A process for the preparation of Formula IIa comprising the steps of: wherein, R' is phenyl or substituted phenyl group (i) N-acylation of 3-Amino-4-methyl pyridine of Formula III with alkyl, aryl or substituted aryl acid chloride or acid anhydride to prepare a compound of Formula IVa and optionally isolating it; wherein R is selected from hydrogen, alkyl, aryl or substituted aryl, (ii) quaternization of Nitrogen of Pyridine system in the compound of Formula IVa, using benzyl or substituted benzyl halide in an organic solvent to prepare a compound of Formula Va and optionally isolating it; wherein R and R' are as defined above; and X represents a halide selected from chloro, bromo, iodo, or a leaving group selected from tosyloxy or mesyloxy, (iii) partial reduction of the compound of Formula Va to produce 1,2,5,6-Tetrahydropyridine system of Formula VIa in presence of a reducing agent in a organic solvent, at an ambient temperature; wherein R and R' are as defined above, (iv) hydrolysis of 1,2,5,6-Tetrahydropyridine system of Formula VIa in presence of an acid or mixture of acids to prepare a compound of the Formula VIIa at an ambient temperature; wherein R' is as defined above, (v) reductive amination of the compound of Formula VIIa using Methylamine in presence of a Lewis acids in an organic solvent or an aqueous solvent or mixture(s) thereof followed by reduction using a reducing agent to prepare a compound of Formula VIIIa at an ambient temperature; and wherein R' is as defined above, (vi) resolution of a compound of formula VIIIa in presence of a resoluting agent in an organic solvent or an aqueous solvent or mixture(s) thereof to prepare the compound of Formula IIa. (i) N-acylation of 3-Amino-4-methyl pyridine of Formula III with alkyl, aryl or substituted aryl acid chloride or acid anhydride to prepare a compound of Formula IVa and optionally isolating it; wherein R is selected from hydrogen, alkyl, aryl or substituted aryl, (ii) quaternization of Nitrogen of Pyridine system in the compound of Formula IVa, using benzyl or substituted benzyl halide in an organic solvent to prepare a compound of Formula Va and optionally isolating it; wherein R and R' are as defined above; and X represents a halide selected from chloro, bromo, iodo, or a leaving group selected from tosyloxy or mesyloxy, (iii) partial reduction of the compound of Formula Va to produce 1,2,5,6-Tetrahydropyridine system of Formula VIa in presence of a reducing agent in a organic solvent, at an ambient temperature; wherein R and R' are as defined above, (iv) hydrolysis of 1,2,5,6-Tetrahydropyridine system of Formula VIa in presence of an acid or mixture of acids to prepare a compound of the Formula VIIa at an ambient temperature; wherein R' is as defined above, (v) reductive amination of the compound of Formula VIIa using Methylamine in presence of a Lewis acids in an organic solvent or an aqueous solvent or mixture(s) thereof followed by reduction using a reducing agent to prepare a compound of Formula VIIIa at an ambient temperature; and wherein R' is as defined above, (vi) resolution of a compound of formula VIIIa in presence of a resoluting agent in an organic solvent or an aqueous solvent or mixture(s) thereof to prepare the compound of Formula IIa.