Process for the preparation of Roflumilast

1. A process for the preparation of Roflumilast comprising the steps of:

a) reacting 4-Difluoromethoxy-3-hydroxy benzaldehyde of Formula II with a cyclopropylmethyl compound of Formula III in the presence of an organic base to obtain 3-cyclopropylmethoxy-4-Difluoromethoxy benzaldehyde of Formula IV

wherein X is a leaving group,

b) oxidising the obtained aldehyde compound of Formula IV into 3-cyclopropylmethoxy-4-Difluoromethoxy benzoic acid of Formula V,

c) converting 3-cyclopropylmethoxy-4-Difluoromethoxy benzoic acid of Formula V to its acid halide and condensing with 4-amino 3,5-Dichloropyridine in the presence of base to obtain Roflumilast, and

d) optionally purifying Roflumilast in an organic solvent to get pure Roflumilast.

2. The process according to claim 1 , wherein the organic base used in the step-a is 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU).

3. The process according to claim 1 , wherein the leaving group in step-a is selected from the group consisting of a halogen, alkylsulfonyloxy, and arylsulfonyloxy.

4. The process according to claim 1 , wherein the oxidation in step-b is carried out in the presence of sulfamic acid and sodium chlorite.

5. The process according to claim 1 , wherein the base used in the step-c is selected from the group consisting of alkali metal hydrides and alkali metal carbonates.

6. The process according to claim 5 , wherein the base is selected from the group consisting of sodium hydride and potassium hydride.

7. The process according to claim 1 , wherein the acid halide in step-c is produced using a halogenating agent and wherein the halogenating agent is thionyl chloride.

8. The process according to claim 1 , wherein the organic solvent used in step-d for the purification of Roflumilast is selected from alcoholic solvents.

9. The process according to claim 8 , wherein the alcoholic solvent is selected from the group consisting of methanol, ethanol, isopropanol, and mixtures thereof.