A method for preparing 3-methyl-2-nitrobenzoic acid is disclosed wherein 1,3-dimethyl-2-nitrobenzene is combined with an oxidation catalayst in the presence of an oxygen source and an initiator, provided that less than 99% of the 1,3-dimethyl-2-nitrobenzene is oxidized. A method for preparing compounds of Formula 7 and Formula 11 is also disclosed wherein the method is characterized by using 3-methyl-2-nitrobenzoic acid as prepared by the method disclosed above ##STR00001## wherein R.sup.1 is C.sub.1-C.sub.7 alkyl, C.sub.3-C.sub.6 cycloalkyl or C.sub.4-C.sub.7 alkylcycloalkyl.

A process for preparing 2-alkyl-4-trifluoromethyl-3-alkylsulfonylbenzoic acids of the formula (I) is described.

##STR00001##

Here, the substituents are radicals such as alkyl and substituted phenyl.

A process for preparing 2-alkyl-4-trifluoromethyl-3-alkylsulfonylbenzoic acids of the formula (I) is described.

##STR00001##

Here, the substituents are radicals such as alkyl and substituted phenyl.

A process for preparing 2-alkyl-4-trifluoromethyl-3-alkylsulfonylbenzoic acids of the formula (I) is described.

##STR00001##

Here, the substituents are radicals such as alkyl and substituted phenyl.

The present invention provides a process for the preparation of Teriflunomide (Formula-I). The present invention describes the synthesis of Teriflunomide without isolating the intermediate Leflunomide. Teriflunomide is prepared from 5-Methyl isoxazole-4-carboxylic acid by converting to its acid chloride and coupling with 4-trifluoromethyl aniline to obtain Leflunomide (which is not isolated) followed by ring opening reaction using aq. Sodium Hydroxide to form Teriflunomide. In other words, the process is telescoped from 5-methylisoxazole-4-carbonyl chloride.

##STR00001##

The present invention provides a process for the preparation of Teriflunomide (Formula-I). The present invention describes the synthesis of Teriflunomide without isolating the intermediate Leflunomide. Teriflunomide is prepared from 5-Methyl isoxazole-4-carboxylic acid by converting to its acid chloride and coupling with 4-trifluoromethyl aniline to obtain Leflunomide (which is not isolated) followed by ring opening reaction using aq. Sodium Hydroxide to form Teriflunomide. In other words, the process is telescoped from 5-methylisoxazole-4-carbonyl chloride.

##STR00001##

A method for preparing 3-methyl-2-nitrobenzoic acid is disclosed wherein 1,3-dimethyl-2-nitrobenzene is combined with an oxidation catalayst in the presence of an oxygen source and an initiator, provided that less than 99% of the 1,3-dimethyl-2-nitrobenzene is oxidized.

A method for preparing compounds of Formula 7 and Formula 11 is also disclosed wherein the method is characterized by using 3-methyl-2-nitrobenzoic acid as prepared by the method disclosed above.

##STR00001##

wherein R.sup.1 is C.sub.1-C.sub.7 alkyl, C.sub.3-C.sub.6 cycloalkyl or C.sub.4-C.sub.7 alkylcycloalkyl

A method for preparing 3-methyl-2-nitrobenzoic acid is disclosed wherein 1,3-dimethyl-2-nitrobenzene is combined with an oxidation catalayst in the presence of an oxygen source and an initiator, provided that less than 99% of the 1,3-dimethyl-2-nitrobenzene is oxidized.

A method for preparing compounds of Formula 7 and Formula 11 is also disclosed wherein the method is characterized by using 3-methyl-2-nitrobenzoic acid as prepared by the method disclosed above.

##STR00001##

wherein R.sup.1 is C.sub.1-C.sub.7 alkyl, C.sub.3-C.sub.6 cycloalkyl or C.sub.4-C.sub.7 alkylcycloalkyl

A method for preparing 3-methyl-2-nitrobenzoic acid is disclosed wherein 1,3-dimethyl-2-nitrobenzene is combined with an oxidation catalyst in the presence of an oxygen source and an initiator, provided that less than 99% of the 1,3-dimethyl-2-nitrobenzene is oxidized. A method for preparing compounds of Formula 7 and Formula 11 is also disclosed wherein the method is characterized by using 3-methyl-2-nitrobenzoic acid as prepared by the method disclosed above. ##STR00001## wherein R.sup.1 is C.sub.1-C.sub.7 alkyl, C.sub.3-C.sub.6 cycloalkyl or C.sub.4-C.sub.7 alkylcycloalkyl.

A method for preparing 3-methyl-2-nitrobenzoic acid is disclosed wherein 1,3-dimethyl-2-nitrobenzene is combined with an oxidation catalyst in the presence of an oxygen source and an initiator, provided that less than 99% of the 1,3-dimethyl-2-nitrobenzene is oxidized. A method for preparing compounds of Formula 7 and Formula 11 is also disclosed wherein the method is characterized by using 3-methyl-2-nitrobenzoic acid as prepared by the method disclosed above. ##STR00001## wherein R.sup.1 is C.sub.1-C.sub.7 alkyl, C.sub.3-C.sub.6 cycloalkyl or C.sub.4-C.sub.7 alkylcycloalkyl.