-dimethylaminomethyl-1-hydroxycyclohexyl)phenyl

1. Compound of general formula (I):

wherein: R 1 is halogen, optional substituted C 1 -C 6 alkyl, OR 3 , NO 2 or optionally substituted aryl, where R 3 is C 1 -C 4 alkyl, R 2 is: H or CH 3 CO; and the salts and optical isomers thereof.

2. A compound according to claim 1 , characterized in that R 1 is halogen, such as F, Cl, Br, halosubstituted phenyl or hydro (C 1 -C 6 fluoroalky).

3. Compound as claimed in claim 1 , characterized in that it is selected from one of the following:

(RR-SS)-2-Acetoxy-4-trifluoromethyl-benzoic acid 3-(2-dimethylaminomethyl-1-hydroxy-cyclohexyl)-phenyl ester;

(RR-SS)-2-Hydroxy-4-trifluoromethyl-benzoic acid 3-(2-dimethylaminomethyl-1-hydroxy-cyclohexyl)-phenyl ester;

(RR-SS)-4-Chloro-2-hydroxy-benzoic acid 3-(2-dimethylaminomethyl-1-hydroxy-cyclohexyl)-phenyl ester;

(RR-SS)-2-Hydroxy-4-methyl-benzoic acid 3-(2-dimethylaminomethyl-1-hydroxy-cyclohexyl)-phenyl ester;

(RR-SS)-2-Hydroxy-4-methoxy-benzoic acid 3-(2-dimethylaminomethyl-1-hydroxy-cyclohexyl)-phenyl ester;

(RR-SS)-2-Hydroxy-5-nitro-benzoic acid 3-(2-dimethylaminomethyl-1-hydroxy-cyclohexyl)-phenyl ester;

(RR-SS)-2′, 4-Difluoro-3-hydroxy-biphenyl-4-carboxylic acid 3-(2-dimethylaminomethyl-1-hydroxy-cyclohexyl)-phenyl ester.

4. A process for obtaining a compound of general formula (I):

as claimed in claim 1 , characterised in that a compound of formula (II);

is reacted with a compound of general formula (III);

wherein R 1 y R 2 have the same meaning as above, and L=OH, halogen

O—R 4 or —CO—R 5 , where R 4 =C 1 -C 4 alkyl, phenyl, optionally substituted phenyl, and R 5 =Alkyl, a phenyl ring optionally substituted with one or more substituents, or a heterocyclic ring optionally substituted with one or more substituents, in an inert solvent, at temperatures ranging from −20° C. to 120° C.

5. A process according to claim 4 , characterized in that a condensation promoting agent is added.

6. A process according to claim 4 , characterized in that said inert solvent is selected from dichloromethane, tetrahydrofuran, acetonitrile, 1,2-dichloroethane, ethyl acetate, dimethoxyethane or dioxane, preferably dichloromethane or tetrahydrofuran.

7. A process according to claim 5 , characterized in that said condensation promoting agent is selected from carbonyldiimidazole, dicyclohexylcarbodiimide, triethylamine ethylchloroformate, triethylamine benzotriazoletosylate or diethylchlorophosphate, preferably carbonyldiimidazole or dicyclohexylcarbodiimide.

8. A process according to claim 4 , characterized in that said temperature range is from 0° and 35° C.

9. A method for treatment of pain which comprises administering to a human being in need of said treatment an effective dose of a compound of general formula (I) according to claim 1 .

10. A pharmaceutical composition, which comprises a compound of general formula (I) according to claim 1 and a pharmaceutically acceptable excipient, for the treatment of pain.